1, the toughness is improved by sandwiching polycarbonate and other resins between two layers of glass and sticking them. This is also the principle of bulletproof glass. Bulletproof window glass is a sandwich structure with a layer of glass (1), and an elastomer layer (2), a polycarbonate layer (3) and a polymethylmethacrylate layer (4) with high elastic modulus are stuck on the back of the glass. The elastic layer is preferably a silicone polymer with a thickness of about 5mm, which is cast in place, with a gasket and a peripheral sheet of appropriate thickness. The elastic layer contains electronic components. Uses and advantages: This bullet-proof glass has a high strength-to-weight ratio and can be used as a protective device for bank exchange windows. When used as double glazing, this bulletproof glass can be installed back to back. The elastic layer plays a role in dispersing the energy from the lens and adjusting the different thermal expansion between the glass (1) and the polycarbonate layer (3). The polymethylmethacrylate layer (4) provides a reproducible scratch-resistant optically excellent surface, thus avoiding the difficulty of grinding and polishing the outer surface of the polycarbonate layer (3).
At present, polyvinyl butyral PVB with excellent performance is usually used as the material of laminated glass and interlayer of automobiles. Laminated glass has high strength, toughness, collision resistance, safety and transparency. Once broken, the fragments of inner and outer glass can still adhere to the PVB film.
2. Insulating glass, with a dry air layer sandwiched between the double layers of glass, or vacuumizing and adding inert gas (nitrogen), with a thickness of about 8 mm, has the characteristics of wind resistance and external impact resistance. Because the moisture permeability of insulating glass is very low, it will not frost when used in the environment with large temperature difference between inside and outside.
3. Tempered glass can resist high temperature up to 300℃. The toughness of tempered glass can make it fall like a small grain of rice when it is crushed by a hard object, without hurting pedestrians. Manufacturing process: the glass is heated to a temperature close to softening (600-650 degrees), and then quenched in high-speed air, so that the surface is cooled first and then deformed. When internal cooling produces deformation, the toughness of glass can be improved by more than 5 times by applying pre-pressure to the surface.
4. Use plexiglass, that is, polymethylmethacrylate, or polycarbonate with the highest transparency, and the light transmittance is no less than that of glass. In addition, do not use ordinary plexiglass, but use biaxially oriented plexiglass.
5. The material remains unchanged, but the structure of the glass has been improved: the impact resistance of optical glass depends on the quality of its surface and edge.
6. Adding metal indium or reinforced glass fiber: indium is a rare metal mixed in zinc and silver deposits. In the process of making liquid crystal display and high-grade glass, adding indium can make the products conductive, reduce the radiation of the display and improve the toughness of the glass. If the light transmittance is not very high, you can also add crisscross glass fibers, and the toughness will be greatly improved.
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Glass is an amorphous inorganic material with quartz sand, soda ash, feldspar and limestone as main raw materials, which is melted, molded and solidified by cooling. It has transparency that ordinary materials can't achieve, and has excellent mechanical and thermal properties.
I. Flat glass
Flat glass refers to flat glass products without other processing, also known as white glass or clean glass. According to different production methods, it can be divided into ordinary flat glass and float glass.
Flat glass can be divided into window glass and decorative glass according to its use.
Flat glass has two uses: 3 ~ 5 mm flat glass is generally used for direct lighting of doors and windows, and 8 ~ 12 mm flat glass can be used for partition. Another important use is as the original sheet for tempering, laminating, coating and insulating glass.
Second, safety glass.
Safety glass refers to glass with high mechanical strength and strong impact resistance compared with ordinary glass. Its main varieties are tempered glass, laminated glass, laminated glass and titanium glass. When the safety glass is broken, its fragments will not hurt people, and it also has the functions of theft prevention and fire prevention. According to the original glass used in production, safety glass has a certain decorative effect.
(1) tempered glass
Tempered glass is also called tempered glass. It uses physical or chemical methods to form a laminated stress layer on the glass surface, and the glass itself has high compressive strength and will not cause damage. When the glass is subjected to external force, this pressure layer can offset part of the tensile stress and prevent the glass from breaking. Although the inside of tempered glass is in a state of great tensile stress, there is no defect in the glass and it will not be damaged, thus achieving the purpose of improving the strength of glass.
Tempered glass is a secondary product of flat glass, and the processing of tempered glass can be divided into physical tempering and chemical tempering.
Physical tempered glass is also called quenched tempered glass. When the ordinary flat glass is heated to the softening temperature (600℃) of the glass in the heating furnace, the internal stress is eliminated by its own deformation, and then the glass is moved out of the heating furnace, and then high-pressure cold air is blown to both sides of the glass with multi-head nozzles, so that it can be quickly and uniformly cooled to room temperature, and tempered glass can be made. This kind of glass is in a stress state of internal tension and external pressure. Once damaged locally, the stress will be released and the glass will be broken into countless small pieces. These small pieces have no sharp edges and corners, so they are not easy to hurt people.
Chemical tempered glass is to improve the strength of glass by changing the chemical composition of the glass surface, and is generally tempered by ion exchange method. In this method, silicate glass containing alkali metal ions is immersed in molten lithium (Li+) salt, so that Na+ or K+ ions on the glass surface are exchanged with Li+ ions, and a Li+ ion exchange layer is formed on the surface. Because the expansion coefficient of Li+ is smaller than that of Na+ and K+ ions, the outer layer shrinks less while the inner layer shrinks more during cooling. When the glass is cooled to normal temperature, it will also be stretched in the inner layer.
Tempered glass has high strength, and its compressive strength can reach more than 125MPa, which is 4 ~ 5 times larger than that of ordinary glass. The impact strength is also high. When measured by steel ball method, 0.8kg steel ball falls from the height of 1.2m, and the glass can be kept intact.
Toughened glass is much more elastic than ordinary glass. A piece of tempered glass with 1 200 mm× 350 mm× 6 mm can have a bending deflection of 100mm after being stressed. When the external force is removed, it can still be restored to its original state, while the bending deformation of ordinary glass can only be a few millimeters.
Thermal stability is good, and it is not easy to crack when it is quenched and heated, which is another feature of tempered glass. This is because the compressive stress of tempered glass can offset part of the tensile stress caused by rapid cooling and rapid heating. Tempered glass is resistant to thermal shock, the maximum safe working temperature is 288℃, and it can withstand the temperature difference change of 204℃.
Tempered glass is widely used in construction engineering, transportation and other fields because of its good mechanical properties and thermal stability. Flat tempered glass is often used as doors and windows, partitions, curtain walls, windows and furniture of buildings, while curved glass is often used in cars, trains and airplanes.
It should be noted that tempered glass cannot be cut and polished, and the corners cannot be bumped and squeezed. Need to choose according to the ready-made size specifications or put forward specific design drawings for processing and customization. The glass used in large-area glass curtain wall should be controlled when tempered, and semi-tempered glass should be selected, that is, its stress should not be too large to avoid self-explosion due to vibration caused by wind load.
According to the different original glass plates used, it can be made into ordinary tempered glass, endothermic tempered glass, colorful tempered glass, tempered hollow glass and so on.
(2), drawing glass
Laminated glass is also called shatterproof glass or steel wire glass. It is produced by calendering method, that is, in the molten state of glass, the preheated steel wire or steel wire mesh is pressed into the middle of glass and annealed and cut. The surface of wire-lined glass can be embossed or polished, and the color can be made colorless, transparent or colored.
Laminated glass is characterized by good safety and fire resistance. Due to the skeleton function of steel wire mesh, not only the strength of glass is improved, but also the fragments will not fly away when damaged by impact or sudden temperature change, thus avoiding the damage of fragments to people. In case of fire, when the flame is prolonged and the laminated glass is cracked by heat, the glass can still be fixed and isolated from the flame due to the role of wire mesh, so it is also called fire-proof glass.
According to the national industry standard JC433-9 1, the thickness of glass lining is divided into 6, 7 and 10mm, and the specifications are generally not less than 600mm×400mm and not more than 2000 mm× 1200 mm. ..
At present, the laminated glass produced in China is divided into laminated embossed glass and laminated polished glass. Laminated glass can be used in doors and windows, skylights, lighting roofs, balconies and other building parts.
(3) laminated glass
Laminated glass is a flat or curved composite glass product made of PVB resin film sandwiched between two or more original glass plates and heated and pressurized. The original sheet of laminated glass can be ordinary flat glass, float glass, tempered glass, colored glass, heat absorbing glass or heat reflecting glass.
There are 2, 3, 5 and 7 layers of laminated glass, with a maximum of 9 layers. For two layers of laminated glass, the original thickness is (mm): 2+3, 3+3, 3+5, etc. The structure of laminated glass is shown in Figure 8- 1.
Laminated glass has good transparency and impact resistance several times higher than ordinary flat glass. Multiple layers of ordinary glass or tempered glass can be compounded to make bulletproof glass. Because of the adhesion of PVB film, even if the glass is broken, the fragments will not fly out and hurt people. By using different original glasses, laminated glass can also have durability, heat resistance and moisture resistance.
With high safety, laminated glass is generally used as doors and windows, skylights, windows and partitions of shops, banks and jewelry in high-rise buildings.
(4) Titanium glass
Titanate glass is also called armored foil glass that never breaks. It is a new type of glass, which closely combines titanium-gold foil film on any glass substrate. Titanate glass has the functions of high compression resistance, high heat resistance and ultraviolet protection. Different base glasses and different titanium foils can be combined into titanium glasses with different colors, properties and specifications. The common colors of titanium glass are: colorless and transparent, dark brown, dark brown reflection, copper reflection and so on.
Third, energy-saving glass.
Traditional glass is mainly used for architectural lighting. With the increase of the size of building doors and windows, people's requirements for the thermal insulation performance of doors and windows are also improved accordingly. Energy-saving decorative glass is a kind of glass that can meet this requirement and integrate energy-saving and decorative functions. Energy-saving decorative glass usually has a pleasant appearance color, but also has the special ability to absorb, transmit and reflect light and heat. The use of glass curtain wall of building external wall windows can play a significant energy-saving effect and has been widely used in various advanced buildings. Energy-saving decorative glass commonly used in buildings includes heat-absorbing glass, heat-reflecting glass and insulating glass.
(1) heat-absorbing glass
Heat absorbing glass is a kind of flat glass, which can absorb a lot of infrared radiation energy and maintain a high visible light transmittance. There are two methods to produce heat-absorbing glass: one is to add a certain amount of colorant with heat-absorbing performance to the raw materials of ordinary soda-lime silicate glass; The other is to spray one or more metal or metal oxide films on the surface of flat glass.
The heat-absorbing glasses are gray, brown, blue, green, bronze, bronze, pink and golden yellow. At present, China mainly produces the first three colors of heat-absorbing glass. There are four kinds of thickness: 2, 3, 5 and 6mm. The heat-absorbing glass can also be further processed into polished, toughened, laminated or insulating glass.
Compared with ordinary flat glass, heat absorbing glass has the following characteristics:
1. absorbs solar radiation heat. For example, the total heat transfer rate of 6mm thick transparent float glass in sunlight is 84%, while the total heat transfer rate of heat absorbing glass under the same conditions is 60%. Different colors and thicknesses of heat-absorbing glass have different degrees of absorption of solar radiation heat.
4. Absorb the visible light of the sun, weaken the intensity of sunlight, and play the role of anti-glare.
3. It has certain transparency and can absorb certain ultraviolet rays.
Because of these characteristics, heat-absorbing glass has been widely used in doors and windows, exterior walls of buildings and windshields of cars and ships, and has the functions of heat insulation, glare prevention, lighting and decoration.
(2) Heat reflective glass
Heat reflective glass is a kind of flat glass with strong heat reflective ability and good light transmittance. It is formed by plating gold, silver, copper, aluminum, chromium, nickel, iron and other metals or metal oxide films on the glass surface by pyrolysis, vacuum evaporation, cathode sputtering and other methods, or replacing the original ions on the glass surface with metal ions by electro-flotation plasma exchange method. Heat reflective glass, also known as mirror glass, has many colors such as gold, brown, gray, purple, brown, bronze, light blue and so on.
Heat-reflective glass has a high thermal reflectivity, for example, the total reflection heat of 6mm thick float glass is only 16%, while under the same conditions, the total reflection heat of heat-absorbing glass is 40%, and the total reflection heat of heat-reflective glass can be as high as 6 1%, so it is often used to make hollow glass or laminated glass to improve its thermal insulation performance. Thermal reflective glass coated with metal film also has the function of one-way image transmission, that is, you can see the outdoor scenery indoors during the day, but you can't see the indoor scene outdoors.