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采用动电位极化曲线、动电位电化学阻抗谱(DEIS)和SEM研究了X80管线钢在NaHCO_3溶液中的阳极电化学行为,结果表明:随着HCO_3~-浓度增加,X80管线钢腐蚀速率呈现先增加、后减小的趋势,X80管线钢“钝化”的临界HCO_3~-浓度为0.009 mol/L.随着HCO_3~-浓度增加,极化曲线阳极电流峰发生变化,当HCO_3~-浓度低于0.009 mol/L时,无阳极电流峰;当浓度在0.009—0.05 mol/L时,有一个阳极电流峰;当浓度增加到0.1 mol/L时,出现两个明显的阳极电流峰,且第1峰与第2峰的峰值电流比随浓度的增大而逐渐增大,DEIS结果与动电位极化曲线完全对应,二者相结合可以很好地研究在不同电位下NaHCO_3溶液中X80管线钢的腐蚀行为,同时对其腐蚀产物和腐蚀机理进行了分析。
The electrochemical behavior of X80 pipeline steel in NaHCO 3 solution was investigated by potentiodynamic polarization curve, potentiodynamic electrochemical impedance spectroscopy (DEIS) and SEM. The results showed that the corrosion rate of X80 pipeline steel increased with the increase of HCO 3 - First increase and then decrease, the critical HCO 3 ~ - concentration in X80 pipeline steel is 0.009 mol / L. With the increase of HCO 3 ~ - concentration, the anodic current peak of polarization curve changes. When HCO 3 ~ - There is no anodic current peak when the concentration is lower than 0.009 mol / L. When the concentration is 0.009-0.05 mol / L, there is an anodic current peak. When the concentration is increased to 0.1 mol / L, there are two obvious anodic current peaks , And the peak current ratio of the first peak and the second peak gradually increased with the increase of the concentration. The DEIS result completely corresponded to the polarization curve of the potentiodynamic. The combination of the two showed that the peak current ratio of the first peak and the second peak in the NaHCO_3 solution X80 pipeline steel corrosion behavior at the same time its corrosion products and corrosion mechanism were analyzed.