International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 3 - September 2015
Wear characteristics of Mg/Tip composites manufactured
through Powder Metallurgy techniques
M.Appoothiadigal1, B.K.Raghunath
1
1. Assistant professors in Manufacturing Engineering, Annamalai University,
Annamalai Nagar, Tamilnadu, India
Abstract- Magnesium (Mg) and Titanium (Ti) alloy is
one of the high potential materials to be effective to
weight reduction because of its low density and high
specific mechanical properties. Magnesium based
materials also exhibit good damping characteristics,
dimensional stability, machinability, and low casting
costs. Despite these advantages, magnesium based
composites normally exhibit limited ductility at room
temperature. The experiment is conducted on pin-ondisc wear tester with different normal load, speed
and distance. The result reveals that the
Mg/Tip
composite have mild wear at the normal load of 15 N
with the speed of 150rpm and at distance of 1000mm.
The wear has been increased with the increasing
load and with increasing speed and distance. Micro
structural analysis is carried out to confirm the test
result.
Keywords: metal matrix composites, wear, wear
parameters, Mg/Ti Composites.
I.INTRODUCTION
Composites have been considered as an
important engineering material for potential
applications in various industries from the days of
their inception. During the last several decades,
extensive research has shown tremendous promise of
Metal Matrix Composites (MMCs) and a large
number of conventional and innovative fabrication
techniques have been developed to engineering
composites for a diverse field of applications [1-4].
Magnesium alloys have been increasingly
used in the automotive industry and aircraft industry
in recent years due to their lightweight and has fuel
consumption. The density of magnesium is
approximately two thirds of that of aluminum, one
quarter of zinc, and one fifth of steel. As a result,
magnesium alloys offer very high specific strength
among conventional engineering alloys. In addition,
ISSN: 2231-5381
magnesium alloys possess good damping capacity,
excellent castability, and superior machinability.
Accordingly, magnesium casting production has
experienced an annual growth of between 10 and
20% over the past decades and is expected to
continue at this rate[5-7]. Their applications are
usually limited to temperatures of up to 120◦C.
Further improvement in the high-temperature
mechanical properties of magnesium alloys will
greatly expand their industrial applications.
Titanium particulate (Tip) is used as
reinforcement. It has a high strength, high hardness,
low coefficient of thermal expansion and density
which when reinforced with metal alloys make them
highly attractive materials and meet the demands in a
range of engineering applications[8]. There have
been several methods to produce the metal matrix
composites; powder metallurgy, stir casting,
disintegrated metal deposition (DMD), melt
infiltration, etc. Among the various metalworking
technologies, powder metallurgy (P/M) is the most
diverse manufacturing approach. One attraction of
P/M is the ability to fabricate high quality, complex
parts to close tolerances in an economical manner. In
essence, P/M takes a metal powder with specific
attributes of size, shape, and packing, and then
converts it into a strong, precise, high performance
shape and less prone to porosity and defects. [9]
The aim of the present investigation is to
synthesize Mg/Tip composites using blend powder
metallurgy (P/M) technique. Magnesium composite
have a potential for enhanced wear resistance over
the Mg alloy. Proper selection of the wear test
parameters can yield the best performance with a
particular wear test setup, hence statistical models
have been developed using response surface
methodology based on experimental results
considering the machining parameters, viz., Load (P)
Speed (N) and Sliding distance (D) as independent
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International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 3 - September 2015
variables. Finally, an attempt has been made to obtain
optimum machining conditions with respect to each
of the wear parameters considered in the present
study with the help of response surface methodology
II.EXPERIMENTAL PROCEDURE
2.1. Materials
Matrix material used in this study is pure
magnesium powder with an average particle size of
45 microns. Ti particulates with an average size of
45microns are used as reinforcement.
2.3Hardness
Micro hardness measurements are made on the
polished Mg/Tip metal matrix composites using a
constant load of 40 kg for 10 sec. Five measurements
have taken and the average has been taken as
hardness of each sample.
2.4. Pin-on-Disc Wear Tester
The experiment is conducted on pin-on-disc
wear tester. The schematic diagram of the pin-on-disc
tester is presented in Fig (1). The disc of the
polishing machine is made of AISI-01 tool-steel, oil
hardened to 63HRC, 250mm
Fig 1: Hydraulic hot press
Fig 2: Pin on Disc wear tester
2.2. Specimen preparation
To obtain the powder mixture, the pure Mg
and 4% Ti powders are introduced together into high
energy planetary ball mill operating at a rotational
speed of 300 rpm with a mixing time of 90 minutes.
The purpose of this step is to mix powders without
changing their original characteristics. The
conventionally mixed powders are consolidated by
cold pressing followed by sintering and hot extrusion.
Cold pressing is carried out in cylindrical die using
uniaxial press with 500Mpa pressure with zinc as the
binder. Sintering is carried out at 5500C with a
soaking time of 120 min under controlled
atmosphere.
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dia and weight 5.25kg. A pin holder is used to secure
the pin during sliding.
2.5. Design of Experiment
The main objective of the experimental
design is to studying the relationship between the
response as a dependent variable and the various
parameter levels. It provides a prospect to study not
only the individual effects of each factor but also
their interactions. The design of experiments for
exploring the influence of various predominant wear
test process parameters as load and speed on the wear
characteristics such as wear rate is modeled. In the
present work experiments are designed on the basis
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International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 3 - September 2015
of experimental design technique using response
surface design method.
Std order
In the present study these are selected as
design factors while other parameters have been
assumed to be constant over the experimental
domain. The upper and lower limits of a factor are
coded as +1 and -1 respectively, the coded value
being calculated from the following relationships:
(1)
Where
is the required coded value of a
variable x.The process variables / design factors with
their values on different levels are listed in Table 1.
The selection of the values of the variables is limited
by the capacity of the machine used in the
experimentation as well as the recommended
specifications. Table 2 shows the experimental matrix
composite design employed in the present study.
2.6. Wear test procedure and their corresponding
levels
A cylindrical pin of size 10mm diameter and
40mm length are prepared for all compositions of
Mg/TiP composite material and after that tested on
the Pin on Disc apparatus.. Before testing the surface
of the all specimens is polished to ensure the flatness
with the help of 1000 grit paper. All the tests are
carried out at the room temperature. These tests are
carried out at different speeds (150rpm, 300rpm,
450rpm) ,various normal load (15N,30N,45N) and
sliding distance (1000mm, 2000mm, 3000mm)
conditions.
Wear rate can be calculated by the formula: WR=
(w1-w2)/2πrnt
Wear test
Parameters
Units
Speed
Load
Sliding
distance
rpm
N
mm
Symbol
N
P
D
Levels
-1
0
1
150
15
1000
300
30
2000
450
45
3000
Run
Order
Speed
(rpm)
Load
(N)
Sliding
Distance
(mm)
1
7
150
45
3000
2
12
300
45
2000
3
14
300
30
3000
4
4
450
45
1000
5
6
450
15
3000
6
11
300
15
2000
7
10
450
30
2000
8
17
300
30
2000
9
18
300
30
2000
10
13
300
30
1000
11
19
300
30
2000
12
2
450
15
1000
13
15
300
30
2000
14
9
150
30
2000
15
20
300
30
2000
16
16
300
30
2000
17
1
150
15
1000
18
3
150
45
1000
19
5
150
15
3000
20
8
450
45
3000
[
Table2: Design Matrix
III.RESULT & DISCUSSION
3.1. Hardness
The
results
of
micro
hardness
measurements, as provided in Table3, show that the
presence of TiP reinforcement led to a significant
increase in micro hardness of magnesium composites.
This can be attributed primarily to the presence of
relatively harder titanium particulates in the matrix,
their strong resistance on the soft magnesium matrix
for any indentation, and finally a reduced grain size.
It was found that pure Mg was hardness of 35Hv and
also measured that the Mg/4%TiP was obtained
hardness of 40Hv. It was found that addition of 4%
Ti was increasing their hardness of 14.28 %.
Specimen
Mg/4%TiP
Mg
1
41
35
Micro Hardness (Hv)
2
3
4
5 Avg
40 39 40 40 40
36 34 34 36 35
Table 1: wear test parameter and their levels
Table 3: Micro hardness of Mg/4%Tip composites
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International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 3 - September 2015
3.2. Effect of Process parameters in wear rate
0.0001
150
300
300
450
450
300
450
300
300
300
300
450
300
150
300
300
150
150
150
45
45
30
45
15
15
30
30
30
30
30
15
30
30
30
30
15
45
15
3000
2000
3000
1000
3000
2000
2000
2000
2000
1000
2000
1000
2000
2000
2000
2000
1000
1000
3000
Wear(gm)
0.0012
0.0014
0.0013
0.0018
0.0011
0.0005
0.0014
0.0012
0.0012
0.0011
0.0012
0.0006
0.0012
0.0007
0.0012
0.0012
0.0001
0.0009
0.0004
450
45
3000
0.0024
Actual Factor
A: Speed = 300
0.0001
Actual Factor
B: Load = 30
0.002
0.0015
0.001
0.0005
0
45
450
39
390
33
330
27
B: Load (N)
270
21
210
15 150
Fig 3 Speed, Load Vs Wear
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3000
A: Speed (rpm)
45
39
2500
33
2000
C: Sliding Distance (mm)
27
1500
B: Load (N)
21
1000
15
Fig 4 Load, Sliding distance Vs Wear
0.0001
0.0025
W e a r (g m )
Actual Factor
C: Sliding Distance = 2000
0.001
0.0005
0
0.0025
X1 = A: Speed
X2 = C: Sliding Distance
Wear test conducted on 15 specimens at
different conditions as given in Table2 and
measurements of wear is given in Table 4.
X1 = A: Speed
X2 = B: Load
0.002
0.0015
Design-Expert® Software
Factor Coding: Actual
Wear (gm)
Design points above predicted value
Design points below predicted value
0.0024
Table 4: Measurement of wear of Mg/Tip composites
Design-Expert® Software
Factor Coding: Actual
Wear (gm)
Design points above predicted value
Design points below predicted value
0.0024
0.0025
X1 = B: Load
X2 = C: Sliding Distance
W e a r (g m )
Sliding
distance(mm)
0.002
W e a r (g m )
Load(N)
Speed(rpm)
Design-Expert® Software
Factor Coding: Actual
Wear (gm)
Design points above predicted value
Design points below predicted value
0.0024
0.0015
0.001
0.0005
0
3000
450
390
2500
330
2000
C: Sliding Distance (mm)
270
1500
A: Speed (rpm)
210
1000
150
Fig 5 Speed, Sliding distance Vs Wear
The influences of speed and load on the
wear rate are shown in Fig 3. The wear reaches its
minimum of 0.0001 gm at the lowest speed of
150rpm, minimum load of 15N and at distance of
1000mm respectively. Similarly the maximum wear
rate of 0.0024gm attained at speed of 450 rpm with
load of 45 N and distance of 3000mm. The influences
of the wear rate parameters (speed, load, distance) on
the response variables selected have been assessed
for Titanium particles. The second order model was
postulated in obtaining the relationship between the
wear rate and the process variables. The analysis of
variance (ANOVA) was used to check the adequacy
of the second order model. The second order
response surface equations have been fitted using the
equations can be given in terms of the coded values
of the independent variables as the following
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International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 3 - September 2015
rate was gradually increases. The gradual wear is
observed at low applied load, as the load increases
further the wear rate also increases for the speed of
300 and 450rpm.
3.3. Effect of speed on wear rate
3.5. Micro structural analysis
The SEM photos for the surface treated samples
before and after wear test done.
Fig 6: Effect of speed on wear rate
Fig 6 depicts influence of speed on wear rate
for various loads. The figure reveals that the speed
increases with speed for all loads corresponds to
variation in wear rate with the speed for the
magnesium/Titanium particles composites. The wear
rate of the composites increased as the speed
increases with increasing of speed, however the same
trend of increasing wear rate with increasing the
speed was observed in composites. A drastic increase
of wear rate was observed for unreinforced alloy
when the speed is increased from 150 rpm to 450.
Heavy noise and vibration was observed during the
process. The effect of Magnesium/Titanium
composite on the wear rate can be observed from
Fig.1. It is clear from the study that the wear rate
increases with increasing of speed.
3.4. Effect of load on wear rate
Fig 8 Microstructure of before wear test
Fig 9 Microstructure of after wear test
Fig 7 Effect of load on wear rate
Fig 7 indicates the dependence of wear rate on
the applied load for speed of 150,300,450rpm.
At the speed of 150rpm and the load of 15N to 30N
the wear rate was steeply increases, and with the
same speed and the load between 30 to 45N, the wear
ISSN: 2231-5381
It is observed that from Fig 8 titanium
particles are uniformly distributed in the matrix .A
few clustering of the reinforcement is observed in the
micrographs. It shows that there are some voids and
no discontinuities in the composites. There was a
good interfacial bonding between the titanium
particles and matrix materials.
Fig 9 has taken from the specimen involved
in wear test at min load of 15N, speed of 150 rpm and
distance of 1000mm. Mild wear has observed on the
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International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 3 - September 2015
surface, where at the high speed and max load, severe
wear experienced.
V. CONCLUSIONS
This experiment was carried to investigate
the influence of the speed and load on wear test of
Mg/TiP composites. The conclusions from the
analysis of this experimental interpretation can be
stipulated as follows.
 The micro hardness of Mg/Tip were attained
as 40Hv
 The wear rate reaches its minimum of
0.0001 gm at the lowest speed of 150rpm,
minimum load of 15N and at distance of
1000mm respectively.
 The maximum wear rate of 0.0024gm
attained at high speed of 450 rpm with
maximum load of 45 N and at distance of
3000mm.
The increasing wear rate for increasing speed is due
the destruction of surface caused with variation of
speed. The wear debris coming out of rubbing surface
is responsible for increasing material loss.
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