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Electrochemical corrosion of magnetron sputtered WTiN-coated mild steels in a chloride medium

Alves, Valéria A.; Brett, Christopher M. A.; Cavaleiro, Albano
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Artigo de Revista Científica Formato: aplication/PDF
ENG
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45.94%
The electrochemical corrosion behaviour of WTiN coatings, of composition W 31, Ti 28 and N 40 at.% sputtered on carbon steel, chromium steel and high speed steel (HSS) has been investigated and the effect of the steel heat treatment on the steel/WTiN system performance explored. Open circuit potential measurements, polarisation curves and electrochemical impedance spectroscopy were used, together with X-ray diffraction and scanning electron microscopy to characterise the corroded and uncorroded coating/substrate systems. It was found that the influence of the substrate on corrosion resistance follows the order Carbon Steel

Corrosion behavior of Ti-xNb-13Zr alloys in Ringer`s solution

ROBIN, A.; CARVALHO, O. A. S.; Schneider, Sandra Giacomin; Schneider, Sérgio
Fonte: WILEY-V C H VERLAG GMBH Publicador: WILEY-V C H VERLAG GMBH
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
45.99%
Ti-6Al-4V alloy has been widely used in restorative surgery due to its high corrosion resistance and biocompatibility. Nevertheless, some studies showed that V and Al release in the organism might induce cytotoxic effects and neurological disorders, which led to the development of V-free alloys and both V- and Al-free alloys containing Nb, Zr, Ta, or Mo. Among these alloys, Ti-13Nb-13Zr alloy is promising due to its better biomechanical compatibility than Ti-6Al-4V. In this work, the corrosion behavior of Ti, Ti-6Al-4V, and Ti-xNb-13Zr alloys (x=5, 13, and 20) was evaluated in Ringer`s solution (pH 7.5) at 37 degrees C through open-circuit potential measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy. Spontaneous passivity was observed for all materials in this medium. Low corrosion current densities (in the order of 10(-7) A/cm(2)) and high impedance values (in the order of 10(5) Omega cm(2) at low frequencies) indicated their high corrosion resistance. EIS results showed that the passivating films were constituted of an outer porous layer (very low resistance) and an inner compact layer (high resistance), the latter providing the corrosion resistance of the materials. There was evidence that the Ti-xNb-13Zr alloys were more corrosion resistant than both Ti and Ti-6Al-4V in Ringer`s solution.; CNPq (Conselho Nacional de Desenvolvimento e Pesquisa-Brazil); PIBIC

Cr3C2-NiCr and WC-Ni thermal spray coatings as alternatives to hard chromium for erosion-corrosion resistance

ESPALLARGAS, N.; BERGET, J.; GUILEMANY, J. M.; BENEDETTI, A. V.; SUEGAMA, P. H.
Fonte: ELSEVIER SCIENCE SA Publicador: ELSEVIER SCIENCE SA
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
45.94%
Cr3C2-NiCr and WC-Ni coatings are widely used for wear applications at high and room temperature, respectively. Due to the high corrosion resistance of NiCr binder, Cr3C2-NiCr coatings are also used in corrosive environments. The application of WC-Ni coatings in corrosive media is 14 not recommended due to the poor corrosion resistance of the (pure Ni) metallic matrix. It is well known that the addition of Cr to the metallic binder improves the corrosion properties. Erosion-corrosion performance of thermal spray coatings is widely influenced by ceramic phase composition, the size of ceramic particles and also the composition of the metallic binder. In the present work, two types of HVOF thermal spray coatings (Cr3C2-NiCr and WC-Ni) obtained with different spray conditions were studied and compared with conventional micro-cracked hard chromium coatings. Both as-sprayed and polished samples were tested under two erosion-corrosion conditions with different erosivity. Tungsten carbide coatings showed better performance under the most erosive condition, while chromium carbide coatings were superior under less erosive conditions. Some of the tungsten carbide coatings and hard chromium showed similar erosion-corrosion behaviour under more and less erosive conditions. The erosion-corrosion and electrochemical results showed that surface polishing improved the erosion-corrosion properties of the thermally sprayed coatings. The corrosion behaviour of the different coatings has been compared using Electrochemical Impedance Spectroscopy (EIS) and polarization curves. Total material loss due to erosion-corrosion was determined by weight loss measurements. An estimation of the corrosion contribution to the total weight loss was also given. (c) 2007 Elsevier B.V. All rights reserved.

Síntese de filmes automontados de poli(o-metoxianilina) e nanopartículas de pentóxido de vanádio como cátodos em baterias de íon-lítio em líquido iônico; Self assembly of poly(o-methoxyaniline) and vanadium pentoxide nanoparticles as cathodes for lithium-ion batteries in ionic liquid

Nogueira, Filipe Braga
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 01/11/2012 PT
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O presente trabalho utilizou a técnica de automontagem camada-por-camada para produzir eletrodos híbridos de poli(o-metoxianilina) e nanopartículas de pentóxido de vanádio. Foram obtidos filmes acusticamente rígidos, homogêneos com relação à massa depositada e com crescimento linear com o número de bicamadas depositadas. A caracterização eletroquímica foi realizada por voltametria cíclica, onde esse filme apresentou alta capacidade de intercalação/desintercalação de íons lítio e de forma reversível. A capacidade eletroquímica desse filme foi então comparada com filmes automontados de poli(dialildimetilamônio)/V2O5 e polialilamina/V2O5. O filme de Poli(dialildimetilamônio) apresentou um crescimento irregular com dissolução das nanopartículas, o que resultou em uma capacidade eletroquímica extremamente inferior ao filme de poli(o-metoxianilina). O filme de polialilamina apresentou uma deposição mais eficiente de V2O5 que o filme de poli(o-metoxianilina), entretanto essa maior quantidade de pentóxido de vanádio não refletiu em um aumento da capacidade do eletrodo. Os resultados de espectroscopia de impedância eletroquímica mostram que o filme de polialilamina é significativamente mais resistivo que o filme de poli(o-metoxianilina). Essa diminuição da condutividade...

WC-CoCr coatings sprayed by high velocity oxygen-fuel (HVOF) flame on AA7050 aluminum alloy: electrochemical behavior in 3.5% NaCl solution

Magnani, Marina; Suegama, Patrícia Hatsue; Recco, Abel André Cândido; Guilemany, Josep Maria; Fugivara, Cecílio Sadao; Benedetti, Assis Vicente
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: 377-385
ENG
Relevância na Pesquisa
45.97%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); In the present work, the electrochemical behavior of WC-CoCr coatings with 10 (W10), 15 (W15) and 20 (W20) torch passes sprayed by High Velocity Oxygen-Fuel (HVOF) flame on AA7050 aluminum alloy substrate, evaluated in 3.5% NaCl solution, were compared using open-circuit potential (E OC) measurements, electrochemical impedance spectroscopy (EIS) and polarization curves. The coating surfaces and their cross sections were characterized by X ray diffraction and the Rockwell-C hardness test, and also by optical (OM) and scanning electron microscopy (SEM) before and after the corrosion tests. The electrochemical data showed that sample W10 presented higher corrosion resistance than the others in chloride solutions. In some tests, aluminum salts on the coating surface were identified by EDS, indicating the corrosion of the substrate. and using aluminon, aluminum ions were detected and analyzing the surface via stereomicroscopy, hydrogen bubbles were observed, both showing that the electrolyte reached the substrate and galvanic corrosion possibly occurred. The physical characterization showed that sample W10 presented a lower number of cracks and pores...

Effect of cerium on structure modifications of a hybrid sol-gel coating, its mechanical properties and anti-corrosion behavior

Cambon, Jean-Baptiste; Esteban, Julien; Ansart, Florence; Bonino, Jean-Pierre; Turq, Viviane; Santagneli, S. H.; Santilli, C. V.; Pulcinelli, S. H.
Fonte: Pergamon-Elsevier B.V. Ltd Publicador: Pergamon-Elsevier B.V. Ltd
Tipo: Artigo de Revista Científica Formato: 3170-3176
ENG
Relevância na Pesquisa
45.99%
An organic-inorganic hybrid coating was developed to improve the corrosion resistance of the aluminum alloy AA 2024-T3. Organic and inorganic coatings derived from glycidoxypropyltrimethoxysilane (GPTMS) and aluminum tri-sec-butoxide Al((OBu)-Bu-s)(3), with different cerium contents, were deposited onto aluminum by dip-coating process. Corrosion resistance and mechanical properties were investigated by electrochemical impedance measurements and nano-indentation respectively. An optimal cerium concentration of 0.01 M was evidenced. To correlate and explain the hybrid coating performances in relation to the cerium content, NMR experiments were performed. It has been shown that when the cerium concentration in the hybrid is higher than 0.01 M there are important modifications in the hybrid structure that account for the mechanical properties and anti-corrosion behavior of the sol-gel coating. (C) 2012 Elsevier Ltd. All rights reserved.

Influence of HVOF parameters on the corrosion and wear resistance of WC-Co coatings sprayed on AA7050 T7

Magnani, M.; Suegama, P. H.; Espallargas, N.; Dosta, S.; Fugivara, C. S.; Guilemany, J. M.; Benedetti, A. V.
Fonte: Elsevier B.V. Sa Publicador: Elsevier B.V. Sa
Tipo: Artigo de Revista Científica Formato: 4746-4757
ENG
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Thermal spray WC-based coatings are widely used in the aircraft industry mainly for their resistance to wear, reworking and rebuilding operations and repair of worn components on landing gear, hydraulic cylinders, actuators, propeller hub assemblies, gas turbine engines, and so on. The aircraft industry is also trying to use thermal spray technology to replace electroplating coatings such as hard chromium. In the present work, WC-Co coatings were built up on an AA 7050 aluminum alloy using high velocity oxygen fuel (HVOF) technology and a liquid nitrogen cooling prototype system. The influence of the spray parameters (standard conditions, W19S, increasing the oxygen flux, W19H, and also increasing the carrier gas flux, W19F) on corrosion, friction, and abrasive wear resistance were also studied. The coatings were characterized using optical (OM) and scanning electron (SEM) microscopy, and X-ray diffraction (XRD). The friction and abrasive wear resistance of the coatings were studied using Rubber Wheel and Ball on Disk tests. The electrochemical studies were conducted using open-circuit potential (E(oc)) measurements and electrochemical impedance spectroscopy (EIS). Differences among coated samples were mainly related to the variation of the thermal spray parameters used during the spray process. No significant differences were observed in the wear resistance for the coatings studied...

Electrochemical behavior of cobalt oxide coatings on cold-rolled steel in alkaline sodium sulfate

Silva, G. C.; Fugivara, C. S.; Tremiliosi, G.; Sumodjo, PTA; Benedetti, A. V.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 1875-1883
ENG
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The electrochemical behavior of a coating of cobalt oxide on cold-rolled steel in alkaline sodium sulfate was Studied using the electrochemical techniques of open-circuit potential measurements and electrochemical impedance spectroscopy. The coating was prepared at different annealing temperatures ranging from 350 to 750 degreesC and characterized by SEM, EDX and XRD. Below 550 degreesC the composition of the coating was basically of Co3O4. At 750 degreesC CoO was formed and big cracks appeared on the film exposing an inner layer of iron oxides. Analysis of the EIS data is very difficult because of the complexity of the interface structure. It can be inferred that the charge transfer resistance of the coatings prepared at 350 and 450 C were higher than those for the coatings prepared at temperatures above 550 degreesC. (C) 2002 Published by Elsevier B.V. Ltd.

Produção de eletrodos em carbono vítreo monolítico e reticulado a partir da resina furfurílica dopada com cobre

Ciavarelli, Vivian Maria
Fonte: Universidade Estadual Paulista (UNESP) Publicador: Universidade Estadual Paulista (UNESP)
Tipo: Trabalho de Conclusão de Curso
POR
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The glassy carbon is a material with a huge technological evolution. Due to its lightness, biocompatibility and their thermal and electrical properties this material finds applications in several industrial fields such as electronics, medical, aerospace and chemical. In order to explore the conductive properties of glassy carbon for use as modified electrodes, the present work aims the processing of monolithic and reticulated glassy carbon with colloidal copper for use in electrochemical applications. First, the best parameters for the cure of furfuryl alcohol resin doped were established through viscosimetry measurements and pressurized differential scanning calorimetry. The analysis of the micrographs of the cured resins show that copper concentrations above 3% weight, generate higher porosity in the material. The characterizations of the monolithic and reticulated glassy carbon resulting from carbonization were performed by scanning electron microscopy (SEM), Raman and Electrochemical impedance spectroscopy, and although it was not possible to detect the presence of copper by SEM, the influence of these particles have been observed by Raman and FT-IR spectra and electrochemical behavior of the material. The decrease in conductivity of monolithic and reticulated glassy carbon in the presence of copper may be related to the defects caused by the presence of copper in the structure of the material.; O carbono vítreo é um material carbonoso com ampla evolução tecnológica. Devido à sua leveza...

Development of an electrochemical immunosensor for Phakopsora pachyrhizi detection in the early diagnosis of soybean rust

Mendes,R. K.; Ferreira,D. C. M.; Carvalhal,R. F.; Peroni,L. A.; Stach-Machado,D. R.; Kubota,L. T.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2009 EN
Relevância na Pesquisa
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Soybean rust is a disease that occurs on soybean leaves and is considered very aggressive, reducing product quality. Early identification of fungus in the plants prevents severe farming losses as well as spreading to neighboring cultures. In this paper, a label-free immunosensor was developed based on impedance measurements to detect Asian rust on soybean leaf extract at the early stages of the disease. The antibody anti-mycelium of Phakopsora pachyrhizi fungus (disease agent) was immobilized on a gold substrate via a self-assembled monolayer (SAM) of thiols using covalent cysteamine coupling. This immunosensor presents a limit of detection of 385 ng mL-1. The optimization of experimental conditions and surface blocking to minimize non-specific adsorption on the immunosensor response were evaluated. These studies, based on electrochemical impedance spectroscopy (EIS), provide new perspectives on using this method for early diagnosis of soybean rust.

Electrochemical evidences of linalyl acetate (LA) adsorption on low-carbon steel in aqueous and ethanol medium

Grosser,Fabiana N.; Barros,Tainá I. T.; Gonçalves,Reinaldo S.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2014 EN
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The electrochemical behavior of low-carbon steel in 0.10 mol L-1 KNO3 aqueous solutions and 0.10 mol L-1 tetraethyl ammonium chloride ethanolic solutions was studied in absence and with different concentrations of linalyl acetate (LA). Electrochemical techniques such as potentiometry, cyclic voltammetry, chronoamperometry, Tafel polarization and electrochemical impedance spectroscopy were used in order to comprehend the interaction between the organic compound and electrode surface. Experiments involving weight loss measurements were performed. LA adsorbs on the low-carbon steel surface even in the presence of a large amount of water or ethanol. The adsorption energy for this process was -25.98 kJ mol-1 for aqueous solutions and -26.71 kJ mol-1 for ethanolic solutions. It was also detected that the adsorbed species on metal surface decreases the anodic current density values as well as the weight loss of the metal species. This effect allows us to classify the linalyl acetate as a green corrosion inhibitor of low-carbon steel in aqueous and ethanol medium.

WC-CoCr coatings sprayed by high velocity oxygen-fuel (HVOF) flame on AA7050 aluminum alloy: electrochemical behavior in 3.5% NaCl solution

Magnani,Marina; Suegama,Patrícia Hatsue; Recco,Abel André Cândido; Guilemany,Josep Maria; Fugivara,Cecílio Sadao; Benedetti,Assis Vicente
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2007 EN
Relevância na Pesquisa
45.97%
In the present work, the electrochemical behavior of WC-CoCr coatings with 10 (W10), 15 (W15) and 20 (W20) torch passes sprayed by High Velocity Oxygen-Fuel (HVOF) flame on AA7050 aluminum alloy substrate, evaluated in 3.5% NaCl solution, were compared using open-circuit potential (E OC) measurements, electrochemical impedance spectroscopy (EIS) and polarization curves. The coating surfaces and their cross sections were characterized by X ray diffraction and the Rockwell-C hardness test, and also by optical (OM) and scanning electron microscopy (SEM) before and after the corrosion tests. The electrochemical data showed that sample W10 presented higher corrosion resistance than the others in chloride solutions. In some tests, aluminum salts on the coating surface were identified by EDS, indicating the corrosion of the substrate. And using aluminon, aluminum ions were detected and analyzing the surface via stereomicroscopy, hydrogen bubbles were observed, both showing that the electrolyte reached the substrate and galvanic corrosion possibly occurred. The physical characterization showed that sample W10 presented a lower number of cracks and pores, justifying its higher corrosion resistance.

Lithium-Ion-Conducting Electrolytes: From an Ionic Liquid to the Polymer Membrane

Fernicola, A.; Weise, F. C.; Greenbaum, S. G.; Kagimoto, J.; Scrosati, B.; Soleto, A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 05/05/2009 EN
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This work concerns the design, the synthesis, and the characterization of the N-butyl-N-ethylpiperidinium N,N-bis(trifluoromethane)sulfonimide (PP24TFSI) ionic liquid (IL). To impart Li-ion transport, a suitable amount of lithium N,N-bis-(trifluoromethane)sulfonimide (LiTFSI) is added to the IL. The Li–IL mixture displays ionic conductivity values on the order of 10−4 S cm−1 and an electrochemical stability window in the range of 1.8–4.5 V vs Li+/Li. The voltammetric analysis demonstrates that the cathodic decomposition gives rise to a passivating layer on the surface of the working electrode, which kinetically extends the stability of the Li/IL interface as confirmed by electrochemical impedance spectroscopy measurements. The LiTFSI–PP24TFSI mixture is incorporated in a poly(vinylidene fluoride-co-hexafluoropropylene) matrix to form various electrolyte membranes with different LiTFSI–PP24TFSI contents. The ionic conductivity of all the membranes resembles that of the LiTFSI–IL mixture, suggesting an ionic transport mechanism similar to that of the liquid component. NMR measurements demonstrate a reduction in the mobility of all ions following the addition of LiTFSI to the PP24TFSI IL and when incorporating the mixture into the membrane. Finally...

Hydrothermal synthesis of MnO2/CNT nanocomposite with a CNT core/porous MnO2 sheath hierarchy architecture for supercapacitors

Xia, Hui; Wang, Yu; Lin, Jianyi; Lu, Li
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em 05/01/2012 EN
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MnO2/carbon nanotube [CNT] nanocomposites with a CNT core/porous MnO2 sheath hierarchy architecture are synthesized by a simple hydrothermal treatment. X-ray diffraction and Raman spectroscopy analyses reveal that birnessite-type MnO2 is produced through the hydrothermal synthesis. Morphological characterization reveals that three-dimensional hierarchy architecture is built with a highly porous layer consisting of interconnected MnO2 nanoflakes uniformly coated on the CNT surface. The nanocomposite with a composition of 72 wt.% (K0.2MnO2·0.33 H2O)/28 wt.% CNT has a large specific surface area of 237.8 m2/g. Electrochemical properties of the CNT, the pure MnO2, and the MnO2/CNT nanocomposite electrodes are investigated by cyclic voltammetry and electrochemical impedance spectroscopy measurements. The MnO2/CNT nanocomposite electrode exhibits much larger specific capacitance compared with both the CNT electrode and the pure MnO2 electrode and significantly improves rate capability compared to the pure MnO2 electrode. The superior supercapacitive performance of the MnO2/CNT nancomposite electrode is due to its high specific surface area and unique hierarchy architecture which facilitate fast electron and ion transport.

A New PC and LabVIEW Package Based System for Electrochemical Investigations

Stević, Zoran; Andjelković, Zoran; Antić, Dejan
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 15/03/2008 EN
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The paper describes a new PC and LabVIEW software package based system for electrochemical research. An overview of well known electrochemical methods, such as potential measurements, galvanostatic and potentiostatic method, cyclic voltammetry and EIS is given. Electrochemical impedance spectroscopy has been adapted for systems containing large capacitances. For signal generation and recording of the response of investigated electrochemical cell, a measurement and control system was developed, based on a PC P4. The rest of the hardware consists of a commercially available AD-DA converter and an external interface for analog signal processing. The interface is a result of authors own research. The software platform for desired measurement methods is LabVIEW 8.2 package, which is regarded as a high standard in the area of modern virtual instruments. The developed system was adjusted, tested and compared with commercially available system and ORCAD simulation.

Structural and electrochemical characterization of two proton conducting oxide thin films for a microfabricated solid oxide fuel cell

Capozzoli, Peter M
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 111 leaves
ENG
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The use of proton conducting oxide materials as an electrolyte offers the potential to reduce the operating temperature of a solid oxide fuel cell (SOFC), leading to improved thermal management and material compatibility. However, many proton conducting materials have not yet been investigated for residual stress and electrochemical properties in thin film form. This research characterizes the thermomechanical and electrochemical properties of two promising materials: Yttria doped Barium Cerate (BaCeo.9Yo0.O) and Terbium doped Strontium Cerate (SrCeo0.95TbYo.050O), for use in a microfabricated SOFC (gSOFC). Uniform, crack-free thin films of both compositions were produced by sputter deposition. Films with thickness ranging from 150 nm to 600 nm were deposited on a fused silica substrate. The desired composition was achieved for both films at a deposition temperature of 5750C, though minor secondary phases were also present. Residual stress for different film thicknesses was measured as a function of temperature using the wafer curvature technique.; (cont.) All films exhibited an initial compressive residual stress (from -200 to -600 MPa) and a significant tensile stress hysteresis upon thermal cycling, leaving a final residual stress at room temperature that ranged from -200 to +200 MPa. The average modulus-CTE product for films of each material was found to be - -0.65 MPa/ OC...

Anisotropic expansion and high rate discharge performance of V-doped MnO2 for Li/MnO2 primary battery

Wang, S.; Liu, Q.; Yu, J.; Zeng, J.
Fonte: Electrochemical Science Group Publicador: Electrochemical Science Group
Tipo: Artigo de Revista Científica
Publicado em //2012 EN
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V-doped MnO2 (VHEMD) has been prepared by thermally treating the mixture of electrolyzed manganese dioxide (EMD) and V2O5 powder and characterized using cyclic voltammetry (CV), constant current discharge, electrochemical impedance spectroscopy (EIS) and X-ray diffraction technique. CV results showed that VHEMD has a much higher reduction peak current than that of only thermally treated electrolyzed manganese dioxide (HEMD), though both have a similar reduction potential. Constant current discharge measurements showed VHEMD exhibits an improved high rate discharge performance. VHEMD reaches a maximum discharge capacity of 202 mAh g-1 at a high rate (2 mA cm-2), which is considerably higher than that of HEMD (155 mAh g-1), although both HEMD and VHEMD have similar discharge capacity at a low rate (0.1 mA cm-2). EIS results demonstrated that both Li+ insertion resistance (Rct) and Li+ diffusion impedance (W) in VHEMD were always lower than those of HEMD at any depth of discharge (DOD). XRD results confirmed that V-doping leads to an anisotropic expansion of MnO2 lattice, with a axis slightly elongated by 0.74% and c axis slightly shortened by 0.17%. The improved crystal structure after V-doping can be attributed to the faster kinetics of both Li+ insertion and diffusion in VHEMD.; http://www.electrochemsci.org/list12.htm#issue1; Shengping Wang...

Electrochemical Study of Pre- and Post-Transition Corrosion of Zr Alloys in PWR Coolant

MACAK Jan; NOVOTNY Radek; SAJDL Petr; RENCIUKOVA Veronika; VRTILKOVA Vera
Fonte: The Minerals, Metals & Materials Society (TMS) Publicador: The Minerals, Metals & Materials Society (TMS)
Tipo: Contributions to Conferences Formato: CD-ROM
ENG
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Corrosion properties of Zr-Sn and Zr-Nb zirconium alloys were studied under simulated PWR conditions at temperatures up to 340 oC and 15MPa using in-situe electrochemical impedance spectroscopy and polarization measurements. EIS spectra were obtained in a wide range of frequencies. It enabled to gain information of both dielectric properties of oxide layers developing on the Zr-alloys surface and of the kinetics of the corrosion process and the associated charge and mass transfer phenomena. Experiments were run for more than 380 days, thus the study of all the corrosion stages was possible. Experimental impedance spectra were approximated by equivalent circuits based models. Jonscher-type analysis was applied to estimate frequency independent oxide capacitance. A model based on integrated Stern-Geary equation was developed to correlate instant and integral corrosion rates of zirconium alloys.; JRC.F.4-Nuclear Reactor Integrity Assessment and Knowledge Management

Electrochemical Evaluation of Linseed Oil as Environment-friendly Inhibitor for Corrosion of Steel in HCl Solution

Afia,L; Salghi,R; Benali,O; Jodeh,S; Warad,I; Ebensod,E; Hammoutie,B
Fonte: Sociedade Portuguesa de Electroquímica Publicador: Sociedade Portuguesa de Electroquímica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/05/2015 EN
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The effect of linseed oil (LO) on the corrosion of carbon steel in 1 M HCl solution was investigated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) technique and weight loss measurements. The inhibiting action increases with the concentration of the tested inhibitor. The highest efficiency (98.2%) is obtained at 3g/L of LO. The influence of temperature on the corrosion behavior of carbon steel in 1 M HCl, with the addition of LO was also studied. The obtained data from EIS measurements were analyzed to model the corrosion inhibition process through an appropriate equivalent circuit model; a constant phase element (CPE) has been used. Polarization measurements show also that LO acts as a good mixed inhibitor. The inhibition process is attributed to the formation of an adsorbed film of the inhibitor on the metal surface which protects the metal against corrosion. LO is adsorbed on the steel surface according to a Langmuir isotherm adsorption model. The results obtained showed that the linseed oil could serve as an effective green inhibitor of the corrosion of carbon steel in hydrochloric acid medium.

Evaluation of Nicotiana Leaves Extract as Corrosion Inhibitor for Steel in Acidic and Neutral Chloride Solutions

Abd-El-Khalek,D.E.; Abd-El-Nabeyb,; Abdel-Gaberb,A.M.
Fonte: Sociedade Portuguesa de Electroquímica Publicador: Sociedade Portuguesa de Electroquímica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2012 EN
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The inhibition of steel corrosion in hydrochloric acid and sodium chloride solutions by Nicotiana leaves extract was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy measurements. Polarization curves showed that the extract behaves as a mixed type inhibitor in acidic medium, while it acts as anodic type in neutral medium. Impedance measurements indicated that the size of the semicircles obtained increased with increasing the concentration of the extract and decreasing the chloride ion concentration. Nicotiana leaves extract was found to be more effective in controlling corrosion of steel in acidic solution than in neutral one. The activation parameters of the corrosion reaction of steel in acid media in absence and presence of nicotiana leaves extract were also calculated and discussed.