Influence of Chromium Diboride on High Temperature Oxidation Resistance of ZrB2-Based Ceramics

The effect of chromium diboride addition on the densification process and oxidation behavior of two ZrB2-MoSi2 and ZrB2-SiC baseline systems was studied. CrB2 was beneficial in lowering the sintering temperature owing to the tendency of its oxide to react with MoSi2 and SiC forming low-melting phases that helped the powder consolidation. Oxidation at 1500 °C induced the formation of further boron oxide as first consequence. In one case, when CrB2 was combined with MoSi2, an improved oxidation resistance was observed due to the stabilization of Cr-borides in the subscales saturated with B2O3. In the other case, when it was combined with SiC, the excessive low viscosity of the borosilicate glass facilitated the consumption of a thicker portion of materials as compared to the ZrB2-SiC reference.