U.S. patent application number 14/635744 was filed with the patent office on 2016-11-03 for superabrasive elements.
The applicant listed for this patent is US SYNTHETIC CORPORATION. Invention is credited to Craig H. Cooley, David P. Miess.
Application Number | 20160318154 14/635744 |
Document ID | / |
Family ID | 45092571 |
Filed Date | 2016-11-03 |
United States Patent
Application |
20160318154 |
Kind Code |
A1 |
Miess; David P. ; et
al. |
November 3, 2016 |
SUPERABRASIVE ELEMENTS
Abstract
Embodiments of the invention relate to thermally-stable
polycrystalline diamond ("PCD") elements, polycrystalline diamond
compacts ("PDCs"), and methods of fabricating such PCD elements and
PDCs. In an embodiment, a method of fabricating a thermally-stable
PCD element includes providing an at least partially leached PCD
body including a plurality of interstitial regions, and
infiltrating at least a portion of the interstitial regions of the
at least partially leached PCD body with at least a portion of an
infiltrant material. The infiltrant material may include at least
one member chosen from the group of glass, silicone, and a ceramic
having a negative coefficient of thermal expansion.
Inventors: |
Miess; David P.; (Highland,
UT) ; Cooley; Craig H.; (Saratoga Springs,
UT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
US SYNTHETIC CORPORATION |
OREM |
UT |
US |
|
|
Family ID: |
45092571 |
Appl. No.: |
14/635744 |
Filed: |
March 2, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13916798 |
Jun 13, 2013 |
9073178 |
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14635744 |
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13655185 |
Oct 18, 2012 |
8741007 |
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13916798 |
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13291463 |
Nov 8, 2011 |
8312943 |
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13655185 |
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12389882 |
Feb 20, 2009 |
8074748 |
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13291463 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B24D 18/0009 20130101;
C04B 35/52 20130101; C04B 2235/427 20130101; B24D 3/06 20130101;
B24D 3/18 20130101; B24D 3/14 20130101; C04B 2235/3244 20130101;
C04B 2235/36 20130101; C04B 2235/5445 20130101; C04B 2235/3472
20130101; C04B 2235/75 20130101; C04B 2235/3886 20130101; C04B
2235/3813 20130101; C04B 2237/363 20130101; C04B 2235/365 20130101;
C04B 2237/401 20130101; C22C 26/00 20130101; C04B 2235/5436
20130101; C04B 35/645 20130101; C04B 2235/616 20130101; C04B
2235/326 20130101; C04B 2235/5472 20130101; C04B 37/026 20130101;
C04B 2237/123 20130101; C04B 2235/483 20130101; C04B 2235/3203
20130101 |
International
Class: |
B24D 3/06 20060101
B24D003/06; B24D 18/00 20060101 B24D018/00; B24D 3/14 20060101
B24D003/14 |
Claims
1. A superabrasive element, comprising: a plurality of bonded
superabrasive grains defining a plurality of interstitial regions;
at least one material disposed in at least a portion of the
plurality of interstitial regions, wherein the at least one
material exhibits a coefficient of thermal expansion less than that
of cobalt; and a catalyst used to initially sinter the plurality of
bonded superabrasive grains disposed in at least a portion of the
plurality of interstitial regions.
2. The superabrasive element of claim 1 wherein the at least one
material includes one or more of a ceramic having a negative
coefficient of thermal expansion, glass, or silicone.
3. The superabrasive element of claim 1 wherein the at least one
material includes glass, and further wherein the glass includes at
least one member selected from the group consisting of a silicate,
a borate, and a borosilicate.
4. The superabrasive element of claim 1 wherein the at least one
material includes silicone.
5. The superabrasive element of claim 1 wherein the at least one
material includes a ceramic having a negative coefficient of
thermal expansion, and further wherein the ceramic includes at
least one member selected from zirconium tungstate, beta spodumene,
and beta eucryptite.
6. The superabrasive element of claim 1 wherein the catalyst
includes iron, cobalt, nickel, or alloys thereof.
7. The superabrasive element of claim 1 wherein the catalyst
includes a cobalt alloy.
8. The superabrasive element of claim 1 wherein the plurality of
bonded superabrasive grains include a plurality of bonded diamond
grains.
9. The superabrasive element of claim 1 wherein the at least one
material exhibits a negative coefficient of thermal expansion over
a temperature range from about -272.degree. C. to about 775.degree.
C.
10. The superabrasive element of claim 1 wherein the plurality of
bonded superabrasive grains is at least partially leached of the
catalyst.
11. A superabrasive compact, comprising: a superabrasive element
including: a working surface; an interfacial surface; a side
surface extending between the working surface and the interfacial
surface; a plurality of bonded superabrasive grains defining a
plurality of interstitial regions; at least one material disposed
in at least a portion of the plurality of interstitial regions,
wherein the at least one material exhibits a coefficient of thermal
expansion less than that of cobalt; a catalyst used to initially
sinter the plurality of bonded superabrasive grains disposed in at
least a portion of the plurality of interstitial regions; and a
substrate bonded to the interfacial surface of the superabrasive
element.
12. The superabrasive compact of claim 10 wherein the at least one
material includes one or more of a ceramic having a negative
coefficient of thermal expansion, glass, or silicone.
13. The superabrasive compact of claim 10 wherein the at least one
material includes glass, and further wherein the glass includes at
least one member selected from the group consisting of a silicate,
a borate, and a borosilicate.
14. The superabrasive compact of claim 10 wherein the at least one
material includes silicone.
15. The superabrasive compact of claim 10 wherein the at least one
material includes a ceramic having a negative coefficient of
thermal expansion, and further wherein the ceramic includes at
least one member selected from zirconium tungstate, beta spodumene,
and beta eucryptite.
16. The superabrasive compact of claim 10 wherein the catalyst
includes iron, cobalt, nickel, or alloys thereof.
17. The superabrasive compact of claim 10 wherein the catalyst
includes a cobalt alloy.
18. The superabrasive compact of claim 10 wherein the plurality of
bonded superabrasive grains include a plurality of bonded diamond
grains.
19. The superabrasive compact of claim 10 wherein the at least one
material exhibits a negative coefficient of thermal expansion over
a temperature range from about -272.degree. C. to about 775.degree.
C.
20. The superabrasive compact of claim 10 wherein the superabrasive
element is at least partially leached of the catalyst.
21. The superabrasive compact of claim 10 wherein the at least one
material is an infiltrant.
22. A superabrasive element, comprising: a plurality of bonded
diamond grains defining a plurality of interstitial regions; at
least one material disposed in at least a portion of the plurality
of interstitial regions, wherein the at least one material exhibits
a negative coefficient of thermal expansion; and a cobalt alloy
catalyst used to initially sinter the plurality of bonded
superabrasive grains disposed in at least a portion of the
plurality of interstitial regions.
23. The superabrasive element of claim 22 wherein the at least one
material includes a ceramic having a negative coefficient of
thermal expansion.
24. The superabrasive element of claim 22 wherein the cobalt alloy
includes a cobalt-iron alloy.
25. The superabrasive element of claim 22 wherein the at least one
material is an infiltrant.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 13/916,798 filed on 13 Jun. 2013, which is a continuation of
U.S. application Ser. No. 13/655,185 filed on 18 Oct. 2012 (now
U.S. Pat. No. 8,741,007 issued on 3 Jun. 2014), which is a
continuation of U.S. application Ser. No. 13/291,463 filed on 8
Nov. 2011 (now U.S. Pat. No. 8,312,943 issued on 20 Nov. 2012),
which is a continuation of U.S. application Ser. No. 12/389,882
filed on 20 Feb. 2009 (now U.S. Pat. No. 8,074,748 issued on 13
Dec. 2011), the contents of each of the foregoing applications and
patents are incorporated herein, in their entirety, by this
reference.
BACKGROUND
[0002] Wear-resistant, polycrystalline diamond compacts ("PDCs")
are utilized in a variety of mechanical applications. For example,
PDCs are used in drilling tools (e.g., cutting elements, gage
trimmers, etc.), machining equipment, bearing apparatuses,
wire-drawing machinery, and in other mechanical apparatuses.
[0003] PDCs have found particular utility as superabrasive cutting
elements in rotary drill bits, such as roller-cone drill bits and
fixed-cutter drill bits. A PDC cutting element typically includes a
superabrasive diamond layer commonly known as a diamond table. The
diamond table is formed and bonded to a substrate using a
high-pressure/high-temperature ("HPHT") process. The PDC cutting
element may also be brazed directly into a preformed pocket,
socket, or other receptacle formed in a bit body. The substrate may
often be brazed or otherwise joined to an attachment member, such
as a cylindrical backing A rotary drill bit typically includes a
number of PDC cutting elements affixed to the bit body. It is also
known that a stud carrying the PDC may be used as a PDC cutting
element when mounted to a bit body of a rotary drill bit by
press-fitting, brazing, or otherwise securing the stud into a
receptacle formed in the bit body.
[0004] Conventional PDCs are normally fabricated by placing a
cemented-carbide substrate into a container with a volume of
diamond particles positioned on a surface of the cemented-carbide
substrate. A number of such containers may be loaded into an HPHT
press. The substrate(s) and volume of diamond particles are then
processed under HPHT conditions in the presence of a catalyst
material that causes the diamond particles to bond to one another
to form a matrix of bonded diamond grains defining a
polycrystalline diamond ("PCD") table. The catalyst material is
often a metal-solvent catalyst (e.g., cobalt, nickel, iron, or
alloys thereof) that is used for promoting intergrowth of the
diamond particles.
[0005] In one conventional approach, a constituent of the
cemented-carbide substrate, such as cobalt from a cobalt-cemented
tungsten carbide substrate, liquefies and sweeps from a region
adjacent to the volume of diamond particles into interstitial
regions between the diamond particles during the HPHT process. The
cobalt acts as a catalyst to promote intergrowth between the
diamond particles, which results in formation of a matrix of bonded
diamond grains having diamond-to-diamond bonding therebetween, with
interstitial regions between the bonded diamond grains being
occupied by the solvent catalyst.
[0006] The presence of the solvent catalyst in the PCD table is
believed to reduce the thermal stability of the PCD table at
elevated temperatures. For example, the difference in thermal
expansion coefficient between the diamond grains and the solvent
catalyst is believed to lead to chipping or cracking of the PCD
table during drilling or cutting operations, which consequently can
degrade the mechanical properties of the PCD table or cause
failure. Additionally, some of the diamond grains can undergo a
chemical breakdown or back-conversion to graphite via interaction
with the solvent catalyst. At elevated high temperatures, portions
of diamond grains may transform to carbon monoxide, carbon dioxide,
graphite, or combinations thereof, causing degradation of the
mechanical properties of the PCD table.
[0007] One conventional approach for improving the thermal
stability of PDCs is to at least partially remove the solvent
catalyst from the PCD table of the PDC by acid leaching. In another
conventional approach for forming a PDC, a sintered PCD table may
be separately formed and then leached to remove the solvent
catalyst from interstitial regions between bonded diamond grains.
The leached PCD table may be simultaneously HPHT bonded to a
cemented-carbide substrate and infiltrated with silicon in a
separate HPHT process. The silicon may infiltrate the interstitial
regions of the leached PCD table from which the solvent catalyst
has been leached and react with the diamond grains to form silicon
carbide. However, pure silicon may reduce the strength of the bond
between the PCD table and the cemented-carbide substrate, and cause
other processing problems.
[0008] Despite the availability of a number of different PDCs,
manufacturers and users of PDCs continue to seek PDCs that exhibit
improved toughness, wear resistance, and/or thermal stability.
SUMMARY
[0009] Embodiments of the invention relate to thermally-stable PCD
elements, PDCs, and methods of fabricating such PCD elements and
PDCs. In an embodiment, a PCD element includes a PCD body
comprising bonded diamond grains defining a plurality of
interstitial regions. The PCD body further includes a first volume
having a first portion of the interstitial regions and a second
volume having a second portion of the interstitial regions. An
infiltrant is disposed in the first portion of the interstitial
regions of the first volume and the second portion of the
interstitial regions of the second volume is substantially free of
the infiltrant. The infiltrant comprises a glass, a glass-ceramic,
a thermal decomposition reaction product of silicone, silicone, a
ceramic having a negative coefficient of thermal expansion, or
combinations thereof.
[0010] In an embodiment, a PDC includes a substrate and a
thermally-stable PCD table bonded to the substrate. The PCD table
includes bonded diamond grains defining a plurality of interstitial
regions. The PCD table further includes a first volume remote from
the substrate having an infiltrant disposed interstitially between
the bonded diamond grains thereof and a second volume adjacent to
the substrate having a metal-solvent catalyst disposed
interstitially between the bonded diamond grains thereof. The
infiltrant comprises a glass, a glass-ceramic, a thermal
decomposition reaction product of silicone, silicone, a ceramic
having a negative coefficient of thermal expansion, or combinations
thereof.
[0011] In an embodiment, a method of manufacturing a
thermally-stable PCD element includes positioning an infiltrant
material adjacent to a surface of an at least partially leached PCD
body including a plurality of interstitial regions. The infiltrant
material includes a glass, silicone, a ceramic having a negative
coefficient of thermal expansion, or combinations thereof. The
method further includes infiltrating at least a portion of the
infiltrant material through the surface and into only a portion of
the interstitial regions of the at least partially leached PCD
body. In one embodiment, a PDC may be fabricated by placing the at
least partially leached PCD table between the substrate and the
infiltrant material, and subjecting the combination to an HPHT
process.
[0012] In an embodiment, a method of forming a thermally-stable PDC
includes providing a PDC comprising an at least partially leached
PCD table including a plurality of interstitial regions and bonded
to a substrate. The method further includes infiltrating at least a
portion of the interstitial regions of the at least partially
leached PCD table with an infiltrant material comprising a glass,
silicone, a ceramic having a negative coefficient of thermal
expansion, or combinations thereof.
[0013] Other embodiments include applications utilizing the
disclosed PCD elements and PDCs in various articles and
apparatuses, such as rotary drill bits, bearing apparatuses,
wire-drawing dies, machining equipment, and other articles and
apparatuses.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The drawings illustrate several embodiments of the
invention, wherein identical reference numerals refer to identical
elements or features in different views or embodiments shown in the
drawings.
[0015] FIG. 1 is a cross-sectional view of an embodiment of a
thermally-stable PCD element.
[0016] FIG. 2 is a cross-sectional view of an assembly to be
processed under HPHT conditions or using a hot isostatic pressing
("HIP") process to form the PCD element shown in FIG. 1 according
to an embodiment of method.
[0017] FIG. 3 is a cross-sectional view of an embodiment of a
thermally-stable PDC.
[0018] FIG. 4 is a cross-sectional view of an assembly to be HPHT
processed to form the PDC shown in FIG. 3 according to an
embodiment of method.
[0019] FIGS. 5A through 5D are cross-sectional views at various
stages during a method of fabricating the PDC shown in FIG. 3
according to an embodiment of method.
[0020] FIG. 6A is an isometric view of an embodiment of a rotary
drill bit that may employ one or more of the disclosed PDC/PCD
element embodiments.
[0021] FIG. 6B is a top elevation view of the rotary drill bit
shown in FIG. 6A.
[0022] FIG. 7 is an isometric cut-away view of an embodiment of a
thrust-bearing apparatus that may utilize one or more of the
disclosed PDC/PCD element embodiments.
[0023] FIG. 8 is a schematic isometric cut-away view of an
embodiment of a subterranean drilling system including the
thrust-bearing apparatus shown in FIG. 7.
[0024] FIG. 9 is a side cross-sectional view of an embodiment of a
wire-drawing die that employs a PDC/PCD element fabricated in
accordance with the principles described herein.
DETAILED DESCRIPTION
[0025] Embodiments of the invention relate to thermally-stable PCD
elements, PDCs, and methods of fabricating such PCD elements and
PDCs. The disclosed PCD elements comprise a first volume including
a glass, a glass-ceramic, silicone, a thermal decomposition
reaction product of silicone, a ceramic having a negative
coefficient of thermal expansion, or combinations thereof to
provide a thermally-stable working region, and a second volume that
has been infiltrated with a metal-solvent catalyst for bonding to a
substrate or a braze alloy for bonding to a matrix-type bit body of
a rotary drill bit. The PCD elements and PDCs disclosed herein may
be used in a variety of applications, such as rotary drill bits,
bearing apparatuses, wire-drawing dies, machining equipment, and
other articles and apparatuses.
[0026] FIG. 1 is a cross-sectional view of an embodiment of a
thermally-stable PCD element 100 that may be used as PCD cutting
element. The PCD element 100 comprises a PCD body 102 including a
plurality of bonded diamond grains having diamond-to-diamond
bonding therebetween. The plurality of bonded diamond grains
defines a plurality of interstitial regions. The PCD body 102
includes a working upper surface 104 and an opposing back surface
106. The PCD body 102 includes a first volume 108 having a first
portion of the interstitial regions, with the first volume 108
extending from the upper surface 104 to an intermediate depth d
within the PCD body 102. The PCD body 102 includes a second volume
110 having a second portion of the interstitial regions, with the
second volume 110 extending inwardly from the back surface 106.
Although the upper surface 104 is illustrated as being
substantially planar, the upper surface may be nonplanar (e.g.,
convex or concave) and a working region of the PCD body 102 may
include peripheral portions of the first volume 108.
[0027] In an embodiment, the intermediate depth d to which the
first volume 108 extends may be about the entire thickness of the
PCD body 102. In another embodiment, the intermediate depth d may
be about 50 .mu.m to about 500 .mu.m, such as about 200 .mu.m to
about 400 .mu.m.
[0028] An infiltrant, including a glass, a glass-ceramic, silicone,
a thermal decomposition reaction product of silicone, a ceramic
having a negative coefficient of thermal expansion, or combinations
thereof, is disposed in the first portion of the interstitial
regions of the PCD body 102. The infiltrant is generally
non-catalytic relative to diamond so that at elevated temperatures
the infiltrant does not promote chemical breakdown or
back-conversion of the diamond grains to graphite, carbon monoxide,
and/or carbon dioxide, which results in degradation of the
mechanical properties of the PCD element 100. The interstitial
regions of the second volume 110 of the PCD body 102 may be
substantially free of the infiltrant.
[0029] Suitable glasses for the infiltrant include, but are not
limited to, a silicate glass, a borate glass, a phosphate glass, a
borosilicate glass, and combinations of any of the foregoing
glasses. For example, the infiltrant may comprise sodium silicate,
zirconium silicate, lithium silicate, sodium borosilicate,
zirconium borosilicate, lithium borosilicate, lithium
aluminosilicate, or combinations thereof. In some embodiments, any
of the foregoing glasses may be reinforced with a filler made from
ceramic particles. For example, the ceramic particles may include,
but are not limited to, boron nitride particles, titanium diboride
particles, zirconium oxide particles, and combinations of the
foregoing ceramic particles.
[0030] Suitable glass-ceramics for the infiltrant include, but are
not limited to, a silicate glass, a borate glass, a phosphate
glass, a borosilicate glass, and combinations of any of the
foregoing glasses that include beta spodumene
("LiAlSi.sub.2O.sub.6") and/or beta eucryptite
("LiAlSi.sub.4O.sub.10") as a constituent. Other glass-ceramics
include a silicate glass, a borate glass, a phosphate glass, a
borosilicate glass, an aluminosilicate glass, and combinations of
any of the foregoing glasses that have been partially
crystallized.
[0031] The infiltrant may also include or may be made from a
ceramic having a negative coefficient of thermal expansion. One
suitable ceramic having a negative coefficient of thermal expansion
is zirconium tungstate, which contracts continuously over a
temperature range from -272.degree. C. to about 775.degree. C.
Previously-mentioned ceramics having a negative coefficient of
thermal expansion are beta spodumene and beta eucryptite.
Furthermore, combinations of zirconium tungstate, beta spodumene,
and beta eucryptite may also be employed. By providing an
infiltrant that exhibits a negative to a small positive coefficient
of thermal expansion, thermal stresses and/or thermal damage (e.g.,
breaking diamond-to-diamond bonds) may be reduced as the
temperature of the PCD element 100 increases during use (e.g.,
during cutting a subterranean formation during drilling) compared
to when the infiltrant is metallic, such as a metal-solvent
catalyst.
[0032] The infiltrant occupying the first portion of the
interstitial regions of the first volume 108 may also include
silicone, a thermal decomposition reaction product of silicone, or
combinations thereof. As will become apparent from reading the
following description of methods for fabricating the PCD element
100, the thermal decomposition reaction product of silicone is a
by-product of a silicone-based infiltrant that has been infiltrated
into the PCD body 102 during a process at a temperature sufficient
to at least partially thermally decompose the silicone-based
infiltrant, such as an HPHT process or a HIP process.
[0033] The second volume 110 of the PCD body 102 is substantially
free of the infiltrant. Depending upon the particular application
for the PCD element 100, the second portion of the interstitial
regions of the second volume 110 may include a metal-solvent
catalyst for bonding to a substrate (not shown) or a braze alloy
used to braze the second volume 110 to a matrix-type bit body (not
shown) of a rotary drill bit.
[0034] FIG. 2 is a cross-sectional view of an assembly 200 to be
processed under HPHT conditions or using a HIP process to form the
PCD element 100 shown in FIG. 1 according to an embodiment of
method. Referring to FIG. 2, an at least partially leached PCD body
202 may be provided that includes the upper surface 104 and the
opposing back surface 106. The at least partially leached PCD body
202 includes a plurality of bonded diamond grains defining a
plurality of interstitial regions that were previously occupied by
a metal-solvent catalyst (e.g., cobalt, nickel, iron, or alloys
thereof) used to sinter the diamond particles. The plurality of
interstitial regions forms a network of at least partially
interconnected pores that extend between the upper surface 104 and
the back surface 106.
[0035] A layer 204 of infiltrant material may be positioned
adjacent to the upper surface 104 to form the assembly 200, such as
by coating the upper surface 104 with the infiltrant material or
disposing the infiltrant material in the bottom of a container and
placing the at least partially leached PCD body 202 in the
container and in contact with the infiltrant material. In some
embodiments, the infiltrant material of the layer 204 may be in
particulate form, a solid, in a liquid solution, a paste, or any
other form that is capable of infiltrating into the interstitial
regions of the at least partially leached PCD body 202.
[0036] Suitable infiltrant materials for the layer 204 include
high-temperature specialty coatings commercially available from
Aremco of Valley Cottage, New York. For example, Aremco-Seal.TM.
613 and 617 are two suitable glass-based high-temperature specialty
coatings commercially available from Aremco. As another example,
Aremco-Cerama-Dip.TM. 538N is a suitable zirconium silicate-based
high-temperature specialty coating commercially available from
Aremco. Another suitable high-temperature specialty coating
commercially available from Aremco is Aremco-Seal.TM. 529, which is
a silicone-based coating. Any of the foregoing high-temperature
specialty coatings commercially available from Aremco may be
brushed onto the upper surface 104 of the at least partially
leached PCD body 202 and/or brushed into a container in which the
at least partially leached PCD body 202 is disposed. Other suitable
infiltrant materials include, but are not limited to, glass
powders, such as particles of sodium silicate, zirconium silicate,
lithium silicate, sodium borosilicate, zirconium borosilicate,
lithium borosilicate, lithium aluminosilicate, and mixtures
thereof.
[0037] The at least partially leached PCD body 202 and the layer
204 of infiltrant material may be placed in a pressure transmitting
medium, such as a refractory metal can embedded in pyrophyllite or
other gasket medium. The pressure transmitting medium, including
the at least partially leached PCD body 202 and layer 204 of
infiltrant material, may be subjected to an HPHT process using an
ultra-high pressure press to create temperature and pressure
conditions at which diamond is stable. The temperature of the HPHT
process may be at least about 1000.degree. C. (e.g., about
1200.degree. C. to about 1600.degree. C.) and the pressure of the
HPHT process may be at least 4.0 GPa (e.g., about 5.0 GPa to about
8.0 GPa) for a time sufficient to infiltrate the at least partially
leached PCD body 202 with the infiltrant material. For example, the
pressure of the HPHT process may be about 5 GPa to about 7 GPa and
the temperature of the HPHT process may be about 1150.degree. C. to
about 1400.degree. C. (e.g., about 1200.degree. C. to about
1300.degree. C.).
[0038] During the HPHT process, infiltrant material from the layer
204 infiltrates into the first volume 108 of the at least partially
leached PCD body 202 generally to the intermediate depth d to fill
a first portion of the interstitial regions thereof and form the
PCD element 100 as illustrated in FIG. 1. The first portion of
first volume 108 of the PCD body 202 extends from the upper surface
104 to the intermediate depth d therewithin. The amount of
infiltrant material in the layer 204 and the HPHT process
conditions (e.g., time, temperature, and/or pressure) are selected
so that the infiltrant material only infiltrates into the first
volume 108 of the at least partially leached PCD body 202 to the
intermediate depth d. The second volume 110 of the infiltrated PCD
body 202 remains substantially free of the infiltrant.
[0039] The HPHT process may also chemically modify the infiltrant
material of the layer 204. For example, various solvents included
in the infiltrant material may evaporate at the high temperature
employed in the HPHT process. Some of the glass-based infiltrant
materials may partially crystallize to form a glass-ceramic during
the HPHT process. When the infiltrant material is a silicone-based
material, the resultant infiltrant in the first volume 108 may
include silicone, a thermal decomposition reaction product of
silicone formed as a result of the high-temperature employed in the
HPHT process, or combinations thereof
[0040] As discussed with respect to FIG. 1, if desired, the PCD
element 100 so-formed may be brazed to another structure, such as a
matrix-type bit body of a rotary drill bit, using a brazing
process. In such an embodiment, a suitable braze alloy may be
placed between the PCD element 100 and the bit body, and subjected
to a braze cycle to cause the braze alloy to melt and infiltrate
into the second portion of the interstitial regions in the second
volume 110 of the PCD element 100. Upon cooling a strong brazed
joint may be formed due to the metallurgical bond between the
second volume 110 of the PCD element 100 and the bit body.
[0041] The at least partially leached PCD body 202 shown in FIG. 2
may be fabricated by subjecting a plurality of diamond particles to
an HPHT sintering process in the presence of a metal-solvent
catalyst (e.g., cobalt, nickel, iron, or alloys thereof) to
facilitate intergrowth between the diamond particles and form a PCD
body comprised of bonded diamond grains that exhibit
diamond-to-diamond bonding therebetween. For example, the
metal-solvent catalyst may be mixed with the diamond particles or
infiltrated from a metal-solvent catalyst foil or powder adjacent
to the diamond particles. The bonded diamond grains define
interstitial regions, with the metal-solvent catalyst disposed
within the interstitial regions. The diamond particles may exhibit
a single-mode diamond particle size distribution, or a bimodal or
greater diamond particle size distribution. The as-sintered PCD
body may be leached by immersion in an acid, such as aqua regia,
nitric acid, hydrofluoric acid, or subjected to another suitable
process to remove at least a portion of the metal-solvent catalyst
from the interstitial regions of the PCD body and form the at least
partially leached PCD body 202. For example, the as-sintered PCD
body may be immersed in the acid for about 2 to about 7 days (e.g.,
about 3, 5, or 7 days) or for a few weeks (e.g., about 4 weeks)
depending on the process employed.
[0042] The plurality of diamond particles sintered to form the at
least partially leached PCD body 202 may exhibit one or more
selected sizes. The one or more selected sizes may be determined,
for example, by passing the diamond particles through one or more
sizing sieves or by any other method. In an embodiment, the
plurality of diamond particles may include a relatively larger size
and at least one relatively smaller size. As used herein, the
phrases "relatively larger" and "relatively smaller" refer to
particle sizes determined by any suitable method, which differ by
at least a factor of two (e.g., 40 .mu.m and 20 .mu.m). More
particularly, in various embodiments, the plurality of diamond
particles may include a portion exhibiting a relatively larger size
(e.g., 100 .mu.m, 90 .mu.m, 80 .mu.m, 70 .mu.m, 60 .mu.m, 50 .mu.m,
40 .mu.m, 30 .mu.m, 20 .mu.m, 15 .mu.m, 12 .mu.m, 10 .mu.m, 8
.mu.m) and another portion exhibiting at least one relatively
smaller size (e.g., 30 .mu.m, 20 .mu.m, 10 .mu.m, 15 .mu.m, 12
.mu.m, 10 .mu.m, 8 .mu.m, 4 .mu.m, 2 .mu.m, 1 .mu.m, 0.5 .mu.m,
less than 0.5 .mu.m, 0.1 .mu.m, less than 0.1 .mu.m). In another
embodiment, the plurality of diamond particles may include a
portion exhibiting a relatively larger size between about 40 .mu.m
and about 15 .mu.m and another portion exhibiting a relatively
smaller size between about 12 .mu.m and 2 .mu.m. Of course, the
plurality of diamond particles may also comprise three or more
different sizes (e.g., one relatively larger size and two or more
relatively smaller sizes) without limitation.
[0043] Instead of infiltrating the at least partially leached PCD
body 202 in an HPHT process, in another embodiment, the infiltrant
material of the layer 204 may be infiltrated into the at least
partially leached PCD body 202 using a HIP process that employs
significantly lower pressure. In such an embodiment, the
temperature of the HIP process should be kept sufficiently low
and/or the process time sufficiently short so that the diamond
grains of the at least partially leached PCD body 202 are not
significantly degraded.
[0044] FIG. 3 is a cross-sectional view of an embodiment of a PDC
300. The PDC 300 includes a thermally-stable PCD table 302 having a
working upper surface 304 and an opposing interfacial surface 306.
The interfacial surface 306 of the PCD table 302 is bonded to a
substrate 308. The substrate 308 may include, without limitation,
cemented carbides, such as tungsten carbide, titanium carbide,
chromium carbide, niobium carbide, tantalum carbide, vanadium
carbide, or combinations thereof cemented with iron, nickel,
cobalt, or alloys thereof. For example, in one embodiment, the
substrate 308 comprises cobalt-cemented tungsten carbide. Although
the interfacial surface 306 of the PCD table 302 is depicted in
FIG. 3 as being substantially planar, the interfacial surface 306
may exhibit a selected nonplanar topography.
[0045] The PCD table 302 includes a plurality of bonded diamond
grains having diamond-to-diamond bonding therebetween. The
plurality of bonded diamond grains defines a plurality of
interstitial regions. The PCD table 302 includes a first volume 310
remote from the substrate 308 that extends from the upper surface
304 to an indeterminate depth d within the PCD table 302. The first
volume 310 includes a first portion of the interstitial regions. A
second volume 312 of the PCD table 302 adjacent to the substrate
308 includes a second portion of the interstitial regions.
[0046] In an embodiment, the intermediate depth d to which the
first volume 310 extends may be about the entire thickness of the
PCD table 302. In another embodiment, the intermediate depth d may
be about 50 .mu.m to about 500 .mu.m, such as about 200 .mu.m to
about 400 .mu.m.
[0047] Any of the previously described infiltrants, such as a
glass, a glass-ceramic, silicone, a thermal decomposition reaction
product of silicone, a ceramic having a negative coefficient of
thermal expansion, or combinations thereof may occupy the first
portion of the interstitial regions of the PCD table 302. Because
the infiltrant is generally non-catalytic relative to diamond, the
first volume 310 of the PCD table 302 provides a relatively
thermally-stable working region compared to the second volume 312.
Although PCD table 302 is illustrated as having a substantially
planar upper surface 304, the upper surface may be nonplanar (e.g.,
convex or concave) and include peripheral portions of the first
volume 310. The second volume 312 of the PCD table 302 may be
infiltrated with a metal-solvent catalyst infiltrated from the
substrate 308, such as cobalt from a cobalt cemented tungsten
carbide substrate, or other source. The infiltrated metal-solvent
catalyst from the substrate 308 provides a strong metallurgical
bond between the interfacial surface 306 of the PCD table 302 and
the substrate 308.
[0048] In one embodiment, the PCD table 302 may be a pre-sintered
PCD table that is bonded to the substrate 308 subsequent to being
formed. In another embodiment, the PCD table 302 may be integrally
formed with the substrate 308 by placing diamond powder adjacent to
the substrate 308, subjecting the combination to an HPHT process,
and substantially removing metal-solvent catalyst in the PCD table
so-formed using a leaching process.
[0049] FIG. 4 is a cross-sectional view of an assembly 404 to be
HPHT processed to form the PDC shown in FIG. 3 according to an
embodiment of method. An at least partially leached PCD table 400
may be positioned between a layer 402 of infiltrant material and
the substrate 308 to form an assembly 404. The at least partially
leached PCD table 400 may exhibit the same or similar structure as
the at least partially leached PCD body 202 shown in FIG. 2 and may
fabricated in the same fashion. The infiltrant material may be
selected from one or more of the infiltrant materials used for the
infiltrant material of the layer 204 shown in FIG. 2. The layer 402
may be applied to the upper surface 304 of the at least partially
leached PCD table 402, and the interfacial surface 306 of the at
least partially leached PCD table 400 may be positioned adjacent to
the substrate 308. The assembly 404 may be enclosed in a suitable
pressure transmitting medium and subjected to an HPHT process to
form the PDC 300 (FIG. 3) using the same or similar HPHT conditions
previously discussed with respect to HPHT processing the assembly
200 shown in FIG. 2.
[0050] During the HPHT process, the lower melting infiltrant
material of the layer 402 infiltrates into a first portion of the
interstitial regions of the at least partially leached PCD table
400. Depending upon the particular infiltrant material employed,
any of the previously described infiltrants (e.g., a glass, a
glass-ceramic, a silicone, a thermal decomposition reaction product
of silicone, a ceramic having a negative coefficient of thermal
expansion, or combinations thereof) may occupy the first portion of
the interstitial regions of the at least partially leached PCD
table 400. The metal-solvent catalyst of the substrate 308
liquefies at a higher temperature, and infiltrates subsequent to
infiltration of the infiltrant material of the layer 402 and into a
second portion of the interstitial regions of the at least
partially leached PCD table 400 so that a strong metallurgical bond
is formed between the substrate 308 and the interfacial surface 306
upon cooling. The infiltrant that occupies the first portion of the
interstitial regions substantially blocks or at least limits
further infiltration into the at least partially leached PCD table
400 by the metal-solvent catalyst.
[0051] In an embodiment, when the infiltrant material of the layer
402 is made predominately from a glass (e.g., a borosilicate-based
glass) and the substrate 308 is a cobalt-cemented carbide
substrate, the infiltrant material flows and infiltrates into the
at least partially leached PCD table 400 at or slightly above about
800.degree. C. and cobalt-cemented carbide substrate from the
substrate 308 liquefies and sweeps into the at least partially
leached PCD table 400 at around about 1490.degree. C.
[0052] In an embodiment, the metal-solvent catalyst may also be
provided from an intermediate layer disposed between the at least
partially leached PCD table 400 and the substrate 308. The
intermediate layer may include any of the aforementioned
metal-solvent catalysts. For example, the intermediate layer may
include a plurality of metal-solvent catalyst particles, or a thin
foil or plate made from the metal-solvent catalyst.
[0053] In other embodiments, the at least partially leached PCD
table 400 is infiltrated with the infiltrant material from the
layer 402 to a selected depth in a first HPHT or HIP process and is
subsequently bonded to the substrate 308 by brazing, using a
separate HPHT bonding process, or another suitable joining
technique, without limitation.
[0054] FIGS. 5A through 5D are cross-sectional views at various
stages during a method of fabricating the PDC 300 shown in FIG. 3
according to another embodiment of method. Referring to FIG. 5A, a
plurality of diamond particles (i.e., diamond powder) may be placed
adjacent to the substrate 308. Referring to FIG. 5B, subjecting the
diamond particles 500 and the substrate 308 to an HPHT process
sweeps metal-solvent catalyst from the substrate 308 into the
diamond particles 500 to catalyze formation of a PCD table 502
therefrom that is integrally formed and bonded to the substrate
308. The PCD table 502 comprises bonded diamond grains defining a
plurality of interstitial regions in which the swept-in
metal-solvent catalyst is disposed.
[0055] Referring to FIG. 5C, the metal-solvent catalyst
interstitially disposed between the bonded diamond grains of the
PCD table 502 may be substantially removed to a selected depth d
using a leaching process to form an at least partially leached
region 504 remote from the substrate 308. For example, the PCD
table 502 may be exposed to an acid, such as aqua regia, nitric
acid, hydrofluoric acid, or subjected to another suitable process
to substantially remove the metal-solvent catalyst and form the at
least partially leached region 504. Region 506 of the PCD table 502
adjacent to the substrate 308 still includes the swept-in
metal-solvent catalyst from the substrate 308 disposed
interstitially between bonded diamond grains.
[0056] Referring to FIG. 5D, a layer 402 of infiltrant material may
be placed adjacent to a working upper surface 508 of the PCD table
502 and infiltrated into the interstitial regions of the at least
partially leached region 504 using another HPHT process or a HIP
process to form the PDC 300 shown in FIG. 3. The temperature of the
HPHT or HIP process may be selected to be less than a temperature
at which the metal-solvent catalyst in the region 506 of the PCD
table 502 or the substrate 308 partially liquefies to prevent
re-infiltration of the at least partially leached region 504 with
the metal-solvent catalyst.
[0057] The following working examples set forth various
formulations for forming PDCs. In the following working examples,
the thermal stability of conventional working examples 1 through 3
is compared to the thermal stability of working examples 4 through
7 of the invention.
COMPARATIVE EXAMPLE 1
[0058] A conventional PDC was obtained that was fabricated by
placing a layer of diamond particles having an average particle
size of about 19 .mu.m adjacent to a cobalt-cemented tungsten
carbide substrate. The layer and substrate were placed in a
container assembly. The container assembly including the layer and
substrate therein were subjected to HPHT conditions in an HPHT
press at a temperature of about 1400.degree. C. and a pressure of
about 5 GPa to about 8 GPa to form a conventional PDC including a
PCD table integrally formed and bonded to the substrate. Cobalt was
infiltrated into the layer of diamond particles from the substrate
catalyzing the formation of the PCD table. The thickness of the PCD
table of the PDC was about 0.095 inch and an about 0.011-inch
chamfer was machined in the PCD table.
[0059] The thermal stability of the PCD table of the conventional
PDC so-formed of comparative example 1 was evaluated by measuring
the distance cut in a Barre granite workpiece prior to failure,
without using coolant, in a vertical turret lathe test. The
distance cut is considered representative of the thermal stability
of the PCD table. The test parameters were a depth of cut for the
PDC of about 1.27 mm, a back rake angle for the PDC of about 20
degrees, an in-feed for the PDC of about 1.524 mm/rev, a cutting
speed of the workpiece to be cut of about 1.78 msec, and the
workpiece had an outer diameter of about 914 mm and an inner
diameter of about 254 mm. The conventional PDC of comparative
example 1 was able to cut a distance of about 1715 linear feet in
the workpiece prior to failure.
COMPARATIVE EXAMPLE 2
[0060] A PDC was obtained that was fabricated as performed in
comparative example 1. The thickness of the PCD table of the PDC
was about 0.09155 inch and an about 0.01285-inch chamfer was
machined in the PCD table. Then, the PCD table was acid leached to
a depth of about 87 .mu.m. The thermal stability of the PCD table
of the conventional PDC so-formed of comparative example 2 was
evaluated by measuring the distance cut prior to failure in the
same Barre granite workpiece used to test comparative example 1 and
using the same test parameters, without using coolant, in a
vertical turret lathe test. The conventional PDC of comparative
example 2 was able to cut a distance of about 3453 linear feet in
the workpiece prior to failure.
COMPARATIVE EXAMPLE 3
[0061] A PDC was obtained that was fabricated as performed in
comparative example 1. The thickness of the PCD table of the PDC
was about 0.097 inch and an about 0.0122-inch chamfer was machined
in the PCD table. The PCD table was acid leached to a depth of
greater than about 200 .mu.m. The thermal stability of the PCD
table of the conventional PDC so-formed of comparative example 3
was evaluated by measuring the distance cut prior to failure in the
same Barre granite workpiece used to test comparative example 1 and
using the same test parameters, without using coolant, in a
vertical turret lathe test. The conventional PDC of comparative
example 3 was able to cut a distance of about 8508 linear feet in
the workpiece prior to failure.
EXAMPLE 4
[0062] A leached PDC was obtained that was fabricated as performed
in comparative example 3. The thickness of the PCD table of the
leached PDC was 0.090 inch and a 0.0122-inch chamfer was machined
in the PCD table. A layer of infiltrant material made from an
Aremco-Seal.TM. 613 coating was disposed in the bottom of a
container assembly. The leached PDC was placed in the container
assembly, with the leached PCD table placed adjacent to the layer
of Aremco-Seal.TM. 613 coating. The container assembly including
the layer of Aremco-Seal.TM. 613 coating and the leached PDC
therein was subjected to HPHT conditions in an HPHT press at a
temperature of about 1200.degree. C. and a pressure of about 5 GPa
to about 8 GPa to infiltrate the leached portion of the PCD table
with the infiltrant material from the layer. The thermal stability
of the infiltrated PCD table of the PDC so-formed of example 4 was
evaluated by measuring the distance cut prior to failure in the
same Barre granite workpiece used to test comparative example 1 and
using the same test parameters, without using coolant, in a
vertical turret lathe test. The infiltrated PCD table of the PDC of
example 4 was able to cut a distance of greater than 10,422 linear
feet in the workpiece prior to failure, which was greater than the
distance that the leached PDC of comparative example 3 was able to
cut.
EXAMPLE 5
[0063] A leached PDC was obtained that was fabricated as performed
in comparative example 3. The thickness of the PCD table of the
leached PDC was about 0.089 inch and an about 0.0118-inch chamfer
was machined in the PCD table. A layer of infiltrant material made
from an Aremco-Seal.TM. 613 coating was disposed in the bottom of a
container assembly. The leached PDC was placed in the container
assembly, with the leached PCD table placed adjacent to the layer
of Aremco-Seal.TM. 613 coating. The container assembly including
the layer of Aremco-Seal.TM. 613 coating and the leached PDC
therein was subjected to HPHT conditions in an HPHT press at a
temperature of about 1300.degree. C. and a pressure of about 5 GPa
to about 8 GPa to infiltrate the leached portion of the PCD table
with the infiltrant material from the layer. The thermal stability
of the infiltrated PCD table of the PDC so-formed of example 5 was
evaluated by measuring the distance cut prior to failure in the
same Barre granite workpiece used to test comparative example 1 and
using the same test parameters, without using coolant, in a
vertical turret lathe test. The infiltrated PCD table of the PDC of
example 5 was able to cut a distance of about 4864 linear feet in
the workpiece prior to failure, which was greater than the
distances that the leached PCD tables of comparative examples 1 and
2 were able to cut.
EXAMPLE 6
[0064] A leached PDC was obtained that was fabricated as performed
in comparative example 3. The thickness of the PCD table of the
leached PDC was about 0.091 inch and an about 0.0118-inch chamfer
was machined in the PCD table. A layer of infiltrant material made
from an Aremco-Seal.TM. 617 coating was disposed in the bottom of a
container assembly. The leached PDC was placed in the container
assembly, with the leached PCD table placed adjacent to the layer
of Aremco-Seal.TM. 617 coating. The container assembly including
the layer of Aremco-Seal.TM. 617 coating and the leached PDC
therein was subjected to HPHT conditions in an HPHT press at a
temperature of about 1300.degree. C. and a pressure of about 5 GPa
to about 8 GPa to infiltrate the leached portion of the PCD table
with the infiltrant material from the layer. The thermal stability
of the infiltrated PCD table of the PDC so-formed of example 6 was
evaluated by measuring the distance cut prior to failure in the
same Barre granite workpiece used to test comparative example 1 and
using the same test parameters, without using coolant, in a
vertical turret lathe test. The infiltrated PCD table of the PDC of
example 6 was able to cut a distance of about 4030 linear feet in
the workpiece prior to failure, which was greater than the
distances that the leached PCD tables of comparative examples 1 and
2 were able to cut.
EXAMPLE 7
[0065] A leached PDC was obtained that was fabricated as performed
in comparative example 3. The thickness of the PCD table of the
leached PDC was about 0.091 inch and an about 0.0119-inch chamfer
was machined in the PCD table. A layer of infiltrant material made
from an Aremco-Seal.TM. 617 coating was disposed in the bottom of a
container assembly. The leached PDC was placed in the container
assembly, with the leached PCD table placed adjacent to the layer
of Aremco-Seal.TM. 617 coating. The container assembly including
the layer of Aremco-Seal.TM. 617 coating and the leached PDC
therein was subjected to HPHT conditions in an HPHT press at a
temperature of about 1200.degree. C. and a pressure of about 5 GPa
to about 8 GPa to infiltrate the leached portion of the PCD table
with the infiltrant material from the layer. The thermal stability
of the infiltrated PCD table of the PDC so-formed of example 6 was
evaluated by measuring the distance cut prior to failure in the
same Barre granite workpiece used to test comparative example 1 and
using the same test parameters, without using coolant, in a
vertical turret lathe test. The infiltrated PCD table of the PDC of
example 7 was able to cut a distance of about 7236 linear feet in
the workpiece prior to failure, which was greater than the
distances that the leached PCD tables of comparative examples 1 and
2 were able to cut.
[0066] The disclosed PCD element and PDC embodiments may be used in
a number of different applications including, but not limited to,
use in a rotary drill bit (FIGS. 6A and 6B), a thrust-bearing
apparatus (FIG. 7), a subterranean drilling system (FIG. 8), and a
wire-drawing die (FIG. 9). The various applications discussed above
are merely some examples of applications in which the PCD element
and PDC embodiments may be used. Other applications are
contemplated, such as employing the disclosed PCD element and PDC
embodiments in friction stir welding tools.
[0067] FIG. 6A is an isometric view and FIG. 6B is a top elevation
view of an embodiment of a rotary drill bit 600. The rotary drill
bit 600 includes at least one PDC configured according to any of
the previously described PDC embodiments. The rotary drill bit 600
comprises a bit body 602 that includes radially and longitudinally
extending blades 604 having leading faces 606, and a threaded pin
connection 608 for connecting the bit body 602 to a drilling
string. The bit body 602 defines a leading end structure for
drilling into a subterranean formation by rotation about a
longitudinal axis 610 and application of weight-on-bit. At least
one PDC cutting element, configured according to any of the
previously described PDC embodiments (e.g., the PDC 300 shown in
FIG. 3), may be affixed to the bit body 602. With reference to FIG.
6B, a plurality of PDCs 612 are secured to the blades 604. For
example, each PDC 612 may include a PCD table 614 bonded to a
substrate 616. More generally, the PDCs 612 may comprise any PDC
disclosed herein, without limitation. In addition, if desired, in
some embodiments, a number of the PDCs 612 may be conventional in
construction. Also, circumferentially adjacent blades 604 define
so-called junk slots 618 therebetween, as known in the art.
Additionally, the rotary drill bit 600 may include a plurality of
nozzle cavities 620 for communicating drilling fluid from the
interior of the rotary drill bit 600 to the PDCs 612.
[0068] In the illustrated embodiment shown in FIGS. 6A and 6B, each
PDC 612 is shown as a compact having a polycrystalline diamond
table bonded to a substrate. However, in other embodiments, one or
more of the PDCs 612 may be replaced by a PCD element (e.g., the
PCD element 100 shown in FIG. 1) that is brazed to the bit body
602. In such an embodiment, the braze alloy infiltrates into and
fills the interstitial regions of the second volume 110 of the PCD
body 102 so that a strong metallurgical bond is formed between the
bit body 602 and the PCD element.
[0069] FIGS. 6A and 6B merely depict an embodiment of a rotary
drill bit that employs at least one cutting element comprising a
PDC or PCD element fabricated and structured in accordance with the
disclosed embodiments, without limitation. The rotary drill bit 600
is used to represent any number of earth-boring tools or drilling
tools, including, for example, core bits, roller-cone bits,
fixed-cutter bits, eccentric bits, bicenter bits, reamers, reamer
wings, or any other downhole tool including PDCs or PCD elements,
without limitation.
[0070] The PCD elements and PDCs disclosed herein (e.g., the PDC
300 shown in FIG. 3) may also be utilized in applications other
than rotary drill bits. For example, the disclosed PCD element and
PDC embodiments may be used in thrust-bearing assemblies, radial
bearing assemblies, wire-drawing dies, artificial joints, machining
elements, and heat sinks
[0071] FIG. 7 is an isometric cut-away view of an embodiment of a
thrust-bearing apparatus 700, which may utilize any of the
disclosed PDC embodiments as bearing elements. The thrust-bearing
apparatus 700 includes respective thrust-bearing assemblies 702.
Each thrust-bearing assembly 702 includes an annular support ring
704 that may be fabricated from a material, such as carbon steel,
stainless steel, or another suitable material. Each support ring
704 includes a plurality of recesses (not labeled) that receives a
corresponding bearing element 706. Each bearing element 706 may be
mounted to a corresponding support ring 704 within a corresponding
recess by brazing, press-fitting, using fasteners, or another
suitable mounting technique. One or more, or all of bearing
elements 706 may be configured according to any of the disclosed
PDC embodiments. For example, each bearing element 706 may include
a substrate 708 and a PCD table 710, with the PCD table 710
including a bearing surface 712.
[0072] In use, the bearing surfaces 712 of one of the
thrust-bearing assemblies 702 bears against the opposing bearing
surfaces 712 of the other one of the bearing assemblies 702. For
example, one of the thrust-bearing assemblies 702 may be operably
coupled to a shaft to rotate therewith and may be termed a "rotor."
The other one of the thrust-bearing assemblies 702 may be held
stationary and may be termed a "stator."
[0073] Referring to FIG. 8, the thrust-bearing apparatus 700 may be
incorporated in a subterranean drilling system. FIG. 8 is a
schematic isometric cut-away view of a subterranean drilling system
800 that includes at least one of the thrust-bearing apparatuses
700 shown in FIG. 7 according to another embodiment. The
subterranean drilling system 800 includes a housing 802 enclosing a
downhole drilling motor 804 (i.e., a motor, turbine, or any other
device capable of rotating an output shaft) that is operably
connected to an output shaft 806. A first thrust-bearing apparatus
700.sub.1 (FIG. 7) is operably coupled to the downhole drilling
motor 804. A second thrust-bearing apparatus 700.sub.2 (FIG. 7) is
operably coupled to the output shaft 806. A rotary drill bit 808
configured to engage a subterranean formation and drill a borehole
is connected to the output shaft 806. The rotary drill bit 808 is
shown as a roller-cone bit including a plurality of roller cones
810. However, other embodiments may utilize different types of
rotary drill bits, such as a so-called "fixed-cutter" drill bit
shown in FIGS. 6A and 6B. As the borehole is drilled, pipe sections
may be connected to the subterranean drilling system 800 to form a
drill string capable of progressively drilling the borehole to a
greater depth within the earth.
[0074] A first one of the thrust-bearing assemblies 702 of the
thrust-bearing apparatus 700.sub.1 is configured as a stator that
does not rotate and a second one of the thrust-bearing assemblies
702 of the thrust-bearing apparatus 700.sub.1 is configured as a
rotor that is attached to the output shaft 806 and rotates with the
output shaft 806. The on-bottom thrust generated when the drill bit
808 engages the bottom of the borehole may be carried, at least in
part, by the first thrust-bearing apparatus 700.sub.1. A first one
of the thrust-bearing assemblies 702 of the thrust-bearing
apparatus 700.sub.2 is configured as a stator that does not rotate
and a second one of the thrust-bearing assemblies 702 of the
thrust-bearing apparatus 700.sub.2 is configured as a rotor that is
attached to the output shaft 806 and rotates with the output shaft
806. Fluid flow through the power section of the downhole drilling
motor 804 may cause what is commonly referred to as "off-bottom
thrust," which may be carried, at least in part, by the second
thrust-bearing apparatus 700.sub.2.
[0075] In operation, drilling fluid may be circulated through the
downhole drilling motor 804 to generate torque and effect rotation
of the output shaft 806 and the rotary drill bit 808 attached
thereto so that a borehole may be drilled. A portion of the
drilling fluid may also be used to lubricate opposing bearing
surfaces of the bearing elements 706 of the thrust-bearing
assemblies 702.
[0076] FIG. 9 is a side cross-sectional view of an embodiment of a
wire-drawing die 900 that employs a PDC 902 fabricated in
accordance with the teachings described herein. The PDC 902
includes an inner, annular PCD region 904 comprising any of the PCD
tables described herein that is bonded to an outer cylindrical
substrate 906 that may be made from the same materials as the
substrate 308 shown in FIG. 3. The PCD region 904 also includes a
die cavity 908 formed therethrough configured for receiving and
shaping a wire being drawn. The wire-drawing die 900 may be encased
in a housing (e.g., a stainless steel housing), which is not shown,
to allow for handling. In use, a wire 910 of a diameter d.sub.1 is
drawn through die cavity 908 along a wire drawing axis 912 to
reduce the diameter of the wire 910 to a reduced diameter
d.sub.2.
[0077] While various aspects and embodiments have been disclosed
herein, other aspects and embodiments are contemplated. The various
aspects and embodiments disclosed herein are for purposes of
illustration and are not intended to be limiting. Additionally, the
words "including," "having," and variants thereof (e.g., "includes"
and "has") as used herein, including the claims, shall have the
same meaning as the word "comprising" and variants thereof (e.g.,
"comprise" and "comprises").
* * * * *