The influence of polypyrrole films on the corrosion behavior of iron in acid sulfate solutions

The corrosion behavior of mild steel covered by electrodeposited polypyrrole films was investigated by electrochemical impedance spectroscopy. Electrodeposition of polypyrrole was performed from an aqueous solution of pyrrole and oxalic acid at a constant current density of 1 mA/cm(2) and yields strongly adherent and smooth polymer layers. The non-linear least squares (NLS) fitting was applied to the impedance spectra to estimate the parameters of the proposed equivalent circuit, based on a physical model for the corrosion of mild steel protected by polypyrrole films in acid sulfate solutions. (C) 1998 Elsevier Science S.A.