Tempered glass/Reinforced glass is a safety glass. Tempered glass is actually a kind of prestressed glass. In order to increase 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, the surface stress is first offset, thereby improving the bearing capacity and enhancing the resistance of the glass itself. Wind pressure, cold and heat, impact and so on. Tempered glass is obtained by first cutting the ordinary annealed glass into the required size and then heating it to about 700 degrees near the softening point, and then performing rapid and uniform cooling (usually 5-6MM glass is heated at 700 °C for 240 seconds). Cool down for about 150 seconds. 8-10MM glass is heated at 700 °C for about 500 seconds, and the temperature is lowered by about 300 seconds. In short, depending on the thickness of the glass, the time for heating and cooling is different. After the tempering treatment, the surface of the glass forms a uniform compressive stress, while the inside forms a tensile stress, which improves the bending and impact strength of the glass, and its strength is about four times that of the ordinary annealed glass. The tempered glass that has been tempered can no longer be processed or damaged by any cutting, grinding, etc., otherwise it will “break the bones” due to the damage of uniform compressive stress.
By shape
1. Tempered glass is divided into flat tempered glass and curved tempered glass according to its shape.
Generally, the thickness of flat tempered glass is 11, 12, 15, 19mm, etc.; the thickness of curved tempered glass is 11, 15 and 19mm, etc. The thickness after processing depends on the equipment and technology of each manufacturer. However, curved (ie, bent steel) tempered glass has a large arc limit for each thickness. That is, R R is usually referred to as a radius.
2. Tempered glass is divided into flat steel and curved steel according to its appearance.
3. Tempered glass is divided into: excellent products and qualified products according to its flatness. The tempered glass of superior grade is used for automobile windshield; the qualified product is used for architectural decoration.
By process
1. Physical tempered glass is also called quenched tempered glass. When the ordinary flat glass is heated in a heating furnace to a softening temperature (600 ° C) close to the glass, the internal stress is removed by its own deformation, and then the glass is removed from the heating furnace, and the high-pressure cold air is blown to the glass by a multi-head nozzle. The tempered glass can be obtained by rapidly and uniformly cooling the two sides to room temperature. This kind of glass is under internal tension and externally stressed. Once local damage occurs, stress is released and the glass is broken into numerous small pieces. These small pieces have no sharp edges and are not easy to injure people.
2. Chemically tempered glass increases the strength of the glass by changing the chemical composition of the surface of the glass, and is generally tempered by ion exchange. The method comprises the steps of: immersing a silicate glass containing an alkali metal ion in a molten lithium (Li+) salt, exchanging Na+ or K+ ions of the glass surface layer with Li+ ions, and forming a Li+ ion exchange layer on the surface, due to Li+ The expansion coefficient is smaller than Na+ and K+ ions, so that the outer layer shrinks less and the inner layer shrinks more during the cooling process. When cooled to normal temperature, the glass is also in the inner layer and the outer layer is under pressure. Similar to physical tempered glass.
Tempering degree
1. Tempered glass: tempering degree = 2~4N/cm, glass surface tempered glass surface stress α≥95Mpa;
2. Semi-tempered glass: tempering degree = 2N/cm, glass curtain wall semi-tempered glass surface stress 24Mpa ≤ α ≤ 69Mpa;
3. Super tempered glass: tempering degree > 4N/cm.