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A. Meher and M. M. Mahapatra
Fig. 3a, it is observed that the wear loss significantly increases with an increase in
applied load for a sliding distance of 1000 m. A similar trend is observed for a sliding
distance of 2000 m and a sliding distance of 3000 m as shown in Fig. 3c, e respectively. It is observed that materials from the contact surface of the test sample start
to deform plastically when the load is applied continuously to the test sample over
the rotating abrasive disc. As the load increases, the extent of plastic deformation
increases and at times resulting in subsurface cracking. Presence of ceramic reinforcement in the magnesium alloy inhibits the formation of one or more cracks and
resultant propagation [10]. In this case, by the addition of 10 wt.% TiB 2 reinforcement
to the magnesium alloy (RZ5) matrix, the wear loss experienced by the composite
material decreases by as much as 40–50 pct. As ceramic particles have high thermal
resistance, adding it to a soft metal matrix does contribute to enhancing the high heat
resistance properties, which in turn helps in decreasing the thermal wear experienced
by the materials. Presence of titanium diboride (TiB 2 ) particles having higher loadbearing capacity and resistance to plastic deformation, does help in contributing to
enhancing the wear resistance [29]. Mandal and co-workers observed that addition
of 10 wt.% TiB 2 to an aluminium matrix decreases the wear rate by as much as 30–
40 pct. when compared one-on-one with the unreinforced material for all loading
conditions. It was noticed that for both the unreinforced alloy and the metal matrix
composites, the variation of wear loss with an increase in load was not linear. Hence,
complex processes occur during wear, which can be easily be explored by analysing
morphology of the wear surface [30].
The coefficient of friction (COF) decreases marginally with an increase in applied
load. For the 10 N applied load, the coefficient of friction was found to be 0.513 and
0.418 for the magnesium alloy (RZ5) and magnesium alloy composite [RZ5/10 wt.%
TiB 2 ], respectively. For the 30 N load, it is found to be 0.470 and 0.391 as indicated
in Fig. 3b and for a sliding distance of 1000 m. A similar trend was observed for a
sliding distance of 2000 m and sliding distance of 3000 m as is shown in Fig. 3d,
f, respectively. Other researchers have noticed a similar trend for the coefficient of
friction by reinforcing boron nitride (BN) and titanium diboride (TiB 2 ) to magnesium
alloy matrix [24, 25]. It is observed that the RZ5/10 wt.% TiB 2 composite had a
lower coefficient of friction when compared to the magnesium alloy (RZ5) for the
same applied load condition. An increase in hardness of the chosen materials may
be a reason for the decrease in coefficient of friction. For the ceramic reinforced
composites, when the materials are exposed to the wear surface, the actual area of
contact decreases due to the presence of hard and essentially elastically deforming
ceramic particles. The tangential force acting on the pin surface decreases due to the
lesser area of contact. Hence, the coefficient of friction of the engineered composite
materials decreases in conformance with Eq. (1).
A. Meher and M. M. Mahapatra
Fig. 3a, it is observed that the wear loss significantly increases with an increase in
applied load for a sliding distance of 1000 m. A similar trend is observed for a sliding
distance of 2000 m and a sliding distance of 3000 m as shown in Fig. 3c, e respectively. It is observed that materials from the contact surface of the test sample start
to deform plastically when the load is applied continuously to the test sample over
the rotating abrasive disc. As the load increases, the extent of plastic deformation
increases and at times resulting in subsurface cracking. Presence of ceramic reinforcement in the magnesium alloy inhibits the formation of one or more cracks and
resultant propagation [10]. In this case, by the addition of 10 wt.% TiB 2 reinforcement
to the magnesium alloy (RZ5) matrix, the wear loss experienced by the composite
material decreases by as much as 40–50 pct. As ceramic particles have high thermal
resistance, adding it to a soft metal matrix does contribute to enhancing the high heat
resistance properties, which in turn helps in decreasing the thermal wear experienced
by the materials. Presence of titanium diboride (TiB 2 ) particles having higher loadbearing capacity and resistance to plastic deformation, does help in contributing to
enhancing the wear resistance [29]. Mandal and co-workers observed that addition
of 10 wt.% TiB 2 to an aluminium matrix decreases the wear rate by as much as 30–
40 pct. when compared one-on-one with the unreinforced material for all loading
conditions. It was noticed that for both the unreinforced alloy and the metal matrix
composites, the variation of wear loss with an increase in load was not linear. Hence,
complex processes occur during wear, which can be easily be explored by analysing
morphology of the wear surface [30].
The coefficient of friction (COF) decreases marginally with an increase in applied
load. For the 10 N applied load, the coefficient of friction was found to be 0.513 and
0.418 for the magnesium alloy (RZ5) and magnesium alloy composite [RZ5/10 wt.%
TiB 2 ], respectively. For the 30 N load, it is found to be 0.470 and 0.391 as indicated
in Fig. 3b and for a sliding distance of 1000 m. A similar trend was observed for a
sliding distance of 2000 m and sliding distance of 3000 m as is shown in Fig. 3d,
f, respectively. Other researchers have noticed a similar trend for the coefficient of
friction by reinforcing boron nitride (BN) and titanium diboride (TiB 2 ) to magnesium
alloy matrix [24, 25]. It is observed that the RZ5/10 wt.% TiB 2 composite had a
lower coefficient of friction when compared to the magnesium alloy (RZ5) for the
same applied load condition. An increase in hardness of the chosen materials may
be a reason for the decrease in coefficient of friction. For the ceramic reinforced
composites, when the materials are exposed to the wear surface, the actual area of
contact decreases due to the presence of hard and essentially elastically deforming
ceramic particles. The tangential force acting on the pin surface decreases due to the
lesser area of contact. Hence, the coefficient of friction of the engineered composite
materials decreases in conformance with Eq. (1).