Tribological properties of Si3N4–graphene nanocomposites

Mechanical and tribological properties of nanocomposites with silicon nitride matrix with addition of 1 and 3 wt% of various types of graphene platelets were studied. The wear behavior was observed by means of the ball-on-disk technique with a silicon nitride ball used as the tribological counterpart at room temperature in dry sliding. Coefficient of friction and specific wear rates were calculated and related to the damage mechanisms observed in the wear tracks. The measured properties were then assessed with respect to the type and volume fraction of the graphene additives. It is shown that addition of such amounts of carbon phases does not lower the coefficient of friction. Graphene platelets seem to be integrated into the matrix very strongly and they do not participate in lubricating processes. The best performance offers materials with 3 wt% of larger sized graphene, which have the highest wear resistance.