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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 behaviors of X80 pipeline steel in various high concentration NaHCO 3 solutions were studied by potentiodynamic polarization curve, potentiostatic polarization curve, electrochemical impedance spectroscopy (EIS) and Mott-Schottky analysis. behavior. The results show that the stability and corrosion resistance of passivation film of X80 pipeline steel are affected by the concentration of NaHCO 3 solution. The electrochemical properties of the passivation film decrease with the increase of HCO 3 - concentration. The thickness of the inner Fe 3 O 4 layer does not change with the concentration of HCO 3 -. It is presumed that its formation is related to the film formation potential. However, the stability and corrosion resistance of the passive film are mainly affected by the γ-Fe 2 O 3 outer layer. According to the analysis of point defect (PDM) theory, the decrease of the stability and corrosion resistance of passive film when the concentration of NaHCO 3 solution increases is related to the increase of solution conductivity and the increase of HCO 3 ~ - adsorption at defect sites.