1999 Volume 67 Issue 10 Pages 960-967
The anodic dissolution mechanism of Fe-Ni alloy was investigated by an electrochemical impedance spectroscopy (EIS). The Fe (II) and Ni(II) dissolved from Fe-Ni alloy electrode were detected simultaneously during the polarization curve measurement by a channel flow electrode system. The preferential dissolution of Fe (II) was observed at low anodic potentials, and the dissolution rate of Fe(II) was controlled by Ni content significantly. Nyquist plot of electrochemical impedance of Fe-Ni alloy electrode shows an inductive semicircle and negative resistance. These unique loci were explained by the formation of adsorbed intermediates Fe(I)ad and Ni(I)ad. The numerical simulation was performed for the experimental results of polarization curves, dissolution currents of Fe (II) and Ni(II) and electrochemical impedance responses. The dissolution mechanism was discussed on the basis of the kinetic parameters obtained by the simulation.
