Potentiodynamic studies on corrosion of copper by chloride ions and its inhibition by inorganic and organic ions in aqueous buffer solution

Abstract

Electrochemical oxidation of copper in aqueous phosphate buffer solution leads to the formation of passive films, which breakdown in the presence of aggressive chloride (Cl−) ions. The addition of Cl− ions in the medium causes shift in current and potential for both cathodic and anodic peaks. At low Cl− ion concentrations, the corrosion current is greatly enhanced and continues to increase up to a certain concentration, after which it decreases. The effect of inorganic ions, chromate (CrO42−) and tungstate (WO42−), and organic ions, acetate (CH3COO−) and oxalate (C2O42−), on the formation and breakdown of passive films in aqueous buffer solution containing 0.10 M Cl− ions have also been investigated. All of the ions inhibit corrosion of copper in the presence of aggressive Cl− ions following the order of overall inhibition efficiency of CrO42− > C2O42− > WO42− > CH3COO− under the experimental conditions.