Research on the Diamond Graphitization Under High Pressure and High Temperature

The graphitization of diamond under high-pressure and high-temperature (HPHT) processes were investigated by the characterization of microstructure, Raman spectroscopy analysis and electrical resistance measurement and found that it was mainly affected by the variables of pressure, temperature and particle size. Finer diamond partials under a higher temperature and a lower pressure tend to be graphitized more, otherwise less. The quantitative analysis of diamond graphitization under different conditions was performed by the peak fitting of Raman spectra. It was found that the diamond to graphitization increases with particle size, and the diamond stress also increases with the particle size. This indicates that the increase in diamond particle size leads to an increase in pressure between diamond particles, which in turn leads to a decrease in the degree of graphitization. This provides some valuable guidance for HPHT parameters choose during the sintering of polycrystalline diamonds.