Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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ELEMENT CONTAINING THERMALLY STABLE POLYCRYSTALLINE DIAMOND
MATERIAL AND METHODS AND ASSEMBLIES FOR FORMATION THEREOF
TECHNICAL FIELD
The current disclosure relates to a super abrasive element containing a super-
abrasive body, such as a thermally stable polycrystalline diamond (TSP) body,
bonded to a base via an infiltrant material. In more specific embodiments, the
TSP
body may substantially free of infiltrant material, with only a small amount
present
near the TSP body surface in contact with the base. In some embodiments, the
infiltrant material may also permeate the base, where if may function as a
binder. The
current disclosure also relates to methods of forming a super abrasive element
containing a TSP body bonded to a base using an infiltrant material. In
particular
embodiments, the method may include forming a super abrasive element by
forming
the base in a mold also containing the TSP in the presence of the infiltrant
material.
BACKGROUND
Components of various industrial devices are often subjected to extreme
conditions, such as high impact contact with abrasive surfaces. For example,
such
extreme conditions are commonly encountered during subterranean drilling for
oil
extraction or mining purposes. Diamond, with its unsurpassed wear resistance,
is the
most effective material for earth drilling and similar activities that subject
components
to extreme conditions. Diamond is exceptionally hard, conducts heat away from
the
point of contact with the abrasive surface, and may provide other benefits in
such
conditions.
Diamond in its polycrystalline form has added toughness as compared to
single crystal diamond due to the random distribution of the diamond crystals,
which
avoids the particular planes of cleavage found in single diamond crystals.
Therefore,
polycrystalline diamond is frequently the preferred form of diamond in many
drilling
applications or other extreme conditions. Device elements have a longer usable
life in
these conditions if their surface layer is made of diamond, typically in the
form of a
polycrystalline diamond (PCD) compact, or another super abrasive material.
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Elements for use in harsh conditions may contain a PCD layer bonded to a
substrate. The manufacturing process for a traditional PCD is very exacting
and
expensive. The process is referred to as "growing" polycrystalline diamond
directly
onto a carbide substrate to form a polycrystalline diamond composite compact.
The
process involves placing a cemented carbide piece and diamond grains mixed
with a
catalyst binder into a container of a press and subjecting it to a press cycle
using
ultrahigh pressure and temperature conditions. The ultrahigh temperature and
pressure are required for the small diamond grains to form into an integral
polycrystalline diamond body. The resulting polycrystalline diamond body is
also
intimately bonded to the carbide piece, resulting in a composite compact in
the form
of a layer of polycrystalline diamond intimately bonded to a carbide
substrate.
A problem with PCD arises from the use of cobalt or other metal
catalyst/binder systems to facilitate polycrystalline diamond growth. After
crystalline
growth is complete, the catalyst/binder remains within pores of the
polycrystalline
diamond body. Because cobalt or other metal catalyst/binders have a higher
coefficient of thermal expansion than diamond, when the composite compact is
heated, e.g., during the brazing process by which the carbide portion is
attached to
another material, or during actual use, the metal catalyst/binder expands at a
higher
rate than the diamond. As a result, when the PCD is subjected to temperatures
above
a critical level, the expanding catalyst/binder causes fractures throughout
the
polycrystalline diamond structure. These fractures weaken the PCD and can
ultimately lead to damage to or failure.
As a result of these or other effects, it common to remove the catalyst from
part of the PCD layer, particularly the parts near the working surface. The
most
common process for catalyst removal uses a strong acid bath, although other
processes that employ alternative acids or electrolytic and liquid metal
techniques also
exist. In general, removal of the catalyst from the PCD layer using an acid-
based
method is referred to as leaching. Acid-based leaching typically occurs first
at the
outer surface of the PCD layer and proceeds inward. Thus, traditional elements
containing a leached PCD layer are often characterized as being leached to a
certain
depth from their surface. PCD, including regions of the PCD layer, from which
a
substantial portion of the catalyst has been leached is referred to as
thermally stable
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PCD (TSP). Examples of current leaching methods are provided in U.S.
4,224,380;
U.S. 7,712,553; U.S. 6,544,308; U.S. 20060060392 and related patents or
applications.
Acid-leaching leaching must also be controlled to avoid contact between
substrate or the interface between the substrate and the diamond layer and the
acids
used for leaching. Acids sufficient to leach polycrystalline diamond severely
degrade
the much less resistant substrate. Damage to the substrate undermines the
physical
integrity of the PCD element and may cause it to crack, fall apart, or suffer
other
physical failure while in use, which may also cause other damage.
The need to carefully control leaching of elements containing a PCD layer
significantly adds to the complications, time, and expense of PCD
manufacturing.
Additionally, leaching is typically performed on batches of PCD elements.
Testing to
ensure proper leaching is destructive and must be performed on a
representative
element from each batch. This requirement for destructive testing further adds
to
PCD element manufacturing costs.
Attempts have been made to avoid the problems of leaching a fully formed
element by separately leaching a PCD layer, then attaching it to a substrate.
However, these attempts have failed to produce usable elements. In particular,
the
methods of attaching the PCD layer to the substrate have failed during actual
use,
allowing the PCD layer to slip or detach. In particular, elements produced
using
brazing methods, such as those described in U.S. 4,850,523; U.S. 7,487,849,
and
related patents or applications, or mechanical locking methods such as those
described
in U.S. 7,533,740 or U.S. 4,629,373 and related patents or applications are
prone to
failure.
Other methods of bonding a PCD layer to a pre-formed substrate are described
in U.S. 7,845,438, but require melting of a material already present in the
substrate
and infiltration of the PCD layer by the material.
In still other methods, leached PCD layers have been attached directly to the
gage region of a bit by infiltrating the entire bit and at least a portion of
the PCD layer
with a binder material. Although these methods are suitable to attaching PCD
to a
gage region, where it need not be removed during the lifetime of the bit, they
are not
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suitable for placing PCD layers in the cutting regions of a bit, where
replacement or
rotation of the PCD is desirable for providing normal bit life.
Using still other methods, PCD elements, often referred to as geosets, have
been incorporated into the exterior portions of drill bits. Geosets are
typically coated
with a metal, such as nickel (Ni). Geoset coatings may provide various
benefits, such
as protection of the diamond at higher temperature and improved bonding to the
drill
bit matrix.
Accordingly, a need exists for an element, including a rotatable or
replaceable
element, having a leached PCD layer, such as a TSP body, attached to a base or
substrate sufficiently well to allow use of the element in high temperature
conditions
such as those encountered by cutting elements of an earth-boring drill bit.
SUMMARY
The disclosure, according to one embodiment, provides a super abrasive
element containing a substantially catalyst-free thermally stable
polycrystalline
diamond (TSP) body having pores and a contact surface, a base adjacent the
contact
surface of the TSP body; and an infiltrant material infiltrated in the base
and in the
pores of the TSP body at the contact surface.
According to another embodiment, the disclosure provides an earth-boring
drill bit containing such a super abrasive element in the form of a cutter.
According to still another embodiment, the disclosure provides an assembly
for forming a super abrasive element including a mold having a bottom, a
thermally
stable polycrystalline diamond (TSP) body having a contact surface and located
in the
bottom of the mold, a matrix powder disposed adjacent the contact surface and
above
the TSP body in the mold, and an infiltrant material disposed above the matrix
powder in the mold.
According to a further embodiment, the disclosure provides an assembly for
forming a super abrasive element including a mold, a thermally stable
polycrystalline
diamond (TSP) body having a contact surface and located in the mold, a matrix
powder disposed adjacent the contact surface in the mold, and an infiltrant or
binder
material disposed in the matrix powder in the mold.
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4a
In accordance with one aspect of the present invention, there is provided a
super abrasive
element comprising: a substantially catalyst-free thermally stable
polycrystalline diamond (TSP)
body having pores, a contact surface, and diamond grains having an average
grain size; a base
adjacent the contact surface of the TSP body; and an infiltrant material
infiltrated in the base and
in the pores of the TSP body at the contact surface to a depth from the
contact surface of less
than 100 nm or two average grain sizes or less.
In accordance with another aspect of the present invention, there is provided
an earth-
boring drill bit comprising a cutter, the cutter comprising a super abrasive
element comprising: a
substantially catalyst-free thermally stable polycrystalline diamond (TSP)
body having pores and
a contact surface; a base adjacent the contact surface of the TSP body; and a
non-catalyst alloy
infiltrant material infiltrated in the base and in the pores of the TSP body
at the contact surface,
wherein the TSP body contains diamond grains having an average grain size, and
wherein the
infiltrant material is infiltrated in the pores of the TSP body to a depth
from the contact surface of
less than 100 IIM or two average grain sizes or less.
In accordance with yet another aspect of the present invention, there is
provided an earth-
boring drill bit comprising a cutter, the cutter comprising a super abrasive
element comprising: a
substantially catalyst-free thermally stable polycrystalline diamond (TSP)
body having pores, a
contact surface, and diamond grains having an average grain size; a base
adjacent the contact
surface of the TSP body; and an infiltrant material infiltrated in the base
and in the pores of the
TSP body at the contact surface to a depth from the contact surface of less
than 100 nm or two
average grain sizes or less.
In accordance with still another aspect of the present invention, there is
provided a
method of forming a super abrasive element comprising: assembling an assembly
comprising: a
mold having a bottom; a thermally stable polycrystalline diamond (TSP) body
having pores and a
contact surface and located in the bottom of the mold, and diamond grains
having an average
grain size; a matrix powder disposed adjacent the contact surface and above
the TSP body in the
mold; and an infiltrant material disposed above the matrix powder in the mold;
heating the
assembly to a temperature at a pressure and for a time sufficient for the
infiltrant material to
infiltrate the matrix powder and pores of the TSP body to a depth of less than
100 [tm or two
average grain sizes or less; and cooling the assembly to form a super abrasive
element.
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4b
In accordance with yet still another aspect of the present invention, there is
provided a
method of forming a super abrasive element comprising: assembling an assembly
comprising: a
mold having a bottom; a thermally stable polycrystalline diamond (TSP) body
having pores and a
contact surface and located in the bottom of the mold, and diamond grain sizes
having an average
grain size; a matrix powder disposed adjacent the contact surface and above
the TSP body in the
mold; and an infiltrant material disposed in the matrix powder in the mold;
heating the assembly
to a temperature at a pressure and for a time sufficient for the infiltrant
material to infiltrate the
matrix powder and pores of the TSP body to a depth of less than 100 Rm or two
average grain
sizes; and cooling the assembly to form a super abrasive element.
The disclosure additionally provides a method of forming a super abrasive by
assembling
an assembly including a mold having a bottom, a thermally stable
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polycrystalline diamond (TSP) body having pores and a contact surface and
located in
the bottom of the mold, a matrix powder disposed adjacent the contact surface
and
above the TSP body in the mold, and an infiltrant material disposed above the
matrix
powder in the mold. The method further includes heating the assembly to a
5 temperature and for a time sufficient for the infiltrant material to
infiltrate the matrix
powder and pores of the TSP body, and cooling the assembly to form a super
abrasive
element.
The disclosure further provides an additional method of forming a super
abrasive element including assembling an assembly including a mold, a
thermally
stable polycrystalline diamond (TSP) body having pores and a contact surface
and
located in the mold, a matrix powder disposed adjacent the contact surface in
the
mold, and an infiltrant or binder material disposed in the matrix powder. The
method
also includes heating the assembly to a temperature and pressure and for a
time
sufficient for the infiltrant or binder material to infiltrate the matrix
powder to form a
base attached to the TSP body.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete understanding of the present embodiments and advantages
thereof may be acquired by referring to the following description taken in
conjunction
with the accompanying drawings, which depict embodiments of the present
disclosure, and in which like numbers refer to similar components, and in
which:
FIGURE 1 is a cross-sectional side view of an infiltration method assembly
for forming a super abrasive element containing a TSP body bonded to a base
via an
infiltrant material;
FIGURE 2 is a magnified cross-sectional view of a super abrasive element;
FIGURE 3 is a cross-sectional side view of a hot press method assembly for
forming a super abrasive element containing a TSP body bonded to a base via an
infiltrant material;
FIGURE 4 is a side view of a TSP body for use in one embodiment of the
present disclosure;
FIGURES 5A and 5B are top and side views of super abrasive elements;
FIGURE 6 is a side view of a carbide casting reinforcement for use in one
embodiment of the present disclosure;
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FIGURE 7 is a side view of a super abrasive element having a dovetail lock;
FIGURE 8 is a side view of a super abrasive element having a lateral lock; and
FIGURE 9 is a side view of a super abrasive element having a combined
dovetail and lateral lock.
DETAILED DESCRIPTION
The current disclosure relates to a super abrasive element containing a super
abrasive body, such as a thermally stable polycrystalline diamond (TSP) body
bound
to a base via an infiltrant material. The disclosure also relates to tools
containing
such super abrasive elements as well as methods of making such super abrasive
elements. In general, during methods of making super abrasive elements, the
super
abrasive properties of the super abrasive body, such as a TSP body, may remain
substantially unchanged or undeteriorated.
Although in the example embodiments described herein, superabrasive
elements are in a generally cylindrical shape with a flat surface, they may be
formed
in any shape suitable for their ultimate use, such as, in some embodiments, a
conical
shape, a variation of a cylindrical shape, or even with angles. Additionally,
the
surface of the superabrasive elements in some embodiments may be concave,
convex,
or irregular.
An assembly 10, as shown in FIGURE 1, may be provided for use in forming
a super abrasive element via an infiltration method. Assembly 10 may include
mold
20 intended to contain the components of the super abrasive element while it
is being
formed. TSP body 30 may be disposed within mold 20. TSP body 30 may
substantially lack catalyst used in forming the body. For instance, at least
85% of the
catalyst may be removed from the body. Matrix powder 40 may also be disposed
within mold 20 on top of TSP body 30. Finally, infiltrant material 50 may be
disposed within mold 20 on top of matrix powder 40.
To form a super abrasive element, assembly 10 may be subjected to a
formation process during which matrix powder 40 is infiltrated by infiltrant
material
50, which functions as a binder, and eventually forms a base. Infiltrant
material 50
wets the surface of TSP body 30 in contact with matrix powder 40 and fills
pores in
TSP body 30 at the surface, attaching TSP body 30 to the base. FIGURE 2 shows
a
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magnified image of a cross-section of a super abrasive element 60 that may be
formed. Super abrasive element 60 includes the TSP body 30 bound to a base 70
that
is formed from the matrix powder 40. In a particular embodiment, infiltrant
material
50 may be dispersed within base 70 as a binder and also infiltrate pores in
the contact
surface 100 of TSP body 30, which is in contact with base 70, to a depth of D
to form
infiltrant material-containing region 80. The remainder of TSP body 30 may
substantially lack binder and may form infiltrant-free region 90. Pores may be
engineered to allow the formation of a micromechanical bond between the base
and
the TSP rather than merely a metallurgical bond.
According to another embodiment (not shown) infiltrant material 50 may be
intermixed with matrix powder 40 prior to the formation process. In such an
embodiment, infiltrant material nevertheless infiltrates matrix powder 40 and
wets the
surface of TSP body 30, also filling in pores on that surface, to allow
attachment of
base 70 formed from matrix powder 40 to TSP body 30.
According to a further embodiment shown in FIGURE 3, a superabrasive
element 60 of the type depicted in FIGURE 2 may be formed using an assembly
10a
and a hot press method. Assembly 10a may include mold 20a intended to contain
the
components of the super abrasive element while it is being formed. TSP body 30
may
be disposed within mold 20a. Matrix powder 40a may be disposed within mold 20a
as well. Typically when using a hot press method, an infiltrant material is
intermixed
with the matrix powder prior to hot pressing. Accordingly, matrix powder 40a
may
additionally contain a binder material intermixed therein. The binder material
may be
an infiltrant material, or it may be a material not able to infiltrate TSP
body 30. In
instances where the binder material cannot infiltrate TSP body 30, or cannot
do so
sufficiently to attach it to base 70 after formation of the super abrasive
element, TSP
body 30 may be attached to base 70 primarily by mechanical forces resulting
from the
use of a hot press methodology. In other hot press embodiments, a disc of
infiltrant
material 50 may be placed on the matrix powder 40 and used to infiltrate the
matrix
powder, for instance under lower pressure.
In alternative embodiments, other infiltration methods, such as hot isostatic
pressing, may be used to infiltrate the matrix powder with infiltrant
material.
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Mold 20 used in assembly 10 may be made of any material suitable to
withstand the formation process and allow removal of the super abrasive
element
formed. According to a particular embodiment, mold 20 may contain a ceramic
material. Although mold 20 is shown with a flat bottom, in certain embodiments
(not
shown) it may be shaped to allow infiltrant material 50 to flow around the
sides of
TSP body 30, assisting in mechanical attachment of TSP body 30 to base 70.
Mold
20a may be any mold suitable to withstand a hot press cycle.
TSP body 30 may be in any shape suitable for use in super abrasive clement
60. In some embodiments, it may be in the form of a disk, as shown in FIGURE
4.
TSP body 30 may have a substantially planar contact surface (not shown).
However,
as shown in FIGURE 4, TSP body 30 may have features to mechanically enhance
its
attachment to base 70 in the super abrasive element 60. In particular, TSP
body 30
may have a non-planar contact surface 100 like that shown in FIGURE 4. The non-
planar contact surface 100 may contain non-planar features, such as grooves
110.
Grooves 110 may help prevent TSP body 30 from slipping from base 70 in
response
to a force applied at a right angle to the grooves. The non-planar contact
surface 100
may have angled regions, such as angled walls 120 of grooves 110. These angled
walls 120 may improve the mechanical connection between TSP body 30 and base
70
by interlocking the two components.
Additional configurations to increase the mechanical attachment of TSP body
to base 70 may also be used. Two examples of such configuration are shown in
FIGURES 5A and 5B. Further mechanical attachments mechanisms may include
prior mechanical TSP attachment mechanisms that proved unsuitable when used
alone
may be suitable when combined with attachment via infiltrant material 50 and
may
25 actually improve the overall attachments of TSP body 30 to base 70.
Example
mechanisms include those found in U.S. 7,533,740 or U.S. 4,629,373.
Other configurations that may increase mechanical attachment of
TSP body 30 to base 70 are shown in FIGURES 7, 8 and 9. Some such
configurations, such at that shown in FIGURE 9, may apply compressive forces
to the
30 TSP body, particularly during use.
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Specific mechanical configurations of TSP body 30 may be used when it is
attached to base 70 mechanically through a hot press formation method, rather
than
via an infiltrant material.
In addition to or alternatively to mechanically enhancing the attachment of
TSP body 30 the base 70, features of contact surface 100 may also increase the
contact surface area in contact with matrix powder 40 before formation of
super
abrasive element 60, or in contact with base 70 after formation of super
abrasive
element 60. In particular, a non-planar contact surface 100 may increase the
contact
surface area. A larger contact surface area may improve bonding of TSP body 30
to
base 70 by providing more pores adjacent the matrix powder 40 to be
infiltrated by
infiltrant material 50 or otherwise by increasing the surface wet by
infiltrant material
50 during the formation process.
In some embodiments, the number or volume of pores at contact surface 100
may also help improve attachment of TSP body 30 to base 70 by providing more
surface area for infiltrant material 50 to wet and attach to.
TSP body 30 may be any PCD leached sufficiently to be thermally stable. At
temperatures suitable to allow infiltrant material 50 to infiltrate matrix
powder 40 and
to wet and infiltrate contact surface 100 or for some hot pressing techniques,
remaining catalyst in PCD material that is not sufficiently leached will cause
the
material to graphitize to carbon, weakening it to the point where it is not
suitable for
use in a super abrasive element or possibly even causing it to disintegrate.
Leaching
of the TSP body may be performed prior to its placement in assembly 10 or 10a
and
prior to the formation of super abrasive element 60. TSP body 30 may be formed
using standard techniques for creating a PCD layer. In particular, it may be
formed
by combining grains of natural or synthetic diamond crystal with a catalyst
and
subjecting the mixture to high temperature and pressure to form a PCD attached
to or
separate from any substrate. The PCD may contain a diamond body matrix and an
interstitial matrix containing the catalyst. According to particular
embodiments, the
catalyst may include a Group VIII metal, particularly cobalt (Co).
The PCD may then be leached by any process able to remove the catalyst from
the interstitial matrix. The leaching process may also remove the substrate,
if any is
present. In some embodiment, at least a portion of the substrate may be
removed
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prior to leaching, for example by grinding. In particular embodiments, the PCD
may
be leached using an acid. The leaching process may differ from traditional
leaching
processes in that there is no need to protect any substrate or boundary
regions from
leaching. For example, it may be possible to simply place the PCD or
PCD/substrate
5 combination into an acid bath with none of the protective components
typically
employed. Even the design of the acid bath may differ from traditional acid
baths. In
many processes for use with the present disclosure a simple vat of acid may be
used.
An alternative leaching method using a Lewis acid-based leaching agent may
also be employed. In such a method, the PCD containing catalyst may be placed
in
10 the Lewis acid-based leaching agent until the desired amount of catalyst
has been
removed. This method may be conducted at lower temperature and pressure than
traditional leaching methods. The Lewis acid-based leaching agent may include
ferric
chloride (FeC13), cupric chloride (CuC12), and optionally hydrochloric acid
(HCI), or
nitric acid (HNO3), solutions thereof, and combinations thereof. An example of
such
a leaching method may be found in US 13/168,733 by Ram Ladi et al., filed June
24,
2011, and titled "CHEMICAL AGENTS FOR LEACHING POLYCRYSTALLINE
DIAMOND ELEMENTS " .
When catalyst is removed from the interstitial matrix, pores are left where
the
catalyst used to be located. The percent leaching of a PCD may be
characterized as
the overall percentage of catalyst that has been removed to leave behind a
pore.
Although, as noted above, a gradient in the degree of leaching may be present
from
the surface of the PCD inwards, the average amount of leaching for a PCD may
nevertheless be determined. According to specific embodiments of the current
disclosure TSP body 30 may include a PCD which is substantially free of
catalyst.
More specifically, the TSP body may include a PCD from which at least 85%, at
least
90%, at least 95%, or at least 99% of the catalyst has been leached on
average.
In certain embodiments, TSP body 30 may have a uniform diamond grain size,
but in other embodiments, the grain size may within the TSP body. For example,
in
some embodiments TSP body 30 may contain larger diamond grains near contact
surface 100 in order to produce more pores, or larger volume pores, thereby
providing
more surface area to contact infiltrant material 50. In certain embodiments,
these
larger diamond grains may form an attachment layer (not shown) in TSP body 30.
In
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other embodiments, diamond density may be less in an attachment layer.
Difficulties
in wetting diamond often pose a challenge in attaching TSP body 30 to base 70,
so the
lower diamond density may aid attachment by improving wetting of contact
surface
100.
In still other embodiments, TSP body 30 may contain an attachment layer
formed by a different material, such as a carbide former, particularly W2C ,
or a
material containing only low amounts of diamond as compared to the TSP body.
In
one embodiment, such an attachment layer may be placed on the TSP body prior
for
formation of the super abrasive element. Due to the destructive tendencies of
leaching, such an attachment layer may be placed on TSP body 30 after it has
been
leached. In another embodiment, the attachment layer may be formed during
super
abrasive element formation by a separate material layer between matrix powder
40
and TSP body 30. In either embodiment, the attachment layer may be attached to
the
TSP body sufficiently to remain intact during use of the super abrasive
element, but
may offer improved attachment to base 70. For instance, the attachment layer
may be
more easily wet by infiltrant material 50, or may form a stronger attachment
to
infiltrant material 50 than TSP does.
Matrix powder 40 or 40a may be a powder or any other material suitable to
form base 70 after infiltration with infiltrant material 50, which may
function as a
binder. In particular embodiments, matrix powder 40 or 40a may be a material
commonly used to form substrates of conventional PCD elements. Matrix powder
40
or 40a may also provide beneficial properties to base 70, such as rigidity,
erosion
resistance, toughness, and each of attachment to TSP body 30. For example, it
may
be a carbide-containing or carbide-forming powder. Base 70 will typically have
a
higher content of infiltrant material 50 than conventional PCD element
substrates
have of similar materials. As a result, base 70 may be less erosion-resistant
than
conventional substrates. Certain powder blends may be used as matrix powder 40
to
improve erosion resistance of base 70. In specific embodiments, powder blends
may
contain carbide, tungsten (W), tungsten carbide (WC or W2C), synthetic
diamond,
natural diamond, chromium (Cr), iron (Fe), nickel (Ni), or other materials
able to
increase erosion resistance of base 70. Powder blends may also include copper
(Cu),
manganese (Mn), phosphorus (P), oxygen (0), zinc (Zn), tin (Sn), cadmium (Cd),
lead
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(Pb), bismuth (Bi), or tellurium (Te). Matrix powder can contain any
combinations or
mixtures of the above-identified materials.
In some embodiments, matrix powder 40 or 40a may have a substantially
uniform particle size. However, in other embodiments, particle size of matrix
powder
40 or 40a may vary depending of the desired properties of base 70 or to
facilitate
attachment of base 70 to TSP body 30 either by infiltration or mechanical
means. For
example, infiltration methods such as those using assembly 10, a layer of
matrix
powder 40 with smaller particle size may be placed adjacent to TSP body 30.
The
smaller particle size may allow infiltrant material 50 to form a stronger
attachment by
allowing more infiltrant material 50 to reach contact surface 100. Typically
particles
of matrix powder 40 or 40a will be on a micrometer or nanometer scale. For
example,
average particle diameter may be greater than or equal to 5 gm, such as 5-6
gm. It
may be much higher, such as 100 gm. These particle sized may represent the
average
diameter of particles found in a portion of base 70 extending half of the
total length of
base 70 from TSP body 30. Overall, particle size of matrix powder 40 or 40a
may be
substantially larger than permissible particle size in pre-formed substrates.
Although appropriate materials are commonly in a powder form, in some
embodiments matrix powder 40 or 40a may be substituted with a non-powder
material
so long as the material is sufficient to be infiltrated with infiltrant
material 50, form
base 70, and substantially conform to contact surface 100 of TSP body 30.
Infiltrant material 50 may include any material able to infiltrate matrix
powder 40 or 40 a to form base 70. In hot press methods such as those using
assembly 10a, infiltrant material 50 may be mixed with matrix powder 40a prior
to
hot pressing. In infiltration methods such as those using assembly 10, and
potentially,
but not necessarily also in some hot press methods, infiltrant material 50 may
also to
wet contact surface 100 and infiltrate at least a sufficient number of pores
located at
contact surface 100 of TSP body 30 to cause bonding of TSP body 30 to base 70
via
infiltrant material 50. In particular embodiments, infiltrant material 50 may
be a
material having an affinity for diamond such that it readily wets contact
surface 100
or is readily drawn into pores via capillary action or a similar attractive
effect. In
more specific embodiments, infiltrant material 50 may include a material
suitable for
use as a catalyst in PCD formation, such as a Group VIII metal, for example
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manganese (Mn) or chromium (Cr). Infiltrant material 50 may also be a carbide
or
material used in the formation of carbide, such as titanium (Ti) alloyed with
copper
(Cu) or silver (Ag). In certain embodiments, infiltrant material 50 may be a
different
material than was used as the catalyst during formation of the PCD later
leached to
form the TSP body. This allows easy detection of catalyst separate from
binder.
However, in other embodiments, the infiltrant material and catalyst may be the
same.
In specific embodiments, infiltrant material 50 may be an alloy, such as a
nickel (Ni) alloy or another metal alloy, such as a Group VIII metal alloy..
Benefits
in melt temperature may make alloys suitable as infiltrant materials, even
when such
alloys would not be suitable as catalyst materials in PCD formation.
After formation of super abrasive element 60, infiltrant material 50 may be
found in base 70, where it may function as a binder. Infiltrant material 50
may also
be found in TSP body 30 near contact surface 100 in filled pores. In some
embodiments, infiltrant material 50 may be substantially confined to contact
surface
100 and pores that open to that surface. However, in other embodiments,
infiltrant
material 50 may also enter pores near contact surface 100. The portion of TSP
body
30 containing infiltrant material 50 may form the infiltrant material-
containing region
80, while the remainder of the TSP body 30 substantially lacking binder may
form
infiltrant-free region 90. According to a specific embodiment, a depth, D to
which
infiltrant material 50 penetrates the TSP body 30 from contact surface 100 may
on
average be any depth sufficient to allow bonding of TSP body 30 to base 70. In
particular embodiments it may be no more than 100 gm. In other particular
embodiments, it may be no more than four grain sizes, no more than two grain
sizes,
no more than one grain size, no more than half a grain size, or no more than
one
quarter a grain size, in which grain size refers to the diamond grains at or
near contact
surface 100. In still other embodiments, infiltrant material 50 may only
penetrate
exposed pore space on contact surface 100.
Infiltrant material 50 may confer properties on TSP body 30 similar to
properties conferred on a PCD by catalyst. In particular, infiltrant material
50 may
decrease the abrasion resistance and thermal stability of regions of the TSP
body in
which it is found. In example embodiments, to minimize the negative effects of
infiltrant material 50 on abrasion resistance and thermal stability, it may be
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advantageous to decrease or minimize the depth D of infiltrant material-
containing
region 80 to the amount sufficient to bond TSP body 30 to base 70.
Without limiting the bonding mechanism of infiltrant material 50, according to
certain embodiments, the manner in which infiltrant material 50 bonds TSP body
30
to base 70 may include the formation of a physically continuous matrix of
infiltrant
material between TSP body 30 and base 70.
Matrix powder 40 or 40a may be formed into base 70 using any appropriate
formation process. In particular embodiments, the formation process may
provide
one-step base formation and attachment, instead of requiring separate
formation and
attachment steps like some prior processes.
In one embodiment, the formation process may be a one-step infiltration
process. In general, in such a process (and also in any hot press process also
relying
on infiltration of TSP body 30 by infiltrant material 50 to attach it to base
70), any
material on contact surface 100 other than diamond may interfere with wetting
and
attachment by infiltrant material 50, so prior to incorporation in assembly
10, in
certain embodiments, contact surface 100 of TSP body 30 may be cleaned.
Assembly
10 may be assembled as described above and then placed in a furnace and heated
to a
temperature and for a time sufficient to cause infiltration of matrix powder
40 and
TSP body 30 with infiltrant material 50 and casting of matrix powder 40 into
base 70.
Specifically, the furnace may be heated to a temperature at or above the
infiltration
temperature of infiltrant material 50. The minimum temperature able to allow
infiltration of infiltrant material 50 may be referred to as the infiltration
temperature.
The time spent at or above the infiltration temperature may be the minimum
amount
required to allow infiltration of matrix powder 40 to form base 70 and
attachment of
base 70 to TSP body 30. In certain embodiments, the time spent at or above the
infiltration temperature may be 60 seconds or less. In order to prevent
oxidation
reactions or contamination of infiltrant material 50 or matrix powder 40
during the
formation process, the process make take place under vacuum or in the presence
of an
oxygen-free atmosphere, such as a reducing or inert atmosphere.
According to a specific embodiment, infiltrant material 50 may travel through
matrix powder 40 due to attractive forces, such as capillary action. Upon
reaching
contact surface 100 of TSP body 30, infiltrant material 50 may wet the surface
and
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bond to it. In particular embodiments, infiltrant material 50 enter open pores
and fill
them to form filled pores. Infiltrant material 50 may be drawn into pores via
an
attractive force, such as capillary action. This is particularly true if
infiltrant material
50 is selected to have an affinity for diamond.
5 After heating, assembly 10 may be removed from the furnace and cooled to
a
temperature below the infiltration temperature. Cooling, in certain
embodiments, may
be carefully controlled in order to reduce or minimize any weakening of the
attachment between base 70 and TSP body 30. For instance, it may be managed to
reduce or minimize any residual stresses. Finally, super abrasive element 60
may be
10 removed from mold 20.
According to another embodiment, assembly 10a may be used to form a
superabrasive element 60 via a one-step hot press method. As noted above, in
some
embodiments forces generated by hot press methods may provide sufficient
mechanical attachment of TSP body 30 to base 70 that attachment via the
infiltration
15 material is not required or is of minimal impact. In such embodiments,
TSP body 30
may be shaped so as to facilitate such mechanical attachment. For instance, it
may
have a shape shown in FIGURES 4 and 5. In other embodiments, even when a hot
press method is used, attachment of TSP body 30 to base 70 may partially or
substantially rely on infiltration of TSP body 30 with infiltrant material 50.
If such
embodiments any material on contact surface 100 other than diamond may
interfere
with wetting and attachment by infiltrant material 50, such that prior to
incorporation
in assembly 10a, contact surface 100 of TSP body 30 may be cleaned.
After cleaning, if conducted, TSP body 30 may be loaded into hot press mold
20a then packed with matrix powder 40a, which may contain both a matrix
material
and an infiltration material or binder. The mold may then be closed and
subjected to
hot pressing at a temperature and pressure sufficient to melt the infiltrant
material or
binder and allow it to form substrate 70. In embodiments where infiltrant
material
infiltrates TSP body 30, the temperature and pressure may also be sufficient
to allow
this infiltration to occur. In certain embodiments, hot pressing may involve a
cycle of
changing temperature and pressure over time.
According to certain embodiments, hot pressing may be conducted under an
inert or reducing atmosphere to prevent or reduce damage to TSP body 30.
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Alternatively, temperature may be carefully controlled to prevent oxidation of
TSP
body 30.
Hot pressing may be used to form a single super abrasive element 60 or
multiple assemblies 10a may be processed as the same time to simultaneously
form
multiple super abrasive elements 60. In either case, each super abrasive
element
maybe removed from mold 20a after completion of hot pressing.
In either infiltration process, the temperature and pressure used may be
outside
of the traditional diamond-stable region. The temperature and pressures at
which
PCD degrades to graphite are known in the art and described in the literature.
For
instance, the diamond-stable region may be determined through reference to
Bundy et
al.. "Diamond-Graphite Equilibrium Line from Growth and Graphitization of
Diamond," J. of Chemical Physics, 35(2):383-391 (1961), Kennedy and Kennedy,
"the Equilibrium Boundary Between Graphite and Diamond," J. of Geophysical
Res.,
81(14): 2467-2470 (1976), and Bundy, etal., "The Pressure-Temperature Phase
and
Transformation Diagram for Carbon; Updated through 1994," Carbon 34(2):141-153
(1996). The
highly
stable nature of TSP may allow it to withstand temperature and pressures
outside of
the diamond-stable region for the time needed to form superabrasive clement
60. For
instance, at pressured used in infiltration processes, temperatures may reach
as high as
1100 C or 1200 C.
In general, if pressure is carefully controlled, an infiltrant with a higher
melt
temperature may be used, reducing the likelihood of infiltrant melting during
downhole conditions or other harsh conditions.
Although use of temperatures and pressures outside of the diamond stable
region is possible, in many embodiments, such as some hot press methods,
temperatures and pressures may be within the diamond stable region. For
example,
some hot press techniques may employ temperatures of between 850 C - 900 C,
particularly 870 C.
In addition to causing a decrease in erosion resistance as noted above, the
presence of additional infiltrant material 50 in base 70 as compared to
similar
amounts of catalyst or binder in a conventional PCD element substrate causes
base 70
to be less stiff than a conventional substrate. This may result in increased
bending
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stresses on TSP body 30 when super abrasive element 60 is in use. In order to
increase the stiffness of base 70, a carbide insert 140 as shown in FIGURE 6
may be
included in base 70. Carbide insert 140 may be formed of a binderless or near
binderless carbide and may be resistant to infiltration by infiltrant material
50.
Carbide insert 140 may be placed within matrix powder 40 in assembly 10. After
formation of super abrasive element 60, carbide insert 140 may be present in
base 70
in essentially the same configuration as it was placed in matrix powder 40. In
addition to increasing the stiffness of base 70, carbide insert 140 may be
exposed on
the non-TSP body end of super abrasive element 60 after grinding and may then
serve
as an attachment point in a brazing process or a guide for rotation or
placement of the
super abrasive element. In an alternative embodiment, the insert may be formed
for
another suitable material other than carbide, such as a ceramic.
Super abrasive elements of the current disclosure may be in the form of any
element that benefits from a TSP surface. In particular embodiments they may
be
cutters for earth-boring drill bits or components of industrial tools.
Embodiments of
the current disclosure also include tools containing super abrasive elements
of the
disclosure. Specific embodiments include industrial tools and earth-boring
drill bits,
such as fixed cutter drill bits. Other specific embodiments include wear
elements,
bearings, or nozzles for high pressure fluids.
Due to the ability to leach TSP body 30 more than a PCD layer may typically
be leached when bound to a substrate, super abrasive elements of the current
disclosure may be usable in conditions in which more elements with a
traditional
leached PCD layer are not. For instance, super abrasive elements may be used
at
higher temperatures than similar elements with a traditional leached PCD
layer.
When super abrasive elements of the current disclosure are used as cutters on
earth-boring drill bits, they may be used in place of any traditional leached
PCD
cutter. In many embodiments, they may be attached to the bits via base 70. For
instance, base 70 may be attached to a cavity in the bit via brazing.
When used in cutting portions of a bit, the working surface of the cutter will
wear more quickly than other portions of TSP body 30. When a circular cutter,
such
as that shown in FIGURE 2 is used, the cutter may be rotated to move the worn
TSP
away from the working surface and to move unused TSP to the working surface.
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Circular cutters according to the present disclosure may be rotated in this
fashion at
least two times and often three times before they are too worn for further
use. The
methods of attachment and rotation may be any methods employed with
traditional
leached PCD cutters or other methods. Similarly, non-circular cutters may be
indexable, allowing their movement to replace a worn working surface without
replacing the entire cutter.
In embodiments using an insert with the shape shown in FIGURE 6 or another
suitable shape, the insert may be used as a guide for alignment of the working
surface
such that the working surface will receive additional support from the insert
during
use of the super abrasive element. For instance, when using an insert in the
shape
shown in FIGURE 6, the element may be aligned such that its working surface is
substantially along one of the insert arms and not in between the arms.
In addition to being rotatable, traditional PCD cutters may also be removed
from a bit. This allows worn or broken cutters to be replaced or allows their
replacement with different cutters more optimal for the rock formation being
drilled.
This ability to replace cutters greatly extends the usable life of the earth
boring drill
bit overall and allows it to be adapted for use in different rock formations.
Cutters
formed using super abrasive elements according to this disclosure may also be
removed and replaced using any methods employed with traditional leached PCD
cutters.
In certain other embodiments, super abrasive elements of the current
disclosure may be used in directing fluid flow or for erosion control in an
earth-boring
drill bit. For instance, they may be used in the place of abrasive structures
described
in U.S. 7,730,976; U.S. 6,510,906; or U.S. 6,843,333.
Although only exemplary embodiments of the invention are specifically
described above, it will be appreciated that modifications and variations of
these
examples are possible. For example, although Super abrasive elements are
discussed in detail other elements containing a similar component, such as
leached
cubic boron nitride, and similar method of forming such elements are also
possible.
The scope of the claims should not be limited by the preferred embodiments set
forth in the examples, but should be given the broadest interpretation
consistent
with the description as a whole.
