Effect of nano-yttria addition on the properties of WC/Co composites

Nano-grained yttria additions to WC/Co based composites have the potential to replace standard materials for tools, dies and wear parts because of their increased hardness and toughness. By means of particle size reduction, the fracture toughness of WC/Co can be increased significantly. This work aims at processing and sintering of composites from WC/Co and 5-20 wt.% nano-grained yttria. The composite mixtures were mixed, formed and sintered at 1450 °C under vacuum. The properties of these composites in terms of densification parameters, fracture toughness, and hardness were measured. The results explored a significant improvement in the properties of WC/Co with addition of 5 wt.%Y2O3. However, the addition of less or more quantity of nano-grained yttria than 5 wt.% has been shown a negative effect on the properties. Fracture toughness (K1C) of the WC/Co-5 wt.%Y2O3 showed remarkable enhancement (∼13.611 MPa m0.5) compared by the reported data of WC-6.5%Co composite (∼9-11 MPa m0.5). The microstructure was correlated with changes of these properties.