Thermal Stability of Lanthanum Zirconate Plasma‐Sprayed Coating

Abstract

Lanthanum zirconate (La 2 Zr 2 O 7 , LZ) is a newly proposed material for thermal barrier coatings (TBCs). The thermal stability of LZ coating was studied in this work by long‐term annealing and thermal cycling. After long‐term annealing at 1400°C or thermal cycling, both LZ powder and plasma‐sprayed coating still kept the pyrochlore structure, and a preferred crystal growth direction in the coating was observed by X‐ray diffraction. A considerable amount of La 2 O 3 in the powder was evaporated in the plasma flame, resulting in a nonstoichiometric coating. Additionally, compared with the standard TBC material yttria‐stabilized zirconia (YSZ), LZ coating has a lower thermal expansion coefficient, which leads to higher stress levels in a TBC system.