Graphite-diamond conversion proceeded by the use of carburized cobalt solvent

Cobalt was carburized by CO -treatment and used as solvent metal in graphite-diamond conversion experiments. The products were correlated to those obtained by the usages of untreated solvents. In the case of carburized Co, a fairy amount of small crystals of diamond were found on a metal-graphite boundary and in a metallic portion close to the boundary. Most of the produced crystals exhibited irregular shape but some crystals had well-developed (111) plane. The temperatures for the synthesis were not necessarily high and sufficient to remain in the range below the melting point of metal, indicating that the nucleation and the growth of diamond took place under solid state. When untreated metals were used as the solvents, the yield of diamond after the synthesis was low at these temperature conditions.