Methods of forming polycrystalline diamond elements, polycrystalline diamond elements, and earth-boring tools carrying such polycrystalline diamond elements

Abstract

Methods of forming polycrystalline diamond elements include forming a polycrystalline diamond element. A Group VIII metal or alloy catalyst is employed to form the polycrystalline diamond compact table at a pressure of at least about 6.5 GPa or greater. The catalyst is then removed from at least a portion of the table to a depth from a working surface thereof, and may be removed from the entirety of the table. Polycrystalline diamond elements include such polycrystalline diamond compact tables. Earth-boring tools include such polycrystalline diamond elements carried thereon and employed as cutting elements.

What is claimed is: 
     
         1 . A method of forming a polycrystalline diamond element, comprising:
 forming a polycrystalline diamond compact comprising a catalyst including a Group VIII metal or alloy at a pressure of at least about 6.5 GPa; and   at least substantially removing the catalyst from at least a portion of the polycrystalline diamond compact.   
     
     
         2 . The method of  claim 1 , wherein forming the polycrystalline diamond compact comprises forming a diamond table on a supporting substrate. 
     
     
         3 . The method of  claim 1 , wherein forming the polycrystalline diamond compact comprises forming a free-standing polycrystalline diamond compact. 
     
     
         4 . The method of  claim 1 , wherein at least substantially removing the catalyst from at least a portion of the polycrystalline diamond compact is effected by leaching. 
     
     
         5 . The method of  claim 4 , further comprising leaching a portion of the polycrystalline diamond compact to a depth of less than about 100 microns. 
     
     
         6 . The method of  claim 4 , further comprising leaching a portion of the polycrystalline diamond compact to a depth of at least about 100 microns. 
     
     
         7 . The method of  claim 6 , wherein leaching a portion of the polycrystalline diamond compact to a depth of at least 100 microns comprises leaching a portion of the polycrystalline diamond compact to a depth of at least about 250 microns. 
     
     
         8 . The method of  claim 1 , wherein at least substantially removing the catalyst from a portion of the polycrystalline diamond compact is effected to a depth of between about 40 microns and about 400 microns from at least one of a cutting face, a side wall, and a chamfer of the polycrystalline diamond compact. 
     
     
         9 . The method of  claim 8 , wherein at least substantially removing the catalyst from a portion of the polycrystalline diamond compact is effected to a depth of between about 100 microns and about 250 microns from at least one of a cutting face, a side wall, and a chamfer of the polycrystalline diamond compact. 
     
     
         10 . The method of  claim 1 , wherein at least substantially removing the catalyst from at least a portion of the polycrystalline diamond compact comprises substantially removing the catalyst from substantially an entirety of the polycrystalline diamond compact. 
     
     
         11 . The method of  claim 1 , wherein forming the polycrystalline diamond compact comprises forming the polycrystalline diamond compact from natural diamond grit, synthetic diamond grit, or a combination thereof. 
     
     
         12 . The method of  claim 1 , wherein forming the polycrystalline diamond compact comprises employing a multi-modal diamond grit mixture. 
     
     
         13 . The method of  claim 1 , wherein forming the polycrystalline diamond compact consists of forming the polycrystalline diamond compact from the group selected from a single layer of diamond grit of a single nominal size, a single layer of diamond grit employing a multi-modal diamond grit mixture, two or more layers of diamond grit with diamond grit within each layer being of a substantially common nominal size, and two or more layers of diamond grit, at least one of the layers comprising a multi-modal diamond grit mixture. 
     
     
         14 . The method of  claim 1 , wherein forming a polycrystalline diamond compact at pressure of at least about 6.5 GPa comprises forming the polycrystalline diamond compact at a pressure of at least about 6.8 GPa, at least about 7 GPa, at least about 7.7 GPa, at least about 8 GPa, or at least about 9 GPa. 
     
     
         15 . A polycrystalline diamond element, comprising:
 a polycrystalline diamond compact table comprising a catalyst including a Group VIII metal or alloy and formed at a pressure of at least about 6.5 GPa;   wherein at least a portion of the polycrystalline diamond compact table is substantially free of the catalyst.   
     
     
         16 . The polycrystalline diamond element of  claim 15 , further comprising a supporting substrate secured to a surface of the polycrystalline diamond compact table. 
     
     
         17 . The polycrystalline diamond element of  claim 15 , wherein the at least a portion of the polycrystalline diamond compact table substantially free of the catalyst comprises a depth of between about 80 microns and about 250 microns from at least one of a cutting face, a side wall, and a chamfer of the polycrystalline diamond compact table. 
     
     
         18 . The polycrystalline diamond element of  claim 15 , wherein the at least a portion of the polycrystalline diamond compact table substantially free of the catalyst comprises a depth of at least 250 microns from at least one of a cutting face, a side wall, and a chamfer of the polycrystalline diamond compact table. 
     
     
         19 . The polycrystalline diamond compact element of  claim 18 , wherein the at least a portion of the polycrystalline diamond compact table substantially free of the catalyst comprises substantially an entirety of the polycrystalline diamond table. 
     
     
         20 . The polycrystalline diamond element of  claim 15 , wherein the polycrystalline diamond compact table comprises natural diamond grit, synthetic diamond grit, or a combination thereof. 
     
     
         21 . The polycrystalline diamond element of  claim 15 , wherein the polycrystalline diamond compact table exhibits a multi-modal diamond grain distribution. 
     
     
         22 . The polycrystalline diamond element of  claim 15 , wherein the polycrystalline diamond compact table consists of the group selected from a single layer of diamond grains of a single nominal size, a single layer of diamond grains having a multi-modal diamond grain distribution, two or more layers of diamond grains with grains of each layer being of a substantially common nominal size, and two or more layers of diamond grains, at least one of the layers comprising a multi-modal diamond grain distribution. 
     
     
         23 . The polycrystalline diamond element of  claim 15 , wherein the polycrystalline diamond compact table is formed at a pressure of at least about 6.8 GPa, at least about 7 GPa, at least about 7.7 GPa, at least about 8 GPa, or at least about 9 GPa. 
     
     
         24 . An earth-boring tool, comprising:
 a body; and   at least one cutting element carried by the body and comprising:
 a polycrystalline diamond compact table formed at a pressure of at least about 6.5 GPa, comprising a Group VIII metal or alloy catalyst and including at least a portion that is substantially free of the catalyst. 
   
     
     
         25 . The earth-boring tool of  claim 24 , further comprising a supporting substrate secured to a surface of the polycrystalline diamond compact table.