THE EFFECT OF MAGNESIA ON THE DEVITRIFICATION OF A SODA-LIME-SILICA GLASS1

Abstract

The effect of magnesia on the devitrifimtion of a certain soda-lime-silica glass has been ascertained. The initial glass had a composition 1.15Na2O.0.84CaO.6SiO2, and tridymite separated as primary phase. On substitution of MgO for CaO, tridymite remained primary phase, and the melting point was lowered, but the curve shows double inflection. Addition of 2% of MgO lowered the melting point almost 200°, with the glass passing from the field of tridymite to that of Na2O.3CaO.6SiO2, but with more than 3%, MgO diopside became the primary phase, and the melting point rapidly increased.