A rock removal body

Abstract

A rock removal body comprises a PCD material ( 601 ) bonded to a substrate ( 602 ) along an interface. The body is of right circular cylindrical shape and the PCD material has a thickness ( 607 ) from the circumferential edge axially along the surface of the barrel portion of around 3 mm or greater, and a functional working volume ( 606 ) having a maximum extent such that the final wear surface does not intersect the interface of the PCD material volume and the substrate. The PCD material volume comprises a diamond network and a metallic component forming a metallic network, the substrate comprises a cementing metal, the metallic component and the cementing metal being independent of one another, independently derived, have not interacted during the high pressure high temperature manufacturing process, are measurably distinguishable and are preselected to be different with respect to their alloy composition. The PCD material encompasses the functional working 609 volume and is homogeneous.

1 . A rock removal body for a drag bit rock drilling application comprising a polycrystalline diamond (PCD) material volume bonded to a cemented hard metal substrate along an interface; wherein:
 a. the body has an overall body volume, and is of a right circular cylindrical shape having a circumferential edge, and a barrel portion, the PCD material volume being axially asymmetrically disposed at one end of the body;   b. the PCD material volume has a thickness from the circumferential edge axially along the surface of the barrel portion of around 3 mm or greater and a functional working volume, the functional working volume being the volume of PCD material progressively worn away in use during useful life of the rock removal body to a form a final wear surface, the functional working volume having a maximum extent such that the final wear surface does not intersect the interface of the PCD material volume and the substrate;   c. the interface bonding the polycrystalline diamond material volume to the cemented hard metal substrate comprising a layer of a third material derived from a refractory material, the third material being a metal diffusion blocking barrier material to molten bonding material of the substrate and molten catalyst solvent sintering aid of the PCD material volume during formation of the rock removal body;   d. the PCD material volume comprising a plurality of inter-bonded diamond grains having an average diamond grain size forming a diamond network and a metallic component forming a metallic network, and the substrate comprising a cementing metal, the metallic component and the cementing metal being independent of one another, independently derived, have not interacted during the high pressure high temperature manufacturing process, are measurably distinguishable and are pre-selected to be different with respect to their alloy composition;   e. the PCD material at least encompasses the functional working volume and is homogeneous in that the PCD material is spatially constant and invariant with respect to diamond network to metallic network volume ratio, wherein the homogeneity is measured at a scale greater than ten times the average diamond grain size, the maximum diamond grain size in the diamond network being less than three times the average diamond grain size.   
     
     
         2 . The rock removal body of  claim 1 , wherein the PCD material volume has a thickness and the substrate has a length along the barrel portion, wherein the ratio of the PCD thickness to the substrate length measured along the barrel portion of the cylinder, is always less than 1.0 and the volume of PCD material in the rock removing body is less than about 50 percent of the overall body volume. 
     
     
         3 . The rock removal body of  claim 2 , wherein the body has a base formed by a free face of the substrate, and wherein the PCD material volume is a cylindrical layer having a thickness of about 3 mm or greater, the thin layer of third material forming the interface between the PCD material volume and the substrate having a thickness, wherein the combined thickness of the thin layer forming the interface and the length of the substrate is about 8 mm or greater, the thin layer forming the interface being substantially flat, substantially planar and substantially parallel to the base of the body. 
     
     
         4 . The rock removal body of  claim 3 , wherein the body has a diameter in the range of about 12 mm to about 20 mm, and the body has an overall length measured along the barrel portion in the range of about 11 mm to about 20 mm. 
     
     
         5 . The rock removal body of  claim 1 , wherein the PCD material which at least encompasses the functional working volume has an average grain size of less than about 10 microns and a metal content in the range of about 5 to about 9 volume percent. 
     
     
         6 . A rock removal body for a roller cone bit rock drilling application comprising a polycrystalline diamond (PCD) material volume bonded to a cemented hard metal substrate along an interface; wherein:
 a. the body comprises a right circular cylinder portion having an associated radius, one end of the cylinder portion forming a generally convex curved surface or surfaces with an apex, or one end forming a general chisel shape where two or more flat surfaces meet to form an apex, the PCD material volume being axially asymmetrically disposed extending from and abutting the apex, the cemented hard metal substrate being disposed at the opposite end of the cylinder;   b. the PCD material volume has a thickness from the apex in the axial direction of the cylinder portion of the body to the interface with the substrate equal to or greater than the radius of the cylinder portion of the body, the PCD material volume further comprising a functional working volume, the functional working volume being the volume of PCD material progressively worn away in use during useful life of the rock removal body to a form a final wear surface, the functional working volume having a maximum extent such that the maximum extent of the functional working volume is less than the thickness of the PCD material volume thickness; the functional working volume extending from the apex in the axial direction;   c. the interface bonding the PCD material volume to the substrate comprising a thin layer of a third material derived from a refractory material, the third material being a metal diffusion blocking barrier material to molten bonding material of the substrate and molten catalyst solvent sintering aid of the PCD material volume during formation of the rock removal body;   d. the PCD material volume comprising a plurality of inter-bonded diamond grains having an average diamond grain size forming a diamond network and a metallic component forming a metallic network, and the substrate comprising a cementing metal, the metallic component and the cementing metal being independent of one another, independently derived, have not interacted during the high pressure high temperature manufacturing process, are measurably distinguishable and are pre-selected to be different with respect to their alloy composition;   e. the PCD material at least encompasses the functional working volume and is homogeneous in that the PCD material is spatially constant and invariant with respect to diamond network to metallic network volume ratio, wherein the homogeneity is measured at a scale greater than ten times the average diamond grain size, the maximum diamond grain size in the diamond network being less than three times the average diamond grain size.   
     
     
         7 . The rock removal body of  claim 6 , wherein the generally convex curved surface or surfaces comprising the apex is any one of hemi-spheroidal, prolate hemi-spheroidal, oblate hemi-spheroidal, or hemispherical; wherein the body comprises a shoulder formed by the line of departure of the barrel portion extending into the generally convex curved surface; and wherein the thin layer of the third material forming the interface between the PCD material volume and the substrate intersects the barrel portion below the shoulder. 
     
     
         8 . The rock removal body of  claim 7 , wherein the generally convex curved surface is hemispherical, the radius of the cylinder portion of the body being around 8 mm. 
     
     
         9 . The rock removal body of  claim 6 , wherein the generally convex curved surface is a cone having a rounded apex, wherein the rounded apex has an associated radius, the radius of the rounded apex being between around a quarter to around a half of the radius of the cylinder portion of the body, wherein the body comprises a shoulder formed by the line of departure of the barrel portion extending into the generally convex curved surface; and wherein the thin layer of the third material forming the interface between the PCD material volume and the substrate intersects the barrel portion below the shoulder. 
     
     
         10 . The rock removal body of  claim 9 , wherein one end of the body forms a chisel shape comprising a conical surface with a rounded apex modified by two symmetrical inclined flat surfaces which meet at the rounded apex, wherein the body comprises a shoulder formed by the line of departure of the barrel portion extending into the generally convex curved surface; and wherein the thin layer of the third material forming the interface between the PCD material volume and the substrate intersects the barrel portion below the shoulder. 
     
     
         11 . The rock removal body of  claim 6 , wherein the volume of the PCD material volume is greater than the volume of the substrate. 
     
     
         12 . The rock removal body of  claim 11  wherein the substrate has an associated radius and a thickness measured as the length of the barrel portion which the substrate forms, the length of the substrate being greater than the radius of the substrate. 
     
     
         13 . (canceled) 
     
     
         14 . (canceled) 
     
     
         15 . The rock removal body of  claim 1 , wherein the thin layer of the third material forming the interface between the PCD material volume and the substrate comprises a partially carburised refractory metal layer having a thickness of between around 20 microns and around 100 microns, the partially carburised refractory metal layer comprising any one or more of tantalum, vanadium, molybdenum, zirconium, tungsten and alloys thereof. 
     
     
         16 . The rock removal body of  claim 15 , wherein the thin layer of the third material forming the interface between the PCD material volume and the substrate comprises a partially carburised layer of tantalum. 
     
     
         17 . The rock removal body of  claim 1 , wherein the thin layer of the third material forming the interface between the PCD material volume and the substrate comprises a PVD or a CVD deposited continuous ceramic layer having a thickness of greater than around 3 microns, the thin layer of the third material comprising any one or more of nitrides of the elements of groups IVa, Va and/or VIa of the periodic table. 
     
     
         18 . The rock removal body of  claim 17 , wherein the thin layer of the third material comprises titanium nitride. 
     
     
         19 . (canceled) 
     
     
         20 . (canceled) 
     
     
         21 . The rock removal body of  claim 1 , wherein the metal forming the metallic network of the PCD material volume is invariant as regards the metal type or alloy across the dimensions of the PCD material volume; and wherein the metallic content of the PCD material increases in the general direction away from a point which is part of the functional working volume which initially bears upon the rock in use, towards the thin layer of the third material forming the interface between the PCD material volume and the substrate. 
     
     
         22 . The rock removal body of  claim 21 , wherein the PCD material volume comprises two or more layers of differing PCD material, the first layer of lowest linear coefficient of thermal expansion and metal content extends from the free surface of the PCD material volume and encompasses the functional working volume, the second or subsequent layers of higher linear coefficient of thermal expansion and metal content separating the first layer from the thin layer forming the interface between the PCD material volume and the substrate. 
     
     
         23 . The rock removal body of  claim 1 , wherein the body has a base portion formed by the free surface of the substrate; wherein the substrate has an associated linear coefficient of thermal expansion which decreases away from the central point of the base of the body towards the thin layer forming the interface between the PCD material volume and the substrate. 
     
     
         24 . The rock removal body of  claim 23 , wherein the substrate comprises a cementing metal material and a hard compound, the cementing metal material and the hard compound being invariant as regards metal type and molecular composition, the amount of cementing metal decreasing in a direction away from the central point of the base of the body towards the thin layer of the third material forming the interface between the PCD material volume and the substrate. 
     
     
         25 . The rock removal body of  claim 24 , wherein the substrate comprises two or more layers of differing hard metal material, the first layer of highest linear coefficient of thermal expansion and metal content extending from the free surface of the substrate forming the base of the body, the second and/or subsequent layers being of lower linear coefficient of thermal expansion and metal content separating the first layer from the thin layer forming the interface between the PCD material volume and the substrate. 
     
     
         26 . The rock removal body of  claim 1 , wherein the PCD material volume is graded in composition and structure such that the linear coefficient of thermal expansion of the PCD material increases in a direction away from a point which is part of the functional working volume towards the interface, the linear coefficient of thermal expansion of the substrate decreasing in a direction away from the central point of the base of the body towards the interface. 
     
     
         27 . (canceled) 
     
     
         28 . (canceled) 
     
     
         29 . (canceled) 
     
     
         30 . (canceled)