Effect of Zn Primer Coating on Electrochemical Properties in Seawater

Abstract

Conventional ships generated almost no cavitation erosion because they traveled at low speed. Thus, most ships have used painting, ICCP and sacrificial anode system. However, with the activation of international trading, and the increase of low-price, large-volume cargos, ships are becoming larger and faster. As a result, damages due to cavitations and corrosions have accelerated. Cavitation and erosion corrosions cause damages to materials by physical shock waves generated from the collapse of bubbles which are generated when the moving parts rotate in seawater. The stern in particular is exposed to more severe environment due to cavitation and high flow speed. When cavitation and electrochemical damages are combined with exposure to severe environment, it has serious impact on the life span of equipment. Therefore, this study investigated the electrochemical and cavitation characteristics in sea environment for Zn primer coating which is a pretreatment process of painting for rudders for ships. As a result, corrosion resistance improved, but erosion resistance did not.