Vertical grain and columnar structured Ba(Mg_1/3Ta_2/3)O₃ thermal barrier coating deposited by solution precursor plasma spray

Thermal barrier coatings (TBC) with a lamellar structure are more susceptible to erosion than fully dense ceramics and electron beam physical vapor deposited (EB-PVD) coatings. This paper presents a distinctive structure of Ba(Mg_1/3Ta_2/3)O₃ (BMT) with a columnar-oriented appearance and vertical grain nature, which was deposited by plasma spray rather than EB-PVD. Indeed, a radio frequency solution precursor plasma spray (RF SPPS) process was adopted for the coating deposition. The morphology and elemental composition of the vertical grains are analyzed first. With the assistance of optical emission spectroscopy (OES), the formation mechanism of the vertical grains is discussed in detail. In addition, a new TBC system designed for niobium alloy is proposed in this paper. Owing to its high thermal expansion coefficient and unique vertical grain structure, BMT has been considered as the most promising insulation material candidate in this TBC system.