Evaluation of Artificial Ageing Methods for Glass

Surface damage that accumulates on the surface of glass is known to govern the strength of this material. It would therefore be very useful to use artificial ageing techniques to replicate this level of damage; this would allow a rapid and cost effective assessment of the expected glass strength and the long term performance of novel glass products and treatments. Some artificial ageing methods exist but it is unclear whether the surface damage induced is correlated with the physical damage found in naturally aged glass. The aim of this paper is therefore, to evaluate available artificial ageing methods of glass using as a reference naturally aged annealed glass. The artificial ageing methods of the as-received specimens involved the induction of: (a) a single flaw on the as-received specimens with a custom-made scratching device (SC series); and (b) uniform damage to the specimens with the use of dropped grit (SA series). Each ageing method was then evaluated with destructive and non-destructive testing. These results were then compared to those obtained from the naturally aged glass (NA series). A 65% reduction in mean strength with the respect to the as-received annealed glass was noted for the naturally aged series. This reduction was approximated (62-79%) by the artificial aged series. However, a perfect match has yet to be found especially when other fractile values of strength as well as surface roughness data are also taken into account. Nevertheless, in general the SA series were found to perform better than the SC series.