Superhard constructions & methods of making same

Abstract

A super hard polycrystalline construction includes a first region having a body of thermally stable polycrystalline super hard material with an exposed surface forming a working surface, and a peripheral side edge. The polycrystalline super hard material has a plurality of intergrown grains of super hard material, a second region forming a substrate to the first region, and a third region interposed between the first and second regions. The third region extends across a surface of the second region along an interface, the third region having a composite material having a first phase comprising a plurality of non-intergrown diamond grains, the majority of said diamond grains having a coating comprising nano-sized cBN particles. There is also disclosed a method of forming such a construction.

1 . A super hard polycrystalline construction comprising:
 a first region comprising a body of thermally stable polycrystalline super hard material having an exposed surface forming a working surface, and a peripheral side edge, said polycrystalline super hard material comprising a plurality of intergrown grains of super hard material;   a second region forming a substrate to the first region; and   a third region interposed between the first and second regions; wherein:   the third region extends across a surface of the second region along an interface, the third region comprising a composite material having a first phase comprising a plurality of non-intergrown diamond grains, the majority of said diamond grains having a coating comprising nano-sized cBN particles.   
     
     
         2 . The super hard polycrystalline construction of  claim 1 , wherein the coatings of the non-intergrown diamond grains of the third region have a thickness of between around 100 nm to around 800 nm. 
     
     
         3 . (canceled) 
     
     
         4 . The polycrystalline super hard construction of  claim 1 , wherein the cBN particles coating the diamond grains in the third region have an average grain size of between around 100 nm to around 200 nm. 
     
     
         5 . The polycrystalline super hard construction of  claim 1 , wherein the composite material of the third region further comprises a second phase. 
     
     
         6 . The polycrystalline super hard construction of  claim 5 , wherein the second phase comprises cBN, and/or WC, and/or wBN. 
     
     
         7 . The polycrystalline super hard construction of  claim 1 , wherein the coated non-intergrown diamond grains comprise between around 20 vol % to around 98 vol % of the third region. 
     
     
         8 . The polycrystalline super hard construction of  claim 1 , wherein the third region further comprises a matrix material comprising any one or more of cobalt, aluminium, and/or nickel, and/or one or more alloys or compounds thereof. 
     
     
         9 . The polycrystalline super hard construction of  claim 1 , wherein the working surface is substantially non-planar. 
     
     
         10 . The polycrystalline super hard construction of  claim 1 , wherein the grains of super hard material of the first region comprise diamond grains, the first region forming a body of polycrystalline diamond material. 
     
     
         11 . (canceled) 
     
     
         12 . The polycrystalline super hard construction of  claim 1 , wherein the composite material of the third region is more acid resistant than polycrystalline diamond material having a binder-catalyst phase comprising cobalt, and/or more acid resistant than cemented carbide material. 
     
     
         13 . The polycrystalline super hard construction of  claim 12 , wherein the composite material of the third region is more resistant to boiling HCl acid than polycrystalline diamond material having a binder-catalyst phase comprising cobalt, and/or more resistant to boiling HCl acid than cemented carbide material. 
     
     
         14 . The polycrystalline super hard construction of  claim 1 , wherein the second region comprises cemented carbide material. 
     
     
         15 . The polycrystalline super hard construction of  claim 14 , wherein the cemented carbide material comprises tungsten carbide particles bonded together by a binder material, the binder material comprising any one or more of Co, Ni, V or Cr, or an alloy thereof. 
     
     
         16 . The super hard polycrystalline construction of  claim 1 , wherein the first region is substantially free of a catalyst material for diamond. 
     
     
         17 . The super hard polycrystalline construction of  claim 1 , wherein the thermally stable first region comprises at most 3 weight percent of inaccessible catalyst material for diamond. 
     
     
         18 . The super hard polycrystalline construction of  claim 1 , wherein the construction has a longitudinal axis, the thickness of the third region along a plane parallel to the longitudinal axis being at least 0.05 mm. 
     
     
         19 . A method of forming a super hard polycrystalline construction comprising:
 forming a pre-sinter assembly comprising:   a first mass of grains or particles of a super hard material;   a source of catalysing material for the first mass of grains or particles of super hard material;   a further mass comprising diamond grains or particles coated with nano-sized cBN particles; and   a mass of grains or particles of a material to form a substrate;   treating the pre-sinter assembly at an ultra-high pressure of around 5 GPa or greater and a temperature to bond together the grains of super hard material in the first mass to form a first region comprising a body of interbonded polycrystalline super hard material bonded to a further region formed of substantially non-interbonded grains or particles of the super hard material in the further mass; the further region being bonded to the substrate along an interface, the further region forming an intermediate region between the first region and the substrate and comprising a diamond composite material comprising a plurality of non-intergrown diamond grains having a coating of nan-sized cBN particles.   
     
     
         20 . The method of  claim 19 , further comprising treating the polycrystalline super hard construction to remove accessible residual catalyst/binder material from interstitial spaces between the interbonded grains of super hard material in the first region. 
     
     
         21 . The method of  claim 19 , wherein the step of forming the pre-sinter assembly comprises:
 providing a mass of diamond grains or particles and/or cubic boron nitride grains or particles to form the first mass of grains or particles of super hard material.   
     
     
         22 . The method of  claim 19 , wherein the step of providing the mass of second phase grains or particles comprises providing a mass of cBN grains, and/or WC grains and/or wBN grains or particles. 
     
     
         23 . The method of  claim 19 , wherein the intermediate region further comprises a matrix material comprising any one or more alloys or compounds of any one or more transition metals including titanium, zirconium, vanadium, hafnium, tantalum, niobium, chromium, molybdenum, tungsten, copper, cobalt, nickel, iron, and/or manganese. 
     
     
         24 . The method of  claim 23 , wherein the one or more alloys or compounds of any one or more of the transition metals comprises oxides, nitrides, carbides, carbonitrides, and/or oxycarbides of said transition metals. 
     
     
         25 . The method of  claim 19 , wherein the matrix material further comprises aluminium, and/or nickel, and/or one or more alloys or compounds thereof. 
     
     
         26 . The method of  claim 19 , wherein the grains of super hard material of the first region comprise diamond grains, the first region forming a body of polycrystalline diamond material.