Protection Current Degradation Modeling and Life Evaluation Method of Sacrificial Anodes for Marine Structures

In this paper, the relation model between anti-corrosion coatings and cathodic protection by sacrificial anodes for marine structures is established from the perspective of electrochemical theory. On this basis, the influence of different protection current densities on coating cathodic disbondment is analyzed. The inverse power law model of coating cathodic disbondment is determined by the data of coating accelerate cathodic disbondment test. The protection current degradation model of sacrificial anode is established based on the mixed potential theory and polarization theory. Finally, according to the physical and electrochemical parameters of the sacrificial anode, the lifetime evaluation method of the sacrificial anode considering the cathodic disbondment of coating is proposed. The results of case analysis show that the sacrificial anode protection current model can effectively describe the consumption state of sacrificial anode. In addition, the coating disbonded area and the protective current of sacrificial anode increase with time, while the protective current density decreases with time.