鋅犧牲陽極在3.5wt % NaCl中之電化學行為研究

Electrochemical Behavior of Zinc Sacrificial Anode in 3.5wt% NaCl Solution

本研究試以電化學技術檢測5種鋅犧牲陽極材料在3.5wt % NaCl溶液中之特性，藉由電化學線性極化法量測此等材料腐蝕速率與時間之關係，經6週之實驗結果顯示鐵含量偏高者或鋁含量偏低者，其腐蝕速率均較低，亦即活性較差；另由動電位極化曲線發現，鐵含量偏高或是鋁含量偏低之鋅犧牲陽極材料，其陽極反應較易被極化，故當陽極過電位為10mV時，所對應之電流值僅約為正常者之四分之一，此結果亦證明其活性之差異。此外，利用掃描式電子顯微鏡檢測試樣表面結果發現，鋅陽極表面腐蝕生成物受微量鋁元素影響，分呈顆粒狀和鱗片狀，其主要成分為Zn(OH)2。

Electrochemical techniques were used to study the characteristics of five zinc sacrificial anodes in 3.5wt% NaCl solution. The corrosion rate vs time was determined by linear polarization (or named polarization resistance). It was found that the anodes with high iron or low aluminum content exhibited lower corrosion rate, i.e., worse activity. From the potentiodynamic curves, it was also found that the less active anodes were much easier to be polarized anodically. Furthermore, the corresponding current for the less active anodes with 10 mV over-potential was only a quater of the normal ones. In addition, results of SEM image of the anodes, which had been immersed in 3.5wt%NaCl solution for 42 days, indicated that the corrosion products on the surface were influenced by aluminum element. The morphology of the corroded surface was divided into two types, i.e., particle-like and layer-like. The mainproduct was Zn(OH)2.