Densification and Surface Carbon Transformation of Diamond Powders under High Pressure and High Temperature.

A new type of poly-diamond plate without a catalyst was produced via the high-pressure high-temperature (HPHT) compression of diamond powders. The densification of diamond powders and sp to sp carbon on the surface under HPHT compression was investigated through the characterization of the microstructure, Raman spectroscopy analysis and electrical resistance measurement. The densification and sp-sp transformation on the surface are mainly affected by the pressure, temperature and particle size.