Fabrication of carbon-carbon composites for aircraft brakes by directional flow thermal gradient chemical vapor infiltration

The carbon cloth and carbon fiber felt are laminated alternately and then needled to prepare the porous carbon/carbon preforms, from which the carbon/carbon composites for aircraft brakes are fabricated by the thermal gradient CVI process. Furthermore, the microstructure of the material is studied by polarized light microscopy. The results show that the process allows simultaneous infiltration of multi to preform per run. Porous carbon carbon preforms, 110 mm×45 mm×(15～20) mm can be densified in a one cycle. Uniform carbon carbon disks with the average density of more than 1.60 g/cm 3 are obtained in 80 h. The precursor utilization efficiency can be as high as 27%. It is also found that the microstructure of pyrocarbon matrix varies from rough laminar structure to banded structure to smooth laminar structure along the radial of the disk. And it also varies along the height of the disk column. Through optimizing the infiltration conditions, carbon carbon composites in which the rough laminar microstructure predominates can be obtained.