pH值对X120钢在模拟鹰潭酸性土壤溶液中电化学行为的影响

摘要

The influence of pH value and applied potential on the electrochemical behavior of X120 steel in Yingtan simulated soil solution was investigated by electrochemical impedance spectroscopy ( EIS) and potentiodynamic polarization. The results showed that the Eoorr decreased with the increase of pH value, except at pH = 5. 5. The electrode reaction resistance R, at high pH values was higher than that at low pH values, indicating that the higher the pH value the greater the resistance to electrode corrosion. At the same pH value, R, increased firstly and then decreased with decieasing the applied potential, reached the maximum at about -0. 75 V. In addition, the influence of pH value on the electrochemical behavior, determined by either measuring the potentiodynamic polarization curves with fast and slow scan rates or EIS, was the same.%采用电化学阻抗谱法和动电位极化法研究了不同pH值(3.5～6.5)和不同外加电位(-0.58～-1.20 V)对X120钢在模拟鹰潭酸性土壤溶液中电化学行为的影响。结果表明，随着pH值的升高，自腐蚀电位整体呈下降趋势，在pH=5.5附近电位有反弹；高pH值溶液中电极反应电阻Rt普遍大于低pH值下的Rt,即pH越高电极腐蚀过程的阻力越大；在同一pH值下，随着外加电位的降低，Rt先增大后减小，在-0.75 V附近达到最大值；这是由于电极过程在阳极电位区受活化控制，在-0.75 V附近受活化和扩散共同控制，而阴极电位区重新受活化控制所致。另外，快慢速率扫描动电位极化曲线反映的pH值对阴阳极极化行为影响的规律与阻抗谱反映的规律一致。