Carbon fiber or carbon fiber (alternatively CF, graphite fibers or graphite fibers) are fibers about 5-10 micrometers in diameter and comprise mostly carbon atoms. Carbon fiber has several advantages including high stiffness, high tensile strength, low weight, high chemical resistance, high temperature tolerance and low thermal expansion. These properties have made carbon fiber very popular in the aerospace, civil engineering, military, and motor sports, along with other competitive sports. However, they are relatively expensive when compared with similar fibers, such as glass fibers or plastic fibers.
To produce carbon fiber, carbon atoms are bonded together in crystals that are more or less parallel to the long axis of fiber as a crystal alignment provides a high fiber-to-volume fiber ratio (making it strong for its size). Several thousand carbon fibers are bundled together to form a crane, which can be used by itself or woven into fabric.
Carbon fibers are usually combined with other materials to form composites. When impregnated with plastic resin and baked to form carbon-reinforced polymers (often referred to as carbon fibers) that have a very high strength-to-weight ratio, and are extremely rigid though somewhat fragile. Carbon fibers are also composed with other materials, such as graphite, to form reinforced carbon-carbon composites, which have extremely high heat tolerances.
Video Carbon fibers
Histori
In 1860, Joseph Swan produced carbon fiber for the first time, for use in light bulbs. In 1879, Thomas Edison roasted cotton yarn or bamboo wedges at high temperatures, turning carbon into carbon-fiber filaments used in one of the first electrically heated incandescent bulbs. In 1880, Lewis Latimer developed a reliable carbon wire filament for incandescent light bulbs, heated by electricity.
In 1958, Roger Bacon created a high-performance carbon fiber at the Union Carbide Parma Technical Center located outside Cleveland, Ohio. The fibers are produced by heating the rayon strands until they are carbonized. This process proves inefficient, since the resulting fiber contains only about 20% carbon and has a low strength and stiffness. In the early 1960s, a process was developed by Dr. Akio Shindo at the Agency of Industrial Science and Technology of Japan, uses polyacrylonitrile (PAN) as raw material. It has produced carbon fibers containing about 55% carbon. In 1960 Richard Millington of H.I. Thompson Fiberglas Co. developed a process (US Patent No. 3,294,489) to produce carbon fiber (99%) using rayon as a precursor. This carbon fiber has sufficient strength (modulus of elasticity and tensile strength) to be used as a reinforcer for composites having high strength to heavy properties and for high temperature resistant applications.
The high potential strength of carbon fiber was realized in 1963 in a process developed by W. Watt, L. N. Phillips, and W. Johnson at the Royal Aircraft Establishment in Farnborough, Hampshire. The process is patented by the UK Ministry of Defense, which is then licensed by the British National Research Development Corporation to three companies: Rolls-Royce, which has already made carbon fiber; Morganite; and Courtaulds. Within a few years, after successful use in 1968 from a collection of carbon fiber fans in Rolls-Royce Conway jet engines from Vickers VC10, Rolls-Royce took advantage of the new material properties to break into the American market with aero-engine RB-211 with carbon fiber compressor blades. Unfortunately, the blades proved to be vulnerable to bird-induced damage. This and other problems caused Rolls-Royce to decline that the company was nationalized in 1971. The carbon fiber production plant was sold to form Bristol Composites.
In the late 1960s, Japan took the lead in manufacturing PAN-based carbon fibers. The joint technology agreement of 1970 enabled Union Carbide to manufacture Japanese Toray Industries products. Morganite decided that carbon fiber production was peripheral to its core business, leaving Courtaulds as the only major British manufacturer. Courtelle's water-based inorganic processes make the product vulnerable to impurities that do not affect the organic processes used by other carbon fiber manufacturers, which caused Courtaulds to stop carbon fiber production in 1991.
During the 1960s, experimental work to find alternative feedstocks led to the introduction of carbon fibers made from petroleum pitch derived from oil processing. These fibers contain about 85% carbon and have excellent bending strength. Also, during this period, the Government of Japan strongly supported the development of carbon fiber at home and some Japanese companies such as Toray, Nippon Carbon, Toho Rayon and Mitsubishi started their own development and production. Since the late 1970s, carbon fiber yarn types have further entered the global market, offering higher tensile strength and higher elastic modulus. For example, a T400 from Toray with a tensile strength of 4,000 MPa and M40, a modulus of 400 GPa. Medium carbon fiber, such as IM600 from Toho Rayon with up to 6,000 MPa developed. Carbon fibers from Toray, Celanese and Akzo find their way into aerospace applications from the secondary to the first primaries in the military and then on civilian aircraft such as in McDonnell Douglas, Boeing and Airbus aircraft.
Maps Carbon fibers
Structure and properties
Carbon fibers are often given in the form of a continuous crane wound to the reel. These cranes are bundles of thousands of individual sustainable carbon filaments that are united and protected by an organic layer, or size, such as polyethylene oxide (PEO) or polyvinyl alcohol (PVA). The crane can be easily removed from the roll for use. Each carbon filament behind it is a continuous cylinder with a diameter of 5-10 micrometers and is composed almost entirely of carbon. The earliest generation (eg T300, HTA, and AS4) has a diameter of 16-22 micrometers. The later fibers (eg IM6 or IM600) have a diameter of approximately 5 micrometers.
The atomic structure of carbon fibers is similar to graphite, which consists of sheets of carbon atoms arranged in ordinary hexagonal patterns (graphene sheets), the difference lies in the interlocking of this sheet. Graphite is a crystal material in which sheets are stacked parallel to each other in the usual fashion. The intermolecular force between the sheets is a relatively weak Van der Waals force, giving the graphite a soft and brittle characteristic.
Depending on precursors for making fibers, carbon fibers may be turbostatic or graphic, or have hybrid structures with existing graphite and turbostatic sections. In carbon fiber turbostratic sheets of carbon at random are folded, or tangled, together. The carbon fibers derived from polyacrylonitrile (PAN) are turbostatic, while the carbon fibers derived from the mesophase pitch are graphite after heat treatment at temperatures exceeding 2200 ° C. Turbostratic carbon fibers tend to have high tensile strength, while carbon fibers treated with sorop- hot-pitch-pitch has a high Young modulus (ie, high stiffness or resistance to extensions under load) and high thermal conductivity.
Apps
In 2012, global demand for the carbon fiber market is estimated at $ 1.7 billion with an annual growth forecast of 10-12% from 2012-2018. The strongest demand for carbon fiber comes from aircraft and air, wind energy, and the automotive industry with an optimized resin system.
Carbon fibers can have a higher cost than other materials that have become one of the limiting factors of adoption. In comparison between steel and carbon fiber materials for automotive materials, the cost of carbon fibers may be 10-12x more expensive. However, this cost premium has declined over the last decade from an estimated 35x more expensive than steel in the early 2000s.
Composite materials
Carbon fibers are primarily used to strengthen composite materials, in particular a class of materials known as carbon fibers or graphite-reinforced polymers. Non-polymeric materials can also be used as matrix for carbon fibers. Due to the formation of metal carbides and corrosion considerations, carbon has seen limited success in the application of metal matrix composites. Reinforced carbon-carbon (RCC) consists of carbon fiber reinforced graphite, and is used structurally in high temperature applications. Fiber also finds use in high temperature gas filtration, as electrodes with high surface area and perfect corrosion resistance, and as anti-static components. The thin layer carbon fiber molding significantly improves the fire resistance of polymers or thermoset composites because the solid and solid layers of carbon fibers efficiently reflect heat.
The increased use of carbon fiber composites is replacing aluminum from aerospace applications that support other metals due to galvanic corrosion problems.
Textile
Precursors for carbon fibers are polyacrylonitrile (PAN), rayon and pitch. Carbon fiber filament yarns are used in several processing techniques: direct use is for prepregging, winding filaments, pultrusion, weaving, braiding, etc. The carbon fiber yarn is rated by linear density (weight per unit length, that is, 1 g/1000 m = 1 tex) or by the number of filaments per number of threads, in the thousands. For example, 200 tex for 3,000 carbon fiber filaments are three times stronger than 1,000 carbon filament yarns, but also three times heavier. This yarn can then be used to weave cloth or carbon fiber filaments. The appearance of these fabrics generally depends on the linear density of the yarn and the woven fabric chosen. Some commonly used weaving types are twill, satin and plain. The carbon filament yarn can also be knitted or braided.
Microelectrode
Carbon fibers are used for the manufacture of carbon fiber microelectrodes. In this application is usually one carbon fiber with a diameter of 5-7? M sealed in capillary glass. At the end of the capillary it is sealed with epoxy and polished to make microelectric disc of carbon fiber or fiber cut to length 75-150? M to make carbon-fiber cylinder electrodes. Carbon fiber-micro fibers are used either in amperometry or fast-cycle cyclic voltammetry to detect biochemical signals.
Flexible heating
Known for its conductivity, carbon fibers can carry very low currents on their own. When woven into larger fabrics, they can be used to reliably provide infrared heating in applications that require flexible heating elements and can easily maintain temperatures past 100 Ã, Â ° C due to their physical properties. Many examples of this type of app can be viewed in 'DIY' or Do your own heated articles of clothing and blankets. Because of its inert nature, it can be used relatively safely between most fabrics and materials; However, shorts caused by the back folding material itself will cause an increase in heat production and may cause a fire.
Synthesis
Each carbon filament is produced from polymers such as polyacrylonitrile (PAN), rayon, or petroleum pitch, known as precursors. For synthetic polymers such as PAN or rayon, the precursors are first spun into filament yarns, using chemical and mechanical processes to initially align polymer atoms by increasing the final physical properties of complete carbon fibers. The compositions of the precursors and the mechanical processes used during spinning filament yarns may vary between manufacturers. After drawing or spinning, the polymer filament yarn is then heated to drive a non-carbon atom (carbonization), producing the final carbon fiber. The carbon fiber filament yarn can be further processed to improve the handling quality, then rolled into a coil.
The general method of manufacture involves heating PAN filaments spinning to about 300 ° C in the air, which breaks many of the hydrogen bonds and oxidizes the material. The oxidized PAN is then placed into a furnace having an inert gas atmosphere such as argon, and heated to about 2000 ° C, which induces the graphitization of the material, alters the molecular bond structure. When heated under the right conditions, this chain binds side-to-side (ladder polymer), forming a narrow graphene sheet that eventually joins to form a single, columnar filament. The result is usually 93-95% carbon. Low quality fibers can be produced using pitch or rayon as a precursor instead of PAN. Carbon can be further improved, such as high modulus, or high strength carbon, by heat treatment processes. The heated carbon in the range 1500-2000 Â ° C (carbonization) shows the highest tensile strength (5,650 Ã, MPa, or 820.000 psi), while the carbon fiber is heated from 2500 up 3000 Â ° C (graphitization) shows a higher elastic modulus (531 GPa, or 77.000.000 psi).
Research on renewable fiber production
Currently, a number of research institutes are conducting research to try to synthesize carbon fiber from raw materials based on renewable and non-fossil fuels. If successful, this can reduce greenhouse gas emissions associated with carbon fiber manufacture as well as long-term production costs.
See also
- Basalt fiber
- Carbon fiber reinforced fiber
- Carbon fiber reinforced materials
- Carbon nanotubes
- ESD material
- Graphene
References
External links
- Creating Carbon Fiber
- How carbon fiber is made
- Carbon Fibers - First Five Year A 1971 Flights article on carbon fiber in the aviation field
Source of the article : Wikipedia
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