U.S. patent application number 14/330851 was filed with the patent office on 2014-10-30 for methods of making polycrystalline diamond compacts.
The applicant listed for this patent is US SYNTHETIC CORPORATION. Invention is credited to Mohammad N. Sani.
Application Number | 20140318027 14/330851 |
Document ID | / |
Family ID | 44814829 |
Filed Date | 2014-10-30 |
United States Patent
Application |
20140318027 |
Kind Code |
A1 |
Sani; Mohammad N. |
October 30, 2014 |
METHODS OF MAKING POLYCRYSTALLINE DIAMOND COMPACTS
Abstract
A polycrystalline diamond compact includes a substrate and a
polycrystalline diamond table attached to the substrate. The
polycrystalline diamond table includes an upper surface and at
least one peripheral surface. Diamond grains of the polycrystalline
diamond table define a plurality of interstitial regions. The
polycrystalline diamond table includes a region having silicon
carbide positioned within at least some of the interstitial regions
thereof. In an embodiment, the first region extends over only a
selected portion of the upper surface and/or at least a portion of
the at least one peripheral surface. In another embodiment, the
first region substantially contours the upper surface and a
chamfer.
Inventors: |
Sani; Mohammad N.; (Orem,
UT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
US SYNTHETIC CORPORATION |
Orem |
UT |
US |
|
|
Family ID: |
44814829 |
Appl. No.: |
14/330851 |
Filed: |
July 14, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13032350 |
Feb 22, 2011 |
8821604 |
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14330851 |
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11983619 |
Nov 9, 2007 |
8034136 |
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13032350 |
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60860098 |
Nov 20, 2006 |
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60876701 |
Dec 21, 2006 |
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Current U.S.
Class: |
51/309 ;
51/307 |
Current CPC
Class: |
B24D 18/00 20130101;
B22F 7/08 20130101; B24D 3/10 20130101; C04B 2237/401 20130101;
F16C 33/043 20130101; C22C 2026/006 20130101; C04B 2237/16
20130101; C22C 26/00 20130101; C04B 37/003 20130101; E21B 10/567
20130101; F16C 33/26 20130101; C22C 2204/00 20130101; F16C 2220/62
20130101; C22C 1/1068 20130101; C04B 2237/363 20130101; B22F 7/06
20130101; C04B 2237/61 20130101 |
Class at
Publication: |
51/309 ;
51/307 |
International
Class: |
B22F 7/08 20060101
B22F007/08; B24D 3/10 20060101 B24D003/10 |
Claims
1. A method of fabricating a polycrystalline diamond compact,
comprising: positioning an at least partially porous
polycrystalline diamond body between a silicon-containing material
and a substrate, wherein the at least partially porous
polycrystalline diamond body exhibits an upper surface, at least
one peripheral surface, and a chamfer extending between the upper
surface and the at least one peripheral surface; subjecting the at
least partially porous polycrystalline diamond body, the
silicon-containing material, and the substrate to a high-pressure,
high-temperature process to infiltrate a first region that extends
inwardly from the upper surface and the chamfer with silicon from
the silicon-containing material.
2. The method of claim 1 wherein the substrate includes a metallic
infiltrant, and wherein subjecting the at least partially porous
polycrystalline diamond body, the silicon-containing material, and
the substrate to a high-pressure, high-temperature process to
infiltrate a first region that extends inwardly from the upper
surface and the chamfer with silicon from the silicon-containing
material includes infiltrating a bonding region of the at least
partially porous polycrystalline diamond body adjacent to the
substrate with the metallic infiltrant.
3. The method of claim 1 wherein the first region extends inwardly
to about the same depth from the upper surface as from the
chamfer.
4. The method of claim 1 wherein the first region of the at least
partially porous polycrystalline diamond body extends along only a
selected portion of the upper surface.
5. The method of claim 1 wherein the silicon-containing material
only covers a selected portion of the upper surface of the at least
partially porous polycrystalline diamond body.
6. The method of claim 1, further comprising masking a selected
portion of the upper surface of the at least partially porous
polycrystalline diamond body from the silicon-containing
material.
7. The method of claim 1 wherein the at least partially porous
polycrystalline diamond body exhibits an average grain diamond size
of 20 .mu.m or less.
8. The method of claim 1 wherein the at least partially porous
polycrystalline diamond body includes tungsten carbide.
9. The method of claim 1 wherein the at least partially porous
polycrystalline diamond body exhibits an average grain diamond size
of 20 .mu.m or less and includes tungsten carbide.
10. A method of fabricating a polycrystalline diamond compact,
comprising: positioning an at least partially porous
polycrystalline diamond body between a first infiltrant material
and a substrate including a metallic second infiltrant that is
different than the first infiltrant material, wherein the at least
partially porous polycrystalline diamond body exhibits an upper
surface, at least one peripheral surface, and a chamfer extending
between the upper surface and the at least one peripheral surface;
subjecting the at least partially porous polycrystalline diamond
body, the first infiltrant material, and the substrate to a
high-pressure, high-temperature process to infiltrate a first
region that extends inwardly from the upper surface and the chamfer
with material from the first infiltrant material.
11. The method of claim 10 wherein subjecting the at least
partially porous polycrystalline diamond body, the first infiltrant
material, and the substrate to a high-pressure, high-temperature
process to infiltrate a first region that extends inwardly from the
upper surface and the chamfer with the material from the first
infiltrant material includes infiltrating a bonding region of the
at least partially porous polycrystalline diamond body adjacent to
the substrate with the metallic second infiltrant.
12. The method of claim 10 wherein the first region extends
inwardly to about the same depth from the upper surface as from the
chamfer.
13. The method of claim 10 wherein the first region of the at least
partially porous polycrystalline diamond body extends along only a
selected portion of the upper surface.
14. The method of claim 10 wherein the first infiltrant material
only covers a selected portion of the upper surface of the at least
partially porous polycrystalline diamond body.
15. The method of claim 10 wherein the at least partially porous
polycrystalline diamond body exhibits an average grain diamond size
of 20 .mu.m or less.
16. The method of claim 10 wherein the at least partially porous
polycrystalline diamond body exhibits an average grain diamond size
of 20 .mu.m or less and includes tungsten carbide.
17. The method of claim 10 wherein the first infiltrant material
includes a silicon-containing material.
18. The method of claim 10 wherein the metallic second infiltrant
includes at least one of cobalt, iron, or nickel.
19. A method of fabricating a polycrystalline diamond compact,
comprising: positioning an at least partially porous
polycrystalline diamond body between a first infiltrant material
and a metallic second infiltrant having a composition different
than the first infiltrant material, wherein the at least partially
porous polycrystalline diamond body exhibits an upper surface, at
least one peripheral surface, and a chamfer extending between the
upper surface and the at least one peripheral surface; subjecting
the at least partially porous polycrystalline diamond body, the
first infiltrant material, and the substrate to a high-pressure,
high-temperature process to infiltrate a first region that extends
inwardly from the upper surface and the chamfer with material from
the first infiltrant material.
20. The method of claim 19 wherein the first infiltrant material
includes a silicon-containing material, wherein the metallic second
infiltrant is included in a substrate, and wherein the metallic
second infiltrant includes at least one of cobalt, iron, or
nickel.
21. A method of fabricating a polycrystalline diamond compact,
comprising: positioning an at least partially porous
polycrystalline diamond body between a silicon-containing material
and a substrate that is adjacent to a metal-solvent catalyst,
wherein the at least partially porous polycrystalline diamond body
exhibits an upper surface and at least one peripheral surface,
wherein the silicon-containing material extends over only a portion
of the upper surface and/or at least a portion of the at least one
peripheral surface; subjecting the at least partially porous
polycrystalline diamond body, the silicon-containing material, and
the substrate to a high-pressure, high-temperature process to
infiltrate a first region of the at least partially porous
polycrystalline body that extends along only a portion of the upper
surface thereof.
22. The method of claim 21 wherein the substrate includes a
metallic infiltrant; and wherein subjecting the at least partially
porous polycrystalline diamond body, the silicon-containing
material, and the substrate to a high-pressure, high-temperature
process to infiltrate a first region of the at least partially
porous polycrystalline body that extends along only a portion of
the upper surface thereof includes infiltrating a bonding region of
the at least partially porous polycrystalline diamond body adjacent
to the substrate with the metallic infiltrant.
23. The method of claim 21 wherein the first region is configured
as an annular region.
24. The method of claim 21, further comprising masking a selected
portion of the upper surface of the at least partially porous
polycrystalline body from the silicon-containing material.
25. The method of claim 21 wherein the silicon-containing material
includes a plurality of discrete portions that cover only the
portion of the upper surface of the at least partially porous
polycrystalline diamond body.
26. The method of claim 21 wherein the silicon-containing material
extends about the at least a portion of the at least one peripheral
surface of the at least partially porous polycrystalline diamond
body.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 13/032,350 filed on 22 Feb. 2011, which is a
continuation-in-part of U.S. application Ser. No. 11/983,619 filed
on 9 Nov. 2007, now U.S. Pat. No. 8,034,136, issued 11 Oct. 2011,
which claims the benefit of U.S. Provisional Application No.
60/860,098 filed on 20 Nov. 2006 and U.S. Provisional Application
No. 60/876,701 filed on 21 Dec. 2006, the contents of each of the
foregoing applications are incorporated herein, in their entirety,
by this reference.
BACKGROUND
[0002] Wear-resistant, superabrasive compacts are utilized for a
variety of mechanical applications. For example, polycrystalline
diamond compacts ("PDCs") are used in drilling tools (e.g., cutting
elements, gage trimmers, etc.), machining equipment, bearing
apparatuses, wire-drawing machinery, and in other mechanical
systems.
[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 or cutter typically
includes a superabrasive diamond layer or table. The diamond table
is formed and bonded to a substrate using an ultra-high pressure,
ultra-high temperature ("HPHT") process. The substrate is often
brazed or otherwise joined to an attachment member such as a stud
or a cylindrical backing. 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. The PDC cutting element may
also be brazed directly into a preformed pocket, socket, or other
receptacle formed in the bit body. Generally, a rotary drill bit
may include a number of PDC cutting elements affixed to the drill
bit body.
[0004] Conventional PDCs are normally fabricated by placing a
cemented carbide substrate into a container or cartridge with a
volume of diamond particles positioned on a surface of the cemented
carbide substrate. A number of such cartridges may be typically
loaded into an HPHT press. The substrates 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
diamond table. The catalyst material is often a solvent catalyst,
such as cobalt, nickel, or iron that is used for facilitating the
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 facilitate intergrowth between the diamond particles,
which results in formation of bonded diamond grains. Often, a
solvent catalyst may be mixed with the diamond particles prior to
subjecting the diamond particles and substrate to the HPHT
process.
[0006] The solvent catalyst dissolves carbon from the diamond
particles or portions of the diamond particles that graphitize due
to the high temperature being used in the HPHT process. The
solubility of the stable diamond phase in the solvent catalyst is
lower than that of the metastable graphite under HPHT conditions.
As a result of this solubility difference, the undersaturated
graphite tends to dissolve into solvent catalyst and the
supersaturated diamond tends to deposit onto existing diamond
particles to form diamond-to-diamond bonds. Accordingly, diamond
grains become mutually bonded to form a matrix of polycrystalline
diamond with interstitial regions between the bonded diamond grains
being occupied by the solvent catalyst.
[0007] The presence of the solvent catalyst in the diamond table is
believed to reduce the thermal stability of the diamond 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 in the PDC
during drilling or cutting operations, which consequently can
degrade the mechanical properties of the PDC or cause failure.
Additionally, some of the diamond grains can undergo a chemical
breakdown or back-conversion with the solvent catalyst. At
extremely high temperatures, portions of diamond grains may
transform to carbon monoxide, carbon dioxide, graphite, or
combinations thereof, thus, degrading the mechanical properties of
the PDC.
[0008] Therefore, manufacturers and users of superabrasive
materials continue to seek improved thermally stable, superabrasive
materials and processing techniques.
SUMMARY
[0009] Embodiments of the present invention relate to methods of
fabricating superabrasive articles, such as PDCs, and intermediate
articles formed during fabrication of such PDCs. Many different PDC
embodiments disclosed herein include a thermally-stable
polycrystalline diamond table in which silicon carbide occupies a
portion of the interstitial regions thereof formed between bonded
diamond grains.
[0010] In one embodiment of the present invention, a method of
fabricating a superabrasive article is disclosed. A mass of
unsintered diamond particles may be infiltrated with metal-solvent
catalyst from a metal-solvent-catalyst-containing material to
promote formation of a sintered body of diamond grains including
interstitial regions. At least a portion of the interstitial
regions may also be infiltrated with silicon from a
silicon-containing material. The silicon reacts with the sintered
body to form silicon carbide within a portion of the interstitial
regions.
[0011] In another embodiment of the present invention, another
method of fabricating a superabrasive article is disclosed. At
least a portion of interstitial regions of a
pre-sintered-polycrystalline diamond body may be infiltrated with
silicon from a silicon-containing material. At least a portion of
metal-solvent catalyst located within the at least a portion of
interstitial regions of the pre-sintered-polycrystalline diamond
body may be displaced into a porous mass. The silicon and the
pre-sintered-polycrystalline diamond body are reacted to form
silicon carbide within the at least a portion of the interstitial
regions. A section of the polycrystalline diamond table so-formed
may be removed by a suitable material-removal process so that an
upper region of the polycrystalline diamond table includes
substantially only silicon carbide within the interstitial regions
thereof.
[0012] In another embodiment of the present invention, a
polycrystalline diamond compact includes a substrate and a
polycrystalline diamond table attached to the substrate. The
polycrystalline diamond table including an upper surface, at least
one peripheral surface, and a chamfer extending between the upper
surface and the peripheral surface. Diamond grains of the
polycrystalline diamond table define a plurality of interstitial
regions. The polycrystalline diamond table includes a first region
extending inwardly from the upper surface and the chamfer, with the
first region substantially contouring the upper surface and the
chamfer. The first region includes silicon carbide positioned
within at least some of the interstitial regions thereof. The
polycrystalline diamond table includes a bonding region bonded to
the substrate, with the bonding region including metal-solvent
catalyst positioned within a second portion of the interstitial
regions.
[0013] In a further embodiment of the present invention, a method
of fabricating a polycrystalline diamond compact includes
positioning an at least partially porous polycrystalline body
between a silicon-containing material and a substrate that is
adjacent to a metal-solvent catalyst. The at least partially porous
polycrystalline body exhibits an upper surface, at least one
peripheral surface, and a chamfer extending between the upper
surface and the at least one peripheral surface. The method further
includes subjecting the at least partially porous polycrystalline
body, the silicon-containing material, and the substrate to an HPHT
process to infiltrate a first region that extends inwardly from the
upper surface and the chamfer with silicon from the
silicon-containing material.
[0014] In yet another embodiment of the present invention, a
polycrystalline diamond compact includes a substrate and a
polycrystalline diamond table attached to the substrate. The
polycrystalline diamond table including an upper surface. Diamond
grains of the polycrystalline diamond table define a plurality of
interstitial regions. The polycrystalline diamond table includes a
first region including silicon carbide positioned within a first
portion of the interstitial regions, the first region extending
over only a selected portion of the upper surface. The
polycrystalline diamond table further includes a bonding region
bonded to the substrate, with the bonding region including
metal-solvent catalyst positioned within a second portion of the
interstitial regions.
[0015] In still a further embodiment of the present invention, a
method of fabricating a polycrystalline diamond compact includes
positioning an at least partially porous polycrystalline body
between a silicon-containing material and a substrate adjacent to a
metal-solvent catalyst. The at least partially porous
polycrystalline body includes an upper surface and at least one
peripheral surface, with the silicon-containing material extending
over only a portion of the upper surface and/or at least a portion
of the at least one peripheral surface. The method further includes
subjecting the at least partially porous polycrystalline body, the
silicon-containing material, and the substrate to an HPHT process
to infiltrate a first region of the at least partially porous
polycrystalline body that extends along only a portion of the upper
surface thereof
[0016] Features from any of the disclosed embodiments may be used
in combination with one another, without limitation. In addition,
other features and advantages of the present disclosure will become
apparent to those of ordinary skill in the art through
consideration of the following detailed description and the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The drawings illustrate several embodiments of the present
invention, wherein like reference numerals refer to like or similar
elements in different views or embodiments shown in the
drawings.
[0018] FIG. 1A is a schematic side cross-sectional view of an
assembly including a substrate, a porous polycrystalline diamond
body, and a silicon-containing material used to fabricate a PDC
according to one embodiment of the present invention.
[0019] FIG. 1B is a schematic side cross-sectional view of an
assembly including a substrate, a porous polycrystalline diamond
body in which a region remote from the substrate contains tungsten
carbide, and a silicon-containing material used to fabricate a PDC
according to one embodiment of the present invention.
[0020] FIG. 2A is a schematic side cross-sectional view of the PDC
resulting from HPHT processing of the assembly shown in FIG.
1A.
[0021] FIG. 2B is a schematic perspective view of the PDC shown in
FIG. 2A.
[0022] FIG. 2C is a schematic cross-sectional view of the PDC
so-formed when the polycrystalline diamond body shown in FIG. 1A
includes a preformed chamfer according to another embodiment.
[0023] FIG. 3A is a schematic side cross-sectional view of another
assembly that may be used to form a PDC with a selectively-shaped
cutting region according to another embodiment of the present
invention.
[0024] FIG. 3B is a schematic side cross-sectional view of another
assembly that may be used to form a PDC in which silicon
infiltrates into a polycrystalline diamond body through sides
thereof according to another embodiment of the present
invention.
[0025] FIG. 4A is a schematic side cross-sectional view of the PDC
resulting from HPHT processing of the assembly shown in FIG.
3A.
[0026] FIG. 4B is a schematic top plan view of the PDC resulting
from HPHT processing of the assembly shown in FIG. 3A when the
silicon-containing material included multiple wedge-shaped
portions.
[0027] FIG. 5 is a schematic side cross-sectional view of another
assembly that may be used to form the PDC shown in FIGS. 2A and 2B
according to another embodiment of the present invention.
[0028] FIG. 6 is a schematic side cross-sectional view of another
assembly that may be used to form the PDC shown in FIGS. 2A and 2B
according to yet another embodiment of the present invention.
[0029] FIG. 7 is a schematic side cross-sectional view of an
assembly including a substrate, unsintered diamond particles, a
metal-solvent-catalyst material, and a silicon-containing material
used to fabricate a PDC according to another embodiment of the
present invention.
[0030] FIG. 8 is a schematic side cross-sectional view of the PDC
resulting from HPHT processing of the assembly shown in FIG. 7.
[0031] FIG. 9 is a schematic side cross-sectional view of an
assembly including a substrate, a silicon-containing material, a
diamond table, and porous mass used to fabricate a PDC according to
another embodiment of the present invention.
[0032] FIG. 10 is a schematic side cross-sectional view of the
resulting structure formed from HPHT processing of the assembly
shown in FIG. 9.
[0033] FIG. 11 is a PDC formed by removing a portion of the
multi-region structure shown in FIG. 10.
[0034] FIG. 12 is a schematic cross-sectional view of an assembly
including a substrate, a mass of unsintered diamond particles, and
layers of metal-solvent-catalyst-containing material and
silicon-containing material disposed between the substrate and the
mass of unsintered diamond particles used to fabricate a PDC
according to another embodiment of the present invention.
[0035] FIG. 13 is a schematic side cross-sectional view of the
resulting structure from HPHT processing of the assembly shown in
FIG. 12.
[0036] FIG. 14 is an isometric view of one embodiment of a rotary
drill bit including at least one superabrasive cutting element
including a PDC configured according to any of the various PDC
embodiments of the present invention.
[0037] FIG. 15 is a top elevation view of the rotary drill bit of
FIG. 14.
[0038] FIG. 16 is a graph showing the measured temperature versus
linear distance during a vertical turret lathe test on a
conventional, leached PDC and a PDC according to working example 2
of the present invention.
[0039] FIG. 17 is a graph showing the measured normal force versus
linear distance during a vertical turret lathe test on a
conventional, leached PDC and a PDC according to working example 2
of the present invention.
[0040] FIG. 18 is a graph illustrating the wear flat volume
characteristics of a conventional, leached PDC and a PDC according
to working example 2 of the present invention.
DETAILED DESCRIPTION
[0041] Embodiments of the present invention relate to methods of
fabricating superabrasive articles, such as PDCs, and intermediate
articles formed during fabrication of such PDCs. For example, many
different PDC embodiments disclosed herein include a
thermally-stable polycrystalline diamond table in which silicon
carbide occupies a portion of the interstitial regions formed
between bonded diamond grains. The superabrasive articles disclosed
herein may be used in a variety of applications, such as drilling
tools (e.g., compacts, cutting elements, gage trimmers, etc.),
machining equipment, bearing apparatuses, wire-drawing machinery,
and other apparatuses. As used herein, the term "superabrasive"
means a material that exhibits a hardness exceeding a hardness of
tungsten carbide. For example, a superabrasive article is an
article of manufacture, at least a portion of which exhibits a
hardness exceeding the hardness of tungsten carbide.
[0042] FIGS. 1A-2B show an embodiment of a method according to the
present invention for fabricating a PDC and the resulting structure
of the PDC. As shown in FIG. 1A, an assembly 10 includes an at
least partially porous polycrystalline diamond body 14 (i.e., a
pre-sintered-polycrystalline diamond body) positioned adjacent to a
substrate 12. The assembly 10 further includes a silicon-containing
material 16 positioned adjacent to the polycrystalline diamond body
14 on a side of the polycrystalline diamond body 14 opposite the
substrate 12. In one embodiment of the present invention, the
silicon-containing material 16 may comprise a green body of
elemental silicon particles (e.g., crystalline or amorphous silicon
particles) in the form of a tape-casted tape that is placed
adjacent to the polycrystalline diamond body 14. In another
embodiment of the present invention, the silicon-containing
material 16 may comprise a disc of silicon.
[0043] Still referring to FIG. 1A, the polycrystalline diamond body
14 includes a plurality of interstitial regions that were
previously occupied by metal-solvent catalyst. The polycrystalline
diamond body 14 may be fabricated by subjecting a plurality of
diamond particles (e.g., diamond particles having an average
particle size between 0.5 .mu.m to about 150 .mu.m) to an HPHT
sintering process in the presence of a metal-solvent catalyst, such
as cobalt, or other catalyst to facilitate intergrowth between the
diamond particles to form a polycrystalline diamond table of bonded
diamond grains. In one embodiment of the present invention, the
sintered diamond grains of the polycrystalline diamond body 14 may
exhibit an average grain size of about 20 .mu.m or less. The
polycrystalline diamond table so-formed may be immersed in an acid,
such as aqua-regia, a solution of 90% nitric acid/10% de-ionized
water, or subjected to another suitable process to remove at least
a portion of the metal-solvent catalyst from the interstitial
regions of the polycrystalline diamond table.
[0044] In one embodiment of the present invention, the
polycrystalline diamond table is not formed by sintering the
diamond particles on a cemented-tungsten-carbide substrate or
otherwise in the presence of tungsten carbide. In such an
embodiment, the interstitial regions of the polycrystalline diamond
body 14 may contain no tungsten and/or tungsten carbide or
insignificant amounts of tungsten and/or tungsten carbide, which
can inhibit removal of the metal-solvent catalyst.
[0045] In other embodiments of the present invention, a
polycrystalline diamond table may be formed by HPHT sintering
diamond particles in the presence of tungsten carbide. For example,
diamond particles may be placed adjacent to a cemented tungsten
carbide substrate and/or tungsten carbide particles may be mixed
with the diamond particles prior to HPHT sintering. In such an
embodiment, the polycrystalline diamond table so-formed may include
tungsten and/or tungsten carbide that is swept in with
metal-solvent catalyst from the substrate or intentionally mixed
with the diamond particles during HPHT sintering process. For
example, some tungsten and/or tungsten carbide from the substrate
may be dissolved or otherwise transferred by the liquefied
metal-solvent catalyst (e.g., cobalt from a cobalt-cemented
tungsten carbide substrate) of the substrate that sweeps into the
diamond particles. The polycrystalline diamond table so-formed may
be separated from the substrate using a lapping process, a grinding
process, wire-electrical-discharge machining ("wire EDM"), or
another suitable material-removal process. The separated
polycrystalline diamond table may be immersed in a suitable acid
(e.g., a hydrochloric acid/hydrogen peroxide solution) to remove
substantially all of the metal-solvent catalyst from the
interstitial regions and form the polycrystalline diamond body 14.
However, an indeterminate amount of tungsten and/or tungsten
carbide may remain distributed throughout the polycrystalline
diamond body 14 even after leaching. The presence of the tungsten
and/or tungsten carbide within the polycrystalline diamond body 14
is currently believed to significantly improve the abrasion
resistance thereof even after infiltration with silicon and HPHT
bonding to the substrate 12, as will discussed in more detail
below.
[0046] In a variation of the above-described embodiment in which
the polycrystalline diamond body 14 has tungsten and/or tungsten
carbide distributed therein, the polycrystalline diamond body 14
may comprise a first portion including tungsten and/or tungsten
carbide and a second portion that is substantially free of tungsten
and/or tungsten carbide. For example, a layer of metal-solvent
catalyst (e.g., cobalt) may be positioned between diamond particles
and a cemented carbide substrate (e.g., cobalt-cemented tungsten
carbide substrate) and subjected to HPHT conditions. During the
HPHT sintering process, metal-solvent catalyst from the layer
sweeps through the diamond particles to effect intergrowth and
bonding. Because the volume of the layer of metal-solvent catalyst
is selected so that it is not sufficient to fill the volume of all
of the interstitial regions between the diamond particles,
metal-solvent catalyst from the substrate also sweeps in, which may
carry or transfer tungsten and/or tungsten carbide. Thus, a first
region of the polycrystalline diamond table so-formed adjacent to
the substrate includes tungsten and/or tungsten carbide and a
second region remote from the substrate is substantially free of
tungsten and/or tungsten carbide. The volume of the layer of
metal-solvent catalyst may be selected so that the second region
exhibits a thickness substantially greater than the second region.
In this embodiment, the metal-solvent catalyst within the
interstitial regions between bonded diamond grains of the
polycrystalline diamond table may be removed from the second region
more easily. For example, the metal-solvent catalyst may be leached
from the first region using a hydrochloric acid/hydrogen peroxide
solution and the metal-solvent catalyst in the second region may be
leached using a less aggressive nitric acid/hydrofluoric acid
solution. As shown in FIG. 1B, the polycrystalline diamond body 14
so-formed after leaching may be oriented with the second region
(shown as 14A) that is substantially free of tungsten and/or
tungsten carbide positioned adjacent to the substrate 12 in the
assembly 10 and the first region (shown as 14B) that includes
tungsten and/or tungsten carbide positioned remote from the
substrate 12 to form at least part of a working or cutting region
of a PDC that is ultimately formed after processing.
[0047] Referring again to FIG. 1A, in another embodiment of the
present invention, the polycrystalline diamond body 14 may be
formed by sintering diamond particles or other particles capable of
forming diamond in response to an HPHT sintering process without a
catalyst. For example, U.S. Pat. Nos. 7,516,804 and 7,841,428, each
of which is incorporated herein, in its entirety, by this
reference, disclose that ultra-dispersed diamond particles and
fullerenes may be mixed with diamond particles and HPHT sintered to
form a polycrystalline diamond body.
[0048] The substrate 12 may comprise a cemented-carbide material,
such as a cobalt-cemented tungsten carbide material or another
suitable material. For example, nickel, iron, and alloys thereof
are other metal-solvent catalysts that may comprise the substrate
12. Other materials that may comprise the substrate 12 include,
without limitation, cemented carbides including titanium carbide,
niobium carbide, tantalum carbide, vanadium carbide, and
combinations of any of the preceding carbides cemented with iron,
nickel, cobalt, or alloys thereof. A representative thickness for
the substrate 12 is a thickness of about 0.100 inches to at least
about 0.350 inches, more particularly about 0.150 inches to at
least about 0.300 inches, and even more particularly about 0.170
inches to at least about 0.290 inches.
[0049] The assembly 10 may be placed in a pressure transmitting
medium, such as a refractory metal can, graphite structure,
pyrophyllite or other pressure transmitting structure, or another
suitable container or supporting element. Methods and apparatuses
for sealing enclosures suitable for holding the assembly 10 are
disclosed in U.S. patent application Ser. No. 11/545,929, which is
incorporated herein, in its entirety, by this reference. The
pressure transmitting medium, including the assembly 10, is
subjected to an HPHT process using an ultra-high pressure press at
a temperature of at least about 1000.degree. Celsius (e.g., about
1300.degree. Celsius to about 1600.degree. Celsius) and a pressure
of at least 40 kilobar (e.g., about 50 kilobar to about 70 kilobar)
for a time sufficient to sinter the assembly 10 and form a PDC 18
as shown in FIGS. 2A and 2B. Stated another way, the HPHT bonds the
polycrystalline diamond body 14 to the substrate 12 and causes at
least partial infiltration of the silicon into the polycrystalline
diamond body 14. The HPHT temperature may be sufficient to melt at
least one constituent of the substrate 12 (e.g., cobalt, nickel,
iron, or another constituent) and the silicon of the
silicon-containing material 16. The PDC 18 may exhibit other
geometries than the geometry illustrated in FIGS. 2A and 2B. For
example, the PDC 18 may exhibit a non-cylindrical geometry.
[0050] As shown in FIGS. 2A and 2B, the HPHT sintered PDC 18
comprises a polycrystalline diamond table 15 that may include three
regions: a first region 20, a second-intermediate region 22, and a
third region 24 (i.e., a bonding region). The first region 20
includes polycrystalline diamond with substantially only silicon
carbide formed within at least some of the interstitial regions
between the bonded diamond grains of the first region 20. It is
noted that the interstitial regions of at least the first region 20
may also include tungsten carbide when tungsten carbide is present
in the polycrystalline diamond body 14, such as in the embodiment
shown in FIG. 1B. During the HPHT process, silicon from the
silicon-containing material 16 liquefies and at least partially
infiltrates the interstitial regions of the polycrystalline diamond
body 14. The silicon reacts with the diamond grains of the
polycrystalline diamond body 14 to form silicon carbide, which
occupies at least some of the interstitial regions between the
diamond grains and bonds to the diamond grains. Further, the amount
of the silicon-containing material 16 may be selected so that the
silicon of the silicon-containing material 16 fills a selected
portion of the interstitial regions of the polycrystalline diamond
body 14.
[0051] During the HPHT process, metal-solvent catalyst from the
substrate 12 or another source also sweeps into the interstitial
regions of the polycrystalline diamond body 14 and fills some of
the interstitial regions thereof, in addition to silicon carbide
filling other interstitial regions as previously described with
respect to the first region 20. In one embodiment of the present
invention, the second-intermediate region 22 of the polycrystalline
diamond table 15 may include polycrystalline diamond with silicon
carbide formed within a portion of the interstitial regions between
the bonded diamond grains of the second-intermediate region 22 and
metal-solvent catalyst (e.g., cobalt) occupying another portion of
the interstitial regions between the bonded diamond grains of the
second-intermediate region 22. In another embodiment of the present
invention, substantially all of or only a portion of the
interstitial regions of the second-intermediate region 22 may
include an alloy of silicon and the metal-solvent catalyst, such as
a silicon-cobalt solid solution alloy or an intermetallic compound
of cobalt and silicon. In yet another embodiment of the present
invention, at least some of the interstitial regions of the
second-intermediate region 22 of the polycrystalline diamond table
15 may include one or more of the following materials: silicon
carbide, metal-solvent catalyst, silicon, and an alloy of silicon
and metal-solvent catalyst. The third region 24 includes
polycrystalline diamond with substantially only metal-solvent
catalyst (e.g., cobalt) occupying at least some of the interstitial
regions between the bonded diamond grains. The metal-solvent
catalyst occupying the interstitial regions of the third region 24
is liquefied and swept into the polycrystalline diamond body 14
from the substrate 12 or another source (e.g., a metal disk,
particles, etc.) during the HPHT process. The third region 24
provides a strong, metallurgical bond between the substrate 12 and
the polycrystalline diamond table 15 to thereby function as a
bonding region. It is noted that at least the first region 20 of
the polycrystalline diamond table 15 may be substantially free of
non-silicon carbide type carbides, such as tungsten carbide, when
the polycrystalline diamond body 14 is not formed in the presence
of tungsten carbide.
[0052] The PDC 18 shown in FIGS. 2A and 2B exhibits an improved
thermal stability relative to a conventional PDC in which the
interstitial regions of the diamond table are occupied with only
cobalt or another metal-solvent catalyst. Additionally, the wear
resistance of the PDC 18 may be improved relative to a conventional
PDC because the silicon carbide phase occupying the interstitial
regions of the first region 20 exhibits a hardness greater than a
hardness of cobalt or other metal-solvent catalysts.
[0053] The PDC 18 may also include a chamfer along a peripheral
region thereof, which may be preformed in the polycrystalline
diamond body 14 (e.g., by machining or grinding) or may be machined
in the polycrystalline diamond table 15 after formation of the PDC
18. For example, FIG. 2C is a cross-sectional view of the PDC 18
so-formed when the polycrystalline diamond body 14 exhibits a
preformed chamfer according to another embodiment. In such an
embodiment, at least the first region 20 and, in some cases, the
second-intermediate region 22 substantially contours a preformed
chamfer 25 and an upper surface 27 of the polycrystalline diamond
table 15, with the chamfer 25 extending between the upper surface
27 and at least one peripheral surface 29. As the polycrystalline
diamond table 15 had a preformed chamfer, the silicon infiltrates
into the polycrystalline diamond table 15 so that a depth "d" of
the first region 20 is substantially the same when measured from
the upper surface 27 and the chamfer 25. The depth "d" may be about
50 .mu.m to about 1000 .mu.m, about 150 .mu.m to about 500 .mu.m,
or about 100 .mu.m to about 200 .mu.m.
[0054] Although the assembly 10 shown in FIGS. 1A and 1B includes
the substrate 12, in another embodiment of the present invention,
the substrate 12 may be omitted. In such an embodiment of the
present invention, an assembly of the polycrystalline diamond body
14 and the silicon-containing material 16 may be subjected to an
HPHT process to form a polycrystalline diamond table. After the
HPHT process, a carbide layer (e.g., a tungsten carbide layer) may
be deposited on the polycrystalline diamond table, as disclosed in
U.S. Patent Application Publication No. 20080085407, to form a PDC
and enable attaching the PDC to a bit body of a rotary drill bit.
U.S. Patent Application Publication No. 20080085407 is incorporated
herein, in its entirety, by this reference. In another embodiment
of the present invention, the polycrystalline diamond table may be
brazed or otherwise secured to a bit body of a rotary drill
bit.
[0055] One of ordinary skill in the art will recognize that many
variations for selectively forming silicon carbide regions within a
pre-sintered-polycrystalline-diamond body may be employed. For
example, in another embodiment of the present invention, a PDC may
be formed with a polycrystalline diamond table including a cutting
region exhibiting a selected configuration. The cutting region may
comprise bonded diamond grains with silicon carbide within at least
some of the interstitial regions between the bonded diamond grains.
By only infiltrating a selected region of an at least partially
porous polycrystalline diamond body with silicon, the toughness may
be improved. As shown in FIG. 3A, a silicon-containing material 16'
in the form of body of silicon or amorphous silicon, green body of
silicon particles in the form of a tape-casted tape in the form of
a tape-casted tape may be placed adjacent to the polycrystalline
diamond body 14. For example, the silicon-containing material 16'
may exhibit an annular geometry, a wedge-shaped geometry, or
another suitable geometry. A mask 21 (e.g., a mica disk or other
ceramic mask) may be disposed adjacent to the silicon-containing
material 16' to cover regions of the polycrystalline diamond body
14 that are not covered by silicon-containing material 16' help
prevent silicon infiltration into the masked region of the
polycrystalline diamond body 14.
[0056] As shown in FIG. 4A, upon subjecting assembly 10' to HPHT
conditions as described generally hereinabove with respect to the
assembly 10, a PDC 18' is formed with a polycrystalline diamond
table 15' including cutting region 20' formed peripherally about
intermediate region 22' and a third region 24'. The cutting region
20' comprises bonded diamond grains with substantially only silicon
carbide within the interstitial regions between the bonded diamond
grains. In one embodiment of the present invention, the
intermediate region 22' comprises bonded diamond grains with
silicon carbide within a portion of the interstitial regions and
metal-solvent catalyst from the substrate 12 or another source
within another portion of the interstitial regions. In another
embodiment of the present invention, substantially all of or only a
portion of the interstitial regions of the second-intermediate
region 22' includes an alloy of silicon and metal-solvent catalyst,
such as a silicon-cobalt solid solution alloy or an intermetallic
compound of cobalt and silicon. In yet another embodiment of the
present invention, at least some of the interstitial regions of the
second-intermediate region 22' of the polycrystalline diamond table
15 may include one or more of the following materials: silicon
carbide, metal-solvent catalyst, silicon, and an alloy of silicon
and metal-solvent catalyst. The third region 24' is formed adjacent
to the substrate 12 and provides a strong, metallurgical bond
between the polycrystalline diamond table 15' and the substrate 12.
The third region 24' comprises bonded diamond grains with
substantially only the metal-solvent catalyst from the substrate 12
or another source within the interstitial regions between the
bonded diamond grains. The third region 24' provides a tough core
that compliments the more thermally-stable first region 20'.
Depending upon the geometry of the silicon-containing material 16',
the geometry of the cutting region 20' of the polycrystalline
diamond table 15' may also be formed to exhibit other selected
geometries.
[0057] FIG. 4B is a top plan view of the PCD table 15' when the
silicon-containing material 16' exhibited a wedge-shaped geometry,
with multiple wedge-shaped portions forming the cutting region 20'.
Of course, other geometries may be employed for the cutting region
20' and the intermediate region 22' that depart from the
illustrated geometry shown in FIG. 4B. For example, the cutting
region 20' and the intermediate region 22' may exhibit an annular
geometry, as described hereinabove, or another selected
geometry.
[0058] Of course, in any of the embodiments described herein that
selectively infiltrate the polycrystalline diamond body 14 with
silicon, the polycrystalline diamond body 14 may also be chamfered.
However, the polycrystalline diamond table 15' may also be
chamfered after being formed.
[0059] In some embodiments, the polycrystalline diamond table 15'
may be subjected to a leaching process to deplete the third region
24' shown in FIGS. 4A and 4B of metal-solvent catalyst (e.g.,
cobalt). Leaching the third region 24' may improve the overall
thermal-stability of the polycrystalline diamond table 15'. The
metal-solvent catalyst may be depleted from the third region 24' to
a selected depth from the upper surface and the peripheral surface.
For example, the leach depth may be about 50 .mu.m to about 1000
.mu.m, about 150 .mu.m to about 500 .mu.m, or about 100 .mu.m to
about 200 .mu.m. The leaching may be performed to remove
substantially all of the metal-solvent catalyst from the third
region 24'.
[0060] FIG. 3B shows another embodiment of the present invention in
which a silicon-containing material 16'' may be positioned adjacent
to at least one peripheral surface 17 of the polycrystalline
diamond body 14. HPHT processing causes silicon from the
silicon-containing material 16'' to at least partially or
substantially infiltrate the polycrystalline diamond body 14. For
example, the silicon from the silicon-containing material 16'' may
partially infiltrate the polycrystalline diamond body 14 to form a
PDC including a multi-region polycrystalline diamond table.
[0061] As shown in FIG. 5, in another embodiment of the present
invention, the PDC 18 may be formed by subjecting an assembly 21 to
HPHT conditions similar to that employed on the assembly 10. The
assembly 21 includes a silicon-containing material 16 positioned
adjacent to a substrate 12, and between the substrate 12 and a
polycrystalline diamond body 14. During HPHT processing, the
assembly 21 is heated at a sufficient rate so that the
metal-solvent catalyst (e.g., cobalt) and the silicon in the
silicon-containing material 16 are in a liquid state at
substantially the same time. Such heating may cause the molten,
metal-solvent catalyst (e.g., from the substrate 12, metal-solvent
catalyst mixed with the silicon-containing material 16, or another
source) to occupy a portion of the interstitial regions of the
polycrystalline diamond body 14 and may cause the molten silicon to
occupy other portions of the interstitial regions of the
polycrystalline diamond body 14. Upon cooling, the resultant,
as-sintered PDC may exhibit a similar multi-region diamond table as
the polycrystalline diamond table 15 shown in FIGS. 2A and 2B.
[0062] FIG. 6 shows another embodiment of the present invention in
which a PDC 13 including a leached polycrystalline diamond table 19
and a silicon-containing material 16 are assembled and HPHT
processed using HPHT conditions as described generally hereinabove
with respect to the assembly 10. In this embodiment, the PDC 13 may
be formed from a conventional PDC with a polycrystalline diamond
table that comprises bonded diamond grains with cobalt or another
metal-solvent catalyst occupying the interstitial regions between
the bonded diamond grains. The metal-solvent catalyst may be
substantially removed from the polycrystalline diamond table by
leaching using an acid, such as aqua-regia, a solution of 90%
nitric acid/10% de-ionized water, or another suitable process to
remove at least a portion of the metal-solvent catalyst from the
interstitial regions of the polycrystalline diamond table. After
removal of the metal-solvent catalyst from the PDC 13, a
silicon-containing material 16 may be positioned adjacent to the
leached polycrystalline diamond table 19 on a side thereof opposite
the substrate 12. The leached polycrystalline diamond table 19 and
the silicon-containing material 16 are subjected to an HPHT process
to infiltrate the leached polycrystalline diamond table 19 with
silicon from the silicon-containing material 16 to form a PDC
having a polycrystalline diamond table with the same or similar
construction as the polycrystalline diamond table 15 shown in FIGS.
2A and 2B.
[0063] FIGS. 7 and 8 show another embodiment of a method according
to the present invention for forming a PDC. As shown in FIG. 7, an
assembly 24 includes a mass of unsintered diamond particles 28
positioned adjacent to the substrate 12. The mass of unsintered
diamond particles 28 may be a green body of diamond particles 28 in
the form of a tape-casted tape. In one embodiment of the present
invention, the diamond particles 28 may exhibit an average particle
size of about 20 .mu.m or less. In another embodiment of the
present invention, the diamond particles 28 may exhibit an average
particle size of about 5 .mu.m to about 50 .mu.m. The mass of
unsintered diamond particles 28 may exhibit a thickness, for
example, of about 0.150 inches to about 0.200 inches. The assembly
24 further includes a metal-solvent-catalyst-containing material 26
positioned adjacent to the mass of diamond particles 28, and a
silicon-containing material 16 positioned adjacent to the
metal-solvent-catalyst-containing material 26. The
metal-solvent-catalyst-containing material 26 may include or may be
formed from a material, such as cobalt, nickel, iron, or alloys
thereof. The metal-solvent-catalyst-containing material 26 may also
be a green body of metal-solvent-catalyst particles in the form of
a tape-casted tape, a thin disc of metal-solvent-catalyst material,
or any other suitable metal-solvent-catalyst material or structure,
without limitation.
[0064] The assembly 24 may be subjected to an HPHT sintering
process using HPHT process conditions similar to those previously
discussed to form a PDC 42 shown in FIG. 8. During HPHT sintering,
the metal-solvent catalyst of the metal-solvent-catalyst-containing
material 26 melts and infiltrates the diamond particles 28 to
effect intergrowth between the diamond particles 28. Molten silicon
from the silicon-containing material 16 also infiltrates the
diamond particles 28 and the infiltration by the molten silicon
follows the infiltration of the metal-solvent catalyst. Thus, the
metal-solvent catalyst from the metal-solvent-catalyst-containing
material 26 promotes bonding of the diamond particles 28 to form
polycrystalline diamond and the silicon infiltrates the
polycrystalline diamond so-formed. The silicon reacts with the
diamond grains of the polycrystalline diamond to form silicon
carbide within some of the interstitial regions between the bonded
diamond grains. The amount of the silicon-containing material 16
metal-solvent-catalyst-containing material 26 may be selected so
that the silicon of the silicon-containing material 16 and the
metal-solvent catalyst from the metal-solvent-catalyst-containing
material 26, respectively, only fill a portion of the interstitial
regions of the polycrystalline diamond formed during the HPHT
process.
[0065] As shown in FIG. 8, the PDC 42 formed by HPHT sintering the
assembly 24 includes a multi-region polycrystalline diamond table
35 similar in configuration to the polycrystalline diamond table 15
shown in FIGS. 2A and 2B. The polycrystalline diamond table 35
includes: a first region 36, a second-intermediate region 38, and a
third region 40. The first region 36 includes substantially only
silicon carbide within at least some of the interstitial regions
between the bonded diamond grains. In one embodiment of the present
invention, the second-intermediate region 38 may include silicon
carbide within a portion of the interstitial regions between the
bonded diamond grains, along with metal-solvent catalyst from the
metal-solvent-catalyst-containing material 26 and/or the substrate
12 within other portions of the interstitial regions of the
second-intermediate region 38. In another embodiment of the present
invention, substantially all of or only a portion of the
interstitial regions of the second-intermediate region 38 may
include an alloy of silicon and metal-solvent catalyst, such as a
silicon-cobalt solid solution alloy or an intermetallic compound of
cobalt and silicon. In yet another embodiment of the present
invention, at least some of the interstitial regions of the
second-intermediate region 38 may include one or more of the
following materials: silicon carbide, metal-solvent catalyst,
silicon, and an alloy of silicon and metal-solvent catalyst. The
third region 40, adjacent to the substrate 12, includes
substantially only metal-solvent catalyst from the substrate 12 or
another source within the interstitial regions thereof for forming
a strong, metallurgical bond between the polycrystalline diamond
table 35 and the substrate 12.
[0066] FIGS. 9-11 show yet another embodiment of a method according
to the present invention for forming a PDC. As shown in FIG. 9, an
assembly 44 is formed by positioning a silicon-containing material
16 between a substrate 12 and a pre-sintered-polycrystalline
diamond table 46. The polycrystalline diamond table 46 may exhibit
a thickness of, for example, about 0.090 inches and an average
grain size of about 20 .mu.m or less. The polycrystalline diamond
table 46 comprises bonded diamond grains sintered using a
metal-solvent catalyst, such as cobalt, nickel, iron, or alloys
thereof. Accordingly, the polycrystalline diamond table 46 includes
bonded diamond grains with the metal-solvent catalyst occupying
interstitial regions between the bonded diamond grains. In one
embodiment of the present invention, the polycrystalline diamond
table 46 may not be formed by sintering diamond particles in the
presence of tungsten carbide so that the interstitial regions of
the polycrystalline diamond table 46 contain no tungsten and/or
tungsten carbide or insignificant amounts of tungsten and/or
tungsten carbide. In other embodiments of the present invention, a
portion or substantially the entire polycrystalline diamond table
46 may be formed to include tungsten and/or tungsten carbide
distributed therethrough, as previously described with respect to
the polycrystalline diamond body 14 shown in FIGS. 1A and 1B. For
example, a first region of the polycrystalline diamond table 46
that is substantially free of tungsten and/or tungsten carbide may
be positioned adjacent to the silicon-containing material 16, while
a second region of the polycrystalline diamond table 46 that
includes tungsten and/or tungsten carbide may be positioned remote
from the silicon-containing material 16. The assembly 44 further
includes a porous mass 48 positioned adjacent to the
polycrystalline diamond table 46 on a side of the polycrystalline
diamond table 46 opposite the silicon-containing material 16. The
porous mass 48 may be unsintered diamond particles, unsintered
aluminum oxide particles, unsintered silicon carbide particles, or
another suitable porous mass. The porous mass 48 may also be a
green body of diamond particles in the form of a tape-casted tape,
or any other form, without limitation.
[0067] The assembly 44 may be subjected to an HPHT sintering
process using sintering conditions similar to the sintering
conditions employed on the assembly 10 to bond the various
components of the assembly 44 together and to form a
polycrystalline diamond structure 50 shown in FIG. 10. During
sintering, silicon from the silicon-containing material 16 melts
and displaces all or a portion of the metal-solvent catalyst of the
polycrystalline diamond table 46 into the porous mass 48. Depending
on the sintering temperature, the metal-solvent catalyst of the
polycrystalline diamond table 46 may also be partially or completed
molten at the same time as the silicon from the silicon-containing
material 16. In one embodiment of the present invention, the amount
of silicon-containing material 16 is selected so that substantially
all of the metal-solvent catalyst of the polycrystalline diamond
table 46 is displaced into the porous mass 48. In another
embodiment of the present invention, the amount of the
silicon-containing material 16 may be selected so that the silicon
from the silicon-containing material 16 displaces only a portion of
the metal-solvent catalyst of the polycrystalline diamond table 46.
The silicon reacts with the diamond grains of the polycrystalline
diamond table 46 or another carbon source to form silicon carbide
within interstitial regions between the bonded diamond grains of
the polycrystalline diamond table 46. Additionally, metal-solvent
catalyst from the substrate 12 or another source also melts and
infiltrates into a region of the polycrystalline diamond table 46
adjacent the substrate 12.
[0068] As shown in FIG. 10, the polycrystalline diamond structure
50 formed by HPHT processing of the assembly 44 comprises a
multi-region polycrystalline diamond table 55 that may include: a
first region 52, a second region 54, a third region 56, a fourth
region 58, and a fifth region 60. The first region 52 includes the
particles from the porous mass 48 with at least some of the
interstitial regions thereof occupied by substantially only the
metal-solvent catalyst displaced from the polycrystalline diamond
table 46. The second region 54 includes the particles from the
porous mass 48 with at least some of the interstitial regions
thereof occupied by an alloy of silicon and metal-solvent catalyst,
such as a silicon-cobalt solid solution alloy or an intermetallic
compound of cobalt and silicon. Depending upon the amount of the
silicon-containing material 16 employed, the second region 54 may
also extend into the HPHT processed polycrystalline diamond table
46. The third region 56, fourth region 58, and fifth region 60 may
be formed from the HPHT processed polycrystalline diamond table 46,
which exhibits a reduced thickness due to the HPHT processing. The
third region 56 includes polycrystalline diamond with substantially
only silicon carbide within at least some of the interstitial
regions between the bonded diamond grains. In one embodiment of the
present invention, the fourth region 58 includes polycrystalline
diamond with at least some of the interstitial regions thereof
occupied by an alloy of silicon and metal-solvent catalyst, such as
a silicon-cobalt solid solution alloy or an intermetallic compound
of cobalt and silicon. In another embodiment of the present
invention, the fourth region 58 may include polycrystalline diamond
with silicon carbide formed within a portion of the interstitial
regions between the bonded diamond grains of the fourth region 58
and metal-solvent catalyst (e.g., cobalt) occupying another portion
of the interstitial regions between the bonded diamond grains of
the fourth region 58. In yet another embodiment of the present
invention, at least some of the interstitial regions of the fourth
region 58 may include one or more of the following materials:
silicon carbide, metal-solvent catalyst, silicon, and an alloy of
silicon and metal-solvent catalyst. The fifth region 60, adjacent
to the substrate 12, includes substantially only metal-solvent
catalyst from the substrate 12 within at least some of the
interstitial regions between bonded diamond grains for forming a
strong, metallurgical bond between the multi-region polycrystalline
diamond table 55 and the substrate 12.
[0069] As shown in FIG. 11, after forming the polycrystalline
diamond structure 50, a PDC 63 including a multi-region structure
65 similar in configuration to the polycrystalline diamond table 15
shown in FIGS. 2A and 2B may be formed by removing the first region
52 and the second region 54 of the multi-region structure 65 using
a lapping process, a grinding process, wire EDM, or another
suitable material-removal process.
[0070] FIGS. 12 and 13 show yet another embodiment of a method
according to the present invention for forming a PDC. As shown in
FIG. 12, an assembly 59 includes a mass of unsintered diamond
particles 62 with a silicon-containing material 16 and a
metal-solvent catalyst-containing material 26 positioned between
the mass of unsintered diamond particles 62 and a substrate 12. The
metal-solvent-catalyst-containing material 26 is positioned
adjacent to the mass of unsintered diamond particles 62 and the
silicon-containing material 16 is positioned adjacent to the
substrate 12. The assembly 59 may be subjected to an HPHT sintering
process using sintering conditions similar to the sintering
conditions employed on the assembly 10 to form a polycrystalline
diamond structure 61 shown in FIG. 13. During HPHT sintering, the
silicon-containing material 16 and the metal-solvent
catalyst-containing material 26 are melted, and metal-solvent
catalyst from the metal-solvent-catalyst-containing material 26
infiltrates the mass of unsintered diamond particles 62 to promote
bonding between the diamond particles, thus, forming
polycrystalline diamond that comprises bonded diamond grains with
interstitial regions between the bonded diamond grains. The silicon
from the silicon-containing material 16 follows the infiltration of
the mass 62 by the metal-solvent-catalyst-containing material 26
and infiltrates the polycrystalline diamond so-formed. The silicon
reacts with the diamond grains to form silicon carbide within some
of the interstitial regions.
[0071] As shown in FIG. 13, the polycrystalline diamond structure
61 formed by HPHT sintering of the assembly 59 comprises a
multi-region polycrystalline diamond table 69 that may include: a
first region 64, a second region 65, a third region 66, a fourth
region 67, and a fifth region 68. The first region 64 includes
polycrystalline diamond with at least some of the interstitial
regions thereof occupied by substantially only the metal-solvent
catalyst from the metal-solvent-catalyst-containing material 26. In
one embodiment of the present invention, the second region 65
includes polycrystalline diamond with at least some of the
interstitial regions thereof occupied by an alloy of silicon and
metal-solvent catalyst, such as a silicon-cobalt solid solution
alloy or an intermetallic compound of cobalt and silicon. In
another embodiment of the present invention, the second region 65
may include polycrystalline diamond with silicon carbide formed
within a portion of the interstitial regions between the bonded
diamond grains of the second region 65 and metal-solvent catalyst
(e.g., cobalt) occupying another portion of the interstitial
regions between the bonded diamond grains of the second region 65.
In yet another embodiment of the present invention, at least some
of the interstitial regions of the second region 65 may include one
or more of the following materials: silicon carbide, metal-solvent
catalyst, silicon, and an alloy of silicon and metal-solvent
catalyst. The third region 66 includes polycrystalline diamond with
substantially only silicon carbide within at least some of the
interstitial regions thereof. The fourth region 67 may include a
composition and microstructure that is the same or similar to the
second region 65. The fifth region 68 adjacent to the substrate 12
includes substantially only metal-solvent catalyst from the
substrate 12 or another source within the interstitial regions
thereof for forming a strong, metallurgical bond between the
multi-region polycrystalline diamond table 69 and the substrate 12.
After forming the multi-region polycrystalline diamond table 69, a
PDC including a polycrystalline diamond table similar in
configuration to the polycrystalline diamond table 15 shown in
FIGS. 2A and 2B may be formed by removing the first region 64 and
the second region 65 using a lapping process, a grinding process,
wire EDM, or another suitable material-removal process.
[0072] In the embodiments described above, silicon is introduced
into a polycrystalline diamond table by infiltrating molten
silicon. However, it is contemplated that silicon may be introduced
in vapor form such as via chemical vapor deposition or another
suitable vapor deposition process. Additionally, a polycrystalline
diamond table that has been integrally formed with a cemented
carbide substrate and leached to a selected depth from an upper
surface thereof may also benefit from being infiltrated with
silicon in molten or vapor form to form a more thermally-stable
polycrystalline diamond table.
[0073] FIGS. 14 and 15 show an isometric view and a top elevation
view, respectively, of a rotary drill bit 70 according to one
embodiment of the present invention. The rotary drill bit 70
includes at least one PDC configured according to any of the
previously described PDC embodiments. The rotary drill bit 70
comprises a bit body 72 that includes radially and longitudinally
extending blades 74 with leading faces 76, and a threaded pin
connection 78 for connecting the bit body 72 to a drilling string.
The bit body 72 defines a leading end structure for drilling into a
subterranean formation by rotation about a longitudinal axis 80 and
application of weight-on-bit. At least one PDC, fabricated
according to any of the previously described PDC embodiments, may
be affixed to rotary drill bit 70. As best shown in FIG. 15, a
plurality of PDCs 86 are secured to the blades 74. For example,
each PDC 86 may include a polycrystalline diamond table 88 bonded
to a substrate 90. More generally, the PDCs 86 may comprise any PDC
disclosed herein, without limitation. In addition, if desired, in
some embodiments of the present invention, a number of the PDCs 86
may be conventional in construction. Also, circumferentially
adjacent blades 74 define so-called junk slots 82 therebetween, as
known in the art. Additionally, the rotary drill bit 70 includes a
plurality of nozzle cavities 84 for communicating drilling fluid
from the interior of the rotary drill bit 70 to the PDCs 86.
[0074] FIGS. 14 and 15 merely depict one embodiment of a rotary
drill bit that employs at least one cutting element that comprises
a PDC fabricated and structured in accordance with the disclosed
embodiments, without limitation. The rotary drill bit 70 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, without limitation.
[0075] The PDCs disclosed herein may also be utilized in
applications other than cutting technology. The disclosed PDC
embodiments may be used in wire dies, bearings, artificial joints,
inserts, cutting elements, and heat sinks. Thus, any of the PDCs
disclosed herein may be employed in an article of manufacture
including at least one superabrasive element or compact.
[0076] Thus, the embodiments of PDCs disclosed herein may be used
on any apparatus or structure in which at least one conventional
PDC is typically used. For example, in one embodiment of the
present invention, a rotor and a stator (i.e., a thrust bearing
apparatus) may each include a PDC according to any of the
embodiments disclosed herein and may be operably assembled to a
downhole drilling assembly. U.S. Pat. Nos. 4,410,054; 4,560,014;
5,364,192; 5,368,398; and 5,480,233, the disclosure of each of
which is incorporated herein, in its entirety, by this reference,
disclose subterranean drilling systems within which bearing
apparatuses utilizing PDCs disclosed herein may be incorporated.
The embodiments of PDCs disclosed herein may also form all or part
of heat sinks, wire dies, bearing elements, cutting elements,
cutting inserts (e.g., on a roller cone type drill bit), machining
inserts, or any other article of manufacture as known in the art.
Other examples of articles of manufacture that may use any of the
PDCs disclosed herein are disclosed in U.S. Pat. Nos. 4,811,801;
4,268,276; 4,468,138; 4,738,322; 4,913,247; 5,016,718; 5,092,687;
5,120,327; 5,135,061; 5,154,245; 5,460,233; 5,544,713; and
6,793,681, the disclosure of each of which is incorporated herein,
in its entirety, by this reference.
[0077] The following working examples of the present invention set
forth various formulations for forming PDCs. The following working
examples provide further detail in connection with the specific
embodiments described above.
Comparative Working Example 1
[0078] A conventional PDC was formed from a mixture of diamond
particles having an average grain size of about 18 .mu.m. The
mixture was placed adjacent to a cobalt-cemented tungsten carbide
substrate. The mixture and substrate were placed in a niobium can
and HPHT sintered at a temperature of about 1400.degree. Celsius
and a pressure of about 5 GPa to about 8 GPa for about 90 seconds
to form the conventional PDC. The conventional PDC was acid-leached
to a depth of about 70 .mu.m to remove substantially all of the
cobalt from a region of the polycrystalline diamond table. The
thickness of the polycrystalline diamond table of the PDC was 0.090
inches and a 0.012 inch chamfer was machined in the polycrystalline
diamond table. The thermal stability of the conventional PDC
so-formed was evaluated by measuring the distance cut in a Sierra
White 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 PDC. The
conventional PDC was able to cut a distance of about only 2000
linear feet in the workpiece prior to failure. Evidence of failure
of the conventional PDC is best shown in FIG. 16 where the measured
temperature of the conventional PDC during cutting increased
dramatically at around about 2000 linear feet and in FIG. 17 where
the normal force required to continue cutting also increased
dramatically at around about 2000 linear feet.
Working Example 2
[0079] A PDC was formed by first fabricating a leached
polycrystalline diamond body. The leached polycrystalline diamond
body was formed by HPHT sintering diamond particles having an
average grain size of about 18 .mu.m in the presence of cobalt. The
sintered-polycrystalline-diamond body included cobalt within the
interstitial regions between bonded diamond grains. The
sintered-polycrystalline-diamond body was leached using a solution
of 90% nitric acid/10% de-ionized water for a time sufficient to
remove substantially all of the cobalt from the interstitial
regions to form the leached polycrystalline diamond body. The
leached polycrystalline diamond body was placed adjacent to a
cobalt-cemented tungsten carbide substrate. A green layer of
silicon particles was placed adjacent to the leached
polycrystalline diamond body on a side thereof opposite the
cobalt-cemented tungsten carbide substrate. The leached
polycrystalline diamond body, cobalt-cemented tungsten carbide
substrate, and green layer of silicon particles were placed within
a niobium can, and HPHT sintered at a temperature of about
1400.degree. Celsius and a pressure of about 5 GPa to about 7 GPa
for about 60 seconds to form a PDC that exhibited a similar
multi-region diamond table as the polycrystalline diamond table 15
shown in FIGS. 2A and 2B, with silicon carbide formed in a portion
of the interstitial regions between the bonded diamond grains. The
thickness of the polycrystalline diamond table was about 0.090
inches and a chamfer of about 0.01065 inch was machined in the
polycrystalline diamond table.
[0080] The thermal stability of the PDC of example 2 was evaluated
by measuring the distance cut in a Sierra White granite workpiece
without using coolant in a vertical turret lathe test. The PDC of
example 2 was able to cut a distance of over 14000 linear feet in a
granite workpiece without failing and without using coolant. This
is best shown in FIGS. 16 and 17 where the measured temperature
(FIG. 16) of the PDC of example 2 during cutting of the workpiece
and the normal force required to continue cutting the workpiece
(FIG. 17) does not increase dramatically as occurred with the
conventional PDC of comparative example 1 during cutting.
Therefore, thermal stability tests indicate that the PDC of example
2 exhibited a significantly improved thermal stability compared to
the conventional PDC of comparative example 1.
[0081] The wear resistance of the PDCs of comparative example 1 and
example 2 were evaluated by measuring the volume of the PDC removed
versus the volume of a Sierra White granite workpiece removed in a
vertical turret lathe with water used as a coolant. As shown in
FIG. 18, the wearflat volume tests indicated that the PDC of
example 2 exhibited a slightly decreased wear resistance compared
to the wear resistance of the PDC of comparative example 1.
However, the wear resistance of the PDC of example 2 is still more
than sufficient to function as a PDC for subterranean drilling
applications. Drop-weight tests also indicated that a PDC
fabricated according to example 2 exhibits an impact resistance
similar to a conventionally fabricated PDC, such as the comparative
example 1. Therefore, the PDC of example 2 exhibited a
significantly superior thermal stability compared to the
conventional PDC of comparative example 1 without significantly
compromising wear resistance and impact resistance.
[0082] Although the present invention has been disclosed and
described by way of some embodiments, it is apparent to those
skilled in the art that several modifications to the described
embodiments, as well as other embodiments of the present invention
are possible without departing from the spirit and scope of the
present invention. Additionally, the words "including" and
"having," as used herein, including the claims, shall be open ended
and have the same meaning as the word "comprising."
* * * * *