Chemical and structural properties of ancient metallic artefacts: multitechnique approach to study of early bronzes

Abstract

tombs of the Necropolis of Chiavari in Italy. A heterogeneous microstructure of the bronze P. PICCARDO was observed, exhibiting a wide range of grain sizes, and a predominant a-phase solid solution containing a/d and a/e eutectoid phases decorated with a high density of inclusions. M. R. PINASCOT he composition of grain boundary surfaces was determined, using scanning Auger micros-E. STAGNO copy (SAM), on specimens fractured in vacuo. T he extent of tin segregation at the grain M. G. IENCO boundaries was 3-5 times greater than that in the grain interiors. Copper rich sulphides R. MAGGIoccasionally containing the oligoelements (iron and lead) were identified as the predominant type of inclusions formed at the grain interfaces and within the grains. Analysis of the corrosion patina at the surface of the bronze artefacts was conducted by combining X-ray diVraction, scanning electron microscopy with energy dispersive X-ray analysis, and SAM. T he patina was found to exhibit a multilayered structure and a complex chemical composition forming various crystallographic phases including malachite, cuprite, and copper-tin oxide. Corrosion of the underlying bronze matrix proceeded along the grain boundaries, where the sacrificial corrosion of tin reacting with diVused oxygen and chlorine was identified. T he results of this study have been used to clarify the metallurgy and manufacturing processes of the examined finds, and to evaluate the state of their degradation.

On‐site Raman and XRF analysis of Japanese/Chinese bronze/brass patina – the search for specific Raman signatures

“…. Note that some authors point out that the tin oxide of the patina was hydrated, which can also explain the modification of the Raman spectrum. Furthermore, because a part of the tin oxide remains embedded in the alloy, this part is not detectable by the Raman technique…”

“…Studies on modern bronzes, copper alloys and replica show the complexity of the oxidation layer (actually, at least three layers, including the upper metal layer with oxide inclusions). Patina of Egyptian, Greek and Roman bronzes are also extensively studied . The composition of a series of antique Chinese vessels ( jia , jue , gu , zun , pou , you , fang yi , ding and yu shape) and the lead isotope ratio have been reported by Mei et al .…”

Surface Characterization of the Corrosion Product Layer Formed on Synthetic Bronze in Aqueous Chloride Solution and the Effect of the Adding of Juniperus Communis Extract by X-Ray Photoelectron Spectroscopy Analysis

“…XPS analysis is used to characterize the alteration process. Robbiola et al [34][35][36][37][38][39][40] proposed two functions to prove the selective copper dissolution:…”

Nanoscale Aspects of Corrosion on Cultural Heritage Metals

“…The outdoor corrosion of ancient "bronzes" (Cu-Sn alloys with sometimes significant quantities of Zn and Pb), conducts to the formation of a protective patina of about 20-50 µm of thickness. An important number of studies was dedicated to understand the nature of these patinas that have similarity with the behaviour of pure copper but differs from it because of the presence of alloying elements (Selwyn et al 1996;Robbiola et al 1998;Spoto et al 2000;Ingo et al 2006;Chiavari et al 2007). Patina can contain both Cu-rich and Sn rich compounds, mainly cuprite (Cu 2 O) or cassiterite (SnO 2 ).…”