Tempered glass is actually a kind of prestressed glass. In order to improve the strength of the glass, chemical or physical methods are usually used to form compressive stress on the surface of the glass. When the glass is subjected to external force, it first offsets the surface stress, thereby improving the bearing capacity and improving the resistance of the glass. tensile strength.
Tempered glass/Reinforced glass is safety glass. Tempered glass is actually a kind of prestressed glass. In order to improve the strength of the glass, chemical or physical methods are usually used to form compressive stress on the surface of the glass. When the glass is subjected to external force, it first offsets the surface stress, thereby improving the bearing capacity and enhancing the resistance of the glass itself. Wind pressure, cold and heat, impact, etc. Pay attention to distinguish it from glass fiber reinforced plastic.
advantage
The first is that the strength is several times higher than that of ordinary glass, and it is resistant to bending.
Second, it is safe to use. The increased bearing capacity improves the fragile nature. Even if the tempered glass is damaged, it will be small fragments without acute angles, which greatly reduces the damage to the human body. Compared with ordinary glass, the resistance to rapid cooling and rapid heating of tempered glass is improved by 3 to 5 times. It is a type of safety glass. To ensure the safety of qualified materials for high-rise buildings.
shortcoming
1. The tempered glass can no longer be cut and processed. The glass can only be processed to the required shape before tempering, and then tempered.
2. Although the strength of tempered glass is stronger than that of ordinary glass, tempered glass has the possibility of self-explosion (self-breaking), while ordinary glass does not have the possibility of self-explosion.
3. The surface of the tempered glass will be uneven (wind spots), with a slight thickness thinning. The reason for the thinning is that after the glass is softened by hot melt, it is rapidly cooled by strong wind, so that the crystal gap inside the glass becomes smaller and the pressure becomes larger, so the glass is thinner after tempering than before tempering. Under normal circumstances, 4~6mm glass will be thinned by 0.2~0.8mm after tempering, and 8~20mm glass will be thinned by 0.9~1.8mm after tempering. The specific degree depends on the equipment, which is why tempered glass cannot be used as a mirror.
1. Physical tempering method
The principle of the physical tempering method is to heat the glass to a suitable temperature and then cool it quickly, so that the surface of the glass shrinks sharply, resulting in compressive stress, while the middle layer of the glass cools slowly, and it is too late to shrink, so the tensile stress is formed, so that the glass obtains higher strength. Generally speaking, the higher the cooling strength, the greater the glass strength.
2. Chemical toughening method
The chemical tempering method refers to a tempering method in which the surface composition of the glass is changed by chemical methods, and the surface lamination stress is increased to increase the mechanical strength and thermal stability of the glass. Because it strengthens the glass by ion exchange, it is also called ion exchange enhancement method. According to the type of exchanged ions and the temperature of ion exchange, it can be divided into ion exchange methods below the transition point and ion exchange methods above the transition temperature.
The principle of the chemical enhancement method is to change the surface composition of the glass according to the mechanism of ion diffusion, and immerse the glass into a high-temperature molten salt at a certain temperature, and the alkali metal ions in the glass and the alkali metal ions in the molten salt are separated by diffusion Mutual exchange occurs, resulting in a "clogging" phenomenon, which causes compressive stress on the surface of the glass, thereby increasing the strength of the glass.
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