Superhard constructions and methods of making same

Abstract

A superhard polycrystalline construction comprises a body of polycrystalline superhard material comprising a superhard phase, and a non-superhard phase dispersed in the superhard phase, the superhard phase comprising a plurality of inter-bonded superhard grains. The non-superhard phase comprises particles or grains that do not chemically react with the superhard grains and form less than around 10 volume % of the body of polycrystalline superhard material. There is also disclosed a method of forming such a superhard polycrystalline construction.

1 . A superhard polycrystalline construction comprising: 
       a body of polycrystalline superhard material, the body of polycrystalline superhard material comprising:
 a superhard phase, and a non-superhard phase dispersed in the superhard phase, the superhard phase comprising a plurality of inter-bonded superhard grains; 
 wherein the non-superhard phase comprises particles or grains that do not chemically react with the superhard grains and form less than around 10 volume % of the body of polycrystalline superhard material. 
 
     
     
         2 . A superhard polycrystalline construction according to  claim 1 ,
 wherein the superhard grains comprise natural and/or synthetic diamond grains, the superhard polycrystalline construction forming a polycrystalline diamond construction.   
     
     
         3 . A superhard polycrystalline construction according to  claim 1 , wherein the non-superhard phase further comprises a binder phase. 
     
     
         4 . A superhard polycrystalline construction according to  claim 3 ,
 wherein the binder phase comprises cobalt, and/or one or more other iron group elements, such as iron or nickel, or an alloy thereof, and/or one or more carbides, nitrides, borides, and oxides of the metals of Groups IV-VI in the periodic table.   
     
     
         5 . A superhard polycrystalline construction according to  claim 3 , wherein the particles or grains that do not chemically react with the superhard grains are such that they do not dissolve in the binder phase material and thereby remain unsintered in the body of polycrystalline material and form defects in the polycrystalline material. 
     
     
         6 . A superhard polycrystalline construction according to  claim 1 , wherein the particles or grains that do not chemically react with the superhard grains comprise any one or more of an oxide material, such as an oxide of alumina, zirconia, yttria, silica, or tantalum oxide, or any combination thereof. 
     
     
         7 - 9 . (canceled) 
     
     
         10 . A superhard polycrystalline construction according to  claim 1 , wherein the particles or grains that do not chemically react with the superhard grains have a grain size of around 30% or less of the grain size of the superhard grains. 
     
     
         11 . A superhard polycrystalline construction according to  claim 1 , wherein the particles or grains that do not chemically react with the superhard grains form between around 0.5 to around 5 volume % of the body of polycrystalline superhard material. 
     
     
         12 . A superhard polycrystalline construction according to  claim 1 , wherein the particles or grains that do not chemically react with the superhard grains form between around 0.5 to around 2 volume % of the body of polycrystalline superhard material. 
     
     
         13 . A superhard polycrystalline construction according to  claim 1 , wherein at least a portion of the body of superhard material is substantially free of a catalyst material for diamond, said portion forming a thermally stable region. 
     
     
         14 . A superhard polycrystalline construction as claimed in  claim 13 , wherein the thermally stable region comprises at most 2 weight percent of catalyst material for diamond. 
     
     
         15 . (canceled) 
     
     
         16 . A method of forming a superhard polycrystalline construction, comprising:
 providing a mass of particles or grains of superhard material;   providing a mass of non-superhard grains or particles comprising particles or grains of a material that does not chemically react with the superhard grains having a grain size of less than around 30% the grain size of the superhard material;   combining the mass of superhard material and the mass of non-superhard grains to form a pre-sinter assembly; and   treating the pre-sinter assembly in the presence of a catalyst/solvent material for the superhard grains at an ultra-high pressure of around 5.5 GPa or greater and a temperature at which the superhard material is more thermodynamically stable than graphite to sinter together the grains of superhard material to form a polycrystalline superhard construction, the superhard grains exhibiting inter-granular bonding and defining a plurality of interstitial regions therebetween, the non-superhard phase being dispersed in the polycrystalline material and forming less than around 10 vol % of the body of polycrystalline superhard material, any residual catalyst/solvent at least partially filling a plurality of the interstitial regions.   
     
     
         17 . A method according to  claim 16 , wherein the step of providing a mass of grains of superhard material comprises providing a mass of diamond grains. 
     
     
         18 . A method according to  claim 17 , wherein the step of providing a mass of diamond grains comprises providing a mass of grains having a first fraction having a first average size and a second fraction having a second average size, the first fraction having an average grain size ranging from about 10 to 60 microns, and the second fraction having an average grain size less than the size of the coarse fraction. 
     
     
         19 . (canceled) 
     
     
         20 . The method of  claim 16 , wherein the average grain size of the first fraction is between around 10 to 60 microns, and the average grain size of the second fraction is between about 0.1 to 20 microns. 
     
     
         21 . The method of  claim 18 , wherein the weight ratio of the first fraction to the second fraction ranges from about 50% to about 97%, the weight ratio of the second fraction ranging from about 3% to about 50 weight %. 
     
     
         22 - 28 . (canceled) 
     
     
         29 . The method of  claim 16 , wherein the step of providing a mass of non-superhard grains or particles comprising particles or grains of a material that does not chemically react with the superhard grains comprises providing a mass of material comprising any one or more of an oxide, a carbide, zirconia, alumina, yttria, and tantalum oxide. 
     
     
         30 . The method of  claim 16 , wherein the step of combining the masses of particles or grains comprises admixing the particles or grains. 
     
     
         31 . The method of  claim 16 , wherein the step of combining the masses of particles or grains comprises coating the superhard grains or particles with the particles or grains of non-superhard material which does not chemically react with the particles or grains of superhard material. 
     
     
         32 . The method of  claim 16 , wherein the step of providing the mass of material that does not chemically react with the superhard grains comprises providing grains or particles to form between around 0.5 to 5 vol % of the body of polycrystalline superhard material. 
     
     
         33 - 39 . (canceled)