Ultrahard Composite Materials

摘要

The present invention concerns a method of producing an ultrahard abrasive composite material having a desirable overall thermal expansion coefficient mismatch, between the ultrahard particles and their matrix materials. The method includes the steps of providing a volume fraction of ultrahard particles having a pre-determined thermal expansion coefficient; determining the volume fraction and thermal expansion coefficient of a matrix material that would be required to produce an ultrahard composite material having a desired overall thermal expansion coefficient mismatch; contacting the ultrahard particles and the matrix material to form a reaction volume; and consolidating and sintering the reaction volume at a pressure and a temperature at which the ultrahard particles are crystallographically or thermodynamically stable. Ultrahard composites where the ultrahard particles are cubic boron nitride and/or diamond are provided, with matrix materials chosen to produce thermal expansion mismatches within specific value ranges, and associated, controlled residual stresses. Ultrahard composite matrices involving combinations of nitride matrices such as titanium nitride/tantalum nitride, and titanium nitride/chromium nitride are exemplified.