Glass refining at reduced pressures

Abstract

The behaviour of bubbles in the glass melt for colour-TV screens has been investigated at reduced pressures using modified high-temperature photography and a mathematical model of single bubbles. The considerable acceleration of the process predicted by the mathematical model and resulting in high values of bubble-growth rates has been confirmed by experiments. Mathematical modelling of the small rectangular continual refining room has shown that the main quantity determining refining efficiency is the already mentioned bubble-growth rate. The value of this quantity needed for effective refining being in the region around 1 · 10^-6 m/s is only slightly dependent on temperature, pressure and glass composition. As is obvious from the presented results, the saturation or oversaturation of glass melt by diffusing gas at given glass composition, pressure and temperature is the general condition of successful refining.