In the next generations of turbine engines, improving the heat resistance and reducing the weight are the key essential solutions to increasing the thermal efficiency, reducing fuel consumption and CO
2 emissions. The silicon-based ceramics (ex. SiC
f/SiC ceramics matrix composites: CMCs and monolithic Si
3N
4) are the leading candidates for these applications because of the extreme light weight and superior heat resistance compared to the current Ni-based alloys. The main challenge of the Si-based ceramics is its oxidation and volatilization of the silica in the high temperature combustion gas environment with the water vapor, and thereby its rapid recession. The most promising approach is protecting the surface of the CMCs from the water vapor attack by an external environmental barrier coating layer (EBC). Since the early 1990′s a lot of efforts have been done and no single material can satisfy all the EBC requirements. Thereby, the current EBC trends are directed to the development of multilayered EBCs, with different functions as a significant solution to prevent the CMC recession and to maximize its performance for next engine generations. This paper discusses the history, current status and future trends of EBC development not only in the world but also in Japan. Furthermore, it introduces the future prospects of fine particle spraying in EBC developments.
View full abstract