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 1 st 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 2 nd cell, which represents the i corr of the 1 st 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 .