Tribological characteristics of graphene as grease additive under different contact forms

The tribological properties of graphene as grease additive were investigated under different contact forms and the worn surfaces were examined by X-ray photoelectron spectroscope (XPS) and Raman Spectrometer to reveal tribological mechanism. By the addition of graphene, the antiwear ability and friction reduction performance of grease were significantly improved. It is concluded that graphene can not only act as a deposition film to protect the substrate, but also stimulate formation of Fe2O3 and Li2O tribofilm. And the synergism of deposition film and tribo-chemical film significantly improve tribological properties of grease. In addition, the easy shear capability of graphene is prone to interlayer slip under the action of friction, thus decreasing the friction coefficient and promoting friction reduction performance of grease.