| 摘要 |
<p>The present invention is directed to an HP/HT process for making polycrystalline CBN particles and compacts from graphitic boron nitride (GBN) (including PBN, HBN, and mixtures) in the substantial absence of bulk catalytically-active material. The inventive process modulates the HP/HT conditions of the process and comprises doping said GBN with between about 0.1 and 50 weight-% of non-BN atoms or clusters thereof, an amount thereof being incorporated into the CBN lattice for at least lowering the pressure required for making said polycrystalline CBN in the absence of said atoms or clusters thereof. The resulting CBN product forms yet another aspect of the present invention. Another technique for moderating the HP/HT conditions in forming CBN comprises coforming GBN atoms or clusters thereof isolated from each other by non-GBN clusters or particles. "Coforming" means that the GBN and non-GBN materials are formed in the stated physical relationship simultaneously or at the same time. Acceptable techniques for this coformation include, for example, chemical vapor deposition, solgel techniques, polymer pyrolysis, and combustion synthesis techniques.</p> |
