A method was developed to determine the faradaic impedance (Zf) of an electrode reaction on the basis of a measurement of the electrode impedance (Z). Neither the reaction mechanism nor the equivalent electric circuit needed to be known. Zf was determined by a method based on determination of the minimum of the length of the electrode admittance diagram minus the capacitive term. A similar method applied to Zf could be used to obtain the electronic transfer and electrode polarization resistances (Rt and Rp, respectively) automatically and thus the corrosion rate for measurements carried out at the corrosion potential (Ecorr). The proposed method was applied to zinc (Zn) corroding in a 3% sodium chloride (NaCl) solution.

Subject
Circuits, Corrosion rate, Sodium chloride, Impedance, Electrolyte resistance, Minimization, Capacitance, Constants, Impedance measurements, Metals, Immersion, Polarization resistance, Electrodes
Keywords:
electrochemical impedance spectroscopy, faradaic impedance, polarization resistance, transfer resistance
NACE International
1995
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