Water diffusion and solubility in sodium aluminosilicate melts

The diffusivity and solubility of water at 1200 degrees C has been measured in a series of sodium aluminosilicate melts. Both the diffusivity and solubility of water in these melts decrease as Na2O is replaced by Al2O3. The partial molar solubilities of SiO2, Na2O and Al2O3 have been determined. The diffusivity of water in these melts exhibits an inverse relationship with the viscosity of the melt, which can be extended to include sodium silicate melts at the same temperature. The glass transformation temperature of these glasses decreases with increasing water concentration. The magnitude of this effect is shown to be similar to that for many other compositional systems.