Polycrystalline diamond

Abstract

The invention relates to a polycrystalline diamond (PCD) body comprising PCD material having a graphitisation onset temperature, the PCD body having a working surface and comprising a first region remote from the working surface, the first region containing a catalysing material; and a second region extending a depth from the working surface into the PCD body, the second region being substantially free of catalysing material; the depth having a thermal gradient characteristic that when the temperature at the working surface is 900 degrees centigrade, the temperature at the depth is in the range from 780 degrees centigrade to 850 degrees centigrade and to inserts, machine tools and drill bits comprising the PCD body.

1 . A polycrystalline diamond (PCD) body comprising PCD material having a graphitisation onset temperature, the PCD body having a working surface and comprising a first region remote from the working surface, the first region containing catalysing material; and a second region extending a depth from the working surface into the PCD body, the second region being substantially free of catalysing material; the depth having a thermal gradient characteristic that when the temperature at the working surface is 900 degrees centigrade, the temperature at the depth is in the range from 780 degrees centigrade to 850 degrees centigrade. 
     
     
         2 . A PCD body as claimed in  claim 1 , in which the temperature at the depth in the range from 800 degrees centigrade to 820 degrees centigrade. 
     
     
         3 . A PCD body as claimed in  claim 1 , in which the temperature at the depth is within 10 degrees centigrade eitherside of the graphitisation onset temperature. 
     
     
         4 . A PCD body as claimed in  claim 1 , in which the depth is in the range from 20 to 90 microns from the working surface. 
     
     
         5 . A PCD body as claimed in  claim 1 , in which the bonded diamond grains have a size distribution in which more than one peak or mode is evident. 
     
     
         6 . A PCD body as claimed in  claim 1 , in which bonded diamond grains of PCD body have a size distribution characteristic that at least 20% of the grains have an average size greater than 10 microns, and at least 10% of the grains have an average size in the range from 10 to 20 microns. 
     
     
         7 . A PCD body as claimed in  claim 1 , in which the bonded diamond grains have an average size in the range from 5 microns to 20 microns. 
     
     
         8 . An insert for a machine tool or drill bit, comprising a PCD body as claimed in  claim 1 . 
     
     
         9 . A machine tool or drill bit comprising an insert as claimed in  claim 8 .