| 摘要 |
Diamond is produced by passing a direct electric current through a mass of raw material, which comprises raw carbon and a catalyst, while maintaining the system at 1000-2000 DEG C. and 50,000-100,000 kg./cm.2 pressure, the flow of the electric current being reversed to effect a second synthesising stage under similar conditions. The pressure may be increased by about 5000 kg./cm.2 after the first stage to inhibit transformation of diamond back to carbon during the second stage. The heating can be entirely by passage of the direct current through the material but may, in part, be by passage of a direct or alternating current through a heating resistance surrounding the raw material. The first stage may, for example, be carried out under a pressure of 65,000 kg./cm2. at a temperature of 1500 DEG C. with the pressure being increased to 70,000 kg./cm.2 upon reversal of the current for the second stage. |
