Patent ID: 7708050

Claim:
A method for producing a composite material having a high thermal conductivity and a small thermal expansion coefficient, comprising the steps of (1) graphitizing an extrudate of carbon particles and/or carbon fibers and tar pitch by burning to thereby obtain a porous graphitized extrudate; (2) impregnating the porous graphitized extrudate with a molten metal at high temperature and pressure wherein said metal is aluminum or an aluminum alloy; and wherein the impregnation of said porous graphitized extrudate with said molten metal is conducted at a temperature higher than the melting point of said molten metal by 10° C. or more and at a pressure of 10 MPa or more to thereby obtain a graphite/metal composite material; and (3) heat-treating the graphite/metal composite material after the molten metal is solidified under the conditions of a temperature-elevating speed of 0.5° C./minute to 30° C./minute, then holding the graphite/metal composite material at a temperature between 200° C. and the melting point—10° C. and thereafter cooling the graphite/metal composite material at a cooling speed of 0.5° C./minute to 20° C./minute, thereby removing thermal hysteresis such that the graphite/metal composite material has a dimensional change ratio within ±0.1% in an extrusion direction and in a direction perpendicular to said extrusion direction.