Reach On Cathodic Protection Control System Based On Electrochemical Impedance Spectroscopy

With the development of marine resources in recent years, The marine platform which mainly reinforced concrete materials is used for large scale. However, due to the complexity of the marine environment, Always subjected to corrosion hazard, Resulting in corrosion of steel, platform damage, economic losses and even casualties. Therefore, how to effectively corrosion of the corrosion of reinforced materials under the marine environment is corrosion protection has become a hot issue in recent years. At present, the corrosion protection method includes the covering corrosion protection layer, the selection of corrosion resistant material, and the cathodic protection. According to the domestic and foreign research status, Cathodic protection technology in electrochemistry is an effective protection technology. For cathodic protection technology, the optimum potential value is usually measured by empirical or cathodic polarization curves. But the scope of application of experience is very limited The inflection point voltage measured by the cathodic polarization curve did not correspond to the maximum polarization resistance of the electrode system and the maximum of the polarization resistance, The two methods of cathodic protection have the limitation of application and the accuracy of the defects. Through investigation, electrochemical impedance spectroscopy is very intuitive and accurate for determining the parameters of electrochemical system. And it has already achieved good results in the study of corrosion protection.In order to solve the problem of the accuracy of the cathodic protection, this paper improves the cathodic protection technology, A new method for determining the optimum protection potential of compulsory current cathodic protection by electrochemical impedance spectroscopy is proposed. And carry out experiments verification. The main contents of this paper are as follows:1. The development of cathodic protection technology in the marine environment and the development of electrochemical impedance spectroscopy are analyzed. The theoretical basis of electrochemical impedance spectroscopy is described in detail. The theoretical basis for the determination of the equivalent circuit and the application of electrochemical impedance spectroscopy in cathodic protection is provided. The corrosion mechanism and the compulsory current cathodic protection principle of the steel in the marine environment are analyzed, and the basis for the design of the cathodic protection scheme based on the electrochemical impedance spectra is analyzed.2. A feasible method for determining the optimum protection potential of compulsory current cathodic protection is proposed in this paper. The method is applied to cathodic protection of electrochemical impedance spectroscopy. The electrode system is perturbed by DC signal and AC signal and the electrochemical impedance spectra of the electrode system are analyzed in the frequency domain. To achieve the objective of determining the optimum protective potential in the cathodic protection of compulsory current. Under the control of the optimum protection potential value, The corrosion resistance of the electrode system is the largest. The corrosion degree is the smallest and the protection effect is the best.3. First build three electrode system, And the impedance spectra of the system were fitted by Zview software. The equivalent circuit of the electrode system is analyzed. Electrochemical impedance spectroscopy analysis of the open circuit state electrode system To determine the parameters of the equivalent circuit elements, including capacitance C (capacitor charging and discharging simulation charge transfer electrode system), electrode resistance (the effective parameters of characterization of electrode potential), solution resistance. Finally, the equivalent circuit and the element parameters are determined by the above. In the Matlab software, the electrochemical equivalent circuit of the corrosion system is modeled. The innovative application of DC signal and AC signal at the same time to the electrode system perturbation. The electrochemical impedance spectra, Nyquist and Potter diagrams of the polarization process were simulated by the electrochemical impedance spectra. And the analysis results of the cathodic polarization curves are compared. The optimal protection potential of the compulsory current cathodic protection is determined. The feasibility and accuracy of the proposed method for the application of electrochemical impedance spectroscopy and the determination of the optimum protection potential of cathodic protection were verified.