U.S. patent application number 14/493142 was filed with the patent office on 2016-09-15 for methods of fabricating a polycrystalline diamond compact including gaseous leaching of a polycrystalline diamond body.
The applicant listed for this patent is US Synthetic Corporation. Invention is credited to Kenneth E. Bertagnolli, Julie Ann Kidd, Michael A. Vail.
Application Number | 20160263727 14/493142 |
Document ID | / |
Family ID | 51702249 |
Filed Date | 2016-09-15 |
United States Patent
Application |
20160263727 |
Kind Code |
A1 |
Kidd; Julie Ann ; et
al. |
September 15, 2016 |
METHODS OF FABRICATING A POLYCRYSTALLINE DIAMOND COMPACT INCLUDING
GASEOUS LEACHING OF A POLYCRYSTALLINE DIAMOND BODY
Abstract
Embodiments of the invention relate to methods of fabricating
polycrystalline diamond compacts ("PDCs") and applications for such
PDCs. In an embodiment, a method of fabricating a PDC includes
providing a polycrystalline diamond ("PCD") table in which a
catalyst is disposed throughout, leaching the PCD table with a
gaseous leaching agent to remove catalyst from the PCD table and
bonding the at least partially leached PCD table to a substrate to
form a PDC.
Inventors: |
Kidd; Julie Ann; (North
Ogden, UT) ; Vail; Michael A.; (Genola, UT) ;
Bertagnolli; Kenneth E.; (Riverton, UT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
US Synthetic Corporation |
Orem |
UT |
US |
|
|
Family ID: |
51702249 |
Appl. No.: |
14/493142 |
Filed: |
September 22, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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13324237 |
Dec 13, 2011 |
8864858 |
|
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14493142 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C09K 3/1409 20130101;
B24D 3/06 20130101; B24D 99/005 20130101; B24D 18/00 20130101; B24D
3/10 20130101 |
International
Class: |
B24D 3/10 20060101
B24D003/10 |
Claims
1. A method, comprising: forming a polycrystalline diamond table
having catalyst distributed therethrough; leaching the catalyst
from at least a portion of the polycrystalline diamond table using
a flow of a gaseous leaching agent; infiltrating the
polycrystalline diamond table with a metallic infiltrant from a
substrate under conditions effective to bond the infiltrated
polycrystalline diamond table to the substrate to form a
polycrystalline diamond compact; and removing at least a portion of
the metallic infiltrant from the infiltrated polycrystalline
diamond table of the polycrystalline diamond compact by exposing at
least one working surface of the infiltrated polycrystalline
diamond table to a gaseous leaching agent.
2. The method of claim 1 wherein the gaseous leaching agent
includes a mixture of a halogen and at least one inert gas.
3. The method of claim 1 wherein the gaseous leaching agent
includes a gas selected from the group consisting of at least one
halide gas, at least one inert gas, a gas from the decomposition of
an ammonium halide salt, a hydrogen gas, a reducing gas, an acid
gas, a gaseous compound including halogen elements, a hydrogen
chloride gas, a hydrogen fluoride gas, a nitrogen gas, and mixtures
thereof.
4. The method of claim 1, further comprising: prior to the act of
infiltrating, heating the at least partially leached
polycrystalline diamond table under partial vacuum conditions to
remove at least some leaching by-products from the leached
polycrystalline diamond table generated during the act of
leaching.
5. The method of claim 4 wherein heating the at least partially
leached polycrystalline diamond table under partial vacuum
conditions comprises: heating the at least partially leached
polycrystalline diamond table at a temperature sufficient to
sublimate the at least some leaching by-products.
6. The method of claim 5 wherein the temperature is above about
500.degree. C. and below about 700.degree. C.
7. The method of claim 1, further comprising: prior to the act of
infiltrating, removing at least some leaching by-products from the
at least partially leached polycrystalline diamond table generated
during the act of leaching by chemically cleaning the leached
polycrystalline diamond table.
8. The method of claim 1, further comprising: prior to the act of
infiltrating, removing at least some leaching by-products from the
at least partially leached polycrystalline diamond table generated
during the act of leaching by using an autoclave under
diamond-stable conditions.
9. The method of claim 1, further comprising: removing at least
some of the leaching by-products from the at least partially
leached polycrystalline diamond table generated during the act of
removing at least a portion of the metallic infiltrant from the
infiltrated polycrystalline diamond table of the polycrystalline
diamond compact.
10. The method of claim 1, further comprising reducing a
non-planarity of an interfacial surface of the at least partially
leached polycrystalline diamond table prior to infiltrating the at
least partially leached polycrystalline diamond table with the
metallic infiltrant.
11. The method of claim 10 wherein reducing a non-planarity of the
interfacial surface of the at least partially leached
polycrystalline diamond table prior to infiltrating the at least
partially leached polycrystalline diamond table with the metallic
infiltrant comprises substantially planarizing the interfacial
surface to a flatness of about 0.00050 inch to about 0.0010
inch.
12. The method of claim 10 wherein reducing a non-planarity of the
interfacial surface of the at least partially leached
polycrystalline diamond table prior to bonding the at least
partially leached polycrystalline diamond table to the substrate
occurs prior to removing at least some leaching by-products from
the leached polycrystalline diamond table.
13. The method of claim 1, further comprising leaching a portion of
the metallic infiltrant present in the infiltrated polycrystalline
diamond table to a selected leach depth of about 50 .mu.m to about
800 .mu.m.
14. A method, comprising: forming a polycrystalline diamond table
having catalyst distributed therethrough; leaching the catalyst
from at least a portion of the polycrystalline diamond table using
a gaseous leaching agent; infiltrating the polycrystalline diamond
table with a metallic infiltrant from a substrate under conditions
effective to bond the infiltrated polycrystalline diamond table to
the substrate to form a polycrystalline diamond compact; protecting
the substrate and at least a portion of the polycrystalline diamond
table proximate to the substrate to limit unintended leaching; and
leaching the metallic infiltrant from a portion of the
polycrystalline diamond table to define a first volume within the
polycrystalline diamond table remote from the substrate and a
second volume within the polycrystalline diamond table adjacent to
the substrate, wherein the first volume is substantially free of
the metallic infiltrant and the second volume is substantially
unaffected by the leaching.
15. The method of claim 14 wherein the gaseous leaching agent
includes a mixture of a halogen and at least one inert gas.
16. The method of claim 14 wherein the gaseous leaching agent
includes a gas selected from the group consisting of at least one
halide gas, at least one inert gas, a gas from the decomposition of
an ammonium halide salt, a hydrogen gas, a reducing gas, an acid
gas, a gaseous compound including halogen elements, a hydrogen
chloride gas, a hydrogen fluoride gas, a nitrogen gas, and mixtures
thereof.
17. The method of claim 14, further comprising reducing a
non-planarity of an interfacial surface of the at least partially
leached polycrystalline diamond table prior to infiltrating the at
least partially leached polycrystalline diamond table with the
metallic infiltrant.
18. A method of forming a polycrystalline diamond compact,
comprising: placing a mass of diamond particles adjacent to a
substrate including a metal-solvent catalyst therein; subjecting
the mass of diamond particles and the substrate a
high-pressure/high-temperature sintering process to form a
polycrystalline diamond table with the metal-solvent distributed
therethrough. separating the polycrystalline diamond table from the
substrate; leaching the metal-solvent catalyst from at least a
portion of the polycrystalline diamond table using a gaseous
leaching agent; removing at least some leaching by-products from
the at least partially leached polycrystalline diamond table
generated during the act of leaching; and infiltrating the
polycrystalline diamond table with a metallic infiltrant from
another substrate using a high-pressure/high-temperature sintering
process effective to bond the infiltrated polycrystalline diamond
table to the additional substrate.
19. The method of claim 18 wherein the gaseous leaching agent
includes a mixture of a halogen and at least one inert gas.
20. The method of claim 18 wherein the gaseous leaching agent
includes a gas selected from the group consisting of at least one
halide gas, at least one inert gas, a gas from the decomposition of
an ammonium halide salt, a hydrogen gas, a reducing gas, an acid
gas, a gaseous compound including halogen elements, a hydrogen
chloride gas, a hydrogen fluoride gas, a nitrogen gas, and mixtures
thereof.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a division of U.S. application Ser. No.
13/324,237 filed on 13 Dec. 2011, the disclosure of which is
incorporated herein, in its entirety, by this reference.
BACKGROUND
[0002] Wear-resistant, superabrasive compacts are utilized in 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
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 (also known as a diamond table). The
diamond table is formed and bonded to a substrate using an
ultra-high pressure, ultra-high temperature ("HPHT") process. The
PDC cutting element may also be brazed directly into a preformed
pocket, socket, or other receptacle formed in the bit body. The
substrate may be often 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 or cartridge with a
volume of diamond particles positioned adjacent to a surface of the
cemented-carbide substrate. A number of such cartridges may be
loaded into a 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
polycrystalline diamond ("PCD") table. The catalyst material is
often a metal-solvent catalyst, such as cobalt, nickel, iron, or
alloys thereof that is used for promoting intergrowth of the
diamond particles.
[0005] In one conventional approach for forming a PDC, 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 solvent catalyst to promote
intergrowth between the diamond particles, which results in
formation of bonded diamond grains. A solvent catalyst may be mixed
with the diamond particles prior to subjecting the diamond
particles and substrate to the HPHT process.
[0006] In another conventional approach for forming a PDC, a
sintered PCD table may be separately formed and then leached to
remove solvent catalyst from interstitial regions between bonded
diamond grains. The leached PCD table may be simultaneously HPHT
bonded to a substrate and infiltrated with a non-catalyst material,
such as silicon, in a separate HPHT process. The silicon may
infiltrate the interstitial regions of the sintered PCD table from
which the solvent catalyst has been leached and react with the
diamond grains to form silicon carbide.
[0007] Despite the availability of a number of different PCD
materials, manufacturers and users of PCD materials continue to
seek PCD materials that exhibit improved toughness, wear
resistance, and/or thermal stability.
SUMMARY
[0008] Embodiments of the invention relate to methods of
fabricating PDCs and applications for such PDCs. In an embodiment,
a method of fabricating a PDC includes providing a PCD table
including a plurality of bonded diamond grains defining a plurality
of interstitial regions in which a metal-solvent catalyst is
disposed. The PCD table may then be leached with a gaseous leaching
agent to at least partially remove the metal-solvent catalyst from
the PCD table. The at least partially leached PCD table may then be
bonded to a substrate to form the PDC.
[0009] 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
[0010] 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.
[0011] FIGS. 1A-1E are cross-sectional views illustrating a method
of fabricating a PDC according to an embodiment.
[0012] FIGS. 2A and 2B are cross-sectional views illustrating a
method of cleaning the at least partially leached PCD table shown
in FIG. 1D prior to being bonding to a substrate according to an
embodiment.
[0013] FIGS. 3A-3D are cross-sectional views illustrating a method
of reducing a non-planarity of an interfacial surface of the at
least partially leached PCD table shown in FIG. 1D prior to bonding
to a substrate according to an embodiment.
[0014] FIGS. 4A and 4B are cross-sectional views illustrating a
method of leaching a PCD table of a PDC using a gaseous leaching
agent according to another embodiment.
[0015] FIG. 5 is an isometric view of a rotary drill bit according
to an embodiment that may employ one or more of the disclosed PDCs
fabricated according to any of the embodiments disclosed
herein.
[0016] FIG. 6 is a top elevation view of the rotary drill bit shown
in FIG. 5.
[0017] FIG. 7 is an isometric cut-away view of a thrust-bearing
apparatus according to an embodiment, which may utilize any of the
disclosed PDC fabricated according to any of the embodiments
disclosed herein as bearing elements.
[0018] FIG. 8 is an isometric cut-away view of a radial bearing
apparatus according to an embodiment, which may utilize any of the
disclosed PDC fabricated according to any of the embodiments
disclosed herein as bearing elements.
DETAILED DESCRIPTION
[0019] Embodiments of the invention relate to methods of
fabricating PDCs and PCD tables in a manner that facilitates
removal of metal-solvent catalyst used in the manufacture of PCD
tables of such PDCs. The PDC embodiments 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.
[0020] FIGS. 1A-1E are cross-sectional views illustrating a method
of fabricating a PDC according to an embodiment that comprises
forming a PCD table from a plurality of diamond particles and a
catalyst in a first HPHT process and at least partially leaching
the so-formed PCD table by exposing the PCD table to a flow of a
gaseous leaching agent. A PDC is formed by bonding the at least
partially leached PCD table to a substrate in a second HPHT
process. Such a method may provide for more effective leaching of
the catalyst from the PCD table before and/or after bonding to the
substrate.
[0021] Referring to FIG. 1A, a cross-sectional view of an assembly
100 is illustrated in which a mass of a plurality of diamond
particles 104 are placed adjacent to a substrate 108. A PCD table
124 as shown in FIG. 1B may be fabricated by subjecting the
plurality of diamond particles 104 (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 catalyst, such as
cobalt, nickel, iron, or an alloy of any of the preceding metals to
facilitate intergrowth between the diamond particles 104 and form
the PCD table 124 (FIG. 1B) comprising directly bonded-together
diamond grains (e.g., exhibiting sp.sup.3 bonding) defining
interstitial regions with the catalyst disposed within at least a
portion of the interstitial regions. In the illustrated embodiment,
the PCD table 124 is formed by sintering the diamond particles 104
on the substrate 108, which may be a cobalt-cemented tungsten
carbide substrate from which cobalt or a cobalt alloy infiltrates
into the diamond particles 104. For example, the substrate 108 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 catalysts that
may form part of the substrate 108. Other materials for the
substrate 108 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. However, in
other embodiments, the substrate 108 may be replaced with a
metal-solvent catalyst disc and/or catalyst particles may be mixed
with the diamond particles 104.
[0022] The diamond particle size distribution of the plurality of
diamond particles 104 may exhibit a single mode, or may be a
bimodal or greater grain size distribution. In an embodiment, the
diamond particles 104 may comprise 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 (by any suitable method) that differ by at least a factor of
two (e.g., 30 .mu.m and 15 .mu.m). According to various
embodiments, the diamond particles 104 may include a portion
exhibiting a relatively larger average particle size (e.g., 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 average particle size (e.g., 6 .mu.m, 5 .mu.m, 4 .mu.m, 3
.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 an embodiment, the diamond particles 104
may include a portion exhibiting a relatively larger average
particle size between about 10 .mu.m and about 40 .mu.m and another
portion exhibiting a relatively smaller average particle size
between about 1 .mu.m and 4 .mu.m. In some embodiments, the diamond
particles 104 may comprise three or more different average particle
sizes (e.g., one relatively larger average particle size and two or
more relatively smaller average particle sizes), without
limitation.
[0023] FIG. 1B illustrates a cross-sectional view of a PDC 120
formed by HPHT processing of the assembly 100 shown in FIG. 1A. In
such an embodiment, the PCD table 124 so-formed may include
tungsten and/or tungsten carbide that is swept in with the catalyst
from the substrate 108. For example, some tungsten and/or tungsten
carbide from the substrate may be dissolved or otherwise
transferred by the liquefied catalyst (e.g., cobalt from a
cobalt-cemented tungsten carbide substrate) of the substrate 108
that sweeps into the diamond particles 104. Additional details
about methods of manufacturing the PDC 120 and magnetic properties
of the PCD table 124 may be found in U.S. Pat. No. 7,866,418, which
is incorporated herein, in its entirety, by this reference.
[0024] The PCD table 124, shown in FIG. 1B, may be separated from
the substrate 108 using a lapping process, a grinding process,
wire-electrical-discharge machining ("wire EDM"), combinations
thereof, or another suitable material-removal process. As shown in
FIG. 1C, the separated PCD table 124 may be enclosed in a suitable
reaction chamber 130 containing a flow of a gaseous leaching agent
132 that is selected to substantially remove all of the catalyst
from the interstitial regions of the separated PCD table 124 and
form an at least partially leached PCD table 200 as shown in FIG.
1D. In an embodiment, the sintered diamond grains of an at least
partially leached PCD table 200 may exhibit an average grain size
of about 20 .mu.m or less.
[0025] Gaseous leaching agents may be used to remove at least a
portion of the catalyst from the PCD table 124. The gaseous
leaching agent may be selected from at least one halide gas, at
least one inert gas, a gas from the decomposition of an ammonium
halide salt, hydrogen gas, carbon monoxide gas, an acid gas, and
mixtures thereof. For example, a gaseous leaching agent may include
mixtures of a halogen gas (e.g., chlorine, fluorine, bromine,
iodine, or combinations thereof) and an inert gas (e.g., argon,
xenon, neon, krypton, radon, or combinations thereof). Other
gaseous leaching agents include mixtures including hydrogen
chloride gas, a reducing gas (e.g., carbon monoxide gas), gas from
the decomposition of an ammonium salt (such as ammonium chloride
which decomposes into chlorine gas, hydrogen gas and nitrogen gas),
and mixtures of hydrogen gas and chlorine gas (which will form
hydrogen chloride gas, in situ), acid gases such as hydrogen
chloride gas, hydrochloric acid gas, hydrogen fluoride gas, and
hydrofluoric acid gas. Any combination of any of the disclosed
gases may be employed as the gaseous leaching agent. In an
embodiment, the reaction chamber 130 may be filled with a gaseous
leaching agent of about 10 volume % to about 20 volume % chlorine
with the balance being argon and the gaseous leaching agent being
at an elevated temperature of at least about 300.degree. C. to
about 800.degree. C. In another embodiment, the elevated
temperature may be between at least about 600.degree. C. to about
700.degree. C. More specifically, in another embodiment, the
elevated temperature may be at least about 650.degree. C. to about
700.degree. C.
[0026] In an embodiment, the leaching process may take place in the
reaction chamber 130 placed within a box furnace. For example, the
reaction chamber 130 may be flushed at room temperature with an
inert gas, such as argon. The reaction chamber 130 is heated under
a flow of argon at a rate of about 10.degree. C./min, to the
desired elevated temperature. According to an embodiment, once the
reaction chamber 130 reaches the desired temperature of, for
example, 700.degree. C., the gaseous leaching agent is introduced
at a flow rate of 900 ml/min (measured at STP, 25.degree. C., and 1
atm) to create the gaseous flow 132 within the reaction chamber 130
as shown in FIG. 1C. The flow rate of the gaseous leaching agent
may optionally be consistently maintained for the duration of the
leaching reaction ranging from 15 minutes to 12 hours, depending on
reaction conditions (i.e., the temperature selected, gaseous
leaching agent used, the selected leach depth desired, etc.).
[0027] In an embodiment, a gaseous leaching agent including at
least about 0.1% to less than about 100% chlorine gas, with the
balance comprised of argon gas may be used at a temperature of
700.degree. C. and a flow rate of 900 ml/min for at least 1 hour.
In an embodiment, a gaseous leaching agent comprising 20% carbon
monoxide, 20% chlorine and 60% argon may be used at a temperature
of 600.degree. C. and a flow rate of 900 ml/min for at least 1
hour. In another embodiment, a gaseous leaching agent comprising
20% chlorine, 20% hydrogen chloride and 60% argon may be used at a
temperature of 700.degree. C. and a flow rate of 900 ml/min for at
least 1 hour. In yet another embodiment, a gaseous leaching agent
comprising 20% chlorine and 80% argon may be used at a temperature
of 700.degree. C. and a flow rate of 900 ml/min for at least 1
hour.
[0028] FIG. 1D illustrates a cross-sectional view of an assembly of
an at least partially leached PCD table 200 (i.e., a porous, PCD
table) and a substrate 206 that may be made from the same materials
as the substrate 108 previously discussed. The at least partially
leached PCD table 200, includes a first surface 202 and an opposing
second interfacial surface 204. The at least partially leached PCD
table 200 includes a plurality of interstitial regions that were
previously occupied by the catalyst and form a network of at least
partially interconnected pores that extend between the first
surface 202 and the second interfacial surface 204.
[0029] The assembly, shown in FIG. 1D, of the at least partially
leached PCD table 200 and substrate 206 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. The pressure
transmitting medium, including the assembly, may be subjected to an
HPHT process using an HPHT press at a temperature of at least about
1000.degree. C. (e.g., about 1300.degree. C. to about 1600.degree.
C.) and a pressure of at least 4 GPa (e.g., about 5 GPa to about 10
GPa, about 7 GPa to about 9 GPa) for a time sufficient to bond the
at least partially leached PCD table 200 to the substrate 206 and
form a PDC 210 as shown in FIG. 1E. The HPHT process bonds the at
least partially leached PCD table 200 to the substrate 206 and may
cause metallic infiltrant from the substrate 206 or another source
to infiltrate the interstitial regions of the at least partially
leached PCD table 200. The HPHT temperature may be sufficient to
melt at least one constituent of the substrate 206 (e.g., cobalt,
nickel, iron, alloys thereof, or another constituent) that
infiltrates the at least partially leached PCD table 200. The PDC
210 so-formed includes an infiltrated PCD table 214 in which the
interstitial regions thereof are at least partially filled with the
infiltrant. It is noted that the PDC 210 may exhibit other
geometries than the geometry illustrated in FIG. 1E. For example,
the PDC 210 may exhibit a non-cylindrical geometry.
[0030] In some embodiments, the PDC 210 so-formed may be subjected
to a number of different shaping operations. For example, an upper
working surface 212 may be planarized and/or polished.
Additionally, a peripherally-extending chamfer may be formed that
extends between the upper working surface 212 and a side surface of
the infiltrated PCD table 214. The shaping operations include
lapping, grinding, wire EDM, combinations thereof, or another
suitable material-removal process.
[0031] As a result of the leaching process used to remove the
catalyst, the at least partially leached PCD table 200 shown in
FIG. 1D may include leaching by-products. For example, the gaseous
leaching agent used to remove, for example, cobalt from the
interstitial regions may leave one or more types of residual salts,
one or more types of oxides, combinations of the foregoing, or
another leaching by-product within at least some of the
interstitial regions of the at least partially leached PCD table
200. For example, depending upon the chemistry of the leaching
solution, the leaching by-products may comprise a salt of nitric
acid, hydrochloric acid, phosphoric acid, acetic acid, or mixtures
of the foregoing. For example, the salt may be cobalt nitrate or
cobalt chloride. The leaching by-products may also comprise a metal
oxide, such as an oxide of tungsten, cobalt or other metal-solvent
catalyst, and/or another type of metal present in the catalyst of
the at least partially leached PCD table 200 prior to leaching. It
is currently believed that such leaching by-products may block,
obstruct, or otherwise inhibit infiltration of the at least
partially leached PCD table 200 with metallic infiltrant, such as
cobalt, when the at least partially leached PCD table 200 is bonded
to the substrate 206. Additionally, such leaching by-products may
inhibit back filling with a non-catalyst material such as
silicon.
[0032] Referring to FIG. 2A, at least some of the leaching
by-products may be removed from the at least partially leached PCD
table 200. For example, as shown in FIG. 2B, at least some of the
leaching by-products may be removed by subjecting the at least
partially leached PCD table 200 to a thermal-cleaning process. In
such a thermal-cleaning process, the at least partially leached PCD
table 200 may be heated under partial vacuum (e.g., at a pressure
less than ambient atmospheric pressure) to a temperature sufficient
to sublimate at least some of the leaching by-products present in
the at least partially leached PCD table 200, but below a
temperature at which the diamond grains of the at least partially
leached PCD table 200 may significantly degrade. For example, the
at least partially leached PCD table 200 may be heated in a vacuum
furnace at a temperature between at least about 500.degree. C. and
less than about 700.degree. C. for about 0.5 hours to about 2.0
hours or more. In an embodiment, the at least partially leached PCD
table 200 may be heated in a vacuum furnace at a temperature of
about 650.degree. C. for about 1 hour to about 1.5 hours.
[0033] In another embodiment, the at least partially leached PCD
table 200 may be cleaned using an autoclave under diamond-stable
conditions in which heat and pressure is applied at a temperature
and pressure sufficient to sublimate at least some of the leaching
by-products present in the at least partially leached PCD table
200. Suitable elevated temperature levels used in the autoclave
process may range from approximately the boiling point of the
leaching agent and/or the leaching by-products to three times the
boiling point of the leaching agent and/or the leaching
by-products. For example, in an embodiment, the elevated
temperature of the autoclave process may be about 90.degree. C. to
about 350.degree. C., such as about 175.degree. C. to about
225.degree. C. In other embodiments, the elevated temperature may
be up to about 300.degree. C. The pressure of the autoclave process
may be selected so that diamond-stable or non-stable conditions are
used, such as a pressure of about 0.5 MPa to about 3 GPa (e.g.,
about 1 GPa to about 2 GPa).
[0034] In another embodiment, at least some of the leaching
by-products may be removed from the at least partially leached PCD
table 200 using a chemical cleaning process. For example, the at
least partially leached PCD table 200 may be immersed in
hydrofluoric acid. The concentration of the hydrofluoric acid and
the immersion time of the at least partially leached PCD table 200
in the hydrofluoric acid may be selected so that at least some of
the leaching by-products and, in some embodiments, substantially
all of the leaching by-products may be removed from the at least
partially leached PCD table 200. In other embodiments, nitric acid,
sulfuric acid, hydrochloric acid, hydrogen peroxide, phosphoric
acid, perchloric acid, any combination of foregoing acids, or the
like, may be selected in place of hydrofluoric acid as a chemical
cleaning agent.
[0035] In an embodiment of a chemical cleaning process, at least
some of the leaching by-products may be removed using an ultrasonic
cleaning process. For example, the at least partially leached PCD
table 200 of FIG. 2A may be immersed in a selected solvent and
ultrasonic energy applied to the selected solvent for a selected
period of time to effect removal of at least some of the leaching
by-products and, in some embodiments, substantially all of the
leaching by-products may be removed from the at least partially
leached PCD table 200. The selected solvent may be an aqueous
solution (e.g., hydrofluoric acid) or an organic solvent. In other
embodiments using the thermal or autoclave cleaning processes
discussed herein, the cleaning processes may also be supplemented
by the application of ultrasonic energy. Such ultrasonic methods
can decrease required cleaning time, and may increase the
efficiency of thermal, autoclave, and chemical cleaning
processes.
[0036] In another embodiment, following removal of at least some of
the leaching by-products, the second interfacial surface 204 of the
at least partially leached PCD table 200 may be bonded to a
substrate in an HPHT bonding process to form a PDC in the same
manner as the at least partially leached PCD table 200 was bonded
to form the PDC 210 shown in FIGS. 1D and 1E.
[0037] Additional details about techniques for cleaning the at
least partially leached PCD table 200 may be found in U.S. Pat. No.
7,845,438. U.S. Pat. No. 7,845,438 is incorporated herein, in its
entirety, by this reference.
[0038] FIG. 3A illustrates a cross-sectional view of an at least
partially leached and cleaned PCD table 300. In the embodiment of
FIG. 3A, after cleaning to remove at least some of the leaching
by-products, a second interfacial surface 302 may be substantially
planarized to reduce a non-planarity thereof. For example, the
planarizing may be accomplished using a planarizing machine, such
as a lapping pad, a grinding pad, or other mechanical or
chemical-mechanical planarization machine. Substantially
planarizing the second interfacial surface 302 of the at least
partially leached PCD table 300 by removing material therefrom
results in formation of a substantially planarized interfacial
surface 304 as shown in FIG. 3B. It is noted that the substantially
planarized interfacial surface 304 may or may not include part of
the former second interfacial surface 302 depending upon the amount
of material removed from the at least partially leached PCD table
300. The substantially planarized interfacial surface 304 may
exhibit a flatness of about 0.00050 inch to about 0.0010 inch. In
another embodiment, the flatness may be about 0.00050 inch to about
0.0075 inch.
[0039] Referring to FIG. 3C, the substantially planarized
interfacial surface 304 of the at least partially leached PCD table
300 may be placed at least proximate to a substrate 308 to form an
assembly 310. For example, in an embodiment, the substantially
planarized interfacial surface 304 may abut with a surface 306 of
the substrate 308. The substrate 308 may be made from any the
materials discussed above for the substrate 108. The assembly 310
may be subjected to HPHT processing for a time sufficient to bond
the at least partially leached PCD table 300 to the substrate 308
and form a PDC 320 as shown in FIG. 3D. The HPHT process bonds the
at least partially leached PCD table 300 to the substrate 308 and
may cause a metallic infiltrant from the substrate 308 or another
source to infiltrate the interstitial regions of the at least
partially leached PCD table 300. The HPHT temperature may be
sufficient to melt at least one constituent of the substrate 308
(e.g., cobalt, nickel, iron, alloys thereof, or another
constituent) that infiltrates the substrate 308. The PDC 320
so-formed includes a PCD table 322 in which the interstitial
regions thereof are at least partially filled with the metallic
infiltrant. It is noted that the PDC 320 may exhibit other
geometries than the geometry illustrated in FIG. 3D. For example,
the PDC 320 may exhibit a non-cylindrical geometry.
[0040] Because the at least partially leached PCD table 300 was
leached with a gaseous leaching agent and cleaned to remove at
least some of the leaching by-products prior to bonding to the
substrate 308, the PCD table 322 so-formed is believed to have at
least one of improved thermal stability, manufacturability, or
performance. In embodiments where the second interfacial surface
302 is substantially planarized, (as shown in FIGS. 3A and 3B),
because the substantially planarized interfacial surface 304 of the
at least partially leached PCD table 300 is substantially planar,
the HPHT process used to form the PDC 320 may not introduce tensile
bending stresses sufficient to cause cracking, and/or spalling in
the PCD table 322 during the HPHT process.
[0041] It should be noted that, in some embodiments, the
planarization process described in FIGS. 3A-3D may be performed on
an un-cleaned at least partially leached PCD table 200 instead of
the at least partially leached and cleaned PCD table 300. In other
embodiments, the cleaning process may be performed after the
planarization process described in FIGS. 3A-3D.
[0042] Referring to FIGS. 4A and 4B, in an embodiment, the
infiltrated PCD table 214 of the PDC 210 (shown in FIG. 1E) may be
leached with a gaseous leaching agent to remove a metallic
infiltrant that forms part of the infiltrated PCD table 214 to a
selected leach depth d measured from an upper working surface 212.
In some embodiments, the infiltrated PCD table 214 may be chamfered
before being subjected to the gaseous leaching process shown in
FIG. 4A. For example, the infiltrated PCD table 214 may be enclosed
in a reaction chamber 400, as illustrated in FIG. 4A, containing a
flow of the gaseous leaching agent 410 (e.g., a mixture of the
halogen, chlorine gas, and an inert gas, argon gas) to leach the
metallic infiltrant from the infiltrated PCD table 214 to form a
first volume 404, shown in FIG. 4B, substantially free of the
metallic infiltrant and remote from a substrate 206. A second
volume 406, proximate to the substrate 206, is relatively
unaffected by the leaching process and includes the metallic
infiltrant therein.
[0043] Although not shown, the substrate 206 and selected portions
of the infiltrated PCD table 214 may be masked or otherwise
protected to limit unintended leaching and damage to the masked
portions. In an embodiment selected portions of the infiltrated PCD
table 214 may be subjected to a masking treatment to mask areas
that are desired to remain unaffected by the leaching process, such
as portions of the second volume 406 at and/or near the substrate
206. For example, electrodeposition or plasma deposition of a
nickel alloy (e.g., a suitable Inconel.RTM. alloy), a suitable
metal, or a metallic alloy covering the substrate 206 and the
second volume 406 may be used to limit the leaching process to the
desired directed area, the first volume 404. In other embodiments,
protective leaching trays and cups for protecting portions of the
infiltrated PCD table 214 and substrate 206 from leaching solution
during leaching may be used. Such methods are disclosed in U.S.
Patent Application No. 61/523,659 filed on 15 Aug. 2011, which is
incorporated herein, in its entirety, by this reference. In another
embodiment, a leaching cup made from a nickel alloy may be placed
around a portion of the infiltrated PCD table 214 to serve as a
shield to mask or otherwise protect a selected portion of the
infiltrated PCD table 214 from the leaching process.
[0044] In an embodiment, as shown in FIG. 4B, the leach depth d
that the first volume 404 extends to may be greater than about 200
gm. In another embodiment, the leach depth d may be about 50 .mu.m
to about 800 .mu.m. In another embodiment, the leach depth d may be
about 400 .mu.m to about 800 .mu.m. In embodiments in which the at
least partially leached PCD table is cleaned prior to bonding to
the substrate 206, even after partially leaching the infiltrated
PCD table 214, at least a region of the infiltrated PCD table 214
proximate to and including the interfacial surface 204 (or the
substantially planarized interfacial surface 304) may be
substantially free of leaching by-products. In another embodiment,
the infiltrated PCD table 214 may be leached so that the leach
depth d may be approximately equal to a thickness of the
infiltrated PCD table 214.
[0045] After leaching the infiltrated PCD table 214, the
infiltrated PCD table 214 may be treated using any of the
previously described cleaning processes, such as thermal or
chemical cleaning, to remove some or substantially all leaching
by-products therefrom from the first volume 404. It is currently
believed that removing at least some of the leaching by-products
from the infiltrated PCD table 214 may increase at least one of the
thermal stability, manufacturability, or performance. of the
leached PCD table.
[0046] Any and all of the embodiments of the PDC fabrication
methods discussed herein, including the embodiments shown in FIGS.
1-4, may include the forming of a PCD table using a first HPHT
process. Further, embodiments of the invention may comprise a
method including at least one or more of the following acts:
forming a PCD table in a first HPHT process, removing a PCD table
from a substrate, leaching of a PCD table using a gaseous leaching
agent to at least partially remove metal catalyst or metallic
infiltrant filled within the interstitial regions of the PCD table,
cleaning of the at least partially leached PCD table to remove
leaching by-products, substantially planarizing a surface of the at
least partially leached PCD table, bonding of the at least
partially leached PCD table to a substrate in a second HPHT
process, infiltrating the interstitial regions of the at least
partially leached PCD table with a metallic infiltrant from the
substrate to form a PDC, leaching the at least partially
infiltrated PCD table of the PDC using a gaseous leaching agent to
a specified depth, and subjecting the leached, infiltrated PCD
table of the PDC to cleaning using at least one of the thermal,
chemical, or ultrasonic cleaning methods discussed herein. The
first cleaning and planarizing steps (before bonding the leached
PCD table to a substrate to form a PDC) may be interchanged so that
the planarizing may occur either prior to or after the first
cleaning step. Any of the foregoing methods, acts, as well as
portions or combinations thereof disclosed herein are contemplated
as embodiments of the invention.
[0047] FIG. 5 is an isometric view and FIG. 6 is a top elevation
view of a rotary drill bit 500 according to an embodiment. The
rotary drill bit 500 includes at least one PDC fabricating
according to any of the previously described PDC embodiments. The
rotary drill bit 500 comprises a bit body 502 that includes
radially and longitudinally extending blades 504 with leading faces
506, and a threaded pin connection 508 for connecting the bit body
502 to a drilling string. The bit body 502 defines a leading end
structure configured for drilling into a subterranean formation by
rotation about a longitudinal axis 510 and application of
weight-on-bit. At least one PDC cutting element, manufactured and
configured according to any of the previously described PDC
embodiments (e.g., the PDC 210 shown in FIG. 1E), may be affixed to
rotary drill bit 500 by, for example, brazing, mechanical affixing,
or another suitable technique. With reference to FIG. 6, each of a
plurality of PDCs 512 is secured to the blades 504. For example,
each PDC 512 may include a PCD table 514 bonded to a substrate 516.
More generally, the PDCs 512 may comprise any PDC disclosed herein,
without limitation. In addition, if desired, in an embodiment, a
number of the PDCs 512 may be conventional in construction. Also,
circumferentially adjacent blades 504 define so-called junk slots
518 therebetween, as known in the art. Additionally, the rotary
drill bit 500 includes a plurality of nozzle cavities 520 for
communicating drilling fluid from the interior of the rotary drill
bit 500 to the PDCs 512.
[0048] FIGS. 5 and 6 merely depict one embodiment of a rotary drill
bit that employs at least one cutting element comprising a PDC
fabricated and structured in accordance with the disclosed
embodiments, without limitation. The rotary drill bit 500 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, mining
rotary drill bits, or any other downhole tool including PDCs,
without limitation.
[0049] The PDCs disclosed herein may also be utilized in
applications other than rotary drill bits. For example, the
disclosed PDC embodiments may be used in thrust-bearing assemblies,
radial bearing assemblies, wire-drawing dies, artificial joints,
machining elements, PCD windows, and heat sinks
[0050] FIG. 7 is an isometric cut-away view of a thrust-bearing
apparatus 700 according to an embodiment, 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 manufactured and
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.
[0051] 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."
[0052] FIG. 8 is an isometric cut-away view of a radial bearing
apparatus 800 according to an embodiment, which may utilize any of
the disclosed PDC embodiments as bearing elements. The radial
bearing apparatus 800 includes an inner race 802 positioned
generally within an outer race 804. The outer race 804 includes a
plurality of bearing elements 806 affixed thereto that have
respective bearing surfaces 808. The inner race 802 also includes a
plurality of bearing elements 810 affixed thereto that have
respective bearing surfaces 812. One or more, or all of the bearing
elements 806 and 810 may be configured according to any of the PDC
embodiments disclosed herein. The inner race 802 is positioned
generally within the outer race 804, with the inner race 802 and
outer race 804 configured so that the bearing surfaces 808 and 812
may at least partially contact one another and move relative to
each other as the inner race 802 and outer race 804 rotate relative
to each other during use.
[0053] 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 be open
ended and have the same meaning as the word "comprising" and
variants thereof (e.g., "comprise" and "comprises").
* * * * *