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References

2015

Articles:

Hazotte, Claire, Meux, Eric, Leclerc, Nathalie and Lapicque, Francois
Chemical Engineering and Processing: Process Intensification, 96:83-93
2015

Mots clefs: Electroassisted leaching Electrodeposition Ni–Cd batteries Solid waste Transport rates

Resume: Abstract Combined leaching of solid wastes to electrodeposition can be an attractive technique for their optimal beneficiation. In most investigations in the area, results are given in terms of energy consumption and selectivity, without thorough analysis of the rates of the various processes involved. The present investigation deals with the significance of transport and transfer phenomena involved in relation to reaction processes, in a cell combining electroassisted leaching to electrodeposition in view to designing treatment processes of manufactured wares after their end of life. The case of the so-called black mass of used Ni–Cd batteries has been considered here, for the separate productions of nickel salts and metal cadmium. First, leaching of the various hydroxides contained in the black mass has been studied either upon addition of acid or by electrochemical generation of H+ at the anode. Moreover, transport of the metal cations produced from the anode compartment to the cathode through the cloth acting as the separator has been investigated through a simple description of transport phenomena. Comparison and discussion of the various transport or reaction rates could show that ion transport through the porous separator could represent the rate-determining step.

Equipe: Département CP2S : Chimie et électrochimie des matériaux

Hazotte, Claire, Leclerc, Nathalie, Diliberto, Sébastien, Meux, Eric and Lapicque, Francois
Environmental Technology, 36(6):796-805
2015

Resume: The aim of this paper is the characterization of spent NiCd batteries and the characterization of an industrial Black Mass obtained after crushing spent NiCd batteries and physical separation in a treatment plant. The characterization was first performed with five cylindrical NiCd batteries which were manually dismantled. Their characterization includes mass balance of the components, active powders elemental analysis and phase identification by X-ray powder diffraction. Chemical speciation of the two metals was also investigated. For cadmium, speciation was previously developed on solid synthetic samples. In a spent battery, the active powders correspond to about 43% of the battery weight. The other components are the separator and polymeric pieces (5%), the support plates (25%) and the carbon steel external case (27%). The sequential procedure shows that the nickel in the positive powders from the dismantled Ni?Cd batteries is distributed between Ni0 (39.7%), Ni(OH)2 (58.5%) and NiOOH (1.8%). Cadmium in the negative powder is about 99.9% as the Cd(OH)2 form with 0.1% of metal cadmium. In the industrial Black Mass, the distribution of cadmium is the same, whereas the distribution of nickel is Ni0 (46.9%), Ni(OH)2 (43.2%) and NiOOH (9.9%). This material contains also 1.8% cobalt and approx. 1% iron.

Equipe: Département CP2S : Chimie et électrochimie des matériaux

2014

Articles:

Hamdan, A., Noel, C., Ghanbaja, J. and Belmonte, T.
Plasma Chemistry and Plasma Processing, 34:1101-1114
2014

Equipe: Département CP2S : Expériences et Simulations des Plasmas Réactifs - Interaction plasma-surface et Traitement des Surfaces ESPRITS

ZHOU, T., COLIN, M., CANDOLFI, C., Boulanger, C., DAUSCHER, A., Santava, E., HEJTMANEK, J., BARANEK, P., AL RAHAL AL ORABI, R., POTEL, M., Fontaine, B., GOUGEON, P., Gautier, R. and LENOIR, B.
Chemistry of Materials, 26(16):4765-4775
2014

Resume: We present a detailed study of the evolution of the electrical, galvanomagnetic, and thermodynamic properties of polycrystalline AgxMo9Se11 compounds for 3.4 ? x ? 3.8 at low temperatures (2?350 K). In agreement with density functional theory calculations, the collected data show an overall gradual variation in the transport properties from metallic to semiconducting behavior on going from x = 3.4 to 3.8. The results evidence subtle variations in the electronic properties with the Ag content, typified by both positive and negative phonon-drag effects together with thermopower and Hall coefficient of opposite signs. Analysis of the data suggests that these features may be due to peculiarities of the dispersion of the valence bands in the vicinity of the chemical potential. A drastic influence of the Ag content on the thermal transport was evidenced by a pronounced change in the temperature dependence of the specific heat below 10 K. Nonlinearities in the Cp(T3) data are correlated to the concentration of Ag atoms, with an increase in x resulting in a more pronounced departure from a Debye law. The observed behavior mirrors that of ionic conductors, suggesting that AgxMo9Se11 for x ? 3.6 might belong to this class of compounds.

Equipe: Département CP2S : Chimie et électrochimie des matériaux

Jana, A., Briquet, L., WIRTZ, T., Philipp, P. and Henrion, G.
Nuclear Instruments and Methods in Physics Research B: Beam Interactions with Materials and Atoms, 326:341-344
2014

Resume: The deposition of multiple carbon atoms on a crystalline silicon (Si) surface is modelled at 5 eV energy by using molecular dynamics simulations combined with a third generation force field that includes bond breaking and formation. Force field parameters are taken from a previous work. These simulations allow for atomic scale insights into the deposition mechanisms and an easier comparison with experimental observations. The results, including distributions of implantation depth, carbon concentrations, sticking coefficients, radial distribution function, and angular distributions are compared for different incidence angles. Due to the deposition of carbon atoms inside the silicon structure, silicon carbide starts to form. The crystalline structure has been investigated for different conditions to get a better understanding of the damaging and growth mechanisms. It is found that a lot of deformation is accumulated in the area of deposition near to the surface but underneath the surface the silicon has still a more crystalline structure. The variation of the silicon (carbide) structu re slightly depends on the angle of incidence. For the conditions used for these simulations, the sticking probability is always high and varies between 95% and 100%, which can be attributed to the high affinity of carbon for silicon.

Equipe: Département CP2S : Expériences et Simulations des Plasmas Réactifs - Interaction plasma-surface et Traitement des Surfaces ESPRITS

Derkaoui, N., Rond, C., Gries, T., Henrion, G. and Gicquel, A.
Journal of Physics D: Applied Physics, 47:205201
2014

Resume: The electron temperature and electron density are measured in a microwave (MW) plasma-assisted chemical vapour diamond deposition reactor for different experimental conditions by varying the substrate temperature, methane content and MW power density. Optical emission spectroscopy (OES) and MW interferometry are used to probe the discharge generated in a stainless steel resonant cavity excited at a frequency of 2.45 GHz. Changing the substrate temperature from 630 to 900 ?C does not show any significant influence on the electron temperature or on the electron density. Increasing the methane content from 0 to 10% does not lead to any modification of the electron temperature or density. However between 10% and 20% CH, a decrease of the electron density is observed which may be attributed to soot particle formation. The electron density increases in the range of (1.2-10) x 1011 cm-3 from moderate power density conditions (50 hPa/1000 W) to high power density conditions (250 hPa/3500 W). OES measurements show that the electron temperature exhibits a flat axial profile in the plasma bulk and ranges from 14 000K at (25 hPa/600 W) to 10 500K at (400 hPa/3000 W).

Equipe: Département CP2S : Expériences et Simulations des Plasmas Réactifs - Interaction plasma-surface et Traitement des Surfaces ESPRITS

Martin, J., Leone, P., Nominé, A., Veys-Renaux, D., Henrion, G. and Belmonte, T.
Surface and Coatings Technology, In Press - available on line
2014

Resume: The chemical stability of the electrolyte in Plasma Electrolytic Oxidation (PEO) has been the subject of much systematic investigation. The present study reports on experimental results on the ageing of a usual PEO electrolyte and its effect on the oxidation of the Al2214 aluminium alloy. A solution of potassium hydroxide ([KOH] = 1 g/L) and sodium silicate ([Na2SiO3] = 1.65 g/L) diluted in deionized water was either aged by running a process during 8 h at most or not. Comparison between materials treated in either solution was made next. Cross-checked experimental results from analytical chemistry, plasma diagnostics and materials science clearly evidence the effect of ageing of the electrolyte on the PEO process behaviour. The transition from arc to "soft" regime occurs earlier (from 18 min to 13 min processing time) as the electrolyte gets older. The concomitant decrease in the electrolyte electrical conductivity (from 7.5 mS.cm-1 to 6.8 mS.cm-1) is correlated with changes in the ionic species content in the electrolyte. Fast video-imaging (125 kfr./s) reveals that the micro-discharge characteristics are also sensitive since they become less numerous per area and unit time (from 220.103 cm-2s-1 to 120.103 cm-2s-1), exhibit shorter lifetime and have smaller sizes as the electrolyte ages. SEM observations of the as-grown coatings combined with roughness measures indicate a decrease in coating thickness ( ~ 20 %) and roughness ( ~ 30 %) while species from the electrolyte accumulate in the outer porous layer simultaneously with a gradual enrichment in a-Al2O3 phase in the inner compact layer (from 36 % to 43 %). Finally, within the PEO conditions that were used, it is shown that the ageing phenomenon of the PEO electrolyte starts to influence the process after 2 hours aged.

Equipe: Département CP2S : Expériences et Simulations des Plasmas Réactifs - Interaction plasma-surface et Traitement des Surfaces ESPRITS

Veys-Renaux, D., ROCCA, E., Martin, J. and Henrion, G.
Electrochimica Acta, 124:30-45
2014

Resume: In the framework of the new ecological regulations, micro-arc oxidation (MAO) appears as an alternativeto usual processes in the field of corrosion protection of Mg alloys. In this work, the initial stagesof anodic layer growth in KOH-based electrolytes are studied up to and beyond the initiation of themicro-arc regime.The properties of the first anodized film preceding the occurrence of the dielectric breakdown (corre-sponding to the start of the micro-arc regime) are mainly determined by the incorporation of additives(fluorides or silicates) in the film, as shown by in situ electrochemical measurements. Scanning electronmicroscopy (SEM), X-ray photoelectron spectroscopy (XPS) and micro-Raman spectroscopy reveal boththe change of morphology and chemical state of silicate and fluoride in the anodized layer before andafter the micro-arc regime. In terms of electrochemical behaviour, investigated by stationary methodsand electrochemical impedance spectroscopy (EIS) in reference corrosive water, the anodic film grownin the silicate medium provides the best corrosion resistance thanks to a thick layer containing Mg2SiO4,whose degradation products seal the porosities of the coating.

Equipe: Département CP2S : Expériences et Simulations des Plasmas Réactifs - Interaction plasma-surface et Traitement des Surfaces ESPRITS

Belmonte, T., Hamdan, A., Kosior, F., Noel, C. and Henrion, G.
Journal of Physics D: Applied Physics, 47:224016 (18 pp)
2014

Resume: Discharge-surface interaction in liquids includes many phenomena which are reviewed in this work. This is used to examine results in the area of nanoparticle synthesis and to propose a general sketch of formation mechanisms.

Equipe: Département CP2S : Expériences et Simulations des Plasmas Réactifs - Interaction plasma-surface et Traitement des Surfaces ESPRITS

Gries, T., Catrin, R., Migot, S., SOLDERA, F., Endrino, J.L., Landa-Cánovas, A.R., Cleymand, F., Mangin, D., Mücklich, F. and Horwat, D.
ACS Applied Materials and Interfaces, 6:13707-13715
2014

Equipe: Département CP2S : Expériences et Simulations des Plasmas Réactifs - Interaction plasma-surface et Traitement des Surfaces ESPRITS

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