Cubic Boron Nitride Compact

Abstract

A polycrystalline cubic boron nitride compact which comprises greater than 75 volume % and not greater than 90 volume % cubic boron nitride particles, the cubic boron nitride particles comprising particles of at least two average particle sizes, and a binder phase constituting the balance of the compact and comprising at least one titanium compound selected from titanium boride, titanium nitride, titanium carbide and titanium carbonitride and at least one aluminium compound selected from aluminium oxide, aluminium boride, aluminium nitride, aluminium carbide and aluminium carbonitride.

1 . A polycrystalline cubic boron nitride compact comprising greater than 75 volume % and not greater than 90 volume % cubic boron nitride particles, the cubic boron nitride particles comprising particles of at least two average particle sizes, and a binder phase constituting the balance of the compact and comprising at least one titanium compound selected from titanium boride, titanium nitride, titanium carbide and titanium carbonitride and at least one aluminium compound selected from aluminium oxide, aluminium boride, aluminium nitride, aluminium carbide and aluminium carbonitride. 
   
   
       2 . The cubic boron nitride compact according to  claim 1  wherein the titanium compound is present in the binder phase in a greater amount, by mass, than that the aluminium compound or compounds. 
   
   
       3 . The cubic born nitride compact according to  claim 1  wherein the titanium compound constitutes at least 80 mass % of the binder phase. 
   
   
       4 . The cubic boron nitride compact according to  claim 1  wherein the titanium is present in the binder phase as titanium carbonitride, titanium nitride or a mixture thereof. 
   
   
       5 . The cubic boron nitride compact according to  claim 1  wherein the aluminium is present in the binder phase as aluminium oxide, aluminium nitride or a mixture thereof. 
   
   
       6 . The cubic boron nitride compact according to  claim 1  wherein the cubic boron nitride particles have a fraction of coarse particles and a fraction of fine particles. 
   
   
       7 . The cubic boron nitride compact of  claim 6  wherein the average particle size of the cubic boron nitride particles in the coarse fraction is at least twice the average particle size of the cubic boron nitride particles in the fine fraction. 
   
   
       8 . The cubic boron nitride compact according to  claim 6  wherein the average particle size of the particles of the coarse fraction is less than 20 microns. 
   
   
       9 . The cubic boron nitride compact according to  claim 6  wherein the average particle size of the particles of the fine fraction is greater than 0.2 microns. 
   
   
       10 . The cubic boron nitride compact according to  claim 8  wherein the average particle size of the fine fraction is greater than 0.2 microns. 
   
   
       11 . The cubic boron nitride compact according to  claim 6  wherein the average particle size of the particles of the coarse fraction is in the range 5 to 12 microns. 
   
   
       12 . The cubic boron nitride compact according to  claim 6  wherein the average particle size of the particles of the fine fraction is in the range 1 to 5 microns. 
   
   
       13 . The cubic boron nitride compact according to  claim 6  wherein the fine fraction comprises 25 volume % to 75 volume % of the cubic boron nitride particles in the compact. 
   
   
       14 . The cubic boron nitride compact according to  claim 6  wherein the fine fraction comprises 30 volume % to 70 volume % of the cubic boron nitride particles in the compact. 
   
   
       15 . The cubic boron nitride compact according to  claim 6  wherein the fine fraction comprises 35 volume % to 60 volume % of the cubic boron nitride particles in the compact. 
   
   
       16 . The cubic boron nitride compact according to  claim 1  wherein the cubic boron nitride is present in an amount of 70 to 85 volume % of the compact. 
   
   
       17 . The cubic boron nitride compact according to  claim 1  wherein the cubic boron nitride is present in an amount of 70 to 80 volume % of the compact. 
   
   
       18 . The cubic boron nitride compact according to  claim 1  wherein:
 the at least two average particle sizes comprises of a coarse fraction and a fine fraction;   the titanium is present in the binder phase as titanium carbonitride;   the aluminium is present in the binder phase as aluminium oxide;   the average particle size of the cubic boron nitride particles in the coarse fraction is at least twice the average particle size of the cubic boron nitride particles in the fine fraction;   the average particle size of the particles of the coarse fraction is in the range 5 to 12 microns; and   the average particle size of the particles of the fine fraction is in the range 1 to 5 microns.