What Are They?
Carbon fibers are made by pyrolizing organic fibers such as viscose, rayon, or polyacrylonitrile (PAN), or from petroleum pitch. The PAN type has the better mechanical properties, but those produced from pitch are cheaper. PAN fibers are first stretched for alignment, the oxidized in air at slightly elevated temperatures, then carbonized in an inert environment at very high temperatures, and finally heated under tension to convert the crystal structure to that of graphite. Carbon fibers have high strength and stiffness with low density, but they oxidize at high temperatures unless the atmosphere is reducing. They come in four grades: high modulus, high strength, ultra high modulus, and ultra high strength – with cost increasing in that order. The single fibers are very thin (<10 microns in diameter); they are generally spun into tows and woven into textiles. They are primarily used as reinforcement in polymer, metal, or carbon matrices. This record describes the properties of single high strength (HS) carbon fibers.
CFRP, and metal-matrix and ceramic matrix composites. Carbon fiber-rein forced carbon for brake pads in racing cars and aircraft.