Crack Healing by Thermal Treatment in Float Glass: The Effect of Tin

Abstract

The evolution of radial cracks generated by Vickers indentation on “tin side” of float glass is analysed when heat treated at 620°C under various atmospheres and results are compared with a previous similar study performed on the “air side” of the same glass. Results evidence that the presence and the oxidation state of tin ions has a strong influence on crack morphological changes. If the oxidation state of tin remains quasi unchanged during the heat treatment, the mechanism responsible of the crack evolution is the spheroidization and there is no strong difference between the crack morphological changes observed on the “air” and “tin side” in this case. For oxidative atmospheres, contrary to what is observed on the “air side”, no crack spheroidization occurs. The cracks stay quasi unchanged for dry air or close for humid air. Increase of the viscosity at the top surface due to Sn oxidation is proposed to explain this spheroidization impediment. It is also shown that in these two cases, there is an efficient blunting and healing of the cracks, as four point bending tests indicate a significant sample strengthening with thermal treatment

Analysis of commercial glasses with different strengthening treatments: Emphasis on the tin side, defects, structure connectivity and cracking behavior

“…to Sn(IV) results after the ion-exchange treatment [19]. Tempered glass seems to have also higher amount of Sn(IV) that could be related with the high temperature of the thermal treatment [31] followed by the rapid cooling that stabilizes a greater amount of oxidized species. However, heat strengthening seems to have an even lower amount of Sn (IV) than annealed glass.…”

Kinetics of crack healing and self‐repair behaviors in a sealant glass for SOFC applications

“…The densification is assumed to be brought about by the cylinders getting shorter and thicker as the sintering time progresses. The change in the geometry that leads to densification is related to reduced time, as shown in Equation (14). The densification plot is extrapolated to obtain fictitious time, t 0 , at which the density of the glass compact is zero that is used to calculate (t − t 0 ) where t is the experimental sintering time.…”

“…The author concluded that depending on the atmosphere, the oxidation of tin changes, which results in different crack-healing morphologies. 14 Zaccaria et al 15 studied the thermal healing of realistic flaws in soda-lime-silica glass. The aim of this study was to understand the effect of strength recovery upon crack healing.…”

“…The study was further extended on the tin side of the float glass to understand the effect of atmosphere on crack healing. The author concluded that depending on the atmosphere, the oxidation of tin changes, which results in different crack‐healing morphologies 14 . Zaccaria et al 15 .…”

A model of crack healing of glass by viscous flow at elevated temperatures

“…The viscosities of glasses and silicate melts decreases with water content, which presents as OH and molecular H 2 O . As the humid atmosphere decreases the viscosity of glass near the crack surface, the crack healing is enhanced in a moist atmosphere . The kinetics of crack healing is studied using radial cracks generated by Vickers indentation, the morphology of which changes with time by heat treatment .…”