Experimental Study on the Polycrystal Diamond Synthesis from Graphite by Multiple Shock-Compressions

Pure graphite powders were subjected to single to fourfold shock-compressions by use of an explosively driven metal flyer impacting onto the recovery capsule, and polycrystal cubic diamond of high purity and with regular morphology was synthesized from the graphite under pressures from 24 to 37 GPa. Conversion ratio from graphite and particle size of diamond displayed an increased trend with the compression times. When the particle size of diamond is greater than about 100 m, however, it is easily to be fractured if the shock pressure is high (over 20 GPa) while the temperature is low (below 1 000 K).