Etude de la corrosion de bronzes archeologiques du Fort-Harrouard: alteration externeet mecanisme d'alteration stratifiee

Robbiola, Luc; Queixalos, Inocencia; Hurtel, Loïc-Pierre; Pernot, Michel; Volfovsky, Claude

doi:10.1179/sic.1988.33.4.205

Cited by 3 publications

(3 citation statements)

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“…The instability of CuCl must have led to its rapid conversion to atacamite upon the preparation of the sample cross section. , Both in situ analysis and the reactivity of the phase with air therefore point to the Cu(I) phase in the archeological sample being CuCl with incorporated oxygen anions. This phase was noted in the core of many corroded archeological copper-base artifacts. ,− ,, This corrosion process is usually associated with oxidation under humid aerobic condition in soils …”

Section: Resultsmentioning

confidence: 99%

“…In burial environments, this phenomenon is directly related to the soil conditions (particularly the presence of water, its pH, and the availability of aqueous electrolytes, such as chlorides and sulfates , ), as well as to the structure and initial surface state of the metal. For Cu-based materials, corrosion most often gives rise to a structure in which layers of Cu(I) and Cu(II) species form, such as red Cu 2 O (cuprous oxide) and green Cu 2 Cl(OH) 3 phases (clinoatacamite or atacamite). , According to the time scale and the conditions of the burial environment, a wide range of structural modifications can be observed, from large periodic corrosion structures to less severe attacks in more compact layers, leading to highly heterogeneous and complex morphologies, that extend from deeply stratified (e.g., Robbiola et al, Scott, De Ryck et al, Oudbashi) to fully intermixed (e.g., Thoury et al). Nonetheless, the corroded structure carries information about the history of the metallic object, which can be recovered through the identification of corrosion products , and the characterization of the corroded structures. ,− …”

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confidence: 99%

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Synchrotron-Based Phase Mapping in Corroded Metals: Insights from Early Copper-Base Artifacts

Guériau

Bellato

et al. 2019

Anal. Chem.

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The detailed description of corrosion processes in ancient and historical metal artifacts currently relies on the indepth study of prepared cross sections. The in-plane elemental and phase distributions can be established from a combination of light and electron microscopy characterization. Here, we show that high-resolution virtual sectioning through synchrotron X-ray microcomputed tomography allows a precise noninvasive 3D description of the distribution of both internal and external mineral phases in whole objects. In fragments of early copper artifacts (third−second millennium BC) from Southern Mesopotamia and the Indus valley, this approach provided essential clues on long-term corrosion processes. Major and minor phases were identified through semiquantitative evaluation of attenuation coefficients using polychromatic X-ray illumination. We found evidence for initially unidentified phases through statistical processing of images. We discuss interpretation of the distribution of these phases. A good correlation between the corrosion phases identified by CT and by invasive BSE-SEM is demonstrated. In addition to the stratigraphy of the copper corrosion compounds, we examine and discuss the variations observed in the attenuation coefficients of Cu(I) phases. Semiquantitative synchrotron X-ray microtomography phase mapping requires no specific sample preparation, in particular polishing or surface finishing, and any material tearing or displacement is avoided. We also provide evidence for the noninvasive observation of phases rapidly altered upon preparation of real cross sections. The method can be applied when cross-sectioning even of minute fragments is impossible.

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Synchrotron-Based Phase Mapping in Corroded Metals: Insights from Early Copper-Base Artifacts

Guériau

Bellato

et al. 2019

Anal. Chem.

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“…), ale závisí aj od iných nezanedbateľných parametrov, ako sú historické obdobia, metalurgické techniky alebo dokonca druh a veľkosť artefaktu (pamiatky, veľké sochy, menšie predmety). Vrstvy patiny sú často zložité; rozloženie povrchových vrstiev, medzigranulárna alebo transgranulárna korózia atď [58][59][60][61][62][63][64][65][66]. Niekoľko štúdií preukázalo, že okrem iných klimatických parametrov zohráva hlavnú úlohu vlhkosť, najmä v prítomnosti korozívnych stimulantov.…”

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Copper and copper patina

Rak

Bureš

2017

Koroze a Ochrana Materialu

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konektory), ale použitie v iných oblastiach je možné (napr. dekorácie, sochy). Na nechránenej medi sa veľmi rýchlo objavuje čierna vrstvička kupritu Cu 2 O [1]. V priebehu niekoľkých rokov je tento povlak nahradený charakteristickou zelenomodrou vrstvičkou [2, 3]. Toto sfarbenie na bronze alebo iných kovoch je označované ako "patina" [1]. Medené patiny sú priestorovo heterogénne vrstvy, ktoré obsahujú prázdne priestory a dtiny. Pórovitosť môže byť ľahko dokázaná schopnosťou patiny absorbovať veľké množstvo vody [4]. Zlúčeniny patiny sú vytvárané chemickou reakciou medi so stopovými prvkami z atmosféry najmä síranmi a chloridmi [5]. Medená patina väčšinou pozostáva z dvoch odlišných vrstiev, 5-10 µm vrstvy kontinuálnej vrstvy kupritu (Cu 2 O) chrániacej základný materiál a vrchnej pórovitej vrstvy 5-40 µm tvorenej zásaditým síranom meďnatým nazývaným aj brochantit (Cu 4 SO 4 (OH) 6 ) alebo bázického chloridu meďnatého atakamitu (Cu 2 Cl(OH) 3 ). Brochantit sa vyskytuje bežnejšie ako atakamit keďže ten sa vytvára iba v prímorských oblastiach [4].Rozpúšťanie medi má nasledujúci mechanizmus: [2, 6]. Príprava umelej patiny na medi a jej zliatinách bola študovaná veľmi dlho, v súčasnosti existujú postupy pre jej prípravu [7][8][9]. V dnešnej dobe väčšina chemických analýz takýchto artefaktov, analýza koróznych procesov a kolorimetrické analýzy sa robia kvôli určeniu pravosti a pôvodu bronzovej zliatiny [9][10][11][12][13][14][15]. Medzi techniky používané na charakterizáciu patín patria skenovacia elektrónová mikroskopia (SEM) s energiovo disperznou spektroskopiou (EDS), elektrochemická impedančná spektroskopia (EIS) a infračervená spektroskopia s Fourierovou transformáciou (FTIR) [16, 17]

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Tracing Manufacturing Technique In An Archaeological Thin Sheet Tube From Tepe Sagzabad In Qazvin Plain, Iran (1500-800 Bc)

Mortazavi¹,

Kakhki²,

Golozar³

et al. 2014

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Etude de la corrosion de bronzes archeologiques du Fort-Harrouard: alteration externeet mecanisme d'alteration stratifiee

Cited by 3 publications

References 6 publications

Synchrotron-Based Phase Mapping in Corroded Metals: Insights from Early Copper-Base Artifacts

Synchrotron-Based Phase Mapping in Corroded Metals: Insights from Early Copper-Base Artifacts

Copper and copper patina

Tracing Manufacturing Technique In An Archaeological Thin Sheet Tube From Tepe Sagzabad In Qazvin Plain, Iran (1500-800 Bc)

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