Chemistry:Nordic Gold
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]
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
- ↑ Predecimal.com. "The selection of the alloy for the New Euro Coins". https://www.predecimal.com/euroarticle.htm.
- ↑ 2.0 2.1 "Brass Material and Specifications Review". Engineer's Edge LLC. https://www.engineersedge.com/brass.htm.
- ↑ "Common sides of euro coins". European Commission website. https://economy-finance.ec.europa.eu/euro/euro-coins-and-notes/euro-coins/common-sides-euro-coins_en.
- ↑ Rohrig, Brian (2020). The Chemistry of Money. Royal Society of Chemistry. p. 146. ISBN 9781782629832. https://books.google.com/books?id=eK8IEAAAQBAJ.
- ↑ "What is Nordic Gold?". European Copper Institute. https://copperalliance.gr/resources/what-is-nordic-gold/.[yes|permanent dead link|dead link}}]
- ↑ Quaranta, Davide (January 2011). "Mechanisms of Contact-Mediated Killing of Yeast Cells on Dry Metallic Copper Surfaces". Appl. Environ. Microbiol. (American Society for Microbiology) 77 (2): 416–426. doi:10.1128/AEM.01704-10. PMID 21097600. Bibcode: 2011ApEnM..77..416Q.
- ↑ Horton, D. (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. https://www.sciencedirect.com/science/article/pii/S0013468615008774. Retrieved 2020-03-20.
- ↑ Foster, Leanna (2014). Tarnishing of a Cu-Al-Zn-Sn Alloy Compared to Commercially Pure Copper: Implications Toward Antimicrobial Function. doi:10.18130/V3Q08V.
- ↑ Kuparinen, Tuulikki (19 December 2001). "Kultaiset eurokolikot syntyvät Outokummun kupariseoksesta" (in fi). https://www.is.fi/taloussanomat/art-2000001355265.html. "Yhtiön tutkimus- ja kehitysasiantuntija Mariann Sundberg on kehittänyt Nordic Gold -kuparimetalliseoksen"
- ↑ "Security features". European Central Bank. 2022. https://www.ecb.europa.eu/euro/coins/security/html/index.en.html.
- ↑ 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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