Trans Indian Inst Met

DOI 10.1007/s12666-016-0923-7

TECHNICAL PAPER

Evaluation of Mechanical and Tribological Behavior

of Al–4 %Cu–x %SiC Composites Prepared Through Powder
Metallurgy Technique
V. Selvakumar1 • S. Muruganandam2 • N. Senthilkumar3

Received: 28 December 2015 / Accepted: 7 June 2016

 The Indian Institute of Metals - IIM 2016

Abstract This article presents characterization of 99.85 % 1 Introduction

pure aluminum with 4 % copper, reinforced with varying
proportions of silicon carbide. Al–Cu–SiC metal matrix Development of newer material is needed at the moment in
composite (MMC’s) are prepared by powder metallurgy order to cater the needs of advanced aerospace and auto-
route for 0, 2.5, 5, 7.5, 10, 12.5 and 15 % of SiC addition. motive applications. Lightweight materials with improved
To investigate the effects of adding SiC particles, mechanical properties are required at this stage to improve
microstructural analysis and mechanical properties by the performance of the system with higher efficiency,
micro-hardness, compression, wear and thermal conduc- paving the way for newer composites. Researchers are
tivity are studied. Scanning electron microscope image working on aluminum based composites and magnesium
shows uniform distribution of particulates. Results show based composites due to less weight, improved mechanical
that upon increasing addition of SiC particles, micro- and physical properties. Composites are materials that are
hardness and compression strength increases, whereas prepared by adding two or more different materials, which
thermal conductivity decreases. Wear rate increases till will suppress the weakness of one material with the supe-
7.5 % SiC addition, with further addition of SiC, wear rate rior property of other [1]. The composite thus produced
increases due to the un-bonding of SiC particles from the will retain the individuality of the added material but
MMC, aiding in the increase of wear rate. Addition of SiC behaves differently than that of their parent materials.
up to 7.5 % play an important role in improving wear Composites may be either metal matrix composites or
resistance, thermal and mechanical properties of Al–Cu– polymer matrix composites, their selection depending on
SiC MMC. the properties and applications [2]. Other advantages of
using these MMC’s are, they can be used in conditions like
Keywords Aluminum MMC  Powder metallurgy  high operating temperatures up to 1260 C, conditions
Micro-hardness  Compression strength  Pin-on-disc requiring high strength coupled with ductility and tough-
ness. In comparison with engineering materials, these
composites offer better stiffness and strength, low thermal
expansion, enhanced resistance to fatigue, abrasion, and
wear [3]. The physical properties, wear and friction
behavior of aluminum MMCs, strongly depend on the
& N. Senthilkumar particles used for reinforcement, size of particles and vol-
nsk@adhiparasakthi.in
ume fraction of particles. The coefficient of friction of
1
Mahalakshmi Engineering College, Tiruchirappalli, metal matrix composites are high when the amount of
TamilNadu 621213, India particles reinforced in MMC is low and besides this, wear
2
K. Ramakrishnan College of Technology, Tiruchirappalli, resistance of MMC increases when particle volume frac-
TamilNadu 621112, India tion increases in the matrix. When particulates used as
3
Adhiparasakthi Engineering College, Melmaruvathur, reinforcement are well bonded to the MMC matrix, wear
TamilNadu 603319, India resistance continuously increases with increased ceramic

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particles volume fraction and while performing wear test, the influence of SiC addition in the aluminum matrix added
load applied determines the critical volume fraction of the with 4 % Copper.
particulates.
Rahman and Rashed [4] studied the wear and mechan-
ical behavior of aluminum MMC reinforced with SiC of 2 Fabrication of Aluminum Metal Matrix
varying proportions and showed that hardness, tensile Composite
strength and wear resistance increases with addition of SiC
reinforcements. Singh and Singla [5] developed alu- In powder metallurgy technique, the base materials used
minum–silicon carbide particulate composites by are calculated as per the volume fractions, weighted and
mechanical alloying route of powder metallurgy and then mixed well, so that the entire powder is homogenous.
showed that uniform dispersion of silicon carbide in matrix Compaction of mixed metal powder is performed under
is possible and observed that the hardness increases with pressure in a closed metal cavity which makes the desired
increase in reinforcement and wear rate decreases linearly shape and size of the product using a die as per the
with silicon carbide addition. requirement. Next step is sintering process. At higher
Khaloobagheri et al. [6] produced copper matrix temperatures, in controlled atmosphere, the compacted
composites with yittria stabilized zirconia as reinforce- specimens are placed in oven. Coalesce of metal powder
ment through powder metallurgy route and found that occurs to form a solid specimen. Repressing should be
mechanical properties increases with reinforcement and carried out after sintering process as a second pressing to
electrical conductivity decreases. Adeosun et al. [7] improve the compacting strength and their properties
reviewed the various work performed on aluminum [11, 12]. Aluminum MMC is prepared and characterized in
composites to study their mechanical, chemical and this work. Al–4 %Copper–x %Silicon carbide is prepared
physical properties and found that type of reinforcement, by powder metallurgy route. In the chosen composite, x %
size of particles, volume of reinforcement and dispersion represents 0, 2.5, 5, 7.5, 10, 12.5 and 15 % of reinforce-
of particles on matrix determines the behavior of com- ment of silicon carbide ceramic particles in matrix of
posites. Jiang and Wang [8] investigated the mechanical aluminum added with 4 % of copper. Initially the starting
and microstructure of 7075 aluminum MMC and found materials: aluminum, copper and silicon carbide, are taken
that ultimate strength and yield strength of rheoformed as per calculated volume fractions and are weighed, mixed,
parts are better than the extruded parts and increase in compacted and sintered for various compositions of SiC
stirring time, pressure and SiC volume fraction improves such as 0, 2.5, 5, 7.5, 10, 12 and 15 % while the percentage
the mechanical properties. of copper is maintained at 4 %. The mixed powders are
The wear and friction performance of aluminum matrix compacted at 20 tons in a closed die. The compacted
MMCs mainly depends on the reinforced particles, their sample is sintered at 500 C for 3 Hours. The furnace has
sizes and volume fractions. The coefficients of friction of been maintained with nitrogen atmosphere of 0.5 L per
MMCs are high if low volume of particles are reinforced in minute. This lightweight material produced will have the
the MMC and besides, if reinforcement volume fraction desired mechanical properties and better thermal conduc-
increases, wear resistance increases [9]. Particulates used tivity with the presence of copper, which is suppressed due
as reinforcement increases the wear resistance, if they are to the addition of SiC. The sequence of operations per-
well bonded in the matrix. Study on Wear behavior of SiC formed in the powder metallurgy route to develop the
and graphite reinforced in aluminum alloy composite using specimen from powdered raw materials and the types of
pin-on-disc setup shows that addition of graphite reduces testing performed on the specimen to study its mechanical
the volume loss during wear and sliding speed is the most and thermal behavior is shown as a flow chart in Fig. 1.
critical parameter that affects the wear rate [10].
Microstructural analysis, thermal behavior and 2.1 Matrix Material
mechanical behavior of aluminum based MMC reinforced
with 4 % copper and different proportions of silicon car- Aluminum is the lightest material owing to which, it is
bide are studied in this work which have been prepared by mostly used in industries, specifically in automotive and
using powder metallurgy technique for effective applica- aerospace applications. It is the most economical, having
tion in automotive and aerospace applications. Based on attractive aesthetic look, easy to fabricate into intrinsic
the literature survey performed, volume fractions of SiC components, and possesses a moderate physical, mechan-
addition is considered. Many authors considered larger ical properties and resistance to corrosion. Advantages
volume fractions of SiC addition in the matrix to study its related to selection of aluminum lies in their; high strength-
behavior. Varying the volume fraction in small quantities to-weight ratios, good electrical and thermal conductivities,
by 2.5 % starting with 0 % of SiC up to 15 % provides us non-toxic in nature, good reflectivity, better appearance,

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Fig. 1 Flowchart of preparation

and testing of composite
material

non-magnetic and can easily be formed or machined to conductivity, develops extreme hardness and resistance to
desired shape. With these excellent properties, aluminum is corrosion [14]. Due to these properties, it produces a better
selected as the matrix material and the properties are thermal shock resistance.
enhanced with the addition of reinforcing material to
improve the mechanical and physical properties. Alu-
minum is not only used as matrix material, but can also be 3 Microstructural Characterization
used as reinforcement with polymer as matrix in rapid
prototyping applications. Examining and determining the various constitution and
determination of structure of constituents present in the
2.2 Reinforcing Materials metals and their alloys is known as Metallography. The
other name for metallography is materialography [15].
Copper is reinforced with aluminum to improve the dam- Characterization of metals and alloys using optical method
age tolerances and is applied in airframe structural appli- involves identification of various phases, precipitation of
cations [13]. Pure powder of copper added to other alloying element and identification of size and shape of the
materials improves electrical and thermal conductivities of grains present, different characteristics of grain boundaries
the material. Copper added with other alloying elements, is and defects associated with the material [16]. In this era,
used in friction materials and structural parts. Addition of even though sophisticated electron microscopic instru-
copper improves high temperature properties of the mate- ments have been invented, both transmission and scanning
rial, their fatigue properties, heat conductivity, and electron microscopes should be used in line with these
machinability and at low temperatures, retention of optical microscopy techniques. Macro examination of the
mechanical and electrical properties. powder metallurgy specimen is performed to reveal the
Silicon Carbide is a ceramic material having higher refinement of grain structure, its grain size, various grain
refractive index when compared with diamond. SiC has boundaries and abnormalities present. Micro examination
lower thermal expansion coefficient, better thermal [17, 18] is performed with the help of scanning electron

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microscopy that uses secondary electrons and also back The rest of the matrix shows fine fused Cu–Al2 in alu-
scattered electrons to capture the image of the specimens. minum solid solution. The particles of SiC are uniformly
With the help of secondary electrons, expansion of reso- present and are distributed in the matrix [16, 22]. The SiC
lution range to few nanometers is possible which bridges particles are shown as dark grey particles in Al–Cu matrix.
the gap that exists between light and transmission electron The micrograph of Al–4 %Cu–7.5 %SiC specimen shows
microscopy [19]. some un-fused/undissolved free copper in the matrix with
The micrograph image of the reinforcing material SiC is 0.6 % by volume fraction. Rest of the matrix shows fine
shown in Fig. 2, which reveals the grain size and grain fused Cu–Al2 in aluminum solid solution. Distribution of
shape of the ceramic particulates. Properties of the P/M SiC particles are uniform and are seen as dark grey parti-
specimens prepared have been characterized by interface cles. Comparing to the 5 % sample, it is observed that the
characteristics between the copper and SiC reinforcements presence of SiC particles in aluminum matrix are more.
in the pure aluminum matrix and its microstructure. The The microstructure of Al–4 %Cu–10 %SiC powder
micrograph of Al–4 %Cu composite material without metallurgy composite shows fine fused Cu–Al2 in alu-
ceramic particulate reinforcement is also shown in Fig. 2. minum solid solution. Ceramic particles are uniformly
Aluminum matrix is seen as grey background with the distributed in the matrix. As percentage of SiC is increased,
white glossy particles being copper. Even distribution of the particles of SiC are more in given field of view.
copper is observed in the aluminum matrix. This sample is Micrograph of Al–4 %Cu–12.5 % SiC composite shows
the powder metallurgical product of pure aluminum and fine fused Cu–Al2 in aluminum solid solution as in the
pure copper in 96:4 ratios, compacted at 640 MPa pressure. previous specimens and even distribution of SiC particles
The SEM image shows the metal matrix composite with in the matrix is observed. SEM image of Al–4 %Cu–
the unfused particles of copper. The micrograph also shows 15 %SiC specimen shows some undissolved free copper in
partial dissolution of copper in aluminum solid solution the matrix with uniform distribution of SiC particles.
which occurs during sintering. This may have been due to Higher SiC particles can be viewed in the matrix due to the
low sintering temperature and variations in the sizes of higher amount of addition of SiC.
copper powder particles such that the higher sized grains
are insoluble. The dissolution of the copper in aluminum
depends on the temperature and the size of the grains. 4 Determinations of Mechanical Properties
The microstructure of various percentile reinforcements
of SiC particulates in the aluminum–copper MMC is pre- 4.1 Micro-Hardness Test
sented in Fig. 3.
The SEM image of Al–4 %Cu–2.5 %SiC powder-met- Resistance of metal components to plastic deformation, by
allurgical product is compacted at 20 tons in a closed die. means of indentation is known as Hardness [20]. Classifi-
The microstructure shows some unfused/undissolved free cations of hardness measurement are based on applied
copper in the matrix. The percentage of free copper is forces and amount of displacements occurring: the types
about 0.6 % in volume. The rest of the matrix shows fine being macro scale, micro scale and nano-scale [21]. Micro-
fused Cu–Al2 in aluminum solid solution. The micrograph hardness are eventual, when materials are multiphasic and
of Al–4 %Cu–5 %SiC powder metallurgical specimen have fine microstructure that are inhomogeneous and are
shows some unfused/undissolved free copper in the matrix. prone to cracking. Micro-hardness determines the hardness
The percentage of free copper is about 0.6 % in volume. of the material by forcing a small sized indenter under pre-

Fig. 2 SEM images of SiC and

Al–Cu composite without SiC
addition

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Fig. 3 SEM micrographs of

various percentiles of SiC in
Al–4 %Cu matrix

determined load into the material surface and by calculat- gauge measures the difference in depth that is caused by
ing the deformation occurred. Micro-hardness is typical in the application of two different forces. The hardness values
determining the hardness of casehardening. With the help of the prepared P/M specimens are determined using
of Rockwell hardness tester, ceramic substrates hardness Rockwell T-scale with a load of 15 kgf and are plotted as
can be determined as per ASTM E18 standards, a dial shown in Fig. 4. The hardness values obtained shows that,

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Fig. 4 Hardness values of P/M

specimens

with increase in SiC reinforcement in the aluminum–cop- Compression strength of various compositions of MMC
per MMC, increase in hardness is observed. This is due to
25
the presence of harder ceramic SiC reinforcement which
bonds in the matrix, impeding the dislocations movement 20
inside the matrix, aiding in improved hardness [4, 13].

Load (kN)
Initially with the addition of SiC particles [22], hardness 15

values increases considerably but after a particular point,

10
the increase in hardness is less. This is due to addition of Aluminum + Copper
Aluminum + Copper + 2.5% SiC
more amounts of SiC particles in the aluminum matrix, 5 Aluminum + Copper + 5% SiC
Aluminum + Copper + 7.5% SiC
which has even distribution of SiC particles [22]. Smaller Aluminum + Copper + 10% SiC
Aluminum + Copper + 12.5% SiC
grain size and decreased dislocations attributes to the 0 Aluminum + Copper + 15% SiC

increase in hardness with more addition of SiC reinforce- 0 1 2 3 4 5 6 7

Displacement (mm)
ment in the aluminum matrix added with copper [6].
Fig. 5 Compression strength of P/M specimens
4.2 Compression Test

Axial compression testing is performed on materials to matrix, load required to fracture the material decreases, due
measure their ductile fracture limits and plastic flow to the brittle nature of the composite. Ductile behavior of
behavior for further studies [23]. Behavior of materials the Al–Cu is changed to brittle by adding SiC particles.
under the influence of crushing load is characterized by Copper is a ductile material, due to which, with zero or
means of compression test, which records the various loads lesser addition of SiC particles, compression strength is
during material deformation [24]. This compression test is higher and with higher addition of SiC particles, com-
done to determine the yield strength, proportional limit, pression strength reduces due to the brittle nature of
yield point, elastic limit and compressive strength and composite. Dispersion hardening effect and high hardness
graphs are plotted between load and displacement, stress are the two strengthening mechanisms behind high hard-
and displacement, stress and strain and bending moment ness and compression strength of the composite. Prevent-
diagram. This test is particularly useful to measure the ing the dislocation motion and its propagation decides the
compressive and elastic fracture properties [25, 26] of strength of metallic materials. Under applied stress,
material with low ductility/brittle materials and in some increasing gear boundaries acts as an obstacle to the dis-
cases, usage of larger L/D ratio specimens must be avoided location movement and these dislocations pile up at the
so that buckling and shear deformation can be prevented. grain boundaries [6].
The machine used for compression test and extensometers Ultimate stress, breaking load, displacement at Fmax
are those used for tension tests in a universal testing (maximum force) and maximum displacement values
machine [27]. To prevent the buckling of load chain during obtained during the compression test for all specimens is
testing prior to material failure or fracturing the sample, shown in Fig. 6. Observation shows that increase in com-
specimens used should be short and stubby. pression test values is seen up to the addition of 7.5 % of
Compression strengths of the prepared composites are SiC and afterwards a downward trend is observed due to
plotted as in Fig. 5. From the graph, it is observed that, the brittle behavior of composite. A considerable decrease
with increase in percentage of SiC particles in Al–Cu in breaking load and displacement is observed by

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Reinforcement of Silicon Carbide vs. Compression Test values proportions of SiC in the MMC. From results obtained, it is
25.780 25.855

25
25.818 observed that wear rate of the cast MMC is reduced up to
the addition of 7.5 % SiC and with further addition of SiC
19.955
20
Ultimate Stress (kN/mm2) 17.870
reinforcement in the matrix, wear rate is increased, due to
Breaking Load (kN)
Displacement at FMax (mm)
15.260 the fact that, excess removal of SiC particles from the
15
Y-Data

Max Displacement (mm)

matrix aids in increasing the wear rate by an amount.
11.255

10 Hence, SiC addition in the Al–4 %Cu matrix is limited to

5.7 6.1 6.6 7.5 % only. During wear test, the exposed aluminum
4.5 4.9 5.1 4.5
5 3.7 3.4
2.8
matrix wears faster than the harder SiC ceramic particles,
2.1 2.1 1.9
0.080 0.081 0.081 0.062 0.056 0.047
1.2
0.035 exposing the SiC particles separately on the worn surface.
0
Further wear of aluminum matrix is protected by the
0.0 2.5 5.0 7.5 10.0 12.5 15.0
Reinforcement of SiC
exposed SiC particles and with increase in SiC addition in
the matrix, wear resistance of the contacting surface is
Fig. 6 Behavior of P/M specimens during compression test increased [4]. Unbonding of SiC particles takes place when
added in higher percentage, which indirectly removes more
increasing the percentage of SiC content in the matrix amount of material from the aluminum matrix [32].
beyond 7.5 %. During testing, the wear behavior of Al–4 %Cu without
the reinforcement of particles i.e the coefficient of friction
4.3 Pin-on-Disc Test (COF) and frictional force (FF) obtained are shown in
Fig. 8. It is found that the maximum COF and FF for 2.5 %
Wear behavior of materials can be determined with the SiC reinforcement is 0.68 and 2.03 N, minimum COF and
help of a tribological meter; used to calculate the materials FF is 0.18 and 0.55 N respectively and for 5 % SiC rein-
wear rate [28–30]. Tribological parameters like frictional forcement it is 0.18 and 0.55 N.
force, coefficient of friction, volume loss of material and The COF and FF obtained during the wear test for the
wear rate between the contact surfaces can be measured by MMC containing 2.5, 5, 7.5, 10, 12.5 and 15 % SiC rein-
tribometer. The simplest of the tribometer is pin-on-disc forcement in Al matrix with addition of Cu are shown in
tribometer, consisting of a stationary pin that is spherical in Figs. 9, 10, 11, 12, 13 and 14 respectively.
shape, which will be in contact with the rotating disc for a The maximum COF and FF obtained for 2.5 % SiC
given load [31, 32]. Pin-on-disc instrument consists of a reinforcement is 0.66 and 1.99 N and minimum COF and
rotating disc in which a pin is pressed with a defined load FF obtained is 0.13 and 0.40 N. Similarly for 5 % SiC
and in the tip of the pin, a radius is provided, resulting in reinforcement, maximum COF and FF obtained is 0.66 and
point contact between the rotating disk and pin. During the 1.69 N, minimum COF and FF obtained is 0.13 and
wear test, this point contact increases its area of contact. 0.40 N. It is found that addition of small amount of SiC in
During the test, motion of rotating disc will not be reversed the matrix does not produce a change in COF and FF but
and presence of lubricating film between the pin and disc is the wear rate decreases. For 7.5 % SiC addition to Al–Cu
totally eliminated. Thereby an ideal sliding friction is matrix, the maximum COF and FF observed is 0.56 and
assumed to occur between the friction components. Sliding 1.69 N and minimum values are 0.31 and 0.92 N. When
velocity, load on the pin, sliding distance of pin and rota- the SiC addition is raised to 10 % in the matrix, maximum
tional speed of pin are varied during the pin-on-disc test value of COF and FF is 0.5 and 1.5 N and the minimum
[33, 34]. Ratio of friction force to applied load on pin COF and FF are 0.26 and 0.77 N, which records the lowest
provides coefficient of friction [35]. Wear rate on the pin value of FF among the prepared specimens. 12.5 % addi-
during the test is calculated from the formulae given in tion of SiC produces a maximum and minimum COF of
Eq. (1). 0.68 and 0.11 N, maximum and minimum FF of 2.04 and
0.34 N which is the lowest COF values among all the
Dw
Wear rate ¼ g/cm ð1Þ specimens. Maximum COF and FF values of 0.62 and
2prNt
1.86 N is obtained for 15 % addition of SiC particulates in
where Dw—difference in weight of pin before and after the matrix, and also produces minimum COF and FF of
wear test w1 - w2 (g), 2pr—is the sliding distance (cm), 0.12 and 0.35 N.
N—is the rotational speed of the disc (800 rpm), t—is the From the results of wear test, it is understood that as the
time period of wear test (10 min) [36]. percentile reinforcement of SiC particulates increases in
After performing the wear test for varying percentage of the aluminum matrix [35], after a certain percentile of
SiC particles in matrix of Al–4 % copper, the wear rate is reinforcement, the SiC particles gets removed from the
calculated. Figure 7 shows the wear rate for various matrix, which aids in further wear.

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Fig. 7 Wear rate of various

composition of MMC

Wear behavior of Al-4%Cu Wear behavior of Al-4%Cu-5%SiC

Coefficient of Friction 2.0 Coefficient of Friction
2.0
Frictional Force Frictional Force

1.5 1.5
Y-Data

Y-Data
1.0 1.0

0.5 0.5

0.0 0.0
0 100 200 300 400 500 600 0 100 200 300 400 500 600
Time (s) Time (s)

Fig. 8 Wear performance of Al–4 %Cu without SiC addition Fig. 10 Wear performance of Al–4 %Cu–5 %SiC

Wear behavior of Al-4%Cu-2.5%SiC Wear behavior of Al-4%Cu-7.5%SiC

2.0 Coefficient of Friction 1.8 Coefficient of Frictio
Frictional Force
Frictional Force
1.6

1.5 1.4

1.2
Y-Data

Y-Data

1.0 1.0

0.8

0.5 0.6

0.4
0.0 0.2
0 100 200 300 400 500 600 0 100 200 300 400 500 600
Time (s) Time (s)

Fig. 9 Wear performance of Al–4 %Cu–2.5 %SiC Fig. 11 Wear performance of Al–4 %Cu–7.5 %SiC

4.4 Thermal Conductivity

net heat energy will flow and a temperature difference will
Conduction is a basic heat-transfer process that involves exist between the two ends of the material. Coefficient of
transfer of thermal energy from molecule to another thermal conductivity will be low in plastics and ceramics
molecule within a material by means of pure thermal and high in metals [40]. In manufacturing, thermal property
motion without mass transfer [37, 38]. Thermal conduc- of materials plays a vital role due to the generation of heat
tivity is the ability of a material to conduct heat by physical during machining process as a consequence of the process.
phenomenon, measured by the coefficient of thermal con- During machining process, the mechanical operation per-
ductivity k [39]. Through the length of the given material, formed will raise the temperature of the workpiece due to

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Wear behavior of Al-4%Cu-10%SiC SiC inclusion in the matrix, the thermal conductivity of the
1.6
material gets dropped [42] due to the presence of ceramic
1.4 particles. When more amount of ceramic particles are
1.2
present, heat transfer is affected, paving the way for loss in
thermal conductivity [7].
1.0
Y-Data

From the experimental results, it is understood that

0.8 Coefficient of Friction 7.5 % addition of SiC produces better mechanical and
Frictional Force
0.6
Tribological properties than the higher volume fractions of
SiC. Further investigations on addition of SiC up to 15 %
0.4
volume fraction is carried out, in order to study the influ-
0.2 ence of higher SiC reinforcements in aluminum matrix
0 100 200 300 400 500 600
Time (s)
added with 4 % copper to understand the phenomenon and
the effect on the mechanical and Tribological properties of
Fig. 12 Wear performance of Al–4 %Cu–10 %SiC the composite if SiC is further increased beyond 7.5 %.
Higher volume fractions up to 15 % SiC addition is con-
Wear behavior of Al-4%Cu-12.5%SiC
sidered since most of the researchers has used this volume
Coefficient of Friction
fractions in their study. Increase in SiC volume fraction
2.0
Frictional Force increases the hardness of composite, which in turn
increases the porosity and reduces the elongation of com-
1.5 posite and area reduction.
Y-Data

1.0
5 Conclusions
0.5
Behavior of Al–4 %Cu–x %SiC composites prepared by
powder metallurgy route are analyzed through
0.0
0 100 200 300 400 500 600 microstructural analysis and mechanical testing, leading to
Time (s) the following conclusions.
Fig. 13 Wear performance of Al–4 %Cu–12.5 %SiC • Micrograph images taken from the P/M specimen’s
shows uniform distribution of copper powders and
silicon carbide particulates in aluminum matrix com-
Wear behavior of Al-4%Cu-15%SiC
2.0
Coefficient of Friction
posite, enhancing the mechanical and wear properties.
Frictional Force • With addition of SiC particles in Al–4 %Cu matrix,
hardness of composite increases due to refinement and
1.5
homogenization of SiC particles which are embedded
in the matrix, and impede the dislocations movement
Y-Data

1.0
inside the matrix, resulting in improved hardness.
• Compressive strength of composite decreases with
0.5 increase in SiC addition and presence of copper, which
tends to alter the ductile property of the aluminum
matrix to hard brittle material. Alloying decreases
0.0
0 100 200 300 400 ductility with increase in the strength.
Time (s) • The wear properties of the P/M Al–4 %Cu–x %SiC MMC
Fig. 14 Wear performance of Al–4 %Cu–15 %SiC are improved significantly by the addition of SiC partic-
ulates which leads to the decrease in wear rate up to the
addition of 7.5 % SiC in the aluminum matrix. With
its specific heat. During these operations, the workpiece addition of higher volume percentage of SiC, unbonding
should be able to conduct the heat away from its source of ceramic particles paves the way for high wear.
which is highly desirable [41]. After adding copper and • A moderate COF and FF are observed for 5 and 7.5 %
silicon carbide as reinforcement in aluminum matrix, SiC reinforced MMC whereas for other reinforcements,
thermal conductivity of the specimens are determined and the maximum and minimum COF and FF vary consid-
the results obtained is shown in Fig. 15. With increase in erably. The variation in COF and FF for 7.5 % SiC

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Fig. 15 Thermal conductivities

of P/M specimens

reinforced MMC shows a lower variation, but for other 13. Rajaram G, Kumaran S, and Srinivasa Rao T, Transactions of
percentile reinforcements, the variation is significant. The Indian Institute of Metals 64 (2011) 53.
14. Ipek R, Journal of Materials Processing Technology 162–163
• Thermal conductivity of Al–4 %Cu composite (2005) 71.
decreases with addition of more ceramic particulates, 15. Ruth E Whan, Materials Characterization, Volume 10, ASM
which inhibits the transfer of heat across the aluminum International, USA (1992).
matrix. Reduction in thermal conductivity is due to 16. Ali Mazhery, and Mohsen Ostad Shabani, Transactions of Non-
ferrous Metals Society of China 23 (2013) 1905.
interfacial properties between the matrix and ceramic 17. Akhlaghi F, Lajevardi A, and Maghanaki H M, Journal of
particulates and also due to low thermal expansion of Materials Processing Technology 155–156 (2004) 1874.
SiC than aluminum matrix. 18. Shorowordi K M, Laoui T, Haseeb A S M A, Celis J P, and
• Desired mechanical properties are achieved with addi- Froyen L, Journal of Materials Processing Technology 142
(2003) 738.
tion of 7.5 % SiC particles in matrix of aluminum 19. George F Vander Voort, Metallography and Microstructures-
added with 4 % copper for applications in aerospace ASM Handbook, Volume 9, ASM International, USA (2004).
and automotive applications. 20. Joseph R Davis, Metals Handbook Desk Edition, Second Edition,
ASM International, USA (1998).
21. Ronald F Gibson, Principles of Composite material mechanics,
McGraw-Hill, Inc., New York (1994), p 374.
22. Rana R S, Rajesh Purohit, Soni V K, and Das S, Materials Today:
Proceedings 2 (2015) 1149.
References
23. Howard Kuhn, and Dana Medlin, Mechanical Testing and
Evaluation, Volume 8, ASM International, USA (2000).
1. Black J T, and Kohser R A, DeGarmo’s Materials and Processes 24. Jin-Chein Lin, Composites Part B: Engineering 38 (2007) 79.
in Manufacturing, Tenth Edition, John Wiley & Sons, Inc, USA 25. Yao X, Zheng Y F, Liang J M, and Zhang D L, Materials Science
(2008), p 334. and Engineering: A 648 (2015) 225.
2. Senthilkumar N, Kalaichelvan K, and Elangovan K, International 26. Huda D, El Baradie M A, and Hashmi M S J, Journal of Mate-
Journal of Mechanical and Materials Engineering 7 (2012) 214. rials Processing Technology 56 (1996) 452.
3. Serope Kalpakjian, and Steven R Schmid, Manufacturing Engi- 27. Mario F Moreno, Carlos J R, and Gonzalez Oliver, Materials
neering and Technology, Prentice Hall, New York (2009), p 216. Science and Engineering: A 418 (2006) 172.
4. Md Habibur Rahman, and Mamun Al Rashed H M, Procedia 28. Hani Aziz Ameen, Khairia Salman Hassan, and Ethar Mohamed
Engineering 90 (2014) 103. Mhdi Mubarak, American Journal of Scientific and Industrial
5. Ramanpreet Singh, and Rahul Singla, International Journal of Research 2 (2011) 99.
Applied Engineering Research 7 (2012) 1420. 29. Rajmohan T, Palanikumar K, and Ranganathan S, Transactions of
6. Khaloobagheri M, Janipour B, Askari N, and Shafiee Kamal Nonferrous Metals Society of China 23 (2013) 2509.
Abad E, Advances in Production Engineering & Management 8 30. Muthu Kumar V, Venkatasamy R, Suresh Babu A, Jagan K, and
(2013) 242. Nithin K, International Journal of production technology and
7. Adeosun S O, Osoba L O, and Taiwo O O, World Academy of Management Research 2 (2011) 49.
Science, Engineering and Technology 8 (2014) 737. 31. Kori S A, and Prabhudev M S, Wear 271 (2011) 680.
8. Jufu Jiang, and Ying Wang, Materials & Design 79 (2015) 32. 32. Natarajan N, Vijayarangan S, and Rajendran I, Wear 261 (2006)
9. Gursoy Arslan, and Ayse Kalemtas, Journal of the European 812.
Ceramic Society 29 (2009) 473. 33. Basavarajappa S, Arun K V, and Paulo Davim J, Journal of
10. Basavarajappa S, and Chandramohan G, Journal of Materials Minerals & Materials Characterization & Engineering 8 (2009)
Engineering and Performance 15 (2006) 656. 379.
11. ASM International Handbook Committee, Powder Metal Tech- 34. Fatih Erdemir, Aykut Canakci, Temel Varol, and Serdar Ozkaya,
nologies and Applications, Volume 7, ASM International, USA Journal of Alloys and Compounds 644 (2015) 589.
(1998). 35. Yang L J, Wear 255 (2003) 579.
12. Aykut Canakci, and Temel Varol, Powder Technology 268 36. Senthilkumar N, Tamizharasan T, and Anbarasan M, Journal of
(2014) 72. Advanced Engineering Research 1 (2014) 48.

123
Trans Indian Inst Met

37. Prieto R, Molina J M, Narciso J, and Louis E, Composites Part A: 41. Mikell P Groover, Fundamentals of Modern Manufacturing-
Applied Science and Manufacturing 42 (2011) 1970. Materials, Processes and Systems, fourth edition, John Wiley &
38. Huber T, Degischer H P, Lefranc G, and Schmitt T, Composites Sons, Inc., USA (2010), p 67.
Science and Technology 66 (2006) 2206. 42. Mohan Krishna S A, Shridhar T N, and Krishnamurthy L, In-
39. Chen J K, and Huang I S, Composites: Part B 44 (2013) 698. ternational Journal of Material Science 5 (2015) 54.
40. Arpon R, Molina J M, Saravanan R A, Garcia-Cordovilla C,
Louis E, and Narciso J, Acta Materialia 51 (2003) 3145.

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