Nordic Gold
Nordic Gold (Swedish: nordiskt guld[1]) is the gold-coloured copper alloy from which many coins are made. 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 złote 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 weight 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 diamond polishing. This passivating layer contains Cu2O, which faces outward, followed by ZnO, SnO2 and Al2O3 closer to the alloy substrate. The latter three possess barrier properties.[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". Retrieved 2020-03-20.
- ^ a b "Brass Material and Specifications Review". Engineer's Edge LLC. Retrieved 14 July 2022.
- ^ "Common sides of euro coins". European Commission website. Retrieved 14 July 2022.
- ^ Rohrig, Brian (2020). The Chemistry of Money. Royal Society of Chemistry. p. 146. ISBN 9781782629832.
- ^ "What is Nordic Gold?". European Copper Institute. Retrieved 14 July 2022.
- ^ Quaranta, Davide; et al. (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. Bibcode:2011ApEnM..77..416Q. doi:10.1128/AEM.01704-10. PMC 3020553. PMID 21097600.
- ^ 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.
- ^ 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) - ^ 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
- ^ "Security features". European Central Bank. 2022.
- ^ 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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