Diamond-based superhard composites: new synthesis approaches and application prospects

We discuss experimental results on high-pressure and high-temperature (HPHT) synthesis of diamond-like cubic boron nitride (cBN) and diamond with a high concentration of point defects. The presence of active fluids allows obtaining cBN with a carbon content up to 10%. The concentration of boron in the diamond lattice is about 2%, and that of vacancies is two times higher. The concentration and positions of substitution atoms were determined by the Rietveld refinement method. Diamond micropowder reactive sintering with fluid phases was used to synthesize new superhard composites. The microstructure and grain boundaries were investigated by transmission and scanning electron microscopy. Tests of the wear resistance of the new diamond-cBN composites demonstrated that these materials offer good prospects for various applications.