1,720,991 research outputs found
Il ripostiglio della tenuta di Lunghezzina (Roma), 1995; indagine microchimica e microstrutturale
No full textIndagine microchimica e microstrutturale di masse metalliche ascrivibili alla categoria dell’Aes rude
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Bronze roman mirrors: the secret of brightness
No full textThe surface microchemical structure of high tin leaded bronze Roman mirrors has been studied by means of scanning electron microscopy combined with energy dispersive spectrometry (SEM-EDS), X-ray diffraction (XRD) and optical microscopy (OM) techniques. The results allowed understanding of the origin of their high chemical stability and silvery-lustrous appearance. Indeed, some areas of the selected Roman mirrors are still characterised by a highly reflective and silver coloured surface even though they have been buried in the soil for about 2000 years. The micro-chemical results obtained from these areas have revealed that the mirror surface was tin enriched via inverse-segregation phenomenon by tailoring the cooling parameters. Furthermore, the presence of tin could be likely enhanced via cycles of oxidation and selective copper corrosion processes, thus resulting in a tin surface enrichment as a semi-transparent amorphous-like tin oxide (SnO2) film, as well as a copper depletion at the outer surfaces
Microchemical investigation of archaeological copper-based artefacts used for currency in ancient Italy before the coinage
No full textBy means of the combined use of XPS and scanning electron microscopy + energy dispersive spectrometry (SEM + EDS), the microchemical structure of long-term corrosion products grown on Aes Rude, i.e. archaeological unworked lumps of Cu-based materials, has been carried out. In ancient Italy, these materials have been used as currency, as a medium of exchange and as a form of saving, from the sixth to the third centuries BC before the use of the struck metallic coins. The results of the microchemical investigation disclose their apparently unusable nature for any functional applications or possible use, being constituted of highly ferruginous leaded copper, and demonstrate that Aes Rude were a primitive form of currency as suggested by archaeologists. Furthermore, XPS and SEM + EDS results give evidence on the corroded external region of the presence of Cu (II) hydrates mixed with hydrated iron oxide and aluminium-silicon phases coming from the soil that have been incorporated into the patina. This information is useful to identify the material nature of these archaeological artefacts and to select tailored conservation strategies finalized to ensure long life to these relevant ancient materials
Microstructure, chemistry and corrosion products of copper and copper alloys of artefacts from Pyrgi (Italy) through a multi-analytical approach
No full textIn this study, several archaeological artifacts, i.e., arrowheads, nails, and aes rude, made of copper or copper alloys were examined (Esposito et al., 2019). They were found at the Etruscan site of Pyrgi (Santa Severa, Italy), dating back to the 6th to 4th century B.C. We explored the microstructure and composition of each sample, considering its relationship to the environmental storage, and the possible corrosion phenomena triggered on its surface. Such phenomena can produce irregular multilayer structures (patina) and possible selective enrichment or depletion processes of alloying elements. A multi-analytical approach, based on Scanning Electron Microscope, X-ray maps, and μ-Raman spectroscopy was used. The chemical composition of nails and aes rude is pure copper, while arrowheads are made of a ternary Cu-Sn-Pb alloy. In addition, it was possible to distinguish artifacts produced by simple casting from those that underwent additional processing. The μ-Raman spectra of the surface of the artifacts indicated the occurrence of cuprite, malachite, and copper trihydroxy-chlorides, indicating the occurrence of type I and type II patinas (Robbiola et al., 1998). The presence of chlorine even within the cores in some samples indicates a very corrosive environment. The chemical and microstructural information allowed hypotheses on the production and metallurgical processes of the artifacts and their application. The choice of using copper nails was quite unusual, but as reported in the literature (Dilo et al., 2010; Pomey et al., 2013), it could be due to their use in ship carpentry. As for the arrowheads, the data suggest that they are votive objects as their composition and structure would make them not particularly suitable as weapons. The aes rude, almost all composed of pure copper, represent one of the earliest forms of coinage. They are semi-finished products, rich in inclusions due to the process of smelting raw materials. These data provide valuable information on the processing techniques and materials used by the Etruscans, contributing to the understanding of their technological capabilities and conservation processes of artifacts found in a coastal archaeological context such as Pyrgi.
Dilo T. et al. (2010) - Archaeometallurgical characterization of some ancient copper and bronze artifacts from Albania. AIP Conference Proceedings, 1203, 985-990, https://doi.org/10.1063/1.3322596.
Esposito A. et al. (2019) - The production of metal artefacts in Southern Etruria (Central Italy): Case studies from copper to Iron Age. Sci. Technol. Archaeol. Res., 5.2, 64-84, https://doi.org/10.1080/20548923.2019.1660496.
Pomey P. et al. (2013) - On the transition from Shell to Skeleton. Int. J. Naut. Archaeol., 42(2), 434-438.
Robbiola L. et al. (1998) - Morphology and mechanisms of formation of natural patinas on archaeological Cu–Sn alloys. Corros. Sci., 40(12), 2083-2111, https://doi.org/10.1016/S0010-938X(98)00096-1
Production of reference ancient Cu-based alloys and their accelerated degradation methods
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