Which is the Right Reference Surface Compression Value for Heat Treated Glass?

Abstract

The paper correlates the data recorded in Stazione Sperimentale del Vetro, in many years. The aim is to define a correlation between the following parameters in heat treated glass: 1) bending strength tested according EN 1288-3 ; 2) fragmentation tested according relevant Standards [EN 1863-1 2004, EN12150-1 2015, EN 14179-1 2016]; 3) surface compression stress measured with laser Gasp [ASTM C1279 2013]. For heat strengthened glass the fragmentation correlation due to the different crack path ("island" fragments instead of small fragments) is only related to conformity: Y/N. The research is the development of the previous ones [Schiavonato et al. 2005, Mognato et al. 2011] carried out at Stazione Sperimentale Vetro, increasing the experimental data (up to 2017)considering in detail the emissivity of coated glass and extending also to enamelled glass. The correlation between surface compression stress and mechanical strength and fragmentation is relevant for the manufacturer, who may use surface pre-stress measurement as a means of product control.