Diamond enhanced drilling insert with high impact resistance

Abstract

An insert for a drill bit may include a substrate; a working layer of polycrystalline diamond material on the uppermost end of the insert, wherein the polycrystalline diamond material includes a plurality of interconnected diamond grains; and a binder material; and an inner transition layer between the working layer and the substrate, wherein the inner transition layer is adjacent to the substrate; wherein the inner transition layer has a hardness that is at least 500 HV greater than the hardness of the substrate.

What is claimed is: 
     
         1 . A cutting element comprising:
 a substrate;   a body attached to the substrate and comprising:
 a working layer of polycrystalline diamond comprising interconnected bonded-together diamond grains and a plurality of interstitial regions dispersed therein; and 
 a transition layer interposed between the working layer and the substrate, the transition layer having a hardness at least 500 HV greater than the hardness of the substrate. 
   
     
     
         2 . The cutting element as recited in  claim 1  wherein the transition layer is adjacent to and disposed over an entire interfacing surface of the substrate. 
     
     
         3 . The cutting element as recited in  claim 1  wherein the transition layer has a hardness that does not exceed the hardness of the substrate by more than 1500 HV. 
     
     
         4 . The cutting element as recited in  claim 1  wherein the polycrystalline diamond interstitial regions are filled with a binder material. 
     
     
         5 . The cutting element as recited in  claim 1  wherein the transition layer has a hardness that is at least 300 HV less than a hardness of the working layer. 
     
     
         6 . The cutting element as recited in  claim 1  wherein the transition layer has a hardness that is less than a hardness of the working layer by less than 1200 HV. 
     
     
         7 . The cutting element as recited in  claim 1  wherein the transition layer has a hardness that is less than a hardness of the working layer by less than 1500 HV. 
     
     
         8 . The cutting element as recited in  claim 1  comprising two transition layers, wherein a first is positioned adjacent the working layer, wherein a second transition layer is interposed between the first transition layer and the substrate, and wherein the first transition layer has a hardness greater than the second transition layer. 
     
     
         9 . A bit for drilling subterranean formations comprising a body and a number of the cutting elements as recited in  claim 1  operatively connected thereto. 
     
     
         10 . A cutting element comprising;
 a substrate;   a body attached to the body and comprising:
 a working layer of polycrystalline diamond material comprising intercrystalline bonded-together diamond grains and interstitial regions dispersed therein; 
 a first transition layer having a hardness that is less than the working layer by less than 1500 HV; and 
 a second transition layer having a hardness that is at least 500 HV greater than the hardness of the substrate; 
 wherein the first and second transition layers are interposed between the working layer and the substrate. 
   
     
     
         11 . The cutting element as recited in  claim 10  wherein the first transition layer is interposed between the working layer and the second transition layer, and the second transition layer is interposed between the first transition layer and the substrate. 
     
     
         12 . The cutting element as recited in  claim 10  wherein the working layer has a hardness of 4000 HV or greater, and the first transition layer has a hardness that is at least 300 HV greater that the working layer. 
     
     
         13 . The cutting element as recited in  claim 10  wherein the second transition later has a hardness that does not exceed the hardness of the substrate by more than 1500 HV. 
     
     
         14 . The cutting element as recited in  claim 10  wherein the polycrystalline diamond interstitial regions comprise a binder material. 
     
     
         15 . The cutting element as recited in  claim 10  wherein the first transition layer has a hardness of from 1800 HV to 2500 HV. 
     
     
         16 . A bit for drilling subterranean formations comprising a body having a number of the cutting elements of  claim 10  attached thereto. 
     
     
         17 . A bit for drilling subterranean formations comprising:
 a body comprising a number of cutting elements attached thereto, the cutting elements comprising:
 a substrate; 
 a working layer of polycrystalline diamond material along an outer surface of the cutting element, the polycrystalline diamond material comprising a plurality of interconnected diamond grains and a plurality of interstitial regions dispersed therein; 
 a transition layer between the working layer and substrate and in contact with the substrate, wherein the transition layer has a hardness that is at least 500 HV greater than the substrate and that does not exceed the hardness of the substrate by more than 1500 HV. 
   
     
     
         18 . The bit as recited in  claim 17  wherein the body comprises a further transition layer in contact with the working layer, and wherein the further transition layer has a hardness that is greater than the transition layer and at least 300 HV less than the working layer hardness. 
     
     
         19 . The bit as recited in  claim 18  wherein the further transition layer has a hardness that is less than 1500 HV less than the working layer hardness. 
     
     
         20 . The bit as recited in  claim 17  wherein the transition layer comprises diamond grains, metal carbide or carbonitride particles, and a binder material.