Characterization and corrosion studies of ternary Zn−Ni−Sn alloys

Nine distinct zinc-nickel-tin films with different compositions have been galvanostatically electrodeposited. The films have been characterized by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). Their corrosion potentials and densities have been estimated using Tafel extrapolation. Next, the electrochemical behaviors of the films (deposited through the electrolytes containing 0, 6, 8, and 10 g/L SnCl₂∙6H₂O) have been examined based on cyclic voltammetry (CV) measurements. Further, these films have been immersed in 3.5wt% NaCl solution for 1 h, 1 d, 7 d, 14 d, 28 d, and 42 d followed by application of Tafel extrapolation and electrochemical impedance spectroscopy (EIS) tests on each aged sample. Finally, to analyze the morphologies and the compositions of the oxide films covering the surfaces of the 42-d aged films, FT-IR and SEM analyses have been performed. The results indicated that the Zn–Ni–Sn film produced through the bath including 6 g/L SnCl₂∙6H₂O exhibits superior corrosion resistance because of the high Ni content in the presence of Sn that promotes the barrier protection capability of the deposit.