|About this Abstract
||Materials Science & Technology 2020
||Coatings to Protect Materials from Extreme Environments
||Anisotropic Wettability of CaO-MgO-Al2O3-SiO2 Deposits on YAlO3: Implications for Grain Boundary Engineering of Environmental Barrier Coatings for Gas Engine Applications
||Amanda M. Velazquez Plaza, Amanda Rochelle Krause
|On-Site Speaker (Planned)
||Amanda M. Velazquez Plaza
Yttrium aluminate perovskite (YAP) is an environmental barrier coating (EBC) candidate for oxide-based ceramic-matrix composite components in gas turbine engines. EBCs protect the composites from volatilization and from attack by ingested airborne calcia-magnesia-aluminosilicates (CMAS). CMAS melts and infiltrates EBC grain boundaries, inducing spallation during engine operation. The penetration rate is dependent on the melt’s wetting behavior and reaction products that can block penetration pathways. Anisotropic differences in these interactions were considered in this study to ascertain the merits of applying grain boundary engineering to CMAS-resilience. We measured contact angles of quenched CMAS on three different orientations of YAP single crystals and characterized the interfacial region with scanning electron microscopy. A wetting transition accompanies the nucleation of several crystalline phases, suggesting the reaction products strongly alter the interfacial energy. We discuss the crystallographic relationships uncovered and its implications for designing future EBC microstructures.