Results and discussion Phase and microstructure analysis

The carbon (i.e., carbon fibers and vitreous carbon) in the composites will be oxidized in an environment containing oxygen above 673 K, and the Barasertib rate increases quickly as the temperature increases, which greatly limits their applications [14] and [15]. Oxidation protective coating is considered to be an effective method for preventing carbon/carbon composites against oxidation at high temperature [16], [17] and [18]. Zirconium boride (ZrB2) possesses high melting point (3523 K), low evaporation, good chemical inertness and good ablation resistance [19] and [20]. Molybdenum disilicide (MoSi2) with high melting point (2303 K) exhibits a brittle-to-ductile transition and significant metallic ductility above 1173 K, which can play important roles in rapid manufacturing processes and avoid catastrophic composite failure during oxidation [21], [22] and [23]. The thermal stable borosilicate glass (i.e., SiO2-B2O3), which has high melting point, appropriate wetting properties and viscosity, has been used as effective crack sealants. Therefore, the introduction of ZrB2, MoSi2 and borosilicate glass into the coating matrix can greatly improve the oxidation resistance of the densified or porous C/C composites under an oxidative atmosphere at high temperature [24], [25] and [26].