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Abstract: Multi-layer MoSi2–CrSi2–Si anti-oxidation coatings with different compositional ratios were prepared on the surface of SiC coated carbon/carbon (C/C) composites by a two-step pack cementation method. The microstructure and anti-oxidation performance of the coating were studied. The results show that the multi-layered coatings could protect the C/C composites from oxidation in air at 1773K for 1000h or 1873K for 750h, respectively. The anti-oxidation performance of the multi-layer MoSi2–CrSi2–Si coating is mainly attributed to their dense and microcrack-free structure, appropriate thermal expansion coefficient and the well dispersed MoSi2 and CrSi2 in the coating. [Copyright &y& Elsevier]

Abstract: To protect carbon/carbon (C/C) composites against oxidation, a B2O3 modified SiC–MoSi2 coating was prepared by a two-step pack cementation. The microstructure and the oxidation resistant property of the coating were studied. The results show that, the as-received coating is a dense structure, and is composed of α-SiC, β-SiC and MoSi2. The B2O3 modified SiC–MoSi2 coating has excellent oxidation resistant property, and can protect C/C composites from oxidation at 1773K in air for more than 242h. The failure of the coating was considered to arise from the existence of the penetration cracks in the coating during the slow cooling from 1873 to 673K. [Copyright &y& Elsevier]