陈高红,肖鉴,杨浩东,于美.LDH预处理溶胶凝胶封闭对铝合金阳极氧化膜耐蚀性的影响[J].表面技术,2024,53(4):58-67.
CHEN Gaohong,XIAO Jian,YANG Haodong,YU Mei.Effects of LDH Pretreatment and Sol-gel Sealing on Corrosion Resistance of Sulfuric Acid Anodized Aluminum Alloy Film[J].Surface Technology,2024,53(4):58-67 |
| LDH预处理溶胶凝胶封闭对铝合金阳极氧化膜耐蚀性的影响 |
| Effects of LDH Pretreatment and Sol-gel Sealing on Corrosion Resistance of Sulfuric Acid Anodized Aluminum Alloy Film |
| 投稿时间：2023-04-21 修订日期：2023-09-07 |
| DOI：10.16490/j.cnki.issn.1001-3660.2024.04.005 |
| 中文关键词: 铝合金 阳极氧化 溶胶凝胶法 封闭改性 LDH 耐蚀性 |
| 英文关键词:aluminum alloy anodization sol-gel method sealing modify LDH corrosion resistance |
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| Author | Institution |
| CHEN Gaohong | School of Materials Science and Engineering, Beihang University, Beijing 100191, China;Beijing Engineering Research Center of Advanced Aluminum Alloys and Applications, Beijing Institute of Aeronautical Materials, Beijing 100095, China |
| XIAO Jian | School of Materials Science and Engineering, Beihang University, Beijing 100191, China |
| YANG Haodong | School of Materials Science and Engineering, Beihang University, Beijing 100191, China |
| YU Mei | School of Materials Science and Engineering, Beihang University, Beijing 100191, China |
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| 中文摘要: |
| 目的 开发一种新型LDH预处理溶胶凝胶封闭工艺，以获得高耐蚀性的封闭阳极氧化膜层。方法 用LDH预处理溶胶凝胶封闭法对阳极氧化铝合金进行表面处理，采用场发射扫描电镜、原子力显微镜对封闭前后的氧化膜进行微观形貌表征，通过接触角测试评价阳极氧化膜层表面的润湿性能，通过浸泡实验、电化学阻抗谱对阳极氧化膜的耐蚀性进行研究，并与传统沸水封闭工艺进行比较。结果 经LDH预处理后，膜层表面被一层致密的LDH覆盖，多孔结构和孔洞缺陷均消失。涂覆溶胶凝胶后，膜层表面均匀平整，无明显缺陷。与沸水封闭相比，LDH预处理溶胶凝胶封闭的氧化膜具有更平整均匀的表面和更低的粗糙度，接触角为92.3°，具有疏水性。在3.5%(质量分数)NaCl溶液中浸泡15 d后，膜层的低频阻抗值仍可达到6.79×106 Ω.cm2，与传统沸水封闭法相比，高出2个数量级。膜层具有良好的长期耐蚀性，其主要机理为LDH的铝合金氧化膜空隙和表面生长出双片层状的LiAl-LDH，表面膜层更致密，片层结构在一定程度上阻挡了腐蚀溶液的入侵，同时使膜层表面存在更多的−OH基团，在溶胶凝胶封闭时提供了更多的反应位点，促进了溶胶凝胶涂层与基体之间的结合，有效阻挡了外界溶液对基体的入侵，因此延缓了腐蚀。结论 LDH预处理溶胶凝胶封闭工艺提高了铝合金阳极氧化膜的致密性和表面疏水性以及膜层的耐蚀性能。 |
| 英文摘要: |
| Anodized oxidation is one of the most commonly used methods in surface pretreatment of aluminum alloy. After anodized oxidation, there is a porous layer outside the film that needs to be closed to improve the corrosion resistance. Traditional boiling water sealing has some problems, such as high energy consumption and unsatisfactory long-term protection performance. Therefore, it is necessary to develop new anodizing sealing methods. In this paper, a new LDH pretreatment sol-gel sealing process was developed to improve compactness, corrosion resistance and hydrophobicity of the oxide film. The microstructure and corrosion resistance of the aluminum alloy anodized oxide film sealed by LDH pretreatment sol-gel were studied to compare with the conventional boiling water sealing process. After oil removal, washing, light and other pretreatment, 2195 aluminum alloy was subject to sulfuric acid anodization. The test conditions of sulfuric acid anodization were as follows:oxidation in 200 g/L sulfuric acid solution at 17 V voltage for 45 min at 15 ℃. The anodized aluminum alloys were pretreated with LDH and then immersed in 0.1 mol/L Li2CO3 solution for 30 min at 50 ℃. After that, the sample was immersed in sol at 80 mm/min and soaked for 5 min and cured for 15 min at room temperature. The above curing process was repeated, and finally the sample was cured at 60 ℃ for 3 h. The microstructure of the oxide films was characterized by a field emission scanning electron microscope (Zeiss SUPRA55) and an atomic force microscope (MESP-RC) before and after sealing. A contact Angle tester (Attension Theta) was used to evaluate the hydrophobicity of the anodized oxide film. The corrosion resistance of anodized oxide film was studied by an immersion test and an electrochemical test. The electrochemical impedance spectroscopy (EIS) of the oxide film was measured by an electrochemical workstation (CHI660C) in neutral 3.5wt.% NaCl solution. The anodic oxide film of 2195 aluminum alloy was successfully sealed by sol-gel pretreatment with LDH. After LDH pretreatment, the surface of the film layer was covered by a dense layer of LDH, and the porous structure and pore defects disappeared. The oxide film sealed with LDH pretreatment sol gel had a more even surface and lower roughness than that sealed with boiling water, with a contact Angle of 92.3° and hydrophobicity. The results of immersion test showed that after 15 days in 3.5wt.% NaCl solution, |Z|0.01 Hz could still reach 6.79×106 Ω.cm2. The film had good long-term corrosion resistance, because the double lamellar LiAl-LDH grew on the surface of the aluminum oxide film of LDH, and the surface film was denser. The lamellar structure prevented the invasion of the corrosion solution. At the same time, there were more —OH groups on the surface of the film, which provided more reaction sites when the sol-gel was closed, promoting the combination between the sol-gel coating and the matrix. As a result, the invasion of the outside solution to the matrix was effectively blocked and the corrosion was delayed. In conclusion, LDH pretreatment sol-gel sealing can improve the density and surface hydrophobicity of aluminum alloy anodized oxide film, and effectively improve the corrosion resistance of the film. |
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