Producing Catalyst-free PDC Cutters

Abstract

Cutters for a downhole drill bit can be formed by providing a catalyst-free synthesized polycrystalline diamond (PCD) having a cross-sectional dimension of at least 8 millimeters; providing a substrate comprising tungsten carbide; and attaching the synthesized PCD to the substrate comprising tungsten carbide to form a PDC cutter.

1 .- 20 . (canceled) 
     
     
         21 . A downhole drill bit comprising:
 a body; and   a plurality of cutters, each cutter comprising a single phase catalyst-free synthesized polycrystalline diamond (PCD) attached to a substrate, wherein the single phase catalyst-free synthesized PCD is synthesized from a diamond powder with a particle size within a range of 0.5 μm to 50 μm, wherein the single phase catalyst-free synthesized PCD is formed without leaching.   
     
     
         22 . The downhole drill bit of  claim 21 , further comprising a filler metal placed between the catalyst-free synthesized PCD and the carbide substrate. 
     
     
         23 . The downhole drill bit of  claim 21 , wherein the catalyst-free synthesized PCD is a generally cylindrical catalyst-free synthesized PCD with a non-planar end surface. 
     
     
         24 . The downhole drill bit of  claim 23 , wherein the non-planar end surface comprises a laser-formed non-planar end surface. 
     
     
         25 . The downhole drill bit of  claim 21 , wherein the catalyst-free synthesized PCD attached to the carbide substrate is bonded to the body by a brazing process. 
     
     
         26 . The downhole drill bit of  claim 21 , wherein the single phase catalyst-free synthesized PCD is attached to the substrate by placing the single phase catalyst-free synthesized PCD in contact with a powder form of the substrate. 
     
     
         27 . The downhole drill bit of  claim 26 , wherein the powder form of the substrate comprises a WC—Co powder having a Co content within a range of one percent to 20 percent by weight. 
     
     
         28 . The downhole drill bit of  claim 27 , wherein the WC—Co powder has a particle size within a range of 0.5 μm to 50 μm. 
     
     
         29 . The downhole drill bit of  claim 21 , wherein the single phase catalyst-free synthesized PCD is attached to the substrate by vacuum diffusion bonding, hot pressing, microwave joining, or high-pressure, high temperature (HPHT) bonding. 
     
     
         30 . The downhole drill bit of  claim 29 , wherein the single phase catalyst-free synthesized PCD is attached to the substrate by vacuum diffusion bonding in a vacuum chamber with 1.0×10 −2  Pa to 1×10 −5  Pa pressure. 
     
     
         31 . The downhole drill bit of  claim 29 , wherein each cutter comprises a filler metal between the single phase catalyst-free synthesized PCD and the substrate. 
     
     
         32 . The downhole drill bit of  claim 21 , wherein the single phase catalyst-free synthesized PCD is attached to the substrate by spark plasma sintering. 
     
     
         33 . The downhole drill bit of  claim 32 , wherein the spark plasma sintering comprises heating the single phase catalyst-free synthesized PCD and the substrate to a temperature within a range of 600° C. to 1200° C. 
     
     
         34 . The downhole drill bit of  claim 33 , wherein heating the single phase catalyst-free synthesized PCD and the substrate comprises passing a pulsed or a direct electric current of 1000 amps (A) to 2000 A through the single phase catalyst-free synthesized PCD and the substrate. 
     
     
         35 . The downhole drill bit of  claim 34 , wherein the single phase catalyst-free synthesized PCD and the substrate are heated in a stepwise fashion from ambient room temperature to a joining temperature. 
     
     
         36 . The downhole drill bit of  claim 21 , wherein the single phase catalyst-free synthesized PCD is attached to the substrate at an applied pressure between 1 and 20 GPa and an applied temperature between 1200° C. and 1500° C. 
     
     
         37 . The downhole drill bit of  claim 21 , wherein the catalyst-free synthesized PCD has a cross-sectional dimension of at least 1 millimeter. 
     
     
         38 . The downhole drill bit of  claim 37 , wherein the single phase catalyst-free synthesized PCD has a cross-sectional dimension of at least 8 millimeters. 
     
     
         39 . The downhole drill bit of  claim 21 , wherein the single phase catalyst-free synthesized PCD has a fracture toughness of 18.7 MPa√{square root over (m)}. 
     
     
         40 . The downhole drill bit of  claim 21 , wherein the single phase catalyst-free synthesized PCD has a Vickers hardness of 120 GPa.