|About this Abstract
||MS&T22: Materials Science & Technology
||Advanced Materials for Harsh Environments
||CMAS Interaction with Model YAlO3 Environmental Barrier Coatings: Effect of Y3Al5O12 Precipitation on Apatite Nucleation and Growth
||Amanda M. Velazquez Plaza, Amanda R. Krause
|On-Site Speaker (Planned)
||Amanda M. Velazquez Plaza
Alumina ceramic-matrix composite parts allow higher operating temperatures and lighter parts, improving the efficiency of gas turbine engines. In engine environments, alumina reacts with steam and volatilizes, requiring environmental barrier coatings (EBC) for protection. However, interaction with molten ingested aluminosilicates (CMAS) can lead to coating corrosion or grain boundary infiltration, resulting in failure. In this study, we examine the nucleation and growth mechanisms of reaction products formed from CMAS attack on single crystals of EBC candidate YAlO3 (YAP): Y3Al5O12 (YAG) and Ca4Y6(SiO4)6O (apatite). We characterized the microstructural evolution of the CMAS interaction region at 1350°C on multiple YAP substrate orientations. Varying YAP orientations led to dissimilar CMAS loading conditions and degrees of apatite coarsening. By correlating the CMAS-blocking ability with the nucleation and growth of the reaction products on different YAP crystallographic planes, we can move towards engineering a coating that favors desirable CMAS-mitigating products.