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Corrosion and cavitation erosion properties of sub-micron WC-Co /Cr3C2-NiCr multi-layered coating on aluminium substrates

Marine and automobile components are subjected to corrosion and cavitation erosion during their service. This paper aims to study the use of hard coatings on aluminium substrates with multiple layers of coating comprising of sub-micron sized WC-Co and Cr3C2-NiCr for enhancement of hardness, corrosion and cavitation erosion properties. Coatings are applied on aluminium substrates using high-velocity liquid fuel (HVLF) spray technique and the coating parameters are optimized for best results. The results indicate that multiple layered coating with alternate film coatings of Cr3C2-NiCr & submicron WC-Co has significantly improved the hardness of aluminium surface. The resistance to corrosion with multiple layers of coating is found to be exceptional and similar to monolayer Cr3C2-NiCr coating. Cavitation erosion tests performed as per ASTM G32 show that coating with multiple layers could resist the erosion of materials under dynamic conditions. The number of layers in the multiple-layer coatings strongly affects the hardness, corrosion and cavitation erosion properties.