PDF《连续变化电导池常数法测定电导率的 等效电路分析及应用》

第 卷第 期 中国有色金属学报 年月18

3 2008

3 Vol.

18 No.3 The Chinese Journal of Nonferrous Metals Mar.

2008 文章编号:1004-0609(2008)03-0551-06 连续变化电导池常数法测定电导率的 等效电路分析及应用 胡宪伟,王兆文,路贵民,石忠宁,曹晓舟,崔建忠,赵兴亮 (东北大学 材料电磁过程研究教育部重点实验室,沈阳 110004) 摘要:通过分析所得的交流阻抗谱,探讨了采用交流阻抗技术使用连续变化电导池常数法测定溶液和熔盐电导 率的合理实验条件.通过对交流阻抗等效电路进行分析,认为实验电路的交流阻抗过程是电化学极化与浓差极化 共同控制的过程,对于溶液来说,扩散体现出 Warburg 扩散特性,而熔盐的扩散体现出 Gerischer 特性.采用边连 续变化电导池常数公式进行电导率计算时,对应的电路电阻最好选择对所得的 Nyquist 图拟合分析所得的溶液/熔 盐与电极及导线电阻之和.如果考虑拟合误差,也可以采用读取高频率时电路电阻的方法来进行计算. 关键词:连续变化电导池常数法;

电导率;

等效电路 中图分类号:TF

821 文献标识码:A Equivalent circuit analysis and application for electrical conductivity measurement by continuously varying cell constant technique HU Xian-wei, WANG Zhao-wen, LU Gui-min, SHI Zhong-ning, CAO Xiao-zhou, CUI Jian-zhong, ZHAO Xing-liang (The Key Laboratory of Electromagnetic Processing of Materials, Ministry of Education, Northeastern University, Shenyang 110004, China) Abstract: The alternating current (AC) impedance spectroscopies of continuously varying cell constant (CVCC) experimental conductivity cell system for solution and melts electrical conductivity measurement were analyzed. The AC impedance rational condition for electrical conductivity measurement by CVCC technique was determined. The AC impedance course of the circuit researched is controlled by both of electrochemical polarization and concentration polarization, Warburg diffusion character is represented for AC impedance diffusion course of solution, meanwhile, the melts concentration polarization impedance is assumed to be Gerischer impedance through equivalent circuit analysis of AC impedance. When the electrical conductivity is calculated by CVCC equation, the best option of the circuit resistance is the sum of solution and melts resistance and electrode and line resistance gained by fitting the equivalent circuit. If fitting error is considered, the circuit high frequency resistance is also a good option. Key words: continuously varying cell constant technique;

electrical conductivity;

equivalent circuit 电导率是反映溶液和熔盐物理化学性质的重要参 数, 对熔盐电导率的研究具有重要的理论和实际意义. 在溶液和熔盐电导率测定的传统方法中[1?2] , 电导 池常数是固定的,导线和电极电阻以及极化电阻的去 除步骤使得电导率的测定很繁琐[3] . WANG 等[4?5] 发明了一种采用长度连续变化的毛 细管电导池测量熔盐或溶液电导率的方法,称为连续 变化电导池常数法(Continuously vary cell constant, CVCC) 将其应用于铝电解体系熔盐电导率的研究. CVCC 法的原理是[4] :对于一个固定的电路和固 基金项目:国家自然科学基金重点资助项目(50334030) 收稿日期:2007-06-01;

修订日期:2008-01-07 通讯作者:王兆文,教授,博士;

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E-mail: [email protected] 中国有色金属学报

2008 年3月552 定的施加频率,电路中总电阻的变化与电导池常数的 变化是呈线性关系的,线性系数是关于溶液或熔盐电 导率的一个常数,电导池常数的变化是由电导池长度 的变化所引起,可以得到: ? ? ? ? ? ? ? ? ? ? ? ? ′ = L Z A d d