提升離岸風機結構物陰極保護用鋁陽極發生電量性質研究

Study on Improving Electrochemical Capacity of Aluminum Anodes for Cathodic Protection of Offshore Wind Structure

Al-Zn-In合金為常用於海洋結構物陰極保護系統之犧牲陽極材料，其合金與組織差異，均為影響其實際發生電量差異的主要變因。本研究針對不同Al-Zn-In合金，藉由微觀組織觀察、電化學特性與表面溶解形貌分析，探討於人工海水環境下，組織、實際發生電量與表面溶解形貌之間的相關性。試驗結果顯示，晶粒尺寸大小與分佈均勻性，為影響實際發生電量表現的關鍵因素。Al-Zn-In合金之晶粒愈細小，其底材內部缺陷數量相對較少且分散，對應的實際發生電量較高，且表面溶解較均勻。反之，當晶粒粗大且分佈不均勻時，其內部缺陷數量會明顯增加，且容易在晶界處形成連續分佈，導致材料於放電過程中，會伴隨局部腐蝕進而導致晶粒剝落的自腐蝕現象，成為實際發生電量降低的關鍵原因。

The Al-Zn-In alloy is the most commonly used sacrificial anode material for cathodic protection systems of marine structures. The alloy composition variation and microstructural characteristics of the sacrificial anode are key factors affecting the practical electrochemical capacity and performance of the anode. This work investigates the relationship between microstructure and the performance of practical electrochemical capacity and corrosion patterns in an artificial seawater environment for different Al-Zn-In alloy anodes. The test results indicate that the grain size and the uniformity of distribution are key factors influencing the practical electrochemical capacity of the anode. The finer the grains of the Al-Zn-In alloy, the fewer defects are present within the substrate. These defects tend to disperse individually, resulting in a higher practical electrochemical capacity of the anode, which exhibits a corrosion pattern that is more uniform. Unlike the previous alloy, the Al-Zn-In alloy exhibits coarser and unevenly distributed grains, resulting in a continuous distribution of internal defects at the grain boundaries. This results in the self-corrosion phenomenon and grain peeling, which is accompanied by localized corrosion during the discharge process. These factors play an essential role in explaining the observed reduction in the practical electrochemical capacity of the anode.