Effect of surface damage on the corrosion resistance of 6005A aluminum alloy in simulated seawater
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摘要: 以6005A鋁合金商品實際產生的表面少缺陷、多缺陷試樣，以及作為比較的完全去除商品表面膜的人工磨制的三種不同表面狀態試樣為研究對象，研究鋁合金商品表面的實際損傷對其耐海水腐蝕性能的影響及其腐蝕電化學行為.通過場發射掃描電鏡和激光共聚焦掃描顯微鏡對具有不同表面狀態的6005A鋁合金表面形貌和粗糙度進行了表征，表明鋁合金商品實際產生的表面缺陷主要為劃傷，體現在隨著表面缺陷的增多，表面粗糙度Ra明顯增大，表面粗糙度Ra大小可以定量描述表面損傷的嚴重程度. 6005A鋁合金在NaCl質量分數3.5%的模擬海水溶液中發生全面腐蝕和點蝕，表面缺陷越多，粗糙度越大，耐蝕性越差；電化學測試結果表明，表面缺陷越多，粗糙度越大，腐蝕電位越低，腐蝕電流密度越大，耐蝕性越差. 6005A鋁合金表面損傷對其耐海水腐蝕性能產生影響的原因為：表面損傷造成鋁合金商品原表面膜被破壞，表面缺陷越多，粗糙度越大，表面膜的破壞和表面塑性變形越嚴重，鋁元素會因為被活化而迅速溶解，有著更高的腐蝕速率，而缺陷較少表面有較為均勻致密的氧化膜，對基體有著較好的保護性.Abstract: A 6005A aluminum alloy was produced by an actual surface with less defects, multiple defect samples, and as-ground samples for the purpose of investigating the effect of aluminum alloy surface damage on corrosion resistance and its corrosion electrochemical behavior in seawater. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) were employed in order to characterize the surface states of the 6005A aluminum alloy. The results show that the surface defects caused by aluminum alloy products consist mainly of scratches. With the increase of surface defects, an obvious increase in Ra is observed, and Ra could quantitatively describe the severity of surface damage. In simulated seawater, the 6005A aluminum alloy undergoes comprehensive corrosion and pitting; thereby, corrosion resistance deteriorates as the amount of defects increases. Electrochemical test results show that the larger the number of surface defects is, the greater are the roughness and lower corrosion potential. Additionally, the greater the corrosion current density is, the worse is the corrosion resistance. A 6005A aluminum alloy that has suffered surface damage and whose corrosion resistance was affected due to seawater can cause the following:the more surface defects are, the greater is the roughness and surface film damage; thereby, the plastic deformation of the surface becomes more serious. The protective layer of the oxide filmis reduced, and the substrate has a higher corrosion rate. The passive film for the samples with less defects is more compact and uniform and could protect the substrate, while effectively reducing further corrosion.
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Key words:
- 6005A aluminum alloy /
- surface damage /
- roughness /
- seawater corrosion /
- electrochemistry
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參考文獻
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