ISIJ International
Online ISSN : 1347-5460
Print ISSN : 0915-1559
ISSN-L : 0915-1559
The Molar Volumes and the Surface Tensions of Melts in the Systems CaF2-MF (M:Li, Na) and CaF2-MF2 (M: Mg, Sr, Ba)
Shigeta HaraHideharu ShibaikeKazumi Ogino
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1990 Volume 30 Issue 4 Pages 298-304


Surface tension and density of molten CaF2-based binary system were measured. From the measurement, the following results were obtained.
(1) Molar volumes of the melts in the systems CaF2-NaF, and CaF2-BaF2 are deviated positively from the additive rule, while for CaF2-LiF and CaF2-MgF2 melts negative deviation from the additive rule on volume is found, but CaF2-SrF2 melt behaves ideally on volume.
(2) Surface tensions of the melts in the binary systems can be expressed by Guggenheim's equation for regular solution, if a suitable interaction energy ω of each binary system is selected.
(3) The interaction energy ω, estimated from surface tension of binary fluoride systems, is related to the excess volume on mixing for CaF2-MxF2 equi-molar composition (x=1 for divalent and x=2 for monovalent fluoride).
(4) Liquidus lines for the systems, calculated from the interaction energy ω in combination with the thermochemical data are fairly in good agreement with those reported, but that for CaF2-NaF system is exceptional.
(5) Surface tensions of binary fluoride melts are strongly depended on packing density of fluorine ions on the surface.

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