Abstract: A sintered polycrystalline compact of cubic boron nitride is made by first forming a mixture of about 30 to 60 percent by weight cubic boron nitride, up to about 50 percent by weight hexagonal boron nitride, and from about 2 to 7 percent by weight adjuvant materials, or sintering aids, comprising an aluminum containing material selected from the group consisting of aluminum, aluminum nitride, or aluminum diboride, and up to 50 percent by weight of nitride, carbide, or carbonitride binder material containing a group IVb, Vb, or VIb transition metal. The mixture of cBN crystals, hBN and other materials is compacted into a preform and subjected to heat treatment in a non-oxidizing atmosphere. The preform is placed onto a cemented tungsten-carbide/cobalt substrate and subjected to elevated pressure and temperature conditions at which cubic boron nitride is thermodynamically stable.

Abstract: A sintered polycrystalline compact of cubic boron nitride is made by forming a mixture of about 45 to 65 percent by weight cubic boron nitride (cBN), from about 30 to 45 percent by weight hexagonal boron nitride (hBN), and from about 2 to 7 percent by weight an aluminum containing material, preferably aluminum nitride, and cobalt aluminide having a melting temperature lower than the melting temperature of cobalt phase. The mixture of cBN crystals, hBN and adjuvant materials is compacted into preforms and subjected to heat treatment in a non-oxidizing atmosphere. The preforms are placed onto a cemented tungsten carbide substrate containing cobalt and subjected to elevated pressure and temperature conditions at which the boron nitride is thermodynamically stable. The elevated pressure and temperature conditions are maintained for a time sufficient to permit the infiltration of a cobalt phase into the cBN matrix and sinter the compact.

Abstract: Abrasive compacts are described which comprise a support mass having abrasive masses bonded to each of the upper and lower surfaces of said support mass. Preferably, the abrasive masses are diamond or cubic boron nitride and the support mass is a sintered carbide. Bonding of the abrasive masses to the support mass preferably is accomplished by a high pressure, high temperature process.