| 摘要 |
PROBLEM TO BE SOLVED: To obtain a cylindrical graphite material having a large diameter and having reduced variations in properties between various parts by placing carbonaceous members between ungraphitized materials to make the thickness of a packing coke layer uniform in a graphitization process of cylindrical materials in an Acheson-type furnace. SOLUTION: This method is suitable for obtaining a cylindrical graphite material having a diameter of >=500 mm, an unevenness in resistivity of <=5% and an unevenness in thermal expansion coefficient of <=5% in a plane perpendicular to the axis. The graphitization is carried out by placing a fired article to be graphitized in an Acheson- type rectangular furnace made of refractory bricks using coke grains as a packing material, followed by directly energizing them in the direction of furnace length to perform graphitization by resistance heating. By placing carbonaceous members 4 together with packing coke 2 between cylindrical materials 1 to be graphitized and by energizing electrodes 3, an electric current uniformly flows through the layer of packing coke 2 and a graphite material having uniform characteristics is obtained. The graphite material shows excellent soaking property in a single crystal puller and a heater because the resistivity is uniform over the entire length and in all directions. homogeneous. |
