Carbon fiber consists of extremely fine filaments, between 5 and 7 microns in diameter. More than 90% of these carbon filaments are composed of carbon atoms, the rest being mainly nitrogen atoms. Carbon atoms form graphitic planes organised in crystals.
Torayca® Carbon Fiber is produced from polyacrylonitrile (PAN) fiber. These PAN fibers are obtained by polymerising, spinning and then stretching the polymer. The resulting polymeric chains are aligned in the filament axis’s direction. This is essential to obtain the characteristic properties of carbon fiber.
Carbon fiber is light because carbon atoms have a low atomic mass. In addition, the chemical structure composed of graphitic planes organised in crystal alignments induces larger spacing between carbon atoms.
Carbon fiber is extremely robust and rigid (high modulus). Covalent bonds bind carbon atoms in the graphitic planes. These chemical bonds are highly stable: as the carbon atoms share electrons, a great deal of energy is required to break a covalent bond.
The structure of the carbon filaments also plays an important role in the material’s strength and resistance.
As a result, carbon composites offer unrivalled tensile strength, modulus and resistance to fatigue.
Carbon fiber is heat-resistant. When used at high operating temperatures, carbon fiber does not degrade or expand.
To make full use of its thermal properties, carbon fiber is sometimes combined with a ceramic matrix, to create a ceramic matrix composites material (CMCs). Carbon can thus be considered ceramic material. Consequently, CMCs retain carbon properties up to temperatures above 2,000 °C.
Carbon fiber is electrically conductive. Under electric current, carbon fiber generates Joule heat. Thanks to its electrical conductivity and excellent thermal resistance, it offers an excellent heating solution. Carbon composites can also be used to shield electronic equipment from radio or electromagnetic interference. Carbon composites, therefore, act as a Faraday cage.
Carbon fiber is composed of lightweight elements: 95% of carbon atoms and 5% nitrogen. It absorbs very few X-rays making it ideally suited for use in medical imaging.
Carbon fiber has an extremely orderly structure that induces many strong bonds between carbon atoms. As a result, the oxidation reaction produced in a fire cannot self-feed, giving this material its non-flammable characteristic.
Light, durable and resistant, carbon fiber is a cutting-edge material. It is most notably used to reinforce composite materials. The main applications are found in the:
Carbon fiber is regularly used to reduce the weight of vehicles, aeroplanes and other forms of public transport. An aeroplane with a fuselage made of carbon composites is 20% lighter than one made using traditional materials. Over the life cycle of the plane, this 20% reduction in weight enables CO2 emissions to be reduced by 400 tons.
Automotive Industry: the Hydrogen Solution
Hydrogen vehicles now have higher battery life than electric battery vehicles (> 500 km). This performance is possible thanks to the storage of compressed hydrogen in a carbon fiber pressure tank. Thanks to its unique properties, carbon fiber is the only material capable of providing the necessary strength, light ness and long-term performance for these tanks.
Toray’s innovative Carbon Paper, is also the solution used to produce the key component of PEM fuel cells: gas diffusion membranes.