Graphene as a lubricant on Ag for electrical contact applications

The potential of graphene as a solid lubricant in sliding Ag-based electrical contacts has been investigated. Graphene was easily and quickly deposited by evaporating a few droplets of a commercial graphene solution in air. The addition of graphene reduced the friction coefficient in an Ag/Ag contact with a factor of similar to 10. The lubricating effect was maintained for more than 150,000 cycles in a pin-on-disk test at 1 N. A reduction in friction coefficient was also observed with other counter surfaces such as steel and W but the life time was strongly dependent on the materials combination. Ag/Ag contacts exhibited a significantly longer life time than steel/Ag and W/Ag contacts. The trend was explained by an increased affinity for metal-carbon bond formation.