Abrasive compacts

Abstract

Abrasive compacts, in particular ultrahard polycrystalline abrasive compacts, are made under high pressure/high temperature conditions and are characterized in that they include a coarser grained fraction of ultrahard particles distributed non-percolatively throughout a finer grained fraction of ultrahard particles, which may be regarded as a finer grained ultrahard particle matrix, in such a way that the individual coarser grains are largely isolated from one another. It therefore performs as a matrix of highly wear resistant finer grained material interspersed with larger grains, offering a structure that has advantageous wear and impact performance over the behaviours of the two components individually or otherwise combined.

1 . An abrasive compact comprising a first fraction of ultrahard abrasive particles having a coarser average particle grain size and a second fraction of ultrahard abrasive particles having a finer average particle grain size, the first fraction of coarser grained ultrahard abrasive particles being distributed non-percolatively throughout the second fraction of finer grained ultrahard abrasive particles. 
     
     
         2 . The abrasive compact according to  claim 1 , wherein the abrasive compact has an overall average particle grain size of less than 20 μm. 
     
     
         3 . The abrasive compact according to  claim 1 , wherein the first fraction of ultrahard abrasive particles comprises less than about 60% of the abrasive compact. 
     
     
         4 . The abrasive compact according to  claim 3 , wherein the first fraction of ultrahard abrasive particles comprises less than about 55% of the ultrahard abrasive phase of the compact. 
     
     
         5 . The abrasive compact according to  claim 1 , wherein the first fraction of ultrahard abrasive particles comprises greater than about 20% of the ultrahard abrasive phase of the compact. 
     
     
         6 . The abrasive compact according to  claim 1 , wherein the first fraction of ultrahard abrasive particles comprises about 50% of the ultrahard abrasive phase of the compact. 
     
     
         7 . The abrasive compact according to  claim 1 , wherein the average distance, X, between the centres of the respective ultrahard abrasive particles of the first fraction is greater than the average particle diameter D of the respective ultrahard abrasive particles of the first fraction. 
     
     
         8 . The abrasive compact according to  claim 1 , wherein the ratio of the average size of the ultrahard abrasive particles of the first fraction to that of the second fraction is greater than 2:1. 
     
     
         9 . The abrasive compact according to  claim 8 , wherein the ratio of the average size of the ultrahard abrasive particles of the first fraction to that of the second fraction is greater than 3:1. 
     
     
         10 . The abrasive compact according to  claim 1 , wherein the ratio of the average size of the ultrahard abrasive particles of the first fraction to that of the second fraction is less than 10:1. 
     
     
         11 . The abrasive compact according to  claim 10 , wherein the ratio of the average size of the ultrahard abrasive particles of the first fraction to that of the second fraction is less than 6:1. 
     
     
         12 . The abrasive compact according to  claim 11 , wherein the ratio of the average size of the ultrahard abrasive particles of the first fraction to that of the second fraction is less than 5:1. 
     
     
         13 . An abrasive compact comprising ultrahard abrasive particles having an average particle grain size of less than about 10 microns, a first fraction of the ultrahard abrasive particles having a coarser average particle grain size and a second fraction of the ultrahard abrasive particles having a finer average particle grain size, the first fraction of coarser grained ultrahard abrasive particles being distributed non-percolatively throughout the second fraction of finer grained ultrahard abrasive particles. 
     
     
         14 . The abrasive compact according to  claim 13 , wherein the coarser and finer ultrahard abrasive particles are provided in a generally 50/50 mixture, the average particle grain size of the coarser fraction being about 8.5 to 10 μm and that of the finer fraction being about 1.0 to 2.5 μm. 
     
     
         15 . The abrasive compact according to  claim 14 , wherein the average particle grain size of the coarser fraction is about 9.5 μm. 
     
     
         16 . The abrasive compact according to  claim 14 , wherein the average particle grain size of the finer fraction is about 1.5 μm. 
     
     
         17 . The abrasive compact according to  claim 13 , wherein the coarser and finer ultrahard abrasive particles are provided in a generally 50/50 mixture, the average particle grain size of the coarser fraction being about 4 to 6 μm and that of the finer fraction being about 0.5 to 1 μm. 
     
     
         18 . The abrasive compact according to  claim 14 , wherein the average particle grain size of the coarser fraction is about 4.5 μm. 
     
     
         19 . The abrasive compact according to  claim 14 , wherein the average particle grain size of the finer fraction is about 0.7 μm.