Abstract:
We present the results of experiments of etching on commercial soda-lime-silicate glasses (SLS) immersed in dilute hydrofluoric acid solutions. The effect of different parameters (such as concentration, immersion time, temperature and irradiation) on the etching of silica has been investigated and expressed by the loss in gm/cm2. It has been found that the dissolution of glass increases with increasing both immersion time and HF concentration. The results show that the sodium concentration increases in the leachant solution as the concentration of HF increases. UV-VIS measurements of the leachate show strong UV absorption which is attributed to the presence of silica released from the corroded glass. Morphological and chemical composition changes were followed using scanning electron microscopy (SEM) combined with energy dispersive x-ray (EDX). The results indicate the formation of crust layers. The ionization of the glass during the passage of gamma-rays results in substantial changes to the chemical reactivity of the glass surface.The results showed an increase in the quantity of corrosion which indicates that irradiation might enhance the corrosion reaction mechanism and consequently the surface corrosion products. FTIR spectroscopy was performed for physico-chemical characterizations. In addition to the silanol band at ~3720 cm-1, IR features are attributed to free hydrogen-bonded and structurally bound molecular water and to silanol which is hydrogen-bonded to neighboring groups. The existence of these species and their behavior during etching are related to a specific mechanism for the reaction between silica glass and molecular water.
