Influence of spraying power on microstructure, phase composition and nanomechanical properties of plasma-sprayed nanostructured Yb-silicate environmental barrier coatings

Currently, achieving high stability for environmental barrier coatings (EBCs) in service at higher operational temperatures (>1400 C) remains a challenging issue. In our previous work, a nanostructured Yb-silicate coating was successfully fabricated, which could be a promising EBC candidate for CMC (Ceramics Matrix Composites) components protection at higher temperatures. However, there have been limited reports on the relationship between mechanical properties and spraying power for producing a nanostructured Yb-silicate coating. Therefore, this study delves into the microstructure, phase composition, and nanomechanical properties of nanostructured Yb-silicate coatings before and after heat treatment at different spraying powers. The results indicate that, due to the intricate interplay of microstructural and phase composition evolution, noticeable disparities in nanomechanical properties were observed in nanostructured Yb-silicate coatings before and after heat treatment. It is noted that the as-sprayed coating at 36 kW exhibits comparable nanomechanical properties to 45.5 kW, whereas the heat-treated coating demonstrates higher nanohardness and elastic modulus at 36 kW but greater damage tolerance at 45.5 kW. These findings offer a preliminary guidance for optimizing process parameters in nanostructured Yb-silicate coating's preparation, and laying the foundation for further researches.