ELECTROCHEMICAL PERFORMANCE OF ZINC ALLOY SACRIFICIAL ANODE IN SEA WATER UNDER WET-DRY CYCLIC EXPOSURE CONDITION

The electrochemical performance of a Zn-Al-Cd alloy sacrificial anode was studied in seawater upon wet-dry cyclic exposure.The morphology of the corrosion products and the dissolution behavior of the anode surface were examined.With the increase of wet-dry cycles,the working potential of the zinc alloy anode moved gradually in the positive direction,while the electrochemical activity of the anode reduced and its current efficiency decreased significantly.The corrosion product of the anode after cyclic exposure was denser than that after full immersion in seawater and the dissolution of the anode suface for the former was not as uniform as for the latter.The decrease of anode activity and current efficiency could be mainly attributed to the formation of dense corrosion product and localized corrosion at the anode surface.