SiC表面固相反应涂层

Coating on SiC Surface by Solid State Reaction With Cr Powder

烧结致密的α SiC片在埋入Cr粉中 ,并经 110 0℃在静态真空环境中高温处理 1h后 ,在其表面形成厚度约 5 μm均匀、致密的涂层。涂层是由Cr的硅化物Cr3Si和碳化物Cr7C3、Cr2 3C6 构成 ,为层状结构 ,其相排列顺序为SiC Cr3Si +Cr7C3 Cr7C3 Cr2 3C6 Cr。SiC与Cr间的固相反应受Cr在涂层中向SiC反应界面的扩散控制。在热震实验中 ,SiC表面涂层结合仍十分紧密 ,没有出现剥落或产生裂纹 ,说明SiC表面涂层具有良好的热稳定性。

α-SiC piece is immersed in Cr powder and annealed at 1 000 °C in static vacuum atmosphere for an hour, forming dense and uniform coating about 5 μm thick on its surface. The coating layer is composed of silicide and carbides of Cr, with a sequence of SiC/Cr3Si + Cr7C3/Cr7C3/Cr23 C6/Cr. The solid phase reaction between SiC and Cr powders is controlled by the diffusion of Cr in the coating towards SiC interface. In thermal shocking test, the coating remains to joint very densely with SiC surface without spalling off and/or cracks. This means that the coating on SiC surface has good thermal stability.