Significant improvement of the self-protection capability of ultra-high temperature ceramic matrix composites

Highlights: • Short term oxidation tests at 1500 °C and 1650 °C were carried out on UHTCMC. • Less than 30 vol% of ZrB₂ into SiC(O) matrix is able to impart a fast passivation. • Oxidation resistance was affected by the distribution of ZrB₂ into the SiC matrix. The oxidation behaviour of C_f/ZrB₂-SiC with different fibre architectures, manufactured by slurry impregnation, polymer infiltration and mild pyrolysis, was investigated. Short term oxidation tests in air were performed for 1 min and 5 min at 1500 °C and 1650 °C in a bottom loading furnace. Microstructure, oxide scale thickness and composition were analysed by SEM/EDS/XRD. Results indicated that a good dispersion of ZrB₂ particles in the polymer derived SiC(O) matrix promoted the formation of compact scales filling surface holes left by fibre oxidation. 20−30 vol% of ZrB₂ in the material was found a good compromise between lightness and oxidation resistance.