In addition to standard types of glass, the industry also produces several special models that are designed for one specific purpose. Such small-scale production makes the material more expensive, but in terms of functionality it will be more perfect. Armored glass is installed in buildings where material assets are stored or high-ranking people work, who can be assassinated.
Also, this material is used in the manufacture of protected vehicles designed to transport members of the government. Glass is characterized by a much greater degree of resistance to mechanical impact than the standard counterpart. A similar effect is achieved through a special production technology.
Types of protective glasses
There are several types of resistant glass, which differ in the degree of protection. All of them can be represented as the following list:
- . anti-vandal glass;
- . glass against breaking;
- . bulletproof glass;
- . blast resistant glass.
The first model is the simplest and usually consists of several standard glasses glued together. Such a design is able to withstand the impact of a heavy object, but with a more decisive impact, it will not withstand. Therefore, this type is not suitable for storing material values. It is used as a showcase so that overly violent citizens cannot damage the goods.
Anti-burglary glass is already being made thicker and more durable. It must withstand not only blows, but also attempts to penetrate with a glass cutter. Attackers often use special tools in their craft to open the protection, so the material must be strong enough so that the violation of its integrity takes a long time. This will most likely scare off thieves and force them to look for another object.
bulletproof glass installed in cars of senior officials, collection vans, military vehicles. The essence of such a material is not only to extinguish the kinetic energy of the bullet, but also to evenly distribute it over the surface. Then the pressure level at one point will drop several times, and the glass will remain intact. Cracks may appear on the outer shell, but integrity will not be compromised.
Although if you hit the same point several times, the glass may break. The explosion-proof model is the most durable of all. It can withstand the multi-point instantaneous destructive effect that is formed when the fragments fly apart. Bank vaults and some vehicles are equipped with such models. Due to the large thickness, the glass will be very heavy.
Manufacturing technology
Many users are interested in the question of how to book glass? At home, it will be impossible to achieve the maximum effect. There are ways to enhance base materials with additional accessories, but the effect will be much lower. In industrial production, technology consists of many successive phases:
- 1. Standard plate glass is produced first. In some cases, special additives are introduced into its composition, which will increase transparency.
- 2. Next, using a double-sided adhesive film, several glasses are interconnected. Sometimes a photohardening polymer is used for this. In this case, the degree of transparency will depend on the amount of materials. Usually protective glass has a greenish tint and poor light transmission.
- 3. At the end, testing is carried out, which will allow you to identify obvious defects and eliminate them before the batch of goods goes to the warehouse.
At home, you can use armored film on glass. It consists of several layers of a complex polymer that increases the strength of any surface to which it is glued. Protection is provided at the molecular level, so its degree will be maximum. You can buy an accessory in the store of the corresponding goods, and its price will be available to everyone. Such booking of window panes will allow you to protect yourself from hooligans and burglars.
Window protection
Such a procedure as armoring car windows with a film is done quite often. In most cases, drivers do not want to protect themselves from firearms and explosions, but simply want to make the glass more durable. Regular models can break from an accidental hit by a pebble that jumped out from under the wheels. And in the presence of a protective layer, such a nuisance is excluded. The maximum that remains is a small trace.
Reservation of a windshield is made on car services. Often, you do not even need to pre-purchase the film, as it can be purchased directly from the masters. The procedure takes several hours, after which the transport is immediately ready for use. You don't have to wait a few days for the material to set.
According to reviews, booking a windshield gives an excellent effect. After the operation, cracks from crushed stone stopped appearing on the glass. Also, all past flaws will be under a reliable dome and will not be able to grow further.
The price of armored glass depends on the brand and thickness. You can find out the specific value in the electronic catalog on the official website of the trading company.
It is easy to imagine the front line, even in the conditions of the modern "civilized" world. There are a lot of dangerous zones where you have to dodge bullets in this world. In such conditions, special assistance is required, which modern technologies are ready to offer. However, not only the sniper's bullet may require protection, but also in other cases when the need to dissipate the energy of movement becomes relevant. In any case, the idea of bulletproof glass seems like a good fit. Therefore, let's consider (just in case "fireman") what constitutes bulletproof, how other moments are produced.
Everyone once had to catch a ball flying fast in the air. The trick of it easy way energy damping is when the hand moves along the motion vector of the flying object, gently stopping the flying ball.
This reduces the strength of the obstacle (arm). As a result, hitting the ball is perceived completely painless. In scientific terms, the force of the ball acting on the palm of the hand is equal to the moment of speed of movement.
The passage of a bullet through ordinary glass is inevitably accompanied by the destruction of the latter. Moreover, the bullet does not lose any energy of movement in this case of resistance However, unlike the palm of the hand, a piece of glass does not have the properties of synchronous movement. If a piece is fired from a firearm, it becomes obvious that this object is not able to bend and absorb energy.
As a result, the glass simply collapses, and the bullet overcomes the obstacle with virtually no loss of momentum. This is why ordinary glass is not capable of protecting against bullets, and in such cases, a bulletproof design is required that is more effective in absorbing motion energy.
How bulletproof glass works
Ordinary and bulletproof glass are two completely different things. In any case, one design differs radically from the other. Meanwhile, bulletproof glass is not a completely bulletproof structure. Restrictions, of course, exist, as there are firearms with different recoil strengths.
This is what the structure of reinforced glass looks like, which is already difficult to destroy with sufficiently large caliber bullets fired from high-powered firearms. Bulletproof glass is made up of several layers of durable transparent material with "interlayers" made on the basis of various kinds plastics. Some designs of bulletproof glass contain a final inner layer made of polycarbonate (a hard type of plastic) or a plastic film.
This layer prevents the "splint" effect (when pieces of glass or plastic break off when hit by a bullet). Such a "sandwich" of layers is called a laminate. A kind of bulletproof laminate is an order of magnitude thicker than ordinary glass, but at the same time it has a relatively small weight.
Energy absorbing design property
When a bullet hits bulletproof glass, it impacts the existing layers. Since the energy is distributed between the various layers of bulletproof glass and plastic interlayers, the spread of force occurs over a large area, which is accompanied by a rapid absorption of energy.
The effect on bulletproof glass of the simplest configuration, obtained from the impact of a bullet fired from a pistol at close range. As you can see in the picture, the structure was damaged, but did not collapse and did not miss the bullet. The movement of the bullet is slowed down to such a level of energy that the forces to overcome the obstacle are completely lost and are not able to cause significant damage. Bulletproof glass panels are, of course, damaged, but the plastic layers do not allow the panels to break into small fragments. Therefore, bulletproof glass should be considered rather as an energy-absorbing object in order to clearly understand the operation of this protective device.
How is bulletproof glass made?
The traditional execution of bulletproof glass, as already noted, is represented by alternating glass panels (3–10 mm thick) and plastic. In this case, the plastic is present in the form of a thin film (thickness 1-3 mm) made on the basis of polyvinyl butyral (PVB). Modern durable types of bulletproof glass represent a similar kind of "sandwich", containing:
- acrylic glass,
- ionoplastic polymer (for example, SentryGlas),
- ethylene vinyl acetate or polycarbonate.
In this case, thick layers of glass and plastic are separated by thinner films of various plastic materials, such as polyvinyl butyrol or polyurethane.
The structure of a three-layer structure from a number of first products: 1, 2 - ordinary glass; 3 - polyvinyl acetate resin mixed with polycarbonate glycol plasticizer To make a simple PVB-based bulletproof glass, a thin film of PVB is sandwiched between thicker glass to form a laminate. The formed laminate is heated and compressed until the plastic begins to melt, making it with a glass panel.
Typically, this process is done under vacuum to prevent air from getting in between the layers. The penetration of air into the interlayer contributes to the weakening of the laminate structure, affects the optical properties (distorts the transmitted light).
The device is then placed in an autoclave and brought to full readiness under conditions of higher temperature (150°C) and pressure (13-15 ATI). The main difficulty of this process is to ensure proper adhesion of the plastic and glass layers. It is necessary to remove air from the space between the layers, to exclude possible deformation of the plastic from overheating and overpressure.
Where is bulletproof glass used?
The product is manufactured in a variety of shapes and sizes to provide different levels of protection for emergency situations. Most often, the use of bulletproof glass is seen as a characteristic phenomenon in the banking sector.
Cash rooms are usually equipped with bulletproof ones, and bulletproof boxes for the exchange of documents and money are also used.
Protection of bank cash desks with a multilayer glass structure provides an increased level of security. This is one of those areas where bulletproof structures are used quite often. The quality of protection depends on the thickness of the product. The thicker the glass (the more layers), the better the absorption of energy is provided, respectively, the level of protection increases. The base bulletproof glass has a thickness of 30-40 mm, but if necessary, this parameter can be doubled.
The only problem is that increasing the thickness of the bulletproof glass inevitably leads to an increase in weight. Perhaps this is a minor problem for equipping a bank's cash desk, but becomes a significant problem, for example, in the case of the production of bulletproof glazing.
Increasing the thickness of the bulletproof glass also reduces the transparency factor as the light is "dimmed" by the additional layers of construction. Sometimes this design creates additional difficulties, for example, in a car, when bulletproof glass impairs the driver's visibility.
Bulletproof glass has a multilayer structure. It consists of special glass sheets and a polymer film between them. The number of layers varies depending on the protection class of the product.
Bulletproof glass: scope
The installation of such structures is justified in those places for which there is a real threat of an armed attack. The installation of special bulletproof booths and windows is carried out in banking institutions, exchange offices, courtrooms, security posts, jewelry stores, and so on. Often such structures are equipped with entrances to protected objects. Special bulletproof windows can be seen in vehicles that have armor protection.
What are the advantages of such glass?
The product is resistant to shock and other mechanical damage.
. The use of special bulletproof glass minimizes the risk of injury from splinters. Even if it breaks, it will not shatter into small pieces, which usually pose the greatest danger.
. The product provides for the possibility of tinting. This feature allows you to use bulletproof glass as a decorative element.
. Bulletproof glass does not change its quality characteristics in conditions of high humidity, sudden temperature changes and other negative external factors. It retains its properties and original appearance throughout the entire operational period.
How is bulletproof glass made? Interested in the production technology of bulletproof glass!
The history of bulletproof glass began in 1910, when the French scientist Edouard Benedictus invented a method for producing extra strong glass by placing a special celluloid film between two glass sheets. Such glass, now known as laminated glass, was patented by Benedictus under the name "triplex". However, do not expect to sit behind bulletproof glass during a serious shelling. Absolute armor that protects against all firearms simply does not exist, especially armor made of glass ...
Triplex is the most reliable and safe glass. Over the century that has passed since the Frenchman made his landmark invention, the glass industry has gone far ahead, and now the triplex manufacturing technology is approximately the following. Two sheets of tempered glass are glued to each other over the entire surface with a polymer film or a laminating liquid. (By the way, she herself worked at the Macromer Research and Production Enterprise in the production of such a liquid - indeed Gin is right, this is Acrolat: http://www.macromer.ru /him.shtml?base=5&...) Moreover, sheets can be made of glass, either one or different types, can be straight or bent (they are shaped before gluing). Lamination itself is a rather complicated process, it is carried out on an automated line in several stages. At the last stage, the glass sheets enter the autoclave, where high temperature the film polymerizes and, like glue, connects the glass. As a result, the impact strength of conventional triplex is 10–15 times higher than that of conventional sheet glass. If the triplex still manages to be broken or pierced by a bullet, the fragments will not splash in all directions - they will hang on the intermediate film without causing harm. Such laminated glass looks like a monolith.
However, a polymer film can glue not two glasses, but more. But a three-layer triplex is still considered the best option- further addition of layers significantly increases the cost of the product, although, of course, the protective properties also increase. But by and large, it makes sense to use multilayer triplexes only where there is a serious threat to human life or to material and museum values.
But safety can be ensured not only by the use of triplex. There is also alternative way hardening and protection of glass in buildings glass structures - gluing window films on ordinary high-quality glass.
Professional window films (such as US Courtaulds Performance Films) when applied to glass avoid the risk of splintering. Glass reinforced with such a film successfully withstands even a shock blast wave - and if it is damaged, it will remain in the frame or fall out in a whole piece without scattering into sharp fragments.
The US Air Force is testing a new transparent material that could soon replace bulletproof glass in military vehicles. Aluminum oxynitride (ALON) is a transparent material similar in optical and structural characteristics to sapphire. It is very strong and much lighter than regular bulletproof glass.
The windshield, which consisted of three layers (ALON, glass, again ALON), during tests successfully withstood, for example, shelling with armor-piercing cartridges from an M-44 sniper rifle. Ordinary bulletproof glass must be several times thicker than an ALON windshield to withstand a similar load.
One day in 1903, the French chemist Edouard Benedict was preparing for another experiment in the laboratory - without looking, he reached out for a clean flask that was on a shelf in the closet and dropped it. Taking a broom and a shovel to remove the fragments, Eduard went to the cabinet and found with surprise that although the flask was broken, all its fragments remained in place, they were connected to each other by some kind of film. The chemist called a laboratory assistant - he was obliged to wash glassware after the experiments - and tried to find out what was in the flask. It turned out that this container was used a few days ago during experiments with cellulose nitrate (nitrocellulose) - an alcohol solution of liquid plastic, a small amount of which, after the alcohol evaporated, remained on the walls of the flask and froze with a film. And since the plastic layer was thin and transparent enough, the laboratory assistant decided that the container was empty.
A couple of weeks after the story with the flask that did not shatter into fragments, Edward Benedict caught the eye of an article in the morning newspaper, which described the consequences of head-on collisions of a new type of transport in those years - cars. The windshield shattered into fragments, inflicting multiple cuts on drivers, depriving them of vision and normal appearance. The photographs of the victims made a painful impression on Benedict, and then he remembered the "unbreakable" flask. Rushing to the laboratory, the French chemist dedicated the next 24 hours of his life to creating unbreakable glass. He applied nitrocellulose to glass, dried a layer of plastic, and tossed the composite onto the stone floor—over and over and over again. So Edward Benedict invented the first triplex glass.
laminated glass
Glass formed by several layers of silicate or organic glass, connected by a special polymer film, is called triplex. Polyvinyl butyral (PVB) is commonly used as the glass bonding polymer. There are two main ways of production of triplex laminated glass - jellied and laminating (autoclave or vacuum).
Filled triplex technology. The sheets are cut to size, if necessary, they are given a curved shape (bending is performed). After thoroughly cleaning the glass surfaces, they are stacked on top of each other so that there is a gap (cavity) between them no more than 2 mm high - the distance is fixed using a special rubber strip. Combined sheets of glass are set at an angle to a horizontal surface, polyvinyl butyral is poured into the cavity between them, a rubber insert around the perimeter prevents it from flowing out. To achieve the uniformity of the polymer layer, the glasses are placed under a press. The final connection of glass sheets due to the curing of polyvinyl butyral takes place under ultraviolet radiation in a special chamber, inside which the temperature is maintained in the range from 25 to 30 ° C. After the formation of the triplex, a rubber band is removed from it and the edge is turned.
Autoclave lamination of triplex. After cutting glass sheets, processing edges and bending, they are cleaned of contamination. Upon completion of the preparation of float glass sheets, a PVB film is placed between them, the formed “sandwich” is placed in a plastic shell - air is completely removed from the bag in a vacuum installation. The final connection of the “sandwich” layers takes place in an autoclave, under a pressure of 12.5 bar and a temperature of 150 ° C.
Vacuum lamination of triplex. Compared to autoclave technology, vacuum triplexing is performed at lower pressure and temperature. The sequence of working operations they have is similar: cutting glass, giving a curved shape in a bending furnace, turning edges, thoroughly cleaning and degreasing surfaces. When forming a “sandwich”, an ethylene vinyl acetate (EVA) or PVB film is placed between the glasses, then they are placed in a vacuum machine, previously placed in a plastic bag. The soldering of glass sheets takes place in this installation: air is pumped out; "sandwich" is heated to a maximum of 130 ° C, the film polymerizes; the triplex is cooled to 55°C. Polymerization is carried out in a rarefied atmosphere (-0.95 bar), when the temperature drops to 55°C, the pressure in the chamber equalizes to atmospheric pressure and, as soon as the temperature of the laminated glass reaches 45°C, the formation of the triplex is completed.
Laminated glass, created by poured technology, is stronger, but less transparent than laminated triplex.
Glass sandwiches made using one of the triplex technologies are used to create windshields cars, they are necessary for glazing high-rise buildings, in the construction of partitions inside offices and residential buildings. Triplex is popular with designers - products from it are an integral element of modern style.
But, despite the absence of fragments when hitting a multi-layer "sandwich" of silicate glass and polymer, it will not stop the bullet. But the triplex glass discussed below will do this quite successfully.
Armored glass - history of creation
In 1928, German chemists create a new material that immediately interested aircraft designers - plexiglass. In 1935, the head of the Research Institute "Plastmass" Sergei Ushakov managed to get a sample of "flexible glass" in Germany, Soviet scientists began to study it and develop technology. serial production. A year later, the production of organic glass from polymethyl methacrylate began at the K-4 plant in Leningrad. At the same time, experiments were begun aimed at creating armored glass.
Tempered glass, created in 1929 by the French company SSG, was produced in the USSR in the mid-30s under the name "stalinite". The hardening technology was as follows - sheets of the most common silicate glass were heated to temperatures in the range from 600 to 720 ° C, i.e. above the glass softening temperature. Then the glass sheet was subjected to rapid cooling - cold air flows in a few minutes lowered its temperature to 350-450 ° C. Thanks to tempering, the glass received high strength properties: impact resistance increased by 5-10 times; bending strength - not less than twice; heat resistance - three to four times.
However, despite its high strength, "stalinite" was not suitable for bending to form an aircraft cockpit canopy - hardening did not allow it to bend. In addition, tempered glass contains a significant number of internal stress zones, a light blow to them led to the complete destruction of the entire sheet. "Stalinite" cannot be cut, processed and drilled. Then the Soviet designers decided to combine plastic plexiglass and "stalinite", turning their shortcomings into dignity. The pre-molded aircraft canopy was covered with small tiles of tempered glass, with polyvinyl butyral as the adhesive. 
The entry of the former Soviet republics into capitalism in the early 1990s sharply increased the demand for armored glass protection for vehicles of collectors and currency exchange offices. At the same time, there was a need for "transparent armor" for cars businessmen. Since the production of real armored glass was expensive, as well as the final product, a number of companies launched the production of imitation armored glass - it was a triplex of rather mediocre quality, the PVB film polymerization was carried out in an accelerated mode, using ultraviolet irradiation. The finished product was able to withstand a pistol bullet from a distance of 5 meters, i.e. corresponded only to the 2nd class of protection (there are six in total). massive armored glass of this type did not withstand temperature fluctuations of more than +20 and below -22 ° C - already after six months the layers of the triplex partially stratified, their already low transparency was seriously reduced.
transparent armor
Modern bulletproof glass, also called transparent armor, is a multilayer composite formed by sheets of silicate glass, plexiglass, polyurethane, and polycarbonate. Also, the composition of the armored triplex may include quartz and ceramic glass, synthetic sapphire.
European armored glass manufacturers mainly produce triplex, consisting of several “raw” float glasses and polycarbonate. By the way, non-tempered glass among companies producing transparent armor is called “raw” - it is “raw” glass that is used in triplex with polycarbonate.
A polycarbonate sheet in such laminated glass is installed on the side facing the inside of the protected room. The task of plastic is to dampen vibrations caused by the shock wave when a bullet collides with armored glass in order to avoid the formation of new fragments in sheets of "raw" glass. If there is no polycarbonate in the composition of the triplex, then the shock wave moving in front of the bullet will break the glass even before it actually comes into contact with them and the bullet will pass through such a “sandwich” without hindrance. The disadvantages of armored glass with a polycarbonate insert (as well as with any polymer in the composition of the triplex): a significant weight of the composite, especially in classes 5-6a (reaches 210 kg per m 2); low resistance of plastic to abrasive wear; exfoliation of polycarbonate over time due to temperature changes.
quartz glass. It is produced from silicon oxide (silica) of natural origin (quartz sand, rock crystal, vein quartz) or artificially synthesized silicon dioxide. It has high heat resistance and light transmission, its strength is higher than that of silicate glass (50 N/mm 2 versus 9.81 N/mm 2).
ceramic glass. It is made of aluminum oxynitride, developed in the USA for the needs of the army, the patented name is ALON. The density of this transparent material is higher than that of quartz glass (3.69 g / cm 3 versus 2.21 g / cm 3), the strength characteristics are also high (Young's modulus is 334 GPa, the average bending stress limit is 380 MPa, which is practically 7-9 times higher than similar indicators of silicon oxide glasses).
Artificial sapphire (leucosapphire). It is a monocrystal made of aluminum oxide, as part of armored glass it gives the triplex the maximum strength properties possible. Some of its characteristics: density - 3.97 g / cm 3; average bending stress limit - 742 MPa; Young's modulus - 344 GPa. The disadvantage of leucosapphire lies in its significant cost due to high production energy costs, the need for complex machining and polishing.
Chemically strengthened glass. "Raw" silicate glass is immersed in a bath with an aqueous solution of hydrofluoric (hydrofluoric) acid. After chemical hardening, the glass becomes 3-6 times stronger, its impact strength increases six-fold. The disadvantage is that the strength characteristics of toughened glass are lower than those of thermally hardened glass.
Armored glass frame
The use of armored triplex in glazing does not mean that the opening blocked by it will be bulletproof - a frame of a special design is required. It is created mainly from metal profiles, most often aluminum. In the grooves located along the junction line of the triplex and the frame profile, steel linings are installed that protect the most weakness in an armored window structure from impact or contact with a bullet. 
Protective armor plates can also be installed outside frame structure, however, this will reduce the aesthetic characteristics of the window. To achieve the maximum level of protection, frames can be made entirely of steel profiles (linings are not needed in this case), but they will become very bulky and costly.
The weight of an armored window often exceeds 300 kg per m 2, not every building and construction material is able to withstand it. Therefore, the installation of an armored window structure is only permissible for reinforced concrete and brick walls. Opening the sash of an armored window is not easy due to its high weight; servo drives are used for this purpose.