外來銅離子對鋁合金散熱器孔蝕腐蝕之影響

Effects of Extrinsic Cupric Ions on Pitting Corrosion of Aluminum Radiator

鋁合金在含氯離子環境下發生孔蝕腐蝕（pitting corrosion）是自發性的行為，鋁合金表面若存在有外來的銅離子將會加速腐蝕。本研究使用電化學雜訊量測分析（electrochemical noise analysis）、浸泡試驗（immersion test），評估鋁合金在氯離子、硫酸根、銅離子和銅粉中的腐蝕速率，並由橫截面觀察蝕孔（pits）形貌和腐蝕生成物分佈。結果顯示在含銅離子的環境下，鋁合金表面的電流密度較高，反應速度增快，造成純銅顆粒沈積，產生蝕孔和腐蝕生成物，本文乃就此研究結果提出合理的反應機制。

Pitting corrosion is relatively easy to appear on aluminum alloys in environments with chloride ions (Cl-). Meanwhile, extrinsic cupric ions that contaminate the surfaces of aluminum alloys would lead to increases in corrosion rate. This study focuses on the effects of cupric ions on pitting corrosion of aluminum alloys. The corrosion rate of the tested alloy was determined by electrochemical noise analysis (ECN) and immersion test. Cross-sectional morphologies of pits and corrosion products were observed using optical microscope and scanning electron microscope. The results showed that the presence of cupric ions led to an increased corrosion current density of the alloy and the deposition of pure copper and the formation of pits on the surface. Possible mechanisms are discussed.