U.S. patent application number 11/758537 was filed with the patent office on 2008-12-11 for polycrystalline diamond cutting elements having improved thermal resistance.
This patent application is currently assigned to SMITH INTERNATIONAL, INC.. Invention is credited to Peter Thomas CARIVEAU, Madapusi K. KESHAVAN.
Application Number | 20080302579 11/758537 |
Document ID | / |
Family ID | 39638037 |
Filed Date | 2008-12-11 |
United States Patent
Application |
20080302579 |
Kind Code |
A1 |
KESHAVAN; Madapusi K. ; et
al. |
December 11, 2008 |
POLYCRYSTALLINE DIAMOND CUTTING ELEMENTS HAVING IMPROVED THERMAL
RESISTANCE
Abstract
Polycrystalline diamond constructions of this invention have a
polycrystalline diamond body and a substrate attached thereto,
wherein the diamond body has a material microstructure comprising a
plurality of bonded-together diamond crystals forming a
polycrystalline matrix phase, and second phase formed from
different types of materials or sintering aids designed to reduce
or eliminate the amount of free Group VIII elements therein. The
use of such materials and the reduction and/or elimination of free
Group VIII elements, in addition to graphitization, facilitates the
sintering the construction at high pressure/high temperature
conditions, e.g., greater than about 65 Kbar, to produce a
construction having a high degree of thermal stability and/or
thermal resistance when compared to conventional PCD materials.
Polycrystalline diamond constructions of this invention are
preferably configured as cutting elements that are disposed on
drill bits used for drilling subterranean earthen formations.
Inventors: |
KESHAVAN; Madapusi K.; (The
Woodlands, TX) ; CARIVEAU; Peter Thomas; (Draper,
UT) |
Correspondence
Address: |
CONNOLLY BOVE LODGE & HUTZ LLP
P.O. BOX 2207
WILMINGTON
DE
19899
US
|
Assignee: |
SMITH INTERNATIONAL, INC.
Houston
TX
|
Family ID: |
39638037 |
Appl. No.: |
11/758537 |
Filed: |
June 5, 2007 |
Current U.S.
Class: |
175/434 |
Current CPC
Class: |
C04B 2235/3839 20130101;
C04B 2235/3847 20130101; C04B 2235/404 20130101; C04B 2235/3873
20130101; C04B 2235/3886 20130101; C04B 35/52 20130101; C04B
2235/3244 20130101; C04B 2235/3232 20130101; C04B 2235/3436
20130101; B22F 2005/001 20130101; C04B 2235/3217 20130101; C04B
2235/427 20130101; E21B 10/54 20130101; C04B 2235/3869 20130101;
C04B 2235/3445 20130101; E21B 10/5735 20130101; C04B 2235/3234
20130101; C04B 2235/3454 20130101; B22F 2005/002 20130101; C04B
2235/3843 20130101; B22F 7/08 20130101; C04B 2235/3427 20130101;
C04B 2235/3224 20130101; C04B 2235/3865 20130101; E21B 10/567
20130101; C22C 26/00 20130101; C04B 2235/3418 20130101; C04B
2235/3826 20130101 |
Class at
Publication: |
175/434 |
International
Class: |
E21B 10/46 20060101
E21B010/46 |
Claims
1. An earth boring drill bit comprising: a body having a number of
cutting elements attached thereto, wherein one or more of the
cutting elements includes a polycrystalline diamond construction
having a material microstructure comprising: a plurality of
bonded-together diamond crystals forming a polycrystalline matrix
phase, and an intermetallic compound interposed within a boundary
phase between the bonded-together diamond crystals, wherein the
intermetallic compound comprises a combination or reaction product
of one or more materials selected from Group VIII of the Periodic
Table, with Cr, Mn, Ti, Zr, Hf, V, Nb, Mo, W, Ta, and alloys
thereof; and a substrate attached to the polycrystalline diamond
construction, and wherein the substrate is formed from a material
selected from the group consisting of ceramics, metals, cermets,
and combinations thereof; wherein the polycrystalline diamond
construction is prepared by the process of: graphitizing part or
all of a precursor diamond powder used to form the polycrystalline
diamond construction, sintering the diamond powder in the presence
of precursor materials used to form the intermetallic compound
under high pressure conditions of greater than about 55 Kbar, and
under high temperature conditions to form the polycrystalline
diamond construction; and attaching the polycrystalline diamond
construction to the substrate.
2. The drill bit as recited in claim 1 wherein the body includes
one or more blades projecting outwardly therefrom, and the number
of cutting elements are attached to the one or more blades, and
wherein the polycrystalline diamond construction forms at least
part of a working surface of the cutting element.
3. The drill bit as recited in claim 1 further comprising a number
of legs extending away from the body, and a number of cones
rotatably attached to the legs, wherein the number of cutting
elements are attached to one or more of the cones, and wherein the
polycrystalline diamond construction forms at least part of a
working surface of the cutting element.
4. The drill bit as recited in claim 1 wherein the polycrystalline
diamond construction further comprises Pd.
5. The drill bit as recited in claim 4 wherein the Pd is disposed
on a surface of diamond grains in the diamond powder before the
step of sintering.
6. The drill bit as recited in claim 5 wherein the precursor
material used to form the intermetallic compound is disposed on a
surface of the Pd layer disposed on the diamond grains.
7. The drill bit as recited in claim 1 wherein the substrate
comprises a Group VIII element from the Periodic table, and an
intermediate layer is interposed between the polycrystalline
diamond construction and the substrate, and wherein the
intermediate layer is formed from a material that is substantially
free of a Group VIII element of the Periodic table.
8. The drill bit as recited in claim 1 wherein the substrate is
formed from a cermet material that is substantially free of a Group
VIII element of the Periodic table.
9. The drill bit as recited in claim 1 wherein the intermetallic
compound comprises a carbide of the materials selected from the
group consisting of Cr, Mn, Ti, Zr, Hf, V, Nb, Mo, W, Ta, and
alloys thereof.
10. The drill bit as recited in claim 1 wherein the step of
sintering the polycrystalline diamond construction takes place at a
pressure of greater than about 65 Kbar.
11. The drill bit as recited in claim 1 wherein the step of
sintering the polycrystalline diamond construction takes place at a
pressure of greater than about 70 Kbar.
12. The drill bit as recited in claim 1 wherein the step of
sintering the polycrystalline diamond construction takes place at a
temperature of from about 1,400 to 1,600 C.
13. The drill bit as recited in claim 1 wherein during the step of
graphitizing, less than about 10 percent by volume of diamond
grains in the diamond powder are graphitized.
14. The drill bit as recited in claim 1 wherein during the step of
graphitization, less than about 5 atomic layers of graphite are
formed on diamond grains in the diamond powder.
15. The drill bit as recited in claim 1 wherein one or more of the
materials selected from the group consisting of Cr, Mn, Ti, Zr, Hf,
V, Nb, Mo, W, Ta, and alloys thereof is present within the diamond
grains before sintering.
16. The drill bit as recited in claim 1 wherein one or more of the
materials selected from the group consisting of Cr, Mn, Ti, Zr, Hf,
V, Nb, Mo, W, Ta, and alloys thereof is added to the diamond grains
to form a diamond mixture before sintering.
17. The drill bit as recited in claim 1 wherein the materials used
to make the intermetallic compound comprises in the range of 0.01
to 10 percent by weight Cr, Mn, Ti, Zr, Hf, V, Nb, Mo, W, Ta, and
alloys thereof.
18. The drill bit as recited in claim 1 wherein before the step of
sintering, the diamond powder is disposed within a container that
is sealed off from the atmosphere.
19. The drill bit as recited in claim 1 wherein the polycrystalline
diamond construction has a diamond volume content of greater than
about 94 percent.
20. The drill bit as recited in claim 1 wherein the polycrystalline
diamond construction is substantially free of a material consisting
exclusively of a Group VIII element of the Periodic table.
21. A polycrystalline diamond construction comprising: a
polycrystalline diamond body having a material microstructure
comprising a plurality of bonded-together diamond crystals forming
a polycrystalline matrix phase, and an intermetallic compound
interposed within a boundary phase between the bonded-together
diamond crystals, wherein the intermetallic compound comprises a
combination or reaction product of one or more materials selected
from Group VIII of the Periodic Table, with Cr, Mn, Ti, Zr, Hf, V,
Nb, Mo, W, Ta, and alloys thereof, wherein the polycrystalline
diamond body is substantially free of a material consisting
exclusively of a Group VIII element of the Periodic table; and a
substrate attached to the polycrystalline diamond construction,
wherein the substrate is formed from a material selected from the
group consisting of ceramics, metals, cermets, and combinations
thereof that are substantially free of a Group VIII element of the
Periodic table; wherein the polycrystalline diamond construction is
prepared by the process of: placing the diamond powder within a
container that is sealed off from the atmosphere; sintering the
diamond powder in the presence of the materials used to form the
intermetallic compound under high pressure conditions of greater
than about 55 Kbar, and under high temperature conditions to form
the polycrystalline diamond construction, wherein some or all of
the materials used to form the intermetallic compound is present in
the diamond grains forming the diamond powder; and attaching the
polycrystalline diamond construction to the substrate.
22. The polycrystalline diamond construction as recited in claim 21
wherein the intermetallic compound is a carbide.
23. The polycrystalline diamond construction as recited in claim 22
wherein the materials used to make the intermetallic compound
comprises in the range of 0.01 to 10 percent by weight Cr, Mn, Ti,
Zr, Hf, V, Nb, Mo, W, Ta, and alloys thereof.
24. The polycrystalline diamond construction as recited in claim 21
wherein the process of preparing further comprises graphitizing
part or all of a precursor diamond powder used to form the
polycrystalline diamond body.
25. A polycrystalline diamond construction comprising: a
polycrystalline diamond body having a material microstructure
comprising a plurality of bonded-together diamond crystals forming
a polycrystalline matrix phase, and an intermetallic compound
interposed within a boundary phase between the bonded-together
diamond crystals, wherein the intermetallic compound comprises a
combination or reaction product of one or more materials selected
from Group VIII of the Periodic Table, with Cr, Mn, Ti, Zr, Hf, V,
Nb, Mo, W, Ta, and alloys thereof, wherein the polycrystalline
diamond body is substantially free of a material consisting
exclusively of a Group VIII element of the Periodic table, and has
a diamond volume content of greater than about 96 percent; and a
substrate attached to the polycrystalline diamond construction,
wherein the substrate is formed from a material selected from the
group consisting of ceramics, metals, cermets, and combinations
thereof; wherein the polycrystalline diamond construction comprises
a diamond content of about 96 percent by volume or more and is
prepared by the process of: graphitizing part or all of a precursor
diamond powder used to form the polycrystalline diamond body;
placing the diamond powder within a container that is sealed off
from the atmosphere; sintering the diamond powder in the presence
of the materials used to form the intermetallic compound under high
pressure conditions of greater than about 55 Kbar, and under high
temperature conditions to form the polycrystalline diamond
construction, wherein the materials used to form the intermetallic
compound are combined with the diamond powder to form a mixture
prior to sintering; and attaching the polycrystalline diamond
construction to the substrate.
26. The polycrystalline diamond construction as recited in claim 25
wherein the intermetallic compound is a carbide.
27. The polycrystalline diamond construction as recited in claim 26
wherein the materials used to make the intermetallic compound
comprises in the range of 0.01 to 10 percent by weight Cr, Mn, Ti,
Zr, Hf, V, Nb, Mo, W, Ta, and alloys thereof.
28. An earth boring drill bit comprising: a body and a number of
cutting elements attached thereto, one or more of the cutting
elements comprising a polycrystalline diamond construction that is
formed from a plurality of bonded-together diamond crystals,
wherein the polycrystalline diamond construction comprises: a
polycrystalline diamond body having a diamond volume content of
greater than about 94 percent; and a substrate attached to the
polycrystalline diamond body, wherein the substrate is formed from
a material selected from the group consisting of ceramics, metals,
cermets, and combinations thereof; wherein the polycrystalline
diamond construction is prepared by the process of: graphitizing
part or all of a precursor diamond powder used to form the
polycrystalline diamond construction; combining the graphitized
diamond powder with a sintering agent comprising Pd and one or more
further material selected from the group consisting of Fe, Co, Ni,
to form a diamond powder mixture, wherein the Pd is disposed on a
surface of diamond grains in the diamond powder and the one or more
further material is disposed on the Pd, and wherein the Pd and one
or more further materials are distributed homogeneously within the
diamond powder mixture; sintering the diamond powder mixture under
a high pressure condition of greater than about 55 Kbar and a high
temperature condition; and attaching the diamond body to the
substrate to form the polycrystalline diamond construction.
29. The drill bit as recited in claim 28 wherein the body includes
one or more blades projecting outwardly therefrom, and the number
of cutting elements are attached to the one or more blades, and
wherein the polycrystalline diamond construction forms at least
part of a working surface of the cutting element.
30. The drill bit as recited in claim 28 further comprising a
number of legs extending away from the body, and a number of cones
rotatably attached to the legs, wherein the number of cutting
elements are attached to one or more of the cones, and wherein the
polycrystalline diamond construction forms at least part of a
working surface of the cutting element.
31. The drill bit as recited in claim 28 wherein the Pd comprises
from 0.01 to 40 percent by weight of the total sintering agent.
32. The drill bit as recited in claim 28 wherein the sintering is
conducted at a pressure of greater than about 70 Kbar.
33. The drill bit as recited in claim 28 wherein the sintering is
conducted at a temperature of greater than about 1600.degree.
C.
34. The drill bit as recited in claim 28 wherein the sintering
agent additionally comprises one or more material selected from the
group consisting of Sn, P, B, and mixtures thereof.
35. The drill bit as recited in claim 28 wherein the sintering
agent additional comprises a tungsten material.
36. The drill bit as recited in claim 28 wherein the substrate is a
cermet material comprising a Group VIII element of the Periodic
table, and wherein the cutting element further comprises an
intermediate layer interposed between the substrate and the
polycrystalline diamond body that is formed from a material that is
substantially free of Group VIII elements of the Periodic
table.
37. The drill bit as recited in claim 28 wherein the substrate is a
cermet material that is substantially free from Group VIII elements
of the Periodic table.
38. The drill bit as recited in claim 28 wherein during the step of
graphitizing, less than about 10 percent by volume of diamond
grains in the diamond powder are graphitized.
39. The drill bit as recited in claim 28 wherein during the step of
graphitization, less than about 5 atomic layers of graphite are
formed on diamond grains in the diamond powder.
40. An earth boring drill bit comprising: a body having a number of
cutting attached thereto, one or more of the cutting elements
comprising a polycrystalline diamond construction comprising: a
polycrystalline diamond body comprising a plurality of
bonded-together diamond crystals; and a substrate attached to the
polycrystalline diamond body, wherein the substrate is formed from
a material selected from the group consisting of ceramics, metals,
cermets, and combinations thereof; wherein the polycrystalline
diamond construction is prepared by the process of: graphitizing
part or all of a precursor diamond powder used to form the
polycrystalline diamond body; combining the graphitized diamond
powder with a sintering aid comprising a compound having one or
more elements selected from the group consisting of Fe, Co, Ni, Mn,
Ti, TiO.sub.2, Si, Alkali earth metals, Alkaline earth metals, rare
earth elements, and O, wherein the compound is selected from the
group consisting of silicates, titanates, and oxides, and wherein
the diamond powder and the sintering aid is disposed within a
container that is sealed off from the atmosphere; sintering the
diamond powder and sintering aid under high pressure conditions of
greater than about 70 Kbar, and under high temperature conditions
to form the polycrystalline diamond body; and attaching the
polycrystalline diamond body to the substrate.
41. The drill bit as recited in claim 40 wherein the body includes
one or more blades projecting outwardly therefrom, and the number
of cutting elements are attached to the one or more blades, and
wherein the polycrystalline diamond construction forms at least
part of a working surface of the cutting element.
42. The drill bit as recited in claim 40 further comprising a
number of legs extending away from the body, and a number of cones
rotatably attached to the legs, wherein the number of cutting
elements are attached to one or more of the cones, and wherein the
polycrystalline diamond construction forms at least part of a
working surface of the cutting element.
43. The drill bit as recited in claim 40 wherein the compound is a
titanate of a metal selected from the group consisting of Fe, Co,
Ni, and Mn.
44. The drill bit as recited in claim 40 wherein the compound is a
titanate of one or more materials selected from the group
consisting of Ti, alkali metals, alkaline earth metals, and O.
45. The drill bit as recited in claim 40 wherein the compound is a
titanate of one or more materials selected from the group
consisting of Ti, rare earth elements, and O.
46. The drill bit as recited in claim 40 wherein the compound is a
composite oxide or solid solution of an oxide of one or more
materials selected from the group consisting of Fe, Co, Ni, Mn, and
TiO.sub.2.
47. The drill bit as recited in claim 40 wherein the compound is a
composite oxide or solid solution of an oxide of one or more
materials selected from the group consisting of TiO.sub.2, alkali
metals, and alkaline earth metals.
48. The drill bit as recited in claim 40 wherein the compound is a
composite oxide or solid solution of an oxide of one or more
materials selected from the group consisting of SiO.sub.2, and
alkaline earth metals.
49. The drill bit as recited in claim 40 wherein the compound is a
composite oxide or solid solution of an oxide of one or more
materials selected from the group consisting of SiO.sub.2, and rare
earth elements.
50. The drill bit as recited in claim 40 wherein the compound is a
composite oxide or solid solution of an oxide of one or more
materials selected from the group consisting of SiO.sub.2, and
TiO.sub.2.
51. The drill bit as recited in claim 40 wherein the compound is a
silicate of one or more materials selected from the group
consisting of alkaline earth elements, and rare earth elements.
52. The drill bit as recited in claim 40 wherein the substrate is a
cermet material comprising a Group VIII element of the Periodic
table, and wherein the cutting element further comprises an
intermediate layer interposed between the substrate and the
polycrystalline diamond body that is formed from a material that is
substantially free of a Group VIII element of the Periodic
table.
53. The drill bit as recited in claim 40 wherein the substrate is
carbide material that is substantially free of a Group VIII element
of the Periodic table.
54. The drill bit as recited in claim 40 wherein during the step of
graphitizing, less than about 10 percent by volume of diamond
grains in the diamond powder are graphitized.
55. The drill bit as recited in claim 40 wherein during the step of
graphitization, less than about 5 atomic layers of graphite are
formed on diamond grains in the diamond powder.
Description
FIELD OF THE INVENTION
[0001] This invention generally relates to cutting elements
comprising one or more regions of bonded together diamond crystals
and, more specifically, to cutting elements comprising bonded
together diamond crystals that are specially engineered to provide
an improved degree of thermal resistance during cutting and/or
wearing operations when compared to cutting elements that are
formed from conventional polycrystalline diamond materials, thereby
providing improved service life in desired cutting and/or drilling
applications.
BACKGROUND OF THE INVENTION
[0002] Polycrystalline diamond (PCD) materials and PCD elements
formed therefrom are well known in the art. Conventional PCD is
formed by combining synthetic diamond grains with a suitable
solvent catalyst material to form a mixture. The mixture is
subjected to processing conditions of extremely high pressure/high
temperature, where the solvent catalyst material promotes desired
intercrystalline diamond-to-diamond bonding between the grains,
thereby forming a PCD structure. The resulting PCD structure
produces enhanced properties of wear resistance and hardness,
making PCD materials extremely useful in aggressive wear and
cutting applications where high levels of wear resistance and
hardness are desired.
[0003] Solvent catalyst materials typically used for forming
conventional PCD include metals from Group VIII of the Periodic
table, with cobalt (Co) being the most common. Conventional PCD can
comprise from 85 to 95 percent by volume diamond and a remaining
amount solvent catalyst material. The material microstructure of
conventional PCD comprises regions of intercrystalline bonded
diamond with solvent catalyst material attached to the diamond
and/or disposed within interstices or interstitial regions that
exist between the intercrystalline bonded diamond regions.
[0004] A problem known to exist with such conventional PCD
materials is that they are vulnerable to thermal degradation, when
exposed to elevated temperature cutting and/or wear applications,
caused by the differential that exists between the thermal
expansion characteristics of the interstitial solvent metal
catalyst material and the thermal expansion characteristics of the
intercrystalline bonded diamond. Such differential thermal
expansion is known to occur at temperatures of about 400.degree.
C., can cause ruptures to occur in the diamond-to-diamond bonding,
and eventually result in the formation of cracks and chips in the
PCD structure during wear and/or cutting operations, rendering the
PCD structure unsuited for further use.
[0005] Another form of thermal degradation known to exist with
conventional PCD materials is one that is again related to the
presence of the solvent metal catalyst in the interstitial regions
and the adherence of the solvent metal catalyst to the diamond
crystals. Specifically, the solvent metal catalyst is known to
cause an undesired catalyzed phase transformation in diamond
(converting it to carbon monoxide, carbon dioxide, or graphite)
with increasing temperature, thereby limiting practical use of the
PCD material to about 750.degree. C.
[0006] Attempts at addressing such unwanted forms of thermal
degradation in conventional PCD materials are known in the art.
Generally, these attempts have focused developing a PCD body having
an improved degree of thermal stability or thermal resistance when
compared to the conventional PCD materials discussed above. One
known technique of improving the thermal stability of a PCD body is
by removing all or a portion of the solvent catalyst material
therefrom after it has been formed or sintered.
[0007] For example, U.S. Pat. No. 6,544,308 discloses a PCD element
having improved wear resistance comprising a diamond matrix body
that is integrally bonded to a metallic substrate. While the
diamond matrix body is formed using a catalyzing material during
high temperature/high pressure processing, the diamond matrix body
is subsequently treated to render a region extending from a working
surface substantially free of the catalyzing material. This same
technique is disclosed in Japanese Published Patent Application
59-219500.
[0008] Other attempts at improving the thermal stability or thermal
resistance of PCD has been to remove the catalyzing material from
not just a distinct region of the diamond body, but removing the
catalyst material from the entire diamond body, thereby forming
what is sometimes referred to in the art as thermally stable
polycrystalline diamond (TSP). While this approach produces an
entire diamond that is substantially free of the solvent catalyst
material, is it fairly time consuming. Additionally, a problem
known to exist with this approach is that the lack of solvent metal
catalyst within the diamond body precludes the subsequent
attachment of a metallic substrate to the diamond body by solvent
catalyst infiltration.
[0009] Additionally, such TSP materials have a coefficient of
thermal expansion that is sufficiently different from that of
conventional substrate materials (such as WC--Co and the like) that
are typically infiltrated or otherwise attached to the diamond
body. The attachment of such substrates to the diamond body is
highly desired to provide a diamond bonded compact that can be
readily adapted for use in many desirable applications. However,
the difference in thermal expansion characteristics between the TSP
body and the substrate, and the poor wettability of the TSP body
due to the substantial absence of solvent metal catalyst, makes it
very difficult to bond the TSP body to conventionally used
substrates. Accordingly, such TSP bodies must be attached or
mounted directly to a device for use, i.e., without the presence of
an adjoining substrate.
[0010] Since such TSP bodies are substantially devoid of a metallic
substrate they cannot (e.g., when configured for use as a drill bit
cutter) be attached to a drill bit by conventional brazing process.
The use of such TSP body in this particular application
necessitates that the TSP body itself be mounted to the drill bit
by mechanical or interference fit during manufacturing of the drill
bit, which is labor intensive, time consuming, and does not provide
a most secure method of attachment.
[0011] While these above-noted known approaches provide insight
into diamond bonded constructions capable of providing some
improved degree of thermal stability or thermal resistance when
compared to conventional PCD materials, it is believed that further
improvements in thermal stability for PCD materials useful for
desired cutting and/or wear applications can be obtained according
to different approaches that are both capable of minimizing the
amount of time and effort necessary to achieve the same, and that
permit formation of a PCD compact comprising a desired substrate
bonded thereto to facilitate attachment of the compact with a
desired application device, e.g., a bit for drilling earthen
formations.
[0012] It is, therefore, desired that polycrystalline diamond
constructions and compacts useful in cutting and/or wear
applications be developed that include a diamond bonded body having
an improved degree of thermal stability and/or resistance when
compared to conventional PCD materials, and that can be engineered
to include a substrate material bonded thereto to facilitate
formation of a compact to permit attachment of the same to an
application device by conventional method such as welding or
brazing and the like.
SUMMARY OF THE INVENTION
[0013] Polycrystalline diamond constructions can be prepared and/or
embodied differently within the scope of this invention. In one
example embodiment, the polycrystalline diamond construction has a
material microstructure comprising a plurality of bonded-together
diamond crystals forming a polycrystalline matrix phase, and an
intermetallic compound interposed within a boundary phase between
the bonded-together diamond crystals. The intermetallic compound
comprises a combination or reaction product of one or more
materials selected from Group VIII of the Periodic Table, with Cr,
Mn, Ti, Zr, Hf, V, Nb, Mo, W, Ta, and alloys thereof. The
intermetallic compound operates to stabilize any solvent metal
catalyst from Group VIII of the periodic table such that the
resulting polycrystalline diamond construction is substantially
free of a material consisting exclusively of a Group VIII element.
In an example embodiment, the materials selected from the group
consisting of Cr, Mn, Ti, Zr, Hf, V, Nb, Mo, W, Ta, and alloys
thereof are a carbide.
[0014] Other materials useful for forming the polycrystalline
diamond construction include Pd. The polycrystalline diamond
construction may further comprise a substrate attached thereto that
is formed from formed materials selected from the group consisting
of ceramics, metals, cermets, and combinations thereof.
[0015] Such example polycrystalline diamond construction can be
prepared by the process of graphitizing part or all of a precursor
diamond powder used to form the polycrystalline diamond
construction. The diamond powder is then sintered in the presence
of precursor materials used to form the intermetallic compound
under high pressure conditions of greater than about 55 Kbar, and
under high temperature conditions to form the polycrystalline
diamond construction. Such sintering can take place at pressures
greater than about 65 Kbar, and greater than about 70 Kbar. Such
sintering can take place at elevated temperatures of from about
1,400 to 1,600.degree. C. The precursor materials can either be
present in the form of separate powders or can be present as part
of the diamond powder. In the event that the polycrystalline
diamond construction includes a substrate, such substrate is also
attached thereto, which attachment can take place during or after
the sintering step.
[0016] In another embodiment, the polycrystalline diamond
construction comprises a polycrystalline diamond body including a
plurality of bonded-together diamond crystals. The polycrystalline
diamond body has a diamond volume content of greater than about 94
percent, and the polycrystalline diamond construction may include a
substrate attached to the polycrystalline diamond body.
[0017] The polycrystalline diamond construction of this embodiment
is prepared by graphitizing part or all of a precursor diamond
powder used to form the polycrystalline diamond construction. The
graphitized diamond powder is combined with a sintering agent
comprising Pd and one or more further material selected from the
group consisting of Fe, Co, Ni, to form a diamond powder mixture.
The Pd is disposed on a surface of diamond grains in the diamond
powder, and the one or more further material is disposed on the Pd.
The Pd may comprise from 0.01 to 40 percent by weight of the total
sintering agent. If desired, the sintering agent can further
include one or more material selected from the group consisting of
Sn, P, B, W, and mixtures thereof.
[0018] In an example embodiment, the Pd and one or more further
materials are distributed homogeneously within the diamond powder
mixture. The mixture is then sintered under a high pressure
condition of greater than about 55 Kbar and a high temperature
condition, and the substrate is attached to the polycrystalline
diamond body. The sintering pressures and temperature can be the
same as noted above for the first example embodiment.
[0019] A further example polycrystalline diamond construction of
this invention comprises a polycrystalline diamond body including a
plurality of bonded-together diamond crystals, and a substrate
attached to the body. The polycrystalline diamond construction is
prepared by graphitizing part or all of a precursor diamond powder
used to form the polycrystalline diamond body. The graphitized
diamond powder is combined with a sintering aid comprising a
compound having one or more elements selected from the group
consisting of Fe, Co, Ni, Mn, Ti, TiO.sub.2, Si, Alkali earth
metals, Alkaline earth metals, rare earth elements, and O. The
sintering aid compound is selected from the group consisting of
silicates, titanates, and oxides. In a preferred embodiment, the
diamond powder and the sintering aid are disposed within a
container that is sealed off from the atmosphere. The diamond
powder and sintering aid is sintered under high pressure conditions
of greater than about 70 Kbar, and under high temperature
conditions to form the polycrystalline diamond body. The substrate
is attached to the polycrystalline diamond body to the
substrate.
[0020] In all of the example embodiments, the substrate material
may or may not include a Group VIII element from the Periodic
table, e.g., the substrate can be substantially free of a Group
VIII element of the Periodic table. In the event that the substrate
does include a Group VIII element, the polycrystalline diamond
construction may include an intermediate layer interposed between
the polycrystalline diamond construction and the substrate to
provide a desired attachment and to minimize and/or to act as a
barrier to minimize and/or eliminate the migration of the Group
VIII element from the substrate to the polycrystalline diamond
construction.
[0021] The polycrystalline diamond constructions of this invention
are particularly well suited for use as a wear and/cutting element
in a wear and/or cutting device. In a preferred embodiment, the
polycrystalline diamond constructions of this invention are
configured as cutting elements, forming at least part of a working
surface of the cutting element. The cutting elements can be used
with a bit for drilling subterranean earthen formations. In one
embodiment, the drill bit comprises a body having one or more
blades projecting outwardly therefrom, and includes a number of the
cutting elements attached to the one or more blades, and wherein
the polycrystalline diamond construction forms at least part of a
working surface of the cutting element. In another embodiment, the
drill bit comprises a number of legs extending away from the body,
and a number of cones rotatably attached to the legs, wherein the
number of cutting elements is attached to one or more of the
cones.
[0022] Such polycrystalline diamond constructions of this invention
display improved properties of thermal stability and/or thermal
resistance when compared to conventional PCD materials, and are
engineered to include a substrate material bonded thereto to
facilitate attachment of the construction, e.g., when configured as
a wear and/or cutting element, by conventional method such as
welding or brazing and the like.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] These and other features and advantages of the present
invention will be appreciated as the same becomes better understood
by reference to the following detailed description when considered
in connection with the accompanying drawings wherein:
[0024] FIGS. 1A to 1E are perspective views of different
polycrystalline diamond compacts of this invention
[0025] FIG. 2 is a perspective side view of an insert, for use in a
roller cone or a hammer drill bit, comprising the polycrystalline
diamond compact of this invention;
[0026] FIG. 3 is a perspective side view of a roller cone drill bit
comprising a number of the inserts of FIG. 2;
[0027] FIG. 4 is a perspective side view of a percussion or hammer
bit comprising a number of inserts of FIG. 3;
[0028] FIG. 5 is a schematic perspective side view of a diamond
shear cutter comprising the polycrystalline diamond compact of this
invention; and
[0029] FIG. 6 is a perspective side view of a drag bit comprising a
number of the shear cutters of FIG. 5.
DETAILED DESCRIPTION
[0030] PCD bodies of this invention are specially engineered having
a diamond-bonded body having an improved degree of thermal
stability when compared to conventional PCD materials. Such PCD
bodies can further include a substrate attached thereto, thereby
forming a compact, to facilitate attachment of the compact to a
desired cutting or wear device, e.g., a bit for drilling earthen
formations, by conventional means such as by welding, or brazing
and the like.
[0031] In a first example embodiment, PCD bodies of this invention
are prepared by subjecting a mixture of synthetic diamond powders
of desired size and/or distribution, with a suitable diamond
synthesizing catalyst material. Diamond powders useful for forming
PCD bodies of this first example embodiment have an average
diameter grain size in the range of from submicrometer to about 0.1
mm in size, and more preferably in the range of from about 0.005 mm
to 0.08 mm. The diamond powder can contain grains having a mono or
multi-modal size distribution. In a preferred embodiment for a
particular application, the diamond powder has an average particle
grain size of approximately 5 to 30 micrometers. However, it is to
be understood that the use of diamond grains having a grain size
outside of this range may be useful for certain cutting and/or wear
applications. 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.
[0032] Example diamond synthesizing catalyst materials include
Group VIII iron metals, or Cr, Mn, Ta or alloys containing them.
The catalyst material is present at a ratio of from about 0.01 to
about 10 percent by weight relative to the diamond powder. In a
preferred embodiment, the diamond powder and/or mixture of the
diamond powder and the catalyst material is wholly or partially
graphitized, which can occur by subjecting the diamond powder or
mixture to a graphite material by coating process or the like, or
which can occur by subjecting the diamond powder and/or the mixture
of diamond powder and the catalyst material to a high temperature
condition, to graphitize a part or whole thereof. In a preferred
embodiment, the mixture is at least partially graphitized by
heating the diamond powder at a temperature of about 1,400.degree.
C. or more in vacuum or a nonoxidizing atmosphere.
[0033] In an example embodiment, it is desired that in the range of
from about 0.5 to 25 percent by volume of the diamond grains be
graphitized, and more preferably less than about 10 percent by
volume. The extent of the diamond grains that are graphitized can
and will vary depending on a number of factors that include the
particular grain size of the diamond powder, the process/sintering
conditions, and the end use application for the PCD body.
[0034] Alternatively, instead of forming graphite from the diamond
grains used to form the PCD body, graphitization is understood to
include the process of adding graphite in the form of powder or the
like to the diamond grains or powder used for forming the PCD
body.
[0035] In preparing the first embodiment PCD body, it is further
desired that one or more materials selected from the group
consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W and the like, and
mixtures thereof be added to the diamond powder and catalyst
material mixture. Such other materials can be added to the mixture
as a raw material before processing, or can be included as part of
the diamond powder, e.g., infiltrated or otherwise contained in the
diamond grains. In an example embodiment, such materials can be
provided during processing from a pressure vessel that is made from
such material. In an example embodiment, such additional material
is diffused into the diamond powder and catalyst material mixture
from a pressure vessel formed from the desired additional material
during a high pressure/high temperature (HPHT) sintering process.
In an example embodiment, a mixture of graphitized diamond powder
and catalyst material is loaded into such a pressure vessel, and
the pressure vessel is subjected to HPHT process conditions of
about 50 Kbar or more, and about 1,400.degree. C. or more. In a
preferred embodiment, the graphitized mixture is sintered at a high
pressure of about 70 Kbar or more, and at a high temperature of
about 1,600.degree. C. or more using a suitable HPHT device, such
as a belt press, a cubic press, a torroid press, or the like.
[0036] During such HPHT processing, the diamond powder is sintered
and intermetallic compounds, consisting of metals or alloys thereof
contained in the raw materials and metals from the reaction vessel,
are formed. The resulting sintered PCD body comprises a ratio of
about 0.01 to 12 percent by weight of the intermetallic compounds
relative to bonded diamond crystals.
[0037] In this first example embodiment, synthetic diamond powders
including Group VIII iron metals of the Periodic table, or Cr, Mn,
Ta or alloys thereof are used as a catalyst in the synthesis of
diamond as impurities, or boron-containing synthetic diamond
powders including Group VIII iron metals, or Cr, Mn, Ta or alloys
thereof can be used as a catalyst in the synthesis of diamond in
crystals thereof, as impurities in the powders used as the raw
materials for forming the PCD body.
[0038] In an example embodiment, synthetic diamond powders
containing the specified quantity of the catalyst material as an
inclusion are wholly or partially graphitized by heating in the
manner noted above prior to sintering. The graphitized powders are
filled in a pressure or reactive vessel made from at least one
metal selected from a group consisting of Ti, Zr, Hf, V, Nb, Ta,
Cr, Mo, W and the like, and the contents of the vessel are sintered
at a super-high pressure and high temperature, under which diamond
is stable, while preventing said metals or alloys thereof from
raiding thereinto from outside of the system, e.g., with the use of
iron group materials and Cr, Mn, and/or Ta in the raw material.
[0039] It was found that where synthetic diamond powders, including
metallic impurities therein at a ratio of about 0.01 to 10 percent
by weight, were used as the starting raw materials, graphitized
diamond was converted to diamond again in the sintering process,
thereby providing a sintered diamond body. Using less than about
0.1 percent by weight of the metallic impurities results in a
mixture that can be difficult to sinter when it is graphitized,
while using more than about 10 percent by weight metallic
impurities can produce a sintered diamond body that does not have a
desired degree of thermal stability or resistance well suited for
use in certain cutting and/or wear applications, e.g., such as a
cutting element for use with a drill bit.
[0040] As noted above, it may be desired that PCD bodies of this
first example embodiment be formed optionally using Boron.
Synthetic diamond powders useful for making PCD bodies of this
invention may include catalyst metal impurities at a ratio of from
about 0.01 to about 3 percent by weight and boron. Boron can be
added to form a solid solution at a ratio of about 0.001 to about 1
percent by weight. PCD bodies formed using boron display an
electrical conductivity almost equivalent to that of the
conventional PCD formed by using cobalt as a catalyst material, are
remarkably compact and strong, and further display improved thermal
stability or resistance when compared to conventional PCD
materials.
[0041] PCD bodies of this first example embodiment display improved
thermal stability or resistance, despite the presence of a catalyst
material, when subjected to operating temperatures of about
1,000.degree. C. The improved thermal stability is believed due
partly to the relatively small metal content used in making such
first example embodiment PCD bodies, when compared to conventional
PCD formed by sintering diamond grains impregnated with cobalt.
Further, such improved thermal stability is also believed due to
the different characteristics and distribution of the metals used
in forming the sintered diamond body.
[0042] Specifically, sintered PCD bodies of this first example
embodiment appear to have diamond crystalline particles that are
very closely joined together, as though the catalyst material
existed within the crystalline particles themselves rather than on
the grain boundary of the particles, such as that found in
conventional PCD where the catalyst metal exists on the boundary
surface of the diamond particles in the form of a thin film. In
conventional PCD, the presence of cobalt on the boundary surface is
a result of the cobalt infiltrating into the gaps between the
diamond powder during the sintering process, and acting as the
bonding phase.
[0043] PCD bodies of the first example embodiment include a small
amount of thin film-like-metal on the grain boundary of the
diamond. However, the thin film is provided in the form of an
intermetallic compound that is formed by the action of the at least
one of the materials selected from the group consisting of Ti, Zr,
Hf, V, Nb, Ta, Cr, Mo, W and the like being diffused into the raw
materials during the sintering process, and being combined or
reacting with the catalyst metal. Thus, the metallic phase in the
resulting sintered PCD body is not the catalyst metal, and the
contact surface area between the metallic phase (in the form of the
intermetallic compound) and the diamond is relatively small.
[0044] Thus, the nature of the intermetallic phase (not being
exclusively catalyst metal), the manner in which the metallic phase
is present and/or distributed in the sintered PCD body, and the
relatively small amount of the metallic phase, is believed
responsible for making the PCD body more resistant to
graphitization during high temperature operations, thereby
providing a PCD body having improved thermal stability and thermal
resistance when compared to conventional PCD materials.
[0045] PCD bodies of this first example embodiment may be better
understood with reference to the following example:
EXAMPLE
First Example Embodiment PCD Body
[0046] Synthetic diamond powders having a mean particle size of
approximately 25 micrometers and containing the following metallic
impurities were used as the starting material. Sample A: Fe--600
ppm; Ni--79,400 ppm; Cr--4300 ppm; Mn--300 ppm; and Ta--200 ppm.
Sample B: Fe--1,600 ppm; Ni--11,900 ppm; Cr--500 ppm; Mn--100 ppm;
and Ta--500 ppm. The numerical values provided above for the
metallic impurities are measured by using a mass spectrometer. Each
of the samples is held in a vacuum furnace at approximately
1,400.degree. C. for one hour. The diamond powders are taken out of
the vacuum furnace and then tested for degree of graphitization by
X-ray diffraction method. Samples A displayed a partial
graphitization of approximately 90 percent by weight, and Sample B
displayed a partial graphitization of approximately 50 percent by
weight. The graphitized Sample A and B powders are each loaded into
respective vessels made of Ta, and then the vessels are sealed
hermetically. Subsequently, the vessels are held at a pressure of
approximately 50 Kbar and a temperature of 1,400.degree. C. for
five minutes in a belt-type super-high pressure apparatus to sinter
the powders.
[0047] The sintered PCD bodies resulting from the Sample A and B
mixtures displayed good abrasion resistance and improved thermal
stability and thermal resistance when compared to conventional PCD
materials. In particular, the thermal resistance was remarkably
improved without reducing the strength of the sintered PCD body,
making such PCD bodies well suited for use as cutting and/or wear
elements on bits used for drilling subterranean formations.
[0048] In a second example embodiment, PCD bodies of this invention
are formed by combining diamond powder, having a desired grain size
or grain size distribution, with a sintering aid or sintering
agent. The diamond powder can be of the same average grain sizes
described above for the first example embodiment, and can comprise
a mono or multimodal distribution of diamond grain sizes. In a
preferred embodiment, the diamond grain size is in the range of
from about 0.1 micrometer to about 70 micrometers, and more
preferably in the range from about 5 to 30-micrometers. Using
diamond grains sized less than about 0.1 micrometers may make
providing a coating of the sintering aid thereon difficult, and/or
may provide a relatively large diamond surface area that may
promote unwanted abnormal diamond growth during sintering, which
can reduce the wear resistance of the resulting sintered PCD body.
Using diamond grains sized greater than about 70 micrometers may
promote unwanted cleavage of the sintered diamond particles, which
could reduce the strength of the sintered PCD body.
[0049] Sintering aids useful for forming second embodiment PCD
bodies of this invention include palladium (Pd) within the range of
from about 0.1 to 40 percent by weight, based on the total weight
of the sintering aid. Pd is useful for reducing the melting point
of the sintering aid, thereby enabling sintering of the PCD body at
relatively low temperatures. If less than about 0.1 percent by
weight Pd is used, the amount may be ineffective for lowing the
melting point of the sintering aid to provide a desired reduction
in the sintering temperature. If greater than about 40 percent by
weight Pd is used, the melting point of the sintering aid
conversely increases, thereby making sintering difficult.
[0050] The sintering aid can also include at least one sintering
assist agent selected from the group of materials including iron
(Fe), cobalt (Co), nickel (Ni), and combinations thereof. In an
example embodiment, the sintering aid includes Pd, in the amount
described above, with a remainder being at least one sintering
assist agent selected from the group including Fe, Co, Ni, and
mixtures thereof.
[0051] PCD bodies of this second example embodiment can be made by
preparing a diamond powder having a desired particle size described
above, precipitating or otherwise disposing Pd within the range
described above onto the surface of each particle of the diamond
powder, and disposing the sintering assist agent including at least
one component selected from Fe, Co, Ni, and mixtures thereof within
the range of about 4 to 20 percent by volume onto the surface of
each particle of the diamond powder, and thus preparing a coated
diamond powder.
[0052] The sintering aid and sintering assist agent are preferably
homogeneously distributed in the sintered diamond particles and do
not contain unnecessary components. The sintering aid and assist
agent are preferably applied to the diamond grains or diamond
powder by spray or deposition process, such as by using chemical
vapor deposition (CVD) methods, physical vapor deposition (PVD)
methods, atomic level deposition (ALD) methods, solution
precipitation methods, or the like. An electroless plating
technique can also be used to coat or otherwise apply the sintering
aid and/or sintering assist agent onto the diamond grains, as
disclosed in Japanese Patent Laying-Open No. 8-225875, which is
incorporated herein by reference. It is desired that the method
that is used be one that is capable of providing a uniform
thickness of the sintering assistant agent to thereby promote
improve the sintering property of the powder and the strength of
the resulting sintered PCD body.
[0053] The so-formed coated diamond powder is loaded into an
appropriate pressure or reaction vessel and the vessel is loaded
into a device capable of subjecting the vessel contents to HPHT
conditions sufficient to cause liquid-phase sintering.
[0054] Distributing the sintering aid and sintering assist agent
homogeneously along the diamond grains by coating the surface of
the diamond grains using any one of the above-described techniques
is desired for the purpose of facilitating the sintering process
and for improving the material structure and properties of the
resulting sintered PCD body. Further, the technique of coating the
diamond grains with the sintering aid and/or sintering assist agent
improves the ability to not only provide a controlled homogeneous
distribution of the sintering aid within the diamond powder
mixture, but provide tight controls over the amount of the
sintering aid (and/or the materials used to form the sintering aid)
that is used. For examples, using ALD, one can control the amount
of material that is applied to the surface of a diamond grain to
one or two atomic layers if so desired.
[0055] Alternatively, PCD bodies of this second example embodiment
can be prepared by preparing a diamond powder having a particle
size as described above, precipitating or otherwise disposing Pd
within the range of about 0.01 to 40 percent by weight onto the
surface of each particle of the diamond powder, and then applying a
sintering assist agent by appropriate technique disclosed above
including at least one component selected from Fe, Co, Ni and
combinations thereof within the range of 0.1 to 20 percent by
volume onto the surface of each particle of the diamond powder, to
thus prepare a coated diamond powder. The coated diamond powder can
then be molded in a body, and an additional sintering assist agent
including at least one of Pd, Fe, Co, Ni, and combinations thereof
can be placed into contact with the powder compact body. The
so-formed molded body is then subjected to liquid-phase sintering
at HPHT conditions, during which conditions the additional
sintering assist agent is infiltrated into the powder compact
body.
[0056] The process of coating the diamond powder particles is
desired for the purpose of providing a greater degree of uniformity
over the distribution of the sintering material in the mixture
during liquid phase sintering, thereby minimizing or avoiding the
presence of unwanted voids and/or pools of the sintering material
that may adversely impact the material structure of the sintered
PCD body. Further supplementing the sintering aid, the sintering
assist agent has been found to further improve uniform infiltration
during sintering.
[0057] Additionally, by using a diamond powder coated with the
above-described sintering agents, uniform melting or infiltration
of the sintering assist agent occurs, so that sintering becomes
possible under conditions that were otherwise not suitable for
sintering, e.g., at a reduced temperature conditions, thereby
enabling formation of a PCD body having a high diamond content, and
desired properties of thermal resistance, strength, and wear
resistance at a reduced sintering temperature.
[0058] In this second example embodiment PCD body, any of Pd, Fe,
Co and Ni can be used by itself as the sintering assist agent for
the diamond powder. However, when the sintering assist agent
includes Pd in addition to at least one of Fe, Co and Ni, the
melting point of the sintering assist agent is reduced and the
sintering property of the diamond powder is remarkably
improved.
[0059] In an example embodiment, it is desired that the coated
diamond powder comprises at least about 4 percent by weight of the
sintering assist agent to facilitate the above-noted sintering
process that will produce a desired sintered PCD body having
above-noted performance properties. It is desired that the amount
of the sintering assist agent used for this example embodiment be
20 percent by volume at most, as the resulting wear-resistance of
the sintered PCD body in view of the reduced diamond content may
not be at a level well suited for certain wear and/or cutting
applications.
[0060] Similarly, when sintering of the coated diamond powder is to
be performed in the presence of the additional sintering assist
agent, the amount of the sintering assist agent should preferably
be at least about 0.1 percent by volume. If the amount of the
sintering assist agent is less than about 0.1 percent by volume,
then uniform coating by the sintering assist agent on the surface
of the diamond particles becomes difficult, making uniform
infiltration of the additional sintering assist agent difficult. If
the total sintering assist agent in the sintered body exceeds about
20 percent by volume, the diamond content is reduced, which can
produce a sintered PCD body having a degree of wear resistance that
may be less than that desired for certain wear and/or cutting
applications.
[0061] When the sintering assistant agent is to be precipitated
onto the surface of the diamond particles by electroless plating,
mixing or inclusion of impurities in the sintering assistant agent
should be prevented as much as possible, in order to obtain a high
diamond content after sintering. Considering the fact that
catalytic nuclei having high catalytic action must exist on the
surface of the diamond particles in the initial reaction of
electroless plating, it is preferred that Pd, exhibiting not only
the function of a sintering aid but also a desired catalytic
action, be coated first onto the surface of the diamond particles.
By providing a coating of a sintering assist agent including at
least one of Fe, Co and Ni with Pd serving as catalytic nuclei, a
coated diamond particle coated with a sintering assistant agent
having a smaller amount or degree of impurity can be obtained.
[0062] In an example embodiment, it is desired that the amount of
Pd precipitated onto the surface of the diamond particle be at
least 10.sup.-4 percent by weight to provide a sufficient
electroless plating reaction to facilitate providing a coating of
the sintering assist agent thereon. If the amount of precipitated
Pd is greater than about 40 percent by weight, then the melting
point of the sintering assistant agent will be elevated,
potentially degrading the sintering property of the PCD body.
[0063] The sintering assist agent can also include at least one
material selected from the group including tin (Sn), phosphorous
(P), and boron (B), in addition to the iron family metal, wherein
the Sn, P and/or B serves to lower the melting point of the
sintering assist agent, significantly improving the sintering
property of the diamond powder coated by the sintering assist
agent.
[0064] Further, the sintering assist agent can optionally include
metal tungsten. As used herein, the substance referred to as
"tungsten" can be metallic tungsten (W) or a tungsten compound such
as tungsten carbide (WC) or the like. In an example embodiment, the
content of tungsten in the sintered PCD body can be up to about 8
percent by weight, based on the total weight of the sintering
assist agent. Tungsten has been found useful in controlling
unwanted diamond growth that may occur during the sintering
process.
[0065] The presence of oxygen (O) or oxide adsorbed at the surface
of the diamond powder particles in a raw material for manufacturing
a diamond sintered body may contribute to defects in the sintered
body. Thus, it is desired that amount of oxygen in PCD bodies
formed according to this second example embodiment be controlled,
and in an example embodiment comprise oxygen in the range from
about 0.005 to 0.08 percent by weight.
[0066] As for precipitation of P in addition to the iron family
element, a sintering assist agent having a desired P concentration
can be precipitated by using a hypophosphite, for example sodium
hypophosphite, as a reducing agent in the electroless plating
solution, and by adjusting the concentration of the reducing agent
in the plating solution, the pH of the plating solution, and the
temperature during plating. Similarly, for precipitation of B in
addition to the iron family element, a sintering assist agent
having a desired B concentration can be precipitated by using a
boron hydride compound, such as sodium borohydride, as the reducing
agent in the electroless plating solution, and by adjusting the
concentration of the reducing agent in the plating solution, the pH
of the plating solution, and the temperature during plating.
[0067] Sn has a superior absorption property with respect to the
surface of the diamond powder particle. Therefore, it can be
directly absorbed onto the diamond particle surface from a tin
chloride solution, for example. Further, precipitation of Pd
serving as the catalytic nucleus after absorption of Sn onto the
diamond particle surface as pre-processing for electroless plating
(sensitizing activating method), or precipitation of Sn and Pd
simultaneously (catalyst accelerating method) is preferable, since
it promotes absorption of Pd at the surface of the diamond
particles.
[0068] If the total content of Sn, P and B in the sintering assist
agent is less than about 0.01 percent by weight, then the desired
effect of lowering the melting point of the sintering assistant
agent may not be achieved. By contrast, if the total content of Sn,
P and B exceeds about 30 percent by weight, then melting of diamond
to the iron family metal which serves as a solvent metal in the
sintering assist agent at the time of sintering is hindered, so
that the binding strength between diamond particles becomes lower,
thus degrading the strength and the thermal properties of the
resulting sintered PCD body. In an example embodiment, the total
content of Sn, P and B in the sintering assist agent is preferably
within the range of about 0.01 to 11.5 percent by weight.
[0069] When the diamond particles are to be coated with the
sintering assist agent by electroless plating, the iron family
element precipitated by electroless plating is, in most cases,
precipitated as an oxide. If sintering is performed using a
sintering assist agent including an oxide, oxygen derived from the
oxide may possibly generate voids in the sintered body, and it may
hinder the melting and precipitation reaction of diamond in the
sintering assistant agent serving as the solvent. Therefore, it may
degrade the property of the diamond sintered body. In order to
prevent such an undesirable effect caused by oxygen, the coated
diamond powder after electroless plating should preferably be
reduced by heat treatment in a vacuum or in a hydrogen
atmosphere.
[0070] When electroless plating is performed on the diamond powder,
the diamond powder can be coated uniformly by the sintering assist
agent if the plating solution including the diamond powder is
fluctuated or agitated by at least one of stirring and ultrasonic
vibration. Further, in order to obtain a diamond sintered body
having higher density, it may be desired to develop a graphite
coating on the diamond particles, which graphite coating can be
provided in the manner described above for the first example
embodiment PCD body. In an example embodiment, the graphite coating
is formed by heating the diamond powder at high temperature
conditions under which the diamond is unstable so that at least a
surface portion thereof is converted into graphite. The partially
graphitized diamond particles are then coated with the sintering
assist agent as described above and the coated particles are
thereafter sintered. Alternatively, the diamond particles can be
coated with the sintering assist agent and then the coated
particles can be at least partially graphitized, and thereafter the
coated graphitized particles can be sintered.
[0071] Graphitizing at least a portion of the diamond particle
surface is desired because the diamond powder itself is not
susceptible to plastic deformation, even under high pressure,
causing spaces that tend to remain between diamond particles.
However, graphite is susceptible to plastic deformation, and the
surface portion that is graphitized can plastically deform under
pressure, causing the density of the sintered body to be
substantially improved. Further, considering melting of carbon and
re-precipitation thereof in the sintering assist agent during
sintering, the speed of reaction of graphite is faster than that of
diamond, and hence the sintering property is improved if the
diamond surface is turned into graphite.
[0072] For these reasons, it is believed that at least partially
graphitizing the diamond particles operates to produce a sintered
PCD body having a diamond density that is higher than can otherwise
be achieved without graphitization. In an example embodiment, it is
desired that the ratio of graphitization of the diamond particles
be in the range of from about 0.5 percent by volume to about 25
percent by volume, and preferably less than about 10 percent by
volume.
[0073] It is possible that various other materials can be included
in the sintered PCD body in small quantities. For example, the
coated diamond powder is generally filled into a vessel formed of a
cemented carbide or a refractory metal and then sintered.
Therefore, one or more materials selected from the group consisting
of W, Ta, Mo, and Cr, which are the components of the vessel, or
carbides thereof, may possibly be mixed into and present in the
sintered body. However, in the event that such additional materials
are mixed into the sintered body, it is desired that the diamond
content in the sintered PCD body be within the range of about 80 to
96 percent by volume.
[0074] Similarly, even when the additional sintering assist agent
is brought into contact with the powder compact body to supplement
the sintering assist agent in the coated diamond powder, and
infiltrated into the powder compact body during sintering, it is
desired that the diamond content of the sintered body be within the
range of about 80 to 96 percent by volume. The additional sintering
assist agent arranged in contact with such powder compact body may
have similar compositions as those for the sintering assist agent
used for coating of the diamond particle.
[0075] PCD bodies formed according to the second example embodiment
of this invention can be better understood with reference to the
following Examples.
EXAMPLE
Second Example Embodiment PCD Body
[0076] Diamond powder having an average grain size of approximately
0.1 to 4 micrometers is selected and two different samples (Samples
A and B) are prepared by coating the powder with different volume
percentages of the sintering assist agent. For both samples, the
sintering assist agent is applied by electroless plating technique
and the diamond powder is prepared in the following manner. First,
the diamond powder is degreased in alcohol. The degreased diamond
powder is cleaned in flowing water, cleaned in a hydrochloric acid
solution of approximately five percent by weight, and then again
cleaned in flowing water. The diamond powder thus cleaned is
immersed for one minute in a solution including stannous chloride
and hydrochloric acid at room temperature as pre-processing, so as
to cause absorption of Sn at the surface of the diamond particles
(sensitizing). The sensitized diamond powder is washed with water
and thereafter immersed for one minute in a hydrochloric acid
solution containing palladium chloride at room temperature, and
thus Pd is precipitated at the surface of the diamond particles
(activated).
[0077] The activated diamond powder is washed with water, and
thereafter immersed for a prescribed time period in a Co--Fe--P
electroless plating solution held at approximately 75.degree. C.,
containing cobalt sulfate, iron sulfate and sodium hypophosphite.
The longer the time of immersion in the electroless plating
solution, the larger the amount of sintering assist agent coated
onto the surface of the diamond particles, and the larger the
content of the sintering assist agent in the powder samples. In the
step of electroless plating, the preplating solution and plating
solution are stirred and at the same time subjected to ultrasonic
vibration. The coated diamond powder which is subjected to
electroless plating in this manner is cleaned, the surface of the
diamond particles is partially graphitized by heat treatment in a
vacuum at approximately 1,000.degree. C. for 60 minutes, and then
the powder is collected, whereby the coated powder Samples A and B
have the following contents and compositions of the sintering
assist agent:
[0078] Sample A--Total content of the sintering assist agent is
approximately 6 percent by volume; sintering assist agent
composition comprised approximately 92.9 percent by weight Co, 0.05
percent by weight Pd, 3.95 percent by weight Fe, 3 percent by
weight P, and 0.1 percent by weight Sn.
[0079] Sample B--Total content of the sintering assist agent is
approximately 13 percent by volume; sintering assistant agent
composition comprised approximately 92.9 percent by weight Co, 0.05
percent by weight Pd, 3.95 percent by weight Fe, 3 percent by
weight P, and 0.1 percent by weight Sn.
[0080] It is to be understood that the following two examples are
provided for purposes of reference and that other samples of second
embodiment PCD bodies comprising different types and/or amounts of
the sintering assists agents, different sizes of diamond powder,
and using different techniques for coating or applying the
sintering assist agents are within the scope of this invention.
Other coating techniques may include arc ion plating methods, ball
milling by including the powder component and using a container and
balls formed from Teflon, and ball milling using mixing balls
and/or the container formed from a desired coating material, e.g.,
cemented tungsten carbide (WC--Co).
[0081] The Sample A and B coated diamond powders are each sealed in
a container or vessel formed of tantalum and exposed to a HPHT
condition of approximately 50 Kbar and a temperature of
approximately 1,400.degree. C. for 10 minutes by using a belt-type
high pressure apparatus. The sintered PCD bodies formed from
Samples A and B demonstrated a high degree of wear resistance and
strength even though the amount of sintering assistant agent was
relatively small, thus making such PCD bodies well suited for use
as cutting and/or wear elements in such applications as bits used
to drill earthen formations.
[0082] Third example embodiment PCD bodies of this invention
comprise approximately 0.1 to 30 percent by volume of a compound
containing at least one metal selected from the group consisting of
Fe, Co, Ni, Mn, Ti and O, and the balance of diamond. In one
example embodiment, the compound containing at least one metal
selected from the group consisting of Fe, Co, Ni, Mn, Ti, and O is
a titanate of a metal selected from the group consisting of Fe, Co,
Ni, and Mn. In another example embodiment, the compound containing
at least one metal selected from the group consisting of Fe, Co,
Ni, Mn, Ti, and O is a composite oxide or solid solution consisting
of an oxide of a metal selected from the group consisting of Fe,
Co, Ni, Mn, and titanium oxide (TiO.sub.2).
[0083] Diamond powder useful for forming third example embodiment
PCD bodies of this invention can be the same as that disclosed
above for the first and second example embodiment PCD bodies of
this invention. In place of, or in addition to, using diamond,
non-diamond carbons such as graphite, glassy carbons, pyrolytic
graphites, and the like can be used as the raw material.
[0084] Example titanates can include FeTiO.sub.3,
FeTi.sub.2O.sub.5, CoTiO.sub.3, MnTiO.sub.3, NiTiO, and the like.
Such materials are capable of exhibiting a strong catalytic
function for diamond and when used as a sintering agent, promote
formation of a strongly-bonded matrix of diamond grains. In a
preferred embodiment, such sintering agent has a grain diameter of
from about 0.01 to 10 micrometers. Such sintering aids are stable
at a high temperature, e.g. about 1,300.degree. C., providing a PCD
body having improved thermal resistance when compared to
conventional PCD materials.
[0085] Such third embodiment PCD bodies can be made by preparing a
mixture of diamond powder or non-diamond carbon powder with a
titanate of Fe, Co or a mixture of iron oxide or cobalt oxide and
titanium oxide under HPHT conditions that are in the
thermodynamically stable region of diamond. The diamond and
sintering agent can be mechanically mixed by dry or wet process and
the resulting powder can be compressed and molded or charged in a
capsule of Mo or the like, followed by sintering at a HPHT
conditions.
[0086] Other third example embodiment PCD bodies of this invention
comprise approximately 0.1 to 30 percent by volume of a compound
containing Ti, at least one metal selected from the group
consisting of alkali metals and alkaline earth metals, and oxygen,
and the balance diamond. In one such embodiment, the compound
containing titanium, at least one metal selected from the group
consisting of alkali metals and alkaline earth metals, and oxygen
is a titanate of a metal selected from the group consisting of
alkali metals and alkaline earth metals. In another such
embodiment, the compound containing titanium, at least one metal
selected from the group consisting of alkali metals and alkaline
earth metals, and oxygen is a composite oxide or solid solution
consisting of an oxide of a metal selected from the group
consisting of alkali metals and alkaline earth metals and titanium
oxide.
[0087] Example titanates of an alkali metal or alkaline earth metal
include LiTiO.sub.3, MgTiO.sub.3, CaTiO.sub.3, SrTiO.sub.3, or the
like. Sintering agents comprising titanates of alkali metals or
alkaline earth metals, or composite oxides or solid solutions of
alkali metal oxides or alkaline earth metal oxides with titanium
oxides are desired as these materials are stable at a high
temperature, e.g. about 1,500.degree. C., contributing improved
thermal resistance to the PCD body when compared to conventional
PCD materials. PCD bodies formed from such sintering aids are made
in the same manner as described above for the third example
embodiment PCD body.
[0088] Still other third example embodiment PCD bodies of this
invention comprise approximately 0.1 to 30 percent by volume of a
compound containing a rare earth element, titanium and oxygen, and
the balance of diamond. In an example embodiment, the compound
containing a rare earth element, titanium and oxygen is a titanate
of a rare earth element. In another embodiment, the compound
containing a rare earth element, titanium and oxygen is a composite
oxide or solid solution consisting of an oxide of a rare earth
element and titanium oxide.
[0089] Example titanates of a rare earth element include
M.sub.2TiO.sub.5 or M.sub.2Ti.sub.2O.sub.7, wherein M is a rare
earth element. The rare earth element can include scandium (Sc),
yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr),
neodymium (Nd), prometium (Pm), samarium (Sm), europium (Eu),
gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho),
erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).
Example oxides of a rare earth element include M.sub.2O.sub.3 or
MO.sub.2, wherein M is a rare earth element. Such sintering aids
are stable at a high temperature, e.g. about 1,300.degree. C.,
thereby providing improved thermal resistance to the sintered PCD
body when compared to conventional PCD.
[0090] Still other third example embodiment PCD bodies of this
invention comprise approximately 0.1 to 30 percent by volume of a
compound containing an alkaline earth metal, silicon and oxygen,
and the balance of diamond. In an example embodiment, the compound
containing an alkaline earth metal, silicon and oxygen is a
silicate of an alkaline earth metal. In another example embodiment,
the compound containing an alkaline earth metal, silicon and oxygen
is a composite oxide or solid solution consisting of an oxide of an
alkaline earth metal and silicon oxide.
[0091] Example silicates of an alkaline earth metal include
MgSiO.sub.3, Mg.sub.2SiO.sub.4, Mg.sub.2Si.sub.3O.sub.4,
CaSiO.sub.3, Ca.sub.2SiO.sub.4, BaSi.sub.2O.sub.5,
Ba.sub.2Si.sub.3O.sub.8, or the like. Such sintering aids are
stable at a high temperature, e.g. about 1,300.degree. C., thereby
providing improved thermal resistance to the sintered PCD body when
compared to conventional PCD.
[0092] Still other third example embodiment PCD bodies of this
invention comprise approximately 0.1 to 30 percent by volume of a
compound containing a rare earth element, silicon and oxygen, and
the balance of diamond. In an example embodiment, the compound
containing a rare earth element, silicon and oxygen is a silicate
of a rare earth element. In another example embodiment, the
compound containing a rare earth element, silicon and oxygen is a
composite oxide or solid solution consisting of an oxide of a rare
earth element and silicon oxide.
[0093] Example silicates of a rare earth element include, for
example, M.sub.2SiO.sub.5 or M.sub.2Si.sub.2O.sub.7, wherein M is a
rare earth element. The rare earth element can include scandium
(Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr),
neodymium (Nd), prometium (Pm), samarium (Sm), europium (Eu),
gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho),
erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu).
Example oxides of a rare earth element include M.sub.2O.sub.3 or
MO.sub.2, wherein M is a rare earth element. Such sintering aids
are stable at a high temperature, e.g. about 1,400.degree. C.,
thereby providing improved thermal resistance to the sintered PCD
body when compared to conventional PCD.
[0094] Still other third example embodiment PCD bodies of this
invention comprise approximately 0.1 to 30 percent by volume of a
compound containing silicon, titanium and oxygen, and the balance
of diamond. In example embodiment, the compound containing silicon,
titanium and oxygen is a composite oxide or solid solution
consisting of silicon oxide (SiO.sub.2) and titanium oxide
(TiO.sub.2). In such example embodiment, the mixture of silicone
oxide and titanium oxide comprises 0.1 to 50 percent by volume
titanium oxide.
[0095] In an example embodiment, the silicon oxide used in the
mixture of silicon oxide and titanium oxide is silicic acid, or
silicon oxide hydrate. Suitable silicic acids include
H.sub.4SiO.sub.4, H.sub.2SiO.sub.3, H.sub.2Si.sub.2O.sub.2, and the
like, and suitable silicon oxide hydrates include
SiO.sub.2--H.sub.2O. Such sintering aids are stable at a high
temperature, e.g. about 1,500.degree. C., thereby providing
improved thermal resistance to the sintered PCD body when compared
to conventional PCD.
[0096] PCD bodies, constructed in accordance with principles of
this invention have a diamond volume content greater than about 94
percent, and preferably greater than about 96 percent. Such PCD
bodies can be used to form cutting and/or wear elements for use
with desired cutting and/or devices to address certain cutting
and/or wear applications. In an example embodiment, such PCD bodies
and can be further combined with a substrate to form a PCD
construction useful in desired cutting and/or wear applications.
The ability to combine such PCD bodies with a substrate is desired
for certain cutting and/or wear applications to facilitate
attachment of the so-formed PCD construction to the desired cutting
or wear device. For example, when the PCD body is designed for use
as a cutting and/or wear element for attachment with a bit, i.e., a
drill bit used for drilling subterranean earthen formations, it is
desired that such cutting and/or wear element include a substrate
that can be attached by conventional technique, such as brazing or
welding or the like, to the bit body.
[0097] Substrates useful for forming PCD compacts having PCD bodies
of this invention include those selected from the group of
materials including ceramic materials, metallic materials, and
cermet materials. Suitable substrates can include those
conventionally used to form PCD compacts, such as those formed from
metallic and cermet materials such as WC--Co. When the substrate
material is one that includes a metal solvent catalyst, i.e., a
Group VIII element of the Periodic table that is capable of
infiltrating into the PCD body during HPHT processing and
catalyzing the formation of diamond-to-diamond bonds during
sintering conditions, then it is desired that such substrate be
attached to the PCD body in a manner that avoids such
infiltration.
[0098] Accordingly, substrate materials including a solvent metal
catalyst can be attached to the PCD body by welding, brazing, or
other process that avoids infiltration of the solvent metal
catalyst into the PCD body. Alternatively, such substrates can be
attached to the PCD body during the HPHT process used to form the
sintered PCD body, or during a subsequent HPHT process, by using an
intermediate layer interposed between the PCD body and the
substrate. In such case, the intermediate layer is one formed from
a material that is substantially free of a Group VIII element and
that both facilitates attachment of the substrate indirectly to the
PCD body, and that acts as a barrier to prevent unwanted
infiltration of the solvent metal catalyst from the substrate into
the PCD body.
[0099] Example intermediate layer materials include those that are
carbide formers, e.g., that react with the carbon in the diamond
body to form a carbide. Suitable carbide forming materials include
refractory metals such as those selected from Groups IV through VII
of the Periodic table. Example refractory materials include Ti, Ta,
W, Mo, Zr and the like.
[0100] Other materials useful for forming the intermediate layer
include ceramic materials such as TiC, Al.sub.2O.sub.3,
Si.sub.3N.sub.4, SiC, SiAlON, TiN, ZrO.sub.2, WC, TiB.sub.2, AlN
and SiO.sub.2, also Ti.sub.XAlM.sub.Y (where x is between 2-3, M is
carbon or nitrogen or a combination of these, and y is between
1-2). Like the carbide forming materials, the ceramic material that
is selected is one that is capable of forming a bond between the
PCD body and substrate by HPHT process without itself infiltrating
or causing unwanted infiltration of materials present in the
substrate into the PCD body during the HPHT process.
[0101] Still other materials useful for forming the intermediate
layer can include non-carbide forming materials such as
non-refractory metals and high-strength braze alloys. A desired
characteristic of such non-refractory metals and high-strength
braze alloys is that they be capable of infiltrating into one or
both of the PCD body and substrate during HPHT conditions, and are
non-catalytic with respect to the diamond in the PCD body. Suitable
non-refractory metals and high-strength braze alloys include
copper, Ni--Cr alloys, and brazes containing high percentages of
elements such as palladium and similar high strength materials, and
Cn-based active brazes. A particularly preferred non-refractory
metal useful as an intermediate material is copper due to its
relatively low melting temperature, below that of cobalt, and its
ability to form a bond of sufficient strength with the PCD body.
The ability to provide an intermediate material having a relatively
low melting temperature is desired for the purpose of avoiding
potential infiltration of any solvent metal catalyst from the
substrate into the PCD body.
[0102] Such intermediate material can be provided in the form of a
preformed layer, e.g., in the form of a foil or the like.
Alternatively, the intermediate material can be provided in the
form of a green-state part, or can be provided in the form of a
coating that is applied to one or both of the interface surfaces of
the PCD body and the substrate. It is to be understood that one or
more intermediate layers can be used to achieve the desired bonding
and/or barrier and or mechanical properties between the PCD body
and the substrate.
[0103] It is to be understood that substrates comprising a catalyst
material can be attached to the PCD body using the intermediate
layer at pressure and/or temperature conditions that are below the
HPHT conditions used to sinter the PCD body, e.g., they can be
attached after the PCD body has been sintered by using less extreme
pressure and/or temperature conditions.
[0104] Alternatively, substrates useful for forming compacts
comprising PCD bodies of this invention can be formed from
materials that do not include a solvent metal catalyst material,
such as the Group VIII elements conventionally used to form PCD
like Co. Examples of such materials include carbides, nitrides,
borides, and carbonitrides or the like, that include a material,
e.g., a carbide former, that is capable of forming an attachment
bond with the PCD body without acting as a catalyst material. Such
attachment can be achieved during HPHT sintering of the PCD body,
or can be achieved by subjecting the already-formed PCD body and
substrate to a temperature and/or pressure condition less extreme
than the one used to form the sintered PCD body. An example of such
substrate material is tungsten carbide molybdenum (WC--Mo).
[0105] Accordingly, PCD bodies of this invention can be used to
form PCD construction through the use of: (1) a substrate material
comprising a solvent catalyst material by welding, brazing, or
other technique that does not result in infiltration of the
catalyst material into the PCD body, (2) a substrate material
comprising a catalyst material and that is attached to the PCD body
via an intermediate layer of material that both facilitates
attachment between the PCD body and substrate while also acting as
a barrier to prevent the catalyst material in the substrate from
infiltrating into the PCD body; and (3) a substrate material that
does not include a solvent catalyst material, but that includes a
material capable of forming an attachment with the PCD body.
[0106] FIG. 1A illustrates an example PCD construction 16 formed in
accordance with this invention. The PCD construction 16 generally
comprises a PCD body 18, formed from the materials and in the
manner described above, that is attached to a desired substrate 20.
Although the PCD construction 16 is illustrated as being generally
cylindrical in shape and having a disk-shaped flat or planar
surface 22, it is understood that this is but one preferred
embodiment and that the PCD construction can be configured other
than as specifically disclosed or illustrated. It is further to be
understood that the construction or compact 16 may be configured
having working or cutting surfaces disposed along the disk-shaped
surface 22 and/or along side surfaces 24 and/or along a beveled
surface interposed therebetween of the PCD body, depending on the
particular cutting or wear application. Alternatively, the PCD
compact may be configured having an altogether different shape but
generally comprising a substrate and a PCD body attached to the
substrate, wherein the PCD body is provided with working or cutting
surfaces oriented as necessary to perform working or cutting
service when the compact is mounted to a desired drilling or
cutting device, e.g., a drill bit.
[0107] FIGS. 1B to 1D illustrate alternative embodiments of PCD
constructions having a substrate and/or PCD body configured
differently than that illustrated in FIG. 1A. For example, FIG. 1B
illustrates a PCD compact 16 configured in the shape of a preflat
or gage trimmer including a cut-off portion 19 of the PCD body 18
and the substrate 20. The preflat includes working or cutting
surface positioned along a disk-shaped surface 22 and a side
surface 24 working surface. Alternative preflat or gage trimmer PCD
compact configurations intended to be within the scope of this
invention include those described in U.S. Pat. No. 6,604,588, which
is incorporated herein by reference.
[0108] FIG. 1C illustrates another embodiment of a PCD compact 16
of this invention configured having the PCD body 18 disposed onto
an angled underlying surface of the substrate 20 and having a
disk-shaped surface 22 that is the working surface and that is
positioned at an angle relative to an axis of the compact. FIG. 1D
illustrates another embodiment of a PCD compact 16 of this
invention configured having the substrate 20 and the PCD body 18
disposed onto a surface of the substrate. In this particular
embodiment, the PCD body has a domed or convex surface 22 serving
as the working surface 22.
[0109] FIG. 1E illustrates a still other embodiment of a PCD
construction 16 that is somewhat similar to that illustrated in
FIG. 1A in that it includes a PCD body 18 disposed on the substrate
20 and having a disk-shaped surface 22 as a working surface. Unlike
the embodiment of FIG. 1A, however, this PCD compact includes an
interface 21 between the PCD body and the substrate that is not
uniformly planar. In this particular example, the interface 21 is
canted or otherwise non-axially symmetric. It is to be understood
that PCD compacts of this invention can be configured having PCD
body-substrate interfaces that are uniformly planer or that are not
uniformly planer in a manner that is symmetric or nonsymmetric
relative to an axis running through the compact. Examples of other
configurations of PCD compacts having nonplanar PCD body-substrate
interfaces include those described in U.S. Pat. No. 6,550,556,
which is incorporated herein by reference.
[0110] A feature of PCD bodies and/or constructions or compacts
formed therefrom of this invention is that they display an improved
degree of thermal stability and/or thermal resistance when compared
to conventional PCD, e.g., PCD made by only using diamond powder
and a solvent metal catalyst, while at the same time providing a
desired degree of strength and toughness unique to conventional
PCD.
[0111] A still further feature is the ability to achieve such
improved thermal stability and/or resistance while at the same time
being able to provide a compact construction comprising a
substrate. This facilitates attaching the compact to different
types of well known cutting and wear devices such as drill bits and
the like by conventional attachment techniques, such as by brazing,
welding, or the like.
[0112] PCD bodies and constructions of this invention can be used
in a number of different applications, such as tools for mining,
cutting, machining and construction applications, where the
combined properties of thermal stability, wear and abrasion
resistance, and strength and toughness are highly desired. PCD
bodies and compacts of this invention are particularly well suited
for forming working, wear and/or cutting components in machine
tools and drill and mining bits such as roller cone rock bits,
percussion or hammer bits, diamond bits, and shear cutters.
[0113] FIG. 2 illustrates an embodiment of a PCD construction of
this invention provided in the form of an insert 62 used in a wear
or cutting application in a roller cone drill bit or percussion or
hammer drill bit. For example, such PCD inserts 62 are constructed
having a substrate portion 64, formed from one or more of the
substrate materials disclosed above, that is attached to a PCD body
66 formed from the materials and in the manner described above. In
this particular embodiment, the insert PCD body comprises a domed
working surface 68. The insert 62 can be pressed or machined into
the desired shape or configuration. It is to be understood that PCD
bodies and/or compacts can be used with inserts having geometries
other than that specifically described above and illustrated in
FIG. 2.
[0114] FIG. 3 illustrates a rotary or roller cone drill bit in the
form of a rock bit 70 comprising a number of the wear or cutting
PCD inserts 72 disclosed above and illustrated in FIG. 2. The rock
bit 70 comprises a body 74 having three legs 76 extending
therefrom, and a roller cutter cone 78 mounted on a lower end of
each leg. The inserts 72 are the same as those described above
comprising the PCD bodies and/or compacts described above, and are
provided in the surfaces of each cutter cone 78 for bearing on a
rock formation being drilled.
[0115] FIG. 4 illustrates the PCD insert described above and
illustrated in FIG. 2 as used with a percussion or hammer bit 80.
The hammer bit generally 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 86 is provided in the surface of a head 88
of the body 82 for bearing on the subterranean formation being
drilled.
[0116] FIG. 5 illustrates a PCD compact constructed as described
above embodied in the form of a shear cutter 90 used, for example,
with a drag bit for drilling subterranean formations. The PCD shear
cutter comprises a PCD body 92 attached to a cutter substrate 94 as
described above. The PCD body 92 includes a working or cutting
surface 96 that can include top, side, and/or beveled surfaces. It
is to be understood that PCD compacts can be configured as shear
cutters having geometries other than that specifically described
above and illustrated in FIG. 5.
[0117] FIG. 6 illustrates a drag bit 98 comprising a plurality of
the PCD shear cutters 100 described above and illustrated in FIG.
5. 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. Because the PCD shear cutters
of this invention include a metallic substrate, they are attached
to the blades by conventional method, such as by brazing, welding
or the like.
[0118] Other modifications and variations of PCD bodies and
constructions comprising the same as practiced according to the
principles of this invention will be apparent to those skilled in
the art. It is, therefore, to be understood that within the scope
of the appended claims, this invention may be practiced otherwise
than as specifically described.
* * * * *