Optimizing structural and compositional properties of electrodeposited ceria coatings for enhanced oxidation resistance of a nickel-based superalloy

Abstract Cathodic electrodeposition was used to generate ceria coatings onto a Ni-based superalloy substrate. The electrochemical parameters were optimized so as to obtain relatively thick but adherent films with tailored composition and microstructural features (multi-cracked network) designed for high temperature applications. Whereas the applied current density was shown to mainly influence the appearance and size of the cracks as well as the amount of oxygen vacancies, the linear trend between the deposited mass and the deposition time allowed a good control of the deposited thickness. A crystallization/diffusion thermal treatment was then applied to promote the dehydration of the deposit, thus resulting in a network of refined cracks, and in the complete crystallization of nanometric CeO2−x exhibiting either a needle-like or a quasi “foam-like” microstructure depending on the applied temperature. This also provided the establishment of an inwardly grown α-Al2O3 scale at the substrate/coating interface expected to further increase the high temperature oxidation resistance of the coated superalloy.