Effects of microstructure on corrosion behaviors for RE2SiO5 (RE=Gd, Y, Er) environmental barrier coatings against calcium-magnesium-alumino-silicate melts

The corrosion behaviors and mechanisms of plasma-sprayed X1-Gd2SiO5 and X2-RE2SiO5 (RE=Y, Er) environmental barrier coatings against CMAS melts at 1400 C were explored. Results showed that the RE2SiO5 coatings dissolved into CMAS melts and formed a continuous dense layer of apatite phase at the interface, while garnet phase was only found in the X2-Er2SiO5 coating. The recession of RE2SiO5 was related to its microstructure and RE ionic radius. The RE2SiO5 with X2 phase and smaller RE ionic radius exhibited better corrosion resistance due to its more stable crystal structure, lower reactivity with CMAS and easier to form garnet phase.