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Journal of Zhejiang University SCIENCE A

ISSN 1673-565X(Print), 1862-1775(Online), Monthly

Corrosion behavior and protection mechanism of carbon steel coated with ethylene chlorotrifluoroethylene (ECTFE)

Abstract: Ethylene chlorotrifluoroethylene (ECTFE) coating was applied to the surface of carbon steel through electrostatic spraying and low-temperature heat treatment. The morphology and structure of the coating were analyzed using various characterization techniques. The electrochemical data of the coated steel soaked in 3.5% (mass fraction) NaCl solution for 90 d at different periods were also examined. The findings indicate that the outer surface of the coating remains structurally stable before and after soaking. F can diffuse into the steel substrate, facilitating the bonding between the coating and the steel substrate, but the free F also induces a weakening effect on the crystalline structure. Due to the thickness of the coating edge and the susceptibility to infiltration of the corrosive medium, under-film micro-zone corrosion occurs at a slow rate. After soaking for 90 d, the impedance modulus measures approximately 104 Ω·cm2, and the open circuit potential (OCP) is -0.61 V. The self-corrosion current density is 1.13×10-6 A/cm2, resulting in a calculated coating protection rate of 99.29%. In summary, despite edge corrosion occurring, the ECTFE coating provides excellent corrosion protection.

Key words: Coating; Fluorine resin; Edge corrosion; Corrosive behavior; Electrochemical performance

Chinese Summary  <2> ECTFE涂层对碳钢的腐蚀行为及防腐机制研究

作者:沈佩浒1,文俊1,董必钦2,李贺东1,王敏嘉1,3
机构:1浙江理工大学,建筑工程学院,中国杭州,310018;2深圳大学,土木与交通工程学院,中国深圳,518061;3浙江省化工研究院有限公司,浙江杭州,310023
目的:钢结构应用广泛,但极易发生腐蚀。本研究旨在通过静电喷涂和低温热处理技术在碳钢表面制备乙烯-三氟氯乙烯(ECTFE)涂层,并对涂层钢的腐蚀行为及耐蚀机理进行深入研究,以揭示在ECTFE涂层保护下碳钢的界面腐蚀演变规律,并为钢结构耐久性技术的提升以及防腐涂层材料的发展提供新的思路。
创新点:1.将半结晶态的ECTFE涂层涂覆于碳钢表面,可对钢结构进行良好的腐蚀防护;2.涂层钢的边缘腐蚀行为会影响附着力,但涂层的致密结构依然能够起到屏障作用。
方法:1.采用静电喷涂结合低温热处理技术在碳钢表面制备ECTFE涂层;2.通过热分析仪TG-DSC确定ECTFE的致密化成型温度,并采用傅里叶变换红外光谱仪、X射线衍射、扫描电子显微镜和能谱仪表征ECTFE涂层钢在3.5%(质量分数)的NaCl溶液中浸泡90d后前后涂层及界面的结构组成、形貌演变及元素分布,同时测试不同浸泡时期涂层钢的开路电位(OCP)、电化学阻抗谱(EIS)和动电位扫描特性。
结论:1.将ECTFE涂层在3.5%的NaCl溶液中浸泡90 d后,其外表面结构稳固;2. F离子能扩散进入钢基体,有助于涂层和钢基体的结合,但会削弱涂层的晶态结构;3.由于涂层边缘较薄,腐蚀介质容易从边缘侵入,造成边缘腐蚀;4.涂层钢在边缘腐蚀的情况下,由于涂层结构致密稳定,所以其依然具有优异的阻隔效果。

关键词组:涂层;氟树脂;边缘腐蚀;腐蚀行为;电化学性能


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DOI:

10.1631/jzus.A2300157

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On-line Access:

2024-06-27

Received:

2023-03-24

Revision Accepted:

2023-07-31

Crosschecked:

2024-06-27

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