熔盐电解法氧离子在氯化钙熔盐中的扩散动力学研究  

Study on Diffusion Dynamics of O in Molten CaCl for Molten Salt Electrolysis

作　　者：但林阳 刘楠[1] 李泽全[1] 李雪敏[1] Dan Linyang;Liu Nan;Li Zequan;Li Xuemin(Chongqing University,Chongqing 401331,China)

机构地区：[1]重庆大学,重庆401331

出　　处：《稀有金属材料与工程》2021年第7期2409-2414,共6页Rare Metal Materials and Engineering

基　　金：重庆大学教改项目(02200051071017);重庆市教委科学技术研究项目(KJQN201800106)。

摘　　要：以分子模拟为基础,构建了O^(2-)/CaCl_(2)的全原子模型,以Born-Mayer-Huggins(BMH)势函数对体系进行描述,研究了O^(2-)在CaCl_(2)熔盐中的扩散动力学行为。结果表明:1073K时O^(2-)扩散系数为2.01×10^(-5)cm^(2)/s,与Ferro经验公式的计算值一致;同时发现温度与O^(2-)的扩散系数呈正相关关系,当温度为1473 K时,O^(2-)扩散系数提高到5.66×10^(-5)cm^(2)/s;拟合得到O^(2-)在CaCl_(2)熔盐中的扩散活化能为15.6kJ/mol。在微观结构方面,由于静电吸引的作用,熔盐中Ca2+会在O^(2-)周围形成正电配位层,并束缚了O^(2-)的扩散;O^(2-)从形成的Ca2+配位层中逸出需要越过的能垒约为1.7J。本文不仅揭示了O^(2-)在CaCl_(2)熔盐中的扩散动力学行为,也为计算机模拟研究改良熔盐配方提供基础。Full-atom models of O^(2-)/CaCl_(2)were constructed and the systems were described by Born-Mayer-Huggins(BMH)potential function to investigate the diffusion dynamic behavior of O^(2-)in CaCl_(2)molten salt based on molecular simulations.The results show that the calculated diffusion coefficient of O^(2-)at 1073 K is about 2.01×10^(-5)cm^(2)/s,which is consistent with the reported value of Ferro’s literature.At the same time,the diffusion coefficient of O^(2-)is closely related to temperatures.When the temperature increases to 1473 K,the diffusion coefficient of O^(2-)is 5.66×10^(-5)cm^(2)/s.The activation energy for diffusion of O^(2-)in CaCl_(2)molten salt is 15.6 kJ/mol by fitting diffusion coefficients at various temperatures.In terms of the microstructure,Ca2+can form a positive coordination layer to inhibit the diffusion of O^(2-)due to the electrostatic attraction.The energy barrier that O^(2-)needs to escape from the Ca2+coordination layer is about 1.7 J.This article not only reveals the diffusion dynamic behaviors of O^(2-)in CaCl_(2),but also provides guide for the research of molten salt compounds by computer simulation.

关 键 词：熔盐电解法 分子模拟 扩散系数 

分 类 号：TF111.522[冶金工程—冶金物理化学]