IJIRST –International Journal for Innovative Research in Science & Technology| Volume 3 | Issue 01 | June 2016 ISSN (online): 2349-6010 All rights reserved by www.ijirst.org 101 Tribological Investigations on Al-Al3Ti In-situ Metal Matrix Composite Veeresha G Assistant Professor Department of Mechanical Engineering New Horizon College of Engineering, Bangalore-560103, Karnataka, India Abstract In the present study, an attempt has been made to prepare and characterize Al-Al3Ti metal matrix composites with varying percentage of in-situ Al3Ti (3, 5 and 7%). The composites were prepared by the reaction commercial purity aluminum 99.7% and K2TiF6 salt at a reaction temperature of 800 °C. The prepared samples were characterized by optical microscopy. The wear tests were conducted on all the prepared samples by varying parameters like wt. % of Al3Ti particles, normal pressures, sliding speeds. Mechanical properties were assessed using computerized universal testing machine, Brinell hardness tester, Surface roughness tester and micro hardness tester. The worn surfaces were examined by optical microscopy after wear test.Al-3Ti, Al- 5Ti and Al-7Ti alloys were prepared and effect of Ti content on hardness, tensile strength, volumetric wear rate and surface roughness were examined. Experimental alloys were fabricated by salt route method. Volumetric wear rate of the reinforced Al- 3Ti, Al-5Ti and Al-7Ti alloys at room temperature were measured. The present results suggest that the wear resistance of Al- Al3Ti composites increases with increase in percentage of Al3Ti particles compared to pure aluminum. In addition, the improvement in mechanical properties of the composite was observed in Al-5Ti composite when compared to Al-3Ti and Al-7Ti and to the pure Al. Better tribological properties of these alloys can be achieved at Al-5Ti. Keywords: Al-Al3Ti, Intermetallic compounds, Hardness, Tensile strength, Volumetric wear rate, sliding speed, Surface roughness, frictional force _______________________________________________________________________________________________________ I. INTRODUCTION For structural application of moving components, the tribological properties (friction and wear) are considered to be one of the major factors controlling the performance. In recent years, lightweight metal matrix composites (MMC) have received wider attention for their technological application, such as automotive parts etc. This paper reports the tribological behavior of Al based composites reinforced with in situ TixAly and Al2O3 particles. The wear experiments were performed on a newly designed fretting tribometer to evaluate the role of intermetallic particulates on the wear performance of in situ composites against bearing steel under the ambient conditions of temperature (22–25 °C) and humidity (50–55% RH). Based on the topographical observation of the worn surfaces the plausible wear mechanisms are discussed. An important result is that Al-based composites with 20 vol% reinforcement exhibit an extremely low coefficient of friction of 0.2 under unlubricated conditions. Also, around five times lower wear volume is measured with 20 vol% composites when compared to unreinforced Al. During past two decades, requirements for specific property material for advanced aerospace and automobile application have escalated since conventional alloy systems are not suitable there. Attempts to enhance the performance characteristics of monolithic materials by reinforcement with high strength/ high stiffness second phase are therefore required. By selecting the appropriate reinforced constituents of a material that is volume fraction, shape and size. It is possible to design alloys with enhanced strength and stiffness. Polymers, ceramics or metals such as aluminum, magnesium, titanium, copper and nickel alloys serve as matrix materials with whiskers (SiC), monofilaments (SiC, B, W), fiber (SiC, Al 2O3, graphite) and particulate (SiC, Al2O3, Al3Ti) acting as reinforcement. These reinforcements normally strengthen the matrix as they are stronger than the matrix alloys. Due to the presence of hard particles these metal matrix composites (MMCs) are currently being considered as promising tribological materials with applications in the aerospace, aircrafts and in a particular automotive industries. The high strength to weight ratio and wear resistance of aluminum MMCs makes the substitution of steel engine parts such as pistons, liners, clutches, pulleys rockers and pivots by MMCs parts in automobiles. This results in improved engine efficiency a reduction in noise and friction. Aluminum based particulate reinforced metal matrix composites have emerged as an important class of high performance materials for use in aerospace, automobile, chemical and transportation industries because of their improved strength, high elastic modulus and increased wear resistance over conventional base alloys. Recently, in situ techniques have been developed to fabricate aluminum-based metal matrix composites [1-4], which can lead to better adhesion at the interface and hence better mechanical properties. Owing to low density, low melting point, high specific strength and thermal conductivity of aluminum, a wide variety of ceramic particulates such as SiC, B4C, Al2O3, TiC and graphite have been reinforced into it. Among these particulates, Al3Ti has emerged as an outstanding reinforcement. This is due to the fact that Al 3Ti is stiff, hard and more importantly, does not react with aluminum to form any reaction product at the interface between the reinforcement and
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IJIRST –International Journal for Innovative Research in Science & Technology| Volume 3 | Issue 01 | June 2016 ISSN (online): 2349-6010
All rights reserved by www.ijirst.org 101
Tribological Investigations on Al-Al3Ti In-situ
Metal Matrix Composite
Veeresha G
Assistant Professor
Department of Mechanical Engineering
New Horizon College of Engineering, Bangalore-560103, Karnataka, India
Abstract
In the present study, an attempt has been made to prepare and characterize Al-Al3Ti metal matrix composites with varying
percentage of in-situ Al3Ti (3, 5 and 7%). The composites were prepared by the reaction commercial purity aluminum 99.7%
and K2TiF6 salt at a reaction temperature of 800 °C. The prepared samples were characterized by optical microscopy. The wear
tests were conducted on all the prepared samples by varying parameters like wt. % of Al3Ti particles, normal pressures, sliding
speeds. Mechanical properties were assessed using computerized universal testing machine, Brinell hardness tester, Surface
roughness tester and micro hardness tester. The worn surfaces were examined by optical microscopy after wear test.Al-3Ti, Al-
5Ti and Al-7Ti alloys were prepared and effect of Ti content on hardness, tensile strength, volumetric wear rate and surface
roughness were examined. Experimental alloys were fabricated by salt route method. Volumetric wear rate of the reinforced Al-
3Ti, Al-5Ti and Al-7Ti alloys at room temperature were measured. The present results suggest that the wear resistance of Al-
Al3Ti composites increases with increase in percentage of Al3Ti particles compared to pure aluminum. In addition, the
improvement in mechanical properties of the composite was observed in Al-5Ti composite when compared to Al-3Ti and Al-7Ti
and to the pure Al. Better tribological properties of these alloys can be achieved at Al-5Ti.
Effect of normal pressure and sliding speed on surface roughness of specimens
From Fig.4.14 Under high sliding speed with increase in the normal pressure surface roughness is decreased. Under high sliding
speed effect of frictional temperature is high.
Therefore volumetric wear rate is high under high sliding speed as low normal pressure. Whereas for the same under high
normal pressure surface roughness is decreased. Under high normal pressure the surface roughness is almost reduced with the
sliding speed. Under high normal pressure the intimate contact between wearing pin surface with the disc is increased. Due to
this increase in more contact area the smoothness is increased hence with under high normal pressure with increase in sliding
speed roughness values is decreased.
Under high sliding speed with increase in the normal pressure the roughness is decreased. Under high sliding speed the micro
growth of weld is reduced due to reduction the residential time between the wearing pin with the disc. Hence under high sliding
speed with increase in normal pressure the roughness values are decreased.
VPN Test: The VPN test was carried out in the micro Vickers hardness tester after the wear test. Hardness is resistance of
material to plastic deformation caused by indentation. Sometimes hardness refers to resistance of material to scratching or
abrasion. Hardness may be measured from a small sample of material without destroying it. Principle of hardness test method is
forcing an indenter into the sample surface followed by measuring dimensions of the indentation (depth or actual surface area of
the indentation).
Tribological Investigations on Al-Al3Ti In-situ Metal Matrix Composite (IJIRST/ Volume 3 / Issue 01 / 020)
All rights reserved by www.ijirst.org 119
0 1 2 3
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Har
dnes
s V
alue
(Kg/
mm
2 )
Specimen Nos.
0.1248 MPa
0.3747 MPa
Sliding Speed - 1m/s
0 1 2 3
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Har
dnes
s V
alue
(Kg/
mm
2 )
Specimen Nos.
0.1248 MPa
0.3747 MPaSliding speed - 3 m/s
0 1 2 3
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Har
dnes
s V
alue
(Kg/
mm
2 )
Specimen Nos.
Speed (1 m/s)
Speed (2 m/s)
Load - 1 KG
0 1 2 3
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
Har
dnes
s V
alue
(Kg/
mm
2 )
Specimen Nos.
Speed (1m/s)
Speed (3m/s)
Load - 3 KG
Hardness Test
Effect of normal pressure on Hardness value for sliding speeds and loads
From fig. 4.15 with increase in hardness fraction of Ti hardness value is increased. Ti is ductile material so with increase in the
volume fraction of the Ti softness is increased hence the plastic deformation will also increase. With increase in the plastic
deformation work hardening takes place hence, values of the hardness for Al-7Ti is higher than the other two materials.
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
0 1 2 3 4
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
0 1 2 3 4
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Har
dnes
s V
alue
(Kg/
mm
2 )
Normal Pressure (MPa)
Sp.1. Al-3Ti
Sp.2. Al-5Ti
Sp.3. Al-7TiSliding Speed - 3 m/s
Har
dnes
s V
alue
(Kg/
mm
2 )
Normal Pressure (MPa)
Sp.No.1 Al-3Ti
Sp.No.2 Al-5Ti
Sp.No.3 Al-7Ti
Sliding Speed - 1 m/s
VPN Test
Har
dnes
s V
alue
(Kg/
mm
2 )
Sliding Speed (m/s)
Sp.No.1. Al-3Ti
Sp.No.2. Al-5Ti
Sp.No.3. Al-7Ti
Load -3 KG
Har
dnes
s V
alue
(Kg/
mm
2 )
Sliding Speed (m/s)
Sp.No.1 Al-3Ti
Sp.No.2. Al-5Ti
Sp.No.3. Al-7TiLoad - 1KG
Tribological Investigations on Al-Al3Ti In-situ Metal Matrix Composite (IJIRST/ Volume 3 / Issue 01 / 020)
All rights reserved by www.ijirst.org 120
Effect of specimens on Hardness
From fig.4.16 it is observed that, 7 Ti values are higher than the other two materials. Ti is ductile material so with increase in the
volume fraction of the Ti softness is increased hence the plastic deformation will also increase. With increase in the plastic
deformation work hardening takes place hence, values of the hardness is higher than the other two materials.
0.100.150.200.250.300.350.40
0.00.20.40.60.81.01.21.4
1.01.5
2.02.53.0 0.100.150.200.250.300.350.40
0.00.20.40.60.81.01.21.4
1.01.5
2.02.53.0
0.100.150.200.250.300.350.40
0.00.20.40.60.81.01.21.4
1.01.5
2.02.53.0
Speciman.3.Al-7TiData 3
Har
dnes
s V
alue
(kg/
mm
2 )
Sliding S
peed(m/s)
Normal Pressure(MPa)
Specimen.1.Al-3TiData 1
Har
dnes
s V
alue
(kg/
mm
2 )
Sliding S
peed(m/s)
Normal Pressure(MPa)
Specimen.1. Al-5TiData 2
Har
dnes
s V
alue
(Kg/
mm
2 )
Sliding S
peed(m/s)Normal PressureMPa)
Hardness Test
Effect normal pressure and sliding speed on hardness for specimens
From Fig.4.17 Under high sliding speed with increase in the normal pressure Hardness value is decreased. Under high sliding
speed effect of frictional temperature is high.
Therefore volumetric wear rate is high under high sliding speed as low normal pressure. Whereas for the same under high
normal pressure Hardness value is decreased. This may be due to high frictional temperature, at this high frictional temperature a
layer at wearing surface may be melted and this molten layer may be behaved as lubricated film so Hardness value is decreased.
For the specimen – 1, under low normal pressure of .1248MPa with increase in the sliding speed hardness values are
increased. Under low normal pressure the generation of frictional temperature is usually low hence, with increase in sliding
speed deformation of the worn surface is more so work hardening effect is more. Due to this work hardening the hardness values
are increased. Under high normal pressure with increase in the sliding speed hardness values are decreased. Under high normal
pressure the amount of area of contact is more and generation of frictional temperature is more, due to this frictional temperature
softening effect takes place. Due to this softening effect the worn surface hardness is deceased.
V. CONCLUSION
The present results suggest that the wear resistance of Al-Al3Ti composites increases with increase in percentage of Al3Ti
particles compared to pure aluminum. In addition, the improvement in mechanical properties of the composite was observed in
Al-5Ti specimen when compared to Al-3Ti and Al-7Ti and to the pure Al. Volumetric wear rate of Al-5Ti is less compare to Al-
3Ti and Brinell hardness value also more for Al-5Ti compare Al-3Ti, Al-7Ti. There is almost no variation at properties between
5Ti and 7Ti but there is much variation between 5Ti and 3Ti. Hence 5Ti is better material among 3Ti, 5Ti and 7Ti.
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