CMAS-Resistant Thermal Barrier Coatings (TBC)

Electron beam-physical vapor-deposited thermal barrier coatings (TBC) are susceptible to damage due to environmental contaminants such as calcium-magnesium-aluminum-silicon oxide systems (CMAS). This paper discusses various approaches of modifying TBC for enhanced protection against CMAS attack. Methodologies were explored with various coating systems maintaining functionality as nonwetting, sacrificial, and impervious to CMAS attack. In the brief isothermal (1260 degrees C/10 min) tests, a nearly crack-free and reglazed Pd coating provided substantial protection from the CMAS attack. Approaches that provided some minor improvements need further optimization to better assess their viability.