C. Rapin | Université de Lorraine (original) (raw)

Papers by C. Rapin

Journal of Nuclear Materials

Journal of Non-Crystalline Solids, 2022

Revue de Métallurgie, 1996

Le comportement de quelques carboxylates lineaires satures de sodium vis-a-vis de l’inhibition de... more Le comportement de quelques carboxylates lineaires satures de sodium vis-a-vis de l’inhibition de la corrosion aqueuse du cuivre a ete suivi par electrochimie. Il ressort de cette etude que les composes CH3 (CH2 )n-2 COONa, ou 6 < n < 11, sont des inhibiteurs dont l’efficacite est fonction de la longueur de leur chaine et de leur concentration. L’inhibition optimale est observee a partir d’une concentration critique, qui semble par ailleurs plus faible pour les longues chaines. Une etude toute particuliere a ete consacree a l’heptanoate de sodium. Les conditions optimales d’utilisation de cet inhibiteur ont ete precisees et le trace du diagramme E-pH a permis d’attribuer l’inhibition a la formation d’une couche barriere composee d’un melange d’hydroxyde et d’heptanoate cuivrique. L’effet accelerateur d’un oxydant fort tel le perborate de sodium a ete egalement examine.

L'Orthodontie Française, 2005

Le brevet du fil B-Titane mis au point par Burstone et Goldberg en 1979 est tombé dans le domaine... more Le brevet du fil B-Titane mis au point par Burstone et Goldberg en 1979 est tombé dans le domaine public. Plusieurs fournisseurs diffusent maintenant des fils réputés équivalents. Matériel Les compositions de 10 groupes de fils provenant de 9 fournisseurs différents ont été analysées : American Orthodontics (B-Ti®), Dentaurum (rematitan®Special), GAC (Résolve®), Highland Metals (Beta Blue®), Ormco (TMA® et Low Friction TMA®), OrthoPlus (Beta Plus®), RMO (Bendaloy®), TP Orthodontics (Ti Molium®), 3M Unitek (Beta I I I Titanium®). Ces fils sont des arcs préformés rectangulaires de section 0.017 x 0.025 inch (soit 0,43 x 0,64 mm). Méthode La détermination de la composition a été faite au microscope électronique à balayage par EDS (Energy Dispersion Spectrometry) pour les fils de American Orthodontics, Dentaurum, GAC, Ormco, OrthoPlus, RMO et 3M Unitek. Pour les fils de Highland Metals et de TP Orthodontics, l'analyse a été complétée par la microsonde électronique de Castaing. Discussion de la méthode L'analyse par EDS est suffisante pour déterminer la composition de 8 des 10 groupes de fils étudiés en se référant à celle donnée par Burstone. Par contre, d'autres éléments chimiques se trouvant dans les fils de Highland Metals et de TP Orthodontics, i l a été nécessaire d'utiliser la microsonde de Castaing pour compléter l'analyse par EDS. Résultats et discussion des résultats Les compositions trouvées pour les fils d'American Orthodontics, Dentaurum, GAC, Ormco, OrthoPlus, RMO et de 3M Unitek sont sensiblement identiques avec environ 80 % de titane, 11 % de molybdène, 4 % de zirconium, 4 % d'étain (% massique). Elles sont peu différentes de celles données par Burstone en 1979 (titane 79 %, molybdène 11 %, zirconium 6 %, étain 4 %). Par contre, le molybdène est en moins grand pourcentage chez Highland Metals (environ 4 %) ; chez TP Orthodontics aucune trace de molybdène mais une très grande proportion de titane (environ 90 %). De plus d'autres éléments : aluminium, vanadium et chrome sont présents chez Highland Metals et chez TP Orthodontics. Conclusion Les fils proposés actuellement aux orthodontistes pour remplacer le TMA® de Burstone n'ont pas tous une composition identique, et parfois même ne contiennent pas de molybdène.

Bulletin du Groupèment international pour la recherche scientifique en stomatologie & odontologie, 2011

Journal of Electroanalytical Chemistry, 2001

... very good ligands for metallic cations. Another major limitation to the use of all thesecoppe... more ... very good ligands for metallic cations. Another major limitation to the use of all thesecopper corrosion inhibitors is their aromaticity, which gives them a possible carcinogenic effect. The research of substitute compounds, more ...

Journal of Colloid and Interface Science, 2005

The influence of humidity on the electrical properties of α-Al 2 O 3 powders has been investigate... more The influence of humidity on the electrical properties of α-Al 2 O 3 powders has been investigated using adsorption isotherms, DC resistivity, and electrochemical impedance spectroscopy. Samples of two α-Al 2 O 3 particle sizes were examined, both individually and mixed together. The results show that the grain-bed resistivity decreases with humidity, whereas the grain capacitance is almost constant. The resistivity difference between the two particle sizes is of several orders of magnitude, while the capacitance values are not very different. These results are interpreted in terms of the layer-by-layer growth of water adsorbed on the grain surfaces. The first, more tightly bound adsorbed layer does not provoke the same effects as those layers adsorbed at higher relative humidity.

Electrochimica Acta, 1998

ÐInhibition of copper in a desearated sodium heptanoate solution (0.08 M, pH 8.0) by electro-oxid... more ÐInhibition of copper in a desearated sodium heptanoate solution (0.08 M, pH 8.0) by electro-oxidation has been investigated. R p measurements were carried out to compare inhibition eciency using this original method with that based on other usual chemical oxidation methods. In-situ spectroscopic and kinetic ellipsometric measurements have been performed to study the passivation mechanism of copper. The inhibition of copper is attributed to the formation of a protective layer composed of a mixture of copper II heptanoate and copper hydroxide. Two growth rates are observed during the passivation process. A model of a duplex layer is proposed. The thickness of the passive ®lm is evaluated at 14 2 1.5 nm.

Corrosion Science, 2004

The efficiency of linear sodium decanoate, CH 3 (CH 2) 8 COONa (noted NaC 10), as corrosion inhib... more The efficiency of linear sodium decanoate, CH 3 (CH 2) 8 COONa (noted NaC 10), as corrosion inhibitor of lead was determined by electrochemical techniques in two corrosive mediums: ASTM D1384 standard water and acetic acid-enriched solutions. Best results were obtained with 0.05 mol l À1 of NaC 10 solution. In these conditions, the inhibition efficiency can be estimated of 99.9%. The corrosion inhibition effect was confirmed by cyclic atmospheric tests in a climatic chamber in two different conditions: water saturated vapour, and acid acetic enriched vapour simulating the atmosphere in the wooden displays in museums. Surface analyses by SEM and X-ray diffraction indicate that the metal protection is due to the formation of a protective layer mainly composed of lead decanoate Pb(C 10) 2 (metallic soap). This inhibition treatment was applied on objects of metallic cultural heritage: gallo-roman sarcophagus in lead. Electrochemical methods confirm the efficiency of treatment on archaeological materials. In conclusion, this inhibitor treatment seems to be very promising against the atmospheric corrosion and the corrosion by organic acid vapour in museums.

Applied and Environmental Microbiology, 2002

Fenton reactions are believed to play important roles in wood degradation by brown rot fungi. In ... more Fenton reactions are believed to play important roles in wood degradation by brown rot fungi. In this context, the effect of tropolone (2-hydroxycyclohepta-2,4,6-trienone), a metal chelator, on wood degradation by Poria placenta was investigated. Tropolone (50 μM) strongly inhibits fungal growth on malt agar, but this inhibition could be relieved by adding iron salts. With an experimental system containing two separate parts, one supplemented with tropolone (100 μM) and the other not, it was shown that the fungus is able to reallocate essential minerals from the area where they are available and also to grow in these conditions on malt-agar in the presence of tropolone. Nevertheless, even in the presence of an external source of metals, P. placenta is not able to attack pine blocks impregnated with tropolone (5 mM). This wood degradation inhibition is related to the presence of the tropolone hydroxyl group, as shown by the use of analogs (cyclohepta-2,4,6-trienone and 2-methoxycyclo...

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Distributed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License

Materials Science Forum, 2004

Several cast strengthened superalloys, Ni base and Co base, were exposed to high temperature oxid... more Several cast strengthened superalloys, Ni base and Co base, were exposed to high temperature oxidation for long times and metallographically examined. Different phenomena occurred in the sub-surface microstructure, depending on both alloy and temperature. Thermodynamic modelling was used to know what it happened for carbon during oxidation, then to explain the observed microstructural changes. It appears that carbon atoms either quit the alloy probably after its oxidation into gases, or on the contrary go deeper into the bulk where they promote the precipitation of new carbides by solid state transformation. Thereafter, thermodynamic modelling allowed to know the new local refractoriness of the zones affected by oxidation, then to appreciate the new mechanical properties in the sub-surface.

Oxidation of Metals, 2005

Microstructure phenomena resulting from high temperature oxidation of three nickel base superallo... more Microstructure phenomena resulting from high temperature oxidation of three nickel base superalloys were studied by microstructure examinations. Disappearance, nature modification, volume fraction evolution or precipitation of carbides were observed in the alloys near the external surface, depending on the temperature and the chemical composition of the alloys. Thermodynamic calculations allowed to better know what happened to carbon and to quantify its new distribution. The studied alloys lost a more or less great part of their sub-surface carbon content at 1200°C while carbon seemingly diffused deeper in the alloy at 1100°C and 1000°C. The latter part of carbon promoted the coarsening of the pre-existing carbides, some modifications of their natures or the precipitation of new carbides in the matrix, then the occurrence of a new carbides zone.

Materials Science Forum, 2008

The efficiency of Waste-to-Energy (W-t-E) boilers is affected by fireside corrosion of the heat e... more The efficiency of Waste-to-Energy (W-t-E) boilers is affected by fireside corrosion of the heat exchangers that involve unexpected shutdown of facilities for repairs and limit the increase of steam conditions used to produce electricity. The parameters governing fireside corrosion are various and mechanisms are very complex, nevertheless, they are relatively well documented in the literature. In this paper, a laboratory-scale corrosion pilot, which reproduces MSWI boilers conditions, is described. The specificity of our approach includes simultaneous simulation of the temperature gradient at flue-gas/tube interface, the velocity of flue-gas and ashes. Corrosion rates obtained on Tu37C carbon steel at a metal temperature equal to 400°C and a flue gas temperatures of 650°C and 850°C (1100 ppm HCl, 110 ppm SO2 and synthetic ashes free of heavy metals) are respectively around 1.6 2m/hour and 5.6 2m/hour. Preferential metal loss, attributed to erosion-corrosion phenomena, is also observe...

The sintering process and microstructural characteristics of tungsten-based and molybdenum-based ... more The sintering process and microstructural characteristics of tungsten-based and molybdenum-based alloys containing chromium and group VIII metals as sintering agents have been investigated. The influences of the alloy composition, the nature of the sintering agent and the synthesis process on the microstructure and microhardness of these materials have been studied. Homogeneous alloys can be obtained with palladium or nickel as the sintering agent. The mechanisms are totally different with these two metals. In the case of nickel, diffusion of the refractory metals through a nickel layer is responsible for the densification of the alloys, whereas with palladium, a CrPd liquid phase at the grain boundaries leads to homogeneous sintering. Formation of the CrPd phase is directly dependent on the chromium content which influences the solubility of palladium in the MoW matrix. Consequently, a low chromium content leads to a high CrPd content, and to an increase in the grain size. On the contrary, with a nickel sintering agent, a high Ni content leads to an increase in thickness of the interdiffusion layer and thus a decrease in the grain size. Stresses generated by uniaxial sintering and mechanical alloying are not released during the annealing sequence and contribute to increase the microhardness of the alloys. Microhardness is also a strong function of the tungsten content.

Materials Science Forum, 2001

The microstructure and oxidation behaviour of tungsten and molybdenum based alloys containing chr... more The microstructure and oxidation behaviour of tungsten and molybdenum based alloys containing chromium, and group VIII metals as sintering agents, have been investigated. Good properties are observed with use of palladium which enhances the diffusion of chromium towards the metal-oxide interface. Contrary to palladium, nickel leads to a catastrophic oxidation of the sample: it segregates at the oxide/alloy interface and induces the formation of a non-protective oxide layer constituted with Cr 2 O 3 and NiWO 4 . Catastrophic oxidation occurs also when the refractory metals are transformed into volatile oxides: this is the case for the alloys with a high molybdenum concentration. Contrary to molybdenum, a high tungsten level leads to a high oxidation resistance, even at high temperature (1300°C.).