LA CORROSIONE ATMOSFERICA DEI MONUMENTI IN BRONZO: PROVE DI INVECCHIAMENTO ARTIFICIALE

I monumenti in bronzo esposti all’aperto risentono di diverse tipologie di degrado, in conseguenza delle diversecondizioni di esposizione all’ambiente e, in particolare, alla pioggia.Allo scopo di studiare la correlazione causa-effetto tra l’evoluzione della corrosione di un bronzo e la suadifferente esposizione alla pioggia (pioggia stagnante o pioggia lisciviante), è stato intrapreso un lavoro di ricercamultidisciplinare. Nel presente lavoro vengono quindi riportati i risultati delle prove eseguite sul bronzo quaternarioG85, largamente impiegato per fusioni artistiche. La soluzione aggressiva impiegata è stata formulata sulla base dellecaratteristiche di piogge reali raccolte nell’area urbana di Bologna. La condizione di stagnazione è stata riprodottamediante un dispositivo wet&dry specificamente progettato e realizzato, in cui il bronzo viene ciclicamente immersonella pioggia sintetica, che viene periodicamente analizzata per valutare l’evoluzione del pH e della concentrazionedi metalli dissolti. Parallelamente, anche i materiali esposti vengono caratterizzati mediante misure gravimetriche,VPSEM+EDS+micro-Raman e XRD. La condizione di pioggia battente (run-off) viene invece simulata medianteun apposito dispositivo di dropping, che intende riprodurre, in condizioni controllate, l’azione della pioggia suuna superficie inclinata a piacere. Anche in questo caso sia le superfici esposte che la soluzione lisciviante vengonoanalizzate parallelamente nel corso dell’esposizione.L’analisi dei dati ottenuti ha permesso la formulazione di modelli interpretativi per i processi di corrosione delbronzo quaternario; inoltre, il confronto con casi reali di corrosione di monumenti bronzei ha consentito di stimarel’affidabilità dei modelli proposti e la loro efficacia a fini diagnostici e conservativi

Ancient coins: cluster analysis applied to find a correlation between corrosion process and burial soil characteristics

Although it is well known that any material degrades faster when exposed to an aggressive environment as well as that "aggressive" cannot be univocally defined as depending also on the chemical-physical characteristics of material, few researches on the identification of the most significant parameters influencing the corrosion of metallic object are available

FIB-FESEM and EMPA results on Antoninianus silver coins for manufacturing and corrosion processes

[EN] A set of ancient Antoninianus silver coins, dating back between 249 and 274¿A.D. and minted in Rome, Galliae, Orient and Ticinum, have been characterized. We use, for the first time, a combination of nano-invasive (focused ion beam-field emission scanning electron microscopy-X-ray microanalysis (FIB-FESEM-EDX), voltammetry of microparticles (VIMP)) and destructive techniques (scanning electron microscopy (SEM-EDX) and electron microprobe analysis (EMPA)) along with non-invasive, i.e., micro-Raman spectroscopy. The results revealed that, contrary to the extended belief, a complex Ag-Cu-Pb-Sn alloy was used. The use of alloys was common in the flourishing years of the Roman Empire. In the prosperous periods, Romans produced Ag-Cu alloys with relatively high silver content for the manufacture of both the external layers and inner nucleus of coins. This study also revealed that, although surface silvering processes were applied in different periods of crisis under the reign of Antoninii, even during crisis, Romans produced Antoninianus of high quality. Moreover, a first attempt to improve the silvering procedure using Hg-Ag amalgam has been identified.Financial support was provided by Sapienza University of Rome (Ateneo funding, 2014 15) and Spanish projects CTQ2014-53736-C3-1-P and CTQ2014-53736-C3-2-P, which are supported with Ministerio de Economía, Industria y Competitividad (MINECO) and Fondo Europeo de Desarrollo Regional (ERDF) funds, as well as project CTQ2017-85317-C2-1-P supported with funds from, MINECO, ERDF and Agencia Estatal de Investigación (AEI). PhD grants of the Department of Earth Sciences, Sapienza University of Rome, are gratefully acknowledgedDomenech Carbo, MT.; Di Turo, F.; Montoya, N.; Catalli, F.; Doménech Carbó, A.; De Vito, C. (2018). FIB-FESEM and EMPA results on Antoninianus silver coins for manufacturing and corrosion processes. Scientific Reports. 8. https://doi.org/10.1038/s41598-018-28990-xS8Doménech-Carbó, A., del Hoyo-Meléndez, J. M., Doménech-Carbó, M. T. & Piquero-Cilla, J. Electrochemical analysis of the first Polish coins using voltammetry of immobilized particles. Microchem. J. 130, 47–55 (2017).Di Turo, F. et al. Archaeometric analysis of Roman bronze coins from the Magna Mater temple using solid-state voltammetry and electrochemical impedance spectroscopy. Anal. Chim. Acta 955, 36–47 (2017).Doménech-Carbó, A., Doménech-Carbó, M. T. & Peiró-Ronda, M. A. Dating Archeological Lead Artifacts from Measurement of the Corrosion Content Using the Voltammetry of Microparticles. Anal. Chem. 83, 5639–5644 (2011).Giumlia-Mair, A. et al. Surface characterisation techniques in the study and conservation of art and archaeological artefacts: a review. Materials Technology 25(5), 245–261 (2010).Robbiola, L. & Portier, R. A global approach to the authentication of ancient bronzes based on the characterization of the alloy–patina–environment system. Journal of Cultural Heritage 7, 1–12 (2006).Campbell, W. Greek and Roman plated coins, Numismatics Notes and Monographs 57, American Numismatic Society, New York (1933).Kallithrakas-Kontos, N., Katsanos, A. A. & Touratsoglou, J. Trace element analysis of Alexander the Great’s silver tetradrachms minted in Macedonia, Nuclear Instruments and Methods in Physics. Research B 171, 342–349 (2000).Catalli, F. Numismatica greca e romana. (Libreria dello Stato, 2003).Cope, L. H. The Metallurgical development of the Roman Imperial Coinage during the first five centuries. (Liverpool, 1974).Scriptores Historiae Augustae. Historia Augusta. (The Perfect Library, 2014).Vlachou-Mogire, C., Stern, B. & McDonnell, J. G. The application of LA-ICP-MS in the examination of the thin plating layers found in late Roman coins. Nucl. Instruments Methods Phys. Res. Sect. B Beam Interact. with Mater. Atoms 265, 558–568 (2007).Keturakis, C. J. et al. Analysis of corrosion layers in ancient Roman silver coins with high resolution surface spectroscopic techniques. Appl. Surf. Sci. 376, 241–251 (2016).Ingo, G. M. et al. Roman sophisticated surface modification methods to manufacture silver counterfeited coins. Appl. Surf. Sci. 1–11, https://doi.org/10.1016/j.apsusc.2017.01.101 (2017).La Niece, S. In: La Niece S. & Craddock, P. (Eds), Metal, Plating and Platination, Butterworth–Heinemann, London, 1993, p. 201.Anheuser, K. & France, P. Silver plating technology of the late 3rd century Roman coinage. Historical Metallurgy 36(1), 17–23 (2002).Anheuser, K. & Northover, P. Silver plating on Roman and Celtic coins from Britain– A technical study. The British Numismatic Journal 64, 22–32 (1994).Anheuser, K. Where is all the amalgam silvering? Materials Issues1996 in Art and Archaeology - V proceedings, Boston.Beck, L. et al. In NIM 269, 2011 and in Counterfeit coinage of the Holy Roman Empire in the 16th century: silvering process and archaeometallurgical replications, Archaeometallurgy in Europe III.Deraisme, A., Beck, L., Pilon, F. & Barrandon, J. N. A study of the silvering process of the Gallo-Roman coins forged during the third century AD. Archaeometry 48, 469–480 (2006).Giumlia-Mair, A. On surface analysis and archaeometallurgy. Nucl. Instruments Methods Phys. Res. Sect. B Beam Interact. with Mater. Atoms 239, 35–43 (2005).Tate, J. Some problems in analysing museum material by nondestructive surface sensitive techniques. Nuclear Inst. and Methods in Physics Research, B, 14 (1), pp. 20–23 (1986).Beck, L., Bosonnet, S., Réveillon, S., Eliot, D. & Pilon, F. Silver surface enrichment of silver-copper alloys: A limitation for the analysis of ancient silver coins by surface techniques. Nucl. Instruments Methods Phys. Res. Sect. B Beam Interact. with Mater. Atoms 226, 153–162 (2004).Pardini, L. et al. X-ray fluorescence and laser-induced breakdown spectroscopy analysis of Roman silver denarii. Spectrochim. Acta - Part B At. Spectrosc. 74–75, 156–161 (2012).Klockenkämper, R., Bubert, H. & Hasler, K. Detection of near-surface silver enrichment on Roman imperial silver coins by x-ray spectral analysis. Archaeometry 41, 311–320 (1999).Ponting, M., Evans, J. A. & Pashley, V. Fingerprinting of roman mints using laser-amblation MC-ICP-MS lead isotope analysis.Del Hoyo-Meléndez, J. M. et al. Micro-XRF analysis of silver coins from medieval Poland. Nucl. Instruments Methods Phys. Res. Sect. B Beam Interact. with Mater. Atoms 349, 6–16 (2015).Cesare Brandi. Il restauro. Teoria e pratica (1939–1986). (Editori Riuniti, 2009).Barberio, M., Veltri, S., Scisciò, M. & Antici, P. Laser-Accelerated Proton Beams as Diagnostics for Cultural Heritage. Sci. Rep. 7, 40415 (2017).Linke, R., Sehreiner, M., Demortier, G., Alram, M. & Winter, H. Non-Destructive Microanalysis of Cultural Heritage Materials. Comprehensive Analytical Chemistry 42, (Elsevier, 2004).Łojewska, J. et al. Recognizing ancient papyri by a combination of spectroscopic, diffractional and chromatographic analytical tools. Sci. Rep. 7, 46236 (2017).Meulebroeck, W., Wouters, H., Nys, K. & Thienpont, H. Authenticity screening of stained glass windows using optical spectroscopy. Nat. Sci. Reports 6 37726, 1–10 (2016).Martina, I., Wiesinger, R. & Schreiner, M. Micro-Raman Characterisation of Silver Corrosion Products: Instrumental Set Up and Reference. e-Preservation. Sci. Rep 9, 1–8 (2012).Rizzo, F. et al. Non-destructive determination of the silver content in Roman coins (nummi), dated to 308–311 A. D., by the combined use of PIXE-alpha, XRF and DPAA techniques. Microchem. J. 97, 286–290 (2011).Carl, M. & Young, M. L. Complementary analytical methods for analysis of Ag-plated cultural heritage objects. Microchem. J. 126, 307–315 (2016).Cepriá, G., Abadías, O., Pérez-Arantegui, J. & Castillo, J. R. Electrochemical Behavior of Silver-Copper Alloys in Voltammetry of Microparticles: A Simple Method for Screening Purposes. Electroanalysis 13, 477–483 (2001).Capelo, S., Homem, P. M., Cavalheiro, J. & Fonseca, I. T. E. Linear sweep voltammetry: a cheap and powerful technique for the identification of the silver tarnish layer constituents. J. Solid State Electrochem. 17, 223–234 (2013).Doménech-Carbó, A. et al. Detection of archaeological forgeries of Iberian lead plates using nanoelectrochemical techniques. The lot of fake plates from Bugarra (Spain). Forensic Sci. Int. 247, 79–88 (2015).Doménech-Carbó, A., Doménech-Carbó, M. T. & Peiró-Ronda, M. A. ‘One-Touch’ Voltammetry of Microparticles for the Identification of Corrosion Products in Archaeological Lead. Electroanalysis 23, 1391–1400 (2011).Doménech-Carbó, A., Doménech-Carbó, M. T., Montagna, E., Álvarez-Romero, C. & Lee, Y. Electrochemical discrimination of mints: The last Chinese emperors Kuang Hsü and Hsüan T’ung monetary unification. Talanta1 69, 50–56 (2017).Ager, F. J. et al. Combining XRF and GRT for the analysis of ancient silver coins. Microchem. J. 126, 149–154 (2016).Fawcett, T., Blanton, J., Blanton, T., Arias, L. & Suscavage, T. Non-destructive evaluation of Roman coin patinas from the 3rd and 4th century. Powder Diffraction, 1–10.Salvemini, F. et al. Neutron tomographic analysis: Material characterization of silver and electrum coins from the 6th and 5th centuries B.C. Mater. Charact. 118, 175–185 (2016).Ashkenazi, D., Gitler, H., Stern, A. & Tal, O. Metallurgical investigation on fourth century BCE silver jewellery of two hoards from Samaria. Sci. Rep. 7, 40659 (2017).Romano, F. P., Garraffo, S., Pappalardo, L. & Rizzo, F. In situ investigation of the surface silvering of late Roman coins by combined use of high energy broad-beam and low energy micro-beam X-ray fluorescence techniques. Spectrochim. Acta - Part B At. Spectrosc. 73, 13–19 (2012).Ingo, G. M. et al. Ancient Mercury-Based Plating Methods: Combined Use of Surface Analytical Techniques for the Study of Manufacturing Process and Degradation Phenomena. Accounts of Chemical Research 46(11), 2365–2375.Pouchou, J. L. & Pichoir, F.¨PAP¨ (ϕ–ρ–Z) procedure for improved quantitative microanalysis, in: Armstrong, J. T. (Ed.), Microbeam Analysis, San Francisco Press, San Francisco, pp. 104–106 (1985)

Metal alloys, matrix inclusions and manufacturing techniques of Moinhos de Golas collection (North Portugal): a study by micro-EDXRF, SEM–EDS, optical microscopy and X-ray radiography

"Article:820"A collection of 35 metallic artefacts comprising various typologies, some of which can be attributed to the Bronze Age and others to later periods, were studied to provide detailed information on elemental composition, manufacturing techniques and preservation state. Elemental analysis by micro-EDXRF and SEM–EDS was performed to investigate the use of different alloys and to study the presence of microstructural heterogeneities, as inclusions. X-ray radiography, optical microscopy and SEM–EDS were used to investigate manufacturing techniques and degradation features. Results showed that most of the artefacts were produced in a binary bronze alloy (Cu–Sn) with 10–15 wt% Sn and a low concentration of impurities. Other artefacts were produced in copper or in brass, the latest with varying contents of Zn, Sn and Pb. A variety of inclusions in the metal matrices were also found, some related to specific types of alloys, as (Cu–Ni)S2 in coppers, or ZnS in brasses. Microstructural observations revealed that the majority of the artefacts were subjected to cycles of thermomechanical processing after casting, being evident that among some artefacts different parts were subjected to distinct treatments. The radiographic images revealed structural heterogeneities related to local corrosion processes and fissures that seem to have developed in wear-tension zones, as in the handle of some daggers. Radiographic images were also useful to detect the use of different materials in one particular brass artefact, revealing the presence of a possible Cu–Sn solder.This work was funded by FEDER funds through the COMPETE 2020 Programme and National Funds through FCT— Fundação para a Ciência e a Tecnologia under the project UID/CTM/ 50025/2013 to CENIMAT/I3N. C2 TN/IST authors gratefully acknowledge the FCT support through the UID/Multi/04349/2013 project. EF acknowledges FCT for the grant SFRH/BPD/97360/2013. JF acknowledge FCT for the grant SFRH/BD/65143/2009. Part of this project has been done in the framework of the FCT project ENARDAS (PTDC/HISARQ/112983/2009).info:eu-repo/semantics/publishedVersio

Composition and electrochemical properties of natural patinas of outdoor bronze monuments

The present study concerns the chemical\u2013physical and electrochemical characterizations of the corrosion compounds formed on outdoor bronzes exposed in urban conditions. Here, we focused on the pale green patinas of surfaces directly exposed to the rainfall leaching. The investigation has been performed from scraped-off patina products of a well representative outdoor bronze monument (Monument to Francis Garnier, 1898) situated in Paris (France). The composition of the patina was analysed by energy dispersive spectrometry (EDS), coupled with SEM, and Raman spectroscopy. Structural characterization was conducted through high-resolution TEM (EDS coupled). The electrochemical reactivity of patina was investigated by cyclic voltammetry and EIS with a microcavity electrode in sulphate solution at pH 2 and 5.6 with time of immersion (up to 10 h). The bronze patina corresponds to a two-layer structure. The external layer is characterised by a marked selective dissolution of Cu and Zn of the alloy, which has been determined from the calculation of dissolution factors. The same phenomenon with the same amplitude has been evidenced on other bronze monuments used for comparison. The pale green patina is a complex mixture of crystalline copper hydroxisulphate and of amorphous/nanocrystal Sn-containing compounds. This patina is stable at pH 5.6 and reactive at pH 2 in relation with the dissolution of copper sulphate compounds in the acidic solution

The discourse about infraction act embodied embodied in the Statute of the Child and Adolescent

A pesquisa tem como objetivo analisar o discurso sobre o ato infracional materializado no Estatuto da Criança e do Adolescente (ECA, 1990) e nos outros artigos jurídicos que se relacionam ao tema, sob a perspectiva teórica e metodológica da Análise do Discurso Pêcheutiana e da Psicanálise lacaniana. Para essas duas áreas do saber, a linguagem é estruturada por um furo, apresentando como composição lógica a equivocidade e a ambiguidade. Seguindo essa concepção, primeiramente, analisamos o funcionamento do discurso do Direito, especificamente no que se refere ao conceito de lei, de infração e de sanção; na sequência, apresentamos o processo sócio-histórico sobre a transgressão na adolescência, conforme as legislações, ao mesmo tempo em que delimitamos o corpus da pesquisa (recorte dos artigos jurídicos). Consideramos que esta lei opera como um dispositivo de controle da prática de ato infracional e que o funcionamento do discurso do Direito mascara a estrutura faltante da Lei e da linguagem. Essas observações nos levaram a traçar o fio discursivo dos outros capítulos - o sujeito do direito, o sujeito do desejo e a forma-sujeito-, já que todo discurso não é sem sujeito. Analisamos as posições ocupadas pelo adolescente que comete o ato infracional na visão dos regulamentos jurídicos, que têm como finalidade estabilizar o funcionamento social. Na continuação, articulamos o sujeito do direito, o ato infracional e as medidas socieducativas como manifestações do discurso capitalista, onde a norma jurídica ganha um estatuto de fetiche, assim como as mercadorias. Ao supormos a existência do sujeito do desejo, não tomamos o ato infracional somente como produto e condição do contexto social e econômico, pois há a singularidade do autor do ato. Concluímos que as legislações não produzem um lugar Simbólico para o sujeito, apenas um lugar Imaginário, como conferem o Estado e o ECA ao ofertar a ideologia de um sujeito de direito e a forma-sujeito de pessoa em desenvolvimento. Desse modo, a criação dos termos ato infracional e medida socioeducativa são interpretadas como efeitos de sentido do eu idealizado proposto pela ideologia capitalista e pela concepção psicológica de desenvolvimento. Nas condições de produção do ECA o adolescente é concebido como alguém passível de ser educado e cujo lugar de sujeito do desejo é ignorado. Portanto, o ato infracional configura-se como um sintoma social e um mal-estar na sociedade pós-moderna e a medida socioeducativa apresenta-se como um fracasso no que diz respeito a uma normalização do sujeito.This research aims to analyze the discourse on infraction act embodied in the Statute of the Child and Adolescent (ECA, 1990) and other legal articles that relate to the theme, from the theoretical and methodological perspective of Pêcheutiana Discourse Analysis and Lacanian Psychoanalysis. For these two areas of knowledge, language is structured by a hole, presenting as logic composition the equivocality and ambiguity. First, we analyze the functioning of the discourse of law, specifically with regard to the concept of law, the offense and sanction; following, we present the socio-historical process of transgression in adolescence, according to the legislation, while we delimit the research corpus (clipping of legal articles). We believe that this law operates as a control device of the practice of an offense and that the operation of the discourse of law masks the missing structure of law and language. These observations led us to trace the discursive thread of the other chapters - the subject of the right, the subject of desire and form-subject - since all speech is not without a subject. We analyzed the positions occupied by the adolescent who commits the offense in view of the legal regulations, which are intended to stabilize the social functioning. In continuation, we articulated the subject of law, infraction and educational measures as manifestations of capital.ist discourse, where the legal norm gains a fetish status, as well as goods. By assuming the existence of the subject of desire, we do not take offense only as the product and condition of the social and economic context, because there is uniqueness of the author of the act. We conclude that the laws do not produce a symbolic place for the subject, just an imaginary place, as conferring the State and the ECA to offer the ideology of a \"subject of law\" and the form-subject \"developing person\". Thus, the creation of the terms offense and socio-educational measures is idealized sense of the idealized \"I\" suggested by capitalist ideology and concept of development. Inside conditions of production of the ECA, adolescent is conceived as someone capable of being educated and whose place of subject of desire is ignored. Therefore, the infraction act configures itself as a social symptom and malaise in postmodern society and the socio-educational measures constitute a failure when it comes to a normalization of the subject

Technological characterisation of early Medieval gilded copper hollow pendants (gombiky), from Mikulčice (Moravia) and Prague Castle (Bohemia)

International audienceGilded copper hollow spherical pendants known as gombiky (s. gombik) were examined to identify the technology of gilding and the material chosen as the substrate. The examined ornaments dating from the ninth and tenth centuries AD were recovered from elite graves of two major political, ecclesiastical and economic centres of the Early Medieval period located in the territory of the present-day Czech Republic: Mikulčice and Prague Castle, major sites of Moravia and Bohemia, respectively. Taking into account the state of degradation and possible bias due to earlier restorations, surface and bulk characterisation of the gilded material has been performed combining optical observation, X-ray radiography, metallography, scanning electron microscopy with energy-dispersive spectrometry (SEM/EDS analysis) and focused ion beam (FIB) milling mounted on FEG-SEM. The manufacturing procedure was reproduced by experimental archaeology. A detailed investigation of the gilded artefacts revealed several types of gombik construction involving different mounted elements, including the main body parts and the suspension system elements joined by hard soldering. The different constitutive parts are made with almost pure copper or low-purity copper. The systematic use of fire gilding (mercury amalgam gilding) was documented. Differences in the materials that were used and technical quality show the coexistence of finely produced objects by highly skilled and knowledgeable jewellers alongside more coarsely manufactured imitations. These variations are discussed in terms of different workshops in a possible relationship with their origin of manufacture