Structure change of glass-like carbon with heat treatment, studied by small angle X-ray scattering: I. Glass-like carbon prepared from phenolic resin

For glass-like carbon samples made from phenolic resin at 950 degrees C and thereafter obtained at various heat-treatment temperatures (HTT), structural studies were carried out by means of small angle X-ray scattering (SAXS), The scattering patterns of the samples heat treated at temperatures higher than 1800 degrees C are significantly different from the ones obtained at lower temperatures. The temperature of about 1800 degrees C seems to be a boundary of different carbonization mechanism. Wide angle X-ray scattering (WAXS) experiments were also performed for the same samples. From the SAXS and WAXS results, it is suggested that the carbonization of glass-like carbon (non-graphitizing carbon) occurs in a similar manner as the graphitizing carbon such as coke, though the sizes of the graphite crystallites are different. The increase of HTT causes the ordering of the planes of small graphite crystallites and the growth of closed pores. The Fourier transform analysis shows that glass-like carbon heat-treated at 3000 degrees C has pores which are nearly uniform in size and about 60 Angstrom in diameter.