City of the future. Carbon technology will revolutionize the construction market. What is carbon? What is carbon fiber doing

True, greatness is short-lived. Reinforced concrete, the most popular construction material XX century, alas, has short term service and 5 thousand years, like the pyramids of Giza, will definitely not survive. However, there is a way to extend the life of such structures. Moscow scientists have come up with durable "clothes" for reinforced concrete. Now this is the latest peep in architectural fashion. And not only.

Despite the fact that the time of Robin Hood has long passed, there are still quite a few fans of the wooden bow all over the world. But professional athletes choose modern technologies. For example, this bow is two times lighter than its wooden counterpart, the initial arrow speed is 105 meters per second, and the aiming range is 100 meters. It received these unique characteristics thanks to the material from which it is made - carbon fiber.

Carbon fiber or carbon fiber - this material is well known not only among sportsmen-archers and hunters. Anyone who has ever skied modern downhill skis has had carbon in their hands, because it is what ski poles are made of. Car enthusiasts dream of a carbon fiber hood or bumper, cyclists are increasingly opting for a carbon frame over aluminum. Even for ordinary household items, such as a computer keyboard or mouse, where super-properties are useless, the design is made “carbon-like”. However, there are entire industries where it is impossible to do without the super-properties of this material. For example, the aviation industry.

“Here you see an element of the aircraft wing, which is completely made of carbon materials according to new technology vacuum infusion. The main difference from the traditional aluminum wing is that this product is made completely integral without the use of any fasteners and additional assembly, ”says Alexey Ulyanov, Deputy Head of the Technology Department of CJSC Aerocomposite.

- How much does a similar part made of aluminum weigh?

- About 200 kilograms.

- This one is about 50 kilograms.

Despite the relative lightness, this fragment of the wing can withstand a load of almost 2,000 tons. In addition, an aircraft with such lightweight wings is able to soar in the air like a glider, so the engines work less, and this saves about 40 percent of fuel in flight, which means passengers' money.

“The advantage of carbon materials is that the designer can create the properties of the final product at his own discretion by assembling various components, so special materials are used here, designed for aircraft construction, for which temperature differences on the ground and in the air do not play any role,” explains Alexey Ulyanov.

carbon fabric- this is what this amazing material looks like. Please note that the future element of the aircraft wing is cut out of it, like a sleeve for some large suit. True, such a sleeve will have much more layers. For example, in this detail there are eighty-two.

How does a seemingly ordinary fabric turn into such a strong structure that can withstand multi-ton loads and such shocks? It's all about infusion technology. The cut and shaped fabric is placed in a vacuum module and then sent to a large oven. There, through special nozzles, another important component is supplied - resin, which binds all layers of the fabric together into one monolith. World leaders in the aviation industry, such as Boeing and Airbus, also use carbon fiber in their aircraft, but the technology developed in the Moscow laboratory of the Aerocomposite company is too tough for them. And in a year or two, Russia may not have any competitors in this area at all.

“We are completing the construction of two serial plants. One plant will manufacture the main power elements, wing boxes, exactly according to the technology that you see here. We are launching it in two months, the start of trial operation and the first experimental wing of the UAC and Aerocomposite will be issued in the middle next year. The second plant in the city of Kazan, which will make elements of mechanization and elevators. This is a plant that we are building together with our Austrian partners, Fischer. It will work both for Russian programs and for extensive export programs commissioned by Fischer,” said Anatoly Gaidansky, President of CJSC "Aerocomposite".

The only thing that Russian manufacturers lose in this carbon field is the quality of the carbon fiber itself, so aircraft manufacturers still have to use imported raw materials. However, soon everything will change. in the capital Technopark "Moscow" A whole team of scientists, engineers and testers is working on the development and creation of competitive carbon fabrics. The Moscow government has long understood that such innovations are the future, and have created the most comfortable working conditions for scientists.

“These are the latest samples of carbon fiber, they are four times stronger than steel, now I will prove it to you on a tensile testing machine. To do this, we fix the sample in the terminals and perform a test. Well, our sample withstood two tons, ”shows Anton Evdokimov, test laboratory engineer.

- What can create such a load?

- Similar loads can be created, for example, by two SUVs pulling this sample in different directions in first gear.

- It turns out that steel would not even withstand such a load?

- Of course not. She would have withstood four times less load, comparable somewhere with 500-700 kg, no more.

The most surprising thing is that this material, which is the most durable in terms of tearing, is made from a liquid. More precisely, from polyacrylonitrile.

Polyacrylonitrile fiber is made by extrusion. Simply put, the polymer is forced through a special die. In this nozzle, which looks completely homogeneous, in fact, there are hundreds of tiny holes with a diameter of only seventy microns, this is the average thickness of a human hair. As soon as it is lowered into the water and pressure is applied, looking closer, you can see thin whitish threads coming out of the spinneret in a continuous stream.

Passing through these hot baths with a special solution, the polymer fiber is thinned by about six times, from seventy microns to twelve. But due to the fact that the molecules in them line up in a certain way, this thread only becomes stronger. As a result, after numerous operations with polyacrylonitrile, an amazing metamorphosis occurs, and the liquid polymer becomes a strong fiber.

“This is not the final product, but only the raw material for carbon fiber production. Before getting carbon fiber, this polyacrylonitrile fiber must go through a process of high-temperature processing, as well as oxidation, graphitization, and carbonization, ”explains Elina Bilevskaya, representative of the Composite company.

Having received the next experimental batch of raw materials, the researchers conduct a thorough analysis of the manufactured material, then adjust the equipment settings and start the process over again. As they say, there is no limit to perfection.

“Our task is to obtain a more environmentally friendly fiber and reduce the cost of its production technology. Which, in fact, we succeed. Over the past year, we have developed approximately one hundred prototypes, which were subsequently transferred for processing into carbon fiber. We continuously conduct research into the formation of our fiber, as well as directly physical mechanical properties fiber obtained,” says Denis Fokin, research engineer.

Several of the most successful developments that came out of the walls of this laboratory in the Moscow technopark are already being successfully used in construction. For example, carbon fiber added to mortars such as gas and foam concrete, significantly increasing their technical characteristics. And in Chelyabinsk, the production of special carbon fiber tapes, which are used in the repair and strengthening of reinforced concrete structures, has been launched not on pilot, but in mass production. But is this technology as good in practice as in words? Now we will find out.

Let's do a demonstrative experiment. Imagine that these are two road bridges. In fact, this is the most ordinary wooden ruler of 30 centimeters. And next to it is also a wooden ruler, but on the one hand it is reinforced with carbon fiber. So let's start the experiment. To begin with, we will test our wooden bridge. It breaks on the third brick. Now let's check the ruler with carbon fiber. One brick, two, three, four - the ruler did not break, the bridge supports broke. Now I am convinced that the carbon fiber reinforced construction is much stronger.

Typical Moscow high-rise building. The house appears to be in good condition, and there are no signs of serious damage in its external appearance. However, they are already happening. Cracks appeared on the supporting structures in the basement of the house. While not big, but already very dangerous. If moisture gets inside, the metal reinforcement will rust, the concrete itself will begin to expand, corrode, and the ceiling may collapse.

“So that these cracks do not appear again, and this one does not open even more, we strengthen it. We are currently working on a similar site,” engineer Aleksey shows.

Here's how you can actually save anyone reinforced concrete structure from destruction and harmful effects external environment. Here in the basement of the house, in fact, the same technological process for creating carbon fiber is performed, which we saw in the production of aircraft parts. Only here the bonding resin is applied directly to the concrete. A carbon fiber tape of the desired width is rolled onto the treated surface and covered with another layer of epoxy on top. After a few hours, when the resin hardens, all cracks on the surface of the reinforced concrete floor will already be reliably protected by a layer of carbon fiber three millimeters thick.

“The obvious advantage of this technology is that a team of three people completed this section of the overlap in four hours. If the strengthening was done by classical methods, for example, using metal frames, it would take about three days, and five years later, in this damp basement, the metal would begin to corrode again, we would have to go back and redo it, ”explains the builder Alexey.

The range of application of this technology in construction is huge. Repair of reinforced concrete floors, strengthening of the supports of numerous bridges and flyovers. Since carbon fiber is not afraid of the aquatic environment, it can be used in the construction and technological maintenance of dams and underground utilities. However, not many construction companies are ready to widely use this material. The thing is that neither GOSTs nor SNiPs have yet been fully developed for the use of carbon fiber in Russia. Even in specialized construction universities, students are taught on traditional materials - wood, brick, reinforced concrete. As soon as this unfortunate gap is eliminated in the education and standardization system, many architectural creations of the past will finally have a solid, carbon chance for a second youth.

What is carbon?

Carbon is a technical fabric consisting of thousands of intertwined carbon fibers that form the same fabric. Carbon is available in a wide variety of weaves depending on the intended use and is just one part of the multi-part construction materials known to everyone as composite materials. Composites are made from components that combine the qualities of different materials, and the goal is to lack rigidity or to obtain strength. In the case of carbon fiber, fiberglass, Kevlar or other similar fabrics, the composite material in question is called FRP (Fiber Reinforced Polymer). In the production of such a polymer, the fabric is used in order to "reinforce" the structural rigidity of the resinous underlayer. The resin provides strength to the composite, while the carbon adds structural integrity to an otherwise brittle plastic.

How is carbon made?

Carbon (carbon fiber), as its name implies, is a fabric consisting only of coal and not having other elements in its composition. But to start production simply from carbon fiber and from the creation of a fabric with weaves of fibers would be a real, but elusive, feat. Instead of using carbon fiber as a raw material, textile factories are starting with plastics with more complex molecular composition, where the thread thickness is less than the thickness of a human hair. Then it is required to perform a number of specific actions, ranging from heat treatment to chemical treatment. The final result of these complex processes is the refinement of the composition of polymer materials to its most empirical form - the form of pure carbon.

Carbon fiber is often measured and sold based on several criteria, such as the type of weave, absolute values ​​(a measure of the strength of a single fiber) and the weight of the fabric. All measurements are in ounces per square yard, plus the number of fibers (usually in the range of 3,000 to 12,000 fibers).

What are the types of weave?

Unidirectional weaving:

Unidirectional weaving means that all of the carbon strands (fibers) are directed in the same direction. Weaving in this style is not visible to the naked eye. Since there is no weaving as such, the strands of the fiber must somehow be held together. And in this case, it is necessary to pull another thread diagonally or perpendicularly so that the fabric remains smooth and uniform (and this weaving element is not structural). As a result of the stiffness of the fabric in only one direction, this type of weave is rarely used in motorsports where the load can go in any direction.

Bidirectional weaving fibers:

Bidirectional carbon fiber is the basic and most common weave type. The strands are intertwined with each other at the required angle, due to which the fabric receives a “checkerboard” structure, where the threads of the fabric are laid sideways and vertically. In this case, all fibers are directed in such a way that the load can be applied in any direction, while the composite material must retain its strength.

Weaving diagonally in two through two threads

Weaving diagonally in two through two strands is the most common type of carbon weave, which is widely used in motorsports. This weave is a little more complicated than bidirectional fiber, as two strands pass over the other two strands, either one over two or two over one. As a result of this interlacing of threads, a herringbone pattern is created on the fabric. Due to the fact that weaving two by two threads diagonally goes with both vertical and horizontal threads (warp and weft), the fabric becomes very flexible and can take various complex shapes. When working with this type of carbon weave, there is no need to perform such work as "bunching", "stretching" or cutting.

Weaving diagonally in four through four threads

Similar to weaving diagonally in two through two threads, namely four through four threads, this type refers to a double-sided diagonal weave, where one bundle includes four threads. As a result, the fabric is not as dense as weaving in two through two strands, but in the case of curved surfaces, a better coverage ratio is achieved, since there is more distance between the actual points of weaving "above and under", which is more efficient, since in this case less amount of hard seams. This makes it easy to carbonize curved die-casts.

Rubberized weave

Rubberized carbon fabric is a very specific way of making fabric that is much less common compared to all the types of weave we are discussing. The rubberized weave of the fibers means that each strand consists of 3,000 to 12,000 strands, with each strand laid out tightly in a row, one after the other, forming the thinnest carbon tape. Standard strands are connected together with several layers of carbon threads. Rubberized fabric can be identified by the presence of wide open areas. Staggered bi-directional carbon fiber with a rubberized fabric structure creates one-inch squares.

Since, due to the large size of these areas of weaving, the fabric loses its density, the points of weaving "above and below" are at a great distance from each other. Thus, the cross points of the threads are at a distance from each other, the frequency of direction changes is greatly reduced, and the fabric can adhere much more closely to the surface.

As described on the website, an English supplier of materials and polymers, “rubberized fabrics are gaining popularity in the high-tech composites industry due to their incredibly flat profile, which virtually eliminates the so-called “copy effect” and the effect of showing a certain texture on surfaces that require perfect smoothness. (for example, airplane wings).

Since the fabric layer is much thinner, it is possible to layer a layer on top of another layer and thereby achieve the required strength characteristics. This type of carbon is often used in areas where aerodynamic performance prevails over strength. Rubberized fabric has appearance, different from the standard, which immediately causes either love or hatred.

Various resins

Carbon fabric is only one component of the composite material that is referred to when talking about motorsport and track racing. Another important component is the resin, which enriches the fabric itself and gives it actual stiffness. Resins are used in various polymer "dishes". The two most commonly used materials are epoxy and polyester resin. Anyone who has ever worked with fiberglass just to fix their surfboard or car part knows that this resin can be a real pain in the ass. Volatile organic compounds (VOCs) are the fumes that are the hallmark of many types of resins, although there are some freely available that do not use these chemicals that can damage your brain. Almost everyone knows the backlash of working with resin when the right products are used. personal protection are not used, but hypersensitivity and allergies develop. And these cases have become so commonplace that we often hear jokes about people who are not able to be in the room in which the resin is being worked on.

Epoxy resin

Epoxy resin is the most common multi-purpose structural resin. As with almost all types of resins, this is a two part solution of resin and catalyst. The reaction time varies, but is directly dependent on environmental conditions. Shelf life ( work time), generally between five and thirty minutes. In general, thermal exposure always speeds up the “ripening” process, but the entire setting process usually takes, neither more nor less, but the whole day (24 hours) - if the mixture is not affected in any way. Compared to polyester resin, epoxy resin is more durable, but requires patience when working with it.

polyester resin

Polyester resin is a cheaper alternative to epoxy, with a faster setting time. It is mainly used in situations where structural integrity is less important than aesthetics, according to easycomposites.co.uk: appearance, UV resistance and price are the top priority.”

Prepregs (pre-impregnated fabrics)

Some carbon fabrics can be produced as pre-impregnated with a resin solution, where heat treatment acts as a catalyst. Prepregs are used in many composite industries because their application does not require any complex processes, and in direct work, mess is minimized: you just need to mix the resins and lay the wet fabric in layers.

Prepregs are also the material of choice in industries where weight plays an important role. Such areas include aviation, where most of the mass of parts is in resin, and not in fabric. Given the minimum required to thoroughly and evenly impregnate the fabric with resin, prepreg can be used to create the strongest and lightest construction.

Manufacturing processes

wet calculations

Traditionally, small parts are laid out while wet, along with a concave shape, then cork is created (but that's another story). The dry cloth is placed inside the mold. The resin is applied with a paintbrush until the fabric is completely soaked or saturated with it. The next layers of fabric are placed on top of the first layer, while respecting the direction of weaving: 45 degrees for bidirectional weaving and 90 degrees for twill fabric. If the layers of fabric do not match in direction, the output part will lose its rigidity in one axis, and will be too strengthened in the other.

Having thus laid as many layers of fabric as necessary to obtain the desired thickness, the excess resin is scraped off with a scraper as if you were removing water from your windshield. The part is then processed in a low pressure vacuum bag. As a result, the resin fills all the remaining air voids, thereby displacing the smallest air bubbles, and the excess resin goes away.

In some cases, all these manipulations are performed in reverse order. The dry fabric is vacuum bagged in the mould, and only then the resin is applied. Thanks to this method, waste and dirt are absent. The final step is heat treatment. All parts are "baked" inside a pressure oven, the so-called autoclave, and the resin is completely set.

Although most do not have access to specialized equipment, procedures such as vacuum bagging and autoclaving are optional for workpieces that do not need to be structured to specific requirements.

Applications

Carbon has gained momentum in the automotive industry. In the aftermarket, carbon is the material most commonly used for coating parts. Body parts, interior trim parts - and all this is made of carbon fiber, which gives the car a high-class appearance. Functionally, carbon fiber parts are used in almost all areas - from the automotive industry, continuing to shipbuilding and ending with aviation.

Carbon is being used in the construction of racing seats, driveshafts, safety features such as helmets and restraints (head restraints), and even compound spring technology is beginning to use carbon for suspension systems.

Carbon is not a panacea

The appeal of carbon is so strong to many that today there is a tendency to misuse this material in applications where best solution still is a metal alloy. Carbon, and especially resin, does not do well in high temperature environments, heat shields, exhaust system components, or any other engine parts. When carbon is chosen as the starting material in these cases, the operating conditions must be evaluated very carefully. There are heat-resistant resins, but their scope is still limited.

impact resistance

Carbon can boast that this (already catchy) phrase fully corresponds to its essence: the lighter the aluminum, the stronger the steel. While this is indeed true, it is important to understand that we are talking about tensile strength and not toughness or stiffness. From an engineering point of view, "toughness" is a technical term that refers to wear resistance, since this composite is reinforced with a layered polyester, the impact resistance of which is low. And even a weak point impact can lead to peeling and, in the end, to the failure of the material. For this reason, carbon cannot be used to make wear resistant or reusable fifth wheel baseplates of satisfactory quality, to manufacture various suspension components, or any other parts that operate under maximum load conditions.

Conductivity

Carbon is a conductive material! Pure carbon is extremely efficient at transferring heat by itself. For example, the hood of a car made of carbon can heat up very quickly in the sun to several hundred degrees. UV rays can damage the composite, give it a yellow tint or cause the resin to crack, so warping is a common defect. In aviation, many carbon fiber parts are finished in glossy white paint because the heat generated from exposure to UV rays can deform the frame and have a negative impact on aerodynamic performance. In addition, UV rays can somehow change the structure of the aircraft.

Carbon is also an electrically conductive material. You may be confused about how a plastic-based composite can suddenly become electrically conductive, but a pure carbon fabric "blazes" a peculiar path for electricity, even if the carbon is enriched with an insulating polymer. When choosing carbon as a surface for electronics or as a cooling fan shroud, make sure there is a ground connection that should not "go through" the carbon. An anecdote from life: we once witnessed a fire that almost started in the engine of the owner of a Geiser Trophy truck, because he simply did not believe that carbon is a conductive material, and the fire of resin is not a joke to you.

Working with carbon

If fiberglass has ever come into contact with your skin, then you know how irritating these particles are, invisible to the eye. And carbon is much worse! Avoid touching the torn edges of carbon fiber and chopped fiber with bare hands.

When ordering carbon fabric, it's important to make sure it comes in rolls like wrapping paper. Fold-packed carbon will have creases and, as a result, the structural integrity of its crimped fibers will be compromised. Follow these instructions when working with the material, and keep the fabric clean to avoid dust and greasy fingerprints, while ensuring the most correct installation. It is necessary to mix the resin in small containers, which is the norm. Be careful, the resin must not be mixed in wax-coated containers. Wax reacts with resins, causing the resin to harden. Resin solidification is an exothermic reaction, which means heat is injected as a by-product as a result of chemical reaction. When mixing large amounts of resin, make sure that excess resin is kept out of the combustible material storage area, otherwise there is a high risk of fire.

Conclusion

The amount of basic knowledge that we have not even touched on in this article is simply huge. But we hope this general review helped you better understand what carbon is. It is an extremely versatile and durable material if handled with care. But if it is used incorrectly, it becomes a real thorn in the eye. Creating simple parts at home is not difficult, but be prepared to spend a little more time working with it compared to fiberglass. Consider everything in your project - goals, budget. And only then decide whether carbon is the right choice or you just want to add aesthetics to your car?

Data taken from the site: tourerv.ru

It is known that a solid indicator of tensile strength, relative to its own weight, which carbon fiber has, is a unique achievement of the material and opens up bright prospects for use in the national economy. The use of carbon in modern construction has not yet been widely used, although carbon is not difficult to buy at present. But simple and reliable methods of application promise to be long.

Carbon fiber

The first production of carbon fibers as a result of the pyrolysis of viscose fiber and the use for filaments was patented by Edison at the end of the 18th century.

Increased interest in fiber appeared in the 20th century as a result of the search for a material for composite components in the manufacture of rocket and aircraft engines.

In terms of its qualities: heat resistance and thermal insulation properties, as well as corrosion resistance, carbon fiber was not equal.

The characteristics of the first samples of polyacrylonitrile (PAN) fibers were not high, but the improvement of the technology made it possible to obtain hydrocarbon fibers with a carbon fiber strength of 2070 MPa and an elastic modulus of 480 GPa.

Today, carbon fiber or carbon fiber has a wide range of applications in construction:

• for external reinforcement system
• for the repair of load-bearing structures of warehouses and bridges, industrial and residential buildings.

The use of carbon fiber products provides an opportunity for construction activities, compared with existing ways reconstruction or reinforcement, quickly and efficiently.

But the story about the achievements of carbon would be incomplete if not to mention its use in the manufacture of aircraft parts.

The achievements of domestic aircraft manufacturers are healthy competition for Mitsubishi Heavy Industries, which manufactures Boeing 787 parts.

Production of products from polymeric material

Polymeric material - carbon is a fine-fiber thread ø from 5 to 15 microns, formed by carbon atoms and combined into microcrystals. It is the alignment during the orientation of the crystals that gives the threads good strength and stretch, slight specific gravity and coefficient of thermal expansion, chemical inertness.

The production processes for obtaining PAN fibers are associated with autoclave technology and subsequent impregnation for strengthening with resin. Carbon fiber is impregnated with plastic (prepreg) and impregnated with liquid plastic, reinforcing the fibers under pressure.

According to physical characteristics, carbon fiber is divided into types:

• high-strength carbon fibers (composition of 12000 continuous fibers)
• general-purpose carbonized carbon fibers (twisted thread of 2 or more fibers up to 100 mm long).

Carbon-fiber structures reinforced with material products reduce the weight of the structure by 30%, and chemical inertness allows the use of carbon fabrics as a filter when cleaning aggressive liquids and gases from impurities.

The production of carbon fiber is presented in this video.

Carbon fiber product range

carbon fabrics

The main product made of high-modulus carbon fiber is a carbon (carbon) fabric with a thickness of 1.6 - 5.0 mm, having a woven plain weave structure with a density of 520 to 560 g / m².

Carbon fabrics with a zero coefficient of linear expansion are highly resistant to deformation and corrosion.

The characteristics of standard carbon fabrics are:

The parameters of carbon fabrics are:

• web width 1000-2000mm
• carbon content 98.5%
• density 100-640 g/m2
• thickness 0.25-0.30 mm.

In addition to carbon fabrics, the main products of high-modulus fiber are ribbons and cords.

Distinguish the following types weaving of carbon fiber fabrics, which to a certain extent affect the mobility of the product:

• linen weave created by interlacing each warp thread with a 1/1 weft thread, creating better fabric strength and movement
• satin weave in which one weft thread interweaves 4-5 warp threads, reducing the possibility of strong bending of the fabric
• twill a weave in which the same number of warp threads are covered by the same number of weft threads.

An example of the possibility of a twill weave is multicolored carbon fabric. Multi-colored carbon fabric is successfully used to create Kevlar clothing and things that are hygroscopic and breathable. Kevlar made of technical threads with different density and structure has already entered the everyday life of the auto and military industry, displacing fiberglass and steel.

The advantages of carbon fiber are clearly expressed in products made of carbonized carbon fiber.

carbon fiber products

The range of products made of carbonized fiber is more expanded and is represented by:

• carbon cloth carbonized RK-300 (glass cloth substitute)
• fabric with one-sided aluminum coating RK-300AF (improved properties due to the thermal screen allow the use of carbon fiber as a heat-insulating wrapping material)
• carbon construction fabrics 1k, 3k, 6k, 12k, 24k, 48k
• carbonized bands and cords.

A woven canvas made of carbon or carbonized fiber performs excellent reinforcement functions, regardless of the type of filler.

In addition, EMP-absorbing screens, thermocouples and electrodes, as well as radio engineering products are made using carbonized fibers.

production of pools with carbon reinforcement

In the production of pools with carbon reinforcement, the technology includes the stage of adding carbon reinforcement, wood balsa and foamed rubber to the ceramic layer. The basis for the creation of a double frame of the pool bowl with carbon reinforcement was the constructed load diagrams and allowable stresses on the material.

We conclude that the growing popularity of the use of carbon fiber in the future will be able to displace reinforcing materials from the market.

CFRP is a composite multilayer material, which is a web of carbon fibers in a shell of thermosetting polymer (usually epoxy) resins, Carbon-fiber-reinforced polymer.

The international name Carbon is carbon, from which carbon fibers are obtained.

But at present, carbon fibers include everything in which the carrier base is carbon fibers, but the binder may be different. Carbon fiber and carbon fiber combined into one term, bringing confusion to the minds of consumers. That is, carbon or carbon fiber is one and the same.

This is an innovative material, the high cost of which is due to the labor-intensive technological process and a large share of manual labor at the same time. With the improvement and automation of manufacturing processes, the price of carbon will decrease. For example: the cost of 1 kg of steel is less than 1 dollar, 1 kg of European-made carbon fiber costs about 20 dollars. Reducing the cost is possible only through the full automation of the process.

Application of carbon

Carbon fiber was originally developed for the sports car industry and space technology, but due to its excellent performance properties, such as low weight and high strength, it has become widespread in other industries:

• in the aircraft industry
• for sports equipment: clubs, helmets, bicycles.
• fishing rods,
• medical technology, etc.

The flexibility of the carbon fabric, the possibility of its convenient cutting and cutting, and subsequent impregnation with epoxy resin make it possible to form carbon products of any shape and size, including independently. The resulting blanks can be sanded, polished, painted and flexo printed.

Technical characteristics and properties of carbon

The popularity of CFRP is due to its unique performance characteristics, which are obtained by combining materials that are completely different in their properties in one composite - a carbon cloth as a carrier base and as a binder.

The reinforcing element common to all types of carbon fiber is carbon fibers 0.005-0.010 mm thick, which work great in tension, but have low bending strength, that is, they are anisotropic, strong only in one direction, so their use is justified only in the form of a web.

Additionally, reinforcement can be carried out with rubber, which gives a gray tint to carbon.

Carbon or carbon fiber is characterized by high strength, wear resistance, rigidity and low weight compared to steel. Its density is from 1450 kg/m³ to 2000 kg/m³. The technical characteristics of carbon fiber can be viewed in density, melting point and strength characteristics.

Another element used for reinforcement along with carbon filaments is. These are the same yellow threads that can be seen in some varieties of carbon fiber. Some unscrupulous manufacturers pass off colored fiberglass, dyed fibers of viscose, polyethylene as Kevlar, the adhesion of which with resins is much worse than that of carbon fiber, and the tensile strength is several times less.

Kevlar is an American brand name for a class of aramid polymers related to polyamides, lavsan. This name has already become a household name for all fibers of this class. Reinforcement increases the resistance to bending loads, so it is widely used in combination with carbon fiber.

How carbon fiber is made

Fibers, consisting of the finest carbon filaments, are obtained by heat treatment in air, that is, by oxidation, of polymer or organic threads (polyacrylonitrile, phenolic, lignin, viscose) at a temperature of 250 ° C for 24 hours, that is, practically by their charring. This is what a carbon filament looks like under a microscope after charring.

After oxidation, carbonization takes place - heating the fiber in nitrogen or argon at temperatures from 800 to 1500 ° C to build structures similar to graphite molecules.

Then graphitization (saturation with carbon) is carried out in the same medium at a temperature of 1300-3000 °C. This process can be repeated several times, cleaning the graphite fiber from nitrogen, increasing the concentration of carbon and making it stronger. The higher the temperature, the stronger the fiber. By this treatment, the carbon concentration in the fiber is increased to 99%.

Types of carbon fibres. canvas

The fibers can be short, cut, theircalled"stapled", and there may be continuous threads on bobbins.These can be tows, yarn, roving, which are then used to make woven and nonwoven fabric and ribbons. Sometimes the fibers are laid in a polymer matrix without entanglement (UD).

Since fibers work great in tension but are poor in bending and compression, the ideal use for carbon fiber is to use it as a Carbon Fabric.

It is obtained by various types of weaving: herringbone, matting, etc., which have the international names Plain, Twill, Satin. Sometimes the fibers are simply intercepted across with large stitches before being filled with resin. Right for CFRP on technical specifications fiber and weave is very important for obtaining high-quality carbon.

As a carrier base, they are most often used, in which the fabric is laid in layers, with a change in the direction of weaving, to evenly distribute the mechanical properties of oriented fibers. Most often, 1 mm of carbon fiber sheet thickness contains 3-4 layers.

Advantages and disadvantages of carbon fiber

The higher price of carbon compared to fiberglass and fiberglass is due to more complex, energy-intensive multi-stage technology, expensive resins and more expensive equipment (autoclave). But strength and elasticity are also obtained higher along with many other undeniable advantages:

• 40% lighter than steel, 20% lighter than aluminum (1.7 g/cm3 - 2.8 g/cm3 - 7.8 g/cm3),
• carbon and kevlar carbon is a little heavier than carbon and rubber, but much stronger, and when hit it cracks, crumbles, but does not crumble into fragments,
• high temperature resistance: carbon retains its shape and properties up to a temperature of 2000 ○С.
• has good vibration damping properties and heat capacity,
• corrosion resistance,
• high tensile strength and high tensile strength,
• aesthetics and decoration.

But compared to metal and fiberglass parts, carbon parts have disadvantages:

• sensitivity to point impacts,
• complexity of restoration with chips and scratches,
• fading, fading under the influence of sunlight, varnished or enameled for protection,
• lengthy manufacturing process
• at the points of contact with the metal, metal corrosion begins, therefore, fiberglass inserts are fixed in such places,
• the complexity of recycling and reuse.

How carbon is made

There are the following main methods of manufacturing products from carbon fiber.

1. Pressing or "wet" method

The canvas is laid out in a mold and impregnated with epoxy or polyester resin. Excess resin is removed either by vacuum forming or pressure. The product is removed after the polymerization of the resin. This process can take place either naturally or accelerated by heating. As a rule, as a result of such a process, sheet carbon fiber is obtained.

2. Molding

A product model (matrix) is made of gypsum, alabaster, polyurethane foam, on which a fabric impregnated with resin is laid out. When rolling with rollers, the composite is compacted and excess air is removed. Then, either accelerated polymerization and curing in an oven, or natural is carried out. This method is called "dry" and products from it are stronger and lighter than those made by the "wet" method. The surface of the product made by the "dry" method is ribbed (if it was not varnished).

This category also includes molding from sheet blanks - prepregs.

Resins, according to their ability to polymerize with increasing temperature, are divided into "cold" and "hot". The latter are used in prepreg technology, when semi-finished products are made in the form of several layers of carbon fiber coated with resin. Depending on the brand of resin, they can be stored for up to several weeks in an unpolymerized state, interleaved with polyethylene film and passed between rolls to remove air bubbles and excess resin. Sometimes prepregs are stored in refrigerators. Before molding the product, the workpiece is heated, and the resin again becomes liquid.

3. Winding

Thread, tape, fabric are wound on a cylindrical blank for the manufacture of carbon pipes. The resin is applied in layers with a brush or roller and dried, preferably in an oven.

In all cases, the application surface is lubricated with release agents for easy removal of the resulting product after curing.

Is it possible to make carbon fiber with your own hands

Products based on carbon fiber can be molded by yourself, which has long been successfully used in the repair of bicycles, sports equipment, and car tuning. The opportunity to experiment with fillers for the resin, with the degree of its transparency, provides a wide field for creativity for fans of car tuning with carbon. You can read more about the main methods for manufacturing carbon parts.

As follows from the technology described above, for molding it is necessary:

• matrix shape,
• carbon cloth,
• lubricant for the mold for easy removal of the finished workpiece,
• resin.

Where to get carbon fiber? Taiwan, China, Russia. But in Russia, this refers to "high-strength structural fabrics based on carbon fiber." If you find a way to the enterprise, then you are very lucky. Many companies offer "Do It Yourself" kits for car and motorcycle carbon fiber trim, including carbon fiber fragments and resin.

70% of the global carbon fabric market is produced by Taiwanese and Japanese major brands: Mitsubishi, TORAY, TOHO, CYTEC, Zoltec, etc.

In general terms, the process of making carbon fiber with your own hands looks like this:

1. The form is lubricated with an anti-adhesive.
2. After it dries, a thin layer of resin is applied, on which carbon fabric is rolled or pressed to release air bubbles.
3. Then another layer of impregnating resin is applied. It is possible to apply several layers of fabric and resin, depending on the required parameters of the product.
4. The resin can polymerize in air. This usually happens within 5 days. You can place the workpiece in a heating cabinet heated to a temperature of 140 - 180 ◦ C, which will significantly speed up the polymerization process.

Then the product is removed from the mold, sanded, polished, varnished, gelcoat or painted.

We hope you have found an exhaustive answer to the question "What is carbon"?

Irina Khimich, technical consultant

Among all kinds of plastics and composites developed by chemical technologists, a special place in the modern world is occupied by carbon (carbon fiber) - a material based on the finest carbon filaments. It is 75% lighter than iron and 30% lighter than aluminum, yet has four times the tensile strength of the best steel grades.
By themselves, carbon threads are quite fragile, so flexible and elastic panels are woven from them. When binder polymer compounds are added to them, carbon fiber plastics are obtained, which have made a real revolution in sports, technology and many other areas of human activity.

On the roads, in the sky and at sea

The most widely known application of carbon is in the automotive industry. At the beginning, its outstanding combination of strength and lightness attracted the attention of the designers of Formula 1 cars, which significantly reduced the weight of racing cars. John Bernard, an engineer at the British car manufacturer McLaren, first made body parts from carbon fiber in the early 1980s. This gave such a noticeable increase in speed that it immediately led the McLaren racing team to prizes.

However, the right to be the fastest is very expensive due to the fact that all carbon fiber parts are actually made by hand. Carbon fabric of special weaving is laid out in molds, then connected with polymer compounds. On the final stage it is processed at high temperature and pressure. Therefore, for a long time, carbon body elements were used only in supercars and premium models. And only recently the release of mass-produced models with carbon fiber parts available to a wide audience was announced. So, in the body structure of the new BMW i3, elements made of carbon fiber will be widely represented. And in new version hatchback Volkswagen Golf GTI VII thanks to the carbon-fiber hood and roof, it was possible to reduce the weight of the car by 200 kg at once!

Carbon-based materials are even more widely used in the aircraft industry, where they began to replace traditional aluminum and titanium. The aircraft designers working in the defense industry were the first to evaluate the prospects. For example, the latest Russian Su-47 and T-50 fighters use carbon-fiber wing and fuselage components.

Carbon fiber is also increasingly being used in passenger aircraft, where it can reduce fuel consumption and increase payload. Thus, in the Boeing 787 Dreamliner, at least 50% of the fuselage elements are made of carbon-based composite materials, due to which fuel consumption is reduced by 20%. For the same purpose, the largest passenger airliner, the Airbus A380, was equipped with wings that are 40% carbon fiber. And the fuselage of the modern Hawker 4000 business jet is almost entirely made of this material!

Carbon fiber is no less actively used in shipbuilding. The reason for the popularity is the same: a unique strength-to-weight ratio, vital in harsh sea conditions. In addition, shipbuilders value the impact and corrosion resistance of this material.

As usual, carbon fiber was the first to be used in the defense sector. Submarine hull elements are made of carbon composites, as they significantly reduce noise and have a stealth effect, making the ship “invisible” to enemy radars. And in the Swedish corvettes of the Visbi type, the hull and superstructures are made of carbon composites using stealth technology. A multi-layer material is used with a PVC base, which is covered with a special weave fabric made of carbon tows. Each such harness absorbs and scatters radio waves from radars, preventing the vessel from being detected.

For civilian ships, radar invisibility is not needed, but lightness, strength and the ability to manufacture parts of almost any configuration turned out to be very popular. Most often, carbon is used in the construction of sports and pleasure yachts, where speed characteristics are important.

Elements of the future ship are “molded” from carbon fiber canvases according to a computer model, like from plasticine. First, a full-size layout of the deck and hull is made from special modeling plastic. Then, according to these patterns, panels of carbon fabric, fastened with epoxy resins, are manually glued in layers. After drying, the finished body is sanded, painted and varnished.

However, there are more modern ways. For example, the Italian company Lanulfi has managed to automate the process almost completely. Large structural elements of the vessel using 3D modeling are broken into smaller, but perfectly matching parts. Based on a computer model, using a machine with program control, bases are made, which serve as matrices for gluing carbon fiber parts. This approach allows you to achieve maximum accuracy, which is very important for the driving performance of sports yachts.

Carbon for everyone

Carbon is beginning to be used more and more in construction. Adding carbon fibers to concrete makes it much more resistant to external influences. In fact, a heavy-duty monolith with a very dense surface is obtained. This technology is used in the construction of skyscrapers and dams, as well as in the construction of tunnels.

It is worth mentioning the materials for strengthening, repairing and restoring reinforced concrete surfaces - special canvases and carbon fabric plates (for example, Mapewrap or Carboplate). They allow you to completely restore the structure without resorting to expensive and not always possible refilling.

For large developers and private developers, such an innovation as the use of carbon in the plaster system of facade insulation is of particular interest.

Reference

“The addition of the smallest carbon fibers with a diameter of less than 15 microns to the reinforcing composition leads to a very important result - a multiple increase in the impact resistance of the facade,” says Roman Ryazantsev, project manager at CAPAROL, an expert in the field of protection and thermal insulation of building facades. “In particular, the carbon additive in the CAPATECT Carbon (Caparol) plaster system allows the facade to withstand impacts with energies up to 60 Joules without harm - this is ten times more than conventional plaster facades can withstand.”

If the cottage owner decides to use such a system for the exterior decoration of his home, he will not only reduce heating costs and provide a favorable microclimate in the premises, but also protect the walls from any mechanical influences. Large hail breaks vinyl siding and leaves dents in ordinary sandy plaster. A squally wind carrying debris and tree branches with it can also damage the façade. But on the finish with the addition of carbon fibers there will be no trace. Moreover, she is not afraid of such everyday influences as hitting a ball or a puck in children's games.

“Usually, to protect the basement of the facade from accidental damage, they use stone cladding, for example, porcelain stoneware,” notes Daniil Mazurov, head of the department wholesale sales Moscow construction and trading company PKK Interstroytekhnologii. – But to finish the basement of the residential complex, which is currently being built in the south of Moscow, we decided to try a plaster system with carbon fiber. In comparative tests, it showed very impressive results.”

Vadim Pashchenko, head of the WDVS department of the Moscow regional department of the CAPAROL company, names another valuable consequence of the use of reinforcing components with carbon fibers in the plaster system: the facade becomes resistant to temperature deformations. For architects and owners of private houses, this means complete freedom in self-expression - you can paint the walls of the house in any of the darkest and most saturated colors. With traditional cement-sand plaster, such experiments can end sadly. The dark surface of the wall heats up too quickly under the sun's rays, which leads to the formation of cracks on the outer protective and decorative layer. But for a facade system with carbon fibers, this problem does not exist.

Now all over Europe, private cottages and commercial buildings, schools and kindergartens, which have been helped to acquire expressive and rich colors, are beginning to appear standing out against the general background. As Russian private homeowners begin to experiment with facade colors, moving away from traditional pastel shades, this innovative technology is becoming in demand in our country as well.

Generation Next

It is now impossible to imagine any high-tech industry without carbon fiber. It is becoming more and more accessible to ordinary people. Now we can buy carbon fiber skis, snowboards, mountain boots, spinning rods and bicycles, helmets and other sports equipment.

But it is already being replaced by a new generation of materials - carbon nanotubes, which are ten times stronger than steel and have a host of other valuable properties.

Schematic representation of a nanotube

So, the Canadian clothing manufacturer Garrison Bespoke has developed a men's suit, which is made of fabric based on carbon nanotubes. Such fabric stops bullets up to .45 caliber and protects against stab wounds. It is also 50% lighter than Kevlar, a synthetic material used to make bulletproof vests. Such suits will certainly become fashionable among businessmen and politicians.

Among the most fantastic applications of carbon nanotubes is the space elevator, which will allow delivering cargo into orbit without expensive and dangerous rocket launches. Its basis should be a heavy-duty cable stretched from the surface of the planet to a space station located in geostationary orbit at an altitude of 35,000 km above the Earth.

This idea was proposed by the great Russian scientist Konstantin Tsiolkovsky in 1895. But until now, the project seemed unfeasible for technical reasons, because there were no known materials from which such a strong cable could be made. However, the discovery of carbon nanotubes in the early 1990s forced to reconsider the boundaries of the possible. A thread of millimeter thickness woven from carbon nanotubes is capable of withstanding a load of about 30 tons. This means that cheap and safe travel to orbit in the cabin of a space elevator is turning from a fantasy story into a practical task for engineers.