Souvenir

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Message from Chairman, ISRS 2008

Dated: 2-12-2008

The ISRS 2008 being held between 10th

and 12th

December 2008, in Chennai is a well

established conference for research scholars working in the broad areas of the science,

engineering, and technology and is recognized as such by the fraternity associated with Materials

Science and Technology. This conference brings together research scholars from around the

world and offers a great opportunity for the participants to learn from each other’s experience.

Thanks to the efforts of the organizers, ISRS 2008 will provide a platform for showcasing some

of the latest advancements in the field of Materials Science and Technology.

This year’s conference is of special significance being the golden jubilee year of IIT Madras and

that of the Department of Metallurgical and Materials Engineering. I am happy to note that the

institute has recognised this event as one of the Golden Jubilee Events. I am convinced that this

effort by the organizers will greatly assist young researchers for enhanced mutual engagement

and interaction, both social and professional. Such interactions are essential in the modern

context where compartmentalization has proven to be counterproductive and even detrimental to

the overall scientific and technological progress. I am sure with such wide participation and keen

enthusiasm this symposium will turn out to be a memorable one.

I am also particularly happy to note that the organisers have taken care to invite eminent plenary

speakers engaged in different aspects of the broad theme of the conference. Undoubtedly it will

be of great benefit to the participants and will strengthen their understanding of Materials

Science and Technology.

I congratulate the organizers of ISRS 2008 for the enthusiasm with which they have gone about

organizing this conference and wish the conference all success.

(Dr. P.K. Nair)

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ISRS 2008 Patrons

Prof. M S Ananth, Director, IIT Madras Dr. Baldev Raj, Director, IGCAR Shri B Muthuraman, Managing Director, TATA Steel Shri M M Murugappan, Chairman, Carborundum Universal Ltd

ISRS 2008 International Advisory Committee Prof. K Krishnaiah, IITM Prof. S Santhakumar, IITM Prof. V G Idichandy, IITM Prof. T T Narendran, IITM Prof. M Singaperumal, IITM Prof. R Ramamurthi, IITM Prof. P Kesavan Nair, IITM Prof. N Chakraborti, IIT Kharagpur Prof. S K Nath, IIT Roorkee Prof. Rajiv O Dusane, IIT Bombay Prof. R Shekhar, IIT Kanpur Prof. K Chattopadhyay, IISc Bangalore Prof. S B Abdullah, Universiti Teknologi MARA, Malaysia Prof. William A. Baeslack III, Ohio State University, USA Dr. D Banerjee, DRDO Dr. S Banerjee, BARC Dr. S Best, University of Cambridge Dr. K Bhanu Sankara Rao, IGCAR, Kalpakkam Dr. D Bhattacharjee, TATA Steel, Jamshedpur Prof. R K Bordia, University of Washington, USA Prof. T Chandra, University of Wollongong, Australia Prof. C Dong, Dallan University of Technology, China Prof. H Hahn, INT, FZK, Germany Prof. K Hono, NIMS Japan Prof. H S Kim, Chungnam National University, S. Korea Prof. D H Kim, University of Yonsel, S. Korea Prof. H G Lee, POSTECH, S. Korea Prof. C G Levi, UCSB Dr. G Malakondaiah, DMRL, Hyderabad Prof. B Matovic VINS, Serbia Prof. S P Mehrotra, NML, Jamshedpur Dr. J Mukhopadhyay, JNARDDC, Nagpur �������������� �������������������������� �

Prof. K L Murty, NC State University, USA Dr. J Narayana Das, NMRL, Ambarnath Prof. K A Padmanabhan, Anna University, Chennai Prof. S Ramakrishna, NUS, Singapore Prof. S Ranganathan, IISc Bangalore Prof. C Ravi Ravindran, Ryerson University, Canada Prof. P Rodriguez, IITM Prof. Schneider, Technical University of Darmstadt, Germany Dr. G Sundararajan, ARCI, Hyderabad Prof. S Suresh, MIT, USA Dr. T Webster, Brown University, USA Prof. P Wollants, Catholic University, Belgium Prof. Y Zeng, Shangai Institute of Ceramics, China

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ISRS 2008 Local Organising Committee

ChairpersonProf. P Kesavan Nair, Head, Dept. of MME, IITM ConvenerDr. Prathap Haridoss, MME, IITM Co-ConvenerDr. Uday Chakkingal, MME, IITM TreasurerDr. K C Hari Kumar, MME, IITM SecretariesMr. R Vijay, MME, IITM Mr. P Gerald Tennyson, MME, IITMMembersProf. D R G Achar, IITM Prof. B Guha, IITM Prof. B S Murty, IITM Prof. Paramanand Singh, IITM Prof. S D Pathak, IITM Prof. K Prasad Rao, IITM Prof. T S Prasanna Kumar, IITM Prof. S Raghavan, IITM Prof. P Rodriguez, IITM Prof. S K Seshadri, IITM Prof. P Venugopal, IITM Dr. M Balasubramanian, IITM Dr. S S Bhattacharya, IITM Dr. S Ganesh Sundara Raman, IITM Dr. M Kamaraj, IITM Dr. V Sampath, IITM Dr. T S Sampath Kumar, IITM Dr. Ashutosh S Gandhi, IITM Dr. G Phanikumar, IITM Dr. Ranjit Bauri, IITM Dr. N V Ravi Kumar, IITM Dr. Ravi Shankar Kottada, IITM Dr. S Sankaran, IITM Dr. V Subramanya Sarma, IITM Mr. Devinder Yadav, IITM Ms. P Susila, IITM Ms. R Sangeetha, IITM Mr. Manjith, IITM Mr. Ganesh Niranjan, IITM Mr. N R Rajasekaran, IITM Mr. T V K Kidao, MMSPL, Chennai Dr. R Mahadevan, India Pistons, Chennai Dr. T V L Narasimha Rao, Sundaram Clayton, Chennai Mr. R Natarajan, TII Group, Chennai Mr. V Parthasarathy, Wave Current Automotive. Chennai Mr. N Sampath Kumar, Ambattur Metal Treators, Chennai Dr. P Sivaprasad, IGCAR, Kalpakkam Dr. S Srikanth, NML, Chennai Mr. B K Venkatesh, Techmat Enterprises, Chennai Dr. S Venugopal, IGCAR, Kalpakkam

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About the Organizing Bodies

Department of Metallurgical and Materials Engineering

The Department of Metallurgical Engineering was established in 1959. President of India in his capacity as the Visitor of IIT Madras approved the change of name of the Department of Metallurgical Engineering as Department of Metallurgical & Materials Engineering with effect from 12th March 2003. The Department offers B.Tech., Dual Degree, M.Tech., M.S. and Ph.D. programmes. The Department has excellent research infrastructure in the broad areas of materials processing (forming, joining, casting, particulate processing, nanostructured materials), characterisation (X-ray diffraction, electron microscopy, thermal analysis, scanning probe microscopy), mechanical testing, environmental degradation, surface engineering, and computational materials science.

The Department has 29 faculty members: 10 Professors, 8 Associate Professors and 9 Assistant Professors. In addition, one Emeritus Professor and one Distinguished Visiting Faculty Member are also hosted by the Department.

Contact Details Department of Metallurgical and Materials Engineering Indian Institute of Technology Madras Chennai - 600 036 INDIAPhone: +91 44 2257-4750 (Office) Phone: +91 44 2257-4751 (HoD) Fax: +91 44 2257-4752 (Dept.) Fax: +91 44 2257-0509 (Institute) e-mail: [email protected] http://mme.iitm.ac.in/

Indian Institute of Metals Chennai Chapter

Indian Institute of Metals (IIM) is a premier organization representing materials and metallurgical engineers in India. Founded in 1946 by a group of metallurgists, today IIM is the largest professional organization for metallurgists and materials scientists in India with over 8000 members from R&D laboratories, academia and industry. The two primary objectives of IIM are: promoting and advancing the science and technology of metals, alloys and materials and protecting the interests of metallurgists, material scientists and metallurgical industry. The Institute has been honored by the Ministry of Steel and Mines, Govt. of India, by naming 14th of November as National Metallurgists Day (NMD) and instituting awards for distinguished metallurgists to be conferred on that day every year. The institute organizes various meetings, seminars, conferences, workshops and courses through its three Divisions namely, Ferrous,

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Nonferrous and Metal Sciences and 52 Chapters at different places regularly, providing opportunities for researchers and industry to come together and exchange ideas of mutual interest. It also organizes an Annual Technical Meeting (ATM) and immediately following NMD celebrations, where in 400-500 metallurgists and material scientists from academia, R&D institutes and industry share their recent research work in various fields. IIM Chennai Chapter functions from the Department of Metallurgical and Materials Engineering of Indian Institute of Technology Madras. The main objective of the Chapter is to disseminate knowledge in the field of Metals, Materials and Metallurgy in this part of the country. This is achieved by arranging lectures by eminent metallurgists, conducting workshops, organizing seminars, courses, etc. The Chapter has arranged a large number of lecture talks by eminent scientists, industrialists and experts from India and abroad. The Chapter has also conducted many workshops /courses / seminars by national and international experts. The Chapter is also a Centre for conducting examinations leading to Associate Membership of IIM. IIM Chennai Chapter has been conducting preliminaries of Prof. Brahm Prakash Memorial Materials Quiz every year for Class XI and XII students of various schools in Chennai. Two teams are selected and they represent IIM Chennai Chapter in the National Level Prof. Brahm Prakash Memorial Materials Quiz at Kalpakkam.

Office Bearers Chairman - Prof. Kesavan Nair Vice Chairmen - Dr. S. S.Bhattacharya Hon. Secretary - Dr. S. Sankaran Hon. Treasurer - Dr. R. Bauri

Contact Details The Indian Institute of Metals Chennai Chapter C/o Dept. of Metallurgical and Materials Engg. IIT Madras, Chennai – 600 036 Phone: 044 – 2257 4750 E-mail: [email protected]: 044 – 2257 0509 / 2257 4752

METSA

METSA is the Metallurgical and Materials Engineering Students’ Association of the Department of Metallurgical and Materials Engineering IIT Madras. A wide range of activities are organized under the banner of METSA and these activities serve to enhance interaction between students and faculty of the Department of Metallurgical and Materials Engineering, IITM.

METSA has organized several contests with joint student-faculty teams participating. These include quiz, dumb charades and pictionary contest, and a cricket match. A welcome dinner for all the incoming students of the Department was organized.

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METSA organizes an annual technical festival “Amalgam” for B.Tech / M.Tech students from Materials and Metallurgy Departments of the country. Events include paper presentation, guest lectures, lecture-demonstrations and quiz.

METSA also releases an annual magazine called 'Etch' with articles contributed by the students and faculty members of the Department.

Activities of METSA provide platform for student-faculty interactions and members of METSA and the faculty of the Department share fond memories of the games, dinner and joint student-faculty variety entertainment programme conducted at a beach.

Office bearers

Chairman : Prof. P. Kesavan Nair

Treasurer and Faculty Advisor : Dr. N.V. Ravi Kumar

Secretaries : Mr. Rahul Ladhania & Mr. T. Ragesh

URL: http://metsa.iitm.ac.in/

Material Advantage Student Chapter at IIT Madras

A career in materials can bring you in contact with an amazing and almost endlessjourney of discovery and creation

About the ChapterThe Material Advantage Student Chapter at IIT Madras was formed as the IIT Madras Student Chapter of ASM International in November 2002. In 2005, ASM International, in collaboration withthe other professional societies viz., The Minerals and Materials Society (TMS), Association for Ironand Steel Technology (AIST) and The American Ceramic Society (ACerS) launched the Material Advantage Program to promote materials science & engineering among students. The members of this program have the benefits of membership of the ASM, TMS, AIST, and ACerS. The Material AdvantageStudent Chapter at IIT Madras is being managed entirely by the students, with guidance from the Faculty Advisor. The Chapter was founded with 22 members and has now grown to a strength of 72.

Chapter ActivitiesActivities are focussed on professional development of student members and promote interest in materials science & engineering among school children. The Chapter has been very active in arranging lectures by

vii

eminent personalities, organising industrial visits, conducting conferences and innovative workshops, and school outreach programmes for motivating the students to take up careers in the field of materials science and engineering. The All India Material Quiz is organised by the Material Advantage Chapter every year.

Chapter Achievements

Chapter Excellence Award for 2004-2005Chapter Excellence Award for 2005-2006Highest Membership Award for 2005-2006Award for the Most Number of New Members Recruited, 2007-08Chapter of Excellence Award for 2007-08Special grant for conducting school outreach programme

Chapter Office BearersFaulty Advisor: Dr. Ashutosh S. Gandhi ([email protected])Chairman: P. Gerald Tennyson ([email protected])Vice-Chairman: P. John Felix Kumar ([email protected])Secretary: Alaparti H.V. Pavan ([email protected])Treasurer: H. Khalid Rafi ([email protected])

Material Advantage Student Chapter at IIT MadrasDepartment of Metallurgical and Materials Engineering Indian Institute of Technology Madras Chennai-600036, INDIA E-mail: [email protected] Material Advantage Program: www.materialadvantage.com IIT Madras Chapter: http://mme.iitm.ac.in/matadv/

Invited speakers

10th

December 2008

Dr. Amol Gokhale

Scientist G, DMRL

Hyderabad

Cellular aluminum and other metals

11th

December 2008

Shri. Pugazhenthy

President, IIM and Executive Director, India

Lead Zinc Development Association

Non-ferrous metals industry in India – The

unfolding scenario

12th

December

Prof. K.A. Padmanabhan

Mercator Professor

University of Muenster, Germany

Ultrafine grain size through mechanical

processing

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ABSTRACTS

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BF-O1

PRESSURE DEPENDENCE OF ELECTRONIC STRUCTURE OF SmSe Gupta D.C., Subhra Kulshrestha, Gajendra Raipuriya, Singh K.C., and Sushil Auluck*,

Condensed Matter Theory Group, School of Studies in Physics, Jiwaji University, Gwalior, India* Department of Physics, Indian Institute of Technology, Kanpur,India

The present paper is an attempt to study various crystal properties viz. structural, electronic and opticalproperties of SmSe as a function of pressure has been computed by the ab-initio pseudo-potential approachusing the density functional theory under the generalized gradient approximation (GGA). It is found that thiscompound undergoes a structural phase transformation from B1 (NaCl structure) to B2 (CsCl structure) athigh pressures. We have investigated the structural phase transformation, electronic band structure and densityof states (DOS) in parent as well as at high pressures. The calculated lattice constant, bulk modulus and itspressure derivative under ambient conditions are in good agreement with their corresponding experimentaldata. The band structure of SmSe shows X). The value of energy gap is in good agreement_ indirect bandgap (with the experimental one. The upper valence bands in SmSe are characterized by Se-5p states andSm-5d states. Beside this, we have also computed the real and imaginary part of dielectric function. We haveanalyzed the interband contribution to the optical properties of SmSe.

BF-O2

BIOACTIVITY ENHANCEMENT OF COMMERCIAL PURE TITANIUMTHROUGH EQUAL CHANNEL ANGULAR PRESSING

Thirugnanam A., Sampath Kumar T.S., Uday ChakkingalDept.of Metallurgical & materials Engg, Indian Institute of Technology, Madras, India

Commercial pure titanium (CP Ti) has been the material of choice for medical implants. There is greatinterest in the formation of nanosize/submicron grains due to their unusual properties as the morphology ofthe biomaterial is critical to its success as an implant material i.e. cells live in a nano-featured environmentof a complex mixture of pores, ridges, and fibers of extracellular matrix (ECM). This information eventuallyleads to the concept of nano biomaterials with advantages over conventional biomaterials. Equal channelangular pressing (ECAP) is one of the severe plastic deformation (SPD) processes used to obtainsubmicron/nano sized grains in bulk metals. Plastic deformation of titanium is difficult at room temperaturedue to limited active slip systems. However, ECAP was done successfully at room temperature up to twopasses. The objective of the present work is to study the bioactivity of ultra fine grain refined CP Ti processedby ECAP in simulated body fluid (SBF). ECAP at room temperature was done using route BC in 120 degreedie angle. Drastic grain refinement (~300nm) was observed in Transmission Electron Microscopy (TEM).Chemical treatment (acid+alkali) was done on the processed specimen to enhance bioactivity. The processedspecimen was immersed in SBF for 2, 4 weeks to access its bioactivity. The immersed specimen werecharacterized using SEM-EDAX and XRD to study the formation of hydroxyapatite(HA). It was observedthat 2nd pass specimen exhibited dense and homogenous hydroxyapatite coating when compared tounprocessed and 1st pass condition. This is due to increase in surface area as a result of chemical treatmentwhich favors more HA to nucleate and grow. The mechanism for enhancement of HA formation will bediscussed in detail in this study.

ISRS-2008 1

BF-O3

EVALUATION OF HEXAVALENT CHROMIUM REDUCTIONBY BACILLUS SP

Mary Mangaiyarkarasi M.S.1,2, Vincent S.2, Janarthanam S.3, Tata B.V.R1

1Materials Science Division, IGCAR, Kalpakkam, India2 PG and Research Department of Zoology, Loyola college, Chennai, India

3 Department of Zoology, University of Madras, Chennai, India

Bioremediation of heavy metals is studied widely using various microorganisms. But the subcellularlocalization of the heavy metal reducing ability, in these organisms is less studied. Three of the bacteria (G1,G2, G7) isolated from soil exposed to tannery effluent were found to have a minimum inhibitory concentration(MIC) of 500ppm of Cr (VI). One of the isolates G7 was found to take up high concentration of Cr (VI) andhence selected as the test organism. G7 was identified as Bacillus sp. through the biochemical tests and 16SrRNA sequencing. The sequencing results show that it has close homology (100%) with Bacillus subtilis.This organism was studied for its Cr (VI) uptake ability at various initial concentrations of 50 to 150ppm.Experiments using whole cells and permeabilized cells of G7 confirmed that a protein, present either in thesoluble or membrane fraction, carries out the reduction process. Further the Cr (VI) reduction assays usingthe cell free extract and the membrane fraction of the cells revealed the role of membrane bound proteins inchromium reduction. In order to investigate the nature of the enzyme involved in chromium reduction, assayswere carried out using the intracellular extract and the membrane fraction of cells exposed and unexposedto Cr (VI). The results of intracellular extract assay demonstrated that the chromium reducing enzyme isconstitutive in nature and not inducible. The difference in reduction of chromium was very negligible (5%).And the membrane fraction of exposed cells showed less reduction ability compared to membrane fractionof cells unexposed to Cr (VI). Thus the association of the protein to the membrane fraction and its constitutivenature are confirmed in the Bacillus sp. through these assays.

BF-O4

EXPERIMENTAL AND NUMERICAL STUDIES ON MECHANICALBEHAVIOUR OF BOVINE CORTICAL BONE USING MINIATURE

SPECIMEN TECHNIQUEChitti babu V., Sehgal D.K., and Pandey R.K.

Indian Institute of Technology, Delhi, India

Measurement of mechanical properties of biological materials often sets important constraints suchas the limited size or the irregular geometry etc. These constraints may be overcome by employing miniaturespecimens for mechanical testing. The advantage of such miniature specimens includes the possibility ofsampling very small volume of material within a heterogeneous structure such as cortical bone. Though theminiature specimen test technique has been used by a number of investigators to predict mechanical propertiesin metallic alloys the work reported in case of bones is practically non-existent. This paper describes theminiature specimen test technique for the study of mechanical behavior of Haversian (matured) bovinecortical bone. The matured bovine cortical bone has been described as a transversely isotropic material. Forthe present investigation rectangular shaped miniature specimens of sizes 10mm (length) 2mm (width) 1mm (thickness) were carefully prepared from the middle third portion of the Bovine tibia in longitudinaland transverse (circumferential) directions. The samples were machined by low speed Buehler Isomet linear

2 ISRS-2008

precision diamond saw under continuous water spray to minimize the thermal damage. Specimens weresubjected to Small Punch Testing at room temperature in wet condition using an MTS (810 model) machine.A specially designed fixture was used to hold the specimens in the MTS machine and the load vs load pointdeflection measurements were taken during the test. The experimental data obtained from miniature specimentests were further analyzed to obtain the standard mechanical properties of the cortical bone such as the yieldstrength, fracture strain and fracture toughness. The results obtained from miniature specimen tests werevalidated by conducting tensile tests and fracture toughness tests on large size specimens from mid diaphysisof bovine cortical bone in both longitudinal and transverse directions. A good agreement was found betweenthe results of miniature test and standard specimen tests. Further, finite element simulation was employed toobtain load-load point deflection diagrams in the miniature specimens by using the elastic-plastic deformationdata from the standard tensile tests conducted in the longitudinal as well as the transverse direction of thespecimens from the cortical bone. The simulation results were found to be in good agreement withexperimental results from miniature tests. The results have been discussed and the main findings have beenoutlined.

BF-O5

POLYMER-MnO2-MWNTs BASED BIOSENSORFOR THE DETECTION OF ORGANOPHOSPHORUS NERVE AGENTS

Neetu Jha and Ramaprabhu S.Department of Physics, Indian Institute of Technology Madras, India

The development of a disposable Acetylcholinesterase (AChE) based biosensor is described. Theprocess of multi walled carbon nanotubes (MWNT) by chemical vapor deposition technique has beendetailed. The as-grown MWNT have been purified by acid treatment and air oxidation methods. MWNT are

further functionalized by hydrophilic functional groups. Nanocrystalline MnO2 particles have been attachedon the surface of MWNT by chemical reduction method. Further, the conducting polymer polypyrrole has

been uniformly coated over the MnO 2MWNT surface using chemical oxidative technique and used for theelectrode preparation over GC electrode. The nanocomposite was characterized by scanning electronmicroscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The high catalyticactivity of MWNT composite towards the electroxidation of thiocholine has been utilized for the detectionof nerve agent paraoxon. Due to high porosity of polymer and high electrical conductivity of CNT basedcomposite, an excellent detection level for paraoxon could be achieved. The details of fabrication of the sensorand the dependence of the sensitivity have been discussed.

BF-P1

PIEZOELECTRIC AND DIELECTRIC PROPERTIES OF PURE ANDDOPED PZT WAFERS

Sudipta Goswami* #, Soumen Mandal, Dhruba Pal, Anshuman Seal and Sen A.Central Glass & Ceramic Reasearch Institute, Kolkata, India

PZT near its MPB (morphotropic phase boundary) has got tremendous technological importance inthe field of transducers, sensors, actuators, mechanical filters etc. Dielectric and piezoelectric properties ofPZT ceramics are strongly dependent on domain wall motion. Incorporating lead or oxygen vacancies intothe original perovskite structure can alter this domain mobility. ‘Donor’ doping induces lead- vacancies

ISRS-2008 3

whereas ‘acceptor’ doping induces oxygen vacancies to maintain the charge neutrality. Hence bymanipulating the composition via doping it is possible to tailor the properties for various technicalapplications. The current trend of miniaturization demands scaling down of the size of the electroniccomponents. Thus high-density PZT wafers are desired for the development of piezoelectric transducers,micro sensors, pyroelectric detectors and embedded surface mounted sensors and actuators for structuralhealth monitoring. It is therefore very challenging to produce high quality doped and pure PZT wafers insteadof bulk samples. Morphotropic, ‘donor’ doped and ‘acceptor’ doped PZT powders were prepared via citratenitrate combustion method. The powders formed were calcined at a relatively low temperature (550 C) toget high quality phase pure material. The wafers were fabricated using tape-casting method followed bysintering. The dielectric and piezoelectric properties of the wafers were compared with those of thecorresponding bulk samples and the possible reasons behind the discrepancies have been discussed.

BF-P2

DIELECTRIC AND FERROELECTRIC PROPERTIES OF PLDGROWN BiFeO3 THIN FILMS

Ramachandran B., and Ramachandra Rao M.S.Dept of Physics, Indian Institute of Technology, Madras, India

Multiferroics are materials which exhibit one or more of ferroic properties, namely ferroelectric,ferromagnetic and ferrotoric. The coupling between two order parameters, called the magnetoelectric effect,is very interesting from the point of view of fundamental Physics and could also lead to applications inspintronics and other fields. In order to use the magnetoelectrics in devices, a preliminary step is to grow thinfilms of magnetoelectrics. Among the possible candidates, BiFeO3 (BFO) has attracted much attentionbecause it has order temperatures far beyond 300 K [the ferroelectric Curie temperature is 1043 K and themagnetic Néel temperature 647 K], which is essential for applications. In this work, we have grown BFOthin films on Si(001) substrate with different substrate temperature (Ts 500 600 C) and oxygen partial

pressure (O2pp 6 10 4 to 0.6 mbar) by pulsed laser deposition (PLD). We have studied dielectric andferroelectric properties of BFO thin films grown on Pt (used as bottom electrode) coated Si (001) at optimizedconditions using impedance analyzer and ferroelectric loop tracer respectively. Details will be presented anddiscussed.

BF-P3

IS TITANIUM A SUITABLE BIO-IMPLANT MATERIAL???FRETTING CORROSION APPROACH

Satendra Kumar1, Sankara Narayanan T.S.N.1, Ganesh Sundara Raman S.2, Seshadri S.K.21National Metallurgical Laboratory, CSIR Madras Complex, Chennai

2Dept. of Metallurgical and Materials Engg. Indian Institute of Technology, Madras

Titanium and titanium alloys are widely used for many biomedical applications due to their low density,excellent biocompatibility, corrosion resistance and mechanical properties. High strength Ti alloys areparticularly susceptible to damage caused by repeated small amplitude reciprocating sliding, typically atattachment locations by a process known as fretting or fretting fatigue. However, these small amplitudemovements become more dangerous if they occur in an environment that is rich in chlorides. The combinedaction of small movements between the contacting parts and the corrosivity of the environment leads to the

4 ISRS-2008

degradation of materials which is known as fretting corrosion. The fretting corrosion is produced by arelatively small-scale (< 100 m) motion between the components. This motion increases the corrosion ratebecause it causes a continuous fracture and re-passivation of the oxide layers of the metallic surfaces.Orthopaedic implants, particularly the hip and knee joints, exposed to a physiological medium suffer due tofretting corrosion. Fretting corrosion leads to a reduction in life-time of the prosthesis. Each year, about800,000 hip joint prostheses are implanted in the world. However, within 9 years of use, 6 % have beenreplaced because of an aseptic loosening of the femoral stem. The mechanical damage combined with thecorrosive action could cause the release of metallic ions and fine debris that could induce deleterious effectson the surrounding tissues. In many instances, the wear debris triggers the liberation of macrophages inducingbone resorption and osteolysis responsible for prostheses failure. The performance of titanium as an implantmaterial under fretting corrosion conditions was assessed using a fretting-corrosion test assembly in Ringer’ssolution (simulated body fluid). During the fretting corrosion tests, load and frequency were set at 3 N and10 Hz respectively, while the on-time and off-time of the fretting motion were varied. The change in opencircuit potential (OCP) was measured as a function of fretting cycles/time. The extent of cathodic shift inOCP caused by the rupture of the passive film due to fretting motion and the time taken for the OCP tore-establish the steady state potential after the fretting motion is stopped indicate the performance of Ti underfretting corrosion conditions. Electrochemical impedance spectroscopy study was also performed to get abetter understanding of the corrosion behaviour of Ti under static and fretting conditions.

BF-P4

DNA FUNCTIONALIZED GOLD-GRAPHENE BIOSENSOR FORDOPAMINE DETECTION

Jyothirmayee Aravind S.S., Tessy Theres Baby, Rakhi R.B., Arockiadoss T.Dept of Physics, Indian Institute of Technology, Madras, India

The two dimensional one carbon atom thick graphene has excellent electronic properties due to theability of the electrons in graphene to conduct electrical current greater than one dimensional carbonnanotubes. In addition, the increase in the surface area in graphene due to the availability of both surfacesmakes it a very promising candidate for sensing and biosensing applications. The present work demonstratesthe detection of dopamine using DNA Functionalized Gold-graphene biosensor. Single strand DNA basedDopamine biosensor has been constructed using Au-graphene and its electrochemical detecting behavior hasbeen reported. Graphene have been synthesized by exfoliation of graphitic oxide, followed byfunctionalization using concentrated acid. It is then treated with aquaregia for better dispersion and to improveits combining capacity with DNA. Functionalized graphene is then decorated with nanocrystalline Au metalclusters using a simple chemical reduction method. Special machine grade DNA[AC] 15 was used forfunctionalization of graphene by a sonication process. Structural and morphological characterizations havebeen carried out using SEM, TEM, HRTEM and FT-IR spectroscopy. Electrochemical characterizations havebeen carried out using potassium ferro cyanide as the redox electrolyte. The detailed cyclic voltammetrystudies indicate the quick electron transfer showing that DNA-Au/graphene film is a good electrochemicalsensor.

ISRS-2008 5

BF-P5

FABRICATION OF AMPEROMETRIC GLUCOSE BIOSENSOR USINGTWO DIMENSIONAL GRAPHENE

Tessy Theres Baby, Jyothirmayee Aravind S.S., Rakhi R.B., Arockiadoss T., and Ramaprabhu S.Dept of Physics, Indian Institute of Technology, Madras, India

Graphene, a single layer of carbon atoms arranged in a honeycombed lattice in a 2 D, has unusualelectronic properties which arise from the hybridization of unbound fourth electrons in orbitals extendingvertically above and below the plane spreading across the whole graphene sheet. As a result, the ability ofthe electrons in graphene to conduct electrical current is 10 to 100 times greater than those in a normalsemiconductor like silicon at room temperature. This makes graphene a very promising candidate for futureelectronic and biosensing applications. In the present work, graphene has been prepared by exfoliation ofgraphitic oxide and characterized by powder X-ray diffraction (XRD), High resolution transmission electronmicroscopy (HRTEM), atomic force microscopy (AFM), thermal gravimetric analysis (TGA) and Ramanspectroscopy. Amperometric biosensor has been fabricated by the deposition of glucose oxidase (GOD) overNafion-solubilized graphene electrode. The electrode used was glassy carbon electrode. The resultantbioelectrode retains its biocatalytic activity and offers fast and sensitive glucose quantification. Theperformance of the sensor was investigated by electrochemical methods at an optimum potential of 0.80V and pH 7.0. The fabricated glucose biosensor exhibits a linear response up to about favorable glucosecontent and an excellent detection limit and the results have been discussed.

BF-P6

PHOSPHORIC ACID GRAFTED MCM-41 IS A NOVEL BRONSTED ACIDCATALYST FOR TRANSESTERIFICATION REACTION OF DIETHYL

OXALATE WITH n-BUTYNedumaran D. and Pandurangan A.

ICPT, A. C. Tech, Anna University, Chennai, India

The focus towards healthy solid acid catalysts associated with recyclability laying road to thepreparation of Orthophosphoric acid grafted MCM-41 mesoporous molecular sieves. The variousconcentration of Orthophosphoric acid was grafted on siliceous MCM-41 by wet impregnation method. Thematerial was dried and Calcined The prepared H3PO4/MCM-41 materials were characterized by X-rayDiffraction analysis (XRD), BET surface area method, Pyridine adsorption FT-IR measurements, NH3-TPD,XPES and31P NMR. The information about the acid sites, state and structure of grafted phosphorus specieswere obtained from the physicochemical investigations. The morphology of mesoporous materials wasstudied by TEM technique. The catalytic activity of the above materials was tested over single step organictransformation reactions. The transesterification reaction of Diethyl oxalate with n-Butanol was studied tocheck the catalytic activity of the synthesized mesoporous material. The pyridine adsorption FT-IRinvestigations show the generation of Bronsted acid sites on mesoporous material. It enhances the selectivityof the product. To get better yield the reaction parameters such as time, temperature and various concentrationsloading of catalyst were optimized. The leaching out of Phosphoric acid from MCM-41 and the reusabilitywere investigated.

6 ISRS-2008

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CM-O1

INNOVATIVE PRODUCTION OF POROUS COPPER COMPOSITEBY CHEMICAL REACTION

Ahmad Moloodi, Ramin Raiszadeh, Jalil Vahdati Khaki, Abolfazl BabakhaniShahid Bahonar University of Kerman

Metal foams are a new, as yet imperfectly characterized, class of materials with low densities and novelphysical, mechanical, thermal, electrical and acoustic properties. Copper foams are popular metal foams thatare used in thermal conductors. This article describes a method named Self-propagating High-temperatureSynthesis (SHS) process to produce open cell copper composite foams. Porous Cu composite was fabricatedby reactions between CuO, Al and C powders. Gas released during these reactions and also the initial porosityof the green powder compact were the source of the produced pores. The relative densities of the coppercomposite foams have been investigated for different metal weight fractions. Optical microscopy andscanning electron microscopy (SEM) were utilized to characterize the porous samples. Analyzing theproperties of the metal foams showed that the optimum weight fraction for blending initial powders was %84CuO, %9.5 Al and %6.5 C. In addition, if the initial compacting pressure of the powders was decreased tobelow 150MPa, the SHS reaction did not take place properly.

CM-O2

SHEAR BEHAVIOR OF REINFORCED CONCRETE T-BEAMSWITH EXTERNALLY SIDE BONDED GLASS FIBER REINFORCED

POLYMER COMPOSITESBhattacharyya S.K. and Barai S.V.

Indian Institute of Technology, Kharagpur, India

Rehabilitation of structures becomes the new challenge for structural engineers today. Fiber ReinforcedPolymer (FRP) composite systems may be used for rehabilitation of reinforced concrete (RC) structures.These materials are an excellent option for use as external reinforcing because of their light weight, highstrength, and high corrosion resistance. This paper presents an experimental study on the performance of2500 mm long reinforced concrete (RC) T-beams strengthened in shear using epoxy bonded glass fiber fabric.Experiments are conducted on nine simply supported RC T-beams, out of which six beams are used as controlbeam with and without transverse steel reinforcements and rest three beams are strengthened in shear withone, two, and three layers of glass fiber reinforced polymer (GFRP) in side of the web of the T-beams. The6 mm dia. stirrups are provided at 200 mm spacing. All the beams are tested at the structural engineeringlaboratory of IIT, Kharagpur by using 300 Ton hydraulic testing machine. It is observed that the magnitudeof the increased shear capacity is dependent not only on the type of GFRP but also on the internal transversesteel reinforcement. The study also shows that the combination of GFRP layers and transverse steel is animportant factor to gain the ductility.

ISRS-2008 7

CM-O3

STRUCTURE AND PROPERTIES OF TRANSITION METAL NITRIDEBASED SUPERHARD NANOCOMPOSITE COATINGS

Deepthi C., Harish, Barshilia C. and Rajam K. S.Surface Engineering Division, National Aerospace Laboratory, Bangalore, India

The role of coatings as a surface modification technique has grown significantly for applications inautomobile, aerospace, electronic, biomedical, cutting tool and other sectors since they can impart specificproperties such as hardness, toughness, wear resistance, etc. to a surface. Transition metal nitride coatingshave been widely used as protective hard coatings to increase the lifetime of cutting and forming tools. Theuse of hard coatings has spread well beyond tools; they are now being used for many tribological applicationsand also for decorative purposes. Among the significant developments in the area of hard coatings has beenthe synthesis of nanostructured coatings like nano-scale multilayers and nanocomposites. Highlysophisticated surface related properties like mechanical, optical, magnetic, electronic and tribologicalproperties can be obtained using nanostructured coatings. Transition metal nitride based nanocompositecoatings are the emerging class of superhard materials (hardness 40 GPa) and apart from high hardness theyalso exhibit high oxidation resistance, toughness, corrosion and wear resistance and even retain their highhardness at elevated temperatures. As these nanocomposite coatings display a combination of extremeproperties, they are expected to have a wide range of technological applications apart from the basic scienceinvolved in the development of such coatings. We have developed a variety of superhard nanocompositecoatings such as TiN/a-C, TiN/a-Si3N4, TiAlN/a-Si3N4, CrN/a-Si3N4 and CrAlN/a-Si3N4. Thispresentation will address issues related to the growth and characterization of these coatings. In particular, wehave used ion beam assisted reactive direct current unbalanced magnetron sputtering process to deposit thesecoatings. Characterization techniques such as X-ray diffraction, X-ray photoelectron spectroscopy,transmission electron microscopy, nanoindentation, scanning electron microscopy, atomic force microscopy,energy dispersive X-ray analysis, micro-Raman spectroscopy, tribometer and potentiodynamic polarizationhave been used. Correlation between the microstructure and various properties of the superhardnanocomposite coatings will be presented.

CM-O4

FORMING AND ANLYSIS IN METAL MATRIX COMPOSITES Al/SiCVijayananth S., Kalaiselvan K., Ravi Subramanian

Madras Institute of Technology, Chennai, India

Superplastic forming analysis of Aluminium 6063 alloy which is reinforced with Silicon Carbideparticles. The presence of the reinforcement phase in a continuous Aluminium alloy Metal Matrix Compositeresults in properties not attainable by other means, thereby enhancing the potential range of possibleapplications. Aluminium metal matrix composite has wide range of applications in the field of Automobileand Aeronautical structures. In this project the superplastic analysis of composite material will be done forvarious particle size and volume fractions of Silicon Carbide. The Al/SiC can be formed by Stir castingprocess and Compare the strength of the materials. Cavitational behavior of the material has been studied.

8 ISRS-2008

CM-O5

EVALUATION OF COMPRESSIVE PROPERTIES OF EPOXY RESINFILLED WITH FLY ASH POLYMER MATRIX COMPOSITE MATERIALS

Arun Kumar M.B. and Swamy R.P.University BDT College of Engineering

This paper summarizes attempts to incorporate fly ash into epoxy matrix to evaluate the compressiveproperties of fly ash epoxy composite materials. It is shown that fly ash can be incorporated effectively intoan epoxy matrix to build fly ash epoxy composite material. With the purpose of characterizing the compressiveproperties of the promising low density epoxy/fly ash composites, a series of epoxy composites filled withdifferent volume fractions of fly ash content are prepared in this work. Compression tests on the cured flyash epoxy composites are performed using computerized universal testing machine and the results arediscussed.

CM-P1

PREPARATION AND CHIP ANALYSIS OF ALUMINIUMMATRIX COMPOSITES (AMC)

Arunachalam R.M., Sasikumar R. and Karthikvenkatesh G.Dept of Mechanical Engg. Sona College of Technology, Salem, India

In the recent years, the nanostructured materials have been identified as a new wave towardsmillennium innovations in the materials science engineering. With reduction of a characteristic length suchas the grain size or the cluster or molecular size, the normal properties of materials are drastically changed.By large strain plastic deformation of materials the grain sizes are refined in the range of submicron level.In this research Aluminium Metal Matrix composites (AMC) casting of 15% silicon carbide (SiC) particleand 85% Aluminium alloy (LM25) is prepared by stir casting method. Aluminium is melted in a compositefurnace and preheated SiC particles are added and stirred. The molten mixture was then poured into a metaldie of diameters 50mm and length 100mm. The casted AMC was machined using tungsten carbide coatedcutting tools. Newly designed mechanical Quick Stop Device (QSD) was fabricated for the chip root study.AMC chip root samples were obtained using the fabricated QSD. The chip sample was mounted and preparedfor microstructure analysis.

Key words: Stir casting, Machining, Aluminium Metal Matrix Composites.

CM-P2

FABRICATION AND TESTING OF GLASS FIBER EPOXY RESINCOMPOSITE LAMINATE

Komuraiah A.*, Srikath Rao D.**, Suvarna Raju L.*, Devender V.***Asst Prof, KITS(S) huzrabad, Asst prof, KITS(S) huzrabad Dist., Karimnagar

**Asst Prof., Asst Prof. S R, Engineering college

A composite material is a combination of two or more materials having compositional variations anddepicting properties distinctly different from those of individual materials of the composites. The compositematerial in general better than the individual components regarding their strength, heat resistant and stiffness.The composite materials are widely used in aerospace industry, underwater exploration and other so many

ISRS-2008 9

industries. In this paper we want to explain how to fabricate the laminate (specimen) of glass/ epoxy compositeand test it. Than the results are compared with the conventional materials i e mild steel. We have found themodulus of rigidity of the composite material is 1.54 10e5 N/sq mm where as mild steel is 8.9 N/sq mm

and Young’s modulus of elasticity is for composite specimen is 0.73 10 e 4 N/sq mm and mild steel is 2.01

10 e5 N/sqmm . We conducted tests to find brinels hardnes test, Impact test. The beauty of thisexperimentation is that the specimens are prepared by commonly available materials and testing done on themachines in our collages.

CM-P3

HYGROTHERMIC BEHAVIOR OF CARBON / GLASS REINFORCEDCOMPOSITES

Sreejith M., Narasimha Murthy H.N., Krishna M., Rai K.S., Sharma S.C. R.V.College of Engineering, Bangalore, India

Moisture absorption and Hygrothermic aging of 2-D woven mat glass / carbon reinforced epoxy / vinylester composites were thoroughly studied for their suitability to marine applications. The laminates (250

250 3 mm) were fabricated using hand lay-up process maintaining a fibre / matrix ratio of 65: 35 by wt %and were naturally cured as post curing is not recommended for marine applications. The test coupons wereexposed to 50oC 60oC, 70oC and 95 % RH for a maximum duration of 196 days in a programmableenvironmental chamber supplied by M/s CM Equipment. The specimens were periodically withdrawn andweighed for moisture absorption and tested for mechanical property (UTS, FS and ILSS) degradation. Themaximum moisture absorption under the test conditions was found to be in case of Epoxy / glass specimens,i.e. 0.95 % at 700oC, 95 % RH and 0.87 % at 500oC. The least moisture absorption was in the case of vinylester/carbon specimens being 0.55% at 700oC, 95 % RH and 0.5% at 500oC. Diffusion mechanism wasstudied based on the Fick’s law of diffusion. Diffusion coefficient (D) was found to be the highest (5.52

E-6) in case of epoxy/glass specimens and the lowest (3.65 E-6) for Vinyl ester / Carbon at 50oC, 95 %. Dincreased with increase in temperature for all the specimens. Between Vinyl ester / Carbon and Epoxy / carbonspecimens the former showed lesser drop in ILSS, UTS and FS. Vinyl ester / glass specimens proved superiorto Epoxy / glass specimens with respect to degradation in the mechanical properties. Though the degradationin the mechanical properties increased with increase in temperature from 50oC to 70oC, the degradation washigher when the temperature was increased from 50 and 60o C than from 60 to 70oC. The overall observationwas that Vinyl ester proved superior to epoxy and carbon to glass. These experimental observations areconfirmed by scanning electron micrographs which showed better adhesion of the fibre to the matrix andlesser plasticization effect of the matrix in case of vinylester/carbon specimens. The better performance ofvinyl ester was attributed to the gel coat which minimizes the voids and decreases water permeation. Thenumber of days to attain maximum moisture absorption increased with respect to increase in temperature inall the four types of specimens. The duration was the least (39 days at 50oC and 48 days at 70oC) in case ofvinylester / carbon specimens. Vinylester based specimens showed stability with respect to degradation unlikethe epoxy based specimens which showed continuous drop in the mechanical properties.

10 ISRS-2008

CM-P4

MORPHOLOGY AND DYNAMIC MECHANICAL PROPERTIES OFPP/MMT/OMMT HYBRID NANOCOMPOSITES

Selvakumar V., Palanikumar K., Palanivelu K.,Dept of Mechanical & Production Engineering, Sathyabama University, Chennai, India

This article addresses the effect of nanoclays montmorillonite (MMT) and organo-montmorillonite(OMMT) on morphology and dynamic mechanical properties of polypropylene (PP). The preparation ofpolymer hybrid nanocomposites by melt compounding PP with MMT and OMMT using polypropylenegrafted maleic anhydride (PP-g-mA) as compotibilizer is described. First stage compositions with MMTcontent 1%, 3%, 5% and 7%by weight ratio PP/MMT nanocomposites were prepared and tested. Secondstage compositions with OMMT content 1%, 3%, 5% and 7% by weight ratio PP/OMMT nanocompositeswere prepared and tested. Third stage both combined MMT and OMMT equally mixed content 1%, 3%, 5%and 7% by weight ratio PP/MMT/OMMT hybrid nanocomposites were prepared and tested. The influenceof nanoclays on the impact fracture morphology of the nanocomposites was studied by scanning electronmicroscopy (SEM). Dynamic mechanical properties (DMA) indicated significant improvement in the storagemodulus and loss modulus compared with neat PP. The tan peak signifying the glass transition temperatureof nanocomposites shifted to higher temperature.

CM-P5

SOME STUDY ON MECHANICAL PROPERTIESOF POLYESTER HYBRID COMPOSITES

Sudha G.S. and Arun kumar M.B.University BDT College of Engineering

The paper presents the results of experimental investigation on mechanical properties of polyesterhybrid composites. Mechanical properties such as compression, shear and hardness for varied volumefractions of polyester, glass-fiber, silica and polyester, glass-fiber emery were conducted for both solid anddrilled specimens with varied wall thickness. Compressive strengths for solid and drilled specimens werecompared and their results were tabulated. It was observed that as the wall thickness varies from 2mm to6mm in step of 2mm the compressive strength increases with increase in wall thickness and also percentageincrease in area and reduction in length for both solid and drilled specimen were noted and graphs wereplotted for percentage increase in area v/s specimen type. Hardness test was conducted and it was studiedthat specimen codePGS4 and PGE2 had the highest RHN-B number.

CM-P6

HIGHER ORDER COMPUTATIONAL MODEL FOR THE STRESSANALYSIS OF ANTISYMMETRIC ANGLE PLY COMPOSITE PLATES

Swaminathan K. and Sangwai G.R. National Institute of Technology, Surathkal, India

Fibre reinforced composite materials are increasingly used in industrial sectors due to their highstrength-to weight ratio, high stiffness-to-weight ratio, excellent corrosion resistance and satisfactory fatiguedurability. For composite plate structures, the elastic modulus to shear modulus ratio is relatively large as

ISRS-2008 11

compared to isotropic plates. The special properties exhibited by composite materials such as high degree ofanisotropy and weak rigidities in transverse shear make the method of analysis using computational modelsbased on Classical Laminated Plate Theory (CLPT) and the First Order Shear Deformation Theory (FSDT)inadequate. Hence the mathematical modeling of the effects of transverse shear deformation and the crosssectional warping has become an important area of research in the analysis and design of various structuralelements viz., plates and shells made up of fibre reinforced composite materials used in aerospaceapplications. Developing accurate and efficient analysis methods for composite structures have consistentlybeen an important area to predict accurate failure patterns which consequently can be used for economicaland durable designs.

In the present investigation one such higher order displacement model with nine degrees-of-freedomis used for the computation of transverse stresses which reduces the mathematical complexity in analyzingthe plates with 3 D elasticity solution. This computational model is based on Taylor’s series expansion of thedisplacements in the thickness coordinate and incorporates the laminate deformations which account for theeffects of transverse shear deformation and a non-linear variation of in-plane displacements. A simplysupported plate subjected to sinusoidal transverse load is considered for the analysis. The equations ofequilibrium are obtained using Principle of Minimum Potential Energy (PMPE). Solutions are obtained inclosed form using Navier’s technique by solving the boundary value problem. Plates with varying aspectratios, degrees of anisotropy, fibre orientations and material properties are considered for the analysis.Extensive numerical results are obtained and presented for the transverse deflection, inplane and transversestresses.

12 ISRS-2008

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CN-O1

MWCNT/CARBON BLACK DISPERSED INTO STRUCTURALADHESIVE (EPOXY) USING TWIN SCREW EXTRUDER FOR

IMPROVED ELECTRICAL CONDUCTIVITYJeena J.K., Narasimha Murthy H.N., Krishna M., Rai K.S.

R.V. College of Engineering, Bangalore, India

Structural adhesives are used extensively in space and aerospace industries for adhesive bonding ofboth metallic and composite materials. Conductivity is required across the joints to prevent static chargebuild-up. Research efforts are concentrated on improving the conductivity of structural adhesives and onepotential method is to disperse nanofillers into the adhesive systems. Though several methods of dispersionof nanofillers such as MWCNT and carbon black (CNP) into Epoxy systems are reported achieving uniformdispersion of the conductive fillers is still a challenge especially in case of adhesive grades. This paper presentsadoption of co-rotating twin screw extrusion for dispersing MWCNT / CNP into AV138M a structuraladhesive which is widely used in space structural applications. The process of dispersion was evolved basedon a patent on the twin screw extrusion for thermoplastics. Preliminary experiments were conducted to arriveat the temperature, speed, residence time and the screw elements of the extruder. Nanocomposite sampleswith up to 15 wt % MWCNT/ CNP were fabricated. Volume and surface resistivities of the nanocompositeswere measured as per ASTM D257using Keithley Model 6517 High resistance meter. Both CNP andMWCNT showed drop in electrical resistivity of the neat resin; a drop to the extent of 1010 ohm-cm, whichwas achieved with 10 wt % MWCNT loading and the same was with 15 wt % in case of CNP. With thecorresponding values of volume resistivity the structural - cm) to adhesive (AV138M) transitioned from

totally insulative (E 15 - cm). The experimental values were compared dissipative range (E 5 with analyticalcomputations using Power law equation. SEM and AFM were used to examine the dispersion. The effect ofnanofillers on the glass transition temperature was studied using DSC. Tg improved by 10 in case of

MWCNT and by 4 C in CNP composites compared with that of neat resin.

CN-O2

FABRICATION OF CARBON NANOTUBE BASED ELECTRODES FOR WATER PURIFICATION

Ashish Kumar Mishra and Ramaprabhu S.Indian Institute of Technology, Madras, India

Carbon nanotubes (CNTs) are currently the focus of intense research interest due to their exceptionalphysical, chemical and electronic properties that could impact broad areas of science and technology, rangingfrom super strong nanocomposites to nanoelectronics. Water purification is one of the most important areasof research in the present era,since natural water has different metal ions which cause different diseases. Highaspect ratio of CNT makes it a suitable candidate for water purification due to the fact that its large surfacearea provides enough adsorption sites for harmful metallic ions present in some natural sources of water.Although sodium (Na) is an essential element for human beings, excess of Na cause health problem andhence there is need for a mechanism which can reduce the excessive amount of Na from natural water.

ISRS-2008 13

Therefore in the present study, the reduction of Na metal ion in water is being focused by the ion exchangemechanism with CNT based electrodes. CNTs have been synthesized by chemical vapor deposition techniqueand the appropriate CNT based nanocomposites have been prepared by chemical methods. CNT basedelectrodes have been fabricated over a flexible carbon fabric substrate using appropriate binder with a specialtreatment to regain the porosity of the CNT. The performance of these electrodes for the removal of Na ionin water has been discussed.

CN-O3

SYNTHESIS OF CNTs OVER MESOPOROUS MCM-41 MOLECULAR SIEVESMalarvizhi A. and Pandurangan A.*

ICPT, A. C. Tech, Anna University, Chennai, India

Carbon nanotubes-based bio-nano-systems, which are formed by functionalizing nanostructures withbiological/biochemical molecules, utilize unique properties of nanostructures in conjunction with remarkablebiological/chemical species recognition capabilities, exhibiting great potential for biological and biochemicalapplications. Carbon nanotubes were synthesized by CVD method using acetylene as carbon source at700-900 $C. Mesoporous Fe, Co and Mg-MCM-41 molecular sieves synthesized by hydrothermal methodin various ratios (25, 50, 75 and 100) were used as catalysts support for the growth of CNTs. The catalystswere characterized by XRD, FT-IR and DRS-UV spectrum. The synthesized carbon nanotubes were purifiedwith acid treatment in order to remove the metal particles and other carbonaceous products. The purifiedCNTs were characterized by SEM, TEM and Raman spectroscopy to know its surface morphology andvibrational properties. These single walled carbon nanotubes were produced in high selectivity and the carbondeposition was found to be more than 90 %. For cholestrol molecules, the most commonly used scheme isto covalently link the CNT carboxylic acid groups.

CN-O4

WATER ASSISTED CHEMICAL VAPOR DEPOSITION FORMILLIMETER LONG GROWTH OF 2D ALIGNED CARBON

NANOTUBESRavi Joshi, Hermann Tempel, Jörg Engstler, Jörg J. Schneider

(Technische Universität Darmstadt Germany.)

Water assisted chemical vapor deposition is a unique route to grow millimeter long ultra pure carbonnanotubes (CNTs). A small amount of water vapor and not the hydrogen gas plays a vital role as catalyst lifeenhancer to keep catalyst clean from amorphous carbon, by which CNT growth rate as high as 20-30 %mper minute can be achieved.

Here we present our work towards an understanding of the vital role of hydrogen gas and aluminummetal as substrate for the typology of the CNTs grown. The type of CNTs grown essentially depends not onthe amount of water vapor supplied but on the quantity of hydrogen gas in the total gas flow as well as thequality of aluminum used as a buffer layer. Our results confirm that hydrogen gas controls the number ofwalls of CNTs grown while type and quantity of aluminum controls the catalyst particle size and therebycontrolling diameter of CNTs grown.

14 ISRS-2008

CN-O5

EFFICIENT PREPARATION OF CARBON NANOTUBES BY FLUIDIZEDFLOATING CATALYST METHOD USING Fe/Ni/Mg

Azira A.A.1*, Zainal N.F.A.1, Nik S.F.1, Soga T.2, Abdullah1S., Rusop M.11Faculty of Applied Sciences

Universiti Teknologi MARA, 40450 Shah Alam, Malaysia2Nagoya Institute of Technology, Nagoya 466-8555, Showa-ku, Gokiso-cho, Japan

Fluidized floating catalyst method has been modified for preparing carbon nanotubes (CNTs) whichyielded high yield even at low temperature; 650 C. Optimum concentration for Fe/Ni/Mg (molar ratio of

Fe:Ni:Mg 1:1:1) has been found to be around 2.133% for the best yield. CNTs are produced from theevaporation of part of the precursor (camphor oil) which decomposes in situ and aggregates on the metalalloy catalyst particles present in the evaporating boat. Since the metallic alloy was obtained by calcining therespective nitrates, it is expected to have residual entrapped nitrogen which may bond with the depositingCNT. This result demonstrates that modified fluidized floating catalyst method is suitable for effectiveformation of CNTs with average size ~11 nm. The morphological studies support ‘tip growth mechanism’for the growth of the CNT’s in our case. The as-grown CNTs were characterized by FESEM and FTIRspectroscopy. FTIR showed that nitrogen does go in the process and C-N is formed by accessing to the surfacecarbon and instead of intercalating within the CNT.

CN-P1

ELECTRON FIELD EMISSION FROM CONDUCTING POLYMERCOATED METAL ENCAPSULATED AND METAL OXIDE LOADED

MULTI WALLED NANOTUBE COMPOSITERakhi R.B., Sethupathi K. and Ramaprabhu S.

Indian Institute of Technology, Madras, India

Due to their natural geometry with high aspect ratio, chemical stability, high mechanical strength, highelectrical conductivity and the possibility of large scale production, carbon nanotubes (CNTs) have beenreported as excellent field emitters at low operating voltages. The realization of CNT based vacuummicroelectronics has been limited due to the absence of a stable film fabrication process over a suitablesubstrate. The weak adhesion of CNTs to the substrate leads to catastrophic vacuum breakdown. In addition,the electronic resistance between the CNTs and the substrate results in joule heating of the interface, reducingthe electrical contact between the emitters and the substrate. In order to overcome such undesirable effects,we have fabricated a fully carbon based field emitter by spin coating a solution of surface modified multiwalled carbon nanotubes (MWNT) over a graphitized carbon cloth. MWNT have been synthesized bychemical vapor deposition technique. Polymer/metal/metal-oxide dispersed MWNT have been prepared byin-situ polymerization and chemical methods and field emitters have been prepared by spin coating thecomposite material on suitable substrates. Field emission properties have been studied using an indigenouslymade facility. The use of graphitized carbon woven as substrate has brought in flexibility in the fabricationof carbon nanotube field emitters with reduced contact resistance and opens several new possibilities forCNT field emitters.

ISRS-2008 15

CN-P2

CARBON NANOTUBE FILLED POLYMER NANOCOMPOSITES FORELECTROMAGNETIC INTERFERENCE SHIELDING

Eswaraiah V., Sankaranarayan V. and Ramaprabhu S.Indian Institute of Technology, Madras, India

With the rapid advances and broad implementation of telecommunication technologies, there is aninterest in shielding of electromagnetic interference in the radio and microwave frequency ranges. The useof metals and their composites as effective shielding materials has disadvantage due to limited mechanicalflexibility, heavy weight and corrosion. Conducting polymers are promising materials for shieldingelectromagnetic radiation because of their relatively high conductivity and flexibility. Due to their naturalgeometry with high aspect ratio, chemical stability, high mechanical strength, high electrical conductivityand the possibility of large scale production, carbon nanotubes (CNTs) can be used together with theconductive polymers for possible electro magnetic shielding applications. In the present investigation, multiwalled Carbon nanotubes (MWNT) coated conducting polymer composites are fabricated by usingsolution-casting method. Multi walled carbon nanotubes are prepared by catalyst supported Chemical VaporDeposition (CVD). Composites with different wt % of MWNT and MWNT have been characterized byHRTEM, SEM, XRD, TGA and Raman spectra measurements. DC electrical conductivity at roomtemperature for these composites has been measured and the transformation from insulator to conductor atparticular percolation threshold value of CNTs has been investigated. The effective use of MWNT filledpolymer composites as Electromagnetic Interference (EMI) shielding material has been discussed.

CN-P3

MULTI-WALLED CARBON NANOTUBES SYNTHESIS BYMECHANO-THERMAL METHOD

Kesava Pandian, S. Karthik K. and Victor Jaya N.Department of Physics, Anna University, Chennai, India

Mechano-Thermal method is a completely new method for carbon tube preparation, multi-wallednanotubes (MWCNT) contain multiple graphite cylinders nesting within each other. The changes in thecrystallinity of graphite during milling have been examined on several occasions and the general conclusionwas that graphite passes through a nanocrystalline phase prior to amorphization. The mechano-thermalmethod, consisting of a pre-ball milling and a subsequent thermal annealing process, can produce much largerquantities of nanotubes due to a solid-state process without any vapor phase and the large milling capability.In this present work graphite powder milled by ball-milling for 150 hours then annealed at 1200 C/6hrs innitrogen atmosphere. The prepared MWCNT’s were characterized by X-ray powder diffraction (XRD),scanning electron microscopy (SEM) and Fourier Transform infrared spectroscopy (FTIR). Subsequentannealing activates the growth of the (0 0 2) basal planes which shows that the prepared sample containsCNT along with the amorphous carbon.

16 ISRS-2008

CN-P4

SYNTHESIS AND CHARACTERIZATION OF CARBON NANOTUBES BY MECHANOTHERMAL PROCESS

Josephine Therasa J.National Institute of Technology, Rourkela, India

This work is intended to study the characteristic nature of carbon nanotubes prepared by Mechanothermal process. CNTs have been produced by first ball milling of graphite at room temperature and then byannealing in the temperature range 1000 1200 C in the N2 atmosphere. Ball milling creates the nuclei fornano tubes and the subsequent annealing is responsible for the formation of carbon nanotube growth. Thestructure and morphology of as-prepared carbon nanotubes are characterized by XRD and SEM. Attachmentof impurities or functional groups with grown nanotubes were characterized by using FTIR spectroscopy.The thermal behavior of the material is studied by using TGA and DTA measurement.

CN-P5

STUDIES ON CARBON NANOTUBE EMBEDDEDIN A SILICON DIOXIDE

ChandraKishore S. and Pandurangan A. ICPT, A.C. Tech, Anna University, Chennai, India

In this work we use carbon nanotube (CNT) synthesized at low temperature using chemical vapordeposition method. The above prepared CNT was purified by various acid treatment method .Carbonnanotubes (CNTs) were investigated by Scanning electron microscopy (SEM), Transmission electronmicroscopy (TEM) and Raman spectroscopy. A monolayer of CNT embedded in a dielectric film wasfabricated by sandwiching CNT between two silicon dioxide layers. Capacitance–voltage measurements at300 K were studied to show CNT function as a floating gate in the above CNT/insulator /semiconductormemory structure. The memory effect will be utilized in next generation flash memories.

CN-P6

STUDIES ON THE BROMINATED MULTI-WALLEDCARBON NANOTUBES

Zainal N.F.A.1*, Azira A.A.1, Nik S.F.1, Zain Ahmed A.2, Abdullah S.1 and Rusop3 M. 1Faculty of Applied Sciences, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor, Malaysia

2Research Management Institute (RMI) Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor, Malaysia3Institute of Sciences, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor, Malaysia

The multi-walled carbon nanotubes (MWCNTs) were brominated at room temperature by immersingthe MWCNTs in bromine solution. The MWCNTs were purified prior to the bromination process. Theintercalation of Br between graphene layers of MWCNTs was confirmed by the X-ray diffraction result,showing an increase in the interlayer spacing compared to the MWCNTs without bromination sample.Thermo-gravimetric analysis (TGA) was used to determine the content of the Br2 in the sample in which theanalyzer characterized the weight loss performed at a heating rate of 10 /min heating from room temperature

to 900 C in air flow.

ISRS-2008 17

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EM-O1

DIELECTRIC STUDIES OF Ca1-x Lax Cu3 Ti4-x Cox O12SYNTHESIZED BY SEMI-WET ROUTE

Alok Kumar Rai, Mandal K.D. and Om Parkash, Department of Applied Chemistry, Department of Ceramic Engineering,

Institute of Technology, B HU Varanasi, India

The calcium copper titanate Ca Cu3 Ti4 O12 (CCTO) is a distorted perovskite exhibiting a giantdielectric constant with non-ferroelectric temperature behavior. The very large value of the dielectric constant

(k>10,000) and its near constancy over a wide temperature (100 600 K) and frequency (10 1MHz) rangemake it a suitable material for memory and radio frequency applications in semiconductor technology. Thedielectric properties of CCTO that can be used in many commercial applications but it is only the loss factor,which is restricting this material for variety of applications. It is well known that dielectric and electricalproperties of CCTO are strongly dependent upon the microstructure such as grain size and processingconditions (such as oxygen partial pressure, sintering temperature and cooling rate) as well as doping. Forthe doping effects, there are many examples in the literature such as substitution of Mn for Cu, La for Ca andZr for Ti. First time in this paper we have doped lanthanum and cobalt simultaneously in CCTO by semi-wetroute using solid TiO2 powder and metal nitrate solutions. TGA/DTA curves of the powder precursor shows1073 K was considered as an appropriate annealing temperature for the gels. X-ray powder diffractionanalysis confirms the formation of single-phase at 1173 K. Energy dispersive X-ray analysis confirms thehigh purity of the synthesized materials. The average grain size was determined by using Scanning electronmicroscopy. Particle size was also confirmed by Transmission electron microscopy. The high permittivitycould be associated Maxwell-Wagner model, which was result from semiconducting grains and insulatinggrain boundaries. The dissipation loss in the giant-dielectric constant materials CCTO was reduced to a levelof practical applications by the lanthanum doping.

EM-O2

INTERPLAY OF THE SINGLE PARTICLE AND JOSEPHSONCOOPER PAIR TUNNELING ON THE SUPERCONDUCTING

QUANTUM DOT JUNCTIONArchana Dhyani*, Tewari B.S. and Ajay

G.B. Pant University of Agriculture and Technology, Pantnagar, India

In the present paper we have investigated the interplay of the single particle and Josephson Cooperpair tunneling on the Josephson supercurrent across the Superconducting Quantum dot junction havings-wave symmetry order parameter and a single level uncorrelated dot. For this purpose we have used arenormalized Anderson model that includes the single particle coupling of the superconducting lead, attractiveBCS effective interaction in the superconducting leads responsible for pairing and Josephson Cooper pairtunneling responsible for the Cooper pair tunneling through such Superconducting Quantum dot junction.We employed the Green’s function and Ambegaokar-Baratoff formalism to analyze the Josephsonsupercurrent across such junction. We have pointed out that the Josephson supercurrent across

18 ISRS-2008

Superconducting Quantum dot junction is dominated by a competitive role of attractive pairing interactionin the lead, energy of the dot level and also on the Josephson Cooper pair tunneling in an essential way.

EM-O3

NON-DESTRUCTIVE EVALUATION OF THERMAL AND ELECTRONICTRANSPORT PROPERTIES OF SEMICONDUCTOR THIN FILMS

Anita R Warrier, Sreekumar R., Sudha Kartha C., Vijayakumar* K.P.Cochin University of Science and Technology, Kochi, India

Photothermal beam deflection technique is a non-destructive means of measuring the carrier mobilityand thermal diffusivity of semiconductor thinfilms. These properties are of major importance in determiningthe device efficiency. Semiconductor materials when excited using a periodically chopped laser beam withenergy greater than the band gap of the material, causes emission of thermal waves due to intraband transitionsand carrier recombinations. Photothermal deflection (PTBD) technique was successfully employed forcharacterization of indium selenide thin films. The chopping frequency was varied from 4 Hz to 2 kHz. Therefractive index gradient produced in the medium surrounding the sample is detected using a low power (0.5mW) probe laser beam. The deflection of probe beam path is measured using bicell and lock in amplifier (SR830). Indium selenide thin films were prepared by annealing In/Se bilayer systems. Thin films of selenium(150 nm thick) were first deposited on glass substrate using chemical bath deposition technique, over which30 nm of indium was deposited with the help of resistive heating technique (using molybdenum boat).Thickness of the films was measured employing a stylus thickness profiler (Model – Dektak 6M). Thesesamples were later irradiated using 80 MeV Ni ions (from 15UD Pelletron accelerator) with a fluence ofranging from 1-tera to 10-tera ions/cm2 at room temperature by using an electromagnetic scanner. Range of80 MeV Ni in Indium selenide is about 15 m (calculated using TRIM code 95), so that it passes throughthe film and gets embedded in the substrate. The minority carrier mobility of the film was found to increasefrom 10 to 21 (cm) 2/Vs with increase in irradiation energy (1 tera to 3 tera ions/sq. cm) and decreases (3.6(cm) 2/Vs) at higher energy irradiation (10 tera ions/sq. cm). This is because irradiation upto certain fluencecan anneal defects in the material but beyond that irradiation can cause creation of defects. We also observethat the irradiation can cause increase in non-radiative thermal emission in the material. Hence we find theincrease in mobility upto 3 tera ions/sq. cm and decreases for higher fluence.

EM-O4

PREPARATION AND ELECTRICAL PROPERTIESOF Sm28Fe72, Sm32Fe68 FILMS

Kamala Bharathi K. and Markandeyulu G.Magnetism and Magnetic Materials Laboratory, Department of Physics, Indian Institute of Technology Madras, India

The electrical resistivity of Tb-Fe and Sm-Fe thin films are reported to increase with decreasingtemperature for certain composition range. This could be due the strain induced anisotropy that dominatesat low temperatures and lead to the development of in-plane anisotropy. Also the spin orbit interaction involvesin the scattering process. In the present case, preparation and the results of electrical resistance measurementsof Sm28Fe72, Sm32Fe68 films are reported. Sm28Fe72, Sm32Fe68 films were prepared by DC magnetronsputtering on glass substrates. A composite target consisting of Fe disc and Sm chips was used. The numberof Sm chips was varied to get different compositions of Sm and Fe. The sputtering conditions used were the

ISRS-2008 19

following: The base pressure was 5 10 6 Torr; Ar was used as a sputtering gas and the sputtering was

carried out at 4 10 3 Torr with a DC input power of 300 W. The XRD patterns of both the films revealedthat they were amorphous. Compositional analysis was carried out by taking spot EDAX at different placeson the film. Electrical resistivity measurements were carried out from 300 K to 20 K using Van der pawmethod. Resistance value was found to increase from 47.5 ohm (300 K) to 55.3 ohm (20 K) for Sm28Fe72film and for Sm30Fe70 film the value was found to increase from 22.6 ohm (300 K) to 27.9 ohm (20 K).

EM-O5

CHANGE IN ELECTRIC POLARIZATION WITHAPPLIED MAGNETIC FIELD AT ROOM TEMPERATURE

IN DY MODIFIED BiFeO3 THIN FILMSMandal M., Prashanthi K., Duttagupta S.P. and Palkar V.R.

Centre for Excellence in Nanoelectronics, Indian Institute of Technology Bombay, India

Multiferroic systems, which exhibit coexistence of both ferroelectric and ferromagnetic ordering atroom temperature, are of great importance for a variety of device application. At the same time it is alsoimportant to have presence of coupling between two order parameters since it gives additional degree offreedom in device designing.

In this paper, we present the change in ferroelectric polarization with varying magnetic field in pulsedlaser deposited multiferroic Bi0.7Dy0.3FeO3 (BDFO) thin films grown on Pt/Si substrate. Experimentalresults clearly show that as the magnetic field increases there is an improvement in ferroelectric hysteresisloops. This trend is identical to what is normally obtained with applied electric field. The observed changein ferroelectric polarization with applied magnetic field indicates that we have been able to orient ferroelectricdomains by means of applied magnetic field. It thus proves the coupling between magnetic and ferroelectricorder parameters in this system.

EM-P1

PREPARATION AND CHARACTERIZATION OF Nd2–xSrxCuO4

(WHERE x 0 to 0.2) CERAMIC COMPOUNDSAnbarasu V., Sathiyakumar S., Manigandan A., Kaliyaperumal L.K. and Jayabalan K.

Anna University, Chennai, India

The search of higher transition temperature on inorganic compounds introduces the newer researcharea “Ceramic Superconductors”. The search of newer ceramic superconducting compounds resulting withthe most productive research with TC around 40 K on La–(Ba/Sr)–Cu–O system. When substituting Ceriumand Strontium on the Nd2CuO4 system the compound Nd–(Ce/Sr)–Cu–O exhibits peculiar character ofn–type superconductivity and crystallize in two different crystal structures. Hence in the present work,Strontium substituted Nd2–xSrxCuO4 (where x 0 to 2) system have been synthesized through solid statereaction technique. Powder X – Ray Diffraction studies was carried out for the analysis of single phaseformation of the compound and it was revealed that variation on lattice parameters was linear with respectto the substitution element. The possibility of n – type superconductivity was observed at x 0.15 becauseof increase in lattice parameters causing increase in volume of the unit cell. Because of substitution of Srelement on Nd site induces a variation on crystal system from parent tetragonal to orthorhombic and the

20 ISRS-2008

lattice parameters were calculated as: a 3.945(3) Å to 3.987(6) Å, b 3.927(6) Å to 3.946(2) Å and c 12.16(1) Å to 12.09(1) Å. From the vibrating sample magnetometer studies it was found that all thecompounds exhibit paramagnetic nature. A peculiar case of getting saturation magnetization on the lowermagnetic field was observed for Nd1.85Sr0.15CuO4 and Nd1.8Sr0.2CuO4 compounds which shows the weakferromagnetic nature at room temperature condition. Electron Spin Resonance (ESR) and DiffusedReflectance Spectroscopy (DRS) studies were involved for the analysis of electronic structure and energygap values of the prepared compounds and results were discussed.

EM-P2

EFFECT OF UNI AXIAL PRESSURE ON Sm0.52Sr0.48MnO3SINGLE CRYSTAL

Murugeswari A., Arumugam1 S. and Mandal P. Bharathidhasan University, Thiruchirapalli, India

Doped manganite perovskites have been extensively studied because of their strong interactionsbetween spin, charge and orbital degrees of freedom. Single crystals of Sm0.52Sr0.48MnO3 were grownusing an optical floating zone surface. The quality of the crystal is checked by X-ray diffraction, electrondispersive X-ray analysis etc. Effect of uniaxial pressure upto 120MPa on the electrical resistivity along bothc axis and ab plane of Sm0.52Sr0.48MnO3 was investigated for a wide c(T,P) rapidly increases with ab(T,P),

range of temperature. Both decreasing temperature until the metal insulator transition temperature (TMI)is reached. The value of TMI is found to be 113K and it is extremely sharp and the sharpness does notappreciably decrease upto c, higher pressure range (P 120MPa). With increasing pressure along TMI shiftstowards lower temperature. The TMI decreases almost linearly with pressure. In contrast, TMI shifts towardshigher temperature with ab. The effect of pressure the application of uniaxial pressure along on electricalresistivity is strongest near TMI and it indicates that the FM to PM phase transition is first order in nature.

EM-P3

EFFECT OF ANNEALING AND THICKNESS ON STRUCTURAL ANDELECTRICAL RESISTIVITY OF FLASH EVAPORATED PBTE THIN FILMS

Kungumadevi L. and Sathyamoorthy R. Kongunadu Arts & Science College,Coimbatore, India

PbTe thin films of different thickness were prepared onto cleaned glass substrates under a pressure of

9 10 6 Torr by flash evaporation method. The deposited films were annealed at different temperatures in

the range 373 573 K in vacuum. The X-ray diffraction analysis revealed that the as-grown films of lowerthickness grow with the stable phase NaCl-type structure whereas films at higher thickness unpredictablyexhibits all phases of PbTe (fcc NaCl, bcc CsCl and orthorhombic GeS). Interestingly, upon annealing all thefilms exhibited hetero-phase of PbTe irrespective of film thickness. Growth mechanism of the prepared PbTefilms has been analyzed. The structural and lattice parameters of the films were calculated and they werefound to depend on thickness and annealing. Electrical resistivity was measured as a function of temperaturein the range 300-483 K and the energy gap was calculated from the Arrhenius plot. Both resistivity and bandgap have shown strong dependence on film thickness and annealing temperature. From the negative valuesof TCR, it is inferred that PbTe films have semiconducting behavior.

ISRS-2008 21

EM-P4

FABRICATION AND TEMPERATURE DEPENDENT I-VCHARACTERISTIC STUDIES OF n-ZnO / p-Si HETERO JUNCTION

Senthil Kumar E. and Ramachandra Rao M.S. Dept.of Physics, Indian Institute of Technology, Madras, India

ZnO is ideally suited for blue-ultraviolet (UV) optoelectronics and transparent electronics due to itsdirect and wide band gap (3.35 eV) and its ability to tailor electronic, magnetic and optical properties throughdoping, alloying and nano engineering. ZnO exhibits intrinsically n-type conductivity and achieving highquality, reproducible p-ZnO with sufficiently high mobility and hole concentration is difficult because of selfcompensation effects due to its native defects. Thus, realization of high quality ZnO based homojunctionlight emitting diode is still la challenging problem. In an alternate approach, ZnO based heterojunctions havebeen focused for short wavelength optoelectronics. As a result a number of heterojunctions such asn-ZnO/p-GaN, n-ZnO/p-SiC, n-ZnO/p-AlGaN, n-ZnO/p-NiO, n-ZnO/p-Si etc. have been fabricated tosuccessfully realize the UV electroluminescence (EL) and photo detection of ZnO.

n-ZnO thinfilm was fabricated on p-Si (100) substrate by pulsed laser deposition method at a substrate

temperature of 400 C and at pressure of 6 10 6 mbar. Al was deposited on back side of p-Si and top of

n-ZnO for top and bottom electrode. The junction area is defined as 500 500 m2 by UV-Lithographytechnique. I-V characteristic of the junction was measured at different temperatures (from 77 K to 300K).The junction shows very good rectifying characteristics at all temperatures. Turn-on voltage decreases from

9.6 V to 2.5 V and the saturation current increases from 5.7 10 5 A to 1.1 10 4 A as the temperatureincreases from 77 K to 300 K. There is a four order decrease in reverse leakage current at a reverse biasvoltage of – 7.5 V as the temperature increases from 77 K to 300 K. These results will be presented anddiscussed in detail.

EM-P5

DC CONDUCTIVITY OF ACTIVATED CARBON FILLED EPOXY GRADIENT COMPOSITES

Navin Chand and Archana NigrawalAdvanced Materials and Processes Research Institute (AMPRI),

(CSIR) (formerly RRL Bhopal) Hoshangabad Road, Bhopal, India

This paper reports the dc conductivity behavior of activated carbon powder filled epoxy gradientcomposites. Activated carbon powder filled epoxy composites having 3 wt. % of activated carbon powderand epoxy resin have been developed. dc conductivity measurements are conducted on the graded compositesby using an Electro-meter in the temperature range from 28 C to 150 C. dc conductivity increases with theincrease of distance in the direction of centrifugal force, which shows the formation of graded structure withthe composites. dc conductivity increases on increase in activated carbon powder content. Activation energywas calculated and showed ionic conduction in the composites.

22 ISRS-2008

EM-P6

COMBUSTION SYNTHESIS AND DIELECTRIC PROPERTIESOF Bi0.5Na0.5TiO3 - ZrO2 COMPOSITEKanagesan S., Velmurugan R., Jesurani S. and Kumar C.

SRM University, Chennai, India

Bismuth sodium zirconium titanate, a new class of ceramic composite powder was prepared bycombustion technique. Reactive metal nitrate and organic solvent are used as fuel. A yellow color precipitationwas obtained by slow evaporation of precursor solution at 90 C for 2 h. The final composition of powder is

Bi0.5Na0.5TiO3/ZrO2. The X-ray diffraction pattern BNZT composite calcined at 700 C shows the formationof mixed phases. The characteristic peaks for BiTi3O12, Bi0.5Na0.5TiO3, m-ZrO2 and BiTiO3 were recorded.The FTIR spectrum shows the absorption bands corresponding to N-H, NO2 and Zr-O) (O-C O). The DSC

shows the crystallization of zirconium oxalate gel into zirconia at 470 C and Sodium bismuth titanate phase

between 625 C to 700 C. From TGA analysis, the major weight loss of 29 % was predicted and the overallyield was calculated about 38 % of starting materials. The width and length of BNZT particle was measured170 nm and 550 nm by atomic force microscope. At higher frequency side (1 kHz to 100 kHz), the dielectricconstant (varies from 75 to 211) is more or less temperature independent and not much increase until 400 C.But, at lower frequencies (50 Hz to 100 Hz), the variation of dielectric constant is significant and attains themaximum value of 2200 at 400 C. The X-ray diffraction analysis of calcined powder indicated that the

addition of zirconia suppress the predominant reflection peak at 32.48 corresponding to pure bismuth sodiumtitanate (BNT) phase. For equal molar mixing of ZrO2 and BNT, zirconium exceeds the stabilization limits

and reduces the polarization contributed by Ti4 ion and hence the dielectric constant is reduced to a lowvalue as compared to pure BNT. The relaxation temperature was not predicted in the present composite until400 C. Therefore, the heavily zirconia doping suppress the formation of BNT phase and reduce the dielectricpermittivity value and increase the relaxation temperature.

ISRS-2008 23

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ET-O1

H OCCUPATION EFFECTS TO HYDROGEN STORAGE PROPERTIESIN BOTH AB5 AND AB2-TYPES HYDROGEN STORAGE ALLOYS

Liang Yuan, Qing Wang, Hai-bin Wang, Chuang DongDalian University of Technology

This paper investigates H occupations in both AB5 and AB2-type hydrogen storage materials, and alsoanalyses how different occupations effect hydrogen storage properties. H exists in both octahedron andtetrahedron interstitial sites in hydrids of LaNi5(AB5), but only occupies tetrahedron interstitial sites inhydrids of ZrV2. The enthalpy changes and lattice deformations of the cells are much different while Hoccupies various interstitial sites. The hydrogen storage properties are determined by both enthalpy changesand lattice deformations.

ET-O2

UNCONVENTIONAL LITHIUM INTERCALATION IN ACTIVE: INACTIVECOMPOSITE CATHODE FOR LI RECHARGEABLE BATTERIES

Sivaprakash S. and Majumder S.B. Indian Institute of Technology, Kharagpur, India

Intensive effort has been devoted to the synthesis of high energy density and stable positive cathodematerials for Li rechargeable batteries. For convention cathode such as lithium cobalt oxide, only about fiftypercent of theoretical capacity could be utilized due to the structural and chemical instability problem in deepdischarge. Capacity close to theoretical value could be achieved using unconventional lithium intercalationin layered composite cathode. With aim to study unconventional lithium intercalation along with conventionallithium intercalation in cathode material, layered composite cathode between two layered end membersLi2MnO3 and Li[Ni0.8Co0.15Zr0.05]O2 have been prepared by wet chemical route. The structural andelectrochemical properties of samples were investigated using XRD and galvanostic charge dischargemeasurement respectively. X-Ray photoelectron spectroscopy has been used to investigate valance changeof transitional metal ion during extraction and insertion of Li+ to the cathode. The analyses indicate that Mn4+

ion in the novel cathode (with unconventional lithium intercalation) does not change its valance state evenafter charging above > 4.6 V. further oxygen evolution during overcharging only meet the requirements ofexcess lithium intercalation in this type of layered composite cathode.

ET-O3

COMPARATIVE STUDIES OF WATER UPTAKE AND PROTONCONDUCTIVITY OF SPEEK AND SPEEK/PES BLENDS

Mahesh Arigonda, Abhijit P. Deshpande, Susy VarugheseDepartment of Chemical Engineering, Indian Institute of Technology Madras,India

Water uptake and proton conductivity are the important parameters to characterize a polymerelectrolytic membrane (PEM) for fuel cell applications. Membranes are prepared by blending sulfonatedpoly (etheretherktone) (SPEEK) and poly (ether sulfone) (PES) using N-methyl-2-pyrrolidone (NMP) and

24 ISRS-2008

Dimethylacetamide (DMAc) as solvents. PES is added in the blend to decrease the water upake and optimizethe mechanical stability of the membrane. SPEEK membranes of different degree of sulfonation (DS) wereprepared. Blend membranes were prepared by using SPEEK of DS 71% with varying weight percentage ofSPEEK/PES (50/50 to 100/0). Water uptake, Ion Exchange capacity (IEC) and proton conductivity of theblend membranes are characterized and a comparative study has been done with SPEEK.

ET-O4

STUDY OF TI-FE-V HYDROGEN STORAGE ALLOYS AND AN IDEALBCC SOLID SOLUTION STRUCTURE BASED ON

CLUSTER-PLUS-GLUE-ATOM MODELHai-bin Wang, Qing Wang, Liang Yuan, Chuang Dong

Dalian University of Technology

This paper investigates the hydrogen-storage properties of (Fe4/13Ti9/13)100-xVx (x 10-50 at. %)alloys which are designed by using our cluster line approach. These alloys are prepared by arc melting bycopper mould suction-casting (suction-cast) method. The hydrogen absorption and desorption measurementsindicate that the suction-cast BCC alloy (Fe4/13Ti9/13)50V50 possesses the optimum hydrogen absorptioncapacity with the maximum hydrogen content of 3.46 wt. %. Furthermore, an ideal BCC solid solutionstructure based on cluster-plus-glue-atom model is given.

ET-O5

DETERMINATION OF SAG IN GAS DIFFUSIONLAYER USED IN PEM FUEL CELL

Vijay R. and Prathap HaridossDept.of Metallurgical & Materials Engg, Indian Institute of Technology, Madras, India

Gas Diffusion Layer (GDL) along with flow field plays the role of distributing the reactants uniformlyin the active area of the fuel cell. Carbon paper and cloth are the two different media that are commonly inuse as a GDL. These diffusion media sag in the fuel cell flow channels. Quantifying the sag becomes importantas affects the performance of the cell. This paper determines the sag in a diffusion medium quantitatively.

For sag measurement experiments flow field templates with channel width ranging from 1 mm, 2mmand 3mm were machined. Experiments were conducted for both carbon paper and carbon cloth. The sampleswere aged for 300 hours in two different environments. One in a humidity chamber at 60 C, 95% relative

humidity and other was in water at 60 C. Sag measurements were made by recording the micrographs of thesamples along with the template which gives the sag profile.

The results show that GDL sag occurs in the samples aged in liquid water, indicating that presence ofliquid water in the cell favors sag of diffusion medium. In comparison with carbon paper, carbon cloth exhibitsmore sag. Increase in channel width increases in sag in all the cases tested.

The experimental procedure used to quantify the sag, and the implications of the results for fuel celltechnology development are discussed.

ISRS-2008 25

ET-P1

PREPARATION AND CHARACTERIZATION OF InTeTHIN FILMS FOR SOLAR CELL APPLICATIONS

Matheswaran P. and Sathyamoorthy R.Kongunadu Arts & Science College, Coimbatore, India

III-VI semiconductor compounds have more attention due to its optoelectronic properties and findsapplications in solar cells, gas sensors, pressure transducers and IR detectors. InTe thin films were prepared

by sequential thermal evaporation of pure material at a pressure of 2 10 6m.bar. Structural, optical, surfacemorphology and elemental composition of prepared films were analyzed by XRD, UV-Visible Spectra,scanning electron microscopy and energy dispersive X-ray Spectroscopy respectively. Variation of band gapenergy with different film thickness and substrate temperature were discussed on the basis of phase transitionand defect formation. Optical studies reveals that the absorption co-efficient is very high and is effective invisible region. Hence it is suitable for preparation of absorber layer in solar cells.

ET-P2

NOVEL GOLD-MANGANESE DIOXIDE-MULTI WALLED CARBONNANOTUBE ELECTROCATALYST FOR PROTON EXCHANGE

MEMBRANE FUEL CELLImran Jafri R. and Ramaprabhu S.

Dept.of Physics, Indian Institute of Technology, Madras, India

Recently polymer electrolyte membrane fuel cells (PEMFC) have drawn considerable attention as a cleanenergy conversion device due to its high energy conversion efficiency. The major challenge in thecommercialization of PEMFC is the cost of Platinum electrocatalyst and the effective utilization of the Pt. Thefocus is the development of Pt-free electrocatalysts for the oxygen reduction reaction in PEMFC. In the presentpaper, we report the synthesis of the gold-manganese dioxide nanocrystals supported on multi walled carbonnanotubes (Au-MnO2/MWNT) and use of the same as electrocatalyst for oxygen reduction reaction in PEMFC.MWNT have been prepared by the catalytic chemical vapor deposition technique and functionalized (f-MWNT)using acid treatment. Au-MnO2 was dispersed on the surface of the f-MWNT by chemical method. Theas-prepared catalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) andTransmission electron microscopy (TEM). Electrodes and membrane electrode assembly were prepared andpolarization measurements for single cell have been performed. The results indicate that Au-MnO2/f-MWNTshow good catalytic activity and stability for oxygen reduction reaction (ORR) in PEMFC.

ET-P3

PHOTOCATALYTIC HYDROGEN PRODUCTION FROM WATER USINGNOBLE METAL DOPED NANO TiO2

Kumaresan A., Prabhu L., Palanichamy M. and Murugesan V.Anna University, Chennai, India

Photocatalytic water splitting into H2 and O2 using semiconductors as a photocatalyst has receivedmuch attention, especially for its potential application to direct production of H2 for clean energy from waterutilizing solar energy. The photoelectrochemical effect of the semiconductor originates from the creation ofelectrons and holes after absorption of light. Since the discovery of photocatalytic splitting of water in a cell

26 ISRS-2008

consisting of Pt and TiO2 electrodes under a small electric bias [1], the photoassisted production of hydrogenand oxygen from water offers an extremely promising method for clean, low-cost and environmentallyfriendly conversion of solar into chemical energy. Numerous efforts have been made for the construction ofefficient and practical systems in the production of hydrogen from water splitting reaction [2,3].Silver, Goldand Platinum metal doped nano TiO2 were synthesised under sol-gel method. The presence of 100% anatasephase was confirmed from XRD analysis. The synthesised materials are characterized by SEM, BET surfacearea analysis, UV-vis DR spectra analysis. The presence of highly porous spherical like sphere was capturedfrom FESEM analysis. All the synthesised materials were tested for photocatalytic water splitting to generatehydrogen under ultra violet and visible light irradiation.

ET-P4

CARBON NANOSTRUCTURES AS COUNTER ELECTRODEMATERIAL FOR DYE SENSITIZED SOLAR CELL

Adarsh K., Arockiadoss T. and Ramaprabhu S.Dept.of Physics, Indian Institute of Technology, Madras, India

Dye-sensitized solar cells (DSSC) are considered to be low cost alternatives for the conventional Siliconsolar cells. However, their efficiencies and long term stability still need to be improved upon, if they are to becomecommercially viable. In DSSC, a thin film of Platinum coated on conductive glass substrate (ITO) is used as acounter electrode material. However considering the cost and scarcity, Pt must be well utilized for the improvementof performance. Recently, Carbon based materials such as carbon black have been employed as alternatives to Ptwith comparable efficiencies. Carbon nanotubes (CNT) and Graphene have excellent electrical conductivity andare also excellent catalyst support materials. Hence, these materials seem to be good alternatives for Pt. Howeverbetter performance can be expected if we combine the properties of Pt and carbon based nanostructures. Thepresent work focuses on the investigation of increase in the efficiencies by the use of Pt nanocrystalline decoratedCNTs and graphene. MWNT have been synthesized by chemical vapor deposition technique and Graphene havebeen synthesized by exfoliation of graphitic oxide, followed by functionalization using concentrated acid.Pt-MWNT and Pt-f-graphene have been prepared by chemical method. DSSC have been fabricated and theperformances have been investigated. The results have been discussed and the role of Pt-MWNT and Pt-Grapheneas efficient counter electrode materials has been explored.

ET-P5

EFFECT OF CROSSLINKING DENSITY ON RHEOLOGY OFCROSSLINKED POLY VINYL ALCOHOL/SSA

Kanakasabai P.Indian Institute of Technology, Madras, India

Sol gel transitions are very important in materials processing. Gelation of crosslinking polymers is ofinterest during polymer processing. The gelation reactions of poly vinyl alcohol (PVA) in the presence ofcross-linker sulfosuccinic acid (SSA) have been monitored through dynamic mechanical experiments.Concentration of crosslinker (SSA) was varied from 0-30 wt %. The gel point (tg) for these chemically gellingsystems was determined. The dynamic storage modulus (G1) and loss modulus (G11) have been measuredfor different cross-linker concentration. Stress relaxation measurements on gelling PVA systems were alsocarried out. The structure of the network and the gel strength will depend on factors such as concentrationsand temperature. The frequency dependence of the viscoelastic properties at the gel point is an importantconsideration. The gelation of PVA-SSA, which is an ionic polymer, will be compared with non-ionic polymersuch as PVA-glutaraldehyde.

ISRS-2008 27

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FO-O1

TEXTURE AND MICRO STRUCTURAL EVOLUTIONOF PURE MAGNESIUM DURING ECAE

Somjeet Biswas, Satyaveer Singh D., Satyam SuwasIndian Institute of Science, Bangalore, India

Initially hot rolled commercially Pure Magnesium having a basal texture was deformed by EqualChannel Angular Extrusion (ECAE) in a 90 die following routes A and Bc. Texture and microstructureevolution were studied using electron back scatter diffraction (EBSD) technique in a field emission gun (FEG)scanning electron microscope (SEM). In addition to significant reduction in grain size, strong <0002> fibertexture inclined at an angle ~ 45 from the extrusion axis formed in the material. Texture was also analyzedby orientation distribution function (ODF) and compared vis-à-vis ideal shear texture. A slightly rotated Band C2 fibers were observed after each ECAE pass. A significant amount of dynamic recrystallizationoccurred during ECAE, which apparently did not influence the deformation texture.

FO-O2

STRETCH BENDING STUDIES OF SHEET METAL– A NEW ATTEMPT USING RUBBER

Ganesh Niranjan G., Sri Harsha and Venugopal P. Dept.of Metallurgical & Materials Engg, Indian Institute of Technology, Madras, India

Bending of sheets assumes significant role in Sheet Metal Working besides deep drawing and cutting.Bending is classified according to tool motion among which press brake bending is very popular. In V andU bending of sheets in press brake, bending originates by moment and thus one finds what is called as “Freebending force”. Free bending force is of academic interest only since, a major problem of spring back isencountered. To correct the spring back, a simple die bending (of industrial importance) which applies a load(varying in the range of 10 to 100 times the free bending force) is recommended. This die bending force hasits own attendant demerits – to cite a few, over stressing of the tools, possible breakage of “C” type pressbrake, defeating the deformation efficiency (since losses vary as the square of the force) etc. Engineeringbending strain (under plane strain condition) is given as the ratio of thickness of sheet to twice the radius ofthe tool. Thus, for a thin sheet bent over a large radius (such as aerofoil) the strain will be so small that, afterbending is done, large spring back is likely to be encountered. Stretch bending involves gripping the endportions of the sheet by giving an initial small percentile load so that, the entire sheet is already in the plasticstage. A form tool then plunges to generate the necessary shape. As the neutral axis is shifted away from theplane of the sheet, the spring back is thus minimized or eliminated. This being the reason for evolution ofstretch bending, various designs for initial stretching the sheet followed. Such clamping tools and machinesinvolving many actions are very expensive.

The present work which is a preliminary attempt in nature, employs rubber of 85 shore hardness forclamping to ensure initial stretching and then V bending is done up to the termination of the free bending.By varying the layers of rubber (to ensure different initial stretching forces) and varying the V bending tools(to ensure different bending strains) the bent aluminium samples are examined for their spring back. Springback with conventional conditions (without stretching) is compared with those obtained through stretch

28 ISRS-2008

bending. The optimal conditions for minimal spring back by stretch bending with rubber are examined. Thesimplicity of the tooling using rubber for initial stretching and its host of advantages for industrial applicationare contained in this paper.

FO-O3

ANALYSIS OF STRESSES IN HYDRODYNAMIC DEEP DRAWING PROCESS

Uday kumar R.*, Ravinder Reddy P**. and Sitaramaraju A.V.*Dept.of Mechanical Engg. Mahatma Gandhi Institute of TechnologyGandipet Hyderabad, India

Dept.of Mechanical Engg. Chaitanya Bharathi Institute of Technology ,Gandipet Hyderabad, IndiaDept.of Mechanical Engg. JNTU College of Engineering, Kakinada, India

A new method, named hydrodynamic deep drawing assisted by radial pressure is suggested in placeof the conventional hydrodynamic deep drawing process (HDD); where in the radial pressure is loaded alongthe blank rim to reduce the drawing force. The radial pressure which is generated in the fluid due to punchpenetration in the fluid chamber is directed to the circumference of the blank to reduce the tensile stressacting on the wall of the semi drawn blank. As a result of the combined effect of counter pressure and radialpressure. High pressure fluid is directed to the peripheral surface of the blank through bypass holes. Thishigh pressure leaks out the blank and both the blank holder and the die. This creates a thin film of fluid onboth the upper and lower surfaces of the flange and subsequently reduces the frictional resistance. In thisphenomenon the shear stress of the fluid and viscosity is to be considered for evaluation of various parameters.The optimum parameters were studied so that the flange wrinkling and fracture can be predicted andcontrolled effectively. In this analysis radial stresses, hoop stresses and shear stresses along with the viscosityare investigated and also these parameters effects with the geometry of blank and process parameters. Theseinvestigations are obtained through theoretical analysis.

FO-O4

RING COMPRESSION TEST AND PLASTIC POISSONSRATIO ON WARM EXTRUSION OF SINTERED POWDER

METALLURGICAL (P/M) PERFORMS OF STEELChakravarthy P., Uday Chakkingal, Venugopal P.

Dept.of Metallurgival & Materials Engg, Indian Institute of Technology, Madras, India

A simple ring compression test had been carried out on sintered performs of steel at various residentdensities to assess the coefficient of friction. These tests were carried out at different temperatures and thevalues of coefficient of friction were used for theoretical estimation of extrusion forces. The sintered preformswere subjected to extrusion at different temperatures and the experimental forces required were recorded. Acomparison of the experimental values and theoretical values showed that the actual forces were greater thancalculated forces. The preforms were also subjected to compression test to analyze the plastic poissons ratioat various resident densities at different temperatures. Some useful inferences with coefficient of friction andplastic poissons ratios are discussed. The poissons ratios of resident preform densities and extrudes at differenttemperatures were compared to characterize the enhancement in densities due to deformation and temperatureassisted sintering at warm working conditions.

ISRS-2008 29

FO-O5

COMPUTER AIDED MODELLING OF METAL FLOWINVESTIGATION OF SQUARE BILLET TO SQUARE SHAPE

THROUGH BEZIER SHAPED CURVED DIESRout A.K. and Maity K.P.

National Institute of Technology, Rourkela, India

Extrusion plays a predominant role in the metal forming industry because of its improved mechanicalproperties and higher productivity. It is usually noted that the extrusion is conventionally carried out with thehelp of the shear faced dies. In these die metal is forced to go through a sudden change in cross-sectioncausing some practical problems such as formation of dead metal zone, non-uniformity in metal flow andmore redundant work, etc. To overcome these problems, extrusion dies are modified as streamlined extrusiondies for smooth flow of material die. The present investigation has been done for the streamlined extrusiondies designed based on a Bezier die profile. The velocity components and strain rates along x, y, and zdirections are determined by upper bound method using dual stream function. The velocity components andstrain rate of metal flow along x, y and z directions are determined in the dead metal zone. It is observed thatthe velocity components Vx, Vy and Vz as well as strain rate components (both direct and shear) vary alongthe die length. The variations are plotted with respect to non-dimensional die length for different reductionsand friction factors.

FO-O6

CHANGES IN DEFORMATION TEXTURE AND PLASTIC ANISOTROPY WITH TEMPERATURE FOR AA6016

Manojit Ghosh1,2, Alexis Miroux1, Jurij Sidor1, Leo Kestens2

1Materials Innovation Institute, Delft, Netherlands2Delft University of Technology, Delft, Netherlands

The use of aluminium alloys in automotive industry is restricted because of poor room temperatureformability in spite of their high strength to weight ratio and corrosion resistance. Tensile, plane straincompression and deep drawing tests have been performed to investigate the forming behaviour of AA6016alloy at room temperature and 250 C. It has been observed that temperature significantly influences theplastic anisotropy of the sheets apart from expected reduction of yield strength. The earing profile of drawncups show a four-fold symmetry after drawing at room temperature and the r-value is minimum along adirection at 45 from RD. At higher temperature the earing profile changes to 2-fold symmetry and the r-valueis minimum along RD. It has been noticed that texture changes after plane strain compression and deepdrawing compared to as-received texture but the effect of temperature is negligible on textural changes. Theexperimental R-value and textures are well predicted by the VPSC model using {111}<110> slip system atroom temperature and {111}<111>, {110}<110> and {100}<110> slip systems at 250 C.

30 ISRS-2008

FO-P1

ANALYSIS OF ROUGHNESS AND FLANK WEAR IN TURNING GRAYCAST IRON USING CRYOGENICALLY TREATED CUTTING TOOLS

Ramji B.R., Narasimha Murthy H.N. and Krishna M.R.V. College of Engineering, Bangalore, India

The purpose of this research was to examine the surface roughness, flank wear in turning gray castiron using cryogenically treated inserts. Turning experiments were conducted with cutting velocities: 53, 85,99, 149 m/sec, feeds: 0.12, 0.16, 0.2, 0.24 mm/rev and a constant depth: 1.5 mm. The specimens were turnedusing cryogenically treated and non-treated carbide inserts. The cryogenic treatment cycle consisted ofcooling the test samples from room temperature to cryogenic temperature(–178.9oC) in three hours, soakingat cryogenic temperature around 24 hours and warming to room temperature in about five hours. The surfaceroughness (Ra, Rz, Rq and Rt m) of the cast iron surface was measured using talysurf and flank wear of the toolwas measured using toolmakers microscope. The experimental lay-out was designed based on Taguchi’sOrthogonal Array technique and ANOVA was performed to identify the effect of the parameters on the responsevariables. Cryogenically treated inserts proved superior to the non-treated in all the test conditions in terms oflesser flank wear of the inserts and reduced surface roughness of the specimens. The after turned inserts wereexamined using Scanning Electron Microscopy for studying the flank wear mechanism.

FO-P2

TEXTURE AND MICROSTRUCTURE EVOLUTION ININTERSTITIAL-FREE STEEL WIRES PROCESSED

THROUGH EQUAL CHANNEL ANGULAR EXTRUSIONSuresh K.S, Fundenberger J.-J. and Satyam Suwas

Indian Institute of Science, Bangalore, India

Interstitial Free Steel (IF Steel) wires were drawn at room temperature from samples annealed at 1023 K for3Hr as well as from Equal Channel Angular Extruded (ECAE) material at 573 K. Texture evolution was analysedboth by X-ray diffraction as well as Electron Back Scattered Diffraction (EBSD). Further, the changes in GrainBoundary Character Distribution (GBCD) of the samples during different routes are also reported. Significance ofStrain Path Changes (SPC) during wire drawing from different routes on grain refinement and texture was examined.Torsion properties of the processed wires with different numbers of ECAE passes were compared.

FO-P3

FAILURE ANALYSIS OF SUPERPLASTIC FORMING / DIFFUSIONBONDING PROCESS (SPF/DB) ON ALUMINIUM ALLOYS DURING

EXPERIMENTATIONGanesh P., Senthil Kumar V.S., Natarajan S., Kalaichelvan K.K.

Madras Institute of Technolgy, Anna University,Chennai, India

Superplastic forming is a high temperature deformation process where neck free elongations of over

400% at low applied stress, half the melting point and low strain rate of about 10 5 to 10 3 s-1are formed.Diffusion bonding is a solid state bonding process capable of joining wide range of metals. During recent

ISRS-2008 31

years SPF/DB is applied in fabricating complex parts has increased in the automobile and aircraft industry.The purpose of this research work is to analyze the formability of hemispherical bonded shaped part, reducecost, weight and tooling. This work focuses on Chronological change in dome height of the formedcomponent, thickness distribution and bonding two sheets of different thickness using SPF/DB process fora hemispherical shape under controlled conditions. The controlled parameters were forming time,temperature and applied pressure. The experiment was carried out for different combinations of pressure,temperature and time and the forming height and bonding thickness were observed. A continuous trial byvarying the parameters, uniform bonding and complete hemispherical forming was achieved by appropriatepressure, temperature and time. The responses such as forming height and bonding thickness were analyzedusing ABAQUS.

FO-P4

EXPERIMENTAL STUDIES ON THE SUPERPLASTIC FORMING OFTi-6Al-4V SHEET METAL INTO SQUARE SHAPED CUPS

Rayudu R.K., Bhattacharya S.S., Deepkumar V.P.Dept.of Metallurgical & Materials Engg, Indian Institute of Technology, Madras, India

Superplasticity is the ability of a polycrystalline material to exhibit, in a relatively isotropic manner, largeelongations when deformed in tension. This property is exploited during superplastic forming in the fabricationof complex-shaped components which are otherwise technically difficult or economically costly to form byconventional methods. The ability of some titanium alloys to undergo superplastic deformation coupled with theirdiffusion bonding capability provides excellent opportunities to fabricate intricate parts in one operation resultingin significant cost and weight savings, particularly in the manufacture of aerospace structures.

In the present work, experimental studies to characterize the superplastic behavior of an as-receivedtitanium Ti-6Al-4V alloy sheet metal commonly used in aerospace structural applications are reported. Theraw material sheet metal stock was characterized for the chemical composition and room temperaturemechanical properties. The raw material was also subjected to tensile tests under superplastic conditions toconfirm its ability to undergo superplasic deformations. Suitable dies, for superplastic forming of 80 mm 80 mm square and 50 mm deep cup specimens, were designed and fabricated including die inserts whichfacilitated the forming of square cup specimens of different depths. Alloy sheet specimens weresuperplastically formed at a temperature of 1200 K (927 C) and 0.7 MPa constant pressure to differentdepths. The superplastic forming rates were monitored throughout the process. The superplastically formedcomponents were characterized for their thickness distribution, mechanical and metallurgical properties.

FO-P5

EFFECT OF PROCESSING ROUTES ON MATERIAL FLOW AND STRAININHOMOGENIETY IN EQUAL CHANNEL ANGULAR PRESSING

Patil Basavaraj V., Uday Chakkingal and Prasanna Kumar T.S. Dept.of Metallurgical & Materials Engg, Indian Institute of Technology, Madras, India

Investigations are currently focused on Equal Channel Angular Pressing (ECAP) because of itspotential to produce ultra fine-grained microstructures in metals and alloys. Ultra-fine materials exhibitsuperior mechanical properties such as high strength and ductility. Many parameters contribute to theinhomogeneity in the resulting work-piece. Among other process parameters the processing route has great

32 ISRS-2008

influence on the distribution of strain and resulting inhomogeneity in the work-piece. This influence can be studiedby Finite Element Modelling. In the present work 3D Finite Element Modelling of ECAP process was carriedout using the ABAQUS / Standard software for four passes in routes A, B and C.A cylindrical work-piece ofdiameter 20 mm and length 105 mm was considered. Channel intersection angle was 105 degree. Strain hardeningbehaviour of Aluminium alloy AA 6101 was used. Strain obtained from the previous pass was given as initialcondition for the subsequent pass. The results presented are useful for understanding the effect of processingroutes on the material flow and the strain distribution. It is also useful for selection of the best route.

FO-P6

STRAIN HARDENING BEHAVIOUR OF WARM ECAP PROCESSED Cp-TiPreetham Kumar G. V. and Uday Chakkingal

Dept.of Metallurgical & Materials Engg, Indian Institute of Technology, Madras, India

Superior properties for structural applications of CP-Ti can be attained through multiple passes of equalchannel angular pressing (ECAP). ECAP is a procedure which involves large simple shear plastic deformationwithout a resultant change in cross sectional area. In the present study, the specimens of CP Ti were extruded tothree passes through an ECAP die with 17mm diameter and an angle of 120o between the two intersectingchannels. All the equal channel angular pressings were carried out at 400oC. Compression and tensile tests wereconducted on the specimens subjected to different passes. The strain hardening behaviour of the CP-Ti materialwas evaluated as a function of the number of passes from the compression test data. Significant strengthening andgrain refinement were observed. The variation of strain hardening rates were calculated as a function of the appliedstrain and this was correlated to the microstructure developed during ECAP.

FO-P7

EFFECT OF MICROSTRUCTUAL AND MECHANICAL PROPERTIESOF Al 2014 ALLOY PROCESSED THROUGH ROUTE A AND BA

Venkatachalam P., Ravisankar B., Thamos Paul*V., Vijayalakshmi*M. and Kumaran S. Department of Metallurgical and Materials Engineering, National Institute of Technology, Tiruchirappalli, India

An Al 2014 alloy has been subjected to equal-channel angular pressing up to five passes by routes A,and BA in a die with channel angle 90 and corner angle 20 . Microstructural and mechanicalproperties were compared for three different conditions namely (i) as received, (ii) solutionized at 768 K for1 hr and (iii) solutionised at 768 K for 1 hr aged at 468 K for 5 hr. Microstructural characterization wasdone using TEM and mechanical properties were evaluated by micro hardness and micro tensile test. Theimproved strength and hardness of ECAPed 2014 Al solutionised at 768 K for 1 hr aged at 468 K for 5 hralloy was due to the precipitation hardening, grain refining and higher dislocation density. However, nosignificant differences in tensile strength and hardness were found between the samples processed throughroute A and BA.

ISRS-2008 33

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JS-O1

OPTIMIZATION OF ZONE REFINING IN PREPARINGGALLIUM EXCEEDING 7N PURITY

Ghosh K., Mani V.N., Dhar S. and Balaraju K.Dept of Electronic Science, University of Calcutta, India

Computer simulation was carried out to optimize zone refining process parameters such as zone lengthand zone travel rate on the impurity concentration profile in the zone refined material ingot. Simulation studywas also used to ascertain the number of passes required to reach the ultimate distribution, which is theattainment of steady state at which no more reduction in impurity concentration takes place. It was alsostudied that stirring of the molten zone produced in the material undergoing the refining process will causeimprovement in impurity segregation enabling higher material purity. Based upon the optimization carriedout through simulation, experiment was conducted to purify gallium by a laboratory scale two-heater verticalzone refiner and a three-zone (hot, gradient and cold zone) Directional Freezing system. After conducting50 zone refining passes on the starting 5N2 (99.9992% pure) gallium, the refined metal was placed in theDirectional Freezing system where it is rotated at 20-35 rpm for effective stirring of the gallium melt. Galliumwas purified up to 7N2 (99.999992%) purity as analyzed by Glow Discharge Mass Spectrometry (GDMS).The total impurity concentration with respect to 24 impurities in gallium namely, Al, Cu, Ca, In, Ni, Si, As,Cd, Fe, Mg, P, Sn, Au, Co, Ge, Mn, Pb, Te, B, Cr, Hg, Na, S and Zn were reduced from 7764 ppb to less than77.7 ppb with an overall impurity concentration reduction efficiency of 99%. The details of instrumentationdifficulties and modifications are discussed.

JS-O2

STUDIES ON Ti-15V-3Cr-3Sn-3Al (Ti-15–3) METASTABLE-BETATITANIUM ALLOY WELDMENTS

Balachandar K., Sarma S., Bhanu Pant, Phanikumar G. Dept.of Metallurgical & Materials Engg, Indian Institute of Technology, Madras, India

In this work, an attempt has been made to understand the weldability of Ti-15V-3Cr-3Sn-3Al alloy.GTAW- DCEN with optimized argon flow in the torch, trailing and backup to reduce the oxidation was utilizedto weld samples. Continuous current and pulsed current with variable frequencies were experimented.Thermal history of the welds was studied using in-situ temperature measurements. Single step post weldaging of the welded samples were tried to achieve optimum microstructural properties. Pulsed currenttechnique was effective in reducing the grain sizes as well as the width of heat affected zone. Sub transusageing resulted in allotriomorphs along the grain boundary and lenticular network along the grains, with

predominant compositional variation between the matrix and laths.

34 ISRS-2008

JS-O3

EFFECT OF BORON ADDITION ON THE GRAIN REFINEMENT OFAz91 (Mg-9Al-1Zn-0.2Mn) MAGNESIUM ALLOY

Suresh M., Srinivasan A., Pillai U.T.S.* and Pai B.C.Materials and Minerals Division, National Institute for Interdisciplinary Science & Technology (CSIR),

Thiruvananthapuram, India

Exploitation of magnesium alloys have been increased significantly in the automotive industry becauseof their great potential in reducing the weight of the components thus resulting improvements in fuelefficiency of vehicles. Among the various Mg alloys, AZ91 alloy has the best combination of castability,mechanical strength and ductility. These excellent properties have made AZ91, as the most preferablemagnesium alloy for the production of light weight automobile components. The performance of thecomponents made by AZ91 alloy can be improved further by increasing its tensile properties, particularly,its yield stress. As it is well established that the yield strength is directly related with the grain size, it isessential to reduce the grain size of the cast alloy to a maximum extent to get a higher tensile properties.

It is well known that grain refinement can be achieved in the castings by several methods like fastersolidification, melt agitation, solute additions, etc. Due to simplicity and efficiency, solute addition as a grainrefiner has become more popular in casting industries. Generally, the grain refinement of Mg-Al alloys isachieved by introducing any of these additives such as Sr, RE, Th, Si, Ca, AlN, etc. into the melt. In the presentstudy, the grain refinement efficiency of boron in Az91 alloy is investigated. Boron addition (0.01 to 0.2 wt%) is carried out to Az91 using Al-4B master alloy and its effect and mechanism of grain refinement studiedis reported.

JS-O4

GRAIN REFINED BORON MODIFIED Ti-6Al-4V ALLOY:ROLE OF Ti-B COMPOUND IN TEXTURE EVOLUTION

Shibayan Roy Laboratory for Texture and Related Studies, Dept. of Materials Engineering, Indian Institute of Science,

Bangalore, India

Owing to their high strength-to-weight ratio, excellent mechanical properties and corrosion resistance,titanium (Ti) and its alloys, especially (alpha+beta) alloys like Ti-6Al-4V, are the backbone materials foraerospace, energy, and chemical industries. Pure titanium has hexagonal (alpha) crystal structure at roomtemperature, which transforms to bcc (beta) structure at ~885 C following specified orientation relationship.Based on this orientation relationship and the symmetries of cubic and hexagonal structures, a total of 12phase can result from the crystallographically distinct variants of grain. The basis for tailoring a

suitable transformation of single texture and microstructure during heat treatment of titanium alloys,

therefore, depends strongly on the to transformation. The same is applicable for (alpha+beta) titaniumalloys.Trace boron addition (~0.1 wt. %) to the alloy Ti-6Al-4V produces a reduction in as-cast grain size byroughly an order of magnitude. Special attributes of Boron addition includes enhanced ductility, higherstiffness and strength in addition to good fracture resistance. Recently, Ti-alloys have been produced byInduction skull melting (ISM) technique, which offers number of advantages in terms of improved ingotquality. Boron addition as well as ISM technique could affect the evolution of texture and microstructure inthe material. A research program has been developed in order to study different aspects of texture evolution

ISRS-2008 35

in ISM processed Boron modified Ti-6Al-4V.The solidification microstructure of Boron free as well as Boroncontaining Ti-6Al-4V after ISM processing are found to be almost homogeneous from periphery towards thecenter of as-cast ingot in terms of both -colony size and distribution. Boron addition substantially reduces

-colony size (~50-80 m). Needle shaped Ti-B particles texture fromsegregate at the grain boundary. Agradual change in periphery towards the center has been observed with orientations close to specific texturecomponents suggesting the formation of texture zones. The mechanism of texture evolution can be visualizedas a result of variant selection during solidification through (alpha+beta) phase field. A fine observation usinglocal area EBSD scans with very small step size supports the above preposition.

JS-O5

MELT RHEOLOGY OF BRANCHED POLYLACTIC ACIDDeenadayalan E., Naveen R., Lele A.K. and Balasubramanian M.

Indian Institute of Technology Madras, India

Polylactic acid (PLA), a biodegradable polymer which can also be produced from annually renewableresources, has recently gained growing attention. Branching and crosslinking of polylactic acid was carriedout in a Haake batch mixer using varying percentages of 2, 5-dimethyl-2, 5-di-(t-butyl peroxide) (Lupersol101) and a multifunctional epoxy based additive. Based on the extrusion temperature and the relative contentof peroxide/epoxy, branching, crosslinking, and chain scission can occur separately or simultaneously. Thetotal degree of branching (short and long chain branching) was determined by 13C NMR spectroscopy. Gelcontent was determined by Soxlet apparatus. The rheology of linear and modified poly (lactic acid) wasinvestigated in shear and uniaxial extensional modes. Time sweep experiments were performed on thesesamples at different temperatures to test the melt stability. Influence of branching and crosslinking on meltingtemperature and glass transition temperature was studied by using differential scanning calorimetry.

JS-P1

DIFFUSION BONDING OF Ti-6Al – 4 V WITH INCONEL718 WITHOUT AND WITH INTERLAYERS

Krishnamoorthi J., Balusamy V., Angelo P.C., Ravisankar B.PSG College of Technology, Coimbatore, India

Joints of titanium alloys with super alloys have wide applications like aerospace engine parts and fueltanks. Joining of these materials by conventional welding processes fails due to the formation of number ofintermetallics resulting embrittlement. Solid state diffusion bonding can minimize the structuralin-homogeneities and assures sound bond. Diffusion bonding is the joining of two nominally flat surfacesby the action of temperature and pressure. In order to avoid fusion, the temperature is chosen less than theabsolute melting temperature of the lower melting point material. Bulk plastic deformation is avoided bykeeping the bonding pressure well below the yield stress of the materials. The bond strength of the diffusionbonded joints can be further improved by inserting suitable material in between the two metals as interlayer.The present investigation attempts were carried out to bond Ti-6Al-4V with INCONEL718 without anyinterlayer and with interlayers like nickel and tantalum foils. The experiments were performed using speciallyconstructed diffusion bonding set-up with varying process parameters viz temperature from 500 to 900 C,bonding pressure from 2 to 10MPa and time from 1 to 5hrs. The relative importance of the process parameters,the mechanism(s) responsible for bonding and the joint characteristics were analysed by optical & electronmicroscopy and hardness survey across the interface. Energy Dispersive Spectroscopy analyses were also

36 ISRS-2008

carried out to understand the elemental distribution across the interface of the joints. The optimum processparameters for the perfect bonding of Ti-6Al-4V with INCONEL718 without and with interlayers wereidentified using the above test results. The influence of interlayer metals and the corresponding bondingconditions on the Ti-6Al-4V with INCONEL718 joints was also investigated.

JS-P2

EFFECT OF METAL-MOLD INTERFACE HEAT FLUX DISTRIBUTIONON MACRO SEGREGATION AND MICROSTRUCTURE

DURING GRAVITY DIE CASTINGSreenivas Rao K.V., Phanikumar G. and Prasanna Kumar T.S.

Dept.of Metallurgical & Materials Engg, Indian Institute of Technology, Madras, India

Experiments were conducted to study the effect of interfacial air gap formation on microstructure andmacro segregation of die-cast Al-4.5%Cu alloy. An experimental method which involved mold filling wasdesigned to accurately capture the thermal histories of the mold and casting. An IHCP algorithm was usedto estimate multiple heat flux components at the metal-mold interface. The estimated heat flux values showa spatial variation along the vertical length of the mold. The analysis indicates that the non-uniform air gapformation at the metal-mold interface leads to spatial variation of interface heat flux. The spatial variationof interface heat flux gives rise to spatial variation of microstructure and macro segregation. Fine grainedcolumnar structure was observed at the bottom of the casting near the mold wall whereas; coarse grains wereseen towards the top of the casting. The copper content decreases from bottom to top near the mold wall.

JS-P3

INFLUENCE OF GATING SYSTEM ON MICROSTRUCTUREAND MECHANICAL PROPERTIES OF MELT AND HEAT TREATED

CAST Al-7Si-0.35Mg ALLOYSwamy N.H.S., Ravi Naika, Josepha M.A., Nagarajan N.M. and Sateesh N.H.

National Institute Of Technology Calicut, India

In the present investigation the effect of low frequency mould vibration and the influenceheat-treatment parameters on microstructure and mechanical properties of modified cast Al-7Si-0.35Mg wt.% alloy in different sand moulds with two different runner designs/systems are studied. The microstructureand mechanical properties of the alloy are found to be affected significantly by the combined effect of mouldvibration and heat treatment in all the cases. Heat treatment produces greater refinement, uniform silicondistribution and formation of spheroids. Scanning electron microscopy of tensile fractured surface revealsthe influence of vibration and solution temperature on the mode of fracture. Among the different sand systemsused in the investigation, castings from dextrine chromium trioxide no-bake system sand mould yield castingswith better mechanical properties. A comparison of the influence of different moulds with two different runnerdesigns with vibration on the tensile strength of the alloy has shown that filtered rectangular runner (FRR)yield castings with higher and more reliable tensile strength than the unfiltered vortex flow runner (UVR)system.

ISRS-2008 37

JS-P4

CONTINUOUS DRIVE FRICTION WELDING OF INCONEL 718 – EN24DISSIMILAR METALS: EFFECT OF PRE-HEAT TREATMENT

Sree Vardhan Lalam, G. Madhusudhan Reddy, T. Mohandas, Kamaraj M. and Murty B.S. Dept.of Metallurgical & Materials Engg, Indian Institute of Technology, Madras, India

The microstructure and mechanical properties are compared for continuous drive friction weldedInconel 718 and EN24 dissimilar joints, in four different combinations of pre-weld heat treatment conditions.The dissimilar welds exhibited low strength and low toughness in all the combinations. The welds made withInconel 718 in solutionized condition resulted in formation of wide HAZ in EN24 than welds made withInconel 718 in annealed condition. At the weld interface diffusion of Fe from EN24 into Inconel 718 wasobserved for the welds made with EN24 in annealed condition and diffusion of Ni, Cr. Mo and Nb fromInconel 718 into EN24 was observed in welds made with EN24 in Q&T condition. The observed trends inmechanical properties are explained in relation to microstructure, fracture behaviour, EPMA, EDS and XRD.

JS-P5

EXPERIMENTATION, FEM AND STATISTICAL ANALYSIS FORPARAMETER OPTIMIZATION IN MIAB WELDING PROCESS

Arungalai Vendan S., Nagamani C., Manoharan S. and Buvanashekaran G.National Institute of Technology, Trichilapalli

The magnetically-impelled arc butt welding process (MIAB) is a solid state joining technique that usesarc heating of the components to be joined, the arc being struck between two tubular components, and thenmagnetically rotated rapidly around the circumference. The arc disrupts the surface oxides and softens theinterfacial material without necessarily melting it, and the components are then forced together to forge outthose oxides and leave only clean material in the joint. MIAB can reduce welding time by up to 90%, cut outthe need to rotate components and weld circular or non-circular components with the same ease. Any angularorientation can be welded. The process can be used to weld steels, stainless steel, aluminum alloys, etc. Inthis study, a laboratory MIAB welding module is designed and developed. Experimental trails are conductedto achieve the arc rotation by varying the input parameters. Further, finite element analysis is performed fordetermining the distribution of various parameters across the joint that governs the MIAB welding process usingfinite element code ANSYS. In addition, Statistical analysis is performed to determine the most significantparameter that governs the arc speed in MIAB welding. The results emphasizes that the welding current andmagnetic coil current importantly governs the arc rotation and also has a linear relation with the arc speed.

JS-P6

DISSIMILAR ELECTRON BEAM WELDING OF MARAGING STEELMDN 250 TO HIGH STRENGTH LOW ALLOY STEEL AIR 15CDV6

Venkateshwara Rao V., Madhusudhan Reddy G. and Sitaramaraju A.JNTU, Hyderabad, India

Recent advances in manufacturing processes using electron beam welding have led to increased useof advanced and dissimilar materials. Dissimilar metal joints are widely used in various industrial applicationsdue to both technical and economical reasons. The adoption of dissimilar metal combinations provides

38 ISRS-2008

possibilities for flexible design of the product by using each material efficiently i.e., befitting from specificproperties of each material in a functional way. In the aerospace scenario, ultra high strength steels such as18% maraging steel (MDN 250) and low carbon low alloy Cr-Mo-V steel (AIR 15CDV6) are widely usedin the fabrication of various critical components.

As there is a considerable difference between the costs of materials MDN 250 and AIR 15CDV6 steel,one of the ways to reduce the total fabrication cost of the component as well as taking the advantageous ofthe specific properties of each of them by adopting a dissimilar metal joining. The data on characteristicsdissimilar metal weldment will be extremely beneficial to the designers to generate a cost effective design.In the present work MDN 250 is welded to 15CDV6 material by using electron beam welding process. Thestudy consists of mechanical property evaluation such as tensile, impact and hardness coupled withmicrostructural examination. Influence of post weld heat treatments also forms part of the study. The postweld heat treatments investigated are quenching and tempering treatment i.e., employed for low alloy steel,post weld ageing at 4800C and post weld solution treating and ageing which is adopted for maraging steel.

Maraging steel welds exhibited lower tensile strength and toughness compared to as received solutiontreated parent metal. Post weld ageing, post weld solutionizing and ageing further reduced the impacttoughness, due to precipitation hardening. However, quenching and tempering treatment similar to thatemployed for the low alloy steel, which does not involve precipitation hardening experienced marginalreduction in toughness from the as-welded condition. AIR 15CDV6 welds exhibited low strength andtoughness compared to parent metal. The strength could be improved by quenching and tempering treatment.In tensile testing, all the failures of dissimilar welds are located outside the weld region.

Dissimilar welds exhibited low strength, low toughness compared to respective parent metal. Post weldheat treatment resulted in further reduction in toughness compared to that in the as-welded condition. Impacttoughness of dissimilar weldments is higher than similar welds. The observed mechanical properties arecorrelated with microstructure and fracture features. The study assumes special significance as studies onthese aspects are not reported hitherto our knowledge.

JS-P7

FRICTION WELDING OF AZ91D MAGNESIUM ALLOYGovindaraju M., Prasad Rao K., Uday Chakkingal, Balasubramanian K.

Dept.of Metallurgical & Materials Engg, Indian Institute of Technology, Madras, India

Magnesium alloys, one of the lightest commercially used alloys, have poor weldability by fusionwelding. Among that, AZ91C and D (Mg-9%Al-1%Zn) are work horse magnesium alloys, in which AZ91Dhas superior corrosion resistance. In this study, AZ91D magnesium alloy was subjected to friction weldingin various conditions like as cast and fully heat treated. For friction load of 45 MPa and upsetting load of 90MPa, sound joints with joint strength more than base metal were obtained. Welded microstructure revealsthat that the grain size is refined in the weld region, and the porosity is eliminated/ minimized. All theexperiments were carried out by using 15mm diameter samples. When the upsetting load exceeded 90MPa(1.6 ton), the samples started buckling. Welding speed was optimized in between 700 and 1100 rpm, wherebelow 700 rpm joint strength was inferior to base metal and more than 1100 rpm joints became more brittle.

ISRS-2008 39

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M1-O1

EFFECT OF GROOVE AT CONTACT EDGEON FRETTING FATIGUE BEHAVIOR

Jayaprakash M., Kimura N., Mutoh Y. and Yoshii K.Nagaoka University of Technology, Nagaoka, Japan

Fretting fatigue is a serious problem in engineering applications, where two components are in contact andsubjected to cyclic loading. In fretting fatigue, the fatigue strength degradation is due to the high stressconcentrations at the contact edge created by fretting action. If stress concentrations at the contact edge are reducedthen, fretting fatigue strength may be improved. Many research works have been published regarding decreasingthe stress concentrations by applying surface coatings and lubricants. But these methods found to be ineffectivein some critical applications. Recently it has been reported that one of the effective method to reduce the stressconcentrations at the contact edge is by modifying the specimen design by making stress relief grooves at thecontact edge. But the major drawback in this method is the increase in stress concentration at the groove root, sopossibility of failure may occurs at the groove root. It is necessary to optimize the groove dimensions to achievethe maximum improvement in fretting fatigue strength by making stress relief grooves.

In the present work the effect of groove, groove shape at contact edge on fretting fatigue behavior inan automobile steel was studied by performing fretting fatigue tests of specimens with grooves of differentgroove dimensions at the contact edge. From the result it was identified that the groove at the contact edgehas a significant effect on fretting fatigue strength. Finite element analysis was performed to evaluate thestress distribution around the contact and groove. The experimental results obtained were discussed basedon the stress distribution around the contact and groove.

M1-O2

MICROSTRUCTURE AND MECHANICAL PROPERTIES OF 16Cr-2NiSTAINLESS STEEL ELECTRON BEAM WELDS-INFLUENCE OF

SINGLE AND DOUBLE AUSTENITERajasekhar A., Madhusudhan Reddy G. and Mohandas T.

University College of Engineering, Osmania University,Hyderabad, India

The influence of single and double austenitizing treatments on microstructure and mechanicalproperties of electron beam welds of AISI 431martensitic stainless steel were studied. The post weld heattreatments consist of austenitizing the weld samples for one hour at 10000C, 10500C, and double austenitizedat 10500C 10000C and air cooling followed by double tempering i.e., tempering at 6700C 6000C. Theprior austenite grain size increased with increase in austenitizing temperature from 10000C to 10500C. Grainrefinement resulted after double austenitization. Parent metal grain size was coarser as compared to grainsize in the weld zone in respective conditions. Retained austenite content increased after doubleaustenitization. Presence of undissolved carbides was observed in welds and parent metal austenitized up to10000C and they dissolved at austenitizing temperature 10500C. Double austenitization (DA) treatmentresulted in dissolution of most of the carbides. Coarsening of martensite laths was observed after tempering.Double austenitization (DA) after double tempering resulted optimum mechanical properties i.e., strength,hardness and toughness.

40 ISRS-2008

M1-O3

FLEXURAL FATIGUE BEHAVIOR OF LONG TERM EXPOSEDNYLON 66 TO MOISTURE

Timmaraju V. Mallina, Gnanamoorthy Rajappaand, Krishna KannanMachine Design Section, Dept.of Mechanical Engg, Indian Institute of Technology, Madras, India

Aim of present study is to understand the effect of water content absorbed during the long term exposureto different surrounding environments on fatigue behavior of nylon 66 under 50% and 100% relative humidityconditions. Injection moulded nylon 66 samples of 4 mm thick are conditioned in water under ambientconditions to get varied weight percentage of water content till saturation. Flexural fatigue tests are performedunder displacement control using a specially developed compact close controlled fatigue test rig at afrequency of 2 Hz. Initial set of experiments are conducted under ambient conditions of 28 C and 50% relative

humidity and later are conducted under 28 C and 100% relative humidity conditions to distinguish the natureof fatigue experienced by the specimens containing same weight percentage of moisture in different testenvironments. Two extreme natures are observed when dry samples (< 0.2%) tested in 50% RH and saturatedsamples tested in 100% RH for a particular displacement amplitude. Dry specimens tested in 50% RHexperienced severe cyclic softening while temperature of the specimen is rising with very high approximateinitial stress amplitude of 65 MPa. Saturated specimens tested in100% RH experienced no cyclic softeningduring the test with extremely less stress amplitude of 20 MPa on average due to severe plasticization uponwater absorption. Dry specimens in 50% RH are influenced by Tg as well during the test and experiencedfatigue failure with smooth regular striations on fracture surface. A very high fatigue life is observed forsaturated samples due to plasticization effect of water which results in very low induced stresses.

M1-O4

MICROSTRUCTURAL EFFECTS ON THE MECHANICAL BEHAVIOROF BORON MODIFIED Ti-6Al-4 V ALLOYS

Indrani Sen and Ramamurty U.Indian Institute of Science,Bangalore, India

Conventionally cast Ti-6Al-4V alloy possesses coarse grain size of several mm. Extensive andexpensive thermomechanical processing is needed to refine the structure. However, small amount of Badditions (< 1 wt.%) refine the as-cast grain size by an order of magnitude, hence improve their mechanicalperformance. In this work, we report the effect of microstructural refinement, achieved through systematicB additions from 0.0 up to 0.55 wt.% B on the mechanical behavior of as cast Ti64 alloys. These includetensile properties, fracture toughness as well as un-notched and notched fatigue strength and crack growthrespectively. Experimental results show about 10 % increment in the tensile strength due to microstructuralrefinement. However, a gradual reduction in threshold for fatigue crack initiation is noticed depending onthe square root of the microstructural length. Stress-controlled high-cycle-fatigue experiments reveal anenhancement in the endurance limit of the alloy with B addition, primarily due to the microstructuralrefinement. However, intermetallic TiB formed due to B addition, affects the crack initiation. Thestrain-controlled low-cycle-fatigue shows variation of the degree of cyclic-softening andtension-compression asymmetry with B addition.

ISRS-2008 41

M1-O5

EFFECT OF PROCESS VARIABLES ON STRUCTURE ANDPROPERTIES OF Al-Si-Mg ALLOYS

Siddalingaswamy N.H., S.Raghavendra Kumar, Joseph M.A., Nagarajan N.M. and Sateesh N.H. National Institute of Technology, Calicut, India

Among the different variants under Al-Si alloy system, Al-Si-Mg alloy has received wider acceptancein aerospace and allied industries particularly owing to its high strength to weight ratio, good machinabilityand corrosion resistance. Many researchers and material scientists have been endeavouring over the past fourdecades, for effective process variations towards achieving improved mechanical properties of this alloy. Thispaper presents the results of investigations carried out on the effects of heat treatment in cast alloys, on majormechanical properties such as tensile strength, ductility and hardness. Al-Si-Mg alloys with 7, 12, 16 %Wt.silicon and cast with modification, combined modification & vibration and heat treatment were testedadopting standard testing procedure have been compared. Samples cast with modification, vibration duringsolidification and heat-treated exhibit relatively better mechanical properties. Optical microscopy study ofthese samples show enhanced Spheroidisation and uniform distribution of eutectic silicon crystals particularlyat higher solutionising temperature. Scanning Electron microscopy slides clearly indicate while modifiedalloys show predominantly cleavage fractured surface and modified and vibrated alloys a mixture of cleavageand dimple fractured surfaces, samples with modification, vibration and heat treatment exhibit predominantlydimple fractured surface.

M1-P1

EFFECT OF PARAMETERS ON MECHANICAL PROPERTIESOF AUSTENITIC STAINLESS STEEL (304) AND 6063 ALUMINIUM

ALLOYS BY FRICTION WELDINGP. Sammaiah, G.R.N. Tagore, K. Prasada Rao and V.G.N. Rao

Osmania University

The aim of this study is to investigate experimentally the mechanical properties in terms of frictionpressure and upset pressure. Friction pressure, upset pressure is varied; burn-off length, rotational speed andduration of welding are fixed. The tensile strength and impact strength are increased with increase in upsetpressure. The tensile strength and impact strength are decreased with increase in friction pressure. It isobserved that the joint efficiency of friction welded dissimilar materials is proportional to upset pressure andinversely proportional to friction pressure. The mechanical properties of friction welded parts also relateswith the rate of axial shortening length. The rate of axial shortening of welded parts increases with increasein upset pressure. Microstructures using micro photographs were examined in the heat affected zone ofwelded parts. Hardness variations in welding zone were also obtained. Experimental results were comparedwith those of parent metals.

42 ISRS-2008

M1-P2

FEM SIMULATION OF POROUS STEELS UNDERCONTACT FATIGUE LOADING

Govindarajan N. and Gnanamoorthy R.Dept. of Mechanical Engg, Indian Institute of Technology, Madras, India

Powder metallurgy route is becoming progressively more essential in automotive sector principallydue to save weight and cost of production. The application of sintered steels depends on the mechanicalproperties which are greatly influenced by densification process. Presence of pore edges in sintered steelsmay worsen the contact fatigue properties. Effect of porosity under the contact fatigue conditions has beenelaborately discussed in the previous publications. The objective of this paper is to investigate the effect ofthe porosity in different amount and shape under the fatigue cyclic loading by numerical approach. Theinduced contact stresses near to the pore edges have been simulated in sintered steels by available generalpurpose code, with this the contact fatigue life is predicted and compared with the experimental results. Forthis Dang Van fatigue model is used.

M1-P3

INVESTIGATES OF CRACK STRUCTUREUSING FINITE ELEMENT METHOD

Hari Prasad K.Sathyabama University, Chennai, India

This paper investigates the accuracy of predicting the dynamic response by finite element modelingof structures with cracks. Steel and composite materials are widely used in various construction elementsand composites in particular have increased substantially over the past few years. These materials aresubjected to various types of damage, mostly cracks and delaminations. These result in local changes of thestiffness of elements from such materials and consequently their dynamic characteristics are altered.

The cracks are modeled as such in case of stress analysis to study the stress pattern at those local regionsof crack, while in case of dynamic analysis an equivalent model is built with many assumptions. While thereare many literatures available on these, there is literally none that has investigated the effect on the results ofthe analysis with such models.

The aim of the work presented in this paper is to analyse the influence of mesh and spring stiffnessvalues on the error in dynamic analysis and modal frequency values of a beam. This problem has been solvedby using the finite element method. The damaged part of the structures has been modeled by contact finiteelements with failures, while the undamaged parts have been represented by other, well-known finiteelements.

ISRS-2008 43

M1-P4

EFFECT OF SLOT NOTCH ON LOW CYCLE FATIGUE BEHAVIOR OFALLOY 718 AT 25 C AND 650 C

Sridhar A.a,b, Vikas Kumar a, Gogia A. K. a and Ganesh Sundara Raman S.baDefence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad, India

bDept. of Metallurgical & Materials Engg, Indian Institute of Technology Madras, India

Low cycle fatigue (LCF) life can be significantly influenced by notches present in components. Mostof the data available in literature have been generated using specimens having circumferential or single ordouble edge notches. Use of specimens with circumferential notch may not be entirely appropriate forcomparison with smooth (unnotched) fatigue specimens, because of difference in their diameters. As thediameter decreases, there is a decrease in volume or surface area of the specimen. This is of significance,since fatigue failures usually start at the surface.

In the present study tangential slot notch was used to investigate its effect on LCF behavior of Alloy718. It removed a very small percentage of the specimen cross-sectional area and did not cover entirecircumference. So a comparison could be made between the smooth and tangential notch specimens withoutmuch variation in their surface areas or volume. Total strain controlled LCF tests were conducted at 25 C

and 650 C (R 0, triangular wave form, 0.3 Hz frequency) using specimens with tangential slot notch andunnotched specimens. Results indicate that tangential slot notch also reduced significantly the fatigue life ofalloy 718 though it removed only a small amount of material from the gauge portion.

M1-P5

EFFECT OF MELT AND HEAT TREATMENT ON MECHANICAL ANDABRASIVE WEAR BEHAVIOUR OF CAST Al-Si-Mg ALLOYS

Swamy N.H.S., Raghavendra Kumar S., Joseph M.A., Nagarajan N.M. and Sateesh N.H.National Institute of Technology, Calicut, India

This paper presents the results of investigations carried out on the effects of heat treatment in cast alloys,on mechanical properties and dry sliding wear behaviour of Al-Si-Mg cast alloys. Al-Si-Mg alloys with 7, 12, 16%Wt. silicon and cast with modification, combined modification & vibration and heat treatment were testedadopting standard testing procedure have been compared. Samples cast with modification, vibration duringsolidification and heat-treated exhibit relatively better mechanical properties and improved wear resistance.Optical microscopy study of these samples show enhanced spheroidisation and uniform distribution of eutecticsilicon crystals. Scanning electron microscopy of tensile fractured and wear surfaces were carried out to analysethe mode of fracture and mechanism of material removal under abrasive wear condition.

44 ISRS-2008

M1-P6

MECHANICAL PROPERTIES OF MANGANESE DOPED Y-TZP:THE EFFECTS OF HOLDING TIME VARIATIONS

Meenaloshini S. and Ramesh S.Universiti Tenaga Nasional, Malaysia

The effect of varying holding times on the mechanical properties of yttria stabilized tetragonal zirconiadoped with 1 wt% MnO2 was investigated. Samples were sintered at 1300 C - 1350 C with holding timesvarying from 12 mins up to 2 hours. Longer holding times (1 hour and 2 hours) resulted in enhanceddensification of the undoped Y-TZP as compared to the MnO2 doped Y-TZP. The MnO2 doped Y-TZPhowever, recorded better densities, especially for sintering temperatures above 1325 C, for samples with 2hours holding time. Higher fracture toughness values were obtained for the undoped samples compared tothe doped ones produced at the same temperature and same holding times. Longer holding times resulted inimprove fracture toughness for undoped samples, these being more noticeable for samples sintered at1325 C. Shorter holding times (12 mins, 30 mins and 1 hour) and higher sintering temperature (>1325 C)saw an improved hardness in the MnO2 doped samples. Even though lower hardness values were recordedfor the undoped samples, as compared to the doped samples, a consistent increase in hardness values weredepicted as holding time was increased from 12 mins to 2 hours. However, an inconsistent trend was observedfor Young’s Modulus values of the doped samples instead.

ISRS-2008 45

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M2-O1

A UNIFIED VISCOPLASTICITY MODEL FOR APPLICATIONIN HIGH TEMPERATURE APPLICATIONS

Shridhar Powar, Lakshmana Rao and Adinarayana NamburiIndian Institue of Technology, Madras, India

Life estimation of high temperature components in power generation equipments is critical for the safeoperation of these components. Current life estimation codes simplify the interaction of the degradationmechanisms of creep and fatigue, hence allowing in a large amount of conservatism in the design of thecomponents to account for the uncertainty. This can be avoided and the life estimation can be improved ifphysics based constitutive models, which attempt to model the degradation mechanisms better are appliedto design of components. In this paper a unified constitutive called Bodner model has been utilized fordemonstrating material behavior under diverse loading scenarios. The model has been applied to a uniaxialspecimen with the material parameters of Inconel 718, which is a widely used material in the industry. Themodel has been compared with experimental data for uniaxial monotonic and cyclic response. Creep responsehas also been simulated under certain conditions. The seamless integration of these two mechanisms and theresulting accumulation of strains have been demonstrated. In addition the response of the model to widelyvarying loading conditions has also been displayed.

M2-O2

EFFECT OF WELDING CONSUMABLES ON TENSILE, HARDNESSAND IMPACT PROPERTIES OF GAS TUNGSTEN ARC WELDED

MARAGING STEEL JOINTSVenkata Ramana P. and Madhusudhan Reddy G.

Jawaharlal Nehru Technological University, Hyderabad, India

Maraging steels are widely used in aerospace applications due to combination of strength andtoughness superior to other high strength steels. The unique property of being weldable in the solutionizedcondition followed by post weld maraging treatment at relatively low temperature (480 C) makes these steelsattractive for fabrication of large structures. In common practice, however, gas tungsten arc welding is widelyemployed in view of the consistency of weld quality and overall economy. The strength and toughness offusion zone of considerably lower than that of parent metal and this has been attributed to presence of revertedaustenite. The strength and toughness of welds to a greater extent are dictated by the filler metal selection.In this investigation an attempt has been made to study the effect of welding consumables on tensile, hardnessand impact properties of maraging steel joints. Three different consumables, namely maraging steel,austenitic stainless steel and medium alloy medium carbon filler have been used to fabricate joints by gastungsten arc welding processes. Weldments were subjected to direct aging treatment at 480 C/3h/air cooling.Microstructure and mechanical properties such as tensile, hardness and impact toughness in the as-weld andaged conditions were evaluated. The joints fabricated using maraging steel filler metal showed superiorstrength than other joints. The joints fabricated using austenitic stainless steel filler metal exhibited superiortoughness than other joints. Optimum combination of strength and toughness are obtained by welds madewith medium alloy medium carbon filler metal. The observed mechanical properties have been correlatedwith microstructure and fracture features.

46 ISRS-2008

M2-O3

STRESS AND DEFLECTION ANALYSIS IN THE CERAMICORTHOTROPIC COMPOSITE PLATES WITH CIRCULAR HOLE(S)

SUBJECTED TO TRANSVERSE LOADINGJain N.K., Shrihari Agrawal and Rajput P.S.

Sagar Institute of Research and Technology, Bhopal, India

The distributions of stresses and deflection in rectangular ceramic orthotropic composite plates withtwo coaxial circular holes subjected to different transverse static loading conditions have been studied usingfinite element method. The aim of author(s) is to analyze the effect of D/A, D/L and X/D ratio (where D ishole diameter, A is plate width, X is centre distance of holes and L is plate length) upon stress concentrationfactor (SCF) for normal stresses in X, Y directions, shear stress in XY plane and von mises stress, anddeflection in transverse direction in ceramic orthotropic rectangular composite plates. The D/A ratio is variedfrom 0.1 to 0.5. The results of ceramic fibre composites are also assessed with results of glass fibre andgraphite fibre composites. The results are obtained for three different boundary conditions as all edges aresimply supported, all edges are fixed and two edges are simply supported and two edges are fixed. Thevariations of SCF and deflection with respect to different parameter are presented in graphical form anddiscussed. The finite element formulation is carried out in the analysis section of the ANSYS package. Thiswork will also provide the guidelines to designer to select the material as per their requirements. This workwill helpful for the designing of members of marine, aircraft, nuclear reactors and chemical vessels wheresuch situations are commonly met width.

M2-O4

EFFECT OF Pt CONTENT ON THE TENSILE PROPERTIES OFFREE STANDING PtAl BOND COATS AS DETERMINED

BY MICROTENSILE TESTINGMd. Z. Alam, Srivathsa B., Kamat S.V., Jayaram V. and Das D.K.

Indian Institute of Science, Bangalore, India

Pt-aluminide (PtAl) bond coats typically 50-100 m thick, are widely used for imparting oxidationresistance to Ni-based superalloy components of gas turbine engines. These coatings exhibit a multilayerstructure and show a graded composition. Despite their excellent oxidation resistance, PtAl coatings arebrittle and, are known to degrade the mechanical properties of the coated components. In order to determinethe mechanism by which these coatings affect the tensile properties of the substrate alloy, the tensile propertiesof free-standing PtAl coatings have been evaluated at room temperature, using microtensile testing. Thedesign of the test specimens was established by parametric studies using finite element method (FEM) basedsimulations using ANSYS. The microsamples that were designed had a parallel gage length of 2 mm, gagewidth of 0.5 mm, thickness ~ 90 m with an overall length of 8 mm. The elastic stress concentration factordue to the 0.5 mm fillet radius was calculated to be in the range of 1.12 to 1.28. These dimensions ensuredthe failure of the samples within the gage length.

PtAl coating samples with varying Pt content were tested at room temperature (RT). Results indicatethat incorporation of Pt upto 5 %m does not affect the tensile properties significantly. However, for high Ptlevels which corresponded to an initial Pt layer thickness of 10 %m, the UTS increases by almost two times.

ISRS-2008 47

Since the brittle-to-ductile transition temperature of these coatings are above 600 C [1, 2], the measurableductility for all the samples was approx. 0.2%. Fractography studies indicate with significantly higher Ptcontent, these coatings show an increased tendency for brittle cleavage failure. Apart from theabove-mentioned results, the various issues regarding the preparation of these coating microsamples and theaspects of testing at such small length scales will be discussed.

M2-O5

CREEP STRENGTH OF CENTRIFUGALLY CAST Al-RICH TIAL ALLOYSSturm D.3, Heilmaier M.3, Saage H.3, Paninski M.1, Schmitz G.J.1, Palm M.2, Stein F.2, Drevermann A.1,

Engberding N.2, Kelm K. 4, Irsen S.41ACCESS e.V., Intzestraße 5, D-52072 Aachen, Germany

2Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Str. 1, D-40237 Düsseldorf, Germany3Otto-von-Guericke-Universität Magdeburg, Institut für Werkstoff- und Fügetechnik, Lehrstuhl

Werkstopffprüftechnik, Postfach 4120, D-39016 Magdeburg, Germany4Stiftung caesar, Electron Microscopy, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany

Al-rich Ti-Al alloys are considered as promising candidates for the development of novel light-weightmaterials for structural applications at high temperatures. Compared to Ti-rich -TiAl-based alloys Al-richTi-Al alloys offer an additional reduction of the density of 20%, a better oxidation resistance - which are bothdue to the increased Al content - and sufficient strength at high temperatures. The material has beencentrifugally cast by ACCESS in Aachen. Microstructural characterization was carried out employinglight-optical, scanning and transmission electron microscopy and XRD analyses. High temperature creep ofa binary Ti-60 Al (at. %) and a Ti-62 Al (at. %) alloy in the cast state and after annealing at 950 C for 200 h

which produced lamellar -TiAl r-Al2Ti microstructure were studied utilizing creep compression tests in

a temperature range between 900 and 1050 C in air. In particular, it is shown here that the as-cast alloysexhibit already quite reasonable creep resistance at 900$C, especially with regard to their low density ofaround 3.8 g/cm3. Stress exponents calculated as the slope n log (strain rate)/ log (stress) 4 were foundto be relatively constant for the temperature and stress regime investigated. This indicates that dislocationclimb may be the rate controlling creep mechanism. The assessment of creep tests conducted at identicalstress levels and varying temperatures yielded activation energies for creep of around Q = 420 kJ/mol for theannealed Ti-60 Al (at. %) alloy. This value is significantly higher than the once found in literature forinterdiffusion of Al or Ti in -TiAl which may arise from the two-phase microstructure of the alloys

investigated here. Whereas the value of Q 347 kJ/mol obtained for the annealed Ti-62 Al (at. %) material

coincides well with that of Al diffusion in -TiAl.

M2-P1

MULTIMODE LAMB WAVES INTERACTION WITH DEFECT INMETALLIC STRUCTURES USING EMAT:

MODELING AND EXPERIMENTDhayalan R., Krishnan Balasubramaniam, Krishnamurthy C.V., Janardhan Padiyar M., Maxfield B.W.

Indian Institute of Technology, Madras, India

This paper describes the finite element simulations and experiments to examine the generation andinteraction of Lamb waves with defects in thin plate using Electromagnetic Acoustic Transducer (EMAT).

48 ISRS-2008

This type of transducer can generate or detect sound waves in electrically conductive or magnetic materialsthrough the Lorentz force principle or magneto-elastic effects. This paper also describes the design principlesof developing electromagnetic acoustic transducers using both experimental and simulation for lamb wave’sgeneration. At low values of the frequency-plate- thickness product (f*d), multiple Lamb wave modes areexcited with different group velocities. The fundamental Lamb wave modes (A0) and S0) are excited at 500kHz in a 2mm thick aluminum plate and these modes are allowed to interact with slot type defects of differentdepths. The fundamental lamb wave modes (A0 and S0) are mode converted by the slot type defects whichobserved in the output signals. The mode converted Lamb wave modes are analyzed and identified with thehelp of Dispersion curves for 2mm thick aluminum plate. In this paper we combine the experimental workwith the finite element simulation to understand the, propagation and interaction of the multimode Lambwaves with defects.

M2-P2

FLOW BEHAVIOR OF AZ31 Mg ALLOY UNDER COMPRESSIONRajesh Korla and Atul H. Chokshi

Indian Institute of Science, Bangalore, India

In textured HCP metals, there is a strong asymmetry in tensile - compressive flow behavior due to alack of sufficient number of slip systems, along with high possibility of twinning. The influence of grain size(8 to 51 m) and temperature (298 to 673 K) on the flow behavior of highly basal textured AZ31 alloy wasstudied under compression. There is a clear transition in the flow behavior with increasing temperature, at523 K. It was also observed that twinning operates only above a certain critical grain size; below this size,slip is the dominant deformation mechanism. The effect of strain rate on transition temperature was alsostudied. The experimental results will be discussed with reference to existing deformation models, and theimplications for creep will also be considered.

M2-P3

DAMPING AND STIFFNESS BEHAVIOR OF FLY ASH REINFORCEDFUNCTIONALLY GRADED RUBBER COMPOSITE

Doddamani M.R. and Kulkarni S.M. National Institute of Technology, Surathkal, India

The paper presents extensive analysis of dynamic behavior of a very special class of composite. Asystematic experimental investigation was conducted to evaluate the stiffness & damping ratio ofunreinforced and fly ash reinforced functionally graded rubber composite (FGRC). FGRC coupons wereprepared using conventional casting technique. Presence of gradience in prepared specimens is attributedtowards variable density particles present in fly ash which settles variably while solidifying. The methodsconsidered for evaluation were Logarithmic Decrement Analysis, Hilbert Transform Analysis, Moving BlockAnalysis, and Modified Half Power Bandwidth method. Stiffness as a function of filler addition as well asgeometrical parameters was investigated. The damping response of varying fly ash bearing FGRC systemwas studied. Experimental investigation was carried out using single channel Fast Fourier Transform analyzer.The results obtained from our Experimental investigations show that, with the increase in filler weight fraction& the thickness there is net increase in damping ratio. In present work, experiments are designed based onTaguchi’s Design of Experiments approach.

ISRS-2008 49

M2-P4

A STUDY ON LARGE DEFORMATION ANALYSISOF HYPERELASTIC MATERIAL

Sujithra R. and Dhanaraj R.Department of Rubber Tech., Department of Aerospace Engg. Madras Institute of Technology, Chennai, India

Rubber-like materials which undergo large elastic deformations, leads to numerous applications inbiomedical and meteorological fields. An increase of applications requires better understanding ofmechanical behavior which cannot be described by a simple stress-strain relation, but by their strain energyfunction.In this paper, hyperelastic constitutive equations are discussed based on various strain energyfunctions using theory of large elastic deformations. From the literature, few examples are considered here:inflation of spherical balloons, inflation of a circular flat elastomer plate, thick walled cylinder subjected tointernal pressure, uniaxial and biaxial stretch. A comparison study has been done based on the analyticalsolution for various material models and the results are also validated with FEA simulation (ANSYS).

M2-P5

TEXTURE AND MICROSTRUCTURE EVOLUTION IN COMPRESSIONOF TITANIUM - A MICROMECHANICS BASED APPROACH

Nilesh Gurao and Satyam SuwasIndian Institute of Science, Bangalore, India

Evolution of microstructure during room temperature compression of hexagonal commercially pureTi with different initial orientation was studied using Orientation Imaging Microscopy (OIM). All thedifferent initial textures yielded the same end texture despite of different microstructural evolution in termsof twin boundaries. This is due to the operation of different slip and twinning systems during deformation.Micro-mechanics based Visco-plastic self consistent model using secant approach was used to reproduce andthus validate the observed experimental results.

M2-P6

RESIDUAL STRESSES INDUCED BY COLD HOLE EXPANSION USINGBALL-SPLIT SLEEVE AND TAPERED PIN- SPLIT SLEEVE METHODS

Gopalakrishna H.D., NarashimaMurthy H.N., Krishna M.R.V. College of Engineering, Bangalore, India

This paper reports experimental results on the determination of residual stresses in cold expanded holesusing ball with split sleeve and tapered pin with split sleeve methods. The results of measurements in thevicinity of cold expanded holes in Al 2024 T3 alloy plates of thickness 4 mm are presented. The holes ofdiameter 10.78, 10.67, 10.56, 10.45 and 10.34 mm were expanded by 2, 3, 4, 5 and 6 % respectively adoptinghardened steel ball of diameter 8.27 mm, EN24 hardened tapered pin and spring steel split sleeve using anInstron machine. Tangential and radial residual stresses were measured using strain gauge method. Thegauges were mounted in radial and tangential directions at different distances from the hole to determine thestress distribution around the hole. The two methods of expansion were compared based on the amount ofresidual stresses induced around the hole and the zone of compressive stresses to establish the influence ofcold expansion on the parameters. The residual stresses verses the degree of hole expansion was studied inboth the methods. Selected specimens were subjected to cyclic loading of 125 KN (tensile and compressive)corresponding to 50 % of the yield strength of Al 2024, at room temperature with a sinusoidal waveform ofa frequency of 25 Hz.

50 ISRS-2008

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MD-O1

EFFECT OF GAS TUNGSTEN ARC WELDING (GTAW) AND LASERBEAM WELDING (LBW) ON CORROSION OF Ti6Al4V ALLOY

Bupesh Raja V.K., Palani Kumar K., Elangovan K.Sathyabama University

The titanium alloys are extensively used due to the properties like high strength-to-weight ratio,excellent mechanical properties and high resistance to corrosion. Among the titanium alloys, Ti6Al4V alloyis used widely due to its good weldability. In this investigation the effect of the welding process on thecorrosion behaviour of 3mm thick plates of Ti6Al4V alloy, is studied. The corrosion behaviour of the Ti6Al4Vweldments was studied using the gas tungsten arc welding (GTAW) and laser beam welding (LBW)technique. These two processes were done to compare the fusion process and high-energy beam processesand their effect on the corrosion behaviour of Ti6Al4V alloy. Further the corrosion behaviour of Ti6Al4Vweldments would be an indication of the quality of the weldment. The corrosion shall be more than theacceptable value, if there is a breach in the argon gas shielding and contamination of the weldment by theatmospheric gases and other inclusions. Generally pitting corrosion is observed in Ti6Al4V alloy; thereforethe pitting corrosion tests were done in this investigation. The pitting corrosion was studied usingpotentiodynamic polarization technique, with non-deaerated 3.5% NaCl solution of pH 7, to create acorrosion environment. The results show joints made by gas tungsten arc welding (GTAW) process yieldbetter pitting corrosion resistance when compared to laser beam welding (LBW) welding process.

MD-O2

WEIGHT LOSS CORROSION STUDIESS OF Al6061 / RED MUDMETAL MATRIX COMPOSITES IN SEA WATER

Abdul Jameel 1, Krupakara P.V.2, Nagaswarupa H.P.31Department of Chemistry, Jamal Mohammed College, Tiruchirapalli.

2Department of Chemistry, Auden Technology and Management Academy, Bangalore.3 Department of Chemistry, East west Institute of Technology, Bangalore.

This paper deals with the corrosion characterization of Al6061- red mud particulate metal matrixcomposites (MMCs). Al6061 alloy is used as matrix. Commercially available alloy is used. Red mud is the wastageobtained after the removal of aluminium from its ore and conatis silics, alumina, titanium diaoxide and ferricoxide. Being a ceramic material red mud remains inert and is hardly affected by the corrosion medium. Red mudparticles of size 50-80 microns are used as reinforcement. Experiments were conducted to determine the corrosionrate of the samples in sea water procured from Arabian sea in malpe, Udupi District, Karnataka. MMC’s areprepared according to ASTM standards by liquid melt metallurgy technique using vortex method. Compositescontaining 2, 4, 6% by weight of Red mud and unreinforced matrix were tested using Arabian sea water at roomtemperature. Specimens are taken in the form of 20mm 20mm cylinders. They were exposed to sea water fordifferent intervals of time. Corrosion rates of all samples were calculated using the formula 534W/DAT mpy. Theresults were computerised and simulation curves were obtained. The composite was found to be more corrosiveresistant than matrix alloy. In each test the corrosion resistance of both alloy composites was found to decreasewith the exposure time. The decrease in the corrosion rates of composites when compared to that of matrixalloy is due to the physical barrier created by Red mud particles.

ISRS-2008 51

MD-O3

STUDIES ON CORROSION BEHAVIOR OF ANNEALED 18 Ni 250GRADE MARAGING STEEL IN ORTHOPHOSPHORICACID MEDIUM

Poornima Shettya T., Jagannatha Nayak and Nityananda Shetty A.National Institute of Technology Karnataka, Srinivasanagar

The corrosion behavior of annealed sample of 18 Ni 250 grade maraging steel was investigated inorthophosphoric acid,which is a potential high strength steel for advanced technologies such as aerospace,nuclear, and sporting goods. The corrosion test was carried out at different temperatures, in a corrosionmedium of orthophosphoric acid at different concentrations using electrochemical techniques like Tafelpolarization, electrochemical impedance spectroscopy (EIS) and scanning electron microscope (SEM)studies.The results obtained from Tafel extrapolation techniques and EIS techniques are in good agreement.The results show increase in corrosion rate with increase in temperature and also with increase inconcentration of corrosion media. The thermodynamic parameters like activation energy, enthalpy andentropy of activation were calculated using transition state theory equations.

MD-O4

ASSESSMENT OF CORROSION RESISTANCE OF Cu-10Ni-1Fe ANDCu-12Zn IN CLEAN AND SULPHIDE POLLUTED SYNTHETIC SEAWATER

Khan A.F., Patil A.P., Rao T.S.VNIT, Nagpur

Cu–10Ni–1Fe is widely used in the marine environments. However, it suffers from acceleratedcorrosion in sulphide-polluted seawater. It is known that addition of Zn to Cu-alloy improves resistance tosulphide attack as in Cu–Zn alloy, but the data is scanty. The present study therefore investigates corrosionresistance of Cu-10Ni alloy and Cu–12Zn alloys, so as to understand the role of Zn. Test method used wascathodic polarization in clean and sulphide polluted synthetic seawater (SSW). The SSW was prepared asper ASTM D 114-75 and sulphide was added through sodium sulphide. Two concentrations of sulphide weretaken viz. 0.1 g/L and 0.2 g/L. Ecorr of both the alloys become active on addition of sulphide in the testsolution. In case of Cu-10Ni it decreases substantially from –0.24 V Vs (SCE) in SSW to –0.92 V Vs (SCE)in SSW 0.2 g/L Na2S. Whereas, the drop in Ecorr of Cu-12Zn alloy is only marginal i.e. from –0.30 V Vs

(SCE) in SSW to –0.44 V Vs (SCE) in SSW 0.2 g/L Na2S. Thus, the corrosion tendency of Cu-10Ni alloyincreases manifold from that of Cu-12Zn alloy on addition of sulphide to SSW. Corrosion current density(icorr) of Cu–10Ni is found to be lower than that of Cu–12Zn alloy in SSW. The icorr of Cu-10Ni increasesfrom 8.78 A/cm2 for SSW to 21.07 A/cm2 for SSW 0.2 g/L Na2S. Whereas, the corrosion rate of Cu-12Znalloy actually decreases on addition of 0.1 g/L sodium sulphide and increases on addition of 0.2 g/L Sodiumsulphide, but still is less as compared to that of Cu–10Ni–1Fe. Thus it is found that Cu–10Ni–1Fe is morecorrosion resistant in clean SSW and less corrosion resistant in sulphide polluted SS than Cu–12Zn alloy.The drop in corrosion resistance of Cu–10Ni–1Fe in sulphide polluted SSW is attributed to formation ofCu2S, that is less protective than Cu2O. Relatively better corrosion resistance of Cu–12 wt% Zn alloy insulphide polluted SSW is attributed to the formation of ZnS that is bad conductor.

52 ISRS-2008

MD-O5

PHENOMENOLOGICAL STUDY OF HOT TEARINGIN AZ91D MAGNESIUM ALLOY

Bichler L. and Ravindran C.Centre for Near-net-shape Processing of Materials, Ryerson University, Toronto, Ontario, Canada

Hot tearing in steels and aluminum alloys has been rigorously investigated in the past decades.However, the interaction between the key factors such as solidification, microstructure and stress and strainat the onset of hot tearing in magnesium alloys remains unclear. Specifically, the stress and strain conditionsrequired to nucleate hot tears are unknown. In this research, neutron diffraction (ND) residual strain mappingwas used to determine the stress and strain conditions in a casting at the onset of hot tearing. The resultsindicate that tensile residual stress of ~12 MPa in a casting region with a stress concentration was necessaryto nucleate and propagate hot tears. Microstructural analysis revealed that hot tears propagated via regionsof high interdendritic shrinkage porosity. These results were compared to the predictions of numericalcomputer modeling and key issues preventing accurate computer modeling of hot tearing were identified.

MD-P1

STUDIES ON PASSIVATION OF AISI 304 STAINLESS STEEL IN0.4N/0.5N H2SO4 AND EFFECT OF OXIDIZER (MnO4

-) ADDITIONKhobragade N.N. and Patil A.P.

Visvesvaraya Natioanal Institute of Technology,Nagpur

Austenitic stainless steel, particularly SS 304 is a popular material for application in chemical andfertilizer industry. It has excellent corrosion resistance in sulfuric acid owing to formation of a fine andcompact Cr2O3 film. Sulfuric acid is an oxidizing acid but when its concentration is low, the film is not stableand does not heal by itself quickly, if damaged. Therefore, if film is damaged by turbulences or erosion, thealloy suffers from accelerated corrosion. The situation can be salvaged by addition of an oxidizer. Presentstudy is aimed at finding out how the passivity in dilute acidic solution can be restored so that the SS 304does not suffer from accelerated corrosion. Test solutions were 0.4N and 0.5N H2SO4 without or with anoxidizer (0.1, 0.2, 0.5,1 and 2% KMnO4). Test method was potentiodynamic polarization 1V from opencircuit potential. It is found that in absence with scan range of of oxidizer the cathodic part shows instabilityand few segments of cathodic/anodic switch over; indicating thereby that active and passive states are stablesimultaneously. This means that the passivity is not truly stable and there is risk of accelerated corrosion incase of damage to the film. On addition of oxidizer, the Ecorr shifts in noble direction and the feature ofsimultaneous presence of active acid and passive state is removed. It is found that the cathodic plot has linearregion extending more than two order of magnitude of current; this part is used to workout cathodic currentdensity at OCP (icorr). Anodic part of the plots containing 0.1 KMnO4 has no passive phase and the icorrobtained from cathodic part is highest. On increasing KMnO4 addition further, few plots exhibit two segment;first limiting current region and second typical passivation region. However, the current density in this regionis too high for this to term as true passivity. The current density in limiting current region is also higher thanicorr obtained from cathodic part. Thus, corrosion of stainless steel in these test solutions is under cathodiccontrol. The optimum amount of KMnO4 both the solutions is 1%. It means, on additions 1% KMnO4 to0.4N and 0.5N H2SO4 solutions, the passivity will become stable. However, corrosion will remain undercathodic control.

ISRS-2008 53

MD-P2

CORROSION BEHAVIOUR STUDIES OF 6061 Al-15vol.pct.SiCCOMPOSITES IN ACID MEDIUM

Geetha Mable Pinto, Jagannath Nayak, Nityananda Shetty A. NITK, Surathkal, Karnataka

The corrosion behavior of 6061 Al-15vol.pct.SiC composite is investigated which is potential structuralmaterial for aerospace and automotive applications. The corrosion test was carried out at differenttemperatures in the concentration range of 0.01N to 1N of 1:1 mixture of hydrochloric acid and sulphuricacid as corrosion media using Tafel Extrapolation Technique and Electrochemical impedancespectroscopy(EIS). Tafel extrapolation plot was obtained by polarizing the specimen to about 250 mVanodically and –250 mV cathodically from the open circuit potential. The EIS measurements were carriedout in a frequency range of 100000Hz to 0.01Hz using the amplitude of 10mV peak to peak with AC signalat the open circuit potential. The corrosion current density icorr was calculated using the charge transferresistence, Rct together with Stern-Geary equation. The results obtained from Tafel Extrapolation Techniqueand Electrochemical impedance spectroscopy were in good agreement. The results show a increase in thecorrosion rate with increases in temperature as well as the increase in the concentration of the corrosionmedia. The thermodynamic parameters like activation energy, enthalpy of corrosion and the change in thestandard free energy were calculated using transition state theory equations.

MD-P3

THE INFLUENCE OF SODIUM MOLYBDATE ON L-VALINE-Zn2+ SYSTEMCONTROLLING CORROSION OF CARBON STEEL IN RAIN WATER

Wilson Sahayaraj J.1 and Susai Rajendran2*1Department of Chemistry, Jeppiaar Engineering College, Chennai

2Corrosion Research Centre, Department of Chemistry, GTN Arts college, Dindigul, Tamil Nadu

Cooling water treatment plays a key role in most industries. In most cooling systems carbon steel isused as construction material for heat exchangers and piping. Carbon steel in contact with water howeverwill corrode. To fight with corrosion in cooling water system, the chemicals with anti-corrosive propertiesare dosed into the water. Though corrosion inhibitors such as chromate, polyphosphate and nitrite provideda reliable measure of corrosion protection, discharge of such toxic materials was considered unacceptabledue to environmental safety guidelines. So L-valine (LV) used as environmental friendly inhibitor in thisstudy. The synergistic effect of L-valine and Zn2 on the inhibition of corrosion of carbon steel in rain water(collected form roof top and stored in concrete tank environment) containing 72 ppm of chloride, 273 ppmof TDS, 14 ppm of sulphate and 9 ppm of nitrate. The formulation consisting of 50 ppm of L-valine and 50ppm of Zn2 has 74% inhibition efficiency (IE). To enhance the IE of L-valine - Zn2 system sodiummolybdate (SM) added. As the concentration of SM increases, IE also increases. As the immersion periodincreases, the inhibition efficiency decreases. Polarization study reveals that the L-valine - Zn2 - SM systemfunctions as mixed inhibitor. AC impedance spectra reveal that a protective film is formed on the metal surface.The FTIR spectra study lead to the conclusion that the Fe2 - LV complex and Fe2 - SM complex formedon anodic sites of the metal surface controlled the anodic reaction and Zn(OH)2 formed on the cathodic sitesof the metal surface controlling the cathodic reaction. The L-valine - Zn2 - SM system may found in coolingwater system.

54 ISRS-2008

MD-P4

EROSION WEAR BEHAVIOR OF DETONATION SPRAYEDWC-Co COATINGS

Suresh Babu P., Basu B., Sundararajan G. IIT Kanpur, Kanpur, ARCI, Hyderabad

Thermal spray techniques have become very popular for depositing wear resistant coatings to enhancethe component life and performance.Plasma spray technique is being used widely for depositing WC-Cocoatings characterized by greater thermal energy and low velocity of the particles, the plasma spray techniqueresults in substantial decomposition of WC leading to formation of brittle and amorphous phases with inferiorwear properties. In order to minimize decomposition, these coatings have been successfully deposited usingHigh Velocity Oxy-Fuel (HVOF) or Detonation spray coating (DSC) techniques. Despite the lower thermalenergy and high velocity used in both the HVOF and detonation processes (compared to plasma spraying),decomposition still occurs though to a lesser extent. A review of the literature indicates that the erosionresistance depends on multiple parameters, which are related to the deposition process, coating microstructureincluding decomposition and coating mechanical properties and erosion test conditions. However, none ofthe earlier studies employed a single technique to systematically vary the extent of decomposition and studythe influence of WC decomposition and coating structure on the wear properties. In the present talk, roomtemperature dry solid particle erosion behavior of detonation sprayed WC-12Co coating will be discussed asa function of processing parameters, coating microstructure and test conditions like various erodents, impactvelocities and impact angles.

MD-P5

OXIDATION BEHAVIOUR OF 30v%ZrB2-SiC & 30v%MoSi2-SiCCOMPOSITES UNDER DIFFERENT CONDTIONS

R.Suresh Kumar*, D.Sivakumar**, Ashutosh S.Gandhi**Department of Metallurgical & Materials Science, IIT Madras

**Materials & Metallurgy Group, Vikram Sarabhai Space Centre, Trivandrum, E-mail: [email protected]

Oxidation studies were conducted on two types of near theoretical density SiC based compositescontaining 30v% ZrB2 and 30v%MoSi2 processed from powders through hot pressing. While isothermaloxidation studies were conducted at 1500 C upto 12 hour duration to understand the oxidation kinetics ofthese materials, the performance under rapid heating under oxidizing conditions was evaluated by conductingrapid heating short duration tests through joule heating of the samples upto 2200 C. The features of oxidesurfaces of samples, both isothermal and rapid heat oxidized, were investigated through X-ray diffractiontechnique and scanning electron microscopy and are presented in this paper.

ISRS-2008 55

MD-P6

STUDY OF ABRASIVE WEAR BEHAVIOUR ON COBALARC/DUROMANGAN MULTILAYER HARDFACED MILD STEEL

FOR SLURRY PUMP APPLICATIONVikas Kholar, Bhanu Kiran V. T., Samarjeet Chanda, Sanglap Ghosh, Siddhartha Dasgupta, Soumen Dutta

The objective of the paper is to study abrasive wear behaviour of cobalarc / duromangan multilayerhardfaced mild steel using sand slurry abrasion tester. Cobalarc (Hardfacing layer) and Duromangan (Bufferlayer) electrodes were selected for replacing conventional hardfacing electrodes such as Stellite. The requiredminimum hardness for slurry pump component material of 60 HRC is achieved by the use of cobalarc /duromangam multilayer hardfaced mild steel. The multilayer hardfaced material (10mm thickness) showedhardness and wear properties comparable to high chromium steel material (30mm thickness) currently beingused for slurry pump lining and impeller. The multilayer hardfacing is usually restricted to two hardfacinglayers, as triple or multiple layers result in the formation of cracks due to welding contraction strain. Thecobalarc / duromangam multilayer hardfaced mild steel can be considered as an alternative material for slurrypump applications.

MD-P7

LOW TEMPERATURE OXIDATION BEHAVIOUR OFNANOCRYSTALLINE vis-à-vis MICROCRYSTALLINE Fe-10Cr ALLOYS

Rajeev K. Gupta1, Singh RamanR.K.1,2, Murty B.S.3, Carl C Koch4

1.Department of mechanical and aerospace engineering, Monash University, Australia 2.Department of chemical engineering, Monash University, Australia

3.Department of metallurgical and materials engineering, IIT-M 4.Department of materials science and engineering, North Carolina state university, NC, USA

Nanocrystalline Fe-10Cr alloy with a mean grain size of 52 4 nm, prepared by high energy ballmilling followed by compaction and sintering, was oxidized in air at 300oC for 52 hours. Its oxidationbehaviour, determined by measuring the weight change after regular time intervals and post-oxidationcharacterization of oxide film using secondary ion mass spectrometry (SIMS), was compared with that ofmicrocrystalline alloy of similar chemical composition, prepared by similar processing route and oxidizedin similar conditions. It was found that grain refinement to nano-scale level leads to a significant improvementin the oxidation resistance of Fe-10Cr alloy. SIMS analysis reveals that the improved oxidation resistance isdue to the formation of a Cr rich inner passive scale and Cr content in the passive film of nc alloy is muchhigher than that of mc alloys. Cr enrichment is due to the unique structure of nanocrystalline material wheregrain boundaries enhance the diffusion of Cr towards the oxide/alloy interface. A mechanism of improvedcorrosion resistance, based on the kinetic curves, SIMS analysis and theoretical knowledge of oxidation ofbinary alloys is proposed.

56 ISRS-2008

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MM-O1

INVERSE MAGNETOCALORIC EFFECTIN Ni-Mn-Sn MELT-SPUN RIBBONS

Babita I.1,2*, Chandrasekaran V.1, Ram S.21Defence Metallurgical research Laboratory, Hyderabad 500 058

2Materials Science Centre, Indian Institute of Technology, Kharagpur 721 302

Materials exhibiting large magnetocaloric (MC) effect under relatively low applied magnetic fieldsare of great interest for environmental friendly room temperature magnetic refrigerant.1 Recently, in Ga freeNi50Mn50-yXy (X In, Sn and Sb) series of Heusler alloys, positive magnetic entropy change, ( SM) oftentermed as inverse MC effect (IMCE) has been reported in the vicinity of the first order structuraltransformation (FOST) due to the strong coupling between magnetism and the structure2-3. Rapidsolidification/melt spinning offers metallurgically an interesting process route to synthesis ribbons of thesematerials with fine microstructure and the ribbon thus processed can be used as precursor for powderproduction. The fine powders in the form of bed or consolidated shapes are technologically attractive forfabrication of MCE devices. Two alloys of compositions Ni49Mn37.4Sn13.6 (R1) and Ni50Mn34.5Sn15.5 (R2)were prepared by arc melting of high purity Ni, Mn, Sn in argon atmosphere. The alloy ingots werehomogenized by turning and re-melting for four times. About 5-10 gm of each alloy was melted in a quartzcrucible and ejected on to a copper wheel with surface velocity of 50 m/s. The composition of the ribbonswas analysed using EDX and EPMA. DSC measurements were carried out to identify the structuraltransformation temperatures. The magnetic entropy change, SM was calculated from M-H data using theMaxwell relation,In this paper, we report the IMCE observed in melt spun Ni-Mn-Sn ribbons and the resultsare discussed in association with FOST and magnetic transitions. Interestingly, in R1 ribbon, the structuraltransformation occurs prior to magnetic transition incongruous to that observed in Ni50Mn34.5Sn15.5 ribbons.A maximum positive magnetic entropy change, SM ~6.0 Jkg-1K-1 and ~1.6 Jkg-1K-1 for a field changeof 2 T was observed in Ni49Mn37.4Sn13.6 and Ni50Mn34.5Sn15.5 ribbons respectively.

MM-O2

EFFECT OF TEMPERATURE ON MAGNETIC DOMAIN STRUCTURE INMULTIFERROIC DY SUBSTITUTED BISMUTH FERRITE THIN FILMS

Prashanthi K., Mandal M., Duttagupta S.P. and Palkar V.R.Centre for Excellence in Nanoelectronics, Indian Institute of Technology Bombay, Mumbai-400076, India

Multi-ferroïcs are exceptional materials whose fundamental state is both magnetic and ferro-electric.Because of coupling between magnetization and polarization (ME coupling) wide range of application canbe proposed with these materials. Possible applications of magnetoelectric materials includemagnetic-electric energy converting components, solid-state nonvolatile memory and multi-state memories.Perovskite BiFeO3 (BFO) is one of the very few room temperature multiferroic materials and has beenattracted many researchers in this field. It exhibits ferroelectricity and antiferromagnetism at roomtemparature. However to explore this material for device applications it is essential to induce ferromagnetismwithout disturbing ferroelectricity at room temperature. We have been successful in achieving the desiredproperties by partial substitution of Dysprosium (Dy) at Bismuth (Bi) sites. In this paper, we present the

ISRS-2008 59

effect of temperature on magnetic domain structure in Bi0.7Dy0.3FeO3 (BDFO) thin films grown by pulsedlaser deposition technique on Pt/Si substrate. Magnetic force microscopy (MFM) was used to image themagnetic domains and effect of temperature was observed in-situ. Interestingly, as-grown film shows irregularmagnetic domain pattern but as the temperature increases, domains start aligning and around 200oC changeto stripe domains. However, above 250oC, once again the domain alignment is disturbed. This could beattributed to magnetic transition which occur around 270oC as indicated by Differential Thermal Analysis(DSC) curve. Upon quenching the system back to room temperature, an irregular pattern is recovered withlarger magnetic domains. The observed changes in the magnetic domain structure with temperature suggesta strong thermal history dependence of the system related to the internal strains in the sample.

MM-O3

MAGNETIC AND OPTICAL PROPERTIES OF Co AND Mn CO-DOPED SnO2Balamurugan K.

Indian Institute of Technology Madras, Chennai

The non-magnetic wide-band gap semiconducting oxides, such as ZnO, TiO2 and SnO2 etc., have beenfound to exhibit interesting magnetic and optical properties when they are doped by 3d transition metals.More interests on these materials are due to the fact that they exhibit ferromagnetism with Curie temperature(TC) greater than 300 K. It has been shown by ab initio calculations that doping the wide band gap (Eg 3eV) TiO2 (rutile) with double impurities of transition metals would create impurity states and Fermi levelclose to the bottom of the conduction band. This double doping could give doped oxide semiconductorswithout oxygen vacancies. Also, it was proposed that these doubly doped oxide semiconductors might besuitable for spintronic applications.

SnO2 is a wide band gap semiconductor with optical band gap Eg 3.6 eV, having rutile structure.The polycrystalline powder sample of composition Sn0.95Co0.03Mn0.02O2 was prepared by solid statereaction method. This sample was found to exhibit a clear non-linear filed dependent magnetization, similarto a ferromagnet. A maximum magnetization of 0.033 emu/g was observed for the applied magnetic filed of1 tesla, at room temperature. Temperature dependent magnetization showed a drop in magnetization around145 K and the overall data looks similar to that of Mn-doped ZnO nanorods. This drop in magnetizationsuggests that there might be magnetic impurities of the doped metals Co and Mn, either in the form of metalor metal-oxide. Correspondingly we find some secondary phase in the scanning electron microscope (SEM)images of the sample. This implies that the observed ferromagnetism at room temperature might be eitherfrom Co metal or Mn3O4 or from both. The diffuse reflectance spectrum (DRS) of the Co-3% and Mn-2%co-doped SnO2 shows two more electronic transitions in addition to that of the host SnO2. Of the twoadditional transitions, one is in the visible region and the other is in the near infra red (NIR) region of theelectromagnetic spectrum. These transitions might be due to the creation of additional impurity energy levelsas an effect of doping.

60 ISRS-2008

MM-O4

EFFECT OF THICKNESS ON MAGNETIC PROPERTIESOF NICKEL FERRITE THIN FILMS

Gagan Dixit*, Singh J.P., Srivastava R.C. and Agrawal H.M.G.B. Pant University of Agriculture & Technology, Pantnagar, Uttarakhand, India

Ferrites are soft magnetic material having high value of resistivity and low eddy current losses . Thismake ferrite thin films suitable for magnetic recording and high frequency microwave device applications.Nickel ferrite has inverse spinel structure. The present work is motivated to study the effect of thickness onthe magnetic properties of the nickel ferrite thin films. The thin films were deposited on Si (100) substrateby pulsed laser deposition technique (PLD) as it preserves the target stoichiometry [1]. The deposition timewas varied from 16 min to 40 min in order to have the films of different thickness.The thickness of the filmsrange from 80nm to 200 nm as measured by surface profilometer.All the films were characterised by XRD,AFM, &VSM. The XRD confirmed the spinel phase. The microstructure of the films was studied by AFM.Both the roughness and grain size of the films were found to increase with the thickness of the films. Theparticle size was estimated from the X-ray diffraction line broadening also. It gives values less than thatobtained by AFM. This may be because AFM gives the grain size with surroundings such as oxides.Nanograins are built of several coherent diffraction domains that also causes the grain to look larger in size.Magnetic properties were studied by vibrating sample magnetometer. M-H curves were recorded for all thefilms at room temperature and at10K.. At 10K the films having thickness 200,150,100 and 80 nm show thecoercivity values 430, 571, 611 and 1112 Oe and saturation magnetisation 233, 173, 170, 97 emu/ccrespectively. The coercivity of the films increase with decrease in thickness while saturation magnetisationdecrease with decrease in thickness. The higher coercivity for low thickness film is attributed to the fact thatas the thickness decreases the grain size also decreases and this causes increase in grain boundary and theconsequence of which is increase in coercivity[2]

MM-O5

HEALTH AND USAGE MONITORING OF COMPOSITE STRUCTURESWITH SMART MAGNETOSTRICTIVE SENSORY LAYER

Anand Kumar & Bishakh BhattacharyaIIT, Kanpur

Fundamental research and development in smart materials and structures have shown great potentialfor enhancing the functionality, serviceability and increased life span of civil and mechanical infrastructuresystems. Researchers from diverse disciplines have been drawn into vigorous efforts to develop smart andintelligent structures that can monitor their own conditions, detect impending failure, control damage andadapt to changing environments. The potential applications of such smart materials and systems areabundant--ranging from design of smart aircraft skin embedded with smart sensors to detect structural flaws,bridges with sensing and actuating elements to counter violent vibrations and flying micro electro-mechanicalsystems with remote control for surveying and rescue missions. Smart structures are generally created throughsynthesis by combining sensing, processing and actuating elements integrated with conventional structuralmaterials such as steel, concrete, or composites. Composite structures are now gaining attention due tooverriding advantages over the conventional metallic structures. The conventional non destructive evaluationtechniques are not very effective in monitoring the structural integrity of composite structuress due to theirmicro-mechanical complexities. Various types of smart patches e.g. PZT patches and PVDF films have been

ISRS-2008 61

used as smart alternatives to sense and detect damage in composite structures. Magnetostrictive materials,like piezoelectric materials, can be used both as sensors and actuators. With the commercial availability ofthe magnetostrictive material Terfenol-D in particulate form, it is feasible to develop particulate sensors todetect damage with minimum effect on structural integrity. These smart sensors provide real time sensing byexploiting their functional properties. They are light in weight, consume less power and have better reliability.In present investigation, the electromagnetic response in the MS layer at the onset of delamination in one ofthe weakest ply of the composite laminate has been analyzed. For the numerical analysis, a number ofsymmetric and asymmetric carbon epoxy laminates with one of its layers embedded with Terfenol-D particleshave been taken. Terfenol-D layer experiences a change in stress due to onset of delamination causing achange in its magnetic state which can be sensed as induced open circuit voltage in the sensing coil enclosingthe laminate beam. The effect of material properties, lamination schemes and placement of MS layer on thesensing capabilities has been analyzed. Classical laminate theory has been used.

MM-P1

ELECTRICAL AND MAGNETIC STUDIES OF MONOVALENT DOPED CMR MANGANITES

Kalyana Lakshmi .Y and Venugopal Reddy .P Department of Physics, Osmania University

In recent times, monovalent (A Li, Na, K, Rb & Ag) doped rare earth manganites are found to exhibit

significant CMR at or near room temperatures at low fields. Among these, K and Ag have been tested asoxidation catalysts for exhaust gauges in internal combustion engines. The physics of these manganites isless understood. Therefore, a systematic investigation is carried out after synthesizing nano crystallinesamples with compositional formula La1-XAXMnO3 (A Li, Na, K, Rb & Ag) and characterizing by X-raydiffraction (XRD) and Transmission electron microscopy (TEM) studies. The XRD data have been analyzedby Rietveld refinement technique and it has been confirmed that most of the materials have Rhombohedralcrystal structure with R‘3 c space group. The particle size is found to vary between 10–55nm. The ferro toparamagnetic and metal-insulator transition temperatures strongly depend composition (x) and dopant andthese are found to vary between 100-330K. A sharp decrease in resistivity is found with increasing magneticfield. The percentage of magnetoresistance is found to increase linearly with decreasing temperature, whichis a typical characteristic of a granular system. The low temperature (T<50K) upturn in the resistivity isanalyzed using the combined effect of weak localization, electron-electron and electron-phonon scatteringmechanism.

MM-P2

EFFECT OF ANNEALING ON THE MAGNETOIMPEDANCEOF Co-Mn-Si-B RIBBONS

Sandhya Dwevedi and Markandeyulu G.Indian Institute of Technology Madras, Chennai

Magnetoimpedance (MI) is the change in the impedance of a soft ferromagnetic material in thepresence of an external steady magnetic field. The MI arises due to skin depth and its origin is the change inthe permeability of the material with respect to external magnetic field. Sensors based on this phenomenonhave ultra high sensitivities compared to the GMR sensors. In this paper, the dependence of MI of as cast

62 ISRS-2008

and annealed Co(68)Mn(5)Si(12)B(15) ribbons on the magnetic field and frequency is presented. High pureelements of the alloy were taken in proper proportions and were melted in an arc furnace under argonatmosphere and then the corresponding ribbons were obtained by melt-spinning method and the as castribbons are amorphous. The crystallization temperature was found to be 573 degree from the DSC study. MImeasurements were done on 7 cm long ribbons in the frequency range 100 kHz – 13 MHz employing theHP4192A impedance analyzer with the application of external magnetic field along the length of the ribbon,up to 80 Oe. The amplitude of the alternating current was maintained at 10 mA during the measurements.The MI is defined as MI% = [{Z(H)-Z(Hsat)}/Z(Hsat)] x 100, where Z(H) is the impedance at the field Hand Z(Hsat) is the impedance at the saturating field. The MI increases with increase in frequency and a valueof 161% was obtained in the as cast ribbon at 13 MHz. The MI versus magnetic field plots exhibited doublepeak behaviour indicating the presence of the transverse domains. Heat treatment was carried out for an hournear the crystallization temperature under vacuum, argon and the nitrogen atmosphere respectively.Annealing under nitrogen atmosphere has increased the anisotropy field leading to a decrease in the MI toas small as 1%. Under the argon atmosphere, brittleness of the ribbon increased and no appreciable changein the impedance was observed while an MI of 43% was obtained when annealed in vacuum.

MM-P3

HALF-METALLIC COMPENSATED FERRIMAGNETIC HEUSLERALLOYS Mn2-XCoXVAl (X = 0.5, 0.75 and 1)

Ramesh Kumar K., Arout Chelvane J., Markandeyulu G. and Harish Kumar N. Indian Institute of Technology Madras, Chennai

Half-metallic ferromagnets (HMFs) are known to have peculiar band structure viz. the majority spinsub-band possess metallic band structure where as the minority spin sub-band exhibit semi-conducting orinsulating type of band structure. Heusler alloys are a class of materials exhibiting half-metallic property,crystallize in cubic L21 structure with stoichiometry X2YZ or XYZ (X and Y are transition metal elementswhere as Z is an element with sp valent electron). Many of these Heusler alloys are magnetically orderedsystems with very high Curie temperature and their crystal structure is very similar to the well knownsemiconducors such as GaAs, GaN etc. Due to these advantages half-metallic Heusler alloys are found to beattractive for magneto-electronic applications. Most of the Mn based ferromagnetic Heusler alloys such asCo2MnZ (Z Al, Si, Ga, Sn and Ge) are extensively studied both theoretically as well as experimentally.Recently, it has been proposed that the Mn moments prefers anti-ferromagnetic coupling if it is occupied inthe X site. The compounds Mn2VZ (Z Al, Ga) are the well studied half-metallic ferri-magnetic systems.These low magnetic moments systems are further advantageous for spintronics applications due to the factthat they do not give raise any stray field in the devices. Hence half-metallic anti-ferromagnetic systemswould be an ideal material for device applications. We have investigated the structural and magnetic propertiesof half-metallic fully compensated ferri-magnetic Mn2-xCoxVAl (x = 0.5, 0.75 and 1) systems. All thecompounds were prepared using an arcfurnace under argon atmosphere and the materials are homogenizedin vacuum for three days at 1073 K. The stochiometry was confirmed by EDS analysis. XRD analysis revealedthat the compounds formed in single phase with a small atomic anti-site disorder which was evident fromthe weak order dependent reflections. The lattice parameter was found to decrease with the Co substitutionfrom 5.864 Å to 5.806 Å indicating the replacement of Mn. Magnetic moment per formula unit was estimatedfrom 5 K magnetization data and the value decreased from 2 B to 0.23 B for the compound with 50%substitution of Co. The reason could be the anti-ferromagnetic coupling between Mn-V moments beingcompensated by the Co-V ferromagnetic coupling with the substitution of Co. Magnetization variation as a

ISRS-2008 63

function of temperature was carried out at the field of 100 Oe and the measurements showed that the Curietemperature decreases with the Co substitution which is consistent with the theoretical estimation of the curietemperature for Mn2VZ (Z-sp valent element) systems.

MM-P4

MAGNETIC PROPERTIES OF La(1-x)Sr(x)MnO3Ramesh Babu, M. Junyang Chen, Han X.F. and Jayavel R.

Anna University, Chennai

La(1-x)Sr(x)MnO3 (LSMO) nanowires are prepared using a simple sol–gel process and alumina oxidetemplate. The as prepared LSMO nanowires are 20 and 200nm in diameter and tens of microns in length.Prepared nano rods were annealed at 700 C for one hour and exhibit polycrystalline perovskite structure.Magnetization and photoluminescence studies were performed from low temperature to room temperature.Field cooled and zero field cooled magnetic measurments with 500Oe field reveals the cluster glass behaviourof the nano rod below Curie temperature. At room temperature hysteresis measurements shows paramagneticnature.

MM-P5

MAGNETOCALORIC STUDIES ON TELLURIUM DOPEDNANOCRYSTALLINE MANGANITES

Rabindra Nath Mahato, Sethupathi K. and Sankaranarayanan V.Indian Institute of Technology Madras, Chennai

Nanocrystalline manganites with perovskite structure R1-xAxMnO3 (where R is a trivalent rare-earthelement and A is the divalent cation) have been the subject matter of large number of recent studies due totheir unusual colossal magnetoresistance along with the other extraordinary structural, magnetic andelectrical properties. The manganite perovskites are also studied for magnetic refrigeration applications dueto their properties of low-field induced high magnetocaloric effect and wide range of their magnetic transitiontemperature below and above room temperature. Nanocrystalline La1-xTexMnO3 (x 0.2, 0.3) compoundswere prepared by citrate complex method. The phase purity and crystal structure of the obtained powder arestudied using powder X-ray diffraction. The crystallite size is measured using Debye-Scherrer formula andit is found to be 40 nm and 36 nm for x 0.2 and 0.3 samples respectively. The scanning electron micrographsof the sample reveals that the sizes of fine particles, are in agglomerated form, decreases as tellurium contentincreases. Transmission electron microscopy image shows that the particles are spherical in shape and theaverage particle size was determined. The magnetic measurements were carried out using vibrating samplemagnetometer and they show Curie temperatures (Tc) of 217 K and 258 K for the samples x 0.2 and 0.3respectively. The magnetocaloric effect is found to be 2.9 J/kg-K in an applied field of 1.2 T forLa0.7Te0.3MnO3 which is large when compared to most of the other perovskite manganites.

64 ISRS-2008

MM-P6

EFFECT OF Pr ADDITION ON THE MAGNETIC PROPERTIESOF Nd2Fe14B/Fe3B NANOCOMPOSITES

Rajasekhar M.1,2, Akhtar D.2, and Ram S.11Materials Science Centre, IIT Kharagpur, Kharagpur, India.

2Defence Metallurgical Research Laboratory, Hyderabad, India.

Nanocomposite magnets composed of hard and soft magnetic phases with grain size in nanometerrange exhibit excellent permanent magnetic properties. These materials also known as exchange coupledmagnets have attracted considerable interest in recent years for development of permanent magnets. A strongcoupling between the soft and hard magnetic grains leads to a high remanence (Br) and maximum energyproduct (BH)max in these materials. Nanocomposite consisting of Nd2Fe14B hard magnetic phase alongwith Fe3B/Fe soft phase(s) has been studied in the recent past. Magnetic properties and the degree of exchangecoupling in nanocomposite magnets depends on microstructural parameters, such as crystallite size, phasedistribution and volume fraction of the hard and soft magnetic phases. Efforts have been made to synthesizesuch materials by melt-spinning, mechanical milling, thin film techniques etc. It has also been suggested thatsome magnetic as well as nonmagnetic elemental additives can further improve the desired permanentmagnetic properties.

In the present study, the effect of partial substitution of Pr for Nd on the crystallization behaviour,phase formation and magnetic properties of Nd4.5-xPrxFe77B18.5 (x 0, 1, 2 and 3) melt spun ribbons havebeen studied. The samples were prepared by melt spinning technique as amorphous ribbons followed byvacuum heat treatment to develop a nanocrystalline microstructure. The as-spun and annealed ribbons werecharacterized using differential scanning calorimetry, X-ray diffraction, magnetic measurement andMössbauer spectroscopy techniques. X-ray diffractograms and thermomagnetic curves confirm the presenceof the Nd2Fe14B hard magnetic phase and soft magnetic Fe3B and Fe phases in the heat treated alloys.Enhancement of Hc and (BH)max was observed for 2 at% of Pr addition. Details of the above investigationsare presented in detail in this paper.

MM-P7

SYNTHESIS, STRUCTURAL AND MAGNETIC NATUREINVESTIGATION OF Fe AND Ni SUBSTITUTED Y2O3 SYSTEM

Manigandan A., Sathiyakumar S., Anbarasu V., Kaliyaperumal L.K. and Jayabalan K.Anna University, Chennai.

Synthesis of new magnetic materials and to characterize its physical properties is important becauseof their potential applications in particularly memory devices. In present work, the newer magnetic materialsY0.75A0.25BiO3 (where A Fe &Ni) was synthesized by Solid-State reaction technique. The single phaseformation and its tetragonal crystallization were studied by Powder X-ray diffraction studies. The wellcrystallization nature of the prepared compounds was observed by Scanning Electron Microscope (SEM)images and the stoichiometric ratio was confirmed by Energy Dispersive X – Ray (EDAX) measurements.The phase transition temperature of both compounds were found to be 600 C and 630 C and the averageweight percentage was found to be 98.94% by Thermal analysis. At room temperature conditionferromagnetic nature of Y0.75Fe025BiO3 system and diamagnetic nature with ferromagnetic contributionof Y0.75Ni025BiO3 system were confirmed by Vibrating Sample Magnetometer (VSM) studies.

ISRS-2008 65

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MP 01

SIMULATION OF CARBON DIFFUSION PROFILE INDISSIMILAR WELDMENT USING DIFFUSION COEFFICIENTS

EVALUATED BY DEN BROEDER‘S METHODSudha C., Saroja S., Terrance A.L.E., Vijayalakshmi M.

IGCAR, Kalpakkam

When dissimilar weldments between 9Cr-1Mo and 214Cr-1Mo ferritic steels are subjected to high

temperature, ‘hard’ and ‘soft’ zones form near the weld interface due to carbon diffusion. Carbonconcentration profile across the weld interface was simulated using a numerical technique in which thediffusion coefficient of carbon, DC was assumed to be a constant. Since the width of the zones changes withheat treatment time, it is necessary to study the change in DC to understand the growth kinetics of the zones.An improved Boltzmann Matano method was used to evaluate DC which showed that carbon diffusion isslower in the hard zone than in the soft zone. This is in agreement with the ratio of the measured width ofhard and soft zones i.e 1:3. In the base metals DC was calculated using Hall’s method and the values for

214Cr-1Mo and 9Cr-1Mo steels were obtained as 1.58 10 11 m2/sec and 9.9 10 11 m2/s respectively

which agree with literature data.

MP-O2

CUBE TEXTURE EVOLUTION CONTROLLED BY GAS –METALATMOSPHERE DURING TRANSFORMATION

IN THE Mn AND Al ALLOYED ULTRA LOW CARBON STEELJai Gautam1&2, Roumen Petrov 1&2, Elke Leunis 3 and Leo Kestens 1&2

1 Materials Science and Engineering Department, Delft University of TechnologyMekelweg 2, 2628 CD Delft, The Netherlands.

2 Dept. of Metallurgy and Material science, Ghent University Technologiepark 903, Ghent, BE 9052, Belgium,3 OCAS N.V., Arcelor Mittal research Industry, Ghent, Belgium

The <100> //ND crystallographic texture also known as the cube fibre texture is of both technical andscientific importance because it contributes to favourable magnetic properties of BCC iron alloys. The <100>directions are the axes of the spontaneous magnetic moments and therefore the directions of easymagnetization. The <100>//ND cube fibre texture is easily obtained in FCC polycrystalline metals and alloysby plane strain deformation and recrystallisation. In BCC metals and alloys this fibre texture is never obtainedthroughout the thickness of material unless specific processing is employed such as directional solidification,cross rolling or high temperature annealing. The frequently used methods to obtain <100> orientations // NDin BCC alloys are based on various ferrite recrystallisation strategies. In contrast, the austenite-to-ferritephase transformation, which is an inherent and significant property of low-carbon steels, has scarcely beeninvestigated to develop cube texture. It is already known that Mn and Al alloyed ULC steels exhibit the <100>// ND and <110>//ND texture on the cold rolled surface after transformation under vacuum. It isshown that this surface texture is predominantly controlled by the lowest surface energy plane at the gas/metalinterface. Although the exact dependence of the interfacial energy between the annealing atmosphere and the

66 ISRS-2008

steel surface on the crystal orientation is largely unknown, it has been widely accepted that the bcc {100}and {110} planes display the lower surface energy. The interfacial energy of these planes can be varied byselecting the furnace atmosphere during transformation annealing.

In the present study different atmospheres like vacuum, inert and reducing gas were used during transformation annealing for inducing a specific surface texture. X-ray diffraction (XRD) and

Orientation Imaging Microscopy (OIM) investigations were carried out on the surface, sub-surface and inthe bulk of annealed sheets to prove the development of the desired cube surface texture in various annealingconditions.

MP-O3

THERMODYNAMIC ASSESSMENT OF THE Ni-Ti-MoTERNARY SYSTEM BY COMBINING FIRST-PRINCIPLES

METHOD AND CALPHAD APPROACHSanthy K. and Hari Kumar K.C.

Indian Institute of Technology Madras, Chennai-600036

Understanding phase equilibria of Ni-Ti-Mo is important for widen its application in biomedical field.The Ni-Ti-Mo is calculated by ternary extrapolation of the constituent binary systems. Thermodynamicparameters of the binary systems were adopted from previous studies. To extend the homogeneity region ofbinary phase into the ternary, the sublattice model for the binary phases were suitably modified. The enthalpiesof formation of hypothetical end-members of these phases are calculated from Ultra Soft Pseudo-Potentialwith plane wave method. A set of model parameter for each phase are obtained using CALPHAD approachby combining first-principle data with available experimental data. The calculated isothermal and verticalsections are compared with experimental results.

MP-O4

LOW TEMPERATURE AQUEOUS SYNTHESIS OF EPITAXIAL ZnO:THERMODYNAMIC CALCULATIONS AND OBSERVATIONS

Jacob J. Richardson and Fred F. LangeUniversity of California, Santa Barbara.

Low temperature synthesis from aqueous solutions is an attractive method of producing epitaxial ZnOdue to low cost and environmental impact as well the ability to perform bottom up patterning and sequentialprocessing on temperature sensitive substrates. The technique however suffers from the lack of a fullunderstanding of the solution behavior and the growth mechanism, which would allow for enhanced controlover the material produced. A simple thermodynamic model is detailed here for predicting the solubility andspeciation of Zn(II) in an aqueous solution. From these calculations it was found that dissolved ammoniaplays a critical role in the solubility of ZnO by forming relatively stable zinc amine complexes. It was alsofound that ZnO should exhibit retrograde solubility with temperature under certain conditions. This behavioris the basis for the construction of a continuous growth reactor. The design of this reactor and experimentalresults are discussed in light of the thermodynamic calculations.

ISRS-2008 67

MP-O5

AB-INITIO CALCULATION OF ELECTRONIC STRUCTURE ANDSTRUCTURAL PROPERTIES OF MgS

Gupta D.C., Sonia Mehra, Subhra Kulshrestha, Singh K.C. and Raypuriya G.S.*Jiwaji University

DFT based ab-initio pseudo potential approach within local density approximation (LDA) using Siestacode has been employed to compute the electronic structure of magnesium sulfide (MgS). The computedband gap is found to be indirect and its value is in good agreement with experimental value. The phase stabilityof MgS has also been computed using Siesta. This compound undergoes structural phase transition from B2)under high pressure. The presently<71>rock-salt to cesium chloride (B1 computed values of lattice constantand zero pressure bulk modulus and its pressure derivative are found to be in good agreement withexperimental data and better than those obtained by earlier workers. The band structure shows thesemiconductor nature of MgS.

MP-P1

A STUDY OF MAGNETRON SPUTTERED THIN FILMS OF TYPE 316STAINLESS STEEL IN ARGON AND NITROGEN ATMOSPHERE

Akila1 B., Dona Amalorpavam1 M., Thirumurugesan R., Kuppusami P.*, Mohandas E. and Johnson I.1Physical Metallurgy Division, Indira Gandhi Centre for Atomic Research, Kalpkkam-603 102.

Department of Physics, St.Joseph’s College, Tiruchirappalli -620 002

Over the last decade, the use of nanostructured materials has already changed the approach to designingmaterials in many applications by seeking structural control at the atomic level and tailoring mechanicalproperties. It is also known that a strong refinement of the grain size can lead to additional increase of strengthdue to the Hall–Petch relationship. With the emergence of methods to produce nanostructures, new routes toenhance properties of metals and alloys have been reported. Type 316 austenitic stainless steel is a widelyused engineering material due to its excellent corrosion and oxidation resistance and good formability.However, application of this material is hindered by its low mechanical strength and poor anti-frictionproperties. Strengthening the stainless steel has drawn much attention in the past decades and variousapproaches have been developed, such as varying its chemical compositions to induce solid solutionhardening and grain refinement. In the present work, thin films of type 316 austenitic stainless steel filmsdeposited on Si(111) single crystal and D-9 alloy substrates by pulsed DC magnetron sputtering in argon andnitrogen atmosphere are investigated. X-ray diffraction of the films deposited with pure argon atmospherefor different substrate temperatures indicate that there is only -phase at lower temperatures (RT- 473K) and

and phases in the temperature range of 673-873K.The size of the nano-crystallites of both and phasesincrease with increasing substrate temperature. The nickel content and deposition temperatures are crucialfactors for phase formation and phase stability.

XRD analysis of the films grown at different nitrogen flow rates indicate that the crystalline structureof the films changed from bcc ferrite , to nitrogen-stabilized fcc austenite , then to expanded austenitephase (also called S-phase) with nitrogen supersaturation, and finally to Fe4N phase. SEM studies at differentsubstrate temperatures confirmed coarsening of particles with increasing substrate temperature.Nano-indentation results showed that there is an increase in the hardness of the deposited films than that ofthe bulk stainless steel.

68 ISRS-2008

MP-P2

PHASE TRANSITIONS AND MICROSTRUCTURE OFTHERMO-RESPONSIVE NANOGEL DISPERSIONS

Brijitta J., Tata B.V.R. and Kaliyappan T. Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603 102

1Department of Chemistry, Pondicherry Engineering College, Pondicherry 605014.

Thermo-responsive nanogel dispersions are polymeric hydrogel particles containing cross-linkedthree-dimensional networks dispersed in water. These particles exhibit sudden decrease in size beyond acritical temperature known as volume phase transition (VPT). As a consequence, the volume fraction (f) ofthese particles is tunable over a wide range by varying T but without changing the number density np of theparticles. Further, the interparticle interaction between the particles in the dispersion can also be tuned fromrepulsive to attractive as a function of T. Hence these nanogel dispersions serve as an ideal condensed mattersystem to study cooperative phenomena such as structural ordering and phase transitions by varying f and T.Apart from the fundamental interest, these nanogel dispersions are studied with great interest due to theirpractical applications: drug delivery, artificial muscles, photonic crystals, and sensors.

One of the fascinating phenomenon of these nanogel dispersions is that they freeze into a crystallineorder with lattice constants in the visible range. Hence static light scattering (SLS) is the appropriate tool toinvestigate the structural ordering in these suspensions. The time scales associated with the motion of theseparticles are in the dynamic light scattering (DLS) regime. The structural ordering of larger size particles(diameter d > 300nm) can be investigated in real space using confocal laser scanning microscope (CLSM).We report here, the results obtained using these techniques in thermo-responsive Poly(N-isopropylacrylamide) nanogel dispersions with varying np and T.

We have synthesized monodisperse PNIPAM microgel spherical particles of two different sizes (d =273 nm and d = 512 nm) in an aqueous medium by free radical polymerization method. From the mothersuspension, different samples with varying np were prepared by dilution. The np for samples S1, S2, S3 andS4 are 4.36 1011, 4.36 1012, 8.71 1013, 1.01 1014cm 3 respectively.

Volume phase transition

To study the effect of temperature on particle size, dilute sample S1 was prepared. This sample wasfound to be non-interacting (gas-like) by performing SLS measurements. At T 25 C the average diameterd of the particles was found to be 273 nm. The particle size was found to vary as a function of T. Anon-continuous collapse transition, known as volume phase transition (VPT) was found to occur at around32 C [1 4]. This transition was found to be reversible upon lowering the T. Below the VPT these gel particlesare highly swollen in water, but upon increasing the temperature above the VPT they rapidly de-swell to acollapsed polymer globule [1-4]. Because of this effect, on increasing the temperature from 25 C to 40 Cthe particle size is found to decrease from 273 nm to 114 nm, which corresponds to about 93% change in thevolume of the particles. Below VPT water is a good solvent for the polymer whereas above VPT water turnsto be a poor solvent.

Melting/Freezing Transition

A concentrated suspension S3 upon repeated annealing above the VPT showed iridescence due toBragg diffraction of visible light. Iridescence in the samples suggests that particles order into a crystallinestate. SLS studies on this sample have revealed the occurrence of first Bragg peak at 2.84 105 cm-1 from

ISRS-2008 69

which the lattice constant is determined to be 383nm. The melting transition of these crystals was identifiedby monitoring the Bragg peak intensity, Imax as a function of T. For the first time, we found that the intensityof the Bragg peak exhibits a sudden decrease at around 26oC. The sudden change in intensity is also associatedwith loss of iridescence suggesting the melting of crystals into a liquid state at 26oC. Further we observedthat the first peak position to remain same across the meting transition suggesting no measurable change innp across this transition. Though the phase behavior of PNIPAM nanogel dispersions closely resembles thatof hard-sphere colloidal system, the volume fraction f at which the crystallization appears is much higher fwas found to be 0.93 at 25 C and 0.85 close to the melting. Such high values of f suggest that PNIPAMparticles behave as soft spheres. This crystalline assembly of the nanogel particles can be used as athermo-sensitive photonic crystal and also as temperature sensor.

Fluid-Fluid transition

Upon further increasing the T of sample S3 beyond the melting point, the peak first peak intensity wasfound to decrease and showed a change in slope at 30.5$C. Beyond 30.5 C, the structural ordering in the

suspension was found to be gas-like. The change in slope across 30.5 C was identified as fluid-to-fluidtransition temperature as the structure changes from liquid-like to gas-like without a change in np. From SLSstudies sample S2 is found to be liquid like ordered and this sample also exhibited a fluid-fluid transitionsimilar to that observed in S3 upon increasing T.

By analyzing the volume fractions across the transitions, we conclude that the observed phase behavioris to due repulsive soft-sphere interactions.

Glass-like order: Sample S4 with np 1.01 1014 cm-3 did not show iridescence. Further the ensembleaveraged electric-field correlation function f(q,t) as a function of time t obtained from DLS measurementsshowed non-decay suggesting that the structural ordering in S4 is glass-like.

Microstructure of PNIPAM microgel crystal

We have observed crystallization in suspensions of 512nm particles. Since these crystals are relativelyturbid, we investigated the microstructure of these crystals using CLSM. We observed (111) planes of crystalsto be parallel to the coverslip having point defects and grain boundaries. The lattice constant of these crystalsis found to be 620nm with long-range order extending over several micrometers. Analysis of stack of opticalslices recorded along (111) direction (z-stacks) showed crystalline regions with FCC and HCP stacking. The3D-pair correlation function calculated from particle positions, which are obtained by image analysis of thez- stacks, have confirmed HCP structure.

To summarize we have synthesized monodisperse PNIPAM nanogel particles of different diametersand observed variety of phase transitions as a function of T in samples of varying f. CLSM studies on largesize particles showed an overall HCP structure with domains of FCC and HCP co-existence.

MP-P3

STUDY OF PHASE TRANSITION IN SmTe THROUGHAB-INITIO PSEUDO-POTENTIAL APPROACH

Gupta D.C., Subhra Kulshrestha, Sonia Mehra, Poonam Sharma and Ashok, Baraiya K. Condensed Matter Theory Group, School of Studies in Physics, Jiwaji University, Gwalior-474 011

ab-initio pseudo-potential approach has been used to compute the structural properties of SmTe. Inthis approach, we have used the local density approximation (LDA) that is based on exchange-correlation

70 ISRS-2008

energy optimization for calculating the total energy. The optimized lattice constant (a = 6.5936 Å) for SmTewhich agrees well with the experimental value (a = 6.6008 Å). This compound is found to be stable in B1(NaCl structure) and undergoes a structural phase transformation to B2 (CsCl structure) under pressure. Thevalue of phase transformation pressure and zero pressure bulk modulus (PT = 13.64 GPa and B0 = 38.8 GPa)show reasonably good agreement with their corresponding experimental data (PT = 12.9-14 GPa and B0 =40 GPa). Beside this, we have also analyzed the change in the nature of bands at different pressures.

MP-P4

KINETICS OF HCP TO BCC PHASE CHANGE IN PURE TITANIUM :EFFECT OF HEATING /COOLING RATES ON TRANSFORMATION

ASYMMETRYJosephine Prabha1 A., Raju2 S., Jeyaganesh2 B., Arun Kumar Rai2, Mohandas2 E.,

Vijayalakshmi2 M. and Johnson3 I.1 Bishop Heber College, Tiruchirappalli, 620017

2 Physical Metallurgy Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603 1023 St. Joseph’s College, Tiruchirappalli, 620 002 .

The kinetics of polymorphic changes in pure metals is a topic of both basic and applied interest. Albeithaving a long history with extensive investigations on various theoretical and experimental fronts, a firmunderstanding of the structural transformation kinetics as dictated by microstructural and thermomechanicalconstraints is still elusive. Facilitated by the recent developments in advanced in-situ experimental techniquesand also by the enhancements in the theoretical armory, certain basic issues connected with allotropic phasechange have resurfaced to offer further feed into applicable basic research. It is in this connection that wehave undertaken to study the kinetics of a hcp to bcc phase transformation in pure titanium using acombination of thermal analysis and metallography.

It emerges that within the range of heating and cooling rates adopted in this study, namely 1 to 99 Kmin-1, the on-heating transformation kinetics can be nicely accounted for by a standard KJMA(Kolmogorov-Johnson-Mehl-Avrami) prescription of a simple nucleation and growth phenomenon, with ofcourse a mild heating rate dependent values for the apparent (overall) activation energy. It is further supposedthat there is a nice power-law scaling of the transformation kinetics with heating rate, if an Arrheniusformulation of activation is considered phase nucleation and growth. On the contrary, the reversetransformation bcc to hcp that occurs on cooling, despite showing a certain degree of superficial resemblanceto the on-heating one, is not described at all by the KJMA formalism. In fact, the observed kinetics is betterdescribed by an empirical formalism attributed to Kamamoto, or to a lesser extent by the Koistinen-Marburgerrelation for the martensitic mode, if the later stages of transformation are ignored. Apart from generating asystematic dataset on the heating / cooling rate dependence of transformation characteristics, including thenature of cooling rate dependent microstructural characteristics (grain size, hardness), the present studybrings out certain outstanding conceptual issues on the mechanics asymmetry between onward and reversetransformation modes in simple polymorphic change.

ISRS-2008 71

MP-P5

PRESSURE INDUCED PHASE TRANSFORMATIONIN THORIUM PNICTIDES

Gupta D.C., Baraiya A.K., Singh K.C., Subhra Kulshrestha, Raipuriya G.S. and Sonia Mehra. Condensed Matter Theory Group, School of Studies in Physics, Jiwaji University, Gwalior – 474 011

Department of Physics, Govt. Modal Science College, Gwalior – 474 001

Thorium pnictides (ThP, ThAs, ThSb) have NaCl (B1) structure at ambient condition and transformto CsCl (B2) phase under pressure. The survey of the literature revealed that a wealth of measured data isavailable on these compounds, but a very scant amount of theoretical works have been done on them. Earlierworks have, in general calculated the band structure or phase transition of these compounds. A modifiedcharge-transfer potential (MCTP) model has been developed to study the phase transition properties of ThX(X=P, As, Sb) compounds. The present MCTP model consist of long-rang coulomb and charge transferinteraction modified by covalency effect found in these compounds and short-range repulsive interactionextended up to next-nearest neighbours. The present model have been used to compute the equilibrium latticeparameters at zero as well as at high pressures in both the phases, cohesive energy ,phase transition pressure,equation of state, volume collapse. The results on these transition pressure (PT = 29.76, 24.70 and 8.95 GPa)shows a reasonably good agreement with the available experimental data (PT = 30, 25 and 9.12 GPa) forthese pnictides. The equation of state in both NaCl (B1) and CsCl (B2) structure has also V(P)/V(0)) beenobtained. The calculated value of the volume collapse ( at the phase transition (9.45, 9.7 and 14.62%) arecloser to the experimental data (11.9, 10 and 9.4%).

MP-P6

PHASE TRANSITION AND THERMAL PROPERTIESOF SULFIDES OF Ca, Eu AND Th

Gupta D.C., Kailash, Singh C., Raipuriya# G.S., Baraiya* A.K., Subhra Kulshrestha and Sonia Mehra,Condensed Matter Theory Group, School of Studies in Physics,

Jiwaji University, GWALIOR – 474 011 (M.P.) INDIASchool of Studies in Physics, Jiwaji University, Gwalior-INDIA

We have investigated the pressure induced structural phase transition in sulfides of Ca, Eu and Th bymeans of modified charge-transfer (many-body) potential (MCTP) model. This model includes effects dueto long-range attraction due to Coulomb, charge-transfer mechanism and covalency effects and short-rangeoverlap repulsion extended up to next nearest interactions and zero point energy. It is interesting to note thatthe present MCTP model is capable to explain the Cauchy-violations C12 C44 0 . These compounds

undergo structural transition from six-fold coordinated NaCl (rock-salt) to eight-fold coordinated CsCl phaseunder high pressure. The computed values of the phase-transition pressure (PT = 39.23, 20.25 and 18.75 GPa)shows reasonably good agreement with the available experimental data for CaS, EuS and ThS, respectivelyand better than the values computed earlier. The calculated values of relative volumes V(P)/V(0) associatedwith compression have also been obtained and plotted in figures to depict the phase diagrams / equation ofstate for these sulfides. The phase-transition volume collapses at transition pressure are 10.32%, 11.70%, and8.90% for CaS, EuS and ThS, respectively. The pressure variation of second order elastic constantsC11,C12 and C44 and there combinations BT C11 2C12 /3, CL C11 C12 2C44 /2 a n d

CS C11 C12 /2 is computed and depicted in figures. It is found that they also show a change at transition

72 ISRS-2008

pressure. Besides this, we have T), calculated the thermal properties, i.e., Debye-temperature ( m. It is found

that the present model, which hasaverage wave velocity less parametric (range , hardness (b) and chargetransfer potential (fm)) nature, is capable of predicting mechanical and thermal properties of sulfides ofalkaline/rare earth materials.

MP-P7

MATHEMATICAL MODELING OF CARBOTHERMALREDUCTION OF ILMENITE

Manju M.S., Savithri SUniversity of Kerala

A novel mechanism for the carbothermal reduction of Ilmenite in a rotary kiln reactor is proposed andvalidated with a mathematical model. The proposed mechanism involves two solid state diffusion processesnamely the diffusion of atomic carbon through the metallic iron layer and the diffusion of oxygen throughthe oxide (mainly rutile) phase. It has been reported by many researchers that the diffusion of CO gas to theoxide phase is inhibited by the formation of a dense metallic iron product layer around the surface of theparticle. Hence in the present study oxygen diffusion is assumed to be rate controlling. A mathematical modelis developed to evaluate the rate of reaction of a single Ilmenite spherical particle. The results of modelingare validated with the experimental data reported in literature for reduction of ilmenite in commercial rotarykiln reactors. It has been observed that the reduction rate increases with temperature at constant pressure.The excellent agreement of modeling results with experimental data confirm that the oxygen diffusiontowards the oxide/iron interface acts as the rate determining step during the carbothermal reduction of ilmenitein a rotary kiln reactor.

ISRS-2008 73

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N1-O1

DEFORMATION STUDIES OF NANOCRYSTALLINE NICKEL ANDNICKEL-ALUMINA COMPOSITES BY MICRO-INDENTATION

Pradipta Ghosh and Atul Chokshi H.IISc Bangalore

In this study the mechanical behavior of nanocrystalline nickel and nickel-alumina composites wasinvestigated over a range of grain size (12nm to bimodal). The nanocrystalline materials were obtained bypulse-electrodeposition technique. A special surfactant was used for codepositing Al2O3 particles with

nickel. The isothermal stability of both deposits was characterized at 523 K. It was observed that Al0O3

particles retarded the grain growth kinetics at 523 K, despite their large sizes.

Microindentation tests with constant loading rate to load ratio were done at 303 K for understandingthe strain rate effect and deformation mechanisms in these materials. A four fold increase in the strain ratesensitivity was observed ~ 0.01 to~ 0.04 for both nanocrystalline nickel and nickel-alumina composites,compared to coarse grain nickel. It was suggested that grain boundary contribution may be playing asignificant role below 16 nm for nanocrystalline nickel. This was supported by the activation volume (V*)measurements. It was observed that, V* increases gradually from ~5b3 to ~100 b3 (b, burger’s vector) withincreasing grain size beyond 12 nm, suggesting a gradual change of deformation mechanism.

N1-O2

DEVELOPMENT & CHARACTERISATION OF POLYURETHANEPROTECTIVE AUTOMOTIVE COATINGS INCORPORATING

LAYERED NANOSILICATES & FUMED SILICAGaurav Verma*, Anupama Sharma and Anup Ghosh K.

Panjab University Chandigarh

Advent of new models and glittering colours in the passenger cars and other vehicles is the prerogativeof the highly competitive automobile industry. Apart from the exterior shape the finish attracts the consumerthe most. Various industries catering to the automotive coatings are facing challenges in clearcoats. Theclearcoat is the coating layer that forms the last interface to the environment. It should have unchanged highgloss and color stability over a long period and must be able to resist environmental etch, bird droppings, carwash machines and other outside influences like industrially generated chemicals & pollutants. Attempt hasbeen made to in-situ polymerize a two pack Polyurethane consisting of a polyol & isocyanate withincorporation of layered silicates (MMT, O-MMT, Cloisites & Bentone 38) in low loadings (0-5wt %) toimprove the barrier properties and solvent resistance. The first challenge faced is proper dispersion,distribution & homogenization of layered silicates into the two pack system to get optimum properties. Thisis tackled by use of combination of mechanical, magnetic mixers as well as ultrasonication and confirmedby XRD analysis. The effect of various organic solvents on the ‘macroscopic swelling’ of layered silicateshas been investigated apart from increasing the interlayer distance. The organic modification of MMT intoOMMT is also shown by FTIR and XRD. The barrier properties and swelling kinetics have been studied andimprovements observed by incorporation of layered silicates. This improvement is related to properdispersion and distribution of layers of silicates in PU system.

74 ISRS-2008

After incorporation of fumed silica (average size less than 100nm) as filler in very low weight % (0-2wt %) it was found to improve anti graffiti properties and accomplish ‘easy cleaning coats’. Kept inenvironment over specific periods of time fumed silica nanocoatings shows better resistance. At weight %above 3wt% adhesion tests failed. Low weight % addition of either layered silicates or fumed silica in PUsystem doesn’t affect the ‘clarity’ of coatings if the dispersion and distribution is uniformly achieved.

N1-O3

FLUORINE DOPED TiO2 NANOCATALYSTFOR DEGRADATION OF AN ORGANIC POLLUTANT

Sivarajasekar N., Saravanan K., Velmani N.Kongu Engineering College/ Anna University

In this study tetra butyl titanate was used as a precursor, and Anatase fluoride doped TiO2 sol

F TiO2 catalyst was prepared by a modified sol-gel hydrothermal method. The influences of F doping,

temperature of hydrothermal, values of medium pH on the morphology and crystallization were studied. Themicrostructure and morphology of sol sample were characterized by XRD, TEM, UV–Vis–DRS, and particlesize distribution (PSD). The results showed that F TiO2 nano particles in sol were spherical and partly

crystallized to anatase structure, and dispersed in the aqueous medium homogeneously and that the averageparticle size was ca. 10.2 nm calculated from XRD and TEM results. It was also found that the crystallizationand adsorption of particles significantly improved by addition of fluorine. The batch reactor experimentsshowed that the photocatalytic activity for decomposition of phenol was enhanced remarkably with the dopingof fluorine.From batch reactor data, it was known that the rate of degradation followed the first order kinetics

N1-O4

HIGH TEMPERATURE TENSILE BEHAVIOR OF ELECTRODEPOSITED NANO-Ni-P ALLOY

Prasad M.J.N.V. and Chokshi A.H. Department of Materials Engineering, Indian Institute of Science, Bangalore – 560 012, India

Nano Ni-P alloy foils were synthesized by pulsed electrodeposition from Watts bath with phosphorousacid (H3PO3) as a source of phosphorous. Nano-Ni-P foils with a grain size down to 3 nm were obtainedwith saccharin (sulfur based organic compound) in bath. The thermal stability of the as deposited nano Ni-1.1at% P alloy with an as-deposited grain size of 6 nm and a nano Ni-2.4 at% P alloy with an as-deposited grainsize of 3 nm was studied using differential scanning calorimetry and isothermal annealing. The high P alloywith a larger fraction of Ni3P particles exhibited sluggish grain growth. The nano Ni-P alloy samples withtwo different P levels, with the same grain size, were tested under tension at different temperatures and strainrates. The Ni-1.1 P exhibited almost zero ductility at 573 K and it exhibited superplasticity with 470 %

elongation at a temperature of 777 K and at a strain rate of 3 10 3 s 1. The Ni- 2.4 P also exhibitedsuperplasticity at 777 K, with a higher elongation to failure of 890 %. There was significant grain growthduring the heating up to test temperature so that the initial grain sizes just before testing at 777 K were ~300nm and 200 nm in the low P and high P alloys, respectively. Strain rate jump tests yielded a strain ratesensitivity m of ~0.5. Microstructural characterization of the fractured specimens indicated considerablegrain growth and cavitation near the fracture tip.

ISRS-2008 75

N1-O5

SYNTHESIS, ELECTRICAL AND DIELECTRIC PROPERTIES OF THENANOCRYSTALLINE Ce0.8Eu0.2O2-8

Ashok Kumar Baral and Sankaranarayanan V.Indian Institute of Technology Madras, Chennai

In the recent years, the fluorite structured nanocrystalline materials of pure and doped ceria haveattracted much attention for being studied and improved the electrochemical properties for the applicationin intermediate temperature solid oxide fuel cell (SOFC). In this work, the nanocrystalline material of 20mol% europium (Eu) doped ceria Ce0.8 Eu0.2 O2 with average grain size of 12 nm is synthesized by

citrate complex method. The phase purity and microstructure of the material are studied using powder XRDand HRTEM. The material is found to be ionic in nature with ionic conductivity of 1.39 10 4 Scm 1 at

550 C. The material shows two different temperature regions of conductivity with activation energies 1.13

and 0.91 eV below and above 470 C respectively. The electric modulus spectra show the presence of arelaxation peak corresponding to bound motion of oxygen vacancy around the Eu+3 ions in the lattice. Themigration energy of the oxygen vacancy in the long range motion is found to be 0.77 eV whereas associationenergies are found to be 0.36 and 0.14 eV in two different temperature regions.

N1-P1

ELECTRICAL RESISTIVITY AND MORPHOLOGICAL PROPERTIESOF PP/MMT/OMMT HYBRID NANO COMPOSITES

Rajarajan S., Raja J.Sathyabama University, Chennai

The preparation of hybrid polymer nanocomposites by melt compounding Polypropylene(PP) withmontmorillonite(MMT) and organically modified montmorillonite(OMMT)using polypropylene graftedmaleic anhydride(PP-g-mA)as compotibilizer is described.Compositions with MMT and OMMT content1%,3%,5% and 7% were prepared and tested.The influence of nanoclays on morphology of thenanocomposites was studied by Scanning Electron Microscopy(SEM).

The results of this investigation of surface resistivity and volume resistivity of polymer hybridnsnocomposites are presented.

N1-P2

CHARACTERIZATION OF CdS-ZnS NANOCOMPOSITESSYNTHESIZED BY MICROWAVE-ASSISTED SOLUTION METHOD

Selvarajan P., Kumar E. and Balasubramanian K.Aditanar College of Arts and Science, Tiruchendur, Tamil Nadu

In the recent years, nanoscience is an intense and rapidly developing field. Due to the arrangement ofatoms or molecules on the 1 to 100 nm scale, nanocrystalline materials possess unique and interestingmechanical, optical, electrical, magnetic, thermal and other properties. Nanocomposites are also possessingunique properties like pure nanomaterials. In this work, We report the synthesis of nanocomposites ofCdS-ZnS by wet chemical method using a microwave oven. The precursors used were cadmium nitrate, zinc

76 ISRS-2008

nitrate and thiocarbamide. The capping agent used to control the size of nanoparticles was ethylene glycol.At different pH values (10, 12, 14) , the nanocomposites of CdS-ZnS were prepared. The synthesizednanocomposites were centrifuged, filtered, washed and dried.

The nanocomposites were characterized by powder XRD, SEM, TEM, atomic absorption, dielectricand conductivity studies. Powder XRD studies reveal the hexagonal structure of nanocomposites and the sizeof nanoparticles was estimated to be below 100 nm. The morphology of most of the nanoparticles wasobserved to be spherical from SEM and TEM studies. The synthesized nanocomposites of CdS-ZnS werepelletized and dielectric and conductivity studies were carried out. The obtained results from various studiesare presented and discussed.

N1-P3

TEMPERATURE DEPENDENT PROPERTIES OF NANO CERIA THINFILMS PREPARED BY PULSED LASER DEPOSITION

Balakrishnan1 G., Kuppusami* P., Thirumurugesan R., Mohandas E., Chandramohan2 P., Srinivasan2 M.P. and Sastikumar D.

1 Physical Metallurgy Division,2Water and Steam Chemistry Division, BARCF, Kalpakkam-603 102, Tamilnadu

1National Institute of Technology, Tiruchirapalli-620015, Tamilnadu

Cerium Oxide CeO2 or Ceria is an ionic metal oxide in the visible and near infrared (VIS-NIR)

spectral region. It possesses physical properties such as high refractive index (2@ 500 nm), large dielectricconstant (~26), wide band gap (3.6eV), good transparency, chemical stability, good adhesion, hardness andthermal stability. Also, CeO2 exhibits cubic structure with a lattice parameter (a= 0.541nm), matching with

silicon. Hence CeO2 thin films have been extensively used as ultra thin gate oxide in CMOS technology,

stable capacitor devices for large scale integration, stable buffer layers between high temperaturesuperconducting materials and silicon substrates, single and multilayer coatings for optical devices,electro-chromic windows , oxygen sensors, solid oxide fuel cells, dynamic random access memory (DRAM),and corrosion resistant coatings.

CeO2 thin films have been prepared by pulsed laser deposition technique using KrF excimer laser of

248 nm wavelength with a repetition rate of 10 Hz. The sintered ceria pellet was used as target material andSi (100) and glass were used as substrates. The films were prepared at various temperatures with an optimized

oxygen partial pressure of 3 10 2 mbar. In the present study, the influence temperature on the structuraland optical properties of the films were investigated. The x-ray diffraction (XRD) analysis showed that thefilms were polycrystalline with cubic structure. The crystallite size increased from 19 to 50 nm in thetemperature range RT- 973 K. At room temperature, the intensity of (111) reflection was maximum and atan increased temperature in the range 573-973 K, the (200) reflection was predominant. The texturecoefficient for the (200) reflection increased with the increase of temperature. The Raman studies showed apeak appeared at ~ 463 cm-1 due to the F2g Raman active mode of CeO2 cubic structure. However, therewas no peak in the Raman spectrum for the films prepared at room temperature because of poor crystallinity.When the temperature was in the range 573 K-973 K, the Raman shift was observed from 459 to 464 cm-1.The trend observed in the FWHM of Raman lines are in agreement with our XRD study. The optical studieshave been carried out using UV-VIS-NIR spectrophotometer with a wavelength range of 190-3000 nm. Asmall variation in the band gap energy from 3.0 to 3.3 eV was noticed.

ISRS-2008 77

N1-P4

RAMAN SPECTROSCOPIC INVESTIGATIONS ON NANOSTRUCTURED ZINC FERRITE

Singh J.P., Gagan Dixit, Srivastava R.C. and Agrawal H.M. G. B. Pant Univ. of Agriculture & Technology, Pantnagar, Uttarakhand (India)

Zinc ferrite has normal spinel structure, in which all ferric ions remain at octahedral site and zinc ionsat tetrahedral site. It is paramagnetic at room temperature in bulk form. This material exhibits unusal physicaland chemical properties when size is reduced to nano regime. Due to its interesting properties in nanoregimethis material is widely studied to understand the underlying physics. The present investigation aims to studythe microstructural state and other local environment of this material through the Raman spectroscopy.

Zinc ferrite was synthesized by using the nitrate route [1,2]. The precursor for the present investigationwas sintered at 400 C, 500 C, 700 C, 900 C and 1000 C. The particle size at these sintering temperatureswere found to be 12, 16, 18, 31 and 62 nm respectively by using the Scherrer’s formula. TEM micrographalso supports the particle size estimated from XRD pattern. We have recorded the Raman spectra for all thesamples in the range 200-1500 cm-1. The Raman system used for the present study consists of Ar-ion laser.The laser power used for recording the spectra is 5 mW. As zinc ferrite belongs to Oh7(Fd3m) space group,it should exhibit five Raman active modes: A1g 669cm 1 , Eg 410cm 1 and 3T2g

193cm 1, 300cm-1, 540cm-1) [3]. The recorded spectra were Lorentz fitted and the values of severalRaman modes are estimated. A visual inspection shows that all spectra consist of three bands in the 200-800cm-1. It may be concluded that due to broadening of the Raman bands other active modes may merge together.For the present case no Raman band is observed at 1320 cm-1 which rules out the presence of Fe2O3 in oursamples.

N1-P5

EFFECT OF ANNEALING ON THE SURFACE MORPHOLOGY OF ZnONANORODS GROWN ON POROUS SILICON SUBSTRATE

Amizam13 S., Rafaie1,3 H.A., Mamat 2,3 M.H., Khusaimi1,3 Z., Sahdan2,3 M.Z., Abdullah1,3 S. and Rusop2,3 M. 1Faculty of Applied Sciences,

2Faculty of Electrical Engineering,3 Centre for Nanotechnology Laboratory (NANO-SciTech), Institute of Science,

University Technology MARA, 40450 Shah Alam, Malaysia

The effect of annealing on the surface morphology of ZnO Oxide (ZnO) Nanorods grown on PorousSilicon (PSi) substrate was studied. The zinc nitrate hexahydrate (Zn(NO3)2.6h2O) and hexamethenamine(C6H12N4) was synthesized . A homogenous and stable solution was prepared by dissolving theZn(NO3)2.6h2O in a solution of DI water and hexamethenamine. The molar ratio of nitrate solution andhexamethenamine is 1:1. Afterthat the immersion method used to prepare the ZnO Nanorods on PSi. Thesamples were annealed at 200, 400, 600 and 800 C for 60 min. The surface morphology and optical propertiesof the samples was characterized using Scanning Electron Microscope (SEM) and photoluminescence (PL)spectroscope. The result indicated that the ZnO Nanorods morphology is most sensitive to the temperature.Room-temperature PL measurements shows the ZnO nanorods exhibit a strong ultra-violet (UV) emissionof 400 nm and several weak emissions in the blue and green bands.

78 ISRS-2008

N1-P6

MAGNETOCAPACITANCE, MAGNETORESISTANCE ANDMAGNETOSTRICTION STUDIES OF NANOSIZED NiZn FERRITE

SYNTHESIZED BY HIGH ENERGY BALL MILLINGSreenivasulu1 G., Markandeyulu2 G., Murty1 B.S.

1Dept. of Metallurgical and Materials Engg. and 2Dept of Physics,Indian Institute of Technology Madras, Chennai-600036.

Ni Fe1.98O4\ Ni (1-x) ZnxFe1.98O4 (x = 10, 20, 30, 40 and 50 mol %) were synthesized by high energyball milling with the starting materials were NiO (99.9% pure), Fe2O3 (99.5% pure), CoO (99.9% pure). Themilled powders were compacted and sintered at 1200 C. The phase formation was confirmed by X-raydiffraction technique. The X-ray densities were calculated and were compared with bulk densities of thesintered samples were about 97-99%. The nanocrystallinity is retained even after sintering and this has beenconfirmed by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The effect ofZn content on DC resistivity, magnetization, magnetocapacitance, magnetoresistance and Magnetostrictionwere studied. DC resistivities were measured with Keithley electrometer and were found to be in the rangeof 108 to 109 -cm, which is 2 to 3 orders of magnitude higher than Zn free ferrite (106 to 107 -cm). Themagnetization measurements were carried out with the help of vibrating sample magnetometer. Themagnetization increased from 51 to 77 emu/g with increasing Zn content as compared to the pure Ni ferrite(46 emu/g). Magnetocapacitance (8%), magnetoresistance (10%) and Magnetostriction measurements werecarried out with the electromagnets at a sweeping field of 1tesla. Raman spectroscopy analysis has beencarried out to correlate the site occupancies of the individual elements with the magnetic moment tounderstand the influence of Zn.

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N2-O1

CHARACTERIZATION AND CONDUCTIVITY STUDY OFPOLYPYRROLE NANOROD SYNTHESIZED BY INTERFACIAL

METHOD IN POLYVINYL ALCOHOL MATRIXBhadra J., Sarkar D.Gauhati University

The intriguing optic and electronic properties of - conjugate back bone conducting polymers havecaptivated much interest in the scientific community. We report here the polymerization of pyrrole byinterfacial method in polyvinyl alcohol (PVA) matrix taken pyrrole and PVA in the ratio of 1:100 by weight.The surface morphology study was done by FESEM, which shows fine nanorods of approximate length of2ìm and diameter of 50 nm. Further the films are characterized by FTIR, UV, XRD and PL for optical study.The FTIR results significants peaks for interlinking of polypyrrole (PPY) and PVA molecules. The UV spectrashows characteristic peak PPY-PVA at 284 nm. And PL spectra shows at excitation wavelength 344 nmemission occurs at 692 nm. The films show homogeneous structure with good electrical properties and nonohmic I-V characteristics.

N2-O2

EVIDENCE OF FORMATION OF ZnO NANOCLUSTERSIN VAPOR PHASE

Antaryami Mohanta and Raj, Thareja K. Indian Institute of Technology, Kanpur

Pulsed laser ablation technique is an efficient way of depositing high quality thin films of variousmaterials such as metals, semiconductors, and ceramic for a variety of applications. Growth of ZnO thin filmsby pulsed laser deposition technique has been made increasing attention amongst the researchers recently,because ZnO is a promising semiconductor materials for optoelectronic devices in the ultraviolet range dueto its wide band gap (~ 3.37 eV) and its high excitonic binding energy (~ 60 meV) which assures the lasingaction due to possibility of excitonic recombination at room temperature (~ 25 meV). As laser ablated plasmais the main source of pulsed laser deposited thin films, a detailed investigation on the physical and chemicalproperties of the laser ablated species are inevitable. A third harmonic of Nd: YAG laser [355 nm, pulse-widthof 5 ns, 10 Hz repetition rate] is used for ablation of a sintered target of ZnO (99.999 % purity) to produceplasma in air. The plasma expands in air; the species of ZnO plasma collides with the molecules of air whichslows down the species inducing rapid cooling of plasma and initiation of chemical reactions, electron-ionrecombination, production of clusters etc. In this abstract, an evidence of formation of ZnO clusters in ZnOplasma by photoluminescence (PL) technique and by Rayleigh scattering experiment is reported. In order toobserve the photoluminescence, the fourth harmonic of a Nd:YAG laser [266 nm, pulse-width of 4 ns, 10 Hzrepetition rate] referred as probe beam is passed through the ZnO plasma perpendicular to the expansion axisof plasma at various distances from the target surface and at various time delays with respect to the ablatingpulse. The emission spectra are recorded by imaging on to a fiber placed perpendicular to the axis of boththe beams, and the other end of the fiber is coupled to the entrance slit of a monochromator. An Intensifiedcharge coupled device (ICCD) is used at the exit slit of the monochromator in order to record the spectra. An

80 ISRS-2008

emission spectrum at 1 ìs delay of probe pulse (266 nm) with respect to the ablating pulse is observed whichshows the Zn I transition lines along with a broad-emission band. This broad-emission band falls in thespectral region of PL band of ZnO and is attributed to the PL from gas-suspended ZnO clusters. As the delaytime of the probe pulse with respect to the ablating pulse increases, decreasing intensity of the Zn I transitionlines with increasing PL intensity is observed. This shows an evidence of formation of ZnO clusters in ZnOplasma. On the other hand, Rayleigh scattering of visible radiation has widely been used for verification ofthe existence of clusters. Therefore, a second harmonic of Nd: YAG laser [532 nm, pulse-width of 6 ns, 10Hz repetition rate] referred as probe beam is passed perpendicular to the expansion axis of plasma at variousdistances from the target surface and at various time delays with respect to the ablating pulse (355 nm), andthe emission spectra are recorded. The Zn I transition lines are observed at 500 ns delay with respect to theablating pulse without passage of the probe pulse (532 nm). When probe pulse (532 nm) is passedperpendicular to the expansion axis of plasma at 500 ns delay with respect to the ablating pulse, a signal at532 nm, referred as Rayleigh scattered signal is observed along with the ZnI transition lines. On increase ofdelay time of probe pulse with respect to the ablating pulse, decreasing intensity of Zn I transition lines withincreasing intensity of the scattered signal is observed. At 2 MUs delay of probe pulse with respect to theablating pulse, the scattered signal dominates the Zn I transition lines. At higher delay (~ 5 MUs) of the probepulse with respect to the ablating pulse, only the scattered signal is observed with complete suppression ofZn I transition lines. This shows the evidence of formation ZnO clusters due to cooling of plasma by collisionof the laser ablated ZnO species with the molecules of the ambient (air) and the signal observed at 532 nmis the scattering of the probe pulse by the gas-suspended ZnO clusters.

N2-O3

PHYSICAL AND OPTICAL PROPERTIES OF NANOSTRUCTUREDZnO DEPOSITED ON SILICON DIOXIDE CATALYST

USING DIFFERENT THICKNESSSahdan M.Z., Kamaruddin S.A., Mamat M.H., Amizam S., Rafaie H.A., Khusaimi Z., Hashim Saim,

Noor U.M., Ahmed A.Z., Abdullah S., Rusop M.University. Teknologi MARA Malaysia

Nanostructured materials have been researched recently due to their novel properties compared to theirbulk materials. Nanostructured ZnO has been grown using various techniques since difference techniqueswould produced different nanostructures. This paper presents new approach of using silicon dioxideSiO2 as catalyst in sol-gel method to grow nanostructured ZnO. The physical and optical properties of

nanostructured ZnO deposited using this approach is studied and the correlation between the catalystthickness and the material properties will be discussed. The physical characterization using scanning electronmicroscope (SEM) and x-ray diffractometer (XRD) shows different SiO2 thickness has produced different

ZnO nanostructures. The optical properties using UV-VIS-NIR and photoluminescence (PL) spectrometerhave shown ZnO is very sensitive at ultraviolet (UV) region. This UV emission and absorption is stronglycorrelated with the surface morphologies and crystallite size.

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N2-O4

SYNTHESIS AND CHARACTERIZATION OF EDTACAPPED ZnS NANOPARTICLES

Vijai Anand K., Karl Chinnu M., Marx Nirmal R., Mohan kumar R., Alagesan T., Pandian K., Mohan R., Jayavel* R.Presidency College, Chennai

The study of nanomaterials provides an opportunity to observe the evolution of material propertieswith crystal structure, size and shape. The synthesis of nanomaterials is an ultimate challenge of modernmaterial research that has an outstanding fundamental and potential technological consequence because oftheir special properties such as large surface to volume ratio, increased activity, special electronic propertiesand unique optical properties as compared to those of the bulk materials. Among a variety of semiconductormaterials, the binary metal chalcogenides of group II have been extensively studied because of theiroutstanding potential applications owing to their non linear optical and luminescence properties, quantumsize effect and other important physical and chemicals properties. Among II-VI compound semiconductors,ZnS is one of the important optoelectronic device materials which are used for a variety of applications suchas optical coatings, photoconductors, optic-modulators and electro-optic modulators owing to its wide bandgap energy. In this present work, we have synthesised Zinc sulfide nanoparticles by a simple chemicalco-precipitation method using disodium ethylenediaminetetraaceticacid (EDTA) as capping agent. The roleof EDTA was to stabilize the nanoparticle against aggregation and also to provide chemical passivation thatleads to a significant influence on the chemical, optical and electronic properties of nanoparticles. Thesynthesized ZnS nanoparticles were characterized by X-ray diffraction (XRD), UV-Visible absorption, FTIRand fluorescence emission spectra in order to study their crystal structure and optical behaviour.

N2-O5

CHEMICAL VAPOUR SYNTHESIS OF PURE AND DOPEDNANOCRYSTALLINE TITANIA AND ITS CHARACTERISATION

Imteyaz Ahmad Md a, Bhattacharya a S.S and Horst Hahn baDepartment of Metallurgical and Materials Engineering,

Indian Institute of Technology Madras, Chennai- 600036, India.b Darmstadt University of Technology, 64287 Darmstadt, Germany and Director,

Institute for Nanotechnology, Forschungszentrum Karlsruhe GmbH,Hermann-von-Helmholtz-Platz 1 76344 Eggenstein-Leopoldshafen, Germany.

During the last decade chemical vapour synthesis (CVS) has been projected as one of the viablemethods for the synthesis of high pure, nanocystalline ceramic powders with a good control over the resultantpowder characteristics. In this process, a metallorganic precursor is decomposed/pyrolysed within thewell-defined high temperature zone of a hot-wall reactor and the nanocrystalline powders synthesized thereinare collected by a suitable method. In the current work it was demonstrated that the chemical vapour synthesis(CVS) route is a suitable method for synthesis of highly crystalline, strain-free and agglomeration- free pureas well as doped/modified nanocrystalline titania. Titanium tetra isopropoxide was used as the precursor forthe synthesis of pure nanocrystalline titania, while triethyl boron and ammonium hydroxide were respectivelyused as additional precursors for doping/modification of nanocrystalline titania with boron and nitrogen. Thepowders synthesized were well below 10 nm with a narrow size distribution and exhibited a high degree ofcrystallinity. The synthesised powders were characterized by the standard methods of x-ray diffraction, highresolution transmission electron microscopy, nitrogen adsorption etc. as well as by using specialized methodssuch as X-ray photoelectron spectroscopy, electron paramagnetic resonance spectroscopy, nuclear magneticresonance and UV-vis spectroscopy in case of the doped/modified powders. The results of the studies andthe conclusions drawn are reported.

82 ISRS-2008

N2-P1

MICROWAVE ASSISTED SYNTHESIS AND CHARACTERIZATION OFEUROPIUM DOPED YTTRIUM OXIDE NANOPARTICLES FOR

LUMINESCENCE APPLICATIONSSrinivasan R., Rajeswari Yogamalar N. and Chandra Bose A.

Department of Physics, National Institute of Technology, Tiruchirappalli - 620 015

Oxide nanomaterials have prospective applications in the field of phosphor industries. Rare earth dopedyttrium oxide (Yttria) nanomaterials are very important in the field of luminescence and phosphor materials.The luminescence efficiency of these oxide nanomaterials are depends upon the crystallite size and synthesismethod also. These materials are prepared by various techniques such as hydrothermal, solvothermal,co-precipitation, and combustion method. Here microwave synthesis is used for preparation of europiumdoped yttria nanoparticles. In this method the reaction time is very short and controlling the particle size issimple by changing the power level of microwave source. The domestic microwave oven is modified slightlyfor holding the reflux condenser set up. The required amount of molar solution of yttrium nitrate and europiumnitrate was taken in round bottom flask and this is fitted with reflux condenser set up. The solution was heatedby microwaves with power 700 W and frequency 2.45 GHz for 30 minutes. Then the certain amount ammoniais added with above solution. The precipitate is obtained and this precipitate is washed by water and dried.The final powder is annealed at different temperatures. All the samples are characterized by XRD for particlesize, SEM for morphology, TEM for particle size, FTIR for structural study, and UV for band gap calculations.All the result will be presented in the conference.

N2-P2

INFLUENCE OF NANO SIZE INERT FILLERS ON THE TRANSPORT CHARACTERISTICS OF MECHANOCHEMICALLY

SYNTHESIZED NaSn2F5Laxmi Narayana Patro and Hariharan* K.

Solid State Ionics Laboratory, Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India

NaSn2F5 dispersed with nano size fillers such as Al2O3 and SiO2 of various concentrations have beenprepared through high energy ball milling at room temperature. XRD, DSC, and SEM result indicates thebiphasic nature of the samples. The transport properties of the samples have been investigated by means ofimpedance spectroscopy. In the present investigation, Al2O3 fillers of different particle sizes (60nm, 1ìm)have been used and it is found that the improvement in conductivity decreases with increase in the particlesize of the filler. An enhancement in conductivity of one order in magnitude is obtained for NaSn2F5 withAl2O3 dopant concentration of 10 mol%. The activation energies for all the composites (0.900.02eV) areclose to the activation energy of pure NaSn2F5. The transport number measurement by dc polarizationtechnique with the cell of configuration Ag/ electrolytes /Ag reveals that the electronic transport number is0.01. This indicates the enhanced conductivity in the present investigated system is due to F- ions. Further,the impedance data have been analyzed in the frame work of complex permittivity and electric modulusformalisms to obtain the better insight of the relaxation dynamics of the materials. The scaling result of theconductivity and imaginary part of modulus shows the relaxation mechanism is independent of temperature.

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N2-P3

SYNTHESIS AND CHARACTERIZATION OF Ce DOPEDZnO NANOCRYSTALLINE

Ilanchezhiyan P., Mohan Kumar G., Subramaniam M. and Jayavel R. Anna University, Chennai

Zinc Oxide is a wide band gap n-type semiconducting material having wide applications such as gassensors, optoelectronic devices, such as light-emitting diodes and solar cells. In this report, Ce doped ZnONanorcrystalline thin Films have been synthesized using Spray Pyrolysis Technique onto Si (100) substrates.XRD analysis is carried out to determine the crystal structure. The diffraction peak shifts towards the higherangles as Ce is added which shows that it has entered the ZnO lattice and substituted Zn ion. Morphologicaland luminescence property were carried out using Scanning electron microscope and photoluminescence.

N2-P4

SYNTHESIS AND CHARACTERIZATION OF METALSULPHIDE NANOPARTICLES BY THERMAL DECOMPOSITION

OF METAL COMPLEXESMarx Nirmal R., Pandian K., Jayabalan K.

Anna University, Chennai

A detailed investigation has been carried out on synthesis and characterization of Metal sulphidenanoparticles by thermal decomposition of metal complexes in presence of hexadecylamine. Different metalcomplexes such as cadmium pyrrolidine dithiocarbamate complex and Zinc prrolidine dithiocarbamatecomplex have been prepared by simple chemical route. The growth of metal sulphide nanoparticles (CdS,ZnS) were synthesized by thermal decomposition on both normal and microwave heating of metal complexin presence of Hexadecyl amine (HDA). HDA has the functioning of solvent as well as shape directing agent.The prepared CdS and ZnS nanoparticles were characterized by X-ray diffraction (XRD), Laser Raman,Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX) and High resolutiontransmission electron microscopy (HRTEM) studies. The optical properties of CdS and ZnS nanoparticleswere studied through UV-visible and fluorescence emission spectral techniques. The present work proposesthermal decomposition technique as one of the simple way to synthesis large quantity of semiconductornanoparticles.

N2-P5

AQUEOUS SYNTHESIS OF Co DOPED CADMIUMSULPHIDE NANOPARTICLES

Saravanan L., Tamil Selvan S., Pandurangan A., Jayave R.Centre for Nanoscience and Technology, Anna University Chennai

Colloidal inorganic nanocrystals are of great interest both for fundamental research and technologicalapplications, due to their strong size and shape dependent properties and excellent chemical processibility.The introduction of dopants and defects in solids has always been a problem of central importance to materialsscience in view of their implications for device science and technology. In recent years, CdS nanostructuralmaterials have been widely investigated. In this work we have synthesised cobalt doped cadmium sulfide

84 ISRS-2008

nanocrystals with different cobalt concentration by aqueous precipitation method. Dopant incorporation wasrecognized by X-ray diffraction (XRD) and the morphology was observed by scanning electron microscopy(SEM). Variation in the luminescence properties was analysed using fluorescence spectroscopy and the resultswill be discussed.

N2-P6

LOW TEMPERATURE SYNTHESIS OF SHAPE- AND SIZE- CONTROLLED ZnO NANOSTRUCTURES BY

SOLVOTHERMAL TECHNIQUESaravana Kumar R., Sathyamoorthy* R., Sudhagar P., Matheswaran P., Mageshwari K.

PG and Research Department of physics, Kongunadu Arts and Science College,Coimbatore - 641 029. Bharathiar University

In recent years, Zinc oxide (ZnO) nanostructures have been extensively investigated due to their greatpotential for fundamental studies of the effects of morphology, dimensionality and size on the materialsproperties as well as for their application in optoelectronic nanodevices. In the present work, ZnOnanoparticles with different surface morphology were obtained by solvothermal reaction technique withoutusing surfactants. The influence of solvent and reaction temperature on the growth of nanoparticles wasstudied. ZnO nanoparticles prepared under different solvent showed that the polarity of solvent and thereaction temperature greatly influences the growth of the nanorods. X-ray diffraction (XRD) patterns exhibithexagonal wurtize structure. Transmission electron microscopy (TEM) showed single crystalline nature ofthe nanorods. Optical band gap energy was calculated by diffused reflectance spectroscopy. Presence of defectlevels and excitons emission behavior of ZnO nanostructures were investigated by photoluminescence (PL)spectra. Both optical and PL spectra reveals the quantum confinement effect. The results are discussed basedon growth mechanism.

ISRS-2008 85

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N3-O1

STRUCTURE AND PROPERTIES OF POLY (BUTYLENESEBACATE-CO-BUTYLENE ISOPHTHALATE)/CLAY

NANO-BIOCOMPOSITE.Siva kumar* G., Nanthini R. and Suganya G.

*Department of Chemistry, Panimalar Engineering College, Chennai-602103 Post- Graduate and ResearchDepartment of chemistry Pachaiyappa’s College, Chennai 600030

Aliphatic-aromatic biodegradable random copolyester, poly (butylene sebacate-co-butyleneisophthalate) PBSeI was synthesized by a two step direct melt polycondensation method. This copolyesterwas characterized by solubility, viscosity measurements, IR, 1H NMR, 13C NMR and thermal studies. But,to be a real alternative to classical synthetic polymers and find applications, biodegradable polymer propertieshave to be enhanced. Synthesis of nano–biocomposites, which are obtained by incorporation of nanofillersin to a biomatrix, is an interesting way to achieve the polymers with characteristic properties. In present study,the bio nanocomposites were synthesized by dispersing different weight percentage (1, 3 and 5%) of Organomodified montmorillonite clay (OMMT) into the biodegradable polyester matrix by solvent intercalationmethod. The structural characterization and thermal analysis have been carried out to understand better therelationship between the nanofillers structuring and the properties of nano-biocomposites. The X-raydiffraction patterns obtained for the systems confirmed the nanodispersion of OMMT-clay in the polyesternetworks. The results show that the clay incorporation enhances the thermal properties of PBSeI due to theexfoliated structure of the nanocomposites formed, and thus may increase the applicability of thisbiodegradable polymer in different fields.

N3-O2

DESIGN AND CHARACTERISTICS OF A BURNERFOR THE CONTROLLED PRODUCTION OF NANOPARTICLES

IN A FLAME REACTORManjith Kumar B, Bhattacharya S S and Shet U S P

Indian Institute of Technology Madras, Chennai.

The study of nanoparticles has invited the attention of researchers across the globe due to the possibilityof developing unusual properties, which are often not obtained in the conventional bulk form. Since theseproperties are closely dependent on the size and morphology of the synthesized powders, efforts are on todevelop effective methods for producing nanomaterials in relatively large quantities with controlled size andmorphology.

Flame reactors are among the most promising gas phase synthesis routes to large volume productionof submicron and nanosized particles. They offer reasonably good control of the product particle properties,short process chains, a self-purifying high temperature synthesis environment, and a wide product range. Inprinciple, these reactors contain diffusion burners within a reaction chamber. The burner consists of concentrictubes for the independent passage of the precursor, a dilutant medium, fuel and an oxidizer gases. The gasesflow through the tubes to reach the burner head, where they mix and facilitate burning and

86 ISRS-2008

combustion/pyrolysis of the precursor resulting in the production of nanoparticles of interest. Thesenanoparticles are then collected by a suitable system. The flame characteristics play an important role indeciding the size and morphology of the nanoparticles.

In this work the design and characteristics of a burner to be used for the controlled production ofnanoparticles in a flame reactor was studied. It is expected that the velocity differences at the burner outletwould influence reactant mixing and, therefore, the nucleation and onset of particle growth. The flame height,on the other hand, would decide on the residence time and the extent of particle growth. A brass burner,suitable for the synthesis of oxide nanoceramics (such as titania or alumina) was designed and fabricated.This was initially tested for flame stability using acetylene as fuel and oxygen as oxidizer. The gas flow rateswere regulated and controlled using standard flow meters. The minimum and maximum gas flow rates andflow velocities at which the flame was stable and soot-free were determined, thus giving an idea of the stableregion of operation. The flame heights were measured at the beginning of an oxidation flame as well as atthe point where the flame started to become discontinuous and was repeated for different flow rates. Theresults of these studies are reported.

N3-O3

SYNTHESIS OF PURE AND CO DOPED SnO2 NANOPARTICLESSATHYASEELAN B. and JAYABALAN K.

Anna University, Chennai.

Tin oxide materials present numerous applications like gas sensors, basic components in optoelectronicdevices or nano and ultrafiltration membranes. Moreover, SnO2 polycrystalline materials prepared by sol-gel

technique have recently been used for shielding fluoride glasses against corrosion. In the present work, pureand Co doped SnO2 Nanoparticles have been synthesized using Sol-Gel Technique. Tin chloride and Cobalt

chloride were used as metal sources. XRD analysis shows that all the samples consist of single phase withrutile phase. The diffraction peak shifts towards the higher angles as Co is added which shows that it hasentered the SnO2 lattice and substituted Sn site. The crystallite size of the pure and Co doped samples lie

between 12 to 18 nm. Morphological characterizations were carried out using Scanning electron microscope.

N3-O4

SYNTHESIS OF SILVER NANOFLUIDS WITH POLY(VINYLIDINE FLUORIDE)

Phule1 A.D., Susrutha1 B., Ram1* S., Tyagi2 A.K.1Material Science Centre, Indian Institute of Technology, Kharagpur-721 302, India

2Solid State Chemistry Section, Applied Chemistry Division, BARC, Mumbai -40009, India.

Nanofluids consisting of nanoparticles (NPs) of noble metals dispersed in an organic or inorganic fluidoffer wide spread applications as computing systems, sensors, colored dyes, pharmaceutical tools, catalysts,biomedical materials, electronic devices, and nonlinear optical devices [1,2]. Apart from the opticalapplications as bandpass filters, there is a tremendous interest in achieving an optical absorber or emitter inthe uv-visible to infrared regions [3]. Here we report part of our broad investigation on synthesis of opticalsilver nanofluids and composites with selective ferroelectric media. A simple Ag Ag0 chemicalreduction reaction and in-situ dispersion of the resulting Ag atoms in form of Ag-NPs in polymer moleculesof poly(vinylidiene fluoride) (PVDF) has been developed and explored to devise stable Ag-PVDF nanofluids.An organic solvent such as dimethylformamide (DMF) was used to obtain the precursor solutions from PVDF

ISRS-2008 87

and AgNO3 as the starting reagents. The reaction was carried out by adding AgNO3 (dissolved in DMF) into

PVDF in DMF under the utrasonication and heating conditions at 50 60 C in air. The Ag-NPs content wasvaried as 0.1, 0.5, 2.0, and 5.0 wt% in order to devise Ag-PVDF nanofluids of selective optical properties.All these nanofluids (which appear in selective apparent colors depending upon the Ag-contents) are radiationemitting in the uv-visible region. Strong photoluminescence bands appear at 392, 394, 403, and 405 nm whenirradiating the nanofluids at 220-300 nm from a xenon source. In general, the spectrum presents considerablered-shift with increasing the Ag-content over the range. The results are analyzed in correlation to size andshape of Ag-NPs which were studied with transition electron microscopic images.

N3-O5

SYNTHESIS AND CHARACTERISATION OF BORON NITRIDENANOTUBES BY CHEMICAL VAPOUR DEPOSITION (CVD) METHOD

Shrine Maria Nithya J. and Pandurangan* A.Institute of catalysis and petroleum technology, A.C. Tech, Anna University, Chennai – 600 025,India

Boron nitride nanotubes (BNTs) found to be a novel material in high temperature applications,bio-sensors, nano-electronic devices and drug delivery systems. BNTs could be used in the fabrication ofnovel devices in which pure carbon nanotube do not perform very efficiency. Generally BNTs weresynthesized by Arc discharge, laser ablation and CVD method. Among these CVD method is best way tosynthesis of boron nitride nanotubes using boric acid (Boron source) and urea, ammonium chloride, ammoniagas as the nitrogen source by using CVD method we achieved good purity of BNTs in the short period ofreaction time. The synthesized BNTs were characterized by XRD, FT-IR, TGA, scanning electronmicroscopy (SEM), and transmission electron microscopy (TEM) techniques. The reaction parameters suchas temperature, molar ratio of the reactants and time were optimised for the better formation of BNTs. Theseresults open up a new kind of synthesis method with low expensive and important perspectives for use inlarge quantity production.

N3-P1

HYDROTHERMAL SYNTHESIS AND STUDIES OF PURE AND NiDOPED ZnO NANORODS FOR PHOTOCATALYSIS APPLICATIONS

Mohan Kumar G., Ilanchezhiyan P., Jayavel R. Centre for Nanoscience and Technology, Anna University, Chennai.

Pure and Ni doped ZnO Nanorods have been synthesized using Hydrothermal Technique. Zinc acetateand Nickel acetate were used as metal sources. XRD analysis shows that all the samples consists of singlephase with hexagonal wurtzite structure. The diffraction peak shifts towards the higher angles as Ni is addedwhich shows that it has entered the ZnO lattice and replaces Zn ion. The crystallite size of the pure and Nidoped samples lie between 12 to 18nm. Morphological characterizations were carried out using Scanningelectron microscope. The morphology of the samples appears to be in the form of rod like structures.Photocatalysis reaction were carried out for the both pure and Ni doped samples, whose results were analyzedusing IR and UV (vis spectra). Ni doped samples were found to be more efficient while compared to the pureZnO nano crystallites.

88 ISRS-2008

N3-P2

SYNTHESIS AND CHARACTERIZATION OF Bi2S3 NANORODS BYSURFACTANT-ASSISTED SOLVOTHERMAL METHOD

Mageshwari K., Sathyamoorthy* R., Sudhagar P., Saravanakumar R.PG and Research Department of physics, Kongunadu Arts and Science College,

Coimbatore - 641 029. Bharathiar University

Bismuth sulfide Bi2S3 nanorods have been prepared by surfactant-assisted solvothermal method.

Bismuth acetate and thioacetamide were used as precursors. Triton 100-X was used as surfactant forcontrolling the morphology of the product. The microstructure and optical properties of the Bi2S3 nanorods

were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersiveand X-ray spectroscopy (EDX), optical absorption and PL spectrum. The XRD pattern reveals that theBi2S3 nanoparticles possess polycrystalline structure with orthorhombic phase. SEM images identified the

nanorods formation. The rod-like morphology obtained by short-time ultrasonic treatment for 10 minutes.The optical and photoluminescence properties of Bi2S3 nanorods have been characterized. The UV absorption

spectrum reveals a clear band shift towards the blue region. The results are discussed on the basis of reactiontime, temperature and surfactant for the formation of nanorods.

N3-P3

SYNTHESIS AND CHARACTERIZATION OF SOL-GEL DERIVEDNANOCRYSTALLINE TIN OXIDE THIN FILM FOR GAS SENSOR

APPLICATIONSVasudevan R., Vijayalakshmi S., Sathayaseelan B., Alagesan T., Jayabalan K.

Anna University, Chennai

In the present investigation, nanocrystalline tin oxide SnO2 semi- conducting thin film was coated

on the glass substrate by sol-gel spin coating technique. The deposited sample was annealed at 200 C toimprove the crystallinity of the film. The XRD confirming the tetragonal structure and the particle size wascalculated approx. 25 nm also it is confirmed through the AFM topography technique. The SEM analysisreveals that the SnO2 film was uniformly coated over the glass substrates and the particles were in the

nanometer range. The functional groups and the band gap of the material were calculated using the FT-IRand UV-Visible spectroscopy respectively. Under these conditions, SnO2 would be a promising material for

the gas sensor also it has sharp increase in conductivity when exposed to a reducing gas.

N3-P4

PREPARATION OF ANATASE TiO2 NANO-PARTICLESBY SOL-GEL METHOD

Karthik K., Kesava Pandian S., Victor Jaya N.Anna University, Chennai.

Titanium dioxide TiO2 is widely used in various technological applications such as photocatalysis,

sensors, and photo electrochemical solar cells. The applications of TiO2 are strongly dependent on the

crystalline structure, morphology and size of particles. The high surface to volume ratio is inherent in a nanoparticle which is useful for photocatalysis and hence most of the studies are focused on the nanosized

ISRS-2008 89

TiO2 with the purpose of improving the light absorption. Nano TiO2 powders have been prepared by sol–gel

technique using titanium (IV) isopropoxide as the precursor. The crystalline structures and anatase phase ofthe nano TiO2 powders have been characterized by using X-ray powder diffraction (XRD) and Laser Raman

Spectroscopy. The surface morphology of the prepared nano TiO2 was carried out by using SEM. The average

particle size was found to be ~17nm. The anatase phase of the prepared TiO2 was conformed by the three

(A1g, B1g, and Eg) Raman active modes.

N3-P5

EFFECT OF METAL CONCENTRATION AND TEMPERATUREFOR THE SYNTHESIS OF

Atchudan R. and Pandurangan* A.*ICPT, A. C. Tech, Anna University, Chennai-25, India

Appropriate weight percentage of antimony (Sb) supported on mesoporous MCM-41 molecular sieveswere prepared by wet impregnated method. The above prepared mesoporous Sb/MCM-41 molecular sieveswere calcined at 500 C for 3 hrs. The calcined materials were characterized by various physicochemicaltechniques such as X-ray diffraction (XRD), thermo gravimetric analysis (TGA), DRS-UV spectroscopy andscanning electron microscopy (SEM). The calcined samples were used as catalytic template for the growthof carbon nanotubes using acetylene as a carbon precursor by chemical vapor deposition technique at 700,800 and 900 C. The reaction parameter such as effect of metal concentration and temperature were optimizedfor better formation of carbon nanotubes. The deposited carbon materials were purified by acid treatmentand air oxidation. The purified materials were characterized by XRD, SEM, HRTEM and Ramanspectroscopy techniques. Carbon nanotubes morphology was observed from HRTEM. The good thermalstability and high productivity observed in this study suggested that the metal loaded MCM-41 could be akind of promising supports for catalytically synthesizing CNTs.

N3-P6

ECONOMICALLY SYNTHSISED NANOSIZE SiCBY ADAPTING SOL- GEL AND

Anthuvan Rajesh J. and Pandurangan* A. ICPT, A. C. Tech, Anna University, Chennai-25, India

A two-step sol–gel processing was used to synthesize SiO2– carbon hybrid gels as SiC precursors,

with tetraethoxysilane (TEOS), and starch being the starting materials, oxalic acid (OA) andhexamethylenetetramine (HMTA) are being the catalysts. At the first step TEOS was prehydrolyzed underthe catalysis of OA. At the second step HMTA was added to facilitate gelation. The influences of the molarratio of OA/TEOS and prehydrolysis time on the sol–gel reaction were investigated. There existed an optimumOA/TEOS ratio where prehydrolysis time needed to form transparent gels was the shortest. The conversionof the gels to silicon carbide powders via carbothermal reduction was complete when heated at 1300 C for2 hrs. The homogeneous distribution of silica within carbon and their loose structure result in the formationof nanosize silicon carbide powders. The as synthesized sample was heated in air at 700 C for removal ofthe residual carbon and treated by nitric acid and then hydrofluoric acid for elimination of unreacted silicaand other impurities. The precursors and their carbothermal reduction products are investigated by XRD,FT-IR, Raman spectroscopy, XPS, SEM with EDX, and HRTEM. The effect of heat treatment temperatureon the synthesis of SiC powder was also discussed.

90 ISRS-2008

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OM-O1

EFFECT OF ANNEALING TEMPERATURE ON PROPERTIES OF ZINCOXIDE THIN FILM GROWN BY THERMAL-CVD

Rafaie1,* H.A., Suhaidah 1 A., Mamat 2 M.H., Khusaimi1 Z., Sahdan2 M.Z., Abdullah1 S. and Rusop2 M.1Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia

2Faculty of Electrical Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia

Zinc oxide (ZnO) thin films were successfully grown on glass substrate by vapor phase Thermal-CVDmethod. Vapor process by Thermal-CVD was employed at low deposition temperature in the range of400 C 500 C. The samples were characterized using Scanning Electron Microscope (SEM), UV-VIS-NIRSpectroscope and Photoluminescence Spectroscope (PL). SEM micrograph confirmed the growth of ZnOstructure while PL spectra showed that the PL intensities increase as the deposition temperature increases.An estimated bandgap energy obtained from UV-VIS-NIR also reported.

OM-O2

DEVELOPMENT OF HIGH QUALITY LARGE SIZE UNIDIRECTIONALADP SINGLE CRYSTAL FOR ELECTRO-OPTICAL DEVICES

Rajesh P. and Ramasamy P. Centre for Crystal Growth, SSN College of Engineering, Kalavakkam- 603 110, India

<10 0> directed ammonium dihydrogen phosphate single crystal has been grown using the uniaxiallysolution-crystallization method of Sankaranarayanan–Ramasamy (SR). The size of the grown crystal is 40mm in diameter and 50 mm in thickness. The growth rate was approximately 1 mm/day. The grown crystalswere characterized by UV–Vis spectroscopy, Vicker’s hardness and dielectric studies. ADP crystal grownfrom SR method has 10% higher transparency than the ADP crystal grown from conventional method.Dielectric constant and dielectric loss increases with increase in temperature for all the frequencies. This maybe due to the contributions of all the four polarizations such as electronic, ionic, dipolar and space chargesare predominant in the lower frequency region. The hardness of ammonium dihydrogen phosphate singlecrystal increases with increase of load. The cracks were formed in the conventional grown crystal at 100 g,but no cracks were observed up to 100g in SR ADP. Comparing the <1 0 0> plane of the conventional methodgrown ADP crystal with <1 0 0> directed SR method grown ADP crystal, the optical transparency, dielectricconstant and Vicker’s hardness number are increased and dielectric loss is decreased in SR method growncrystal. The low dielectric loss, higher transparency and higher hardness indicates that the low concentrationof defects in the SR method grown single crystal. These are the requirements for the good electro-opticalmaterial. The result shows that the SR method grown crystal has higher quality than the conventional methodgrown crystal.

ISRS-2008 91

OM-O3

CHARACTERISATION OF CHEMICALLY SYNTHESISEDNANOCRYSTALLINE CADMIUM SULPHIDE FILMS

Kusumanjali Deshmukh, Mukherjee M. and Bhushan S.Pt. Ravishankar Shukla University

The films formed by wide gap II-VI semiconductor are of considerable interest, as their emissionscover the technologically attractive blue and green spectral region. In particular, thin CdS films deserveattention, as these films are an appealing host for photonic devices. It has advantage of size-induced changesin structural, optical and electronic properties, which deviate from the corresponding bulk phase properties.In this paper growth of Nanocrystalline CdS semiconducting films on the glass substrate by means of chemicalbath deposition method (CBD), with Cd CH3COO 2 as Cd ion source, NH2 2CS as S ion sources and

Thioglycerol and Methanol together as capping agent(stabilizing agent) is reported. UV-VIS absorptionspectral studies and SEM images indicate that the volume of capping agents adjust the band gap of CdS toobtain stable and homogenous films. XRD studies reflect the existence of hexagonal planes and confirm theparticle size reduction. Band gaps are found to increase and particle size is found to be in nano region fromoptical absorption studies.

OM-O4

PRESSURE DEPENDENT IONIZATION ENERGIESIN A SPHERICAL QUANTUM DOT

Sivakami1* A., Senthur Pandi 1 R., Chokkalingam1 R., Kanistha1 R., Mahendran1* M. and Navaneethakrishnan2 K.

1Department of Physics, Thiagarajar College of Engineering, Madurai-625 015, India.2School of Physics, Madurai Kamaraj University, Madurai-625 021, India.

At present, there is a considerable interest in the physics and applications of Low-DimensionalSemiconductor Systems (LDSS). The most widely investigated quantum dot system is the GaAs/Ga1-xAlxAs. The quantum dot occurs in the GaAs region with GaAlAs providing the barrier. The opticaland transport properties of semiconductors are sensitive to impurities, external fields and stress therefore, itis important to consider these aspects in heterostructures.

In the present work, a hydrogenic donor is introduced in the GaAs region and calculated the ionizationenergy in a spherical quantum dot. The donor ionization energies in a GaAs spherical quantum dot underhydrostatic pressure is calculated by using a variational approach (with the inclusion of polaronic effects)within the effective mass approximation. The ionization energy is computed as a function of hydrostaticpressure and the dot size with inclusion of the band non-parabolicity and polaronic effects. All the calculationshave been carried out for finite barrier with square well confinement. Our results reveal that, (i) the hydrostaticpressure increases the ionization energy and also the variation is larger for smaller dots only, (ii) as the dotsize decreases the ionization energy increases for the finite potential well and (iii) the hydrostatic pressuredecreases the sub band energy with the different dot size. These results are in good agreement with S TPerez-Merchancano et.al, (J. Phys. Condens. Matter 19 (2007) 026225) in which they have used thevariational approach without considering the polaronic effects. Finally, we concluded that the hydrostaticpressure affects the ionization energies appreciably for narrow dots only. The ionization energies have beeninvestigated for singlet state and will be addressed in the conference.

92 ISRS-2008

OM-O5

INVESTIGATIONS ON MMTC SINGLE CRYSTALFOR LASER APPLICATIONS

Rajesh Kumar T., Jeyasekeran R., Gunaseelan R., Prabha K. and Sagayaraj P.LOYOLA COLLEGE, Madras Univeristy, Chennai, India

Recently, second-order (NLO) materials capable of efficient frequency conversion of visible andultraviolet wavelengths, especially materials which can generate blue-violet light for applications includingtelecommunications, optical computing, optical information processing and optical disk data storage arewidely studied. Manganese mercury thiocyanate (MMTC) crystal is an excellent second-order nonlinearoptical material; it is normally grown by slow evaporation method. Deviated from the earlier article, thepresent work deals with the growth of MMTC by temperature lowering method for the first time. Singlecrystals of nonlinear optical MMTC were grown by temperature lowering method. The UV cut-offwavelength of MMTC was found to be at 373 nm. The blue and violet emission from the crystal was evidentfrom the PL spectrum. The ac and dc conductivity studies are reported. Surface morphology study was doneon the selected face on the grown crystal. Dendrite growth pattern was observed on the surface of the crystalfrom SEM.

OM-P1

STRUCTURAL AND OPTICAL PROPERTIES OF CdONANOCRYSTALLINE THIN FILMS FOR OPTOELECTRONIC

APPLICATIONSTamil selvan S., Saravanan L., Arivuoli D., Jayavel R.

Anna University,Chennai.

From the group of II-VI semiconductors Cadmium Oxide is one of the promising transparentconducting Oxides which have great potential for optoelectronic devices. Compare to other transparentconducting oxides cadmium oxide is uniquely positioned for application in photometry due to its absorptionof light in the blue region of the electromagnetic spectrum. It has been used as heat mirrors in the solar cellsbecause of high reflectance in the infrared region, together with high transparency in the visible region.Formation of cadmium hydroxide at room temperature onto glass substrate from an aqueous alkalinecadmium nitrate solution using a simple chemical bath deposition and its conversion to cadmium oxide (CdO)by thermal annealing treatment has been studied in this paper. The structural, surface morphological andoptical studies were performed for as deposited and the annealed films. The structural analyses revealed thatas-deposited films consists of mixture of Cd OH 2 and CdO, while annealed films exhibited crystalline CdO.

From surface morphological studies, conversion of clusters to grains after annealing was observed. Afterannealing treatment the band gap energy values were changed from the as-deposited films. The results werediscussed in detail.

ISRS-2008 93

OM-P2

MICROSTRUCTURAL, MECHANICAL AND OPTICAL PROPERTIESOF CrN THIN FILMS PREPARED BY PULSED

DC MAGNETRON SPUTTERINGElangovan1 T., Kuppusami* P., Thirumurugesan R., Ramaseshan2 R., Bera3 S., Mohandas E. and Mangala raj1 D.

1Physical Metallurgy Division, 2Material Science Division, 3Water and Steam Chemistry Division, BARCF, IndiraGandhi Center for Atomic Research, Kalpakkam-603 102, India.

1Thin Film Laboratory, Department of Physics, Bharathiar University, Coimbatore-641046, India. PhysicalMetallurgy Division, 2Material Science Division, 3Water and Steam Chemistry Division, BARCF, Indira Gandhi

Center for Atomic Research, Kalpakkam-603 102, India. 1Thin Film Laboratory, Department of Physics, BharathiarUniversity, Coimbatore - 641046, India.

CrN has received considerable interest over the past several years due to its high hardness and corrosionresistance, and for applications as hard, wear, and corrosion-resistant coatings. Chromium nitride (CrN) thinfilms were deposited on (100) silicon and D-9 alloy steel substrates using an asymmetric-bipolar pulsed DCmagnetron sputtering system. The CrN coatings were deposited at different nitrogen flow rates, substratetemperatures, pulse width and frequency. The analyses revealed that the nitrogen partial pressure during filmdeposition had a strong influence on the resulting deposition rate and crystallinity. At low N2 low rates, ( <

2sccm), pure Cr was detected, while at the intermediate flow rates ( < 5 sccm), the hexagonal and cubicphases were obtained [Cr2N and CrN]. Finally, in the range of 10-25 sccm, only the cubic CrN phase was

obtained. Substrate temperature, pulse frequency, and pulse width seem to influence the film or ientation.Also, the films sputtered in pure argon atmosphere contained larger crystallites than those sputtered innitrogen atmosphere. The Cr 2p3/2 and N 1s XPS spectra confirmed the formation of CrN phase. Therefractive index, dielectr ic constant, and absorption coefficient of the CrN coating in the wavelength rangeof 300–1200 nm were determined. The CrN coatings deposited under the optimized process conditionsexhibited an average nanoindentation hardness of 15 GPa and an elastic modulus of 283 GPa.

OM-P3

EFFECT OF 50 MEV Si4+ ION IRRADIATION ON CdS THIN FILMSChithambararaj A., Chandramohan S., Sathyamoorthy* R., Kanjilal D.

PG & Research Department of Physics, Kongunadu, Art & Science College, Coimbatore

In Recent years, the advantage of Swift heavy Ion irradiation finds attention towards the modificationof material properties from its bulk nature. In this paper, we have reported the Swift heavy ion (SHI) irradiationon Cadmium sulphide (CdS) thin films deposited on silicon substrate by using 50 MeV Si4 ions of various

doses from 5 1012 to 5 1013 ions/cm2. The structure, morphology and luminescence properties of pristineand irradiated films were carried out by using x-ray diffraction (XRD), Raman spectra, AFM andPhotoluminescence, respectively. X-ray diffraction studies reveals that the pristine and irradiated CdS thinfilms have cubic or hexagonal phase with preferential orientation along (111) C or (002) H. The improvementin crystallization and degradation of the film has been studied depends on irradiation energy and the resultis in good agreement with Raman studies. The AFM study implied significant changes in the roughness in

the film due to irradiation. From PL, for lower irradiation energy 5 1012ions/cm2 , the defect annihilation

and radiative transition has been observed and at higher irradiation energy 5 1013ions/cm2 further defectcreation and non- radiative recombination is noted, it may be due to lattice disorder in the film structure.

94 ISRS-2008

OM-P4

STRUCTURAL AND OPTICAL STUDIES ON WO3THIN FILMS BY SPRAY PYROLYSIS

Kovendhan1 M., Gokulraj2 S., Ramesh Kumar1 G., Mathivanan1 V., Suriya kumar1K., Sivakumar1 B., Paul Joseph3 D., Venkateswaran3 C. and Mohan1 R.

1Department of Physics, Presidency College, Chennai - 600 005,2Department of Physics, National Institute of Technology, Tiruchirapalli - 620 015,

3Department of Nuclear Physics, University of Madras, Chennai - 600 025.

Tungsten oxide WO3 thin films were deposited onto amorphous glass substrates at different substrate

temperatures ranging from 250 C to 500 C in a spray pyrolysis unit. The precursor solution is prepared bydissolving appropriate quantity of WO3 powder in a mixture of hot ammonia solution and distilled water. The

XRD analysis indicated crystallinity for the films deposited at substrate temperatures above 350 C. The peakvalues 23.10 and 24.06 correspond to the monoclinc (002) and (020) planes of WO3. SEM analysis reveal

variations in surface morphology for films deposited at different substrate temperatures. The UV-Vis analyseswere performed to study the transparency of the deposited WO3 films as a function of substrate temperature. LaserRaman measurements for the deposited films were also carried out at 300 K. The results are discussed.

OM-P5

STRUCTURAL AND OPTICAL CHARACTERIZATIONSOF MN AND IN DOPED ZnS NANOCRYSTALS

Brightson M., Selvarajan P., Freeda T.H., John Kennady S., Meenakshi Sundar S.Sri Paramakalyani College

Undoped and Mn, In doped ZnS nanocrystals have been synthesized using solvothermal technique.Microwave oven was used as a method for this technique. Sizes of the particles were determined using theDebye-Scherrer’s formula from the XRD patterns. Lattice parameter values were calculated using XRDAsoftware and verified with JCPDS files. Band gap energy values were calculated for the four ratios of Mndoped ZnS nanocrystals . SEM and EDAX spectra were taken for the Mn doped ZnSnanocrystals.Co-ordination compounds were identified using the FT-IR spectra for the undoped and dopedcrystals. The results will be discussed in detail in the conference.

OM-P6

PREPARATION AND CHARACTERIZATION OF CADMIUMSULPHIDE NANOCRYSTALS

Nirmala Jothi N.S., Dennis Christy P., Ramalingam G., Muthuvinayagam A. Loyola college, Madras University.

CdS is one of the important II-VI semiconductor due to its wider band gap (2.42 eV) and non-linearoptical properties. CdS nanomaterials have vital applications in flouresence probe, sensors, solar cells,photoelectrocatalysis and light emitting diodes etc. Controlling the particle size not only alters the forbiddengap of the semiconductor, but also its electronic properties. In this investigation, we have reported a newprocess using thiourea and cadmium nitrate at partially low temperature which approach nanoparticles havingapproximate diameter of 40 nm. The synthesized nanoparticles have been characterized using techniquessuch as X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV-Vis absorptionspectroscopy. The experimental results have indicated CdS nanocrystals in single phase with hexagonalstructure. From the TEM images, size of the nanocrystals was measured as 40 nm.

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SE-O1

PARAMETRIC STUDIES OF LASER SURFACE ALLOYINGPROCESSES OF WALLEX 50 AND COLMONOY 88 DEPOSITS

Shivamurthy R.C., Kamaraj M., Nagarajan R., Shariff S.M. and Padmanabham G. Indian Institute of Technology Madras, Chennai-600036.

Laser surface alloying (LSA) is a new and promising hardfacing technique for generating surface alloyshaving a wide range of favourable properties such as hardness, wear and corrosion resistance. The alloyingcan be done in a single-stage or two-stage process. In single-stage process, alloying material is transporteddirectly to the zone of interaction between the laser beam and the substrate. The two-stage process includespre-depositing a layer of desired alloying material on the substrate, followed by laser heat treatment.

The present work describes an investigation of the effect of 3 different parameters of laser surfacealloying—i.e., laser power, laser scanning speed and powder feed rate on deposited height, depth and width.L8 orthogonal array has been designed to study these 3 parameters at 2 levels each. Commercial Co-basedWallex-50 and Colmonoy 88 alloy powders have been deposited on AISI 415 martensitic steel by single-stepprocess of laser surface alloying using 6 kW CW Diode Laser system.

The results of single clad pass with extent of dilution, surface hardness and microstructures producedby different conditions are presented and discussed. Finally, an attempt has also been made to list out theparameters at which enhanced hardness, minimum dilution and desired clad height and clad depth can beobtained.

SE-O2

HIGH TEMPERATURE EROSION RESISTANCE OF STAINLESS STEELSBhanu Kiran V.T., Vishal S., Vinayak Tiware S., Ashok T.V., Sriharsha R.V., Kumar R.K.

R. V. College of Engineering, Bangalore / VTU, Belgaum

In this study, the erosion resistance of different grades of stainless steels (SS) such as SS304, SS309L,15/5 precipitation hardened stainless steel and tungsten carbide (WC) hardfaced stainless steel has beencharacterized, under accelerated laboratory conditions. A systematic study on the erosion resistancecharacteristics of different grades of stainless steels, using jet erosion type laboratory test rig has been carriedout. The process variables include particle velocity, erodent type, impact angle, exposure time andtemperature. The erosion measurements were carried out at room temperature and at elevated temperatures300 C, 380 C to ascertain the sensitivity of different grades of SS. The erosion resistance tests were

conducted at different erodent particle impact angles viz. 15, 30, 45, 60, 90 and at different erodent particlevelocities. The data generated is useful for selection of specific grade of stainless steel material, forapplications where high temperature erosion is involved.

96 ISRS-2008

SE-O3

HIGH TEMPERATURE ADHESION EVALUATION OF WC-Co COATING ON AlSi 440C BY DETONATION SPRAY COATINGS

Edward Kennedy Z., Natarajan S., Aniruddha ChatterjeeNational Institute of Technology, Trichy

WC-based coatings are widely used in the Aircraft industry mainly for their resistance to wear,reworking and rebuilding operations and repair of worn components on landing gear, hydraulic cylinders,actuators, propeller hub assemblies, gas turbine engines, and so on. Also in automotive parts, to improve thewear resistance of the cylinder liner of the engines operating in desert area, the tungsten carbide coatings areused.

In the present work, WC-Co coatings were built up on an AISI 440C stainless steel substrate usingdetonation spray. High temperature friction and sliding wear resistance were studied using pin-on-disctribo-tester. The various parameters involved like, sliding velocity, sliding distance, Load and temperaturewere analyzed. The evaluation of wear was made using mass loss techniques. It was found that the compositecoating showed a better performance even at high temperature when compared with room temperature. Also,the coefficient of friction increases steadily with time which was confirmed by Lab-view images. The coatingswere characterized using scanning electron microscopy (SEM and X-ray diffraction (XRD). The XRD imagesrevealed no reflection from substrate element even after several thousand meters ensuring a good adhesionof coating thickness.

SE-O4

BN-FILLED PRECERAMIC POLYMERS AS BARRIERCOATINGS ON STEEL

Flores O.J.U., Günthner M., Krenkel W., Motz G. Universität Bayreuth

Preceramic polymers are an excellent alternative to the manufacture of protective ceramic coatings onsteel against oxidation and corrosion attack. In this context, two different particle-filled polysilazane systemswere developed, using BN powder as a passive filler. The ceramic coatings were manufactured on steelsubstrates by dip-coating, followed by pyrolysis in air up to 800 C. After the thermal treatment they werecharacterized regarding layer thickness, adhesion, oxidation and corrosion resistance. The passive fillerreduces the shrinkage of the layer, which results from ceramization of the precursor content. The SEMmicrographs showed that the combination passive filler/polysilazane leads to a dense and well adheredcoating which is resistant against oxidative environments at high temperatures and free of cracks for thicknesslayers up to 15%m. The coated substrates also presented a high resistance against corrosion, once they wereleft in a 1N HCl solution for more than 24 hours without suffering delamination.

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SE-O5

STRUCTURAL ASPECTS OF SPUTTER-DEPOSITED 304 STEEL-10 WT% Al COATINGS

Seelam U.M.R. and Suryanarayana C.1Ohkubo T. and Hono K. 2Cheruvu N.S. and Wei R. Department of Mechanical, Materials and Aerospace Engg., University of Central Florida, Orlando, FL-32816, USA.

1Nanostructure Analysis Group, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki-305-0047, Japan.

2Southwest Research Institute, San Antonio, TX-78228, USA.

It is well known that Al addition to steel improves high temperature oxidation and corrosion resistance.Microstructural understanding of such steels is important before applying them for high temperatureapplications. This investigation deals with the microstructural characterization of magnetron-sputteredaustenitic stainless steel (304SS) coating containing 10 wt% Al. The 304SS+10 wt% Al coating was depositedon 304SS substrate using plasma enhanced magnetron sputtering (PEMS) technique. The sputter-deposited32 m thick coating was characterized by XRD, TEM (SAD, STEM, EDS and HREM), 3-Dimensional AtomProbe (3DAP) and SEM techniques. While both XRD and TEM helped in phase identification, TEM and3DAP studies further helped in revealing the microstructural features of the phases. The coating had columnargrains with size ranging from 0.8-3 m. The coating contained the á-Fe solid solution as matrix and 2-10 nm

ordered FeAl B2 precipitates. The coating also had layered structure with a periodicity of 2-3 nm. The

alternate layers were either enriched or depleted in Al and Ni. In the layer enriched with Al and Ni, Fe andCr were depleted and vice versa in the next layer. Detailed results of this investigation will be presented.

SE-P1

STUDY ON THE INFLUENCE OF SURFACTANTS ON COATINGEFFICIENCY, CRYSTALLINITY, WEAR AND CORROSION

BEHAVIOUR OF ELECTROLESS COATINGElansezhian R., Kesavan Nair P. and Ramamoorthy B.

Indian Institute of Technology Madras

Electroless nickel - phosphorus (EN) coating is a well established surface engineering process that involvesdeposition of a metal-metalloid alloy coating on a variety of materials. EN coating has received widespread acceptanceand finds many applications in micro- and nanotechnologies. A major drawback of EN coating is its high cost ofproduction due to factors such as high cost of chemicals used, wastage in the form of metal bearing sludge, poornickel recovery from the bath etc. Due to these reasons, the EN coating efficiency is reported to be poor. Efforts basedon additives which influence the chemical process directly have been made by several researchers. One possiblealternate approach for improving efficiency of EN coating process might be the addition of some suitable surfactantsto the electrolyte bath. The effects of surfactants sodium dodecyl sulfate (SDS) and cetyltrimethyl ammoniumbromide (CTAB), on the coating efficiency, crystallinity, wear and corrosion behaviour EN deposits are investigatedin this study. The variation on surface morphology was examined using high resolution scanning electron microscope(HRSEM). The EN coated samples were characterized using X-ray diffraction analysis (XRD). Wear studies wereperformed on a pin-on-disc wear testing instrument. Accelerated corrosion studies were carried out on a neutral saltspray chamber. It was observed that coating efficiency, crystalline behaviour, specific wear rate, corrosion rate, andsurface morphology of electroless Ni-P coating were clearly influenced by the addition of surfactants SDS andCTAB. The complete experimental details, results obtained and their analysis are presented in this paper.

98 ISRS-2008

SE-P2

INVESTIGATION ON SPRAY PROCESSING OF Al-SiALLOYS AND THEIR WEAR CHARACTERISTICS

Raju K., Harsha A.P., Ojha S.N.Institute of Technology/Banaras Hindu University

Spray forming is an attractive novel technique for the production of near net shaped components of avariety of alloys. In the present investigation Al-12%Si, Al-15%Si and Al-20%Si alloys have been sprayformed at a temperature of 850 C and a pressure of 1MPa. The microstructural and wear characteristics ofthese alloys have been evaluated and compared with that of chill cast alloys. The microstructure of sprayformed alloys exhibited ultra fine Si particles with globular shape in the matrix having equiaxed grainmorphology in contrast to the needle like and plate like Si particles in the matrix in chill cast alloys. The wearrate of spray formed alloys was invariably observed to be lower than that of chill cast alloys over a wide rangeof load conditions. The reason for microstructural modification and resultant improvement in wearcharacteristics are discussed.

SE-P3

EFFECT OF HARDFACING TECHNIQUES ON WEAR PROPERTIES OFSTELITE-6 AND SS410 COATING ON MILD STEEL SUBSTRATE

Suresh K.V., Kulkarni R.S., Krishna M., Narasimha Murthy H.N. R V College of Engineering.

The research work is focused on the effect of hard facing techniques such as plasma transferred arcmethod, spray fuse method and gas tungsten arc welding method on wear properties of Stelite-6 coated mildsteel and SS410 coated mild steel. The hard faced specimens (2 mm coating thickness) are subjected tohardness and dry sliding wear tests using Rockwell hardness tester and pin-on-disc wear testing machinerespectively. The dry sliding wear tests are conducted for three sliding distances such as 0.5, 1.0 and 1.5 kmat speed of 500 and load of 10N. The microstructure and chemical composition of the coatings were analyzedby optical microscopy and XRD respectively. The results demonstrate that the both coating materials increasehardness and wear resistance of the specimens in all sliding distances. Coatings with stelite-6 with plasmatransferred arc method shows better wear resistance result compared with other two methods.

SE-P4

TRIBO-PERFORMANCE EVALUATION OF FUNCTIONALLYGRADED CERAMIC COATING BY D-GUN

Raja Kumar S., Vijayaraghavan L., Mayuram M.M.Indian Institute of Technology Madras, Chennai.

Surface engineering encompass with texture and chemistry alterations on the surface, as today’sengineering components demand more than one superior value of desirable properties. To meet suchconflicting demands Functionally Graded Coating (FGC) [1] are used. Layer structured FGC’s of Aluminaand Alumina-Titania (AT-13) of different layer thickness are developed by Detonation-gun (D-gun) coatingand subjected to sliding indentation/scratch test [2] to study their response to tribo-logical demands. Duringthe sliding indentation test, the energy liberation and vibration signal are monitored on-line using Acoustic

ISRS-2008 99

Emission (AE). The friction force was measured using a strain gauge transducer holding the indenter and theexperiment was conducted for different loads and passes. During sliding, the indenter plows on the ceramiccomposites and also experience adhesive friction to form a distressed zone around the indenter. Based on theapplied normal load, either relatively smoother groove can occur or a groove associated with formation ofsurface fissure and subsequent cracking of the adherent material can result. The typical variation of theaverage tangential force with respect to applied normal loads varies non-proportionally for different FGC’s.Normally co-efficient of friction should be independent of normal load under traditional tribo-logicalenvironment. However, with ceramic coatings, due to possible defects in the lay-up such as porosity,un-melted particles and also varying interlayer/cohesive strength, hardness gradient, the co-efficient offriction exhibits a non-linear relationship. The fluctuation of co-efficient of friction beyond a certain normalload can be attributed to the damage of the material with high loading, i.e., this load may be critical slidingload, associated with change from plowing friction to scratch friction. The paper presents relevant illustrationin the same.

SE-P5

EFFECT OF TEMPERATURE ON RUN-IN PERIODOF Ni BASED HARDFACING ALLOY DEPOSITED

BY PLASMA TRANSFERRED ARC WELDINGKesavan D. and Kamaraj M.

Indian Institute of Technology Madras,Chennai

The investigation attempts to understand the effect of temperature on run-in period in friction plot ofNi based (Colmonoy 5) hardfacing alloy deposited by plasma transferred arc welding (PTAW).Characterization of the deposits was carried out using with optical microscopy, SEM-EDAX, TEM, XRDand Vicker’s microhardness tester. Dry sliding wear tests of deposits were carried out at room temperature(RT), 3000C and 550 C in air atmosphere for a fixed sliding velocity of 0.25m/s and at a constant load of

60N using high temperature pin-on-disc machine.Microstructure of the deposit consists of dendrites of –nickel solid solution phase and eutectic interdendritic consistutents. TEM micrograph reveals the fine globularand needle like precipitates less than 100nm in sizes. The X ray diffraction pattern of deposits showed thatthe various phases and precipitates of – Ni, Chromium carbide Cr7C3 , Chromium boride Cr5B3 , Nickel

carbide Ni3C , Nickel boride Ni3B , and Nickel silicide Ni3Si . The hardness of the deposits is around 420

VHN whereas substrate is about 170 VHN.The co-efficient of friction (COF) at RT was found to be between0.3 - 0.4, whereas at 300 C and 550 C it was hovering between 0.25 – 0.35 and 0.2 – 0.3, respectively. It hasbeen observed that steady state in COF values after run-in period for all the tests. High COF was observedupto a run-in period of 200m at room temperature tests, whereas at 300 C it was observed up to 150m and

at 550 C, run-in period was almost negligible. Change in a COF value and run-in period are associated withestablishment of compacted layer of oxides and partially oxidized debris on the sliding surfaces. Mechanismsinvolved at RT tests are pure abrasion, delamination and ploughing whereas at high temperatures mildabrasion, adhesion and oxidation were responsible.

100 ISRS-2008

SE-P6

STUDIES ON FRICTION SURFACING OF AUSTENITICSTAINLESS STEEL ON MILD STEEL

Khalid Rafi H., Janakiram G.D., Phanikumar G., Prasad Rao K.Dept. of Metallurgical and Materials Engg. IIT Madras, Chennai-36

Single-bead coatings of AISI 310 stainless steel were deposited on mild steel substrates using frictionsurfacing. Friction surfacing process parameters were optimized based on statistically deigned experiments.The coatings were found to be metallurgically bonded to the substrate with good interfacial characteristics.A well defined heat affected zone existed underneath the coatings, whose microstructure and hardness werefound to vary significantly with process parameters. Fully martensitic and hard HAZs typically resulted underconditions of high heat input. It has been shown that, with careful choice of parameters, good coatings withsmaller/softer HAZs can be produced. The coatings showed fine equiaxed grains, indicative of dynamicrecrystallization. Preliminary microstructural studies showed no undesirable phases in coatings. EDAXlinescan studies confirmed that there was practically no dilution, demonstrating the superiority of frictionsurfacing over conventional fusion welding based surfacing processes.

SE-P7

SYNTHESIS AND CHARACTERIZATION OF TERNARYELECTROLESS Ni-W-P COATINGS USING A BATH CONTAINING

MIXED COMPLEXING AGENTSLogavenkatesh S., Seshadri S.K., Prathap Haridoss

Dept. of Metallurgical and Materials Engg. IIT Madras, Chennai-36

Electroless plating is a technique in which the redox reactions among chemicals are used to depositmetal on an object without passing external electrical energy. Generally complexing agents are used in thebath to control the free nickel ion concentration and to maintain pH level during electroless process. In thisinvestigation a bath to produce ternary electroless Ni-W-P using two complexing agents namely sodiumtricitrate and glycine was formulated, and plating rates estimated by using weight gain method. The bathcontaining 10 g/l and 15 g/l of sodium tricitrate and glycine respectively shows the maximum plating rate.Coatings with different composition were produced by altering the amount of sodium tungstate in the bath.The chemical composition was determined by EDAX analysis. The structural analysis was conducted usingX-ray diffraction and TEM for as plated and heat-treated coatings, which shows the coatings to be nanocrystalline even after heat treatment. Surface morphology of the coatings was studied using SEM and showsnodular structure. Mild steel was chosen as substrate for coatings and hardness was determined using Vickersmicro hardness testing, for both as plated and heat treated samples.

Key words: electroless nickel; mixed complexing agent; ternary alloys.

ISRS-2008 101

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SP-O1

SURFACE TREATMENT OF POLYESTER WITH GLOWDISCHARGE PLASMA IN AIR AT LOW PRESSURE

Inbakumar S. and Anu kaliani* A. PG and Research department of Physics,Kongunadu arts & Science College, Coimbatore-641029, Tamilnadu, India.

In order to increase the hydrophilicities and to improve dyeability, polyester fabrics were treated inlow pressure - glow discharge plasma. Different plasma parameters like pressure, exposure time and voltagewere variables in the process. Morphological changes as a result of plasma treatment were observed usingscanning electron microscopy (SEM). When treated, these fibres showed a new lamellar crystallization, asshown by a new melting peak using differential scanning calorimetry (DSC). X-ray photoelectronspectroscopy (XPS) has been used to study the chemical effect of low pressure glow discharge plasmatreatments of a PET surface. The capillary method was applied to evaluate the improvement in water uptakeof polyester fabrics.

SP-O2

GROWTH AND SINGLE CRYSTAL STRUCTURESOLUTION OF Fe1.97Bi0.03O3

Sathiyakumar S., Anbarasu V., Manigandan A.Anna University, Chennai.

The title compound crystallizes in Rhombohedral system with unit cell values a = 5.0244(3) Å, c =13.7233(8) Å and space group R3c. The percentage occupancy of Bi in Fe site was obtained by site occupancyparameters as a variable in the least square refinement of the structure. There is a merohedral twinning of thesystem about the c axis. The structure is essentially coincident with that of Fe2O3.

SP-O3

SYNTHESIS OF ZnO MICROSTRUCTURES FROM METALLIC ZnShubra Singh and Ramachandra Rao M.S.

Indian Institute of Technology Madras, Chennai

ZnO is one of the most important functional oxides with direct wide band gap (3.37 eV) and largeexciton binding energy (60 meV), exhibiting many interesting properties including near-UV emission,transparent conductivity, and piezoelectricity. In recent years, a variety of ZnO nano-/ micromaterials havebeen synthesized, such as nanowires, nanobelts, nanospring, nanoneedles, walls, tubes, nanobidges,nanonails, sea urchin-like ZnO structures, etc.[1-4]. These complex ZnO structures have a particularsignificance in the realization of advanced electronic and optoelectronic devices. In the present work differentmorphologies of ZnO have been realized by vapour synthesis technique, using metallic Zn flakes. The growthtakes place at 800 C without employing any metal catalysts that are conventionally used in vapour depositiontechnique. The as prepared sample consisted of fork and broom like structures. It exhibits visible greenemission (around 510 nm) on UV excitation. EDX data point towards oxygen deficiency in the sample.Photoluminescence spectra confirm the presence of defects and a poor crystal quality of the as prepared

102 ISRS-2008

sample. The sharp tips and high surface area of these unique structures make them a potential candidate forfield emission, ultra-sensitive gas sensing, catalysts and filtering. A simple growth mechanism has beenproposed to explain the formation of such structures.

SP-O4

A STUDY ON THE HEAT CAPACITY BEHAVIOUR OF INDIGENOUSLYDEVELOPED REDUCED ACTIVATION FERRITIC MARTENSITIC

(RAFM) STEEL BY DSCJeyaganesh* B., Arun Kumar Rai, Mythili R., Raju S., Saroja S., Mohandas E.,

Vijayalakshmi M. and Bhanu Sankara Rao K. Indira Gandhi Centre for Atomic Research, Kalpakkam.

Reduced activation ferritic – martensitic steels (RAFM) are rather recent additions to thewell-established family of high chromium, low carbon, low swelling ferritic alloys. Currently these steelsare under active consideration as candidate material for the plasma facing first wall and tritium breeder blanketcomponents in emerging fusion reactor design (ITER and DEMO). In applications related to nuclear fusion,the structural candidate must posses a higher degree of swell resistance against neutrons of higher energythan encountered in a fast reactor, besides good high temperature creep strength at temperatures upwards of600 C. Above all, they must pose a highly reduced radioactive hazard at the waste disposal end as otherwisethe high induced radioactivity would demand deep underground burial for prolonged periods of time. It isby the way of mitigating this important problem, truly reduced activation ferritic martensitic steels have comeinto existence. These steels are basically designed after modified 9Cr variety with the important caveat thatthe concentration of Nb, Mo, Cu, Ti, Al, Sb, P, S etc are reduced to below ppb levels. Thus Mo is replacedby W + V and Nb is replaced by Ta and by controlling the impurity content by making use of very purestar t ing material , i t is possible to design a RAFM. One such composit ion, namely9Cr-1W-0.226V-0.003Mo-0.063Ta-0.0039Nb-0.026N-0.005Cu-0.05Si-0.0036Al (all in wt.%) has beenmelted in MIDHANI and this has been taken up for detailed physical, metallurgical and mechanicalcharacterization in IGCAR. As a part of this study, we have measured the temperature variation of heatcapacity Cp using a high temperature heat flux differential scanning calorimetry. The measurements havebeen made on various samples with different base microstructure, like the as received, quenched / normalized(980, 1180, 1280 C / 0.5 to 2h) and tempered (780 C – 2 and 5 hour) conditions. The heat flux signal fromthe calorimeter has been calibrated using pure iron (Fe-80ppm C, Aldrich Chemicals) in the temperaturerange 200 1200 C. Highly reproducible and consistent results have been obtained for heat capacity of RAFM.These data were compared critically with our own earlier measurements on other 9Cr-Mo based steelsincluding Eurofer –97 and also with literature information. As a result, a critically assessed lower and upperbound Cp estimates are arrived for generic 9Cr-steel, including RAFM. As a by product of this study, accuratevalues for the various phase transformation arrest points have also been determined for RAFM.

ISRS-2008 103

SP-O5

ROLE OF 12-PHOSPHOTUNGSTIC ACID SUPPORTEDMESOPOROUS MATERIALS INVOLVING ORGANIC

TRANSFORMATION REACTIONS – A LEACHING STUDYKarthikeyan G., Pandurangan* A.

ICPT, A.C. Tech, Anna University, Chennai-25, India

The drive towards healthy solid acid catalysts associated with recyclability lead to the preparation ofHPWA/MCM-41 mesoporous molecular sieves of appropriate ratios by loading phosphotungstic acid onsiliceous MCM-41 by wet impregnation method. The prepared HPWA/MCM-41 materials werecharacterized by X-ray Diffraction analysis (XRD), BET surface area method, FT-IR measurements and 31PNMR. The morphology of mesoporous materials was studied by TEM technique. The catalytic activity ofthe above materials was tested over single step organic transformation reactions and the diminishing load ofHPWA for every cycle was measured by ICP-AES technique in terms of tungsten percentage. The effect oflarge pore pass-through for bulk molecules with high range acidity and the dissolution of syntheticallyprepared HPWA/MCM-41 in various solvents with regard to tungsten content and complete achievement ofthe loading were observed. The effects of process parameters such as concentration of loading, temperature,nature of solvents, time on the dissolution rate of HPWA from the support and negligible leaching pointdeciding the reusability were investigated.

Key words: Tungsten, Heteropoly acid, Leaching, Organic transformation reactions

SP-P1

AUTOMATION OF HOME MADE SPRAY PYROLYSIS UNITAND DEPOSITION OF CuFe2O4 THIN FILMS

Paul Joseph D. and Venkateswaran C.University of Madras, Chennai.

The home made spray pyrolysis unit has been automated for horizontal rastering of the spray gun andfor controlled spray with constant interval in order to achieve homogenous coating over a large area. Thevarious components used in the automation of the unit are discussed with the help of a block diagram. Inorder to check the performance of the automated unit, CuFe2O4 thin films were deposited onto a quartz

substrate at 500 C with constant rastering of the spray gun. The structural, microstructural, optical and

magnetic properties of the post annealed (800 C/1h in air) CuFe2O4 thin film are presented and discussed.

104 ISRS-2008

SP-P2

GROWTH AND CHARACTERIZATION OF PURE AND 1,10 PHENANTHRLAINE DOPED POTASSIUM

PENTA BORATE (KB5) SINGLE CRYSTALSPrabhaa K., Rajeshkumara T., Dennish Christya P., Ramesh babub M., Nirmala Jothia N.S.,

Chenc H. and Sagayaraja* P.Loyola College, Madras Univeristy, Chennai, India

Borate crystals are often employed for high-power UV generation because of their relatively hightolerance to laser-induced damage, large optical nonlinear coefficients, and greater transparency in the UVregion. KB5 appears to be superior to ammonium penta borate NH4B5O8.4H2O in most essential properties

relevant for use in nonlinear optical devices. For example at 222.2 nm KB5 generated more than ten times as

much radiation as the NH4B5O8.4H2O sample. We concentrate the low temperature slow solvent evaporation

method and characterization of 1,10 phenanthraline doped KB5 and describe its potential as a non-linear

optical material. The grown crystal has been subjected to single crystal X-ray diffraction analysis to identifythe unit cell parameters and crystal systems. The presence of carbon, hydrogen and oxygen content wereconfirmed by CHN analysis. The Kurtz’s-Perry powder SHG efficiency was found to be for Pure and 1,10phenanthraline doped KB5 crystals 1.6 and 2.2 times than that of pure KDP. Functional groups of the

compounds were confirmed by FT-IR studies. Surface morphology of the pure and doped KB5 crystals has

been found to be Scanning Electron Microscopic technique (SEM).

SP-P3

HIGH SPEED MACHINING (TURNING) OF SUPERALLOY INCONEL 718Thakur D.G., Ramamoorthy B., Vijayaraghavan L.

Mechanical Engineering Department, Indian Institute of Technology Madras, Chennai-600 036 TN (India)

Nickel and Nickel based alloys especially, superalloy Inconel 718 has found its niche in manyindustries, owing to its unique properties such as high oxidation resistance, corrosion resistance even at veryhigh temperatures and it retains a high mechanical strength under these conditions as well. Thus, it is oftenused in extreme conditions, such as aircraft engine parts, chemical processing, pressure vessels, steam turbinepower plants, space vehicles, marine applications, automotive sector etc. As a result of these properties andpotential applications, a great necessity exists to understand the problems/questions associated with themachining of such a superior material. However, Inconel 718 is considered to have poor machinability dueto its peculiar characteristics like low thermal conductivity, work hardening, presence of abrasive carbideparticles, hardness, affinity to react with tool material etc. which makes it difficult to machine. Hence, Inconel718 is classified as the “difficult-to-cut materials”. Success in machining Inconel 718 depends largely onovercoming several of the inherent properties of the metal such as workhardening, its tendency to weld tothe tool, intense heat generation due to low thermal conductivity, shorter tool life due to stresses andtemperature etc. Considering all the above facts, an attempt has been made in this work to understand themachinability of superalloy Inconel 718 with respect to cutting forces, acoustic emission, and microstructuralalteration while high speed turning. The experimental investigations were carried out and the results arepresented and analyzed in this paper.

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SP-P4

INFLUENCE OF MILLING TIME AND ATMOSPHEREON THE PRODUCTION OF LEADED BRASS IN THE PRESENCE

OF GRAPHITE USING MECHANOCHEMICAL METFarahbakhsh, Tabaian S.H., Vahdati J.

Iran University of Science and Technology.

Mechanochemical process was applied for brass alloy production using oxide powders. Alpha brasswas produced when CuO, ZnO and PbO were milled under argon atmosphere in the presence of graphite (asreducing agent). Concurrent reduction of zinc, copper and lead oxides took place in the argon atmosphere,whereas the reduction reactions did not proceed well in the closed chamber filled with air. These reactionswere promoted by milling time up to 100 hours. The amount of reduction tends to decrease for longer times.

SP-P5

EFFECT OF SURFACE ROUGHNESS ON SURFACE HEAT FLUX DURING IMMERSION QUENCHING

OF STAINLESS STEEL PROBES IN WATERBabu K. and Prasanna Kumar T.S.

Indian Institute of Technology Madras, Chennai.

During quenching, if the properties like thermal stresses, thermal strains, residual stresses andmicrostructure of the steel are to be simulated using numerical methods, it is obligatory to give an accurateboundary condition. The surface heat-transfer coefficients or heat fluxes between specimen and the quenchantare regarded as key parameters for numerical simulation of the quenching process. Heat transfer duringquenching is very complex and is affected by parameters like surface temperature, surface condition of thespecimen, fluid properties such as viscosity, density, specific heat and all thermal physical properties of thesolid and quenchant agitation. In this paper, the effect of surface texture on the heat flux during quenchingof stainless steel probes in water has been studied. Stainless steel probes of diameter 20 mm and 50 mm longwere prepared from 304L which has no transformations during quenching. Three quench probes weremachined to different surface finish with its roughness (Ra) being . The estimation of heat flux at the and

2.196 , 1.289 0.210 quenched surface was based on Inverse Heat Conduction Problem (IHCP).Thermocouples were inserted at the holes drilled at 2 mm below the cylindrical surface of the quench probes.Using a computer assisted data acquisition system, the time-temperature data were recorded during quenchingof these probes in water. The IHCP algorithm gives the surface temperature of the probe along with the heatflux using the measured temperature data as input. The results of the computation showed that the peak heatflux increased with increase in surface roughness of the specimen. The slope of different regimes liketransition boiling, nucleate boiling and convective boiling in the cooling curve remained same. However,there is a appreciable change in the magnitude of peak heat flux values but its corresponding surfacetemperature did not vary much.

106 ISRS-2008

SP-P6

ANALYSIS AND IDENTIFICATION OF NATURAL COPPER OREPuthilibai a,* G. Vasudhevan b S. and Athapan c P.R.

aDepartment of Chemistry, SriSairam Engineering College, West Tambaram, Chennai - 600 044, India.bDepartment of Chemistry, K.V.,Central Leather Research Institute, Adyar, Chennai - 600 020, India.

cDepartment of Inorganic Chemistry, School of Chemistry, Madurai Kamaraj University, Madurai - 625 021, India.

The natural Copper ore obtained for the present project was collected from Antipatti Hill area, nearVaigai Dam, Madurai District, situated in the state of Tamil Nadu, India. The appearance of the ore was amixture of deposits of blue, violet, ash and green colours. In total, the ore look like greenishblue in colour.The present work is aimed at collecting and estimating the individual metals and anlysing the nature of theore and its constituents by various physicochemical methods (UV-Vis spectra, FTIR spectra, Cyclicvoltametric and Crystallographic studies). Based on the results of physicochemical studies the ore isconfirmed as a carbonate and oxide based Malachite [Cu(OH)2.CuCO3] with varying degree of Cuprite. Thisstudy may open up a new chapter in industrial development in TamilNadu by bringing up a new industry forprocessing the newly identified Copper ore.

SP-P7

MESOPOROUS Al- KIT-6 CATALYSTS FOR THE PREPARATION OFFINE CHEMICALS: SYNTHESIS OF JASMINALDEHYDE

Prabhu A., Kumaresan L., Palanichamy M. and Murugesan* V. Anna Univrsity, Chennai

The discovery of silica-based and metal-substituted mesoporous materials M41S has attracted intenseinterest due to their high surface area, uniform pore size distribution, large pore size, and highly valuablepotential applications in catalysis, separation, adsorption, nano devices, and nanostructured materials. Manymesoporous siliceous materials, such as MCM-48, MCM-41, SBA-15 and KIT-6, have been prepared by theself-assembly method using long-chain surfactants as templates over the past decade.The mesoporous silicaKIT-6 was reported by Kleitz et .al[1]. The incorporation of Al into KIT-6 mesostructure was carried out bydirect synthesis method using Aluminium isopropoxide as Al source. Mesoporous aluminosilicate Al-KIT-6was synthesized from assembly of polymer surfactant micelle as a template in strong acidic media. In thetypical synthesis of Al-KIT-6, Triblock copolymer (Pluronic P123) was used as the structure-directingtemplate. Mesoporous Al-KIT-6 molecular sieves with Si/Al ratios 20, 50,100 and 150 were synthesizedhydrothermally and characterized by XRD, FT-IR, BET, SEM and HR-TEM. Mesoporous Al-KIT-6 wasgood phase purity from XRD analysis. The surface area of the catalysts was found to be varying from 699

to 887m2/g. The HR-TEM picture of Al-KIT-6(50) showed formation of particles of cubic morphology.-n-Amylcinnamaldehyde (Jasminaldehyde) has been prepared with high selectivity and using low ratios of

benzaldehyde/heptanal by means of mesoporous Al-KIT-6 molecular sieves. The synthesis ofjasminaldehyde, a compound used in the flavor industry, is not only a reaction of commercial interest, but isalso an interesting test reaction to assess the selectivity of the catalyst.The products were confirmed by GCand GC-MS analysis.

ISRS-2008 107

ISRS-2008 109

Participating Institutes in ISRS 2008

Indian Universities

Indian Institute of Technology Madras Indian Institute of Technology Kanpur Indian Institute of Technology Kharagpur Indian Institute of Technology Bombay Indian Institute of Technology Delhi Indian Institute of Science Bangalore NIT Trichy NIT Surathkal NIT Calicut NIT Rourkela VNIT Nagpur Anna University NIIST Trivandrum CSIR AMPRI(Formerly RRL) CSIR Bhopal IGCARNAL Bangalore DMRL Hyderabad Central Glass & Ceramic Reasearch Institute , Kolkata University of Madras University of Calcutta Osmania University Mysore University ITBHUJNTU Hyderabad University of Kerala MGIT Hyderabad Cochin university Gauhathi University Loyola college, Chennai Jiwaji University G. B. Pant University Bharathidhasan University Bharathiyar University Kakatiya University Panjab University Presidency College Chennai PSG Tech Coimbathore Kongu Engineering College R V College

110 ISRS-2008

Pt. Ravishankar Shukla University Sathyabama University SRM University St Joseph College Thiagarajar College of Engineering Auden Technology and Management Academy, Bangalore University BDT College of Engineering Sagar Institute of Research and Technology, Bhopal

International Universities

Univ. of Central Florida, USA Univ. Teknologi MARA Malaysia University of California Santa Barbara, USA Universiti Tenaga Nasional, Malaysia Universität Bayreuth, Germany Nagaoka University of Technology, Nagaoka, Japan Iran University of Science and Technology, Iran Dalian University of Technology, China Delft University of Technology, Netherlands Technical University Darmstadt, Germany Shahid Bahonar University of Kerman Ryerson University, Canada

ISRS-2008 111

List of Sponsors

All India Council for Technical Education (AICTE)

Board of Research in Nuclear Sciences (BRNS)

Department of Science and Technology (DST)

Defense Research and Development Organisation (DRDO)

Atomic Energy Regulatory Board (AERB)

Council of Scientific and Industrial Research (CSIR)

Department of Mathematics, IIT Madras

Department of Management Studies, IIT Madras

Department of Physics, IIT Madras

112 ISRS-2008

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