Influence of water dissolved in the structure of soda-lime-silica glass on melting, forming and properties: state-of-the-art and controversial issues

摘要

The paper summarizes the information available about the water content of soda-lime-silica glass, the factors that influence it and the influence exerted by water in glass on redox and sulphur retention, on fining, on the melting and forming behaviour, workability and the physical and chemical properties of the melt. Such issues were discussed by the authros in their presentations at the first Forum on Water in Glass, organized in 1997 by Technical Committee 14 (TC 14 "Gases in Glass") of the International Commission on Glass (ICG). The present paper reports the conclusions of the final discussion, highlighting the issues on which consensus was reached (IR spectroscopy is suitable to monitor the water content; the water content of conventionally fired containers is 300 to 400 ppm and daily oscillations are moderate; water, redox and sulphur interact mutually; water lowers the viscosity; the influence of water content variations on the radiative thermal conductivity is moderate) and the still controversial issues (influence of water and hydroxides in the batch on the final water content; influence of water in the batch and atmosphere on the redox state of the glass; influence of oscillations of OH level on the workability; influence of OH level on ease of forming, product quality and stength).