Paolo Piccardo

Manufacture of Eastern European decorative tin–bronze discs from twelfth century BC

During the European Bronze Age, flat discs with a variety of decorative elements were produced to be used most likely as either decoration attached to clothing or as parts of horse harnesses. The size and decoration differ according to region and period. The discs discussed here were all found in hoards deposited in a rather short period around 1200–1100 BC in Croatia, Bosnia and Austria. They were analysed to obtain information about their composition and manufacture, both of which may have changed in relation to increasing distance from the centre of distribution or supposed production as a result of copying, or might not have changed significantly if the discs were imported.

Software Design and Simulation of a DS/CDMA Multimedia Transmission System for Remote Video—Surveillance Applications

The most recent developments in the research concerning the Video—Surveillance reveal an increasing interest related to the systems operating in remote modality. The applications of such systems generally concern the video—surveillance of unattended environments. A local elaboration system acquires images by video sensors, it processes the images and it sends the elaborated information to a remote control centre. A secure and noise—robust transmission link for the critical information is required. In this work, an innovative software design technique of a DS/CDMA multimedia transmission system is presented, together with the visual results related to the multimedia transmission simulation.

On the Effect of Surface Treatment to Improve Oxidation Resistance and Conductivity of Metallic Interconnects for SOFC in Operating Conditions

Due to the reduction of operating temperature from 1000°C to 800°C, chromia forming alloys are the best candidates for interconnects in Solid Oxide Fuel Cells (SOFCs). These interconnects have to be operational in service conditions, at 800°C in air (cathode side) and in humidified hydrogen (anode side). The performance of the interconnect stainless steels is limited by the oxide scale formation (chromia), the low electronic conductivity of this scale and the possible volatility of chromium oxides. In the field of high temperature oxidation of metals, it is well known that the addition of a nanometric layer made of reactive element oxide such as, La2O3, Nd2O3 and Y2O3 by MOCVD (Metal Organic Chemical Vapor Deposition) on alloy surface resulted in an important improvement in the high temperature oxidation resistance. These coatings are made on metallic alloys in order to form perovskite oxides such as LaCrO3, NdCrO3 and YCrO3, which are expected to present a good conductivity at 800°C in air. However, this temperature looks somewhat too low to guarantee the formation of perovskite oxides and thus to improve the oxidation resistance and electrical conductivity. In fact, XRD analyses revealed that for Y2O3 coatings, perovskite oxides were not formed after oxidation in air at 800°C for 100 hours. The goal of this study is to perform pre-oxidation at 1000°C for 2 hours in air under atmospheric pressure on coated Crofer22APU to pre-form perovskite phases. The so-prepared perovskite were tested in a thermobalance in air. Experiments performed in H2/10%H2O under 150 mbar at 800°C validated the coating influence from the anode side as well as the cathode side. The corrosion products were analyzed after 100 hours ageing at 800°C by SEM, EDX, and XRD. ASR (Area Specific Resistance) was measured for the same times and temperature in air.

Artistic patinas on ancient bronze statues

Abstract: ‘Artistic/intentional’ patina is a surface layer intentionally produced by an artist or a specialized professional on a metallic artwork with aesthetic or practical purposes. From the science of surfaces point of view the ‘artistic’ patina could be considered as an interface between the metallic substrate and the external environment and therefore affecting, depending on its physical and chemical peculiarities, the corrosion process. In order to understand how the ‘artistic’ patina behaves inside the exposure environment, an experimental activity was carried out: the study of the data collected with the application of different analytical techniques contributed to a more pertinent knowledge of the characteristics of metallic works of art which, in turn, leads to a restoration process respecting their real nature.

A Characterisation Study on Modern Bronze Sculpture: The Artistic Patinas of Nado Canuti

ABSTRACT Artistic patination is a traditional colouring technique for metal sculpture, employed by artists in ancient and modern times for aesthetic purposes. Today, knowledge of the artistic value and the chemistry of this superficial chromatic layer, called ‘artistic patina’, can be successfully acquired through a close collaboration between living artists, foundry artisans, and scientists. Starting from several interviews with the Italian artist Nado Canuti and foundry artisans, specific information was gathered about patination methods and the artist’s attitude towards materials restoration. Afterwards, the patinas most used by Canuti were reproduced to study their nature before any ageing or degradation. Their chromatic values, morphologies, and compositions were studied employing a range of techniques such as colour measurements, scanning electron microscopy with energy dispersive X-ray spectroscopy, and micro-Raman spectroscopy. The collected data revealed the formation of main compounds (cuprite, cassiterite, rouaite, chalcocite, isocubanite, and ferroxyhite) and additional compounds (atacamite and CN-containing compound). The scientific results, as well as the artist’s statements concerning the patinas’ significance, maintenance, and conservation, will contribute towards the future care and preservation of Canuti’s sculptures.

Effect of YSZ Coatings as Diffusion Barrier between Glass Sealing and Steel

In this work three experimental glass compositions have been applied and tested on ferritic stainless steel (FSS) substrates with and without yttria-stabilized zirconia (YSZ) coating deposited by plasma spraying. Samples have been tested at 780 °C on static air up to 1000 hours to investigate the materials compatibility, stability and interactions at the interfaces. Microstructural changes and migration of elements have been characterized post-experiment in cross-section by means of scanning electron microscopy and energy dispersive X-ray analysis. Two of the tested compositions resulted well adherent on the metal substrate for the whole test duration and the interface evolved with the formation of a stable Cr, Mn-rich layer due to the steel oxidation. The application of YSZ allowed all the glass composition to bond to the substrate and effectively act as a diffusion barrier limiting the diffusion of the substrate elements.