Crystallization and phase evolution in novel (Gd1/6Tb1/6Dy1/6Tm1/6Yb1/6Lu1/6)(2)Si2O7 environmental barrier coating

Design of multiple rare-earth (RE) principal elements is a practical strategy to optimize key property of RE disilicate environmental barrier coating (EBC). However, multi-RE component in the feedstocks may also introduce critical fabrication problems due to the different evaporating and crystallizing behaviors of the EBC containing various RE composition. We herein report the preparation of a novel multi-RE disilicate (Gd1/6Tb1/6Dy1/6Tm1/6Yb1/6Lu1/6)(2)Si2O7 EBC by atmospheric plasma spraying (APS). The crystallization behavior of the as-deposited coating annealed at 1100 degrees C-1300 degrees C with different durations (5 and 20 h) in air and argon atmospheres were investigated through comprehensive characterization techniques. RE disilicate, RE mono-silicate, and RE apatite were detected in the as-sprayed coatings, and mono-silicate and apatite transform to RE2Si2O7 with the increment of temperature and extension of annealing duration. Furthermore, the contribution of multiple RE to the formation of apatite phase is discussed. The results provide a fundamental understanding and may guide the controllable preparation of multi-RE disilicate EBC via APS method.