X100钢在流动氯化物中的腐蚀行为

Corrosion Behavior of X100 Steel in Flowing Chloride

为了给油气田的腐蚀防护方案和研究方向提供借鉴,采用动电位极化曲线、交流阻抗谱以及扫描电镜(SEM)等手段研究了静止、流动2种状态下Cl^-浓度对X100钢腐蚀行为的影响。结果表明:流动状态改变不影响动电位极化曲线阴阳极反应机理;但和静止状态相比,流动的液体加速了腐蚀产物的迁移,并且增加了电极表面的剪切力,破坏了腐蚀产物层,增加了电极表面侵蚀离子的接触几率,使电极表面腐蚀点增多,腐蚀面积更大,腐蚀速率大幅度提高;阻抗谱对比研究发现,流动状态下的液相传质速度增加,溶液和电极表面之间离子浓度迅速达到均匀分布,导致Warburg阻抗消失,最终流体力学因素与腐蚀电化学因素共同作用,促进了流动状态下的腐蚀,使得腐蚀速率是静止条件下的200多倍,达到58.365 mm/a。

The effects of Cl^- concentration on the corrosion behaviors of X100 steel under static and flow conditions were studied by potentiodynamic polarization curves,AC impedance spectroscopy,scanning electron microscope( SEM) and so on. Results showed that the change of flow state did not affect the mechanism of the anode-anode reaction of potentiodynamic polarization curves. However,compared with the static state,the flowing liquid accelerated the migration of the corrosion product,increased the shearing force of the electrode surface,destroyed the corrosion product layer,increased the contact probability of the erosion ions of the electrode surface,increased the corrosion points of the electrode surface,increased the corrosion area and improved the corrosion rate. Furthermore,the comparison study of AC impedance spectrum found that the liquid phase mass transfer rate in the flowing state increased,and the ion concentration between the solution and the electrode surface quickly reached a uniform distribution,resulting in the disappearance of the Warburg impedance. Moreover,the final fluid mechanic factors interacted with the corrosive electrochemical factors promoted together the corrosion rate under flow condition,which was about 200 times of the corrosion rate under static condition and reached 58.365 mm/a.