结合WBE与EIS技术研究环氧涂层下碳钢与铜合金在海水中的电偶腐蚀
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摘要
目的研究环氧涂层下碳钢与铜合金在海水中的电偶腐蚀行为及涂层整体和局部区域的劣化过程。方法使用丝束电极(WBE)技术和电化学阻抗谱(EIS)技术研究丝束电极表面的电流密度分布和涂层阻抗谱演化,同时对比分析碳钢区域与铜合金区域涂层的阻抗谱特征。结果阳极电流峰首先出现在碳钢局部区域,而电流密度较大的阴极电流峰主要集中出现在铜合金区域的边缘。当浸泡至122 h时,铜合金区域的涂层阻抗明显低于碳钢区域的涂层阻抗,且EIS响应出现了Warburg扩散阻抗特征。在浸泡456 h后,单根钢电极发生由阴极向阳极的极性转换。结论涂层下碳钢与铜合金在海水中发生电偶腐蚀时,铜合金作为阴极被保护,但铜合金区域的涂层在阴极剥离的作用下加速劣化。在涂层劣化过程中,碳钢区域的涂层缺陷处成为腐蚀反应的阳极区,而主要的阴极区位于铜合金的边缘区域,这与溶解氧的"竞争效应"有关。由于涂层发生阴极剥离现象使得基底金属被腐蚀,从而导致涂层下单根钢电极的电流发生由阴极向阳极的极性转换。
The work aims to study the galvanic corrosion behaviors of carbon steel/copper alloy couple under epoxy coating and the degradation process of the whole and local area of the coating exposed to seawater. The current density distributions of the WBE and the EIS evolution of the coating on WBE surface were studied by WBE and EIS techniques. Meanwhile, the EIS characteristics of the coating on carbon steel and copper alloy surface were also compared and analyzed. It showed that the anodic current peak first appeared at the local area of carbon steel, while the cathodic current peaks with larger current densities appeared at the edge of the copper alloy area. After 122 h of immersion, the impendence value of the coating on copper alloy surface was obviously lower than that of the coating on carbon steel surface, and the Warburg impedance behavior could be observed in the EIS of the coating on copper alloy surface. The current of the single steel electrode changed from cathodic to anodic when the WBE was immersed for 456 h. In conclusion, when the carbon steel and copper alloy under epoxy coating were electrically coupled in seawater, the copper alloy was protected by carbon steel from corrosion but the degradation processes of the coating on copper alloy surface was accelerated by cathodic delamination. During the degradation processes of the epoxy coating, the local defect area of the coating on carbon steel surface became the anodic area and the main cathodic area was concentrated at the edge of copper alloy area, which was related to the "competition effect" for dissolved oxygen. The reason of the polarity reversals from cathodic to anodic of the single carbon steel electrode may be that the metal was corroded because of cathodic delamination.
The work aims to study the galvanic corrosion behaviors of carbon steel/copper alloy couple under epoxy coating and the degradation process of the whole and local area of the coating exposed to seawater. The current density distributions of the WBE and the EIS evolution of the coating on WBE surface were studied by WBE and EIS techniques. Meanwhile, the EIS characteristics of the coating on carbon steel and copper alloy surface were also compared and analyzed. It showed that the anodic current peak first appeared at the local area of carbon steel, while the cathodic current peaks with larger current densities appeared at the edge of the copper alloy area. After 122 h of immersion, the impendence value of the coating on copper alloy surface was obviously lower than that of the coating on carbon steel surface, and the Warburg impedance behavior could be observed in the EIS of the coating on copper alloy surface. The current of the single steel electrode changed from cathodic to anodic when the WBE was immersed for 456 h. In conclusion, when the carbon steel and copper alloy under epoxy coating were electrically coupled in seawater, the copper alloy was protected by carbon steel from corrosion but the degradation processes of the coating on copper alloy surface was accelerated by cathodic delamination. During the degradation processes of the epoxy coating, the local defect area of the coating on carbon steel surface became the anodic area and the main cathodic area was concentrated at the edge of copper alloy area, which was related to the "competition effect" for dissolved oxygen. The reason of the polarity reversals from cathodic to anodic of the single carbon steel electrode may be that the metal was corroded because of cathodic delamination.
引文
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[10]孙志华,蔡建平,刘明,等.金属/有机涂层体系环境失效的电化学研究方法[J].装备环境工程,2007,4(4):1-5.SUN Zhi-hua,CAI Jian-ping,LIU Ming,et al.Review on electrochemical investigation methods of environmental failure at metal/organic Interface[J].Equipment environmental engineering,2007,4(4):1-5.
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[13]陈刚,刘光明,姚敬,等.有机硅/SiO2杂化涂层电化学阻抗研究[J].表面技术,2008,37(6):47-50.CHEN Gang,LIU Guang-ming,YAO Jing,et al.Study on the electrochemical impedance spectroscopy of silicone/Si O2 hybrid coating[J].Surface technology,2008,37(6):47-50.
[14]WANG Y H,LIU Y Y,WANG W,et al.Influences of the three-phase boundary on the electrochemical corrosion characteristics of carbon steel under droplets[J].Materials and corrosion,2013,64(4):309-313.
[15]WANG Y H,WANG W,LIU Y Y,et al.Study of localized corrosion of 304 stainless steel under chloride solution droplets using the wire beam electrode[J].Corrosion science,2011,53(9):2963-2968.
[16]MUSTER T H,BRADBURY A,TRINCHI A,et al.The atmospheric corrosion of zinc:The effects of salt concentration,droplet size and droplet shape[J].Electrochim acta,2011,56(4):1866-1873.
[17]TAN Y J.Experimental methods designed for measuring corrosion in highly resistive and inhomogeneous media[J].Corrosion science,2011,53(4):1145-1155.
[18]TAN Y J,YU S T.The effects of inhomogeneity in organic coatings on electrochemical measurements using a wire beam electrode.Part I[J].Progress in organic coatings,1991,19(1):89-94.
[19]LIU J,ZHANG L W,MU X L,et al.Studies of electrochemical corrosion of low alloy steel under epoxy coating exposed to natural seawater using the WBE and EIS techniques[J].Progress in organic coatings,2017,111:315-321.
[20]TAN Y J,YU S T.The effects of inhomogeneity in organic coatings on electrochemical measurements using a wire beam electrode.Part II[J].Progress in organic coatings,1991,19(3):257-263.
[21]刘杰,王伟,王佳.结合EIS和WBE技术研究环氧涂层劣化[J].材料科学与工艺,2013,21(5):33-39.LIU Jie,WANG Wei,WANG Jia.Evaluation of the deterioration of epoxy coating by EIS and WBE techniques[J].Materials science&technology,2013,21(5):33-39.
[22]LENG A,STRECKEL H,HOFMANN K,et al.The delamination of polymeric coatings from steel part 3:Effect of the oxygen partial pressure on the delamination reaction and current distribution at the metal/polymer interface[J].Corrosion science,1998,41(3):599-620.
[23]WANG B,Li X B,LIU J,et al.Comparison of atmospheric corrosion behavior of Al-Mn and Al-Zn-Mg-Cu alloys in a tropical coastal environment[J].Materials and corrosion,2018,69:888-897.
[24]SYKES J M,XU Y.Electrochemical studies of galvanic action beneath organic coatings[J].Progress in organic coatings,2012,74(2):320-325.
[25]赵洪涛,陆卫中,李京,等.模拟流动海水条件下无溶剂环氧防腐涂层的失效行为[J].腐蚀科学与防护技术,2016,28(5):397-406.ZHAO Hong-tao,LU Wei-zhong,LI Jing,et al.Failure behavior of solvent-free epoxy coating in simulated flowing sea water[J].Corrosion science and protection technology,2016,28(5):397-406.
[26]胡吉明,张鉴清,谢德明,等.环氧树脂涂覆LY12铝合金在NaCl溶液中的阻抗模型[J].物理化学学报,200319(2):144-149.HU Ji-ming,ZHANG Jian-qing,XIE De-ming,et al.Impendance models of epoxy coated LY12 aluminum alloys in NaCl solution[J].Acta physico-chimica sinica,2003,19(2):144-149.
[27]TAN Y J.Wire beam electrode:A new tool for studying localised corrosion and other heterogeneous electrochemical processes[J].Corrosion science,1999,41(2):229-247.
[28]BI H C,SYKES J.Cathodic delamination of unpigmented and pigmented epoxy coatings from mild steel[J].Progress in organic coatings,2016,90:114-125.
[29]张伟,王佳,赵增元,等.电化学阻抗谱对比研究连续浸泡和干湿循环条件下有机涂层的劣化过程[J].中国腐蚀与防护学报,2011,31(5):329-335.ZHANG Wei,WANG Jia,ZHAO Zeng-yuan,et al Comparing the degradation process of organic coatings under continuous soaking and dry-wet circle conditions using EIS[J].Journal of Chinese society for corrosion and protection,2011,31(5):329-335.
[30]刘华剑,有机涂层下船用钢电偶腐蚀规律研究[D].青岛:中国海洋大学,2011.LIU Hua-jian.The investigation of galvanic corrosion under the organic coating on sheep steel[D].Qingdao:Ocean University of China,2011.
[31]丁锐,桂泰江,蒋建明,等.应用EIS研究改性无溶剂环氧防腐涂层的防护性能和腐蚀特征[J].真空科学与技术学报,2017,37(2):165-176.DING Rui,GUI Tai-jiang,JIANG Jian-ming,et al.Electrochemical impedance spectroscopy study of corrosion behavior of solvent-free epoxy coatings on steel substrate[J].Chinese journal of vacuum science and technology,2017,37(2):165-176.
[32]KOEHLER E L.The mechanism of cathodic disbondment of protective organic coatings-aqueous displacement at elevated pH[J].Corrosion,1984,40(1):5-8.
[33]何建波,李学良,林建新.铜在浓碱溶液中的阳极钝化膜[J].中国有色金属学报,1997,7(1):48-51.HE Jian-bo,LI Xue-liang,LIN Jian-xin.The anode passivation film of copper in a concentrated alkali solution[J].The Chinese journal of nonferrous metals,1997,7(1):48-51.
[2]王春丽,吴建华,李庆芬.海洋环境电偶腐蚀研究现状与展望[J].中国腐蚀与防护学报,2010,30(5):417-420.WANG Chun-li,WU Jian-hua,LI Qing-fen.Current status and prospects of research on galvanic corrosion in marine environment[J].Journal of Chinese society for corrosion and protection,2010,30(5):417-420.
[3]周立新,程江,杨卓如.有机涂层防腐性能的研究与评价方法[J].腐蚀科学与防护技术,2004,16(6):375-377.ZHOU Li-xin,CHENG Jiang,YANG Zhuo-ru.Methods for study and evaluation of anticorrosion performance of organic coatings[J].Corrosion science and protection technology,2004,16(6):375-377.
[4]萧以德,张三平.金属和有机涂层在海水环境中的腐蚀与保护性能[J].材料保护,1995,28(12):3-5.XIAO Yi-de,ZHANG San-ping.Corrosion and protection properties of metal and organic coatings in seawater[J].Materials protection,1995,28(12):3-5.
[5]LIU J,LI X B,WANG J,et al.Studies of impedance models and water transport behaviours of epoxy coating at hydrostatic pressure of seawater[J].Progress in organic coatings,2013,76(7):1075-1081.
[6]张鉴清,曹楚南.电化学阻抗谱方法研究评价有机涂层[J].腐蚀与防护,1998,19(3):99-104.ZHANG Jian-qing,CAO Chu-nan.Study and evaluation on organic coating by electrochemical impendence spectroscopy[J].Corrosion&protection,1998,19(3):99-104.
[7]BIERWAGEN G P,TALLMAN D E.Choice and measurement of crucial aircraft coatings system properties[J].Progress in organic coatings,2001,41(4):201-216.
[8]ZHU C F,XIE R,XUE J H,et al.Studies of the impedance models and water transport behaviors of cathodically polarized coating[J].Electrochimica acta,2011,56(16):5828-5835.
[9]WANG Z D,LI J,WANG Y,et al.An EIS analysis on corrosion resistance of anti-abrasion coating[J].Surfaces and interfaces,2017,6:33-39.
[10]孙志华,蔡建平,刘明,等.金属/有机涂层体系环境失效的电化学研究方法[J].装备环境工程,2007,4(4):1-5.SUN Zhi-hua,CAI Jian-ping,LIU Ming,et al.Review on electrochemical investigation methods of environmental failure at metal/organic Interface[J].Equipment environmental engineering,2007,4(4):1-5.
[11]MONTAZERI S,RANJBARA Z,RASTEGAR S.A study on effects of viscoelastic properties on protective performance of epoxy coatings using EIS[J].Progress in organic coatings,2017,111:248-257.
[12]胡吉明,张鉴清,曹楚南.铝合金表面环氧涂层中水传输行为的电化学阻抗谱研究[J].金属学报,2003,39(5):544-549.HU Ji-ming,ZHANG Jian-qing,CAO Chu-nan.EIS studies of water transport in epoxy coatings coated on LY12aluminum alloys[J].Acta metallurgica sinica,2003,39(5):544-549.
[13]陈刚,刘光明,姚敬,等.有机硅/SiO2杂化涂层电化学阻抗研究[J].表面技术,2008,37(6):47-50.CHEN Gang,LIU Guang-ming,YAO Jing,et al.Study on the electrochemical impedance spectroscopy of silicone/Si O2 hybrid coating[J].Surface technology,2008,37(6):47-50.
[14]WANG Y H,LIU Y Y,WANG W,et al.Influences of the three-phase boundary on the electrochemical corrosion characteristics of carbon steel under droplets[J].Materials and corrosion,2013,64(4):309-313.
[15]WANG Y H,WANG W,LIU Y Y,et al.Study of localized corrosion of 304 stainless steel under chloride solution droplets using the wire beam electrode[J].Corrosion science,2011,53(9):2963-2968.
[16]MUSTER T H,BRADBURY A,TRINCHI A,et al.The atmospheric corrosion of zinc:The effects of salt concentration,droplet size and droplet shape[J].Electrochim acta,2011,56(4):1866-1873.
[17]TAN Y J.Experimental methods designed for measuring corrosion in highly resistive and inhomogeneous media[J].Corrosion science,2011,53(4):1145-1155.
[18]TAN Y J,YU S T.The effects of inhomogeneity in organic coatings on electrochemical measurements using a wire beam electrode.Part I[J].Progress in organic coatings,1991,19(1):89-94.
[19]LIU J,ZHANG L W,MU X L,et al.Studies of electrochemical corrosion of low alloy steel under epoxy coating exposed to natural seawater using the WBE and EIS techniques[J].Progress in organic coatings,2017,111:315-321.
[20]TAN Y J,YU S T.The effects of inhomogeneity in organic coatings on electrochemical measurements using a wire beam electrode.Part II[J].Progress in organic coatings,1991,19(3):257-263.
[21]刘杰,王伟,王佳.结合EIS和WBE技术研究环氧涂层劣化[J].材料科学与工艺,2013,21(5):33-39.LIU Jie,WANG Wei,WANG Jia.Evaluation of the deterioration of epoxy coating by EIS and WBE techniques[J].Materials science&technology,2013,21(5):33-39.
[22]LENG A,STRECKEL H,HOFMANN K,et al.The delamination of polymeric coatings from steel part 3:Effect of the oxygen partial pressure on the delamination reaction and current distribution at the metal/polymer interface[J].Corrosion science,1998,41(3):599-620.
[23]WANG B,Li X B,LIU J,et al.Comparison of atmospheric corrosion behavior of Al-Mn and Al-Zn-Mg-Cu alloys in a tropical coastal environment[J].Materials and corrosion,2018,69:888-897.
[24]SYKES J M,XU Y.Electrochemical studies of galvanic action beneath organic coatings[J].Progress in organic coatings,2012,74(2):320-325.
[25]赵洪涛,陆卫中,李京,等.模拟流动海水条件下无溶剂环氧防腐涂层的失效行为[J].腐蚀科学与防护技术,2016,28(5):397-406.ZHAO Hong-tao,LU Wei-zhong,LI Jing,et al.Failure behavior of solvent-free epoxy coating in simulated flowing sea water[J].Corrosion science and protection technology,2016,28(5):397-406.
[26]胡吉明,张鉴清,谢德明,等.环氧树脂涂覆LY12铝合金在NaCl溶液中的阻抗模型[J].物理化学学报,200319(2):144-149.HU Ji-ming,ZHANG Jian-qing,XIE De-ming,et al.Impendance models of epoxy coated LY12 aluminum alloys in NaCl solution[J].Acta physico-chimica sinica,2003,19(2):144-149.
[27]TAN Y J.Wire beam electrode:A new tool for studying localised corrosion and other heterogeneous electrochemical processes[J].Corrosion science,1999,41(2):229-247.
[28]BI H C,SYKES J.Cathodic delamination of unpigmented and pigmented epoxy coatings from mild steel[J].Progress in organic coatings,2016,90:114-125.
[29]张伟,王佳,赵增元,等.电化学阻抗谱对比研究连续浸泡和干湿循环条件下有机涂层的劣化过程[J].中国腐蚀与防护学报,2011,31(5):329-335.ZHANG Wei,WANG Jia,ZHAO Zeng-yuan,et al Comparing the degradation process of organic coatings under continuous soaking and dry-wet circle conditions using EIS[J].Journal of Chinese society for corrosion and protection,2011,31(5):329-335.
[30]刘华剑,有机涂层下船用钢电偶腐蚀规律研究[D].青岛:中国海洋大学,2011.LIU Hua-jian.The investigation of galvanic corrosion under the organic coating on sheep steel[D].Qingdao:Ocean University of China,2011.
[31]丁锐,桂泰江,蒋建明,等.应用EIS研究改性无溶剂环氧防腐涂层的防护性能和腐蚀特征[J].真空科学与技术学报,2017,37(2):165-176.DING Rui,GUI Tai-jiang,JIANG Jian-ming,et al.Electrochemical impedance spectroscopy study of corrosion behavior of solvent-free epoxy coatings on steel substrate[J].Chinese journal of vacuum science and technology,2017,37(2):165-176.
[32]KOEHLER E L.The mechanism of cathodic disbondment of protective organic coatings-aqueous displacement at elevated pH[J].Corrosion,1984,40(1):5-8.
[33]何建波,李学良,林建新.铜在浓碱溶液中的阳极钝化膜[J].中国有色金属学报,1997,7(1):48-51.HE Jian-bo,LI Xue-liang,LIN Jian-xin.The anode passivation film of copper in a concentrated alkali solution[J].The Chinese journal of nonferrous metals,1997,7(1):48-51.
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