In glasses that contain mobile alkali ions, an ion exchange between protons or hydronium ions in the surrounding aqueous liquid and alkali ions in the glass causes a surface stress to develop in the glass. These surface stresses are responsible for subcritical crack growth thresholds and for low level crack growth plateaus in commercial glasses, depending on the sign of the surface stress. In this paper we discuss a technique of measuring the surface stresses in a soda-lime-silicate glass and compare the measured exchange layer thickness with that determined from measurements of bending strain. The direct measurements show from 2 to 5 times as much penetration as that obtained from the bending strain measurement. Reasons for the difference in estimated and measured penetration distance are discussed.
Citation: Journal of Materials Science
Pub Type: Journals
glass, hydration, ion exchange, residual sresses, static fatigue, surface stress