U.S. patent application number 13/870610 was filed with the patent office on 2013-10-31 for metal alloy and jewelry articles formed therefrom.
This patent application is currently assigned to Black & Blue. The applicant listed for this patent is BLACK & BLUE. Invention is credited to Asher C. Hoffman.
Application Number | 20130287622 13/870610 |
Document ID | / |
Family ID | 49477461 |
Filed Date | 2013-10-31 |
United States Patent
Application |
20130287622 |
Kind Code |
A1 |
Hoffman; Asher C. |
October 31, 2013 |
METAL ALLOY AND JEWELRY ARTICLES FORMED THEREFROM
Abstract
An article is formed of a metal alloy that includes the
following constituents: (a) cobalt in an amount of between about
50.0% to about 51.0% by weight of the article; (b) tungsten in an
amount of between about 21.0% to about 22.0% by weight of the
article; (c) chromium in an amount of about 22.0% by weight of the
article; (d) nickel in an amount of between about 2.5% to about
3.0% by weight; and (e) molybdenum in an amount of about 5.0% by
weight. The article can be in the form of a jewelry article, such
as a ring, a bracelet, a necklace, or an earring and can be formed
by a shell casting process.
Inventors: |
Hoffman; Asher C.; (New
York, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BLACK & BLUE |
New York |
NY |
US |
|
|
Assignee: |
Black & Blue
New York
NY
|
Family ID: |
49477461 |
Appl. No.: |
13/870610 |
Filed: |
April 25, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61639671 |
Apr 27, 2012 |
|
|
|
Current U.S.
Class: |
420/436 ;
164/47 |
Current CPC
Class: |
C22C 27/04 20130101;
C22C 1/02 20130101; A44C 27/003 20130101; C22C 30/00 20130101; C22C
19/07 20130101 |
Class at
Publication: |
420/436 ;
164/47 |
International
Class: |
A44C 27/00 20060101
A44C027/00 |
Claims
1. An article formed of a metal alloy comprising: cobalt in an
amount of between about 50.0% to about 51.0% by weight of the
article; tungsten in an amount of between about 21.0% to about
22.0% by weight of the article; chromium in an amount of about
22.0% by weight of the article; nickel in an amount of between
about 2.5% to about 3.0% by weight; and molybdenum in an amount of
about 5.0% by weight.
2. The article of claim 1, wherein the article comprises a jewelry
article.
3. The article of claim 2, wherein the jewelry article is selected
from the group consisting of a ring, a bracelet, a necklace, a
pendant, and an earring.
4. The article of claim 1, wherein the article is formed by a shell
casting process.
5. The article of claim 1, wherein the metal alloy has a melting
point of between about 1495.degree. C. and about 1910.degree.
C.
6. The article of claim 1, wherein the metal alloy has a hardness
value on a Rockwell scale of between HRC40 and HRC42.
7. The article of claim 1, wherein the metal alloy has a density of
about 10.2 g/cm.
8. The article of claim 1, wherein the metal alloy is shell
castable and can be machined after being formed by a shell casting
process.
9. A method forming a scratch resistant, machinable article of
jewelry comprising the steps of: preparing a metal alloy that
comprises: cobalt in an amount of between about 50.0% to about
51.0% by weight of the article; tungsten in an amount of between
about 21.0% to about 22.0% by weight of the article; chromium in an
amount of about 22.0% by weight of the article; nickel in an amount
of between about 2.5% to about 3.0% by weight; and molybdenum in an
amount of about 5.0% by weight; pouring the metal alloy in a melted
state into a mold; and forming the jewelry article by means of a
shell casting process, wherein the formed jewelry article is at
least substantially scratch resistant, yet flexible, and is
machinable and of such hardness that a stone can be set directly
into the jewelry article.
10. A method forming a scratch resistant, machinable article of
jewelry comprising the steps of: preparing a metal alloy that at
least includes: cobalt in an amount of between about 50.0% to about
51.0% by weight of the article; and tungsten in an amount of
between about 21.0% to about 22.0% by weight of the article;
pouring the metal alloy in a melted state into a mold; and forming
the jewelry article by means of a shell casting process, wherein
the formed jewelry article is at least substantially scratch
resistant, yet flexible, and is machinable and of such hardness
that a stone can be set directly into the jewelry article.
11. The method of claim 10, wherein the metal alloy includes carbon
in an amount up to about 2% by weight of the article.
12. The method of claim 10, wherein the metal alloy further
includes chromium, nickel and molybdenum.
13. A jewelry article formed of a metal alloy that undergoes a
shell casting process to form a blank that is then processed to
form the jewelry article, wherein the metal alloy includes cobalt
present in an amount between 20.0% to about 60.0% by weight of the
article and tungsten present in an amount between 20.0% to about
60.0% by weight of the article.
14. The jewelry article of claim 13, wherein the blank is processed
by a machining process.
15. The jewelry article of claim 13, wherein the cobalt is present
in an amount of between about 50.0% to about 51.0% by weight of the
article; and the tungsten is present in an amount of between about
21.0% to about 22.0% by weight of the article.
16. A jewelry article formed of a metal alloy comprising: cobalt in
an amount of between about 20.0% to about 60.0% by weight of the
article; and tungsten in an amount of between about 20.0% to about
60.0% by weight of the article; wherein the jewelry article is
formed of a blank that is formed of the metal alloy by a shell
casting process; wherein the blank is machinable.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application claims the benefit of U.S. Patent
Application Ser. No. 61/639,671, filed Apr. 27, 2012, which is
hereby incorporated by reference in its entirety.
TECHNICAL FIELD
[0002] The present invention relates generally to methods of making
jewelry items such as finger rings, bracelets, necklaces, pendants,
earrings, body jewelry and the like, and more particularly to a
metal alloy, such as a tungsten cobalt alloy, that is particularly
adapted to form the above jewelry articles by a casting process and
more specifically, the present metal alloy composition is
especially adapted to be machined after its cast and offers a
number of other desirable and advantageous material properties.
BACKGROUND
[0003] Jewelry has for centuries been made of soft materials such
as gold, silver, platinum and other soft materials, because such
metals were malleable, castable, forgeable, moldable or otherwise
formable. However, whereas such materials are relatively easy to
mold, shape and polish, they are equally subject to wear,
scratching and other damage detracting from their longevity
appearance and value, i.e., wearing down of edges to a smooth and
rounded state.
[0004] More recently, the industry has focused on other materials
including tungsten, cemented carbide and high tech ceramics that
are much harder than the previously mentioned precious metals, and
once formed, have increased harness when used in a normal jewelry
wearing environment. The problem with such materials is that
because of their hardness, they are very difficult to shape, and
once formed, require special machining and/or grinding tools to
alter their configuration and appearance.
[0005] Many of these types of jewelry articles are in the form of
tungsten carbide or plain cobalt metal jewelry. However, as
discussed herein, there are a number of disadvantages with using
these types of materials. The metal alloy of the present invention
overcomes the deficiencies of these materials and provides a
superior metal that is particularly adapted for use in making
various jewelry articles.
[0006] With respect to using hard metals, including tungsten, to
form jewelry articles, one of the most common manufacturing
techniques is a metal injection molding (MIM) process. The metal
injection molding (MIM) process is commonly used to precisely
manufacture small metal components that exhibit complicated or
unusual shapes. The basic MIM process involves: 1) the injection
molding of a feedstock comprised of fine metal powders mixed with a
polymeric binder, 2) a debinding step wherein the polymeric binder
is removed from the component, and 3) a sintering step wherein the
porosity of the component is reduced. However, MIM components are
often considered to exhibit mechanical properties that are inferior
to the properties that are attainable from components produced via
machining operations. In the case of surgical devices, the MIM
process is often considered an inferior method since these devices
require excellent mechanical performance. The MIM process is
further discussed in U.S. Pat. No. 4,113,480, the disclosure of
which is incorporated herein by reference. The feedstock will vary
depending upon the final articles that are to be produced and can
include, in addition to the binders that serve to carry the metal
powders into the mold, a percentage by weight of tungsten-carbide
(WC) and a percentage by weight of cobalt (the percentages of each
can vary widely and metallic binders other than cobalt (e.g.
nickel) can be used, as well). In addition, other alloying metals
or compounds can be added to the feedstock as additives (e.g.
tantalum, tantalum-carbide, titanium-carbide, niobium-carbide,
chromium-carbide, cobalt-nickel, nickel-tantalum, titanium-nitride,
and diamond dust), which produce different chemical and physical
properties in the resulting cemented carbide.
[0007] Conventionally, tungsten jewelry, including tungsten rings,
is manufactured using the MIM process; however, as can be
appreciated based on the above disclosure, the MIM process is
expensive and is time consuming. As a result, there is a need for
an improved tungsten alloy that is suitable for undergoing
different, less expensive and less complex manufacturing techniques
to product jewelry articles having superior properties.
SUMMARY
[0008] In accordance with one exemplary embodiment, an article is
formed of a metal alloy that includes the following constituents:
(a) cobalt in an amount of between about 20.0% to about 60.0% by
weight of the article; and (b) tungsten in an amount of between
about 20.0% to about 60.0% by weight of the article. Other
constituents such as chromium, nickel, molybdenum and carbon can be
used in forming the metal alloy of the present invention. The
formed article is particularly suited for making jewelry
articles.
[0009] In accordance with one exemplary embodiment, an article is
formed of a metal alloy that includes the following constituents:
(a) cobalt in an amount of between about 50.0% to about 51.0% by
weight of the article; (b) tungsten in an amount of between about
21.0% to about 22.0% by weight of the article; (c) chromium in an
amount of about 22.0% by weight of the article; (d) nickel in an
amount of between about 2.5% to about 3.0% by weight; and (e)
molybdenum in an amount of about 5.0% by weight. The article can be
in the form of a jewelry article, such as a ring, a bracelet, a
necklace, or an earring. In accordance with one exemplary
embodiment, the article is formed by a casting process, such as a
shell casting process.
[0010] In yet another exemplary embodiment, a method for forming a
scratch resistant, machinable article of jewelry includes the steps
of: (a) preparing a metal alloy that comprises: (1) cobalt in an
amount of between about 50.0% to about 51.0% by weight of the
article; (2) tungsten in an amount of between about 21.0% to about
22.0% by weight of the article; (3) chromium in an amount of about
22.0% by weight of the article; (4) nickel in an amount of between
about 2.5% to about 3.0% by weight; and (5) molybdenum in an amount
of about 5.0% by weight; (b) pouring the metal alloy in a melted
state into a mold (shell); and (c) forming the jewelry article by
means of a shell casting process, wherein the formed jewelry
article is at least substantially scratch resistant, yet flexible,
and is machinable and of such hardness that a stone can be set
directly into the jewelry article.
BRIEF DESCRIPTION OF DRAWING FIGURES
[0011] FIG. 1 is a perspective view of a ring made with a tungsten
carbide composition of the present invention and according to a
shell casting process as described herein;
[0012] FIG. 2 is a perspective view of a jewelry article made with
the tungsten carbide composition of the present invention;
[0013] FIG. 3 is a cross-sectional view showing shell components
used in a shell casting process; and
[0014] FIG. 4 is a side perspective view showing a resulting blank
formed with the casting shells of FIG. 3.
DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS
[0015] The present invention includes a composition and method for
making composite articles that have desirable material
characteristics including being scratch resistant (yet still
flexible), machinable and can be manufactured using a casting
process. Jewelry items such as finger rings, bracelets, necklaces,
pendants, earrings, body jewelry, and the like, are one particular
example of such articles. Medical, dental, and industrial devices
or components are other examples of such articles.
[0016] More specifically and according to one embodiment, the
present invention relates to a tungsten carbide composition that is
particularly suitable for making jewelry articles and has unique
properties that allow the composition to be cast (e.g., using a
shell casting process as described herein), machined, and
manipulated (e.g. set with stones), while still being at least
substantially scratch resistant and heavy in weight (all of which
are desirable properties). The tungsten carbide composition of the
present invention can thus be used to form jewelry articles using
techniques other than metal injection molding (MIM) techniques,
while providing superior results. In other words, the tungsten
carbide composition of the present invention allows tungsten
jewelry articles, such as rings, to be manufactured using an
alternative process other than MIM.
[0017] In accordance with one embodiment of the present invention,
a metal alloy that is particularly suitable for use in making
jewelry articles by shell casting includes the following
constituents (% by weight):
TABLE-US-00001 Cobalt (Co) 20.0 to 60.0% Tungsten (W) 20.0 to
60.0%
[0018] In accordance with one embodiment of the present invention,
a metal alloy that is particularly suitable for use in making
jewelry articles by shell casting includes the following
constituents (% by weight):
TABLE-US-00002 Cobalt (Co) 45.0 to 55.0% Tungsten (W) 20.0 to
25.0%
[0019] In accordance with another embodiment of the present
invention, a metal alloy that is particularly suitable for use in
making jewelry articles by shell casting includes the following
constituents (% by weight):
TABLE-US-00003 Cobalt (Co) 50.0 to 51.0% Tungsten (W) 21.0 to 22.0%
Chromium (Cr) 22.0% Nickel (Ni) 2.5 to 3.0% Molybdenum (Mo)
5.0%
[0020] In accordance with the present invention, the metal alloy
can include carbon as a constituent; however, when carbon is part
of the metal alloy, the carbon is present in no more than 2.0% by
weight.
[0021] The above metal alloy of the present invention also has the
following properties. The metal alloy has a hardness value on the
Rockwell scale of HRC39-43 and in particular, HRC40-42. As is
known, the determination of the Rockwell hardness of a material
involves the application of a minor load followed by a major load,
and then noting the depth of penetration, vis a vis, hardness value
directly from a dial, in which a harder material gives a higher
number.
[0022] The density of the metal alloy is about 10.2 g/cm and the
melting point of the metal alloy is between about 1495.degree. C.
to about 1907.degree. C. depending upon the specific formulation of
the alloy.
[0023] It will be appreciated that there can be some variation in
the weight percentages of the above constituents that form the
metal alloy of the present invention while still maintain the
advantageous properties and characteristics described herein.
[0024] In accordance with one embodiment, a three-dimensional
article (a blank) that is formed with the metal alloy described
above by means of a shell casting process (see blank 400 of FIGS.
3-4). As will be understood, the article (blank) is then further
processed using conventional techniques, such as
machining/polishing, to form an article of jewelry, such as a ring
100 shown in FIG. 1. As described herein, the article (blank) can
be processed into any number of different types of jewelry articles
and therefore, a ring is merely one exemplary jewelry article and
is not limiting of the present invention. Other exemplary jewelry
articles include but are not limited to bracelets, necklaces,
pendants, earrings, etc. FIG. 2 shows another jewelry article 200
which can be formed using the alloy composition of the present
invention and can be formed from a blank as discussed herein. FIG.
2 illustrates that multiple articles can be combined to form a
complete jewelry article.
[0025] In addition, as described herein, the article can be further
manipulated to produce the finished jewelry article. For example,
the article can be set with stones or the like and can be easily
machines (to allow intricate details to be formed) and also can be
easily polished. All of these attributes are advantageous and
desirable and are in contrast to the more limiting processing
available with articles formed using a MIM process.
[0026] In accordance with the present invention, the article of
jewelry can be formed using any number of different techniques;
however, in accordance, with one preferred technique, the article
of jewelry is manufactured using a casting process. More
specifically, the article of jewelry is formed using a shell
casting process as described below.
[0027] Investment casting is a traditional industrial process based
on and also called lost-wax casting, which happens to be one of the
oldest known metal-forming techniques. Casts can be made of a wax
model itself (the direct method); or of a wax copy of a model that
need not be of wax (the indirect method). The following steps are
for the indirect process and are provided for illustrative purposes
only and are not limiting of the present invention. A first step is
to produce a master pattern (model). An artist creates an original
pattern from wax, clay, wood, plastic, steel, or another material.
A mold, known as the master die, is made of the model (master
pattern). The model can be made from a low-melting-point, such as
metal, steel, etc. Although called a wax pattern, pattern materials
can also include plastic and other materials. In one process the
wax is poured into the mold and swished around until an even
coating covers the inner surface of the mold. This is repeated
until the desired thickness is reached. Another method is filling
the entire mold with molten wax, and let it cool, until a desired
thickness has set on the surface of the mold. After this the rest
of the wax is poured out again, the mold is turned upside down and
the wax layer is left to cool and harden. If a core is required,
there are generally two options: soluble wax or ceramic. Soluble
wax cores are designed to melt out of the investment coating with
the rest of the wax pattern, whereas ceramic cores remain part of
the wax pattern and are removed after the workpiece is cast. The
wax patterns can then be assembled by removing from the mold.
Depending on the application multiple wax patterns may be created
so that they can all be cast at once. In other applications,
multiple different wax patterns can be created and then assembled
into one complex pattern. In the first case the multiple patterns
are attached to a wax sprue, with the result known as a pattern
cluster, or tree; as many as several hundred patterns may be
assembled into a tree. The wax patterns are attached to the sprue
or each other by means of a heated metal tool. The wax pattern can
also be chased, which means the parting line or flashing are rubbed
out using the heated metal tool. Finally it is dressed, which means
any other imperfections are addressed so that the wax now looks
like the finished piece.
[0028] The ceramic mold, known as the investment, is produced by
three repeating steps: coating, stuccoing, and hardening. The first
step involves dipping the cluster into a slurry of fine refractory
material and then letting any excess drain off, so a uniform
surface is produced. This fine material is used first to give a
smooth surface finish and reproduce fine details. In the second
step, the cluster is stuccoed with a coarse ceramic particle, by
dipping it into a fluidized bed, placing it in a rainfall-sander,
or by applying by hand. Finally, the coating is allowed to harden.
These steps are repeated until the investment is the required
thickness. Common refractory materials used to create the
investments are: silica, zircon, various aluminum silicates, and
alumina. Silica is usually used in the fused silica form, but
sometimes quartz is used because it is less expensive. Exemplary
binders used to hold the refractory material in place include:
ethyl silicate (alcohol-based and chemically set), colloidal silica
(water-based, also known as silica sol, set by drying), sodium
silicate, and a hybrid of these controlled for pH and viscosity.
The investment is then allowed to completely dry. Drying can be
enhanced by applying a vacuum or minimizing the environmental
humidity. It is then turned upside-down and placed in a furnace or
autoclave to melt out and/or vaporize the wax. Most shell failures
occur at this point because the waxes used have a thermal expansion
coefficient that is much greater than the investment material
surrounding it, so as the wax is heated it expands and induces
great stresses. In order to minimize these stresses the wax is
heated as rapidly as possible so that the surface of the wax can
melt into the surface of the investment or run out of the mold,
which makes room for the rest of the wax to expand. In certain
situations holes may be drilled into the mold beforehand to help
reduce these stresses. Any wax that runs out of the mold is usually
recovered and reused.
[0029] The mold is then subjected to a burnout to remove any
moisture and residual wax, and to sinter the mold. Sometimes this
heating is also used as the preheat, but other times the mold is
allowed to cool so that it can be tested. If any cracks are found
they can be repaired with ceramic slurry or special cements. The
mold is preheated to allow the metal to stay liquid longer to fill
any details and to increase dimensional accuracy, because the mold
and casting cool together.
[0030] The investment mold is then placed cup-upwards into a tub
filled with sand. The metal may be gravity poured, but if there are
thin sections in the mold it may be filled by applying positive air
pressure, vacuum cast, tilt cast, pressure assisted pouring, or
centrifugal cast. The shell is hammered, media blasted, vibrated,
waterjeted, or chemically dissolved (sometimes with liquid
nitrogen) to release the casting. The sprue is cut off and
recycled. The casting can then be cleaned up to remove signs of the
casting process, usually by grinding or other machining
process.
[0031] While suitable for many uses, the above described investment
cast process is not particularly suited for use in the present
invention and in particular to form article with the present metal
alloy due to a number of reasons including the fact that the high
melting temperatures of the material (metal alloy) prevent
investment from being used. As a result, another casting process is
required for use with the present metal alloy.
[0032] Thus, the above-described traditional casting process is
modified for alternative-metal casting. In accordance with the
present invention, the article is formed using a shell casting
process (alternatively, a modified lost wax casting). Normally, the
wax that is inside the special plaster (referred to as the
investment as described above) dissolves in water at the end of the
process, thereby freeing up the tree that is made of a metal, such
as gold, platinum or silver. For alternative metal casting, the
melting temperatures are too high for investment since, as
described above, the melting point temperature for the metal alloy
of the present invention is between about 1495.degree. C. and about
1907.degree. C.
[0033] In view of the foregoing high melting point temperatures,
the wax trees are dipped in special types of plaster to build up
layers. The pour step of the present process is aggressive. Instead
of simply using water to release the tree from the plaster by
dissolving the wax, the alternative process includes a hammer step
in which the article is hammered and the plaster is shattered in
order to free the casted article, such as article.
[0034] In particular, one exemplary shell process for use with
metal alloy of the present invention in order to produce jewelry
articles is described below. The shell casting process can be
described as including the following steps:
[0035] 1) production of wax/plastic "sub-masters": these waxes are
either 1) final designs that will go directly to finishing after
casting, 2) ingots/blanks that are then machined after casting and
then sent to finishing, or 3) final designs that will also get
machined and then go to finishing.
[0036] 2) addition of waxes to a tree: this tree is structured in
the traditional way for casting.
[0037] 3) layer by layer application of a ceramic slurry: a tree is
dipped into this slurry once a day and allowed to dry (harden).
Generally, 5 layers are applied. After 5 days the coated tree is
ready.
[0038] 4) burn out: the hardened ceramic shell is placed in an
oven. The wax/plastic is burned out
[0039] 5) molten alloy is prepared in accordance with the present
invention: previously prepared metal mixture in melted.
[0040] 6) pour: the ceramic shell is removed from the oven and the
molten metal is poured in.
[0041] 7) cooling: the filled ceramic shell is allowed to cool for
a day.
[0042] 8) release: the metal core is released from the ceramic
shell by shattering the shell with heavy blows. Usually this is
done manually with a hammer, but in some cases a pneumatic tool is
used.
[0043] 9) clipping: metal blanks, or final designs are clipped from
the tree and the left over button of the pieces is ground off.
[0044] 10) finishing 1: castings are sent to a tumbling process.
This rough polishes and burnishes the metal.
[0045] 11) finishing 2: if and machining is needed, combination
with other metals, or inlay.
[0046] 13) finishing 3: any stone setting that might be
required.
[0047] 14) finishing 4: polishing using a buffing wheel and various
abrasive compounds of increasing fineness to bring about a bright
luster.
[0048] 15) finishing 5: wash-out/steam: pieces are submerged in an
ultrasonic bath to release polishing debris/compound. then, they
are steamed to blast off any residual material loosed by the
bath.
[0049] 16) finishing 6: any additional finish like satin,
sandblast, beadblast, scratch, acid etch, photo etch, plating
(ionic, DLC, etc. . . . ), and the like. This could also be the
point where other components are laser welded to the main body of
the piece, or laser engraving of any additional design details like
the logo, or hallmark.
[0050] 17) finishing 7: final steam clean.
[0051] 18) Quality assurance (QA) inspection: pieces are inspected
to ascertain if the final product is properly made.
[0052] 19) repeat of any step needed to correct a flaw found in
QA.
[0053] 20) package and ship.
[0054] FIG. 3 shows an exemplary shell cast process. Element 300
represents a shell that has a wall 302 that defines a hollow
interior 305 into which the molten alloy material is delivered
(poured). It will be appreciated that the wall 300 can be formed of
one or more layers of plaster that form the shell. The hollow
portion 305 of the shell 302 defines a flow path for the molten
material. Molten material is delivered into the hollow interior 305
and flows according to the arrows 310 to allow complete filling of
the hollow interior 305. The shape of the resulting blank that is
formed and in effect is in the shape of the hollow interior 305 of
the shell 300. FIG. 4 shows a resulting blank 400 that is formed
after the wall 302 (e.g., plaster layers) shown in FIG. 3 is
removed. Element 410 represents a screw that is formed in the pour
step (see FIG. 3) and this portion is removed, thereby forming a
ring shaped blank 400 in this illustrated embodiment. As discussed
above, the blank 400 is then processed (machined, etc.) and stones
are optionally set, etc.
[0055] It will be understood that the preceding steps describe an
exemplary shell casting process and are not limiting of the present
invention since one or more the steps can be modified and/or
eliminated.
[0056] In one embodiment, the casting process to form blank 400
(and ultimately article 100) is performed at a temperature about
2000.degree. C. which is above the melting point for the metal
alloy of the present invention. The casting process takes a number
of days and in particular, can take a number of days to form the
blank 400 (and ultimately article 100).
[0057] There are a number of advantages obtained by using the metal
alloy of the present invention and in particular, why the tungsten
cobalt based metal alloy of the present invention is superior to
using conventional tungsten carbide or conventional cobalt for
forming jewelry articles. First, the present metal alloy has
improved appearance relative to conventional articles of tungsten
carbide but with a lower cost due to the simplified manufacturing
process and the use of the special alloy of the present invention.
Second, the metal alloy is scratch resistant but still flexible,
thereby making it less likely to shatter compared to tungsten
carbide. Third, the metal alloy of the present invention is
machinable. The metal alloy is soft enough that designs can be more
elaborate and stones can be set directly in the metal. Fourth,
consumers are already familiar with tungsten and cobalt metal in
terms of jewelry and therefore, on a business side, using the metal
alloy of the present invention will be familiar.
[0058] In one embodiment, the present invention is directed to
providing a metal alloy that is castable (as opposed to being
limited to being produced by a MIM process) and machinable due to
the material properties of the metal alloy composition and provides
other advantageous properties such as being at least substantially
scratch resistant (yet retain some flexibility). This is in
contrast to conventional metal alloys, such as the ones described
herein.
[0059] While the invention has been described above and illustrated
with reference to certain embodiment of the invention, it is to be
understood that the invention is not so limited. Modifications and
alterations will occur to others upon reading and understanding of
the specification including the drawings.
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