The Synthesis Of Near Perfect Octahedral Cubic Boron Nitride Under High Pressure And High Temperature

Cubic boron nitride (cBN) has eAcellent properties such as high thermal conductivity and chemical inertness against ferrous metals, wide band gap and high temperature semiconductors, machining ferrous materials and so on. cBN has attracted worldwide interst as a functional material.Generally, cBN crystal is synthesized from hBN with the solvent/catalysts at high temperature and high pressure (HT-HP).In all factors to affect the quality of man-made cubic boron nitride crystal, catalysts are the most important. Based on the solvent theory of synthesis cubic boron nitride and combining with the characters of A catalysts, we use the technologe which is"twice boosting pressure"method to synthesize cubic boron nitride in HPHT. The effects of the main parameters such as waiting time and step pressure, etc, on the cBN with octahedral morphologe.The results indicate that, under the same conditions, the nucleus of cBN crystal and output decrease with the waiting time increasing. The crystal shape becomes more integrity follow the eAtending of waiting time. The higher step pressures the more nucleuses.Based on the work, we found the best technologe for synthesizing cubic boron nitride by A catalysts. A near perfect octahedral cBN crystal with 0.1 mm～0.4 mm was synthesized. The eAperimental results prove that this technologe is effective for the high-grade cBN crystals.The chemical property of A is veryactive and it can easily react with the atmosphere. So the character of catalyst would changein the application. According to A's character of easily reacting with the atmosphere, we studied the influence of Li 2 O and LiOH on the nucleation of cBN. The results indicate that, they operate negative for synthesis of near perfect octahedral cBN.