Comparison of lubrication mechanism and friction behavior of graphene on stainless steel substrate at different scales

Graphene at both nano and macro scales reduces friction in stainless steel, but there are differences in the lubrication mechanisms of graphene at the two scales. In macroscopic friction, graphene achieves lubrication through the combined effect of low friction properties of the material itself and relative sliding at the friction interface. In nano-friction, the relative sliding of graphene at the friction interface does not occur, and the lubrication is realized only by the low friction property of graphene. In nano-friction, the bulge structure of graphene on a stainless-steel substrate causes a two-stage increase in friction. At the same time, friction strengthening behavior and stick–slip behavior occur in graphene during nano-friction.