Synergistic lubrication mechanisms of molybdenum disulfide film under graphene-oil lubricated conditions

Single solid or liquid lubricant cannot meet the ever-increasing lubricating performance of mechanical motion under extreme operating conditions. Solid-liquid synergistic lubrication could effectively solve the friction and wear problems due to the cooperation of solid and liquid lubricant. Herein, the solid–liquid composite coating was prepared via molybdenum disulfide (MoS2) film under graphene hybrid gear oil lubrication conditions. Its anti-friction and anti-wear abilities were reduced by 13.0% and 37.4% compared with gear oil lubricated MoS2 film, and 46.7% and 97.1% lower than those of only MoS2 film, respectively. More importantly, the graphene-like transfer film at frictional contact interfaces was formed. Hence, the excellent lubrication function of MoS2-based solid–liquid lubricating coating was attributed to not only the structural advantages of MoS2 and graphene, but also the solid–liquid synergism and transfer film, thereby enhancing the interfacial load-bearing capacity and anti-friction/wear behaviors.