Superlubric polycrystalline graphene interfaces

This research investigates the frictional properties of extended planar graphitic contacts with polycrystalline surfaces using molecular dynamics simulations. The simulations reveal that kinetic friction is primarily determined by shear-induced buckling and unbuckling of corrugated grain boundary dislocations, resulting in a non-monotonic relationship between friction and normal load/temperature. A phenomenological two-state model effectively captures these effects, enabling the characterization of tribological properties in large-scale polycrystalline layered interfaces without extensive atomistic simulations. The observed negative differential friction coefficients at high loads can mitigate the typical linear scaling of grain-boundary friction with surface area, potentially restoring superlubricity at larger length scales.

Xiang Gao, Wengen Ouyang, Michael Urbakh, Oded Hod