Tafel Slopes and Corrosion Rates from Polarization Resistance Measurements

A new analysis of polarization curves in the non-Tafel region in the vicinity of the corrosion potential is described which allows calculation of the polarization resistance (Rp) and the Tafel slopes (ba and bc). From these data instantaneous corrosion rates are calculated. Experimental data for the system Fe/1N H2SO4 are analyzed by the proposed method and by computer least square analysis. The good agreement observed suggests that all important corrosion parameters (corrosion potential, corrosion current, Tafel slopes) can be obtained by the proposed analysis. These parameters are used for mechanistic considerations which explain the observation time dependence of corrosion potential and corrosion current.