Comparison of pure and white cast iron dissolution kinetics in highly alkaline electrolyte

Electrochemical impedance spectroscopy was used to compare the anodic disso lution kinetic of pure and white cast iron in 14 M NaOH. It was found that iron carbide in the anode material causes an apparent decrease in the surfa ce oxide layer resistivity and consequently in the protective properties. A lso the potential of the anodic end of the passivity region is moved toward s more cathodic potential. The changes of the impedance spectra with electr ode potential and electrolyte temperature are reported. (C) 1999 Elsevier S cience Ltd. All rights reserved.