Role of Solution Chemistry on Corrosion of Copper in Tap Water: Effect of Sulfate Ion Concentration on Uniform and Localized Attack

A laboratory study was conducted of the corrosion of copper in synthetic tap waters with various chemistries under stagnant conditions at room temperature. The primary interest was the effect of sulfate ion concentration ([SO42−]) on general corrosion and localized attack. Short-term tests were conducted using electrochemical methods, but results were insignificant. Long-term experiments were conducted over eight months using the weight-loss method. Increases in [SO42−] in tap water resulted in an increased corrosion rate due to uniform attack. The effect of the ratio of bicarbonate ions ([HCO3−]) to [SO42−] also was investigated. A mechanism for this effect on the corrosion of copper was proposed and verified experimentally. Results yielded an acceptable equation relating the corrosion rate to [HCO3−]/[SO42−] over an exposure period of 2 months to 8 months under stagnant conditions.