Electrochemical characterization of the effect of chloride and sulphate ions on zinc

Abstract

This study presents results obtained in the characterization of corrosion undergone by test samples of zinc in the presence of chloride and sulfate ions using electrochemical techniques (Tafel and Ecorr vs t). A simulation is presented for the major polluting agents in the Canary Island's atmosphere. The SO42- anion which is the intermediate product in the reaction of SO2 with metals is characteristic of industrial atmospheres, and the chlorides are due to the marine aerosol. The effect of each pollutant was studied separately, and later together, with the finding that the sulfate ion caused a greater corrosive effect than the chloride, especially at low concentrations (0.05 to 0.2M). When both ions are together they produce a synergistic effect, with the effect of the sulfate predominant. With 0.4M and 0.8M Na2SO4 solutions, weak amelioration phenomena were found. The techniques utilized demonstrated that zinc lost its anti-corrosion properties when exposed to aggressive ions such as Cl- and SO42-.