12
A. Patil et al.
Wear Analysis
Figure 5 showing the CoF plots of the SPS processed pure nickel and Ni-Ti-C
composites indicate that the presence of titanium carbide and graphite phases in
these composites beneficially reduced the CoF and increased the wear resistance
of the Ni-Ti-C composite samples. The highest CoF value of ~0.61 is observed for
pure nickel. In contrast, the lowest CoF value of ~0.085 is observed for Ni-10Ti-10C
composite. The presence of unreacted graphite is evident in the SEM micrographs of
Ni-10Ti-10C composite, which was not expected since Ti and C content were in equal
proportion to form titanium carbide without any leftover excess graphite. Therefore,
the presence of both graphite and titanium carbide precipitates beneficially formed
a lubricant film on the surface, which remarkably improved the wear resistance.
Scanning electron microscopy micrograph of wear track of Ni-Ti-C composites is
shown in Fig. 6. The presence of grooves across the wear track indicates an abrasive
wear mechanism in these composites. Also, the formation of the lubricant layer is
observed on the wear track, indicating that the attrition of graphite has occurred due
to the sliding mechanism during the wear test, reducing the CoF. In Ni-5Ti-10C, a
higher CoF is observed, and a large volume of wear debris is seen on the wear track.
It can be attributed to the frictional heat generated during the sliding mechanism. The
second-lowest coefficient of friction value of ~0.2 was obtained for Ni-5Ti-20C and
exhibited the wear track width of ~106 µm, attributed to the high volume fraction
of graphite present in the sample, which is also evident from the SEM micrographs.
Fig. 5 Coefficient of friction versus distance profiles of pure nickel and Ni-Ti-C composites. (Color
figure online)
A. Patil et al.
Wear Analysis
Figure 5 showing the CoF plots of the SPS processed pure nickel and Ni-Ti-C
composites indicate that the presence of titanium carbide and graphite phases in
these composites beneficially reduced the CoF and increased the wear resistance
of the Ni-Ti-C composite samples. The highest CoF value of ~0.61 is observed for
pure nickel. In contrast, the lowest CoF value of ~0.085 is observed for Ni-10Ti-10C
composite. The presence of unreacted graphite is evident in the SEM micrographs of
Ni-10Ti-10C composite, which was not expected since Ti and C content were in equal
proportion to form titanium carbide without any leftover excess graphite. Therefore,
the presence of both graphite and titanium carbide precipitates beneficially formed
a lubricant film on the surface, which remarkably improved the wear resistance.
Scanning electron microscopy micrograph of wear track of Ni-Ti-C composites is
shown in Fig. 6. The presence of grooves across the wear track indicates an abrasive
wear mechanism in these composites. Also, the formation of the lubricant layer is
observed on the wear track, indicating that the attrition of graphite has occurred due
to the sliding mechanism during the wear test, reducing the CoF. In Ni-5Ti-10C, a
higher CoF is observed, and a large volume of wear debris is seen on the wear track.
It can be attributed to the frictional heat generated during the sliding mechanism. The
second-lowest coefficient of friction value of ~0.2 was obtained for Ni-5Ti-20C and
exhibited the wear track width of ~106 µm, attributed to the high volume fraction
of graphite present in the sample, which is also evident from the SEM micrographs.
Fig. 5 Coefficient of friction versus distance profiles of pure nickel and Ni-Ti-C composites. (Color
figure online)