Thermal cycling performance assessment of double-layered lanthanum titanium aluminate thermal barrier coatings developed using plasma spheroidized powders

In this present investigation, lanthanum titanium aluminate (LTA) powder is prepared by solid-state sintering followed by spheroidization through an atmospheric plasma spray torch within a spheroidization chamber. The spheroidized powder is used to deposit thermal barrier coatings (TBCs). The developed coatings were evaluated for thermal cycling performance at 1150 °C, and the phase and microstructural observations were carried out before and after thermal cycling. A continuous layer of alumina (Al2O3) thermally grown oxide (TGO) is grown at the interface of the NiCoCrAlY bond coat and YSZ top coat in both coatings. The higher TGO growth rate kinetics beyond the critical thickness-induced thermal stresses and the associated coefficient of thermal expansion (CTE) mismatch between the TGO and the top coat resulted in the delamination of the coatings.