Abstract: The moisture and CMAS resistant capabilities of Yb Hafnia multi-layer T-EBCs for SiC CMCs have been evaluated at temperatures in the 1550oC-1600oC range. Several experimental T-EBC compositions with top layers that varied from modest Yb Hafnia to high Yb Hafnia concentrations were subjected to 50% relative humidity and combined AFRL-03 (CMAS)- 50% relative humidity tests under isothermal and thermal cycling conditions. Comprehensive characterization methods-XRD, SEM, EDS- interrogated the reaction behavior of the T-EBC multilayers in 50% RH at temperatures at 1550oC (2822oF) and higher and the nature of the CMAS-coating reactions at 1550oC. CMAS-50% RH tests were also conducted on dense, hot pressed Yb Hafnia samples at 1550oC.
Authors: Larry Fehrenbacher, David Kroliczek, Jeffrey Kutsch, Igor Vesnovsky, Erik Fehrenbacher, Anindya Ghoshal, Michael Walock, Muthyvel Murugan, and Andy Nieto
Keywords: Thermal Environmental Barrier Coatings, SiC CMCs, CMAS, Yb Hafnia