温度、pH值和氯离子对X80钢钝化膜内点缺陷扩散系数的影响

借助于Mott-Schottky和点缺陷模型(PDM)研究了溶液温度、pH值以及氯离子对X80管线钢在模拟土壤环境中所形成钝化膜内点缺陷扩散系数D₀的影响. 结果表明: 随着溶液温度的升高、溶液pH值的降低以及氯离子浓度的增大, 钝化膜内的施主密度呈现增大的趋势. 依据点缺陷模型可以得到钝化膜内点缺陷(假设点缺陷为氧空位或铁离子间隙)的扩散系数D₀达到10^－16～10^－17 cm²•S^－1, 且D₀随着溶液温度的升高、溶液pH值的降低及氯离子浓度的增加而增大.

Influences of Temperature, pH Value and Chloride Ion on the Diffusivity of Point Defect in the Passive Film on X80 Pipeline Steel

The influences of solution temperature, pH value and chloride ion concentration on the diffusivity of point defect (D₀) in the passive film on X80 pipeline steel, were investigated by Mott-Schottky plot analysis and point defect model. The results showed that the donor density increased with increasing solution temperature, increasing chloride ion concentration and decreasing pH value. On the base of a point defect model (PDM), the diffusivity of point defect (assuming that the donors are oxygen vacancies and/or iron interstices) was calculated to be of 10^－16～10^－17cm²&;#8226;S^－1. D₀ increases with increasing solution temperature, decreasing pH value and increasing chloride ion concentration.