Abstract
This study investigates the fabrication of stoichiometric gadolinium niobate (GdNbO4) coatings using plasma spraying, leveraging the unique characteristics of the process, such as elevated feedstock temperatures and rapid solidification of deposited particles. Various stoichiometric compositions of Nb2O5/Gd2O3 powders (NG 1.0, 1.2, and 1.4) served as the initial feedstock. Scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) analysis revealed a uniform elemental distribution in the coatings, while X-ray diffraction (XRD) confirmed the presence of GdNbO4, alongside Nb2O5 and Gd2O3 phases in the initial powders. X-ray fluorescence (XRF) analysis indicated the 20-45% evaporation of the Nb2O5 phase in the coatings, with compensation observed in the NG1.2 and NG1.4 formulations. GdNbO4 coating with the stoichiometric ratio of Nb2O5/Gd2O3=1.0 has been achieved at P2G1 for NG1.2 and for NG1.4 powder at P2G3 and P3G1 parameters. Additionally, Raman spectroscopy and high-resolution transmission electron microscopy (HRTEM) affirmed the successful synthesis of GdNbO4 coatings. Notably, the coating with the achieved stoichiometric ratio of 1.0 exhibited no phase changes up to 1273K in in-situ XRD tests and demonstrated impressive thermal durability, achieving nearly 550 cycles in high-temperature plasma conditions. Hardness and Young’s modulus were measured at 6.64 GPa and 129.8 GPa, respectively, highlighting the potential of this novel material for next-generation thermal barrier coatings.
Published Version
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