Brass dezincification in a tap water bacterial suspension

The dezincification of Al-brass under the influence of Pseudomona fluorescens in potable water is investigated. The experiments were carried out using artificial tap water, pH 7.6. For comparison, a bacterial suspension, was also used. Potentiodynamic reduction curves, polarization curves, polarization resistance and impedance spectroscopy as well as reflectance spectroscopy were used to characterise the surface films grown at open circuit potential. The dezincification associated to the presence of bacteria was revealed by changes in the reduction curves, and also by changes in the reflectance spectra. No significant differences were observed between the fitting parameters of the impedance spectra. The Tafel slopes were found to increase in the bacterial suspension. The corrosion currents are higher than in the inoculated electrolyte, particularly in the case of brass. This increment is attributed to the higher Tafel slope and is taken as an indication of the dezincification phenomenon. (c) 2005 Elsevier Ltd. All rights reserved.