Preparation of passive Cu–Ni–Fe coating on low-carbon steel for improving corrosion resistance

Cu–Ni–Fe alloy coating was prepared on low-carbon steel by surface alloying. The surface heat treatment of coated low-carbon steel was performed at 700 °C, 800 °C, 900 °C and 1000 °C for 3 h under hydrogen atmosphere. The structure and microstructure of coatings were separately analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). A series of electrochemical analysis was carried out to examine the corrosion resistance of Cu–Ni–Fe alloy coatings in borate buffer solution. Results indicated that a uniform and homogeneity Cu–Ni–Fe alloy coating constituted of γ-phases was prepared on the surface of low-carbon steel at 1000 °C, which promoted the formation of compact passive film. The passive film significantly improved the substrateʹs corrosion resistance in alkaline solution.