摘要
为探明薄层液膜下外加直流电场(DCEF)对Cu/Ag电偶腐蚀行为的影响机制,通过开路电位、电化学阻抗谱和极化曲线等电化学测试,并结合表面分析技术,研究了在薄层液膜条件下,外加DCEF中Cu/Ag电偶腐蚀行为。结果表明:外加DCEF后,铜的腐蚀电位明显正移,阴极电流密度和自腐蚀电流密度减小,阻抗增大,这表明了DCEF减缓了铜的腐蚀速率。与有电场无电流相比,有电流时,铜的腐蚀电位正移,阴极电流密度减小,阻抗略微增大。表明漏电电流能够进一步抑制铜银之间的电偶腐蚀速率,这归因于DCEF负极处的析氢反应使得局部OH-离子浓度的增加,在电场梯度的作用下向电场正极迁移,从而导致电偶腐蚀的阴极过程受到抑制。不同条件下铜和银之间的电偶电流密度大小顺序为:偶合>偶合有电场无电流>偶合有电场有电流,这归因于DCEF降低了铜银的电位差,削弱了铜银之间的电偶腐蚀效应;而漏电电流则加速了电场阴极处因析氢产生的OH-离子向电场正极迁移,导致电偶腐蚀的阴极过程被显著抑制。
To investigate the influence of applied direct current electric field(DCEF) on the galvanic corrosion behavior of Cu/Ag under a thin electrolyte layer,the galvanic corrosion behavior of Cu/Ag with a DCEF under a thin electrolyte layer was investigated by electrochemical tests including open-circuit potential,electrochemical impedance spectroscopy and polarization curve,combined with surface analysis technology.The experimental results show that the corrosion potential of copper changes significantly under a DCEF,the cathodic current density and self-corrosion current density decrease,and the impedance increases,which indicates the DCEF slows down the corrosion rate of copper.Compared with that under a DCEF without current,the corrosion potential of copper under a DCEF with current moves positively,the cathodic current density of copper decreases,and the impedance increases slightly.This indicates that the leakage current can further inhibit the galvanic corrosion of copper.This can be explained as follows:the hydrogen evolution at the negative electrode of DCEF leads to the increase of the concentration of local OH-ions,and the produced OH-ions migrate to the positive electrode of DCEF,eventually inhibiting the cathodic process of galvanic corrosion.Under different conditions,the order of the galvanic current densityof Cu/Ag is:coupled>coupled under electric field without electric current>coupled under electric field with electric current.This can be ascribed that DCEF reduces the potential difference between copper and silver,and weakens the galvanic corrosion effect.However,the leakage current accelerates the migration of OH-ions caused by hydrogen evolution to the positive electrode of DCEF,resulting in significant inhibition of the cathodic process of galvanic corrosion.
作者
吴凤麒
祁康
黄华良
WU Fengqi;QI Kang;HUANG Hualiang(School of Chemistry and Environmental Engineering,Wuhan Institute of Technology,Wuhan 430205,China)
出处
《武汉工程大学学报》
CAS
2022年第3期266-273,共8页
Journal of Wuhan Institute of Technology
基金
国家自然科学基金(51401151)
湖北省自然科学基金(2018CFB525)
武汉工程大学研究生教育创新基金(CX2020263)。
关键词
直流电场
电偶腐蚀
铜
极化
电化学阻抗谱
薄液膜
direct current electric field
galvanic corrosion
copper
polarization
electrochemical impedance spectroscopy
thin electrolyte liquid
