Supersonic plasma sprayed MoSi₂–ZrB₂ antioxidation coating for SiC–C/C composites

A dense and crack free MoSi₂–ZrB₂ coating was prepared on the SiC coated carbon/carbon (C/C) composites using a supersonic plasma spraying technique. The coated composites were characterised using scanning electron microscopy and X-ray diffraction. The analysis shows that the as prepared MoSi₂–ZrB₂ coating, with a thickness of ∼100 μm, combines well with the inner SiC coating. After oxidation at 1200°C for 72 h in air, the mass loss of MoSi₂–ZrB₂/SiC coated C/C is only 4.24 wt-%, which is significantly lower than that of MoSi₂/SiC coated C/C (11.35 wt-%). The excellent oxidation protective ability of the MoSi₂–ZrB₂ coating is mainly attributed to ZrSiO₄ produced by dispersive ZrO₂ particles and SiO₂ in the coating at high temperature.