Calcium-magnesium-alumina-silicate (CMAS) resistant Ba2REAlO5 (REÂ =Â Yb, Er, Dy) ceramics for thermal barrier coatings

Calcium-magnesium-alumina-silicate (CMAS) attack has been a great challenge for the application of thermal barrier coatings (TBCs) in modern turbine engines. In this study, a series of prospective TBC candidate materials, Ba2REAlO5 (RE = Yb, Er, Dy), are found to have high resistance to CMAS attack. The rapid formation of a continuous crystalline layer on sample surface contributes to this desirable attribute. At 1250 °C, Ba2REAlO5 dissolve in the molten CMAS, accumulating Ba, RE and Al in the melt, which could trigger the crystallization of celsian, apatite and wollastonite crystals. Especially, the formation of the crystalline layer in the Ba2DyAlO5 sample is the fastest. This study also reveals that Ba is a useful element for altering CMAS composition to precipitate celsian. Thus, doping Ba2+ in yttria partially stabilized zirconia or other novel TBCs might be an attractive way of mitigating CMAS attack.