High-temperature stability and oxidation behavior of SiOC/HfO₂ ceramic nanocomposite in air

High temperature stability (1100−1500 °C) and oxidation behavior at 1500 °C of the SiOC/HfO₂ ceramic nanocomposite were investigated in air. Consumption of free carbon dominated thermal stabilities of the bulk at below 1200 °C. Whereas, the continuous cristobalite scale, rather than HfSiO₄, was responsible for the improved oxidation resistance at exceeding 1200 °C. At 1500 °C, HfSiO₄, with maximum 30 vol. % concentration for duration of ∼ 15 h, suffered ruptured spherical-bubbles by volatilized species and did not consolidate into a completely protective scale. Thus, the bulk exhibited limited resistance to oxidation at 1500 °C for long-term applications.