High temperature oxidation resistance of hot-pressed h-BN/ZrO2 composites

Influences of ZrO2 additive on the microstructure and high temperature oxidation behavior of h-BN/ZrO2 composites have been investigated. In addition to the enhanced strength, the oxidation reaction between boron and oxygen can be effectively hindered even at 1200 °C when adding 20 wt% ZrO2 into the h-BN matrix. Besides the doped ZrO2 particles, ZrB2 and ZrB were also formed in the composites after sintering via the reaction between ZrO2 and h-BN. The oxidation product ZrO2 of these Zr–B compounds can act as protective layer during oxidation, which covers the sample surface and prevents further penetration of oxygen. Good oxidation resistance at 1200 °C and high strength make h-BN/ZrO2 composites promising materials for high temperature applications.