Nd_2O_3对AlF_3-(Na/Li)F-Al_2O_3熔体性质及结构的影响研究

The Investigation of the Influence of Nd_2O_3 on Properties and Structure of AlF_3-(Na/Li)F-Al_2O_3 Molten Salt

为研究熔盐电解制取Al-Nd中间合金基础电解质AlF_3-(Na/Li)F-Al_2O_3-Nd_2O_3在一定组成及温度(1183 K^1263 K)范围内的主要物理化学性质变化规律,并间接地分析熔体结构信息及Nd_2O_3的溶解过程,分别采用阿基米德法、旋转法、连续变化电导池常数(CVCC)法测量熔盐体系的密度、粘度、电导率。结果表明,AlF_3-NaF-8%LiF-6%Al_2O_3(质量分数,下同)体系(NaF/AlF_3=2.2,摩尔比)在1183 K^1263 K范围密度随温度呈线性递减变化,而粘度随温度升高而降低,电导率随温度升高而升高,但呈非线性变化关系;在1223 K时,体系中Nd_2O_3质量分数达到2.5%左右时,密度、粘度、电导率分别达到极值;Nd_2O_3质量分数小于2.5%范围内,Nd_2O_3主要以化学溶解为主,并生成堆积密度大的Nd-O-F络合离子团;Nd_2O_3质量分数大于2.5%时,Nd_2O_3主要以物理溶解为主。

The main physical and chemical properties （density, viscosity and conductivity） of AlF3-（Na/Li） F-Al2O3- Nd2O3 molten salt for preparing Al - Nd intermediate alloy were studied by archimedes method, rotation method, continuous change constant of conductance pool method at specific composition and temperature range （1183 K - 1263 K）, and melt structure information and dissolving process of Nd2O3 were analyzed indirectly. The results show that the density decreased with temperature rising linearly, viscosity decreased with temperature rising and conductivity increased with temperature rising nonlineariy of AlF3 -NaF- 8% LiF- 6% A1203 melt system （NaF/AlF3 = 2. 2, molecular ratio） in the temperature range of 1183 K- 1263 K. The density, viscosity and conductivity reached to extreme value at the temperature of 1223 K with the content of Nd203 closed to 2.5% （ mass fraction）, respectively. The main dissolving ways of Nd203 less than 2.5% （ mass fraction） is chemical dissolution with Nd - O - F complex ions group characterized high stacking density, and the main dissol- ving ways of Nd2O3 more than 2.5% （mass fraction） is physical dissolution. Key words： physical and chemical properties; molten salt electrolysis ; Al - Nd intermediate alloy; melt structure; chemical dissolution