Abstract: The structural parameters of carbon fiber, pitch-derived carbon and pyrolytic carbon in C/C composites were charaterized by laser Raman microspectroscopy and
XRD. In Raman spectra of these carbons, two bands named D and G were observed near 1336.73cm^-1 and 1581.00cm^-1 respectively, the peak positions do
not but the relative intensities of the two bands change with heat treatment temperatures. The relationship between the XRD data of graphitization degree g
and R^-1 where R is the relative intensity of band D to band G was plotted, the result shows that g increases with the increase of R^-1, but the gradient
of the R^-1-g curve decreases and gradually tends to zero with the increase of R^-1, and their relation can be written into the following equation:
g=1-e^{-2.11(1/R-0.34)}. The foundation of the correlation between R^-1 and g makes it possible to analyze the local distribution of graphitization degree in C/C composites.

Key words: C/C composite, graphitization degree, laser Raman microspectroscopy, XRD