Graphitization and Microstructure of Carbon Fibre-Glassy Carbon Composite

Abstract

The graphitization of furfuryl alchohol condensate mixed with 4.0vol% of carbon fibre was investigated as a function of heat treatment temperature with an aid of optical microscope in polarized light and X-ray diffraction technique.Lamellar structure considered as graphite has evolved microscopically arranging perpendicular to the direction of compressive stress in optically anisotropic matrix heat treated above 2200°C. The X-ray diffraction profile corresponding to the (004) diffraction of graphite was separated into two components with 2d(004)≅3.42 and 3.36 Å. Although the first component showed no remarkable change irrespective of the heat treatment temperature, the second component increased its intensity and decreased its spacing nearly to that of graphite, as the heat treatment temperature was raised. The high angle second component corresponded to the lamellar structure. The stress induced in the matrix near the fibre was roughly estimated as below 5kbar by a calculation based on an assumption that the contraction of the condensate was restrained by the presence of the fibre. This value agreed with the pressure graphitizing glassy carbon, as reported. It was then supposed that the activated stage formed by the stress induced on the carbonization would act as a source for the graphitization of the composite at high temperature.