Superhard construction

Abstract

The present disclosure generally relates to constructions including a body of polycrystalline diamond (PCD) material attached to a substrate.

1 . A superhard construction comprising:
 a layer of superhard material;   a substrate attached to the layer of superhard material along an interface and formed of a material having a coefficient of thermal expansion; and   a region of material in the substrate having a different coefficient of thermal expansion to the coefficient of thermal expansion of the material forming the substrate;   wherein the region of material comprises a solid of revolution about an axis of symmetry or a partial solid of revolution; and   wherein the region has a point, edge or face in contact with or extending to the layer of superhard material and/or a peripheral surface of the superhard construction.   
     
     
         2 . A superhard construction according to  claim 1 , wherein the superhard material comprises polycrystalline diamond material or polycrystalline cubic boron nitride. 
     
     
         3 . A superhard construction according to  claim 1 , wherein the substrate is formed of a carbide selected from the group comprising tungsten carbide, niobium carbide, zirconium carbide, hafnium carbide, vanadium carbide, tantalum carbide and titanium carbide. 
     
     
         4 . A superhard construction according to  claim 1 , further comprising two or more regions of material having a different coefficient of thermal expansion to the coefficient of thermal expansion of the substrate, one or more of said regions having the same or different coefficients of thermal expansion to others of said regions. 
     
     
         5 . A superhard construction according to  claim 1 , wherein one or more regions of material have a lower coefficient of thermal expansion than the material forming the substrate. 
     
     
         6 . A superhard construction according to  claim 1 , wherein one or more of the regions of material comprise one or more of a cylinder, a conical section, a frusto-conical section, an ovoid, an annulus, or partial sections thereof. 
     
     
         7 . A superhard construction according to  claim 1 , wherein the PCD construction has a longitudinal axis and wherein one or more of the one or more regions of material have an axis of symmetry coaxial with the PCD construction. 
     
     
         8 . A superhard construction according to  claim 1 , wherein the PCD construction has a longitudinal axis and wherein one or more of the one or more regions of material have an axis of symmetry offset from the longitudinal axis of the PCD construction. 
     
     
         9 . A superhard construction according to  claim 8 , wherein one or more of the one or more regions of material have an axis of symmetry spaced from and non-parallel to the longitudinal axis of the PCD construction. 
     
     
         10 . A superhard construction according to  claim 1 , comprising a plurality of said regions of material, one or more regions abutting a further one or more regions. 
     
     
         11 . A superhard construction according to  claim 10 , wherein one of said plurality of regions is located radially within a further of said regions. 
     
     
         12 . A superhard construction comprising:
 a layer of superhard material;   a substrate attached to the layer of superhard material along an interface and formed of a material having a coefficient of thermal expansion;   a region of material in the substrate having a different coefficient of thermal expansion to the coefficient of thermal expansion of the material forming the substrate;   wherein the superhard construction has a longitudinal axis;   wherein the region of material comprises a solid of revolution about an axis of symmetry or a partial solid of revolution about an axis of symmetry, said region of material having a different coefficient of thermal expansion to the coefficient of thermal expansion of the material forming the substrate; and   and   wherein the axis of symmetry of the solid or partial solid of revolution is offset from the longitudinal axis of the superhard construction and not parallel to said longitudinal axis.   
     
     
         13 . A superhard construction comprising:
 a layer of superhard material;   a substrate attached to the layer of superhard material along an interface and formed of a material having a coefficient of thermal expansion;   one or more regions of material in the substrate having different coefficient(s) of thermal expansion to the coefficient of thermal expansion of the material forming the substrate;   wherein one or more of the regions of material comprise one or more annuli.   
     
     
         14 . A superhard construction according to  claim 1 , said region or one or more regions of material in the substrate having different coefficients of thermal expansion to the coefficient of thermal expansion of the substrate extend(s) into the layer of superhard material and into the substrate, one or more of said regions comprising a solid of revolution about an axis of symmetry or a partial solid of revolution about an axis of symmetry. 
     
     
         15 . A superhard construction according to  claim 12 , wherein the one or more regions of material have a lower coefficient of thermal expansion than the material forming the substrate. 
     
     
         16 . A superhard construction according to  claim 12 , wherein one or more of the regions has a point, edge or face in contact with or extending to the layer of superhard material and/or a peripheral surface of the superhard construction. 
     
     
         17 . A superhard construction according to  claim 12 , wherein the superhard material comprises polycrystalline diamond material or polycrystalline cubic boron nitride. 
     
     
         18 . A superhard construction according to  claim 12 , wherein one or more of the regions of material comprise one or more of a cylinder, a conical section, a frusto-conical section, an ovoid, an annulus, or partial sections thereof. 
     
     
         19 . A superhard construction according to  claim 12 , comprising a plurality of said regions of material, one or more regions abutting a further one or more regions. 
     
     
         20 . A superhard construction according to  claim 19 , wherein one of said plurality of regions is located radially within a further of said regions. 
     
     
         21 . A superhard construction according to  claim 12 , wherein the PCD construction has a longitudinal axis and wherein one or more of the one or more regions of material have an axis of symmetry offset from the longitudinal axis of the PCD construction. 
     
     
         22 . A superhard construction according to  claim 12 , wherein one or more of the one or more regions of material have an axis of symmetry spaced from and non-parallel to the longitudinal axis of the PCD construction.