温度对X70钢在高pH值溶液中腐蚀行为的影响

采用动电位极化、电化学阻抗谱技术、Mott-Schottky等测试方法,研究了温度对X70钢在高pH值溶液 (0.5 mol/L Na₂CO₃+0.5 mol/L NaHCO₃) 中钝化膜性能和电化学腐蚀行为的影响。结果表明：随着温度升高,X70管线钢的点蚀电位降低,维钝电流密度和钝化膜的极化电阻减小。在实验温度范围内,钝化膜为Fe₂O₃和Fe₃O₄的混合物,半导体类型为n型半导体,且不随温度升高而改变。但是随着温度的升高,钝化膜缺陷密度增加,膜厚度减小,腐蚀倾向增大。因此,温度升高会降低钝化膜的稳定性,导致其保护作用下降。

Effect of Temperature on Electrochemical Corrosion Behavior of X70 Pipeline Steel in High pH Solution

Effect of temperature on corrosion behavior of X70 pipeline steel in high pH solution (0.5 mol/L Na₂CO₃+0.5 mol/L NaHCO₃) was studied by means of potentiodynamic polarization, electrochemical impedance spectroscopy and Mott-Schottky measurements. Results showed that the pitting potential, passive current density and the polarization resistance of X70 pipeline steel all decreased with the increase of temperature. In the experimental temperature range, the formed passive film consisted mainly of Fe₂O₃ and Fe₃O₄ with features of n-type semiconductor. With the rising temperature, the thickness and donor density of the passive film increased, correspondingly, corrosion tendency of the steel increased. Therefore, the stability of the passive film decreased with the increasing temperature, which weakened the corrosion resistance of the X70 steel.