Microstructure-electrochemical property correlation in electrodeposited CuFeNiCoCr high-entropy alloy-graphene oxide composite coatings

This study investigates the microstructure-electrochemical property correlation in high-entropy alloy-graphene oxide (HEA-GO) composite coatings. HEA coating containing Cu, Fe, Cr, Co, and Ni was electrodeposited over mild steel. Graphene oxide (GO) content in the coating was varied by changing the amount of GO in the electrolyte bath during the electrodeposition. Corrosion behaviour of the coatings was examined through potentiodynamic polarisation and electrochemical impedance spectroscopy methods. It was observed that with an increase in the GO amount, the corrosion resistance of HEA-GO composite coatings progressively increased. Microstructural charaterisation, using the transmission electron microscopy technique, revealed that the addition of GO enhanced the amount of Cr in the coatings and also produced a layered microstructure with Cu and Cr-rich layer covering the coating surface. Both these factors along with the impermeability of GO facilitated enhancement in the corrosion resistance. Major application areas that require protective coatings over mild steel are oil and gas pipe lines, structural components exposed to marine environments, automobiles, industrial cleaning, etc.