Role of Ni content in improvement of corrosion resistance of Zn–Ni alloy in 3.5% NaCl solution. Part I: Polarization and impedance studies

Zn plays an important role in the protection of iron and steel from corrosion in sea water, and the alloying of Zn and Ni can improve its corrosion resistance. The corrosion behavior of Zn–Ni alloys in synthetic sea water (3.5% NaCl, mass fraction) was studied using Tafel plot and electrochemical impedance spectroscopy (EIS) techniques. The corrosion resistance of the investigated alloys with various Ni contents (0.5%–10%, mass fraction) was compared with that of Zn. The results show that the corrosion resistance of Zn–Ni alloys (except 0.5% Ni) is superior to that of Zn. The 10% Ni gives the highest corrosion resistance due to the formation of γ-Zn₃Ni with γ-ZnNi phases in the alloy. In the case of alloy I (0.5% Ni), it exhibits a higher corrosion rate (less corrosion resistance) than Zn.