Initial oxidation behaviors of ZrB2-SiC-ZrC ternary composites above 2000 °C

The initial oxidation behavior of ZrB2-SiC-ZrC (ZSZ) composites above 2000 °C after the initial ∼5-10 s was examined by an electric heating system. The morphology of the oxide layer was shown to depend on the ZrC content. Volume expansion during the conversion of ZrC to ZrO2 contributed to the morphology of the surface oxide layer. Above 2000 °C, the ZSZ composite with the highest ZrC amount had the lowest oxide layer thickness. This study clearly showed the efficacy of ZrC as an additive to significantly alter the oxide layer morphology relative to that observed for ZrB2-SiC composites tested under the same condition.