Preparation of NiCrAlY/nano-CeO2 powder with the core-shell structure using high-velocity oxy-fuel spraying process

In this study, NiCrAlY/nano-CeO2 feedstock powders with core-shell structure were prepared via ball-milling process and subsequent direct spraying of the powder into the water using high-velocity oxy-fuel (HVOF) spraying method. X-ray powder diffraction, scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS), Atomic absorption spectroscopy (AAS) and Ultraviolet-visible spectroscopy (UV-Vis) tests were utilized for characterization of the processed powders. Results indicated that powders with core-shell structure were successfully prepared using this method. In this regard, each core-shelled particle consisted of a relatively homogeneous and uniform nanocomposite layer (shell) including dispersed CeO2 nanoparticles on the surface of NiCrAlY together with ultra-fine grained structure. Furthermore, the absorbance spectra of the core-shelled powder is different from the ball-milled powder due to the homogenizing and stabilizing effect of CeO2 nanoparticles in the shell after direct HVOF spraying. The consequences of the Williamson-Hall plot analysis demonstrated that the core-shelled NiCrAlY/nano-CeO2 powder has smaller crystallite size and also has a considerable lattice strain compared to the conventional NiCrAlY powder owing to the rapid melting and solidification during direct HVOF spraying into the water.