| 摘要 |
1,147,456. Isotropic graphite. UNITED KINGDOM ATOMIC ENERGY AUTHORITY 8 Aug., 1966 [9 Aug., 1965], No. 34080/65. Heading C1A. Isotropic graphite is made by tumbling graphitic granules with smaller anisotropic grains and pressing the larger particles formed by snowballing into a coherent body. Suitable grains are made by graphitizing at 2,600‹ C. a calcined anisotropic petroleum coke crushed to below 50Á, mixing this graphitized material with a solution of phenol-formaldehyde resin and crushing and sieving the dried product to below 76Á. A stream of these prepared grains is sprayed with a solvent for the resin just prior to falling into a tumbling mass of granules, e.g. anisotropic graphite ground to 500Á. A charge of the "balls" formed is pressed at 2,000 p.s.i. whilst simultaneously being heated to polymerize the binder and, after removal from the pressing die, is baked in a gas stream to 850‹ C. and degassed under vacuum at 1,800‹ C. In a modification carbonaceous material such as calcined or non-calcined coke, is used for the grains, the granules, or both, and the balls formed are pressed into a coherent body which is then heated to graphitization.
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