Variable-Amplitude Galvanostatically Modulated Impedance Spectroscopy as a Tool for Assessing Reactivity at the Corrosion Potential Without Distorting Temporal Evolution of the System Available to Purchase

An algorithm was developed in which galvanostatic regulation of electrochemical impedance measurements is conducted with an amplitude of current perturbation that is adjusted at each frequency to yield a desired variation in potential. Measurements of three previous frequencies are used to estimate the value of the impedance at the target frequency. The algorithm was implemented using a graphically based general interfacing software on a personal computer. Experimental results illustrated artifacts that can arise as a result of galvanostatic measurement with a fixed current amplitude or as a result of potentiostatic measurements for systems with a changing corrosion potential. A demonstration was presented of the use of variable-amplitude galvanostatically modulated impedance spectroscopy to monitor corrosion of copper in synthetic seawater.