Coupling between ionic defect structure and electronic conduction in passive films on iron, chromium and iron-chromium alloys
Coupling between ionic defect structure and electronic conduction in passive films on iron, chromium and iron-chromium alloys
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DOI：
10.1016/s0013-4686(99)00423-5
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发表时间：
2000-01-01
影响因子：
6.6
通讯作者：
Sundholm, G
中科院分区：
文献类型：
--
作者：
Bojinov, M;Fabricius, G;Sundholm, G
本文提出了Fe、Cr和Fe-Cr合金稳态钝化膜的定量动力学模型。它强调离子缺陷结构和电子传导之间的耦合。根据该模型，无源异质结可以表示为重掺杂的n型半导体-绝缘体-p型半导体结。在低电位的钝化状态下，在金属/膜界面注入的正缺陷发挥电子供体的作用。在高的正电位下，注入膜/溶液界面的负缺陷起电子受体的作用。在足够高的正电位下，这些离子缺陷和相应的电子空穴的浓度达到足够高的值，使薄膜转变为导体。这使得能够在膜表面上过钝化地溶解Cr和析氧。钝化膜的电子电导率的方程，取决于点缺陷的浓度，推导出来。用旋转环盘伏安法、光电流和阻抗谱以及接触电阻法（CER）测量了Fe、Cr、Fe-12%Cr合金和Fe-25%Cr合金在0.1M硫酸盐溶液（pH9.2）中钝化后的电阻，并与实验数据进行了比较。(C)2000 Elsevier Science Ltd;保留所有权利。
A quantitative kinetic model is presented for the steady-state passive films on Fe, Cr and Fe-Cr alloys. It emphasises the coupling between the ionic defect structure and electronic conduction. According to the model, the passive him can be represented as a heavily doped n-type semiconductor-insulator-p-type semiconductor junction. At low potentials in the passive state, the positive defects injected at the metal/film interface play the role of electron donors. At high positive potentials, the negative defects injected at the film/solution interface play the role of electron accepters. At sufficiently high positive potentials the concentration of these ionic defects and corresponding electron holes reaches high enough values for the film to transform into a conductor. This enables transpassive dissolution of Cr and oxygen evolution on the film surface. Equations for the electronic conductivity of the passive film, as depending on the concentration of point defects, are derived. The proposed model is compared with experimental data obtained for pure Fe, pure Cr, Fe-12%Cr alloy and Fe-25%Cr alloy passivated in 0.1 M berate solution (pH 9.2) using rotating ring-disk voltammetry, photocurrent and impedance spectroscopy and in situ de resistance measurements by the contact electric resistance (CER) technique. (C) 2000 Elsevier Science Ltd; All rights reserved.