Note: Descriptions are shown in the official language in which they were submitted.
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ULTRA-HARD CONSTRUCTIONS WITH IMPROVED ATTACHMENT STRENGTH
BACKGROUND
The use of constructions comprising ultra-hard and metallic components that
are joined
together is well known in the art. An example of such may be found in the form
of cutting
elements comprising an ultra-hard component that is joined to a metallic
component. In such
cutting element embodiment, the wear or cutting portion is formed from the
ultra-hard
component and the metallic portion of the cutting element is attached to the
wear and/or
cutting device. In such known constructions, the ultra-hard component may be
formed from a
polycrystalline material such as polycrystalline diamond (PCD),
polycrystalline cubic boron
nitride (PcBN), or the like, that has a degree of wear and/or abrasion
resistance that is greater
than that of the metallic component.
In particular examples, the ultra-hard component may be PCD that has been
treated so
that it is substantially free of a catalyst material, e.g., a Group VIII metal
from the Periodic table,
that was used to form/sinter the same at high-pressure/high-temperature
conditions, and that
comprises bonded-together diamond crystals. PCD that has been rendered
substantially free of
the catalyst material is referred to as thermally stable polycrystalline
diamond (TSP), as removal
of the catalyst material has been found to improve the thermal stability of
the resulting
diamond body by eliminating unwanted degradation and thermal expansion
mismatches that
with increasing temperature may adversely impact the effective service life of
the diamond
body.
While TSP provides desired improvements in thermal stability, a problem known
to exist
with TSP is that its lack of catalyst material within the body operates to
preclude subsequent
attachment of the TSP body to a metallic substrate by solvent catalyst
infiltration. Further, such
TSP bodies have a coefficient of thermal expansion that is sufficiently
different from that of
conventional substrate materials (such as cermets like WC--Co and the like)
that are typically
infiltrated or otherwise attached to a PCD body. Attaching such substrates to
the TSP body is
highly desired to provide a TSP compact that may be readily adapted for use in
many desirable
applications. However, the difference in thermal expansion between the TSP
body and the
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substrate, and the poor wettability of the TSP body due to the substantial
absence of the
catalyst material, makes it very difficult to bond the TSP body to
conventionally used
substrates. Thus, some TSP bodies are attached or mounted directly to the
desired end-use
device without the presence of an adjoining substrate.
It is known that TSP bodies may be attached to a desired metallic substrate
through the
use of active braze materials, which are known to have relatively low melting
temperature and
low yield strengths. Combining the known limitations of active braze materials
with the
inherently poor wettability of the TSP body, the braze joint attachment that
is formed between
the TSP body and the substrate is one that is not as strong as the attachment
bond formed
between conventional PCD and a metallic substrate by infiltration. The
resulting construction is
one having a diminished service life due to the low yield strength of the
braze material, which
leads to delamination between the TSP body and the substrate during service.
SUMMARY
Ultra-hard construction disclosed herein comprise a diamond-bonded body
comprising a
matrix phase of bonded-together diamond grains and a plurality of interstitial
regions
interposed between the bonded-together diamond grains. The interstitial
regions are
substantially free of a catalyst material used to sinter the diamond-bonded
body at high-
pressure/high-temperature conditions. A metal material is disposed on a
substrate interface
surface of the diamond body. In an example embodiment, the metal material has
a carbide
constituent. In an example embodiment, the metal material has a layer
thickness in the range
of from about 0.1 to 10 microns. The construction further includes a substrate
connected with
the diamond-bonded body. The substrate may comprise a carbide constituent. The
substrate
is attached to the diamond-bonded body through a braze joint interposed
between the metal
material and the substrate. The braze joint is formed from a non-active braze
material that
reacts with the substrate and metal material. In an example embodiment, the
braze joint is
formed at the melting temperature of the non-active braze material in the
absence of high-
pressure conditions. The diamond-bonded body of such ultra-hard constructions
is made at
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high-pressure/high-temperature conditions. A substrate interface surface of
the so-formed
body is treated to include the metal material layer thereon. A metallic
substrate is attached to
the diamond-bonded body by the braze joint comprising the non-active braze
material at
approximately the melting temperature of the braze material in the absence of
high-pressure
conditions. If desired, a carburizing treatment can be performed prior
attaching the substrate.
This summary is provided to introduce a selection of concepts that are further
described below
in the detailed description. This summary is not intended to identify key or
essential features of
the claimed subject matter, nor is it intended to be used as an aid in
limiting the scope of the
claimed subject matter.
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BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of ultra-hard constructions are described with reference to the
following
figures:
FIG. 1 is view taken from a section of a diamond-bonded body after it has been
treated
to remove a catalyst material used to form the same therefrom;
FIG. 2 is a perspective view of the diamond-bonded body after it has been
treated to
remove the catalyst material used to form the same therefrom;
FIG. 3 is a cross-sectional side view of a diamond-bonded body comprising a
metal
material disposed on to a body substrate interface surface;
FIG. 4 is a cross-sectional side view of an ultra-hard construction as
disclosed herein
comprising a diamond-bonded body comprising a metal material disposed on to a
body
substrate interface surface, and further comprising a braze material forming a
braze joint
interposed between and bonding a substrate to the body;
FIG. 5 is a side view of an ultra-hard construction as disclosed herein
embodied in the
form of an insert;
FIG. 6 is a perspective side view of a rotary cone drill bit comprising a
number of the
inserts illustrated in FIG. 5;
FIG. 7 is a perspective side view of percussion or hammer bit comprising a
number of
inserts illustrated in FIG. 5;
FIG. 8 is a perspective view of an ultra-hard construction as disclosed herein
embodied
in the form of a shear cutter; and
FIG. 9 is a perspective side view of a drag bit comprising a number of the
shear cutters
illustrated in FIG. 8.
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DETAILED DESCRIPTION
Ultra-hard and metallic constructions as disclosed herein comprise a thermally
stable
polycrystalline diamond (TSP) bonded body that is substantially free of a
catalyst material
initially used to sinter the body, and that is specially engineered to
accommodate attachment
with a substrate or end-use device by a braze joint in a manner that provides
an enhanced
degree of attachment strength therewith when compared to conventional TSP
constructions.
As used herein, the term "ultra-hard" is understood to refer to those
materials known in
the art to have a grain hardness of about 4,000 HV or greater. Such ultra-hard
materials may
include those capable of demonstrating physical stability at temperatures
above about 750 C,
and for certain applications above about 1,000 C, that are formed from
consolidated materials.
Such ultra-hard materials may include but are not limited to diamond, cubic
boron nitride
(cBN), diamond-like carbon, boron suboxide, aluminum manganese boride, and
other materials
in the boron-nitrogen-carbon phase diagram which have shown hardness values
similar to cBN
and other ceramic materials.
Polycrystalline diamond (PCD) is a useful material for forming the ultra-hard
component
once it has been treated to remove a catalyst material, such as the Group VIII
materials noted
above, used to initially sinter or form the same at high-pressure/high-
temperature (HPHT)
conditions. As used herein, the term "catalyst material" refers to the
material that was initially
used to facilitate diamond-to-diamond bonding or sintering at the initial HPHT
process
conditions used to form the PCD.
TSP has a material microstructure characterized by a polycrystalline matrix
phase
comprising bonded-together diamond grains or crystals, and a plurality of
voids or empty pores
that exist within interstitial regions within the matrix disposed between the
bonded-together
diamond grains. The TSP material is initially formed by bonding together
adjacent diamond
grains or crystals at HPHT process conditions. The bonding together of the
diamond grains at
HPHT conditions is facilitated by the use of an appropriate catalyst material,
such as a metal
solvent catalyst selected from Group VIII of the Periodic table, thereby
forming conventional
PCD comprising the catalyst material disposed within the plurality of voids or
pores.
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Diamond grains useful for forming the TSP component or body may include
natural
and/or synthetic diamond powders having an average diameter grain size in the
range of from
submicrometer in size to 100 micrometers, and in the range of from about 1 to
80 micrometers.
The diamond powder may contain grains having a mono or multi-modal size
distribution. In an
example embodiment, the diamond powder has an average particle grain size of
approximately
20 micrometers. In the event that diamond powders are used having differently
sized grains,
the diamond grains are mixed together by conventional process, such as by ball
or attritor
milling for as much time as necessary to ensure good uniform distribution.
The diamond grain powder is cleaned, to enhance the sinterability of the
powder by
treatment at high temperature, in a vacuum or reducing atmosphere. The diamond
powder
mixture is loaded into a desired container for placement within a suitable
HPHT consolidation
and sintering device.
The diamond powder may be combined with a desired catalyst material, e.g., a
solvent
metal catalyst, in the form of a powder to facilitate diamond bonding during
the HPHT process
and/or the catalyst material may be provided by infiltration from a substrate
positioned
adjacent the diamond powder and that includes the catalyst material. Suitable
substrates
useful as a source for infiltrating the catalyst material may include those
used to form
conventional PCD materials, and may be provided in powder, green state, and/or
already
sintered form. A feature of such substrate is that it includes a metal solvent
catalyst that is
capable of melting and infiltrating into the adjacent volume of diamond powder
to facilitate
bonding the diamond grains together during the HPHT process. In an example
embodiment,
the catalyst material is cobalt (Co), and a substrate useful for providing the
same is a Co
containing cermet material, such as WC--Co.
The diamond powder mixture may be provided in the form of a green-state part
or
mixture comprising diamond powder that is combined with a binding agent to
provide a
conformable material product, e.g., in the form of diamond tape or other
formable/conformable diamond mixture product to facilitate the manufacturing
process. In the
event that the diamond powder is provided in the form of such a green-state
part, it is desirable
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that a preheating step take place before HPHT consolidation and sintering to
drive off the
binder material. In an example embodiment, the PCD material resulting from the
above-
described HPHT process may have diamond volume content in the range of from
about 85 to 95
percent.
The diamond powder mixture or green-state part is loaded into a desired
container for
placement within a suitable HPHT consolidation and sintering device. The HPHT
device is
activated to subject the container to a desired HPHT condition to effect
consolidation and
sintering of the diamond powder. In an example embodiment, the device is
controlled so that
the container is subjected to a HPHT process having a pressure of 5,000 MPa or
greater, and a
temperature of from about 1,350 C to 1,500 C for a predetermined period of
time. At this
pressure and temperature, the catalyst material melts and infiltrates into the
diamond powder
mixture, thereby sintering the diamond grains to form PCD. After the HPHT
process is
completed, the container is removed from the HPHT device, and the so-formed
PCD material is
removed from the container.
In the event that a substrate is used during the HPHT process, e.g., as a
source of the
catalyst material, the substrate is removed prior to treating the PCD material
to remove the
catalyst material therefrom to form TSP. The substrate may be removed during
or after the
treatment to form TSP. In an embodiment, any substrate is removed prior to
treatment to
expedite the process of removing the catalyst material from the PCD body.
The term "removed", as used with reference to the catalyst material after the
treatment
process for forming TSP, is understood to mean that a substantial portion of
the catalyst
material no longer resides within the remaining diamond bonded body. However,
it is to be
understood that some small amount of catalyst material may still remain in the
resulting
diamond bonded body, e.g., within the interstitial regions and/or adhered to
the surface of the
diamond crystals. Additionally, the term "substantially free", as used herein
to refer to the
catalyst material in the diamond bonded body after the treatment process, is
understood to
mean that there may still be some small/trace amount of catalyst material
remaining within the
TSP material as noted above. Rather than removing the catalyst material from
the PCD, the
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PCD may be rendered TSP by treating the catalyst material used to form the PCD
in such a
manner so as to render the catalyst material nonreactive or noncatalytic at
construction
operating temperatures.
In an example embodiment, the PCD body is treated to render the entire body
substantially free of the catalyst material. This may be done, by subjecting
the PCD body to
chemical treatment such as by acid leaching or aqua regia bath,
electrochemical treatment such
as by electrolytic process, by liquid metal solubility, or by liquid metal
infiltration that sweeps
the existing catalyst material away and replaces it with another noncatalyst
material during a
liquid phase sintering process, or by combinations thereof. This process may
be conducted
under conditions of elevated temperature, elevated pressure, high-frequency
vibration, and
combinations thereof. In an example embodiment, the catalyst material is
removed from the
PCD body by an acid leaching technique, such as that disclosed for example in
U.S. Pat. No.
4,224,380.
The TSP may be formed using thermally stable catalyst systems such as
carbonates,
sulfites, or pyrites. In such cases temperatures above 2000 C and pressures
over 7.0 GPa may
be required to form the TSP body. In an additional embodiment, the TSP may be
formed from
graphitic or non-diamond carbon sources which will require temperatures
greater than 2000 C
pressures above 10.0 GPa.
FIG. 1 illustrates a section of the diamond-bonded TSP body 10 resulting from
the
removal of the catalyst material therefrom. The TSP body has a material
microstructure
comprising a polycrystalline diamond matrix phase made up of a plurality of
diamond grains or
crystals 12 that are bonded together, and a plurality of interstitial regions
14 that are disposed
within the matrix between the bonded together diamond grains, and that exist
as empty pores
or voids within the material microstructure, as a result of the catalyst
material being removed
therefrom.
FIG. 2 illustrates an example embodiment of the TSP body 16 wherein the TSP
body
includes a top surface 22 extending along the diamond table, and a side
surface 24 that extends
along a wall portion of the body. The TSP body comprises a working surface
that may include
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all or a portion of the top and/or side surfaces, depending on the particular
end-use
application. While the TSP body illustrated in FIG. 2 is in the form of a
wafer or disc that has a
generally cylindrical side surface and flat top and bottom surfaces, it is to
be understood that
TSP bodies that are configured differently are intended to be within the scope
of the ultra-hard
construction as disclosed herein. Additionally, the TSP body 16 may include
one or more
surface features provided to facilitate use of the construction in its end-use
application. For
example, the TSP body may at this stage of processing include a chamfer or a
beveled surface
section between the top and side surfaces, e.g., extending circumferentially
around an edge of
the top surface, and such surface may be a working surface.
The so-formed TSP body is treated prior to being attached to a substrate by
use of a
braze joint, which substrate may be provided in the form of part that is
separate from the end-
use device, such as a substrate that is conventionally used for making PCD
compacts, or may be
in the form of the end-use device itself. The treatment comprises applying a
layer of metal
material to a surface of the TSP body positioned to interface with the
substrate, i.e., a substrate
interface surface. The metal material is provided for the purpose of enhancing
the strength of
the attachment that is formed with the substrate through the braze joint, to
thereby provide an
improved service life by avoiding substrate delamination.
In an example embodiment, the TSP body is treated by depositing the metal
material
thereon by any suitable deposition process, e.g., by dipping, by spray, CVD
process, sputtering
process, or the like. In an example embodiment, it is desired that a metal
material be one that
includes carbide and/or that is a carbide former, e.g., that forms carbide
upon subsequent
treatment. It is desired that the metal material be applied in sufficient
amount and/or
thickness to provide a desired amount of carbide at the substrate interface
for the purpose of
permitting the use of a non-active braze to join the substrate and TSP body
together. In some
instances, more than one layer of the metal material may be applied to achieve
the desired
amount or content of carbide on the TSP body surface.
In an example embodiment, the thickness of the metal layer may be in the range
of
from about 0.1 to 10 microns, in the range of from about 0.5 to 5 microns, and
in the range of
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from about' to 3 microns. It is understood that the exact thickness of the
metal layer that is
used will depend on the type of metal material being applied as well as the
type of braze
material being used. The treatment may be one that provides a surface coating
of the metal
material onto the substrate interface surface and/or that introduces the metal
material into a
region of the TSP body that extends a partial depth from the substrate
interface surface.
Metal materials useful for this treatment may include metallic materials,
metals, metal
alloys, and the like that either include carbide or that are produce carbide,
e.g., are carbide
formers, upon further treatment. As noted above, the metal material is used to
provide a
desired amount of carbide on the TSP body to permit the use of non-active
braze materials in
joining the TSP body to the substrate. The use of such non-active braze
materials is desired
because they provide a strong attachment bond with the metallic substrate and
have a
relatively higher yield strength and melting temperature than active braze
materials
conventionally used in the process of joining diamond-bonded bodies (PCD and
TSP) to a
cermet substrate. As used herein, the term "active braze" means a braze
material that reacts
the polycrystalline ultra-hard material (untreated). The term "non-active
braze" means a braze
material that does not react with the polycrystalline ultra-hard material
(untreated).
Suitable carbide containing metal materials useful for this treatment include
B, Si, Ti, Zr,
Hf, V, Nb, Ta, Cr, Mo, and W, and combinations and alloys thereof. Example
carbide-
containing metal materials include and are not limited to B4C, SiC, TiC, ZrC,
HfC, VC, NbC, TaC,
Cr2C3, CrC2, Mo2C, MoC, W2C, and WC.
Suitable carbide forming metal materials useful for this treatment include
those that are
capable of forming a carbide when subjected to a carburizing process, which
carburizing
process may be conducted as a step separate from brazing or during the brazing
process.
Suitable carbide forming materials include refractory metals such as those
selected from
Groups IV through VII of the Periodic table. In an example embodiment, the
metal material is
tungsten (W), and the layer of tungsten is carburized such that the primary
constituent on the
substrate interface surface is tungsten carbide (WC). The metal material is
titanium and the
carbide is titanium carbide (TiC)
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It is desired that the metal material used for this treatment be one that
produces a
desired level or content of carbide on the substrate interface surface to
facilitate use of a non-
active braze material to join the substrate and TSP body together. Non-active
braze materials
are ones uniquely suited to form a strong bond with a carbide containing
surface. Thus,
treating the TSP body substrate interface surface in this matter provides such
a carbide surface
on the TSP body to match the carbide already present on the surface of the
substrate, thereby
ensuring that a strong brazed attachment is formed therebetween. Additionally,
because non-
active braze materials have a relatively higher yield strength and melting
temperature than
active braze materials (that are conventionally used to join polycrystalline
bodies to metallic
substrate), the braze joint formed by the non-active braze material is less
apt to delaminate and
fail during service, thereby enhancing the service life of ultra-hard
constructions that are
formed therefrom.
The metal material used to facilitate brazed attachment between the TSP body
and
substrate may also serve as a barrier to prevent any unwanted migration or
infiltration of
material into the TSP body during the braze operation. Additionally, the metal
material may
help to accommodate any mismatch in mechanical properties that exist between
the TSP body,
the braze material, and the substrate, e.g., differences in thermal expansion
characteristics,
that may create high residual stresses in the construction during the
attachment process. The
residual stress mismatch may be helped by having a tungsten or titanium layer
that contains a
gradient composition with respect to carbide content, for example containing
approximately
90% or higher carbide near the ultra-hard material interface, and 50% or lower
carbide content
at the interface to be joined with a non-active braze.
FIG. 3 illustrates an example embodiment of the ultra-hard construction as
disclosed
herein at a stage of processing where a layer of the metal material 30 has
been applied or
deposited onto a substrate interfacing surface 32 of the TSP body 34 for
purpose of subsequent
substrate attachment. In an example embodiment, the metal material 30 is
tungsten and is
provided by CVD, PVD, or sputtering process. The amount of metal material 30
that is applied
will depend on whether a surface coating along the substrate interface surface
32 is desired, or
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whether it is desired to form an infiltrated region in the TSP body extending
a partial depth
from the substrate interface surface. Whether a surface layer or infiltrated
region is desired
will depend on a number of factors such as the type of substrate and braze
material that is
used, as well as the end-use application.
A treatment providing a coated surface may be desired in instances where
maximum
thermal protection of the TSP cutting edge or working surface is required. An
additional barrier
layer coating may optimize the thermal gradient into the TSP body and thereby
prolong cutting
life. In an example embodiment where a coated surface is provided, the coating
may extend a
thickness measured from the substrate interface surface of the TSP body of
from about 1 to 5
microns, from about 5 to 20 microns, and more than about 20 microns.
A treatment providing an infiltrated region within the TSP body may be desired
in
instances where an enhanced attachment strength between the substrate and TSP
body is
desired and provided by the bonding of the braze material, in addition to the
surface of the TSP
body, to the region within the TSP body comprising the metal material. In an
example
embodiment, where infiltration of the metal material is desired, the
infiltration depth may be in
the range of from about 1 to 20 microns.
In an embodiment where the metal material is additionally selected to act as a
barrier
material, its presence operates to prevent unwanted migration of constituents
from the braze
joint and/or substrate into the TSP body. Additionally, the presence of such a
barrier metal
material may operate to block unwanted infiltration of the any materials from
the from the TSP
body into the adjacent braze joint or substrate.
Once the TSP body has been treated to include the metal material, it may be
subjected
to further treatment prior to being braze attached to the substrate. In the
event that the metal
material applied to the TSP body already contains carbide, then the TSP body
may be brazed
without further treatment. In the event that the metal material applied to the
TSP body was a
carbide former and does not already contain carbide, then further treatment
will take place to
form the desired carbide constituent. In an example embodiment, such further
treatment may
comprise carburizing the metal material at an elevated temperature in the
range of from about
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700 to 1,500 C. In an example embodiment, the carburizing process takes place
at a
temperature of about 900 C for an amount of time sufficient to create the
desired carbide.
Temperatures and times may also be manipulated to create a desired gradient
condition in the
metallic layer.
The step of forming the carbide constituent in the metal material, e.g., by
carburizing,
may take place separately and independent from the step of brazing the TSP
body to the
substrate. The step of forming the carbide constituent may take place during
the step of
brazing, e.g., immediately before joining together the TSP body and the braze
material.
Suitable non-active braze materials useful in forming ultra-hard constructions
as
disclosed herein include those selected from the group including Cu, Ni, Mn,
Au, Pd and
combinations and alloys thereof. Example alloys include those having the
following
composition and liquid temperature (LT) and solid temperature (ST), where the
composition
amounts are provided in the form of weight percentages: 40 Ni, 60 Pd, LT = ST
= 1,238 C; 70
Au, 22 Ni, 8 Pd, LT = 1,037 C, ST = 1,005 C; 35 Au, 31.5 Cu, 14 Ni, 10 Pd, 9.5
Mn, LT = 1,004 C, ST
= 971 C; 52.5 Cu, 9.5 Ni, 38 Mn, LT=925 C, ST=880 C; 31 Au, 43.5 Cu, 9.75 Ni,
9.75 Pd, 16 Mn,
LT=949 C, ST=927 C; 54 Ag, 21 Cu, 25 Pd, LT=950 C, ST=900 C; 67.5 Cu, 9 Ni,
23.5 Mn,
LT=955 C, ST=925 C; 58.5 Cu, 10 Co, 31.5 Mn, LT=999 C, ST=896 C; 35 Au, 31.5
Cu, 14 Ni, 10
Pd, 9.5 Mn, LT=1,004 C, ST=971 C; 25 Su, 37 Cu, 10 Ni, 15 Pd, 13 Mn, LT=1,013
C, ST=970 C;
and 35 Au, 62 Cu, 3 Ni, LT=1,030 C, ST=1,000 C.
The TSP body (comprising the carbide-containing substrate interface surface)
is joined to
the substrate through the braze material under elevated temperature conditions
sufficient to
melt the braze material. The braze joint may be formed by using conventional
braze techniques
such as by vacuum brazing, induction brazing, and the like. Thus, a further
feature of ultra-hard
constructions disclosed herein is that the TSP body is attached to the
substrate by brazing at
elevated temperature without elevated pressure, i.e., without having to
subject the TSP body to
a second HPHT process. Avoiding the need to rely on an HPHT process for
attaching the TSP
body to the substrate is highly desired as it improves manufacturing
efficiency and reduces
related manufacturing costs, and avoids unwanted infiltration issues.
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FIG. 4 illustrates an example embodiment TSP construction 40 comprising a TSP
body 42
that is attached to a substrate 44 via a braze joint 46. The TSP body includes
a working surface
that may exist along a top surface 48, a side surface 50, and/or an edge
surface 52. The TSP
body comprises a substrate interface surface 54 and a metal material 56
containing a carbide
constituent disposed thereon, that operates to provide an enhanced attachment
with a non-
active braze material used to form the braze joint 46 when compared to
conventional TSP
construction that does not include the metal material.
Example braze materials useful for forming the braze joint include materials
that are
capable of forming a strong chemical bond between the TSP body and a desired
substrate. It is
desired that the braze material includes one or more elements that are capable
of reacting with
one or more elements in the TSP body to form such strong chemical bond. For
this reason,
materials useful for forming the braze material may be referred to as being
"active" braze
materials or alloys.
As noted above, the substrate useful in forming ultra-hard constructions as
disclosed
herein may be provided in the form of a part that is separate from the end-use
device, such as a
cermet or carbide part, or may be provided in the form a portion of the end-
use device itself.
Accordingly, it is to be understood that TSP bodies that have been treated in
the manner
described above may be attached directly or indirectly to the end-use device
by the above-
described braze joint.
Suitable substrates that are provided separate from the end-use device may be
selected
from those materials conventionally used as substrates for forming PCD
compacts, and may
include metallic materials, ceramic material, cermet materials, and
combinations thereof. An
example substrate is one that is a carbide, such as one formed from WC--Co.
The size and
configuration of the substrate may and will vary depending on the size and
configuration of the
TSP body and the end-use application. Various types of steels may be employed
as substrates
and may include or be later machined to contain features such as threads or
other fastener
devices to facilitate convenient mechanical attachment to a drill bit. Wherein
the types of
steels useful as a substrate include those having a Rockwell C hardness of 50
or more.
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While particular example embodiment ultra-hard constructions have been
disclosed
above and illustrated, it is understood that variations of these example
embodiment are
understood to be within the scope of what is being disclosed herein.
A feature of ultra-hard constructions as disclosed herein is that the TSP body
included
therein has been treated to include a metal material prior to brazed
attachment with a
substrate, wherein such metal material either includes or is treated to
include a carbide
constituent. A further feature of such ultra-hard constructions as disclosed
herein is that the
braze material used to form the braze joint is a non-active braze material
that is well suited to
form an improved degree of bond strength between carbide containing surfaces,
as they
currently exist on both the TSP body and the substrate. A further feature of
such ultra-hard
constructions is that the non-active braze material has a relatively higher
yield stress and
melting temperature as compared to active braze materials conventionally used
to form the
braze joint between the TSP body and the substrate, thereby improving service
life by
minimizing unwanted delamination while in service. A still further feature of
such ultra-hard
constructions is the avoidance of having to undergo HPHT processing to attach
the TSP body to
the substrate, wherein the braze joint is formed at the braze material melting
temperature
without the need for elevated pressure, thereby improving manufacturing
efficiency and
reducing related manufacturing costs.
Ultra-hard constructions as disclosed herein may be used in a number of
different
applications, such as tools for mining, cutting, machining, milling and
construction applications,
wherein properties of shear strength, thermal stability, wear and abrasion
resistance,
mechanical strength, and/or reduced thermal residual stress are highly
desired. Ultra-hard
constructions as disclosed herein are particularly well suited for forming
working, wear and/or
cutting elements in machine tools and drill and mining bits such as roller
cone rock bits,
percussion or hammer bits, diamond bits, and shear cutters used in
subterranean drilling
applications.
FIG. 5 illustrates an embodiment of an ultra-hard construction as disclosed
herein
provided in the form of a cutting element embodied as an insert 60 used in a
wear or cutting
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application in a roller cone drill bit or percussion or hammer drill bit. For
example, such inserts
60 may be formed from blanks comprising a substrate portion 62 formed from one
or more of
the substrate materials 64 disclosed above, and an ultra-hard material body 66
having a
working surface 68 formed from the thermally stable region of the ultra-hard
body. The blanks
are pressed or machined to the desired shape of a roller cone rock bit insert.
FIG. 6 illustrates a rotary or roller cone drill bit in the form of a rock bit
70 comprising a
number of the wear or cutting inserts 60 disclosed above and illustrated in
FIG. 5. The rock bit
70 comprises a body 72 having three legs 74, and a roller cutter cone 76
mounted on a lower
end of each leg. The inserts 60 may be fabricated according to the method
described above.
The inserts 60 are provided in the surfaces of each cutter cone 76 for bearing
on a rock
formation being drilled.
FIG. 7 illustrates the inserts 60 described above as used with a percussion or
hammer bit
80. The hammer bit comprises a hollow steel body 82 having a threaded pin 84
on an end of the
body for assembling the bit onto a drill string (not shown) for drilling oil
wells and the like. A
plurality of the inserts 76 (illustrated in FIG. 7) are provided in the
surface of a head 100 of the
body 96 for bearing on the subterranean formation being drilled.
FIG. 8 illustrates an ultra-hard construction as disclosed herein as embodied
in the form
of a shear cutter 90 used, for example, with a drag bit for drilling
subterranean formations. The
shear cutter 90 comprises a thermally stable ultra-hard body 92 that is
sintered or otherwise
attached/joined to a cutter substrate 94. The thermally stable ultra-hard
material body includes
a working or cutting surface 96.
FIG. 9 illustrates a drag bit 100 comprising a plurality of the shear cutters
90 described
above and illustrated in FIG. 8. The shear cutters are each attached to blades
102 that extend
from a head 104 of the drag bit for cutting against the subterranean formation
being drilled.
Although only a few example embodiments have been described in detail above,
those
skilled in the art will readily appreciate that many modifications are
possible in the example
embodiments without materially departing from this invention. Accordingly, all
such
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modifications are intended to be included within the scope of this disclosure
as defined in the
following claims. In the claims, means-plus-function clauses are intended to
cover the
structures described herein as performing the recited function and not only
structural
equivalents, but also equivalent structures. Thus, although a nail and a screw
may not be
structural equivalents in that a nail employs a cylindrical surface to secure
wooden parts
together, whereas a screw employs a helical surface, in the environment of
fastening wooden
parts, a nail and a screw may be equivalent structures. It is the express
intention of the
applicant not to invoke 35 U.S.C. 112, paragraph 6 for any limitations of
any of the claims
herein, except for those in which the claim expressly uses the words 'means
for' together with
an associated function.
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