B. M. M. SELVAN et al.: INVESTIGATION OF TRIBOLOGICAL BEHAVIOR OF AA8011-ZrB2 IN-SITU ...
451–457
INVESTIGATION OF TRIBOLOGICAL BEHAVIOR OF
AA8011-ZrB
2
IN-SITU CAST-METAL-MATRIX COMPOSITES
RAZISKAVA TRIBOLO[KIH LASTNOSTI IN-SITU LITEGA
KOMPOZITA S KOVINSKO OSNOVO AA8011-ZrB
2
Muthamizh Selvan Bellamballi Munivenkatappan, Anandakrishnan Veeramani,
Duraiselvam Muthukannan
Department of Production Engineering, National Institute of Technology Tiruchirappalli-620015 Tamilnadu, India
krishna@nitt.edu
Prejem rokopisa – received: 2017-04-26; sprejem za objavo – accepted for publication: 2018-02-02
doi:10.17222/mit.2017.046
Aluminium alloy 8011 matrix composites reinforced with different weight percentages of ZrB2 were successfully fabricated
using an in-situ casting technique. X-ray diffraction and scanning electron microscopic analyses were performed to examine the
presence and distribution of the reinforcements in the composites. Wear tests were performed with the weight percentage of the
reinforcement, temperature, load, sliding velocity and sliding distance as the input parameters for the wear rate as response. D3
steel was used as the counterpart. The effects of various factors on the wear rate were analysed using analysis of variances. The
optimal combination of the 1500-m sliding distance, 4 % of mass fractions of ZrB2 reinforcement, 200°C temperature, 10 N
load and 2 m/s sliding velocity was found to give the minimum wear rate.
Keywords: in-situ stir casting, aluminium-matrix composites, wear behavior, design of experiments
V ~lanku avtorji opisujejo uspe{no izdelavo kompozitov z matrico iz Al zlitine 8011 in oja~ano z razli~no vsebnostjo ZrB2.S
pomo~jo spektroskopije uklona rentgenskih `arkov (XRD) in vrsti~ne elektronske mikroskopije (SEM) so dolo~ili dele` in
porazdelitev oja~itvene faze v izdelanih kompozitih. Izvedli so tudi teste njihove obrabe v odvisnosti od temperature,
obremenitve, hitrosti in razdalje drsenja. Kot protidrsni element so uporabili orodno jeklo D3. Z analizo varianc so dolo~ili vpliv
razli~nih faktorjev na hitrost obrabe. Ugotovili so, da je dose`ena najmanj{a hitrost obrabe, ko so razdalja drsenja 1500 m,
masni dele` ZrB2 4 %, temperatura 200 °C, obremenitev 10 N in hitrost drsenja 2 m/s.
Klju~ne besede: in-situ litje s preme{avanjem taline, kompoziti z matrico na osnovi Al zlitine, obstojnost proti obrabi,
na~rtovanje eksperimentov
1 INTRODUCTION
Metal-matrix composites (MMCs) are a type of
composite material that is a macroscopic combination of
two or more distinct materials with a recognizable
interface between them.
1
Particle-reinforced aluminium
matrix composites (AMCs) possess superior properties,
such as low density, high strength-to-weight ratio, spe-
cific stiffness, good shock absorption, good dimensional
stability for casting, resistance to corrosion, wear, abra-
sion, temperature, easy workability and easy fabrication.
Due to these excellent properties AMCs are used in the
applications of aerospace, automotive, electronics
industries, and sports equipment. AMCs are extensively
used in the fabrication of critical components like brake
drums, pistons, cylinder heads, cylinder liners, drive
shafts, etc. by automobile companies like Honda, Nissan,
Toyota and General Motors. AA8011 alloy is used as a
substitute for the AA3003 aluminium alloy to avoid
problems such as contamination of the melting and
holding furnaces. AA8011 is widely used in the pro-
duction of semi-rigid containers and in the packaging of
foods and dairy products.
2–6
Aluminium composites are
fabricated with various methods such as powder metal-
lurgy,
7
vortex method,
8
squeeze casting,
9
stir casting ex
situ,
10
thermal spray deposition,
11
laser surface alloying
12
and reactive process in situ.
13
The in-situ technique has
an advantage over other techniques such as the econo-
mical, uniform distribution of reinforcements, grain
refinements, clear interface, good interfacial bonding
strength between the matrix and reinforcement without
the need of a wetting agent and a high degree of thermal
stability.
14–18
From the literature, it was found that
AMC’s are fabricated with many reinforcements such as
SiC, TiC, Al
2
O
3
,T i B
2
, ZrB
2
, in the form of oxides,
carbides, nitrides, borides, fly ash, etc.
4,14,19
Among the
reinforcements, ZrB
2
is a promising candidate with its
excellent properties, such as high melting point
(>3000 °C), high hardness, chemical inertness against
molten metal, high thermal shock resistance, high wear
resistance, excellent covalent bond, high corrosion
resistance, better thermal and electrical conductivity,
which is much needed in the aerospace applications.
14–18
Generally, reinforced aluminium composites show
superior tribological properties compared to the unrein-
forced aluminium alloy.
4,19
The wear behaviour of alumi-
nium matrix composites reinforced with multi-walled
carbon nano tubes was synthesized through the powder
metallurgy technique. The wear resistance enhanced with
Materiali in tehnologije / Materials and technology 52 (2018) 4, 451–457 451
UDK 67.017:669.715:539.538 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 52(4)451(2018)

the addition of multi-walled carbon nano tubes in alu-
minium.
20
The hybrid AA2024 with5%o fm a s s
fractions of SiC and graphite (0, 5 and 10) % of mass
fractions fabricated by the powder metallurgy method
was investigated using the pin-on-disc method to study
the tribological property of the composite. The addition
of the SiC and the graphite improved the wear resistance
in the composite material.
21
Rao et al. fabricated the
Al-Zn-Mg aluminium alloy with the SiCp (10, 15 and
25) % of mass fractions of particles using the stir-casting
technique. The pin-on-disc was used for an investigation
of the dry sliding wear behaviour of the materials. The
wear rate of the alloy was increased due to the addition
of reinforcement.
22
AA5052 was developed with ZrB
2
through the in-situ stir-casting technique. The K
2
ZrF
6
and KBF
4
were the halide salts added in the molten form
of aluminium, which was maintained at a working
temperature of 860 °C to synthesize ZrB
2
in the AA5052
alloy. The AA5052-ZrB
2
showed improvement in the
ultimate tensile strength and a 0.2 % yield strength up to
9 % of volume fractions of ZrB
2
.
14
The AA6061/ZrB
2
was fabricated through the in-situ casting technique. The
dry sliding wear behaviour was investigated on alumi-
nium composites. The in-situ formed ZrB
2
particles in
the aluminium alloy improved the wear resistance of the
composite.
15
The in-situ composites of AA6351-ZrB
2
(0, 3, 6 and 9) % of mass fractions were synthesized by
the in-situ stir-casting technique. The results indicated
that the wear rate was decreased with an increase in the
weight percentage of ZrB
2
.
16
AA4032-TiB
2
-ZrB
2
hybrid
composite is fabricated through the in-situ stir casting
technique. The working temperature was 850 °C. A
Taguchi L25 orthogonal array is used to design the
experimental trials.
17
In-situ Al composites reinforced by
Al
3
Zr and ZrB
2
particles fabricated with the different
combinations of (10, 15, 20, and 25) %, the dry sliding
wear properties of the composites were investigated. The
inclusion of ZrB
2
increased the wear resistance.
23
Design of experiments (DoE) is a statistical tool that
is used in various areas such as medical, engineering,
basic science, etc. to find the optimal combination of
parameters, reduce the number of trials, process control
and product performance prediction. The tribological
behaviour of the aluminium composite reinforced with
B
4
C fabricated through the in-situ stir casting method
was studied through designing the experimental trials
with an Taguchi L27 orthogonal array. DoE was used to
find the optimal combination of parameter and the in-
fluence of the parameters.
24
From the brief literature survey it is clear that AMCs
are used in real-time applications, which requires wear
resistance and the addition of reinforcements in alumi-
nium matrix, and has paved the way for the enhancement
of wear resistance. The in-situ stir casting technique pro-
vides the fine and homogeneous distribution of rein-
forcements in the aluminium matrix in a cost-effective
mode. In this paper AA 8011- ZrB
2
(0, 4 and 8) % is
synthesized through the in-situ stir-casting technique and
the synthesized materials are involved in X-ray
diffraction (XRD), scanning electron microscope (SEM)
and energy-dispersive spectroscopy (EDS) to study the
presence and distribution of the ZrB
2
particles. The
dry-sliding wear behaviour of the materials was
investigated by conducting a pin-on-disc wear test based
on the experimental plan designed through the Taguchi
technique and the significance and influence of the
parameters on wear behaviour of the material was
identified with the help of ANOVA.
2 EXPERIMENTAL PART
2.1 Fabrication of materials
The in-situ stir-casting technique was carried out to
reinforce the ZrB
2
in the AA8011 alloy, whose chemical
composition is given in Table 1. Halide salts of K
2
ZrF
6
and KBF
4
were taken to obtain the required composite
proportions of weight percentage as per the litera-
ture
14,15,16,25
mixed and pre-heated at the temperature of
250 °C for 30 min to remove the moisture. The pre-
weighed AA8011 matrix was melted in the graphite
crucible by using electrical resistance furnace and it was
maintained at 850 °C to convert it to molten form. The
in-situ stir-casting process involves the addition of halide
salts, i.e., K
2
ZrF
6
and KBF
4
, in molten form of alumi-
nium to develop the ZrB
2
particles. The mass of salts to
be added in the melt has been calculated as per the
stoichiometric ratio given in Table 2 to form composites
AA8011 - 4 % of mass fractions of ZrB
2
and AA8011 -
8 % of mass fractions of ZrB
2
. Stirring is done in every
5 min by using graphite rod, for maintaining the
homogenous mixture of the halide salts in AA8011. The
time allowed for completion of the reaction is 30 min.
The process parameters such as melting temperature,
time for in-situ reaction, temperature maintained for
removing moistures of halide salts and pre heating of
permanent cast mould were decided through literature
reviews.
14–18
The exothermic reactions that take place
between molten form of aluminium and halide salts are
shown in Equation (1), (2) and (3). After the completion
of reaction, elements other than the ZrB
2
were evapo-
rated or formed as slag was removed. The molten form
of AA8011 was poured into the 250 °C pre-heated
permanent cast iron mould and then it was formed to the
desired shape and dimensions. The same procedure was
followed for the fabrication of both AA8011 - 4%o f
mass fractions of ZrB
2
and AA8011 - 8 % of mass frac-
tions of ZrB
2
composites. The AA8011 without ZrB
2
is
also studied to compare the wear behaviour of the
AA8011 alloy and the fabricated composites.
3K
2
ZrF
6
+ 13Al  3Al
3
Zr+2K
3
AlF
6
+ 2AlF
3
(1)
6KBF
4
+ 9Al  3AlB
2
+2K
3
AlF
6
+ 4AlF
3
(2)
AlB
2
+Al
3
Zr  ZrB
2
+ 4Al (3)
B. M. M. SELVAN et al.: INVESTIGATION OF TRIBOLOGICAL BEHAVIOR OF AA8011-ZrB2 IN-SITU ...
452 Materiali in tehnologije / Materials and technology 52 (2018) 4, 451–457

Fabricated as-casted aluminium samples were
investigated using a RINGKU XRD machine for x-ray
diffraction analysis to confirm the presence of the in-situ
formed ZrB
2
and AA8011 alloy. The samples were
polished in different grade sheets as per the standard and
etched with the Kellers etchant. Further, the presence and
the distribution of the reinforcements over the matrix
was explored with the scanning electron microscopic
analysis along with the elemental analysis on the
composites using a HITACHI SU 3000 SEM machine.
Table 1: Chemical composition of AA8011 alloy in percentage
Si Fe Cu Mn Mg Cr Zn Ti Al
0.6 0.7 0.25 0.15 0.9 0.2 0.25 0.15 Remaining
Table 2: Quantity of halide salts added for obtaining various compo-
sitions of materials.
Material Composition
Quantity of powder added (g)
K 2ZrF
6 KBF
4
AA8011 0 0
AA8011 - 4 w/% ZrB 2
100.45 200.90
AA8011 - 8 w/% ZrB 2
89.25 171.50
2.2 Wear testing
The tribological behaviours of materials were studied
by conducting a dry-sliding wear test through the
pin-on-disc method was carried out in DUCOM wear
testing machine strictly followed by ASTM: G99 stand-
ards. Based on the literature
4,20,21,24
the selected para-
meters are: Sliding distance (m), Reinforcement (%),
Temperature (°C), Load (N) and Sliding velocity (m/s).
A Taguchi orthogonal array was used to optimize the
number of experiments to be conducted. L18 was
selected as the orthogonal array. The sliding distance was
varied in two levels and the other four parameters are
varied in 3 levels as shown in Table 3. The as-casted
materials were machined to 8 mm diameter and 31 mm
length. Based on earlier literature D3 steel with hardness
of 63 HRC was selected as the counterpart.
4
To make the
perfect contact between the pin and the counterpart, the
face of the pins are polished to maintain the surface
roughness of 1μm. For each experiment the samples are
cleaned with acetone and weighed in the electronic
weighing balance to an accuracy of 0.0001 g. To improve
the accuracy of the readings, each trial was carried out 3
times and the average was taken. The wear rates for the
samples were calculated through the formula given in
equation (4) and the values are tabulated in Table 3.
Wear rate
mm
m
Mass loss Density
Sliding dist
3
⎛ ⎝ ⎜ ⎞ ⎠ ⎟ =
ance
⎛ ⎝ ⎜ ⎞ ⎠ ⎟ (4)
B. M. M. SELVAN et al.: INVESTIGATION OF TRIBOLOGICAL BEHAVIOR OF AA8011-ZrB2 IN-SITU ...
Materiali in tehnologije / Materials and technology 52 (2018) 4, 451–457 453
Table 3: Experimental results for the wear rate
Expt.
No.
Sliding distance
(m)
Reinforcement
(w/%)
Temperature
(°C)
Load
(N)
Sliding velocity
(m/s)
Wear rate
(mm
3
/m)
S/N ratio
1 1000 0 35 10 1 0.003620 48.8258
2 1000 0 100 20 1.5 0.003282 49.6772
3 1000 0 200 30 2 0.003925 48.1232
4 1000 4 35 10 1.5 0.002843 50.9245
5 1000 4 100 20 2 0.003105 50.1588
6 1000 4 200 30 1 0.005046 45.9411
7 1000 8 35 20 1 0.006620 45.0053
8 1000 8 100 30 1.5 0.007976 43.1279
9 1000 8 200 10 2 0.003171 49.9761
10 1500 0 35 30 2 0.003090 50.2008
11 1500 0 100 10 1 0.002165 53.2908
12 1500 0 200 20 1.5 0.002571 51.798
13 1500 4 35 20 2 0.002264 52.9025
14 1500 4 100 30 1 0.003084 50.2177
15 1500 4 200 10 1.5 0.002070 53.6806
16 1500 8 35 30 1.5 0.004666 46.6211
17 1500 8 100 10 2 0.002711 51.3374
18 1500 8 200 20 1 0.004330 47.2702
Figure 1: X-Ray diffraction results of the as-cast AA8011 and com-
posites

3. RESULTS AND DISCUSSION
3.1 X-ray diffraction (XRD) analysis
The fabricated materials are exposed to X-Ray
diffraction analysis to ensure the presence of ZrB
2
.
Figure 1 clearly indicates the peaks equivalent to ZrB
2
,
which confirms the presence of ZrB
2
in the AA8011 -
4 % of mass fractions of ZrB
2
and AA8011 - 8%o f
mass fractions of ZrB
2
. No other significant peaks were
observed in the analysis.
3.2 Micro-structural analysis
Based on the SEM images obtained as shown in
Figures 2b and 2c, it is evident that synthesized alu-
minium composites do not show any sign of common
B. M. M. SELVAN et al.: INVESTIGATION OF TRIBOLOGICAL BEHAVIOR OF AA8011-ZrB2 IN-SITU ...
454 Materiali in tehnologije / Materials and technology 52 (2018) 4, 451–457
Figure 2: SEM images of: a) AA8011, b) AA8011 - 4 % of mass fractions of ZrB
2
, c) AA8011 - 8 % of mass fractions of ZrB
2
, d) magnified
SEM image of ZrB
2
. Elemental mapping of magnified ZrB
2
, e) aluminium, f) zirconium, g) boride, h) EDS spectrum of Figure 2d

casting defects that include porosity, shrinkages, slag
inclusions, etc. The density of the ZrB
2
particles in Fig-
ure 2c is more than Figure 2b, which infers that the
presence of ZrB
2
in the AA8011 - 4 % of mass fractions
of ZrB
2
is more than the AA8011 - 8 % of mass fractions
of ZrB
2
. The energy-dispersive spectroscopy and the
elemental mapping shown in Figures 2h, 2e, 2f and 2g
confirms the presence of ZrB
2
in the aluminium matrix
and the corresponding elemental analysis is given in
Table 4. ZrB
2
distribution along the matrix is found to be
homogeneous and even along the grain boundaries and
the interface bond between the matrix and reinforcement
has a higher strength, which tends to improve the
mechanical and tribological properties of aluminium
metal matrix composites. The density difference between
the aluminium matrix and ceramics particles directs the
properties of solidification and the homogeneous distri-
bution of ceramic particles in an aluminium matrix. If
the density of the ceramic particles is greater by 2 g/cm
3
than the matrix material, then the ceramic particle will
suspend in the molten aluminium for long time, and this
leads to the homogeneous distribution of ceramic parti-
cles in an aluminium matrix. In this study, the difference
between the ZrB
2
particle and AA8011 matrix is ob-
served to be greater than 2 g/cm
3
. Due to the wetting
action between the molten aluminium and ZrB
2
particles,
the free movement of ZrB
2
gets retarded and makes the
ceramic particle suspend for a greater time in the molten
aluminium.
25
As mentioned in the earlier literature
surveys, this work depicts the fabrication of composites
through the in-situ stir-casting technique. The fabricated
composites exhibit a homogeneous distribution of rein-
forcements in the matrix and provide a clear interfacial
bond between the matrix and reinforcements.
4,14,15,17
Table 4: Elemental analysis of energy-dispersive spectroscopy
Element Weight (%) Atomic (%)
Al K 73.85 90.09
Zr L 25.67 9.26
Mg K 0.48 0.64
Total 100.00 100.00
3.3 Statistical analysis
In this work the Taguchi method was used to convert
the objective function to the signal-to-noise (S/N) ratio,
which is a quality characteristic. The wear rate is the ob-
jective function and "lower the better" quality characte-
ristics was selected to minimize the objective function.
3.3.1 Analysis of factors
MINITAB-16 is used to calculate the signal-to-noise
(S/N) ratio values for all the wear rates of the experiment
trials in Table 3 to analyse and to find which factors are
influencing the wear rate. The most influencing factors
are determined by the corresponding delta values of the
factors calculated through the S/N ratios. The most
influencing factors for wear rate are load, followed by
the reinforcement, sliding distance, sliding velocity and
temperature, given in the Table 5. The influence of the
temperature is negligible. The optimal condition to
obtain the minimum wear rate is a higher level of sliding
distance (1500 m), middle level of reinforcement (4 %),
high level of temperature (200 °C), lower level of load
(10 N) and higher level of sliding velocity (2 m/s)
observed from the main effect plot Figure 3.
The optimal combination of parameters obtained
from the main effect plot is not found in the L18
orthogonal array design, so separately the experiment
was carried out and the wear track is examined through
the SEM. From Figure 4a, the wear track of the optimal
combination of parameter has the smooth track which
does not contain many cracks, debris, delamination and
deeper grooves. The worst wear rate is observed for the
AA8011 - 8 % ZrB
2
from the readings of Table 3, with
the experimental parameters of load 30 N, sliding
velocity 1.5 m/s, temperature 100 °C and sliding distance
1000 m and it was observed by the SEM, which shows
many cracks, debris, micro ploughing, delamination and
deeper grooves on its morphology, as shown in Figure
4b, these mechanisms causes the severe plastic defor-
mation.
26,27
From Figure 3, the wear rate decreases with
B. M. M. SELVAN et al.: INVESTIGATION OF TRIBOLOGICAL BEHAVIOR OF AA8011-ZrB2 IN-SITU ...
Materiali in tehnologije / Materials and technology 52 (2018) 4, 451–457 455
Figure 3: Main-effect plot for the wear rate
Table 5: Response table for wear rate (smaller is better)
Level Sliding distance (m) Reinforcement (w/%) Temperature (°C) Load (N) Sliding velocity (m/s)
1 47.97 50.32 49.08 51.34 48.43
2 50.81 50.64 49.63 49.47 49.30
3 - 47.22 49.46 47.37 50.45
Delta 2.84 3.41 0.55 3.97 2.02
Rank 32514

the increase of sliding distance, at the 1000 m the wear
rate is higher because the asperities which make contact
with the aluminium samples are sharp and this initiates
the crack. At the sliding distance of 1500 m as the
distance increases, over the time asperities got com-
pacted and blunt between the pin and the counterpart.
24
When the percentage of ZrB
2
increases the wear rate also
increases, because the co-efficient of thermal expansion
of ZrB
2
is more than the aluminium matrix, so this
difference leads to an increase in the density of the
dislocations during the solidification.
14,15
But the increase
in the reinforcement is not linear with the decrease in the
wear rate because the AA8011 - 4 % ZrB
2
shows better
wear resistance than the AA8011 - 8 % of mass fractions
of ZrB
2
, which may be attributed to the occurrence of
complex processes during the wear of the material.
4
When the temperature and the sliding speed increases the
wear rate is decreased, as confirmed in the SEM image
in Figure 4a, because the pin gets softer due to the
formation of the thin molten layer at the asperity
contacts, which is called the mechanical mixed layer
(MML). It acts as a thin layer between the counterpart
and pin. MML hardness is six times greater than the bulk
composite.
20
When the load increases, the wear rate
increases, which is indicated in Figure 4b.
15,23
The
increase in the pressure and the contact between the pin
and the counterpart leads to an increase in the frictional
heat. The frictional heat between them causes the
softening of the pin, which allows the asperities to easily
enter into the material. This entry of asperities into the
material triggers more wear rate, paves the way to
mechanisms such as micro-ploughing, fracture,
deformation and fragmentation.
15
3.3.2 ANOVA analysis
ANOVA is a statistical tool used to find the most
significant factors influencing the response. The analysis
of the variance for the S/N ratios of the wear rate is given
in the Table 6, which has the convincing R-sq. value of
96.48 %. The probability, given in the seventh column of
Table 6, decides the influence of factors on the response.
The factors which has probability less than 0.005 are the
significant factors influencing the response. Sliding
distance (m), reinforcement (w/%) and load (N) are the
factors that have a more significant influence on the wear
rate. Sliding velocity (m/s) and temperature (°C) failed
to make any significant and influence on the wear rate.
Especially temperature shows very small influence on
the response.
3.3.3 Confirmation test
A confirmation experiment was conducted based on
the optimal combination of parameter and obtained a
wear rate of 0.000629 mm
3
/m. To verify the accuracy of
the experimental result, the wear rate for the optimal
combination of parameter was also predicted as
0.0006033 mm
3
/m with the Taguchi analysis using
MINITAB-16 statistical analysis software. A minimal
error of 4.25% was obtained while comparing the
B. M. M. SELVAN et al.: INVESTIGATION OF TRIBOLOGICAL BEHAVIOR OF AA8011-ZrB2 IN-SITU ...
456 Materiali in tehnologije / Materials and technology 52 (2018) 4, 451–457
Table 6: Analysis of variance for the S/N ratios of the wear rate
Source Df
a
Seq SS
b
Adj SS
c
Adj MS
d
FP
e
Sliding distance (m) 1 36.293 36.293 36.293 57.02 0.000
Reinforcement (w/%) 2 42.695 42.695 21.347 33.54 0.000
Temperature (°C) 2 0.970 0.970 0.485 0.84 0.498
Load (N) 2 47.268 47.268 23.634 37.13 0.000
Sliding velocity (m/s) 2 12.368 12.368 6.184 9.72 0.007
Error 8 5.092 5.092 0.637
Total 17 144.686
S = 0.797822, R-Sq = 96.48 % and R-Sq (adj) = 92.52 %
a
Degree of freedom,
b
Sequential sum of squares,
c
Adjusted sum of squares,
d
Adjusted mean squares,
e
Probability
Figure 4: Wear track for: a) composite of AA8011+4%m a s s
fraction of ZrB
2
after sliding for 1500 m at a 10 N load, 2 m/s sliding
velocity and 200 °C temperature b) composite of AA8011+8%mass
fraction of ZrB
2
after sliding for 1000 m at a 30 N load, 1.5 m/s
sliding velocity and 100 °C temperature

predicted and experimental value, which validates the
experimental results.
4 CONCLUSIONS
The AA8011-ZrB
2
has been successfully fabricated
through an in-situ stir-casting method.
• The presence of ZrB
2
particles has been confirmed by
XRD analysis.
• SEM analysis along with energy-dispersive spectros-
copy analysis shows the presence of ZrB
2
and its
uniform distribution over the matrix material.
• The main effect plot for wear rate, the optimal
combination of parameter for obtaining minimum
wear rate was identified as 1500 m sliding distance,
4 % of reinforcement, 200 °C temperature, 10 N load
and 2 m/s sliding velocity.
From the ANOVA analysis the sliding distance (m),
reinforcement (w/%) and load (N) were identified as
significant factors influencing the wear rate.
• The confirmation test was carried out based on the
optimal combination of parameters, the experimental
wear rate was at a close range, with the predicted
value having a minimal error of 4.25 %.
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D. B. Miracle, S. L. Donaldson, ASM Handbook for Composites,
ASM International, Materials Park, OH, USA, 2001, 1
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B. M. M. SELVAN et al.: INVESTIGATION OF TRIBOLOGICAL BEHAVIOR OF AA8011-ZrB2 IN-SITU ...
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