GRAPHITIZATION AND BEHAVIOR OF SURFACE OX IDE OF C C COMPOSITE/

C/C composites are one of the representative advanced composites, sinc e they have superior mechanical properties(strength to weight ratio, r elative Young high modulus and heat resistance). Many researchers have pointed out so far that their mechanical properties depend on the deg ree of graphitization for their components(matrices and fibers)and the ir precise evaluation techniques are required from the view point of p racticality. Therefore, we investigated the correlation between the de gree of graphitization measured by X-ray Diffraction Analysis(XRD)and the redox behavior of surface oxides measured by Potential Step Chrono amperometry(PSCA). As specimens, three kinds of C/Cs composed of the s ame matrices(pitch type)and different fibers (mesophase pitch type)wer e used basically. In addition, only fibers of each specimen were graph itized at 2773K in advance and also used as specimens to investigate t he effect of fiber indicate that the specimens of pre-treated fibers d eveloped the graphite structure and have high degree of graphitization , since their integrated intensity is higher and their half value widt h is smaller than those of non-treated specimens. The results of PSCA at 0.4V indicate that the quantity of electricity for the formation of phenol-type oxides on the surface decreased with increasing degree of graphitization. On the other hand, PSCA at 0.6 similar to 0.8V indica tes that the quantity of electricity for the formation of carbonyl-typ e oxides had no correlation with the degree of graphitization. However , PSCA on the reduction side(from 0.8V to 0.4V and from 0.8V to 0.6V)i ndicates that the quantity increased with the degree of graphitization .