Electrochemical study of the passive behaviour of Ni-Cr alloys in a borate solution -: a mixed-conduction model approach
Electrochemical study of the passive behaviour of Ni-Cr alloys in a borate solution -: a mixed-conduction model approach
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DOI：
10.1016/s0022-0728(01)00423-5
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发表时间：
2001-05-04
影响因子：
4.5
通讯作者：
Sundholm, G
中科院分区：
文献类型：
--
作者：
Bojinov, M;Fabricius, G;Sundholm, G
本文讨论了新近提出的混合导电模型（MCM）在描述Ni-Cr合金阳极氧化膜电化学行为中的应用。MCM强调膜中离子点缺陷的空间分布与膜的电子导电性之间的耦合。介绍了MCM的基本概念，导出了MCM中离子缺陷浓度分布、电导率和交流响应的方程。本工作的实验部分包括表征Ni-Cr合金，纯Ni和纯Cr在0.1 M Na_2B_4O_7溶液（pH 9.3）在环境温度下的阳极行为，使用旋转圆盘和循环伏安法，接触电阻（CER）和电化学阻抗谱（EIS）技术。实验表明，Ni-20%Cr合金表面的膜与纯Cr表面的膜相似，而Ni-10%Cr合金表面的膜与纯Ni表面的膜相似。Ni-Cr合金钝化膜的导电性取决于膜中Ni和Cr价态的空间和电位分布。尽管在模拟中使用了几个简化的假设，理论和实验数据之间的定性协议实现。(C)2001 Elsevier Science B. V.保留所有权利。
This paper discusses the application of the recently introduced mixed-conduction model (MCM) to describe the electrochemical behaviour of anodic films formed on Ni-Cr alloys. The MCM emphasises the coupling between the spatial distribution of ionic point defects in the film and the electronic conductivity of the film. The basic concepts of the MCM are introduced, and equations for the concentration profiles of ionic defects, for the conductivity and for the ac response of the film are derived. The experimental part of this work consist of characterising the anodic behaviour of Ni-Cr alloys, pure Ni and pure Cr in 0.1 M Na2B4O7 solution (pH 9.3) at ambient temperature using rotating disc and cyclic voltammetry, contact electric resistance (CER) and electrochemical impedance spectroscopic (EIS) techniques. The experiments indicate that the film on a Ni-20%Cr alloy resembles that on pure Cr, whereas similarities can be found between the film on Ni-10%Cr alloy and pure Ni. The conductivity of the passive film formed on Ni-Cr alloys can be concluded to be based on the spatial and potential distribution of the valence states of Ni and Cr in the film. In spite of several simplifying assumptions used in the simulations, a qualitative agreement between the theory and experimental data was achieved. (C) 2001 Elsevier Science B.V. All rights reserved.