Oxidation resistance, oxidation mechanism and mechanical properties of ZrB₂-SiC-TaB₂ ceramics

In order to further improve the oxidation resistance of ZrB₂-SiC ceramics, ZrB₂-SiC-TaB₂ ceramics were designed and prepared. The effects of TaB₂ content on the ZrB₂-SiC ceramics were investigated systematically. Oxidation resistance, oxidation mechanism and mechanical properties were investigated by first-principles calculation and experiments. ZrB₂-SiC-TaB₂ ceramics showed the significantly improved oxidation resistance. After oxidation at 1400 °C for 20 h, compared with ZrB₂-SiC ceramic, the specific weight change of ZrB₂-SiC-TaB₂ ceramic was decreased from 18.86 mg/cm² to 8.95 mg/cm² and the corresponding residual strength retention ratio was increased from 52 % to 69 %. The improved oxidation resistance and residual strength retention ratio could be ascribed to the formation of Ta-modified glassy layer, which resulted in the increased bridging oxygen content, the improved stability of glass structure and the decreased oxygen diffusion rate. This work contributes to a better understanding of the oxidation mechanism of ZrB₂-SiC-TaB₂ ceramic.