Self Regenerative Coatings for Enhanced Protection of Silicon Based Ceramic Composites in Particle Laden Degraded Engine Environments

Environmental barrier coatings (EBCs) are coating systems that are applied to the surface of Si-based ceramics resulting in protection against moisture-assisted oxidation-induced ceramic recession. These coatings require many attributes to be successful including: good stability in the presence of water vapor; a mechanism for limiting the transport of oxygen and water vapor to the ceramic substrate; good chemical compatibility at the interface; high temperature phase stability, to limit volume changes resulting from phase transformations in the coating materials; and the ability to provide thermal protection. These requirements also must be retained in the presence of particle laden environments. Particle interactions with the coating systems in service can result in both the gradual removal of material (i.e., erosion) and the cracking and immediate removal of significant amounts of material (i.e., impact or foreign object damage). At higher engine operating temperatures, particles ingested in the engine will melt and result in the formation of glassy deposits on engine components that reduce coating durability. The work is this program is designed to utilize a baseline T/EBC system and, then, incorporate and test multiple protection concepts that are anticipated to result in improved durability in particle laden environments.