无机材料学报 ›› 2015, Vol. 30 ›› Issue (6): 627-632.DOI: 10.15541/jim20140582

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封闭对铝合金微弧氧化膜在酸性溶液中耐蚀性的影响

叶作彦1, 刘道新1, 李重阳1, 张晓化1, 张小明2, 雷明霞2   

  1. (1. 西北工业大学 腐蚀与防护研究所, 西安 710072; 2. 中航工业第一飞机设计研究院, 西安 710089)
  • 收稿日期:2014-11-14 修回日期:2014-12-25 出版日期:2015-06-04 网络出版日期:2015-05-22
  • 作者简介:叶作彦(1987–), 男, 博士研究生. E-mail: yebonpu@126.com
  • 基金资助:
    国家自然科学基金(51171154);轻合金加工科学与技术国防重点学科实验室开放课题研究基金(gf201401001)

Effect of Sealing Treatments on the Corrosion Behavior of Micro-arc Oxidation Coating on Aluminum Alloy in Acid NaCl Solution

YE Zuo-Yan1, LIU Dao-Xin1, LI Chong-Yang1, ZHANG Xiao-Hua1, ZANG Xiao-Ming2, LEI Ming-Xia2   

  1. (1. Corrosion and Protection Research Laboratory, Northwestern Polytechnical University, Xi'an 710072, China; 2. AVIC the First Aircraft Institute, Xi'an 710089, China)
  • Received:2014-11-14 Revised:2014-12-25 Published:2015-06-04 Online:2015-05-22
  • About author:YE Zuo-Yan. E-mail: yebonpu@126.com
  • Supported by:
    National Natural Science Foundation of China (51171154);National Defense key Disciplines Laboratory of light Alloy Procossing Science and Technology, Nachang Hangkong University (gf201401001)

摘要:

为了提高7A85铝合金的耐蚀性, 采用单极性正脉冲微弧氧化(MAO)技术在其表面制备了陶瓷膜层, 并采用稀土铈盐、铬酸盐和SiO2溶胶对MAO膜进行封闭处理。采用扫描电子显微镜(SEM)、X射线衍射仪和电化学工作站研究了封闭处理对膜层表面形貌、结构和在酸性NaCl溶液中腐蚀行为的影响。实验发现, MAO膜在酸性NaCl溶液中不能有效地保护铝合金基体。稀土铈盐和铬酸盐封闭处理通过沉积水合氢氧化物封闭孔隙, 可以提高MAO膜的耐蚀性。但在酸性溶液中, 封孔物质会和H+发生反应而溶解, 故经封闭的MAO试样也会发生腐蚀失效。SiO2溶胶封闭处理后MAO膜表面覆盖一层凝胶, 使膜层成为完整的致密层, 可以保护铝合金基体在酸性NaCl溶液中免受腐蚀。

关键词: 铝合金, 微弧氧化, 封闭处理, 电化学, 耐蚀性, SiO2溶胶

Abstract:

Ceramic coatings were fabricated on 7A85 aluminum alloy by unipolar positive pulsed micro-arc oxidation (MAO) treatment for enhancing corrosion resistance. A bi-layer coating was formed with large pores between the layers. The outer layer contained several micro pores and cracks. Therefore, cerium nitrate, potash bichromate and SiO2 sol were adopted to seal the MAO coatings. Scanning electron microscope, X-ray diffraction and electrochemistry instrument were used to investigate the effect of sealing treatments on the surface morphology, coating structure and corrosion resistance of MAO coatings. Results show that the MAO coating can not protect aluminum alloy from acid NaCl solution for the existing of defects. The defects can be sealed by precipitations produced by cerium nitrate and potash bichromate sealing treatment, and corrosion resistance of the MAO coating is improved. However, the sealed coatings also fail in the acid NaCl solution for dissolution of the precipitation. After sealing with SiO2 sol, the MAO coating is covered with a SiO2 gel layer has become a compact barrier layer to protect aluminum substrate from corrosion in acid NaCl solution.

Key words: aluminum alloy, micro-arc oxidation, seal treatment, electrochemistry, corrosion resistance, SiO2 sol

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