ANALYSIS OF THE IMPEDANCE RESPONSE OF PASSIVE IRON

The impedance response of passive iron is described in terms of a mode l that takes into account the electrochemical processes taking place a t both the metal/oxide and oxide/electrolyte interfaces and the influe nce of the ionic transport in the passive film. The comparison of the theoretical transfer function with experimental data corresponding to iron passivated in aqueous boric acid-borate buffers leads to the conc lusion that the potential perturbing signal does not interfere with th e equilibrium of the layer formation reactions (deposition and removal of oxygen ions), the faradaic impedance being related to the iron dis solution through the passive film.