Carbon fiber (or carbon fiber) is made up of many fine strands (0.09mm diameter) of carbon that has the strength of alloy steel at a much lower weight (about the same as aluminum). These threads are woven into fiber; the result is a very durable fabric. The fibers can be arranged randomly, or they can be in the form of weaving.

The starting material for producing carbon fiber is polyacrylonitrile, a white substance with properties reminiscent of wool. It is heated several times in an environment of inert gases. At the first stage, at a temperature of +260°C, the structure of the substance is changed (at the molecular level), then at +700°C, carbon atoms are “forced to release” hydrogen. Gradually, over several heating times, it is brought to +3000°C - this process is called graphitization. As a result, there is more carbon and the bonds between its atoms are stronger. Simply put, carbon fiber can be considered carbon fiber that has been heated to the point of charring.

Carbon characteristics and application

One of the main positive qualities of carbon is its high strength, reaching 1500 kg/cubic meter. m. At the same time, the tensile strength reaches 1800 mPa. The temperature limit of this material is +2000°C. Carbon fiber threads only work well in tension, so making a rigid structure is very problematic. Carbon is quite fragile and crumbles on impact, so it is almost impossible to repair the part. With constant exposure to ultraviolet radiation, carbon fiber loses its original color. However, the positive properties outweigh the negatives; This is confirmed by the manufacture of brake discs and pads for sports cars, not to mention space technology.

One of the characteristics of carbon is its specific gravity (or fabric density), expressed in g/sq. m. This parameter depends on the thickness of the fiber, which can contain several thousand threads. For example, if the marking contains the designation 2K, then the fiber contains 2000 threads. The most durable carbon fiber is designated by the abbreviation UHM. In addition to density, an important characteristic is the method of weaving the threads (it is absent in the cheapest material).

When tuning vehicles, the types of weaving most often used are Twill, Satin, and Plain. The most common number of threads in a fiber is from 1 to 24K. The latter type of fabric is widely used in the manufacture of military equipment that experiences enormous stress.

Carbon (material)

Carbon fiber- a polymer composite material made of interwoven carbon filaments located in a matrix of polymer (for example, epoxy) resins.

The main component of carbon fiber is carbon filaments (essentially the same as, for example, the lead in a pencil). Such threads are very thin, they are very easy to break, but quite difficult to break. Fabrics are woven from these threads. They can have different weaving patterns (herringbone, matting, etc.). To give even greater strength, these fabrics made from carbon threads are laid in layers, each time changing the angle of the weaving direction. The layers are held together using epoxy resins. It is used for the manufacture of lightweight but durable parts, for example: cockpits and fairings in Formula 1, spinning rods, windsurfing masts, bumpers and sills on sports cars, helicopter rotors.

Carbon filaments are usually produced by heat treating chemical or natural organic fibers, which leaves primarily carbon atoms in the fiber material.

Temperature treatment consists of several stages.

The first of them is the oxidation of the original (polyacrylonitrile, viscose) fiber in air at a temperature of 250 °C for 24 hours.

As a result of oxidation, ladder structures are formed.

After oxidation, the carbonization stage follows - heating the fiber in nitrogen or argon at temperatures from 800 to 1500 °C. As a result of carbonization, graphite-like structures are formed.

The heat treatment process ends with graphitization at a temperature of 1600-3000°C, which also takes place in an inert environment. As a result of graphitization, the amount of carbon in the fiber is increased to 99%.

In addition to ordinary organic fibers (most often viscose and polyacrylonitrile), special fibers from phenolic resins, lignin, coal and petroleum tars can be used to produce carbon filaments.

In addition, carbon parts are stronger than fiberglass parts.

Carbon parts are much more expensive than similar fiberglass parts.

The “high cost” of carbon is caused, first of all, by more complex production technology and the higher cost of derived materials.

For example, for gluing layers, more expensive and high-quality resins are used than when working with fiberglass, and the production of parts requires more expensive equipment, for example, such as an autoclave.

The disadvantage of carbon is the fear of “pinpoint” impacts. For example, a carbon fiber hood can turn into a sieve after frequent exposure to small stones. Unlike metal or fiberglass parts, carbon parts cannot be restored to their original appearance. Therefore, after even minor damage, the entire part will have to be replaced entirely. In addition, carbon parts are susceptible to fading when exposed to sunlight.

Application

Carbon fiber racing car mirror housing

Used instead of metals in many products, from spaceship parts to fishing rods

• rocket and space technology
• aviation technology (aircraft manufacturing, helicopter manufacturing)
• shipbuilding (ships, sports shipbuilding)
• automotive industry (sports cars, motorcycles, tuning and finishing)
• science and research
• sports equipment (bicycles, roller skates, fishing rods)
• Medical equipment
• fishing tackle (rods)
• telephone and laptop manufacturing (case finishing)

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Among all kinds of plastics and composites developed by chemical technologists, carbon (carbon fiber) - a material based on the finest carbon threads - occupies a special place in the modern world. It is 75% lighter than iron and 30% lighter than aluminum, and yet has a tensile strength four times higher than the best grades of steel.
The carbon threads themselves are quite fragile, so flexible and elastic panels are woven from them. By adding binder polymer compositions 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 on the sea

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

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 a special weave is laid out in casting molds, then joined with polymer compounds. At 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 serial models with carbon fiber parts available to a wide audience was announced. Thus, carbon fiber elements will be widely represented in the body structure of the new BMW i3. And in the new version of the Volkswagen Golf GTI VII hatchback, 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 have become even more widely used in aircraft manufacturing, where they have begun to replace traditional aluminum and titanium. Aircraft designers working in the defense industry were the first to appreciate the prospects. For example, the latest Russian Su-47 and T-50 fighters use carbon fiber components for the wing and fuselage.

Carbon 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 business jet Hawker 4000 is almost entirely made of this material!

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

As usual, carbon fiber reinforced plastics were the first to be used in the defense sector. Carbon composites are used to make elements of submarine hulls, as they seriously reduce noise and have a stealth effect, making the ship “invisible” to enemy radars. And in the Swedish Visbi-type corvettes, 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 specially woven fabric made of carbon strands. Each such bundle 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 in great demand. Most often, carbon is used in the construction of sports and pleasure yachts, where speed characteristics are important.

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

However, there are more modern methods. For example, the Italian company Lanulfi managed to almost completely automate the process. Using 3D modeling, large structural elements of the vessel are divided into smaller, but perfectly matching parts. Based on a computer model, using a computer-controlled machine, the bases are made, which serve as matrices for gluing carbon fiber parts. This approach allows us to achieve maximum accuracy, which is very important for the performance of sports yachts.

Carbon for everyone

Carbon is beginning to be increasingly used in construction. Adding carbon fibers to concrete makes it much more resistant to external influences. In fact, a super-strong 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 materials for strengthening, repairing and restoring reinforced concrete surfaces - special canvases and plates made of carbon fabric (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 builders, such an innovation as the use of carbon in the plaster system for insulating facades is of particular interest.

Reference

“Adding tiny 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 an energy of up to 60 Joules without harm - this is ten times more than conventional versions of plaster facades can withstand.”

If the owner of a cottage decides to use such a system for the exterior decoration of his home, he will not only reduce heating costs and provide a favorable indoor microclimate, but also protect the walls from any mechanical influences. Large hail shatters vinyl siding and leaves dents in regular sand stucco. Strong winds carrying debris and tree branches can also damage the façade. But the finish with the addition of carbon fibers will not leave a trace. Moreover, she is not afraid of such everyday influences as being hit with a ball or puck in children's games.

“Usually, to protect the basement part of the facade from accidental damage, they use stone cladding, for example, porcelain stoneware,” notes Daniil Mazurov, head of the wholesale sales department of the Moscow construction and trading company PKK Interstroytekhnologii. – But to finish the basement of a residential complex, which is currently being built in the south of Moscow, we decided to try a carbon fiber plaster system. 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 using 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 in the outer protective and decorative layer. But for a facade system with carbon fibers, such a problem does not exist.

Nowadays, private cottages and commercial buildings, schools and kindergartens, which stand out from the general background, are beginning to appear throughout Europe, for which carbon has helped to acquire expressive and rich colors. 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.

Generation Next

It is now impossible to imagine any high-tech industry without carbon. It is becoming more and more accessible to ordinary people. Now we can purchase 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 tens of times stronger than steel and have a host of other valuable properties.

Schematic representation of a nanotube

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

Among the most fantastic applications of carbon nanotubes is a space elevator, which will allow cargo to be delivered 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 thousand km above the Earth.

This idea was proposed by the great Russian scientist Konstantin Tsiolkovsky in 1895. But until now the project seemed impracticable 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 us to reconsider the boundaries of the possible. A millimeter-thick thread woven from carbon nanotubes can withstand a load of approximately 30 tons. This means that cheap and safe travel to orbit in a space elevator is turning from a science fiction plot into a practical task for engineers.

True, greatness is short-lived. Reinforced concrete, the most popular building material of the 20th century, unfortunately, has a short service life and will definitely not last 5 thousand years, like the Pyramids of Giza. However, there is a way to extend the life of such structures. Moscow scientists have come up with durable “clothing” for reinforced concrete. Now this is the latest squeak in architectural fashion. And not only.

Despite the fact that the time of Robin Hood has long passed, there are still many 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 speed of the arrow is 105 meters per second, and the target range is 100 meters. It received these unique characteristics thanks to the material from which it is made - carbon fiber.

Carbon or carbon fiber - this material is well known not only among archery athletes and hunters. Anyone who has ever skied modern alpine skiing has held carbon fiber 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 choosing a carbon frame over an aluminum one. Even ordinary household items, such as a computer keyboard or mouse, where super properties are not needed, have a carbon fiber design. However, there are entire industries where it is impossible to do without the super properties of this material. For example, aircraft manufacturing.

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

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

— About 200 kilograms.

— This one is about 50 kilograms.

Despite its relative lightness, this wing fragment can withstand a load of almost 2 thousand tons. In addition, an aircraft with such lightweight wings is able to hover in the air like a glider, so the engines work less, and this allows saving about 40 percent of fuel during the flight, and therefore 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 designed for aircraft construction are used here, for which temperature differences on the ground and in the air do not matter,” explains Alexey Ulyanov.

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

How does a seemingly ordinary fabric turn into such a strong structure that can withstand multi-ton loads and such impacts? It's all about infusion technology. The fabric, cut and laid into the desired shape, is placed in a vacuum module and then sent to a large oven. Another important component is supplied there through special pipes - resin, which binds all layers of fabric together into one monolith. World leaders in the aircraft industry, such as Boeing and Airbus, also use carbon fiber reinforced plastics in their aircraft, but the technology developed in the Moscow laboratory of the Aerocomposite company is not yet suitable for them. And in a year or two, Russia may have no competitors left in this area at all.

“We are finishing the construction of two serial plants. One plant will produce exactly the technology you see here, the main power elements, wing caissons. We launch 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 of next year. The second plant in the city of Kazan, which will produce mechanization elements and elevators. This is a plant that we are making together with our Austrian partners, the Fischer company. It will work both for Russian programs and extensive export programs commissioned by Fischer,” said Anatoly Gaidansky, President of JSC Aerocomposite.

The only thing that Russian manufacturers are losing out on in this carbon field is the quality of the carbon fiber itself, so aircraft manufacturers still have to use imported raw materials. However, everything will change soon. 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 long ago realized that such innovations are the future, and 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 this to you using a tensile testing machine. To do this, we attach the sample to the terminals and perform the test. Well, our sample withstood two tons,” shows Anton Evdokimov, testing laboratory engineer.

— What could create such a load?

— Similar loads can be created, for example, by two SUVs pulling a given sample in different directions in first gear.

— It turns out that steel wouldn’t even withstand such a load?

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

The most amazing thing is that this tensile strength material is made from liquid. More precisely, from polyacrylonitrile.

Polyacrylonitrile fiber is produced by extrusion. Simply put, the polymer is forced through a special die. This attachment, which appears to be completely homogeneous, actually contains 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, if you look closely, you can see thin whitish threads coming out of the spinneret in a continuous stream.

By passing through these hot baths of a special solution, the polymer fiber is thinned by approximately 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 durable fiber.

“This is not the final product yet, but only the raw material for producing carbon fiber. Before obtaining carbon fiber, this polyacrylonitrile fiber must undergo a process of high-temperature treatment, as well as oxidation, graphitization, and carbonization,” explains Elina Bilevskaya, representative of the Composite company.

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

“Our goal is to obtain more environmentally friendly fiber and reduce the cost of the technology for its production. Which, in fact, is what we succeed in. 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 the direct physical and mechanical properties of the resulting fiber,” says Denis Fokin, research engineer.

Several of the most successful developments that came out of the walls of this laboratory in the Moscow technology park are already being successfully used in construction. For example, carbon fiber added to building 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 in pilot, but in mass production. But is this technology as good in practice as it is said to be? Now we'll find out.

Let's conduct a demonstration experiment. Let's 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 one side it is reinforced with carbon fiber. So, let's start the experiment. First we will test our wooden bridge. It breaks on the third brick. Now let's check the carbon fiber ruler. One brick, two, three, four - the ruler did not break, the bridge supports did. Now I'm convinced that carbon fiber reinforced construction is much stronger.

A typical Moscow high-rise building. The house appears to be in good condition and there are no signs of serious damage in its appearance. However, they are already happening. Cracks appeared on the load-bearing structures in the basement of the house. Not big yet, 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.

“To prevent these cracks from appearing again, and this one from opening up even more, we are strengthening it. We are currently working on a similar area,” says engineer Alexey.

This is how you can actually save any reinforced concrete structure from destruction and the harmful effects of the external environment. Here, in the basement of the house, essentially the same technological process for creating carbon fiber that we saw in the production of aircraft parts is carried out. Only here the binding resin is applied directly to the concrete. Carbon fiber tape of the required width is rolled onto the treated surface and covered with another layer of epoxy. After a few hours, when the resin hardens, all cracks on the surface of the reinforced concrete floor will 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 overlap in four hours. If the reinforcement had been carried out using classical methods, for example, using metal frames, it would have taken about three days, and after five years in this damp basement the metal would begin to corrode again, and we would have to go back and redo it,” explains builder Alexey.

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

What is carbon?

Carbon is a technical fabric consisting of thousands of carbon fibers intertwined to form the same fabric. Carbon fiber comes in a wide variety of weaves depending on the intended application and is just one part of a structural materials that includes many parts that are known as composite materials. Composites are made from components that combine the qualities of different materials, and the goal is to avoid rigidity or to obtain strength. In the case of carbon, fiberglass, Kevlar or other similar fabrics, the composite material in question is called FRP (Fiber Reinforced Polymer). In the production of such a polymer, fabric is used to “strengthen” the structural rigidity of the resin sublayer. The resin provides strength to the composite, while the carbon adds structural integrity to otherwise brittle plastic.

How is carbon produced?

Carbon fiber (carbon fiber), as its name suggests, is a fabric consisting only of coal and has no other elements in its composition. But starting production simply with carbon fiber and creating a fabric with interwoven fibers would be a real, but elusive, feat. Instead of using carbon fiber as a raw material, textile factories are starting with plastics with a more complex molecular composition, where the thickness of the thread is less than the thickness of a human hair. Then a series of specific actions are required, 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 is often measured and sold based on several criteria, the type of fiber weave, absolute values ​​(measuring 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 ranging from 3,000 to 12,000 fibers).

What types of weave are there?

Unidirectional weave:

Unidirectional weaving means all carbon 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 fiber strands must be held together somehow. 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). Due to the fact that the fabric is stiff in only one direction, this type of weave is rarely used in motorsports, where the load can go in any direction.

Bidirectional fiber weaving:

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

Weaving diagonally in two through two threads

Diagonally woven two-by-two is the most common type of carbon fiber weave and is widely used in motorsports. This weave is a little more complex compared to bidirectional fiber because two strands pass over the other two strands, either one over two or two over one. As a result of this interweaving of threads, a herringbone pattern is created on the fabric. Due to the fact that weaving two by two threads diagonally with both vertical and horizontal threads (warp and weft threads), the fabric becomes very flexible and can take on various complex shapes. When working with carbon fiber of this type of weaving, it is not necessary to perform such work as “packing”, “stretching” or cutting.

Weaving diagonally in four through four threads

Similar to weaving diagonally in two through two threads, namely in four through four threads, this type refers to a double-sided diagonal weave, where one bundle includes four threads. The result is that the fabric is not as dense as a two-by-two weave, but with curved surfaces a better coverage ratio is achieved because there is more space between the actual over and under weave points, which is more efficient because less is achieved. hard seams. This makes carbon coating of curved castings easy.

Rubberized weave

Rubberized carbon fabric is a very specific way of making fabric that is much less common compared to all the types of weaves we discuss. The rubberized fiber weave means that each strand is made up of between 3,000 and 12,000 threads, with each thread laid out tightly in a row, one after the other, to form the finest carbon tape. Standard strands are joined together through several layers of carbon fibers. Rubberized fabric can be identified by the presence of wide open areas. The staggered pattern of bi-directional carbon fiber with a rubberized fabric structure creates one-inch square sections.

Since the fabric loses its density due to the large size of these weaving areas, the weaving points “above and below” are located at a great distance from each other. So, the intersection points of the threads are located at a distance from each other, the frequency of changes in direction is greatly reduced, and the fabric can adhere much more tightly to the surface.

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

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

Various resins

Carbon fabric is just one component of the composite material that is referred to when talking about motorsports and track racing. Another important component is the resin, which enriches the fabric itself and gives it actual rigidity. Resins are used in various polymer “dishes”. The two most commonly used materials are epoxy resin and polyester resin. Anyone who has ever worked with fiberglass to simply fix their surfboard or car part knows that this resin can be a real problem. Volatile organic compounds (VOCs) are vapors that are a hallmark of many resins, although there are some that are freely available that do not contain these brain-damaging chemicals. Almost everyone knows the opposite effect of working with resin, when proper personal protective equipment is not used, but hypersensitivity and allergies develop. And these cases have become so commonplace that we often hear jokes about people who are unable to stay in the room where they are working with resin.

Epoxy resin

Epoxy resin is the most common multi-purpose structural resin. As with virtually all types of resins, it is a two-part solution of resin and catalyst. Reaction times vary, but are directly dependent on environmental conditions. The shelf life (working time) is generally between five and thirty minutes. In general, thermal influence always accelerates the “ripening” process, but the entire setting process usually takes, neither more nor less, but a 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 resin with a fast cure time. It is mainly used in situations where structural integrity is at a premium over aesthetics, as easycomposites.co.uk states: “However, there are situations in which a sandwich structure is of least importance and properties such as appearance appearance, UV resistance and price come first in importance.”

Prepregs (pre-impregnated fabrics)

Some carbon fiber fabrics can be produced as pre-impregnated resin solutions, where the catalyst is heat treatment. Prepregs are used in many composites industries because they don't require any complicated processes and the mess is kept to a minimum by simply mixing the resins and laying down wet fabric in layers.

Prepregs are also the material of choice in industries where weight is an issue. Such areas include aviation, where most of the mass of parts is resin rather than fabric. Given the minimum required to thoroughly and uniformly impregnate the fabric with resin, prepreg can be used to create the most durable and lightweight structure.

Production processes

Wet displays

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

Having thus laid down 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 vacuum bagged under low pressure. As a result, the resin fills all remaining air voids, thereby displacing the smallest air bubbles, and excess resin is eliminated.

In some cases, all these manipulations are performed in reverse order. The dry fabric is vacuum bagged in a mold before the resin is applied. Thanks to this method, there is no waste or dirt. At the final stage, heat treatment takes place. All parts are “baked” inside the oven under pressure, 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 autoclave baking are optional for work parts whose structure does not need to meet specific requirements.

Areas of application

Carbon has gained its strength in the automotive industry. In the aftermarket, carbon is the material most often used to cover parts. Body parts, interior trim parts - and all this is made of carbon fiber, which provides the car with the highest class appearance. Functionally, carbon 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 devices such as helmets and restraints (head restraints), and even composite spring technology is beginning to use carbon for suspension systems.

Carbon is not a panacea

The attractiveness of carbon is so great for many that today there is a tendency to misuse this material in areas where the best solution is still a metal alloy. Carbon, and especially resin, does not do well in high-temperature environments, heat shields, exhaust components, or any other engine parts. When carbon is selected as the starting material in these cases, the operating conditions must be assessed very carefully. There are heat-resistant resins, but their scope of application still has its limitations.

Impact resistance

Carbon can boast that this (already a catchphrase) 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 a reinforced polyester laminate whose impact resistance is low. And even a weak point blow can lead to peeling and, ultimately, failure of the material. For this reason, carbon cannot be used to create wear-resistant or reusable fifth-wheel base plates of satisfactory quality, for the production of various suspension components, or for any other parts that are used under maximum load conditions.

Conductivity

Carbon is a conductive material! Pure carbon is extremely efficient at transferring heat on its own. For example, a car hood made of carbon fiber can very quickly heat up to several hundred degrees in the sun. Ultraviolet rays can damage the composite, turning it yellow or causing the resin to crack, so warping is a common defect. In aviation, many carbon fiber parts are coated with glossy white paint, since the heat generated from exposure to UV rays can deform the frame and have a negative impact on aerodynamic characteristics. In addition, UV rays may change the structure of the aircraft in some other way.

Carbon is also an electrically conductive material. You might be confused as to how a plastic-based composite can suddenly become electrically conductive, but pure carbon fiber fabric paves the way for electricity, even if the carbon is enriched with an insulating polymer. When carbon fiber is selected as a surface for electronics or as a cooling fan shroud, make sure there is a ground connection that does not "pass" through the carbon fiber. An anecdote from real life: we once witnessed a near fire in the engine of a Geiser Trophy truck owner, because he simply did not believe that carbon is a conductive material, and a resin fire is no joke.

Working with carbon

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

When ordering carbon fiber fabric, it is important to ensure that it comes in rolls, like wrapping paper. Carbon packaged in folds will have folds and, as a result, the structural integrity of its folded fibers will be compromised. Follow these instructions when handling the material, and keep the fabric clean to avoid dust and greasy fingerprints, while ensuring that it fits as smoothly as possible. It is necessary to mix the resin in small containers, which is the norm. Be careful not to mix resin in wax-lined containers. The wax reacts with the resins, causing the resin to harden. Resin curing is an exothermic reaction, which means heat is produced as a by-product of the chemical reaction. When mixing large quantities of resin, make sure that excess resin is kept away from flammable materials storage areas, otherwise there is a high risk of fire.

Conclusion

The amount of basic knowledge that we haven’t even touched on in this article is simply enormous. But we hope this general overview has given you a better idea of ​​what carbon fiber is. It is an extremely versatile and durable material if handled wisely. But if used incorrectly, it becomes a real eyesore. Making 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 make a decision, is carbon fiber the right choice or do you just want to add aesthetics to your car?

Data taken from the site: tourerv.ru