{{Short description|Metal alloy of copper with lead}} [[File:Eight leaded copper alloy discs (FindID 194878).jpg|thumb|alt=Eight malformed yellow metal tokens| 17th c. leaded copper tokens, found in Hatton, Lincolnshire; face & reverse<ref>{{cite web |url=https://finds.org.uk/database/ajax/webcite/id/194878/type/artefacts |title=Finds record for: LIN-7A08C1 |author=Daubney, A |accessdate=Feb 18, 2026|publisher=The Portable Antiquities Scheme}}</ref> ]] '''Leaded copper''' ({{langx|el|μολυβδόχαλκος}}, {{transliteration|el|'''molybdochalkos'''}} {{literal|lead-copper}})<ref>{{cite book |last1=Liddell |first1=Henry George |last2=Scott |first2=Robert |date=1940 |title=A Greek-English Lexicon |publisher=Oxford University Press |isbn=9780198642268 |edition=9th}}</ref> is a metal alloy of copper with lead. A small amount of lead makes the copper easier to machine. Alloys with a larger amount of lead are used for bearings. Brass and bronze alloys of copper may have lead added and are then also sometimes referred to as leaded copper alloys.<ref name="welter">Welter (2014)</ref> Leaded copper and its alloys have been used since ancient times.
==History== Signs of leaded copper use are found in the manufacture of ancient Egyptian faience. By 1500 BC leaded copper could be found across the Old World from East Asia to Africa and Europe.<ref>[https://copperalliance.org.uk/about-copper/copper-history/copper-through-the-ages/ "Copper Through the Ages"] {{Webarchive|url=https://web.archive.org/web/20211110105629/https://copperalliance.org.uk/about-copper/copper-history/copper-through-the-ages/ |date=2021-11-10 }}, Copper Development Association (retrieved 16 October 2019)</ref>
Enigmatic entries in a Chinese manuscript, the ''Kao Gong Ji'' dating from around 300 BC, were deciphered by scholars in 2022, and seem to indicate that a pre-prepared copper-lead alloy named ''Jin''(金) may have been used in the preparation of ancient bronzes. Another copper-tin-lead alloy named ''Xi''(锡) was also tentatively identified as a pre-prepared component of Chinese bronzes. This part of the manuscript relates to an attempt to standardise the quality of bronze manufacture.<ref>{{Cite journal |last=Pollard |first=A. M. |last2=Liu |first2=Ruiliang |date=2022 |title=The six recipes of Zhou: a new perspective on Jin (金) and Xi (锡) |url=https://www.researchgate.net/profile/Ruiliang-Liu-3/publication/362594264_The_six_recipes_of_Zhou_a_new_perspective_on_Jin_jin_and_Xi_xi/links/62f39ffeb8dc8b4403d26c68/The-six-recipes-of-Zhou-a-new-perspective-on-Jin-jin-and-Xi-xi.pdf |journal=Antiquity |language=en |volume=96 |issue=389 |pages=1200–1213 |doi=10.15184/aqy.2022.81 |issn=0003-598X}}</ref><ref>{{Cite news |last=Pare |first=Sascha |date=10 August 2022 |title=Researchers decode metal-making recipes in ancient Chinese text |url=https://www.theguardian.com/world/2022/aug/10/metal-making-recipes-ancient-chinese-text-kaogong-ji |access-date=10 August 2022 |work=The Guardian}}</ref>
Leaded copper was frequently used in alchemy. Yellow-colored {{transliteration|el|molybdochalkos}} was a starting material for transmutation into gold.<ref>{{Citation |title=History of Alchemy and Early Chemistry |last=Partington |first=J.R. |date=1947-01-18 |work=Nature |issue=159 |pages=81-85 |doi=10.1038/159081a0}}</ref> In the tradition of Mary the Jewess, {{transliteration|el|molybdochalkos}} was the typical base metal used in the ''kerotakis'', wherein leaded copper was exposed to sulfur vapors and blackened, on the basis of ''nigredo.''<ref>{{cite book |author1=Kyle Fraser |editor1-last=Keyser |editor1-first=Paul |editor2-last=Scarborough |editor2-first=John |date=2018 |title=The Oxford Handbook of Science and Medicine in the Classical World |publisher=Oxford University Press |isbn=9780199734146 |pages=732–733 |chapter=Distilling Nature's Secrets: The Sacred Art of Alchemy}}</ref><ref>{{Citation |chapter=Griechische Alchemie |last=Jost |first=Weyer |title=Geschichte der Chemie Band 1 – Altertum, Mittelalter, 16. bis 18. Jahrhundert |place=Berlin, Heidelberg |publisher=Springer Spektrum |year=2018 |doi=10.1007/978-3-662-55798-3_5 |isbn=978-3-662-55797-6|trans-chapter=Greek Alchemy|trans-title=History of Chemistry Volume 1 – Antiquity, Middle Ages, 16th to 18th Century|lang=German}}</ref>{{rp|136}}
==Applications==
Leaded copper alloys are used to make electrical connectors and mechanical bearings, especially in the automotive industry where high performance and reliability are required. Mechanical bearings can have high lead content. Such high lead content alloys are unsuitable for welding or brazing.<ref>Aalco, pp.72-3</ref>
===Machined alloys=== Alloys with around 2-4% lead are used for machined copper applications, where the lead content lubricates the copper and makes it easier to machine. These include high-quality electrical connectors where a high current capacity and low electrical resistance are required. Such connectors are used in industrial automation and the automotive industry.<ref>Robert Hult, [https://www.connectorsupplier.com/leaded-copper-alloys-get-a-new-lease-on-life/ "Leaded Copper Alloys Get A New Lease on Life"], ConnectorSupplier.com. (retrieved 16 October 2019)</ref><ref name="welter"/> Brasses (copper alloyed with zinc) may also be leaded for the same reason.<ref name="aalco74">Aalco, p.74.</ref>
===Cast and sintered alloys=== High-strength casting copper alloys typically contain less than 2% lead.<ref name="welter"/> Bearing alloys are often cast or sintered onto a steel backing. Softer alloys with a higher lead content are also used, for example in bushes where conformance to the opposite bearing surface is important.<ref>Richard Stone; ''Introduction to Internal Combustion Engines'', 4th Edition, Palgrave Macmillan, 2012. {{ISBN|978-0-230-57663-6}}. Pages 160-1.</ref><ref name="vandervell">[http://www.connellmarketing.co.uk/vandervell/materials/mobile/index.html Engine Bearing Materials] catalogue, Glacier Vanderbell.</ref>
Some casting alloys have over 20% lead content but, due to their toxicity, they are no longer used.<ref name="aalco74"/>
==Toxicity== When lead alloys wear, lead is released into the environment. It is a toxic heavy metal and in recent times the use of leaded copper alloys has been reduced.<ref name="welter"/>
==References== <references />
===Bibliography=== *[http://www.aalco.co.uk/literature/files/aalco-copper-brass-bronze.pdf Aalco brochure], Pages 70-85. *Jean-Marie Welter; [https://elv.exemptions.oeko.info/fileadmin/user_upload/Consultation_2014_1/Ex_3/E3__02__Welter_2014_leaded_copper_alloys_for_automotive_applications-a_scrutiny.pdf Leaded Copper Alloys for Automotive Applications: A Scrutiny], European Copper Institute, 2014.
Category:Copper alloys Category:Lead alloys Category:Alchemical substances
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