# US 8,540,036 B2 · Ultrahard sintered carbide particles in hardfacing for earth-boring bit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,540,036 B2 - Document ID: US8540036B2 - Status: Granted - Kind: B2 - Application number: 12/893,953 - Filed: 2010-09-29 - Published: 2011-03-31 - Granted: 2013-09-24 - Earliest claimed: 2009-09-29 - Assignees: Baker Hughes Incorporated - Applicants: James L. Overstreet - Inventors: James L. Overstreet - Web page: https://patentgrep.com/patent/US8540036B2 ## CPC - E21B 10/46: characterised by wear resisting parts, e.g. diamond inserts - B24D 99/005: {Segments of abrasive wheels} - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS - B24D: TOOLS FOR GRINDING, BUFFING OR SHARPENING (abrading-bodies specially designed for tumbling apparatus, e.g. abrading-balls B24B31/14; honing tools B24B33/08; lapping tools B24B37/11) ## Abstract A hardfacing composition for downhole well tools, such as earth-boring bits, contains sintered ultrahard particles. The ultrahard particles consist of tungsten carbide grains, cobalt and vanadium. The ultrahard particles are dispersed within a matrix metal of iron, nickel or alloys thereof. The composition may also have sintered tungsten carbide particles of a larger size than the ultrahard particles. The ultrahard particles have a greater hardness than the sintered tungsten carbide particles. The ultrahard particles and the sintered tungsten carbide particles may be in a spherical pellet form. Other hard metal particles may be in the composition. ## Claims ### Claim 1 A hardfacing composition, comprising: sintered ultrahard pellets, each consisting of tungsten carbide grains, cobalt, and vanadium; and a matrix metal comprising iron, nickel, or alloys thereof, the sintered ultrahard pellets dispersed in the matrix metal. ### Claim 2 (depends on 1) The hardfacing composition of claim 1, further comprising sintered tungsten carbide pellets of a larger size than the sintered ultrahard pellets. ### Claim 3 (depends on 2) The hardfacing composition of claim 2, wherein the sintered ultrahard pellets have a greater hardness than the sintered tungsten carbide pellets. ### Claim 4 (depends on 1) The hardfacing composition of claim 1, further comprising: cast tungsten carbide pellets exhibiting greater hardness than the sintered ultrahard pellets; and sintered tungsten carbide pellets exhibiting less hardness than the sintered ultrahard pellets, and having a larger size than the sintered ultrahard pellets and the cast tungsten carbide pellets. ### Claim 5 (depends on 1) The hardfacing composition of claim 1, further comprising sintered tungsten carbide pellets, a portion of the sintered ultrahard pellets in a spherical form and another portion of the sintered ultrahard pellets in a crushed form. ### Claim 6 (depends on 5) The hardfacing composition of claim 5, further comprising: spherical cast carbide pellets; crushed cast tungsten carbide pellets; and monocrystalline tungsten carbide particles. ### Claim 7 (depends on 1) The hardfacing composition of claim 1, wherein the sintered ultrahard pellets are in a spherical form, and further comprising: spherical sintered tungsten carbide pellets having larger diameters than the sintered ultrahard pellets; and crushed cast tungsten carbide pellets. ### Claim 8 (depends on 1) The hardfacing composition of claim 1, wherein the sintered ultrahard pellets comprise spherical pellets, and further comprising: spherical sintered tungsten carbide pellets having larger diameters than the sintered ultrahard pellets; and monocrystalline tungsten carbide particles. ### Claim 9 (depends on 1) The hardfacing composition of claim 1, wherein the sintered ultrahard pellets comprise 4 to 8 percent cobalt, 0.25 to 2 percent vanadium, and a remainder of tungsten carbide. ### Claim 10 A hardfacing composition, comprising: spherical sintered ultrahard pellets comprising tungsten carbide grains, elemental cobalt, and elemental vanadium; and a matrix metal comprising iron, nickel, or alloys thereof, the spherical sintered ultrahard pellets dispersed in the matrix metal. ### Claim 11 (depends on 10) The composition of claim 10, further comprising spherical sintered tungsten carbide pellets of a larger diameter than the spherical sintered ultrahard pellets. ### Claim 12 (depends on 11) The composition of claim 11, wherein the spherical sintered ultrahard pellets have a greater hardness than the sintered tungsten carbide pellets. ### Claim 13 (depends on 10) The composition of claim 10, wherein diameters of the ultrahard pellets are within a range of from about 177 to 250 microns. ### Claim 14 (depends on 10) The composition of claim 10, further comprising crushed sintered ultrahard pellets comprising tungsten carbide grains, elemental cobalt, and elemental vanadium. ### Claim 15 (depends on 10) The composition of claim 10, wherein the spherical sintered ultrahard pellets comprise 4 to 8 percent cobalt, 0.25 to 2 percent vanadium, and a remainder of tungsten carbide. ### Claim 16 An earth-boring bit comprising: a body; a plurality of bit legs; a plurality of cones rotatably mounted to the plurality of bit legs; hardfacing on at least one of the plurality of bit legs and the plurality of cones, and comprising: spherical sintered ultrahard pellets comprising tungsten carbide grains, elemental vanadium, and at least one of cobalt, iron, and nickel; spherical sintered tungsten carbide pellets of a larger diametrical size than the spherical sintered ultrahard pellets; and a matrix metal comprising iron, nickel, or alloys thereof, the spherical sintered ultrahard pellets and the sintered tungsten carbide pellets dispersed in the matrix metal. ### Claim 17 (depends on 16) The earth-boring bit of claim 16, wherein the hardfacing is located on outer sides of the plurality of bit legs, and wherein the diametrical sizes of the spherical sintered ultrahard pellets are within a range from about 45 to 250 microns. ### Claim 18 (depends on 16) The earth-boring bit of claim 16, wherein the hardfacing is located on the plurality of cones, and wherein a diametrical size of the spherical sintered ultrahard pellets is within a range from about 177 to 250 microns. ### Claim 19 (depends on 16) The earth-boring bit of claim 16, wherein a hardness of the spherical sintered ultrahard pellets is greater than that of the sintered tungsten carbide pellets. ### Claim 20 (depends on 16) The earth-boring bit of claim 16 wherein the hardfacing further comprises spherical cast carbide pellets having a diametrical size within a range of from about 177 to 250 microns, the spherical cast carbide pellets having a greater hardness than that of the spherical sintered ultrahard pellets. ### Claim 21 (depends on 16) The earth-boring bit of claim 16, wherein the hardfacing is substantially free of cast tungsten carbide pellets.