Showing papers on "Bronze published in 2012"

A new interpretative approach to the chemistry of copper-alloy objects: source, recycling and technology

Abstract: The metal composition of bronze alloys has been routinely examined as a means of inferring the source of the ore. But bronze is recycled, and the quantity of some components, such as arsenic, is depleted every time the alloy is melted down. Since the Early Bronze Age of the British Isles was largely supplied from a single mine on Ross Island, Co. Kerry, tracking arsenic content shows the number of re-melts and this gives the object a biography and a social context. Applying this ingenious new procedure to their large database, the authors also winkle out other sources of supply and new insights about the technology involved.

The characterization of Sn‐based corrosion products in ancient bronzes: a Raman approach

Abstract: The characterization of corrosion patinas on bronzes is preliminarily connected to the determination of proper conservation strategies. Moreover, it also provides an essential contribution to the comprehension of the mechanisms of formation of patinas. Concerning the last aspect, several studies highlighted that bronze corrosion behaviour cannot be assimilated to that of pure copper. In particular, decuprification and relative enrichment of tin in the corrosion layers were observed. Tin therefore, together with its insoluble salts, plays an important role in the mechanism of formation of bronze patinas. Thus, the characterization of Sn-based corrosion products becomes fundamental, although remaining quite problematic. This work reports several case studies where Sn-based corrosion products grown in bronzes have been identified, thanks to the hyphenated system scanning electron microscopy–energy dispersive spectrometry–Raman structural and chemical analyser. Combining the main characteristics of these techniques, different Sn-containing compounds, mainly crystalline and nano-sized tin dioxides, were detected in bronze patinas exposed to different environments (to the atmosphere, in both natural and accelerated ageing conditions, and to the soil). The main issues regarding the interpretation of Raman spectra of these compounds are presented and discussed. Copyright © 2012 John Wiley & Sons, Ltd.

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

Abstract: The assignment of Asian bronzes and brasses is difficult because the copies of ancient pieces have been made a long time ago in different countries. A selection of 30 Japanese and/or Chinese bronzes/brasses are studied on-site in the storage and exhibition rooms of the Cernuschi Museum, in Paris, using portable Raman and X-ray fluorescence spectrometers. Attempts are made to identify specific Raman signatures of the patina to detect similarity in a nondestructive procedure. X-ray fluorescence measurements allow an identification of two brass artefacts and different types of bronze, including lead-rich and mixed lead–tin–zinc-rich compositions. The following phases are identified: CuO, Cu2O, Cu2S, tin oxides, ZnO, Cu3(OH)4SO4, Cu4(OH)6SO4, 3PbOPbSO4 H2O, PbSO4/PbO, Pb(AsO4)3Cl, HgO/HgS. Relics of the mould, retained as concretions at the artefact surface are also identified: TiO2, SiO2, and different soda(−lime) glasses. Patina with very similar colour and habit may have different Raman signatures. This study offers tools to classify the artefacts in a noninvasive way. Copyright © 2011 John Wiley & Sons, Ltd.

Studies on properties of as-cast Al6061-WC-Gr hybrid MMCs

Abstract: Aluminum (Al) alloys started replacing cast iron and bronze alloys in the manufacture of wear-resistant parts and are materials of interest owing to their low density, higher strength to weight rat...

Effects of Ca-substitution on structural, dielectric, and ferroelectric properties of Ba5SmTi3Nb7O30 tungsten bronze ceramics

Abstract: Effects of Ca-substitution on the crystal structure and dielectric properties were investigated for Ba5SmTi3Nb7O30 tungsten bronze ceramics. The tetragonal tungsten bronze structure in space group P4bm was determined in Ba4CaSmTi3Nb7O30 ceramics, which was the same for Ba5SmTi3Nb7O30. The c-axis off center displacement in both B1 and B2-sites for Ba5SmTi3Nb7O30 was slightly larger than that in BaCaSmTi3Nb7O30, while the distortion of Ti/Nb(2)O6 octahedra in Ba4CaSmTi3Nb7O30 was obviously suppressed compared with that in Ba5SmTi3Nb7O30. Though there were also two dielectric anomalies observed in Ba4CaSmTi3Nb7O30, the relaxor ferroelectric nature was changed to the normal ferroelectric one, and both the endothermal peak in differential scanning calorimetry curve and the significant thermal hysteresis of the phase transition confirmed the first order ferroelectric transition. These results indicated that the ferroelectric nature of Ba4CaSmTi3Nb7O30 was more close to that in Ba4Sm2Ti4Nb6O30, and it could be c...

Raman investigation of artificial patinas on recent bronze‒part II: urban rain exposure

Abstract: Patinas form spontaneously on copper and high copper alloys when exposed to humidity and air. They usually protect the underlying metal from corrosion. Bronze is often chemically patinated by artists to achieve an antique appearance. However, in the case of chemical patinations on bronze, there is a lack of studies about their change over time during exposure to different types of environments. Recent types of bronze, brown patina and two green type patinas (green chloride and green nitrate patina) applied over a brown patina, were selected for testing. The aim of the present study was to monitor the transformation process of chemically formed patinas and of the bronze itself after exposure to simulated urban acid rain, for a period of 35 days. The structures of the patina and corrosion products were characterized by scanning electron microscopy (SEM) and Raman spectroscopy. Three differently coloured patinas were scraped off from the bronze statue of the poet France Preseren, two green type patinas and one brown type, to predict the probable influences of the environment, the base alloy and previously used patination techniques. Copyright © 2012 John Wiley & Sons, Ltd.

Archaeometallurgical characterization of hellenistic metal objects: the contribution of the bronze objects from rishon le‐zion (israel)*

Abstract: An archaeometallurgical analysis is presented of 14 bronze artefacts retrieved from an Early Hellenistic–period farmstead in controlled archaeological excavations at Rishon Le-Zion, Israel, and dated to the first quarter of the third century bce according to coins and pottery vessels. The bronze assemblage includes a needle, pins, spatulas and fibulas. The aims of the research are to determine the composition, microstructure and manufacturing process of these artefacts, and to discover their place of production. This will provide a better understanding of Hellenistic technological abilities and material culture. The examination included optical microscopy, microhardness, SEM including EDS, and XRD. The results show that the collection consists of Cu–Sn binary alloys, with evidence for a controlled alloying process and the absence of recycling. Furthermore, the microstructure of the objects indicates that all artefacts were produced by a cold-working process. Moreover, the manufacturing process of the rectangular cross-section fibulas included sophisticated joining techniques of copper and iron.

On some south levantine early bronze age ceramic ‘wares’ and styles

Abstract: Studies on pottery of the south Levantine Early Bronze Age (Early Bronze Ages I, II and III) often use terms such as ‘wares’ to designate specific types of ceramics identified with regional and chronological niches in the archaeological record. While some such designations appear to be valid, as they refer to groups of objects defined by very specific parameters, others represent broad categories with poorly defined parameters. This paper presents a proposal for some specifically defined groups, traditions of ceramic production called ‘wares’ and ‘styles’, with indications of their temporal and regional distributions. It further suggests abandon- ing some commonly used designations that offer too little specificity, thus making them less than useful for archaeological research and discussion.

Bronze in Archaeology: A Review of the Archaeometallurgy of Bronze in Ancient Iran

Abstract: The history of metals and metallurgy is rooted in the history of civilizations as the "Archaeometallurgy" and has been a subject of great interest for over a century. Due to the relatively good preservation of metallic goods and the modern values related to metals, metal artefact typologies often served as the very basis for prehistoric sequences during the late 19th and early 20th centuries. In many ways, it was V. Gordon Childe who placed metallurgical technology at the front, arguing as he did for the roles of "itinerant metal smiths" and bronze production in the rise of social elites and complex societies. Childe was also one of the first to systematically argue for the transmission of metallurgy from the Near East to the Eurasia (Thornton & Roberts, 2009). On the other hand, many of the artefacts which excavated, as well as some of the metallurgical talent being practiced are standing examples that depict the superior metallurgical skills used by human. Archaeometallurgical investigations can provide evidence about both the nature and level of mining, smelting and metalworking trades, and support understanding about structural and technical evidences. Such evidence can be essential in understanding the economy of a settlement, the nature of the industry and craft, the technological capabilities of its craftsmen as well as their cultural relations. In order to achieve such data, it is obvious that archaeometallurgical discipline has considered at each stage of archaeological and historical investigations in the field of ancient metal working.

Rock Art and Religion The sun journey in Indo-European mythology and Bronze Age rock art

Abstract: In this article I carry out an analysis of the sun journey in Bronze Age rock art in south Scandinavia. The story is based upon a widely shared Indo-European myth about the sun maiden and her twin brothers and helpers, the Divine or Heavenly Twins, who in disguise of ships and horses come to her help so that the sun can rise in the morning. This myth can be illustrated by combining Bronze Age iconography, bronze figurines, burials, hoards, and rock art (Kristiansen and Larsson 2005, fig. 139). Here I wish to explore if scenes referring to the sun journey can be identified in rock art alone. I apply the method of identifying singular motifs that relate to the overall narrative of the journey of the sun. On figures 1.6 to 1.12 I have selected and combined episodes from various rock art panels that refer back to the original mythological narrative of the sun journey. Although there is some regional variation it can be demonstrated that Bronze Age rock art in Scandinavia contains scenes from the shared Indo-European myth about the sun journey.

The Long Life of a Dead King: A Bronze Statue from Hazor in Its Ancient Near Eastern Context

Abstract: A Middle Bronze Age gold-coated bronze statue of a seated king found in a Late Bronze Age context on the acropolis of Tel Hazor is interpreted as an old icon of a dead king whose image was still me...

Characterization of Egyptian bronze archaeological artifacts

Abstract: This paper presents the results of in situ non-destructive X-ray fluorescence determination of the chemical analysis of a collection of ten bronze statues that are on display at the Egyptian museum of Cairo. The statues are from the late period of the ancient Egyptian history. In addition, destructive technique X-ray diffraction analysis was applied on 11 damaged archaeological objects to determine the corrosion products and the alloy compositions. Specimens of the latter objects were subjected to metallographic examinations to determine the microstructure of the alloy. Surprisingly, the results indicated that all ten statues and 10 of the 11 damaged objects were made of lead – bronze alloy; the percentage of the lead varied from 3.43 to 18.04, the tin varied from 2.53 to 10.67. The chemical composition of the patina on eight damaged objects is essentially composed of (Cu2O) cuprite for all objects in addition to other compounds such as (SnO2) cassiterite in two objects, (PbCO3) cerussite in three other objects and (Cu2(OH)3Cl) atacamite or (Cu(OH)3Cl) paratacamite in two other objects. The formation of chlorides and carbonate resulted from the interaction between surrounding environment and the alloy. The results of the metallographic examinations indicated a non-homogenous structure and the increase of the lead content increases the globular lead particles. In spite of this condition, the galvanic corrosion tendency when the alloy is exposed to moist air or soil is not possible as lead compounds are electrically insulating. Another advantage for using leaded bronze in making statues is being heavy and thus leads to stability. Copyright © 2012 John Wiley & Sons, Ltd.

An investigation into the cause of corrosion on indoor bronze sculpture

Abstract: Corrosion noted on a number of nineteenth and twentieth century indoor bronze sculptures in the collection of the National Gallery of Canada was the cause for a major condition survey of its Canadian, American, and European bronzes. The results led to a comprehensive study, which included material analysis. This article outlines the steps undertaken to determine the extent and type of corrosion, its possible cause(s), and potential remediation. The survey included 136 bronzes, of which 40 were selected for an in-depth study. Indoor air quality tests of the current building, housing the collection since 1988, were carried out. The dossiers and database records of the selected sculptures were reviewed to investigate their condition, treatment, and storage history. The metal, patina, and corrosion products were subjected to analysis. More areas of corrosion were generally associated with predominantly green patinas and chloride-containing compounds identified in either patina or corrosion samples. Th...

Identification of forgeries by measuring tin isotopes in corroded bronze objects

Abstract: The reliable identification of fakes consisting of bronze often presents problems, because traditional methods such as stylistic studies, optical microscopy, chemical analysis or X-ray diffraction of the corrosion may not be conclusive. We present a method that is based on the comparison of the tin isotope ratios 122Sn/116Sn and 117Sn/119Sn in the metal and in the adherent corrosion layer. An artificial patina is usually generated within a short time period. It has been observed that such a procedure leads to a depletion of the light tin isotopes in the corrosion layer, while in naturally corroded authentic archaeological objects no isotopic fractionation has been detected. The method has also been applied to archaeological objects and it could be confirmed, among other examples, that the famous ‘Sky Disc of Nebra’ is authentic.

Nourishing a structured world with living metal in Bronze Age Europe

Abstract: For over a thousand years, European peoples intently deposited bronze artefacts into the earth. This essay examines the motivation for doing so from a cosmological perspective. It argues that depositions were believed to support universal life processes and assure availability of resources for people and polities by literally “feeding“ universal creative energies. It is suggested that metallic ores were considered living materials that grew within the earth in locales usually at some distance from a given society and that they were embued with generative force that would be returned to the earth when metal was deposited within it. The vital life force was tangibly evidenced by metallurgical processes and uses and especially by the blue-green patina that copper and copper alloys acquire when the metal is exposed to moist conditions.

Leaded-tin bronze destruction mechanism

Abstract: The paper is devoted to comparative analysis of the structure and mechanical properties of leaded-tin bronze with lead inclusions of various morphologies. In order to obtain lead inclusions of certain morphology, casts are cooled at certain velocities. Low cooling velocities cause spheroidizing of lead inclusions, whereas high ones give prolate inclusions with torn uneven surface.

Micro‐structural and micro‐chemical composition of bronze artefacts from Tharros (Western Sardinia, Italy)

Abstract: The present work reports the results of the SEM-energy dispersive spectrometry, X-ray diffraction (XRD), XPS and optical microscopy (OM) investigations performed to identify the corrosion products nature, i.e. the patina, grown on bronze common use artefacts found during excavations carried out at Tharros (on the west coast of Sardinia, Italy). The micro-chemical investigations of the patina revealed the structure and the chemical composition of the stratified corrosion layers, where tin depletion phenomenon has been observed within some cases of a surface enrichment of lead combined with elements coming from the soil such as Cl and P and mixed with other burial elements such as Ca, Si, Fe, Si and Al. The presence of soil elements was also confirmed by XPS investigations that evidence from the lineshape analysis and Binding Energy (BE) values of Cu 2p, Sn 3d and Pb 4f photoemission signals that these elements are mainly present in their maximum oxidation states on the surface. The surface information is confirmed by OM and XRD results that evidence also the presence of copper trihydroxychlorides. In the inner layers, OM, SEM-energy dispersive spectrometry and XRD results disclose the presence of Cu (I) compounds such as cuprite (Cu 2O) and nantokite (CuCl), the latter being the specie that induces the cyclic and self-sustaining degradation process commonly defined 'bronze disease'. The micro-chemical and micro-structural informations demonstrate the strict interaction between soil components and corrosion products that form different compounds as a function of the local characteristics of the soil and of the chemical composition and metallurgical features of the Cu-based alloys

Reconstructing a Bronze Age hidden landscape: geoarchaeological research at Tratturo Canio (Italy, 2009)

Abstract: In 2009, the GIA dug a trench alongside the Archaic to Roman rural temple sanctuary of Juno at Tratturo Canio in the ager of Setia in the Pontine plain (Lazio, Italy), in order to investigate the older Bronze and Iron Age remains that had been reported in Italian probing excavations in the mid-1980s. The trench, up to 2 m deep, yielded a wealth of stratigraphic and environmental data as well as much pottery and bone from a Middle Bronze Age habitation layer. This article describes the work, the finds, and the phased geoarchaeological interpretations and reconstructions that were based on the sedimentology and environmental samples. The work is part of the Hidden Landscapes Project which aims to show that there is a well-preserved protohistoric landscape buried beneath the Pontine plain.

Davis bronze-steel composite bimetallic bearing material and manufacturing method thereof

Abstract: The invention provides a nickel bronze-steel compound double metal bearing material and a manufacture method thereof, wherein the base layer is made of low carbon high grade plain carbon steel material and the surface is made of nickel bronze alloy. The nickel bronze alloy is sintered on the surface of the low carbon high grade plain carbon steel material. The nickel bronze alloy comprises the following chemical components in percentage by weight: 1-16% of nickel, 5-9% tin, 0-2% of zinc, 72.5-94% of copper and impurities as the balance with the total content thereof no more than 0.5%. The nickel bronze-steel compound double metal bearing material is high in both strength and hardness and can bear a very high load. The nickel bronze-steel compound double metal bearing material is also high in stress corrosion resistance and chemical corrosion resistance and can be used in various environments. Meanwhile, the nickel bronze-steel compound double metal bearing material is low in friction coefficient and can reduce the occurrence of accidents caused by abrasion occlusion. Compared with the traditional lead bronze bearing material, the nickel bronze-steel compound double metal bearing material does not contain Pb and complies with environmental requirements. Thus, the nickel bronze-steel compound double metal bearing material maintains the excellent bearing performances of nickel bronze alloy, while the cost is greatly reduced.

Brass before bronze? Early copper-alloy metallurgy in China

Abstract: An artifact of brass apparently predating the “Bronze Age” was unearthed at Jiangzhai site (China, Shaanxi Province, 4700-4000 BC). So that we might infer the probable metallurgical process for the production of this early brass, we performed simulation experiments that, in turn, involved two widely differing methodologies. For convenience we refer to their metallurgical routes as “melting” on the one hand, and “solid-state reduction” on the other. Clearly, either of these processes could have supplied the starting material for the subsequent development of metal production leading to a casting technology, which is a highly significant step in the technical progress of metallurgy, whether of copper, brass, bronze or arsenical bronze. The distribution of zinc and lead in the brass artifact of the fifth millennium BC and several brass specimens produced by simulation experiments were analyzed by μ-X-ray fluorescence at the Shanghai Synchrotron Radiation Facility (SSRF). The results suggest that the archaeological brass artifact utilized alloy produced by a solid-state reduction process. This result is consistent with an indigenous origin in China.