Microstructure evolution and tribological performance of Cu-WS2 self-lubricating composites

Cu-WS2 self-lubricating composites containing various contents of WS2 were prepared by hot-pressing. The composite was also annealed at different temperatures to reveal the decomposition of WS2 during preparation. The influences of WS2 amount and annealing temperature on the phase, microstructure, hardness as well as friction and wear behaviors were investigated. The dry sliding wear of the composites against GCr15 steel ball was measured at the load of 10 N in atmosphere condition. The results revealed that the residual amount of WS2 decreased as the annealing temperature increased. The increase of hardness with the addition of WS2 was attributed to the interfacial reaction. Furthermore, the composite reinforced with 10 vol% WS2 exhibited a 71% reduction in the friction coefficient along with a promising 79% wear rate reduction, and an addition of 40 vol% WS2 resulted in even high wear resistance, with a 96% reduction in the wear rate. The tribological behavior of the composite was greatly influenced by the annealing temperature owing to the decomposition of WS2. Horizontal oriented WS2 sheets induced by friction were observed in tribolayer, and the related wear mechanism for the composites was discussed.