Superhard constructions & methods of making same

Abstract

A superhard polycrystalline construction ( 1 ) comprises a body ( 12 ) of polycrystalline superhard material having a cutting face ( 14 ) and a substrate ( 10 ) bonded to the body of polycrystalline superhard material along an interface ( 18 ). The substrate comprises a substrate body and a first end surface ( ) 20 forming the interface, the first end surface of the substrate comprising a projection extending from the body of the substrate into the body of superhard material towards the cutting face. The projection has an outer peripheral surface around which the body of polycrystalline superhard material extends. The body of polycrystalline superhard material has a thickness (h) from the cutting face along the peripheral side edge ( 13 ) to the interface with the substrate of at least around 4 mm and at least a portion of the projection has a thickness measured in a plane extending along the longitudinal axis of the construction of at least around 4 mm. There is also disclosed a method of making such a superhard polycrystalline construction.

1 . A superhard polycrystalline construction comprising:
 a body of polycrystalline superhard material having a cutting face; and   a substrate bonded to the body of polycrystalline superhard material along an interface;   the construction having a central longitudinal axis extending therethrough and a peripheral side edge; wherein:   the substrate comprises a substrate body and a first end surface forming the interface, the first end surface of the substrate comprising a projection extending from the body of the substrate into the body of superhard material towards the cutting face, the projection having an outer peripheral surface, the body of polycrystalline superhard material extending around the peripheral outer surface of the projection;   wherein the body of polycrystalline superhard material has a thickness from the cutting face along the peripheral side edge to the interface with the substrate of at least around 4 mm; and   wherein at least a portion of the projection has a thickness measured in a plane extending along the longitudinal axis of the construction of at least around 4 mm.   
     
     
         2 . The superhard polycrystalline construction of  claim 1 , wherein the projection from the substrate extends to and forms part of the working face. 
     
     
         3 . The superhard polycrystalline construction of  claim 1 , wherein the projection from the substrate extends to a distance of around 0.5 mm or less from the cutting face. 
     
     
         4 . The superhard polycrystalline construction of  claim 1 , wherein the body of polycrystalline superhard material comprises natural and/or synthetic diamond grains, and/or cubic boron nitride grains. 
     
     
         5 .- 10 . (canceled) 
     
     
         11 . The superhard polycrystalline construction of  claim 1 , wherein the body of superhard material comprises polycrystalline diamond material having interbonded diamond grains and interstices therebetween; 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. 
     
     
         12 . The superhard polycrystalline construction of  claim 11 , wherein the depth of the thermally stable region from the cutting face along the peripheral side edge is at least around 3.5 mm or greater. 
     
     
         13 . The superhard polycrystalline construction of  claim 11 , wherein the depth of the thermally stable region from the cutting face along the peripheral side edge is at least around 4.5 mm or greater. 
     
     
         14 . The superhard polycrystalline construction of  claim 1 , further comprising a protective layer over at least a portion of the cutting face. 
     
     
         15 . (canceled) 
     
     
         16 . The superhard polycrystalline construction of  claim 1 , further comprising one or more interlayers bonded between at least a portion of the substrate and the body of superhard material. 
     
     
         17 . The superhard polycrystalline construction of  claim 16 , wherein the one or more interlayers differ from one or other or both of the other interlayers and/or the body of superhard material in grain size and/or composition. 
     
     
         18 . The superhard polycrystalline construction of  claim 16 , wherein one or more of the interlayers comprise(s) one or more of a mixture of WC and diamond powder(s), a mixture of cBN and diamond powder(s), and/or a mixture of refractory metal(s) and hard material powders, the hard material powders comprising one or more of tungsten, vanadium or molybdenum. 
     
     
         19 . (canceled) 
     
     
         20 . The superhard polycrystalline construction of  claim 1 , wherein the projection comprises a planar central portion spaced from the body of the substrate by an interconnecting surface. 
     
     
         21 . (canceled) 
     
     
         22 . The superhard polycrystalline construction of  claim 20 , wherein the interconnecting surface is concave. 
     
     
         23 . The superhard polycrystalline construction of  claim 22 , wherein the interconnecting surface extends from the planar central section to the peripheral side edge of the construction. 
     
     
         24 . (canceled) 
     
     
         25 . The superhard polycrystalline construction of  claim 20 , wherein the interconnecting surface comprises a first portion extending from the planar central section to a position spaced from the peripheral side edge of the construction, the interconnecting surface further comprising a second portion extending from the first portion to the peripheral side edge, the projection being substantially frustro-conical in shape. 
     
     
         26 . The superhard polycrystalline construction of  claim 25 , wherein the second portion forms a shoulder portion having a length of up to around 3 mm. 
     
     
         27 . The superhard polycrystalline construction of  claim 25 , wherein the peripheral outer surface of the projection is inclined at an angle of up to around 15 degrees from the central longitudinal axis. 
     
     
         28 . The superhard polycrystalline construction of  claim 1 , wherein the body of polycrystalline superhard material comprises an annular portion extending around the peripheral outer surface of the projection. 
     
     
         29 . The superhard polycrystalline construction of  claim 28 , wherein the annular portion is continuous around the outer peripheral surface of the projection. 
     
     
         30 . The superhard polycrystalline construction of  claim 28 , wherein the annular portion is discontinuous around the outer peripheral surface of the projection. 
     
     
         31 .- 62 . (canceled)