Lubrication of Graphene Nanoplatelets (GNs) on Rough Gold

Lubrication employing graphene nanoplatelets has emerged as a critical topic in nano- and microtribology research, both as additives and as stand-alone solid lubricants. Nevertheless, simulation studies addressing the molecular dynamics of graphene nanoplatelets (GNs) remain scarce in the literature. This paper primarily investigates the lubrication effects of various graphene morphologies on rough gold substrates using atomistic simulations with a particular focus on elucidating the lubrication and wear mechanisms of graphene nanoplatelets. The frictional properties of monolayer graphene nanoplatelets are found to be intermediate between those of continuous monolayer graphene and those of a bare substrate. A pronounced friction transition─divisible into six distinct phases─is observed when the tip ascends and descends the graphene nanoplatelet. Furthermore, the lubrication performance is influenced by factors such as the arrangement state, sliding speed, applied pressure, and number of friction cycles. Notably, stacks comprising at least two layers of graphene nanoplatelets exhibit an enhanced friction reduction and wear resistance.