NaHCO3溶液中X100和X80管线钢钝化膜性能比较

采用动电位极化曲线分析了X100和X80钢在0.5 mol/L NaHCO₃溶液中的极化行为，通过电流密度-时间曲线以及Mott-Schottky曲线研究了两种钝化膜的生长机制和钝化膜的半导体性质，借助电容测量和点缺陷模型计算了两种钝化膜内的缺陷密度和缺陷扩散系数。结果表明：两种管线钢在该介质中都存在一个很宽的钝化区间，钝化膜的生长均受电迁移和溶解-沉积混合机制控制，钝化膜均为n型半导体。但与X80钢相比，X100钢具有更低的自腐蚀电流密度和维钝电流密度，及更高的击穿电位。X100钢表面钝化膜也更为致密、均匀、稳定，钝化膜的施主密度更低，缺陷扩散系数约是X80钢的1/3。因此，X100钢比X80钢生成的钝化膜表现出更好的抗均匀腐蚀性能和抗点蚀性能。

Comparison of Passive Films on X100 and X80 Pipeline Steels in NaHCO3 Solution

The polarization behavior of X100 and X80 pipeline steel in 0.5 mol/L NaHCO₃ solution were analyzed by potentiodynamic polarization, and the growth mechanism and semiconductor properties of both passive films were investigated using current density versus time curves and Mott-Schottky measurement, and the density and diffusion coefficient of point defect in passive films were calculated by means of capacitance measurement and point defect model (PDM). The results showed that the growth process of the two passive films formed on pipeline steels was controlled by electromigration and dissolution-deposition process, and the conductive characteristics of the two passive films belonged on n-type semiconductor. However, in comparison with X80 steel, X100 steel exhibited lower corrosion current density and passive current density, but a higher pitting breakthrough potential. The passive film on X100 steel had a lower donor density and point defect diffusion coefficient. Therefore, X100 steel displayed a better general corrosion and pitting corrosion resistance than X80 steel.