利用线性极化、电化学阻抗谱及表面分析技术研究了N80钢在NaCl溶液中腐蚀锈垢形成过程的电化学行为。结果表明, 随着锈垢的形成, 腐蚀过程由电化学控制转变为扩散控制, 电荷传递电阻及扩散电阻减小, 阻抗扩散部分直线与实轴夹角逐渐减小。提出了试样表面锈垢的物理模型, 解释了锈垢层疏松多孔特性与阻抗谱特征之间的相关性。腐蚀锈垢分为两层, 表面层疏松多孔, 内层较为致密, Cl-在内层产生浓集, 对基底腐蚀起促进作用。

The corrosion behaviors of rusted N80 steel in NaCl solution were studied by linear polarization, electrochemical impedance spectroscopy (EIS) and surface analysis techniques. The results indicated that the control step of the corrosion process changed from electrochemical reaction to diffusion process, the charge transfer resistance and the diffusion resistance decreased. The angles between diffusion tail in the Nyquist plot at low frequency and the real-axis decreased with the increase of immerging time of N80 steel in 0.2 mol/L NaCl solution. A physical model describing the rusted steel was used to explain the correlation of EIS characters and porosity of corrosion rust layer. The corrosion rust was found to have two layers, the outer layer was loose and porous, the inner layer was relatively compact. The Cl- was concentrated in the inner layer and the corrosion process of the substrate metal was promoted.