CREEP-BEHAVIOR OF A PITCH-BASED CARBON-FILAMENT

New fabrication techniques were developed for uniaxial creep specimens of high-strength, high elastic modulus, pitch-based, carbon filaments , with a matrix-free test section. Experiments show that pitch-based c arbon filaments with a tensile modulus of 896 GPa can exhibit, under h igh stress, large creep deformation,without necking, The stress expone nt for the pitch-based fibers in the Dorn equation is much lower than that for PAN-based fibers, while the activation energy is the same, Th e activation energies and activation volumes determined from the exper iments suggest mechanisms of creep deformation.