IMPROVEMENT OF THE TORSION PENDULUM IN MOLTEN VISCOSITY MEASUREMENTS

Improvements on a torsion pendulum suitable for viscosity measurements of a melt at high temperature are described. Two torsion wires to replace the single torsion wire of a conventional torsion pendulum were used. This improvement enhanced both the anti-disturbance and repeatability of the experimental curves, and made it possible to measure the molten viscosity of oxide melt in air ambience. It was found that the damping factor cu, changes nearly linearly with the kinematical viscosity. An empirical formula was derived for the damping factor alpha(1) and the viscosity. As an application of this method, the soaking effect on the viscosity of molten Li2B8O13 was investigated. The soaking process induces the decrease of viscosity and its activation energy of molten Li2B8O13. The torsion pendulum method shows high potential to the study of the relationship between the molten viscosity and composition, atmosphere, temperature and heat history of the melt.