U.S. patent application number 16/129874 was filed with the patent office on 2019-01-10 for methods of making polycrystalline diamond bodies having annular regions with differing characteristics.
The applicant listed for this patent is DIAMOND INNOVATIONS, INC.. Invention is credited to Andrew Gledhill, Alexanne Johnson, Christopher Long, Joseph Rhodes.
Application Number | 20190009390 16/129874 |
Document ID | / |
Family ID | 58548853 |
Filed Date | 2019-01-10 |
United States Patent
Application |
20190009390 |
Kind Code |
A1 |
Long; Christopher ; et
al. |
January 10, 2019 |
Methods of Making Polycrystalline Diamond Bodies Having Annular
Regions with Differing Characteristics
Abstract
Polycrystalline diamond bodies having an annular region of
diamond grains and a core region of diamond grains and methods of
making the same are disclosed. In one embodiment, a polycrystalline
diamond body includes an annular region of inter-bonded diamond
grains having a first characteristic property and a core region of
inter-bonded diamond grains bonded to the annular region and having
a second characteristic property that differs from the first
characteristic property. The annular region decreases in thickness
from a perimeter surface of the polycrystalline diamond body
towards a centerline axis.
Inventors: |
Long; Christopher;
(Westerville, OH) ; Gledhill; Andrew;
(Westerville, OH) ; Johnson; Alexanne; (Columbus,
OH) ; Rhodes; Joseph; (Heath, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DIAMOND INNOVATIONS, INC. |
Worthington |
OH |
US |
|
|
Family ID: |
58548853 |
Appl. No.: |
16/129874 |
Filed: |
September 13, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15460404 |
Mar 16, 2017 |
10105826 |
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16129874 |
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62309073 |
Mar 16, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C22C 2204/00 20130101;
B30B 15/30 20130101; C04B 35/528 20130101; E21B 10/54 20130101;
C04B 2235/427 20130101; C22C 1/05 20130101; B24D 18/0009 20130101;
C22C 26/00 20130101; B22F 3/14 20130101; C04B 2235/775 20130101;
B30B 11/004 20130101; E21B 10/5676 20130101; C22C 1/10 20130101;
B22F 2202/17 20130101; E21B 10/567 20130101; B22F 2005/001
20130101 |
International
Class: |
B24D 18/00 20060101
B24D018/00; B30B 15/30 20060101 B30B015/30; C04B 35/528 20060101
C04B035/528; E21B 10/567 20060101 E21B010/567 |
Claims
1. A method of making a polycrystalline diamond body, comprising:
positioning a first quantity of diamond grains having a first
characteristic property in a low-reactivity cup having a perimeter
wall; distributing the first quantity of diamond grains into an at
least partially annular configuration in which the annular region
decreases in thickness from the perimeter wall towards a centerline
axis of the low-reactivity cup; positioning a second quantity of
diamond grains having a second characteristic property that differs
from the first characteristic property in the low-reactivity cup,
the second quantity of diamond grains be positioned to at least
partially contact the perimeter wall of the low-reactivity cup and
to at least partially contact the first quantity of diamond grains;
and subjecting the low-reactivity cup, the first quantity of
diamond grains, and the second quantity of diamond grains to a HPHT
process in which adjacent diamond grains are sintered to one
another and form diamond-to-diamond bonds.
2. The method of claim 1, further comprising, during the HPHT
process, melting and directing a catalyst material through the
first quantity of diamond grains and the second quantity of diamond
grains, thereby encouraging diamond-to-diamond bonding of adjacent
diamond grains.
3. The method of claim 1, further comprising positioning a
substrate material proximate to the second quantity of diamond
grains to enclose the low-reactivity cup.
4. The method of claim 3, wherein the substrate material comprises
hard metal carbides.
5. The method of claim 4, wherein the substrate material further
comprises a catalyst material.
6. The method of claim 1, further comprising mixing catalyst
material into the second quantity of diamond grains.
7. The method of claim 1, further comprising mixing non-catalyst
material into the second quantity of diamond grains.
8. The method of claim 7, further comprising, during the HPHT
process, melting the non-catalyst material and directing the
non-catalyst material from the second quantity of diamond grains
into the first quantity of diamond grains.
9. The method of claim 1, wherein the second quantity of diamond
grains is in direct contact with the first quantity of diamond
grains.
10. The method of claim 1, wherein the first quantity of diamond
grains is distributed into the low-reactivity cup by displacing the
unbonded diamond grains with a mandrel.
11. The method of claim 10, wherein the mandrel is rotated relative
to the low-reactivity cup.
12. The method of claim 10, wherein the mandrel is traversed into
the low-reactivity cup.
13. The method of claim 1, wherein the first quantity of diamond
grains are distributed into the low-reactivity cup by subjecting
the first quantity of diamond grains to centripetal
acceleration.
14. The method of claim 13, wherein the low-reactivity cup is
rotated as the first quantity of diamond grains are distributed
into the low-reactivity cup.
15. The method of claim 13, wherein the second quantity of diamond
grains are distributed into the low-reactivity cup without the
second quantity of diamond grains being subjected to centripetal
acceleration.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] None.
TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY
[0002] The present disclosure relates generally to polycrystalline
diamond bodies and compacts including the same and, more
particularly, to polycrystalline diamond bodies having annular
regions with differing characteristics than the remaining regions,
and methods of making the same.
BACKGROUND
[0003] PCD compacts typically include a superabrasive diamond
layer, referred to as a polycrystalline diamond body that is
attached to a substrate. The polycrystalline diamond body may be
formed in a high pressure high temperature (HPHT) process, in which
diamond grains are held at pressures and temperatures at which the
diamond particles bond to one another.
[0004] It is conventionally known to incorporate uniform or
nearly-uniform properties across the PCD body, for example, by
incorporating uniform or nearly-uniform constituent materials
throughout the PCD body. However, such PCD bodies may exhibit
improved abrasion, thermal stability, and/or toughness when
materials having different properties are introduced to the PCD
bodies.
[0005] Accordingly, PCD bodies and compacts and compacts
incorporating the same may be desired.
SUMMARY
[0006] In one embodiment, a polycrystalline diamond body includes a
working surface, an interface surface, and a perimeter surface. The
polycrystalline diamond body also includes an annular region of
inter-bonded diamond grains that extends away from at least a
portion of the working surface and at least a portion of the
perimeter surface, where the annular region comprises diamond
grains having a first characteristic property. The polycrystalline
diamond body further includes a core region of inter-bonded diamond
grains bonded to the annular region and that extends away from the
interface surface, and at least a portion of the core region is
positioned radially inward from the annular region, where the core
region comprises diamond grains having a second characteristic
property that differs from the first characteristic property. The
annular region decreases in thickness from the perimeter surface
towards a centerline axis of the polycrystalline diamond body.
[0007] In another embodiment, a polycrystalline diamond body
includes a working surface, an interface surface, and a perimeter
surface. The polycrystalline diamond body also includes an annular
region of inter-bonded diamond grains that extends away from at
least a portion of the working surface and at least a portion of
the perimeter surface, where the annular region comprises diamond
grains having a first particle size distribution. The
polycrystalline diamond body further includes a core region of
inter-bonded diamond grains bonded to the annular region and that
extends away from the interface surface, and at least a portion of
the core region is positioned radially inwardly from the annular
region, where the core region comprises diamond grains having a
second particle size distribution that differs from the first
particle size distribution.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The foregoing summary, as well as the following detailed
description of the embodiments, will be better understood when read
in conjunction with the appended drawings. It should be understood
that the embodiments depicted are not limited to the precise
arrangements and instrumentalities shown.
[0009] FIG. 1 is a schematic side perspective cross-sectional view
of a PCD compact according to one or more embodiments shown or
described herein;
[0010] FIG. 2 is a detailed schematic side cross-sectional view of
the PCD compact of FIG. 1 shown at location A;
[0011] FIG. 3 is a schematic side perspective view depicting a
manufacturing process of a PCD body according to one or more
embodiments shown or described herein;
[0012] FIG. 4 is a side cross-sectional view depicting a
manufacturing process of a PCD body according to one or more
embodiments shown or described herein;
[0013] FIG. 5 is a side cross-sectional view depicting a
manufacturing process of a PCD body according to one or more
embodiments shown or described herein;
[0014] FIG. 6 is a side cross-sectional view depicting a
manufacturing process of a PCD body according to one or more
embodiments shown or described herein;
[0015] FIG. 7 is a schematic side perspective view depicting a
manufacturing process of a PCD body according to one or more
embodiments shown or described herein;
[0016] FIG. 8 is a side cross-sectional view depicting a
manufacturing process of a PCD body according to one or more
embodiments shown or described herein;
[0017] FIG. 9 is a side cross-sectional view depicting a
manufacturing process of a PCD body according to one or more
embodiments shown or described herein;
[0018] FIG. 10 is a side cross-sectional view of a supported PCD
compact having a PCD body according to one or more embodiments
shown or described herein;
[0019] FIG. 11 is a side cross-sectional view of a supported PCD
compact having a PCD body according to one or more embodiments
shown or described herein;
[0020] FIG. 12 is a side cross-sectional view of a supported PCD
compact having a PCD body according to one or more embodiments
shown or described herein;
[0021] FIG. 13 is a side perspective view of a supported PCD
compact having a PCD body according to one or more embodiments
shown or described herein;
[0022] FIG. 14 is a side cross-sectional view of a supported PCD
compact having a PCD body according to one or more embodiments
shown or described herein;
[0023] FIG. 15 is a side perspective view of a supported PCD
compact having a PCD body according to one or more embodiments
shown or described herein;
[0024] FIG. 16 is a side perspective view of a earth-boring tool
having PCD compacts attached thereto according to one or more
embodiments shown or described herein;
[0025] FIG. 17 is a plot of abrasive wear data for conventional and
disclosed PCD compacts according to one or more embodiments shown
or described herein; and
[0026] FIG. 18 is a micrograph of a leached PCD compact according
to one or more embodiments shown or described herein.
DETAILED DESCRIPTION
[0027] The present disclosure is directed to PCD bodies, compacts,
cutters, and drill bits incorporating the same. The PCD bodies
include a working surface, an interface surface, and a perimeter
surface. The PCD bodies include an annular region of inter-bonded
diamond grain that extends away from at least a portion of the
working surface and at least a portion of the perimeter surface,
and a core region of inter-bonded diamond grains that are bonded to
the annular region and that extends away from interface surface.
The annular region and the core region comprise diamond grains
having a first characteristic property and a second characteristic
property, respectively, that differ from one another.
[0028] By varying the properties of the annular region and the core
region, materials that provide advantageous material properties may
be selectively positioned within the PCD bodies. By selectively
positioning materials within the PCD bodies, the local material
properties of the PCD bodies may be tuned to provide enhanced
resistance to wear mechanisms that are directed into local regions
of the PCD bodies. For example, materials that exhibit enhanced
abrasion resistance may be positioned along the perimeter surface
and extending away from the working surface to improve the wear
resistance of the portion of the PCD body that is brought into
intimate contact with earth during a down-hole drilling operation,
such that abrasion resistance of the PCD body may be increased. In
other embodiments, materials may be selectively positioned within
the PCD body to selectively modify PCD body properties including,
for example and without limitation, the abrasion resistance, the
impact resistance, the thermal stability, the stiffness, the
fracture toughness, the coefficient of thermal expansion, the
particle size distribution, particle size modality, particle shape,
the inherent diamond grain crystal toughness, the catalyst content,
the non-catalyst content, the coercivity, the sweep resistance, and
combinations thereof. Through modification of these PCD body
properties, improved PCD body performance may be realized.
[0029] Without being bound by theory, it is believed that through
selective positioning of materials within the PCD bodies, the PCD
of the core region may provide a stress state that allows for good
attachment between the core region and the annular region of PCD
that exhibit dissimilar characteristic properties. The
configuration of the core region and the annular region of the PCD
body presented herein provides resilient coupling between the
annular region to the core region. Further, the configuration of
the core region and the annular region of the PCD body presented
herein may improve manufacturability of PCD bodies that include
regions having differing characteristic properties. PCD bodies,
compacts, compacts, and drill bits comprising the same are
described in greater detail below.
[0030] It is to be understood that this disclosure is not limited
to the particular methodologies, systems and materials described,
as these may vary. It is also to be understood that the terminology
used in the description is for the purpose of describing the
particular versions or embodiments only, and is not intended to
limit the scope. For example, as used herein, the singular forms
"a," "an," and "the" include plural references unless the context
clearly dictates otherwise. In addition, the word "comprising" as
used herein is intended to mean "including but not limited to."
Unless defined otherwise, all technical and scientific terms used
herein have the same meanings as commonly understood by one of
ordinary skill in the art.
[0031] Unless otherwise indicated, all numbers expressing
quantities of ingredients, properties such as size, weight,
reaction conditions and so forth used in the specification and
claims are to be understood as being modified in all instances by
the term "about". Accordingly, unless indicated to the contrary,
the numerical parameters set forth in the following specification
and attached claims are approximations that may vary depending upon
the desired properties sought to be obtained by the end user. At
the very least, and not as an attempt to limit the application of
the doctrine of equivalents to the scope of the claims, each
numerical parameter should at least be construed in light of the
number of reported significant digits and by applying ordinary
rounding techniques.
[0032] As used herein, the term "about" means plus or minus 10% of
the numerical value of the number with which it is being used.
Therefore, "about 40" means in the range of 36-44.
[0033] As used herein, the term "non-catalytic material" refers to
an additive that is introduced to the polycrystalline diamond body,
and that is not catalytic with carbon in forming diamond and
inter-diamond grain bonds. Non-catalytic materials do not include
hard-phase materials that may be introduced to the polycrystalline
diamond body from the support substrate or reaction products that
are formed in the polycrystalline diamond body during the HPHT
processes.
[0034] Polycrystalline diamond compacts (or "PCD compacts", as used
hereafter) may represent a volume of crystalline diamond grains
with embedded foreign material filling the inter-granular spaces.
In one example, a PCD compact includes a plurality of crystalline
diamond grains that are bound to each other by strong inter-diamond
bonds and forming a rigid polycrystalline diamond body, and the
inter-granular regions, disposed between the bound grains and
filled with a non-diamond material (e.g., a catalytic material such
as cobalt or its alloys), which was used to promote diamond bonding
during fabrication of the PCD compact. Suitable metal solvent
catalysts may include the metal in Group VIII of the Periodic
table. PCD cutting elements (or "PCD compact", as is used
hereafter) include the above mentioned polycrystalline diamond body
attached to a suitable support substrate (for example, cemented
tungsten carbide-cobalt (WC--Co)). The attachment between the
polycrystalline diamond body and the substrate may be made by
virtue of the presence of a catalyst, for example cobalt metal. In
another embodiment, the polycrystalline diamond body may be
attached to the support substrate by brazing. In another
embodiment, a PCD compact includes a plurality of crystalline
diamond grains that are strongly bound to each other by a hard
amorphous carbon material, for example a-C or t-C carbon. In
another embodiment, a PCD compact includes a plurality of
crystalline diamond grains, which are not bound to each other, but
instead are bound together by foreign bonding materials such as
borides, nitrides, or carbides, for example, SiC.
[0035] As discussed above, conventional PCD compacts and compacts
are used in a variety of industries and applications in material
removal operations. PCD compacts and compacts are typically used in
non-ferrous metal removal operations and in downhole drilling
operations in the petroleum industry. Conventional PCD compacts and
compacts exhibit high toughness, strength, and abrasion resistance
because of the inter-granular inter-diamond bonding of the diamond
grains that make up the polycrystalline diamond bodies of the PCD
compacts. The inter-diamond bonding of the diamond grains of the
polycrystalline diamond body in a sintering reaction are promoted
during an HPHT process by a catalytic material. However, at
elevated temperature, the catalytic material and its byproducts
that remain present in the polycrystalline diamond body after the
HPHT process may promote back-conversion of diamond to non-diamond
carbon forms and may induce stress into the diamond lattice due to
the mismatch in the coefficient of thermal expansion of the
materials.
[0036] It is conventionally known to select diamond grains that are
introduced to the HPHT process, and have certain properties. For
example, it is conventionally known that decreasing the particle
size of the diamond grains increases the abrasion resistance and
decreases the toughness of the resulting PCD compact. Conversely,
it is conventionally known that increasing the particle size of the
diamond grains increases the toughness and decreases the abrasion
resistance of the resulting PCD compact.
[0037] Experimental results have demonstrated that diamond grains
that include a multimodal particle size distribution (for example,
a bimodal particle size distribution) typically results in a PCD
compact that exhibits increased abrasion resistance and fracture
toughness as compared to a PCD compact made from diamond grains
having a monomodal particle size distribution. Without being bound
by theory, it is believed that a multimodal particle size
distribution of diamond grains exhibit enhanced diamond-to-diamond
bonding as compared to a monomodal particle size distribution of
diamond grains. This enhanced diamond-to-diamond bonding may be
attributed to increased packing density of the multimodal particle
size distribution diamond grains as compared to the monomodal
particle size distribution diamond grains. The enhanced
diamond-to-diamond bonding may be also be attributed to less
diamond crystal fracturing during the HPHT process. The enhanced
diamond-to-diamond bonding may further be attributed to
comparatively less movement of the multimodal particle size
distribution diamond grains as compared to the monomodal particle
size distribution diamond grains in the HPHT process after
application of pressure but before sintering of the diamond grains
has completed.
[0038] Referring now to FIGS. 1 and 2, the PCD compact 100 includes
a support substrate 110 and a polycrystalline diamond (PCD) body
120 that is attached to the support substrate 110. The PCD body 120
includes a plurality of diamond grains 122 that are bonded to one
another, including being bonded to one another through
inter-diamond bonding. The bonded diamond grains 122 form a diamond
lattice that extends along the PCD body 120. The diamond body 120
also includes a plurality of interstitial regions 124 between the
diamond grains. The interstitial regions 124 represent a space
between the diamond grains. The PCD compact 100 includes a working
surface 130, a perimeter surface 132 that circumscribes the working
surface 130, an interface surface 138 positioned distally from the
working surface 130, and a centerline axis 134 that is concentric
with the perimeter surface 132 and, as depicted, extends
perpendicularly to the working surface 130. The PCD compact 100 may
also include a chamfer 136 between the perimeter surface 132 and
the working surface 130. The exterior surfaces of the PCD compact
100 may be cylindrically symmetric about the centerline axis 134.
In the depicted embodiment, the PCD compact 100 has a generally
cylindrical shape, however, other shapes of the PCD compact,
including having hemispherical, domed, or oblong shapes, are
envisioned without departing from the scope of the disclosure.
[0039] Referring to FIG. 1, the PCD body 120 includes a core region
140 and an annular region 142. The core region 140 and the annular
region 142 are separated by an intersection surface 144. The
diamond grains in the core region 140 may be in direct contact with
the diamond grains of the annular region 142 and free of a
non-diamond material interface, such that the intersection surface
144 represents the location of intersection of the core region 140
and the annular region 142. In one embodiment, the core region 140
and the annular region 142 may be directly connected to one another
without additional material therebetween. In other embodiments, the
core region 140 and the annular region 142 may be separated by an
additional material. The annular region 142 decreases in thickness
from the perimeter surface 132 towards the centerline axis 134, as
evaluated from the working surface 130. The thickness of the
annular region 142, therefore, is tapered inward from the perimeter
surface 132 of the PCD body 120. In the depicted embodiment, the
annular region 142 terminates at a position along the working
surface 130 that is spaced apart from the centerline axis 134. In
other embodiments (see FIG. 12), the annular region 142 may
maintain a non-zero thickness across the working surface 130 of the
PCD body 120. In the depicted embodiment, the intersection surface
144 between the annular region 142 and the core region 140 may
include a generally frustoconical portion. In another embodiment,
the intersection surface 144 between the annular region 142 and the
core region 140 may include a concave truncated conical portion. In
another embodiment, the intersection surface 144 between the
annular region 142 and the core region 140 may include a convex
truncated conical portion.
[0040] In certain embodiments, the intersection surface 144 between
the annular region 142 and the core region 140 may be generally
symmetric about the centerline axis 134. In such embodiments, the
annular region 142 may have a generally uniform cross-section
evaluated around the circumference of the PCD body 120. In other
embodiments, the intersection surface 144 between the annular
region 142 and the core region 140 may be non-symmetric about the
centerline axis 134, such that the annular region 142 does not have
a generally uniform cross-section when evaluated around the
circumference of the PCD body 120. In one embodiment, the core
region 140 may have a "lobed" pattern in which a plurality of
protrusions extend outward from the core region 140 into the
annular region 142. In certain embodiments, the lobed pattern of
the core region 140 may have a regularly repeating pattern that is
symmetric about the centerline axis 144.
[0041] The intersection surface 144 between the core region 140 and
the annular region 142 may be formed at an angle relative to the
centerline axis 134 that is between about 2 and about 85 degrees,
for example being at an angle that is between about 10 and 60
degrees, for example, being at an angle that is between about 10
and 45 degrees, for example, being at an angle that is between
about 10 and 25 degrees. The intersection surface 144 may be at an
angle relative to the centerline axis 134 that replicates the angle
of wear scar generation during the end user's application, such
that the wear scar generated during the end user's application
primarily abrades diamond from the annular region 142. In some
embodiments, the angle of the intersection surface 144 relative to
the centerline axis 134 may affect the impact resistance of the PCD
compact 100. In one embodiment, an earth-boring tool may include a
plurality of mounting surfaces within a bit body, where each of the
mounting surfaces is positioned and oriented to present the PCD
compact 100 for earth removal in a down-hole drilling application.
The intersection surface 144 may be at an angle relative to the
centerline axis 134 that is within about 5 degrees of a back-rake
angle of an earth-boring tool in which the PCD compact 100 is
installed.
[0042] The core region 140 may include diamond grains having a
first characteristic property and the annular region 142 may
include diamond grains having a second characteristic property that
differs from the first characteristic property. Examples of such
characteristic properties include, for example and without
limitation, the abrasion resistance, the impact resistance, the
thermal stability, the stiffness, the fracture toughness, the
coefficient of thermal expansion, the particle size distribution,
particle size modality, particle shape, the inherent diamond grain
crystal toughness, the catalyst content, the non-catalyst content,
the coercivity, the sweep resistance, and combinations thereof.
[0043] In some embodiments, the core region 140 and the annular
region 142 may be made from starting materials that differ from one
another. For example, the core region 140 may be made from starting
diamond particles having a first particle size distribution. The
annular region 142 may be made from starting diamond particles
having a second particle size distribution.
[0044] In one exemplary embodiment, the core region 140 includes a
first concentration of non-catalyst material, while the annular
region 142 includes a second concentration of non-catalyst
material. In some embodiments, the core region 140 may include a
non-zero concentration of non-catalyst material while the annular
region 142 is free of non-catalyst material. Further, the core
region 140 may include a first particle size distribution, while
the annular region 142 may include a second particle size
distribution of diameter. In another exemplary embodiment, the
annular region 142 may be substantially free of a catalyst material
while the core region 140 may include a non-zero concentration of
catalyst material. In yet another embodiment, the core region 140
may include a concentration of a first catalyst material and the
annular region 142 may include a concentration of a second catalyst
material.
[0045] During the HPHT process, the unbonded diamond grains in the
core region 140 and in the annular region 142 may be compressed,
such that relative movement of diamond grains is limited. However,
because of the temperatures and pressures of the HPHT process,
non-diamond materials may be swept along the diamond body, such
that the first constituent material from the core region 140 may be
introduced to the annular region 142. In such embodiments, the
relatively homogeneous constituency of the core region 140 and the
annular region 142 present before the HPHT process will be
broken.
[0046] The HPHT process introduces a catalyst material to the
unbonded diamond grains, thereby encouraging formation of
diamond-to-diamond bonds between the diamond grains, and forming a
monolithic polycrystalline diamond body 120. The polycrystalline
diamond body 120 includes diamond grains bonded to one another
through diamond-to-diamond bonds and interstitial regions 124
positioned between diamond grains. The polycrystalline diamond body
120 may continue to exhibit the core region 140 and the annular
region 142 described hereinabove, although with a modified shape
from the core region 140 and the annular region 140 as evaluated
prior to the HPHT process.
[0047] In at least some of the interstitial regions 124, a
non-carbon material is present. In some of the interstitial regions
124, a non-catalytic material is present. In other interstitial
regions 124, catalytic material is present. In yet other
interstitial regions 124, both non-catalytic material and catalytic
material is present. In yet other interstitial regions 124, at
least one of catalytic material, non-catalytic material, swept
material of the support substrate 110, for example, cemented
tungsten carbide, and reaction by-products of the HPHT process are
present. Non-carbon, non-catalytic or catalytic materials may be
bonded to diamond grains. Alternatively, non-carbon, non-catalytic
or catalytic materials may be not bonded to diamond grains.
[0048] The catalytic material may be a metallic catalyst, including
metallic catalysts selected from Group VIII of the periodic table,
for example, cobalt, nickel, iron, or alloys thereof. The catalytic
material may be present in a greater concentration in the support
substrate 110 than in the polycrystalline diamond body 120, and may
promote attachment of the support substrate 110 to the
polycrystalline diamond body 120 in the HPHT process, as will be
discussed below. The polycrystalline diamond body 120 may include
an attachment region 128 that is rich in catalyst material promotes
bonding between the polycrystalline diamond body 120 and the
support substrate 110. In other embodiments, the concentration of
the catalytic material may be greater in the polycrystalline
diamond body 120 than in the support substrate 110. In yet other
embodiments, the catalytic material may differ from the catalyst of
the support substrate 110. The catalytic material may be a metallic
catalyst reaction-by-product, for example catalyst-carbon,
catalyst-tungsten, catalyst-chromium, or other catalyst compounds,
which also may have lower catalytic activity towards diamond than a
metallic catalyst.
[0049] The non-catalytic material may be selected from a variety of
materials that are non-catalytic with the carbon-diamond conversion
and include, for example, metals, metal alloys, metalloids,
semiconductors, and combinations thereof. The non-catalytic
material may be selected from one of copper, silver, gold,
aluminum, silicon, gallium, lead, tin, bismuth, indium, thallium,
tellurium, antimony, polonium, and alloys thereof.
[0050] Both non-catalytic material and catalytic material may be
present in a detectable amount in the polycrystalline diamond body
of the PCD compact. Presence of such materials may be identified by
X-ray fluorescence, for example using a XRF analyzer available from
Bruker AXS, Inc. of Madison, Wis., USA. Presence of such material
may also be identified using X-ray diffraction, energy dispersive
spectroscopy, or other suitable techniques.
[0051] The non-catalytic material may be introduced to the unbonded
diamond particles prior to the first HPHT process in an amount that
is in a range from about 0.1 wt. % to about 5 wt. % of the diamond
body 120, for example an amount that is in a range from about 0.2
wt. % to about 2 wt. % of the diamond body 120. In an exemplary
embodiment, non-catalytic material may be introduced to the
unbonded diamond in an amount from about 0.33 to about 1 wt. %.
Following the HPHT process and leaching, the non-catalytic material
content is reduced by at least about 50%, including being reduced
in a range from about 50% to about 80%.
[0052] In the HPHT process, catalytic material may be introduced to
the diamond powders. The catalytic material may be present in an
amount that is in a range from about 0.1 wt. % to about 30 wt. % of
the diamond body 120, for example an amount that is in a range from
about 0.3 wt. % to about 10 wt. % of the diamond body 120,
including being an amount of about 5 wt. % of the diamond body 120.
In an exemplary embodiment, catalytic material may be introduced to
the unbonded diamond is an amount from about 4.5 wt. % to about 6
wt. %. Following the first HPHT process and leaching, the catalytic
material is reduced by at least about 50%, including being reduced
in a range from about 50% to about 90%.
[0053] The non-catalytic material and the catalytic material may be
non-uniformly distributed in the bulk of the polycrystalline
diamond compact 100 such that the respective concentrations of
non-catalytic material and catalytic material vary at different
positions within the polycrystalline diamond body 120. In one
embodiment the non-catalytic material may be arranged to have a
concentration gradient that is evaluated along the centerline axis
134 of the polycrystalline diamond compact 100. The concentration
of the non-catalytic material may be higher at positions evaluated
distally from the substrate 110 than at positions evaluated
proximally to the substrate 110. In opposite, the concentration of
the catalytic material may be greater at positions evaluated
proximally to the substrate 110 than at positions evaluated
distally from the substrate 110. In yet another embodiment, the
concentrations of the non-catalytic material and the catalytic
material may undergo an interrupted or a continuous change when
evaluated along the centerline axis 134 of the polycrystalline
diamond compact 100. In some embodiments, the concentration of
non-catalytic material may experience a step change, where the step
change in concentration reflects the location of the intersection
between the core region 140 and the annular region 142. In another
embodiment, the concentration of non-catalytic material may exhibit
a continuous change that exhibits an inflection point in the
concentration, where the inflection point in concentration reflects
the location of the intersection between the core region 140 and
the annular region 142. In yet another embodiment, the
concentrations of the non-catalytic material and the catalytic
material may exhibit a variety of patterns or configurations.
Independent of the concentration of the non-catalytic material and
the catalytic material in the polycrystalline diamond body 120,
however, both non-catalytic material and catalytic material may be
detectible along surfaces proximately and distally located relative
to the substrate 110.
[0054] In another embodiment, the polycrystalline diamond body 120
may exhibit relatively high amounts of the catalytic material at
positions proximate to the substrate 110 and at which the catalytic
material forms a bond between the polycrystalline diamond body 120
and the substrate 110. In some embodiments, at positions outside of
such an attachment zone, the non-catalytic material and the
catalytic material maintain the concentration variation described
above.
[0055] Embodiments according to the present disclosure may undergo
a conventionally-known leaching operation in which portions of the
PCD compact are subjected to a leaching agent. The leaching agent
may at least partially dissolve material from interstitial regions
between the bonded diamond grains while the diamond grain structure
is left intact. The resulting PCD compact structure may continue to
exhibit material in interstitial regions that are inaccessible to
the leaching agent. Such materials may include non-diamond
material, such as catalyst material or non-catalyst material.
[0056] While embodiments depicted and described herein discuss the
presence of an annular regions and a core region, it should be
understood that PCD compacts according to the present disclosure
may include a plurality of annular regions that are positioned in a
nested arrangement relative to one another, and each of the annular
regions includes an intersection surface between the two adjacent
annular regions or the adjacent annular region and core region.
[0057] Polycrystalline diamond bodies 120 according to the present
disclosure may be fabricated according to a variety of methods.
Referring now to FIGS. 3-6, one embodiment of an apparatus for
filling a low-reactivity cup 204 is depicted. The apparatus
includes a mandrel 210 that displaces unbonded diamond grains,
thereby forming a pre-determined shape of the unbonded diamond
grains. In practice, the low-reactivity cup 204 may be positioned
on a static support. Unbonded diamond grains that later form the
annular region 142 are positioned in the low-reactivity cup 204.
The mandrel 210 is brought into contact with the unbonded diamond
grains and displaces diamond grains that it comes into contact
with, thereby introducing a shape into the unbonded diamond grains
that are positioned in the low-reactivity cup 204. Subsequent to
formation of the shape in the bonded diamond grains, additional
unbonded diamond grains may be added to the low-reactivity cup 204.
The composition of the subsequently added unbonded diamond grains
may differ from the unbonded diamond grains that were introduced
earlier to the low-reactivity cup 204.
[0058] The low-reactivity cup 204 and the diamond grains positioned
therein may be positioned proximate to a catalyst material source,
for example a cobalt cemented tungsten carbide substrate. The
low-reactivity cup 204 and the diamond grains may be subjected to a
HPHT process in which the low-reactivity cup 204 and the diamond
grains are subjected to conditions of elevated pressure and
temperature sufficient to cause the previously unbonded diamond
grains to form diamond-to-diamond bonds between one another.
Following the completion of the HPHT process, a recovered
monolithic polycrystalline diamond body 120 may be recovered from
the HPHT apparatus.
[0059] The different material compositions between the annular
region 142 and the core region 140 may provide different properties
between the annular region 142 and the core region 140. Examples of
such properties include, for example and without limitation, the
abrasion resistance, the impact resistance, the thermal stability,
the stiffness, the fracture toughness, the coefficient of thermal
expansion, the particle size distribution, particle size modality,
particle shape, the inherent diamond grain crystal toughness, the
catalyst content, the non-catalyst content, the coercivity, the
sweep resistance, diamond contiguity, and combinations thereof. In
some embodiments, materials may be introduced to the annular region
142 from the core region 140 and/or the substrate 110 during the
HPHT process. In one example, a non-catalytic material, for
example, copper, silver, gold, aluminum, silicon, gallium, lead,
tin, bismuth, indium, thallium, tellurium, antimony, polonium, or
alloys thereof, may be blended with the diamond grains of the core
region 140 prior to the diamond grains being deposited in the
low-reactivity cup 204. The diamond grains of the annular region
142 and the core region 140 may be free of catalyst material prior
to the HPHT process. During the HPHT process, the non-catalyst
material that is mixed with the diamond grains of the core region
140 may be swept into the diamond grains of the annular region 142.
Further, during the HPHT process the catalyst material, which is
present in the substrate 110, is swept into the diamond grains of
the core region 140 and the annular region 142, thereby
accelerating sintering of the diamond grains.
[0060] Additionally, and without being bound by theory, it is
believed that by having diamond grains with different properties in
the annular region 142 and the core region 140, the properties of
the HPHT process itself can be modified. In one example, the
diamond grains in the core region 140 may first be mixed with a
non-diamond material, for example, a non-catalyst material such as
copper, silver, gold, aluminum, silicon, gallium, lead, tin,
bismuth, indium, thallium, tellurium, antimony, polonium, or alloys
thereof, while the diamond grains in the annular region 142 is free
of such non-diamond material prior to the HPHT process. During the
HPHT process, the non-diamond material may be swept from the
diamond grains in the core region 140 into the diamond grains in
the annular region 142. The variation in materials between the core
region 140 and the annular region 142 may allow for the non-diamond
material to be introduced into the annular region 142 in a
concentration that differs from the concentration in the core
region 140.
[0061] Placement of the diamond grains of the annular region 142
without introduction of non-diamond material and/or catalyst
material in the annular region 142 may allow for a maximum of
diamond density within the annular region prior to the HPHT
process. During the HPHT process, the unbonded diamond grains in
the annular region 142 may be pressurized, such that a maximum
packing density of the unbonded diamond grains is realized. A lack
of non-diamond and/or catalyst materials in the annular region 142
may minimize spacing between unbonded diamond grains, resulting in
comparatively small interstitial regions between the bonded diamond
grains, and thereby allowing for the highest packing density.
Additionally, during the HPHT process non-diamond material and/or
catalyst material may be introduced into the unbonded diamond
grains of the annular region 142. Because of the pressures and
temperatures of the HPHT process, the introduction of the
non-diamond material and/or catalyst material may encourage
sintering of the diamond grains. Further, the increased diamond
density and the reduced interstitial regions between the
inter-bonded diamond grains in the annular region 142 may result in
a decrease in defect centers from which defects in the
polycrystalline diamond body may grow.
[0062] It is believed that by positioning the non-diamond material
in the core region 140 and not in the annular region 142, the
dynamics of the sweep during the HPHT process can be modified. In
one example, the diamond grains in the annular region 142 may have
a different resistance to sweep than the diamond grains in the core
region 140. In one embodiment, the non-diamond material that is
mixed with the diamond grains may be difficult to sweep during the
HPHT process. By including the non-diamond material in the core
region 140 and excluding the non-diamond material from the annular
region 142, the non-diamond material may be swept from the core
region 140 into the annular region 142. The variation in
concentration of the non-diamond material prior to the HPHT process
may allow for the non-diamond material to be swept from the core
region 140 to the annular region 142, which may provide a more even
transition from the core region 140 to the annular region 142 than
had if the non-diamond material be placed in both the core region
140 and the annular region 142 prior to the HPHT process. Providing
a more even transition from the core region 140 to the annular
region 142 may reduce variations in the internal stress field of
the monolithic polycrystalline diamond body 120, and/or may reduce
the occurrence of defects that would otherwise be introduced to the
polycrystalline diamond body because of a variation in a
characteristic property between the diamond grains of the core
region 140 and the diamond grains of the annular region 142.
[0063] In other embodiments in which sintering of the diamond
grains and/or non-diamond material has proven to be difficult,
incorporation of a diamond body having a core region 140 and an
annular region 142 may allow for enhanced sintering of the diamond
grains that are positioned in the annular region 142 as compared to
a diamond body that is free of various regions. In particular, it
is believed that the incorporation of the annular region 142 to a
polycrystalline diamond body 120 allows for a reduced volume of
difficult-to-sinter material that is sintered during the HPHT
process. Because the volume of diamond grains is relatively smaller
in the annular region 142, the distance through which catalyst
material is swept through difficult-to-sinter material is reduced.
Therefore, the incorporation of the annular region 142 may increase
the likelihood of high-quality sintering of difficult-to-sinter
materials and may reduce the amount of difficult-to-sinter
materials while maintaining the performance attribute offered by
the difficult-to-sinter material.
[0064] Additionally, when the polycrystalline diamond bodies are
used in down-hole drilling bits, the diamond grains of the annular
region 142 are typically subjected to more wear than the diamond
grains of the core region 140. Accordingly, by positioning diamond
grains with preferred mechanical properties (for example, highly
abrasion resistant, highly tough, highly thermally stable) in the
annular region 142, the benefits of those diamond grains can be
realized by the end user without the diamond grains of the core
region 140 having to share those properties. Therefore, the diamond
grains of the core region 140 and the diamond grains of the annular
region 142 may be selected to provide a desired combination of
mechanical properties that are beneficial to the end user.
[0065] In some embodiments, the intersection surface between the
core region and the annular region may have a single facet. In some
embodiments, the intersection surface may be generally linear when
evaluated along a centerline cross-section. In other embodiments,
the intersection surface may be generally curved. In some
embodiments, the intersection surface may include a plurality of
faceted linear portions. In other embodiments, the intersection
surface may include a plurality of smoothly-connected linear
portions. In some embodiments, the intersection surface between the
core region and the annular region may be normal to at least one of
the working surface, the perimeter surface, or the chamfer of the
PCD compact. In another embodiment, the intersection surface
between the core region and the annular region may be angled at a
non-normal orientation to all of the working surface, the perimeter
surface, and the chamfer of the PCD compact. In another embodiment,
the intersection surface between the core region and the annular
region may be angled at a non-normal orientation to all of the
working surface, the perimeter surface, and the chamfer of the PCD
compact at locations that project normally from the respective
working surface, the perimeter surface, and the chamfer. Note that
some variation in shape of the intersection surface is to be
expected due to the fabrication process, including due to
positioning of a substrate into a low-reactivity cup and the
pressures applied during an HPHT process.
[0066] In some embodiments, the intersection surface between the
core region and the annular region may extend a distance evaluated
along the centerline axis of the polycrystalline diamond body that
is at least 25% of a thickness of the polycrystalline diamond body,
as evaluated from the working surface to the interface surface,
being, for example, at least 50% of the thickness of the
polycrystalline diamond body, for example at least 75% of the
thickness of the polycrystalline diamond body, for example, at
least 85% of the thickness of the polycrystalline diamond body, up
to 100% of the thickness of the polycrystalline diamond body.
[0067] Referring now to FIGS. 7-9, another embodiment of an
apparatus for filling a low-reactivity cup 204 is depicted. The
apparatus includes a rotating table 222 onto which the
low-reactivity cup 204 is positioned. A conduit 220 is positioned
at least partially within the low-reactivity cup 204. The rotating
table 222, the low-reactivity cup 204, and the conduit 220
simultaneous spin about an axis of rotation of the rotating table
222. Diamond grains are fed through the opening 221 of the conduit
220, fall downward due to gravity, and are subjected to centripetal
acceleration that displaces the diamond grains outward due to the
rotation of the low-reactivity cup 204 on the rotating table 222.
Diamond grains may fill the open region between the low-reactivity
cup 204 and the conduit 220, including by moving in a direction
opposite gravity, such that the diamond grains extend to a position
above the lowest vertical position of the conduit 220. The diamond
grains that are loaded into the low-reactivity cup 204 through the
conduit 220 form the annular region 142 of the finished monolithic
polycrystalline diamond body 120.
[0068] Subsequent to positioning the diamond grains in
low-reactivity cup 204 through the conduit 220, the conduit 220 may
be removed from the low-reactivity cup 204. The low-reactivity cup
204 is subsequently filled with additional diamond grains, which
form the core region 140 of the finished monolithic polycrystalline
diamond body 120, that are positioned on top of the previously
placed diamond grains that form the annular region 142 finished
monolithic polycrystalline diamond body 120.
[0069] Similar to the previously discussed embodiment, the
reactivity cup 204 and the diamond grains positioned therein may be
positioned proximate to a catalyst material source, for example a
cobalt cemented tungsten carbide substrate. The low-reactivity cup
204 and the diamond grains may be subjected to a HPHT process in
which the low-reactivity cup 204 and the diamond grains are
subjected to conditions of elevated pressure and temperature
sufficient to cause the previously unbonded diamond grains to form
diamond-to-diamond bonds between one another. Following the
completion of the HPHT process, a recovered monolithic
polycrystalline diamond body 120 may be recovered from the HPHT
apparatus. The recovered polycrystalline diamond body 120 may
continue to exhibit a shape consistent with the shape of the
intersection between the annular region 142 and the core region 140
that was introduced to the unbonded diamond grains during loading
of the low-reactivity cup 204, as discussed above.
[0070] In yet another embodiment of the fabrication process (not
shown), unbonded diamond grains may be positioned in a
low-reactivity cup. Subsequently, a mandrel may be positioned to
enclose the low-reactivity cup, and the low reactivity cup, the
mandrel, and the low reactivity cup's contents may be positioned on
a rotating table and spun about an axis of rotation of the rotating
table. The diamond grains may fill the open regions between the
low-reactivity cup and the mandrel, including by moving in a
direction opposite gravity, such that the diamond grains extend to
a position above the lowest vertical position of the mandrel. The
low-reactivity cup and the diamond grains may be processed
according to the above-discussed fabrication embodiments to arrive
at a PCD compact.
[0071] In some embodiments, vibratory energy, for example,
ultrasonic vibratory energy, may be introduced to the unbonded
diamond grains to encourage even distribution prior to introduction
to the HPHT process. The vibratory energy may enhance distribution
of the unbonded diamond grains before, during, or after loading the
unbonded diamond grains into the low-reactivity cup, including, for
example, simultaneous spinning and vibrating of the low-reactivity
cup and the unbonded diamond grains positioned therein. In some
embodiments, the unbonded diamond grains may be distributed in the
low-reactivity cup using pneumatic or a hydraulic agitation. In
some embodiments, the unbonded diamond grains may be positioned
into the low-reactivity cup using a slurry loading technique in
which diamond grains are at least partially held in suspension in a
liquid vehicle.
[0072] In some embodiments, an annular region may be fabricated
into an at least semi-rigid body that has sufficient strength to
resist handling damage, and may be referred to as a green body. In
some embodiments, the strength of the green body may be provided by
a binder, for example an organic or an inorganic polymer. The green
body of the annular region may be positioned within the
low-reactivity cup. The low-reactivity cup may subsequently be
filled with unbonded diamond grains having a different
characteristic than the diamond grains of the green body, as
described in the above-discussed fabrication embodiments. The
low-reactivity cup and the diamond grains may be processed
according to the above-discussed fabrication embodiments to arrive
at a PCD compact. The binder of the green body, if any, may be
removed from the diamond grains during the HPHT process or in a
separate heating cycle of the diamond grains.
[0073] It should be understood that embodiments of the
polycrystalline diamond bodies 120 according to the present
disclosure may have a variety of shapes and configurations of the
annular region 142 and the core region 140 of the polycrystalline
diamond body 120. Examples of such shapes are depicted in FIGS.
10-15.
[0074] Referring to FIG. 10, the polycrystalline diamond body 120
exhibits an intersection 144 between the core region 140 and the
annular region 142, where the intersection 144 has a generally
frustoconical shape. In this embodiment, the intersection 144
extends from the working surface 130 of the polycrystalline diamond
body 120 to the substrate 110.
[0075] Referring now to FIG. 11, the polycrystalline diamond body
120 exhibits an intersection 144 between the core region 140 and
the annular region 142, where the intersection 144 has a generally
frustoconical shape. In this embodiment, the intersection 144
extends from the working surface 130 of the polycrystalline diamond
body 120 and is terminated at a longitudinal position short of the
substrate 110.
[0076] Referring now to FIG. 12, the polycrystalline diamond body
120 exhibits an intersection 144 between the core region 140 and
the annular region 142, where the intersection 144 has a generally
frustoconical shape. In this embodiment, the intersection 144
extends at a distance away from the working surface of the
polycrystalline diamond body 120 and terminates at the substrate
110. The intersection 144 between the core region 140 and the
annular region 142 is spaced apart from the working surface 130 at
radial positions inside of the frustoconical portion of the
intersection 144.
[0077] Referring now to FIG. 13, a polycrystalline diamond body 120
is depicted with a portion of the polycrystalline diamond body
removed for illustrative clarity. The polycrystalline diamond body
120 exhibits an intersection 144 between the core region 140 and
the annular region (not shown), where the intersection 144 has a
shape corresponding to a truncated pyramid. While the embodiment
depicted in FIG. 13 exhibits a truncated square pyramid, it should
be understood that other pyramidal frustums are contemplated,
including truncated triangular pyramids and truncated pentagonal
pyramids.
[0078] Referring now to FIG. 14, the polycrystalline diamond body
120 exhibits an intersection 144 between the core region 140 and
the annular region 142, where the intersection 144 has a shape
corresponding to a truncated paraboloid.
[0079] Referring now to FIG. 15, a polycrystalline diamond body 120
is depicted with a portion of the polycrystalline diamond body
removed for illustrative clarity. The polycrystalline diamond body
120 exhibits an intersection 144 between the core region 140 and
the annular region 142, where the intersection 144 has a shape
corresponding to a lobed truncated conical surface. In the
embodiment depicted in FIG. 15, the intersection shape 144 exhibits
a 4-lobed truncated conical surface. However, it should be
understood that other lobed truncated conical surfaces are
contemplated including 2-lobed truncated conical surfaces, 3-lobed
truncated conical surfaces, and 5-lobed truncated conical
surfaces.
[0080] Referring now to FIG. 16, an earth-boring tool 160 having at
least one PCD compact 100 according to the present disclosure is
depicted. The earth-boring tool 160 includes a bit body 162 having
a plurality of mounting surfaces. Each of the mounting surfaces is
positioned and oriented to present the PCD compact 100 for earth
removal in a down-hole drilling application.
EXAMPLES
Example A (Comparative Example)
[0081] Conventional polycrystalline diamond compacts having a
monolithic polycrystalline diamond body and a cobalt cemented
tungsten carbide substrate was produced in an HPHT process. The PCD
compacts were made from feed diamond grains having a uniform,
bimodal feed of about 93 vol. % diamond having a D50 of about 16
.mu.m and about 7 vol. % diamond having a D50 of about 1 .mu.m. A
cobalt cemented-tungsten carbide substrate was positioned to close
the low-reactivity cup. The cup was introduced to a belt-type HPHT
apparatus. The low-reactivity cup and its contents were subjected
to a maximum pressure of about 8 GPa and to a temperature above the
melting point of cobalt for about 6 minutes. Supported PCD compacts
were recovered from the HPHT apparatus and processed according to
conventional finishing operations to arrive at a cylindrical PCD
compact having a diameter of about 16 mm and a diamond table height
of about 2.1 mm.
[0082] The PCD compacts were subjected to a test that replicates
forces experienced by the polycrystalline diamond body in a
downhole drilling application. The PCD compacts were installed in a
vertical turret lathe ("VTL") and used to machine granite.
Parameters of the VTL test may be varied to replicate desired test
conditions. In one example, the PCD compacts were configured to
remove material from a Barre white granite workpiece. The PCD
compacts were positioned with a 15.degree. back-rake angle relative
to the workpiece surface. The PCD compacts were positioned at a
nominal depth of cut of 0.25 mm. The infeed of the PCD compacts was
set to a constant rate of 7.6 mm/revolution with the workpiece
rotating at 60 RPM. The PCD compacts were water cooled.
[0083] The VTL test introduces a wear scar into the PCD compacts
along the position of contact between the PCD compacts and the
granite. The size of the wear scar is compared to the material
removed from the granite workpiece to evaluate the abrasion
resistance of the PCD compacts. The respective performance of
multiple polycrystalline diamond bodies may be evaluated by
comparing the rate of wear scar growth and the material removal
from the granite workpiece. Abrasion resistance performance
captured by comparing the wear scar size to the volume of granite
machined by the PCD compacts of this and other examples is
reproduced in Table 1 below.
[0084] PCD compacts made according to the present example were also
subjected to a frontal impact test. PCD compacts were prepared with
a chamfer between the working surface and the perimeter surface.
The PCD compacts were rigidly held in a clamping fixture by
gripping on the outer diameter of the substrate, leaving a section
of the polycrystalline diamond body exposed. Using an Instron Model
instrument, the clamping fixture and the PCD compact were raised to
a designated height above an impact bar. The impact bar was
rectangular in shape with a square cross section, and made of steel
that was through-hardened to a hardness of 60 on the Rockwell C
scale. The height and mass of the clamping fixture and the PCD
compact determine the kinetic energy of an impact between the PCD
compact and the impact bar.
[0085] The PCD compact was positioned within the clamping fixture
so that when dropped onto the impact bar, the PCD compact impacts
at an angle of 15 degrees relative to the working surface of the
PCD compact. Restate, the axis of symmetry of the PCD compact is
aligned 15 degrees from normal with the contact surface of the
impact bar.
[0086] The test method evaluates the maximum kinetic energy
absorbed by the PCD compact before cracks are induced. A first
estimate of the maximum kinetic energy is set in a first impact. In
subsequent drops, the maximum kinetic energy is increased and/or
decreased and the PCD compact is rotated to determine the maximum
kinetic energy absorbed by the PCD compact before cracks are
induced. Multiple drops were completed at different clocking
locations of the PCD compacts to arrive at an average value of
energy absorbed. Frontal impact performance of the PCD compacts of
this and other examples is reproduced in Table 2 below and in FIG.
17.
Example B
[0087] PCD compacts according to the present disclosure were
fabricated having a core region of polycrystalline diamond and an
annular region of polycrystalline diamond. The PCD compacts were
made with a first population of diamond grains (that form an
annular region) having a bimodal feed of about 93 vol. % diamond
having a D50 of about 16 .mu.m and about 7 vol. % diamond having a
D50 of about 1 .mu.m. The PCD compacts had a second population of
diamond grains (that formed the core region) having a monomodal
feed of diamond having a D50 of about 20 .mu.m. The core region was
supplemented with about 1.3 wt. % bismuth powder, as evaluated
prior to the HPHT process. The diamond grains were introduced to
the low-reactivity cup was completed using a filling apparatus
having a rotating table, as depicted in FIGS. 7-9. These diamond
grains were fed into the low-reactivity cup and the diamond grains
exhibited a frustoconical shape that was complementary to the shape
of the conduit, and had a shape that corresponded to the embodiment
depicted in FIG. 11.
[0088] A cobalt cemented-tungsten carbide substrate was positioned
in the low-reactivity cup and against the diamond grains. A cell
assembly was built around the low-reactivity cup and substrate. The
cell assembly was inserted into a belt-type pressure apparatus
where the cell assembly and its contents were exposed to a HPHT
process. The cell assembly was subjected to a maximum pressure of
about 8 GPa and held above the melting temperature of cobalt for
about 6 minutes. The HPHT process produced a polycrystalline
diamond body that was integrally sintered to the substrate.
Supported PCD compacts were recovered from the HPHT apparatus and
processed according to conventional finishing operations to arrive
at a cylindrical PCD compact having a diameter of about 16 mm and a
diamond table height of about 2.1 mm.
[0089] A polycrystalline diamond body was destructively inspected
to evaluate the quality of the sinter reaction. In the
polycrystalline diamond body made according to Example B, body
exhibited complete sinter throughout the body. XRF analysis of the
polycrystalline diamond body indicated that bismuth was present in
all areas of the polycrystalline diamond body, including in regions
of the polycrystalline diamond corresponding to where no bismuth
was present prior to the HPHT process. As such, the XRF analysis
demonstrated that bismuth was swept into the first population of
diamond grains from the second population of diamond grains during
the HPHT process.
[0090] The PCD compacts according to this example were tested in
accordance with the above-referenced VLT test parameters. Abrasion
resistance performance captured by comparing the wear scar size to
the volume of granite machined by the PCD compacts of this example
is reproduced in Table 1 below. Cutters were impacted tested as
outlined in the previous example and the results are tabulated in
Table 2.
TABLE-US-00001 TABLE 1 Abrasion Resistance Test Results Granite
Machined Example A Example B (million mm.sup.3) PCD Wear (mm.sup.3)
4.2 0.13 0.08 8.4 0.28 0.13 12.5 0.90 0.20 16.7 1.84 0.37 20.9 3.99
1.34 25.1 5.86 2.74 29.2 8.63 4.52 33.4 13.77 5.80 37.6 7.00 41.8
8.77 45.9 11.10 50.1 13.77
TABLE-US-00002 TABLE 2 Impact Resistance Test Results Example A
Example B Average Maximum Energy Absorbed (J) 9.7 15.7
Example C
[0091] PCD compacts according to Example B were produced and
subsequently subjected to a leaching operation in which portions of
the polycrystalline diamond body were brought into intimate contact
with a leaching agent. The leaching agent successfully removed
substantially all of the cobalt (catalyst material) and bismuth
from the interstitial regions between bonded diamond grains that
were positioned proximate to the working surface of the PCD
compacts.
[0092] A PCD compact was sectioned and examined in a scanning
electron microscope. A micrograph taken from the SEM is reproduced
as FIG. 18. As depicted, the micrograph illustrates the leached
region in the darkest grey, the unleached annular region in the
intermediate grey, and the unleached core region in lightest
grey.
[0093] It should now be understood that polycrystalline diamond
bodies may include an annular region of inter-bonded diamond grains
that extends away from at least a portion of the working surface
and the perimeter surface of the polycrystalline diamond body and a
core region of inter-bonded diamond grains that are bonded to the
annular region. The diamond grains of the annular region may have a
first characteristic property, while the diamond grains of the core
region may have a second characteristic property that differs from
the first characteristic property. The variation between the
diamond grains of the annular region and the diamond grains of the
core region may allow for enhanced sweep of non-diamond materials
through the diamond grains during the HPHT process. The variation
between the diamond grains of the annular region and the diamond
grains of the core region may also allow for diamond grains to be
preferentially placed in the polycrystalline diamond body that
provides desirable mechanical properties for a chosen end user
application.
[0094] While reference has been made to specific embodiments, it is
apparent that other embodiments and variations can be devised by
others skilled in the art without departing from their spirit and
scope of this disclosure. The appended claims are intended to be
construed to include all such embodiments and equivalent
variations.
* * * * *