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1.
《文物保护研究》2013,58(3):148-152
AbstractMineralogical changes which occur during the reaction of copper(II) chloride with carbonate in aqueous solution have been investigated, and compared with those involving copper(I) chloride, nantokite, CuCI, and copper artifacts coated with malachite, CU2CO3(OH)2 The reactions observed and the products obtained are seen to have implications with respect to the use of aqueous sodium carbonate solutions to stabilize archaeological copper objects. The frequent observation of the mineralogically rare species chalconatronite, Na2Cu(CO3)2·3H2O, on the surface of treated objects is readily explained by known reaction chemistry. Its formation can be minimized by washing the object after treatment. 相似文献
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《文物保护研究》2013,58(2):100-106
AbstractThe paper discusses the methodology adopted for and the results derived from a pilot project to conserve the lead and lead alloy communion tokens in the collections of St Andrews University. For the project a new conservation process, ‘potentiostatic reduction’, was developed, involving reduction of the tokens at ?1·2V vs. SCE (saturated calomel electrode) in 0·5M H2SO4, The aim of the pilot project was to test the effectiveness of the new process in tackling a largescale conservation problem by observing its effects on a wide range of tokens made of various alloys and suffering from varying degrees of corrosion. The results of the pilot project indicated that potentiostatic reduction is as effective as standard electrolytic reduction. Since the new technique greatly reduces the time required for the conservation of individual artifacts, there are substantial savings in conservation costs. 相似文献
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《文物保护研究》2013,58(2):139-142
AbstractAlkaline dithionite treatment has been recommended for use on copper and its alloys. The efficacy of this procedure is confirmed through the conservation of several small bronze artifacts from Tel Nami, Israel. Because Tel Nami is located near the Mediterranean Sea, the bronze artifacts suffer from cuprous chloride contamination. Alkaline dithionite is the preferred treatment because of its ability to remove chlorides while consolidating corroded artifacts. The conservation of the Tel Nami artifacts indicates that treatment time for small objects ranges from two to five days. An experiment with bronze Chinese coins confirms that some metal is lost to solution when using alkaline dithionite; however, the loss is minimal in comparison to the overall success rate for treating ancient bronze artifacts. 相似文献
4.
《文物保护研究》2013,58(4):264-272
AbstractThe removal of calcareous accretions from archaeological bronzes can be a difficult step in their conservation. Chemical cleaning with chelating agents might be an alternative to mechanical methods. In this study the use of the chelating agent sodium tripolyphosphate (STPP) was examined to determine whether it is effective in discriminating between calcium carbonate and copper patina, and non-corrosive to copper alloys in the presence of air. Comparative experiments with STPP and disodium ethylenediamine-tetraacetate (Na2-EDTA) were carried out on synthetic malachite, cuprite, calcium carbonate, naturally polished malachite surfaces and sheets of bronze and brass. In addition to the properties of the chelating agent, the solubility of the salts and the pH values of the solutions are crucial factors in the removal of compounds of low solubility. The quantity of metal ions dissolved, estimated by atomic absorption spectral analysis and scanning electron microscopy, showed that the calcareous accretions could be removed satisfactorily, but STPP also dissolved constituent parts of the patina, such as malachite and cuprite, and may harm bronze or brass. Compared to Na2-EDTA, STPP is less effective in dissolving calcium carbonate. It is less harmful to the patina and base metal, but may lead to patination of the underlying metal. 相似文献
5.
A technical study was conducted on a group of copper alloy artifacts excavated from the burial tumulus of Lofkënd (fourteenth–ninth century BCE) to identify the alloy compositions and methods of manufacture. The surface corrosion was also examined in order to understand the diagenetic processes affecting the preservation of the finds and their condition. Portable X-ray fluorescence spectroscopy, metallographic examination, and X-ray powder diffraction (XRD) analysis were used to characterize the alloy composition and identify the corrosion products present. XRD analysis showed the presence of brochantite (Cu4SO4(OH)6) on five of the metallic artifacts. Brochantite is not commonly reported on archaeological bronzes from terrestrial sites, but is more readily found on copper alloy objects exposed to sulfur pollutants in the air or soil. The possible conditions that could have led to the formation of this corrosion on the bronzes from Lofkënd are discussed in the context of the particular burial environment found at the tumulus. 相似文献
6.
《文物保护研究》2013,58(3):203-209
AbstractTo inhibit the corrosion of lead objects and lead in high-lead bronzes, particularly in the presence of organic emanations from wood, paint, etc., and/or high humidity, is a difficult conservation problem. A method to prevent corrosion of lead in copper objects was therefore developed using benzotriazole (BTA). The most appropriate treatment method for the conservation of the objects was to immerse them in neutral BTA solution, for which a 0.5% (w/v) concentration of BTA was enough. For bigger objects, three or four coats of 1.0% solution applied by brushing were equally effective. The method was used successfully for the conservation of some ancient copper coins and bronze sculptures containing high amounts of lead; it can also be used to inhibit corrosion of lead objects. 相似文献
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ABSTRACTTwo Spiritelli attributed to Donatello have been extensively studied from a technical point of view, including X-radiography, alloy analysis, characterization of the core, and visual observations on the interior and exterior of the statues. The results of this technical study reveal how the two statues were cast and document the artist’s technical choices. These new insights offer additional information to address questions regarding their attribution, production context, and conservation history. First, the technical study confirmed that the statues were made by the same workshop and argues against the prior proposal of different attributions for the two figures. Second, the results strongly suggest that the statues have never been separated since they were taken off Luca Della Robbia’s Cantoria. Finally, study of the two Spiritelli offers further evidence of the heterogeneity and ingeniousness of Donatellos bronze artistic production, and contributes to the ongoing debate whether the artist himself was involved in the technical aspects of his sculpture. 相似文献
8.
《文物保护研究》2013,58(3):274-282
AbstractA study of the composition and phase distribution of the corrosion layers on three ferrous objects, excavated at K2 (Bambandyanalo), an archaeological site in South Africa, was conducted. The objective of the study was to obtain information that can contribute to conservation procedures to be performed on the iron artefacts from this site. Examination of cross sections by means of energy-dispersive X-ray spectroscopy coupled to a scanning electron microscope (SEM–EDX), X-ray powder diffraction (XRD), and micro-Raman spectroscopy revealed the same corrosion composition and structure for all the objects under study, namely an internal layer adjacent to the metal surface with ghost inclusions and an external layer containing quartz grains. The study also revealed that the presence of magnetite (Fe3O4), maghemite (γFe2O3), and lepidocrocite (γ-FeOOH) within the internal layer is the only difference between the chemical compositions of iron corrosion products within the two layers. The results also made it possible to retrace the corrosion history during burial and long-term storage. 相似文献
9.
ABSTRACTChalconatronite, Na2[Cu(CO3)]2·3H2O, is formed as a corrosion product when copper alloys are exposed to sodium carbonate solutions in the air. This also happens when metals come into contact with corroding soda glass which forms alkaline surface films in reaction with humidity from clean air. More often, substantial amounts of formaldehyde are present indoors which react to formate via the Cannizzarro reaction and accumulate over time in the films. Twenty cases of chalconatronite (including two mentioned in the literature) are reported as occurring on heritage objects with glass in contact with copper alloys: Baroque reliquaries with set glass gems, enamel on metal (sixteenth century and a modern replica of intentionally unstable composition), Christmas tree glass baubles with wires, glass buttons with metal shanks, a glass figure with a wire support, miners’ lamps, and a glass framed daguerreotype. These confirmed identifications might help conservators in investigating similar cases to shed more light on the formation conditions. 相似文献
10.
ABSTRACTHafez’s tomb was constructed on the grave of the well-known Iranian poet in Shiraz, in the 1930s. The dome of this monument is made of copper metal and has been exposed to the urban environment for 80 years. In this study, corrosion mechanisms and conservation conditions of the metallic dome of the Hafez’s tomb are investigated by analytical methods including optical microscopy, ICP-MS, SEM-EDX, and X-ray diffraction. The results showed that the dome is constructed from many copper sheets that are hammered to shape the dome. The corrosion products formed on the surface of copper sheets include copper oxide and copper trihydroxichlorides. In fact, the corrosion mechanism occurring in the metallic dome consists of copper oxidation and redeposition of copper II products because of reaction with air pollutants. 相似文献
11.
《文物保护研究》2013,58(4):147-152
AbstractIn order to test some of the methods of archaeological bronze conservation, a procedure was perfected that reproduces the structure and composition of original patinas. Then the most common methods of treatment were applied on test samples thus prepared and on archaeological items. This experiment has allowed us to choose the best treatment in accordance with the following requirements: restraint of corrosion, speed of operation, lack of colour alteration and avoidance of break-up or solution of patina. 相似文献
12.
《文物保护研究》2013,58(1):17-40
AbstractA study is presented of the growth of sulphidecontaining corrosion products on antiquities in museums. Analysis of the corrosion products suggests that they are dependent on the mode of formation. Techniques for conservation have also been investigated and l-amido-l-cyanoethylene, 2,2-di(sodium thiolate) is recommended for dissolving the sulphide layers, while a treatment with benzotriazole followed by lacquering is recommended for long-term protection. 相似文献
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A new coating system for archeological bronze protection that consists of a primer coating and a top coating was prepared in this study. The primer coating was prepared by mixing water-based acrylic emulsion with 1,2,3-benzotriazole, and the ultraviolet (UV) light-resistant top coating was prepared by mixing water-based acrylic emulsion with nano-sized TiO2 and SiO2 particles. UV light resistance and visible light transmission, contact angle, corrosion resistance, and mechanical properties of the new coating system were investigated and the results showed that UV resistance, hydrophobicity, oleophobicity, glossiness, and corrosion resistance all were improved. Application of the new system on real archaeological bronzes showed that the coating film was colorless, odorless, transparent, soft low-lustre, removable, and the original appearance of the archaeological bronze was well maintained. 相似文献
15.
《文物保护研究》2013,58(4):226-232
AbstractCarbonyl compounds are of concern in museums because of their potential to damage artifacts. The mode of damage for aldehydes is far from clear and seems to require oxidation. Lead coupons were exposed to gaseous formaldehyde (methanal) and formic acid (methanoic acid) in various humid oxidizing atmospheres. The resulting corrosion products were weighed and identified using X-ray diffraction analysis after as much as 56 days exposure. When fomaldehyde was in more oxidizing environments (atmospheres containing hydrogen peroxide) it caused heavy corrosion but in the dark, with no oxidant, there was only very slight tarnish, even at high humidities. This suggests that oxidation is an important control on corrosion by formaldehyde. Thermodynamic calculations indicate that at low formic acid concentrations (below about 1 ppb) the corrosion products should be carbonates (plumbonacrite and hydrocerussite) while at higher concentrations lead formate would be expected. The mineralogical complexity and the importance of oxidants make it very difficult to set standards for formaldehyde in the museum environment. 相似文献
16.
Benedetto Bozzini Belén Alemán Matteo Amati Marco Boniardi Vincenzo Caramia Giuseppe Giovannelli 《文物保护研究》2017,62(8):465-473
A recent assessment (Giovannelli, G., D'Urzo, L., Maggiulli, G., Natali, S., Pagliara, C., Sgura, I. & Bozzini, B. 2010. Journal of Solid State Electrochemistry, 14: 479–94.) of the corrosion state of a late Bronze Age artefact (ca. 1100 BCE) exposed to a coastal environment, based on optical and scanning electron microscopies, X-ray fluorescence mapping, and X-ray diffractometry, led to recognition of bronze disease conditions essentially related to the presence of nantokite locked inside mesoscopic subsurface pits. The object was then treated successfully with a novel electrochemical approach specifically designed to allow penetration of the electric field into deep, screened pits. In order to further develop and optimize this promising approach by fine-tuning the capabilities of electrochemical control, more insight is required on the specific morphochemistry of the corrosion product scenario. To this end, here we report a space-dependent compositional and chemical-state analysis, performed with synchrotron-based scanning photoelectron microspectroscopy. The investigated object consists of a segregated cast bronze. The prevailing corrosion form is preferential attack of Sn-rich phases, accompanied by a synergistic type of Sn and Cu attack triggered by the peculiar type of decuprification taking place in a bronze disease framework and characterized by the formation of Sn(OH)Cl as a result of local HCl generation in the Cu corrosion process. 相似文献
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ABSTRACT Sandstone is a common sedimentary rock that is easily carved due to its weakly cemented fine grains and relatively low strength. Therefore, numerous large-scale grottoes in China are made of sandstone. However, these sandstone cultural heritage structures are often seriously damaged due to temperature and humidity changes, air pollution, biodeterioration, and repeated dissolution and crystallization of soluble salts. In general, it is imperative that a consolidant capable of providing cohesion by infilling pores between the stone grains is synthesized. In recent years, it has been reported that using organic consolidation materials for sandstone protection comes with various negative effects, such as a short lifetime, poor compatibility, and preservation damage. Using inorganic consolidation materials to protect sandstone seems to be one of the research trends for the future. Herein, this paper introduces a permeable, inorganic magnesium-based material (MMH solution) for silica sand consolidation. To assess this consolidant, the paper investigates the influence of varying molar ratios of MgO:MgCl2·6H2O:H2O on properties such as penetration depth, consolidation weight, colour variation, and compressive strength. The results demonstrate that the molar ratios of MgO:MgCl2·6H2O:H2O can significantly affect the consolidation performance. Additionally, it is believed that the MMH solution of MgO:MgCl2·6H2O:H2O?=?5:1:16 can be successfully used for the consolidation of silica sand, as the cubic specimens’ surface micrographs show good compatibility between the consolidation product and sand grains. Experiments (i.e. weight loss rate and mineralogical compositions analysis) are performed to evaluate the cubic specimens’ water resistance properties after being immersed in water. Furthermore, the consolidation material’s failure mechanism as a self-sacrificing material is preliminarily analyzed. Results indicate that MMH solution is a promising conservation material that shows great potential for consolidating severely weathered sandstone. 相似文献
19.
CORROSION AND CONSERVATION OF A SILVER VISCERAL VESSEL FROM THE BEGINNING OF THE SEVENTEENTH CENTURY
《文物保护研究》2013,58(3):114-117
AbstractTwo different cleaning methods were found necessary to remove silver chloride corrosion products from different areas of a silver canopic vessel containing about 6% of copper. Two possible mechanisms of silver corrosion which could have led to the differing silver chloride corrosion products are put forward. 相似文献
20.
《文物保护研究》2013,58(3):142-163
AbstractCorrosion 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. The most frequently identified compounds in the patina samples were atacamite, a copper(II) chloride hydroxide, and cuprite, a copper(I) oxide. The most frequently identified compounds in the corrosion samples were atacamite and rouaite, a copper(II) hydroxide nitrate. The analysis determined that the current environment is not contributing to the surface alterations of the sculptures; however, past storage conditions, chemical residues from artificial patination, and likely casting residues are the main causes of the current condition. 相似文献