Tempered glass has higher strength, better heat resistance, and compression resistance than ordinary glass. It is a type of safety glass widely used in our daily lives, such as glass guardrails, sightseeing elevator passages, glass coffee tables, car windshields, televisions, mobile phones, pot covers, etc., all of which are made of tempered glass. Someone may ask, since it has the characteristics of pressure resistance and heat resistance, why is it still prone to self explosion? How to distinguish whether tempered glass is self destructing?

1、 The reason for the self explosion of tempered glass

The impact of glass quality defects: Firstly, there are stones, impurities, and bubbles in the glass. Impurities in the glass are the weak points and stress concentration areas of tempered glass. Especially if the stone is located in the tensile stress zone of tempered glass, it is an important factor leading to cracking; Secondly, glass contains nickel sulfide crystals, and nickel sulfide inclusions generally exist as small crystalline spheres with a diameter of 0.1-2mm. They have a metallic appearance, and these impurities are Ni3S2, Ni7S6, and Ni XS, with X=0-0 in between. 07. As long as Ni1-XS phase is the main cause of spontaneous breakage of tempered glass; Thirdly, due to improper processing or operation, the surface of the glass may have defects such as scratches, burrs, and deep edges, which can easily lead to stress concentration or self explosion of tempered glass.

Uneven and offset stress distribution in tempered glass: Firstly, the temperature gradient that occurs along the thickness direction of the glass during heating or cooling is uneven and asymmetric. Tempered products tend to self destruct, and some may experience "wind explosion" during rapid cooling. If the tensile stress zone deviates to one side of the product or to the surface, the tempered glass will self destruct; Secondly, the degree of tempering has an impact. Experiments have shown that when the degree of tempering is increased to level 1/cm, the self explosion rate reaches 20% -25%. It can be seen that the higher the stress, the higher the degree of tempering, and the greater the self explosion capacity.

2、 Distinguishing whether tempered glass is self destructing

The causes of tempered glass cracking can be divided into two types: self explosion and external force factors. The causes of self explosion of tempered glass can be divided into two types: one is self explosion caused by visible defects in the glass, such as stones, sand particles, bubbles, inclusions, gaps, scratches, and edge bursts; The second is the self explosion of tempered glass caused by nickel sulfide impurities and heterogeneous particles in the glass.

Let me teach you a small method to correctly identify the self explosion of tempered glass:

Firstly, find a "butterfly" to determine the cause of the explosion. Carefully observe whether the broken glass has a "butterfly" shape. Looking towards the center of the crack in the glass, there will be traces resembling a butterfly shape. If such a "butterfly" is seen on the glass, it proves that the glass is self destructed.

The second trick is to find the butterfly egg, scientific name is nickel sulfide. If you find small black spots on the butterfly's chest and abdomen, you can 100% confirm that it has self destructed. Butterfly eggs are composed of nickel mixed into quartz sand, the main glass material, and sulfur brought in by fuel, which are burned and melted at high temperatures. We can imagine it as a lit candle, the black debris pointed to by the oval shaped butterfly arrow; Although the principles are different, they are similar. When this piece of glass is sent to another device for tempering treatment, heated to a temperature of around 620 ℃, and then rapidly blown and cooled, it can have a high external compressive strength.

Other reasons for self explosion: According to experts, the self explosion of tempered glass is related to the original glass sheet (i.e. untempered glass), the pre-treatment process of deep processing enterprises (cutting, edge grinding process, etc.), and the parameter settings of the tempering furnace, and is not closely related to the thickness of the glass. Even glass without butterfly eggs may self explode.

Article source: Tempered glass coverwww.yinghuade.com