Abstract: The infiltration of carbon fiber preforms was studied by microwave pyrolysis chemical vapor infiltration technique, CH₄
as the carbon source gas, and N₂ as diluent gas, at 1100℃ and methane partial pressure of 10kPa with residence time of 0.05,0.1,0.15 and 0.2s, respectively. The textures of samples were observed, the densification rules of microwave pyrolysis CVI were analyzed by densification rate and radial--direction density distribution with different residence time. Results show that carbon fiber preforms can be densified from inside to outside at 1100℃ for 90h, with gas residence time of 0.15s, the carbon/carbon composite has a higher bulk density of 1.70g·cm^-3. Simultaneously, polariscope images show that the textures of the pyrocarbon change from low-textured to medium-textured with the extending of residence time.

Key words: carbon/carbon composites, microwave pyrolysis CVI, residence time, densification