▎ 摘　　要

In this study, the tribological behaviors of graphene as a lubricant additive for steel/copper and steel/steel friction pairs were compared. For the steel/copper friction pair, the graphene sheets remarkably decreased the coefficient of friction and wear scar depth under low loads, but these slightly increased under high loads. The steel/steel friction pair showed excellent tribological properties even under high loads. Severe plastic deformation on the copper surface reduced the stability of the graphene tribofilm because of a rough copper transfer film on the steel during the running-in period. The results provide a better understanding of the mechanism of graphene as a lubricant additive.