温度、氯离子和铬元素对J55油套管钢钝化膜半导体性能的影响

利用电容测量法及电化学阻抗谱技术研究了温度、氯离子浓度和铬元素对目前广泛使用的J55油套管钢在模拟土壤环境中所成钝化膜半导体性能的影响.结果表明:钝化膜呈现n型半导体特性,随着成膜温度的升高、铬元素的加入和氯离子浓度的增加,Mott-Schottky曲线直线部分的斜率减小,表明膜内杂质密度增加.阻抗谱结果表明:在同一温度下,离子在膜内的传递电阻R1随着氯离子浓度增加而减小,膜内的扩散系数YW增加;同一氯离子浓度下,随着成膜温度的升高,扩散系数YW减小.表明温度升高、溶液中氯离子浓度的增加以及铬元素的加入会使钝化膜对J55油套管钢基体的保护作用减弱.

Effects of temperature,chloride ion concentration and chromium element on the semi-conductive property of the passive film formed on J55 tubing and casing steel in simulation soil environment

The influences of temperature,chloride ion concentration and chromium element on the semi-conductive property of the passive film formed on J55 steel in simulation soil environment are studied by using capacitance measurement and electrochemical impedance spectroscopy (EIS).The results show that the passive film presents n-type semi-conductive property.The slopes of two straight line segments in Mott-Schottky curve decrease with the increases of temperature and chloride ion concentration and the addition of chromium into the steel,which indicates that the density of the defects in the passive film increases.EIS results show that the transfer impedance R1 of chloride ion in the film will decrease while the diffusion coefficient YW of chloride ion in the film will creases with the increase of chloride ion concentration at the same temperature.The diffusion coefficient YW of chloride ion in the film will increase with the increase of temperature under the same chloride ion concentration.These results show that that the corrosion protection effect of the passive film to the steel substrate decreases with the increases of temperature and chloride ion concentration and the addition of chromium into carbon steel.