World's Strongest Materials

Carbon fibers or carbon fibres (alternatively CF, graphite fiber or graphite fibre) are fibers with a diameter of 5-10 micrometers and composed mostly of carbon atoms. Carbon fibers have many advantages such as high strength, high tensile strength, low weight, high chemical resistance, high temperature tolerance and low thermal expansion. These properties have made carbon fiber very popular in aerospace, civil engineering, military applications, motorsports and other competitive sports. However, they are relatively expensive compared to similar fibers such as glass fibers or plastic fibers. To produce a carbon fiber, carbon atoms are bonded together in crystals that are more or less parallel to the long axis of the fiber, with crystal alignment providing the fiber's high strength-to-volume ratio (which reinforces the dimension). Several thousand carbon fibers are brought together to form a tow that can be woven on its own or in a fabric. Carbon fibers are typically combined with other materials to form a composite. When impregnated with a plastic resin and cured in an oven, it creates carbon fiber reinforced polymer (commonly referred to as carbon fiber) with a very high strength-to-weight ratio and is extremely rigid despite being somewhat brittle. Carbon fibers are combined with other materials such as graphite to create reinforced carbon-carbon composites with very high heat tolerance. In 1860, Joseph Swan first produced carbon fibers in light bulbs. In 1879, Thomas Edison produced carbon filament by heating cotton threads or bamboo strips at high temperatures, used in one of the first incandescent bulbs to be heated electrically. In 1880, Lewis Latimer developed a reliable carbon filament for electrically heated incandescent bulbs. In 1958, Roger Bacon produced high-performance carbon fibers at the Union Carbide Parma Technical Center in Cleveland, Ohio. These fibers were produced by heating rayon threads until they were carbonized. It was found that this process was inefficient because only 20 percent of the resulting fibers contained carbon and had low strength and hardness properties. In the early 1960s, a process was developed by Dr. Akio Shindo at Japan's Agency of Industrial Science and Technology using polyacrylonitrile (PAN) as a raw material. In this way, a carbon fiber containing approximately 55 percent carbon could be produced. In 1960, Richard Millington from H.I. Thompson Fiberglas Co. pioneered a method to produce high carbon content (99 percent) using rayon (U.S. Patent No. 3,294,489). These carbon fibers had sufficient strength (elastic modulus and tensile strength) to be used as reinforcement for high-temperature-resistant applications with high strength-to-weight properties. The high potential strength of carbon fiber was realized in 1963 by a process developed by W. Watt, L. N. Phillips and W. Johnson at the Royal Aircraft Establishment in Farnborough, Hampshire. The process was patented by the United Kingdom Ministry of Defence and licensed by the British National Research Development Corporation to three companies already producing carbon fiber: Rolls-Royce; Morganite; and Courtaulds. By the late 1960s, the Japanese took the lead in the production of PAN-based carbon fibers. In 1970, a joint technology agreement allowed Toray Industries products to be manufactured by Union Carbide. In the 1970s, experimental work to find alternative raw materials led to the introduction of carbon fibers made from petroleum pitch obtained from oil refining. These fibers contained approximately 85 percent carbon and had excellent bending strength. Once considered for space and aerospace materials, carbon fiber has now become commercialized. Today, carbon fibers are an important part of many products and new applications are being developed every year. The United States, Japan and Western Europe are the leading producers of carbon fibers. Carbon fibers are used where low weight, high hardness, high conductivity or carbon fiber woven appearance is desired.

Carbon Fiber in Aerospace

Space and aerospace were among the first industries to adopt carbon fiber. The high carbon fiber modulus is suitable for structurally replacing alloys such as aluminum and titanium. The weight savings it provided became the primary reason for carbon fiber adoption by the aerospace industry. Every kilogram of weight reduction can make a significant difference in fuel consumption, which is why Boeing's new 787 Dreamliner aircraft became the best-selling passenger aircraft in history. The majority of this vehicle's structure consists of carbon fiber reinforced composites.

Sports Equipment

Recreational sports is a market segment willing to pay more for higher performance. Tennis rackets, golf clubs, softball bats, hockey sticks and archery arrows and bows are generally products manufactured with carbon fiber reinforced composites. Lightweight equipment without compromising strength is a significant advantage in sports. For example, with a lighter tennis racket, faster racket speed can be achieved and as a result, the ball can be hit harder and with greater force. Athletes continue to have advantages in equipment using carbon fiber. For this reason, professional cyclists ride bicycles made entirely of carbon fiber and wear bicycle shoes using carbon fiber.

Wind Turbine Blades

Although fiberglass is generally used in a wind turbine blade, in blades larger than 45 meters, there is a component with a stiffening spar that extends the length of the blade. These components are typically 100 percent carbon and are only a few centimeters thick. Carbon fiber is used to provide the required strength without adding an enormous amount of weight. This is important because a lightweight wind turbine blade is more efficient in generating electricity.

Automotive

Mass-produced automobiles are not yet using carbon fiber; this is because the increased raw material cost and the necessary changes to molds still outweigh the advantages. However, Formula 1, NASCAR and advanced technology automobiles use carbon fiber. In most cases, carbon fibers are preferred for their appearance rather than the benefits of their properties or weight. There are many aftermarket automotive parts made from carbon fiber, and instead of being painted, they are clear coated. Carbon fiber has become a symbol of high technology and high performance. This can be observed in many spare parts. To reduce costs, products are encountered with a single carbon fiber layer on the visible surface and many fiberglass layers underneath. This shows that the appearance of carbon fiber is actually the determining factor. However, as costs also decrease, many new carbon fiber applications are emerging today. The growth of carbon fiber is continuing rapidly and we can say with certainty that in the near term, the use of carbon fiber will increase.

Prepared by: B. Serhat Cengiz

References • "The Gifted Men Who Worked for Edison" . Lewis Howard Latimer . National Park Service . Retrieved Dec 1, 2014 . • Bacon, R. "Filamentary graphite and method for producing the same" U.S. Patent 2,957,756 , Priority date March 18, 1958 • "Stand Points . Flight International . 26 September 1968, p. 481 • W.J. Cantwell; J Morton (1991). "The impact resistance of composite materials – a review". Composites . 22 (5): 347–62. doi : 10.1016/0010- 4361(91)90549-V . • "Global Carbon Fiber Composites Supply Chain Competitiveness Analysis" (PDF) . Clean Energy Manufacturing Analysis Center . Retrieved 2017-05-24 . • "Market Report: World Carbon Fiber Composite Market" . Acmite Market Intelligence. July 2010.