Causes of glass self-explosion after tempering
The reason why the tempered glass self-explosion is that in the process of manufacturing the glass, some nickel-containing impurities are mixed in the melt of the raw material or the refractory material, and these impurities are used to form nickel sulfide crystals in the glass melting process. The nickel sulfide crystal has an α phase at a high temperature of over 380 ° C and a β phase at normal temperature. When the nickel sulfide crystal is changed from the α phase to the β phase, the volume of the crystal changes by 2-4%, and the diameter of the nickel sulfide crystal which causes the self-explosion of the tempered glass is about 0.2 mm on average. Soft Children Blanket,Kids Blanket,Cartoon Animal Blanket,Kids Cotton Blanket SUZHOU JINYULAI TEXTILE CO.,LTD , https://www.jyltextile.com
When the original sheet glass is molded, a slow annealing process is required, and the nickel sulfide crystal does not substantially affect the strength of the glass. But when the glass is tempered, the situation is very different. Since the tempered glass is a quenching process. Under the action of the cooling air, the glass cools very fast. When the glass is cooled to normal temperature and the structure is completely fixed, the α-phase nickel sulfide crystal is too late to be converted into the low-temperature β phase, but still exists in the high-temperature α phase.
If the nickel sulfide crystals appear in the tensile stress region of the tempered glass, self-explosion will occur as long as the crystal transformation occurs. Since the time of crystal transformation is variable, the self-explosion of tempered glass at normal temperature is completely uncertain. The method of detonating to reduce the self-explosion probability to solve the self-explosion of tempered glass is to homogenize the tempered glass: reheating the tempered glass to 280-300 ° C, and then holding it for 2-4 hours, so that the tempered glass with conditional self-explosion is in this Broken in the process. The homogenization of tempered glass is also referred to as the detonation treatment of tempered glass or the hot dip treatment of tempered glass.
According to statistics, after strict homogenization treatment, the self-explosion probability of tempered glass will be greatly reduced, and the probability of one piece of self-explosion per 10,000 square meters of glass in one year is only 1% or less. The tempered glass at this time can be called a real safety glass.