EP2384372A2 - Alliage de cuivre de couleur blanche avec une teneur en nickel réduite - Google Patents

Alliage de cuivre de couleur blanche avec une teneur en nickel réduite

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Publication number
EP2384372A2
EP2384372A2 EP09813496A EP09813496A EP2384372A2 EP 2384372 A2 EP2384372 A2 EP 2384372A2 EP 09813496 A EP09813496 A EP 09813496A EP 09813496 A EP09813496 A EP 09813496A EP 2384372 A2 EP2384372 A2 EP 2384372A2
Authority
EP
European Patent Office
Prior art keywords
alloys
copper alloy
alloy
copper
white
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP09813496A
Other languages
German (de)
English (en)
Other versions
EP2384372A4 (fr
Inventor
Craig Clark
Richard Pratt
Thomas D. Johnson
Timothy Suh
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
PMX Industries Inc
PMX Ind Inc
Original Assignee
PMX Industries Inc
PMX Ind Inc
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Filing date
Publication date
Application filed by PMX Industries Inc, PMX Ind Inc filed Critical PMX Industries Inc
Publication of EP2384372A2 publication Critical patent/EP2384372A2/fr
Publication of EP2384372A4 publication Critical patent/EP2384372A4/fr
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C9/00—Alloys based on copper
    • C22C9/04—Alloys based on copper with zinc as the next major constituent
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C9/00—Alloys based on copper
    • C22C9/05—Alloys based on copper with manganese as the next major constituent

Definitions

  • This invention relates to white- or silver-colored copper-based alloys with reduced nickel content compared to standard alloys of similar color.
  • 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.
  • 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.
  • C713 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.
  • nickel silvers 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.
  • 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.
  • 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.
  • 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.
  • a second YKK patent 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.
  • Another European patent 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.
  • An alloy disclosed in US Patent 6432556 (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.
  • Patent 6432556 The alloy content of Patent 6432556 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.
  • SBA Susan B. Anthony
  • 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.
  • 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.
  • 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.
  • 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.
  • the alloy contains both zinc and manganese and a reduced level of nickel compared to traditional white-colored copper-base alloys.
  • iron may be used in place of or in addition to the nickel for improved color
  • the alloy has a white visual appearance and an electrical conductivity similar to that of CDA Alloy C713 used in circulating US coinage.
  • the alloy has an appearance similar to that of stainless steel and also exhibits an electrical conductivity in the same range as stainless steel.
  • 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.
  • 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.
  • 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.
  • 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.
  • a white-colored copper alloy having an electrical conductivity greater than 2.5% IACS at eddy current gauge exciting frequencies between 6OkHz 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.
  • FIG. 1 graphically illustrates the CIELAB color chart attributes for lightness, hue and chroma as known from prior art.
  • 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.
  • FIG. 3 shows the same data as FIG 2, but focusing on the desired "white visual appearance” range.
  • FIG. 4 shows the antimicrobial effectiveness of alloys of the invention.
  • 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.
  • 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.
  • 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° observer) meets -2 ⁇ a* ⁇ 3 and -2 ⁇ b* ⁇ 10 on the CIE 1976 L* a* b*
  • 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
  • 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.
  • Resistant to tarnishing shall hereafter be defined as: after 30 days exposure in air at 20-25 °C without contact with human skin or body fluids, color change AE CMC (as defined in ASTM D2244-07, pp.2-3) between initial color and final color is less than 1.
  • "Resistant to elevated temperature tarnishing” shall hereafter be defined as: after 24 hours exposure in air at 150°C, color change AE CMC (as defined in ASTM D2244-07, pp.2-3) between initial color and final color is less than 20.
  • Determination of color may be by spectroscopy or other objective means. Instruments such as those supplied by X-Rite, Inc. (Grand Rapids, MI) 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 Figure 1.
  • CIELAB Commission Internationale de 1' 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.
  • 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
  • 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).
  • a specific combination of L*, a*, and b* values identifies a unique location in color space and a specific color, saturation, and brightness.
  • Alloys according to the present invention are listed in the tables as II, 12, 13, etc. Comparative copper alloys are listed as Cl, 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 Sl, S2, S3, and so forth.
  • 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 Cl) to the strongly white copper- nickel used in circulating US coinage (Alloy C5).
  • 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-IONi- IFe) 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.
  • 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 US 6,432,556 Bl 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.
  • 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.
  • 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.
  • Alloy C4 (Cu-IONi-IFe), 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.
  • ranges having endpoints within the ranges discussed above are contemplated even if those endpoints or ranges are not specially set forth.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • the alloys have an electrical conductivity greater than 2.5% IACS at eddy current gauge exciting frequencies between 6OkHz 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.
  • each of the compositions discussed above also has an electrical conductivity between 4% IACS and 7% IACS.
  • 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.
  • compositions contemplated include:
  • ranges having endpoints within the ranges discussed above are also contemplated even if those endpoints or ranges are not specially set forth.
  • 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.
  • 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.
  • 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.
  • Ni 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 Bl (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.
  • 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.
  • 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.
  • 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.
  • 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.
  • Mn for some of the remaining Ni, alloys with much lower Ni content are possible with substantially white (colorless) appearance.
  • retention of a low level of Ni 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.
  • 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.
  • 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.
  • Fe may be used in place of Ni or in addition to Ni to improve the whiteness of Cu-Zn-Mn alloys.
  • 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.
  • 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.
  • ⁇ E* 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 ⁇ l Section 6.2.2
  • the equivalent total color difference equation is then:
  • AE* ab [(AL*) 2 + (AC*) 2 +(AH*f] m
  • AE CMC Colour Measurement Committee
  • AE* CMC cf [(ALV(IS 1 )) 2 + (ACV(C-Sc)) 2 MAHV(S n ))) 2 ] m
  • 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.
  • the commercial factor cf can be varied to match the desired range for a given application.
  • Table 2 Atmospheric Tarnishing Table - Room Temperature Table 2. Atmospheric Tarnishing - Room Temperature
  • 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 °C and above), the direct formation of black CuO is preferred over red Cu 2 O 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.
  • AE CMC 11.9, illustrating that addition of Fe not only improved whiteness of the alloy but enhanced tarnish resistance as well.
  • Touch surfaces 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.
  • 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; ⁇ E 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; ⁇ E 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.
  • 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 Il 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.
  • 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.
  • 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 ⁇ l aliquot of a suspension of active bacterial culture (E. CoIi, 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 6 - 10 8 colony-forming units per milliliter (CFU/ml).
  • active bacterial culture E. CoIi, American Type Culture Collection [ATCC] strain 11229, Gram-negative
  • the coupons were placed in tubes containing 20 ml of sterilized Butterfield's buffer (3.1x10 " 4 M K 2 HPO 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 ⁇ l aliquot of this original suspension and of each dilution was plated onto nutrient agar and incubated at 35-37 ° C for 48 hours to count the surviving colonies.
  • Comparative Alloy C32 (Cu-IOZn) shows a 99.9% reduction in bacteria count after exposures between 90 and 105 minutes and complete inactivation after 105 minutes.
  • Alloy C4 (Cu-IONi-IFe) 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 Cl commercially pure copper shows a 99.9% reduction in bacteria count after exposures between 75 and 90 minutes, with complete inactivation after 90 minutes.

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Abstract

La présente invention concerne un alliage de cuivre de couleur blanche comprenant en poids jusqu’à 30 % de zinc, jusqu’à 20 % de manganèse, jusqu’à 5 % de nickel et le complément étant du cuivre. Cet alliage peut comprendre de 6 % à 25 % de zinc, de 4 % à 17 % de manganèse, de 0,1 % à 3,5 % de nickel et le complément étant du cuivre. Le complément de cuivre dans l’alliage peut contenir en outre au moins l’un de : jusqu’à 0,5 % d’au moins l’un du groupe constitué de Sn, Si, Co, Ti, Cr, Fe, Mg, Zr, et Ag; et jusqu’à 0,1 % d’au moins l’un du groupe qui est constitué de P, B, Ca, Ge, Se, Te. Il peut contenir en outre jusqu’à 0,3 % de Zr en poids. L’alliage peut avoir une conductivité électrique supérieure à 2,5 % IACS à des fréquences d’excitation de jauge de courant de Foucault comprises entre 60 kHz et 480 kHz.
EP09813496.8A 2008-09-10 2009-09-08 Alliage de cuivre de couleur blanche avec une teneur en nickel réduite Withdrawn EP2384372A4 (fr)

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CN103074516A (zh) * 2013-01-28 2013-05-01 江西理工大学 一种低镍无铅易切削白铜及其制备方法
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CN104046812B (zh) * 2014-06-05 2016-08-24 锐展(铜陵)科技有限公司 一种汽车用高延展铜合金线的制备方法
CN106148757A (zh) * 2015-04-20 2016-11-23 沈阳万龙源冶金新材料科技有限公司 一种铜合金
KR20190061639A (ko) 2017-11-28 2019-06-05 (주)퀀텀바이오 구리-철 나노 분말 및 그 제조 방법
CN109897988A (zh) * 2019-03-08 2019-06-18 嘉善雄真金属钮扣厂(普通合伙) 一种应用复合材料的金属纽扣及其生产工艺
CN110055451A (zh) * 2019-04-28 2019-07-26 杭州鼎好新材料有限公司 一种养生保健复合材料及其制备方法
CN110157945B (zh) * 2019-04-29 2021-08-31 宁波博威新材料有限公司 一种抗软化的铜合金及其制备方法和应用
CN112063882B (zh) * 2020-09-15 2021-10-12 九牧厨卫股份有限公司 一种铸造用无铅铜合金及其制备方法
CN113604702A (zh) * 2021-07-20 2021-11-05 佛山市麦欧金属有限公司 一种激光切割925银版专用铜合金及加工方法
CN115522099B (zh) * 2022-11-07 2023-07-21 广州番禺职业技术学院 一种铸造白铜饰品材料及其制备方法
CN115992324B (zh) * 2023-02-15 2024-08-02 宁波金田铜业(集团)股份有限公司 一种低镍锌白铜线材及其制备方法
CN117305649B (zh) * 2023-11-29 2024-02-27 中铝科学技术研究院有限公司 铜合金材料及其制备方法

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AU2009291971A1 (en) 2010-03-18
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EP2384372A4 (fr) 2013-11-20
MX2011002500A (es) 2011-04-07
KR101859438B1 (ko) 2018-05-21
AU2018204756A1 (en) 2018-07-19
CN102149834B (zh) 2013-06-12
KR101859435B1 (ko) 2018-05-21
KR20170020554A (ko) 2017-02-22
JP6170099B2 (ja) 2017-07-26
KR20170020553A (ko) 2017-02-22
KR20110053998A (ko) 2011-05-24
WO2010030597A2 (fr) 2010-03-18
JP2015221943A (ja) 2015-12-10
WO2010030597A3 (fr) 2010-07-01
JP2012502189A (ja) 2012-01-26
CN102149834A (zh) 2011-08-10

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