Oxidation behaviors of ZrB2-SiC binary composites above 2000 °C

Rapid oxidation testing for monolithic ZrB2 and ZrB2-SiC binary composites with different SiC contents (0-30 vol%) was performed using an electric heating system above 2000 °C. The system used in this study achieved the high heating rate of 250 °C/s. The experimental results showed that the morphologies of the oxidized specimens depended strongly on the SiC content. The formation mechanism of SiC-depleted layers beneath the surface scale above 2000 °C differed completely from that below 2000 °C. Although the holding time was below 10 s, SiC-depleted layers were formed because the oxygen partial pressure of the air atmosphere was not enough to form SiO2 by the oxidation of SiC. It was determined that ZrB2-20 vol% SiC showed the best oxidation resistance above 2000 °C at high heating rates.