Interaction of ytterbium monosilicate environmental barrier coating material with molten calcium-magnesium-aluminosilicate (CMAS)

The corrosion behaviors and mechanism of CMAS on Yb2SiO5 (YbMS) ceramics were investigated. Results indicated that YbMS was corroded by CMAS to generate various apatite and garnet, whose stability depends on the amounts of doping cations. Noticeably, the Ca2+ acts as an obvious sign of the reaction front diffusing into YbMS along the grain boundaries and volume. The higher diffusion rate of grain boundary than volume results in discontinuous reaction layers. The YbO1.5 formed by the dissolution of YbMS diffuses along the CMAS glass grid until the solubility is saturated to form a cyclic apatite phase, above 1300 ℃.