Mechanical and tribological properties of Ni-based alloy/CeF3/graphite high temperature self-lubricating composites

In this paper, Ni-based alloy/CeF3/graphite high temperature self-lubricating composites with different graphite addition amounts (0, 1, 3 and 5 wt.%) were prepared using P/M (powder metallurgy) method. Findings indicated that the addition of graphite could increase the compressive strength and hardness of the composites, while poor results were obtained for the impact toughness at room temperature. The microstructures of the composites were studied using SEM with EDS and were correlated to their mechanical strengths with respect to the formation of carbides and graphite during the process. The effects of graphite addition amount on the friction and wear performances of the composites both at room temperature and 600°C in air in sliding against high speed steel (W18Cr4V) were investigated using a pin-on-disk high temperature tribometer. Results showed that the wear rates of the composites and their counterparts could be remarkably reduced at room temperature with graphite addition. As for 600°C, with no apparent improvement on wear resistance of the composites with graphite addition, the wear rate of high speed steel was higher than that with no graphite addition. Finally, the wear rate of high speed steel at 600°C was correlated to the hardness of the composites and the wear mechanism was discussed.