|About this Abstract
||Materials Science & Technology 2020
||Thermodynamics of Materials in Extreme Environments
||Improved CMAS Resistance of Environmental Barrier Coatings via Tailoring Phase and Composition of Mixed Rare Earth Silicates
||Elizabeth J. Opila, Rebekah Webster, Cameron Miller, Clark Luckhardt
|On-Site Speaker (Planned)
||Elizabeth J. Opila
Environmental barrier coatings (EBCs) are required to protect SiC-based composites from rapid water vapor degradation in turbine engine combustion environments. State-of-the-art EBC materials are rare earth silicates, chosen for their reduced silica activity, chemical compatibility and thermal expansion match with the substrate. However, deleterious reactions with CMAS (CaO-MgO-Al2O3-SiO2) that is ingested into aircraft turbine engines remain a challenge. CMAS melts at approximately 1200C and can infiltrate/react with the coating, degrading the coating microstructure via crack, blister and pore formation. One approach to mitigate the degradation is to formulate coating compositions that promote CMAS reactions to form dense product phases, such as apatite, that limit further infiltration and reaction. In this presentation, novel EBC materials are described that show promise for mitigating EBC–CMAS reactions. These compositions include mixed rare earth mono- and disilicates, mixed rare earth disilicate-rare earth oxides, and mixed rare earth cations in a single monosilicate solution phase.