Microstructure and mechanical properties of hot pressed ZrB2-SiCp-ZrO2 composites

The present paper investigated the microstructure and mechanical properties of ZrB₂-10 vol.%SiC_p-10 vol.%ZrO₂ composites hot pressed at three temperatures. Phase transformability from t-ZrO₂ to m-ZrO₂ during fracture was analyzed through calculating the volume fractions of m-ZrO₂ and t-ZrO₂ on polished and fracture surfaces. The densification temperature was found to have a significant effect on the microstructure, phase transformation and the properties of the composites. When the composite was hot pressed at 1950 °C, the average grain size was 9.5 µm, and the fracture toughness was 4.5 MPa·m^1/2. Comparatively, when the composite was hot pressed at 1750 °C, the average grain size was 3.4 µm, and the fracture toughness increased by ~ 50% to 6.8 MPa·m^1/2.