A Comparative Study on the Corrosion of Galvanized Steel under Simulated Rust Layer Solution with and without 3.5wt%NaCl

A comparative study of the corrosion behavior of galvanized steel under 3.5wt% NaCl and chloride-free simulated rust layer (SRL) solution was investigated using polarization curve and electrochemical impedance spectroscopy (EIS). The morphology, organization and chemical properties of the rust layer were detected by scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). The results indicated that the rust layer could inhibit the corrosion of galvanized steel in chloride-free SRL solution, both of the resistance of rust layer (Rf) and charge transfer resistance (Rct) increased with the increase of immersion time. However, non-uniform corrosion occurred on the galvanized steel in the SRL solution containing 3.5wt% NaCl, the rust layer absorbed on the electrode was gradually destroyed under the erosion of Cl-.