Abstract: A SiC-WSi₂/MoSi₂ multilayer oxidation protective coating for carbon/carbon (C/C) composites was prepared by pack cementation. Effects of the total content of W and Mo on the microstructure and high temperature anti-oxidation property of the multi-coating were studied by XRD, SEM, EDS and isothermal oxidation test. The results show that with the total content of W and Mo increasing in the pack powders, the as-received multi-coating thickness first increases and then decreases. The multi-coating with 10.0at％ (W and Mo) has a thicker, denser structure and higher content of WSi₂ and
MoSi₂ than those with 0at％, 8.4at％ and 13.1at％ (W and Mo). A stable and dense glassy SiO₂ film can be formed on the coating surface with 10.0at％
(W and Mo) during the oxidation test. The coated specimen with 10.0at％ (W and Mo) has no weight loss after oxidation in air for 315h at 1500℃ and no cracks after thermal cycling between 1500℃ and room temperature for 18 times, which implies that the multicoating has excellent oxidation protective ability and thermal shock resistance.

Key words: C/C composites, coating, oxidation resistan