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采用动电位极化曲线和动电位电化学阻抗谱对含不同浓度Cl-和HCO3-溶液体系中N80钢的阳极电化学行为进行了研究.溶液体系中不含Cl-的情况下,HCO3-的浓度超过0.03 mol.L-1时可使N80钢发生钝化.Cl-能极大提高发生钝化的HCO3-浓度临界值,同时对材料表面的钝化膜具有强烈的破坏作用.在阳极区,同等HCO3-浓度下,含Cl-的溶液体系中点蚀电位下降,维钝电位区间变窄,维钝电流密度升高.动电位电化学阻抗谱结果与动电位极化曲线基本对应.等效电路中电器元件与极化电位的关系表明,在含Cl-的溶液体系中N80钢的钝化膜粗糙度与致密性均有所下降,维钝电流密度升高主要由电荷转移电阻的降低所致.
The electrochemical behavior of the anode of N80 steel with different concentration of Cl- and HCO3-solution was investigated by potentiodynamic polarization curve and potentiodynamic impedance spectroscopy. In the absence of Cl- in the solution system, HCO3- N80 steel can be passivated when the concentration exceeds 0.03 mol·L-1, Cl- can greatly increase the passivation HCO3- concentration critical value, and at the same time, it has a strong destructive effect on the passive film on the surface of the material. Under the same concentration of HCO3-, the pitting potential of the solution containing Cl- decreased, the dimension of the dimension of the blunt potentials became narrower, and the dimension of the blunt current increased.The electrokinetic impedance spectroscopy results of the potentiodynamic polarization basically corresponded with that of the potentiodynamic polarization. The relationship between the electrical components and the polarization potential in the effective circuit shows that the roughness and densification of the passivation film of N80 steel in the solution system containing Cl- decrease. The increase of the dimensionless current density is mainly caused by the decrease of charge transfer resistance Due.