Electrodeposition and Corrosion Resistance of Cu/Zn/Cu Multilayer Coatings

Cu/Zn/Cu multilayer coatings were prepared on mild steel substrates by dual bath technique in order to improve the corrosion resistance of mild steel in seawater. The microstructures of the coated substrates and its resistance to corrosion in simulated seawater were evaluated by scanning electron microscopy (SEM), the brine immersion test and electrochemical impedance spectroscopy (EIS). Salt water immersion test results show that the Cu/Zn/Cu multilayer coatings exhibited the highest corrosion resistance. The red rust spot appeared on the coating surface for the first time when the time of the coating soaked in salt water reached 2520h. The trend of the impedance variation reflected by the electrochemical impedance spectroscopy was the same as the change tendency of corrosion resistance was analyzed by the salt water immersion test. The results of SEM showed that the layer of copper were deposited by round cell structure, the middle layer of zinc coating was flat and compact.