U.S. patent application number 16/741444 was filed with the patent office on 2020-05-14 for polycrystalline diamond cutting element.
This patent application is currently assigned to National Oilwell DHT, L.P.. The applicant listed for this patent is National Oilwell DHT, L.P.. Invention is credited to Mark Jonathan Francis, Russell C. Gilleylen, Michael D. Hughes, Deepthi Raj Setlur, Harold A. Sreshta, JiinJen Albert Sue, Guodong Zhan.
Application Number | 20200149353 16/741444 |
Document ID | / |
Family ID | 45972014 |
Filed Date | 2020-05-14 |
United States Patent
Application |
20200149353 |
Kind Code |
A1 |
Setlur; Deepthi Raj ; et
al. |
May 14, 2020 |
Polycrystalline Diamond Cutting Element
Abstract
A polycrystalline-diamond cutting element for a drill bit of a
downhole tool. The cutting element includes a substrate and a
diamond table bonded to the substrate. The diamond table includes a
diamond filler with at least one leached polycrystalline diamond
segment packed therein along at least one working surface thereof.
The cutting element may be formed by positioning the diamond table
on the substrate and bonding the diamond table onto the substrate
such that the polycrystalline diamond segment is positioned along
at least one working surface of the diamond table. A spark plasma
sintering or double press operation may be used to bond the diamond
table onto the substrate.
Inventors: |
Setlur; Deepthi Raj;
(Cypress, TX) ; Hughes; Michael D.; (Conroe,
TX) ; Francis; Mark Jonathan; (Randwick, GB) ;
Sreshta; Harold A.; (Conroe, TX) ; Zhan; Guodong;
(Spring, TX) ; Gilleylen; Russell C.; (Spring,
TX) ; Sue; JiinJen Albert; (The Woodlands,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
National Oilwell DHT, L.P. |
Conroe |
TX |
US |
|
|
Assignee: |
National Oilwell DHT, L.P.
Conroe
TX
|
Family ID: |
45972014 |
Appl. No.: |
16/741444 |
Filed: |
January 13, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14553849 |
Nov 25, 2014 |
10570667 |
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16741444 |
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13279553 |
Oct 24, 2011 |
8919463 |
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14553849 |
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61406273 |
Oct 25, 2010 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B22F 3/105 20130101;
Y10T 428/12174 20150115; B24D 18/0009 20130101; Y10T 428/12576
20150115; B22F 7/02 20130101; E21B 10/573 20130101; B22F 3/16
20130101; C22C 19/07 20130101; E21B 10/567 20130101 |
International
Class: |
E21B 10/567 20060101
E21B010/567; E21B 10/573 20060101 E21B010/573; B24D 18/00 20060101
B24D018/00; C22C 19/07 20060101 C22C019/07; B22F 7/02 20060101
B22F007/02; B22F 3/16 20060101 B22F003/16 |
Claims
1. A polycrystalline-diamond cutting element for a drill bit of a
downhole tool, comprising: a substrate; and a diamond table bonded
to the substrate, the diamond table comprising a polycrystalline
diamond material intermixed with small polycrystalline diamond
particles that are substantially free of all catalyzing and other
metallic material along at least one working surface thereof;
wherein the small polycrystalline diamond particles comprise small
particles formed from a polycrystalline diamond blank with a
metallic catalyst therein that has been subjected to a first high
temperature-high pressure pressing operation, leached of
substantially all of the other metallic materials, and intermixed
with the polycrystalline diamond material; and wherein the diamond
table is subjected to a second high temperature-high pressure
pressing operation.
2. The polycrystalline diamond cutting element of claim 1, wherein
the small polycrystalline diamond particles are formed by sintering
and crushing the polycrystalline blank and sizing the crushed
polycrystalline blank into the small particles.
3. Polycrystalline diamond cutting element of claim 2, wherein the
polycrystalline diamond cutting element has a higher wear
resistance than a polycrystalline diamond cutting element
comprising a diamond table comprising no material that has been
sintered prior to formation of the diamond table.
4. The polycrystalline diamond cutting element of claim 1, wherein
the small polycrystalline diamond particles are leached particles
that have been leached before the small particles are formed from
the polycrystalline diamond blank.
5. The polycrystalline diamond cutting element of claim 1, wherein
the small particles are leached after they are formed from the
polycrystalline diamond blank.
6. The polycrystalline diamond cutting element of claim 1, wherein
the small particles have selected sizes and shapes.
7. The polycrystalline diamond cutting element of claim 1, wherein
the substrate comprises tungsten carbide, cobalt,
nickel-nano-tungsten carbide and combinations thereof.
8. The polycrystalline diamond cutting element of claim 1, wherein
the diamond material comprises diamond feedstock, diamond powder
and combinations thereof.
9. The polycrystalline diamond cutting element of claim 1, wherein
the plurality of small leached polycrystalline diamond particles
are positioned along at least one of a top and peripheral working
surface.
10. The polycrystalline diamond cutting element of claim 1, wherein
the first high temperature-high pressure pressing operations have a
temperature higher than 1300.degree. C. and a pressure greater than
65 KBar.
11. The polycrystalline diamond cutting element of claim 1, wherein
the first high temperature-high pressure pressing operations have a
temperature higher than 1300.degree. C. and a pressure greater than
65 KBar.
12. The polycrystalline diamond cutting element of claim 1, wherein
the second high temperature-high pressure pressing operations have
a temperature higher than 1300.degree. C. and a pressure greater
than 65 KBar.
13. The polycrystalline diamond cutting element of claim 1, further
comprising a carrier, the substrate bonded to the carrier.
14. The polycrystalline diamond cutting element of claim 1, wherein
the small polycrystalline diamond particles comprise small
particles of less than about 5 micron in size.
15. The polycrystalline diamond cutting element of claim 1, wherein
the small polycrystalline diamond particles are leached small
polycrystalline diamond particles substantially free of all
catalyzing and other metallic material due to leaching.
16. The polycrystalline diamond cutting element of claim 1, wherein
the at least one working surface comprises a top working surface, a
peripheral working surface, or both a top working surface and a
peripheral working surface of the diamond table.
17. The polycrystalline diamond cutting element of claim 1, wherein
the at least one working surface is a leached surface, as a result
of treating all or a portion of the at least one working surface in
a leaching process to remove all or select portions of any catalyst
that may have infiltrated during the bonding of the diamond table
onto the substrate.
18. The polycrystalline diamond cutting element of claim 1, wherein
the small, polycrystalline diamond particles comprise a grit, and
wherein the size, quantity, and/or layer thickness of the grit are
selected such that the polycrystalline diamond cutting element is
self-sharpening.
19. The polycrystalline diamond cutting element of claim 18,
wherein the small polycrystalline diamond particles comprise small
particles of about 0.5 micron in size.
20. The polycrystalline diamond cutting element of claim 1, wherein
the first high temperature-high pressure pressing operation and the
second high temperature-high pressure pressing operation comprise
the same conditions.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 14/553,849, filed Nov. 25, 2014, which is a divisional of U.S.
application Ser. No. 13/279,553 filed Oct. 24, 2011, and claims the
benefit of U.S. Provisional Patent Application No. 61/406,273,
filed on Oct. 25, 2010, the disclosure of each of which is hereby
incorporated by reference herein in its entirety for purposes not
contrary to this disclosure.
BACKGROUND
1. Field
[0002] Disclosed herein are elements of superhard polycrystalline
material synthesized in a high temperature, high-pressure process
and used for wear, cutting, drawing, and other applications. These
elements have specifically placed superhard surfaces at locations
where wear resistance may be required. In particular, disclosed
herein are polycrystalline diamond and polycrystalline diamond-like
(collectively called PC D) cutting elements with tailored wear and
impact toughness resistance and methods of manufacturing them. One
particular form of PCD cutting elements which may be used in drill
bits for drilling subterranean formations are called
polycrystalline diamond cutters (PDC's).
2. Description of the Related Art
[0003] U.S. Pat. No. 6,861,098 discloses methods for fabrication of
PCD cutting elements, inserts, and tools. Polycrystalline diamond
and polycrystalline diamond-like cutting elements are generally
known, for the purposes of this specification, as PCD cutting
elements. PCD cutting elements may be formed from carbon based
materials with short inter-atomic distances between neighboring
atoms. One type of polycrystalline diamond-like material known as
carbonitride (CN) is described in U.S. Pat. No. 5,776,615. Another,
form of PCD is described in more detail below. In general, PCD
cutting elements are formed from a mix of materials processed under
high-temperature and high-pressure (HTHP) into a polycrystalline
matrix of inter-bonded superhard carbon based crystals. A trait of
PCD cutting elements may be the use of catalyzing materials during
their formation, the residue from which may impose a limit upon the
maximum useful operating temperature of the PCD cutting element
while in service.
[0004] One manufactured form of PCD cutting element is a two-layer
or multi-layer PCD cutting element where a facing table of
polycrystalline diamond is integrally bonded to a substrate of less
hard material, such as cemented tungsten carbide. The PCD cutting
element may be in the form of a circular or part-circular tablet,
or may be formed into other shapes, suitable for applications such
as hollow dies, heat sinks, friction bearings, valve surfaces,
indenters, tool mandrels, etc. PCD cutting elements of this type
may be used in applications where a hard and abrasive wear and
erosion resistant material may be required. The substrate of the
PCD cutting element may be brazed to a carrier, which may also be
made of cemented tungsten carbide. This configuration may be used
for PCD's used as cutting elements, for example, in fixed cutter or
rolling cutter earth boring bits when received in a socket of the
drill bit, or when fixed to a post in a machine tool for machining.
PCD cutting elements that are used for this purpose may be called
polycrystalline diamond cutters (PDC's).
[0005] PCD cutting elements may be formed by sintering diamond
powder with a suitable binder-catalyzing material with a substrate
of less hard material in a high-pressure, high-temperature press.
One method of forming this polycrystalline diamond is disclosed,
for example, in U.S. Pat. No. 3,141,746, the entire contents of
which are hereby incorporated by reference. In one process for
manufacturing PCD cutting elements, diamond powder is applied to
the surface of a preformed tungsten carbide substrate incorporating
cobalt. The assembly may then be subjected to high temperatures and
pressures in a press. During this process, cobalt migrates from the
substrate into the diamond layer and acts as a binder-catalyzing
material, causing the diamond particles to bond to one another with
diamond-to-diamond bonding, and also causing the diamond layer to
bond to the substrate.
[0006] The completed PCD cutting element may have at least one
matrix of diamond crystals bonded to each other with many
interstices containing a binder-catalyzing material metal as
described above. The diamond crystals may form a first continuous
matrix of diamond, and the interstices may form a second continuous
matrix of interstices containing the binder-catalyzing material. In
addition, there may be some areas where the diamond to diamond
growth has encapsulated some of the binder-catalyzing material.
These "islands" may not be part of the continuous interstitial
matrix of binder-catalyzing material.
[0007] In one particular form, the diamond element may constitute
85% to 95% by volume of the PDC and the binder-catalyzing material
the other 5% to 15%. Although cobalt may be used as the
binder-catalyzing material, other group VIII elements, including
cobalt, nickel, iron, and alloys thereof, may be employed.
[0008] U.S. Pat. No. 7,407,012 describes the fabrication of a
highly impact resistant tool that has a sintered body of diamond or
diamond-like particles in a metal matrix bonded to cemented metal
carbide substrate at a non-planar interface. The catalyst for
enabling diamond-to-diamond sintering may be provided by the
substrate. The general manufacture of a PDC, insert, or cutting
tool may use a cemented carbide substrate to provide a catalyst to
aid in the sintering of the diamond particles.
[0009] Published US Patent Application US 2005/0044800, describes
the use of a meltable sealant barrier to cleanse the PCD cutting
element constituent assembly via vacuum thermal reduction followed
by melting the sealant to provide a hermetic seal in a can used for
the further high temperature, high pressure (HTHP) processing--with
a temperature which may be higher than 1300e and a pressure which
may be greater than 65 KBar. The sealing of the can may be required
to limit contamination of the diamond particle bed during HTHP
processing, and to also maintain a high vacuum in the can to limit
oxidation and other contamination. The HTHP can assemblies may help
to prevent contamination of the PCD cutting element table and may
also be sealed by using processes, such as EB welding, used for
standard production of cutters and inserts.
[0010] U.S. Pat. No. 6,045,440 describes a structured PDC that is
oriented for use in earth boring where formation chips and debris
are funneled away from the cutting edge via the use of raised top
surfaces on the PDC. The redirection of the debris may be achieved
by creation of high and low surfaces on the PDC cutting surface. A
method used to form the protrusion on the PDC is not described in
detail in this patent, the surface texture and geometry of this
cutter surface may be limited to the ability to extrude and/or form
sealing can surfaces that are a negative of the desired PDC front
face extrusions, or alternatively formed by post HTHP processing,
such as EDM and Laser cutting--as may be necessary to form the
surfaces on the cutter face.
SUMMARY
[0011] Described herein is a process for making PCD cutting
elements in a `double pressing` operation. This process may provide
PCD cutting elements with improvements in wear life over prior PCD
cutting elements. Previously, high temperature, high pressure
(HTHP) sintering of round discs into a PCD (polycrystalline
diamond) material (or segments) manufactured in a second HTHP press
cycle tended to result in cracking of the diamond material on the
face of the PDC due to the stresses developed during the forming
process.
[0012] The present `double pressed` HTHP sintered PDC disclosed
herein may have enhanced physical characteristics. The method for
making a double pressed HTHP sintered PDC uses a previously HTHP
pressed PCD material that may be leached or rendered free of all or
substantially all of the metallic material is provided. This PCD
material may then be crushed and sized to form a PCD grit that may
be layered or dispersed with other materials and then canned &
sintered into a final product PDC in a second HTHP pressing
operation.
[0013] In one preferred embodiment, these canned & sintered
PDC's made from previously pressed PCD cutting elements may be
formed into tiles or segments (rectangular or arc shaped) and then
may be leached (or substantially rendered free) of all metallic
material, laid out in single or multiple layers, packed with a
diamond filler (e.g., traditional diamond feedstock or diamond
powder), and then HTHP sintered a second time in the normal fashion
into a PDC of the present disclosure.
[0014] This method for making a double pressed HTHP sintered PDC
may begin by arranging segments of previously pressed PCD segments
that are leached (as described above) and laid out in a single
layer or multiple layers, packed with a diamond filler (e.g.,
traditional diamond feedstock), and then HTHP sintered in the
normal fashion into a PDC.
[0015] In another embodiment, other assorted shapes of previously
pressed PCD may be selected, designed, and/or configured for
advantageously arranging the stress fields within the PDC when in
operation. These previously pressed PCD cutting elements may be
leached or otherwise rendered free of metals and then may be
combined with various combinations of diamond grit, diamond
`chunks`, and/or shaped PCD segments and geometrically arranged in
a pattern optimized for performance and subjected to a second HTHP
cycle, cleaned up and made ready for use in earth-boring, or other
related operations known in the industry.
[0016] An alternative forming process for manufacturing a PDC in
accordance with the present disclosure may utilize a spark plasma
sintering process (SPS) in place of the second HTHP pressing cycle.
A forming process utilizing a spark plasma sintering process (SPS)
may also be provided as an additional or alternative process in PDC
manufacture. In this process, the powder materials may be stacked
between a die and punch on a sintering stage in a chamber and held
between a set of electrodes. When a pulse or a pulse stream is
provided under pressure, the temperature may rapidly rise to a
sintering temperature, say from about 1000 to about 2500.degree. C.
resulting in the production of a sintered PDC in only a few
minutes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is an illustrative view of a typical earth boring
drill rig in operation.
[0018] FIG. 2 is a PCD cutting element typical of those of the
present disclosure.
[0019] FIG. 3 is a drill bit which may utilize PCD cutting elements
of the present disclosure.
[0020] FIGS. 4 and 5 are perspective views of one embodiment of the
present disclosure using segmented pieces of leached PCD
material.
[0021] FIGS. 6 and 7 are perspectives views of individual blocks of
leached PCD material arranged in another embodiment of a PCD
cutting element of the present disclosure.
[0022] FIG. 8 is a perspectives view full disc of leached PCD
material in still another embodiment of a PCD cutting element of
the present disclosure.
[0023] FIG. 9 illustrates a spark sintering process which is an
alternate process for forming the PCD cutting element of the
present disclosure.
[0024] FIG. 10 depicts a flowchart describing a method of making a
PCD cutting element of the present disclosure.
DETAILED DESCRIPTION
[0025] In the following description, the sintered composite
described hereafter may be formed of polycrystalline diamond (or
PCD). However, this process may also be applicable to other super
hard abrasive materials, including, but not limited to, synthetic
or natural diamond, cubic boron nitride, and other related
materials.
[0026] Polycrystalline diamond cutters (PDC's) may be used as
cutting elements in drilling bits used to form boreholes into the
earth, and may be used for, but not limited to, drilling tools for
exploration and production of hydrocarbon minerals from the
earth.
[0027] For illustrative purposes only, a typical drilling operation
is shown in FIG. 1. FIG. 1 shows a schematic representation of a
drill string 2 suspended by a derrick 4 for drilling a borehole 6
into the earth for minerals exploration and recovery, and in
particular petroleum products. A bottom-hole assembly (BHA) 8 is
located at the bottom of the borehole 6. The BHA 8 may have a
downhole drilling motor 9 to rotate a drill bit 1.
[0028] As the drill bit 1 is rotated from the surface and/or by the
downhole motor 9, it drills into the earth allowing the drill
string 2 to advance, forming the borehole 6. For the purpose of
understanding how these systems may be operated for the type of
drilling system illustrated in FIG. 1, the drill bit 1 may be
anyone of numerous types well known to those skilled in the oil and
gas exploration business, such as a drill bit provided with PCD
cutting elements as will be described further herein. This is just
one of many types and configurations of bottom hole assemblies 8,
however, and is shown only for illustration. There are numerous
arrangements and equipment configurations possible for use for
drilling boreholes into the earth, and the present disclosure is
not limited to anyone of particular configurations as illustrated
and described herein.
[0029] A more detailed view of a PCD cutting element 10 of the
present disclosure is shown in FIG. 2. Referring now to FIGS. 2 and
3, a PCD cutting element 10 of the present disclosure may be a
preform cutting element 10 (as shown in FIG. 2) for the fixed
cutter rotary drill bit 11 of FIG. 3. The bit body 14 of the drill
bit 1 may be formed with a plurality of blades 16 extending
generally outwardly away from a central longitudinal axis of
rotation 18 of the drill bit 1. Spaced apart side-by-side along a
leading face 20 of each blade 16 is a plurality of the PCD cutting
elements 10 of the present disclosure.
[0030] The PCD cutting element 10 may have a body in the form of a
circular tablet having a thin front facing, diamond table 22 of
diamond bonded in a `double press` process which may be, for
example, a high-pressure high-temperature (HPHT) process. The
double press process may be used to press the diamond table 22 to a
substrate 24 of less hard material, such as cemented tungsten
carbide or other metallic material--as will be explained in detail.
The cutting element 10 may be preformed (as will also be described)
and then may be bonded onto a generally cylindrical carrier 26
which may also be formed from cemented tungsten carbide, or may
alternatively be attached directly to the blade 16. The cutting
element 10 may also have a non-planar interface 27 between the
diamond table 22 and the substrate 24. Furthermore, the PCD cutting
element 10 may have a peripheral working surface 28 and an end
working surface 30 which, as illustrated, may be substantially
perpendicular to one another.
[0031] The cylindrical carrier 26 is received within a
correspondingly shaped socket or recess in the blade 16. The
carrier 26 may be brazed, shrink fit or press fit into the socket
(not shown) in the drill bit 1. Where brazed, the braze joint may
extend over the carrier 26 and part of the substrate 24. In
operation, the fixed cutter drill bit 1 is rotated and weight is
applied. This forces the cutting elements 10 into the earth being
drilled, effecting a cutting and/or drilling action.
[0032] These PCD cutting elements 10 may be made in a conventional
very high temperature and high pressure (HTHP) pressing (or
sintering) operation (which is well known in the industry), and
then finished machined into the cylindrical shapes shown. One such
process for making these PCD cutting elements 10 may involve
combining mixtures of various sized diamond crystals, which are
mixed together, and processed into the PCD cutting elements 10 as
previously described.
[0033] Forming these cutting elements 10 with more than one HTHP
cycle may be called `double pressing`. `Double pressing` of cutters
has been attempted in the past and may provide some improvement in
wear life results of the products, but the process for manufacture
may entail difficulties and internal defects. These defects may
involve limited wear life of the resulting product. In particular,
HTHP sintering of round discs into a PDC in a second press cycle
may lead to cracking of the diamond layer due to stresses developed
during the process.
[0034] An alternate process for double pressing PCD cutting
elements as described herein involves double pressing an HTHP
sintered PDC. Previously pressed PCD material may have all metallic
materials removed from its crystalline structure by, for example,
acid leaching. The PCD material may then be crushed and sized to
form a fine PCD grit. This PCD grit may be layered (or otherwise
dispersed) in a normally canned and sintered PCD cutting element.
Optionally, the grit may be mixed with `virgin` diamond crystals of
selected shapes and sizes before being canned and sintered. The
previously pressed PCD material may be leached before and/or after
it is crushed and/or formed.
[0035] In another embodiment, previously pressed PDC segments (or
tiles) of various shapes, including but not limited to triangular,
rectangular, circular, oval and arc shaped, are first rendered
substantially free of all catalyzing and other metallic material,
typically in a leaching process, and laid out in a mold with a
single or multiple layer configuration. The spaces between these
tiles may then be packed with diamond filler (e.g., traditional
diamond feedstock) of one or more selected sizes and shapes, and
HTHP sintered a second time to form the new PDC of the present
disclosure.
[0036] In one particular example, a number of `pie` shaped
previously pressed PDC segments were fully leached of catalyzing
material and then laid out in a single (or alternately multiple)
layer(s) in a mold, and the intervening spaces were then packed
with fine grained, traditional diamond feedstock. The resulting
product was then HTHP sintered a second time in the normal fashion
into a PDC.
[0037] Additionally, `stress engineered` shapes (e.g., geometries
of PCD cutting elements that make advantageous use of the operating
behavior of the PCD cutting element) of previously pressed PCD may
also be utilized. These `recycled` PCD cutting elements may be
leached of substantially all of the metallic and/or catalyzing
material they may have remaining. These `recycled` PCD cutting
elements may then be combined with, or selectively used in, various
combinations of crushed diamond grits and/or solid shapes to form a
PDC. In this manner, the PDC may then be patterned for optimized
performance.
[0038] As shown in FIGS. 4 through 8, and will be explained in more
detail later, the PCD material in the form of pie shaped pieces,
tiled layers, tiny blocks and/or other segments may be assembled
and combined with a finer PCD grit (either new or left over from
earlier process of filling separate cans) along with standard
available diamond feedstock to form a PDC. These PDC were then HTHP
pressed in a normal cycle imparting a second press to the
previously pressed & leached parts.
[0039] In another example, the manufacturing process may begin with
a fine (.about.5 micron distribution) HTHP diamond feedstock made
into a large diameter circular PDC blank, as may be used with
cutting tools. This large PDC blank may then be cut into a number
of smaller pieces (or segments) that may be, but not limited to,
pie-shaped tiles, cylinders, blocks, or one of many other geometric
shapes. The diagonal dimension of these pieces may be, but is not
limited to, sizes smaller than about 1.0 mm. These pieces may then
be leached to remove all or substantially all of the metallic
materials that may be present, such as tungsten carbide (WC)
substrate, cobalt (Co), and any other metallic materials which may
be present. These pressed and leached pieces (or segments) of PCD
may then be combined with fine powdered diamond feedstock as
described above and pressed a second time in the HTHP process as
previously described, resulting in a preformed PCD cutting element
of the present disclosure.
[0040] This preformed PCD cutting element was comparison tested to
the `standard product` known prior art PCD cutting element in a two
part internal standard wear test procedure known as a G-ratio
test.
[0041] Based on historical data, an unleached `standard product`
PCD cutting element may have a G-ratio (which is a number
indicative of the wear resistance of the PCD material) of about
20.times.10.sup.5 (volume of diamond removed/volume of granite
removed). If the cutting surface of this `standard product` PCD
cutting element is leached substantially free of catalyzing
material, the typical G-ratio may increase to about
80.times.10.sup.5. This increased G-ratio may be a number typical
for conventional leached prior art cutting elements. By way of
comparison, a 5 micron `double pressed` cutting tool made in
accordance with the present disclosure using a 5 micron average
particle size diamond feedstock and tested in a similar fashion as
described above may have a G-ratio of 50.times.10.sup.5 before
leaching and a G-ratio of 150.times.10.sup.5 upon leaching--nearly
a 100% improvement over the `standard product` PDC cutting element.
During the second pressing operation, some of the pore spaces of
the previously pressed & leached portion of the diamond table
may be re-filled with the binder/catalyzing material (e.g., cobalt)
to drop the G-ratio.
[0042] In another example, before leaching, abrasion testing of the
double pressed PDC cutting element may yield a G-ratio of about
100.times.10.sup.5. Upon leaching, the G-ratio of this previously
pressed, leached, double pressed & re-leached PDC cutting
element may increase to about 1000.times.10.sup.5, yielding over a
tenfold increase in wear resistance over the `standard product`
leached PDC. It should be noted that laboratory tests may not
account for all the variability's of PDC cutting elements as they
are run in the field. Therefore, although laboratory test results
may be helpful for selecting which of the cutting elements may be
better, field testing may be performed for confirmation.
[0043] The new PDC may provide improved abrasion resistance over
existing PDC cutting elements. In addition, the loose diamond
feedstock packing within the PCD material pieces may provide a form
of stress relief in the final product. In addition, tiling the
diamond layer may result in a relatively stress free, yet very
thick PCD layer. In addition, the fine feedstock of the previously
pressed PCD cutting element may provide an additional incremental
increase to the abrasion resistance of the resulting PDC without
using a significantly higher pressure during processing.
[0044] The PCD grit may be varied in grit size, quantity, and layer
thickness to vary the physical properties of the final product, as
may be required. The comparable wear patterns of the various PCD
grit options may reveal differential wear rates between the
previously pressed, leached, double pressed, and re-leached product
and the loose feedstock packed around that grit, HTHP sintered and
leached for the first time. These differential wear rates may allow
the PDC cutting edge to become `self-sharpening` for a more
efficient cutting action at the rock.
[0045] The various grit options may also be useful in cases where
an edge of the PDC were to chip during operation. The differential
wear rate of the PDC may favor smaller pieces being dislodged
rather than creating larger chunks. This may be characteristic of a
more homogenous, traditionally produced diamond table. In addition,
the `double pressed` product may provide a way to reuse the `used`
PDC material recovered from `dull`, previously used cutters. The
initial pressed feedstock for double HTHP pressing may be made into
pie, tiled or block shapes. Alternatively, the PDC's may be free
standing--thereby potentially reducing the need for finishing &
cutting.
[0046] In the manufacturing process for the PCD 50, it may be
desirable to control the feedstock of the double pressed PDC, the
grit size of the previously pressed PCD grit, the mix ratio of the
PCD grit with loose diamond feedstock, the particle size of the
loose feedstock, the layer thickness, and (where present), and the
geometrical arrangement of the PCD segments or tiles. This may be
used to minimize the residual stress for providing a stress free
product, controlled layer thickness of the PCD grit mix, leaching
process, and leach depth.
[0047] In performing the present applications, it may be necessary
to control a number of process parameters. These may include, for
example, origin of feedstock of the double pressed PDC, the
previously pressed grit size, the mix of the PCD grit with loose
diamond feedstock, and the size of the loose feedstock. Other
process parameters to control may involve controlling the layer
thickness, and designing the geometrical arrangement of the
segments or tiles for a stress free product. In addition, the layer
thickness of the PCD grit mix, the leaching process, and the leach
depth may require close control.
[0048] In some circumstances, it may also be desirable to treat the
PCD produced in a further leaching process to remove all of, or
selected portion(s) of, any catalyst infiltrant that may have
re-infiltrated the PCD layer.
[0049] In addition to being useful for PCD cutting elements 10 with
an integral face (or working surface 30) as shown in FIG. 2, these
components may also be used as PCD 50 with segmented faces 56 as
shown in FIGS. 4 and 5.
[0050] As shown in FIG. 4, the segmented faces 56 may have
alternating segments 52, 54 comprising leached PCD segments 54
substantially free of catalyzing materials, alternating with
non-leached PCD segments 52 containing catalyzing material.
[0051] In an alternate embodiment, as shown, in FIG. 5, the PCD
cutting element 50 may have separate segmented leached PCD segments
54 which are all PCD material, leached to be substantially free of
all catalyzing material or any metallic materials which may be
present. Although `wedge` shaped PCD 50 have been illustrated
herein, it is contemplated that many different shapes of PCD
components, including round, oval, rectangular, arc-shaped,
triangular, star, etc., may be used as PCD 50 without departing
from the scope of the present disclosure.
[0052] For instance, the above described PCD cutting element 50 may
have non-leached PCD segments 52 between leached PCD segments 54
and may be used as PCD cutting elements in much the same manner as
the PCD cutting element 10 with integrally formed faces.
[0053] In still other embodiments, the pre-leached PCD material 54
may have selected shapes and sizes for the PCD 50, for example as
shown in FIGS. 6, 7, and 8. In FIGS. 6 and 7, individual blocks of
leached PCD material 54 that are substantially free of catalyzing
materials are placed with the diamond powder in production cans
along with diamond filler (e.g., standard available diamond
feedstock) 55, such that after the second HTHP press cycle the
leached PCD material 54 is integrally formed with the PCD cutting
element 50. In FIG. 6, the individual blocks of leached PCD
material 54 are placed in a mosaic pattern on the face, effectively
covering the entire face (or end working surface 30) of the PCD 50
in leached PCD material 54.
[0054] Alternately, the individual blocks of leached PCD material
54 may be shaped and laid in an arc around the periphery (or
peripheral working surface 28) of the PCD cutting element 50 as
shown in FIG. 7. Again, after the second HTHP press cycle, the
pre-leached PCD material 54 becomes integrally formed with the PCD
cutting element 50. This arrangement may optimize the amount of
pre-leached PCD material 54 needed for each PCD cutting element and
also may help in controlling the process of the second press
cycle.
[0055] Finally, in another embodiment as shown in FIG. 8, it may be
desirable to form the entire working surface (or facing table) with
a single disc of leached PCD material 54. The PCD material is
positioned on the feedstock 55.
[0056] In each of these embodiments, as described herein, the
entirety of the working surfaces 28, 30 (or portions thereof) of
the PDC 50 may be leached a second time in a leaching process, and
then assembled into a drill bit 1, or other wear component.
[0057] In addition, an alternative forming process for
manufacturing a PCD cutting element 50 may utilize a spark plasma
sintering process (SPS) as illustrated in FIG. 9. In this process,
pre-sintered discs (or stack) 100 of previously pressed diamond
powder materials may be stacked within in a cylindrical vacuum
chamber 110 mounted within a sintering die 120 arranged between an
upper punch 130 and a lower punch 140. A sintering die 120 located
between upper punch 130 and a lower punch 140 on a sintering stage
170 and is held between a set of `spark` electrodes 200, 210. The
resulting `stack` 100 has sufficiently high electrical resistivity
to allow a high voltage differential applied to the `stack` 100 to
cause sparking between and among the diamond powder materials.
[0058] When moderate mechanical pressure is applied to the `stack`
100, as shown by the letter `P`, and the voltage is maintained
across the stack through upper electrode 200 and lower electrode
210, the combination of the pressure P, and sparking allows the
`stack` 100 to form diamond-to-diamond bonds of PCD, similar to
those formed in the traditional HTHP process commonly used for
diamond synthesis. Since the electric pulse (or pulses) is (are)
provided to the discs 100 under moderate compressive pressure P,
the temperature within the discs 100 may rapidly rise to sintering
temperature, for example, at about 1000.degree. C. to about
2500.degree. C., resulting in the production of a near finished
sintered PCD cutting element 50 in only a few minutes. The PCD
cutting element 50 may be finished (e.g., trimmed) following
various stages of the manufacture, such as after a first pressing,
after a second pressing and/or after SPS.
[0059] This SPS process or other microwave process may be used to
bond or attach a diamond layer, such as a partially (or fully)
leached diamond wafer, to a carbide substrate. These processes may
be used with low temperature, low pressure bonding or attaching
methods. The bonding may be performed using an alloy or compound,
such as a nano-alloy compound (e.g., Ni-nano-WC, or a Ni-nano
diamond alloy). For example, Ni-nano-WC (Nickel-nano-tungsten
carbide) may be used to join 20 um diamond powders with a WC--Co
substrate. In another example, SPS is used to bond a partially (or
fully) leached flat diamond wafer to a carbide substrate with
nano-WC 65%+NiCrFeBSi.
[0060] FIG. 10 shows a method 1000 for manufacturing a PCD cutting
element. The method involves positioning 1090 a diamond table on a
substrate (the diamond table has diamond filler and at least one
leached polycrystalline diamond segment), and sintering 1092 the
diamond table onto the substrate such that the polycrystalline
diamond segment is positioned along at least one working surface of
the diamond table. The steps may be performed in any order and
repeated as desired. The sintering may be an SPS sintering or a
double press operation as described herein.
[0061] Whereas the present invention has been described in
particular relation to the drawings attached hereto, it should be
understood that other and further modifications apart from those
shown or suggested herein, may be made within the scope and spirit
of the present disclosure.
* * * * *