Electrochemical Analysis of Chloride Impacts on Passivation of Archaeological Iron in Desalination Solutions in Studies in conservation, Vol.70 N°5-6(2025; July-August) (2025-07-01)  

Public ISBD [article]  inStudies in conservation > Vol.70 N°5-6(2025; July-August) (2025-07-01) . - P. 518-529 Titre : Electrochemical Analysis of Chloride Impacts on Passivation of Archaeological Iron in Desalination Solutions Type de document : texte imprimé Année de publication : 2025 Article en page(s) : P. 518-529 Langues : Anglais (eng) Catégories : Analyse électrochimique Chlorures alcalins Corrosion -- Analyse Fer -- Antiquité -- Conservation et restauration Fer -- Teneur en sodium -- Mesure Microstructure (physique) Passivité (chimie) Index. décimale : 7.025 Dommages. Conservation. Protection Résumé : ABSTRACT Based on the passivation of iron in alkaline solutions, aqueous alkaline treatment has been taken as an effective desalination technique to increase the stability of archaeological iron. However, chlorides may destroy the passivation of iron artifacts, causing damage to the treated artifacts during desalination. In this study, electrochemical and microstructure analyses were carried out in alkaline solutions with known chloride content, using archaeological iron and pre-corroded iron coupons with varying chloride levels within the rust layer. The study revealed that alkalinity ensures passivation even in the presence of chloride within the rust layer. However, the passivation weakens as the concentration of ‘free’ chloride ions in the alkaline solution increases due to their migration from the rust layer, leading to active corrosion. A chloride threshold value (CTV) of 355 ppm in 0.1 mol/L NaOH solution was established as a chloride level for the replacement of the alkaline solution. The determination of CTV based on electrochemical measurements is intended to guide the timely replacement of the desalination solutions, thereby preventing chloride-induced iron corrosion during desalination treatments. En ligne : https://www.tandfonline.com/doi/full/10.1080/00393630.2024.2423970 [article] Electrochemical Analysis of Chloride Impacts on Passivation of Archaeological Iron in Desalination Solutions [texte imprimé] . - 2025 . - P. 518-529. Langues : Anglais (eng) in Studies in conservation > Vol.70 N°5-6(2025; July-August) (2025-07-01) . - P. 518-529 Catégories : Analyse électrochimique Chlorures alcalins Corrosion -- Analyse Fer -- Antiquité -- Conservation et restauration Fer -- Teneur en sodium -- Mesure Microstructure (physique) Passivité (chimie) Index. décimale : 7.025 Dommages. Conservation. Protection Résumé : ABSTRACT Based on the passivation of iron in alkaline solutions, aqueous alkaline treatment has been taken as an effective desalination technique to increase the stability of archaeological iron. However, chlorides may destroy the passivation of iron artifacts, causing damage to the treated artifacts during desalination. In this study, electrochemical and microstructure analyses were carried out in alkaline solutions with known chloride content, using archaeological iron and pre-corroded iron coupons with varying chloride levels within the rust layer. The study revealed that alkalinity ensures passivation even in the presence of chloride within the rust layer. However, the passivation weakens as the concentration of ‘free’ chloride ions in the alkaline solution increases due to their migration from the rust layer, leading to active corrosion. A chloride threshold value (CTV) of 355 ppm in 0.1 mol/L NaOH solution was established as a chloride level for the replacement of the alkaline solution. The determination of CTV based on electrochemical measurements is intended to guide the timely replacement of the desalination solutions, thereby preventing chloride-induced iron corrosion during desalination treatments. En ligne : https://www.tandfonline.com/doi/full/10.1080/00393630.2024.2423970

A Multi-Method Investigation of Ferruginous Concretions on Ceramics from Nan’ao No. I Shipwreck in Studies in conservation, Vol.70 N°5-6(2025; July-August) (2025-07-01)  

Public ISBD [article]  inStudies in conservation > Vol.70 N°5-6(2025; July-August) (2025-07-01) . - P. 501-517 Titre : A Multi-Method Investigation of Ferruginous Concretions on Ceramics from Nan’ao No. I Shipwreck Type de document : texte imprimé Année de publication : 2025 Article en page(s) : P. 501-517 Langues : Anglais (eng) Catégories : Archéologie sous-marine -- Chine Céramique -- Chine -- 1368-1644 (Dynastie des Ming) -- Conservation et restauration Corrosion -- Analyse Fourier, Spectroscopie infrarouge à transformée de Microscopie Microscopie électronique à balayage Spectroscopie de fluorescence Spectroscopie infrarouge proche Spectroscopie Raman Index. décimale : 7.025:738 Conservation, restauration de céramique Résumé : ABSTRACT The Nan’ao No. I shipwreck, dating back to the Wanli period of China's Ming Dynasty (1573–1620 CE), was discovered in the South China Sea, from which a large number of ceramics was meticulously excavated. This study employs a comprehensive multi-method approach, encompassing techniques such as multispectral imaging, microscopy, scanning electron microscopy (SEM), Raman spectroscopy, Fourier transform infrared reflectance (FTIR) spectroscopy, near-infrared reflectance (NIR) spectroscopy, and X-ray fluorescence (XRF) analysis, to investigate the ferruginous concretions found on the ceramic sherds from the Nan’ao I shipwreck. The findings reveal that these concretions are predominantly distributed across defective areas of the ceramic surfaces, including pitted and cracked regions. The primary constituents of the concretions are identified as goethite, hematite, and lepidocrocite, with the varying proportions of these components potentially contributing to the differing colors of the concretions. Furthermore, iron sulfides may also play a significant role in the composition of the concretions. En ligne : https://www.tandfonline.com/doi/full/10.1080/00393630.2024.2422252 [article] A Multi-Method Investigation of Ferruginous Concretions on Ceramics from Nan’ao No. I Shipwreck [texte imprimé] . - 2025 . - P. 501-517. Langues : Anglais (eng) in Studies in conservation > Vol.70 N°5-6(2025; July-August) (2025-07-01) . - P. 501-517 Catégories : Archéologie sous-marine -- Chine Céramique -- Chine -- 1368-1644 (Dynastie des Ming) -- Conservation et restauration Corrosion -- Analyse Fourier, Spectroscopie infrarouge à transformée de Microscopie Microscopie électronique à balayage Spectroscopie de fluorescence Spectroscopie infrarouge proche Spectroscopie Raman Index. décimale : 7.025:738 Conservation, restauration de céramique Résumé : ABSTRACT The Nan’ao No. I shipwreck, dating back to the Wanli period of China's Ming Dynasty (1573–1620 CE), was discovered in the South China Sea, from which a large number of ceramics was meticulously excavated. This study employs a comprehensive multi-method approach, encompassing techniques such as multispectral imaging, microscopy, scanning electron microscopy (SEM), Raman spectroscopy, Fourier transform infrared reflectance (FTIR) spectroscopy, near-infrared reflectance (NIR) spectroscopy, and X-ray fluorescence (XRF) analysis, to investigate the ferruginous concretions found on the ceramic sherds from the Nan’ao I shipwreck. The findings reveal that these concretions are predominantly distributed across defective areas of the ceramic surfaces, including pitted and cracked regions. The primary constituents of the concretions are identified as goethite, hematite, and lepidocrocite, with the varying proportions of these components potentially contributing to the differing colors of the concretions. Furthermore, iron sulfides may also play a significant role in the composition of the concretions. En ligne : https://www.tandfonline.com/doi/full/10.1080/00393630.2024.2422252

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