LAUSR

Abstract The oxidation behaviors of four compositions of ZrB 2 -SiC-ZrC and one composition of ZrB 2 -SiC were studied at 1700 °C in air and under low oxygen partial pressure. Volatility diagrams for ZrB 2 -SiC-ZrC and ZrB 2 -SiC were used to thermodynamically elucidate the oxidation mechanisms. SiO 2 and ZrO 2 layers formed on the surfaces of ZrB 2 -SiC-ZrC and ZrB 2 -SiC oxidized at 1700 °C. A SiC-depleted layer only formed on the surface of the ZrB 2 -SiC oxidized under low oxygen partial pressure. The oxide layer thickened with increasing ZrC volume content during oxidation in air and under low oxygen partial pressure. The ZrB 2 -SiC-ZrC oxide surface exploded in air when the ZrC volume content was more than 50%. Under low oxygen partial pressure, the oxide surfaces of all the ZrB 2 -SiC-ZrC specimens bubbled.