Novel magnetron sputtered yttrium-silicon-iron oxide as CMAS resistant top coat material for environmental barrier coatings

A nano-crystalline coating containing X2-yttrium monosilicate, yttrium ferrite and yttria was developed as a potential CaO-MgO-Al2O3-SiO2 (CMAS) resistant top layer for Environmental Barrier Coatings (EBCs) to protect Ceramic Matrix Composites. High temperature reactions at 1300 degrees C with a synthetic CMAS and Colima volcanic ash revealed that the phases react quickly with the melt to oxyapatite and garnet which effectively restricted the infiltration into the coating. The Fe played a major role in stabilizing the multi-phase coating as well as X2 -yttrium monosilicate. Iron-free YSi-Ox coatings could not induce garnet formation and found to be less effec-tive in restricting the CMAS infiltration.