基于等效电路模型的X90钢交流腐蚀动力学行为

AC Corrosion Electrode Process of X90 Steel Based on Equivalent Circuit Model

通过电化学测试明确了交流电作用下X90钢腐蚀电位和实时电位波形的变化规律;建立了包含阳极电极过程和阴极电极过程的等效电路模型,并通过Multisim进行了求解,通过分析阳极和阴极电荷转移电阻(R_(a),R_(c))、双电层电容(Cdl)对交流腐蚀电位及阳极和阴极法拉第电流(I_(a),I_(c))、非法拉第电流(I_(dl))的影响,分析了电极过程动力学参数对交流腐蚀的影响。结果表明;随着交流电密度增加,X90钢腐蚀电位的负移程度先增大后减小,且于100 A/m2处达到最小值,实时电位波形与正弦交流干扰具有相同的频率和波形;随着R_(a)增大,通过阳极和阴极过程的法拉第电流均会逐渐减小;当阳极过程和阴极过程电荷转移电阻大小不同时,交流电通过腐蚀电极时会发生整流效应,使实时电位的波形中产生直流偏置,造成腐蚀电位发生偏移;相对于电荷转移电阻,双电层电容对交流电作用下腐蚀电极过程的影响更为明显。

The change law of corrosion potential and real-time potential waveform of X90 steel under the action of alternating current was clarified by electrochemical test;an equivalent circuit model including anodic electrode process and cathodic electrode process was established and solved by Multisim.By analyzing the effects of anodic and cathodic charge transfer resistances(R_(a),R_(c))and electric double layer capacitance on AC corrosion potential and anodic and cathodic Faradaic currents(I_(a),I_(c))and non-Faradaic currents(I_(dl)),the effects of electrode process kinetic parameters on AC corrosion were analyzed.The results showed that with the increase of AC density,the degree of negative shift of corrosion potential of X90 steel first increased and then decreased,and reached the minimum value when the current density was 100 A/m2.The real-time potential waveform had the same frequency and waveform as sinusoidal AC interference.As R_(a)increased,the Faradaic current through both the anodic and cathodic processes gradually decreases When the anodic process and the cathodic process had different charge transfer resistances,a rectification effect would occur when the alternating current passes through the corrosion electrode,causing a DC bias in the waveform of the real-time potential,causing the corrosion potential to shift.Compared with the charge transfer resistance,the electric double layer capacitance had a more obvious effect on the corrosion process of the electrode under the action of alternating current.