Microstructures and mechanical behavior of C/C composites prepared by ICVI using n-propanol as precursor

Two dimension needle-punched carbon fiber felts with an initial bulk density of 0.43 g/cm³ were densified by isothermal-isobaric chemical vapor infiltration (ICVI) at 1050, 1100, 1150°C and total pressure of 6kPa, using n-propanol diluted by nitrogen as the precursor of pyrolytic carbon. The bulk density of C/C composite after densified for 96h were 1.64 g/cm³, 1.68g/cm³ and 1.69/cm³, respectively. Bulk densities of the infiltrated samples were determined as a function of infiltration time. The flexural strength was investigated by three-point bending test. Texture and fracture surface morphology of the samples were studied by polarized light microscope (PLM) and scanning electron microscope (SEM). A layer of midium-textured carbon followed by a layer of high-textured carbon matrix were formed at 1050 and 1150°C. While C/C composites with pure high-textured pyrolytic carbon matrix was obtained at 1100°C, with the flexural strength of 199.24MPa. No oxidation trace was found on the surface of carbon fiber from PLM and SEM observation. Consequently, n-propanol is a promising precursor in CVI process for the densification of high-performance C/C composites.