Processing of yttria stabilized zirconia/tungsten carbide composites by ceramic injection molding

Ceramic composites with partially stabilized zirconia (3Y-TZP) matrix and 20 vol% micron-sized WC dispersion were produced by ceramic injection molding (CIM) and subsequent pressureless sintering. In order to produce dense parts, injection molding and sintering parameters were optimized. High densities and mechanical properties were obtained by long dwelling and by using proper sintering atmosphere. Mechanical and microstructural properties were compared with hot pressed parts of the same composition. Composites with a high fracture toughness of 9. 2 MPa. m^1/2 but somewhat reduced strength were obtained by pressureless sintering. XRD analyses of sintered and hot-pressed materials revealed different phase compositions. To measure the tribological properties, unlubricated pin on disc tests were performed on the polished surfaces of the composites. Friction coefficients and wear resistance of CIM samples were similar to hot pressed materials. This indicates that production of complex shaped Y-TZP/WC wear parts with moderate WC fractions ≤ 20 vol-% is possible with ceramic injection molding technique.