Synthesis and Characterization of Graphite-Nickel Composites
*Presenting author: nirav@ipr.res.in
Corresponding authors: * nirav@ipr.res.in; **pramod_bhingole@yahoo.com
Abstract:
This work investigates the synthesis and characterization of graphite-nickel composites for potential use as solid bearings in high temperature and high pressure tribological applications. Graphite has wide applications as a solid bearing material, however its poor wear resistance limits its use. To improve its mechanical and tribological properties, graphite can be reinforced with metal composites. In this study, high purity graphite powder of 10 microns was mixed with nickel powder of 20 microns using high energy ball milling, and powder samples of 70% graphite and 30% nickel (wt%) were prepared. The samples were then subjected to spark plasma sintering at 1000 ˚C and 40 MPa using the Gleeble® system. Pure graphite samples prepared using the same processing route were used for comparison. The resulting samples were characterized using XRD, SEM-EDS, and microhardness tests. The microstructure was analysed, and the area fraction was compared with the ratio of the powders mixed. The microstructure analysis showed that nickel was uniformly distributed in the graphite matrix. The average microhardness (under 0.01 Kg indentation load) of pure graphite was found to be 12 HV, while the microhardness of graphite in the Gr-Ni composite was 18 HV, and nickel particles in the matrix was 180 HV, comparable with the reported literature. The samples were also subjected to dry tribological studies using a pin-on-disc tribometer for 2000 m distance at 7 m/s sliding speed. The results showed a substantial increase in the wear resistance of the graphite-nickel composite samples. This study suggests that graphite-nickel composites synthesized via powder metallurgy route can improve the mechanical and tribological properties of pure graphite, making it suitable for high temperature tribological applications.