Using electrochemical frequency modulation technique to detect corrosion of carbon steel in seawater
A system for electrochemical frequency modulation (EFM) measurement was set up, which consisted of a potentiostat, a laptop computer, a NI DAQ card and application softwares developed with LabVIEW 7.0.The system was used to detect the corrosion rate of carbon steel/seawater system.The influence of such test parameters as perturbation frequency on the EFM results was studied.The early corrosion rate for Q235 steel in Zhoushan seawater was determined in laboratory with the EFM technique as well as two general electrochemical techniques—analysis of the polarization curve in the vicinity of the corrosion potential and electrochemical impedance spectroscopy (EIS).The corrosion rate determined with EFM technique was a little higher than the real value due to the capacitance behavior influence, while the advantages of the EFM technique still make it an ideal candidate for detecting and monitoring the carbon steel coupons'corrosion at the marine corrosion test sites.