Tailoring the stoichiometry in NdNbO4 for advanced thermal barrier coating applications

RENbO4 ceramics have the potential to serve as a viable alternative to YSZ for advanced thermal barrier coatings. However, the fabrication of stoichiometric plasma spray RENbO4 coatings remains unexplored. Herein, we proposed a strategy to deposit a stoichiometric NdNbO4 coating using the atmospheric plasma spray technique. This was accomplished by the addition of excess Nb2O5 in feedstock powder to compensate for the evaporated Nb2O5 during the plasma spray process. The influence of powder composition and critical plasma spray parameters (CPSP) on the microstructure and phase formation of NdNbO4 coatings were characterized. Further, quantitative assessment of Nb2O5 evaporation with varying plasma parameters was also characterized using energy-dispersive X-ray fluorescence spectroscopy. Moreover, the support vector machines (SVM) model was used to construct a relation between the initial powder composition, CPSP, and stoichiometry of the coating. This strategy can be used for the fabrication of stoichiometric RENbO4 coatings for next-generation thermal barrier coatings.