关键词: Si-SiC-TaB₂涂层, Si-SiC涂层, 石墨, 抗烧蚀性, 反应熔渗

Abstract: In order to improve the ablation resistance of carbon materials,Si-SiC and Si-SiC-TaB₂ coatings were prepared on the surface of graphite materials using graphite block as the matrix,SiC (d₅₀=10 μm),B₄C (d₅₀=50 μm) and TaC (d₅₀=3 μm) as main raw materials,by the slurry method combined with reactive melt infiltration of Si.The phase composition,the microstructure,and the element distribution of the coatings were studied,the thermal shock resistance of the Si-SiC-TaB₂ composite coating from room temperature to 1 600 ℃ was investigated,and the ablation resistance of the coating on graphite at high temperatures was tested by the plasma flame ablation test (120 and 1 980 s at 2 350 ℃,respectively).The results show that:the structure of Si-SiC-TaB₂ composite coating is dense,and there is no obvious interface among SiC,TaB₂ ceramic particles and Si in the coating.After 20 cycles of thermal shock from 1 600 ℃ to room temperature,the mass of the coating sample basically increases gradually,and the sample performs good thermal shock resistance.The mass of the Si-SiC-TaB₂ composite coated sample increases after 1 980 s of ablation,and the surface is covered with a Ta-Si-O oxidation protective layer containing Ta₂O₅ and SiO₂,which effectively prevents the corrosion of high temperature flame to the interior of the graphite.The mass of the Si-SiC coated sample decreases after ablation,and a damaged SiO₂ oxide layer is formed on the surface,and there are clearly visible ablation pits.

Key words: Si-SiC-TaB₂ coating, Si-SiC coating, graphite, ablation resistance, reactive melt infiltration