U.S. patent application number 14/088842 was filed with the patent office on 2014-05-29 for eruption control in thermally stable pcd products by the addition of transition metal carbide.
This patent application is currently assigned to Smith International, Inc.. The applicant listed for this patent is Smith International, Inc.. Invention is credited to Ronald K. Eyre, Guojiang Fan, Jeffrey Bruce Lund.
Application Number | 20140144712 14/088842 |
Document ID | / |
Family ID | 50772290 |
Filed Date | 2014-05-29 |
United States Patent
Application |
20140144712 |
Kind Code |
A1 |
Lund; Jeffrey Bruce ; et
al. |
May 29, 2014 |
ERUPTION CONTROL IN THERMALLY STABLE PCD PRODUCTS BY THE ADDITION
OF TRANSITION METAL CARBIDE
Abstract
A method of loaning a diamond compact includes adding an
additive material to a tungsten carbide substrate, the additive
material including a transition metal carbide other than tungsten
carbide, placing a diamond body adjacent to an interface surface of
the tungsten carbide substrate, and subjecting the diamond body and
the tungsten carbide substrate to a high pressure high temperature
bonding process to bond the diamond body to the tungsten carbide
substrate.
Inventors: |
Lund; Jeffrey Bruce; (Salt
Lake City, UT) ; Eyre; Ronald K.; (Orem, UT) ;
Fan; Guojiang; (Lehi, UT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Smith International, Inc. |
Houston |
TX |
US |
|
|
Assignee: |
Smith International, Inc.
Houston
TX
|
Family ID: |
50772290 |
Appl. No.: |
14/088842 |
Filed: |
November 25, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61730318 |
Nov 27, 2012 |
|
|
|
Current U.S.
Class: |
175/428 ; 51/295;
51/297 |
Current CPC
Class: |
C04B 2235/78 20130101;
B24D 99/005 20130101; C04B 37/021 20130101; C04B 37/005 20130101;
C04B 2237/363 20130101; B24D 18/0009 20130101; C04B 37/001
20130101; C04B 2237/083 20130101; C04B 2237/704 20130101; C04B
2237/401 20130101; C04B 37/025 20130101; B24D 18/0054 20130101;
C04B 2237/36 20130101; E21B 10/5735 20130101; C04B 35/645
20130101 |
Class at
Publication: |
175/428 ; 51/297;
51/295 |
International
Class: |
E21B 10/567 20060101
E21B010/567; B24D 18/00 20060101 B24D018/00 |
Claims
1. A method of forming a diamond compact, comprising: adding an
additive material to a tungsten carbide substrate, the additive
material comprising a transition metal carbide other than tungsten
carbide; placing a diamond body adjacent to an interface surface of
the tungsten carbide substrate; and subjecting the diamond body and
the tungsten carbide substrate to a high pressure high temperature
bonding process to bond the diamond body to the tungsten carbide
substrate.
2. The method of claim , wherein the transition metal carbide is
selected from the group consisting of VC, Mo.sub.2C,
Cr.sub.3C.sub.2, NbC, TaC, TiC, and combinations thereof.
3. The method of claim 1, wherein the additive material is added to
the tungsten carbide substrate by coating the interface surface of
the tungsten carbide substrate.
4. The method of claim 3, wherein the additive material is added by
a coating method selected from the group consisting of applying a
foil, applying a layer of powder, applying a layer of paste,
casting, brushing, spraying, chemical vapor deposition, and
physical vapor deposition.
5. The method of claim 1, wherein the step of adding comprises
coating a surface of the diamond body with the additive material
and placing the coated surface adjacent to the tungsten carbide
substrate.
6. The method of claim 5, wherein the additive material is added by
a coating method selected from the group consisting of applying a
foil, applying a layer of powder, applying a layer of paste,
casting, brushing, spraying, chemical vapor deposition, and
physical vapor deposition.
7. The method of claim 1, wherein the additive material is added to
the tungsten carbide substrate by forming the tungsten carbide
substrate with the additive material premixed therein.
8. The method of claim 1, wherein the additive material comprises
up to 0.5 percent by weight of the tungsten carbide substrate.
9. The method of claim 1, wherein the tungsten carbide substrate is
provided as a powdered layer.
10. The method of claim 1, wherein the tungsten carbide substrate
is provided as a pre-sintered body.
11. The method of claim 1, wherein the high pressure high
temperature bonding process comprises a pressure of greater than
5,000 MPa and a temperature of greater than 1,300.degree. C.
12. The method, of claim 1, further comprising: sintering diamond
crystals and a catalyst material at a first high pressure high
temperature condition to form a polycrystalline diamond material;
and leaching the polycrystalline diamond material to form the
diamond body.
13. The method of claim 1, wherein the diamond body has a height
ranging from about 0.05 mm to about 12 mm.
14. A cutting element, comprising: a substrate, the substrate
comprising tungsten carbide grains bonded together with a cobalt
binder; and a polycrystalline diamond table bonded to the substrate
at an interface, the polycrystalline diamond table comprising: a
cutting face; and a microstructure comprising a plurality of bonded
together diamond grains and a plurality of interstitial regions
disposed among the bonded together diamond grains, at least a
portion of the interstitial regions comprising the cobalt hinder
and a transition metal carbide, the polycrystalline diamond table
being substantially free of eruptions.
15. The cutting element of claim 14, wherein the transition metal
carbide is also disposed at the interface between the
polycrystalline diamond table and the substrate.
16. The cutting element of claim 14, wherein the substrate further
comprises the transition metal carbide.
17. The cutting element of claim 14, wherein the transition metal
carbide is selected from the group consisting of VC, Mo.sub.2C,
Cr.sub.3C.sub.2, NbC, TaC, TiC, and combinations thereof
18. The cutting element of claim 14, wherein the transition metal
carbide comprises up to 0.5 percent by weight of the substrate.
19. The cutting element of claim 14, wherein the polycrystalline
diamond table further comprises a height measured between the
interface and the cutting face ranging from about 0.05 mm to about
12 mm.
20. The cutting element of claim 19, wherein the cobalt binder and
the transition metal carbide occupy the interstitial regions
throughout the entire height of the polycrystalline diamond table.
Description
CROSS-REFERNCE TO RELATED APPLICATIONS
[0001] Pursuant to 35 U.S.C .sctn. 119, this application claims the
benefit of U.S. Provisional Ptitent Application No. 611730,318,
filed on Nov. 2, 2012, which is herein incorporated by reference in
its entirety.
BACKGROUND
[0002] Polycrystalline diamond ("PCD") materials and PCD elements
formed therefrom arc well known in the art. Conventional PCD may be
formed by subjecting diamond particles in the presence of a
suitable solvent metal catalyst material to processing conditions
of high pressure/high temperature (HPHT), where the solvent metal
catalyst promotes desired intercrystalline diamond-to-diamond
bonding between the particles, thereby forming a PCD structure. The
resulting PCD structure produces enhanced properties of wear
resistance and hardness, making such PCD materials useful in
aggressive wear and cutting applications where high levels of wear
resistance and hardness are desired. FIG. 1 illustrates a
microstructure of conventionally formed PCD material 10 including a
plurality of diamond grains 12 that are bonded to one another to
form an intercrystalline diamond matrix first phase. The
catalyst/binder material 14, e.g., cobalt, used to facilitate the
diamond-to-diamond bonding that develops during the sintering
process is dispersed within the interstitial regions thrilled
between the diamond matrix first phase. The term "particle" refers
to the powder employed, prior to sintering a superabrasive
material, while the term "grain" refers to discernable
superabrasive regions subsequent to sintering, as known and as
determined in the art.
[0003] The catalyst/binder material used to facilitate
diamond-to-diamond bonding can be provided generally in two ways.
The catalyst/binder can be provided in the form of a raw material
powder that is pre-mixed with the diamond grains or grit prior to
simering. In some cases, the catalyst/binder can be provided by
infiltration into the diamond material (during high
temperature/high pressure processing) from an underlying substrate
material that the final PCD material is to be bonded to. After the
catalyst/hinder material has facilitated the diamond-to-diamond
bonding, the catalyst/binder material is generally distributed
throughout the diamond matrix within interstitial regions formed
between the bonded diamond grains. Particularly, as shown in FIG.
1, the binder material 14 is not continuous throughout the
microstructure in the conventional PCD material 10. Rather, the
microstructure of the conventional PCD material 10 may have a
uniform distribution of binder among the PCD grains. Thus, crack
propagation through conventional PCD material will often travel
through the less ductile and brittle diamond grains, either
transgranularly through diamond grain/binder interfaces 15, or
intergranularly through the diamond grain/diamond grain interfaces
16.
[0004] Solvent catalyst materials may facilitate diamond
intercrystalline bonding and bonding of PCD layers to each other
and to an underlying substrate. Solvent catalyst materials used for
forming conventional PCD may include metals from Group VIII of the
Periodic table, such as cobalt iron, or nickel and/or mixtures or
alloys thereof, with cobalt being the most common. Conventional PCD
may include from 85 to 95% by volume diamond and a remaining amount
of the solvent catalyst material. However, while higher metal
content may increase the toughness of the resulting PCD material,
higher metal content also decreases the PCD material hardness, thus
limiting the flexibility of being able to provide PCD layers having
desired levels of both hardness and toughness.
[0005] Conventional PCD is stable at temperatures of up to
700-750.degree. C., after which observed increases in temperature
may result in permanent damage to and structural failure of PCD.
For example, upon heating of PCD, the difference in the coefficient
of thermal expansion of the binder material, which may be cobalt,
as compared to diamond results in the cobalt and the diamond
lattice expanding at different rates, which may cause cracks to
form in the diamond lattice structure and result in deterioration
of the PCD. High operating temperatures may also lead to back
conversion of the diamond to graphite causing loss of
microstructural integrity, strength loss, and rapid abrasive
wear.
[0006] In order to overcome this problem, strong acids may be used
to "leach" the cobalt from the diamond lattice structure (either a
thin volume or the entire body) to at least reduce the damage
experienced from different expansion rates within a diamond-cobalt
composite during heating and cooling. Briefly, a strong acid, such
as nitric acid or combinations of several strong acids (such as
nitric and hydrofluoric acid) may be used to treat a PCD body,
e.g., by submersing the body in the acid, thereby removing at least
a portion of the catalyst from the PDC composite. In certain
embodiments, a select portion of a diamond composite is treated, in
order to gain thermal stability with less effect on impact
resistance.
SUMMARY
[0007] 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.
[0008] In one aspect, embodiments disclosed herein relate to a
method of forming a diamond compact, where the method includes
adding an additive material to a tungsten carbide substrate, where
the additive material includes a transition metal carbide other
than tungsten carbide, placing a diamond body adjacent to an
interface surface of the tungsten carbide substrate, and subjecting
the diamond body and the tungsten carbide substrate to a high
pressure high temperature bonding process to bond the diamond body
to the tungsten carbide substrate.
[0009] In another aspect, embodiments disclosed herein relate to a
cutting element having a substrate, where the substrate includes
tungsten carbide grains bonded together with a cobalt binder, and a
polycrystalline diamond table bonded to the substrate at an
interface, where the polycrystalline diamond table has a cutting
face and a microstructure including a plurality of bonded together
diamond grains and a plurality of interstitial regions disposed
among the bonded together diamond grains, where at least a portion
of the interstitial regions include the cobalt binder and a
transition metal carbide, and where the polycrystalline diamond
table is substantially free of eruptions.
[0010] Other aspects and advantages of the claimed 5 subject matter
will be apparent from the following description and the appended
claims.
BRIEF DESCRIPTION OF DRAWINGS
[0011] Embodiments of the present disclosure are described with
reference to the following figures. The same numbers are used
throughout the figures to reference like features and
components.
[0012] FIG. 1 shows the microstructure of conventionally formed
polycrystalline diamond.
[0013] FIG. 2 is a picture of a conventionally formed reinfiltrated
diamond table.
[0014] FIG. 3 is a picture of a reinfiltrated diamond table formed
according to embodiments of the present disclosure.
[0015] FIG. 4 is a cross-sectional view of a conventionally formed
diamond compact.
[0016] FIG. 5 is a cross-sectional view of a reattached compact
formed using methods of the present disclosure.
[0017] FIG. 6 is a cross-sectional view of a cutting element formed
according to methods of the present disclosure.
DETAILED DESCRIPTION
[0018] Polycrystalline ultra-hard materials, and compacts formed
therefrom, are specifically engineered having a polycrystalline
ultra-hard material body having a material microstructure that is
substantially free of substrate material eruptions, catalyst or
infiltrant material eruptions and thereby free of localized
concentrations, regions or volumes of the catalyst or infiltrant
material therein, and substantially free of any other substrate
constituent material. As used herein, "eruptions" refer to
precipitated regions of carbide grains and binder pools (catalyst
or infiltrant material) formed from the substrate material that
create voids or inclusions that are substantially larger than the
interstitial regions formed in a polycrystalline diamond body. As
used herein, the eruptions may he at least an order of magnitude
larger than conventional interstitial regions. Eruptions may occur
during HPHT bonding methods of attaching a diamond body to a
substrate without pressure control, where the eruptions precipitate
from die substrate into the diamond body.
[0019] Preformed diamond bodies may be formed of polycrystalline
diamond ("PCD"), for example, or other diamond-bonded material with
or without a second phase (such as a catalyst or binder second
phase). As used herein, the term "PCD" refers to polycrystalline
diamond that has been formed, at high pressure/high temperature
(HPHT) conditions, through the use of a catalyst, such as solvent
metal catalysts from Group VIII of the Periodic table, non-metallic
catalysts including carbonates, as well as non-catalyst formed
polycrystalline diamond formed with even higher temperatures and
pressure than those used to form polycrystalline diamond with
cobalt.
[0020] According to embodiments of the present disclosure. PCD may
be formed by HPHT sintering of diamond grains in the presence of a
suitable catalyst or binder material, such as cobalt and/or other
transition metal from Group VIII of the Periodic Table, to achieve
intercrystalline bonding between the diamond grains. Upon sintering
the PCD body, the catalyst binder may remain within the
interstitial regions formed between the bonded together diamond
grams. The network of interstitial regions formed between the
bonded together diamond grains may include interstitial regions
that are directly or indirectly accessible to other interstitial
regions formed within the PCD body, as well as interstitial regions
that are inaccessible, which may be dispersed throughout PCD
microstructure.
[0021] As used herein, the term "sintering" refers to the process
of forming PCD using a HPHT process, examples of which may be found
in U.S. Pat. Nos. 4,694,918, 5,370,195, and 4,525,178. Briefly, to
form a sintered PCD body, an unsintered mass or volume of diamond
grains may be placed within an enclosure of a reaction cell of a
HPHT apparatus. Examples of suitable HPHT apparatuses are described
in U.S. Pat. Nos. 2,947,611, 2,941,241, 3,609,818, 4,289,503,
4,673,414, and 4,954,139. A metal solvent catalyst material such as
described above, may be included with the unsintered mass of
crystalline particles to promote intercrystalline
diamond-to-diamond bonding. The catalyst material may be provided
in the form of powder and mixed with the diamond grains, or may be
infiltrated into the diamond grains during HPHT sintering, such as
from an adjacent carbide substrate. The reaction cell is then
placed under HPHT processing conditions sufficient to cause the
intercrystalline bonding between the diamond particles.
[0022] HPHT processing may be carried out at elevated pressures of
about 4 to 7 GPa or greater, and at elevated temperatures of about
1,300.degree. C. (2,372.degree. F.) to 1,600.degree. C.
(2,912.degree. F.) or greater. However, a variety of temperatures
and pressures may be used, depending on, for example, the type of
catalyst material being used, the amount of diamond being bonded
together, and the diamond grain size.
[0023] It should be noted that if too much additional non-diamond
material is present in the powdered mass of crystalline particles,
appreciable intercrystalline bonding is prevented during the
sintering process. Such a sintered material where appreciable
intercrystalline bonding has not occurred is not within the
definition of PCD. Following such formation of intercrystalline
bonding, a PCD body may be formed that has at least about 80
percent by volume diamond, with the remaining balance of the
interstitial regions between the diamond grains occupied by the
catalyst material. In other embodiments, the PCD body may have at
least 85 percent by volume diamond, and in another embodiment at
least 90 percent by volume diamond,
[0024] Diamond grains used for forming PCD or other diamond bonded
material may include any type of diamond particle, including
natural or synthetic diamond powders having a wide range of
particle sizes, For example, such diamond powders may have an
average particle size in the range from submicrometer to about 100
micrometers, and from 1 to 80 micrometers in other embodiments.
Further, the diamond powder used may include particles haying a
mono-modal or multi-modal. distribution. According to some
embodiments. diamond bodies may have an average grain size ranging
from less than 1 micrometer. According to other embodiments,
diamond bodies may have an average grain size ranging from 1 to 80
micrometers. In yet other embodiments. diamond bodies may have an
average grain size ranging from greater than 80 micrometers.
[0025] In various embodiments, a formed PCD body having a catalyst
material in the interstitial spaces between bonded diamond grains
may he subjected to a leaching process (before or after attachment
to a substrate), whereby the catalyst material is removed from the
PCD body. As used herein, the term "removed" refers to the reduced
presence of catalyst material in the PCD body, and is understood to
mean that a substantial portion of the catalyst material no longer
resides in the PCD body. However, one skilled in the art would
appreciate that the leaching process is limited in that trace
amounts of catalyst material may still remain in the microstructure
of the PCD body within the interstitial regions and/or adhered to
the surface of the diamond grains. Such trace amounts may result
from limited access of leaching agents during the leaching process,
and because of this limited access, other methods may be used to
reduce the thermal coefficient differential between the remaining
catalyst material and diamond.
[0026] Rather than actually removing the catalyst material
remaining in the interstitial spaces and/or adhered to the surface
of the diamond grains from the PCD body or compact, the selected
region of the PCD body or compact may be rendered thermally stable
by treating the catalyst material in a manner that reduces the
potential for the catalyst material to adversely impact the
intercrystalline bonded diamond at elevated temperatures due to the
thermal mismatch between the diamond and the remaining catalyst
material Is well as potential back conversion or graphitization.
For example, the catalyst material may be combined chemically with
another material or transformed into another material, thus causing
it to no longer act as a catalyst material. Accordingly, as used
herein, the terms "removing substantially all" or "substantially
free" as used in reference to the catalyst material is intended to
cover the different methods in which the catalyst material can be
treated to no longer adversely impact the intercrystalline diamond
in the PCD body or compact with increasing temperature.
[0027] The quantity of the catalyst material remaining in the
material PCD microstructure after the PCD body has been subjected
to a leaching treatment may vary, the example, on factors such as
the treatment conditions, including treatment time as well as
whether the PCD body is attached to the substrate body before or
after leaching. Further, one skilled in the art would appreciate
that it may be desired in certain applications to allow a small
amount of catalyst material to remain in the PCD body. In a
particular embodiment, the PCD body may include up to 1-2 percent.
by weight of the catalyst material. However, one skilled in the art
would appreciate that the amount of residual catalyst present in a
leached PCI) body may depend on the diamond density of the material
and body thickness.
[0028] A conventional leaching process involves the exposure of an
object to be leached with a leaching agent, such as described in
U.S. Pat. No 4,224,380. In select embodiments, the leaching agent
may be a weak, strong, or mixtures of acids. In other embodiments,
the leaching agent may be a caustic material such as NaOH or KOH.
Suitable acids may include, for example, nitric acid, hydrofluoric
acid, hydrochloric acid, sulfuric acid, phosphoric acid, or
perchloric acid, or combinations of these acids. In addition,
caustics, such as sodium hydroxide and potassium hydroxide, have
been used by the carbide industry to digest metallic elements from
carbide composites. In addition, other acidic and basic leaching
agents may be used as desired. Those having ordinary skill in the
art will appreciate that the molarity of the leaching, agent may he
adjusted depending on the time desired to leach, concerns about
hazards, etc.
[0029] Once the leaching step is completed and the PCD body is
removed from the leaching agent, the resulting material
microstructure of the leached portion of the diamond body may
include a first matrix phase of the bonded-together diamond grains
and a second phase of a plurality of empty interstitial regions
dispersed within the matrix phase. In other words, at the end of
the leaching process, the treated interstitial regions may be
substantially empty so that the second phase may be described as a
plurality of voids or empty regions dispersed throughout the
diamond-bonded matrix phase. Thus, the leached portion of the
diamond body may be substantially free of the catalyst material
used to initially form or sinter the diamond body, and may be
referred to as thermally stable polycrystalline diamond.
[0030] Leached diamond bodies may be attached (or reattached) to a
substrate after completing the leaching process by methods
disclosed herein, to facilitate attachment to a bit, cutting tool,
or other end use application or device. For example, according to
embodiments of the present disclosure, a method of forming a
diamond compact (i.e., a diamond body attached to a substrate) may
include adding a transition metal carbide other than tungsten
carbide to a tungsten carbide substrate and placing a leached
diamond body adjacent to an interface surface of the tungsten
carbide substrate. The tungsten carbide substrate may be provided
as a pre-sintered body or as a powdered layer. The leached diamond
body and the adjacent tungsten carbide substrate may then be
subjected to a HPHT bonding process to bond the diamond body to the
tungsten carbide substrate. A HPHT bonding process may include, for
example, placing a diamond body and a substrate with a transition
metal carbide added thereto within a sealed can and subjecting the
can and its contents to elevated pressures, such as greater than
5,000 MPa, and elevated temperatures, such as greater than
1,300.degree. C. The HPHT bonding process may have different
durations, temperatures, and pressures than the HPHT sintering
step.
[0031] Substrates of the present disclosure may include wear
resistant material having hard particles dispersed in a hinder
metal matrix. An example substrate material may include tungsten
carbide particles dispersed in a cobalt binder, such as cemented
tungsten carbide and cobalt (WC/Co). Such substrate materials
include a hard particle phase made of tungsten carbide particles
and a metal binder phase made of cobalt. Tungsten carbide
substrates may have, for example, a grain size ranging from about 6
microns or less (fine grain) in sonic embodiments, or greater than
6 microns (coarse grain) in other embodiments, and a binder content
ranging from a lower limit selected from 6%, 8% and 10% by weight
to an upper limit selected from 10%, 12%, 14% and 16% by
weight.
[0032] In addition to the hard particle (tungsten carbide) phase
and metal binder phase (cobalt) described above, substrates of the
present disclosure may also include an additive material, where the
additive material is made of one or more transition metal carbide
materials other than tungsten carbide. The transition metal carbide
may be selected from at least one of vanadium carbide (VC),
molybdenum carbide (Mo.sub.2C), chromium carbide (Cr.sub.3C.sub.2),
niobium carbide (NbC), tantalum carbide (TaC) and titanium carbide
(TiC). According to embodiments of the present disclosure, the
additive material may form greater than 0.2 percent by weight and
up to 1 percent by weight of the tungsten carbide substrate.
According other embodiments, the amount of additive material added
to a tungsten carbide substrate may range from a lower limit
selected from 0.1, 0.2 and 0.3 percent by weight of the tungsten
carbide substrate to an upper limit selected from 0.4, 0.5. 0.8 and
1.0 percent by weight of the tungsten carbide substrate, where any
lower limit may be used in combination w any upper limit.
[0033] One or more additive transition metal carbides may be added
to a tungsten carbide substrate by forming the tungsten carbide
substrate with the transition metal carbide premixed therein. For
example, a mixture of tungsten carbide particles, cobalt for other
binder) powder and an additive material may be pressed into a green
compact and then sintered to form a substrate having tungsten
carbide grains bonded together with a cobalt binder and the
additive material dispersed throughout. As used herein, an additive
material refers to a transition metal carbide other than tungsten
carbide, and may he selected from one or more of VC, Mo.sub.2C,
Cr.sub.3C.sub.2, NbC, TaC and TiC. The substrate may be sintered,
for example, at temperatures ranging from about 1,400.degree. C.
(2,552.degree. F.) to about 1,600.degree. C. (2,912.degree. F.).
Other sintering methods known in the art for sintering tungsten
carbide substrates may be used, such as, for example. HPHT
sintering or hot isostatic pressing.
[0034] According to other embodiments of the present disclosure, an
additive material may be added to a tungsten carbide substrate by
coating an interface surface of the tungsten carbide substrate with
the additive material. For example, an additive material, such as
chromium carbide, may be coated onto a surface of a tungsten
carbide substrate that will eventually interface a preformed
diamond body. The additive material may be coated onto the
interface surface, for example, by applying a foil, applying a
layer of powder, applying a layer of paste, casting, brushing,
spraying, chemical vapor deposition ("CVD"), or physical vapor
deposition ("PVD") methods.
[0035] According to yet other embodiments, an additive material may
be added to a tungsten carbide substrate by coating an interface
surface of a preformed diamond body with the additive material. For
example, an additive material, such as chromium carbide, may be
coated onto a surface of the diamond body that will eventually
interface the substrate. The additive material may be coated onto
the interface surface, for example, by applying a foil, applying a
layer of powder, applying a layer of paste, casting, brushing,
spraying, chemical vapor deposition ("CVD"), or physical vapor
deposition ("PVD") methods.
[0036] By incorporating the additive material into a diamond
compact (i.e., a diamond body bonded to a substrate) during the
method of bonding or reattaching the diamond body to the tungsten
carbide substrate, eruptions composed of tungsten carbide grains
and cobalt pools that would have otherwise occurred may be
prevented. As used herein, "eruptions" refer to precipitated
regions of carbide grains and hinder pools (e.g., catalyst or
infiltrant material) formed from the substrate material that create
voids or inclusions that are substantially larger than the
inertstitial regions formed in a polycrystalline diamond body.
Eruptions may have a distinct form and composition from the
remaining. TSP microstructure and also produce a non-uniform
substrate microstructure. For example, FIG. 2 shows an example of a
conventional diamond table 200 that had been attached to a tungsten
carbide substrate (not shown) by HPHT bonding without using
additive material (e.g., VC, Mo.sub.2C, Cr.sub.3C.sub.2, NbC, TaC
or TiC). The diamond table 200 has a plurality of pores 210 formed
therein. As described above, the pores 210 were formed from
eruptions that precipitated from the substrate into the diamond
body. In contrast, FIG. 3 shows a diamond table 300 formed
according to methods of the present disclosure, where the diamond
table 300 had been attached to a substrate (not shown) by HPHT
bonding using an additive material. As shown, the diamond table 300
has a substantially continuous microstructure, where no pores have
been formed.
[0037] Further, eruptions may create a non-uniform microstructure
in the diamond body. Particularly, eruptions formed using
conventional methods of attaching a tungsten carbide substrate to a
diamond body may include precipitated tungsten carbide grams and
cobalt pools extending into the diamond body in a tree-shaped or
branched pattern. Thus, the attached polycrystalline diamond both
may have a microstructure including a plurality of bonded together
diamond grains, a plurality of interstitial regions disposed among
the bonded together diamond grains, and extensions of precipitated
tungsten carbide grains and cobalt pools extending from the
interface between the tungsten carbide substrate and diamond body a
distance into the diamond body and through the bonded together
diamond grains and interstitial regions. However, diamond compacts
formed according to methods of the present disclosure may have an
attached diamond body that is substantially free of eruptions. For
example, an attached polycrystalline diamond body may have a
substantially uniform microstructure including a plurality of
bonded together diamond grains and a plurality of interstitial
regions disposed among the bonded together diamond grains.
[0038] FIG. 4 shows an example of a diamond compact 400 formed by
HPHT bonding of a diamond body 410 to a tungsten carbide substrate
420 without using an additive material (as described above). During
the attaching step, eruptions 430 of tungsten carbide and cobalt
precipitated from the substrate 420 into the diamond body 410 in a
branched pattern. Eruptions 430 occuring from the HPHT bonding
process of attaching a diamond body 410 to a tungsten carbide
substrate 420 are distinct from substrate material that may
infiltrate into the diamond body 410 during the HPHT bonding
process. For example, as described above, eruptions 430 may be made
at precipitated tungsten carbide and cobalt, which has a tree-like
or dendrite form extending into the diamond body. During the HPHT
bonding process, substrate material may also infiltrate into the
diamond body. Infiltration occurs when the temperature of the HPHT
bonding process reaches the melting temperature of the substrate
material. For example, when the HRHT bonding process temperature
reaches the melting point of cobalt, the cobalt from the tungsten
carbide substrate may melt and infiltrate into the diamond body
thereby filling at least a portion of the interstitial regions.
Further, prior to attachment to the substrate, the diamond body 410
may include bonded together diamond grains and substantially empty
interstitial regions between the bonded together diamond grains.
After the HPHT bonding process, the diamond body 410 may have an
amount of infiltrated cobalt disposed within the interstitial
regions, thereby reducing thermal stability.
[0039] However, referring now to FIG. 5, eruptions may not occur
when additive materials of the present disclosure are used to
reattach a diamond body to a substrate to form a diamond compact.
Particularly. FIG. 5 shows a diamond compact 500 formed by HPHT
bonding of a diamond body 510 to a tungsten carbide substrate 520,
wherien an additive material of the present disclosure, such as
chromium carbide, was used in the diamond compact during the HPHT
bonding process, such as by premixing the additive material within
the substrate or coating the additive material onto the interface
surface of the tungsten carbide substrate or the diamond body. The
final diamond compact 500 (i.e., diamond body bonded to a
substrate) formed with an additive material may have a diamond body
microstructure made of a plurality of bonded together diamond
grains and a plurality of interstitial regions between the bonded
together diamond grains and is substantially free of eruptions. As
described above, in some embodiments, cobalt from the substrate 520
may infiltrate into the diamond body 510 during the HPHT bonding
process. In such embodiments, the diamond body may have infiltrated
cobalt disposed within a plurality of the previously emptied
interstitial regions. Further, in some embodiments, an amount of
the additive material may infiltrate into the interstitial regions
of the diamond body from the substrate during the HPHT bonding
process. For example, according to some embodiments, an additive
material made of a transition carbide material other than tungsten
carbide, such as chromium carbide, may be added to a tungsten
carbide substrate, such as by premixing the additive material
within the substrate or providing the additive material at the
interface between the substrate and the diamond body. During the
HPHT bonding, process, an amount of the additive material along
with an amount of cobalt from the substrate may infiltrate into the
diamond body and may be disposed within at least a portion of the
interstitial regions.
[0040] Thus, diamond compacts formed according to embodiments of
the present disclosure may include a substrate attached to a
polycrystalline diamond table, where the diamond table has a
microstructure substantially free of precipitated tungsten carbide
grains and cobalt pools. The substrate may include tungsten carbide
grains bonded together with a cobalt binder. Further, according to
some embodiments, an amount of the additive material used during
HPHT attachment may remain within the substrate. The attached
diamond body may be substantially free of eruptions and may include
a plurality of bonded together diamond grains and a plurality of
interstitial regions disposed among the bonded together diamond
grains. According to some embodiments, the diamond body may also
include an amount of the additive material used during HPHT
attachment. Further, according to some embodiments, the additive
material may be disposed at the interface between the substrate and
the diamond body. Additive material used to form diamond compacts
of the present disclosure may include a transition metal carbide
selected from at least one of VC, Mo.sub.2C, Cr.sub.3C.sub.2, NbC,
TaC and TiC. Further, diamond compacts of the present disclosure
may include up to 1.0 percent by weight of additive material, up to
0.08 percent by weight of additive material, and up to 0.05 percent
by weight of additive material according to some embodiments.
[0041] Diamond compacts formed according to methods of the present
disclosure may form cutting elements for use on a down hole tool.
Down hole tools may include, for example, bits having a body, a
plurality of blades extending from the body, and at least one
cutting element disposed on the plurality of blades. The cutting
element(s) may be disposed on the blades such that a cutting face,
i.e., a surface that contacts and cuts the formation being drilled,
is positioned at a leading face of the blade and faces in the
direction of the drill's rotation. The cutting element may be
formed according to methods disclosed herein, where a diamond body
is attached to a substrate having an additive material therein by
HPHT sintering.
[0042] Referring now to FIG. 6, a cross-sectional view of a cutting
element formed using an additive material according to methods
disclosed herein is shown. Particularly, the cutting element 600
may include a polycrystalline diamond table 610 attached to a
tungsten carbide substrate 620 at an interface 615, where the
polycrystalline diamond table 610 has a cutting face 605 opposite
from the interface 615. The polycrystalline diamond table 610 may
have a height 612 measured between the interface 615 and the
cutting face 605. According to embodiments of the present
disclosure, the height 612 may range from about 0.05 mm to about 12
mm. The polycrystalline diamond table. 610 may have a plurality of
bonded together diamond grains and a plurality of interstitial
regions disposed between the bonded together diamond grains, where
cobalt binder from the attached tungsten carbide substrate 620 may
occupy at least a portion of the interstitial regions. Further,
according to embodiments of the present disclosure, the additive
material may occupy at least a portion of the interstitial regions.
According to some embodiments of the present disclosure, cobalt
binder from the attached substrate and an amount of the additive
material may occupy the interstitial regions of the polycrystalline
diamond table throughout the entire height of the polycrystalline
diamond table. According to other embodiments, cobalt binder from
the attached substrate and an amount of the additive material may
occupy the interstitial regions of the polycrystalline diamond
table throughout a partial height of the polycrystalline diamond
table.
[0043] Although only a few example embodiments have been described
in detail above, those skilled in the art will readily appreciate
that many modifications are possible in the example embodiments
without materially departing from this invention. Accordingly, all
such modifications are intended to be included within the scope of
this disclosure as defined in the following claims.
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