Effect of Surface Viscosity on the Foaminess of Molten Oxides

Abstract

Foaming heights, when an Ar gas was blown into some binary oxide melts in the systems Na₂O-P₂O₅, BaO-B₂O₃, Na₂O₃-B₂O₃ and Na₂O-SiO₂ through a platinum sapillary, were measured to evaluate the foaminess. The maximum foaminess was observed for 17.8 mol% BaO-82.8 mol% B₂O₃ melt at 1 000°C, that lies near the two-liquid phase region (1 to 13 mol% BaO). From the results, it is presumably concluded that higher viscosity of melts itself is not enough to stabilize the foam, but higher surface tension depression with change of melt composition is also required, althogh the foaminess of the melts strongly depends on surface viscosities of the melts.