Enhancing hardness and toughness of WC simultaneously by dispersed ZrO2

A novel method was proposed to achieve uniform dispersion of ZrO2 nanoparticles in the WC matrix. The prepared WC-ZrO2 ceramic exhibited outstanding mechanical properties with simultaneously high hardness and fracture toughness. It was disclosed that the high toughness of the present WC-ZrO2 ceramic results from the contributions of stress-induced phase transformation from t-ZrO2 to m-ZrO2, the homogeneous ultrafine microstructure with coherent WC/ZrO2 interface, and the stress release of WC in the vicinity of ZrO2. The later two factors enhance the fracture toughness by crack deflection and crack bridging. In particular, the contribution to toughness by phase transformation of ZrO2 is 1.9 and 2.7 times of that of the crack deflection and crack bridging, respectively. This study provides a strategy to increase toughness of ceramics greatly while keeping its high hardness.

Automated summary

A novel method was proposed to achieve uniform dispersion of ZrO2 nanoparticles in the WC matrix, resulting in WC-ZrO2 ceramics with outstanding mechanical properties. The high toughness of the ceramic was attributed to stress-induced phase transformation, a homogeneous ultrafine microstructure with coherent WC/ZrO2 interface, and stress release of WC near ZrO2. Factors like crack deflection and crack bridging further enhanced the fracture toughness. The contribution to toughness by ZrO2 phase transformation was found to be 1.9 and 2.7 times higher than that of crack deflection and crack bridging, respectively. This study provides a strategy to significantly increase the toughness of ceramics while maintaining high hardness.