Water release behaviour of soda-lime-silica glass melts

Abstract

Glass with the composiüon (in mol%) 16Na₂O * 10CaO * 74SiO₂ and a water content of 0.12 to 0.005 mol/1 has been investigated by IR spectroscopy. It has been found that at a water content of < 0.01 mol/l the rado of the extincdons of the absorpdon bands at 3550 and 2800 cm⁻¹ is not constant. Through the vacuum hot extraction method it could be shown that the release of bonded water from glass melt does not occur continuously, and is not determined by the kinetics of formadon of molecular water. At concentrations > 0.01 mol/l the largest part of bonded water is released at temperatures < 1000°C. Small amounts of water can be detected at temperatures > 1250°C as well. This high-temperature release of strongly bonded water is caused by changes in the structure of glass melt or by the simultaneous release of other volatile species.