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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第23卷    第6期    总第171期    2013年6月

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文章编号:1004-0609(2013)06-1640-08
电化学阻抗谱技术研究Ce(Ⅲ)转化膜在3.5%NaCl溶液中的腐蚀行为
顾宝珊,杨培燕,宫 丽

(中国钢研科技集团有限公司 先进金属材料涂镀国家工程实验室,北京 100081)

摘 要: 应用电化学阻抗谱(EIS)连续测试B95铝合金表面稀土转化膜在3.5%NaCl溶液中铈盐转化膜的破坏过程,通过阻抗值的变化研究B95铝合金表面稀土转化膜在3.5%NaCl溶液中的腐蚀行为,采用等效电路的方式对测试的EIS进行解析。通过转化膜腐蚀过程阻抗谱特征研究,建立了B95铝合金表面Ce(Ⅲ)转化膜腐蚀破环的3个阶段模型:浸泡早期、浸泡中期和浸泡后期。浸泡早期,铝合金表面稀土转化膜被电解质溶液湿润,水开始渗透进转化膜;浸泡中期,电解质溶液渗透转化膜被破坏,同时与转化膜自修复相互竞争,转化膜破坏/再钝化;浸泡后期,转化膜破坏超过转化膜自修复,铝合金基体开始逐渐腐蚀溶解。同时,该模型可以定量预测转化膜表面腐蚀发展的程度。

 

关键字: 铝合金;电化学阻抗;Ce转化膜;腐蚀行为;NaCl溶液

Corrosion behavior of Ce(III) conversion coating in 3.5%NaCl solution by electrochemical impedance spectroscope
GU Bao-shan, YANG Pei-yan, GONG Li

National Engineering Laboratory for Advanced Coatings Technology of Metal Materials,
China Iron and Steel Research Institute Group, Beijing 100081, China

Abstract:The corrosion behavior of cerium(Ⅲ) conversion coating on B95 aluminum alloy in 3.5%NaCl solution was investigated by electrochemical impedance spectroscope (EIS). The process of corrosion and mechanism of cerium(Ⅲ) conversion coating on B95 aluminum alloy were investigated through the changes of EIS in the process. The tested EIS based on equivalent circuit was analyzed. The results show that the variation of EIS can clearly display the corrosion behavior change of cerium(Ⅲ) conversion coating on B95 aluminum alloy in 3.5%NaCl solution. Through investigating the EIS features, the respective model of each stage and its corresponding equivalent circuit were built to show the corrosion and destruction of the Ce(Ⅲ) conversion coating on B95 aluminum alloy. They are, respectively, the early stage, the middle stage and the terminal stage of immersion. The early stage refers to the time when the conversion coating on aluminum alloy is moisturized by electrolyte solution and water begins to permeate into the coating. The middle stage refers to the time when this permeation into the conversion coating is destructed while the conversion coating undergoes self-rehabilitation, thus giving rise to the competition between the destruction and self-rehabilitation of the conversion coating. The terminal stage refers to the time when the destruction of conversion coating outweighs its self-rehabilitation, the alloy begins to get corroded and resolved. This model can predict the corrosion degree of the conversion coating surface.

 

Key words: aluminium alloys; electrochemical impedance spectroscope (EIS); cerium conversion coating; corrosion behavior; NaCl solution

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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