High-Temperature Oxidation at 1900°C of ZrB2-xSiC Ultrahigh-Temperature Ceramic Composites

Oxidation of ZrB2-based ultrahigh-temperature ceramic composites containing 10, 20, and 30 vol% SiC was performed at 1900 degrees C for 1 h in air. ZrB2-20 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 ZrB2-10 vol% SiC and ZrB2-30 vol% SiC. In addition, cracks and spallation in the oxide scale were also detected for the latter materials. The oxidation behaviors of ZrB2-SiC composites were investigated. The effect of SiC content was analyzed and oxidation models were proposed to describe the observed microstructures.