SiC coatings were prepared on the surface of C/C composites by pack cementation and chemical vapor deposition.The structure characteristics of SiC coatings respectively prepared by two methods and the oxidation behavior of C/C composites in static air at 1 200 ℃ were analyzed by X-ray diffraction (XRD),scanning electron microscopy (SEM) and thermal oxidation experiments.The results show that the PC-SiC coating is composed of irregular polygonal particles with high binding strength to the matrix,but the carbon fiber of the matrix will be corroded by Si to different degrees during the reaction.With the increase of Al2O3 additive content,the SiC particles in the coating will be refined,resulting in higher density and antioxidant properties.The CVD-SiC coating is composed of spherical SiC particles with poor crystablline,and the coating has high density.Since the coating is prepared by deposition,there is a clear interface between the coating and the C/C matrix,and the binding strength is poor,and the coating is easy to peel during oxidation.As the deposition time increases,the thickness of the coating increases,and the antioxidant performance increases,but it is weaker than the antioxidant capacity of the PC-SiC coating.

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