Full definition
High-performance reinforcement fiber composed of >92% carbon atoms, produced by controlled pyrolysis (carbonization) of precursor fibers (PAN — polyacrylonitrile, or pitch). Carbon filaments (5-10 μm diameter) are bundled into tows (1K-48K filaments) and combined with a polymer matrix (typically epoxy resin) to create carbon fiber reinforced polymer (CFRP). Properties: tensile strength 3,500-7,000 MPa (5-10x steel), elastic modulus 230-600 GPa, density 1.75-1.95 g/cm³ (vs 7.85 for steel) — yielding the highest specific strength and stiffness of any engineering material. Types: standard modulus (T300, T700), intermediate (T800), high modulus (M40, M55). Manufacturing processes: prepreg layup + autoclave, filament winding, pultrusion, and resin transfer molding. Applications: aerospace structures (Boeing 787 is 50% CFRP), Formula 1 chassis, wind turbine blades, sporting goods, medical prosthetics, and industrial rollers. Per ASTM D3039 for tensile testing. Limitation: brittle failure mode, high cost ($15-150/kg), and UV sensitivity requiring protective coating.