High‐Temperature Oxidation at 1900°C of ZrB ₂ – x SiC Ultrahigh‐Temperature Ceramic Composites

Oxidation of ZrB 2 ‐based ultrahigh‐temperature ceramic composites containing 10, 20, and 30 vol% SiC was performed at 1900°C for 1 h in air. ZrB 2 –20 vol% SiC exhibited the highest oxidation resistance at this temperature and formed a dense coherent oxide scale after oxidation, whereas a strong degradation was observed for both ZrB 2 –10 vol% SiC and ZrB 2 –30 vol% SiC. In addition, cracks and spallation in the oxide scale were also detected for the latter materials. The oxidation behaviors of ZrB 2 –SiC composites were investigated. The effect of SiC content was analyzed and oxidation models were proposed to describe the observed microstructures.