Molecular dynamics simulation and experimental study on the lubrication of graphene additive films

Abstract

Friction between silicon nitride (Si 3 N 4 ) and bearing steel (GCr15) affects the hybrid bearing performance. The effects of graphene as an additive in n-hexadecane (C 16 H 34 ) lubricating oil on the lubricating properties of a Si 3 N 4 -GCr15 friction pair were studied. The effects of pressure and shear velocity on the coefficient of friction and friction force were probed experimentally, while the changes in the van der Waals energy, shear stress, and thickness of the solid film in the lubrication area were simulated by molecular dynamics methods. Graphene additives increased the van der Waals energy and thickness of the solid film in the lubrication region, while reducing the shear stress of the Si 3 N 4 -GCr15 friction pair, coefficient of friction, and friction force. Furthermore, the lower the overall shearing velocity, the lower was the van der Waals energy and shear stress, and the thicker was the solid film. Finally, as the pressure and shear velocity increased, graphene exerted a greater influence on the lubricating properties of the Si 3 N 4 -GCr15 friction pair.