Tailored analytical strategies for the investigation of metallic artefacts from the Ayanis Fortress in Turkey

Abstract

A noteworthy number of metallic artefacts dating back to 673-645 BC have been found during excavations in the Ayanis Fortress, near the lake of Van. They are large bronze shields, quivers, helmets, arrows and plates, some of which are decorated with cuneiform inscriptions, and demonstrate a high-level quality of technological competence reached by the ancient craftsmen of Ayanis during the reign of King Rusa II. The artefacts have been studied from a microchemical, micromorphological and microstructural point of view by means of different techniques, from optical microscopy to scanning electron microscopy (SEM), to X-ray diffraction.Microchemical and microstructural investigations showed metallurgical features of the bronze artefacts and of the corrosion products' layered structures that can be explained in terms of manufacturing processes (repeated cycles of mechanical work and annealing thermal treatments) and environmental context (presence of high amounts of chlorides in the soil that preferentially attack the bronze along the grain boundaries). In particular, the repeated cycles of mechanical work and annealing thermal treatments were carried out to restore the ductility and the malleability of the alloy, thus inducing the crystallisation and the growth of flattened grains as well as impurities segregation phenomena along grain boundaries.

Underwater corrosion of metallic heritage artefacts

“…The problems of conservation and restoration of metallic artefacts coming from underwater sites, both marine and, to a less extent, freshwater sites, show only some similarities with the ones faced by artefacts that have experienced long-lasting burial in soil [12][13][14][15][16][17]. In fact, all the artefacts recovered from the sea, mainly from warm waters such as the Mediterranean and Caribbean Sea, independently of their chemical composition, are encrusted with thick layers of calcium carbonate, magnesium hydroxide, corrosion products, in the specifi c case of metallic artefacts, sand, clay and various forms of marine life such as shells, coral, barnacles and algae.…”

Surface modification plasma treatments of PMMA optical fibres for sensing applications

“…The research on the conservation of works of art proceeds in two different but interconnected directions. On one side, the analytical characterisation performed to understand the materials properties, [16][17][18] and on the other side, tests for assessing the complexity of the risks (physical, chemical and biological) of the environment where the artworks are exhibited, such as museums, galleries, churches, or microenvironments such as showcases and storage boxes, with the ultimate goal of developing tailored strategies for conservation. [19,20] Increasingly, it has been recognised that atmospheric gases cause the degradation of historic and archaeological artefacts.…”

Surface and interface investigation of electrochemically induced corrosion on a quaternary bronze

“…Artefacts are mainly endangered by ‘bronze disease’ when the pitting corrosion is developed at high %RH and chloride supply . Moreover, phase segregation phenomena contribute to surface heterogeneity and induce local galvanic cells . The binary Cu‐Sn bronzes exhibit selective dissolution of copper, the brasses with a Zn content above 14 wt% are prone to dezincification, while Pb, when present, is immiscible with alloy phases leading to rapid local corrosion and formation of passive compounds.…”