X80管线钢钝化膜在各种高浓度NaHCO_3溶液中的电化学行为  

ELECTROCHEMICAL BEHAVIOR OF PASSIVE FILMS FORMED ON X80 PIPELINE STEEL IN VARIOUS CONCENTRATED NaHCO_3 SOLUTIONS

作　　者：范林[1] 李晓刚[1] 杜翠薇[1] 刘智勇[1] 

机构地区：[1]北京科技大学腐蚀与防护中心,北京100083

出　　处：《中国腐蚀与防护学报》2012年第4期322-326,共5页Journal of Chinese Society For Corrosion and Protection

基　　金：国家科技基础条件平台建设资助项目(2005DKA10-400)资助

摘　　要：采用动电位极化曲线、恒电位极化曲线、电化学阻抗谱(EIS)、Mott-Schottky分析等电化学方法研究了X80管线钢在各种高浓度的NaHCO_3溶液中形成钝化膜的电化学行为。结果表明,X80管线钢钝化膜的稳定性和耐蚀性会受到NaHCO_3溶液浓度的影响。钝化膜电化学性质随HCO_3^-浓度升高而降低;内层Fe_3O_4的厚度不随HCO_3^-浓度变化,推测其形成与成膜电位有关;内外膜层厚度比随HCO_3^-浓度的升高而增大,钝化膜的稳定性和耐蚀性主要受外层γ-Fe_2O_3的影响。根据点缺陷(PDM)理论的分析认为,NaHCO_3溶液浓度升高时钝化膜稳定性和耐蚀性的降低与溶液电导率的升高和HCO_3^-在缺陷点处吸附作用的增强有关。The electrochemical behavior of the passive films formed on X80 pipeline steel in various concen- trated NaHCO3 solutions was studied using potentiodynamic polarization curves, potentiostatic polarization curves, electrochemical impedance spectroscopy （EIS） as well as Mott-Schottky plots. The electrochemical test results indicated n-type semiconducting characters of the passive film, which was composed of two layers, with γ-Fe2O3 as the outer layer, and Fe3O4 as the inner layer. The properties of the passive films were influenced by the concentration of NaHCO3 solutions. The thickness of the inner layer merely remained constant, which was supposed to be dominated by the film forming polarization, whereas the thickness of the outer layer decreased with the increase of the concentration of NaHCO3 solution, which suggested that the outer layer plays a more important role to the corrosion resistance and stability of the passive film. According to the point defect model （PDM）, higher donor density and lower thickness of the passive films was affected by the enhanced conductivity of the solution and the intensified adsorption of HCO： at local defect sites with higher HCO3^- concentration.

关 键 词：X80管线钢 钝化膜 极化曲线 电化学阻抗谱 Mott—Schottky分析 

分 类 号：TG172[金属学及工艺—金属表面处理]