Electrochemical Characterization of an Al-Zn-In Galvanic Anode

Abstract The electrochemical behavior of an Al-Zn-In anode was studied by means of the following techniques: Polarization Curve Measurements, Electrochemical Noise and Electrochemical Impedance, using two different electrochemical cell arrangements. The Electrochemical cell arrangements were: Al-Zn-In anode, saturated calomel electrode and platinum wire as the working electrode, reference and counter electrode, respectively (First System)Two identical Al-Zn-In as a working electiode (Second System) At different concentration levels of sodium chloride (NaCl), from 3% wt to 0.001% wt, the dissolution mechanism is not the expected for a good Al-sacrificial anode. It was found that the polarization resistance, Rp, values were upper-estimated when the traditional two-electrode setup is used. Electrochemical noise measurements gave the highest values of Rp. The corrosion attack, determined as a result of the Localization Index values obtained, suggests a change from localized pitting corrosion, to general corrosion behavior during the time of exposure. The response of the different electrochemical techniques is related to the sodium chloride concentration and by the electrochemical cell arrangement chosen. In this work, the two working electrodes cell configuration showed to be the better one.