The existence of nickel sulfide stone in glass is the main reason for the self-detonation of toughened laminated glass. This view is the main explanation for the white burst of toughened glass in the world at present, and it can be verified by observation, theoretical analysis and experiment. In some standards mentioned in the "self-explosion of toughened glass" actually refers to the existence of tiny nickel sulfide stones inside the glass, resulting in the phenomenon of the spontaneous breakage of toughened glass. Through some statistical investigation, most of the toughened glass self-explosion phenomenon is caused by this reason.
It should be noted that some studies suggest that not all NiS stones will cause self-detonation of toughened glass. The critical diameter of self-detonation stones is generally between 0.04 and 0.65 ram, and the critical diameter depends on the glass stress around the stones. The relationship between the surface stress value of glass and the number of debris particles in the range of 50ram×50ram. It can be seen that the larger the stress, the smaller the critical diameter, the more NiS particles that can cause self-detonation, and correspondingly the higher the self-detonation rate. When the heating temperature and cooling intensity of each part of the same glass surface are inconsistent, plane stress will be produced. This stress superimposed on the thickness stress makes the actual core tensile stress rise in some areas, causing the critical diameter value to fall, resulting in the increase of self-detonation rate.
There are some other reasons for the breakage of tempered laminated glass. For example, special attention should be paid to the cooling uniformity of the glass in contact with the mold when tempered, so as to reduce the surface tensile stress formed by the blocking cooling of the part as far as possible. The existence of this stress will also lead to the breakage of the glass in the future. Some other glass defects such as sand, bubbles and other inclusions in glass and human-caused gap, scratch, edge bursting defects may also cause the tempered glass to crack in storage, installation and use.