溶融MgCl₂-KClおよびCaCl₂-KCl 2成分系の粘性

抄録

Viscosity coefficients of molten MgCl₂-KCl and CaCl₂-KCl mixtures have been precisely measured by using the oscillating vessel method over the temperature ranges of 590∼880°C and 715∼880°C, respectively. The equation derived by Knappwost was used to calculate the viscosity coefficient from the logarithmic decrement and the oscillating period of the vessel. The results obtained are summarized as follows:
(1) For both systems, the viscosity coefficient shows a negative temperature gradient over the entire range of composition. In the molten CaCl₂-KCl system the viscosity coefficient is lowest in pure KCl and increases with increasing CaCl₂ content over the entire range of composition. On the other hand, for the MgCl₂-KCl system, the composition dependence of viscosity is not monotonous as in the case of the CaCl₂-KCl system. The viscosity coefficient does not show any significant change within the composition range of 0∼33 mol% MgCl₂, but it increases markedly with increasing MgCl₂ content beyond that composition range. The maximum value is obtained at the composition of 80 mol% MgCl₂. The temperature gradient of the viscosity coefficient for the MgCl₂-KCl system is negative but is not so large as in the case of CaCl₂-KCl.
(2) The measured viscosity coefficients of molten KCl and MgCl₂ coincide with the values reported by the other investigators, but the value for molten CaCl₂ is slightly higher.
(3) The composition dependences of viscosity coefficients, activation energies and other physicochemical properties can well be explained by considering the changes due to the constituent chemical species of these systems.