The Performance of Zinc Sacrificial Anode in Simulating Marine Fouling Environment

Zinc sacrificial anodes with excellent merits are widely used in the marine cathodic protection of steel structures being suffered marine biofoulings. It is important to study the property of zinc anodes in marine fouling environment. However, it is very difficult to study the effect of macro-fouling on the corrosion of zinc anodes in the real ocean environment, and it is also almost impossible for the people to do this by culturing the macro-fouling in lab. In this work, the corrosion behaviour and performance of zinc anode in simulated marine fouling environment was discussed using electrochemical impedance spectroscopy, self-discharge, scanning electron microscopy and simulating methods. The results indicated that marine foulings on the surface had some protective effect on the anti-corrosion performance of anodes in the early attachment stage of fouling organisms. The corrosion rate of zinc anode was decreased sharply at the first attachment stage of the fouling organisms. The zinc sacrificial anode still possesses high current efficiency though covered with biofoulings, but its potential varies dramatically in simulated biofouling environment. Surface analysis revealed that localised corrosion occurred on the surface of zinc sacrificial anodes coated with the powder of barnacles and oysters. The experiment result shows that it is very useful and simple for us to study the effect of macro-fouling on the corrosion of zinc anodes in lab by simulating the coating of the powder of barnacles and oysters, which is consistent with the actual marine results.