Investigation of Glass Aqueous Corrosion Using Surface Characterization Tools

Abstract

The aqueous corrosion of glass is of considerable interest given its critical role in industrial applications, biomedical processes, and carbon dioxide sequestration in earth’s crust. Particularly, a thorough understanding of corrosion of nuclear waste form glass is a prioritized task for its use in the application of nuclear waste storage under current energy demands. The modifier ions in the glass network exchange with hydrogen species upon contact with aqueous solution, and this ion-exchange process leads to the dissolution of Si from the glass network. In order to quantify the kinetics of glass dissolution, phenomenological observations of corroded glass has led to the discovery of a hydration coupled ion-exchange mechanism of glass corrosion. However, those observations were mostly based on the corrosion of pulverized glasses or bulk glasses of interest and lacked the use of surface characterization tools in investigating the glass corrosion behavior. In this study, attention was focused on how surface characterization techniques can contribute to the understanding of glass corrosion. Firstly, a series of glass surface finishing techniques was evaluated both compositionally and morphologically using Xray photoelectron spectroscopy and atomic force microscopy. Also, advanced fractal algorithms were used when analyzing the AFM images in search of an atomically smooth glass surface with surface composition close to the bulk composition. For the very first time, an aluminoborosilicate glass melt surface prepared by heat treatment was used to develop a novel method of measuring glass dissolution rates and monitoring surface roughening behavior via AFM. The obtained glass dissolution rate (via AFM) is similar to the reported dissolution rates of other glasses with similar composition. Additionally, it was found that the corrosion of glass can lead to the roughening of glass surfaces. A similar relationship was observed using synchrotron radiated X-ray reflectivity and diffuse scattering. The XRR and XDS study of two different flat panel silicate glasses highlights a new series of evidence favoring the interfacial dissolution and reprecipitation mechanism of glass dissolution. The XRR/XDS evidence in favor of this mechanism is also supported by XPS data and associated calculations.