Microstructure, mechanical properties and thermal shock resistance of hot-pressed ZrO 2(3Y)-BN composites

Abstract

ZrO 2(3Y)-BN composites were prepared by hot-pressing with different contents of BN ranging from 0 vol.% to 40 vol.%. The addition of BN was found to have a significant influence on the phase transformation, microstructure, mechanical properties and thermal shock resistance of the composites. With the increased content of BN, the Vickers’ hardness, flexural strength and fracture toughness of the ZrO 2(3Y)-BN composites exhibited a gradual degradation, but the thermal shock resistance was obviously improved. Results showed that the critical thermal shock temperature (Δ T C) of ZrO 2(3Y) was only 280 °C; however, it was increased to be more than 430 °C and 530 °C for ZrO 2(3Y)-20BN and ZrO 2(3Y)-40BN, respectively. Improvement of thermal shock resistance for the ZrO 2(3Y)-BN composites was mainly due to the lower α, E, k and higher ratio value of K IC/ σ by adding BN particles.