In this study, porosity and graphitizability of coal tar pitch with the tre
atment pressure were investigated. 4-directional carbon/carbon composites (
4D C/C) were made from the matrix precursor of coal tar pitch through the p
rocess of impregnation and carbonization. Then the effects of applied press
ure during the densification on the composites were observed. The matrix pi
tch which had 600 bar applied during the carbonization process had one and
a half times less pore area ratio than that treated at 1 bar. When the pitc
h was heat treated up to 2300 degrees C after the high pressure carbonizati
on, the degree of graphitization was improved on a small scale and the crys
tal size tended to reduce. As the applied pressures to 4D C/C composites in
creased from 1 to 600 bar, the densification ratio was greatly improved. In
the pore size distribution of the 4D C/C composites, the macropore portion
was decreased while the mesopore portion increased, when high pressures we
re applied. (C) 1999 Kluwer Academic Publishers.