{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,8]],"date-time":"2026-04-08T00:57:10Z","timestamp":1775609830619,"version":"3.50.1"},"reference-count":22,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2022,2,27]],"date-time":"2022-02-27T00:00:00Z","timestamp":1645920000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e Tecnologia","doi-asserted-by":"publisher","award":["UID\/FIS\/04559\/2019"],"award-info":[{"award-number":["UID\/FIS\/04559\/2019"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Processes"],"abstract":"<jats:p>Very high fluence implantation of 14N+ ions was used to promote the formation of a nitride layer on the surface of steel coinage dies used by the Portuguese Mint. Die steel samples were studied before and after implantation at 90 keV plus 30 keV for two nominal fluences, 5.0 \u00d7 1017 at\/cm2 and 1.0 \u00d7 1018 at\/cm2, and for two implantation temperatures, room and liquid nitrogen temperature. Surface characterization was carried out by ultramicrohardness indentation, Atomic Force Microscopy (AFM), and Rutherford Backscattering Spectrometry (RBS). A significant increase (factor two) in depth reached by the implanted nitrogen was observed for LN2 implantations, which, to our knowledge, was never reported before. Results point out the benefit of nitrogen implantation at room temperature with a nominal fluence of 5.0 \u00d7 1017 at\/cm2, which raised the hardness of the dies by \u223c40% (from 6.2 \u00b1 0.5 to 8.7 \u00b1 0.7 GPa). Nitrogen implanted dies were used to mint circulating two cents euro coins and their performance was assessed, showing that when compared to Vautrol coated dies (standard coating used by the Portuguese Mint), the crack density was lower and similar wear resistance was observed.<\/jats:p>","DOI":"10.3390\/pr10030479","type":"journal-article","created":{"date-parts":[[2022,2,27]],"date-time":"2022-02-27T20:48:33Z","timestamp":1645994913000},"page":"479","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Surface Characterization and Performance Evaluation of Nitrogen Implanted Coinage Dies"],"prefix":"10.3390","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3242-0328","authenticated-orcid":false,"given":"Jo\u00e3o","family":"Cruz","sequence":"first","affiliation":[{"name":"Laborat\u00f3rio de Instrumenta\u00e7\u00e3o, Engenharia Biom\u00e9dica e F\u00edsica da Radia\u00e7\u00e3o (LIBPhys-UNL), Departamento de F\u00edsica, Faculdade de Ci\u00eancias e Tecnologia da Universidade Nova de Lisboa, Monte da Caparica, 2892-516 Caparica, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8323-0634","authenticated-orcid":false,"given":"Victoria","family":"Corregidor","sequence":"additional","affiliation":[{"name":"Centro de Ci\u00eancias e Tecnologias Nucleares (C2TN), Instituto Superior T\u00e9cnico, Universidade de Lisboa, E.N. 10 km 139,7, 2695-066 Bobadela LRS, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7130-447X","authenticated-orcid":false,"given":"Bruno","family":"Nunes","sequence":"additional","affiliation":[{"name":"Centro de Qu\u00edmica Estrutural (CQE), Instituto Superior T\u00e9cnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal"},{"name":"Atl\u00e2ntica, Instituto Universit\u00e1rio, Fabrica da P\u00f3lvora, 2730-036 Barcarena, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5369-5019","authenticated-orcid":false,"given":"Lu\u00eds","family":"Alves","sequence":"additional","affiliation":[{"name":"Centro de Ci\u00eancias e Tecnologias Nucleares (C2TN), Instituto Superior T\u00e9cnico, Universidade de Lisboa, E.N. 10 km 139,7, 2695-066 Bobadela LRS, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5529-1621","authenticated-orcid":false,"given":"Rog\u00e9rio","family":"Cola\u00e7o","sequence":"additional","affiliation":[{"name":"Instituto de Engenharia Mec\u00e2nica (IDMEC), Instituto Superior T\u00e9cnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal"}]},{"given":"Eduardo","family":"Alves","sequence":"additional","affiliation":[{"name":"Centro de Ci\u00eancias e Tecnologias Nucleares (C2TN), Instituto Superior T\u00e9cnico, Universidade de Lisboa, E.N. 10 km 139,7, 2695-066 Bobadela LRS, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2022,2,27]]},"reference":[{"key":"ref_1","unstructured":"(2021, December 14). B\u00d6HLER. Available online: https:\/\/www.bohler.at\/export\/en\/."},{"key":"ref_2","unstructured":"(2021, December 14). VTT. Available online: https:\/\/www.vtt.de."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"263","DOI":"10.1016\/0025-5416(87)90220-5","article-title":"Tribological Properties of Ion-implanted Steels","volume":"90","author":"Iwaki","year":"1987","journal-title":"Mater. Sci. 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