Liquidus temperature of Na₃AlF₆-Al₂O₃-X•F systems(X=Li, Na, Mg, Ca, Al)

Abstract

Hot-thermocouple has two functions, that is, measuring the temperature like ordinary thermocouple and heating the molten samples with the same Pt-Rh filament. The molten samples held on the filament can be observed through the microscope. By applying this method, the liquidus temperature of Na₃AlF₆-Al₂O₃-X•F systems (X = Li, Na, Mg, Ca, Al) has been determined.
Our liquidus lines show a good agreement with the previous result which was determined by the direct observation like our method. Na₃AlF₆-Al₂O₃ system has a eutectic point at the composition of 10.6wt%Al₂O₃ and its temperature is 961°C. The effects of additive flouride on liquidus temperature of Na₃AlF₆-Al₂O₃ system have been also measured. LiF seemed to give a remarkable effect to lower the liquidus temperature in small addition.