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 nano-sized super hard particles and particles of super hard material having an average particle or grain size of 1 or more microns, dispersing the particles in the liquid suspension to form a substantially homogeneous suspension which is then dried and sintered to form a body of polycrystalline super hard material comprising a first and second fractions of super hard grains, the nano-sized particles forming the second fraction. The super hard grains in the first fraction are bonded along at least a portion of the peripheral surface(s) thereof to at least a portion of a plurality of nano-sized grains in the second fraction, the grains in the first fraction having a greater average grain size than that of the grains in the second fraction which is less than 999 nm, the average grain size of the first fraction being around 1 micron or more

What is claimed is: 
     
         1 . A method of forming a super hard polycrystalline construction, comprising:
 forming a liquid suspension of a first mass comprising nano-sized super hard particles and a mass of particles or grains of super hard material having an average particle or grain size of 1 or more microns;   dispersing the first mass 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 first mass and the 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 super hard grains, the super hard grains exhibiting inter-granular bonding and defining a plurality of interstitial regions therebetween, the nano-sized particles forming the second fraction of super hard grains; wherein   the super hard grains in the first fraction are bonded along at least a portion of the peripheral surface(s) thereof to at least a portion of a plurality of nano-sized 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 grains in the second fraction being less than around 999 nm and the average grain size of the grains of superhard material in the first fraction being around 1 micron or more.   
     
     
         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, the nano-sized particles or grains comprising nanodiamond. 
     
     
         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 the liquid suspension comprises dispersing the nano-sized particles or grains and the super hard 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 nano-sized particles or grains and a mass of particles or grains of super hard material comprises dispersing the 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 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 drying the suspension to form an admix of the 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. 
     
     
         12 . The method of  claim 1 , wherein the average grain size of the nano-sized grains or particles in the admix is around 999 nm or less, or around 500 nm or less, or around 250 nm or less, or around 100 nm or less. 
     
     
         13 . The method of  claim 1 , wherein the first mass comprises polycrystalline nano-diamond material. 
     
     
         14 . 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 less than around 999 nm; and   wherein the average grain size of the super hard grains in the first fraction is around 1 micron or more.   
     
     
         15 . (canceled) 
     
     
         16 . The super hard polycrystalline construction of  claim 1 , wherein the grains in the first and second fraction comprise natural and/or synthetic diamond grains, the super hard polycrystalline construction forming a polycrystalline diamond (PCD) construction. 
     
     
         17 . The super hard polycrystalline construction of  claim 16 , 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. 
     
     
         18 . The super hard polycrystalline construction according to  claim 17 , 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. 
     
     
         19 - 21 . (canceled) 
     
     
         22 . The super hard polycrystalline construction according to  claim 14 , 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. 
     
     
         23 . The super hard polycrystalline construction as claimed in  claim 22 , wherein the thermally stable region comprises at most 2 weight percent of catalyst material for diamond. 
     
     
         24 . The super hard polycrystalline construction of  claim 14 , wherein the first fraction comprises a mass of super hard abrasive grains having two or more different average grain sizes. 
     
     
         25 . The super hard polycrystalline construction of  claim 14 , wherein the super hard grains in the second fraction are arranged to space one or more adjacent grains in the first fraction by a distance of less than around 500 nm, or less than around 250 nm, or less than around 100 nm. 
     
     
         26 - 32 . (canceled)