study of the Corrosion Behavior of Mild Steel in Sodium Chloride Solution with Zinc Phosphate Pigment Extract and Organic Inhibitor

One of the approaches for improving the protective performance of organic coatings is to add organic corrosion inhibitors in the formulation. The scope of this research is to investigate the corrosion behavior of mild steel in 3.5% sodium chloride solution with zinc phosphate anticorrosion pigment (ZP) and 2-mercaptobenzimidazole as organic inhibitor through taking advantage of electrochemical impedance spectroscopy (EIS) and polarization measurements. The results which were obtained from electrochemical tests on the samples within 24 hours of immersion in the solution indicated superior protective performance of the combination of zinc phosphate anticorrosion pigment and 2-mercaptobenzimidazole inhibitor compared to only the zinc phosphate pigment. In general¡ time variations of parameters charge transfer resistance (Rct) which was obtained from electrochemical impedance spectroscopy and polarization resistance (Rp) as well as corrosion current density (icorr) which were extracted from polarization curves implied precipitation of a protective layer on the surface in the presence of 2-mercaptobenzimidazole inhibitor.