La conservation-restauration du patrimoine technique et industriel dans le cadre de la loi sur les Musées de France, une mission impossible ?

Après avoir mis en évidence les difficultés de conservation-restauration spécifiques aux objets techniques et industriels, cette étude décrit – à travers l’exemple d’un projet de restauration de matériel ferroviaire – les grandes étapes d’un chantier de restauration puis, propose quelques solutions pour gérer au mieux ce type de dossier dans le respect de la loi sur les musées de France.After having brought to light the difficulties of conservation-restoration of technical and industrial objects, this study describes – using the example of a railway material restoration project – the main stages of a restoration project, and then goes on to propose several solutions to manage more efficiently this type of project respecting French museum legislation

Proprietés structurales et physiques de nouveaux stannures ternaires a base d' uranium et d'element de transition (Fe, Co, Ni, Ru, Rh, Pd, Ir, Pt)

L'étude des systèmes uranium-cobalt ou rhodium-étain a permis de mettre en evidence les nouveaux stannures ternaires: UCo1,45Sn2, U3Rh4Sn13, UM2Sn et U2M2Sn (M=Co, Rh). Certains d'entre eux ont des propriétés physiques intéressantes comme UCo1,45Sn2 qui présente une transition métamagnétique induite par des faibles champs ou U3Rh4Sn13 qui est considère comme un "fermions lourds" magnétiquement ordonne. D'autre part, l'étude de la nouvelle famille U2M2Sn montre que le comportement magnétique de l'uranium dans ces stannures est fortement influence par la nature de l'élement de transition M présent. Ceci a été expliqué par la force de l'hybridation 5f (U)-nd (M) qui dépend en particulier du nombre d'électrons d de l'élement M.non disponibl

Electrochemical Behaviour of Thick Rust Layers on Steel: Strategies for Protection of Cultural Heritage Artefacts

International audienceFor several decades, a large number of heritage collections are related to the technical and industrial field because society wishes to preserve those materials which constitute traces of our industrial development. Compared to the collection of archaeological artefacts, the industrial and technical heritage is composed of numerous objects in cast iron or steel as the collection of extraction machines of coal in the Mining History Centre of Lewarde (France), or has a huge size as U4 blast furnace in Uckange in France. The diagnosis of the conservation state and the choice of the restoration treatment are important questions that have to be solved by curators to avoid expensive restoration works.The purpose of this study is to characterize the key-parameters of the electrochemical behaviour of different thick rust layers, observed on these objects. Then, the objective is to propose a simple electrochemical strategy to block or to reduce the electrochemical activity of these complex systems in order to lower the degradation rate of structures, without applying thick organic coatings as paints or varnishes.Previous studies (1) have demonstrated that some iron(III) phases constituting the rust layer play a role in the corrosion processes during wet and dry periods, and can increase the corrosion rate of the underlying metal.On this kind of artefacts, two main rust layers were observed and characterized by combining metallographic observations and different techniques of materials analysis (X-ray diffraction, Raman spectroscopy): a ferrhydrite/goethite and magnetite/goethite rust systems. The electrochemical activity of the oxyhydroxide iron compounds was characterized by cyclic voltamperometry in a carbon paste electrode, and the total system “metal/rust layer” was described by electrochemical impedance spectroscopy in aqueous corrosive media in function of immersion time.Corrosion-inhibiting formulations in aqueous media based on sodium decanoate and decanoic acid solutions were set-up for the treatment of these rust systems, from previous studies (2, 3, 4). These compounds are non-toxic and fulfil the criteria (reversibility, no modification of the final visual appearance) for their application in the field of the cultural heritage conservation. The impedance measurements coupled with the analysis of the treated surface shows that the application of the inhibiting solution has a positive effect on both the chemical diffusion of iron species in the pores network of the layer and the electrical conductivity of the rust system. So, the electrochemical reactivity of several iron oxide phases is drastically reduced.From those experiments, it turns out that those inhibitor solutions represent an interesting alternative of new environmentally safe treatments for corroded iron artefacts

Electrochemical behavior of thick rust layers on steel artefact: Mechanism of corrosion inhibition

International audienceThe electrochemical behavior of aged corrosion layers (CL) on artefact was studied, in corrosive reference water without and with non-toxic corrosion inhibitors such as decanoate ions and flavonoids compounds, constituting the condensed tannins, such as catechin. Electrochemical impedance spectroscopy measurements on the metal/CL system and voltammetric studies of FeOOH phases on carbon paste electrode show that the corrosion inhibition mechanism is mainly based on the blocking of the dissolution of FeOOH-type phase and the decrease of the diffusion of ionic species in the pores network of CL. Indeed, the formation of iron decanoate, revealed by X-ray diffraction and microscopic observation, inhibits the electrochemical activity of FeOOH-type phases and blocks the electrochemical dissolution of FeOOH into Fe2+ cations. On the other hand, the catechin compound modifies the surface of rust compounds into a blue-black compound, but this modification has a poor influence on the electrochemical activity of FeOOH-type compounds

Local and structural characterisation of chlorinated phases formed on ferrous archaeological artefacts by μXRD and μXANES

International audienceThe deterioration after excavation of archaeological artefacts buried in soil is often associated with the presence of chlorine ions which play an important role in iron corrosion mechanisms. The understanding of these processes, related to the presence of chlorine, has to be made towards a precise study of the morphological and physicochemical properties of the iron corrosion products. A characterisation study on ferrous artefacts coming from four archaeological sites has been carried out; the rust layers have been studied using several techniques. The composition analyses were performed by energy dispersive spectroscopy coupled to scanning electron microscope. Structural information has been obtained by micro X-ray diffraction, micro Raman spectrometry and micro X-ray absorption experiments. The results obtained illustrate the necessity of the combination of these different techniques for the detailed study about corrosion typology

A complementary set of electrochemical and X-ray synchrotron techniques to determine the passivation mechanism of iron treated in a new corrosion inhibitor solution specifically developed for the preservation of metallic artefacts

International audienc

Conversion of steel by polyphenolic model molecules: Corrosion inhibition mechanism by rutin, esculin, esculetol

International audienceThis paper focuses on the potential corrosion protection of steel in presence of three polyphenolic model molecules (rutin, esculin, esculetol) in a weak acidic medium (pH = 4). From an electrochemical point of view, the cathodic inhibition was attributed to the oxygen scavenger role of the considered antioxidant compounds. SEM observations, Raman spectroscopy and Synchrotron X-ray absorption spectroscopy revealed furthermore the formation of a surface film by precipitation of iron polyphenolate conversion products, in which iron III is likely coordinated with free-catechol groups. Glycosylated catechol groups are rather adsorbed on a FeOOH layer

Development of an analytical methodology for the study of organic protection treatments for opper alloys

International audienc

Polychrome wares from Pakistani Makran, Mehrgarh/Nausharo (Pakistan) and Mundigak (Afghanistan): First results of the archaeometric studies

International audienc