Abstract
When the mixed molten salts are used, it is essential to know the melting points of their multi component systems. So, the phase diagram of ternary PrCl3-CaCl2-NaCl system was determined on the basis of three kinds of the binary systems of PrCl3-NaCl, PrCl3-CaCl2, and CaCh-NaCl, and twelve kinds of the quasi binary systems of NaCl⋅CaCl2-PrCl3.
PrCl3 was prepared by the chlorination of Pr6O11 with NH4Cl and subsequently purified by sublimation. Resultant PrCl3 was 99.9% up in purity. Reagent grade of NaCl and CaCl2were thoroughly demoistened by heating at temperatures right below their melting points under vacuum for ca. 8h.
The phase diagrams w ere determined by the DTA method with an X-Y recorder on the basis of cooling curves of the molten salts under purified Ar atmosphere, wherein the cooling rates were about 10°C/min at 800°C and 6°C/min at 500°C.
The peritectic compound of NaCl⋅3 PrCl3 so far unknown was found in the binary NaClPrCls system, whose peritectic point was 587°C. The ternary PrCl3-CaCL-NaCl phase diagram had a eutectic and a peritectic point; the former was 440°C at 20-30-50 (PrCls-CaCl2-NaCl)mol%, the latter 587°C at 36-50-14 mol%.
