U.S. patent application number 14/088935 was filed with the patent office on 2014-05-29 for eruption control in thermally stable pcd products.
The applicant listed for this patent is Ronald K. Eyre, Guojiang Fan, Jeffrey Bruce Lund. Invention is credited to Ronald K. Eyre, Guojiang Fan, Jeffrey Bruce Lund.
Application Number | 20140144713 14/088935 |
Document ID | / |
Family ID | 50772291 |
Filed Date | 2014-05-29 |
United States Patent
Application |
20140144713 |
Kind Code |
A1 |
Lund; Jeffrey Bruce ; et
al. |
May 29, 2014 |
ERUPTION CONTROL IN THERMALLY STABLE PCD PRODUCTS
Abstract
A method of making a polycrystalline diamond cutting element
includes placing a body of polycrystalline diamond including a
matrix phase of bonded together diamond grains and a plurality of
empty interstitial spaces between the bonded together diamond
grains adjacent a first substrate material to form an assembly and
subjecting the assembly to high pressure/high temperature
conditions that include an initial pressure ramping, a pressure
hold, and a second pressure ramping.
Inventors: |
Lund; Jeffrey Bruce; (Salt
Lake City, UT) ; Eyre; Ronald K.; (Orem, UT) ;
Fan; Guojiang; (Lehi, UT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lund; Jeffrey Bruce
Eyre; Ronald K.
Fan; Guojiang |
Salt Lake City
Orem
Lehi |
UT
UT
UT |
US
US
US |
|
|
Family ID: |
50772291 |
Appl. No.: |
14/088935 |
Filed: |
November 25, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61730305 |
Nov 27, 2012 |
|
|
|
Current U.S.
Class: |
175/428 ; 51/307;
51/309 |
Current CPC
Class: |
B24D 3/06 20130101; B24D
18/0009 20130101; B24D 3/10 20130101 |
Class at
Publication: |
175/428 ; 51/307;
51/309 |
International
Class: |
E21B 10/567 20060101
E21B010/567; B24D 3/10 20060101 B24D003/10; B24D 18/00 20060101
B24D018/00 |
Claims
1. A method of making a polycrystalline diamond cutting element,
comprising: placing a body of polycrystalline diamond comprising a
matrix phase of bonded together diamond grains and a plurality of
empty interstitial spaces between the bonded together diamond
grains adjacent a first substrate material to form an assembly; and
subjecting the assembly to high pressure/high temperature
conditions that include an initial pressure ramping, a pressure
hold, and a second pressure ramping.
2. The method of claim 1, further comprising: placing a plurality
of diamond particles adjacent a second substrate material
comprising a catalyst material; subjecting the plurality of diamond
particles and the second substrate material to second high
temperature/high pressure conditions to form a polycrystalline
diamond body comprising a matrix phase of bonded together diamond
grains and a plurality of interstitial spaces between the bonded
together diamond grains occupied by the catalyst material bonded to
the second substrate material; removing the second substrate
material from the polycrystalline diamond body; and removing
substantially all of the catalyst material from the interstitial
spaces of the polycrystalline diamond body.
3. The method of claim 1, wherein the high pressure/high
temperature conditions include an initial temperature ramping, a
temperature hold, and a second temperature ramping.
4. The method of claim 1, wherein the high pressure/high
temperature conditions include a monotonic increase in temperature
through the initial pressure ramping, the pressure hold, and the
second pressure ramping.
5. The method of claim 1, wherein the high pressure/high
temperature conditions include an initial temperature ramping
during the initial pressure ramping and a temperature hold through
the pressure hold and second pressure ramping.
6. The method of claim 1, wherein the high pressure/high
temperature conditions further include a second pressure hold
following the second pressure ramping.
7. The method of claim 6, wherein the second pressure hold is
longer than the first pressure hold.
8. The method of claim 1, wherein the first pressure ramping is at
a greater ramp rate than the second pressure ramping.
9. The method of claim 1, wherein the first pressure ranges from
about 50 to 70 kbar.
10. The method of claim 1, wherein the second pressure ranges from
70 to 82 kbar.
11. The method of claim 1, wherein the first substrate material
comprises a plurality of carbide particles bonded together by a
infiltrant material.
12. The method of claim 11, wherein during the subjecting step, the
infiltrant material infiltrates into at least some of the empty
interstitial spaces.
13. The method of claim 12, further comprising: removing at least a
portion of the infiltrant materials from the interstitial
spaces.
14. A method of forming a polycrystalline ultra-hard material,
comprising: placing a volume of ultra-hard material adjacent to a
substrate material comprising a Group VIII-containing material to
form an assembly; subjecting the assembly to a first high
pressure/high temperature condition sufficient to cause the Group
VIII-containing material to melt and partially infiltrate the
volume of ultra-hard material; and subjecting the combination to a
second high pressure/high temperature condition sufficient to cause
the Group VIII-containing material to further infiltrate the volume
of ultra-hard material, the pressure of the second high
pressure/high temperature condition is higher than that of the
first high pressure/high temperature condition.
15. The method of claim 14, wherein the volume of ultra-hard
material comprises a body of polycrystalline diamond comprising a
matrix phase of bonded together diamond grains and a plurality of
empty interstitial spaces between the bonded together diamond
grains.
16. The method of claim 14, wherein the first high pressure/high
temperature condition has a temperature maximum that is
substantially the same as the second high pressure/high temperature
condition.
17. The method of claim 14, further comprising: holding the first
high pressure/high temperature condition for a period of time prior
to ramping to the second high pressure/high temperature
condition.
18. The method of claim 14, wherein the volume of ultra-hard
material comprises a mass of diamond particles.
19. The method of claim 14, further comprising: placing a plurality
of ultra-hard particles adjacent a second substrate material
comprising a catalyst material; subjecting the plurality of
ultra-hard particles and the second substrate material to second
high temperature/high pressure conditions to form the ultrahard
material comprising a matrix phase of bonded together ultra-hard
particle grains and a plurality of interstitial spaces between the
bonded together ultra-hard particle grains occupied by the catalyst
material bonded to the second substrate material; removing the
second substrate material from the polycrystalline diamond body;
and removing substantially all of the catalyst material from the
interstitial spaces of the ultra-hard material.
20. A polycrystalline diamond compact, comprising: a
polycrystalline diamond body comprising a matrix phase of bonded
together diamond grains and a plurality of interstitial spaces
between the bonded together diamond grains, the polycrystalline
diamond body being substantially free of eruptions; and a substrate
attached to the polycrystalline diamond body at an interface, the
polycrystalline diamond body comprising at least two regions, a
first region adjacent the interface and a second region opposite
the interface, the first region of the polycrystalline diamond body
comprising an infiltrant material disposed within the interstitial
spaces and being substantially free of a catalyst material used to
form the polycrystalline diamond body, and the interstitial spaces
in the second region of the polycrystalline diamond body being
substantially free of the infiltrant material and the catalyst
material used to form the polycrystalline diamond body.
21. A cutting tool, comprising: at least one polycrystalline
diamond compact of claim 20 disposed thereon.
Description
CROSS-REFERENCE OF RELATED APPLICATIONS
[0001] Pursuant to 35 U.S.C. .sctn.119, this application claims the
benefit of U.S. Provisional Patent Application No. 61/730,305,
filed on Nov. 27, 2012, which is herein incorporated by reference
in its entirety.
BACKGROUND
[0002] Polycrystalline diamond ("PCD") materials and PCD elements
formed therefrom are well known in the art. Conventional PCD may be
formed by subjecting diamond particles in the presence of a
suitable solvent metal catalyst material to processing conditions
of high pressure/high temperature (HPHT), where the solvent metal
catalyst promotes desired intercrystalline diamond-to-diamond
bonding between the particles, thereby forming a PCD structure. The
resulting PCD structure produces enhanced properties of wear
resistance and hardness, making such PCD materials extremely useful
in aggressive wear and cutting applications where high levels of
wear resistance and hardness are desired. FIG. 1 illustrates a
microstructure of conventionally formed PCD material 10 including a
plurality of diamond grains 12 that are bonded to one another to
form an intercrystalline diamond matrix first phase. The
catalyst/binder material 14, e.g., cobalt, used to facilitate the
diamond-to-diamond bonding that develops during the sintering
process is dispersed within the interstitial regions formed between
the diamond matrix first phase. The term "particle" refers to the
powder employed prior to sintering a superabrasive material, while
the term "grain" refers to discernable superabrasive regions
subsequent to sintering, as known and as determined in the art.
[0003] The catalyst/binder material used to facilitate
diamond-to-diamond bonding can be provided generally in two ways.
The catalyst/binder can be provided in the form of a raw material
powder that is pre-mixed with the diamond grains or grit prior to
sintering. In some cases, the catalyst/binder can be provided by
infiltration into the diamond material (during high
temperature/high pressure processing) from an underlying substrate
material that the final PCD material is to be bonded to. After the
catalyst/binder material has facilitated the diamond-to-diamond
bonding, the catalyst/binder material is generally distributed
throughout the diamond matrix within interstitial regions formed
between the bonded diamond grains. Particularly, as shown in FIG.
1, the binder material 14 is not continuous throughout the
microstructure in the conventional PCD material 10. Rather, the
microstructure of the conventional PCD material 10 may have a
uniform distribution of binder among the PCD grains. Thus, crack
propagation through conventional PCD material will often travel
through the less ductile and brittle diamond grains, either
transgranularly through diamond grain/binder interfaces 15, or
intergranularly through the diamond grain/diamond grain interfaces
16.
[0004] Solvent catalyst materials may facilitate diamond
intercrystalline bonding and bonding of PCD layers to each other
and to an underlying substrate. Solvent catalyst materials used for
forming conventional PCD include metals from Group VIII of the
Periodic table, such as cobalt, iron, or nickel and/or mixtures or
alloys thereof, with cobalt being the most common. Conventional PCD
may include from 85 to 95% by volume diamond and a remaining amount
of the solvent catalyst material. However, while higher metal
content increases the toughness of the resulting PCD material,
higher metal content also decreases the PCD material hardness, thus
limiting the flexibility of being able to provide PCD layers having
desired levels of both hardness and toughness. Additionally, when
variables are selected to increase the hardness of the PCD
material, brittleness also increases, thereby reducing the
toughness of the PCD material.
[0005] PCD is commonly used in earthen drilling operations, for
example in cutting elements used on various types of drill bits.
Although PCD is extremely hard and wear resistant, PCD cutting
elements may still fail during normal operation. Failure may occur
in three common forms, namely wear, fatigue, and impact cracking.
The wear mechanism occurs due to the relative sliding of the PCD
relative to the earth formation, and its prominence as a failure
mode is related to the abrasiveness of the formation, as well as
other factors such as formation hardness or strength, and the
amount of relative sliding involved during contact with the
formation. Excessively high contact stresses and high temperatures,
along with a very hostile downhole environment, also tend to cause
severe wear to the diamond layer. The fatigue mechanism (including
both thermal and/or mechanical fatigue) involves the progressive
propagation of a surface crack, initiated on the PCD layer, into
the material below the PCD layer until the crack length is
sufficient for spalling or chipping. Lastly, the impact mechanism
involves the sudden propagation of a surface crack or internal flaw
initiated on the PCD layer, into the material below the PCD layer
until the crack length is sufficient for spalling, chipping, or
catastrophic failure of the cutting element.
SUMMARY
[0006] This summary is provided to introduce a selection of
concepts that are further described below in the detailed
description. This summary is not intended to identify key or
essential features of the claimed subject matter, nor is it
intended to be used as an aid in limiting the scope of the claimed
subject matter.
[0007] In one aspect, embodiments disclosed herein relate to a
method of making a polycrystalline diamond cutting element that
includes placing a body of polycrystalline diamond including a
matrix phase of bonded together diamond grains and a plurality of
empty interstitial spaces between the bonded together diamond
grains adjacent a first substrate material to form an assembly and
subjecting the assembly to high pressure/high temperature
conditions that include an initial pressure ramping, a pressure
hold, and a second pressure ramping.
[0008] In another aspect, embodiments disclosed herein relate to a
method of forming a polycrystalline ultra-hard material that
includes placing a volume of ultra-hard material adjacent to a
substrate material including a Group VIII-containing material to
form an assembly, subjecting the assembly to a first high
pressure/high temperature condition sufficient to cause the Group
VIII-containing material to melt and partially infiltrate the
volume of ultra-hard material, and subjecting the combination to a
second high pressure/high temperature condition sufficient to cause
the Group VIII-containing material to further infiltrate the volume
of ultra-hard material, where the pressure of the second high
pressure/high temperature condition is higher than that of the
first high pressure/high temperature condition.
[0009] In yet another aspect, embodiments disclosed herein relate
to a polycrystalline diamond compact that includes a
polycrystalline diamond body including a matrix phase of bonded
together diamond grains and a plurality of interstitial spaces
between the bonded together diamond grains, where the
polycrystalline diamond body is substantially free of eruptions,
and a substrate attached to the polycrystalline diamond body at an
interface, where the polycrystalline diamond body has at least two
regions, a first region adjacent the interface and a second region
opposite the interface, where the first region of the
polycrystalline diamond body has an infiltrant material disposed
within the interstitial spaces and being substantially free of a
catalyst material used to form the polycrystalline diamond body,
and where the interstitial spaces in the second region of the
polycrystalline diamond body are substantially free of the
infiltrant material and the catalyst material used to form the
polycrystalline diamond body.
[0010] Other aspects and advantages of the claimed subject matter
will be apparent from the following description and the appended
claims.
BRIEF DESCRIPTION OF DRAWINGS
[0011] Embodiments of the present disclosure are described with
reference to the following figures. The same numbers are used
throughout the figures to reference like features and
components.
[0012] FIG. 1 shows the microstructure of conventionally formed
polycrystalline diamond.
[0013] FIG. 2 is a picture of a reinfiltrated PCD diamond table
after removing the metal matrix.
[0014] FIG. 3 is a picture of a reinfiltrated PCD diamond table,
after removing the metal matrix, formed according to embodiments of
the present disclosure.
[0015] FIGS. 4.1-4.3 shows a schematic of formation of a cutting
element in accordance with the present disclosure.
[0016] FIG. 5 shows a fixed cutter drill bit.
[0017] FIG. 6 shows a hole opener.
[0018] FIG. 7 shows is a cross-sectional view of a conventionally
formed reinfiltrated diamond compact.
DETAILED DESCRIPTION
[0019] In one aspect, embodiments disclosed herein relate to use of
multiple pressure stages during the formation of a polycrystalline
diamond compact cutter, and the polycrystalline diamond compact
cutters formed by such processing.
[0020] Polycrystalline ultra-hard materials, and compacts formed
therefrom, are specifically engineered having a polycrystalline
ultra-hard material body having a material microstructure that is
substantially free of substrate material eruptions, e.g., catalyst
or infiltrant material eruptions, and thereby free of localized
concentrations, regions or volumes of the catalyst or infiltrant
material therein, and substantially free of any other substrate
constituent material. As used herein, "eruptions" refer to
precipitated regions of carbide grains and binder pools (catalyst
or infiltrant material) formed from the substrate material, which
may create inclusions that are substantially larger than the
interstitial regions formed in a polycrystalline diamond body.
Eruptions created by binder pools may leave voids within the
material microstructure once the binder is removed. In other words,
pores may not be present in the reinfiltrated polycrystalline
diamond body until the binder pools are removed. Thus, "eruptions"
may refer to inclusions or collections of precipitated material
different from the remaining polycrystalline diamond
microstructure, while "pores" refer to the voids left in the
polycrystalline diamond microstructure after removal of the
inclusions. As used herein, the eruptions may be at least an order
of magnitude larger than conventional interstitial regions.
Eruptions may occur during HPHT bonding methods of attaching a
diamond body to a substrate without pressure control, where the
eruptions precipitate from the substrate into the diamond body.
[0021] For example, FIG. 7 shows an example of a diamond compact
400 formed by HPHT bonding of a preformed diamond body 410 to a
tungsten carbide substrate 420 without using the pressure stages
described herein. During the HPHT step, eruptions 430 of tungsten
carbide and cobalt precipitated from the substrate 420 into the
diamond body 410 in a branched pattern. Eruptions 430 occurring
from the HPHT bonding process of attaching a diamond body 410 to a
tungsten carbide substrate 420 are distinct from substrate material
that may infiltrate into the diamond body 410 during the HPHT
bonding process to form the metallic bonds. For example, as
described above, eruptions 430 may be made of precipitated tungsten
carbide and cobalt, which has a tree-like or dendrite form
extending into the diamond body, and which may have a substantially
larger size than the infiltrated materials residing in interstitial
spaces between diamond grains bonded together. During the HPHT
bonding process, substrate material may also infiltrate into the
diamond body. Infiltration occurs when the temperature of the HPHT
bonding process reaches the melting temperature of the substrate
material. For example, when the HPHT bonding process temperature
reaches the melting point of cobalt, the cobalt from the tungsten
carbide substrate may melt and infiltrate into the diamond body,
thereby filling at least a portion of the empty interstitial
regions. Further, prior to attachment to the substrate, the diamond
body 410 may include bonded together diamond grains and
substantially empty interstitial regions between the bonded
together diamond grains. After the HPHT bonding process, the
diamond body 410 may have an amount of infiltrated cobalt disposed
within the interstitial regions. Further, the present disclosure
also relates to the use of a two-stage pressure profile during HPHT
sintering and formation of polycrystalline diamond to result in a
more uniform polycrystalline diamond microcrystalline
structure.
[0022] Eruptions may have a distinct form and composition from the
remaining diamond microstructure and may also produce a non-uniform
substrate microstructure. Thus, in accordance with the present
disclosure, the catalyst or infiltrant material in such
polycrystalline ultra-hard material body is instead evenly
dispersed throughout the material microstructure, or throughout at
least a region of material microstructure for those embodiments
where the catalyst or infiltrant material has been removed
therefrom. In an example embodiment, such polycrystalline
ultra-hard materials and compacts are formed by controlling the
HPHT process used to sinter the polycrystalline ultra-hard
material, to regulate the manner in which the catalyst or
infiltrant material melts and is infiltrated into the adjacent
ultra-hard material before and during the sintering process.
[0023] For example, FIG. 2 shows an example of a conventional
pre-formed diamond table 200 that had been reinfiltrated with
cobalt by HPHT processing without using a two-stage pressure
profile. The diamond table 200 has a plurality of pores 210 formed
therein. Particularly, eruptions of a metal matrix precipitated
from a substrate into the diamond table 200 during processing, and
when the metal matrix material was subsequently removed, the pores
210 were left in the diamond table 200. In other words, the pores
210 in the diamond table 200 are not formed until the metal matrix
is removed, such as by leaching. In contrast, FIG. 3 shows a
diamond table 300 formed according to methods of the present
disclosure, where the preformed diamond table 300 had been attached
to a substrate (not shown) by HPHT bonding using a two-stage
pressure. As shown, the diamond table 300 has a substantially
continuous microstructure, where substantially no eruptions have
been formed by the reinfiltration of cobalt.
[0024] Further, eruptions may create a non-uniform microstructure
in the polycrystalline diamond. Particularly, eruptions formed
using conventional methods of attaching a tungsten carbide
substrate to a diamond body may include precipitated tungsten
carbide grains and cobalt pools extending into the diamond body in
a tree-shaped or branched pattern. Thus, the attached
polycrystalline diamond body may have a microstructure including a
plurality of bonded together diamond grains, a plurality of
interstitial regions disposed among the bonded together diamond
grains, and extensions of precipitated tungsten carbide grains and
cobalt pools extending from the interface between the tungsten
carbide substrate and diamond body a distance into the diamond body
and through the bonded together diamond grains and interstitial
regions. However, constructions formed according to methods of the
present disclosure may have an attached diamond body that is
substantially free of eruptions. In other words, the attached
diamond body may have a substantially uniform microstructure
including a plurality of bonded together diamond grains and a
plurality of interstitial regions disposed among the bonded
together diamond grains.
[0025] Aspects of the present disclosure involve the use of an HPHT
profile that is controlled to minimize or reduce the number of
eruptions of the substrate materials into the diamond body. The
controlled HPHT process may involve a process used in the initial
formation of a polycrystalline diamond body on a substrate or/and
it may involve a subsequent HPHT process whereby a previously
formed polycrystalline diamond (PCD) body is attached to a
substrate.
[0026] As used herein, the term "PCD" refers to polycrystalline
diamond that has been formed, at high pressure/high temperature
(HPHT) conditions, through the use of a catalyst, such as solvent
metal catalysts from Group VIII of the Periodic table, non-metallic
catalysts including carbonates, as well as non-catalyst formed
polycrystalline diamond formed with even higher temperatures and
pressure than those used to form polycrystalline diamond with
cobalt.
[0027] In accordance with particular embodiments of the present
disclosure, the two-stage pressure profile of the HPHT process may
be particularly applicable for attaching previously formed diamond
bodies to a substrate in an HPHT process to reduce or avoid the
formation of eruptions within the diamond body. In such
embodiments, the diamond body attached to the substrate may be
previously treated to be rendered thermally stable so that the
diamond body is substantially free of the catalyst material used to
form the diamond body. When the diamond body is then attached to a
substrate in an HPHT process, the bond is formed by a continuous
metal bond. However, other embodiments of the present disclosure
also relate to the use of a two-stage pressure profile in the HPHT
process used to form the polycrystalline diamond
microstructure.
[0028] Forming Polycrystalline Diamond
[0029] A polycrystalline diamond body may be formed in a
conventional manner, such as by a high pressure, high temperature
sintering of "green" particles to create intercrystalline bonding
between the particles. "Sintering" may involve a high pressure,
high temperature (HPHT) process. Examples of high pressure, high
temperature (HPHT) process can be found, for example, in U.S. Pat.
Nos. 4,694,918; 5,370,195; and 4,525,178. Briefly, to form the
polycrystalline diamond object, an unsintered mass of diamond
crystalline particles is placed within a metal enclosure of the
reaction cell of a HPHT apparatus. A suitable HPHT apparatus for
this process is described in U.S. Pat. Nos. 2,947,611; 2,941,241;
2,941,248; 3,609,818; 3,767,371; 4,289,503; 4,673,414; and
4,954,139. A metal catalyst, such as cobalt or other Group VIII
metals, may be included with the unsintered mass of crystalline
particles to promote intercrystalline diamond-to-diamond bonding.
The catalyst material may be provided in the form of powder and
mixed with the diamond grains, or may be infiltrated into the
diamond grains during HPHT sintering. For example, a minimum
temperature may be about 1200.degree. C. (2192.degree. F.) and a
minimum pressure may be about 35 kilobars. In some embodiments,
processing may be conducted at a pressure of at least 45 kbar and
1300.degree. C. (2372.degree. F.). Those of ordinary skill in the
art will appreciate that a variety of temperatures and pressures
may be used, and the scope of the present invention is not limited
to specifically referenced temperatures and pressures. Further, it
is also within the scope of the present disclosure that the
two-step pressure profile disclosed below may be used in the
polycrystalline diamond formation process.
[0030] Diamond grains useful for forming a polycrystalline diamond
body may include any type of diamond particle, including natural or
synthetic diamond powders having a wide range of grain sizes. For
example, such diamond powders may have an average grain size in the
range from submicrometer in size to 100 micrometers, and from 1 to
80 micrometers in other embodiments. Further, one skilled in the
art would appreciate that the diamond powder may include grains
having a mono- or multi-modal distribution.
[0031] Moreover, the diamond powder used to prepare the PCD body
may be synthetic diamond powder or natural diamond powder.
Synthetic diamond powder is known to include small amounts of
solvent metal catalyst material and other materials entrained
within the diamond crystals themselves. The diamond grain powder,
whether synthetic or natural, may be combined with or already
includes a desired amount of catalyst material to facilitate
desired intercrystalline diamond bonding during HPHT processing.
Suitable catalyst materials useful for forming the PCD body include
those solvent metals selected from the Group VIII of the Periodic
table, with cobalt (Co) being the most common, and mixtures or
alloys of two or more of these materials. In a particular
embodiment, the diamond grain powder and catalyst material mixture
may include 85 to 95% by volume diamond grain powder and the
remaining amount catalyst material. In other embodiments, the
diamond grain powder can be used without adding a solvent metal
catalyst in applications where the solvent metal catalyst can be
provided by infiltration during HPHT processing from the adjacent
substrate or adjacent other body to be bonded to the PCD body.
[0032] The diamond powder may be combined with the desired catalyst
material, and the reaction cell is then placed under processing
conditions sufficient to cause the intercrystalline bonding between
the diamond particles. In the event that the formation of a PCD
compact including a substrate bonded to the PCD body is desired, a
selected substrate is loaded into the container adjacent the
diamond powder mixture prior to HPHT processing. Additionally, in
the event that the PCD body is to be bonded to a substrate, and the
substrate includes a metal solvent catalyst, the metal solvent
catalyst used for catalyzing intercrystalline bonding of the
diamond may be provided by infiltration, in which case, a metal
solvent catalyst does not have to be mixed with the diamond powder
prior to HPHT processing.
[0033] In an example embodiment, the device is controlled so that
the container is subjected to a HPHT process including a pressure
in the range of from 40 to 70 kilobars and a temperature in the
range of from about 1320 to 1600.degree. C., for a sufficient
period of time. During this HPHT process, the catalyst material in
the mixture melts and infiltrates the diamond grain powder to
facilitate intercrystalline diamond bonding. During the formation
of such intercrystalline diamond bonding, the catalyst material may
migrate into the interstitial regions within the microstructure of
the so-formed PCD body that exists between the diamond bonded
grains. It should be noted that if too much additional non-diamond
material is present in the powdered mass of crystalline particles,
appreciable intercrystalline bonding is prevented during the
sintering process. Such a sintered material where appreciable
intercrystalline bonding has not occurred is not within the
definition of PCD. Following such formation of intercrystalline
bonding, a polycrystalline diamond body may be formed that has, in
one embodiment, at least about 80 percent by volume diamond, with
the remaining balance of the interstitial regions between the
diamond grains occupied by the catalyst material. In other
embodiments, such diamond content may include at least 85 percent
by volume of the formed diamond body, and at least 90 percent by
volume in yet another embodiment. However, one skilled in the art
would appreciate that other diamond densities (or gradients of
diamond densities) may be used in alternative embodiments. In
particular embodiments, the polycrystalline diamond bodies being
leached in accordance with the present disclosure include what is
frequently referred to in the art as "high density" polycrystalline
diamond, which refers to a diamond body having a diamond content of
at least 90 percent by volume. However, in other embodiments, the
high density polycrystalline diamond used in the method of the
present disclosure may have a density of at least 92 percent by
volume up to 97 percent by volume. One skilled in the art would
appreciate that conventionally, as diamond density increases, the
leaching time (and potential inability to effectively leach)
similarly increases.
[0034] Further, one skilled in the art would appreciate that,
frequently, a diamond layer is sintered to a carbide substrate by
placing the diamond particles on a preformed substrate in the
reaction cell and sintering. However the present disclosure is not
so limited. Rather, the polycrystalline diamond bodies treated in
accordance with the present disclosure may or may not be attached
to a substrate.
[0035] In a particular embodiment, the polycrystalline diamond body
is formed using solvent catalyst material provided as an infiltrant
from a substrate, for example, a WC--Co substrate, during the HPHT
process. In such embodiments where the polycrystalline diamond body
is formed with a substrate, it may be desirable to remove the
polycrystalline diamond portion from the substrate prior to
leaching so that leaching agents may contact the diamond body in an
unshielded manner, i.e., from each side of the diamond body without
substantial restriction.
[0036] In various embodiments, a formed PCD body having a catalyst
material in the interstitial spaces between bonded diamond grains
is subjected to a leaching process (before or after attachment to a
substrate), whereby the catalyst material is removed from the PCD
body. As used herein, the term "removed" refers to the reduced
presence of catalyst material in the PCD body, and is understood to
mean that a substantial portion of the catalyst material no longer
resides in the PCD body. However, one skilled in the art would
appreciate that the leaching process is limited in that trace
amounts of catalyst material may still remain in the microstructure
of the PCD body within the interstitial regions and/or adhered to
the surface of the diamond grains. Such trace amounts may result
from limited access of leaching agents during the leaching process,
and because of this limited access, alternative methods may be used
to reduce the thermal coefficient differential between the
remaining catalyst material and diamond.
[0037] Rather than actually removing the catalyst material
remaining in the interstitial spaces and/or adhered to the surface
of the diamond grains from the PCD body or compact, the selected
region of the PCD body or compact can be rendered thermally stable
by treating the catalyst material in a manner that reduces or
prevents the potential for the catalyst material to adversely
impact the intercrystalline bonded diamond at elevated temperatures
due to the thermal mismatch between the diamond and the remaining
catalyst material as well as potential back conversion or
graphitization. For example, the catalyst material can be combined
chemically with another material or transformed into another
material, thus causing it to no longer act as a catalyst material.
Accordingly, as used herein, the terms "removing substantially all"
or "substantially free" as used in reference to the catalyst
material is intended to cover the different methods in which the
catalyst material can be treated to no longer adversely impact the
intercrystalline diamond in the PCD body or compact with increasing
temperature.
[0038] The quantity of the catalyst material remaining in the
material PCD microstructure after the PCD body has been subjected
to a leaching treatment may vary, for example, on factors such as
the treatment conditions, including treatment time, as well as
whether the PCD body is attached to the substrate body before or
after leaching. Further, one skilled in the art would appreciate
that it may be desired in certain applications to allow a small
amount of catalyst material to remain in the PCD body. In a
particular embodiment, the PCD body may include up to 1-2 percent
by weight of the catalyst material. However, one skilled in the art
would appreciate that the amount of residual catalyst present in a
leached PCD body may depend on the diamond density of the material
and body thickness.
[0039] A conventional leaching process involves the exposure of an
object to be leached with a leaching agent, such as described in
U.S. Pat. No. 4,224,380. In select embodiments, the leaching agent
may be a weak, strong, or mixtures of acids. In other embodiments,
the leaching agent may be a caustic material such as NaOH or KOH.
Suitable acids may include, for example, nitric acid, hydrofluoric
acid, hydrochloric acid, sulfuric acid, phosphoric acid, or
perchloric acid, or combinations of these acids. In addition,
caustics, such as sodium hydroxide and potassium hydroxide, have
been used to the carbide industry to digest metallic elements from
carbide composites. In addition, other acidic and basic leaching
agents may be used as desired. Those having ordinary skill in the
art will appreciate that the molarity of the leaching agent may be
adjusted depending on the time desired to leach, concerns about
hazards, etc.
[0040] Once the leaching step is completed and the PCD body is
removed from the leaching agent, the resulting material
microstructure of the leached portion of the diamond body may
include a first matrix phase of the bonded-together diamond grains
and a second phase of a plurality of empty interstitial regions
dispersed within the matrix phase. In other words, at the end of
the leaching process, the treated interstitial regions may be
substantially empty so that the second phase may be described as a
plurality of voids or empty regions dispersed throughout the
diamond-bonded matrix phase. Thus, the leached portion of the
diamond body may be substantially free of the catalyst material
used to initially form or sinter the diamond body, and may be
referred to as thermally stable polycrystalline diamond.
[0041] Reattachment
[0042] Preformed diamond bodies may be attached (or reattached) to
a substrate subjecting the polycrystalline diamond body and
substrate to the HPHT conditions disclosed herein, to facilitate
attachment to a bit, cutting tool, or other end use application or
device. Furthermore, methods of attaching (or reattaching) a
diamond layer to a substrate may result in the migration of an
infiltrant material, the source of which may be the substrate
and/or an optional intermediate material. In a particular
embodiment, the source of infiltrant material may be a substrate
that is attached to preformed diamond body during the HPHT
process.
[0043] As used herein, the term "infiltrant material" is understood
to refer to materials that are other than the catalyst material
used to initially form the diamond body, and may include materials
identified in Group VIII of the periodic table that have
subsequently been introduced into the already formed diamond body.
The type of infiltrant material is not a limitation on the scope of
the present disclosure. Additionally, the term "infiltrant
material" is not intended to be limiting on the particular method
or technique used to introduce such material into the already
formed diamond body. The infiltrant material may be selected from
the group of materials including metals, ceramics, cermets, or
combinations thereof. In an example embodiment, the infiltrant
material is a metal or metal alloy selected from Group VIII of the
Periodic Table, such as cobalt, nickel, iron or combinations
thereof. It is to be understood that the choice of material or
materials used as the infiltrant material can and will vary
depending on such factors including but not limited to the end-use
application, and the type and density of the diamond grains used to
form the polycrystalline diamond matrix first phase, and the
mechanical properties and/or thermal characteristics desired for
the polycrystalline diamond construction.
[0044] After forming a diamond body, the catalyst material residing
in the interstitial regions may be removed so that an infiltrant
material may take its place in the interstitial regions. That is,
once the catalyst material used to initially form the diamond body
is removed from the diamond body, the remaining microstructure
includes a polycrystalline matrix phase with a plurality of
interstitial voids forming what is essentially a porous material
microstructure.
[0045] The voids or pores in the polycrystalline diamond body may
be filled with the infiltrant material using a number of different
techniques. Further, voids throughout the diamond body or voids
throughout a portion of the diamond body may be filled with the
replacement material. In an example embodiment, the infiltrant
material may be introduced into the diamond body by liquid-phase
sintering under HPHT conditions. In such example embodiment, the
infiltrant material may be provided in the form of a sintered part
or a green-state part that contains the infiltrant material and
that is positioned adjacent one or more surfaces of the diamond
body. The assembly is placed into a container that is subjected to
HPHT conditions sufficient to melt the infiltrant material within
the sintered part or green-state part and cause it to infiltrate
into the diamond body. In an example embodiment, the source of the
infiltrant material may be a substrate that will be used to form a
compact from the polycrystalline diamond construction by attachment
to the diamond body during the HPHT process.
[0046] The term "filled", as used herein to refer to the presence
of the infiltrant material in the voids or pores of the diamond
body that resulted from removing the catalyst material used to form
the diamond body therefrom, is understood to mean that a
substantial volume of such voids or pores contain the infiltrant
material. However, it is to be understood that there may also be a
volume of voids or pores within the same region of the diamond body
that do not contain the infiltrant material, and that the extent to
which the infiltrant material effectively displaces the empty voids
or pores will depend on such factors as the particular
microstructure of the diamond body, the effectiveness of the
process used for introducing the infiltrant material, and the
desired mechanical and/or thermal properties of the resulting
polycrystalline diamond construction. In some embodiments, when
introduced into the diamond body, the infiltrant fills
substantially all of the voids or pores throughout the diamond
body. In some embodiments, complete migration of the infiltrant
material through the diamond body is not realized, in which case a
region of the diamond body may not include the infiltrant material.
This region devoid of the infiltrant material from such incomplete
migration may extend from the region including the infiltrant to a
surface portion of the diamond body, such as a cutting surface of
the diamond body.
[0047] In an example embodiment, a substrate is used as the source
of the infiltrant material and to form the polycrystalline
construction. Substrates useful in this regard may include
substrates that are used to form conventional PCD, e.g., those
formed from metals, ceramics, and/or cermet materials that contain
a desired infiltrant. In an example embodiment, the substrate is
formed from WC--Co, and is positioned adjacent the diamond body
after the metal catalyst material used to initially form the same
been removed, and the assembly is subjected to HPHT conditions
sufficient to cause the cobalt in the substrate to melt and
infiltrate into and fill the voids or pores in the polycrystalline
diamond matrix.
[0048] Once the diamond body has been filled with the infiltrant
material, it may then be treated to remove a portion of the
infiltrant material therefrom. In some embodiments, where the
infiltrant material did not migrate completely through the diamond
body, a subsequent infiltrant removal step may not be conducted, or
may useful as a clean up process to ensure a uniform infiltrant
removal depth. Treating the compact to remove such infiltrant
material may render the polycrystalline diamond body or compact
thermally stable by treating the infiltrant material in a manner
that reduces or prevents the potential for the infiltrant material
to adversely impact the intercrystalline bonded diamond at elevated
temperatures. Generally, infiltrant materials are problematic when
heat is generated at the cutter impact point of the compact.
Specifically, heat generated at the exposed part of the
polycrystalline diamond body, caused by friction between the
polycrystalline diamond and the work material, may result in
thermal damage to the polycrystalline diamond in the form of cracks
(due to differences in thermal expansion coefficients) which may
lead to spalling of the polycrystalline diamond layer, delamination
between the polycrystalline diamond and the substrate, and back
conversion of diamond to graphite causing rapid abrasive wear.
Thus, increased thermal stability may be achieved by treating the
compact to remove such infiltrant material using such methods as
leaching or other methods known in the art.
[0049] In an example embodiment, the infiltrant material is removed
from the diamond body a depth of less than about 0.7 mm from the
desired surface or surfaces, and in some embodiments, in the range
of from about 0.05 to 0.5 mm. Ultimately, the specific depth of the
region formed in the diamond body by removing the infiltrant
material will vary depending on the particular end-use
application.
[0050] In some embodiments, a detached polycrystalline diamond
layer may be treated to first remove the catalyst material
initially used to form the polycrystalline bonds in the
polycrystalline diamond layer. The resulting thermally stable
polycrystalline diamond body may then be attached to a substrate
using an HPHT process for a period of time and at a temperature
sufficient to meet the melting point of an infiltrant material
present in the substrate such that the infiltrant material migrates
to the polycrystalline diamond body. The resulting polycrystalline
diamond compact may then be treated to remove a portion of the
infiltrant material therefrom. Techniques useful for removing a
portion of the infiltrant material from the diamond compact include
the same techniques described above for removing the catalyst
material used to initially form the diamond compact from the
polycrystalline diamond body, e.g., such as by leaching or the
like. Depending on the application, it may be desired that the
process of removing the infiltrant material be controlled so that
the infiltrant material be removed from a targeted region of the
diamond compact extending a determined depth from one or more
diamond compact surfaces. These surfaces may include working and/or
nonworking surfaces of the diamond compact.
[0051] Referring now to FIGS. 4.1-4.3 collectively, an embodiment
of the process steps of the present disclosure is shown. As shown
in FIG. 4.1, a polycrystalline diamond body 30 having a catalyzing
material found in the interstitial regions between the diamond
grains (as described above) may be formed attached to a carbide
substrate 34. The polycrystalline diamond body 30 may be detached
(shown in FIG. 4.2) from the substrate 34 simultaneous with or
prior to removal of the catalyzing material from the interstitial
spaces. Further, as shown in FIG. 4.3, the diamond body 30 may then
be attached (or reattached) to a substrate 36 through sintering,
and in particular using multiple stages of elevated pressure.
[0052] Two Stage Pressure Profile
[0053] In accordance with embodiments of the present disclosure,
the HPHT process in which the diamond material (either preformed
body or mass of diamond particles) is attached to a substrate and
infiltrated with a catalyst or infiltrant material, may include a
two-stage pressure profile. The first stage may include elevated
temperatures (to temperatures sufficient to cause infiltration of
the catalyst or infiltrant material), and a first stage of pressure
ramping. However, after a short hold at the first stage of elevated
pressure, the pressure is further ramped to a predetermined second
stage pressure and held for the duration of the HPHT process. In
one or more embodiments, the second pressure hold may be longer
than the first pressure hold. Further, in one or more embodiments,
the first pressure ramping is at a greater ramp rate than the
second pressure ramping. Suitable ramp rates for the first pressure
ramping (of the internal cell pressure increase) may include rates
of 0.8 to 15 kbar/sec, and at least about 1, 2, 3, or 5 kbar/sec in
one or more embodiments, and no more than about 14, 13, 10, or 8
kbar/sec in one or more embodiments, where any lower limit may be
used in combination with any upper limit. Suitable ramp rates for
the second pressure ramping may include rates of may include rates
of 0.8 to 15 kbar/sec, and at least about 1, 1.2, 1.5, or 2
kbar/sec in one or more embodiments, and no more than about 6, 5,
4, or 3 kbar in one or more embodiments, where any lower limit may
be used in combination with any upper limit. As mentioned above,
these pressure ramp rates are the ramp rates for the internal cell
pressure experienced by the diamond body, etc., not the external
application of hydraulic pressure applied that will trigger
internal cell pressure increases. The correlation between the
hydraulic pressure applied and the internal cell pressure will vary
for each cell configuration, as understood by those of ordinary
skill in the art, and thus, because the internal cell pressure is
what effects the infiltration process as it is the pressure
experienced by the cell contents, it is the internal cell pressure
that is discussed herein.
[0054] Further, suitable hold periods for the first pressure hold
may range from about 20 seconds to up to 240 seconds, and may be
less than 120 seconds or 60 seconds in particular embodiments, and
suitable hold periods for the second pressure hold may range from
about 40 seconds up to 320 seconds, but may be less than 240
seconds or 180 seconds in particular embodiments. It is also within
the scope of the present disclosure that subsequent pressure stages
may be reached in further step-wise fashion.
[0055] The temperature reached during the two-stage HPHT process
may range, for example, from 1300 to 1600.degree. C., but also may
depend on the melting temperature of the infiltrant material
selected. The total pressure range for the two-stage HPHT process
may generally range from at least 40 kbar to 85 kbar, where the
first pressure stage may range from 50 kbar to 65 kbar in one or
more embodiments, (e.g., 57 kbar), and the second pressure stage
may range from 60 kbar to 82 kbar in one or more embodiments. In
one or more embodiments, the first pressure stage may have a lower
limit of any of 40, 45, 50, 55, or 60 kbar, and an upper limit of
any of 50, 55, 60, 65, or 68 kbar, where any lower limit can be
used in combination with any upper limit. Further, in one or more
embodiments, the second pressure stage may have a lower limit of
any of 55, 60, 65, or 70 kbar, and an upper limit of any of 60, 65,
70, 75, 80, or 82 kbar, where any lower limit can be used in
combination with any upper limit.
[0056] Further, like the ramp-hold-ramp pattern in the pressure
increase, the HPHT conditions may also include an initial
temperature ramping, a temperature hold, and a second temperature
ramping, in one embodiment. In another embodiment, the high
pressure/high temperature conditions may include a monotonic
increase in temperature through the initial pressure ramping, the
pressure hold, and the second pressure ramping. In yet another
embodiment, the high pressure/high temperature conditions may
include an initial temperature ramping during the initial pressure
ramping and a temperature hold through the pressure hold and second
pressure ramping. In one or more embodiments, a substantial
majority of the temperature increase may occur during the first
pressure ramping, where the second stage observes a temperature
increase of less than 100 degrees, less than 75 degrees, less than
50 degrees, less than 25 degrees, or less than 20 degrees
Celsius.
[0057] The cutting elements of the present disclosure may be
incorporated in various types of cutting tools, including for
example, as cutters in fixed cutter bits or on borehole enlargement
tools such as reamers. Thus, the structure on which the cutting
elements of the present disclosure may be installed may be referred
to as a cutting element support structure, i.e., a blade for fixed
cutter bit or a reamer.
[0058] Referring now to FIG. 5, an embodiment of a fixed cutter
drill bit 100 is shown. As shown in FIG. 5, drill bit 100 includes
a bit body 110 having a threaded upper pin end 111 and a cutter
face 112. The cutter face 112 may include a plurality of ribs or
blades 120 arranged about the rotational axis L of the drill bit
and extending radially outward from the bit body 110. Cutting
elements, or cutters, 150 are embedded in the blades 120 at
predetermined angular orientations and radial locations relative to
a working surface and with a desired back rake angle and side rake
angle against a formation to be drilled. Cutters 150 are
conventionally attached to a drill bit or other downhole tool by a
brazing process so that the ultra hard cutting table faces into the
direction of rotation of the bit. In the brazing process, a braze
material is positioned between the cutter substrate and the cutter
pocket. The material is melted and, upon subsequent solidification,
bonds (attaches) the cutter in the cutter pocket.
[0059] A plurality of orifices 116 are positioned on the bit body
110 in the areas between the blades 120, which may be referred to
as "gaps" or "fluid courses." The orifices 160 are commonly adapted
to accept nozzles. The orifices 160 allow drilling fluid to be
discharged through the bit in selected directions and at selected
rates of flow between the blades 120 for lubricating and cooling
the drill bit 100, the blades 120 and the cutters 150. The drilling
fluid also cleans and removes the cuttings as the drill bit 100
rotates and penetrates the geological formation. Without proper
flow characteristics, insufficient cooling of the cutters 150 may
result in cutter failure during drilling operations. The fluid
courses are positioned to provide additional flow channels for
drilling fluid and to provide a passage for formation cuttings to
travel past the drill bit 100 toward the surface of a wellbore (not
shown).
[0060] FIG. 6 shows a general configuration of a hole opener 830
that includes one or more cutting elements of the present
disclosure. The hole opener 830 includes a tool body 832 and a
plurality of blades 838 disposed at selected azimuthal locations
about a circumference thereof. The hole opener 830 generally
includes connections 834, 836 (e.g., threaded connections) so that
the hole opener 830 may be coupled to adjacent drilling tools that
include, for example, a drillstring and/or bottom hole assembly
(BHA) (not shown). The tool body 832 generally includes a bore
therethrough so that drilling fluid may flow through the hole
opener 830 as it is pumped from the surface (e.g., from surface mud
pumps (not shown)) to a bottom of the wellbore (not shown). The
tool body 832 may be formed from steel or from other materials
known in the art. For example, the tool body 832 may also be formed
from a matrix material infiltrated with a binder alloy.
[0061] The blades 838 shown in FIG. 6 are spiral blades and are
generally positioned at substantially equal angular intervals about
the perimeter of the tool body so that the hole opener 830. This
arrangement is not a limitation on the scope of the invention, but
rather is used merely to illustrative purposes. Those having
ordinary skill in the art will recognize that any downhole cutting
tool may be used.
[0062] Although only a few example embodiments have been described
in detail above, those skilled in the art will readily appreciate
that many modifications are possible in the example embodiments
without materially departing from this invention. Accordingly, all
such modifications are intended to be included within the scope of
this disclosure as defined in the following claims. In the claims,
means-plus-function clauses are intended to cover the structures
described herein as performing the recited function and not only
structural equivalents, but also equivalent structures. Thus,
although a nail and a screw may not be structural equivalents in
that a nail employs a cylindrical surface to secure wooden parts
together, whereas a screw employs a helical surface, in the
environment of fastening wooden parts, a nail and a screw may be
equivalent structures. It is the express intention of the applicant
not to invoke 35 U.S.C. .sctn.112, paragraph 6 for any limitations
of any of the claims herein, except for those in which the claim
expressly uses the words `means for` together with an associated
function.
* * * * *