【摘要】 油气输送管道表面的钝化膜易遭受HCO-3 破坏 ,从而引起管道报废造成重大损失。采用动电位扫描技术研究了管道用材 (X70钢 )在 4种不同NaHCO3 /Na2 CO3 浓度溶液中的极化曲线 ,并根据极化曲线确定其电位范围 ,测试了X70钢在NaHCO3 /Na2 CO3 溶液中钝化膜的电化学交流阻抗谱 (EIS) ,提出了X70钢在NaHCO3 /Na2CO3 溶液中的等效电路模型。结果表明 :X70钢在NaHCO3 /Na2 CO3 溶液中具有二次钝化行为 ,表面先后形成两种性能不同的钝化膜 ,随着HCO-3 浓度的增加 ,一次钝化膜逐渐溶解 ,二次钝化膜逐渐增厚 ,耐蚀性增强 ,起到了很好的保护作用。更多还原

【Abstract】 Passive films on the flow piping of oil and gas are easy to damage by HCO 3 - so as to bring about fail of pipeline and heavy loss. Thus polarization curves of X70 steel were studied in NaHCO 3/Na 2CO 3 solutions by potentio-dynamic scanning technique. In accordance to the potential determined by polarization curve, electrochemical impedance spectroscopy (EIS) was used to study the passive film of X70 steel in NaHCO 3/Na 2CO 3 solutions, and then equivalent circuit for X70 steel was presented. The results indicate that there exist secondary passivating for X70 steel in NaHCO 3/Na 2CO 3 solutions, and two different passive film form orderly on the surface. With the increase of HCO 3 concentration, first passive film dissolves gradually while secondary passive film increases, and the corrosion resistance increases.更多还原