U.S. patent application number 14/368665 was filed with the patent office on 2014-12-04 for method of making polycrystalline diamond material.
The applicant listed for this patent is Element Six Abrasives, S.A.. Invention is credited to Kaveshini Naidoo.
Application Number | 20140353047 14/368665 |
Document ID | / |
Family ID | 45573082 |
Filed Date | 2014-12-04 |
United States Patent
Application |
20140353047 |
Kind Code |
A1 |
Naidoo; Kaveshini |
December 4, 2014 |
METHOD OF MAKING POLYCRYSTALLINE DIAMOND MATERIAL
Abstract
A method of making polycrystalline diamond material includes
providing a fraction of diamond particles or grains and a sintering
additive, the sintering additive comprising a carbon source of
nano-sized particles or grains, forming the diamond particles and
sintering additive into an aggregated mass, consolidating the
aggregated mass and a binder material to form a green body, and
subjecting the green body to conditions of pressure and temperature
at which diamond is more thermodynamically stable than graphite and
for a time sufficient to consume the sintering additive, sintering
it and forming polycrystalline diamond material that is
thermodynamically and crystallographically stable and is
substantially devoid of any nano-structures.
Inventors: |
Naidoo; Kaveshini; (Springs,
ZA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Element Six Abrasives, S.A. |
Luxembourg |
|
LU |
|
|
Family ID: |
45573082 |
Appl. No.: |
14/368665 |
Filed: |
December 13, 2012 |
PCT Filed: |
December 13, 2012 |
PCT NO: |
PCT/EP2012/075374 |
371 Date: |
June 25, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61580850 |
Dec 28, 2011 |
|
|
|
Current U.S.
Class: |
175/432 ; 51/307;
51/309 |
Current CPC
Class: |
C04B 2235/422 20130101;
C04B 2235/5445 20130101; B82Y 30/00 20130101; C04B 35/52 20130101;
C04B 2235/427 20130101; B01J 2203/0625 20130101; C22C 26/00
20130101; B01J 2203/0655 20130101; B01J 2203/0615 20130101; C04B
2235/5454 20130101; C04B 35/645 20130101; C04B 2235/424 20130101;
C04B 2235/786 20130101; C04B 2235/5472 20130101; C04B 2235/6567
20130101; C04B 2235/5436 20130101; B01J 2203/062 20130101; B01J
2203/0685 20130101; B24D 3/06 20130101; C04B 2235/785 20130101;
B24D 18/0009 20130101; B01J 3/062 20130101; E21B 10/567 20130101;
E21B 10/5735 20130101; C04B 2235/425 20130101; C04B 35/6261
20130101; B01J 2203/061 20130101 |
Class at
Publication: |
175/432 ; 51/307;
51/309 |
International
Class: |
B24D 3/06 20060101
B24D003/06; E21B 10/573 20060101 E21B010/573; B24D 18/00 20060101
B24D018/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 28, 2011 |
GB |
1122365.8 |
Claims
1. A method of making polycrystalline diamond material, the method
including providing a fraction of diamond particles or grains and a
sintering additive, the sintering additive comprising a carbon
source of nano-sized particles or grains, forming the diamond
particles and sintering additive into an aggregated mass,
consolidating the aggregated mass and a binder material to form a
green body, and subjecting the green body to conditions of pressure
and temperature at which diamond is more thermodynamically stable
than graphite and for a time sufficient to consume the sintering
additive, sintering it and forming polycrystalline diamond material
that is thermodynamically and crystallographically stable and is
substantially devoid of any nano-structures.
2. A method according to claim 1, wherein the binder material
comprises a catalyst material for diamond.
3. A method according to claim 1, wherein the sintering additive is
nanodiamond.
4. A method according to claim 3, wherein nanodiamond is UDD
(ultra-dispersed nanodiamond), PDD (polycrystalline detonated
diamond powder), or a crushed source of nanodiamond.
5. A method according to claim 1, wherein the sintering additive is
a nano-sized carbon source selected from the group comprising
graphite, soot, coke, carbon anions and fullerenes.
6. A method according to claim 1, wherein the sintering additive is
provided in an amount of from about 0.01 to about 5 wt % of the
aggregated mass, or from about 0.5 to about 1 wt % of the
aggregated mass.
7. A method according to claim 1, wherein the method includes
subjecting the green body to a pressure of about 6.0 GPa or more
and a temperature of about 1350.degree. C. or more.
8. A method according to claim 1, wherein the green body is
sintered for a period of 2 minutes to 60 minutes.
9. A method according to claim 1, wherein the diamond particles or
grains, prior to contact with the sintering additive or binder
material, have an average particle or grain size ranging from about
0.1 microns to about 50 microns.
10. A method according to claim 1, wherein the step of subjecting
the green body to a pressure treatment comprises subjecting the
green body to a pressure of greater than 6.0 GPa, or at least about
6.2 GPa, or at least about 6.5 GPa, or at about 6.8 GPa or more, or
at least about 8 GPa, or at least about 7.7 GPa, or at least about
7.5 GPa, or at least about 7.2 GPa, or at least about 7.0 GPa.
11. A method according to claim 1, wherein the aggregated mass and
the binder material are mixed in powder form with one or more
binding aids.
12. A method according to claim 1, wherein the step of
consolidating the aggregated mass and binder material comprises
coating the diamond particles with the binder material using any
one or more of a sol-gel technique, electrolytic or electroless
deposition, PVD, or CVD and consolidating the coated diamond
particles with the sintering additive.
13. A method according to claim 1, wherein the binder material is
any one or more of cobalt-tungsten carbide, Ni, Pd, Mn or Fe.
14. A body of polycrystalline diamond (PCD) material formed
according to the method of claim 1.
15. A tool or tool component for cutting, milling, grinding,
drilling, earth boring, rock drilling, or the cutting and machining
of metal, comprising an a body of PCD material formed according to
the method of claim 1.
16. A drill bit for boring into the earth for use in the oil and
gas drilling industry comprising the tool of claim 15.
Description
FIELD
[0001] This disclosure relates to a method of making a
polycrystalline diamond (PCD) material, and to a PCD material so
made.
BACKGROUND
[0002] Cutter inserts for machine and other tools may comprise a
layer of polycrystalline diamond (PCD) bonded to a cemented carbide
substrate. PCD is an example of a superhard material, also called
superabrasive material, which has a hardness value substantially
greater than that of cemented tungsten carbide.
[0003] Components comprising PCD are used in a wide variety of
tools for cutting, machining, drilling or degrading hard or
abrasive materials such as rock, metal, ceramics, composites and
wood-containing materials. PCD comprises a mass of substantially
inter-grown diamond grains forming a skeletal mass, which defines
interstices between the diamond grains. PCD material comprises at
least about 80 volume % of diamond and may be made by subjecting an
aggregated mass of diamond grains to an ultra-high pressure of
greater than about 5 GPa, typically about 5.5 GPa, and temperature
of at least about 1200.degree. C., typically about 1440.degree. C.,
in the presence of a sintering aid, also referred to as a catalyst
material for diamond. Catalyst material for diamond is understood
to be material that is capable of promoting direct inter-growth of
diamond grains at a pressure and temperature condition at which
diamond is thermodynamically more stable than graphite. Some
catalyst materials for diamond may promote the conversion of
diamond to graphite at ambient pressure, particularly at elevated
temperatures. Examples of catalyst materials for diamond are
cobalt, iron, nickel and certain alloys including any of these. PCD
may be formed on a cobalt-cemented tungsten carbide substrate,
which may provide a source of cobalt catalyst material for the PCD.
The interstices within PCD material may at least partly be filled
with the catalyst material.
[0004] WO 2010/140108 discloses a polycrystalline diamond (PCD)
material comprising at least 88 volume percent and at most 99
volume percent diamond grains, and having a mean diamond grain
contiguity of greater than about 60 percent. The PCD is
manufactured at ultra high pressures of 6 GPa or higher to increase
diamond contiguity resulting in improved wear performance.
[0005] U.S. Pat. No. 7,516,804 and US patent application
publication number 2009/0158670 disclose a superabrasive element
that includes a mass of polycrystalline diamond including
ultra-dispersed diamond grain structures present in an amount
greater than zero weight percent and less than about 75 weight
percent of the mass of polycrystalline diamond.
SUMMARY
[0006] Viewed from a first aspect there is provided a method of
making polycrystalline diamond material, the method comprising
providing a fraction of diamond particles or grains and a sintering
additive, the sintering additive comprising a carbon source of
nano-sized particles or grains, forming the diamond particles or
grains and sintering additive into an aggregated mass,
consolidating the aggregated mass and a binder material, typically
a catalyst material for diamond, to form a green body, and
subjecting the green body to conditions of pressure and temperature
at which diamond is more thermodynamically stable than graphite and
for a time sufficient to consume the sintering additive, sintering
and forming polycrystalline diamond material that is
thermodynamically and crystallographically stable and is
substantially devoid of any nano-structures.
[0007] In some embodiments, the sintering additive is nanodiamond.
The nanodiamond may be UDD (ultra-dispersed nanodiamond), PDD
(polycrystalline detonated diamond powder) or a crushed source of
nanodiamond.
[0008] In some embodiments, the sintering additive is a nano-sized
carbon source selected from the group comprising graphite, soot,
coke, carbon anions and fullerenes.
[0009] In some embodiments, the sintering additive is provided in
an amount of from about 0.01 to about 5 wt % of the aggregated
mass, or from about 0.5 to about 1 wt % of the aggregated mass.
[0010] In some embodiments, the method includes subjecting the
green body to a pressure treatment at a pressure of greater than
6.0 GPa, at least about 6.2 GPa, or at least about 6.5 GPa, or even
at about 6.8 GPa or more, in the presence of a metallic catalyst
material for diamond at a temperature sufficiently high for the
catalyst material to melt, and sintering the diamond grains to form
PCD material. In some embodiments the pressure is at least about 8
GPa, at least about 7.7 GPa, at least about 7.5 GPa, at least about
7.2 GPa or at least about 7.0 GPa.
[0011] In some embodiments of the method, the temperature may be in
the range from about 1,350 degrees centigrade to about 2,300
degrees centigrade, in the range from about 1,400 degrees
centigrade to about 2,000 degrees centigrade, in the range from
about 1,450 degrees centigrade to about 1,700 degrees centigrade,
or in the range from about 1,450 degrees centigrade to about 1,650
degrees centigrade.
[0012] In some embodiments of the method, the green body may be
sintered for a period in the range from about 2 minutes to about 60
minutes, in the range from about 3 minutes to about 30 minutes, or
in the range from about 5 minutes to about 15 minutes.
[0013] In some embodiments, the aggregated mass and the binder
material are mixed in powder form with appropriate binding
aids.
[0014] In some embodiments the binder material is infiltrated into
the aggregated mass.
[0015] In some embodiments, the diamond particles can be coated
with the binder material using techniques such as sol-gel,
electrolytic or electroless deposition, PVD, or CVD. The coatings
may be continuous or dispersed.
[0016] In some embodiments, infiltration using shims, powders,
discs or from a substrate containing the binder material may be
used.
[0017] In some embodiments, the binder material is cobalt-tungsten
carbide.
[0018] In some embodiments, the binder material is Ni, Pd, Mn or
Fe, or combinations of these metal catalysts.
[0019] In some embodiments, the diamond particles or grains prior
to contact with the sintering additive or binder material have an
average particle or grain size of from about 0.1 microns to about
50 microns, or from about 0.2 microns to about 10 microns, or from
about 0.9 microns to about 2 microns.
[0020] Viewed from a further aspect there is provided a body of
polycrystalline material body such as a body of polycrystalline
diamond material formed according to the above method.
[0021] An embodiment of the invention provides a tool or tool
component for cutting, boring into or degrading a body, comprising
an embodiment of a PCD material formed according to the above
method. In some embodiments, the tool or tool component may be for
cutting, milling, grinding, drilling, earth boring, rock drilling
or other abrasive applications, such as the cutting and machining
of metal. In one embodiment, the tool component may be an insert
for a drill bit, such as a rotary shear-cutting bit, for boring
into the earth, for use in the oil and gas drilling industry. In
one embodiment, the tool may be a rotary drill bit for boring into
the earth.
DETAILED DESCRIPTION OF EMBODIMENTS
[0022] As used herein, "polycrystalline diamond" (PCD) material
comprises a mass of diamond grains, a substantial portion of which
are directly inter-bonded with each other and in which the content
of diamond is at least about 80 volume percent of the material. In
one embodiment of PCD material, interstices between the diamond
grains may at least partly be filled with a binder material.
[0023] As used herein, "catalyst material for diamond" is a
material that catalyses intergrowth of polycrystalline diamond
particles or grains under conditions of temperature and pressure at
which diamond is more thermodynamically stable than graphite.
[0024] As used herein, "interstices" or "interstitial regions" are
regions between the diamond grains of PCD material.
[0025] As used herein, a "green body" is an article that is
intended to be sintered or which has been partially sintered, but
which has not yet been fully sintered to form an end product. It
may generally be self-supporting and may have the general form of
the intended finished article.
[0026] As used herein, a "superhard wear element" is an element
comprising a superhard material and is for use in a wear
application, such as degrading, boring into, cutting or machining a
workpiece or body comprising a hard or abrasive material.
[0027] As used herein, the words "average" and "mean" have the same
meaning and are interchangeable.
[0028] In the field of quantitative stereography, particularly as
applied to cemented carbide material, "contiguity" is understood to
be a quantitative measure of inter-phase contact. It is defined as
the internal surface area of a phase shared with grains of the same
phase in a substantially two-phase microstructure (Underwood, E. E,
"Quantitative Stereography", Addison-Wesley, Reading Mass. 1970;
German, R. M. "The Contiguity of Liquid Phase Sintered
Microstructures", Metallurgical Transactions A, Vol. 16A, July
1985, pp. 1247-1252). As used herein, "diamond grain contiguity" is
a measure of diamond-to-diamond contact or bonding, or a
combination of contact and bonding within PCD material.
[0029] As used herein, "nanodiamond" and "nano-sized carbon source"
are particles or grains that have their major diametric dimension
smaller than 0.1 microns (100 nm).
[0030] As used herein, UDD is "ultra-dispersed nanodiamond",
consisting of diamond particles of 2-50 nm, and produced by
detonation of carbon-containing explosives. UDD particles typically
consist of a polycrystalline diamond core surrounded by a
metastable (non-diamond) carbon shell.
[0031] As used herein, PDD is "polycrystalline detonated diamond
powder", also known as "poly-dispersed diamond" comprising
particles that may be as small as 0-50 nm, typically consisting of
polycrystalline nanodiamond grains of about 20-25 nm that are
produced by shock-wave compression of carbon materials mixed with
catalyst. PDD typically contains non-carbon impurities from the
catalyst, for example copper.
[0032] As used herein, "crushed source nanodiamond" is synthetic
(synthesised at HPHT conditions) or natural micron-sized diamond
that has been ground, purified and graded to yield nanosized
fractions of monocrystalline diamond particles.
[0033] An embodiment of PCD material has a diamond content of from
80 to 90 volume percent and a binder content of at least 10 volume
percent, and comprises diamond grains having a mean diamond grain
contiguity of greater than 60 percent and a standard deviation of
less than 2 percent. The diamond grains form a skeletal mass
defining interstices or interstitial regions between them. The
combined lengths of lines passing through all points lying on all
bond or contact interfaces between diamond grains within a section
of the PCD material are summed to determine the diamond perimeter,
and the combined lengths of lines passing through all points lying
on all interfaces between diamond and interstitial regions within a
section of the PCD material are summed to determine the binder
perimeter.
[0034] A multimodal size distribution of a mass of grains is
understood to mean that the grains have a size distribution with
more than one peak, each peak corresponding to a respective "mode".
Multimodal polycrystalline bodies are typically made by providing
more than one source of a plurality of grains, each source
comprising grains having a substantially different average size,
and blending together the grains. Measurement of the size
distribution of the blended grains may reveal distinct peaks
corresponding to distinct modes. When the grains are sintered
together to form the polycrystalline body, their size distribution
is further altered as the grains are compacted against one another
and fractured, resulting in the overall decrease in the sizes of
the grains. Nevertheless, the multimodality of the grains may still
be clearly evident from image analysis of the sintered article.
[0035] Unless otherwise stated herein, dimensions of size,
distance, and perimeter and so forth relating to grains and
interstices within PCD material, as well as the grain contiguity,
refer to the dimensions as measured on a surface of, or a section
through a body comprising PCD material and no stereographic
correction has been applied. For example, the size distributions of
the diamond grains of some embodiments were measured by means of
image analysis carried out on a polished surface, and a Saltykov
correction was not applied.
[0036] Catalyst material may be introduced to an aggregated mass of
diamond grains for sintering in any of the ways known in the art.
The PCD may be backed by a substrate, and the binder may be
infiltrated from the substrate during HPHT synthesis, or be
infiltrated from a shim, foil or layer of alternative binder
material at the interface between the PCD layer and the substrate.
The PCD may be unbacked, in which case the binder may be introduced
via known methods in the art such as mixing, milling or coating of
the diamond powder with the binder material, or may be infiltrated
from a substrate, foil, layer or shim which may be removed after
sintering. The PCD may be leached or unleached. The binder may be
Co--WC or other binder materials known in the art such as for
example Ni, Pd, Mn or Fe or combinations of these. The interface
between the PCD table and the substrate may be planar or
non-planar/shaped. The PCD table may have a chamfered edge.
[0037] In some embodiments, the aggregated mass of diamond grains
and sintering additive, together with the catalyst or binder
material, may be formed into a green body, which may be placed onto
a cemented carbide substrate. The cemented carbide substrate may
contain a source of catalyst material for diamond, such as cobalt.
The assembly of aggregated mass and substrate may be encapsulated
in a capsule suitable for an ultra-high pressure furnace apparatus
capable of subjecting the capsule to a pressure of greater than 6
GPa. Various kinds of ultra-high pressure apparatus are known and
can be used, including belt, toroidal, cubic and tetragonal
multi-anvil systems. The temperature of the capsule should be high
enough for the source of catalyst material to melt and low enough
to avoid substantial conversion of diamond to graphite. The time
should be long enough for sintering to be completed and for the
entire sintering additive to be consumed.
[0038] In an embodiment, the binder material is combined with a
first fraction of coarser diamond particles or grains and a second
fraction of nano-sized diamond particles or grains in powder form.
It can be mixed in a conventional mixing process such as, for
example, a planetary ball milling process, typically in the
presence of a milling aid such as methanol, for example. Milling
balls, such as Co--WC milling balls, are used to mill the binder
and diamond powders together. The binder and diamond mixture is
then typically dried at a temperature of 50 to 100.degree. C. to
remove the methanol and other volatile residues. The resultant
aggregated mass is then consolidated into a green body ready for
sintering.
[0039] Prior to contact with the binder material, the diamond
particles of the coarser fraction may have an average particle size
ranging from about 0.1 microns to about 50 microns.
[0040] The green body, once formed, is placed in a suitable
container and introduced in to a high pressure and high temperature
press. Pressure and heat are applied in order to sinter the diamond
particles together, typically at pressures of 6 GPa or more and
temperatures of 1350.degree. C. or more.
[0041] Sintering is carried out for a time sufficient for all of
the nano-sized diamond particles or grains to be consumed, such
that no nano-structures are to be found in the sintered PCD
material.
[0042] The diamond grain sizes in the sintered PCD may range from
about 0.1 microns to about 50 microns, or from about 0.2 microns to
about 10 microns, or from about 0.9 microns to about 2 microns.
[0043] Diamond contiguity is an important performance indicator, as
it indicates the degree of intergrowth or bonding between the
diamond particles, and all else being equal the higher the diamond
contiguity the better the cutter performance. Higher diamond
contiguity is normally associated with high diamond content which
in turn results in lower binder content, as the high diamond
content translates into low porosity and therefore low binder
content, as the binder occupies the pores.
[0044] According to classic materials science of composite
materials, low binder content results in low fracture toughness, as
it is normally the hard grains (in this case diamond) that imparts
hardness to the composite material, and the more ductile binder (in
PCD, normally Co--WC) that imparts toughness to the composite
material.
[0045] Therefore, high diamond content and low binder content are
expected to be associated with increased hardness and decreased
toughness, so that failure due to fracture or spalling of the PCD
is expected to increase.
[0046] It was therefore surprising to find that PCD with improved
wear performance can be obtained by adding nanodiamond particles to
the green body prior to sintering at HPHT. The nanodiamond
particles are not evident in the final product, so that they
perform the role of a sacrificial sintering additive. Using a
nanodiamond additive in this way results in an unusual combination
of diamond content, binder content and diamond contiguity, enabling
an increase in diamond contiguity combined with a decrease in
diamond content and an increase in binder content. This unusual
combination is expected to result in improved wear performance
without compromising toughness.
[0047] Wishing not to be bound by theory, due to its very small
particle size, nanodiamond has a higher solubility than larger,
micron-sized diamond, and it is believed that it is this property
that makes it an effective sintering additive.
[0048] During the HPHT sintering cycle, the nanodiamond is believed
to dissolve preferentially to the larger diamond particles,
probably dissolving sooner and resulting in a higher carbon
concentration dissolved in the molten metal than would be the case
with the larger diamond particles. As it dissolves sooner, less of
the original large tightly packed diamond particles are lost to
dissolution, and the higher carbon concentration in the molten
metal means a higher supersaturation level is obtained which
facilitates crystallisation or precipitation of the dissolved
carbon as newly formed diamond that bonds the diamond particles
together.
EXAMPLES
[0049] Embodiments are discussed in more detail with reference to
the following examples, which are not intended to be limiting.
[0050] General Method:
[0051] 0.5 g of nanodiamond was added to 99.5 g of diamond powder
of average particle size 3.6 micron and the aggregated mass ball
milled in 10 ml of methanol with Co--WC milling balls. The ratio of
milling balls: powder was 4:1 and the milling was carried out at 90
rpm for 1 hour. 2 g of this mix were placed on top of a Co-WC
substrate and sintered under HPHT conditions at 6.8 GPa and
1450.degree. C. for 10 minutes dwell at maximum temperature. The
PCD cutter was recovered and processed.
[0052] This same method was carried out for the following
aggregated masses:
TABLE-US-00001 Amount of nanodiamond Amount of micron sized Mix (%
wt) diamond (% wt) 1 (base case) 0 100 2 0.01 99.99 3 0.05 99.95 4
0.1 99.9 5 0.5 99.5 6 0.75 99.25 7 1 99.0 8 3 97.0 9 5 95.0
[0053] Image analysis was carried out on scanning electron
micrographs of polished samples of the PCD, and the results are
shown in Table 1 below.
TABLE-US-00002 TABLE 1 Dia- mond Standard Binder Standard Diamond
Standard Mix content deviation content deviation contiguity
deviation 1 87.93 0.99 12.07 0.99 65.35 2.48 2 85.91 0.67 14.09
0.67 67.26 1.20 3 86.34 0.61 13.66 0.61 67.71 1.28 4 86.06 0.86
13.94 0.86 66.11 1.84 5 87.75 0.63 12.25 0.63 69.21 1.54 6 7 86.02
0.71 13.98 0.71 65.86 1.91 8 9
[0054] The PCD cutters were subjected to a wear resistance test and
the wear resistance results for different amounts of added
nanodiamond are shown in Table 2 below.
TABLE-US-00003 TABLE 2 Mix Wear scar length (mm) Standard deviation
1 0.311 0.002 2 3 4 0.306 0.003 5 0.310 0.004 6 0.296 0.008 7 0.299
0.001 8 0.324 0.012 9 0.314 0.003
* * * * *