The impact of quality defects on tempered glass

A. There are stones, impurities, and bubbles in the glass: Impurities in the glass are the weak points of tempered glass and also the places where stress is concentrated. Especially if the stone is located in the tensile stress zone of tempered glass, it is an important factor leading to explosion.
Stones exist in glass and have a different coefficient of expansion from the vitreous body. The stress concentration in the crack area around the stone increases exponentially after glass tempering. When the coefficient of expansion of the stone is smaller than that of glass, the tangential stress around the stone is in a tensile state. The crack propagation that accompanies stones is highly likely to occur.
B. Glass contains nickel sulfide crystals
Nickel sulfide inclusions generally exist as crystalline small spheres with a diameter of 0.1-2 mm. The appearance is metallic, and these impurities are Ni3S2, Ni7S6, and Ni-XS, with X=0-0. 07. Only Ni1-XS phase is the main cause of spontaneous fragmentation of tempered glass.
The theoretical NIS is known to be at 379. There is a phase transition process at C, starting from the high-temperature state α- Transition of NiS hexagonal crystal system to low-temperature state β- During the process of NiS cubic crystal system, a volume expansion of 2.38% occurs. This structure is preserved at room temperature. If the glass is heated in the future, it may quickly appear α-β State transition. If these debris are inside the tempered glass under tensile stress, volume expansion will cause spontaneous cracking. If there is a-NIS at room temperature, it will gradually transition to β During this phase transition, a slow increase in volume may not necessarily cause internal rupture.
C. Defects such as scratches, blowouts, and deep edges on the surface of glass caused by improper processing or operation can easily lead to stress concentration or self explosion of tempered glass.