NaCl-CaCl_(2)-SrCl_(2)三元相图的测定

MEASUREMENT OF THE PHASE DIAGRAM OF MOLTEN SALT SYSTEM NaCl-CaCl_(2)-SrCl_(2)

本文以NaCl-CaCl_(2)-SrCl_(2)三元计算相图作为“预知图形”,采用高灵敏度的微型差热分析仪,测定该三元相图是三元低共晶体系,其低共晶点E的组成(百分摩尔)为NaCl41.9%,CaCl_(2)40.0%,SrCl_(2)18.1%,温度为744K。

In this paper, the phase diagram of molten salt system NaCl-CaCl3-SrCl_(2) has been determined by MDTA with high sensitivity, using the calculated phase diagram as a prior one. Especially, it is considered that supercooling of salts affects the accuracy of measurement.This ternary system contains an eutectic point at 41.9 mol% NaCl,40.0 mol%CaCl_(2), 18.1 mol%SrCl_(2), 744K. In the liquidus surface for saturation with the CaCl_(2)-SrCl_(2) solid solution unvariant line starts at 823K, and the liquid composition is 24.8 mol%NaCl, 50.1 mol%CaCl_(2),25.1 mol%SrCl_(2).This phase diagram is important for the practice of sodium electrolysis. It may furnish an example in judging the reliability of a thermody-namic model that has been applied for calculation of the phase diagrams of charge-asymmetric ternary molten salt systems.