测量了达克罗涂层在海水中全浸不同时间的电化学阻抗谱（EIS），并用等效电路Ro(RpC)(RDQ)进行解析。结果表明：腐蚀过程中试样的极化电阻Rp、双电层电容C、扩散电阻RD均不断增大，且RD/Rp也一直增大。达克罗涂层的腐蚀初期为金属Zn的溶解，随着腐蚀的进行，腐蚀产物在膜内的累积导致钝化膜的有效厚度增加，Zn粉的牺牲阳极作用受到了限制；腐蚀后期主要是机械的壁垒保护作用，直到扩散和溶解作用超过壁垒作用后，涂层以点蚀的形式发生破坏。
The evolution of electrochemical impedance spectroscopy(EIS)and open circuit potential were obtained from dacromet-coating mild steel, which were fully soaked in seawater. The EIS was analyzed by the equivalent circuitRO (RpC) (RDQ). The resistance showed the increasing with immersing time of the polarization resistance Rp, douible layer capacity C,diffusion resistance RD and the value of RD/RP. The conclusion was drawn that Zn dissolved at the beginning of corrosion process of dacromet and its sacrificial anode effects were limited by the accumulation of corrosion products,which thickened the thickness of passivation coating. The physical barrier action was the prominent anticorrosive mean afterqards.Dacromet coating failed to protect the base for pitting afier the cooperation of diffusion and dissolution overtook the barier effects.
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