Earth-Boring Bit Parts Including Hybrid Cemented Carbides and Methods of Making the Same
An earth-boring bit part such as, for example, a bit body, roller cone, or mud nozzle includes a hybrid cemented carbide composite. The hybrid cemented carbide includes a cemented carbide dispersed phase, and a cemented carbide continuous phase. A method of manufacture also is disclosed.
1 . A method of making a part for an earth-boring bit, the method comprising:
combining a portion of a first grade of a cemented carbide powder and a portion of a second grade of a cemented carbide powder to provide a powder blend;
consolidating at least a portion of the powder blend into a green compact, wherein the first grade of a cemented carbide powder is a dispersed phase of the green compact and the second grade of a cemented carbide powder is a continuous phase of the green compact; and
at least one of partially and fully sintering the green compact to form a densified compact comprising a hybrid cemented carbide composite including a cemented carbide dispersed phase and a cemented carbide continuous phase;
wherein the part for an earth-boring bit comprises a bit body, a roller cone, or a mud nozzle.
2 . The method of claim 1 , further comprising:
combining a third grade of a cemented carbide powder with the first and second grades of a cemented carbide powder into the powder blend;
wherein the hybrid cemented carbide composite includes the cemented carbide continuous phase, a first cemented carbide dispersed phase, and a second cemented carbide dispersed phase; and
wherein at least one of composition, hardness, Palmquist toughness, and wear resistance of the first cemented carbide dispersed phase is different than that of the second cemented carbide dispersed phase.
3 . The method of claim 1 , further comprising, prior to consolidating:
placing at least a portion of a first powder blend for forming the first hybrid cemented carbide composite composition into a first region of a void of a mold;
placing at least a portion of a second powder blend for forming the second cemented carbide composite composition into a second region of the void; and
wherein consolidating at least a portion of the powder blend comprises pressing the powder blends within the void of the mold to provide the green compact.
4 . The method of claim 1 , wherein a contiguity ratio of the dispersed phase of the hybrid cemented carbide composite is no more than 0.48.
5 . The method of claim 1 , wherein a hardness of the dispersed phase of the hybrid cemented carbide composite is greater than a hardness of the continuous phase of the hybrid cemented carbide composite.
6 . The method of claim 1 , wherein the cemented carbide dispersed phase of the hybrid cemented carbide composite is between 2 and 25 percent by volume of the hybrid cemented carbide composite.
7 . The method of claim 1 , wherein the hardness of the cemented carbide dispersed phase of the hybrid cemented carbide composite is at least 88 HRA and no greater than 95 HRA.
8 . The method of claim 7 , wherein the Palmquist toughness of the cemented carbide continuous phase of the hybrid cemented carbide composite is greater than 10 MPa·m 1/2 .
9 . The method of claim 8 , wherein the hardness of the cemented carbide continuous phase of the hybrid cemented carbide composite is at least 78 HRA and no greater than 91 HRA.
10 . The method of claim 1 , wherein the cemented carbide dispersed phase comprises tungsten carbide hard particles and a binder comprising cobalt, and wherein the cemented carbide continuous phase comprises tungsten carbide hard particles and a binder comprising cobalt.
11 . The method of claim 9 , wherein the binders further comprise at least one alloying agent selected from the group consisting of tungsten, titanium, tantalum, niobium, aluminum, chromium, copper, manganese, molybdenum, boron, carbon, silicon, and ruthenium, wherein the alloying agent comprises up to 20 weight percent of the binder.
12 . The method of claim 1 ,
wherein a volume fraction of the cemented carbide dispersed phase is less than 50 volume percent of the hybrid cemented carbide composite; and
wherein the cemented carbide dispersed phase has a contiguity ratio less than 1.5 times the volume fraction of the cemented carbide dispersed phase in the hybrid cemented carbide composite.
13 . The method of claim 1 , wherein the hybrid cemented carbide composite has a wear resistance greater than 0.7 mm −3 , and a Palmquist toughness greater than 10 MPa·m 1/2 .
14 . The method of claim 1 , wherein at least one of partially and fully sintering the green compact comprises:
presintering the green compact to form a brown compact; and
sintering the brown compact.
15 . The method of claim 14 , further comprising, prior to sintering the brown compact, machining the brown compact.
16 . The method of claim 15 , wherein machining the brown compact comprises machining at least one cutter insert pocket in the brown compact.
17 . The method of claim 14 , further comprising, prior to presintering the green compact, machining the green compact.
18 . The method of claim 17 , wherein machining the green compact comprises machining at least one cutter insert pocket in the green compact.
19 . The method of claim 1 , wherein consolidating at least a portion of the powder blend comprises isostatically pressing the at least a portion of the powder blend.
20 . The method of claim 14 , wherein sintering the brown compact comprises sintering the brown compact at a liquid phase temperature.
21 . The method of claim 13 , wherein sintering the brown compact comprises sintering the brown compact at a pressure of 300 to 2000 psi and a temperature of 1350° C. to 1500° C.