Experimental investigation of lubricated rolling and sliding contact for three types of Si3N4against nodular cast iron reveal that additives to the Si3N4and processing methods affect wear rates and wear modes. The friction coefficient is governed by the contact type rather than by the material type. In rolling contact tests, grain pullout of Si3N4caused a higher wear rate than submicron chipping. In sliding tests, tungsten carbide particles added in the Si3N4matrix inhibit the wear by 50 percent. Schematic drawings of these wear processes are presented representing the wear modes in a stepwise manner.