Self-Lubricating Metal Matrix Composites

This chapter addresses the tribology of carbon-based and MoS₂hBN/WS₂/CaF₂/BaF₂ self-lubricating metal matrix composites with special attention to the role of third bodies in determining the performance of the materials. For instance, under sliding conditions, the metal/graphite composite is self-lubricating because of the transfer layer of the graphite on the tribo-surfaces and then the formation of a thin layer of graphite, which prevents direct contact between the mating surfaces. Composite materials make use of more than one material class, with one acting as the matrix and the other as a reinforcing component. The dominant wear mechanism at low loads is abrasion due to the presence of grooves formed by the reinforcing particles on the worn surfaces of the composites along the sliding direction. The greatest disadvantage of embedding aluminum graphite composites is the low mechanical properties of self-lubricating composites reinforced by graphite. Excellent high-temperature performance of nickel–graphite composites makes some application of the composites for high-efficiency engine.