Abstract:The SiC/ZrSiO4-SiO2 composite coatings were prepared on carbon/carbon(C/C) composites by combining pack cementation and slurry painting method to improve the oxidation resistance and decrease the infrared emissivity. The phase compositions and microstructures of the as-prepared coatings were characterized by XRD, SEM and EDS. The oxidation resistance of the SiC/ZrSiO4-SiO2 coatings were evaluated in dynamic air (air flow rate: 0.6 L/min) at 1400℃ and 1500℃, respectively. The infrared emissivity of the SiC/ZrSiO4-SiO2 coatings coated C/C samples were also investigated at 90℃ and 500℃, respectively. The results show that the composite coatings which are composed of SiC inner coating with loose structure and ZrSiO4-SiO2 outer coating with mosaic structure exhibit excellent oxidation resistance and can protect C/C matrix from oxidation for long time. The mass loss rates of the SiC/ZrSiO4-SiO2 coatings coated samples are only 0.124% and 0.03% in dynamic air at 1400℃ and 1500℃ after 55h oxidation, respectively. The infrared emissivity of C/C composites can be decreased by coated SiC/ZrSiO4-SiO2 composite coatings, and the infrared emissivity descends with the temperature increasing. The average infrared emissivity of the coated C/C samples in 3~5μm and 8~14μm at 90℃ are 0.55 and 0.66, respectively. And the average infrared emissivity in 3~5μm and 8~14μm at 500℃ are 0.48 and 0.62, respectively. From the anti-oxidation and infrared emissivity property point of view, the C/C composites coated SiC/ZrSiO4-SiO2 coatings may be one of the most promising candidates as high-temperature structural materials applied in the field of aeronautics and astronautics.