Mechanical Performance and Tribological Behavior of WC-ZrO2 Composites with Different Content of Graphene Oxide Fabricated by Spark Plasma Sintering

This paper presents research on the effects of the addition of various contents of graphene oxide and sintering temperature on the mechanical, tribological, and electrical characteristics of WC-ZrO2 composites. Wet processing and spark plasma sintering provided dense samples with simultaneous reduction of graphene oxide (rGO) during sintering. The obtained results showed that the best mechanical properties were observed at a sintering temperature of 1700 °C in samples with 0.5 vol.% rGO content; namely, indentation fracture toughness (5.8 ± 0.4 MPa·m1/2) and flexural strength (872 ± 43 MPa) increased by 9% and 24.3% compared with the sample without rGO. In addition to improved mechanical performance, rGO-reinforced composites exhibited lower wear rates and friction coefficients than non-rGO composites, due to the formation of a graphitic lubricating tribolayer on worn surfaces and counterbodies in a friction pair, which provided sufficient lubrication to reduce the coefficient of friction and wear rate. The resulting composites also showed low electrical resistivity, suggesting the possibility of using electrical discharge machining to manufacture ceramic products of complex shapes from them.