Method of selectively adapting material properties across a rock bit cone

Abstract

Methods of forming cutter assemblies for use on earth-boring tools include sintering a cone structure to fuse one or more cutting elements thereto and having a hardened land area. In some embodiments, one or more green, brown, or fully sintered cutting elements may be positioned on a green or brown cone structure prior to sintering the cone structure to a final density. Cutter assemblies may be formed by such methods, and such cutter assemblies may be used in earth-boring tools such as, for example, earth-boring rotary drill bits and hole openers.

1 . A method of forming a cutter assembly for use on an earth-boring tool, the method comprising:
 providing a less than fully sintered cone structure comprising first hard particles and a matrix material, the cone structure having positions for at least two rows of cutting elements to be located thereon and a land located between the at least two rows of cutting elements, the land comprising second hard particles and a matrix material; and   sintering the cone structure to a final density to fuse the at least one cutting element to the cone structure.   
   
   
       2 . The method of  claim 1 , wherein providing a less than fully sintered cone structure comprises providing a green cone structure. 
   
   
       3 . The method of  claim 2 , wherein providing a green cone structure comprises:
 mixing the first hard particles and second hard particles with other particles comprising the matrix material to form a powder mixture; and   pressing the powder mixture to form the green cone structure.   
   
   
       4 . The method of  claim 3 , further comprising:
 selecting the first hard particles and the second hard particles from the group consisting of diamond, boron carbide, boron nitride, aluminum nitride, and carbides or borides of the group consisting of W, Ti, Mo, Nb, V, Hf, Ta, Cr, Zr, Al, and Si; and   selecting the matrix material from the group consisting of cobalt-based alloys, iron-based alloys, nickel-based alloys, cobalt and nickel-based alloys, iron and nickel-based alloys, iron and cobalt-based alloys, aluminum-based alloys, copper-based alloys, magnesium-based alloys, and titanium-based alloys.   
   
   
       5 . The method of  claim 2 , further comprising machining at least one aperture in the green cone structure for positioning at least one cutting element on the less than fully sintered cone structure. 
   
   
       6 . The method of  claim 2 , further comprising machining at least one protrusion on the green cone structure for positioning at least one cutting element on the less than fully sintered cone structure onto the at least one protrusion of the green cone structure. 
   
   
       7 . The method of  claim 1 , wherein providing a less than fully sintered cone structure comprises providing a brown cone structure. 
   
   
       8 . The method of  claim 7 , wherein providing a brown cone structure comprises:
 mixing the first hard particles and the second hard particles with particles comprising the matrix material to form a powder mixture;   pressing the powder mixture to form a green cone structure; and   partially sintering the green cone structure to form the brown cone structure.   
   
   
       9 . The method of  claim 8 , further comprising:
 selecting the first hard particles and the second hard particles from the group consisting of diamond, boron carbide, boron nitride, aluminum nitride, and carbides or borides of the group consisting of W, Ti, Mo, Nb, V, Hf, Ta, Cr, Zr, Al, and Si; and   selecting the matrix material from the group consisting of cobalt-based alloys, iron-based alloys, nickel-based alloys, cobalt and nickel-based alloys, iron and nickel-based alloys, iron and cobalt-based alloys, aluminum-based alloys, copper-based alloys, magnesium-based alloys, and titanium-based alloys.   
   
   
       10 . The method of  claim 7 , further comprising machining at least one aperture in the brown cone structure, and wherein positioning at least one cutting element on the less than fully sintered cone structure comprises inserting the at least one cutting element into the at least one aperture of the brown cone structure. 
   
   
       11 . The method of  claim 7 , further comprising machining at least one protrusion on the brown cone structure for positioning at least one cutting element on the less than fully sintered cone structure. 
   
   
       12 . The method of  claim 1 , further comprising positioning at least one cutting element on the less than fully sintered cone structure comprising third hard particles and a matrix material on the less than fully sintered cone structure. 
   
   
       13 . The method of  claim 1 , further comprising:
 positioning at least one bearing structure on the less than fully sintered cone structure; and   fusing the bearing structure to the less than fully sintered cone structure while sintering the cone structure to a final density.   
   
   
       14 . The method of  claim 1 , further comprising mounting the cone structure on a bearing pin of an earth-boring tool. 
   
   
       15 . An earth-boring tool comprising:
 a bearing pin; and   a cutter assembly rotatably mounted on the bearing pin, the cutter assembly comprising:
 a cone comprising a particle-matrix composite material having a first material composition and a second material composition in the land region thereof. 
   
   
   
       16 . The earth-boring tool of  claim 15 , wherein the particle-matrix composite material of the cone of the first material composition and the second material composition each comprise a plurality of hard particles dispersed throughout a matrix material, the hard particles comprising a material selected from diamond, boron carbide, boron nitride, aluminum nitride, and carbides or borides of the group consisting of W, Ti, Mo, Nb, V, Hf, Ta, Cr, Zr, Al, and Si, the matrix material selected from the group consisting of cobalt-based alloys, iron-based alloys, nickel-based alloys, cobalt and nickel-based alloys, iron and nickel-based alloys, iron and cobalt-based alloys, aluminum-based alloys, copper-based alloys, magnesium-based alloys, and titanium-based alloys. 
   
   
       17 . The earth-boring tool of  claim 15 , further comprising at least one bearing structure co-sintered and integral with the cone. 
   
   
       18 . The earth-boring tool of  claim 15 , wherein the at least one bearing structure comprises a particle-matrix composite material. 
   
   
       19 . The earth-boring tool of  claim 15 , further comprising at least one cutting element. 
   
   
       20 . The earth-boring tool of  claim 15 , further comprising at least a portion of a cutting tooth structure. 
   
   
       21 . The earth-boring tool of  claim 15 , wherein the at least one cutting element has a varying material composition between a first region proximate an interface between the at least one cutting element and the cone and a second region proximate a formation-engaging surface of the at least one cutting element. 
   
   
       22 . A cutter assembly for use on an earth-boring tool, the cutter assembly comprising at least one cutting element co-sintered and integral with a cone structure, the cone structure comprising a particle-matrix composite material having a first material composition in a tooth area and a second material composition in a land area. 
   
   
       23 . The cutter assembly of  claim 22 , wherein the particle-matrix composite material of the cone structure of the first material composition and the second material composition each comprise a plurality of hard particles dispersed throughout a matrix material, the hard particles comprising a material selected from diamond, boron carbide, boron nitride, aluminum nitride, and carbides or borides of the group consisting of W, Ti, Mo, Nb, V, Hf, Ta, Cr, Zr, Al, and Si, the matrix material selected from the group consisting of cobalt-based alloys, iron-based alloys, nickel-based alloys, cobalt and nickel-based alloys, iron and nickel-based alloys, iron and cobalt-based alloys, aluminum-based alloys, copper-based alloys, magnesium-based alloys, and titanium-based alloys. 
   
   
       24 . The cutter assembly of  claim 22 , further comprising at least one bearing structure co-sintered and integral with the cone structure. 
   
   
       25 . The cutter assembly of  claim 22 , wherein the at least one bearing structure comprises a particle-matrix composite material. 
   
   
       26 . The cutter assembly of  claim 22 , further comprising at least one cutting element comprising a cutting insert. 
   
   
       27 . The cutter assembly of  claim 22 , further comprising at least one cutting element comprising at least a portion of a cutting tooth structure.