An atomistic study of the abrasive wear and failure of graphene sheets when used as a solid lubricant and a comparison to diamond-like-carbon coatings

The failure mechanisms of graphene under nanoscale sliding conditions are examined using atomistic simulations to evaluate its use as a solid lubricant and to simultaneously answer principal questions regarding wear of lamellar films comprised of atomically-thin sheets. To determine the failure behavior of graphene and the impact of adhesion on wear and failure, an asperity is slid over a substrate-supported graphene film with various adhesion strengths. For a purely-repulsive asperity, the graphene never delaminates and lower substrate-membrane adhesion appears to reduce the overall damage to the graphene layer and permits the recovery of more of the load-bearing capability of the graphene post-tearing. When tri-layer graphene is benchmarked with a 2 nm repulsive asperity against an 86% sp3 content diamond-like-carbon (DLC) coating of the same thickness (1.0 nm), the graphene supports up to 8.5 times the normal load of DLC during indentation, and up to twice the normal load of DLC during sliding even after failure of one or more layers. The preliminary results indicate that graphene has promise as a solid lubricant with thickness on the order of nanometers due to its atomically-thin configuration and high load carrying capacity.