La2O3-modified YSZ coatings: High-temperature stability and improved thermal barrier properties

Abstract Lanthana precursor was coated on yttria-stabilized-zirconia (YSZ) powders by wet chemical infiltration, and was introduced to the crystalline structure and grain boundaries of YSZ after plasma spraying of thermal barrier coatings (TBCs). The microstructural stability and thermal barrier properties of this new kind of TBCs were studied under different annealing conditions. It demonstrates that the La 2 O 3 surface coating restrains grain growth of YSZ during both deposition and post-annealing processes, compared to a TBC obtained from commercially available unmodified YSZ powders. According to the composition analysis, lanthana partially dissolved in the zirconia matrix after heat treatment. The thermal diffusivity of YSZ coating significantly decreased after lanthana modification, typically from 0.354 mm 2 s − 1 for an unmodified sample to 0.243 mm 2 s − 1 , reflecting a decrease of 31%. Even after annealed at 1200 °C for 50 h, the thermal diffusivity of modified coatings still shows a reduction of 25% than unmodified samples.