| Abstract |
In the case of a heat treatment method for toughened glass panes for the purpose of eliminating those of them under threat of spontaneous breakage following the growth of included crystals, in particular by conversion of nickel sulphide inclusions froPWKHLUSKDVH KRWVRDNtest), the glass panes, after the toughening treatment, being maintained, for a defined time interval, at a temperature value that increases the rate of growth of the crystals, the temperature of the glass panes is brought, by conWURODFFRUGLQJWRWKHLQYHQWLRQLQWKH.-NiS LQFOXVLRQVIURPDQLQLWLDOWHPSHUDWXUHLQWKHUDQJHIRUIRUPDWLRQRI-phase nuclei, which lies below 250ยบ C and above room temperature (the nuclei formation range), the temperature change during controlled approach, of the nuclei formation range being at more than 2 degrees K/minute and a substantially slower change being imposed or a defined temperature being maintained for a defined temperature interval within the nuclei formation range. The method is appropriate in particular for being carried out immediately following the thermal toughening treatment of glass panes, by firstly lowering their temperature after the toughening and by maintaining this temperature within the aforementioned nuclei formation range. (FIG.nil ) |