Super hard components and powder metallurgy methods of making the same

Abstract

A method of forming a super hard polycrystalline construction comprises forming a liquid suspension of graphene and grains of super hard material, dispersing the graphene and super hard grains in the liquid suspension to form a substantially homogeneous suspension which is dried and from which a pre-sinter assembly is formed and then treated to create a sintered body of polycrystalline super hard material comprising a first fraction of super hard grains and a second fraction of diamond grains, the graphene being at least partially converted to diamond during the sintering stage to form the second fraction. The super hard grains in the first fraction are bonded along at least a portion of the peripheral surface to at least a portion of a plurality of diamond grains in the second fraction, and have a greater average grain size than that of the grains in the second fraction which is between 60 nm to 1 micron.

What is claimed is: 
     
         1 . A method of forming a super hard polycrystalline construction, comprising:
 forming a liquid suspension of a first mass of graphene and a mass of particles or grains of super hard material;   dispersing the graphene and mass of super hard particles or grains in the liquid suspension to form a substantially homogeneous suspension;   drying the suspension to form an admix of the graphene and super hard grains or particles;   forming a pre-sinter assembly comprising the admix;   treating the pre-sinter assembly in the presence of a catalyst/solvent material for the super hard grains at an ultra-high pressure of around 5 GPa or greater and a temperature to sinter together the grains of super hard material to form a body of polycrystalline super hard material comprising a first fraction of super hard grains and a second fraction of diamond grains, the super hard grains exhibiting inter-granular bonding and defining a plurality of interstitial regions therebetween;   the graphene being at least partially converted to diamond during the sintering stage to form the second fraction; wherein   the super hard grains in the first fraction are bonded along at least a portion of the peripheral surface to at least a portion of a plurality of diamond grains in the second fraction;   the super hard grains in the first fraction having a greater average grain size than the average grain size of the grains in the second fraction, the average grain size of the diamond grains in the second fraction being between around 60 nm to around 1 micron.   
     
     
         2 . The method of  claim 1 , wherein the step of providing a mass of super hard material comprises providing a mass of natural and/or synthetic diamond grains, the super hard polycrystalline construction forming a polycrystalline diamond (PCD) construction. 
     
     
         3 . (canceled) 
     
     
         4 . The method of  claim 1 , further comprising treating the super hard construction to remove at least a portion of residual binder/catalyst from at least a portion of interstitial spaces between interbonded super hard grains. 
     
     
         5 . The method of  claim 1 , wherein the step of forming a liquid suspension of a first mass of graphene and a mass of particles or grains of super hard material comprises dispersing the graphene and superhard particles or grains in deionized water. 
     
     
         6 . The method of  claim 1 , wherein the step of forming a liquid suspension of a first mass of graphene and a mass of particles or grains of super hard material comprises dispersing the graphene and superhard particles or grains in an organic solvent. 
     
     
         7 . The method of  claim 6 , wherein the organic solvent comprises ethanol. 
     
     
         8 . The method of  claim 1 , wherein the step of forming a liquid suspension further comprises adding a surfactant to the liquid suspension. 
     
     
         9 . The method of  claim 8 , wherein the surfactant comprises a non-ionic or cationic surfactant. 
     
     
         10 . The method of  claim 1 , wherein the step of dispersing the graphene and mass of super hard particles or grains in the liquid suspension to form a substantially homogeneous suspension comprises applying to the liquid suspension one or more of:
 a sonication process;   an ultrasonic dispersion process;   a homogenization process; and/or a jet milling process.   
     
     
         11 . The method of  claim 1 , wherein the step of dispersing the graphene and mass of super hard particles or grains in the liquid suspension to form a substantially homogeneous suspension comprises adjusting the pH of the liquid suspension to render the suspension acidic to assist in inhibiting agglomeration or aggregation of the graphene. 
     
     
         12 . The method of  claim 1 , wherein the step of drying the suspension to form an admix of the graphene and super hard grains or particles comprises one or more of drying the suspension using freeze drying spray freeze drying, spray drying, spray granulation, and/or spray freeze granulation. 
     
     
         13 . The method of  claim 1 , wherein the graphene has a BET surface area of around 50 m 2 /g or more, or around 100 m 2 /g or more, or around 300 m 2 /g or more, or around 500 m 2 /g or more. 
     
     
         14 . The method of  claim 13 , wherein the average grain size of the super hard grains or particles in the admix is around 6 microns or less, or around 4 microns or less, or around 2 microns or less. 
     
     
         15 . A super hard polycrystalline construction comprising:
 a body of polycrystalline super hard material comprising a first fraction of super hard grains and a second fraction of super hard grains, the first fraction having a greater average grain size than the super hard grains in the second fraction;   the super hard grains in the first and second fraction having a peripheral surface;   
       wherein
 the super hard grains in the first fraction are bonded along at least a portion of the peripheral surface to at least a portion of a plurality of super hard grains in the second fraction; 
 the super hard grains in the second fraction being arranged to space one or more adjacent grains in the first fraction by a distance of between around 60 nm to around 1 micron. 
 
     
     
         16 . (canceled) 
     
     
         17 . The super hard polycrystalline construction of  claim 15 , wherein the body of super hard material comprises inter-bonded super hard grains comprising natural and/or synthetic diamond grains, the super hard polycrystalline construction forming a polycrystalline diamond (PCD) construction. 
     
     
         18 . The super hard polycrystalline construction of  claim 15 , wherein the PCD construction further comprises a non-super hard phase comprising a binder phase located in interstitial spaces between the inter-bonded diamond grains. 
     
     
         19 . The super hard polycrystalline construction according to  claim 18 , 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. 
     
     
         20 .- 22 . (canceled) 
     
     
         23 . The super hard polycrystalline construction according to  claim 15 , wherein at least a portion of the body of super hard material is substantially free of a catalyst material for diamond, said portion forming a thermally stable region. 
     
     
         24 . The super hard polycrystalline construction as claimed in  claim 23 , wherein the thermally stable region comprises at most 2 weight percent of catalyst material for diamond. 
     
     
         25 . The super hard polycrystalline construction of  claim 15 , wherein the first fraction comprises a mass of super hard abrasive grains having two or more different average grain sizes. 
     
     
         26 .- 33 . (canceled)