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Showing 6 results for Copper

Parastou Naeimi Taraei, Shaiba Khadir,
Volume 1, Issue 1 (4-2017)
Abstract

Due to the complex corrosion mechanism of the bronze objects, explaining the structure of different layers of corrosion in these objects at microscopic levels is possible. Typically copper oxide(I) is the first corrosion layer on surface of bronze objects that are excavated of historical sites. However, depending on the environmental conditions، various forms of corrosion layer of tin or copper-rich oxide are formed that are effective in corrosion resistance of objects. Identification of tin oxides or copper-tin corrosion products is not simple by using of routine methods of instrumental analysis.However in this research the formation process of copper and tin oxides of some of historical bronze objects of Iran were studied by using the optical microscope with polarized light that show colored corrosion products and in some cases the method of scanning electron microscopy equipped with elemental analysis (SEM-EDX) was used to complete the identification process of oxide layers. According to the results, identify of evidence of differences in distribution of copper and tin in the microstructure that is result of macroscopic and microscopic segregation, formation of a solid solution of copper besides the copper-copper oxide eutectic mixture during the solidification process, the appearance of copper oxide inclusions in the microstructure of metal, moving The tin-rich layer of copper oxide layer to the outside, formation of copper oxide-tin oxide sandwiching layers, selective dissolution of tin in the outer layers, decuprification phenomenon in corrosion layers  and condensation of tin oxides in the center of sample and finally the usual formation or degradation of copper oxide layer under certain conditions have been studied with microscopic imagesof selected samples of bronze objects which confirmed the ability of microscopic techniques in the study of oxide layers of bronze objects.

Shaiba Khadir, Parastoo Naeimi Taraei,
Volume 1, Issue 2 (10-2017)
Abstract

Given the nature of the chloride ion and its tendency to penetrate the inner layers of the metal, paying attention to it in the field of protection of metal artifacts is of great importance. In this article, the effect of the attacking chloride ion on historical copper and silver-based metals has been discussed, and according to the results of a long-term research project on the pathology of metal artifacts in Iran, various examples of artifacts affected by chloride attacks have been briefly presented and compared. In conducting corrosion studies in the aforementioned project, X-ray imaging, optical microscopy, and scanning electron microscopy, and wet and instrumental analysis methods (EDX, XRD, PIXE) were used to analyze the corrosion process. According to the studies conducted, severe pitting corrosion with progressive conditions was observed in the works of the Rasht Museum, as well as corrosion of the tin-rich phase and its simultaneous release as oxide compounds in many of the mirrors in this museum, which in many cases had a starting point under surface sediments when local conditions were provided. This process in the works in museums in southern Iran with high humidity conditions and with chlorides concentrated in the corrosion products has caused the loss of the metal core in many of the works obtained from Hormuz. The concentration and crystallization of chloride in the corrosion layers and the attacks caused by it in the works of the dry regions of Iran, despite periodic humidity or uncontrolled storage conditions after excavation, is the cause of the loss of the metal core of many of the works obtained from Sites such as Sarm, Qoli Darvish, and Sialk have been affected by chloride attacks through different mechanisms, from chloride penetration into the oxide layer to the dissolution and removal of copper from the outer layers. Silver artifacts obtained from different sites have also been affected by chloride attacks, due to the presence of horn silver chloride compounds (Sialk), severe local corrosion (Hormoz), and intermittent copper deposition and the deposition of its chloride salts (Teppeh-e-Hisar).

Shaiba Khadir, Fathollah Niyazi, Kouorsh Kouhestani,
Volume 6, Issue 4 (3-2024)
Abstract

The "Clogs of the Kaaba" at the Iran Carpet Museum is a pair of metal/ copper alloy shoes by Parviz Tanavoli for an outdoor installation. The work is part of a memorial chapel designed minimalist style within the museum’s grounds. The clogs are crafted to a life-size scale, with their surfaces textured with fine and delicate grooves to enhance their aesthetic and visual appeal. The artist has also applied a dark artistic patina to the surface of the clogs. The interior of the clogs has accumulated dust, soot, and debris from the surrounding greenery. Additionally, prolonged exposure to environmental conditions such as annual rainfall, seasonal temperature variations, and urban pollutants such as acid rain has affected their condition on the ground. The surface of the clogs shows green corrosion products and carbonate deposits. the aim of this operation is to stabilize the clogs and prevent further exposure to harmful urban environmental factors. In order to evaluate and document the current condition, digital photography was conducted on both a macroscopic and microscopic scales. Surface sediment removal was carried out using manual mechanical methods with a scalpel and ultrasonic device. The poultice method was applied in a controlled and limited manner to remove thick sediments using Rachel's salt solution and%2 hydrochloric acid. To protect the surface, a %3 BTA (benzotiazol: C6H5N3) solution was used, followed by a coating of epoxy polyamide solution.

Fatemeh Alamirzaei, Parasto Naeimi Taraei,
Volume 7, Issue 3 (11-2024)
Abstract

The study of corrosion mechanisms in ancient bronze artifacts, particularly those from the salty and humid region of Hormuz, is crucial due to severe corrosion. This article examines a bronze dagger attributed to excavations in Hormuz to analyze its corrosion behavior influenced by the environment. Techniques such as X-ray imaging, stereomicroscopy, X-ray diffraction (XRD), polarized light microscopy (PLM), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) were employed. Results show that most of the dagger has transformed into corrosion products, including copper and tin oxides, as well as basic chloride compounds like atacamite and paratacamite, forming a three-layered corrosion structure. The corrosion mechanism involves selective dissolution of copper, its migration to outer layers, and the concentration of tin oxide compounds in the central regions, accompanied by chloride ion penetration. This process has preserved patterns of grain structure and thermal twinning in the inner oxide layers, with periodic deposition of copper and tin oxides indicating the formation of a colloidal solution of copper and tin salts beneath the soil (Scott, 2002; Robbiola et al., 1998).

Aminallah Kamali,
Volume 7, Issue 4 (2-2025)
Abstract

Yazd Province, with its diverse mineral resources and long history of metallurgical activities from prehistoric to contemporary times, is considered one of the primary centers of ancient metalworking in the Central Iranian Plateau. The Dehneh Lashkar metal smelting site, located near Robat Posht-Badam village, was identified during regional geological surveys and studied for the first time. From this site, covering an area of 140 square meters, 10 slag samples were collected, with 4 samples subjected to petrographic analysis and 4 samples analyzed chemically using ICP-OES. The examined samples exhibited distinct macroscopic characteristics, including dark green to black coloration, irregular morphology, porous to dense textures, and dimensions ranging from 2 to 7 cm. Petrographic studies revealed that the slags primarily consist of fayalite (FeSiO), pyroxene, and glassy phases, with spinifex and porphyritic textures indicative of rapid cooling and incomplete melt crystallization. Polished section analyses further confirmed the presence of copper sulfide phases, including bornite (CuFeS), covellite (CuS), and native copper (Cu) within the slags. Chemical analyses indicated an average copper concentration of 1.96 wt% and zinc concentration of 0.88 wt%, suggesting the use of Cu-Pb-Zn polymetallic ores as the primary raw material. The average calcium oxide (CaO) content of 24 wt% points to the use of carbonate rocks (likely limestone and dolomite) as fluxes to adjust viscosity and lower the melting temperature. The chemical composition of the slags suggests an average smelting temperature of 1100–1200°C, consistent with the use of siliceous and carbonate fluxes to enhance metal separation. This study provides evidence of an ancient metalworking industry at the site based on petrographic and chemical analyses of the slags. The main research questions addressed the types of metals extracted and the metallurgical processes employed. Based on the findings, the site was primarily exploited for copper extraction. Although insufficient surface evidence was available for precise dating, petrographic and chemical studies indicate the use of advanced metallurgical technologies capable of achieving temperatures of 1100–1200°C and employing combined siliceous-carbonate flux systems to optimize the reduction and metal separation processes.

Aminallah Kamali,
Volume 8, Issue 1 (6-2025)
Abstract

Yazd Province, with its diverse mineral resources and long history of metallurgical activities from prehistoric to contemporary times, is considered one of the primary centers of ancient metalworking in the Central Iranian Plateau. The Dehneh Lashkar metal smelting site, located near Robat Posht-Badam village, was identified during regional geological surveys and studied for the first time. From this site, covering an area of 140 square meters, 10 slag samples were collected, with 4 samples subjected to petrographic analysis and 4 samples analyzed chemically using ICP-OES. The examined samples exhibited distinct macroscopic characteristics, including dark green to black coloration, irregular morphology, porous to dense textures, and dimensions ranging from 2 to 7 cm. Petrographic studies revealed that the slags primarily consist of fayalite (FeSiO), pyroxene, and glassy phases, with spinifex and porphyritic textures indicative of rapid cooling and incomplete melt crystallization. Polished section analyses further confirmed the presence of copper sulfide phases, including bornite (CuFeS), covellite (CuS), and native copper (Cu) within the slags. Chemical analyses indicated an average copper concentration of 1.96 wt% and zinc concentration of 0.88 wt%, suggesting the use of Cu-Pb-Zn polymetallic ores as the primary raw material. The average calcium oxide (CaO) content of 24 wt% points to the use of carbonate rocks (likely limestone and dolomite) as fluxes to adjust viscosity and lower the melting temperature. The chemical composition of the slags suggests an average smelting temperature of 1100–1200°C, consistent with the use of siliceous and carbonate fluxes to enhance metal separation. This study provides evidence of an ancient metalworking industry at the site based on petrographic and chemical analyses of the slags. The main research questions addressed the types of metals extracted and the metallurgical processes employed. Based on the findings, the site was primarily exploited for copper extraction. Although insufficient surface evidence was available for precise dating, petrographic and chemical studies indicate the use of advanced metallurgical technologies capable of achieving temperatures of 1100–1200°C and employing combined siliceous-carbonate flux systems to optimize the reduction and metal separation processes.


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