Improving the mechanical and tribological behavior of Cu-WS2 self-lubricating composite with the addition of WS2 nanosheet

Copper matrix self-lubricating composites (CMSCs) are commonly used as sliding contacts in aerospace craft for their good electrical conductivity and wear resistance. In efforts to further improve performance and prolong the service life of CMSCs, the effect of WS2 nanosheet addition ranging from 10 to 25 wt% on the mechanical and tribological properties of Cu-WS2 self-lubricating composites was analyzed in this work. The dry sliding wear of composites against beryllium copper counter discs was measured at the load of 1 N. The increase in WS2 nanosheet leads to a decline in the strength of Cu-WS2 composite, whereas it improves the tribological properties presented as the reduction of friction coefficients and wear rates. Compared to Cu-WS2 with submicron WS2 sheet, Cu-WS2 with WS2 nanosheet shows both improved mechanical and tribological properties. The wear rate of Cu-WS2 composite with 25 wt% WS2 nanosheets is 61.2% lower than that with 25 wt% submicron WS2 sheets. The addition of WS2 nanosheet reduces the size of WS2 agglomerates and generates finely dispersed WS2 particles in Cu-WS2 composites. It not only promotes lubrication film continuous and smooth, but also inhibits the initiation and propagation of cracks at the worn subsurface by improving the strength of Cu-WS2 composite.