Y2O3 and Nd2O3 co-stabilized ZrO2-WC composites

Y2O3 + Nd2O3 co-stabilized ZrO2-based composites with 40 vol% WC were fully densified by pulsed electric current sintering (PECS) at 1350 C and 1450 C. The influence of the PECS temperature and Nd2O3 co-stabilizer content on the densification, hardness, fracture toughness and bending strength of the composites was investigated. The best combination of properties was obtained for a 1 mol% Y2O3 and 0.75 mol% Nd2O3 co-stabilized composite densified for 2 min at 1450 C under a pressure of 62 MPa, resulting in a hardness of 15.5 ± 0.2 GPa, an excellent toughness of 9.6 ± 0.4 MPa.m0.5 and an impressive 3-point bending strength of 2.04±0.08 GPa. The hydrothermal stability of the 1 mol% Y2O3 + 1 mol% Nd2O3 co-stabilized ZrO2-WC (60/40) composites was compared with that of the equivalent 2 mol% Y2O3 stabilized ceramic. The double stabilized composite did not degrade in 1.5 MPa steam at 200 C after 4000 min, whereas the yttria stabilized composite degraded after less than 2000 min. Moreover, the (1Y,1Nd) ZrO2-WC composites have a substantially higher toughness (*9 MPa.m0.5) than their 2Y stabilized equivalents (*7 MPa.m0.5).