Tempered glass is also known as tempered glass. It uses physical or chemical methods to form a compressive stress layer on the glass surface. The glass itself has high compressive strength and will not cause damage. When the glass is subjected to an external force, the pressure layer can offset part of the tensile stress to avoid cracking of the glass. Although the interior of the tempered glass is in a state of large tensile stress, the interior of the glass is free from defects and will not be destroyed. In order to achieve the purpose of improving the strength of the glass.
Tempered glass is a secondary processing product of flat glass. The processing of tempered glass can be divided into physical tempering and chemical tempering.
Physical tempered glass is also known as hardened tempered glass. When the ordinary plate glass is heated in a heating furnace near the softening temperature (600°C) of the glass, the internal stress is eliminated by its own deformation, then the glass is removed from the heating furnace, and then the high pressure cold air is blown to the glass by a multi-nozzle. On both sides, it is quickly and uniformly cooled to room temperature to obtain a tempered glass. This kind of glass is in the stress state of internal tension and external pressure. Once local damage occurs, stress will be released and the glass will be broken into numerous small pieces. These small pieces have no sharp corners and are not easy to hurt.
Chemically toughened glass increases the strength of the glass by changing the chemical composition of the surface of the glass. Generally, the tempered glass is tempered using an ion exchange method. The method comprises immersing a silicate glass containing alkali metal ions into molten lithium (Li+) salt to exchange Na+ or K+ ions of the glass surface layer with Li+ ions, forming a Li+ ion exchange layer on the surface, because of Li+ The coefficient of expansion is less than that of Na+ and K+ ions, which results in less shrinkage of the outer layer and greater shrinkage of the inner layer in the cooling process. When cooled to room temperature, the glass is also in the state of inner layer tension and outer layer compression. Similar to physical tempered glass.
Tempered glass has high strength, its compressive strength can reach 125MPa or more, 4 to 5 times larger than ordinary glass, and its impact strength is also very high. When measured by the steel ball method, 0.8kg of steel ball falls from a height of 1.2m, glass can be Stay intact.
The elasticity of tempered glass is much larger than that of ordinary glass. A tempered glass of 1200mm×350mm×6mm can be flexed to a deflection of 100mm after being subjected to force. When the external force is removed, it can still be restored to its original shape, while ordinary glass bending deformation can only occur. A few millimeters.
The thermal stability is good. When it is quenched and hot, it is not easy to cause explosion is another characteristic of tempered glass. This is because the compressive stress of tempered glass can offset a part of tensile stress due to quenching and rapid heating. Tempered glass heat shock resistance, the maximum safe operating temperature is 288 °C, can withstand the temperature change of 204 °C.
Because tempered glass has good mechanical properties and thermal stability, it has been widely used in construction, transportation and other fields. Flat tempered glass is often used as doors, windows, walls, curtain walls, windows, and furniture in buildings. Curved glass is commonly used in automobiles, trains, and airplanes.
When using, it should be noted that the tempered glass can not be cut, ground, and the corners can not be impacted and squeezed. It is necessary to select or submit specific design drawings according to the ready-made size specifications for processing and customizing. The glass used in large-area glass curtain walls is to be controlled in tempering. The semi-tempered glass is selected so that the stress cannot be too large to avoid spontaneous vibration caused by the wind load.
According to different glass originals used, ordinary tempered glass, heat-absorbing tempered glass, colored glass, tempered insulating glass, etc. can be made.