Method of solid PCBN sythesis
The invention generally relates to a sintered CBN composite compact having a non-CBN portion. The compact includes about 86 to about 90% CBN and the non CBN portion contains borides and nitrides of Al. The compact is for use as a cutting tool insert in continuous machining of gray cast iron. The sintered compact has a thermal conductivity of 1.25-4 W/cm/° K. in the temperature range of about 200° C. to about 600° C. and sonic velocity of at least about 14.5 Km/sec at room temperature.
1. A sintered cubic boron nitride composite compact having a non-cBN portion, the compact comprising:
about 86 to about 90 wt. % cBN; and
the non cBN portion consisting essentially of about 10 to about 14 wt.
% A 1 N, A 1 B 2 and other borides of Al;
wherein the compact has a cBN grain size distribution that is at least bimodal and comprises about 80% coarse particles ranging in size from about 10 to about 60 μm and about 20% fine particles ranging in size from about 1 about 12 μm.
2. The sintered cubic boron nitride composite compact according to claim 1 , said compact having a thermal conductivity at room temperature of about 1.25 to about 4 W/cm ° K in the temperature range of about 200° C. to about 600° C.
3. The sintered cubic boron nitride composite compact according to claim 1 , said compact having a sonic velocity of at least about 14.5km/s.
4. The sintered cubic boron nitride composite compact according to claim 1 , wherein said compact comprises a cutting insert for continuous machining of gray cast iron with an aging time of less than about 100hours.