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| 纯铁在均匀液膜下的CO2腐蚀机制 |
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李强1,2,张玉瑜2,刘刚1,2,朱铁燕1,唐晓3,李焰3
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(1.山东省油气储运安全重点实验室,山东青岛 266580;2.中国石油大学(华东)储运与建筑工程学院,山东青岛 266580;3.中国石油大学(华东)材料科学与工程学院,山东青岛 266580)
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| 摘要: |
| 液膜下的CO2腐蚀是湿天然气管道内腐蚀破坏的重要形式,对其腐蚀机制的认知还非常有限。自主设计、搭建一套可实现温湿度控制、液膜厚度表征与控制以及三电极电化学测试的试验装置,结合电化学阻抗谱、极化曲线等电化学测试,研究纯铁在不同CO2分压环境、不同厚度均匀液膜中的CO2腐蚀行为机制。结果表明:液膜下的CO2腐蚀过程受阴极扩散控制,电极表面扩散层厚度小于1000 μm;液膜厚度小于1000 μm时,腐蚀速率整体随液膜厚度增大呈增大趋势,因受到CO2溶解度与腐蚀产物膜的影响,腐蚀速率在液膜厚度为400 μm时出现局部极值;液膜厚度小于400 μm时,CO2在液膜中的溶解度是制约腐蚀速率的重要因素;液膜厚度在400～1000 μm时,腐蚀产物膜成为影响腐蚀速率的主要因素;薄层液膜环境下增加CO2分压既可提高腐蚀速率又可以促进腐蚀产物膜的生成。 |
| 关键词: CO2腐蚀 均匀液膜 腐蚀机制 纯铁 腐蚀产物膜 饱和度 |
| DOI：10.3969/j.issn.1673-5005.2020.03.018 |
| 分类号::TE 988 |
| 文献标识码:A |
| 基金项目:山东省自然科学基金项目(ZR2019BEE040);中央高校基本科研费用专项(18CX02001A,19CX05007A);中国石油大学(华东)人才引进项目(YJ20170031) |
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| CO2 corrosion mechanism of pure Fe under action of uniform water film |
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LI Qiang1,2, ZHANG Yuyu2, LIU Gang1,2, ZHU Tieyan1, TANG Xiao3, LI Yan3
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(1.Shandong Key Laboratory of Oil ＆ Gas Storage and Transportation Safety, Qingdao 266580, China;2.College of Pipeline and Civil Engineering in China University of Petroleum (East China), Qingdao 266580, China;3.School of Materials Science and Engineering in China University of Petroleum (East China), Qingdao 266580, China)
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| Abstract: |
| CO2 corrosion under the action of a water film is an important corrosion pattern in wet gas pipelines. However, current understandings on the CO2 corrosion mechanism under the action of a water film are very limited. A testing setup, which enables the control of temperature and humidity, characterization and control of the water film 's thickness, and three-electrode electrochemical testing, was designed and established. Electrochemical tests, including electrochemical impedance spectroscopy and polarization curve, were performed to study the CO2 corrosion mechanism of pure iron under the action of a uniform water film with different thicknesses and variable CO2 partial pressure conditions. The results show that pure iron is under the catholic diffusion control, and the diffusion layer 's thickness is smaller than 1 000 μm. When the thickness of the water film is smaller than 1 000 μm, the corrosion rate increases with the increase of the film 's thickness. Due to the effect of CO2 solubility in the water film and the presence of corrosion product film, the corrosion rate has a local extreme value when the film thickness is 400 μm. When the film thickness is smaller than 400 μm, the effect of CO2 solubility dominates the process, while the effect of corrosion product film becomes the leading factor when the water film thickness is between 400 μm and 1 000 μm. Increasing the CO2 concentration can enhance the corrosion rate, and at the same time can promote the formation of corrosion product. |
| Key words: CO2corrosion uniform water film corrosion mechanism pure iron corrosion product film saturation level |
