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采用动电位极化、电化学阻抗和电容测量等方法研究了X70管线钢在0.5 mol·L~(-1) NaHCO_3溶液中的电化学行为及生成钝化膜的电化学性能。极化曲线结果表明,X70钢在该溶液中有着明显的钝化行为;电化学阻抗表明,随着成膜电位正移,X70钢表面形成的钝化膜更加致密,均匀性更好;电容测量表明,X70钢在不同成膜电位下形成的钝化膜在-0.20～0.80 V扫描范围内为n型半导体,并且随着成膜电位的正移,空间电荷层更厚,施主密度逐渐减小,耐蚀性更好。
The electrochemical behavior of X70 pipeline steel in 0.5 mol·L -1 NaHCO 3 solution and the electrochemical performance of passivation film were studied by potentiodynamic polarization, electrochemical impedance and capacitance measurement. The results of polarization curves show that X70 steel has obvious passivation behavior in this solution. The electrochemical impedance shows that the passivation film formed on the surface of X70 steel is denser and the uniformity is better as the film formation potential shifts. Capacitance measurement The results show that the passivation films of X70 steel formed under different deposition potentials are n-type semiconductors in the -0.20 ~ 0.80 V scan range, and the space charge layer is thicker and the donor density is gradually decreased with the positive shift of the film deposition potential Corrosion resistance is better.