College of Materials Science and Engineering, Shenzhen University, Shenzhen Key Laboratory of Special Functional Materials, Shenzhen 518060, China
Funds:
National Science Foundation of China (50672059,50702034), Programme of Tackle Key Problems on SciTechnliogy of Guangdong in China (2004B10301006) and Project Supported by the Scientific Research Foundation for Shenzhen University.
Microwave assisted chemical vapor infiltration (CVI) was carried out to prepare carbon/carbon composites in a homemade microwave furnace in the temperature range of 1075-1150℃, using carbon fiber felt as the substrate and and methane as the pyrolytic carbon precursor. The felts were heated by absorbing microwave energy. Because the selective heating of the carbon fiber surface by polarization of polar groups on the carbon fiber surface and the catalytic effect of homogeneous gasphase reactions by microwaves, the preform was densified from center to surface to a bulk density 1.70g/cm3 after CVI for 90h. The densification rate was increased to 0.0189g/(cm3 · h). The pyrolytic carbon has a smooth laminar structure along carbon fiber surface. The radial density distribution of carbon investigated by optical microscopy indicates that plugging of the surface pores is avoided in the carbon fiber felts and the microstructure of the materials is uniform, having a medium texture.