A Novel Method for Corrosion Reaction Analysis by Fourier Transform Electrochemical Impedance Spectroscopy: Corrosion of 9Cr-1 Mo Ferritic Steel in 0.050M H2SO4

We hereby report a novel method of analyzing corrosion reactions by real-time Fourier transform electrochemical impedance (FTEIS) spectroscopy and applied it to the corrosion study of 9Cr-1 Mo ferritic steel in 0.050M sulfuric acid. The real-time monitoring was achieved by running small signal staircase linear sweep voltammetric experiments, in which each voltage step and the chronoamperometric current obtained thereupon were converted to impedance data by first converting them into frequency domain employing Fourier transformation followed by acquisition of impedance spectra. The technique provided real-time potentiodynamic impedance data in real time while the potential was being swept. A large body of impedance data thus obtained as a function of swept potential allowed not only corrosion potentials and currents but also a full set of kinetic parameters of reactions involved in corrosion to be evaluated. The quantitative data obtained for corrosion also help better elucidate the corrosion mechanism at the steel electrode/electrolyte interface.