Synthesis of diamond using nano-graphite and Fe powder under high pressure and high temperature

In this paper, a method about the synthesis of diamond using nano-graphite powder as a carbon source was presented. Experiments were carried out with a 6 × 12 MN hexad-top-hydraulic press machine. Nano-graphite, as a carbon source, was prepared by detonation of negative oxygen balance explosives (TNT) in a steel container under vacuum condition. Ni70Mn25Co5 wafers and Fe powders were used as catalysts. In these experiments, the pressure was 5.1 GPa and temperature was varied from 950 to 1330 K. Spherical and granular diamond particles with a size of 5–20 μm were synthesized at the temperature of 1250–1330 K. The granular diamond was clear. The forming mechanism of the diamond and the facts which lead to the change of synthesis condition were discussed. With nano-graphite particles, diamond can be synthesized under lower temperature because of the surface activity of nanometer particles.