MoSi2-based oxidation protective coatings for SiC-coated carbon/carbon composites prepared by supersonic plasma spraying

To protect carbon/carbon (C/C) composites against oxidation, MoSi2-based oxidation protective coatings for SiC-coated carbon/carbon composites were prepared on them by supersonic plasma spraying. The MoSi2-based coatings primarily consist of MoSi2, Mo5Si3 and glassy SiO2. Only a few pinholes and some microcracks are observed on the surface and no through-thickness cracks penetrate the cross-section. Weight loss of the MoSi2-based coated specimens is only 1.14% after 400 h oxidation in air at 1773 K and the coated C/C composites remain intact after 11 thermal cycles between 1773 K and room temperature. The outstanding anti-oxidation ability is mainly attributable to the formation of SiO2-based layer on the surface of MoSi2-based coatings.