Helmut Franz

Durability and corrosion of silicate glass surfaces

Abstract Durability of glass, or its resistance to corrosion, as a function of glass composition, surface state, and environmental conditions, has been discussed extensively in context with concepts for chemical reaction mechanisms and changes in surface structure involved in corrosion processes. In practical terms, durability and corrosion of silicate glasses are mainly affected by surface composition, and conditions during manufacturing, fabrication, storage and service. Deterioration of surface properties due to corrosion may range from light haze or stain to severe damage such as iridescence or opacity. Methods for improving durability and reducing corrosion include chemical modification of surface layers by ion-implantation, ion-exchange, or chemical reaction, application of protective materials, and deposition of durable oxide films on the glass surface.

Effect of Water Content on Density, Refractive Index, and Transformation Temperature of Alkali Borate Glasses

The solubility of water vapor in boric oxide [1] and binary alkali borate melts [2] has been found to be proportional to the square root of the partial pressure PH2O, indicating that water vapor introduced at PH20< 1 atm is dissolved in the form of hydroxyl groups (−OH), in analogy to the incorporation of water in silicate melts [3–6]. Correlations between the bond state of dissolved hydroxyl groups and the structure of alkali borate [2] and alkali silicate [7] glasses have been derived from solubility data and infrared absorption spectra. The effect of water content on some properties of silicate glasses have been discussed previously [8]. This study will present experimental data on the effect of the hydroxyl concentration on density, refractive index, and transformation temperature of binary lithium, sodium, and potassium borate glasses containing 0 to 33 mole percent R20. The corresponding properties of water-free alkali borate glass systems have been extrapolated. Results are discussed in terms of a simplified structural model interpreting the effects of incorporated hydroxyl groups on structure sensitive properties of alkali borate glasses.