Simultaneous Evaluation of Viscous and Crystallization Behaviors of Silicate Melts by Capacitance and Viscosity Measurements

Abstract

This study set out to develop a device capable of simultaneously measuring viscosity and capacitance. The viscosity measurements required prior calibration of the device. However, room-temperature calibration using silicone oil is affected by the immersion depth of the rod, rotational speed of the crucible, and diameter/length of the torsion wire. The calibration results revealed that the potential produced by the torque acting on the torsion wire, generated by the viscous resistance of the silicone oil, was stable when the rod was immersed to a depth of 10 mm. Upon varying the rotational speed of the crucible and viscosity of the silicone oil, the rotational speed of the crucible was found to be proportional to the potential. Furthermore, the measured potential was found to be proportional to the viscosity. Based on the room-temperature calibration results, the immersion depth of the rod was set to 10 mm. By adjusting the diameter and length of the torsion wire, a wide range of viscosities could be measured. High-temperature calibration was performed using the SRM2 standard-viscosity material and involved comparing the measured viscosity with the recommended value for SRM2 or with the results of viscosity measurements obtained by other laboratories. The viscosity measurements obtained in the present study were in good agreement with both the recommended values and the results obtained by other laboratories. Therefore, the device designed in the present study was capable of precisely measuring the viscosity. Finally, the device could also simultaneously measure the viscosity and capacitance of the simple 50CaO-50SiO2 (mol%) and complex 46.4CaO-38.6SiO2-10CaF2-5B2O3 and 43.6CaO-36.4SiO2-10CaF2-10B2O3 (mol%) melts. Furthermore, a drastic increase in the viscosity led to a drastic decrease in the capacitance, corresponding to the crystallization of the melt, which is assumed to affect the viscosity of the melt.