Microstructural and Electrochemical Characterization of Zinc Coating onto Low Carbon Steel Substrate

Ordinary steels have poor corrosion resistance in chloride medium leading to a deterioration of their longevity. The present research work focuses on the deposition and characterization of a zinc layer by dip galvanizing onto low carbon steel ASTM A283M-98 in sheet form using different characterization techniques such as optical microscopy, scanning electron microscopy (SEM) coupled to energy dispersion spectrometer (EDS), atomic force microscopy (AFM) and X-ray diffraction (XRD). Optical microscopy and X-ray diffraction analyses of the steel reveal a ferritic microstructure with the presence of a small amount of pearlite. The deposited layer is composed of four Fe–Zn intermetallic phases, namely eta (η), zeta (ζ), delta (δ), and gamma (Γ). The electrochemical study in 0.5M NaCl medium indicate an enhancement of the corrosion resistance of ASTM A283M-98 steel coated with Fe–Zn multi-phased layer, characterized by a decrease in corrosion current ( I corr = 3.36μA/cm 2 ) and corrosion rate (Cr = 0.29mm/year) compared to the bare steel ( I corr = 12.29μA/cm 2 and Cr= 0.72mm/year).