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 second phase dispersed in the superhard phase, the superhard phase comprising a plurality of inter-bonded superhard grains. The second phase comprises particles or grains that do not chemically react with the superhard grains, and/or do not inter-grow, and form between around 1 to 30 volume % or wt % of the body of polycrystalline superhard material.

1 . A superhard polycrystalline construction comprising:
 a body of polycrystalline superhard material, the body of polycrystalline superhard material comprising:   a superhard phase, and a second phase dispersed in the superhard phase, the superhard phase comprising a plurality of inter-bonded superhard grains;   wherein the second phase comprises particles or grains that do not chemically react with the superhard grains, and/or do not inter-grow, and form between around 1 to 30 volume % or around 1 to around 30 wt % 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 , further comprising a non-superhard phase comprising 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 of the second phase 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 second phase particles or grains comprise any one or more of an oxide material, a carbide material, alumina, zirconia, yttria, silica, tantalum oxide, cBN, PCBN, hexagonal boron nitride, tungsten carbide, hafnium carbide, zirconium carbide, silicon carbide, or any combination thereof. 
     
     
         7 .- 9 . (canceled) 
     
     
         10 . A superhard polycrystalline construction according to  claim 1 , wherein the second phase particles or grains have a grain size substantially equal to or between around 1.5 to around 3 times the average grain size of the superhard grains. 
     
     
         11 . A superhard polycrystalline construction according to  claim 1 , wherein the second phase particles or grains form between around 1 to around 30 volume % of the body of polycrystalline superhard material. 
     
     
         12 . A superhard polycrystalline construction according to  claim 1 , wherein the second phase particles or grains form between around 5 to around 15 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 superhard polycrystalline construction according to  claim 1 , wherein the second phase particles or granules have a different stiffness and/or fracture toughness than that of the superhard phase. 
     
     
         17 . A method of forming a superhard polycrystalline construction, comprising:
 providing a mass of particles or grains of superhard material;   providing a mass of second phase grains or particles comprising particles or grains of a material that do not chemically react with the superhard grains, and/or do not inter-grow, and form between around 1 to 30 volume % of the body of polycrystalline superhard material;   combining the mass of superhard material and the mass of second phase 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 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 second phase being dispersed in the polycrystalline material and forming between around 1 to around 30 vol % of the body of polycrystalline superhard material, any residual catalyst/solvent at least partially filling a plurality of the interstitial regions.   
     
     
         18 . A method according to  claim 17 , wherein the step of providing a mass of grains of superhard material comprises providing a mass of diamond grains. 
     
     
         19 . A method according to  claim 18 , 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. 
     
     
         20 . The method of  claim 19 , wherein the second fraction has an average grain size between around 1/10 to 6/10 of the size of the first fraction. 
     
     
         21 . The method of  claim 17 , 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. 
     
     
         22 . The method of  claim 19 , 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 %. 
     
     
         23 .- 27 . (canceled) 
     
     
         28 . The method of  claim 19 , wherein the step of providing a mass of grains of superhard material comprises providing three or more grain size modes to form a multimodal mass of grains comprising a blend of grain sizes having associated average grain sizes. 
     
     
         29 . (canceled) 
     
     
         30 . The method of  claim 17 , wherein the step of providing a mass of second phase grains or particles comprises providing second phase particles or grains comprising any one or more of an oxide material, a carbide material, alumina, zirconia, yttria, silica, tantalum oxide, cBN, PCBN, hexagonal boron nitride, tungsten carbide, hafnium carbide, zirconium carbide, silicon carbide, or any combination thereof. 
     
     
         31 . (canceled) 
     
     
         32 . The method of  claim 17 , wherein the step of combining the masses of particles or grains comprises coating the superhard grains or particles with the particles or grains of second phase material which does not chemically react with the particles or grains of superhard material. 
     
     
         33 .- 39 . (canceled)