Thermal anisotropic composites were fabricated by extrusion of natural graphite powder-pitch precursor mixture, to which 1-2 wt% of chopped carbon fiber was added. The extruded green body was stabilized in an autoclave up to 530 ℃ and carbonized up to 1,000℃. Chopped carbon fibers were aligned along the longitudinal direction by extrusion, and contributed to the enhancement of interfacial adhesion between filler and binder.
Therefore, the mechanical properties such as tensile strength, E-modulus, and flexural strength of composites were increased. Especially the properties of longitudinal direction were increased two or three times than those of transverse direction due to the alignment of chopped carbon fiber.
The thermal conductivity of longitudinal direction was about 12-20 times larger than that of transverse direction in the temperature range of 0-400 ℃ by adding 2 wt% chopped carbon fiber, and the thermal anisotropic factor of composites were varied on the amount of chopped carbon fiber added.