Preparation of C/C composites by thermal gradient chemical vapor infiltration with vaporized kerosene as a precursor

Abstract

A thermal gradient chemical vapor infiltration method with vaporized kerosene as a precursor for the fabrication of C/C composites was studied,in which a disc-shaped carbon felt preform was sandwiched within two flat heating sources,forming a temperature gradient,and the precursor was supplied with a third heating source. The density and open porosity of the composites were investigated by the Archimedes method (in water) and microstructures were studied by SEM. Results shows that the densities of the composites increase linearly with temperature and the C/C composite has a density up to 1.72 g/cm3 when a carbon felt with a bulk density of 0.2 g/cm3 was infiltrated at 1 100 ℃for 3 h.. The interlayer spacing (d002) decreases and the composite can be easily graphitized at 2 200 ℃. The carbon fibers in the composites are surrounded by a ring of pyrocarbon. The deposition process is analyzed by dividing the reactor into four regions associated with different functions. The rapid densification can be accounted for by the short convection and diffusion paths for the precursor and the thermal gradients across the preform.