PROJECT REPORT ON CHARACTERISTICS AND PROPERTY EVALUATION OF METAL MATRIX COMPOSITES [MMCs] USING STIR CASTING Submitted in partial fulfillment of requirements for the award of degree of BACHELOR OF TECHNOLOGY In By ANKIT PATHAK 1112840020 ANKUSH VERMA 1112840030 AVINASH UPADHYAY 1112840043 ANKUR GOEL 1112840028 Under the guidance of MR. SAURABH GUPTA MECHANICAL ENGINEERING DEPARTMENT BHARAT INSTITUTE OF TECHNOLOGY, MEERUT. 1
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PROJECT REPORT
ON
CHARACTERISTICS AND PROPERTY EVALUATION OF METAL MATRIX
COMPOSITES [MMCs] USING STIR CASTING
Submitted in partial fulfillment of requirements for the award of degree of
BACHELOR OF TECHNOLOGY
In
By
ANKIT PATHAK 1112840020
ANKUSH VERMA 1112840030
AVINASH UPADHYAY 1112840043
ANKUR GOEL 1112840028
Under the guidance of
MR. SAURABH GUPTA
MECHANICAL ENGINEERING DEPARTMENT
BHARAT INSTITUTE OF TECHNOLOGY, MEERUT.
MEERUT-250103
1
CANDIDATE’S DECLARATION
I hereby declare that the work carried out in this project report entitled,
“CHARACTERISTICS AND PROPERTY EVALUATION OF METAL MATRIX
COMPOSITES [MMCs] USING STIR SQUEEZE CASTING”, is presented in partial
fulfillment of the requirements for the award of degree of “Bachelor of Technology” in
Mechanical Engineering with specialization in production & industrial system engineering,
submitted to the Department of Mechanical Engineering, Bharat Institute of Technology,
Meerut, under the guidance of Mr.Saurabh Gupta, Assistant Professor,Department of
Mechanical and Industrial Engineering.
Date: ANKIT PATHAK 1112840020
ANKUSH VERMA 1112840030
AVINASH UPADHYAY 1112840043
ANKUR GOEL 1112840028
Place: Meerut
This is to certify that the above statement made by the candidate is correct to the best of my
knowledge and belief.
(Mr. Saurabh gupta)
Assistant Professor
2
ACKNOWLEDGEMENT
The euphoria and joy, accompanying the successful completion of my task would be
incomplete without the special mention of those people whose guidance and encouragement
made my effort successful.
I am deeply indebted to my guides Mr. Saurabh Gupta, Asst. Professor in the department of
MECHANICAL ENGINEERING, Bharat Institute of Technology, Meerut, whose help,
stimulating suggestions and encouragement helped me in all the time to make my effort
successful.
Especially, I would like to give my special thanks to my parents and my friends, whose
support and motivation inspire me to complete the study.
ANKIT PATHAK 1112840020
ANKUSH VERMA 1112840030
AVINASH UPADHYAY 1112840043
ANKUR GOEL 1112840028
M.TECH-4ND YEAR
3
CONTENTSPAGE NUMBER
ABSTRACT 6
INTRODUCTION 8
COMPOSITES 10
Classification of composites 11
METAL MATRIX COMPOSITES 14
Constituents of MMCs 16
Types of MMCs 17
INTRODUCTION TO ALUMINIUM
MATRIX COMPOSITES 18
PRODUCTION METHODS OF ALUMINIUM
MATRIX COMPOSITES 21
EXPERIMENTAL SET UP AND PROCEDURE
Stir Squeeze Casting Set up 25
Stir Squeeze Casting Procedure 26
DEFINITION & FORMULAE 27
RESULTS AND DISCUSSIONS 28
CONCLUSION 29
FUTURE ASPECTS 30
REFERENCES 31
4
LIST OF FIGURES
Fig no. Name of figure Page no.1 Classification of composite 8
2(a)Typical microstructure of silicon carbide particle/ aluminum
alloy composite18
2(b)Typical microstructure of silicon carbide particle/ aluminum
alloy composite18
3 Some application of AMCs 20
4 Stir Casting 25
5 Diagram of Set up 27
LISTOF TABLES
Table
no.Name of table Page no.
1 Typical reinforcements used in metal matrix composites 16
2A comparative evaluation of the different techniques used for
MMC fabrication22
3 Chemical Composition of A6063 alloy 25
4 Result & discussion 27
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ABSTRACT
Manufacturing of aluminum alloy based casting composite by stir casting is one of the
most economical method of processing MMC. The aluminum based composites are
increasingly being used in the transport, aerospace, marine, automobile and mineral
processing industries, owing to their improved strength, stiffness and wear resistance
properties. The widely used reinforcing materials for these composites are silicon carbide,
aluminum oxide and graphite in the form of particles or whiskers. The ceramic particles
reinforced aluminum composites are termed as new generation material and these can be
tailored and engineered with specific required properties for specific application
requirements. Particle reinforced composites have a better plastic forming capability than that
of the whisker or fiber reinforced ones, and thus they have emerged as most sought after
material with cost advantage and they are also known for excellent heat and wear resistance
applications .Given the factors of reinforcement type, form, and quantity, which can be
varied, in addition to matrix characteristics, the composites have a huge potential for being
tailored for particular applications. One factor that, to date, has restricted the widespread use
of MMCs has been their relatively high cost. This is mostly related to the expensive
processing techniques used currently to produce high quality composites. The most widely
applied methods for the production of composite materials and composite parts are based on
casting techniques such as the stir casting of porous ceramic pre - forms with liquid metal
alloys and powder metallurgy methods. The cost and the properties of the produced MMC are
highly dependent on the method of their processing.
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INTRODUCTION
Aluminum alloys are preferred engineering material for automobile, aerospace and
mineral processing industries for various high performing components that are being used for
varieties of applications owing to their lower weight, excellent thermal conductivity
properties. The composites formed out of aluminum alloys are of wide interest owing to their
high strength,fracture toughness, wear resistance and stiffness. Further these composites are
of superior in nature for elevated temperature application when reinforced with ceramic
particle [1].
Alluminium and its alloys are being widely used as matrix for the synthesis of metal matrix
composites (MMCs) by researchers, owing to their abundant availability, easy processing,
low melting point and easy machining. In the world of polymer matrix composites, and
plastics, Al and its alloys maintain their critical importance due to characteristic properties of
metals i.e. ductility, strength and, thermal and electrical conductivity [1]. Higher strength to
weight ratio, ease in alloying and recycling are added advantages of Al and its alloys. [2]
The addition of high strength, high modulus refractory particles to a ductile metal matrix
produce a material whose mechanical properties are intermediate between the matrix alloy
and the ceramic reinforcement. Metals have a useful combination of properties such as high
strength, ductility and high temperature resistance, but sometimes have low stiffness, whereas
ceramics are stiff and strong, though brittle. Aluminium and silicon carbide, for example,
have very different mechanical properties: Young's moduli of 70 and 400 GPa, coefficients of
thermal expansion of 24 X 10-6 and 4 X 10-6/oC, and yield strengths of 35 and 600 MPa,
respectively. By combining these materials, e.g. A6061/SiC/17p (T6 condition), an MMC
with a Young's modulus of 96.6 GPa and yield strength of 510 MPa can be produced [3]. By
carefully controlling the relative amount and distribution of the ingredients of a composite as
well as the processing conditions, these properties can be further improved.
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COMPOSITE
Composite material are materials made from two or more constituent materials with
significantly different physical and chemical properties, that when combined, produce a
material with characteristics different from the individual component.[4] Many of common
materials (metals, alloys, doped ceramics and polymers mixed with additives) also have a
small amount of dispersed phases in their structures, however they are not considered as
composite materials since their properties are similar to those of their base constituents
(physical property of steel are similar to those of pure iron) . Favorable properties of
composites materials are high stiffness and high strength, low density, high temperature
stability, high electrical and thermal conductivity, adjustable coefficient of thermal
expansion, corrosion resistance, improved wear resistance etc. composite materials are
generally used for buildings, bridges and structures such as boat hulls, swimming pool panels,
race car bodies, shower stalls, bathtubs, storage tanks, imitation granite and cultured marble
sinks and counter tops. the most advanced examples perform routinely on spacecraft and
aircraft in demanding environments.
Composites as engineering materials normally refer to the material with
the following characteristics: 1. These are artificially made (thus, excluding natural material such as wood).
2. These consist of at least two different species with a well defined interface.
3. Their properties are influenced by the volume percentage of ingredients.
4. These have at least one property not possessed by the individual constituents.
Performance of Composite depends on:
1. Properties of matrix and reinforcement,
2. Size and distribution of constituents,
3. Shape of constituents,
4. Nature of interface between constituents.
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CLASSIFICATION OF COMPOSITES
Composite materials are classified
a. On the basis of matrix material,
b. On the basis of filler material.
Fig1: Classification of composites
9
(a) On the basis of Matrix:1. Metal Matrix Composites (MMC)
Metal Matrix Composites are composed of a metallic matrix (aluminium, magnesium,
iron, cobalt, copper) and a dispersed ceramic (oxides, carbides) or metallic (lead, tungsten,
molybdenum) phase.
2. Ceramic Matrix Composites (CMC)
Ceramic Matrix Composites are composed of a ceramic matrix and imbedded fibers
of other ceramic material (dispersed phase).
3. Polymer Matrix Composites (PMC)
Polymer Matrix Composites are composed of a matrix from thermoset (Unsaturated
polyester (UP), Epoxy) or thermoplastic (PVC, Nylon, Polysterene) and embedded glass,
carbon, steel or Kevlar fibers (dispersed phase).
(b) On the basis of Material Structure:1. Particulate Composites
Particulate Composites consist of a matrix reinforced by a dispersed phase in form of
particles.
1. Composites with random orientation of particles.
2. Composites with preferred orientation of particles. Dispersed phase of these materials
consists of two-dimensional flat platelets (flakes), laid parallel to each other.
2. Fibrous Composites
(a) Short-fiber reinforced composites. Short-fiber reinforced composites consist of a matrix
reinforced by a dispersed phase in form of discontinuous fibers (length < 100*diameter).
Composites with random orientation of fibers.
Composites with preferred orientation of fibers.
(b) Long-fiber reinforced composites. Long-fiber reinforced composites consist of a matrix
reinforced by a dispersed phase in form of continuous fibers.
Unidirectional orientation of fibers.
Bidirectional orientation of fibers (woven). 10
Laminate Composites
When a fiber reinforced composite consists of several layers with different fiber orientations,
it is called multilayer (angle-ply) composite.
3.Laminar Composites
Laminar composites are found in as many combinations as the number of materials. They can
be described as materials comprising of layers of materials bonded together. These may be of
several layers of two or more metal materials occurring alternately or in a determined order
more than once, and in as many numbers as required for a specific purpose.
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METAL MATRIX COMPOSITES
(MMCs)
Metal matrix composites, at present though generating a wide interest in research
fraternity, are not as widely in use as their plastic counterparts. High strength, fracture
toughness and stiffness are offered by metal matrices than those offered by their polymer
counterparts. They can withstand elevated temperature in corrosive environment than
polymer composites. Metal Matrix Composites are composed of a metallic matrix (Al, Mg,
Fe, Cu etc) and a dispersed ceramic (oxide, carbides) or metallic phase ( Pb, Mo, W etc).
Ceramic reinforcement may be silicon carbide, boron, alumina, silicon nitride, boron carbide,
boron nitride etc. whereas Metallic Reinforcement may be tungsten, beryllium etc [4]. MMCs
are used for Space Shuttle, commercial airliners, electronic substrates, bicycles, automobiles,
golf clubs and a variety of other applications. From a material point of view, when compared
to polymer matrix composites, the advantages of MMCs lie in their retention of strength and
stiffness at elevated temperature, good abrasion and creep resistance properties [4]. Most
MMCs are still in the development stage or the early stages of production and are not so
widely established as polymer matrix composites. The biggest disadvantages of MMCs are
their high costs of fabrication, which has placed limitations on their actual applications [2].
There are also advantages in some of the physical attributes of MMCs such as no significant
moisture absorption properties, non-inflammability, low electrical and thermal conductivities
and resistance to most radiations [5]. MMCs have existed for the past 30 years and a wide
range of MMCs have been studied. Compared to monolithic metals, MMCs have:
Higher strength-to-density ratios
Higher stiffness-to-density ratios
Better fatigue resistance
Better elevated temperature properties
Higher strength
Lower creep rate
Lower coefficients of thermal expansion
Better wear resistance
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The advantages of MMCs over polymer matrix composites are: Higher temperature capability
Fire resistance
Higher transverse stiffness and strength
No moisture absorption
Higher electrical and thermal conductivities
Better radiation resistance
No out gassing
Fabric ability of whisker and particulate-reinforced MMCs with conventional
metalworking equipment.
Some of the disadvantages of MMCs compared to monolithic metals and
polymer matrix composites are: Higher cost of some material systems
Relatively immature technology
Complex fabrication methods for fiber-reinforced systems (except for casting)
Limited service experience
Numerous combinations of matrices and reinforcements have been tried since work on
MMC began in the late 1950s. However, MMC technology is still in the early stages of
development, and other important systems undoubtedly will emerge. Numerous metals
have been used as matrices. The most important have been aluminum, titanium,
magnesium, and copper alloys and superalloys.
CONSTITUENTS OF MMC
The major constituents of a metal matrix composite material are matrix and reinforcements.
Interface between matrix and reinforcement is also considered as one of the constituents as it
plays a crucial role in determining the properties of the composite.
MATRIX: Metals are essential constituent for fabrication of MMC and choice of matrix
material depends upon strength, temperature of application, density, cost requirement, easy
availability and ease of processing .The major function of matrix is to transfer and distribute
13
the load over the reinforcement. The transfer of load depends on the bonding interface
between the matrix and the reinforcement, however bonding depends on the type of matrix
and the reinforcement along with fabrication technique. Currently the main focus on matrix
material for MMC is given to Aluminium alloys because of unique combination of high
corrosion resistance, low density and excellent mechanical properties [6].
REINFORCEMENT: Second phase materials added to the matrix alloys which normally
enhance strength, stiffness, wear and creep resistances of the composites. The choice of
reinforcement always depends on the final property requirements of the composite system or
the component to be fabricated [6]. SiC has been reported to be the most advantageous
reinforcement for matrix of Aluminium alloys . The key properties of Sic are as under:
High strength
Low thermal expansion
High thermal conductivity
High hardness
High elastic modulus
Excellent thermal shock resistance
Superior chemical inertness [7].
INTERFACE: It is the region that lies between its constituents i.e. matrix and reinforcement.
It plays a crucial role in determining the composite properties. It may contain a simple row of
atomic bonds (e.g. the interface between alumina and pure Al), or reaction products between
matrix and the reinforcement (e.g. Aluminium carbide between Al and C fibers), or
reinforcement coatings (e.g. reinforcement coatings between SiC and titanium matrices). In
comparison (i) stiffening and strengthening rely on load transfer across the interface, (ii)
toughness is influenced by crack detection/fiber pullout, and (iii) ductility is affected by
relaxation of peak stresses near the interface [6].
TYPES OF METAL MATRIX COMPOSITES
14
There are three kinds of metal matrix composites (MMCs):
Particle reinforced MMCs
Short fiber or whisker reinforced MMCs
Continuous fiber or sheet reinforced MMCs
Table provides examples of some important reinforcements used in metal matrix composites
and their aspect (length/diameter) ratios and diameters.