Local electrochemical behavior of 2A12 aluminium alloy in the initial stage of atmospheric corrosion under Cl- conditions
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摘要: 用掃描開爾文探針(SKP)和局部電化學交流阻抗(LEIS)技術,研究了2A12鋁合金在鹽霧腐蝕實驗早期階段的腐蝕行為和電化學過程.結果表明,鹽霧實驗初期,鋁合金表面出現點蝕坑,Cl-對鋁合金腐蝕有顯著的加速作用,隨鹽霧時間延長,點蝕擴展.掃描開爾文探針的測試結果顯示,在鹽霧腐蝕過程的初期,金屬表面陰極區和陽極區不斷發生變化,呈現局部腐蝕的特征.隨著鹽霧時間的延長,試樣表面電位逐步正移,并出現明顯的陰極區和陽極區.局部電化學交流阻抗的測試結果表明,試樣表面的局部電化學阻抗隨鹽霧時間的延長而有所增加,但分布較為分散.這說明在腐蝕過程的初期,2A12鋁合金表面不斷生成腐蝕產物,對腐蝕反應產生阻礙作用.Abstract: Scanning Kelvin probe (SKP) and localized electrochemical impedance spectroscopy (LEIS) were employed to investigate the corrosion process and electrochemical behavior of 2A12 aluminium alloy during the initial corrosion period. It is shown that Cl- accelerates the atmospheric corrosion of 2A12 aluminum alloy and pitting expands with exposure time during the initial stage. SKP results indicated that anodic and cathodic areas on the surface changed constantly with distinct characters of localized corrosion in the initial corrosion period. When the corrosion process continued, the surface potential of 2A12 aluminium alloy moved positively, while the anodic and cathodic fields distinguished evidently from each other. LEIS results showed that the surface localized electrochemical impedance in the initial stage increased with time, but distributed dispersively. During the initial stage of the corrosion process, corrosion products formed on the surface of 2A12 aluminium alloy constantly, which could restrict the corrosion process.
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Key words:
- aluminium alloys /
- salt spray test /
- atmospheric corrosion /
- electrochemical behavior
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