The corrosion behaviour of copper in neutral tap water. Part II: Determination of corrosion rates

Abstract

The corrosion rates of copper in neutral tap water have been determined using potentiodynamic polarization and a weight loss method. Under the condition of diffusion control of copper ions in oxide film, the instantaneous corrosion rates can be determined by extrapolating the straight line portion of E versus log i in the anodic direction to the corrosion potential. The reliability of this method is verified theoretically and the corrosion rates derived from this method are found to be consistent with those obtained by the weight loss method. The latter is ideal for average corrosion rate determination while the electrochemical method is superior for the evaluation of instantaneous corrosion rates. The polarization resistance (Rp) measured by an electrochemical impedance spectroscopy (EIS) method is also used to estimate instantaneous corrosion rates.