U.S. patent application number 13/960906 was filed with the patent office on 2013-12-05 for intermetallic bonded diamond composite composition and methods of forming articles from same.
This patent application is currently assigned to Southern Illinois University Carbondale. The applicant listed for this patent is Southern Illinois University Carbondale. Invention is credited to Peter Filip, Dale E. Wittmer.
Application Number | 20130323108 13/960906 |
Document ID | / |
Family ID | 37073941 |
Filed Date | 2013-12-05 |
United States Patent
Application |
20130323108 |
Kind Code |
A1 |
Wittmer; Dale E. ; et
al. |
December 5, 2013 |
INTERMETALLIC BONDED DIAMOND COMPOSITE COMPOSITION AND METHODS OF
FORMING ARTICLES FROM SAME
Abstract
An intermetallic bonded diamond composite composition and
methods of processing such a composition are provided by the
present invention. The intermetallic bonded diamond composite
composition preferably comprises a nickel aluminide (Ni.sub.3Al)
binder and diamond particles dispersed within the nickel aluminide
(Ni.sub.3Al) binder. Additionally, the composite composition has a
processing temperature of at least about 1,200.degree. C. and is
processed such that the diamond particles remain intact and are not
converted to graphite or vaporized by the high-temperature process.
Methods of forming the composite composition are also provided that
generally comprise the steps of milling, pressing, and sintering
the high-temperature intermetallic binder and diamond
particles.
Inventors: |
Wittmer; Dale E.;
(Carbondale, IL) ; Filip; Peter; (Carbondale,
IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Southern Illinois University Carbondale |
Carbondale |
IL |
US |
|
|
Assignee: |
Southern Illinois University
Carbondale
Carbondale
IL
|
Family ID: |
37073941 |
Appl. No.: |
13/960906 |
Filed: |
August 7, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11389546 |
Mar 24, 2006 |
8506881 |
|
|
13960906 |
|
|
|
|
60667725 |
Apr 1, 2005 |
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Current U.S.
Class: |
419/11 ;
264/669 |
Current CPC
Class: |
B22F 2998/10 20130101;
B22F 2998/10 20130101; C22C 2026/006 20130101; C22C 32/0084
20130101; B22F 2009/043 20130101; B22F 3/12 20130101; C22C 26/00
20130101; B22F 3/10 20130101; B22F 9/04 20130101; B22F 2005/002
20130101; B22F 3/02 20130101; B22F 3/10 20130101 |
Class at
Publication: |
419/11 ;
264/669 |
International
Class: |
B22F 3/12 20060101
B22F003/12; B22F 3/10 20060101 B22F003/10 |
Claims
1. A process of forming an inter-metallic-bonded diamond composite,
comprising the steps of: (a) milling an intermetallic binder and
diamond particles; (b) pressing the intermetallic binder and
diamond particles; and (c) sintering the intermetallic binder and
diamond particles at a processing temperature of at least about
1,200 degrees C.
2. The process according to claim 1, wherein the step of milling
comprises wet milling in solvent.
3. The process according to claim 2, further comprising the step of
drying the milled intermetallic binder and diamond particles before
the pressing of step (b).
4. The process according to claim 1, further comprising the step of
screening the milled intermetallic binder and diamond particles
through a mesh before the pressing of step (b).
5. The process according to claim 1, wherein the step of sintering
the intermetallic binder and diamond particles is selected from a
group consisting of continuous sintering, vacuum sintering,
vacuum-pressure sintering, hot pressing, and hot isostatic
pressing.
6. The process according to claim 1, wherein the intermetallic
binder is an alloy selected from a group consisting of nickel
aluminide (Ni.sub.3Al), nickel aluminide (Ni.sub.3Al) and TiC
(titanium carbide), nickel aluminide (Ni.sub.3Al) and boron (B),
nickel aluminide (Ni.sub.3Al) and molybdenum (Mo), nickel aluminide
(Ni.sub.3Al), boron (B), and molybdenum (Mo), and nickel aluminide
(Ni.sub.3Al), boron (B), molybdenum (Mo), and titanium carbide
(TiC).
7. The process according to claim 1, wherein the diamond particles
comprise between approximately 20% and approximately 70% by weight
of the composition.
8. The process according to claim 1, wherein the diamond particles
range between approximately 1 and approximately 140 microns in
size.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. patent
application Ser. No. 11/389,546, filed on Mar. 24, 2006, which
claims benefit to U.S. patent application Serial No. 60/667,725,
filed Apr. 1, 2005, the entire disclosures of which are
incorporated herein by reference.
FIELD
[0002] The present invention relates generally to wear resistant
materials and more specifically to intermetallic bonded composite
compositions and processes for forming articles from the same.
BACKGROUND
[0003] In the field of wear resistant materials, diamonds are a
desirable element due to their hardness and wear resistance. Known
compositions having diamonds for wear resistance generally have
resin or ductile metal binders with relatively low processing
temperatures and pressures to achieve compaction and usable
strength. The processing temperatures have been relatively low to
prevent the diamonds from forming graphite or vaporizing during
processing. If the diamonds form graphite, they lose their hardness
and thus cannot be used in applications requiring wear resistance.
[0004] In the field of coal mining, for example, conventional tool
bits have been made from tungsten carbide (WC) bonded with cobalt
(Co), commonly referred to as carbides, for years because there has
not yet to date been a material that can surpass WC in abrasion
resistance. In operation, the attack of the Co binding phase leads
to wear of the tool bit and as the WC bit wears, it becomes less
efficient in cutting, produces more dust, and builds up heat at its
tip. This heat in turn increases the attack on the binding phase
and as a result, the tool tip either fractures or is pulled from
the body of the cutting tool.
[0004] Additionally, most of the tungsten ore that is used to
manufacture WC tool bits is exported from countries such as Canada,
China, and Russia. Similarly, cobalt is also exported from
countries such as China and South Africa. Thus, many countries are
dependent on the importation of tungsten and cobalt for their
industrial needs.
[0005] Although attempts have been made to embed diamonds into
metals to improve wear resistance and sharpness of tools, these
attempts have not been successful due to the poor oxidation
resistance and poor thermal stability of the diamonds during
processing of the metals. As previously stated, the diamonds also
tend to form graphite and/or vaporize during processing, thus
resulting in a material having unacceptable wear resistance.
SUMMARY
[0006] In one preferred form, the present invention provides an
intermetallic bonded diamond composite composition comprising a
nickel aluminide (Ni.sub.3Al) binder and diamond particles
dispersed within the nickel aluminide (Ni.sub.3Al) binder. The
composite composition is processed at high-temperatures in a manner
such that the diamond particles remain intact and do not form
graphite or vaporize during processing.
[0007] In other forms, the intermetallic bonded diamond composite
composition further comprising titanium carbide (TiC) for improved
oxidation resistance, strength of the binder, diamond retention,
and wear resistance. In yet another form, the intermetallic bonded
diamond composite further comprises an additional alloying element
selected from the group consisting of boron (B) and molybdenum (Mo)
for increased ductility of the intermetallic.
[0008] The present invention also includes processes for forming an
intermetallic bonded diamond composite. One process comprises the
steps of milling an intermetallic binder and diamond particles,
pressing the intermetallic binder and diamond particles to form a
composite article, and sintering the composite article formed of
the intermetallic binder and diamond particles at a processing
temperature of at least about 1,200.degree. C.
[0009] Additional forms of the present invention comprise a
high-temperature intermetallic binder that has a variety of
alloying elements in combination with the diamond particles. These
alloying elements comprise nickel (Ni), aluminum (Al), chromium
(Cr), iron (Fe), titanium (Ti), along with ceramic carbides.
Additional alloying elements for affecting ductility are also
provided in various forms of the present invention that comprise
iron (Fe), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium
(V), and chromium (Cr).
[0010] Further areas of applicability of the present invention will
become apparent from the detailed description provided hereinafter.
It should be understood that the detailed description and specific
examples, while indicating the preferred embodiment of the
invention, are intended for purposes of illustration only and are
not intended to limit the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The present invention will become more fully understood from
the detailed description and the accompanying photomicrographs and
drawings, wherein:
[0012] FIG. 1 is a series of photomicrographs at increasing
magnification illustrating diamond particles of various sizes in
accordance with the teachings of the present invention;
[0013] FIG. 2 is a process flow diagram illustrating a method of
processing an intermetallic bonded diamond composite composition in
accordance with the teachings of the present invention;
[0014] FIG. 3 is a series of photomicrographs at increasing
magnification illustrating diamond particles within an
intermetallic composite binder after high-temperature processing in
accordance with the teachings of the present invention; and
[0015] FIG. 4 is a series of photomicrographs at increasing
magnification illustrating faceted diamond particles within an
intermetallic composite binder after high-temperature processing in
accordance with the teachings of the present invention.
[0016] Corresponding reference numerals indicate corresponding
parts throughout the several views of the drawings.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] The following description of the preferred embodiments is
merely exemplary in nature and is in no way intended to limit the
invention, its application, or uses.
[0018] The present invention generally comprises an intermetallic
bonded diamond composite composition that is made of a
high-temperature intermetallic binder and diamonds, hereinafter
referred to as diamond particles. The high-temperature
intermetallic binder is preferably nickel aluminide (Ni.sub.3Al)
and may also include titanium carbide (TiC) to reduce oxidation,
strength of the binder, diamond retention, and wear resistance, and
either or both boron (B) and molybdenum (Mo) for increased
ductility. However, nickel aluminide (Ni.sub.3Al) alone, without
the addition of titanium carbide (TiC), boron (B), or molybdenum
(Mo) as the high-temperature binder has resulted in a composite
composition having excellent wear resistance. Additional alloying
elements that form a high-temperature intermetallic binder, other
than or in addition to nickel aluminide (Ni.sub.3Al), may also be
employed in accordance with the teachings of the present invention
as described in greater detail below.
[0019] Processing techniques according to various forms of the
present invention are carried out at a relatively high temperature
while preventing the diamond particles from forming graphite or
vaporizing during processing. As a result, an intermetallic bonded
diamond composite composition is used to form composite articles
exhibiting superior wear resistance. These processes are described
in greater detail below.
[0020] Referring to FIG. 1, a variety of diamond sizes were
employed according to the teachings of the present invention. The
sizes ranged from 2-10 .mu.m (upper left), 10-15 .mu.m (upper
right), 35-40 .mu.m (lower left), 20-25 .mu.m (lower right), and
sizes up to and including, but not limited to, 80-100 .mu.m and
120-140 .mu.m (not shown). Generally, larger diamond sizes are
preferred because the smaller diamond sizes have demonstrated a
reduced ability to withstand certain processing methods as
described in greater detail below.
[0021] Referring now to FIG. 2, a method of processing the
intermetallic bonded diamond composite composition is illustrated
in a flow diagram. Generally, the high-temperature intermetallic
binder and the diamond particles are milled to form a homogeneous
mixture. The homogeneous mixture is then pressed to form a
composite article in a shape as desired or as a coating on a
substrate for the desired application, e.g. tool bit. The pressed
composite article is then sintered by processes such as, but not
limited to, continuous sintering, vacuum sintering, vacuum-pressure
sintering, hot pressing, and hot isostatic pressing. This process,
along with additional embodiments for further processing steps, are
now described in greater detail.
Milling
[0022] The high-temperature intermetallic binder and the diamond
particles are first milled preferably by a wet ball milling
operation. Preferably, the fluid used for the wet milling is
isopropyl alcohol; however, other fluids may also be used while
remaining within the scope of the present invention. The
high-temperature intermetallic binder and the diamond particles are
placed in a container and milled for approximately two (2) hours in
one form of the present invention. After the milling operation, the
high-temperature intermetallic binder and the diamond particles
form powders which are then dried, preferably in a vacuum oven,
until all of the fluid is eliminated. In one form of the process
according to the teachings of the present invention, the containers
are periodically closed, shaken, and then returned to the dryer
every thirty (30) minutes. After the fluid is eliminated, the
high-temperature intermetallic binder and the diamond particles are
preferably milled again for a period of time to deagglomerate the
resulting powders.
[0023] After the milling operation, the powders are passed through
a mesh sieve, e.g. 40 mesh, to obtain a free flowing powder mixture
of the high-temperature intermetallic binder and diamond particles.
The mixture is then pressed to form a composite article in a shape
as desired or processed as a coating on a substrate for the desired
end use or application.
Sintering
[0024] The composite articles formed from the intermetallic bonded
diamond composite composition are then further developed through a
sintering process. The sintering process may include one or more of
a variety of sintering processes such as pressureless or continuous
sintering, vacuum sintering, vacuum-pressure sintering, hot
pressing, or hot isostatic pressing. These sintering processes are
exemplary only and are not intended to limit the scope of the
present invention. It should be understood that other sintering
processes may also be employed while remaining within the teachings
of the present invention.
[0025] With a pressureless or continuous sintering process, the
composite articles are placed in graphite boats with tight fitting
lids. Additionally, a setter plate, preferably coated with boron
nitride (BN) to prevent reactions with the graphite, is used to
protect the bottom of each boat. Preferably, boats containing no
composite articles, or "dummy" boats, are placed before and after
each boat containing composite articles for better thermal
balance.
[0026] In one form, the boats are run on a belt at a rate into the
furnace of the continuous sintering process until they are centered
in a hot zone and are then stopped. The boats are held for a period
of time, after which the temperature of the furnace is increased
and the boats are held for an additional period of time. After this
second hold period, the belt is started again and the boats are
transported at a rate to complete the sintering process. In one
form, the boats are run at a rate of about 1.5 in. (3.81 cm) per
minute into a hot zone of approximately 2,192.degree. F.
(1,200.degree. C.). The corresponding hold period is about one (1)
hour and the temperature of the furnace is increased to about
2,552.degree. F. (1,400.degree. C.). The boats are then held for a
period of about one (1) hour, after which the belt is started again
and moved at a rate of about 1.5 in. (3.81 cm) per minute to
complete processing of the composite articles.
[0027] In an alternate vacuum/pressure sintering process, similar
graphite boats containing the composite articles are centered in a
large tube furnace. After purging the furnace, preferably with
argon (Ar), the temperature is increased from room temperature
under vacuum at a given rate to a first temperature. At this first
temperature, the furnace is again purged and the temperature is
increased again for a period of time to a second temperature. The
temperature is again increased to a third temperature and pressure
is increased to a given level and held for a period of time. The
furnace power is then shut off and the graphite boats and the
composite articles contained therein are allowed to cool to room
temperature.
[0028] In one form, the furnace is first purged with Ar for three
(3) cycles and the first temperature is about 1,832.degree. F.
(1,000.degree. C.), which is obtained at. a rate of about
50.degree. F. (10.degree. C.) per minute. The second temperature is
about 2,192.degree. F. (1,200.degree. C.) and the first hold time
is about one (1) hour. The third temperature is about 2,507.degree.
F. (1,375.degree. C.) with a pressure of about 300 psig of Ar for a
period of time of about one (1) hour.
[0029] In an alternate hot pressing process, dies and punches are
preferably formed from high density graphites, although the high
density graphites exhibit a tendency to wear. The composite
articles are first preloaded and then the hot press is purged
through a number of cycles, preferably using Ar. Vacuum is then
applied and held for a period of time, after which the temperature
is increased to a first level, stabilized for a period of time, and
then increased to a second level. Pressure is then increased and
the temperature increased again to a third level, while the load is
increased to a given level. The temperature is held at this third
level for a period of time and the temperature is further increased
along with pressure until a predetermined extension or temperature
maximum is reached.
[0030] In one form, the preload is about 500 lbs and the hot press
is purged for three (3) cycles. The vacuum is held for about 8 to
12 hours and the first temperature is about 932.degree. F.
(500.degree. C.). The second temperature is about 1,832.degree. F.
(1,000.degree. C.), followed by a pressure of about 5 psi of Ar and
a third temperature of about 2,192.degree. F. (1,200.degree. C.)
under about a load of about 1,500 lbs. The third temperature was
held for about one (1) hour, and the temperature maximum or peak,
which varies according to the intermetallic bonded diamond
composite composition, is established as the temperature just below
where the intermetallic is forced out of the hot-press die at a
load of about 1,500 lbs.
[0031] Generally, the hot press process results in higher density
compacts, as the pressure from this process forces the liquid
intermetallic into the pores of the composite composition and
forces out trapped gasses. Additionally, preferably processing
temperatures for the sintering processes described herein are
between about 2,192.degree. F. (1,200.degree. C.) and about
2,912.degree. F. (1,600.degree. C.) for times between about 15
minutes and about 2 hours or more.
[0032] Referring now to FIGS. 3 and 4, the presence of diamonds in
the high-temperature intermetallic binder after processing is
shown. FIG. 3 illustrates scanning electron microscope (SEM) images
of intermetallic bonded diamonds (IBDs) following continuous
sintering at 1,400.degree. C. FIG. 4 illustrates SEM images of a
hot-pressed surface of an intermetallic bonded diamond formulation
showing how well dispersed and faceted the diamonds are after
processing. The diamonds, which are the dark phase, are well
preserved and well faceted, and have not been converted to graphite
or vaporized during processing. These photomicrographs are of an
intermetallic bonded diamond composite composition having only
nickel aluminide (Ni.sub.3Al) as the high-temperature intermetallic
binder without any additional alloying element, thus demonstrating
that this intermetallic binder alone protects the diamonds from
graphitization and vaporization.
[0033] The formulation for the high-temperature intermetallic
binder is preferably a nickel aluminide (Ni.sub.3Al) with
additional alloying elements in other forms of the invention to
improve properties of the intermetallic bonded diamond composite
composition. For example, titanium carbide (TiC) is added to reduce
oxidation, improve strength of the binder, improve diamond
retention, and increase wear resistance of the composite
composition. Additionally, boron (B) and/or molybdenum (Mo) are
added to improve the ductility of the composite composition. Other
elements such as iron (Fe), titanium (Ti), zirconium (Zr), hafnium
(Hf), vanadium (V), or chromium (Cr) may also be employed to
improve the ductility of the composite composition in accordance
with the teachings of the present invention.
[0034] Alternately, the high-temperature intermetallic binder may
be composed of combinations of nickel (Ni), aluminum (Al), chromium
(Cr), iron (Fe), and titanium (Ti) while remaining within the scope
of the present invention. Additionally, the high-temperature
intermetallic binder may also comprise a ceramic carbide such as,
by way of example, titanium carbide (TiC), silicon carbide (SiC),
tungsten carbide (WC), or boron carbide (B.sub.4C).
[0035] According to the principles of the present invention, it has
been determined that at least one mechanism for the protection of
the diamonds during high-temperature processing is the relative
close proximity, or high difference, of the coefficient of thermal
expansion (CTE) of the diamond particles and the high-temperature
intermetallic binder. For instance, the CTE of the diamond
particles is approximately 1.0.times.10.sup.-6/.degree. C. and the
CTE of the high-temperature intermetallic binder of Ni.sub.3Al is
approximately 14.0.times.10.sup.-6/.degree. C. The large difference
in these CTE values provides for the contraction of the
intermetallic binder surrounding the diamond particles, thus
physically clamping the diamonds through the compressive stresses
developed. These clamping stresses are believed to put enough
stress on the diamond particles to keep them from converting to
graphite. Accordingly, other materials having relatively large
differences in CTE compared to that of the diamond particles may
also be employed as a binder in accordance with the teachings of
the present invention.
[0036] The diamond volume is generally between about 0.5% by volume
to about 80% by volume, although higher values may also be employed
depending on the high-temperature intermetallic binder and the
particular end use or application. Sizes of the diamond particles
range from about 1 micron up to about 700 microns or even greater,
depending again on the high-temperature intermetallic binder and
the particular application.
[0037] Applications for such an intermetallic bonded diamond
composite composition are numerous and include, by way of example,
coal mining tools, rock bits, rock cutters, masonry cutter and
drills, cutting tools, abrasion resistant parts, rotary cutters,
industrial drills, continuous miners, particle board cutters,
ceramic tile cutters and routers, and high heat transfer platens
and shapes. It should be understood that these applications are
exemplary only and should not be construed to limit the scope of
the present invention.
[0038] In testing conducted to date, the intermetallic bonded
diamond composite compositions have been shown to improve wear
resistance up to 800 times that of conventional tungsten carbide
(WC). Table I below illustrates results of such testing, which
includes both grinding and diamond cut-off wheel testing, with
various formulations of intermetallic bonded diamond composite
compositions compared with tungsten carbide (WC). TABLE-US-00001
TABLE I Dia- Ave. Area mond Depth of Penetration Wt. Wt. Loss of
Cut Cut Rate .times. 10.sup.-3 Sample % Formulation (grinding)
(in.) (in.sup.2) (in.sup.2/min) IBD1 33 Ni.sub.3Al 5.6% 0.489 0.134
4.5 IBD2 35 Ni.sub.3Al and 5.0% 0.150 0.041 1.4 35% TiC IBD3 33
Ni.sub.3Al 1.7% 0.036 0.008 0.3 IBD4 35 Ni.sub.3Al and 1.9% 0.034
0.009 0.3 35% TiC, B, and Mo WC None 94% WC 3.7% 0.912 0.324 259.2
and 6% Co
[0039] Additional testing including polishing the composite
articles using standard metallographic techniques resulted in
extremely high wear resistance. In one set of tests, after 30 hours
of polishing against a new 250 .mu.m diamond polishing wheel, less
than 1% wear was observed. It should be understood that these test
results are exemplary in nature to demonstrate the improved wear
resistance of intermetallic bonded diamond composite compositions
over conventional tungsten carbide (WC) and in no way are intended
to limit the scope of the present invention.
[0040] The description of the invention is merely exemplary in
nature and, thus, variations that do not depart from the substance
of the invention are intended to be within the scope of the
invention. Such variations are not to be regarded as a departure
from the spirit and scope of the invention.
* * * * *