Thermal shock behavior of Ba(Mg1/3Ta2/3)O3-YSZ double-ceramic-layer thermal barrier coatings prepared by atmospheric plasma spraying

The Ba(Mg1/3Ta2/3)O3 (BMT) ceramic is considered a potential candidate material for thermal barrier coating (TBC) applications, due to its excellent thermophysical properties. However, the low fracture toughness and poor chemical compatibility with thermally grown oxides result in an inferior thermal shock performance of single-layer BMT coatings and greatly limit its application. In this study, BMT-yttria partially stabilized zirconia (BMT-YSZ) and BMT/20 wt% YSZ-YSZ composite double-ceramic-layer coatings were prepared by atmospheric plasma spraying, and their thermal shock behaviors were investigated in detail. The results indicate that the thermal shock performance of the BMT-YSZ coatings was significantly superior to that of single-layer BMT coatings. The spallation of the BMT-YSZ coatings was due to the stress generated by the Ba3Ta5O15 phase formed on the coating surface and the low fracture toughness of BMT. By employing the BMT/20 wt% YSZ-YSZ composite double-ceramic-layer structure, the thermal shock performance of the coatings could be further improved, because the addition of YSZ in the BMT layer effectively increased the fracture toughness of the coatings.