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Showing 5 results for Naeimi Taraei
Comparative study of the formation process of oxides in bronze objects according to the microscopic studies
Parastou Naeimi Taraei, Shaiba Khadir,
Volume 1, Issue 1 (Special Issue 1.1 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.

A review of the erosion process resulting from chloride attacks in samples of copper and silver-based artifacts
Shaiba Khadir, Parastoo Naeimi Taraei,
Volume 1, Issue 2 (Spesial Issue 1.2 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).

Corrosion Inhibitors: Existing Challenges and Evaluation of Optimization Potential
Parastoo Naeimi Taraei, Seyed Mohammad Amin Emami, Abolghasem Dolati,
Volume 2, Issue 2 (Special Issue 1.1 2019)
Abstract
Various chemical and natural substances have been employed to control corrosion in historical metal artifacts. However, the use of these substances has not always been effective and has occasionally led to secondary issues. This article reviews the existing challenges associated with corrosion inhibitors and investigates factors influencing the selection of materials to optimize corrosion control conditions. Based on available data, a multifunctional derivative of phosphonic acid with active phosphorus and nitrogen centers was selected. Its effectiveness in controlling corrosion of iron artifacts was evaluated through electrochemical impedance and polarization measurements, as well as microscopic methods. The results demonstrate the material’s ability to reduce corrosion rates at very low concentrations with minimal impact on the artifacts’ appearance, marking a significant step toward their preservation. Furthermore, the potential for optimizing corrosion control conditions through the use of complementary materials alongside phosphonic acid derivatives, leveraging their synergistic effects, is discussed.

Technical Study of a High-Tin Bronze Vessel from the Bam World Heritage Site
Ramin Talei, Parastoo Naeimi Taraei,
Volume 2, Issue 2 (Special Issue 1.1 2019)
Abstract
With the advent of Islam, bronze temporarily replaced gold and silver in the production of metal vessels. Among the bronze artifacts used during this period, high-tin bronze (white bronze) objects, valued for their silver-like appearance, gained significant attention. One such artifact is a vessel discovered during debris removal operations following the 2003 Bam earthquake, located in the southern part of the Bam Citadel, specifically the southern section of the house known as Mir Akbar. Similar decorative patterns are found in artifacts from the Seljuk and Timurid periods. In this study, the artifact was examined using X-ray imaging, and microstructural analysis of a sample from the vessel’s base was conducted using reflected light optical microscopy after preparation. To further the technical investigation, Scanning Electron Microscopy (SEM) equipped with Energy-Dispersive X-ray Spectroscopy (EDX) was employed to analyze the alloy composition and metallic and non-metallic phases. The results indicate that the vessel was produced through casting, with directional mechanical work causing elongation of non-metallic sulfide phases within the metal matrix. The microstructure of the vessel consists of single copper-rich grains dispersed in a needle-like beta phase rich in tin, characteristic of high-tin bronze (white bronze). After cooling, the alloy underwent heat treatment at approximately 650°C followed by rapid quenching, leading to the formation of the needle-like phase and resulting in the vessel’s hardness and brittleness.

Research Paper Analysis of the Decuprification Process in the Corrosion Behavior of a Bronze Dagger
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).

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