Synthesis, characterization and tensile strength of CVI C/SiC, SiC/SiC, SiC/B4C, and C/B4C composites

CVD of carbon (derived from two different precursors) on SiC and B4C matrices has been employed to yield single-strand unidirectional composites. The tensile strength of carbon deposited via pyrolysis of propylene was higher than that of methane pyrolysis-deposited carbon matrices. A novel CVD boron-carbon interface has also been developed which does not degrade carbon yarns and yields composites exhibiting high strengths; these strength levels were, moreover, highly resistant to long-duration, high-temperature annealing. Coated fibers and composites have been characterized by SEM and XRD. 8 refs