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Metallographic Examination of Fine Gold and a Gold-Copper Alloy for Coin Manufacturing

  • S. Greil , C. Edtmaier , R. Haubner and L. Lauter
Published/Copyright: June 9, 2018
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Practical Metallography
From the journal Practical Metallography Volume 55 Issue 6

Abstract

The mechanical properties and microstructures of alloys play an important role in the different steps of the coin manufacturing process. Only few data are available for the precious metals gold and silver as well as for their respective alloys. Several different circular coin blanks were metallographically examined in order to provide a better estimation of the impact of the production steps on the material. An electrochemical polishing method was developed aiming at obtaining contrast-rich and artifact-free micrographs. The microhardness was systematically measured on the whole surface of polished cross sections in order to generate distribution mappings. Object of the examination was fine gold (Au 999.9) and ducat gold (Au 986) which are primarily used to manufacture bullion and collector coins.

Kurzfassung

Für die verschiedenen Schritte in der Münzherstellung sind die mechanischen Eigenschaften und Gefüge der Legierungen wichtig. Für die Edelmetalle Gold und Silber sowie deren Legierungen stehen jedoch nur wenige Daten zur Verfügung. Um die Einflüsse der Produktionsschritte auf das Material besser einschätzen zu können, wurden verschiedene Münzronden metallographisch untersucht. Um kontrastreiche und artefaktfreie Gefügeaufnahmen zu erzielen, wurde eine elektrochemische Poliertechnik entwickelt. An polierten Querschliffen wurde die Mikrohärte systematisch auf der gesamten Fläche gemessen, um Verteilungsbilder zu erhalten. Es wurden Feingold (Au 999,9) und Dukatengold (Au 986) untersucht, aus denen vorwiegend Anlage- und Sammlermünzen hergestellt werden.

Translation: E. Engert

References / Literatur

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Received: 2018-02-22
Accepted: 2018-03-08
Published Online: 2018-06-09
Published in Print: 2018-06-15

© 2018, Carl Hanser Verlag, München

Articles in the same Issue

  1. Contents/Inhalt
  2. Contents
  3. Editorial
  4. Editorial
  5. Technical Contributions/Fachbeiträge
  6. Metallographic Examination of Fine Gold and a Gold-Copper Alloy for Coin Manufacturing
  7. Effects of Friction Stir Processing on the Microstructure and Mechanical Properties of Al-Mg-Sc Alloy
  8. Derivation of Property Distribution Images from Microstructural Analyses of X2CrNi18-9 with Regard to Hydrogen Embrittlement
  9. Condition Monitoring of a Power Tower Using Metallurgical Investigations of Structural Members
  10. Meeting Diary/Veranstaltungskalender
  11. Meeting Diary
https://doi.org/10.3139/147.110524

Articles in the same Issue

  1. Contents/Inhalt
  2. Contents
  3. Editorial
  4. Editorial
  5. Technical Contributions/Fachbeiträge
  6. Metallographic Examination of Fine Gold and a Gold-Copper Alloy for Coin Manufacturing
  7. Effects of Friction Stir Processing on the Microstructure and Mechanical Properties of Al-Mg-Sc Alloy
  8. Derivation of Property Distribution Images from Microstructural Analyses of X2CrNi18-9 with Regard to Hydrogen Embrittlement
  9. Condition Monitoring of a Power Tower Using Metallurgical Investigations of Structural Members
  10. Meeting Diary/Veranstaltungskalender
  11. Meeting Diary
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