U.S. patent application number 16/541918 was filed with the patent office on 2021-02-18 for techniques for affecting leaching profiles in cutting elements for earth-boring tools and related cutting elements, earth-boring tools, and methods.
The applicant listed for this patent is Baker Hughes Oilfield Operations LLC. Invention is credited to Wanjun Cao, Xu Huang, Steven W. Webb.
Application Number | 20210047887 16/541918 |
Document ID | / |
Family ID | 1000004338022 |
Filed Date | 2021-02-18 |
United States Patent
Application |
20210047887 |
Kind Code |
A1 |
Cao; Wanjun ; et
al. |
February 18, 2021 |
TECHNIQUES FOR AFFECTING LEACHING PROFILES IN CUTTING ELEMENTS FOR
EARTH-BORING TOOLS AND RELATED CUTTING ELEMENTS, EARTH-BORING
TOOLS, AND METHODS
Abstract
Cutting elements for earth-boring tools may include a cutting
table secured to a substrate. The cutting table may include a first
region at least substantially free of an infiltrant, a second
region comprising the infiltrant, and a passageway extending from
an exterior partially through the first region. A distance between
the exterior and a boundary between the first region and the second
region, as measured from a major surface of the cutting table, may
not be constant. Methods of making cutting elements for
earth-boring tools may involve placing a sacrificial material among
grains of a superabrasive material. The grains of the superabrasive
material and the sacrificial material may be exposed to elevated
temperature and pressure in a presence of a catalyst material to
form a cutting table. The sacrificial material and a portion of the
catalyst material may be removed from a first region of the cutting
table.
Inventors: |
Cao; Wanjun; (The Woodlands,
TX) ; Webb; Steven W.; (The Woodlands, TX) ;
Huang; Xu; (Spring, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Baker Hughes Oilfield Operations LLC |
Houston |
TX |
US |
|
|
Family ID: |
1000004338022 |
Appl. No.: |
16/541918 |
Filed: |
August 15, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 10/567
20130101 |
International
Class: |
E21B 10/567 20060101
E21B010/567 |
Claims
1. A cutting element for an earth-boring tool, comprising: a
cutting table secured to a substrate, the cutting table comprising:
a first region at least substantially free of solid infiltrant
material in interstitial spaces among interbonded grains of
superabrasive material located proximate a cutting face of the
cutting table; a second region comprising solid infiltrant material
in the interstitial spaces among the interbonded grains of the
superabrasive material located proximate the substrate; and a
passageway extending from an exterior of the cutting table
partially through the first region; and wherein a distance between
the exterior of the cutting table and a boundary between the first
region and the second region, as measured from a major surface of
the cutting table, is not constant.
2. The cutting element for an earth-boring tool of claim 1, wherein
the passageway extends from the exterior, partially through the
first region, to a location spaced from the substrate by about 5%
or more of a thickness of the cutting table, as measured along a
longitudinal axis of the cutting element.
3. The cutting element for an earth-boring tool of claim 2, wherein
the passageway extends from the exterior, partially through the
first region, to a location within the first region spaced from the
boundary.
4. The cutting element of claim 1, wherein a shortest distance
between walls defining the passageway is greater than a greatest
distance between interbonded grains of superabrasive material.
5. The cutting element of claim 4, wherein the shortest distance
between walls defining the passageway is between about 0.025 mm and
about 1 mm.
6. The cutting element of claim 1, wherein a terminal end of the
passageway is located within the cutting table.
7. The cutting element of claim 1, wherein a minimum distance
between an opening of the passageway at the exterior of the cutting
table and a lateral side surface of the cutting table, as measured
in a direction perpendicular to a longitudinal axis of the cutting
element, is between about 5% and about 30% of a maximum width of
the cutting table, as measured in the same direction.
8. The cutting element of claim 1, wherein the distance between the
exterior of the cutting table and the boundary between the first
region and the second region varies with radial distance from the
longitudinal axis, with angular distance around the longitudinal
axis, or both.
9. The cutting element of claim 1, wherein the second region is
rotationally symmetrical about the longitudinal axis, reflectively
symmetrical about at least one plane intersecting the longitudinal
axis, or both.
10. An earth-boring tool, comprising: a cutting element secured to
a body, the cutting element comprising: a cutting table secured to
a substrate, the cutting table comprising: a first region at least
substantially free of solid infiltrant material in interstitial
spaces among interbonded grains of superabrasive material located
proximate a cutting face of the cutting table; a second region
comprising solid infiltrant material in the interstitial spaces
among the interbonded grains of the superabrasive material located
proximate the substrate; and a passageway extending from an
exterior of the cutting table partially through the first region;
and wherein a distance between the exterior of the cutting table
and a boundary between the first region and the second region, as
measured from a major surface of the cutting table, is not
constant.
11. A method of making a cutting element for an earth-boring tool,
comprising: placing a sacrificial material among grains of a
superabrasive material; exposing the grains of the superabrasive
material and the sacrificial material to elevated temperature and
pressure in a presence of a catalyst material, forming a cutting
table including a polycrystalline, superabrasive material; removing
the sacrificial material and a portion of the catalyst material
from a first region of the cutting table; and leaving a remainder
of the catalyst material in a second region of the cutting
table.
12. The method of claim 11, wherein placing the sacrificial
material among the grains of the superabrasive material comprises
placing a metal or metal alloy including 10% by weight or more
rhenium among the grains of the superabrasive material.
13. The method of claim 12, wherein placing the metal or metal
alloy including 10% by weight or more rhenium among the grains of
the superabrasive material comprises placing a tungsten-rhenium
alloy or material mixture among the grains of the superabrasive
material.
14. The method of claim 11, wherein placing the sacrificial
material among the grains of the superabrasive material comprises
placing a wire, foil, or sheet of the sacrificial material among
the grains of the superabrasive material.
15. The method of claim 14, wherein placing the wire, foil, or
sheet of the sacrificial material among the grains of the
superabrasive material comprises placing a wire, foil, or sheet
including one or more of bends, curves, and straight portions among
the grains of the superabrasive material.
16. The method of claim 11, wherein placing the sacrificial
material among the grains of the superabrasive material comprises
one or more ends of the sacrificial material adjacent to a wall of
the mold and otherwise surrounding the sacrificial material in the
grains of the superabrasive material.
17. The method of claim 11, further comprising removing the
sacrificial material at a greater rate than a rate at which the
portion of the catalyst material is removed.
18. The method of claim 17, further comprising removing the
sacrificial material at a rate between about 5 times and about 25
times greater than a rate at which the portion of the catalyst
material is removed.
19. The method of claim 11, wherein removing the sacrificial
material and the portion of the catalyst material comprises
exposing the cutting table to a leaching agent.
20. The method of claim 11, wherein the acts of removing the
sacrificial material and the portion of the catalyst material from
the first region and leaving the remainder of the catalyst material
in the second region comprise rendering a distance between an
exterior of the cutting table and a boundary between the first
region and the second region, as measured from a major surface of
the cutting table, non-constant.
Description
FIELD
[0001] This disclosure relates generally to cutting elements for
earth-boring tools and related earth-boring tools and methods. More
specifically, disclosed embodiments relate to techniques for
producing a desired leach profile within a cutting table of a
cutting element of an earth-boring tool.
BACKGROUND
[0002] Cutting elements used in earth-boring tools often include a
volume of polycrystalline, superabrasive material secured to a
substrate. For example, polycrystalline diamond compact (often
referred to as "PDC") cutting elements include a volume of
polycrystalline diamond material secured to a substrate of a
ceramic-metallic composite material (e.g., tungsten carbide). When
forming the polycrystalline, superabrasive material, grains of the
superabrasive material are conventionally placed in a
high-temperature/high-pressure environment in the presence of a
catalyst material to catalyze formation of intergranular bonds
among the grains and render the material polycrystalline. In some
situations, catalyst material located in the interstitial spaces
among interbonded grains of the polycrystalline, superabrasive
material, or portions thereof, may be removed. This removal reduces
stress that would otherwise be introduced due to differences in the
coefficients of thermal expansion between the polycrystalline,
superabrasive material and the catalyst material. The process of
removing catalyst material is referred to as "leaching," and is
conventionally accomplished by exposing the catalyst material to an
acid or a combination of acids (e.g., aqua regia). Complete removal
of the catalyst material, however, may render the polycrystalline,
superabrasive brittle. In an attempt to balance both concerns,
cutting elements may be produced with a portion of the catalyst
material removed from the volume of polycrystalline, superabrasive
material, and a remainder of the catalyst material still positioned
in the interstitial spaces among the grains of the polycrystalline,
superabrasive material.
BRIEF SUMMARY
[0003] Cutting elements for earth-boring tools may include a
cutting table secured to a substrate. The cutting table may include
a first region at least substantially free of solid infiltrant
material in interstitial spaces among interbonded grains of
superabrasive material located proximate a cutting face of the
cutting table, a second region comprising solid infiltrant material
in the interstitial spaces among the interbonded grains of the
superabrasive material located proximate the substrate, and a
passageway extending from an exterior of the cutting table
partially through the first region. A distance between the exterior
of the cutting table and a boundary between the first region and
the second region, as measured from a major surface of the cutting
table, may not be constant.
[0004] Earth-boring tools may include a cutting element secured to
a body. The cutting element may include a first region at least
substantially free of solid infiltrant material in interstitial
spaces among interbonded grains of superabrasive material located
proximate a cutting face of the cutting table, a second region
comprising solid infiltrant material in the interstitial spaces
among the interbonded grains of the superabrasive material located
proximate the substrate, and a passageway extending from an
exterior of the cutting table partially through the first region. A
distance between the exterior of the cutting table and a boundary
between the first region and the second region, as measured from a
major surface of the cutting table, may not be constant.
[0005] Methods of making cutting elements for earth-boring tools
may involve placing a sacrificial material among grains of a
superabrasive material. The grains of the superabrasive material
and the sacrificial material may be exposed to elevated temperature
and pressure in a presence of a catalyst material, forming a
cutting table including a polycrystalline, superabrasive material.
The sacrificial material and a portion of the catalyst material may
be removed from a first region of the cutting table, and a
remainder of the catalyst material may be left in a second region
of the cutting table.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] While this disclosure concludes with claims particularly
pointing out and distinctly claiming specific embodiments, various
features and advantages of embodiments within the scope of this
disclosure may be more readily ascertained from the following
description when read in conjunction with the accompanying
drawings, in which:
[0007] FIG. 1 is a partial cutaway perspective view of a cutting
element 100 for an earth-boring tool. The cutting element 100 may
include a cutting table 102 secured to a substrate 104.
[0008] FIG. 2 is a cross-sectional view of the cutting element of
FIG. 1;
[0009] FIG. 3 is a simplified drawing illustrating how a
microstructure of a first region of the cutting table of the
cutting element of FIGS. 1 and 2 may appear under magnification and
illustrates the substantial absence of catalyst material in
interstitial spaces among interbonded grains of superabrasive
material in the first region of the cutting table;
[0010] FIG. 4 is a simplified drawing illustrating how a
microstructure of a second region of the cutting table of the
cutting element of FIGS. 1 and 2 may appear under magnification and
illustrates the presence of catalyst material in interstitial
spaces among interbonded grains of superabrasive material in the
second region of the cutting table;
[0011] FIG. 5 is a cross-sectional view of another embodiment of a
cutting element in accordance with this disclosure;
[0012] FIG. 6 is a cross-sectional view of another embodiment of a
cutting element in accordance with this disclosure;
[0013] FIG. 7 is a cross-sectional view of another embodiment of a
cutting element in accordance with this disclosure;
[0014] FIG. 8 is a flowchart diagram of a method for forming the
cutting element of FIG. 1;
[0015] FIG. 9 is a cross-sectional view of a first intermediate
product during a first stage in the method of forming the cutting
element of FIG. 8;
[0016] FIG. 10 is a cross-sectional view of a second intermediate
product during a second stage in the method of forming the cutting
element of FIG. 8;
[0017] FIG. 11 is a cross-sectional view of a third intermediate
product during a third stage in a method of forming the cutting
element of FIG. 6;
[0018] FIG. 12 is a cross-sectional view of another embodiment of a
third intermediate product during the third stage in a method of
forming the cutting element of FIG. 7;
[0019] FIG. 13 is a perspective view of an earth-boring tool
including one or more cutting elements in accordance with this
disclosure;
[0020] FIG. 14 is a photograph surface view of a cutting face of a
cutting element in accordance with this disclosure; and
[0021] FIG. 15 is a photograph cross-sectional view of a cutaway
portion of the cutting element of FIG. 14.
DETAILED DESCRIPTION
[0022] The illustrations presented in this disclosure are not meant
to be actual views of any particular cutting element,
microstructure for a material, earth-boring tool, or component
thereof, but are merely idealized representations employed to
describe illustrative embodiments. Thus, the drawings are not
necessarily to scale.
[0023] Disclosed embodiments relate generally to techniques for
producing a desired leach profile within a cutting table of a
cutting element of an earth-boring tool. More specifically,
disclosed are embodiments of techniques for producing a desired
leach profile within a cutting table involving providing a
sacrificial material in a precursor material, forming the cutting
table, and leaching the sacrificial material and a portion of
catalyst material from the cutting table. The sacrificial material
may provide a higher-rate passageway for leaching agent to flow
from an exterior of the cutting table toward an interior, removing
the sacrificial material and catalyst material in such a way that a
resulting profile of the catalyst material remaining in the cutting
table may have a shape different from a profile of the cutting
table itself.
[0024] As used herein, the terms "substantially" and "about" in
reference to a given parameter, property, or condition means and
includes to a degree that one of ordinary skill in the art would
understand that the given parameter, property, or condition is met
with a degree of variance, such as within acceptable manufacturing
tolerances. For example, a parameter that is substantially or about
a specified value may be at least about 90% the specified value, at
least about 95% the specified value, at least about 99% the
specified value, or even at least about 99.9% the specified
value.
[0025] As used herein, the terms "earth-boring tool" means and
includes any type of bit or tool used for drilling during the
formation or enlargement of a wellbore in a subterranean formation.
For example, earth-boring tools include fixed-cutter bits, roller
cone bits, percussion bits, core bits, eccentric bits, bi-center
bits, reamers, mills, drag bits, hybrid bits (e.g., rolling
components in combination with fixed cutting elements), and other
drilling bits and tools known in the art.
[0026] As used herein, the term "superabrasive material" means and
includes any material having a Knoop hardness value of about 3,000
Kgf/mm.sup.2 (29,420 MPa) or more. Superabrasive materials include,
for example, diamond and cubic boron nitride. Superabrasive
materials may also be characterized as "superhard" materials.
[0027] As used herein, the term "polycrystalline material" means
and includes any structure comprising a plurality of grains (i.e.,
crystals) of material that are bonded directly together by
inter-granular bonds. The crystal structures of the individual
grains of the material may be randomly oriented in space within the
polycrystalline material.
[0028] As used herein, the terms "inter-granular bond" and
"interbonded" mean and include any direct atomic bond (e.g.,
covalent, metallic, etc.) between atoms in adjacent grains of
superabrasive material.
[0029] As used herein, terms of relative positioning, such as
"above," "over," "under," and the like, refer to the orientation
and positioning shown in the figures. During real-world formation
and use, the structures depicted may take on other orientations
(e.g., may be inverted vertically, rotated about any axis, etc.).
Accordingly, the descriptions of relative positioning must be
reinterpreted in light of such differences in orientation (e.g.,
resulting in the positioning structures described as being located
"above" other structures underneath or to the side of such other
structures as a result of reorientation).
[0030] FIG. 1 is a partial cutaway perspective view of a cutting
element 100 for an earth-boring tool. The cutting element 100 may
include, for example, a cutting table 102 secured to an end of a
substrate 104 at an interface 106. In additional embodiments, the
cutting table 102 may be formed and/or employed without the
substrate 104. The cutting element 100 may be generally cylindrical
or disc-shaped, as shown in FIG. 1. In other embodiments, the
cutting element 100 may have a different shape, such as a dome,
cone, or chisel shape.
[0031] The substrate 104 may have a first end surface 114, a second
end surface 116, and a generally cylindrical lateral side surface
118 extending from the first end surface 114 to the second end
surface 116. The first end surface 114 and the second end surface
116 shown in FIG. 1 are substantially planar. In other embodiments,
the first end surface 114 and/or the second end surface 116 (and,
hence, the interface 106 between the substrate 104 and the cutting
table 102) may be non-planar.
[0032] The substrate 104 may be formed of and include a hard,
wear-resistant material suitable for the downhole environment. By
way of nonlimiting example, the substrate 104 may be formed from
and include a ceramic-metal composite material (i.e., a "cermet"
material). More specifically, the substrate 104 may be formed of
and include, for example, a matrix-cemented carbide material, such
as matrix-cemented tungsten carbide material, in which tungsten
carbide particles are cemented together in a metallic matrix
material (sometimes referred to in the art as a "binder"). As used
herein, the term "tungsten carbide" means any material composition
that contains chemical compounds of tungsten and carbon, such as,
for example, WC, W.sub.2C, and combinations of WC and W.sub.2C.
Tungsten carbide includes, for example, cast tungsten carbide,
sintered tungsten carbide, and macrocrystalline tungsten carbide.
The metallic matrix material may include, for example, a catalyst
material for catalyzing intergranular bonds among grains of
superabrasive material. More specifically, the metallic matrix
material may include, for example catalyst materials including
Group VIII-A metals and alloys including Group VIII-A metals (e.g.,
cobalt, nickel, iron, alloys and/or mixtures thereof). Such
catalyst materials may be referred to in the art as "metal solvent
catalysts." As a specific, nonlimiting example, the substrate 104
may be formed of and include a cobalt-cemented tungsten carbide
material.
[0033] The cutting table 102 may be disposed on or over the first
end surface 114 of the substrate 104. The cutting table 102 may
include a volume of interbonded grains of superabrasive material,
and may have a first major surface 108 defining a cutting face of
the cutting table 102, a second major surface 109 on an opposite
side of the cutting table 102, and at least one lateral side
surface 110 extending from the second major surface 109 toward the
first major surface 108. The second major surface 109 of the
cutting table 102 may abut against the first end surface 114 of the
substrate 104 at the interface 106. A longitudinal axis A may
extend through a geometric center of the cutting table 102 in a
direction at least substantially perpendicular to the first major
surface 108.
[0034] The cutting table 102 may also include a chamfer surface 112
at a periphery of the first major surface 108 in some embodiments.
The chamfer surface 112 shown in FIG. 1 extends at an oblique angle
from the first major surface 108 to the lateral side surface 110 in
the embodiment of FIG. 1, although the cutting table 102 may have
additional chamfer surfaces, and such chamfer surfaces may be
oriented at a series of oblique angles from the first major surface
108 to the lateral side surface 110. As an alternative, one or more
surfaces of the cutting table 102 may be rounded or comprise a
combination of at least one chamfer surface and at least one
arcuate surface.
[0035] The lateral side surface 110 of the cutting table 102 may be
at least substantially flush with the lateral side surface 118 of
the substrate 104, and the cutting face 108 of the cutting table
102 may be oriented at least substantially parallel to the first
end surface 114 of the substrate 104. The cutting table 102 may be
generally cylindrical or disc-shaped. In other embodiments, the
cutting table 102 may have a different shape, such as a dome, cone,
or chisel shape. In embodiments where the cutting table 102 is
cylindrical, the cutting table 102 may have a thickness T, as
measured in a direction at least substantially parallel to the
longitudinal axis A, of between about 1 mm and about 4 mm (e.g.,
between about 1.5 mm and about 3.0 mm). As a specific, nonlimiting
example, the cutting table 102 may have a thickness T in of between
about 1.8 mm and about 2.2 mm (e.g., about 2 mm). As used herein,
ranges characterized as being between two values shall be
interpreted to include those values and all values therebetween.
For example, a range between 1 and 4 shall include 1, 4, and all
values between 1 and 4.
[0036] The cutting table 102 may include, for example, interbonded
grains of diamond or cubic boron nitride. The superabrasive
material may make up, for example, more than about 70% by volume of
the cutting table 102. More specifically, grains of the
superabrasive material may occupy between about 70% and about 90%
(e.g., about 80%) by volume of the cutting table 102.
[0037] Interstitial spaces among the interbonded grains of
superabrasive material in one or more first regions 120 of the
cutting table 102 may be at least substantially devoid of solid
infiltrated material, the interstitial spaces in such first regions
120 being occupied by environmental fluid (e.g., air). The
interstitial spaces may be occupied by (e.g., filled with) a solid
infiltrated material (e.g., a catalyst material) in one or more
second regions 122 of the cutting table 102. At least one of the
first regions 120 of the cutting table 102 at least substantially
devoid of solid infiltrated material in the interstitial spaces may
be located proximate to the exterior 124 of the cutting table 102.
For example, one or more first regions 120 may extend from one or
more of the first major surface 108, the chamber surface 112, and
the lateral side surface 110 toward the interior of the cutting
table 102. The second region(s) 122 of the cutting table 102 having
solid infiltrated material in the interstitial spaces may be
located within the interior of the cutting table 102, and at least
one first region 120 of the cutting table 102 at least
substantially devoid of solid infiltrated material in the
interstitial spaces may be interposed between each second region
122 having solid infiltrated material in the interstitial spaces
and the exterior 124.
[0038] FIG. 2 is a cross-sectional view of the cutting element 100
of FIG. 1. A profile of the second region(s) 122 of the cutting
table 102, as viewed in a plane at least substantially
perpendicular to the first major surface 108, may be different from
a profile of the cutting table 102. For example, a cross-sectional
shape of the cutting table 102 as defined by the first major
surface 108, the chamfer surface(s) 112, the lateral side surface
110, and the second major surface 109 may be rectangular with
chamfered corners on one side, as shown in the embodiment of FIG.
2. A cross-sectional shape of the second region(s) 122 of the
cutting table 102, as defined by at least a portion of the second
major surface 109 and a boundary 126 between the second region(s)
122 having solid infiltrated material in the interstitial spaces
and the first region(s) 120 at least substantially devoid of solid
infiltrated material in the interstitial spaces, may be, for
example, in the shape of a stepped pyramid or undulating series of
plateaus in the embodiment of FIG. 2. In other embodiments, the
cross-sectional shape of the second region(s) 122 of the cutting
table 102 having solid infiltrated material in the interstitial
spaces may have other shapes differing from shrunken versions of
the cross-sectional shape of the cutting table 102.
[0039] For example, a first distance Di between at least the first
major surface 108 of the cutting table 102 and the boundary 126
between the first region(s) 120 and the second region(s) may not be
constant (e.g., may vary across the first major surface 108 of the
cutting table 102). More specifically, the first distance Di
between the first major surface 108 and the boundary 126, the first
distance Di between the lateral side surface 110 and the boundary
126, or both may vary with radial distance from the longitudinal
axis A, with angular distance around the longitudinal axis A, or
both. In some embodiments, the cross-sectional shape of the second
region(s) 122 of the cutting table 102 having solid infiltrated
material in the interstitial spaces may be rotationally symmetrical
about the longitudinal axis A, reflexively symmetrical about at
least one plane intersecting the longitudinal axis A, or both. In
other embodiments, the cross-sectional shape of the second
region(s) 122 of the cutting table 102 may be rotationally
asymmetrical about the longitudinal axis A, reflectively
asymmetrical about at least one plane intersecting the longitudinal
axis A, or both.
[0040] To enable formation of such geometries for the second
region(s) 122 of the cutting table 102 having solid infiltrated
material in the interstitial spaces among interbonded grains of the
polycrystalline, superabrasive material, the first region(s) 120 of
the cutting table 102 at least substantially lacking solid
infiltrated material may include passageways 128 extending from the
exterior 124 of the cutting table 102, partially through the first
region(s) 120, toward the substrate 104. For example, one or more
passageways 128 may extend from the first major surface 108,
partially through the first region(s) 120, to locations spaced from
the substrate 104 by about 5% or more of the thickness T of the
cutting table 102. More specifically, one or more passageways 128
may extend from the first major surface 108, partially through the
first region(s) 120, to locations spaced from the substrate 104 by
between about 10% and about 50% (e.g., about 25%) of the thickness
T of the cutting table 102. As another example, one or more
passageways 128 may extend from the lateral side surface 110,
partially through the first region(s) 120, to locations within the
first region(s) 120 spaced from the boundary 126 between the first
region(s) 120 and the second region(s) 122.
[0041] The passageway(s) 128 may take the form of, for example,
tubes, channels, or other flow paths comprising spaces unoccupied
by solid infiltrated material, defined by the interbonded grains of
polycrystalline, superabrasive material, and having a larger
average diameter than the average diameters of the interstitial
spaces. Such passageway(s) 128 may enable leaching agent to which
the cutting table 102 is exposed to more easily remove those
materials that previously occupied the passageway(s) 128 and the
interstitial spaces proximate thereto, when compared to the rate at
which the leaching agent may remove material from the interstitial
spaces absent the passageways 128. As a result, a second distance
D.sub.2 from the passageway(s) 128 to the boundary 126 may be equal
to a shortest first distance D.sub.1 between the exterior 124 and
the boundary 126. In other words, the leaching depth to define the
boundary 126 may generally be equal to the second distance D.sub.2,
as measured from the exterior 124 of the cutting table 102 or a
passageway 128 proximate to the second region 122, whichever is
closest.
[0042] A shortest third distance D.sub.3 between walls 130 of the
polycrystalline, superabrasive material defining the passageway(s)
128 may be, for example, between about 0.025 mm and about 1 mm.
More specifically, the shortest third distance D.sub.3 between
walls 130 of the polycrystalline, superabrasive material defining
the passageway(s) 128 may be, for example, between about 0.05 mm
and about 0.5 mm. As specific, nonlimiting examples, the shortest
third distance D.sub.3 between walls 130 of the polycrystalline,
superabrasive material defining the passageway(s) 128 may depend
partially on what precursor structure(s) are utilized to form the
passageway(s) 128, with wires of sacrificial material generally
producing a shortest third distance D.sub.3 of between about 0.05
mm and about 1 mm and foils of sacrificial material generally
producing a shortest third distance D.sub.3 of between about 0.025
mm and about 0.5 mm.
[0043] Terminal ends 132 of the passageway(s) 128 may be located
within the cutting table 102 itself. For example, the terminal ends
132 of the passageways(s) 128 may be located within the first
region 120. More specifically, the terminal end 132 of a given
passageway 128 may be spaced from the substrate 104 by at least one
second region 122 and a portion of the first region 120 through
which the passageway 128 extends. In other embodiments, one or more
passageway(s) 128 may lack "terminal" ends 132. For example, such
passageway(s) 128 may include two openings 133 to the exterior 124
of the cutting table 102, the passageway(s) 128 extending from a
first opening 133, into and through the first region(s) 120, back
to a second opening 133.
[0044] A minimum fourth distance D.sub.4 between an opening 133 of
a passageway 128 and the lateral side surface 110 of the cutting
table, as measured in a radial direction perpendicular to the
longitudinal axis A, may be, for example, about 5% of the maximum
width W of the cutting table 102, as measured in the same
direction. More specifically, the minimum fourth distance D.sub.4
between the opening 133 of a passageway 128 and the lateral side
surface 110 of the cutting table 102 may be, for example, between
about 5% and about 30% of the maximum width W of the cutting table
102. As a specific, nonlimiting example, the minimum fourth
distance D.sub.4 between the opening 133 of a passageway 128 and
the lateral side surface 110 of the cutting table 102 may be
between about 10% and about 25% (e.g., about 15%) of the maximum
width W of the cutting table 102. Keeping the minimum fourth
distance D.sub.4 between the opening 133 of a passageway 128 and
the lateral side surface 110 of the cutting table 102 above a
certain amount may reduce the likelihood that stresses concentrated
proximate the lateral side surface 110 (e.g., due to contact
between the cutting table 102 and an underlying earth formation
during removal) will result in crack propagation from and around
the passageway(s) 128. Of course, the openings 133 to passageways
128 may also be located farther from the lateral side surface 110
than the minimum fourth distance D.sub.4, such as, for example, at
and/or proximate to the longitudinal axis A.
[0045] FIG. 3 is a simplified drawing illustrating how a
microstructure of a first region 120 of the cutting table 102 of
the cutting element 100 of FIGS. 1 and 2 may appear under
magnification and illustrates the substantial absence of solid
infiltrant material in interstitial spaces 134 among interbonded
grains 136 of superabrasive material in the first region 120 of the
cutting table 102. The passageway(s) 128 may be located within the
first region 120 and, as shown in FIG. 3, the shortest third
distance D.sub.3 between the walls 130 defining the passageway(s)
128 may be greater than the greatest distance between interbonded
grains 136 of superabrasive material defining the interstitial
spaces 134.
[0046] FIG. 4 is a simplified drawing illustrating how a
microstructure of a second region 122 of the cutting table 102 of
the cutting element 100 of FIGS. 1 and 2 may appear under
magnification and illustrates the presence of solid infiltrant
material 138 in interstitial spaces 134 among interbonded grains
136 of superabrasive material in the second region 122 of the
cutting table 102. The solid infiltrant material 138 may include,
for example, a catalyst material for catalyzing intergranular bonds
among grains 136 of superabrasive material. More specifically, the
solid infiltrant material 138 may include, for example, the same
material as the metallic matrix material from the substrate. As a
specific, nonlimiting example, the solid infiltrant material 138
may include Group VIII-A metals and alloys including Group VIII-A
metals (e.g., cobalt, nickel, iron, alloys and/or mixtures
thereof).
[0047] FIG. 5 is a cross-sectional view of another embodiment of a
cutting element 140 in accordance with this disclosure. In some
embodiments, the shape and position of the passageway(s) 128 may
enable one or more of the second region(s) 122 of the cutting table
102 including solid infiltrant material 138 in the interstitial
spaces 134 among interbonded grains 136 of superabrasive material
(see FIG. 4) to be located distal from the substrate 104. For
example, the first region 120 may extend from the first major
surface 108 of the cutting table 102, along the longitudinal axis A
to one second region 122A, laterally around the one second region
122A, longitudinally past the one second region 122A, to another
second region 122B located proximate to the substrate 104. The one
second region 122A may be located proximate to the longitudinal
axis A. For example, the longitudinal axis A may intersect with the
one second region 122A, and the one second region 122A may be
rotationally symmetrical about the longitudinal axis A. To enable
formation of such a shape for the first region 120 and second
regions 122A and 122B, the cutting table 102 may include
passageways 128 extending from the first major surface 108
laterally distal from the longitudinal axis A, along the
longitudinal axis A into the first region 120 proximate to the
first major surface 108, radially outward toward the lateral side
surface 110 above the one second region 122A, along the
longitudinal axis A past the one second region 122A proximate the
lateral sides of the one second region 122A.
[0048] FIG. 6 is a cross-sectional view of another embodiment of a
cutting element 200 in accordance with this disclosure. The shape
and position of the passageway(s) 128 may enable one or more of the
second region(s) 122 of the cutting table 102 including solid
infiltrant material 138 in the interstitial spaces 134 among
interbonded grains 136 of superabrasive material (see FIG. 4) are
located distal from the substrate 104, as with the cutting element
140 of FIG. 5. In addition, one or more of the second region(s) 122
of the cutting table 102 may be located distal from the
longitudinal axis A. For example, the first region 120 may extend
from the first major surface 108 of the cutting table 102, along
the longitudinal axis A to the other second region 122B located
proximate to the substrate 104, laterally along the other second
region 122A toward a periphery of the cutting table 102, and
longitudinally between the one second region 122A and the other
second region 122B located proximate to the substrate 104 as the
first region 120 approaches the lateral side surface 110. To enable
formation of such a shape for the first region 120 and second
regions 122A and 122B, the cutting table 102 may include
passageways 128 extending from the first major surface 108
laterally proximate to the longitudinal axis A, along the
longitudinal axis A into the first region 120 proximate to the
first major surface 108, radially outward toward the lateral side
surface 110 above the one second region 122A and underneath the one
second region 122A proximate the lateral side surface 110 of the
cutting table 102.
[0049] FIG. 7 is a cross-sectional view of another embodiment of a
cutting element 202 in accordance with this disclosure. In some
embodiments, the shape and position of the passageway(s) 128 may
enable multiple instances of the second region(s) 122 of the
cutting table 102 including solid infiltrant material 138 in the
interstitial spaces 134 among interbonded grains 136 of
superabrasive material (see FIG. 4) to be located distal from the
substrate 104. For example, the first region 120 may extend from
the first major surface 108 of the cutting table 102, along the
longitudinal axis A to the other second region 122B located
proximate to the substrate 104, laterally along the other second
region 122A toward a periphery of the cutting table 102,
longitudinally between a first instance of the one second region
122A and another instance of the one second region 122A located
distal from the substrate 104 as the first region 120 approaches
the lateral side surface 110, and longitudinally between the other
instance of the one second region 122A and the other second region
122B located proximate to the substrate 104 as the first region 120
approaches the lateral side surface 110. To enable formation of
such a shape for the first region 120 and second regions 122A and
122B, the cutting table 102 may include passageways 128 extending
from the first major surface 108 laterally proximate to the
longitudinal axis A, along the longitudinal axis A into the first
region 120 proximate to the first major surface 108, with one set
of the passageways 128 extending radially outward toward the
lateral side surface 110 above the other instance of the one second
region 122A and underneath the first instance of the one second
region 122A proximate the lateral side surface 110 of the cutting
table 102, and another set of the passageways 128 extending
radially outward toward the lateral side surface 110 above the
other second region 122B and underneath the other instance of the
one second region 122A proximate the lateral side surface 110 of
the cutting table 102. In still other embodiments, passageways 128
in accordance with this disclosure may take on other shapes and be
located at other positions within the first region(s) 120,
producing other shapes for the second region(s) 122.
[0050] FIG. 8 is a flowchart diagram of a method 142 for forming
the cutting element 100 of FIG. 1. The method 142 may involve
placing a sacrificial material 144 (see FIG. 9) among grains 136
(see FIGS. 3, 4) of superabrasive material, as shown at act 146.
FIG. 9 is a cross-sectional view of a first intermediate product
148 during a first stage in the method 142 of forming the cutting
element 100 of FIG. 8, generally corresponding to act 146.
Referring collectively to FIGS. 8 and 9, the intermediate product
148 may include a mold 150 including one or more generally
cup-shaped members 152 (e.g., defining an interior cavity 153
generally in the shape of a right cylinder or other inverse of the
shapes for cutting elements described previously), which may be
assembled and swaged and/or welded together to form the mold 150.
The intermediate product 148 may also include the grains 136 of
superabrasive material, the sacrificial material 144 partially
embedded therein, a catalyst material 154, and the substrate 104 or
precursor materials for forming the substrate 104 (e.g., ceramic
particles and powdered metal matrix material) adjacent to the
grains 136 of superabrasive material in the mold 150. The catalyst
material 154 may be in the form of, for example, the metal matrix
material of the substrate 104 or precursor material therefor, a
foil 156 interposed between the substrate 104 or its precursor
materials and the grains 136 of superabrasive material, a powder
intermixed with the grains 136 of superabrasive material, or any
combination or subcombination of these.
[0051] At this stage, the grains 136 may not be interbonded to one
another, and may be in the form of a powder or grit. The grains 136
may have a multimodal (e.g., bimodal, trimodal, etc.) or monomodal
grain size distribution, and grains 136 of different average grain
sizes may be segregated into different regions of the mold 150 to
impart desired characteristics to the resulting cutting table 102
(see FIG. 10).
[0052] The sacrificial material 144 may include one or both ends
158 adjacent to a wall 160 of the mold 150 and otherwise be
surrounded by, and embedded within, the grains 136 of superabrasive
material. The sacrificial material 144 may be positioned to form
the passageways 128, and to impart a desired geometry to the second
region(s) 122 upon removal of the sacrificial material 144 and a
portion of catalyst material 154 from within the cutting table 102
(see FIGS. 2, 5-7). The sacrificial material 144 may take the form
of, for example, a wire, foil, or sheet, and the wire, foil or
sheet may include bends, curves, straight portions, or other
geometries, as desired. Materials suitable for use as the
sacrificial material 144 may be removable by exposure to leaching
agents and may be resistant to alloying or otherwise intermixing
with the catalyst material 154. For example, the sacrificial
material 144 may include metals and metal alloys including 5% by
weight or more rhenium (e.g., a tungsten-rhenium alloy or material
mixture).
[0053] With continued reference to FIGS. 8 and 9, the method 142
may involve exposing the grains 136 of superabrasive material and
the sacrificial material 144 to elevated temperature and pressure
in the presence of the catalyst material 154 to form a cutting
table 102 including a polycrystalline, superabrasive material, as
shown at act 162. For example, a high-temperature, high-pressure
(HTHP) process may be used to sinter and interbond the grains 136
of superabrasive material in the presence of the catalyst material
154 without alloying the sacrificial material 144 with the catalyst
material 154. More specifically, using the HTHP process may place
the catalyst material 154 into a flowable state, enabling the
catalyst material 154 to flow freely among the grains 136 of
superabrasive material and catalyze interbonding among the grains
136. The HTHP process may also secure the cutting table 102 to the
first end surface 114 the substrate 104. Although the specific
parameters of HTHP processes may vary depending on the materials
used and the quantities of material in the mold 150, a pressure of
at least about 5 GPa may be applied to the mold 150, while mold 150
is exposed to a temperature above about 1320.degree. C., and
contents of the mold 150 may remain at peak pressure and peak
temperature for at least about 5 minutes. The exact conditions may
be selected to impart a desired final microstructure (e.g., the
microstructures depicted in FIGS. 3 and 4) and associated
properties to the resulting cutting table 102.
[0054] FIG. 10 is a cross-sectional view of a second intermediate
product 164 during a second stage in the method 142 of forming the
cutting element 100 of FIG. 8 generally corresponding the result of
performing act 162. The second intermediate product 164 may include
the cutting table 102 secured to the substrate 104. The cutting
table 102 may include a single second region 122, being infiltrated
throughout the interstitial spaces 138 among interbonded grains 136
of superabrasive material by the catalyst material 154 by solid
infiltrant material in the form of the catalyst material 154. The
cutting table 102 may also include one or more passageway(s) 128
extending from the exterior 124 of the cutting table 102, partially
through thickness T of the cutting table 102 toward the substrate,
as measured along the longitudinal axis A, as discussed previously.
The passageways(s) 128 may be occupied by the sacrificial material
144, the sacrificial material 144 temporarily remaining within the
cutting table 102 following the HTHP process.
[0055] FIG. 11 is a cross-sectional view of another second
intermediate product 206 during the second stage in a method of
forming the cutting element 200 of FIG. 6, and FIG. 12 is a
cross-sectional view of still another embodiment of a third
intermediate product 208 during the second stage in a method of
forming the cutting element of FIG. 7. During the second stage
shown in FIGS. 11 and 12, a protective material 204 may be
positioned over at least the exposed surfaces 116 and 118 of the
substrate 104, and optionally over portions of the exposed surfaces
108, 110, and 112 of the cutting table 102. More specifically, the
protective material 204 may be positioned over the exposed surfaces
116 and 118 of the substrate 104 and the lateral side surface 110
of the cutting table 102, the chamfer surface 112 and the first
major surface 108 (e.g., the cutting surface) of the cutting table
102 remaining free from direct contact with the protective material
204. The protective material 204 may inhibit (e.g., prevent) those
surfaces that it covers from being exposed to leaching agent,
reducing the likelihood that (e.g., preventing) the leaching agent
from removing leachable materials from those surfaces toward the
interior of the intermediate products 206 and 208. The protective
material 204 may include, for example, rubber or epoxy. The
protective material 204 may be formed utilizing any of the
techniques for utilizing a protective material (e.g., a mask)
disclosed in U.S. Pat. No. 9,534,450, issued Jan. 3, 2017, to
Cheng, the disclosure of which is incorporated in this application
in its entirety by this reference.
[0056] Returning to FIG. 8, the method 142 may involve removing the
sacrificial material 144 and a portion of the catalyst material 154
from a first region 120 of the cutting table 102, as indicated at
act 166. A remainder of the catalyst material 154 may be left
within the section region 122 of the cutting table 102, as
indicated at act 167. With combined reference to FIGS. 1, 2, and 8,
at least a portion of the cutting table 102 may be, for example,
exposed to a leaching agent, which may proceed to remove the
sacrificial material 144 and the portion of the catalyst material
154 from the exterior 124 of the cutting table 102 inward, forming
the first region(s) 120 and imparting a shape other than a shrunken
version of the shape of the cutting table 102 to the second
region(s) 122. In some embodiments, at least portions of the
substrate 104, the cutting element 102, or both may be covered in a
protective material 204, as described previously in connection with
FIGS. 11 and 12. The intermediate products 164, 206, and 208 of
FIGS. 10 through 12 (with the protective material) may be submerged
or partially submerged in the leaching agent and left for a
predetermined amount of time to achieve a desired leach depth. The
leaching agent may include, for example, an acid or combination of
acids (e.g., aqua regia). The leach time may vary from, for
example, several minutes, several hours, or several days, depending
on the materials used and the desired leach depths.
[0057] A rate at which the leaching agent may remove the
sacrificial material 144 from within the passageway(s) 128 may be
greater (i.e., faster) than a rate at which the leaching agent may
remove the catalyst material 154 from the interstitial spaces 134
among interbonded grains 136 of superabrasive material in the first
region(s) 120. For example, the rate at which the leaching agent
removes the sacrificial material 144 from within the passageway(s)
128 may be between about 5 times and about 25 times greater than
the rate at which the leaching agent removes the catalyst material
154 from the interstitial spaces 134 among interbonded grains 136
of superabrasive material in the first region(s) 120. More
specifically, the rate at which the leaching agent removes the
sacrificial material 144 from within the passageway(s) 128 may be,
for example, between about 10 times and about 20 times (e.g., about
15 times) greater than the rate at which the leaching agent removes
the catalyst material 154 from the interstitial spaces 134 among
interbonded grains 136 of superabrasive material in the first
region(s) 120.
[0058] The leaching agent may at least substantially completely
remove the sacrificial material 144 from the passageway(s) 128 and
the catalyst material 154 from the first region(s) 120. Of course,
trace amounts of the sacrificial material 144, the catalyst
material 154, or both may remain in the respective passageway(s)
128 and first region(s) 120 following the leaching process.
[0059] In some embodiments, to further impart a desired shape to
the second region(s) 122, protective material 204 (see FIGS. 11,
12) may be positioned on one or more portions of the surfaces of
the cutting table 102, such as the first major surface 108, the
chamfer surface(s) 122, the lateral side surface 110, or any
combination or subcombination of these. For example, any of the
techniques for utilizing a protective material (e.g., a mask) to
impart shape to unleached portions of a cutting table disclosed in
U.S. Pat. No. 9,534,450, issued Jan. 3, 2017, to Cheng, may be used
in addition to, and in combination with, the passageway(s) 128 and
sacrificial materials 144 of this disclosure. In other embodiments,
the cutting table 102 may be exposed to the leaching agent at least
substantially without any protective material 204 (see FIGS. 11,
12) covering the surfaces of the cutting table 102 (e.g.,
protective material covering the substrate 104 may extend to a
minor degree over the lateral side surface 110, such as covering
less than about 10% of the lateral side surface 110).
[0060] FIG. 13 is a perspective view of an earth-boring tool 166
including one or more cutting elements 100, 140, 200, and/or 202 in
accordance with this disclosure. The earth-boring tool 166 may
include a body 168 to which the cutting element(s) 100 and/or 140
may be secured. The earth-boring tool 166 specifically depicted in
FIG. 8 is configured as a fixed-cutter earth-boring drill bit,
including blades 170 projecting outward from a remainder of the
body 168 and defining junk slots 172 between rotationally adjacent
blades 170. In such an embodiment, the cutting element(s) 100, 140,
200, and/or 202 may be secured partially within pockets 174
extending into one or more of the blades 170 (e.g., proximate the
rotationally leading portions of the blades 170 as primary cutting
elements 100, 140, 200, and/or 202, rotationally following those
portions as backup cutting elements 100, 140, 200, and/or 202, or
both). However, cutting elements 100, 140, 200, and/or 202 as
described herein may be bonded to and used on other types of
earth-boring tools, including, for example, roller cone drill bits,
percussion bits, core bits, eccentric bits, bi-center bits,
reamers, expandable reamers, mills, hybrid bits, and other drilling
bits and tools known in the art.
[0061] FIG. 14 is a photograph surface view of a first major
surface 108 of a cutting element 100 in accordance with this
disclosure. FIG. 14 specifically depicts an opening 133 of a
passageway 128 at the cutting face 108 of a cutting table 102. When
forming the cutting table 102, a foil of sacrificial material
including a curve extending partially radially around the
longitudinal axis A of the cutting table 102 was employed to define
the shape and positioning of the passageway 128 and subsequently
removed, leaving the opening 133 visible in FIG. 14.
[0062] FIG. 15 is a photograph cross-sectional view of a cutaway
portion of the cutting element 100 of FIG. 15. The foil of
sacrificial material 144 used to form the passageway 128 of FIG. 14
also included a curve extending radially away from the longitudinal
axis A as radial distance from the longitudinal axis A increased.
Upon removal of the sacrificial material 144 and a portion of the
catalyst material 154, the boundary 126 between the first region
120 and the second region 122 includes a curved depression or divot
in the position interposed between the passageway 128 and the
second region 122.
[0063] Techniques for forming leaching profiles in accordance with
this disclosure may enable formation of shapes for leaching
profiles not possible utilizing conventional technique, may produce
leach profiles not matching cutting table profiles at lower cost
and greater speed when compared to conventional techniques, and may
utilize structures and materials not employed when compared to
conventional structures and materials. For example, the use of
sacrificial materials passageways for high-rate material removal
may enable discontinuous regions of leached and unleached materials
to be provided within a cutting table and may cost less and take
less time to produce a desired leach profile when compared to
conventional techniques.
[0064] Additional, nonlimiting embodiments within the scope of this
disclosure include the following:
[0065] Embodiment 1: A cutting element for an earth-boring tool,
comprising: a cutting table secured to a substrate, the cutting
table comprising: a first region at least substantially free of
solid infiltrant material in interstitial spaces among interbonded
grains of superabrasive material located proximate a cutting face
of the cutting table; a second region comprising solid infiltrant
material in the interstitial spaces among the interbonded grains of
the superabrasive material located proximate the substrate; and a
passageway extending from an exterior of the cutting table
partially through the first region; wherein a distance between the
exterior of the cutting table and a boundary between the first
region and the second region, as measured from a major surface of
the cutting table, is not constant.
[0066] Embodiment 2: The cutting element for an earth-boring tool
of Embodiment 1, wherein the passageway extends from the exterior,
partially through the first region, to a locations spaced from the
substrate by about 5% or more of a thickness of the cutting table,
as measured along a longitudinal axis of the cutting element.
[0067] Embodiment 3: The cutting element for an earth-boring tool
of Embodiment 2, wherein the passageway extends from the exterior,
partially through the first region, to a location within the first
region spaced from the boundary.
[0068] Embodiment 4: The cutting element of any one of Embodiments
1 through 3, wherein a shortest distance between walls defining the
passageway is greater than a greatest distance between interbonded
grains of superabrasive material.
[0069] Embodiment 5: The cutting element of Embodiment 4, wherein
the shortest distance between walls defining the passageway is
between about 0.025 mm and about 1 mm.
[0070] Embodiment 6: The cutting element of any one of Embodiments
1 through 5, wherein a terminal end of the passageway is located
within the cutting table.
[0071] Embodiment 7: The cutting element of any one of Embodiments
1 through 6, wherein a minimum distance between an opening of the
passageway at the exterior of the cutting table and a lateral side
surface of the cutting table, as measured in a direction
perpendicular to a longitudinal axis of the cutting element, is
between about 5% and about 30% of a maximum width of the cutting
table, as measured in the same direction.
[0072] Embodiment 8: The cutting element of any one of Embodiments
1 through 7, wherein the distance between the exterior of the
cutting table and the boundary between the first region and the
second region varies with radial distance from the longitudinal
axis, with angular distance around the longitudinal axis, or
both.
[0073] Embodiment 9: The cutting element of any one of Embodiments
1 through 8, wherein the second region is rotationally symmetrical
about the longitudinal axis, reflectively symmetrical about at
least one plane intersecting the longitudinal axis, or both.
[0074] Embodiment 10: An earth-boring tool, comprising: a cutting
element secured to a body, the cutting element comprising: a
cutting table secured to a substrate, the cutting table comprising:
a first region at least substantially free of solid infiltrant
material in interstitial spaces among interbonded grains of
superabrasive material located proximate a cutting face of the
cutting table; a second region comprising solid infiltrant material
in the interstitial spaces among the interbonded grains of the
superabrasive material located proximate the substrate; and a
passageway extending from an exterior of the cutting table
partially through the first region; wherein a distance between the
exterior of the cutting table and a boundary between the first
region and the second region, as measured from a major surface of
the cutting table, is not constant.
[0075] Embodiment 11: A method of making a cutting element for an
earth-boring tool, comprising: placing a sacrificial material among
grains of a superabrasive material; exposing the grains of the
superabrasive material and the sacrificial material to elevated
temperature and pressure in a presence of a catalyst material,
forming a cutting table including a polycrystalline, superabrasive
material; removing the sacrificial material and a portion of the
catalyst material from a first region of the cutting table; and
leaving a remainder of the catalyst material in a second region of
the cutting table.
[0076] Embodiment 12: The method of Embodiment 11, wherein placing
the sacrificial material among the grains of the superabrasive
material comprises placing a metal or metal alloy including 10% by
weight or more rhenium among the grains of the superabrasive
material.
[0077] Embodiment 13: The method of Embodiment 12, wherein placing
the metal or metal alloy including 10% by weight or more rhenium
among the grains of the superabrasive material comprises placing a
tungsten-rhenium alloy or material mixture among the grains of the
superabrasive material.
[0078] Embodiment 14: The method of any one of Embodiments 11
through 13, wherein placing the sacrificial material among the
grains of the superabrasive material comprises placing a wire,
foil, or sheet of the sacrificial material among the grains of the
superabrasive material.
[0079] Embodiment 15: The method of Embodiment 14, wherein placing
the wire, foil, or sheet of the sacrificial material among the
grains of the superabrasive material comprises placing a wire,
foil, or sheet including one or more of bends, curves, and straight
portions among the grains of the superabrasive material.
[0080] Embodiment 16: The method of any one of Embodiments 11
through 15, wherein placing the sacrificial material among the
grains of the superabrasive material comprises one or more ends of
the sacrificial material adjacent to a wall of the mold and
otherwise surrounding the sacrificial material in the grains of the
superabrasive material.
[0081] Embodiment 17: The method of any one of Embodiments 11
through 16, further comprising removing the sacrificial material at
a greater rate than a rate at which the portion of the catalyst
material is removed.
[0082] Embodiment 18: The method of Embodiment 17, further
comprising removing the sacrificial material at a rate between
about 5 times and about 25 times greater than a rate at which the
portion of the catalyst material is removed.
[0083] Embodiment 19: The method of any one of Embodiments 11
through 18, wherein removing the sacrificial material and the
portion of the catalyst material comprises exposing the cutting
table to a leaching agent.
[0084] Embodiment 20: The method of any one of Embodiments 11
through 19, wherein the acts of removing the sacrificial material
and the portion of the catalyst material from the first region and
leaving the remainder of the catalyst material in the second region
comprise rendering a distance between an exterior of the cutting
table and a boundary between the first region and the second
region, as measured from a major surface of the cutting table,
non-constant.
[0085] While certain illustrative embodiments have been described
in connection with the figures, those of ordinary skill in the art
will recognize and appreciate that the scope of this disclosure is
not limited to those embodiments explicitly shown and described in
this disclosure. Rather, many additions, deletions, and
modifications to the embodiments described in this disclosure may
be made to produce embodiments within the scope of this disclosure,
such as those specifically claimed, including legal equivalents. In
addition, features from one disclosed embodiment may be combined
with features of another disclosed embodiment while still being
within the scope of this disclosure, as contemplated by the
inventors.
* * * * *