Crack Formation and Corrosion Behavior of 6061 Al Alloy in Sulfuric Acid

6061鋁合金於硫酸溶液中進行陽極氧化處理的薄膜裂痕形成與耐腐蝕行為之研究

鍾逸駿(I-ChunChung) ； 鍾震桂(Chen-Kuei Chung) ； 蘇炎坤(Yan-Kuin Su)

《中國機械工程學刊》 39卷3期 (2018/06) Pp. 287-293

摘要

The 6061 aluminum alloys (AA6061) specimens were anodized in the sulfuric acid solution. The crack formation and corrosion behavior of the AA6061 oxide films were investigated in a wide range of sulfuric acid concentration (1~5 M) and current density (0.3~3 A/dm^2). A number of cracks were formed on the surface of the anodized AA6061 oxide film at a high electrolyte concentration of 5 M and low current density of 0.3 A/dm^2. Moreover, increasing current density could suppress crack formation at a high concentration of 5 M while decreasing electrolyte concentration was also helpful for eliminating cracks at a constant current density of 1 A/dm^2. The more the cracks, the higher the corrosion current was. Suppressing crack formation was crucial for promoting corrosion resistance of the AA6061 film with less corrosion current. The best corrosion resistance of the anodized film with I_(corr)=1.433×10^(-10) A/cm^2was obtained at a current density of 1 A/dm^2 and a concentration of 1 M sulfuric acid, that could be potentially used for long-term anti-corrosion coatings on many AA6061 alloy products.

關鍵字

Anodic aluminum oxide ； Crack ； Corrosion ； AA6061

並列摘要

本文主要是使用6061鋁合金製作陽極氧化薄膜，採用硫酸當作陽極處理過程的電解液，探討在大範圍的硫酸濃度（1~5 M）與電流密度（0.3~3A/dm^2）對於陽極氧化膜裂痕的形成以及耐腐蝕行為的影響。在高的硫酸濃度（5 M）與低的電流密度（0.3 A/dm^2）時，陽極氧化薄膜表面發現許多裂痕形成，當在較高的硫酸濃度時增加電流密度將抑制陽極氧化薄膜裂痕的形成；當電流密度固定在1A/dm^2時降低硫酸濃度亦有助於消除裂痕。當裂痕數量越多時，腐蝕電流密度則越高代表耐蝕性越差，抑制裂痕的形成將導致腐蝕電流變小代表有助於耐蝕性能提升，本研究最佳耐蝕性是當電流密度為1 A/dm^2，硫酸濃度為1 M時腐蝕電流密度為I_(corr)=1.433×10^(-10) A/cm^2。