U.S. patent application number 12/555644 was filed with the patent office on 2010-03-11 for white-colored copper alloy with reduced nickel content.
This patent application is currently assigned to PMX INDUSTRIES INC.. Invention is credited to CRAIG CLARK, THOMAS D. JOHNSON, RICHARD PRATT, TIMOTHY SUH.
Application Number | 20100061884 12/555644 |
Document ID | / |
Family ID | 41799480 |
Filed Date | 2010-03-11 |
United States Patent
Application |
20100061884 |
Kind Code |
A1 |
CLARK; CRAIG ; et
al. |
March 11, 2010 |
WHITE-COLORED COPPER ALLOY WITH REDUCED NICKEL CONTENT
Abstract
Disclosed is a white-colored copper alloy comprising by weight
up to 30% zinc, up to 20% manganese, up to 5% nickel with the
balance copper. This alloy may have from 6% to 25% zinc, from 4% to
17% manganese, from 0.1% to 3.5% nickel and the balance copper. The
balance copper in the alloy may further contain at least one of: up
to 0.5% of at least one of the group which consists of Sn, Si, Co,
Ti, Cr, Fe, Mg, Zr, and Ag; and up to 0.1% of at least one of the
group which consists of P, B, Ca, Ge, Se, Te. It may also contain
up to 0.3% Zr by weight. The alloy may have an electrical
conductivity greater than 2.5% IACS at eddy current gauge exciting
frequencies between 60 kHz and 480 kHz.
Inventors: |
CLARK; CRAIG; (HIAWATHA,
IA) ; JOHNSON; THOMAS D.; (CEDAR RAPIDS, IA) ;
PRATT; RICHARD; (MOUNT VERNON, IA) ; SUH;
TIMOTHY; (CEDAR RAPIDS, IA) |
Correspondence
Address: |
SIMMONS PERRINE MOYER BERGMAN PLC
CITY CENTER SQUARE, 1100 - 5th Street Suite 205
CORALVILLE
IA
52241
US
|
Assignee: |
PMX INDUSTRIES INC.
CEDAR RAPIDS
IA
|
Family ID: |
41799480 |
Appl. No.: |
12/555644 |
Filed: |
September 8, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61095719 |
Sep 10, 2008 |
|
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|
61095733 |
Sep 10, 2008 |
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Current U.S.
Class: |
420/472 ;
420/469; 420/473; 420/477; 420/479; 420/480; 420/481; 420/482;
420/485; 420/487; 420/493; 420/496 |
Current CPC
Class: |
C22C 9/04 20130101; C22C
9/05 20130101 |
Class at
Publication: |
420/472 ;
420/481; 420/473; 420/479; 420/469; 420/477; 420/487; 420/482;
420/480; 420/496; 420/493; 420/485 |
International
Class: |
C22C 9/04 20060101
C22C009/04; C22C 9/05 20060101 C22C009/05; C22C 9/06 20060101
C22C009/06 |
Claims
1) An effectively antimicrobial copper alloy with a visual
appearance similar to one of stainless steel and "nickel silver",
the copper alloy comprising: a) 6-25% zinc (Zn) b) 4-17% manganese
(Mn), c) 0.1-3.5% nickel (Ni), d) a balance of substantially Cu;
and e) the combination of a-d exhibiting a white visual appearance
and is effectively antimicrobial.
2) The copper alloy of claim 1 wherein the balance of substantially
Cu also contains up to at least one of: 0.5% of at least one of the
following group which consists of: Sn, Si, Co, Ti, Cr, Fe, Mg, Zr,
Ag; and up to 0.1% of at least one the following group which
consists of: P, B, Ca, Ge, Se, Te; and said alloy has a time to
complete inactivation of less than 60 minutes.
3) A copper alloy of white visual appearance similar to one of
stainless steel and "nickel silver" the copper alloy consisting
essentially of: a) 6-25% zinc (Zn), b) 4-17% manganese (Mn), c)
0.1-2.5% iron (Fe), d) a balance of substantially Cu e) wherein the
combination of a-d exhibits a white visual appearance and is
effectively antimicrobial.
4) The copper alloy of claim 3 wherein the balance of substantially
copper also contains at least one of: up to 0.5% of at least one of
the following group which consist of: Sn, Si, Co, Ti, Cr, Ni, Mg,
Zr, Ag, and up to 0.1% of at least one of the following group
consisting of: P, B, Ca, Ge, Se.
5) A copper alloy of white visual appearance similar to one of
stainless steel and "nickel silver"; the copper alloy consisting
essentially of: a) 6-25% zinc (Zn), b) 4-17% manganese (Mn), c)
0.1-5% nickel (Ni), d) 0.05-2.5% iron (Fe), and e) a balance of
substantially Cu; f) where the combination of a-e is effectively
antimicrobial and has a white visual appearance.
6) The copper alloy of claim 5 which also contains at least one of:
up to 0.5% of at least one of the following group which consists
of: Sn, Si, Co, Ti, Cr, Mg, Zr, Ag, and up to 0.1% of at least one
of the group consisting of: P, B, Ca, Ge, Se, Te.
7) The copper alloy of claim 1 which combination is resistant to
tarnishing on room temperature exposure in air and has a time to
complete inactivation of less than 60 minutes.
8) The copper alloy of claim 7 which contains 12-20% Zn, 10-17% Mn,
and 0.5-3.5% Ni
9) The copper alloy of claim 8 which contains 13-16% Zn, 14-17% Mn,
and 1.5-2.5% Ni, and wherein said time to complete inactivation is
less than 20 minutes.
10) copper alloy of claim 1 which contains up to 0.3% Zr by
weight.
11) The copper alloy of claim 3 which is effectively antimicrobial
and contains Ni only as an impurity.
12) The copper alloy of claim 11 which contains 12-20% Zn, 10-17%
Mn, and 0.5-2.5% Fe.
13) The copper alloy of claim 12 which contains 15-18% Zn, 14-17%
Mn, and 0.5-1.5% Fe.
14) The copper alloy of claim 5 which is resistant to elevated
temperature tarnishing.
15) The copper alloy of claim 14 which contains 12-20% Zn, 10-17%
Mn, 0.5-3.5% Ni and 0.1-1.0% Fe.
16) The copper alloy of claim 15 which contains 13-16% Zn, 14-17%
Mn, 1.5-2.5% Ni and 0.2-0.6% Fe.
17) The copper alloy of claim 14 which contains at least one of: up
to 1.0% Al; and and at least one of: up to 0.5% of at least one of
the following group consisting of: Sn, Si, Co, Ti, Cr, Mg, Zr, Ag,
and; up to 0.1% of at least one of the group consisting of: P, B,
Ca, Ge, Se, Te.
18) A copper alloy of white visual appearance and resistant to
touch tarnishing to be used for coinage applications as a direct
replacement for C713, the copper alloy comprising: a) 6-25% zinc
(Zn), b) 4-17% manganese (Mn), c) 0.1-9.0% nickel (Ni), d) a
balance of substantially Cu; and e) said combination of a-d having
a white visual appearance, is effectively antimicrobial and has an
electrical conductivity greater than 2.5% IACS at eddy current
gauge exciting frequencies between 60 kHz and 480 kHz.
19) The copper alloy of claim 18 wherein the balance of
substantially Cu also contains up to at least one of: 0.5% of at
least one of the following group which consists of: Sn, Si, Co, Ti,
Cr, Fe, Mg, Zr, Ag; and up to 0.1% of at least one the following
group which consists of: P, B, Ca, Ge, Se, Te.
20) The copper alloy of claim 19 wherein said electrical
conductivity is between 4% IACS and 7% IACS; and further having a
time to complete inactivation of less than 60 minutes.
21) The copper alloy of claim 19 containing up to 0.3% Zr by
weight; and the time to complete inactivation is less than 30
minutes.
22) The copper alloy of claim 21 containing 10-18% Zn, 4-7% Mn,
4-9% Ni and 0.05-0.20% Zr; and the time to complete inactivation is
less than 20 minutes.
23) The copper alloy of claim 22 which contains 12-16% Zn, 4-6% Mn,
5-9% Ni and 0.05-0.15% Zr; and the time to complete inactivation is
less than 15 minutes.
24) The copper alloy of claim 18 which has been formed into a
planchet.
Description
[0001] The invention claims the benefit of priority of U.S.
Provisional Patent Application No. 61/095,719, "WHITE-COLORED
COPPER ALLOY WITH REDUCED NICKEL CONTENT", filed on Sep. 10, 2008
and U.S. Provisional Patent No. 61/095,733 "IMPROVED WHITE-COLORED
COPPER ALLOY WITH REDUCED NICKEL CONTENT" filed on Sep. 10,
2008.
FIELD OF THE INVENTION
[0002] This invention relates to white- or silver-colored
copper-based alloys with reduced nickel content compared to
standard alloys of similar color.
BACKGROUND OF THE INVENTION
[0003] Copper base alloys are widely used for their combination of
ease of fabrication, corrosion resistance, electrical and thermal
conductivity, and availability in a wide range of attractive
colors. They are the preferred material worldwide for circulating
coinage, in many cases as part of multi-layer composite systems. In
addition, recent research has shown copper and copper alloy
surfaces can be manufactured to be antimicrobial, inactivating a
variety of microorganisms in a matter of two hours or less.
[0004] Even though copper by itself is red in color, addition of
most alloying elements results in more or less reddish or yellowish
colors. These colors are typically well known, with descriptive
names (brassy, golden, bronze, etc.). Alloys with a whiter color
(reflecting all light wavelengths more uniformly) are also
available, although it is generally difficult to achieve good white
colors without strong reddish or yellowish overtones, particularly
after the material has tarnished or partially oxidized. These
whiter alloys are generally achieved using large additions of
nickel (cupronickels and nickel silvers). Unfortunately, nickel is
more expensive than most other alloying elements, and has been
implicated as a major contributor to increased cases of allergic
contact dermatitis when used in contact with human skin and other
tissue. The intent of this invention is to provide copper alloys
with a good white color but using reduced nickel content.
[0005] Alloys consisting primarily of copper and nickel (with minor
additions of other elements) are known as cupronickels or
copper-nickels. As the nickel content increases, the color goes
from copper red toward a pale reddish/purple at 10% Ni (C706) to a
reasonably pure white at 25% Ni (C713). This white copper-nickel is
used extensively for US circulating coinage as the material for the
5-cent coin and as the outside of the three-layer composite for the
10-cent, 25-cent and 50-cent coins. While attractive and durable,
the alloy is expensive due to the high Ni content, since Ni is
typically over twice the price of copper. The high cost of C713 is
partially responsible for the use of composite coinage in the US;
by substituting a core of less expensive copper surrounded by the
silver-colored C713, the desired appearance can be achieved at
lower cost. Another alternative to the high cost of white
copper-nickels is to substitute zinc in the alloy for a portion of
the copper, forming the alloys known as "nickel silvers" for their
silvery color. Although less effective as a whitener for copper
alloys than nickel, Zn reduces the need for Ni and is both less
dense and less expensive than either Cu or Ni. Copper alloys of
high manganese content (20% and more) are also reliably white but
suffer from difficulties with hot working and very low electrical
and thermal conductivity, so they have been used primarily as
castings, where their lower melting point and increased fluidity
compared to "nickel silvers" is an advantage.
[0006] By substituting a combination of Zn and Mn for most of the
nickel in a white-colored copper alloy, a lower-cost alloy is
possible with a similar appearance and other novel properties.
While other white-colored copper base alloys superficially similar
to the proposed alloys have been disclosed in the past, none match
the composition range of this invention, as will be brought out
below.
[0007] Numerous copper-nickels and nickel silvers are offered by
various copper alloy producers with more or less white colors. Of
41 wrought copper-nickel alloys listed in the Copper Development
Association (CDA) database, only two (C71640 and C72420) have a Mn
content greater than 1%; neither of these alloys contains Zn
greater than 1%. Of 25 wrought nickel silvers (Cu--Zn--Ni alloys)
listed, only four have a minimum Mn content; all of these have Pb
added to improve machining properties. Copper-aluminum alloys
(aluminum bronzes) will contain either Zn or Mn, but not both.
There are only two wrought Cu--Zn--Mn alloys listed in the CDA
database, both nickel-free--C66900 and C66950. The first contains
0.25% max Fe (as an impurity) and 0.20% max other impurities with
no other additions. The second (Wieland Alloy FX9) contains 14-15%
Zn, 14-15% Mn, 1.0-1.5% Al, and the balance Cu.
[0008] Cast alloys listed in the CDA database show a similar trend;
alloys which contain more than 1% of both Mn and Zn also contain at
least 0.5% of Al. The one exception to this is an alloy known as
"Bronwite" (C99750), which contains 17-23% Mn, 17-23% Zn, and at
least 0.5% Pb with up to 5% Ni. Bronwite is very white, very fluid
and has a relatively low melting temperature which makes it
excellent for small, thin and delicate castings such as costume
jewelry, but it contains enough Pb to cause problems with current
Restrictions on Hazardous Substances (RoHS) and Consumer Product
Safety regulations.
[0009] A number of nickel-free white alloys have been disclosed in
the past. Wieland Alloy FX9 (C66950) has been mentioned above. YKK
Corporation of Tokyo, Japan holds a number of patents on
nickel-free alloys. U.S. Pat. No. 5,997,663 covers two ranges: 1)
70-85% Cu, 5-22% Zn, 7-15% Mn and 0-4% of Al or Sn or a combination
of both Al and Sn (with a white color); and 2) 70-85% Cu, 10-25%
Zn, 0-7% Mn, and 0-3% of Al or Sn or a combination of both Al and
Sn (with a distinctly yellow color). A second YKK patent (U.S. Pat.
No. 6,340,446) discloses nickel-free alloys containing 0.5-5% Zn,
7-17% Mn, 0.5-4% Al and the balance copper, which may also contain
one or more of Cr, Si, and/or Ti up to 0.3%. A third such patent
(EP1306453) teaches of Ni-free white alloys with 0.5-30% Zn and
1-7% Ti, optionally including up to 4% of a combination of one or
more of Al, Sn, Mg, and/or Mn.
[0010] Another European patent (EP0685564) discloses a Ni-free
alloy with generally lower copper (50-70% Cu) and higher Mn (8-25%
Mn) than the YKK patents with the remainder zinc. Most of these
previously disclosed Ni-free white alloys are intended to meet the
EU regulations restricting Ni in jewelry, eyeglasses, and similar
items in "direct and prolonged contact with human skin" (due to
issues with allergies and sensitization) by completely eliminating
Ni and are generally intended for use as cast articles or as wire
products.
[0011] An alloy disclosed in U.S. Pat. No. 6,432,556 (Brauer, et.
al) contains 5-10% Mn, 10-14% Zn, 3.5-4.5% Ni and less than 0.07%
Al with the balance Cu. The alloy content of U.S. Pat. No.
6,432,556 is specifically balanced so as to provide both a "golden
visual appearance" and an electrical conductivity suitable for use
as a replacement for standard alloy C713 (75 Cu-25 Ni) in both
monolithic and clad form for use in circulating US coinage,
particularly as a yellow alloy replacement for the Susan B. Anthony
(SBA) dollar coin, and is currently in use as the outer clad layers
of both the Sacajawea dollar and the US Presidential dollar series
of circulating coins. A related earlier patent (U.S. Pat. No.
2,445,868, to Berwick and assigned to Olin Inc.) which is referred
to in the application for U.S. Pat. No. 6,432,556 teaches about
quaternary (4-component) alloys of Cu--Zn--Ni--Mn type with 5% Ni
minimum and essentially no other additions.
[0012] Another substantially Ni-free alloy is disclosed in U.S.
Pat. No. 3,778,237 (Shapiro, et. al.) specifically as a substrate
for silver plated articles such as flatware or hollow ware for food
service. This alloy consists of 8-16% Mn, 20-31% Zn and the balance
Cu with small additions of other elements (Al, Fe, Sn, Si, Co, Mg,
Mo, Ni, P, As, Sb) permitted but not required. Nickel is permitted
up to 0.3% but preferably no Ni is added U.S. Pat. No. 3,778,236
(Goldman, et. al.) is a patent for an alloy containing 0.5-5% Ni,
also restricted as a substrate for silver-plated articles. Other
Ni-free Cu--Mn--Zn alloys are disclosed in U.S. Pat. No. 2,772,962
(Reichenecker, for a cast electrical-resistance alloy) and in U.S.
Pat. No. 2,479,596 (Anderson and Jillson, et. al.). U.S. Pat. Nos.
5,997,663, 6,340,446, 6,432,556, 2,445,868, 3,778,236, 3,778,237,
2,772,962 and European Patent Nos. EP1306453 and EP0685564 are
incorporated by reference in their entireties herein.
SUMMARY OF THE INVENTION
[0013] It is an object of at least one embodiment of the present
invention to provide a copper-based alloy with a white- or
silver-colored appearance and reduced nickel content compared to
traditional copper alloys of similar appearance. A further object
of at least one embodiment of the present invention is that the
alloys of the invention exhibit tarnish resistance at least equal
to other copper alloys of similar color. Yet a further object of at
least one embodiment of the present invention is that the alloys of
the invention exhibit resistance to staining (when subjected to
repeated touch by human skin) at least equal to other copper alloys
of similar color. A further object of at least one embodiment of
the present invention is that alloys of the invention exhibit
electrical conductivities substantially similar to those of
stainless steels or similar to those of alloys currently used for
circulating coinage. It is yet a further object of at least one
embodiment of the present invention that these alloys exhibit
antimicrobial properties such that bacteria exposed on the uncoated
surface of the alloy exhibit inactivation rates equal to or
superior to published data for copper-based alloys of similar color
and significantly superior to stainless steels of similar
color.
[0014] The above-stated objects, features and advantages will
become more apparent from the specifications and drawings which
follow. [0015] (1) It is a feature of at least one embodiment of
the present invention that the copper-base alloy claimed has a
white- or silver-colored appearance making it suitable for the
manufacture of decorative articles of various types, particularly
(but not limited to) architectural and builders' hardware. It
further may be used either in a monolithic form or as part of a
composite system with other materials where the color, tarnish
resistance and antimicrobial and other properties of the alloy of
the invention permit creation of novel material systems with
characteristics uniquely tailored to specific applications. [0016]
(2) Yet another feature of at least one embodiment of the present
invention is that the alloy contains both zinc and manganese and a
reduced level of nickel compared to traditional white-colored
copper-base alloys. [0017] (3) It is another feature of at least
one embodiment of the present invention that iron may be used in
place of or in addition to the nickel for improved color and [0018]
(4) tarnish resistance and [0019] (5) stain resistance compared to
alloys without either nickel or iron. [0020] (6) Another feature of
at least one embodiment of the present invention is that the alloy
has a white visual appearance and an electrical conductivity
similar to that of CDA Alloy C713 used in circulating US coinage.
[0021] (7) Yet another feature of at least one embodiment of the
present invention is that the alloy has an appearance similar to
that of stainless steel and also exhibits an electrical
conductivity in the same range as stainless steel.
[0022] Among the advantages of at least one embodiment of the
present invention is that the white-colored copper-base alloy of
the invention has antimicrobial properties. The inactivation rate
of bacteria placed on a surface composed of the alloy of at least
one embodiment of the present invention is superior to that of
other copper-based alloys of similar color, and is also superior to
what would be expected from the rates found with commercial binary
alloys of copper with components of the proposed alloy.
[0023] In accordance with the present invention there is provided a
white-colored copper alloy comprising by weight up to 30% zinc, up
to 20% manganese, up to 5% nickel with the balance copper. This
alloy more preferably contains from 6% to 25% zinc, from 4% to 17%
manganese, from 0.1% to 3.5% nickel and the balance copper. The
balance copper in the alloy may further contain at least one of: up
to 0.5% of at least one of the group which consists of Sn, Si, Co,
Ti, Cr, Fe, Mg, Zr, and Ag; and up to 0.1% of at least one of the
group which consists of P, B, Ca, Ge, Se, Te. This alloy preferably
contains from 12% to 20% Zn, from 10% to 17% Mn, and from 0.5% to
3.5% Ni. It more preferably contains from 13% to 16% Zn, from 14%
to 17% Mn, and from 1.5% to 2.5% Ni. It may also contain up to 0.3%
Zr by weight.
[0024] There is also provided, in accordance with the present
invention, a white-colored copper alloy comprising by weight up to
30% zinc, up to 20% manganese, up to 4% iron with the balance
copper. This alloy more preferably contains from 6% to 25% zinc,
from 4% to 17% manganese, from 0.1% to 2.5% iron and the balance
copper. The balance copper in the alloy may further contain at
least one of: up to 0.5% of at least one of the group which
consists of Sn, Si, Co, Ti, Cr, Ni, Mg, Zr, and Ag; and up to 0.1%
of at least one of the group which consists of P, B, Ca, Ge, Se,
Te. This alloy preferably contains Ni only as an impurity (that is,
less then about 0.1%), and consists of from 12% to 20% Zn, from 10%
to 17% Mn, and from 0.5% to 2.5% Fe. It more preferably contains
from 15% to 18% Zn, from 14% to 17% Mn, and from 0.5% to 1.5%
Fe.
[0025] There is further provided, in accordance with the present
invention, a white-colored copper alloy comprising by weight up to
30% zinc, up to 20% manganese, up to 6% nickel, up to 4% iron with
the balance copper. This alloy more preferably contains from 6% to
25% zinc, from 4% to 17% manganese, from 0.1% to 5% nickel, from
0.05% to 2.5% iron and the balance copper. The balance copper in
the alloy may further contain at least one of: up to 0.5% of at
least one of the group which consists of Sn, Si, Co, Ti, Cr, Mg,
Zr, and Ag; and up to 0.1% of at least one of the group which
consists of P, B, Ca, Ge, Se, Te. This alloy preferably contains
from 12% to 20% Zn, from 10% to 17% Mn, from 0.5% to 3.5% Ni, and
from 0.1% to 1% Fe. It more preferably contains from 13% to 16% Zn,
from 14% to 17% Mn, from 1.5% to 2.5% Ni, and from 0.2% to 0.6% Fe.
This alloy may further contain up to 1.0% Al.
[0026] There is yet further provided, in accordance with the
present invention, a white-colored copper alloy having an
electrical conductivity greater than 2.5% IACS at eddy current
gauge exciting frequencies between 60 kHz and 480 kHz comprising by
weight up to 30% zinc, up to 20% manganese, up to 10% nickel, up to
4% iron, up to 1% Zr with the balance copper. This alloy more
preferably contains from 6% to 25% zinc, from 4% to 17% manganese,
from 0.1% to 9% nickel, up to 2.5% iron, up to 0.5% Zr and the
balance copper. The balance copper in the alloy may further contain
at least one of: up to 0.5% of at least one of the group which
consists of Sn, Si, Co, Ti, Cr, Mg, and Ag; and up to 0.1% of at
least one of the group which consists of P, B, Ca, Ge, Se, Te. This
alloy preferably contains from 10% to 18% Zn, from 4% to 7% Mn,
from 4% to 9% Ni, and from 0.05% to 0.2% Zr. It more preferably
contains from 12% to 16% Zn, from 4% to 6% Mn, from 5% to 9% Ni,
and from 0.05% to 0.15% Zr; the combination having an electrical
conductivity between 4% IACS and 7% IACS.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 graphically illustrates the CIELAB color chart
attributes for lightness, hue and chroma as known from prior
art.
[0028] FIG. 2 shows the alloys of the invention plotted on a
2-dimensional CIELAB color chart illustrating the desired color
range, as well as comparative alloys.
[0029] FIG. 3 shows the same data as FIG. 2, but focusing on the
desired "white visual appearance" range.
[0030] FIG. 4 shows the antimicrobial effectiveness of alloys of
the invention.
DEFINITIONS
[0031] For purposes of the claims listed below, the following
definitions shall apply:
[0032] All compositions are given in percentages by weight. A
composition listed as Cu-18Zn-17Ni will mean a nominal 18% by
weight Zn, 17% by weight Ni and the remainder copper and inevitable
impurities. Other compositions listed in similar form can be
understood by analogy with this example.
[0033] "Copper-base alloy" shall hereafter be defined as: an alloy
having a minimum of 50% by weight Cu with one or more elemental
constituents, or a multi-component alloy where the percentage of Cu
is greater than that of any other constituent.
[0034] "White visual appearance" shall hereafter be defined as:
color (as measured with a spectrophotometer of d/8 sphere geometry
(specular reflection included) with a D65 illuminant and 10.degree.
observer) meets -2.ltoreq.a*.ltoreq.3 and -2.ltoreq.b*.ltoreq.10 on
the CIE 1976 L*a*b* (CIELAB) scale.
[0035] "Effectively antimicrobial" shall hereafter be defined as:
99.9% of bacteria in a suspension placed on an uncoated surface
will be inactivated within 120 minutes exposure
[0036] "Time to complete inactivation" shall hereafter be defined
as the time from placement of a bacteria on a surface until 99.9%
of the bacteria is inactivated.
[0037] "Resistant to tarnishing" shall hereafter be defined as:
after 30 days exposure in air at 20-25.degree. C. without contact
with human skin or body fluids, color change .DELTA.E.sub.CMC (as
defined in ASTM D2244-07, pp. 2-3) between initial color and final
color is less than 1.
[0038] "Resistant to elevated temperature tarnishing" shall
hereafter be defined as: after 24 hours exposure in air at
150.degree. C., color change .DELTA.E.sub.CMC (as defined in ASTM
D2244-07, pp. 2-3) between initial color and final color is less
than 20.
DETAILED DESCRIPTION
[0039] Determination of color (of alloys or other materials) may be
by spectroscopy or other objective means. Instruments such as those
supplied by X-Rite, Inc. (Grand Rapids, Mich.) or Hunter Associates
Laboratory, Inc. (Reston, Va.) quantify color according to two
chromatic attributes "hue" and "chroma" and a lightness attribute
known as "value". Hue is color perception, the recognition of an
object as red, green, yellow, blue, etc. Chroma is the color
concentration (intensity or saturation), ranging from gray to the
pure hue. Value is a measure of the lightness of the color tone,
ranging from pure white to pure black. A combination of these
values gives a unique location in color space in polar coordinates,
with hue denoting color tone (angular location), chroma denoting
intensity (radial location), and value denoting lightness (vertical
location) in FIG. 1.
[0040] An alternative method of specifying color is by the CIELAB
scale. CIE stands for Commission Internationale de l'Eclairage
(International Commission on Illumination) and LAB stands for the
L*, a*, b* coordinates of the scale; thus CIELAB is an abbreviation
for CIE 1976 L*a*b* color scale. On this scale, hue is expressed in
terms of color pairs, with +a* being red, -a* being green, +b*
being yellow, and b* being blue. Chroma (intensity or saturation)
is expressed as a value from the center of the coordinate system (0
being gray) to full intensity of the color component at .+-.60.
Higher values of any component mean more intense colors, while
lower values mean the material being measured is closer to
colorless. The lightness value L* ranges from 0 (pure black) to 100
(pure white). Once again, a specific combination of L*, a*, and b*
values identifies a unique location in color space and a specific
color, saturation, and brightness.
[0041] Colors of all alloys were analyzed using an SP-62
spectrophotometer manufactured by X-Rite Inc. (Grand Rapids,
Mich.). Analysis conditions were a d/8 sphere geometry (specular
reflection included) with a D65 illuminant and 10.degree. observer.
All color measurements are reported on the CIE 1976 L*a*b* (CIELAB)
scale. For initial color measurement, samples were prepared with
the same surface finish (6-18 Ra; a measure of surface roughness)
and cleaned to remove surface oxides, which can affect both initial
color measurement and subsequent analysis of atmospheric tarnishing
resistance. Chemistry and color of alloys according to the
invention are presented in Table 1 along with the same data for
comparative copper alloys and selected stainless steels. Alloys
according to the present invention are listed in the tables as I1,
I2, I3, etc. Comparative copper alloys are listed as C1, C2, C3,
etc. Comparative alloys which are not based on copper (carbon and
stainless steel, zinc and aluminum alloys, pure metals other than
copper, etc.) are listed as S1, S2, S3, and so forth.
[0042] Table 1. Chemistry and original (true metal) color
TABLE-US-00001 TABLE 1 Chemistry and Color Electrical Actual
Chemistry Color Conductivity at Alloy Cu Zn Mn Ni Fe Other L* a* b*
Visual 240 kHz (% IACS) C1 100 80.44 13.62 14.16 Red 100 C2 70 30
85.75 -1.44 21.74 Yellow 28.00 C3 77 12 7 4 80.41 2.30 10.27 Yellow
5.50 C4 88 10.5 1.5 79.96 3.65 8.18 Red 9.00 C5 75 0.5 24.5 78.79
1.00 5.26 White 5.60 C6 68.5 0.5 30 1 76.76 0.19 3.74 White 4.60 C7
71 11 18 79.30 0.84 6.74 White 6.80 C8 66 17 17 78.29 0.21 6.74
White 6.00 C9 91 6 3 82.03 7.49 13.99 Gold 13.25 C10 86 6 8 79.53
4.85 11.95 Gold 6.09 C11 82 6 12 79.48 3.04 9.09 Yellow 4.05 C12 78
6 16 78.61 1.99 6.95 White 3.05 C13 83 13 4 83.40 2.77 14.61 Yellow
10.34 C14 79 13 8 83.10 1.87 11.65 Yellow 5.60 C15 75 13 12 81.02
1.37 9.57 White 3.75 C16 71 14 15 80.70 0.88 7.13 White 2.82 C17 74
21 5 85.58 0.26 15.58 Yellow 9.31 C18 70 21 9 82.36 0.27 11.43
Yellow 5.17 C19 67 21 12 81.04 0.17 8.61 White 3.53 C20 63 21 16
80.24 0.15 6.66 White 2.72 C21 67 29 4 84.54 -0.64 17.59 Yellow
11.25 C22 63 29 8 83.36 -0.24 11.94 Yellow 5.10 C23 60 29 11 82.29
-0.19 10.52 Yellow 4.12 C24 56 28 16 82.78 -0.08 8.34 White 2.47
C25 88 6 4 2 77.37 5.63 12.19 Red 9.84 C26 69 15 15 1 Al 78.25 0.75
8.30 White 3.19 C28 97.8 2.2 80.67 11.05 12.06 Red 65.00 C29 85 15
84.19 4.36 19.14 Gold 37.00 C30 88 12 79.58 5.05 8.27 Red 4.15 C31
85 15 78.55 2.89 7.24 White 9.15 C32 90 10 81.54 6.44 17.58 Gold
44.00 I1 80 7 7 6 78.37 2.71 8.44 White 5.10 I2 74 9 14.5 2.5 78.49
1.53 6.92 White 3.10 I3 78.5 9 12 0.5 80.27 2.01 8.43 White 3.69 I4
76.5 9 12 2.5 78.39 1.82 7.69 White 3.61 I5 75.5 9 12.5 2.5 0.5
78.70 1.64 7.41 White 3.41 I6 75 8.5 11.5 2.5 2.5 78.79 1.65 7.28
White 3.26 I7 66 15 16 3 78.52 0.64 6.23 White 2.76 I8 66 17 16 1
79.09 0.49 6.98 White 2.96 I9 66 13 16 3 2 77.50 0.75 6.05 White
2.76 I10 77 14 4 3 2 80.16 2.07 11.65 Yellow 7.74 I11 53 25 17 3 2
77.76 0.09 5.32 White 2.52 S2 6.5 4 72 17 Cr, 77.18 0.30 4.64 White
2.50 0.25 N S3 7 76 17 Cr 75.89 0.40 4.83 White 2.50
[0043] One of the difficulties with creating a "white" copper-base
alloy is determining exactly what is meant by "white". Many of the
early applications for these alloys were as lower-cost alloys for
coinage, flatware, and hollowware, so the desired color was similar
to that of sterling and coin silver. More recently, "white" copper
alloys are being considered as replacements for stainless steel or
brushed nickel finishes in builder's hardware and architectural
applications, so that the antimicrobial properties of copper alloys
are available with similar appearance to the modern look of
stainless steel. A number of traditional "white" copper alloys were
analyzed for color, along with other alloys which exhibited slight
but distinct reddish or yellowish color overtones. Stainless and
carbon steel were also analyzed, along with pure nickel, zinc and
tin such as would be found on the surface of white-colored plated
products. These materials were compared to determine practical
limits on CIELAB values for white alloys. Materials with measured
values of both a* and b* close to zero appear nearly colorless and
thus whiter than those with higher values of either a* or b* at the
same overall lightness (L*) value. Lightness values (L*) for copper
alloys typically range from 75-86 for surfaces free of oxide and a
surface roughness of 6-18 Ra; this is true for all copper alloys
measured, from bright yellow cartridge brass (Alloy C2, Cu-30Zn) to
red pure copper (Alloy C1) to the strongly white copper-nickel used
in circulating US coinage (Alloy C5).
[0044] For purposes of determining the desired white color, the
upper limit of a* is hereafter defined at the point where the
visual appearance of the copper alloy is no longer primarily white
and first becomes white with a distinctly red hue. This transition
from white to red is defined by the a* value of Alloy C31
(Cu-15Ni). Alloy C31 has an a* value of 2.9. A comparable
commercially available copper alloy (Alloy C4, Cu-10Ni-1Fe) is
noticeably reddish and has an a* value of 3.7. For the purposes of
the present invention, it is proper to consider alloys with a*
values less than 3 and appropriate b* values (on the CIELAB scale)
to be white.
[0045] For copper alloys with a white visual appearance, the upper
limit of b* is defined at the point where the copper alloy is no
longer primarily white and first becomes distinctly yellow (or
white with a yellow hue). This transition from white to yellow is
defined by the b* value of comparative Alloy C3 (Cu-12Zn-7Mn-4Ni).
This is a patented alloy with a "golden visual appearance" (as
discussed in U.S. Pat. No. 6,432,556 B1 to Brauer et al.) and is
specifically formulated to exhibit a color closer to that of 18K
gold than to the white of Alloy C5 used for circulating US coinage;
this alloy has a measured b* value of 10.2. We set the upper limit
for b* at 10, so that only alloys less yellow than Alloy C3 are
acceptable.
[0046] Lower limits for a* and b* were set based on the color of
pure zinc (Alloy C35, a* -1.7, b* -1.9). Pure zinc subjectively
appears white, although faint bluish and greenish overtones are
visible on freshly cleaned and prepared surfaces. Therefore the
lower limits for a* and b* were both set at -2 in order to include
zinc in the white alloy zone. Copper alloys measured in our studies
all had CIELAB values a*>-1.5 and b*>1.5.
[0047] To be considered white the copper alloy must meet the
constraints listed above for both a* and b*; that is, a* is
preferably between about -2 and about +3, while b* is preferably
between about -2 and about +10. More preferably, a* is between
about -2 and about +2, while at the same time b* is between about
-2 and about +8. Most preferably, a* is between about -2 and about
+1 while at the same time b* is between about -2 and about +7.
Alloys meeting one or the other but not both are not considered
white. For example, Alloy C2 (Cu-30Zn) has CIELAB a*, b* values of
(-1.5, 21.5); although this falls within the a* range for white
(low redness), it exceeds the maximum allowable b* to be considered
white, therefore, Alloy C2 is a yellow copper alloy. A further
example is Alloy C4 (Cu-10Ni-1Fe), with CIELAB a*, b* values of
(3.7, 8.2); although the b* value is within the white range (low
yellowness) it exceeds the allowable a* value, and is visually
reddish. Moreover, ranges having endpoints within the ranges
discussed above are contemplated even if those endpoints or ranges
are not specially set forth. For example, the range of values for
a* may have a lower endpoint of -1.9, -1.8, -1.7, etc. through
+2.7, +2.8 and +2.9, while the upper endpoint may be +2.9, +2.8,
+2.7, etc. through -1.7, -1.8 and -1.9. Similar endpoints for the
values b* are also contemplated. Also, it also contemplated to
combine any of the ranges for a* with any of the ranges for b*. For
example, the range of values for a* may be -2 to +2, while the
range for the values of b* may be -2 and about +10.
[0048] The present invention includes alloys that are, by weight,
up to 30% zinc, up to 20% manganese, up to 5% nickel with the
balance copper. These alloys more preferably contains from 6% to
25% zinc, from 4% to 17% manganese, from 0.1% to 3.5% nickel and
the balance copper. The balance copper in the alloys may further
contain at least one of: up to 0.5% of at least one of the group
which consists of Sn, Si, Co, Ti, Cr, Fe, Mg, Zr, and Ag; and up to
0.1% of at least one of the group which consists of P, B, Ca, Ge,
Se, Te. These alloys preferably contain from 12% to 20% Zn, from
10% to 17% Mn, and from 0.5% to 3.5% Ni. It more preferably
contains from 13% to 16% Zn, from 14% to 17% Mn, and from 1.5% to
2.5% Ni. These alloys may also contain up to 0.3% Zr by weight. In
a most preferred embodiment, the alloys of the above compositions
are also white copper-based alloys; that is, they have CIELAB
values where a* is preferably between about -2 and about +3, while
b* is preferably between about -2 and about +10. More preferably,
a* is between about -2 and about +2, while at the same time b* is
between about -2 and about +8. Most preferably, a* is between about
-2 and about +1 while at the same time b* is between about -2 and
about +7. It is contemplated that composition discussed above may
be combined with each range of CIELAB values discussed above.
[0049] The present invention includes alloys that are, by weight,
up to 30% zinc, up to 20% manganese, up to 4% iron with the balance
copper. These alloys more preferably contains from 6% to 25% zinc,
from 4% to 17% manganese, from 0.1% to 2.5% iron and the balance
copper. The balance copper in the alloys may further contain at
least one of: up to 0.5% of at least one of the group which
consists of Sn, Si, Co, Ti, Cr, Ni, Mg, Zr, and Ag; and up to 0.1%
of at least one of the group which consists of P, B, Ca, Ge, Se,
Te. These alloys preferably contain Ni only as an impurity (that
is, less then about 0.1%), and has from 12% to 20% Zn, from 10% to
17% Mn, and from 0.5% to 2.5% Fe. These alloys more preferably
contain from 15% to 18% Zn, from 14% to 17% Mn, and from 0.5% to
1.5% Fe. In a most preferred embodiment, the alloys of the above
compositions are also white copper-based alloys; that is, they have
CIELAB values where a* is preferably between about -2 and about +3,
while b* is preferably between about -2 and about +10. More
preferably, a* is between about -2 and about +2, while at the same
time b* is between about -2 and about +8. Most preferably, a* is
between about -2 and about +1 while at the same time b* is between
about -2 and about +7. It is contemplated that composition
discussed above may be combined with each range of CIELAB values
discussed above.
[0050] The present invention includes alloys that are, by weight,
up to 30% zinc, up to 20% manganese, up to 6% nickel, up to 4% iron
with the balance copper. These alloys more preferably contain from
6% to 25% zinc, from 4% to 17% manganese, from 0.1% to 5% nickel,
from 0.05% to 2.5% iron and the balance copper. The balance copper
in the alloys may further contain at least one of: up to 0.5% of at
least one of the group which consists of Sn, Si, Co, Ti, Cr, Mg,
Zr, and Ag; and up to 0.1% of at least one of the group which
consists of P, B, Ca, Ge, Se, Te. These alloys preferably contain
from 12% to 20% Zn, from 10% to 17% Mn, from 0.5% to 3.5% Ni, and
from 0.1% to 1% Fe. These alloys more preferably contain from 13%
to 16% Zn, from 14% to 17% Mn, from 1.5% to 2.5% Ni, and from 0.2%
to 0.6% Fe. These alloys may further contain up to 1.0% Al. In a
most preferred embodiment, the alloys of the above compositions are
also white copper-based alloys; that is, they have CIELAB values
where a* is preferably between about -2 and about +3, while b* is
preferably between about -2 and about +10. More preferably, a* is
between about -2 and about +2, while at the same time b* is between
about -2 and about +8. Most preferably, a* is between about -2 and
about +1 while at the same time b* is between about -2 and about
+7. It is contemplated that composition discussed above may be
combined with each range of CIELAB values discussed above.
[0051] In another embodiment of the invention, the alloys have an
electrical conductivity greater than 2.5% IACS at eddy current
gauge exciting frequencies between 60 kHz and 480 kHz and that are,
by weight, up to 30% zinc, up to 20% manganese, up to 10% nickel,
up to 4% iron, up to 1% Zr with the balance copper. These alloys
more preferably contain from 6% to 25% zinc, from 4% to 17%
manganese, from 0.1% to 9% nickel, up to 2.5% iron, up to 0.5% Zr
and the balance copper. The balance copper in the alloys may
further contain at least one of: up to 0.5% of at least one of the
group which consists of Sn, Si, Co, Ti, Cr, Mg, and Ag; and up to
0.1% of at least one of the group which consists of P, B, Ca, Ge,
Se, Te. These alloys preferably contain from 10% to 18% Zn, from 4%
to 7% Mn, from 4% to 9% Ni, and from 0.05% to 0.2% Zr. The alloys
more preferably contains from 12% to 16% Zn, from 4% to 6% Mn, from
5% to 9% Ni, and from 0.05% to 0.15% Zr. In a more preferred
embodiment, each of the compositions discussed above also has an
electrical conductivity between 4% IACS and 7% IACS. In a most
preferred embodiment, the alloys of the above compositions are also
white copper-based alloys; that is, they have CIELAB values where
a* is preferably between about -2 and about +3, while b* is
preferably between about -2 and about +10. More preferably, a* is
between about -2 and about +2, while at the same time b* is between
about -2 and about +8. Most preferably, a* is between about -2 and
about +1 while at the same time b* is between about -2 and about
+7. It is contemplated that composition discussed above may be
combined with each range of CIELAB values discussed above as well
as combined with each of the electrical conductivity
characteristics discussed above.
[0052] Some specific examples of compositions contemplated include:
[0053] 1) 6-25% zinc, 4-17% manganese, 0.1-3.5% nickel and balance
Cu; and [0054] 2) Same as 1), with 0.5% of at least one of Sn, Si,
Co, Ti, Cr, Fe, Mg, Zr or Ag and up to 0.1% of P, B, Ca, Ge, Se or
Te. [0055] 3) Same as 1) or 2), with 0.1-2.5% iron. [0056] 4) Same
as 1) or 2), with 0.1-5% nickel and 0.05-2.5% iron. [0057] 5)
12-20% Zn, 10-17% Mn, and 0.5-3.5% Ni and balance Cu. [0058] 6)
13-16% Zn, 14-17% Mn, and 1.5-2.5% Ni and balance Cu. [0059] 7)
Same as 1) with up to 0.3% Zr. [0060] 8) 12-20% Zn, 10-17% Mn, and
0.5-2.5% Fe and balance Cu. [0061] 9) 15-18% Zn, 14-17% Mn, and
0.5-1.5% Fe and balance Cu. [0062] 10) 13-16% Zn, 14-17% Mn,
1.5-2.5% Ni and 0.2-0.6% Fe and balance Cu. [0063] 11) 6-25% zinc,
4-17% manganese, 0.1-9.0% nickel and balance Cu. [0064] 12) Same as
11) with up to 0.3% Zr. [0065] 13) 10-18% Zn, 4-7% Mn, 4-9% Ni,
0.05-0.20% Zr and balance Cu. [0066] 14) 12-16% Zn, 4-6% Mn, 5-9%
Ni, 0.05-0.15% Zr and balance Cu. [0067] All of these examples may
be combined with any combination of a* and b* values and any ranges
of electrical conductivity.
[0068] For all the components in the compositions, ranges having
endpoints within the ranges discussed above are also contemplated
even if those endpoints or ranges are not specially set forth. For
example, the range of values for Zn may have a lower endpoint of
6.1% 6.2%, 6.3%, etc. through 24.7%, 24.8% and 24.9%, while the
upper endpoint may be 24.9%, 24.8%, 24.7%, etc. through 6.3%, 6.2%
and 6.1%. Similar endpoints for the ranges of the other components
are also contemplated. Also, it also contemplated to combine any of
the specially set forth ranges for Zn with any of the specifically
set forth ranges for the other components. For example, ranges of
from 6% to 25% zinc may be combined with ranges of from 10% to 17%
Mn, and from 0.5% to 3.5% Ni.
[0069] A feature of the invention is that the alloys contain both
Zn and Mn and lower levels of Ni than traditional "white"
copper-based alloys. This results from synergistic effects of the
alloying elements, where a combination of multiple components gives
results not obtainable with simple binary alloys.
[0070] Nickel is a potent whitener in copper alloys. Addition of
10% Ni to Cu (Alloy C4) gives a pale alloy but still with a
reddish-purple tinge. Additions of 15% Ni (Alloy C31) or more give
distinctly white colors, and the alloys become more nearly
colorless as the Ni content increases to 30% (Alloy C6). Increased
Ni contributes to atmospheric tarnish resistance, inhibiting the
formation of dark copper oxides. Unfortunately, Ni is also
significantly more expensive than Cu (generally 2-3 times the
cost), so there is a strong economic advantage to producing alloys
similar in appearance but with less Ni. Higher additions of Ni also
decrease the antimicrobial effectiveness of the alloys, so Ni
should be held to a minimum consistent with the desired color and
tarnish resistance. Nickel has been implicated as the major factor
in metal-contact dermatitis, prompting the European Union to
legislate Ni-free alloys for jewelry, eyeglasses, and similar items
in "direct and prolonged contact with human skin" as seen in EP 0
635 564 B1 (Ammannati); "Copper-zinc-manganese alloy for the
production of articles coming into direct and prolonged contact
with the human skin"; Dec. 1, 2000; title, pg. 1-2.
[0071] Manganese is also an effective whitener in copper alloys,
although binary alloys have had little commercial significance due
to low strength, difficulties with ingot casting and hot rolling,
and low and inconsistent ductility related to short-range ordering.
Addition of 12% Mn or more to Cu give a relatively white alloy
(Alloy C30, [a*, b*]=[5.05, 8.27]), but this is the range where
short-range ordering becomes significant in binary alloys.
Manganese is commonly used for strengthening at low levels in more
complicated copper alloys containing Al, Zn, Si, Ni or combinations
of these. These low-level Mn additions can also improve casting and
hot rolling characteristics of these alloys.
[0072] Additions of Zn to copper alloys change the color strongly,
but the alloys do not become "white" or colorless; instead, Cu--Zn
alloys ("brasses") become golden to yellow as the content increases
to .about.30% Zn. Beyond 33% Zn, the alloys turn reddish again with
the formation of a new crystal structure. High Zn-brasses also
exhibit short-range ordering under certain conditions, which can
limit ductility and cause properties to change in service. Zinc can
reduce the need for Ni in whitening copper-base alloys (the basis
of the "nickel silver" Cu--Ni--Zn alloys). Appearance is close to
the white Cu--Ni alloys, with a slight admixture of yellow due to
the Zn content.
[0073] Iron additions to copper alloys are limited by low
solubility. There is a miscibility gap above 3.5% Fe, preventing
casting of higher-Fe alloys. Between 0.5% and 2.5%, Fe can be
retained in solid solution by suitable heat treatment, and it is
nearly as effective a whitener as Ni at the same levels. Fe can
also be a potent strengthener, forming precipitates both directly
and by reaction with P (phosphorus) in the alloy.
[0074] Zinc and aluminum are similar in copper alloys as far as
color is concerned, but Al is significantly more effective at
achieving golden-yellow colors. Addition of 6% Al (Alloy C32) gives
a similar color to Cu-15Zn (Alloy C29). Over time, Cu--Al alloys
(including those with other elements such as Zn, Mn and Fe) form
tight passive oxide films which are beneficial for tarnish and
corrosion resistance. This same effect reduces antimicrobial
effectiveness of alloys of Cu with Al, so Al should be held to a
minimum for antimicrobial applications. Hot- and cold-rolling and
heat treatment of Al-containing alloys is more complicated than
those without Al, due to interactions with many other alloying
elements.
[0075] One of the primary objects of the invention is to provide a
copper alloy of white visual appearance but with a reduced Ni
content. The above description of the effects of alloying additions
on the color of copper-base alloys point to methods for achieving
this goal. By substituting Zn for a portion of the Ni, alloys of
reduced Ni content can be created although the color tends to
become yellower than Cu--Ni alloys of the same total Cu content. By
further substituting Mn for some of the remaining Ni, alloys with
much lower Ni content are possible with substantially white
(colorless) appearance. We have found that retention of a low level
of Ni (at a particular total alloy content) helps maintain the
desired white color and also has benefits in terms of atmospheric
tarnish resistance and in decreasing staining due to contact with
fluids from human skin. Thus, copper alloys of white visual
appearance are found by substituting a combination of Zn and Mn for
Ni in traditional alloys, along with maintaining a low level of Ni
for improved color and tarnish resistance.
[0076] Another feature of the invention is that Fe may be used in
place of Ni or in addition to Ni to improve the whiteness of
Cu--Zn--Mn alloys. When measuring the color of commercial Cu--Ni
alloys, we found that the whiteness of some of these alloys was
better than expected from the Ni content alone. The alloys in
question were found to contain significant amounts of Fe, added to
improve casting and hot- and cold-working properties in these
alloys. Further investigation of Cu--Fe alloys showed that while
they are still distinctly red due to the low overall alloy content,
they are closer to white (with a lower a* value on the CIELAB
scale) than expected for Cu--Zn or Cu--Mn of the same alloy
content. Based on this, we added up to 2.5% Fe to alloys of the
invention and found that the improved whiteness carried through
even at total alloy content over 30%. Further, we found that the
presence of Ni did not interfere with the effect of Fe so either or
both may be used to improve the whiteness of Cu--Zn--Mn alloys. We
also found that the presence of Fe in solid solution in the alloy
(at a particular total alloy content) helps maintain the desired
white color and also has benefits in terms of atmospheric tarnish
resistance and in decreasing staining due to contact with fluids
from human skin, similarly to the effects of low levels of Ni on
these properties. These effects are also found when Fe or a
combination of Fe and Ni are used in place of Ni alone. Thus,
copper alloys of white visual appearance are found by substituting
a combination of Zn and Mn for Ni in traditional alloys, along with
maintaining a low level of Ni or Fe or a combination of both Ni and
Fe for improved color and tarnish resistance.
[0077] An important factor in selection of copper-base alloys for
appearance (such as architectural and builder's hardware) is the
stability of the appearance over time. Stainless steels do not
change appearance significantly when exposed to the atmosphere;
this is due to formation of passive oxide layers preventing visible
tarnish and corrosion and is why they are considered "stainless".
Unfortunately, stainless steels are not available in the wide range
of colors and tones that can be achieved with copper-base alloys,
nor do stainless steels possess the antimicrobial characteristics
of properly prepared copper alloys. Traditionally, Ni is added to
copper alloys for improved resistance to atmospheric tarnishing, as
Ni forms a passive oxide layer at the surface similar in function
to the passive surface of stainless steels. We have found that it
is possible to tailor the chemical composition of white copper
alloys with reduced Ni content to give alloys with a desirable
white appearance and resistance to atmospheric tarnishing
substantially the same as traditional higher-Ni white copper-base
alloys.
[0078] Tarnishing in copper alloys is the result of the formation
of oxide films over time by reaction with oxygen from the
atmosphere. It generally shows up as a darkening of the surface,
although the different colors of the oxides formed from the base
material (as well as interference-layer effects) can also introduce
differences in hue and chroma compared to the original appearance
of the material. By comparing colors before and after exposure, the
magnitude of tarnishing can be quantified and objective comparisons
made between different alloys.
[0079] Color differences between samples with measured CIELAB
values are readily calculated; a variety of color-difference and
color-tolerance equations are given in ASTM Standard
D2244-07.sup..epsilon.1 "Standard Practice for Calculation of Color
Tolerances and Color Differences from Instrumentally Measured Color
Coordinates"; ASTM International; May 1, 2007. The total color
difference .DELTA.E*.sub.ab between two colors each given in terms
of L*, a*, b* can be calculated as:
.DELTA.E*.sub.ab=[(.DELTA.L*).sup.2+(.DELTA.a*).sup.2+(.DELTA.b*).sup.2]-
.sup.1/2
[0080] .DELTA.E.sup.*.sub.ab provides the magnitude of the color
difference but gives no indication of the character of the
difference since it does not indicate the relative quantity and
direction of hue, chroma, and lightness differences. (ASTM Standard
D2244-07.sup..epsilon.1, Section 6.2.2). It is most useful when the
color change is dominated by one of the three factors and the
nature of the color change is easily understood but less useful
when two or three components are significant contributors to the
measured color change. It is also possible to transform the L*, a*,
b* rectangular coordinates into L*, C*, H* cylindrical coordinates
to better understand the relative differences in lightness L*,
chroma C* and hue H*. The equivalent total color difference
equation is then:
.DELTA.E*.sub.ab=[(.DELTA.L*).sup.2+(.DELTA.C*).sup.2+(.DELTA.H*).sup.2]-
.sup.1/2
[0081] An alternate calculated color difference .DELTA.E.sub.CMC
(as defined by the Colour Measurement Committee (CMC) of the
Society of Dyers and Colourists in England) is intended to be used
as a single-number shade-passing equation (also defined in ASTM
D2244-07.sup..epsilon.1). It was developed as a tolerancing system
based on CIELCH cylindrical coordinates and defines ellipsoids
around a standard color (specific point in color space) within
which the difference from the standard is acceptable for the
intended application. The color difference .DELTA.E.sub.CMC is
given by:
.DELTA.E*.sub.CMC=cf[(.DELTA.L*/(lS.sub.L)).sup.2+(.DELTA.C*(cS.sub.C)).-
sup.2+(.DELTA.H*/(S.sub.H))).sup.2].sup.1/2
[0082] Parameters in the equation account for differences in
spectral sensitivity and relative importance of the lightness
versus chroma and hue, so that there is better agreement between
numeric tolerances and the actual range of colors visually
acceptable to human perception. In particular, the commercial
factor cf can be varied to match the desired range for a given
application. A .DELTA.E.sub.cmc=1 is assumed to represent a just
perceptible difference in color.
[0083] For purposes of comparing resistance to color change due to
atmospheric exposure, .DELTA.E.sub.CMC was calculated based on the
actual color difference between the samples before exposure
(time=0) and after exposure at a given time and temperature. Lower
values of .DELTA.E.sub.CMC (less color change due to exposure) are
considered a measure of superior atmospheric tarnish
resistance.
[0084] Table 2: Atmospheric Tarnishing Table--Room Temperature
TABLE-US-00002 TABLE 2 Atmospheric Tarnishing - Room Temperature
Initial Color 15 Days 30 Days Alloy L* a* b* .DELTA.E*.sub.ab
.DELTA.E.sub.cmc .DELTA.E*.sub.ab .DELTA.E.sub.cmc C3 80.41 2.30
10.27 1.04 0.69 1.25 0.80 C4 79.96 3.65 8.18 1.02 0.56 1.33 0.76 C5
78.79 1.00 5.26 0.43 0.27 0.51 0.37 C6 76.76 0.19 3.74 0.32 0.32
0.43 0.45 C7 79.30 0.84 6.74 0.84 0.48 0.93 0.58 C8 78.29 0.21 6.74
0.48 0.29 0.46 0.31 C11 79.48 3.04 9.09 0.77 0.52 1.30 1.05 C12
78.61 1.99 6.95 1.27 0.71 2.32 1.44 C14 83.10 1.87 11.65 2.08 0.99
2.32 1.11 C15 81.02 1.37 9.57 0.78 0.57 1.95 1.31 C16 80.70 0.88
7.13 1.01 0.50 1.15 0.72 C17 85.58 0.26 15.58 2.75 1.35 3.09 1.54
C19 81.04 0.17 8.61 0.86 0.66 0.92 0.72 C20 80.24 0.15 6.66 0.88
0.74 1.45 1.04 C23 82.29 -0.19 10.52 0.94 0.75 1.05 0.87 C24 82.78
-0.08 8.34 0.59 0.53 0.80 0.71 C26 78.25 0.75 8.30 0.84 0.73 0.90
0.83 I1 78.37 2.71 8.44 0.45 0.34 0.66 0.48 I2 78.49 1.53 6.92 0.80
0.72 0.91 0.85 I3 80.27 2.01 8.43 0.81 0.56 0.85 0.63 I4 78.39 1.82
7.69 0.45 0.41 0.53 0.48 I5 78.70 1.64 7.41 0.60 0.46 0.71 0.52 I6
78.79 1.65 7.28 0.67 0.45 0.72 0.54 I7 78.52 0.64 6.23 0.57 0.58
0.76 0.73 I8 79.09 0.49 6.98 0.68 0.66 0.88 0.79 I9 77.50 0.75 6.05
0.86 0.76 0.97 0.83 S2 77.18 0.30 4.64 0.39 0.16 0.51 0.22 S3 75.89
0.40 4.83 0.27 0.15 0.21 0.14
[0085] Color change due to atmospheric tarnishing is given in Table
2. After 30 days at room temperature, many of the nickel-free
comparative alloys (Alloys C11-C24) show .DELTA.E.sub.CMC>1.
Nickel-containing comparative alloys C3-C8 (with Ni content >4%)
all show less color change, with .DELTA.E.sub.CMC<1. Alloys of
the invention (Alloys I1-I9) also show .DELTA.E.sub.CMC<1, even
with Ni <3.5%. Comparing Alloy C16 with Alloy I8, it is expected
that one would see that adding 1% Fe (to a color-balanced
Cu--Zn--Mn alloy) may not decrease tarnish resistance and may move
the visual appearance closer to colorless. Similarly comparing
Alloy I7 to Alloy C16, it is expected that one would see that
addition of 3% Ni also may give a whiter alloy and significantly
improves tarnish resistance. Addition of both Ni and Fe (Alloy I9)
is expected to show that the color and tarnishing benefits of both
elements are independent and may not interfere with each other.
TABLE-US-00003 TABLE 3 Atmospheric Tarnishing - Elevated
Temperature 150.degree. C. for Initial Color 7 Hours 150.degree. C.
for 24 Hours Alloy L* a* b* .DELTA.E*.sub.ab .DELTA.E.sub.cmc
.DELTA.E*.sub.ab .DELTA.E.sub.cmc C3 80.41 2.30 10.27 18.2 12.4
20.9 14.4 C4 79.96 3.65 8.18 52.4 31.5 46.9 40.3 C5 78.79 1.00 5.26
16.7 14.9 30.3 26.7 C6 76.76 0.19 3.74 13.2 13.3 21.1 23.0 C7 79.30
0.84 6.74 19.4 15.3 29.6 22.9 C8 78.29 0.21 6.74 16.9 14.2 16.9
14.2 C11 79.48 3.04 9.09 18.3 13.8 28.5 21.5 C14 83.10 1.87 11.65
20.8 13.9 28.1 19.1 C16 80.70 0.88 7.13 13.4 11.5 17.6 15.6 C26
78.25 0.75 8.30 12.9 10.5 16.6 13.9 I2 78.49 1.53 6.92 12.4 10.8
15.9 14.0 I3 80.27 2.01 8.43 15.1 12.2 21.2 17.5 I4 78.39 1.82 7.69
13.3 10.9 16.8 12.7 I5 78.70 1.64 7.41 13.0 11.0 19.1 16.1 I6 78.79
1.65 7.28 13.0 10.9 18.0 15.1 I7 78.52 0.64 6.23 6.6 5.4 9.3 9.1 I8
79.09 0.49 6.98 9.1 8.4 12.7 11.9 I9 77.50 0.75 6.05 8.0 7.4 10.4
9.9 S2 77.18 0.30 4.64 3.1 2.9 4.0 3.8 S3 75.89 0.40 4.83 2.5 2.4
3.0 2.8
[0086] Elevated temperatures are often used to simulate longer-term
exposures for purposes of oxidation or corrosion studies. It is
important to select temperature-time regimes where the nature of
the oxides or corrosion products is the same as under the
conditions being simulated. For example, at moderately elevated
temperatures in air (200.degree. C. and above), the direct
formation of black CuO is preferred over red Cu.sub.2O which later
transforms to CuO; this affects the nature of the color change
during atmospheric tarnishing in terms of all three components
(hue, chroma, and lightness). These exposures also indicate how
materials will respond when used at moderately elevated
temperatures (such as panels on kitchen appliances) or when
subjected to automatic dishwashing or autoclave sterilization
cycles.
[0087] Color change due to elevated-temperature atmospheric
exposure is shown in Table 3. Alloy samples (also called coupons)
were cleaned and prepared by the same procedure as other color
samples and the CIELAB color measured before exposure. Color was
reevaluated after exposure and .DELTA.E.sub.CMC calculated. After
furnace treatment at 150.degree. C. for either 7 or 24 hours, the
alloys of the invention (Alloys I2-I9) showed the same or less
color change as any of the comparative copper alloys listed in
Table 3 (Alloys C3-C26). The preferred embodiments of the invention
(Alloys I7-I9) showed the least color change of any copper alloy
listed. Of particular interest is a comparison between Alloy C16
and these preferred embodiments. Alloy C16 is essentially the same
as these embodiments, but without either Ni or Fe; after 24 hours
at 150.degree. C., color change .DELTA.E.sub.CMC=15.6. For the same
alloy with 1% Fe (Alloy I8), .DELTA.E.sub.CMC=11.9, illustrating
that addition of Fe not only improved whiteness of the alloy but
enhanced tarnish resistance as well. The same is true (but more so)
for Alloys I7 and I9 (.DELTA.E.sub.CMC=9.1-9.9); addition of Ni (or
Ni plus Fe) to the basic Cu--Zn--Mn alloy dramatically improved
tarnish resistance as well as whiteness of the alloy.
[0088] Touch surfaces (handrails, door hardware, countertops,
appliance panels, hospital equipment, etc.) are in repeated contact
with films of water, sweat, sebum, and other body fluids as part of
their function. These body fluids contain complex mixtures of
substances, many of which are noticeably corrosive to copper and
copper alloys. An evaluation of how the appearance of these alloys
changes after repeated contact with human skin is important not
only in selection of these alloys for touch surface applications
but also useful to determine the frequency of cleaning necessary to
maintain their appearance. From a functional standpoint, cleaning
and sanitizing cycles ranging from once per week to multiple times
each day are recommended for stainless steel and similar hospital
surfaces to minimize cross-contamination in healthcare
situations.
TABLE-US-00004 TABLE 4 Touch Tarnishing - Room Temperature Initial
Color 3 Days 7 Days Alloy L* a* b* .DELTA.E*.sub.ab
.DELTA.E.sub.cmc .DELTA.E*.sub.ab .DELTA.E.sub.cmc C3 80.41 2.30
10.27 6.92 3.70 8.79 4.37 C4 79.96 3.65 8.18 3.49 2.00 7.05 3.35 C5
78.79 1.00 5.26 1.93 1.68 4.55 2.88 C6 76.76 0.19 3.74 3.05 1.77
6.25 2.90 C7 79.30 0.84 6.74 4.49 2.46 6.45 3.60 C8 78.29 0.21 6.74
5.31 2.83 6.27 3.38 C11 79.48 3.04 9.09 4.80 2.74 6.96 3.93 C12
78.61 1.99 6.95 2.51 1.69 5.63 3.38 C14 83.10 1.87 11.65 3.17 1.86
9.90 4.78 C15 81.02 1.37 9.57 4.02 2.30 5.58 3.35 C16 80.70 0.88
7.13 4.22 2.56 5.85 3.30 C17 85.58 0.26 15.58 4.98 2.62 9.74 4.85
C19 81.04 0.17 8.61 2.14 1.87 6.13 4.04 C20 80.24 0.15 6.66 1.52
1.24 5.47 3.23 C23 82.29 -0.19 10.52 1.39 0.89 7.68 4.12 C24 82.78
-0.08 8.34 1.09 0.76 7.47 4.40 C26 78.25 0.75 8.30 2.62 1.66 4.75
3.03 I1 78.37 2.71 8.44 3.22 1.99 7.91 4.18 I2 78.49 1.53 6.92 4.26
2.68 6.72 3.72 I3 80.27 2.01 8.43 3.01 1.80 7.56 4.54 I4 78.39 1.82
7.69 2.75 1.84 6.72 4.49 I5 78.70 1.64 7.41 2.27 1.54 4.91 3.28 I6
78.79 1.65 7.28 1.20 0.91 3.33 2.34 I7 78.52 0.64 6.23 1.72 1.16
2.93 1.90 I8 79.09 0.49 6.98 3.70 2.24 5.67 3.50 I9 77.50 0.75 6.05
2.03 1.37 3.18 2.06 S2 77.18 0.30 4.64 0.46 0.48 2.19 1.67 S3 75.89
0.40 4.83 2.29 1.67 3.93 2.75
[0089] Coupons of the alloys of interest were cleaned and prepared
with the desired surface finish (6-18 Ra). Initial color was
determined before any contact with human skin and/or fluids. The
coupons were contacted daily, and the change in color determined
and calculated for comparison. Results are given in Table 4. After
three days of repeated skin contact, all white alloys showed little
difference in stain resistance; .DELTA.E.sub.CMC was 1.2-2.8. There
did not seem to be any strong correlation with content of any
particular alloying element or combination of elements. After seven
days of repeated exposure, the differences between alloys were even
less although total color change was greater; .DELTA.E.sub.CMC was
2.9-4.4. Alloys of the invention were no worse than conventional
alloys in terms of resistance to color change due to contact with
human skin and/or body fluids, even though content of Ni and/or Fe
was significantly lower than the Ni content of conventional white
copper-base alloys.
[0090] Many of the applications for copper-based alloys involve
conduction of electricity or resistance to such conduction. For
example, controlled electrical conductivity or resistivity is used
as a security feature in discriminating between legal circulating
coinage or tokens and invalid "slugs", where a particular
combination of color and electrical properties are desired. It is
also used to control the activity of electrical equipment such as
fuses and circuit breakers. Conductivity is controlled primarily by
alloy content; addition of different alloying elements to pure
copper (with 100% IACS conductivity) will cause more or less
reduction in the conductivity. Conductivity of comparative alloys
as well as alloys according to the invention is listed in Table
1.
[0091] Comparing Alloy C29 (Cu-15Zn, 37% IACS), Alloy C31 (Cu-15Ni,
9.15% IACS) and Alloy C30 (Cu-12Mn, 4.15% IACS), we see that
various alloying elements have different effects on electrical
conductivity. Taking advantage of this, it is possible to design
alloys for a specific conductivity while maintaining a particular
visual appearance. Alloy I1 has a white visual appearance and
electrical conductivity (5.1% IACS) similar to that of Alloy C5 but
it contains only 6% Ni compared to the 24.5% Ni in C5, which could
result in a significant cost savings if substituted in circulating
US coinage.
[0092] Among the advantages of the invention is that the
white-colored copper-base alloy of the invention has antimicrobial
properties. Copper and many copper-base alloys, when properly
prepared, decrease the viability of bacteria and other
microorganisms exposed on surfaces of these alloys. The
effectiveness of the alloy surface at inactivating bacteria is
related to alloy chemistry as well as other factors, such as
surface roughness as demonstrated in PCT Application _PCT/US
2007/069413. The exposure time necessary to inactivate 99.9% of
bacteria on the surface is a useful measure of the antimicrobial
properties of the alloys under consideration, and a test procedure
based on that in the November 2003 study sponsored by the Copper
Development Association (Wilks, et. al) was used for comparison
with their published values.
[0093] Coupons (-22 mm square) of the alloys of interest were
prepared and sterilized prior to exposure. The prepared coupons
were placed in Petri dishes on sterilized filter paper. A 5-20
.mu.l aliquot of a suspension of active bacterial culture (E. Coli,
American Type Culture Collection [ATCC] strain 11229,
Gram-negative) in nutrient broth was applied onto the surface of
the coupon; this inoculum contained a minimum of 10.sup.6-10.sup.8
colony-forming units per milliliter (CFU/ml). After the desired
exposure time, the coupons were placed in tubes containing 20 ml of
sterilized Butterfield's buffer (3.1.times.10.sup.-4M
K.sub.2HPO.sub.4 in filtered deionized/reverse osmosis
laboratory-grade water) and ultrasonically agitated for 5 minutes
to suspend any surviving bacterial colonies from the surface of the
coupons. The suspension of surviving bacterial colonies was
serially diluted four times ( 1/10, 1/100, 1/1000, and 1/10000). A
20 .mu.l aliquot of this original suspension and of each dilution
was plated onto nutrient agar and incubated at 35-37.degree. C. for
48 hours to count the surviving colonies. To check the baseline
(the number of colonies in the original inoculum exposed on the
coupons), a 20 .mu.l aliquot of the original inoculum was placed
into a tube containing 20 ml of sterile buffer directly without
exposure on a metal coupon and this was then treated in identical
fashion to the suspension of survivors from the coupons
(ultrasonically agitated, diluted, placed on agar plates and
incubated before counting). Duplicate coupons were exposed and the
dilutions plated in duplicate to average out statistical variation
common in biological testing. The number of colonies present on
each agar plate was counted and the number of colony-forming units
(CFU) per ml in the original baseline and the suspension from the
exposed coupons calculated, accounting for all dilutions. Only
plates exhibiting between 5 and 400 colonies were used for the
final calculations, in order to minimize statistical variability.
The exposure time required to achieve a 99.9% reduction in bacteria
count (3 log.sub.10 reduction in CFU) and time to complete
inactivation are the primary measures of antimicrobial
effectiveness.
[0094] Results of antimicrobial testing of alloys of the invention
challenged with E. Coli are presented in Table 5 and FIG. 4.
Published information on commercial alloys challenged with E. Coli
(from Wilks and Keevil) is included below for comparison.
TABLE-US-00005 TABLE 5 Antimicrobial Effectiveness of Copper Alloys
Equivalent Alloy Time to Sample ID (from Table Time to Complete
(Wilks and Keevil) 1) 99.9% Reduction Inactivation 110 CDA C1 75-90
90 220 CDA C32 90-105 105 260 CDA C2 90-105 120 706 CDA C4 90-105
105 713 CDA C5 90-105 120 752 CDA C8 90-105 105 Y90 CDA C3 90 120
I1 45-60 60 I2 45-60 60
[0095] Comparative Alloy C32 (Cu-10Zn) shows a 99.9% reduction in
bacteria count after exposures between 90 and 105 minutes and
complete inactivation after 105 minutes. Alloy C4 (Cu-10Ni-1Fe) has
essentially the same effectiveness as Alloy C32. Similar alloys
with higher alloy content (C2 [Cu-30Zn] and C5 [Cu-25Ni-0.5Fe])
show slightly less effectiveness, with 99.9% reduction between 90
and 105 minutes and complete inactivation only after 120 minutes.
Alloy C8 (Cu-17Zn-18Ni) is intermediate in chemistry between these
alloys and shows intermediate antimicrobial effectiveness, just
slightly less than C22000 Alloy C32 and Alloy C4. A commercial
coinage alloy (Y90 from Olin Brass, Comparative Alloy C3,
Cu-12Zn-4Ni-7Mn) also contains Mn like the alloys of the invention,
but is balanced to have a "golden visual appearance" rather than
the substantially white color of the invention. Antimicrobial
effectiveness of C3 is slightly better than alloys without Mn, with
99.9% reduction near 90 minutes exposure and complete inactivation
after 120 minutes. Alloy C1 (commercially pure copper) shows a
99.9% reduction in bacteria count after exposures between 75 and 90
minutes, with complete inactivation after 90 minutes.
[0096] Based on these published results, we expected antimicrobial
effectiveness of the alloys of the invention to be similar to that
of Alloy C3 (Y90). The zinc is somewhat higher (making for longer
times, from a comparison of Alloy C32 and Alloy C2) and the nickel
is slightly lower (shorter times, comparing Alloy C4 and C5).
Comparing Alloy C8 and C3, the Mn did not seem to have a strong
effect on antimicrobial effectiveness, although there was a more
gradual and earlier drop in bacterial count rather than the sharp
drop seen with most alloys. Unexpectedly, initial testing showed
99.9% reduction in CFU counts between 45 and 60 minutes (40% faster
than other alloys) and complete inactivation after 60 minutes
(40-50% faster). Subsequent testing showed a 99.9% reduction at
times as short as 10 minutes or less and complete inactivation
between 15 and 30 minutes, and similar results for the same alloys
challenged with the Gram-positive bacteria Staph. Aureus [ATCC
6538] using the same sample preparation and procedures. The
mechanism responsible for the increased kill rates in our modified
higher-Mn alloys is unclear, although it seems to be related to
suppression of passivating oxide layers present on alloys of Cu
with Zn and Ni.
[0097] It is apparent that there has been provided in accordance
with this invention a copper alloy which fully satisfies the
objects, features, and advantages of the invention as set forth
herein. While the invention has been described in combination with
specific embodiments thereof, it is evident that there are many
alternatives, modifications and variations based on these
descriptions which will be apparent to those skilled in the art.
Accordingly, this invention is intended to embrace all such
alternatives, modifications and variations as fall within the broad
spirit and scope of the appended claims, and not be restricted to
the specific examples set forth herein.
[0098] It will be further appreciated that functions or structures
of a plurality of components or steps may be combined into a single
component or step, or the functions or structures of one-step or
component may be split among plural steps or components. The
present invention contemplates all of these combinations. Unless
stated otherwise, dimensions and geometries of the various
structures depicted herein are not intended to be restrictive of
the invention, and other dimensions or geometries are possible.
Plural structural components or steps can be provided by a single
integrated structure or step. Alternatively, a single integrated
structure or step might be divided into separate plural components
or steps. In addition, while a feature of the present invention may
have been described in the context of only one of the illustrated
embodiments, such feature may be combined with one or more other
features of other embodiments, for any given application. It will
also be appreciated from the above that the fabrication of the
unique structures herein and the operation thereof also constitute
methods in accordance with the present invention. The present
invention also encompasses intermediate and end products resulting
from the practice of the methods herein. The use of "comprising" or
"including" also contemplates embodiments that "consist essentially
of" or "consist of" the recited feature.
[0099] The explanations and illustrations presented herein are
intended to acquaint others skilled in the art with the invention,
its principles, and its practical application. Those skilled in the
art may adapt and apply the invention in its numerous forms, as may
be best suited to the requirements of a particular use.
Accordingly, the specific embodiments of the present invention as
set forth are not intended as being exhaustive or limiting of the
invention. The scope of the invention should, therefore, be
determined not with reference to the above description, but should
instead be determined with reference to the appended claims, along
with the full scope of equivalents to which such claims are
entitled. The disclosures of all articles and references, including
patent applications and publications, are incorporated by reference
for all purposes.
* * * * *