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 ZrO ₂ 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.