2205双相不锈钢与316L奥氏体不锈钢钝化膜内点缺陷扩散系数的计算分析

应用电容测试法并借助于点缺陷模型（PDM）计算了2205双相不锈钢与316L 奥氏体不锈钢在NaCl溶液中所形成的钝化膜内点缺陷的扩散系数，利用实验测得钝化膜的稳态电流和PDM模型对计算结果进行了验证分析。通过两种计算方法得到点缺陷在2205双相不锈钢与316L奥氏体不锈钢钝化膜内的扩散系数约为10^-23cm²/s~10^-20 cm²/s数量级，并发现在模拟海水溶液中2205钢的扩散系数比316L钢小，氧空位所形成的点缺陷在2205钢的钝化膜内比316L钢扩散困难，从而使得2205不锈钢的钝化膜比316L不锈钢更加致密与完整，保护性能更好。

CALCULATION AND ANALYSIS OF DIFFUSIVITY OF POINT DEFECTS IN PASSIVE FILM FORMED ON 2205 DUPLEX STAINLESS STEEL AND 316L AUSTENITIC STAINLESS STEEL

The diffusivity of point defects in the passive film formed on 2205 duplex stainless steel and 316L stainless steel in NaCl solution was calculated by means of capacitance measurement and PDM (point defect model). The calculated result was testified and analyzed by experimental steady current density of passive film and PDM. It is showed that the order of magnitude of diffusivity is about 10^-23 cm²/s~10^-20 cm²/s, and the diffusivity of 2205 DSS is less than 316L SS in simulated ocean solution. It is concluded that the diffusion of point defect which is caused by oxygen vacancy in 2205 DSS is harder than 316L SS, so in contrast to 316L SS, the passive film of 2205 DSS is much densified and compact with completeness and excellent protection.