Microstructure and thermal shock resistance of Ba(Mg_1/3Ta_2/3)O₃ coatings prepared by suspension plasma spraying

To evaluate the feasibility of suspension plasma spraying (SPS) in enhancing the performance of thermal barrier coatings (TBCs), Ba(Mg_1/3Ta_2/3)O₃ (BMT) coating, a potential candidate ceramic coating material for TBCs, was prepared using SPS. The microstructure, phase composition, and thermal shock resistance of the coatings were characterized. The results indicate that SPS can deposit BMT coatings with a distinct columnar-like structure, significantly different from those prepared by atmospheric plasma spraying (APS). During water-quenching thermal shock tests from room temperature to 1150 °C, the double-ceramic-layer coatings composed of SPS-deposited BMT and APS-deposited YSZ endured up to 67 cycles, seven times more than BMT-YSZ coatings prepared by APS under identical conditions. This improvement is attributed to the columnar-like structure of SPS-deposited BMT coatings, which offers higher strain tolerance and effectively inhibits crack propagation, delaying coating spalling. The coating failure is primarily attributed to impurity phase formation in the BMT coating, its relatively low fracture toughness, and the growth stresses of the thermally grown oxides (TGO).