Processing and characterization of ZrB2–SiCW ultra-high temperature ceramics

SiC whisker-reinforced ZrB2 ultra-high temperature ceramics containing 20 vol.% whisker were prepared in the temperature range of 1750–2000 °C by hot pressing. The microstructure and mechanical properties of ZrB2–SiCW ultra-high temperature ceramics were examined. The results showed that SiC whiskers were not stable in the ZrB2 matrix above 1900 °C and degenerated into particles. The sintering temperature for this material system should be lower than 1800 °C to obtain high performance of ZrB2–SiCW. Significant improvement in fracture toughness of the material was obtained at 1800 °C using fine ZrB2 particles compared to ZrB2 ceramic. The improvement of toughness was mainly attributed to whisker bridging and cracking deflection around whiskers.