Nordic_gold

Nordic Gold

Nordic Gold

Copper alloy used in many coins

Nordic Gold (Swedish: nordiskt guld[1]) is the gold-coloured copper alloy from which many coins are made. The alloy is a type of aluminium brass. It has been used for a number of coins in many currencies, most notably in euro 50, 20, and 10 cents,[2][3] in the Swedish 5 and 10 kronor coins (for which it was originally developed and introduced in 1991),[4] as well as the Polish 2 złoty commemorative coins. Its composition is 89% copper, 5% aluminium, 5% zinc, and 1% tin.[5][2]

50 euro cent coin made out of Nordic Gold.

Being a copper alloy, it contains no gold. Its colour and density are unlike pure gold. It is non-allergenic; its other advantages include antimycotic[6] and weak antimicrobial (especially after abrasion)[7] attributes, and resistance to tarnishing. It has been studied for its antimicrobial hospital applications.[8]

Nordic Gold was developed by Mariann Sundberg while she worked for the Finnish metal company Outokumpu.[9] The European Central Bank says that the alloy is "difficult to melt and used exclusively for coins."[10]

Properties

Compared to commercial copper metal, Nordic Gold has significantly smaller grains. A thin oxide material is formed after abrasive polishing.[11] The alloy's antimicrobial properties were studied extensively in 2014 because it showed promise for use in hospitals, to help prevent MRSA infections. A rather complete description of its electrochemical properties was one result.

References

  1. [1]
    Predecimal.com. "The selection of the alloy for the New Euro Coins". Retrieved 2020-03-20.
  2. [2]
    "Brass Material and Specifications Review". Engineer's Edge LLC. Retrieved 14 July 2022.
  3. [3]
    "Common sides of euro coins". European Commission website. Retrieved 14 July 2022.
  4. [4]
    Rohrig, Brian (2020). The Chemistry of Money. Royal Society of Chemistry. p. 146. ISBN 9781782629832.
  5. [5]
    "What is Nordic Gold?". European Copper Institute. Retrieved 14 July 2022.[permanent dead link]
  6. [6]
    Quaranta, Davide; et al. (January 2011). "Mechanisms of Contact-Mediated Killing of Yeast Cells on Dry Metallic Copper Surfaces". Appl. Environ. Microbiol. 77 (2). American Society for Microbiology: 416–426. Bibcode:2011ApEnM..77..416Q. doi:10.1128/AEM.01704-10. PMC 3020553. PMID 21097600.
  7. [7]
    Horton, D.; et al. (2015). "Tarnishing and Cu Ion release In Selected Copper-Base Alloys: Implications Towards Anti-Microbial Functionality". Electrochimica Acta. 169: 351–366. doi:10.1016/j.electacta.2015.04.001. Retrieved 2020-03-20.
  8. [8]
    Foster, Leanna (2014). "Tarnishing of a Cu-Al-Zn-Sn Alloy Compared to Commercially Pure Copper: Implications Toward Antimicrobial Function". doi:10.18130/V3Q08V. {{cite journal}}: Cite journal requires |journal= (help)
  9. [9]
    Kuparinen, Tuulikki (19 December 2001). "Kultaiset eurokolikot syntyvät Outokummun kupariseoksesta". Ilta-Sanomat (in Finnish). Retrieved 7 February 2021. Yhtiön tutkimus- ja kehitysasiantuntija Mariann Sundberg on kehittänyt Nordic Gold -kuparimetalliseoksen
  10. [10]
    "Security features". European Central Bank. 2022.
  11. [11]
    Chang, Tingru; Wallinder, Inger Odnevall; Jin, Ying; Leygraf, Christofer (2018). "The golden alloy Cu-5Zn-5Al-1Sn: A multi-analytical surface characterization". Corrosion Science. 131: 94–103. doi:10.1016/j.corsci.2017.11.014.
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