目前,有关温度对CO2-3 HCO3-环境下X80管线钢腐蚀行为的影响规律尚无统一的认识.为了探究高强度钢在不同温度的0.5 mol/L Na2CO3+1.0 mol/L NaHCO3溶液中的腐蚀行为,采用动电位极化、电化学阻抗技术,并结合金相显微镜观察研究了温度对X80管线钢在0.5 mol/L Na2CO3+1.0 mol/L NaHCO3溶液中电化学腐蚀行为的影响规律,并通过Mott-Schottky曲线对不同温度下钝化膜的半导体性质进行探讨.结果表明:温度从30℃上升至75℃时,X80钢的点蚀电位和电荷转移电阻均逐渐减小,腐蚀现象越明显;当温度达到90℃时,点蚀电位和电荷转移电阻反而增大,腐蚀程度有所减缓;在0.3～0.7 V内,钝化膜呈现出典型的n型半导体特征;随着温度的升高,钝化膜内的施主电流密度和平带电位呈现先降低后增加的趋势,钝化膜稳定性先减弱后增强;在75～90℃之间存在一个临界温度,此温度下钝化膜的缺陷密度最大,保护性最差.
In order to explore the corrosion behavior of high strength steel in 0.5 mol/L Na2 CO3 + 1.0 mol/L NaHCO3 solution of different tem perature,the effects of temperature on electrochemical corrosion behavior of X80 pipeline steel in 0.5 mol/L Na2 CO3 + 1.0 mol/L NaHCO3 solution were investigated by potentiodynamic polarization,electrochemical impedance spectroscopy(EIS) and metallographic microscope,and the semiconductor properties of passive films at different temperatures were studied by Mott-Schottky curves.Results showed when the temperature rose from 30 ℃ to 75 ℃,the pitting potential and charge transfer resistance of X80 steel decreased gradually,and the corrosion phenomenon became more obvious.When the temperature reached 90 ℃,the pitting potential and charge transfer resistance increased,and the corrosion degree reduced gradually.In the range of 0.3 V to 0.7 V,the passivation film exhibited n-type semiconductor characteristics.With the increase of temperature,the current density of donor and fiat band potential of passive film decreased firstly and then increased,and the stability of pas sive film declined firstly and then increased.A critical temperature existed between 75 ℃ and 90 ℃,and at this temperature,the defect density of passive film was the maximum and the protection was the worst.
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