(192d) Atomistic Simulations of the Superlubricity between Graphene Nanoribbons and Au/Ag/Cu Surfaces

The state of extremely low friction, known as superlubricity, has very important applications to the development of various types of materials. Examples are materials that are invaluable to the goal of reducing energy loss in mechanical systems, and those in drivetrains with complex gearing and bearing systems, or in turbines. One such material is graphene that offers distinctive properties as a solid-state lubricant, and can potentially be used as a coating material on surfaces. A series of molecular dynamics simulations have been carried out to measure the friction force between a graphene layer and an opposing metal surface. We demonstrate superlubricity on a gold surface, but a higher friction force, though still small, for both silver and copper surfaces. The MD simulations are performed using a hybrid of AIREBO and EAM force fields, with the interaction of Au/Ag/Cu with graphene represented by the LJ parameters. By lifting the graphene layer a distance Z from the metal surface, a spring constant k can be calculated based on the deformation of the graphene layer. The spring constant is then used to determine the friction force between the opposing layers. Our simulations indicate that the average friction force for graphene on a gold surface is approximately 20 pN.