Oxidation behaviours of ZrB2-SiC-MoSi2 composites at 1800 °C in air with different pressures

Abstract The oxidation behaviours of ZrB 2 -20SiC and ZrB 2 -20SiC-10MoSi 2 (vol.%) at 1800 °C in air with different pressures of 0.5, 5 and 10 kPa (correspondingly the oxygen partial pressure was 0.1, 1 and 2 kPa, respectively) were investigated. In 0.5 kPa air, catastrophic oxidation occurred for both composites. However, the addition of MoSi 2 could enhance the oxidation resistance of the ZrB 2 -20SiC composite in 5 and 10 kPa air, this was attributed to the reactions of MoSi 2 with ZrB 2 and highly volatile B 2 O 3 to form stable MoB, causing the formation of a continuous, compact and silica-rich outer oxide layer with lower oxygen permeability.