Copper Corrosion in Industrial Waters. A Multimethod Analysis

The spectral analysis of the electrochemical noise produced by copper corrosion during exposures to artificial industrial waters of different pH values was compared to the results obtained by electrochemical impedance spectroscopy (EIS). The noise impedance spectra are in good agreement with EIS spectra. A particularly good agreement is found at low frequencies, thus allowing a correct estimation of the low-frequency limit of copper impedance spectra. Atomic absorption analysis was also performed to validate the findings of EIS and electrochemical noise analysis. Different techniques were used to investigate the nature of the surface films grown under different pH conditions: scanning electron microscope observations, electron probe microanalysis, Fourier transform infrared spectroscopy, and electrochemical reduction tests. Cu{sub 2}O was found to be the main corrosion product under all investigated conditions, while only traces of copper carbonate or basic copper carbonate were detected, with the exception of pH 3.0.