Superlubric Polycrystalline Graphene Interfaces

Abstract

The effect of corrugated grain boundaries on the frictional properties of extended graphitic contacts incorporating a polycrystalline surface are investigated. The friction is found to be dominated by shear induced buckling and unbuckling of corrugated grain boundary dislocations, leading to a nonmonotonic behavior of friction with normal load and temperature. The underlying mechanism involves two competing effects, where an increase of dislocation buckling probability is accompanied by a decrease of the dissipated energy per buckling event. These effects are well captured by a phenomenological two-state model, that allows for characterizing the tribological properties of any large-scale polycrystalline layered interface, while circumventing the need for demanding atomistic simulations. The resulting negative differential friction coefficients obtained in the high-load regime can reduce the expected linear scaling of grain-boundary friction with surface area and restore structural superlubricity at increasing length-scales.

A review of advances in tribology in 2020–2021

“…These results have important implications for understanding and improving the wear resistance of SL-MoS 2 with GB defects. Gao et al [972] investigated the effect of corrugated GB on the tribological properties of extended planar graphite contacts containing polycrystalline surfaces through molecular dynamics simulations. It is found that dynamic friction is mainly affected by shear-induced buckling and debuckling of corrugated GB dislocations, resulting in non-monotonic behavior of friction under normal loads and temperatures.…”