Improved Processing of Carbon-Carbon Composites.

Abstract : The objectives of this research program were to investigate the use of a catalyst to increase the char yield of petroleum pitch and thus increase the processing efficiency of carbon-carbon composites, and to investigate the use of an alternate pitch that forms a fine-isotropic matrix microstructure which may improve the interlaminar shear strength of bidirectional carbon-carbon composites. After the first carbonization and heat-treatment cycle, the composite with A240 petroleum-pitch matrix precursor with 20 w/o AlCl3 had a 4 percent higher bulk density. The composite with a fine-isotropic matrix microstructure from a thermal pitch from vacuum-distilled bottoms did not have higher interlaminar shear strength. This matrix was more viscous and did not infiltrate well the fiber bundles through which the shear fracture occurred. Further work is needed to better understand the relationships between char yield, viscosity, and microstructure, and to optimize these properties of the pitch matrix precursors. Keywords: Carbonaceous mesophase; Densification. (Author)