黄发王俭秋韩恩厚柯伟
金属学报
doi:10.3724/SP.J.1037.2011.00212
在硼酸缓冲溶液中, 采用动电位极化、电化学阻抗谱(EIS)和半导体电容分析方法分别研究了Cl-浓度(0.5-2 mol/L)和溶液温度(25-80 ℃)对690合金腐蚀行为的影响, 并结合AFM, XPS及电位-pH图分析了钝化膜层的腐蚀产物. 结果表明, 不同Cl-浓度和温度的溶液中, 690合金均表现出沿晶腐蚀和二次钝化的特征. Cl-浓度和溶液温度的提高均使 690合金的自腐蚀电位下降, 腐蚀电流密度增大, 同时温度的升高还使690合金的点蚀电位降低, 钝化区间变窄. 恒电位极化相同时间, 低电位的钝化区内的腐蚀产物主要为Cr, Fe 的氧化物和Ni(OH)2, 钝化膜较薄且致密性好, 体现n型与p型共存的特征. 高电位的钝化区内的腐蚀产物主要为Ni2O3, 钝化膜较厚但致密性差, 体现n型半导体特征.
关键词:
690合金
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passive film
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potentiodynamic polarization
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electrochemical impedence spectroscopy (EIS)
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Mott-Scottky relation
J.F.Li
金属学报(英文版)
The corrosion behavior and electrochemical impedance spectroscopy (EIS) features of 8090 AI-Li alloys in EXCO solution were investigated, and the EIS was simulated using an equivalent circuit. At the beginning of immersion in EXCO solution, the EIS is comprised by a depressed capacitive arc at high-mediate frequency and an inductivearc at low frequency, and the inductive component decreases and disappears with immersion time. Once exfoliation or severe pitting corrosion is produced, two capacitive arcs appear in the EIS. These two capacitive arcs are originated from the two parts of the corroded aUoy surface, the original flat alloy surface and the new inter-face exposed to the aggressive EXCO solution due to the exfoliation or pitting corrosion.Some corrosion development features of 8090 AI-Li alloys in EXCO solution can be obtained through simulated EIS information.
关键词:
8090 Al-Li alloy
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null
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