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Avaliação da resistência à corrosão de titânio comercialmente puro submetido à desinfecção química e polarização em salivas artificiais com diferentes pHs; Evaluation of corrosion resistance of commercially pure titanium submitted to chemical disinfection and polarization in artificialsalivas with different pHs

Raimundo, Lariça Barbosa
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 26/08/2010 PT
Relevância na Pesquisa
36.26%
O objetivo desse estudo foi avaliar a ação de hipoclorito de sódio e ácido peracético na resistência à corrosão de titânio comercialmente puro, grau 4, (Ticp-4) em salivas artificiais, ácida e neutra, com diferentes períodos de imersão, por meio de ensaio de polarização potenciodinâmica anódica, microscopia eletrônica de varredura e espectrometria dispersiva de raios-X. Corpos-de-prova cilíndricos (5 mm x 5 mm) de Ticp-4 foram envolvidos com fio de cobre e fita isolante, este conjunto foi incluído em tubos de PVC (25 mm x 15 mm) e preenchidos com resina poliéster quimicamente ativada, após a polimerização da resina esses eletrodos de trabalho que foram polidos mecanicamente com lixas, feltros e pastas. Os 54 eletrodos de trabalho foram divididos em nove grupos (n=6) referentes às soluções e períodos de imersão: água destilada (controle), hipoclorito de sódio 1% (10 e 40 minutos), ácido peracético 0,2% (10, 30, 40 e 120 minutos) e ácido peracético 2% (30 e 120 minutos). Após serem imersos nas soluções, foram divididos em 2 subgrupos (n=3), pois os ensaios de polarização anódica foram realizados em triplicatas e utilizados dois eletrólitos, salivas artificiais pH 4,8 e pH 6,8. No ensaio de polarização anódica foi utilizada uma célula eletroquímica constituída por um eletrodo de referência do tipo calomelano saturado (ECS)...

Estudo da polarização ferroelétrica no copolímero P (VDF/TrFE); Study of ferroelectric polarization in P(VDF/TrFE) copolymer

Alves, Neri
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 29/04/1992 PT
Relevância na Pesquisa
36.29%
Usando-se a técnica do triodo de corona com corrente constante estudaram-se as propriedades ferroelétricas dos copolímeros P(VDF-TrFE) contendo diferentes teores de VDF. Descrevem-se as metodologias usadas na preparação de amostras por solução, a caracterização por raios X e DSC e a determinação do grau de cristalinidade. Apresentam-se o princípio de funcionamento da técnica do triodo de corona com corrente constante e a equivalência das curvas de potencial de superfície com as curvas de histerese. Mostra-se que a condução elétrica pode ser desprezada quando as medidas são realizadas em atmosfera com baixo valor de umidade. O valor do campo coercivo e da polarização remanente foram determinados a partir das curvas de subida do potencial de superfície, sendo o valor da polarização diretamente proporcional ao grau de cristalinidade das amostras. Esses resultados foram analisados supondo-se que os filmes de P(VDF-TrFE) podem ter duas fases cristalinas. Também são discutidos os modelos teóricos usados para interpretar as curvas de subida do potencial de superfície.; Ferroelectric properties of P(VDF-TrFE) copolymers having different contents of VDF were investigated using the corona triode with constant current. The casting procedure for the sample preparation...

SAE 1045 steel/WC-Co/Ni-Cu-Ni/SAE 1045 steel joints prepared by dynamic diffusion bonding: Microelectrochemical studies in 0.6 M NaCl solution

Andreatta, Francesco; Matesanz, Laura; Akita, Adriano H.; Paussa, Luca; Fedrizzi, Lorenzo; Fugivara, Cecilio S.; Gomez de Salazar, Jose M.; Benedetti, Assis V.
Fonte: Pergamon-Elsevier B.V. Ltd Publicador: Pergamon-Elsevier B.V. Ltd
Tipo: Artigo de Revista Científica Formato: 551-559
ENG
Relevância na Pesquisa
36.13%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Processo FAPESP: 07/53633-0; Corrosion of SAE 1045 steel/WC-Co/Ni-Cu-Ni/SAE 1045 steel interfaces was investigated in 0.6 M NaCl solution using an electrochemical microcell, which enables local electrochemical characterization at the micrometer scale. Two pieces of steel, one with a WC-Co coating covered with Ni (12 mu m) and Cu (5 mu m) layers, and the other with a Ni (15 mu m) layer,were welded by dynamic diffusion bonding. AWC-Co coating was applied to the steel by the high velocity oxygen-fuel process, and Ni-Cu and Ni layers by electroplating. Polarization curves were recorded using an electrochemical microcell. Different regions of welded samples were investigated, including steel, cermet coating, and steel/cermet and steel/Ni-Cu-Ni/cermet interfaces. Optical and electronic microscopes were employed to study the corroded regions. Potentiodynamic polarization curves obtained using the microcell revealed that the base metal was more susceptible to corrosion than the cermet. In addition, cermet steel/cermet and steel/Ni-Cu-Ni/cermet joints exhibited different breakdown potentials. Steel was strongly corroded in the regions adjacent to the interfaces...

Influence of cerium (IV) ions on the inorganic and organic phase for preparation of a siloxane-PMMA based film on tin plate substrate

Sarmento, V. H V; Diniz, R. N.; Benedetti, A. V.; Santilli, C. V.; Suegama, P. H.; Aoki, I. V.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência Formato: 2138-2147
ENG
Relevância na Pesquisa
46.21%
Tinplate is one of the most widely used food canning materials, however, there are significant problems related to the use of tinplate cans, such as alterations in sensory features affecting food quality and corrosion phenomena of the canning material. To avoid corrosion problems different methods have been used for the passivation of tinplate such protective lacquers or different kinds of corrosion inhibitors (chromate and dichromate). However, chromates and dichromates are extremely harmful to the environment and can cause carcinogenic tumors to humans. An option, protective coatings obtained by the sol-gel process, act as a physical barrier, which isolates the surface of metal protecting from the corrosive agents. The aim of this work is to study the influence of addition of cerium (IV) ions in the inorganic and organic part of sol-gel processing in the formation of hybrid coatings based on siloxane-PMMA on tin plate. The coatings were obtained by dip-coating technique and evaluated by open circuit and impedance measurements, linear polarization and polarization curves obtained in 3.5% NaCl solution. The results have clearly shown the improvement on the protective properties of the Ce 4+ modified film when added into the organic phase...

Study of the influence of the rare earth elements (Ce3+ and Ce4+) concentration on the siloxanes coating applied on the copper surface

Basho, É N.; Sakai, R. T.; Da Cruz, F. M D L; De Melo, H. G.; Benedetti, A. V.; Suegama, P. H.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência Formato: 3-7
ENG
Relevância na Pesquisa
46.05%
This work studied the influence of the rare earth (Ce3+ and Ce4+) elements concentration in polysiloxane flints deposited on copper by dip-coating process, and evaluated their resistance in a 3.5 wt.% NaCl medium. Classical electrochemistry techniques were used as open circuit potential, polarization curves and electrochemical impedance spectroscopy. The results revealed that by adding low concentration of Ce4+ ions, the coating prevents the electrolyte uptake any longer retarding the substrate degradation consequently. ©The Electrochemical Society.

Formation of silver chloride nanocrystals as a corrosion product of silver in H2SO4 solution

Picon, C. A.; Fernandes, F. A P; Machado, S. A P; Tremiliosi-Filho, G.; Casteletti, L. C.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência Formato: 199-202
ENG
Relevância na Pesquisa
36.17%
The purpose of this study is to characterize the corrosion product on the surface of silver, employing H2SO4 (0.5M) as electrolyte. The electrochemical parameters, Ecor, Icor, V cor and Rp were obtained after analyzing the potentiodynamic polarization curve in which two peaks were observed. The smallest (passive region) is attributed to the Cl- traces from the reference electrode, with micro-cracks. The second peak (in the transpassivation region) corresponds to the polarization curve of silver in H2SO 4 without contaminants. SEM images and EDS analysis reveal images of a surface layer on silver, consisting of structures containing sulfur, oxygen, silver and chloride, as the corrosion product. On this layer silver sulfate crystals were observed, which occurs during the formation of silver chloride nanocrystals with different morphologies, when chloride ions were added to the electrolyte medium. ©The Electrochemical Society.

Carbon nanotube-reinforced siloxane-PMMA hybrid coatings with high corrosion resistance

Hammer, P.; Dos Santos, F. C.; Cerrutti, B. M.; Pulcinelli, S. H.; Santilli, C. V.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 601-608
ENG
Relevância na Pesquisa
46.05%
Siloxane-polymethyl methacrylate hybrid films containing functionalized multiwall carbon nanotubes (CNTs) were deposited by dip-coating on carbon steel substrates from a sol prepared by radical polymerization of methyl methacrylate and 3-methacryloxy propyl-trimethoxysilane, followed by hydrolytic co-polycondensation of tetraethoxysilane. The correlation between the structural properties and corrosion protection efficiency was studied as a function of the molar ratio of nanotubes carbon to silicon, varied in the range between 0.1% and 5%. 29Si nuclear magnetic resonance and thermogravimetric measurements have shown that hybrids containing carbon nanotubes have a similar degree of polycondensation and thermal stability as the undoped matrix and exhibit and excellent adhesion to the substrate. Microscopy and X-ray photoelectron spectroscopy results revealed a very good dispersion of carbon nanotubes in the hybrid matrix and the presence of carboxylic groups allowing covalent bonding with the end-siloxane nodes. Potentiodynamic polarization curves and electrochemical impedance spectroscopy results demonstrate that CNTs containing coatings maintain the excellent corrosion protection efficiency of the hybrids, showing even a superior performance in acidic solution. The nanocomposite structure acts as efficient corrosion barrier...

Influence of ethanol, acidity and chloride concentration on the corrosion resistance of AISI 316L stainless steel

Ferreira, Elivelton A.; Noce, Rodrigo Della; Fugivara, Cecílio S.; Benedetti, Assis V.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 397-405
ENG
Relevância na Pesquisa
46.05%
The influence of ethanol, sulfuric acid and chloride on the corrosion resistance of 316L stainless steel was investigated by means of polarization curves and electrochemical impedance spectroscopy measurements. Over the studied range, the steel corrosion potential was independent of H2SO 4 and NaCl concentrations in aqueous solution. On the other hand, in solution containing 65 wt.% ethanol and 35 wt.% water, the corrosion potentials were higher than those obtained in aqueous solution. Besides, the steel corrosion potential was affected by the addition of H2SO4 and NaCl in solution. In solutions with and without ethanol, plus 0.35 wt.% NaCl, the presence of 1 wt.% H2SO4 inhibited the appearance of pitting corrosion. © 2013 Sociedade Brasileira de Química.

Hydrogen PEMFC stack performance analysis : a data-driven approach

Lopes, Vitor V.; Novais, Augusto Q.; Rangel, C. M.
Fonte: Hypothesis VII - Hydrogen - Power Theoretical and Engineering Solutions International Symposium Publicador: Hypothesis VII - Hydrogen - Power Theoretical and Engineering Solutions International Symposium
Tipo: Conferência ou Objeto de Conferência
Publicado em 01/04/2009 ENG
Relevância na Pesquisa
46.13%
For low power fuel cells, it is paramount that management of reactants, water and heat, be realized in a passive fashion in order to minimize parasitic losses. Effective fuel, oxygen supply and water management for reliable performance are also greatly affected by cell geometry and materials. Fuel cells are complex systems to optimize on a mere experimental basis. As an aid to this goal, data-driven analysis techniques, requiring no mathematical model to be fixed a priori, are gaining a reputation in other fields of work, where a phenomenological modeling approach might be intractable. This work presents a characterization study of a 12W PEMFC series stack by means of a new data-driven technique, M-NMF. The stack was developed for low temperature operation, uses own designed flow field plates, integrated in a series configuration, and is operated for 12 combinations of hydrogen/air flowrate ratios, generating as many polarization curves. M-NMF is applied, in combination with an alternating least squares algorithm, to the analysis of the overvoltage data matrix derived from the original experimental polarization data. From this analysis, it is possible to group and differentiate data according to similar overvoltage patterns and gain insight into their relative contribution to fuel cell performance immunization.

Influence of ethanol, acidity and chloride concentration on the corrosion resistance of AISI 316L stainless steel

Ferreira,Elivelton A.; Della Noce,Rodrigo; Fugivara,Cecílio S.; Benedetti,Assis V.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2013 EN
Relevância na Pesquisa
46.05%
The influence of ethanol, sulfuric acid and chloride on the corrosion resistance of 316L stainless steel was investigated by means of polarization curves and electrochemical impedance spectroscopy measurements. Over the studied range, the steel corrosion potential was independent of H2SO4 and NaCl concentrations in aqueous solution. On the other hand, in solution containing 65 wt.% ethanol and 35 wt.% water, the corrosion potentials were higher than those obtained in aqueous solution. Besides, the steel corrosion potential was affected by the addition of H2SO4 and NaCl in solution. In solutions with and without ethanol, plus 0.35 wt.% NaCl, the presence of 1 wt.% H2SO4 inhibited the appearance of pitting corrosion.

Effect of Toxic Components on Microbial Fuel Cell-Polarization Curves and Estimation of the Type of Toxic Inhibition

Stein, Nienke E.; Hamelers, Hubertus V. M.; van Straten, Gerrit; Keesman, Karel J.
Fonte: MDPI Publicador: MDPI
Tipo: Artigo de Revista Científica
Publicado em 11/07/2012 EN
Relevância na Pesquisa
46.4%
Polarization curves are of paramount importance for the detection of toxic components in microbial fuel cell (MFC) based biosensors. In this study, polarization curves were made under non-toxic conditions and under toxic conditions after the addition of various concentrations of nickel, bentazon, sodiumdodecyl sulfate and potassium ferricyanide. The experimental polarization curves show that toxic components have an effect on the electrochemically active bacteria in the cell. (Extended) Butler Volmer Monod (BVM) models were used to describe the polarization curves of the MFC under nontoxic and toxic conditions. It was possible to properly fit the (extended) BVM models using linear regression techniques to the polarization curves and to distinguish between different types of kinetic inhibitions. For each of the toxic components, the value of the kinetic inhibition constant Ki was also estimated from the experimental data. The value of Ki indicates the sensitivity of the sensor for a specific component and thus can be used for the selection of the biosensor for a toxic component.

Estudo de revestimentos inorgânicos com inibidor de corrosão aplicado na superfície do concreto

Nunes, Pollyanna Thaís Tavares Batista
Fonte: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Ciência e Engenharia de Materiais; Processamento de Materiais a partir do Pó; Polímeros e Compósitos; Processamento de Materiais a part Publicador: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Ciência e Engenharia de Materiais; Processamento de Materiais a partir do Pó; Polímeros e Compósitos; Processamento de Materiais a part
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
46.05%
The corrosive phenomenon on reinforced concrete structures is one of the most founded pathologies on the coastal area. With the objective to prevent the process development, or even, retard its beginning, it was studied the application of inorganic covering over concrete surfaces, after its cure, as well as, evaluate the efficiency of the covering applied on the concrete in reducing its porosity of concrete preventing the entrance of aggressive agents to preserve the integrity of the existing armor inside it, comparing the result obtained with the body-of-proof reference, that didn´t receive covering protection. On the concrete production it was used Portland Cement CP II 32, coarse aggregate, fine aggregate and water from the local distributive. Two types of covering were used, one resin based of silicon and solvent and other white cement based, selected sands and acrylic resin. The concrete mixture adopted was 1:1,5:2,5 (cement, fine aggregate, coarse aggregate) and 0.50 water/cement ratio. With the concrete on fresh state was made the experiment test to determinate the workability. On the hardened state was made the concrete resistance experiment, absorption of water and electrochemical experiments, through polarization curves. Also was held optical microscopy and Scanning Electron Microscopy experiments to analyze the layer of the covering applied to the concrete surface and the interface between the concrete and the layer. The obtained results shows that the covering applied to the concrete surface didn´t affect the resistance towards compression. On the absorption of water occurred a diminution of the percentage absorbed...

Polarization sensitivity of rainbow trout (Oncorhynchus mykiss) under natural photic conditions

Hauser, Frances E
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN
Relevância na Pesquisa
36.16%
The underwater photic environment provides spectral and polarization visual cues that fish use to guide their behaviour. Variation in the spectrum of underwater light affects how polarization stimuli are detected. Rainbow trout (Oncorhynchus mykiss) detect the polarization of light through the use of the UVS and LWS cone mechanisms – two differentially sensitive polarization detectors that overlap in the ultraviolet spectral region. However, since polarization sensitivity was previously measured under artificial background lighting, polarization sensitivity under natural lighting conditions has not yet been examined. Using compound action potential recordings from the optic nerve, I assessed the spectral sensitivity of juvenile rainbow trout under background lighting conditions that simulated a natural photic environment of rainbow trout, and found that this condition activated the UVS and LWS cone mechanisms. To define the spectral range over which polarization sensitivity is possible under natural lighting, I presented plane-polarized stimuli at a number of wavelengths that extend into the long wavelength region of the spectrum. I found that a plane-polarized ultraviolet stimulus activated both detector mechanisms, resulting in a “W”-shaped polarization sensitivity function. The activation of two differentially sensitive polarization detectors indicates the potential for discrimination between polarized stimuli in the natural environment. Contrary to our current understanding of the spectral limits of polarization sensitivity...

Photometric Light Curves and Polarization of Close-in Extrasolar Giant Planets

Seager, S.; Whitney, B. A.; Sasselov, D. D.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 03/04/2000
Relevância na Pesquisa
36.32%
The close-in extrasolar giant planets [CEGPs], $\ltorder$ 0.05 AU from their parent stars, may have a large component of optically reflected light. We present theoretical optical photometric light curves and polarization curves for the CEGP systems, from reflected planetary light. Different particle sizes of three condensates are considered. In the most reflective case, the variability is $\approx 100$ micromagnitudes, which will be easily detectable by the upcoming satellite missions MOST, COROT, and MONS, and possibly from the ground in the near future. The least reflective case is caused by small, highly absorbing grains such as solid Fe, with variation of much less than one micromagnitude. Polarization for all cases is lower than current detectability limits. We also discuss the temperature-pressure profiles and resulting emergent spectra of the CEGP atmospheres. We discuss the observational results of Tau Boo b by Cameron et al. (1999) and Charbonneau et al. (1999) in context of our model results. The predictions - the shape and magnitude of the light curves and polarization curves - are highly dependent on the size and type of condensates present in the planetary atmosphere.; Comment: 33 pages, accepted by ApJ

A polarimetric study of asteroids: Fitting phase - polarization curves

Cellino, A.; Bagnulo, S.; Gil-Hutton, R.; Tanga, P.; Canada-Assandri, M.; Tedesco, E. F.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 05/11/2015
Relevância na Pesquisa
46.25%
By considering all asteroid linear polarization data available in the literature, it is possible to obtain updated phase - polarization curves for several tens of objects. In a separate paper (Cellino et al., 2015a, MNRAS, 451, 3473) we have produced new calibrations of different relations between the geometric albedo and several polarimetric parameters, based on an analysis of a limited sample of asteroids for which the albedo is known with sufficient accuracy. In this paper, we present the main polarization parameters and corresponding albedos for a larger dataset of asteroids which we did not use for calibration purposes. We find a good agreement between the albedo values computed using different polarization parameters. Conversely, in the case of the so-called Barbarian asteroids the situation is rather unclear. Moreover, we present an updated analysis of the distributions of different polarimetric parameters, including the so-called inversion angle and the solar phase angle corresponding to the extreme value of negative polarization, and study their mutual relations. We find that the above parameters can be used to clearly distinguish some unusual classes of asteroids. Polarimetric parameters are known to be related to physical properties of asteroid surfaces which are difficult to infer by means of other observing techniques. By using a much larger dataset...

Microvariability in the optical polarization of 3C279

Andruchow, I.; Cellone, S. A.; Romero, G. E.; Dominici, T. P.; Abraham, Z.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 12/08/2003
Relevância na Pesquisa
36.13%
We present results of a microvariability polarization study in the violently variable quasar 3C279. We have resolved the polarization curves in the V band for this object down to timescales of minutes. We found two main components in the evolution of the degree of linear polarization, one consisting of a flicker with timescales of several tens of minutes and other component with far more significant variations on timescales of a few days. The linear polarization descended from $\sim 17$ % down to $\sim 8$ % in three nights. The polarization angle underwent a sudden change of more that 10 degrees in a few hours, perhaps indicating the injection of a new shock in the jet. The amplitude of the intranight flickering in the degree of polarization is at the level of $\sim 1$%. These are probably the best sampled polarization data ever obtained for this object. We also performed IR observations and we provide a follow-up of the evolution of this source at such energies after the main polarization outburst.; Comment: 10 pages, 9 figures, accepted for publication in A&A

Multi-q Pattern Classification of Polarization Curves

Fabbri, Ricardo; Bastos, Ivan N.; Neto, Francisco D. Moura; Lopes, Francisco J. P.; Goncalves, Wesley N.; Bruno, Odemir M.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 10/05/2013
Relevância na Pesquisa
46.35%
Several experimental measurements are expressed in the form of one-dimensional profiles, for which there is a scarcity of methodologies able to classify the pertinence of a given result to a specific group. The polarization curves that evaluate the corrosion kinetics of electrodes in corrosive media are an application where the behavior is chiefly analyzed from profiles. Polarization curves are indeed a classic method to determine the global kinetics of metallic electrodes, but the strong nonlinearity from different metals and alloys can overlap and the discrimination becomes a challenging problem. Moreover, even finding a typical curve from replicated tests requires subjective judgement. In this paper we used the so-called multi-q approach based on the Tsallis statistics in a classification engine to separate multiple polarization curve profiles of two stainless steels. We collected 48 experimental polarization curves in aqueous chloride medium of two stainless steel types, with different resistance against localized corrosion. Multi-q pattern analysis was then carried out on a wide potential range, from cathodic up to anodic regions. An excellent classification rate was obtained, at a success rate of 90%, 80%, and 83% for low (cathodic)...

Modeling of Polarization Losses of a Microbial Fuel Cell

Zhao, Li; Naviaux, John; Brouwer, Jacob; Hochbaum, Allon
Fonte: American Society of Mechanical Engineers Publicador: American Society of Mechanical Engineers
Tipo: Book Section; PeerReviewed Formato: application/pdf
Publicado em //2014
Relevância na Pesquisa
36.17%
Microbial fuel cells (MFCs) are promising for simultaneous treatment of wastewater and energy production. In this study, a mathematical model for microbial fuel cells with air cathodes was developed and demonstrated by integrating biochemical reactions, Butler-Volmer expressions and mass/charge balances. The model developed is focused on describing and understanding the steady-state polarization curves of the microbial fuel cells with various levels and methods of anode-biofilm growth with air cathodes. This polarization model combines enzyme kinetics and electrochemical kinetics, and is able to describe measured polarization curves for microbial fuel cells with different anode-biofilm growth. The MFC model developed has been verified with the experimental data collected. The simulation results provide insights into the limiting physical, chemical and electrochemical phenomena and their effects on cell performance. For example, the current MFC data demonstrated performance primarily limited by cathode electrochemical kinetics.

Electrochemical Study about Microorganisms Induced Corrosion in Inconel

Domínguez-Sánchez,G.; Tiburcio,C. Gaona; Almeraya-Calderón,F.M.; Martínez-Villafañe,A.
Fonte: Sociedade Portuguesa de Electroquímica Publicador: Sociedade Portuguesa de Electroquímica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2005 EN
Relevância na Pesquisa
46.05%
Inconel 600 has been designed to heat resistance. It is used in the chemistry industry, food industry and, of course, in the production of electric energy, among others. The goal of this project was to decrease the costs in the equipments and pipes deterioration by prolonging their lifetime, controlling and preventing their deterioration by means of appropriated and programmed maintenance, but above all knowing the mechanism and kinetic of corrosion that affects them. We used polarization curves to evaluate the effect of wild culture isolated from a traditional thermoelectric plant located northern Mexico. The studied culture was isolated by enrichment cultures in two phases, in a selective medium for sulfate-reductive bacteria in environmental temperature. It was selected for being thermo resistant and promising the largest influence in the corrosion rate. Inconel 600 keeps a multiple protection control until week 7, then it becomes an anodic protection control and later it becomes unstable to these cultures

Corrosion Resistance of Mo3Si with Niobium Additions in Hydrochloric Acid

Huicochea,C.; Rosales,I.; Castañeda,I.E.; Uruchurtu,J.
Fonte: Sociedade Portuguesa de Electroquímica Publicador: Sociedade Portuguesa de Electroquímica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2007 EN
Relevância na Pesquisa
46.13%
In the present work, the electrochemical behavior of molybdenum-silica-niobium alloy produced by arc cast technique is presented, keeping silica constant (at 24 wt %), using different niobium concentrations (5, 10, 15 & 20 wt %) as alloying elements. These samples were immersed in an electrochemical solution of 10 % by volume hydrochloric acid. The corrosion behavior was obtained using electrochemical techniques, namely: open circuit potential, polarization curves and electrochemical current noise. The potential behaviour as a function of time allows to determine the activity of the alloy as a function of its content, the polarization technique was used to obtain characteristic electrochemical parameters and the electrochemical current noise the type of attack while comparing them with the corrosion surface morphological features. Surface images showed different corrosion morphologies, being the most attacked the sample without niobium additions. It was found that niobium additions result in a better corrosion resistance when its concentration is increased in the alloy.