Volume 8, Issue 1, June 2020, Page: 1-5
Influence of Manufacturing Processes in Deterioration of Ag-Cu Artefact Alloy
Abeer Gharib, Conservation Department, Faculty of Fine Arts, Minia University, Minia, Egypt
Received: Dec. 10, 2019;       Accepted: Dec. 20, 2019;       Published: Jan. 4, 2020
DOI: 10.11648/j.ija.20200801.11      View  349      Downloads  95
Abstract
Ancient silver with about 2% copper object is studied to determine manufacturing defects based on chemical and microscopic investigations. In this paper Bullion (silver-copper alloy) ink box inlays with enamel from the Museum of the faculty of applied arts in Cairo, Egypt has been investigated to identify manufacturing process and its effect on the ink deterioration. Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectrometry (SEM-EDS) method has been used on samples to reveal chemical composition of the alloys and the effect of various fabrication and thermal treatment. The results indicated that all samples were made of silver-copper alloys, other elemental corrosion layers have detected in contents such as C, O, S, Cl, Si, Na, Ca, Al. Fracture surfaces provide with important information helping to recognize failure causes, so the fracture surface investigation and etching by means of alcoholic ferric chloride was carried out for microstructural analysis. Scanning Electron Microscopy SEM-micrograph of etching sample showed pores and cracking propagation. Crack initiation usually appears at the object surface, and is generally produced by stress concentrators, producing rise to local plastic deformation or cracking and detachment of brittle precipitates. Local stress–strain concentration related to a variety of microstructural inhomogeneities. The X-ray diffraction analysis (XRD) confirmed the EDX analysis that the corrosion compounds consist of Montmorillonite NaO3(Al, Mg)2Si4O10(OH)2XH2O, Atacamite Cu2Cl(OH)3, Malachite Cu2CO3(OH)2, Paratacamite Cu2Cl(OH)3, Cuprite Cu2O, Acanthite Ag2S, Tenorite CuO, Calcite CaCO3, Chlorargyrite AgCl, Copper Cu. Silver–copper alloys failed through corrosion process that produce brownish-black tarnish. This tarnish alters the aesthetic of the object. The corrosion layers of the object referred to long-term contamination and oxidation, which led to increase intergranular cracking, regions of ductile fracture, and brittle intergranular fracture.
Keywords
Silver-Copper Alloy, Art Work Defects, SEM-EDX, XRD, Plastic Deformation, Defects Analysis
To cite this article
Abeer Gharib, Influence of Manufacturing Processes in Deterioration of Ag-Cu Artefact Alloy, International Journal of Archaeology. Vol. 8, No. 1, 2020, pp. 1-5. doi: 10.11648/j.ija.20200801.11
Copyright
Copyright © 2020 Authors retain the copyright of this article.
This article is an open access article distributed under the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Reference
[1]
O. Omid, S. Atefeh, (2015). Chemical and microstructural analysis of some Achaemenian silver alloy artefacts from Hamedan, western Iran, Periodico di Mineralogia, 84, 3A (Special Issue), pp. 419-434.
[2]
S. M. Northover, J. P. Northover, (2014) Microstructures of ancient and modern cast silver–copper alloys, Materials Characterization, 90, pp. 173-184.
[3]
C. M. B. Martinsa, J. I. Martins, (2011). Identification of Corrosion Products on a Medieval Copper-Silver Coin, Protection of Metals and Physical Chemistry of Surfaces, Vol. 47, No. 1, pp. 128–132.
[4]
J. E. Hatch, Microstructure of Alloys, (1984). Aluminum Properties and Physical Metallurgy, ASM International, p. 58.
[5]
U. Krupp, (2007). Fatigue Crack Propagation in Metals and Alloys: Microstructural Aspects and Modelling Concepts, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
[6]
Von der Fakultät für Werkstoffwissenschaft und Werkstofftechnologie, (2003). Material properties of copper alloys containing arsenic, antimony, and bismuth the material of Early Bronze Age ingot torques, PhD, Technischen Universität Bergakademie Freiberg.
[7]
D. Ashkenazi, N. Iddan, and O. Tal, (2012). Archaeometallurgical Characterization of Hellenistic Metal Objects: The Contribution of The Bronze Objects from Rishon Le-Zion, Archaeometry 54, 3, 528–548.
[8]
A. A. Kassie, S. B. Assfaw, (2013). Minimalization of Casting Defects, IOSR Journal of Engineering. Vol. 3. Issue 5.
[9]
L. Collini, (2012). Copper Alloys – Early Applications and Current Performance –Enhancing Processes, Manager Iva Simcic, Croatia.
[10]
A. Gharib, F. S. Madkour, (2014). The Treatment Procedures of Persian Metallic Objects Covered with Colored Enamels, 18th – 20th Centuries AD, International Journal of Conservation Science, Volume 5, Issue 4, October-December: 447-458.
[11]
Casting Defects-Sand Mould, Metal Casting, http://www.iron-foundry.com/casting-defects-pictures.html.
[12]
Dislocations & Strengthening Mechanisms Problem Solutions, http://www.acadox.com/action_handler/download/resource/13842/24821.pdf.
[13]
R. Pippan1, C. Zelger, E. Gach, C. Bichler, and H. Weinhandl, (2010). On the mechanism of fatigue crack propagation in ductile metallic materials, Fatigue & Fracture of Engineering Materials and Structures, 34, 1–16 1.
[14]
Z. Ziming, L. Weiling, Y. Shaofeng, and B. J Juergen, (2015) Metal crack propagation monitoring by photoluminescence enhancement of quantum dots, Engineering and Laboratory Note, Vol. 54, No. 21, pp. 6498-6501.
[15]
C. Pierre, V. Christophe, C. Christian, D. François, (2015). Effect of cold work, second phase precipitation and heat treatments on the mechanical properties of copper–silver alloys manufactured by cold spray, Materials Science and Engineering A 637, 40–47.
[16]
Y. Z. Tian, and Z. F. Zhang, (2009). Microstructures and tensile deformation behavior of Cu-16wt.%Ag binary alloy, Materials Science and Engineering A, www.reserchgate.net/publication/240423160.
[17]
J. C. D. de Figueiredo, S. S. Asevedo, J. H. Barbosa, (2014). Removal of brownish-black tarnish on silver–copper alloy objects with sodium glycinate, Applied Surface Science 317, 67–72.
[18]
G. Balassone et al. (2018). Multi-analytical characterization and provenance identification of protohistoric metallic artefacts from Picentia- Pontecagnano and the Sarno valley sites, Campania, Italy, Measurement 128, 104–118.
Browse journals by subject