Diamond synthesis from a system of chromium-carbide and Ni70Mn25Co5 alloy

In order to ascertain the mechanism of interaction between carbide and meta llic catalyst and formation of diamond under high pressure and high tempera ture, and find a new method to synthesize diamond with special properties, it is necessary to investigate the reaction behavior of different carbides and metallic solvent-catalysts under high pressure and high temperature. A system of Cr3C2 powder and Ni70Mn25Co5 alloy in weight ratio of 1:6 was tre ated under 6.0 GPa and 1 500 degrees C for 20, 30 or 60 min respectively. X -ray diffraction of the samples indicated the Cr3C2 decomposed partially af ter high pressure and temperature treatment, and Cr7C3, Cr and diamond form ed respectively. There was not any trace of graphite in the samples. The re sult suggested that the separated carbon atoms could form diamond directly without conversion process of graphite into diamond. The observation of SEI , WDX and EDX also showed that diamond crystals were synthesized in the sys tem, which have perfect surfaces and shapes, with the average grain size of about 40 mu m. The properties of the crystals are being investigated.