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Showing 3 results for Chloride
Risk Analysis Based on Measurement of Effective Factors in Active Corrosion and Risk Assessment in Archaeological Bronze Collections
Omid Oudbashi,
Volume 1, Issue 1 (4-2017)
Abstract
Recently risk assessment and management in cultural-historical collections is one of the important subjects in the field of preventive conservation research. Different methods and aspects of are used and studied in the field of risk assessment in archaeological sites and collections and significant results are achieved and published in last decades. One of the types of archaeological collections is metal collections that may be found in archaeological excavations. In this paper, application of risk assessment approach is investigated to estimate conservation condition in archaeological bronze collection. This approach is concentrated on occurrence of active corrosion (bronze disease) and factors influencing it during burial time and post-excavation period. Thus, the results of analyses based on an analytical system is considered that is performed previously (Metal-Environment-Corrosion system) including identification of soil environment, characterization of corrosion mechanism and their effect on conservation condition in bronze objects. For this purpose, two bronze collections are studied that are discovered from Haft Tappeh and Sangtarashan sites from Iran. The condition of two collections is assessed consisting of identification of risks and deterioration factors influencing bronze objects during excavation operation as well as post-excavation preservation and risk assessment based on occurrence of active corrosion in the collections. Finally, conservation condition and excavation procedure and preservation of the collections are estimated and analyzed based on the corrosion mechanism occurred in the objects and results of risk assessment in soil and museum environments.

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 (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).

Chloride Ions Removal and Stabilization of Archaeological Irons: A Review of Methods, Efficiency, Limitations and Challenges
Elaheh Hajjari, Mohammad Mortazavi, Keyvan Raeissi, Mohammad Hafezi Kahnamoei ,
Volume 8, Issue 4 (3-2026)
Abstract
The inherent instability of archaeological iron objects is due to contaminated with chloride ions from the burial environment, as well as being exposed to oxygen and high relative humidity. Therefore, the removal of chloride ions and the stabilization of active corrosion are essential steps to prevent further deterioration and to preserve these artefacts. Numerous scholars have investigated various methods for the dechlorination of archaeological irons. However, the complexity of the corrosion mechanisms, the varying condition under which artefacts were buried, the specific characteristic of each object, and the ethical principles of conservation and restoration confront conservation scientists with significant challenges. As a result, from the earliest research in this field to the present day, studies in the subjects are still ongoing. A meticulous review of the literature can lead to a better understanding of existing research findings and help identify aspects that more research is needed. The aim of this paper is to review, critique and examine each of the different chlorination methods, while also discussing their disadvantages and limitations. This review discuses different methods of chloride ions removal and stabilization of archaeological iron artefacts, including electrochemical techniques, immersion in alkaline aqueous solutions, application of subcritical fluids, hydrogen plasma, and biological treatment using bacteria. In addition, factors affecting the process before, during, and after dechlorination, as well as the specific challenges of treating large and composite objects are examined. Finally, by reviewing and comparing the studies conducted in this paper, it was found that there are still gaps in this regard, the analysis of which will ultimately lead to the application and optimization of appropriate dechlorination methods tailored to the specific characteristics of each object and its conservation conditions.

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