Study of the SiC-TaSi₂/MoSi₂ multilayer oxidation protective coating for carbon/carbon composite

A SiC-TaSi₂/MoSi₂ multilayer oxidation protective coating on carbon/carbon (C/C) composite was prepared by pack cementation. Effects of the contents of Ta and Mo in the second-step pack powders 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 the multi-coating prepared at the mol ratio of 1:1 of Ta and Mo has a thicker, denser structure than those at the other mole ratios of 0:1, 1:3, 3:1, on which the stable and dense glassy SiO₂ film could be formed during oxidation test. After 326 h oxidation in air at 1500°C and thermal cycling between 1500°C and room temperature for 23 times, the weight loss of the coated specimen was only 0.97%, implying that the multi-coating prepared at the mol ratio of 1:1 of Ta and Mo has excellent oxidation protective ability and thermal shock resistance.