Corrosion film breakdown of galvanized steel in sulphate-chloride solutions

This work presents the corrosion performance of galvanized steel in sulphate-chloride solutions. The surface area changes, film breakdown susceptibility, and protectiveness of the corrosion products were studied using Potentiodynamic Polarization, Cyclic Voltammetry, Cyclic Polarization, and Electrochemical Impedance Spectroscopy. Samples immersed in MgCl2 solutions had the lowest corrosion rate, while samples immersed in the NaCl solutions showed the worst performance. The longer expected durability of samples immersed in MgCl2 was attributed to the lower corrosion kinetics, and a greater surface coverage by the corrosion product. However, results show that the formed corrosion layer is non-protective under any of the studied conditions.