Construction of Y(Al)SixOy protective layer on SiC ceramic substrate through thermal diffusion

As the promising candidates for hot section components used in gas turbines , SiC f /SiC composites suffer severe gas steam/melt corrosion, so their long-term stability depends on the surficial environmental barrier coatings . Here, we provide an alternative method to construct the protective structure by thermal diffusion . Firstly, Y-Al diffusants is diffused into the SiC substrate, forming a Y-Al diffusion layer . Then the diffusion layer can transform to a corrosion-resistant Y(Al)Si x O y layer after oxidative treatment. The compositions and morphologies of the as-received diffusion layer and the Y(Al)Si x O y layer were contrasted. Results show that a Y(Al)Si x O y protective layer, which thickens with the extension of oxidative treatment time and the increase of Y/Al ratio, can be formed on the SiC surface. Concentration gradient caused by preferential oxidation of Y-Al prompts the Y-Al diffusing towards surface. Meanwhile, the oxidation of Y-Al makes the Y(Al)Si x O y layer denser and thicker, and finally form the Y(Al)Si x O y protective layer.