Classification of glass products. Classification of glasses according to technical purpose According to the chemical composition, glass is classified
Glass has been known to people for about 55 centuries. The most ancient samples were found in Egypt. In India, Korea, Japan, glass items have been found dating back to 2000 BC. Excavations show that in Russia they knew the secrets of glass production more than a thousand years ago. And the first mention of a Russian glass factory (it was built near Moscow near the village of Dukhanino) dates back to 1634. Despite such an ancient history, the mass production of glass acquired only at the end of the last century thanks to the invention of the Siemens-Martin furnace and the factory production of soda. And sheet glass is a completely modern thing. The technology of its manufacture was developed in our century.
Endurance test.
The mechanical strength of glass is characterized by hardness. It also determines its resistance to deformation, which will certainly occur if you try to "embed" a more solid body (stone, for example) into the glass. The practical method for determining microhardness is curious. A diamond pyramid is pressed into the glass surface with an indentation load of 50 to 100 grams.
The brittleness of glass is its ability to resist impact. When testing for brittleness, a reference steel ball is dropped on a glass sample or beaten with a pendulum. In both cases, the strength is determined by the work expended on the destruction of the samples.
We cut...
Glass cutting is carried out with a diamond or carbide glass cutter. Diamond - one in the frame of which a diamond grain is inserted in such a way that it has two angles - obtuse and sharp. The sharp one should move forward when cutting, then the diamond slides freely on the glass, not lingering on the irregularities on the glass. If you lead the diamond with an obtuse angle forward, the grain will quickly fall out or move to the side from its place. So that when cutting glass you do not have to constantly use a protractor, measuring the angle of inclination of the diamond, a special mark is made on the frame of the glass cutter, which should always be facing the ruler when cutting.
But no matter how hard a diamond is, it dulls over time. Then you have to turn to a jeweler (or watchmaker) for help to turn the grain to another facet.
A carbide glass cutter is usually a three-roller cutter. The rollers are the cutting part. Each of them is designed for cutting 350 running meters of glass. After severe blunting, the roller is sharpened on a special bar with diamond dust or an electric grinder.
Various glass shapes can be cut with a homemade "glass-cutting pencil" made from charcoal. Coal is ground in a mortar into a fine powder and kneaded in gum arabic (a viscous transparent liquid secreted by some types of acacia; it dissolves in water, forming a sticky solution). The resulting thick dough is rolled into large sticks and dried well.
Immediately before cutting, the edge of the glass is filed with a triangular file. Then a pencil is lit from one end and touches the sawn edge of the glass with it. The hot tip of the pencil is led in the right direction. Glass cracks break easily.
Drilling...
Glasses, like people, age - their fragility increases with time. Therefore, when working with old glasses, they must first be washed, dried, wiped with a cloth slightly moistened with turpentine, and dried again, protecting from dust.
Holes in glass are best made with a hand drill, as when working with a power tool, the glass at the drilling site is very hot.
Drills are used mainly diamond. The drilling center is marked with a "cross" using a glass cutter. The role of lubricant is performed by technical turpentine, in which rosin is diluted. The first drop of this solution is applied to the "cross", and then gradually added already during drilling, so that the recess is always filled with grease.
After drilling through 0.7-0.8 of the thickness, when the point almost reaches the other side, the glass is turned over. With a light blow of the tip of the drill, they introduce it into the drilled cone and continue to work "to the bitter end" from the other side. This "trick" allows you to avoid cracks, getting uneven edges of the hole, and also reduce its taper. There are other ways to drill glass.
We make stained glass.
The traditional technology of making stained-glass windows is complex, expensive, and only experienced master artists can do it. But if your "hands grow from where you need it," then decorating the door with a home-made stained-glass window made of broken glass on silicate glue will be quite possible. First, a drawing of the future "work" is developed (performed on a sheet of paper in full size and in color). Then stick it on the reverse side of the glass on which the stained glass will be made, "face" down.
After that, with a thin brush with quick-drying paint in black, dark blue or dark brown, the contours of the image are applied. Colored glass for stained glass can be obtained from improvised material (green and brown - from broken bottles, red - from light filters or from car headlights, etc.). Glasses selected by color are broken into fragments to the size necessary for making a decorative ornament. Glasses with a glued pattern are placed in a horizontal position on a flat base with their face up and wiped with ammonia.
A layer of silicate glue is applied to the surface prepared in this way and a mosaic is laid out. After 4-6 hours, the surface of the stained-glass window is poured with a continuous layer of glue so that it covers all the protruding fragments. Glue smoothes all the roughness of the stained glass, the surface becomes wavy, shiny, clearly visible through the light.
Coloring...
"Frost patterns" on glass are obtained using wood glue. To do this, the glass is first given a dull finish by sanding by hand or sandblasting. A two to three millimeter layer of a hot strong solution of wood glue is applied to the matte surface. Drying, the glue tears off a thin film of glass, which can be easily removed with a brush.
Laminated glass.
FIELD OF APPLICATION: it is expedient to use as glasses protecting from breaking, from bullets, from fire and noise, to protect a person from various injuries, as well as for the manufacture of insulating double-glazed windows.
Laminated or laminated is called glass, consisting of two or more layers, "glued" together with a film or laminating liquid. Layers can be: made of glass of the same or different types, straight or bent in accordance with a given shape (they are shaped before gluing).
The lamination process is complex, carried out using an automated line in several stages. The last stage is carried out in an autoclave under heat and pressure. Lamination does not increase the mechanical strength of glass, but makes it "safe" - when broken, the fragments do not scatter in all directions, but remain "hanging" on an elastic film. In addition, such glasses (whole, of course) protect well from ultraviolet radiation. Laminated glass is sold both in the form of large plates, from which sheets of the required size are cut, and in the form of finished products of certain shapes and sizes.
Window glass.
APPLICATION: glazing windows, stained-glass windows, balcony doors, skylights, greenhouses, greenhouses and other translucent enclosing structures of residential buildings and industrial facilities.
High-quality window glass sheets are transparent and colorless - no iridescent and matte spots, indelible deposits, and other traces of leaching on the surface! Greenish and bluish shades are allowed, but on condition that they do not reduce the light transmission coefficient (the ratio of two light fluxes - passing through a sheet of glass to falling on the same sheet).
The strength of glass depends on several components: the method of manufacturing and processing surfaces and ends, homogeneity, the degree of annealing or hardening, the state of the sheet surface and its dimensions. When choosing glass, remember that microcracks and inhomogeneities that appeared during the manufacturing process on the sheet surfaces and in its volume reduce strength by about 100 times. Carefully inspect the edges, they should be smooth and the corners intact. Even small chips and notches along the edges will become stress concentrators, such glass is not a tenant. The presence of small defects (bubbles, foreign inclusions, scratches, and so on) is possible, but regulated by special standards.
For ordinary window glazing, sheets with a thickness of 2.5-4 mm are more often used. For large windows and stained-glass windows, they are not suitable, they cannot withstand the wind load. In such cases, thicker glass should be installed - 6 or even 10 mm. Moreover, the higher the large window is located, the thicker the glass should be and the smaller the area of its sheet.
And one more important thing. Although the properties of glass do not depend much on the direction of its cutting, it is still desirable to mark the long side of the window glass parallel to the long side of the sheet being cut. When placing an order, keep this in mind. By the way, cutting glass increases its cost by about 30 percent.
Solar control glass.
APPLICATION: glazing of windows, as well as sun protection devices - visors, vertical screens, etc. The most appropriate application in buildings with the active use of air conditioners.
Solar control glasses either reflect or absorb radiation. Heat absorbers are obtained by introducing special additives into the glass mass, coloring it in greenish-bluish or gray tones. Such glasses transmit 65-75 percent of light, and infrared rays - only 30-35 percent, and their ability to transmit and absorb rays (with a single chemical composition) depends on the thickness of the sheet.
With a high light absorption coefficient, "dark" heat-absorbing glass can become very hot (50-70 degrees above the environment), so they are not recommended for use in external glazing. It is also undesirable to subject them to uneven heating or cooling. The second type of glass, which is designed to protect from the sun, is with thin metal oxide, ceramic or polymer coatings that are transparent to the visible rays of the spectrum. These coatings are applied to one of the surfaces of ordinary colorless glass. Such glasses also absorb part of the infrared solar radiation, but they heat up much less, and their lighting characteristics do not depend much on the thickness of the sheet.
Thanks to the sun-protection glasses, the room is not so hot in summer, the contrast and brightness of the illuminated objects is less. As a result, eye fatigue is reduced, people are less tired. However, such glasses do not protect from direct sunlight (the brightness of the solar disk remains too high), so there is no need to refuse blinds or curtains.
When purchasing solar control glass, please note: the distortion of the colors of objects viewed through it should be minimal.
Heat-saving glass (energy-saving).
FIELD OF APPLICATION: are used mainly in the production of double-glazed windows.
If you buy a gas or conventional electric stove, pay attention to the fixation of the cover of the hob. It is very convenient and safe when you can leave the cooker lid in any position (at any angle of inclination). This is achieved by special balancing of the hinges.
Glasses are produced both with "hard" coatings - K-glass, and with so-called "soft" coatings - i-glass. In contrast to "soft" coatings, "hard" coatings have an inherent slight surface haze, especially noticeable in bright light. A window with such glass looks like it has been washed with dirty water.
Such glasses are most often used in modern PVC windows, significantly saving energy. For example, at an outside temperature of -26 degrees and an indoor temperature of +20, the temperature on the glass surface inside the room will be +5.1 for a conventional double-glazed window, +11 for a double-glazed window with K-glass, +14 - with i-glass.
Patterned glass.
APPLICATION: glazing of window and door openings, installation of partitions in residential, public and industrial buildings. It is not recommended to use patterned glass in rooms with a lot of dust, soot, etc.
Patterned sheet glass has a clear embossed repeating pattern on one or both surfaces and is available both colorless and colored. Color is obtained from colored "in bulk" glass or by applying colorless metal oxide coatings to one of the surfaces.
This is a decorative item. External and internal stained-glass windows, screens, partitions from it in the foyer, lobbies, cafe halls are magnificent. But it's not worth it to "screen off" rooms for confidential conversations with patterned glass. Patterned, like ordinary or colored glass, is not a barrier for those who like to eavesdrop.
The color and pattern of the glass surface must comply with approved standards. The depth of relief lines is from 0.5 to 1.5 mm. Patterned glass should transmit and diffuse light. The light transmission coefficient of the colorless version when illuminated with diffused light, if the patterns are applied only on one side - not less than 0.75, if the patterns are on both sides - 0.7. The light transmission of colored patterned glass is determined by the composition, color of the glass and coatings and is 30-65%.
Strained glass.
FIELD OF APPLICATION: glazing of windows and partitions, doors, balcony railings, flights of stairs, etc., as well as in the production of insulating double-glazed windows or laminated glasses.
Tempered glass is made from sheets of unpolished, polished or patterned glass on special tempering plants. If necessary, the required cutouts, holes are preliminarily made in the glass, the edges are processed, because the finished tempered glass cannot be cut, drilled or subjected to other types of machining.
Tempering glass is somewhat similar to tempering steel. First, it is heated above the softening temperature, and then quickly cooled in air jets. When cooled, the surface layers of the glass are the first to solidify. In them, when the inner layers cool, residual compressive stresses arise. It is these stresses that provide the mechanical strength and heat resistance of glass.
The strength of tempered glass in bending and impact is 5-6 times greater than the strength of ordinary glass, while its thermal stability is much higher. Broken tempered glass breaks into small sharp pieces. Moreover, this is regulated by the requirements of quality standards - during the control destruction with a sharp hammer weighing 75 grams, tempered glass must have at least 40 fragments in a square with dimensions of 50x50 mm or 160 fragments in a square of 100x100 mm.
The most vulnerable point of tempered glass is its edges. When mounting structures, it is necessary to protect its ends from bumps, scratches and other damage.
The light transmission of clear tempered glass is at least 84 percent.
Reinforced glass.
APPLICATION: glazing of windows, skylights, partitions in industrial, public and residential buildings, for the installation of balcony railings. Glass reinforcement is carried out as follows: a metal mesh with square cells is placed in the middle of the sheet parallel to its surface during the manufacturing process.
The grid is used welded from steel wire, and for glass of the highest quality category - also with a protective aluminum coating. The side of the square cell is 12.5 or 25 mm. The mesh should be located over the entire area of the sheet at a distance of at least 1.5 mm from the glass surface. The result is a light-transmitting material with increased safety and fire resistance.
Here it is necessary to bring clarity. Reinforcement does not increase the mechanical strength of glass and even reduces it by about 1.5 times. It won't protect you from thieves either. But the presence of a grid will not allow the fragments to scatter and fall out of the bindings if, for example, a ball or stone flies into it. High-quality reinforced glass should break off along the cut line without cracking. If there are a lot of bubbles in it, it is a marriage.
One of the surfaces of "armored glass" can be patterned or corrugated. There is also colored reinforced glass, it is made from glass mass, colored with metal oxides. The most common colors are golden yellow, green, lilac-pink, blue.
Working with reinforced glass at home is quite difficult (it is difficult to break off small pieces), but it is possible. They cut it in the usual way, then separate the pieces from each other, and the ends of the wire protruding along the edges are “bited off” with pliers. The wire is thin and breaks off easily.
It is best to fasten reinforced glass in bindings with solid glazing beads on all four sides of the sheet through rubber gaskets or on putty (mastic).
Inorganic glasses are classified by type of glass-forming substance, type of modifiers, manufacturing technology and appointment.
According to the type of glass-forming substance, inorganic glasses are divided into silicate(SiO2), aluminosilicate(A1 2 0 3 -SiO 2), borosilicate(B 2 0 3 -SiO 2), aluminoborosilicate(A1 2 0 3 -B 2 0 5 -SiO 2), aluminophosphate(А1 2 0 3 –Р 2 0 5), chalcogenide(for example, As 31 Ge 30 Se 21 Te 180), halide and other glasses.
According to the type of modifiers, they distinguish alkaline, non-alkaline and quartz inorganic glasses. The strength of alkaline glass under the action of moisture is halved, since water leaches the glass. In this case, alkaline solutions are formed, which wedged the glass, causing the appearance of microcracks in the surface layer.
According to the manufacturing technology, inorganic glass can be obtained blowing, casting, stamping, drawing into sheets, tubes, fibers, etc. Glass is produced by industry in the form of finished products, blanks, and individual parts.
By purpose, inorganic glasses are divided into technical, building and household(glass containers, dishes, household, etc.).
Technical glass by area of application is divided for electrical, transport; optical, lighting, heat-resistant, refractory, fusible, chemical laboratory and etc.
Electrical glass. High electrical resistivity, high electrical strength (16–50 kV/mm), low dielectric loss (tgδ=0.0018–0.0175) and relatively high dielectric constant (ε=3.5–16), which increases with an increase in the concentration of PbO or BaO. When heated in the temperature range of 200–400 °C, the electrical resistivity decreases by a factor of 108–1010, which is associated with an increase in the mobility of alkali ions, and the glass loses its insulating properties. Oxides of heavy metals - lead and barium reduce the mobility of ions and reduce losses.
When soldering metal into glass, when welding glasses of different composition, thermal stresses appear in the glass due to the difference in the temperature coefficients of linear expansion. If the temperature coefficients of both materials are close, then glass junctions with the material are called matched junctions, and if they are different mismatched junctions.
As a dielectric, it is used for bulbs of lighting lamps and radio tubes, in electric vacuum devices, for insulators, for sealing integrated circuits. Thus, in the form of a thin (up to 3–4 µm) film, glass is used as a strong, non-cracking, and heat-resistant insulation on metal wires and thermocouples. Chalcogenide glass is used to encapsulate semiconductor devices. Electrically conductive (semiconductor) glasses: chalcogenide and oxide vanadium - are widely used as thermistors, photoresistors.
Electrical glasses, depending on the value of the temperature coefficient of linear expansion, are divided into platinum (C89-2), molybdenum (C49-1) and tungsten (C38-1). Each glass group is used for matched junctions with Mo, W and Fe-N alloys. The brand of electrical glass indicates the value of the temperature coefficient of linear expansion.
Transport glass. In mechanical engineering, it is effectively used as a structural material, provided that brittleness is neutralized, which is achieved by hardening it, as a rule, in an air stream.
The specific properties of glasses are their optical properties: translucency, reflection, scattering, absorption and refraction of light. The refractive index of such glasses is 1.47–1.96, the scattering coefficient is in the range of 20–71.
The types of transport glass are triplexes and thermopan, used for glazing in vehicles, space suits.
Triplexes - composite material obtained from two sheets of tempered silicate (or organic) glass 2-3 mm thick, glued together with a transparent elastic polymer (usually from polyvinyl butyral) film. When the triplex is destroyed, the formed non-sharp fragments are retained on the polymer film.
Thermopan - three-layer glass, consisting of two sheets of tempered glass and an air gap between them. This air layer provides thermal insulation.
Optical and lighting glass. The optical properties of glasses depend on their color, which is determined by the chemical composition of the glasses, as well as on the state of the surface of the products. Optical products should have an isotropic, stress-free annealed structure and smooth, polished surfaces.
Ordinary unpainted sheet glass transmits up to 90%, reflects about 8%, and absorbs about 1% of visible and partially infrared light; ultraviolet radiation is absorbed almost completely. Quartz glass is transparent to ultraviolet radiation. Light-diffusing glasses contain fluorine in their composition. Glass with a high content of PbO absorbs X-rays.
Optical glasses used in optical devices and instruments are divided into crowns, characterized by low refraction (n d \u003d 1.50), and flints(n d \u003d 1.67) - with a high content of lead oxide.
Heat-resistant and refractory glass.
Pyrex - heat-resistant glass based on SiO 2 (80.5%) with a high content of B 2 0 3 (12%), Na 2 0 (4%), as well as oxides of aluminum, potassium and magnesium.
"Mazda" - refractory glass based on SiO 2 (57.6%) with oxides of aluminum (25%), calcium (7.4%), magnesium (8%) and potassium. "Pyrex" and "Mazda" are used for the manufacture of products used at elevated operating temperatures: thermometer shells, sight glasses, etc.
Lightweight glass. These glasses are made on the basis of PbO (70%) with the addition of B 2 O 3 (20%) or B 2 0 3 (68.8%) with the addition of ZnO (28.6%) and Na 2 O (2.6%) ; are used for the manufacture of enamels, glazes and solders for soldering glass.
building glass produce the following types: sheet, facing and glass products and structures.
Sheet glass is made from glass mass, which includes 71–73% SiO 2, 13.5–15% Na 2 O, up to 10% CaO, up to 4% MgO and up to 2% A1 2 0 3. The mass of 1 m 2 of sheet glass is 2–5 kg. Light transmission - not less than 87%.
Sheet glass is produced in three grades and, depending on the thickness, six sizes (grades): 2; 2.5; 3; 4; 5 and 6 mm. The grade of sheet glass is determined by the presence of defects, which include: banding - unevenness on the surface; svil - narrow threadlike stripes; bubbles - gas inclusions, etc. The width of the glass sheets is 250–1600 mm, the length is 250–2200 mm.
The industry also produces special types of sheet glass: showcase(polished), heat-absorbing, uviole(transmitting 25-75% of UV rays), hardened, architectural and construction and etc.
Sheet glass is the main type of glass used for glazing window and door openings, shop windows, exterior and interior decoration of buildings.
Facing glass is applied to finishing of facades and internal rooms of the building. The consumer properties of such glass include high decorativeness (bright colors, shiny surface), great weather resistance and durability. The group of facing glasses includes:
stemalite - sheet building material made of tempered polished (6–12 mm thick) glass, coated on the inside with opaque (deaf) ceramic paint. The coating is protected from the room side by a thin layer of aluminum deposited in a vacuum. It is applied to internal and external facing of buildings;
marblit - sheet building material 12 mm thick made of colored opaque glass with a polished front surface and a corrugated back, can imitate marble;
glass enamel tiles made from waste sheet glass (glass enamel) welded onto the surface of glass cut to the required dimensions (150x150, 150x70 mm with a thickness of 3–5 mm);
glass mosaic - carpet mosaic in the form of small square tiles (20x20 or 25x25 mm) made of opaque (muted) colored glass, laid out in plain or mosaic carpets;
smalt - cubes or plates 10 mm thick of colored opaque glass, obtained by casting or pressing; used for making mosaics.
Glass products and structures. The most common glass products and structures in the construction industry include:
glass blocks - hollow blocks of two molded halves welded together. Light transmission - not less than 65%, light scattering - about 25% (light scattering is increased by corrugation of the inner side of the blocks), thermal conductivity - 0.4 W / (m K). They are used to fill light openings in external walls and to install translucent coatings and partitions;
double-glazed windows - two or three sheets of glass connected along the perimeter by a metal frame (cage), between which a hermetically closed air cavity is created. Are applied to a glazing of buildings;
glass profile - large-sized building panels made of profile glass, produced by the method of continuous rolling of box-shaped, tee, channel and semicircular profiles. Glass profiles can be reinforced and non-reinforced, colorless and colored. It is applied to the device of translucent protections of buildings and constructions.
Fiberglass - fibrous material obtained from molten glass. The most widely used are alkali-free alumina-borosilicate E-glass, as well as high-strength glass based on oxides: SiO 2 , A1 2 0 3, MgO. The glass fiber diameter ranges from 0.1 to 300 microns. The shape of the section can be in the form of a circle, square, rectangle, triangle, hexagon. Hollow fibers are also produced. By length, the fiber is divided into staple (from 0.05 to 2–3 m) and continuous. Fiberglass density 2400–2600 kg/m 3 . The strength of elementary glass fibers is several tens of times higher than bulk glass samples: the tensile strength reaches 1500–3000 MPa for continuous fibers with a diameter of 6–10 μm. Fiberglass has high thermal, electrical and sound insulation properties, it is thermally and chemically resistant, non-flammable, and does not rot.
The surface of glass fibers during transportation and various types of processing is oiled to prevent abrasion, since their strength depends on the state of the surface of the fibers. Made from fiberglass glass wool, fabrics and grids, as well as nonwovens in the form of bundles and canvases, glass mats.
Glass wool - material made of glass fibers, the diameter of which for the manufacture of heat-insulating products should not exceed 21 microns. The structure of cotton wool should be loose - the number of strands consisting of parallel fibers should not exceed 20% by weight. The loose density should not exceed 130 kg/m 3 . Thermal conductivity - 0.05 W / (m K) at 25 ° С. Glass wool from a continuous fiber is used for the manufacture of heat-insulating materials and products at temperatures of insulated surfaces from -200 to +450°C.
Super fine fiber glass wool has a density of 25 kg / m 3, thermal conductivity of 0.03 W / (m K), operating temperatures from -60 to +450 ° C, sound absorption of 0.65–0.95 in the frequency range of 400–2000 Hz. Superfine glass wool, as well as products based on it, are used in construction as a soundproofing material.
Glass mats(ASIM, ATIMS, ATM-3) - materials consisting of glass fibers located between two layers of fiberglass or fiberglass mesh quilted with glass threads. They are used at temperatures of 60–600°C as reinforcing elements in composite materials.
Glass roofing material and fiberglass - roll materials obtained by double-sided application of a bituminous (bitumen-rubber or bitumen-polymer) binder, respectively, on a glass fiber canvas or glass felt and coating on one or both sides with a continuous layer of dressing. The combination of a biostable base and impregnation with enhanced physical and mechanical properties makes it possible to achieve durability for glass roofing material of about 30 years.
Depending on the type of dressing that prevents sticking when stored in rolls, and the purpose of the glass roofing material, the following grades are produced: S-RK (with coarse-grained dressing), S-RF (with scaly dressing) S-RM (with dust-like or fine-grained dressing). Glass roofing material is used for the upper and lower layers of the roofing carpet and for glued waterproofing.
Gidrostekloizol - waterproofing roll material intended for waterproofing reinforced concrete lining of tunnels (grade T), superstructures of bridges, overpasses and other engineering structures (grade M).
Gidrostekloizol consists of a glass base ( woven or non-woven retina, doubled with fiberglass), coated on both sides with a layer of bituminous mass, which includes bitumen, mineral filler (about 20%) with ground talc, magnesite, and also a plasticizer. It differs in addition to high water resistance by good tensile strength in the longitudinal direction. It withstands breaking load at the highest quality category of 735 N. Heat resistance - 60–65 °С, brittleness temperature - from -20 to -10 °С.
Hydrostekloizol is glued without the use of mastics - by uniform melting (for example, using a gas burner flame) of its surface.
Foam glass (cellular glass)- a cellular material obtained by sintering finely divided glass powder and a blowing agent. They are produced from cullet or use the same raw materials as for the production of other types of glass: quartz sand, limestone, soda and sodium sulfate. Pore formers can be coke and limestone, anthracite and chalk, as well as calcium and silicon carbides, which release carbon dioxide during sintering, which forms pores.
Foam glass has a specific structure - the material of the walls of large pores (0.25–0.5 mm) contains the smallest micropores, which leads to low thermal conductivity (0.058–0.12 W / (m K)) with sufficiently high strength, water resistance and frost resistance . The porosity of various types of foam glass is 80–95%; density 150–250 kg / m 3; strength 2–6 MPa. It has high heat and sound insulation properties. Foam glass is a fireproof material with high (up to 600 °C) heat resistance. Easily processed (sawed, polished); it adheres well to, for example, cementitious materials.
Foam glass shields are used for thermal insulation of building envelopes (walls, ceilings, roofs, etc.), in refrigerator structures (insulation of surfaces with an operating temperature of up to 180 ° C), for decorative interior decoration. Filters for acids and alkalis are made from open-pore foam glass.
Glasspore obtained by fanulation and swelling of liquid glass with mineral additives (chalk, ground sand, TPP ash, etc.). Three grades are produced: SL ρ 0 \u003d 15–40 kg / m 3, λ \u003d 0.028–0.035 W / (m K); L ρ 0 \u003d 40–80 kg / m 3, λ \u003d 0.032–0.04 W / (m K); ρ 0 \u003d 80–120 kg / m 3, λ \u003d 0.038–0.05 W / (m K).
In combination with various binders, glass pores are used for the manufacture of piece, mastic and poured thermal insulation. The most effective use of glass pores is in unfilled foam plastics, since its introduction into the foam plastic makes it possible to reduce polymer consumption and significantly increase the fire resistance of heat-insulating products.
Reinforced glass - a structural product obtained by the method of continuous rolling of inorganic glass with simultaneous rolling inside a sheet of metal mesh from annealed chrome-plated or nickel-plated steel wire. This glass has a compressive strength of 600 MPa, increased fire resistance, shatterproof in case of destruction, light transmission - more than 60%. It may have a smooth, forged or patterned surface, be colorless or colored.
Reinforced glass is used for glazing skylights, window casings, partition walls, flights of stairs, etc.
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Glass grinding and polishing
The concept of glass and the classification of glass products
The concept of glass. Solids are crystalline and amorphous (glassy). Crystalline bodies have a geometrically regular crystalline structure formed by particles (ions or atoms) in a strictly repeating order throughout the volume (long-range order). They have a constant melting point. Amorphous bodies with increasing temperature gradually soften up to the formation of a melt. They are characterized by a short-range order, i.e. they have only small sections of a regular, ordered structure, which are asymmetrically interconnected.
Amorphous bodies are called glass, obtained by supercooling the melt, regardless of their chemical composition and solidification temperature range, and possessing the mechanical properties of solids as a result of a gradual increase in viscosity, and the process of transition from a liquid state to a glassy state must be reversible. By their nature, glasses are isotropic substances, that is, they have the same physical properties in all directions, while crystalline bodies are anisotropic, that is, their properties are different in different directions.
Glass is a transparent (colorless or colored) brittle material. According to the type of glass-forming component, silicate glasses (based on EIg), borate glasses (based on B2O3), borosilicate, aluminosilicate, boroaluminum-silicate, phosphate glasses (based on P2O5), etc. are distinguished.
Classification of glass products. Various products are made from glass, which are classified according to various criteria.
By purpose, glass products are divided into technical, construction and household.
Technical glass includes optical, chemical and laboratory, medical, electrical, electrode, transport, instrument, protective, heat, sound and electrical insulating, lighting, lumpy, as well as pipes, technical mirrors, photographic glass, fiberglass and fiberglass, filters, glass abrasives and various glass parts of machines and installations. This is the most numerous class of glass products.
The class of building glass includes glass products used in construction: window, display, profile, reinforced, patterned, cladding, foam glass, mosaic, double-glazed windows, glass blocks, stained-glass windows, architectural, various building details, building fiberglass and decorative finishing glass fabrics.
Household glass - dishes and spectacles, glass containers, household mirrors, enamels, glazes, decorations and imitations. Tableware glass includes sorted glass with or without artistic processing (glasses, glasses, glasses, vases, decanters, salad bowls, sugar bowls, powder boxes, thermoses). It is these products that are most often ground and polished.
According to the nature of the surface, glass products come with a glossy or non-glossy surface. The glossy surface is obtained by metallization, semiconductor or conductor coating, organic film and organosilicon compounds. A separate group consists of products with a smooth, chemically etched surface. A non-glossy, coating-free surface can be matte solid or patterned, grainy, “frosty”.
According to the type of processing, glass products are divided into five classes: the first - products subjected to heat treatment, the second - products whose surface has a mechanical (cold) treatment; the third - with mechanical (cold) processing of the edges of products; the fourth - with chemical treatment; the fifth - with surface coatings.
Numerous glass compositions have been developed to meet the requirements for each product group. For convenience, glass compositions are expressed as a percentage by weight of the oxides included in this glass, for example:
conventional Si02 -74.5; A1203 -0.5; CaO -6.5; MgO-2.0; Na20 -14.0; KjO - 2.0; crystal Si02 -57.5; A1203 -0.5; K20-15.5; B203 - 1.5; ZnO-1.0; PbO - 24.0 (up to 24% PbO is added to the composition of crystal glasses, which improves the gloss and color of the glass).
Glass goods.
Glass- a homogeneous amorphous body, which is obtained by cooling the glass mass. A simple example is to take a cube of sugar, heat it to a liquid state, and then cool it. Sugar loses its original crystalline structure and becomes an amorphous substance.
History of glass.
For the first time glass appeared in Ancient Egypt for 3 ... 4 millennia BC. However, the glasses of that era, even in appearance, differed from those of today. They were, as a rule, not transparent and contained a large number of bubbles. Jewelry was made from such glass.
At the end of the 7th century glass production occurs in Venice where by the 9th century. it reaches a high level. Famous Venetian stained-glass windows and mosaics adorned the churches of that period, and various artistic products made of colored glass, mosaic and filigree glass, mirrors were the monopoly of Venetian glassmaking. Then this art penetrated other countries of Western Europe and the Middle East.
At the end of the XVII century. in the Czech Republic, glass was invented, distinguished by purity, transparency and hardness, and known as "Bohemian crystal".
Glassmaking in Russia arose in the 9th - 10th centuries, i.e., much earlier than in
America (XVII century) and earlier than in many other countries of Western Europe.
The first glass factory in Russia was founded in 1638 near Moscow. This plant produced window glass and other glass products. Glassmaking was greatly developed under Peter I. During this period, glass factories were created near Moscow, in Kyiv and other cities. By 1760, there were already more than 25 glass factories in Russia, located in various provinces. These factories produced mainly window glass, bottles and household utensils.
The founder of the scientific foundations of glassmaking in Russia is M.V. Lomonosov, who in 1752 built a factory near St. Petersburg and organized the production of colored glasses on it. M.V. Lomonosov developed a method of hot pressing of glass.
glass composition.
Raw materials for glass production are divided into basic or glass-forming and auxiliary.
With the help of basic materials, various oxides are introduced into the composition of the glass, which, when fused, form a glass mass. The properties of glass depend on the oxides included in it and their ratio. The main oxide, SiO2, is introduced into the glass through quartz sand. The sand must be free from impurities, especially coloring (oxides of iron, titanium, chromium), which cause bluish, yellowish, greenish shades of glass, reduce its transparency. With an increase in the content of silicon dioxide in glass, mechanical and thermal strength, chemical resistance improve, but the melting temperature rises.
Boron oxide B2O3 facilitates melting and improves the physicochemical properties of glass.
A12O3 aluminum oxide helps to increase the strength and chemical resistance of glass.
Alkaline oxides Na2O, K2O lower the melting temperature of glass, facilitate the molding of products, but reduce strength, heat resistance and chemical resistance.
Oxides of calcium, magnesium, zinc increase the chemical resistance and heat resistance of products. Oxides of barium, lead and zinc increase the density, improve optical properties and therefore are used in the production of crystal.
Auxiliary materials introduced to improve the consumer properties of glass. According to their purpose, they are divided into clarifiers, bleaches, silencing agents, dyes, reducing agents and oxidizing agents.
Clarifiers contribute to the removal of gases from the glass mass, which are formed during the decomposition of raw materials. Due to gas inclusions, the mass of glass becomes opaque. Saltpeter, ammonium salts, arsenic trioxide are used as clarifiers. When heated, clarifiers decompose, rise up in the form of vapors and entrain gaseous inclusions.
Decolorizers extinguish or weaken unwanted color shades. Due to small impurities of iron oxides, the glass has a greenish-bluish tint and decolorizers are used to make this tint invisible. Apply 2 methods of discoloration - physical and chemical. With the physical method, an additional dye is introduced into the composition of the glass mass, which neutralizes the effect of the main one. Physical bleaches include compounds of manganese, cobalt, etc. Chemical bleaches convert colored compounds into uncolored ones. These include saltpeter, antimony. These compounds convert 2-valent iron oxide to 3-valent iron oxide, which has a weaker color.
Silencers(fluorides and phosphates) reduce transparency and cause the glass to appear white.
Dyes give the glass the desired color. Heavy metal oxides or sulfides are used as dyes. Coloring can also occur due to the release of colloidal particles of free metals (copper, gold, antimony) in the glass.
Glass is dyed blue with cobalt oxide, blue with copper oxide, green with chromium or vanadium oxide, purple with manganese peroxide, and pink with selenium, etc.
Oxidizing and reducing agents added when cooking colored glasses to create a certain pH environment. These include saltpeter, carbon, etc.
Cooking accelerators contribute to the acceleration of glass melting. These include fluorine compounds, aluminum salts, etc.
glass properties. Depends on its composition.
The density of ordinary glass is 2500 kg/m3, glasses with a high content of lead oxide have the highest density - up to 6000 kg/m3. It depends mainly on the presence of heavy metal oxides (lead, barium, zinc) in the composition of the glass and affects the mass of products, optical and thermal properties. With an increase in density, the refractive index of light, the brilliance and the play of light in the faces increase, but the heat resistance, strength and hardness decrease.
The optical properties of glass are varied. Glasses can be transparent (transmittance of 0.85 or more) and muted to varying degrees, colorless and colored, with a shiny and matte surface. The main optical properties of glass are: light transmission (transparency), light refraction, reflection, scattering, etc. Ordinary silicate glasses transmit well the entire visible part of the spectrum and practically do not transmit ultraviolet and infrared rays. The transparency of most glasses is 84-90%. By changing the chemical composition of the glass and its color, it is possible to control the light transmission of the glass. The refractive index (the ratio of the sine of the angle of incidence to the sine of the angle of reflection) for ordinary glasses is 1.5, for crystal 1.9. At the same time, the higher the refractive index, the higher the reflection coefficient.
Glass has a high compressive strength of 700-1000 MPa and a low tensile strength of 35-85 MPa.
Hardness is the ability of glass to resist being penetrated by another body. Depends on composition. Quartz glasses, as well as borosilicate low-alkali glasses, have high hardness. Crystal glasses are 2 times softer than ordinary ones. The hardness of ordinary silicate glasses is 5-7 on the Mohs scale.
Brittleness is the ability of glass to resist impact. Glass does not resist impact well, that is, it is fragile. The presence of boric anhydride and magnesium oxide in the glass increases the impact resistance of the glass.
The thermal conductivity of glass is low, so glass is used to protect rooms in winter. Quartz glass has the highest thermal conductivity.
The thermal stability of glasses depends on many factors: the composition of the glass, the shape and size of the product, the nature of the surface, etc. With the help of special heat treatment, the thermal resistance of glass can be increased several times.
The electrical conductivity of glass is low (glass is a dielectric). At the same time, the electrical conductivity of glasses changes with temperature (molten glass conducts current). The greatest influence on the electrical conductivity is exerted by the content of lithium oxide in them; the more it is in the composition of the glass, the higher the electrical conductivity. Reduce the electrical conductivity of oxides of divalent metals (most of all BaO).
Glass can be machined: it can be sawn with diamond-filled circular saws, turned with pobedite cutters, cut with a diamond, ground, polished. In the plastic state, at a temperature of 800-1000°C, glass can be molded.
glass classification.
Glasses are classified according to composition. Their name depends on the content of certain oxides. The following oxide glasses are distinguished:
silicate - SiO 2;
aluminosilicate - Al 2 O 3, SiO 2;
borosilicate - B 2 O 3, SiO 2;
boron aluminosilicate - B 2 O 3, Al 2 O 3, SiO 2 and others.
Each type of glass has certain properties.
Silicate glasses are divided into ordinary, crystal, heat-resistant. Common ones include soda-lime, soda-lime, potassium-lime, soda-potassium lime glasses.
Crystal glasses are characterized by increased brilliance and strong refraction. Distinguish between lead and lead-free crystal. Lead crystal has an increased mass and is well decorated. According to the amount of lead oxide, lead crystal is divided into
1. Crystal glass containing at least 10% lead, boron or zinc oxide.
2. Low lead crystal containing 18-24% lead oxide.
3. Lead crystal containing 24-30% lead oxide.
4. High lead crystal containing 30% or more lead oxide.
Lead-free crystal contains mainly barium oxide (at least 18%), which improves refraction, increases the hardness and brilliance of glass, but reduces transparency.
Heat-resistant glasses withstand sudden changes in temperature. They include boron compounds (12-13%). The thermal stability of such glass increases after tempering.
Chemical properties of glass.
The chemical resistance of glass determines the purpose and reliability of products. It is very high, especially in relation to water, organic and mineral acids (except hydrofluoric). Alkalis and alkali carbonates act more aggressively. Hydrofluoric acid dissolves glass and is therefore used for applying patterns to glass, matting and chemical polishing of products.
The formation of consumer properties of glass products occurs in the process of their production.
Production of glass goods consists of a number of stages: preparation of raw materials, blending, melting of glass melt, production of glass products, processing and decoration of products, sorting, marking and packaging of products.
1. The preparation of raw materials is reduced to the purification of quartz sand and other components from unwanted impurities, fine grinding and screening of materials.
2. The preparation of the charge, i.e., a dry mixture of materials, consists in weighing the components according to the recipe and thoroughly mixing them until completely homogeneous. A more advanced method is the production of briquettes and granules from the charge; at the same time, the homogeneity of the charge is maintained, and cooking is accelerated. In addition, to speed up the melting of glass, 25-30% of glass cullet is added to the mixture. Cullet is washed, crushed and passed through a magnet.
3. Cooking glass melt from the charge is carried out in baths and pot furnaces at a maximum temperature of 1450-1550°C. During the cooking process, complex physical and chemical transformations and interactions of raw materials occur. With the help of clarifiers, the glass mass is freed from gas inclusions, thoroughly mixed until a uniform composition and viscosity is achieved. In case of violations of the modes of processing raw materials, preparation of the mixture and cooking, defects in the glass mass are formed (we will analyze later).
4. The molding of products from viscous glass mass is carried out by various methods. The molding method largely determines the configuration of products, wall thickness, decoration techniques, coloring, and therefore is an important assortment feature and pricing factor.
Household products are made by blowing, pressing, pressing blowing, bending (bending), casting, etc.
Blowing - the oldest method of molding glass products. Blowing can be mechanized, vacuum-blown, manual in molds and gooten (free).
Manual blowing is carried out using a glass blowing tube. Such blowing can be carried out in molds and without molds. By blowing in molds, products of any configuration and wall thickness with a smooth and shiny surface are obtained. They produce colorless, mass-dyed and overhead products (two- and multi-layered).
Blowing without a mold or free blowing (in the trade - Gooten molding) is also carried out by means of a glass blowing tube, but the products are molded and finally finished mainly in air. Products are characterized by the complexity of forms, smooth transitions of parts, thickened wall.
By mechanized blowing on automatic machines, colorless products of simple outlines, mainly glasses, are produced.
Blown products have the smoothest walls, strong gloss, high transparency, the most diverse shape and wall thickness. They are decorated in almost all possible ways and are considered the highest quality.
Pressing are the most widespread and economical methods of obtaining glass products. Products are formed on automatic and semi-automatic presses in special molds, where a pattern is immediately applied to them. They are characterized by a large wall thickness (more than 3 mm), a large mass, less transparency and heat resistance, a significant bottom thickness, traces of the shape are visible. Pressed utensils have simple shapes with a wide top.
They try to overcome some monotony of pressed products by creating a light relief pattern on the surface (textured press), by pressing without an upper ring, which makes it possible to obtain a freely formed edge different for each product, by combining pressing and bending (press bending).
Pressblowing characterized by the fact that the molding of products takes place in two stages - first they are molded in a mold, and then in hot air. Products have a narrow neck, thick uneven walls and traces of the shape. Press blowing produces jars, bottles, carafes, vials; Products obtained by this method differ from pressed ones in a more complex shape, and from blown ones, in thick walls, traces of the shape and a rougher pattern.
Casting. The glass mass is poured into a special mold, where it cools and takes on the shape of the mold. This method is used to obtain artistic and decorative products.
centrifugal casting carried out in rotating metal molds under the action of centrifugal forces. Products obtained by this method have a large mass, and large-sized products are finished manually. Aquariums can serve as an example of products made by centrifugal casting.
Other molding methods are less common.
Incorrect molding may cause various defects.
5. Annealing products. During molding, due to the low thermal conductivity of glass, sharp and uneven cooling, residual stresses arise in products that can cause their spontaneous destruction. Therefore, annealing is required - heat treatment, which consists in heating the products to 530-550 ° C, keeping at this temperature and subsequent slow cooling. During annealing, residual stresses are weakened to a safe value and are evenly distributed over the cross section of the products. The thermal stability of glass depends on the quality of annealing.
6. Processing and decoration. Primary processing consists in processing the edge and bottom of the products, grinding the corks to the throat of decanters. Decorative processing is the application of decorations of a different nature to products. Decor determines the aesthetic properties of glass products and is one of the main pricing factors.
Cuttings are classified according to the stage of application (hot and cold), types, complexity.
Hot applied decorations:
1. Colored glass is obtained by adding dyes to glass mass.
2. Colored products are made from 1 layer of glass and coated with 1 or 2 layers of intensely colored glass.
3. Decoration of blown products in a hot state is carried out by applying glass moldings, ribbons, twisted and tangled threads. Variety - decoration with filigree or twisting has the form of 2 or 3-colored spiral threads.
4. Marble or malachite decoration is obtained in the process of melting milk glass with the addition of ground, unmixed colored glass.
5. Cutting "crackle" ("under the frost", "frosty glass") - a network of small surface cracks formed during the rapid cooling of the product in water. Next, the semi-finished product is placed in a furnace, where the cracks are melted.
6. A “roller cut” is used, which creates an optical effect due to the wavy inner surface formed when the billet is blown in a ribbed shape.
7. Jewelry in bulk. The heated workpiece is rolled over crushed colored glass, which is melted to the surface.
8. Iridescent films (irrization) on the surface of products can be obtained when salts of tin chloride, barium, etc. are deposited on a hot product; these salts, decomposing, form transparent, shiny, iridescent films of metal oxides (reminiscent of mother-of-pearl).
9. Jewelry by free blowing - the product acquires a peculiar and unique shape.
10. Chandeliers - application of metal solutions to the surface of the product. Next, the product is annealed, the solvent evaporates, and the metal film is fixed on the surface.
11. Pressed products are decorated mainly due to the pattern from the mold.
Cold decoration carried out by mechanical processing, chemical processing (etching) and surface decoration using silicate paints, gold preparations, chandeliers.
Mechanically applied cuts include matte tape, numbered grinding, diamond cutting, flat cutting, engraving, sandblasting.
1. Matte tape is a strip 4-5 mm wide. A metal strip is pressed against the surface of the product during its rotation, under which sand and water are fed. In this case, the grains of sand scratch the glass.
2. Number grinding - matte surface (shallow) pattern of round, oval sections or notches. Applied with emery wheels.
3. A diamond face is a pattern of deep dihedral grooves, which, combined with each other, form bushes, nets, polygonal stones, simple and multi-beam stars and other elements. The pattern is applied on manual or automatic machines using an abrasive wheel with a different edge profile. After cutting the pattern, it is polished to full transparency. The diamond facet is especially effective on crystal products, where the brilliance and play of light in the facets are well revealed.
4. Flat edge - these are polished planes of various widths along the contour of the products.
5. Engraving - a surface matte or less often light drawing of a predominantly vegetative nature without large depressions. It is obtained using rotating copper disks or ultrasound.
6. Sandblasting - a matte pattern of various shapes, formed during the processing of glass with sand, which is fed under pressure into the cutouts of the stencil.
Cuts applied by etching, subdivided into simple (heliospheric), complex (pantograph), deep (artistic) etching. To obtain a pattern, products are covered with a layer of protective mastic, on which a pattern is applied with machine needles or manually, exposing the glass. The glassware is then immersed in a bath of hydrofluoric acid, which dissolves the glass in a naked pattern to varying depths.
Simple, or heliospheric, etching is an in-depth transparent geometric pattern in the form of straight, curved, broken lines.
Complex, or pantograph, etching is a linear in-depth pattern, but of a more complex, often vegetative nature.
Deep, or artistic, etching is a relief pattern in the main plant plot on 2 or 3-layer glass. Due to the different depth of etching of colored glass, a pattern of different color intensity is formed.
Surface decoration can be carried out with silicate paints, gold preparations. Such decorations include painting, decalcomania (represents a multi-color drawing without brush strokes, applied using decals), silk-screen printing (a single-color drawing obtained by stenciling using a silk mesh), applying ribbons (4-10 mm wide), layering (1- 3 mm), antennae (up to 1 mm), photographic images, etc. New methods of jewelry are being developed - plasma spraying of metals, glass powders, photochemical engraving, etc.
The production process ends with acceptance control and labeling of products.
Glass has been known to all mankind for quite a long time, to be more precise, around the 54th-55th centuries. And accordingly, during this entire period, it has undergone many changes, one can even say that it has changed. Since at the moment there is more than one type of glass, there is a whole glass classification. Without any doubt, no matter what the glass is, each of its types must combine the functions that were previously incorporated in it. To be more specific it is:
- - aesthetics;
- - soundproofing;
- - thermal insulation;
- - overheat protection;
- - security.
Next, we will dwell in more detail on the currently available classification of glasses.
1. Window glass It is a colorless and completely transparent leaf. According to the rules, this type should not contain any spots, blackouts and other defects, unless, of course, this is high-quality glass. The window sheet may have a shade of green or blue, but taking into account the fact that the light transmittance will not be below the established norm.
When choosing glass, do not forget that the more transparent and uniform it is, the better and stronger it is. Since each defect reduces its strength by 90-100 times, except for those regulated by special standards.
And one more thing to remember, if you are going to glaze windows on the lower floors, then choose glass with a thickness of 3 or 4 millimeters. And if you are going to install large stained-glass windows at a higher level, then you need to choose glasses with a thickness of at least 6 mm, that is, it turns out that the higher the window, the greater its thickness, but already a smaller area.
As you already understood, window panes are used for glazing stained-glass windows, balconies, greenhouses and other light-transmitting fences in residential or non-residential premises.
2. Heat-saving or energy-saving glass- this is a type of glass coated with an optical coating that allows short-wave solar radiation to enter the room, but prevents long-wave thermal radiation from leaving the room, for example, from the same heating devices.
At the present time, the following types of coatings are known:
- K-glass (hard coating);
- i-glass (soft coating).
If we compare these coatings, then the hard coating has a slight surface haze, noticeable only in bright light. But such a window looks like it is in dirty water outlets.
Such types of glass are most often used in more modern PVC windows, which save energy significantly.
Energy-saving windows are usually used in the production of double-glazed windows.
3. sun protection glass- a glass that can reduce the transmission of light energy.
Sunglasses are divided into 2 types:
- significantly reflecting radiation;
- substantially receiving radiation.
Type 1 solar-reflecting glass is window sheets of colorless or maybe even colored glass, one of the sides of which is covered with a thin layer of metal oxide during the manufacturing process, which prevents radiation from penetrating through the glass. Reflective layers at the same time absorb part of the radiation.
Glass of this type can be installed both inside and outside. It depends on what shade you need from the inside of the room.
In the manufacture of absorbing glass, crystals or metal oxides are deposited on molten glass, capable of absorbing part of the radiation. At the same time, the glasses are heated and, accordingly, give a large proportion of the heat they receive to the outside. Part of the heat is still transferred inside the room, which is of course undesirable, since it increases the need for energy at times, which is necessary for cooling the room.
Thanks to sun-protection glasses in summer weather, the room is not so hot, the brightness and contrast of the illuminated objects is much less. And as a result, people feel less tired. But these glasses, unfortunately, do not help from direct bright sunlight, so the curtains will have to be left.
Sunglasses are used for glazing sunscreens and windows, and to a greater extent they should be used in air-conditioned office buildings.
4. patterned glass- this is a glass sheet that has a double-sided or one-sided repeating relief pattern on transparent or colored glass. Patterned glass is considered a decorative element of the interior, and therefore it can transmit all sounds both from the outside and from the inside.
The design and color of the glass must comply with established standards. The depth of the relief should be according to the established rules - from 0.4 to 1.6 mm. According to the rules, patterned glass must also transmit and distribute light. The light transmission coefficient of transparent glass of this kind when illuminated by diffuse light, if the patterns are only one-sided - not less than 0.75, and if the patterns are double-sided - 0.7. The light transmission of colored patterned glass is always determined by their composition, the color of the coatings and the glass itself and is 35-60%. Patterned glass can also be used for glazing windows, doorways, various screens and partitions.
5. Reinforced glass It is a glass with a simple metal mesh, it is completely safe and fire resistant, and serves as a good smoke barrier. In the event of a fire, it may crack, but the reinforcement will hold it in place and prevent the fire from escaping. Pieces of glass will not fall out even if a series of faults are formed. Reinforced glass can be used for glazing factory floors, windows, elevators and facades.
6. Strained glass- this is a sheet of glass, which can be polished, unpolished or even patterned, which is further tempered on special tempering devices.
Tempering glass is similar to tempering steel. At the same time, it must be remembered that tempered glass can no longer be mechanically processed, and therefore this procedure must be carried out strictly before the tempering process itself.
The most vulnerable or fragile place of tempered glass is considered to be its edges. During reconstruction, it is necessary to protect its ends from heavy blows and other possible damages. The light transmission of colorless transparent tempered glass must be at least 85%.
Tempered glass is used both in glazing and in the production of so-called insulating glass or laminated glass.
7. Laminated or laminated glass- this is glass, which consists of two, three or more layers, combined with each other by a laminating liquid.
Lamination does not increase the strength of the glass, but when broken, laminated glass does not break into small pieces due to the laminating liquid, i.e. pieces remain on it. Laminated glass also provides ideal soundproofing for rooms. several layers of glass can effectively reduce the impact of unnecessary noise. It is possible to organize almost any glass tinting with a laminating film.
Laminated glass in most cases is used for glazing facades, balconies, windows, as well as for protection against bullets, fires, noise and burglary.
8. Self-cleaning glass- this is the most ordinary glass with a special coating on the outer surface of the glass, which has a double effect. In the event that reflections of daylight fall on the glass itself, its coating reacts to light in two ways.