A New Method For Corrosion Current Measurement: The Dual-Electrochemical Cell (Dec)

This paper presents the "dual electrochemical cell" (DEC) method, a new technique that allows monitoring of corrosion current (i(corr)) in real time with a corrosion potential (E-corr) that may change with time. In this method, the E-corr of a metal corroding in a solution containing the oxidant of interest is measured in the 1st cell. This potential is then continuously applied in real time to a second cell using the same metal electrode in the same solution but free of the oxidant, and the current of the 2nd cell, which represents the i(corr) of the 1st cell, is monitored. This setup allows direct measurement of i(corr) without having to polarize the corroding electrode away from E-corr. The advantages of DEC over conventional methods are that it does not require the corroding system to be at steady state, and avoids any ambiguities associated with the extrapolation of the measured current-potential relationship to extract i(corr). The i(corr) values obtained using the DEC method were compared with those obtained using conventional polarization techniques, using dissolved metal concentrations and surface analysis observations, and the results showed that the DEC method provides the most accurate measurement of i(corr). (c) 2020 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. For permission for commercial reuse, please email: permissions@ioppublishing.org.