Brass dezincification in a tap water bacterial suspension

M.B. VALCARCE; S.R. DE SÁNCHEZ; M. VÁZQUEZ

ELECTROCHIMICA ACTA

Elsevier

Lugar: Amsterdam; Año: 2006 vol. 51 p. 3736 - 3742

0013-4686

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 (ATW) pH 7.6. For comparison, a bacterial suspension, labelled as BATW, was also used. The surface films were grown at open circuit potential for 2 hs. Different techniques such as potentiodynamic reduction curves, polarization curves, polarization resistance (Rp), impedance spectroscopy (EIS) and reflectance spectroscopy were used. The dezincification associated to the presence of bacteria was reveled by the disappearance of the peak attributed to Zn(II) reduction in the potentiodynamic reduction curves, and also by changes in the spectra. No significant differences were observed between the fitting parameters of the impedance spectra. The Rp values obtained by potential sweeps, as well as by EIS were in good agreement. The Tafel slopes were found to increase in BATW. In BATW, the corrosion currents are higher than in ATW, particularly in the case of brass. This increment could be attributed to the higher Tafel slope and can be taken as an indication of the dezincification phenomenon.