23 resultados para Copper alloys.
Resumo:
Dissertação para obtenção do Grau de Mestre em Conservação e Restauro
Resumo:
Archaeological excavations carried out in the archaeological site of São Pedro (Southern Portugal) revealed a Chalcolithic settlement occupied in different moments of the 3rd millennium BC. The material culture recovered includes different types of materials, such as ceramics, lithics and metals. The later comprises about 30 artefacts with different typologies such as tools (e.g. awls, chisels and a saw) and weapons (e.g. daggers and arrowheads) mostly belonging to the 2nd and 3rd quarter of the 3rd millennium BC. In the present work the collection of chalcolithic metallic artefacts recovered in São Pedro was characterized. Analytical studies involved micro energy dispersive X-ray fluorescence spectrometry (micro-EDXRF) to determine elemental composition, together with optical microscopy and Vickers microhardness testing for microstructural characterisation and hardness determination. Main results show copper with variable amounts of arsenic and very low content of other impurities, such as iron. Moreover, nearly half of the collection is composed by arsenical copper alloys (As > 2 wt.%) and an association was found between arsenic content and typology since the weapons group (mostly daggers) present higher values than tools (mostly awls). These results suggest some criteria in the selection of arsenic-rich copper ores or smelting products. Furthermore, after casting an artefact would have been hammered, annealed and sometimes, finished with a hammering operation. Additionally, microstructural variations in this collection reveal somewhat different operational conditions during casting, annealing and forging, as expected in such a primitive metallurgy. Moreover the operational sequence seems to be used to achieve the required shape to the object, rather than to intentionally make the alloy harder. Overall, this study suggests that Chalcolithic metallurgists might have a poor control of the addition of arsenic and/or were unable to use this element to increase the hardness of tools and weapons. Finally, the compositions, manufacturing processes and hardness were compared to those from neighbouring regions and different chronological periods.
Resumo:
Dissertação apresentada para a obtenção do Grau de Doutor em Conservação e Restauro, especialidade Ciências da Conservação, pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia
Resumo:
Eur. J. Biochem. 271, 2361–2369 (2004)
Resumo:
Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Mecânica
Resumo:
Dissertação apresentada à Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Doutor em Engenharia Civil
Resumo:
Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Biotecnologia
Resumo:
Dissertação para obtenção do Grau de Mestre em Engenharia Mecânica
Resumo:
Dissertação para obtenção do Grau de Doutor em Conservação e Restauro, especialidade Ciências da Conservação
Resumo:
Dissertação para obtenção do Grau de Mestre em Engenharia de Materiais
Resumo:
J Biol Inorg Chem (2011) 16:183–194 DOI 10.1007/s00775-011-0753-3
Resumo:
Biochemistry, 2004, 43 (46), pp 14566–14576 DOI: 10.1021/bi0485833
Resumo:
Dissertação para a obtenção do grau de Mestre em Engenharia Mecânica
Resumo:
Dissertação para obtenção do Grau de Doutor em Nanotecnologia e Nanociência
Resumo:
Dissertation for the Master’s Degree in Structural and Functional Biochemistry