Physico-chemical investigation of the behavior of sodium in the float glass process Part 2. Reactions of sodium and oxygen dissolved in the bath of molten tin

Abstract

The chemical reactions which may be evoked by the Joint action of sodium and oxygen dissolved in the molten tin of the float bath are discussed from a thermodynamic point of view. It is shown that the prevalent thermodynamic conditions preclude precipitation of Na2O from the tin melt at decreasing temperatures, but admit chemical reactions of sodium and oxygen with the refractory material (burnt fire clay). The thermodynamic conditions for the sodium and oxygen transfer from the tin bath to the refractory lining are specified, and the reactions occurring in the lining by the incorporation of Na2O are considered. The results indicate that large amounts of Na2O can be incorporated in the refractory material. Since under the prevailing conditions the sodium and oxygen contents of the tin melt are very small, however, the transport of large amounts of Na2O from the glass melt to the refractory lining can only take place over a long time period.