STATISTICAL ANALYSIS OF A SODA LIME GLASS THERMAL SHOCK RESISTANCE

Comparatively to the as received soda lime glass samples, the strength distribution after thermal shocks showed the appearance of a second branch in the Weibull curves. This branch is observed for temperature differences (Delta T) equal or higher than the critical temperature difference (Delta Tc) for both water and motor oil cooling baths. The dispersion is more spread out in these two baths in comparison with the olive oil bath probably because of more pronounced slow crack growth effect. The Weibull modulus varies according to the used cooling bath and the considered temperature difference. In the case of thermal shock caused by air blast cooling at T = 20 degrees C, a bimodal distribution is observed for only the critical state. The initial cracking time, obtained by acoustic emission, corresponds to the unstable propagation of the most critical defect. The number of cracks induced by thermal shock is proportional to the number of acoustic events.