Tatsuhiko Ejima1 and Masatoshi Ogasawara2
1Department of Metallurgy, Faculty of Engineering, Tohoku University, Sendai
Density of the MgCl2-KCl binary melt has been measured as accurately as possible by means of the Archimedean method with two spherical sinkers of different sizes made of platinum. The results obtained are summarized as follows:
(1) The density decreases monotonously with rising temperature at each composition. The temperature coefficient of density for MgCl2 is considerably low, but those for KCl and MgCl2-KCl mixtures are nearly the same.
(2) The variation of the density at liquidus temperature with composition is well corresponding to the liquidus line of the phase diagram except on the MgCl2-rich side.
(3) The molar volume calculated from the density at 800°C deviates negatively from the additivity for the compositions less than 30 mol%KCl, and shows a positive deviation in the remaining range.
(4) The excess molar volume at 800°C shows a minimum at about 17 mol%KCl and a maximum at about 67 mol%KCl.
(5) The values of the partial molar volume of KCl at 800°C are considerably low on the MgCl2-rich side, but are approximately constant on the KCl-rich side. On the other hand, the partial molar volume of MgCl2 changes monotonously on the MgCl2-rich side, but it begins to increase at about 60 mol%KCl and becomes constant in the range more than 80 mol%KCl.
These trends are explained by the change of the ionic constituents.
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