Tribological Investigation of Multilayer Graphene as Lithium Grease Additives

As an advanced antiwear and friction reducing material, graphene has been widely studied and applied in many fields. In this study, the tribological characteristics of lithium grease with multilayer graphene (MLG) additive were studied on a four-ball tester. The micro-morphologies and elemental distributions of the wear surfaces of steel balls were identified by FESEM and EDAX. The tribological properties of grease were obviously improved by MLG additive. When the content of MLG was 0.1 wt%, the improvement effect was the best. The coefficient of friction and the wear scar diameter (WSD) decreased by 22.6% and 9%, respectively, at 686 N and 1450 rpm as compared to the original lithium grease. Because of the layered structure of graphene along with its high strength and surface activity, a layer of lubricating film which was favorable for improving the anti-friction and anti-wear property of the friction pair was formed on the friction surface during the friction process.