L. Fehrenbacher, D. Kroliczek, J. Kutsch, I. Vesnovsky, E. Fehrenbacher Technology Assessment and Transfer, Inc., A. Ghoshal*, M. Murugan*, M. Walock*, A. Nieto*; *Army Research Laboratory, Aberdeen Proving Ground MD
Technology Assessment and Transfer has extended the moisture and CMAS capabilities of Yb hafnia based multi-layer T-EBCs to 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- confirmed the degree of degradation in 50% RH at temperatures above 1550oC and the nature of the CMAS-coating reactions at temperatures from 1400oC to 1550oC. The high temperature behavior of AFRL-03 mineral based CMAS was compared to synthetic 33CaO–9MgO–13AlO1.5–45SiO2 CMAS with selected Yb hafnia coatings.