Cl^-对X80管线钢在HCO_3^-溶液中的电化学行为影响  

Effect of Cl^- on Electrochemical Behavior of X80 Pipeline Steel in HCO_3^- Solutions

作　　者：周建龙[1] 李晓刚[1] 张新[2] 李涛[1,3] 孙敏[1] 杜翠薇[1] 

机构地区：[1]北京科技大学腐蚀与防护中心,北京100083 [2]环境保护部核与辐射安全中心,北京100082 [3]内蒙古科技大学材料与冶金工程学院,包头014010

出　　处：《腐蚀与防护》2013年第10期865-869,共5页Corrosion & Protection

基　　金：国家自然科学基金重点项目(51131001)

摘　　要：采用动电位极化曲线、电化学阻抗谱(EIS)及SEM研究了X80管线钢在NaHCO_3/NaCl溶液中的电化学腐蚀行为。结果表明,X80管线钢在HCO_3^-/Cl^-溶液体系中,随着Cl^-浓度增加,钝化区逐渐变窄,点蚀电位逐渐降低,维钝电流密度逐渐增加,耐蚀性降低。在HCO_3^-/Cl^-溶液体系中,Cl^-与HCO__3^-在金属表面产生竞争吸附表现为两种效应:一种是HCO_3^-的钝化效应,该效应使钝化膜增厚,阳极电流密度下降,从而金属保持钝性状态;另一种是Cl的侵蚀效应,该效应使钝化膜变薄或离子电导增大,阳极电流密度增大,金属失去钝性。用点缺陷模型解释了钝化膜的生成和破裂过程。X80管线钢的耐蚀性与HCO_3^-和Cl^-的浓度比有关,该比值越大,则钝化性能越强;Cl^-浓度越大,则活性越强。The electrochemical behavior of X80 pipeline steel in NaHCO3-/NaCl- mlutions was studied using potentiodynamic polarization curves, electrochemical impedance spectroscopy（E IS） and SEM. The results show that the passivation region becomes narrower, the pitting potential decreases and the passivation current density increases gradually with the increase of Cl- concentration, and the corrosion resistance of X80 pipeline steel lowers. In HCO3 /Cl- solutions, Cl- competes with HCO2- for adsorption on the surface of X80 pipeline, which results in two kinds of effects： the passivation effect of HCO3- and the aggressive effect of C1 . The passive film thickens and the anodic current density decreases because of the former effect, which keeps the metal in passive stare On the contrary, the latter effect makes the passive film thinned or the solution conductance increased, which leads to the increase of anodic current density and to the loss of metal passivity. The point defect model was used to explain the initiation and breakdown process of passive film. The corrosion resistance of X80 pipeline steel in HCO3-/C1- solutions system is strongly relevant to the concentration ratio of HCO3- to Cl1-. The corrosion resistance of X80 pipeline steel is strengthened with the increase of HCO3- concentration and weakened with the increase of HCO3- concentration.

关 键 词：X80管线钢 动电位极化曲线 电化学阻抗谱 HCO3-/Cl-溶液 

分 类 号：TG172.4[金属学及工艺—金属表面处理]