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采用双辉等离子技术在石墨表面制得W/Ir功能复合涂层,研究了其组织结构和抗烧蚀机制。该复合涂层由两层W和两层Ir交替叠加而成,与石墨接触的W起到增加涂层结合强度的作用,表面的Ir起到隔离氧环境的作用。在2 000℃的氧-乙炔焰下烧蚀70 s,涂层仍能保持完整的结构,有效地保护了石墨基体。烧蚀结果表明,Ir涂层控制氧的渗透速度,经Ir涂层缺陷渗入的氧与W涂层反应形成挥发性WO3,W涂层作为消耗层,进一步阻止氧的扩散,保护内部涂层。试样的烧蚀失重率为1.62%。
The W / Ir composite coating was prepared on the surface of graphite by double glow plasma technology, and its microstructure and anti-ablation mechanism were studied. The composite coating is composed of two layers of W and two layers of Ir alternatingly superimposed, and the graphite in contact with W acts to increase the bonding strength of the coating. The surface Ir plays a role of isolating the oxygen environment. After ablation for 70 s at 2 000 ℃ for oxy-acetylene flame, the coating can still maintain the intact structure and effectively protect the graphite matrix. The ablation results show that the Ir coating controls oxygen penetration rate and oxygen infiltrated by Ir coating defects reacts with W coating to form volatile WO3. The W coating acts as a sacrificial layer, further retarding the diffusion of oxygen and protecting the interior coating. Ablation weight loss rate of the sample was 1.62%.