Diffusion kinetics of water in glasses and glass-forming melts

The diffusion kinetics for both the entry and removal of water have been studied in a number of commercial and non-commercial glasses at temperatures in the melt and near and within the transformation range. These glasses include: fused silica, float glass, a commercial soda-lime-silica glass, E-glass, and alkali galliosilicate glasses. Effective diffusion coefficients and water solubilities were calculated based on infrared analysis of samples.; The diffusion kinetics of water in fused silica depends upon fictive temperature, forming method, and direction of diffusion. The removal of water from fused silica glasses at low temperatures occurs with a constant activation energy. At temperatures near the transformation range, the diffusion becomes non-Arrhenian.; The diffusion of water in float glass depends upon the direction of diffusion. At temperatures near the transformation range, the diffusion kinetics for the removal of water are Arrhenian from below {dollar}rm Tsb{lcub}g{rcub}{dollar} to temperatures above {dollar}rm Tsb{lcub}g{rcub}{dollar}. The solubility of water in float glass at temperatures near {dollar}rm Tsb{lcub}g{rcub}{dollar} is significantly greater than that in the melt. The solubility of water in the melt increases with temperature.; The effective diffusion coefficients determined in the melt for a second soda-lime silica glass correlate well with those determined near {dollar}rm Tsb{lcub}g{rcub}{dollar}, with Arrhenian diffusion in both temperature ranges. The solubility of water above the liquidus decreases with increasing temperature.; The activation energy for removal of water from E-glass at temperatures near the transformation range is significantly greater than activation energies for water diffusion in other glasses.; Lithium, sodium, and potassium galliosilicate melts with a 1:1 {dollar}rm Rsb2O{dollar}:{dollar}rm Gasb2Osb3{dollar} ratio were equilibrated in one atmosphere of water vapor at {dollar}rm1450spcirc C{dollar}. The rate of hydroxylation increases with decreasing silica content and increasing alkali ion field strength. The activation energy for dehydroxylation in the transformation range increases with decreasing silica content for lithium galliosilicate glasses.