SOLUBILITY OF SC2O3 IN NA3ALF6-K3ALF6-ALF3 MELTS

The electrolyte with high solubility for Sc2O3 is very important to realize the preparation of Al-Sc master alloy by the molten salt electrolysis. The solubility of Sc2O3 in K3AlF6-Na3AlF6-AlF3 melts is determined with an isothermal saturation method. The effects of KR (ratio of K3AlF6 to K3AlF6+Na3AlF6), the concentration of Al2O3 and the temperature on the solubility of Sc203 are also investigated. The results indicate that the solubility of Sc2O3 in K3AlF6-Na3AlF6-AlF3 melts increases and then decreases with KR increasing. The solubility of Sc2O3 is 8.698 wt.% in (K3AlF6-Na3AlF6)(KR25%)-18 wt.% AlF3 melts at 940 degrees C. The effect of temperature on the solubility is little, and the values are 8.575 wt.% and 8.762 wt.% respectively when the temperatures are 930 degrees C and 960 degrees C. The solubility decreases from 8.809 wt.% to 7.058 wt.% as the concentration of AL03 increases from 1.5 wt.% to 5.0 wt.% at 950 degrees C.