Self-healing ZrB2–SiO2 oxidation resistance coating for SiC coated carbon/carbon composites

• ZrB2–SiO2 coating was prepared by infiltrating silica sol into porous ZrB2 layer.
• Dispersed ZrB2 particles improved the oxidation resistance of the coating.
• Formation of ZrO2 and ZrSiO4 generated compressive stress during oxidation.
• Compressive stresses restrained the formation of cracks in the coating.

A ZrB2–SiO2 coating was prepared on the SiC coated carbon/carbon composites by infiltrating silica sol into a porous ZrB2 layer. The ZrB2–SiO2 coating protected the composites from oxidation for 330 h at 1500 °C with a weight loss of 158 g/m2. The formation of ZrO2 and ZrSiO4 from ZrB2 expanded the volume of solid phase, generating compressive stress in the coating at high-temperature oxidations. The phase transformation of ZrO2 provided the compressive stress in the coating during cooling. These compressive stresses restrained the formation of cracks and improved the oxidation protection of the coating.