Graphene nanocrystallites induced short run-in period with low electric power at current-carrying sliding interface

We reported the current-carrying friction behavior of graphene nanocrystallites carbon (GNC) film, which had hybrid structure with graphene nanocrystallites embedded in amorphous carbon (a-C) matrix. The GNC film exhibited high electrical conductance of 7.7 ~ 30.9 S/cm for effective current transmission, and short run-in period of 10 ~ 25 frictional cycles for achieving low friction (μ = 0.03 ~ 0.05) with low electric power of 0.25 ~ 0.60 W under the electric current of 0.5 A. As a comparison, a-C film showed low electrical conductance of 3.2 S/cm and long run-in period of 50 frictional cycles with high electric power of 1.25 W. The high electrical conductance and the short run-in period effectively reduce the electrical and mechanical energy consumption for the GNC film, thus presenting wider promising practical applications. Based on the nanostructure characterization, the role of graphene nanocrystallites was summarized as the electron transport channels for transmitting the electric current and the source of graphene nanocrystallite structure for promoting the low friction interface formation. These findings present potentials of the GNC film in protecting the current-carrying friction interface.