Based on the capabilities of the HVOF process for MCrAlY coatings on nickel-based superalloys, the aim of this project is to develop the coating technology of NiCoCrAlTaY modified with the alumina nanoparticles on a single-crystal CMSX-4 nickel-based superalloy by HVOF method. In order to compare the oxidation process of the samples with a reference coating, aluminizing process was used. To create a nanocomposite coating, alumina nanoparticles along with NiCoCrAlTaY powder were agglomerated by preparing a suspension and then HVOF process was used. The effect of the percentage of nanoparticles (3, 6 and 9% by weight) on the coating was discussed. In this regard, the characteristics of the nanocoatings, such as roughness, porosity and micro-hardness were eva‎luated. Furthermore, the mechanism of alumina nanoparticles on improving the oxidation resistance of the coating was disscused. The results showed that the increase of alumina nanopowder up to 6% wt with the formation of a dense layer of Al2O3 had led to the improvement of oxidation resistance by reducing the thickness of the oxide layer and β depletion zone. A further increase in nanoparticles led to significant increase in the porosity and roughness of the coating resulted in a decrease in oxidation resistance.

احمد كرمانپور , فخرالدين اشرفي زاده

احمد كيواني

مهران نحوي , علي اشرفي , سعيدرضا بخشي