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Poly(glutamic acid) nanofibre modified glassy carbon electrode: Characterization by atomic force microscopy, voltammetry and electrochemical impedance

Santos, Daniela Pereira; Zanoni, Maria Valnice Boldrin; Bergamini, Márcio Fernando; Chiorcea-Paquim, Ana-Maria; Diculescu, Victor Constantin; Brett, Ana-Maria Oliveira
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Artigo de Revista Científica Formato: aplication/PDF
ENG
Relevância na Pesquisa
86.39%
Glassy carbon electrodes (GCE) were modified with poly(glutamic acid) acid films prepared using three different procedures: glutamic acid monomer electropolymerization (MONO), evaporation of poly(glutamic acid) (PAG) and evaporation of a mixture of poly(glutamic acid)/glutaraldehyde (PAG/GLU). All three films showed good adherence to the electrode surface. The performance of the modified GCE was investigated by cyclic voltammetry and differential pulse voltammetry, and the films were characterized by atomic force microscopy (AFM) and electrochemical impedance spectroscopy (EIS). The three poly(glutamic acid) modified GCEs were tested using the electrochemical oxidation of ascorbic acid and a decrease of the overpotential and the improvement of the oxidation peak current was observed. The PAG modified electrode surfaces gave the best results. AFM morphological images showed a polymeric network film formed by well-defined nanofibres that may undergo extensive swelling in solution, allowing an easier electron transfer and higher oxidation peaks.; http://www.sciencedirect.com/science/article/B6TG0-4PKPGY2-1/1/55de2306ffa3b92e8caefdef0c353957

Interaction of BSA protein with copper evaluated by electrochemical impedance spectroscopy and quartz crystal microbalance

Pinto, Edilson M.; Soares, David M.; Brett, Christopher M. A.
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Artigo de Revista Científica Formato: aplication/PDF
ENG
Relevância na Pesquisa
96.46%
The interaction of bovine serum albumin (BSA) protein with copper in phosphate buffer solution has been studied by a combination of electrochemical impedance spectroscopy (EIS) close to the open circuit potential, with simultaneous monitoring by the electrochemical quartz crystal microbalance (EQCM), in order to throw light on BSA adsorption. Copper films were electroplated onto gold quartz crystals and mounted in the EQCM. Experiments were conducted in the presence and absence of dissolved oxygen and of BSA and the results show the influence of O2 on the protein/metal interaction and also show specific interactions between BSA and copper. The good reproducibility obtained in these experiments suggests future application to other systems and which should lead to a better understanding of the use of such types of protein as corrosion inhibitors.; http://www.sciencedirect.com/science/article/B6TG0-4RSYCCD-5/1/a45edf5c4389350ee3577b6142716862

"Estudo da eletro-oxidação de monóxido de carbono sobre eletrocatalisadores suportados por espectroscopia de impedância eletroquímica"; Study of carbon monoxide electro-oxidation on supported electrocatalysts by electrochemical impedance spectroscopy

Ciapina, Eduardo Gonçalves
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 16/02/2006 PT
Relevância na Pesquisa
96.43%
O presente trabalho estudou comparativamente, do ponto de vista fundamental, a reação de eletro-oxidação de monóxido de carbono (CO) em meio ácido, sobre Pt75Sn25/C, Pt65Ru35/C e Pt/C através da Espectroscopia de Impedância Eletroquímica. Os materiais foram preparados por redução com ácido fórmico e caracterizados fisicamente por EDX e DRX de alta intensidade e eletroquimicamente por voltametria. Previamente aos estudos de Impedância, foram realizados estudos potenciodinâmicos da reação de eletro-oxidação de CO adsorvido (?Stripping de CO?) e a oxidação de CO em uma solução saturada de CO. Para os materiais Pt65Ru35/C e Pt/C, estes estudos mostraram que há um deslocamento de potencial do inicio da oxidação para valores mais positivos quando CO está presente em solução se comparado a oxidação (stripping) de CO, devido a competição de sítios de adsorção entre moléculas de CO e H2O, responsáveis pela reação. Por outro lado, no material bimetálico Pt75Sn25/C a presença de CO em solução não influenciou de maneira significativa o potencial de inicio da oxidação, confirmando a ausência de adsorção competitiva neste material. A curva de polarização em estado estacionário revelou que, dentre os 3 materiais estudados...

Uso da voltametria cíclica e da espectroscopia de impedância eletroquímica na determinação da área superficial ativa de eletrodos modificados à base de carbono; Use of cyclic voltammetry and electrochemical impedance spectroscopy for the determination of active surface area of modified carbon-based electrodes

Souza, Leticia Lopes de
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 28/07/2011 PT
Relevância na Pesquisa
86.46%
Eletrodos à base de carbono, como os eletrodos de troca iônica, entre outros, têm aplicação principalmente no tratamento de efluentes industriais e rejeitos radioativos. Carbono é também amplamente utilizado em células a combustível como substrato para os eletrocatalisadores, por possuir elevada área superficial, que supera a sua área geométrica. O conhecimento desta superfície ativa total é importante na determinação das condições de operação de uma célula eletroquímica no que diz respeito às correntes a serem aplicadas (densidade de corrente). No presente estudo foram utilizadas duas técnicas eletroquímicas na determinação da área superficial ativa de eletrodos de carbono vítreo e poroso e eletrodos de troca iônica: espectroscopia de impedância eletroquímica (EIE) e voltametria cíclica (VC). Os experimentos foram realizados com soluções de KNO3 0,1 mol.L-1 em célula eletroquímica de três eletrodos: eletrodo de trabalho à base de carbono, eletrodo auxiliar de platina e eletrodo de referência de Ag/AgCl. Os eletrodos de carbono vítreo e de carbono poroso utilizado possuíam uma área geométrica de 3,14 x 10-2 cm2 e 2,83 10-1 cm2, respectivamente. O eletrodo de troca iônica foi preparado misturando-se grafite...

Utilization of electrochemical impedance spectroscopy for monitoring bornite (CU5FeS4) oxidation by Acidithiobacillus ferrooxidans

Bevilaqua, Denise; Acciari, Heloisa Andréa; Arena, Fabiana A.; Benedetti, Assis V.; Fugivara, Cecilio S.; Tremiliosi Filho, Germano; Garcia Junior, Oswaldo
Fonte: Pergamon-Elsevier B.V. Ltd Publicador: Pergamon-Elsevier B.V. Ltd
Tipo: Artigo de Revista Científica Formato: 254-262
ENG
Relevância na Pesquisa
96.43%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); In this work, the monitoring of the bacterial and chemical dissolution of bornite was evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS); the mineral surface was examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The analysis of CV results allowed attributing the different peaks observed in both direct and reverse potential scanning to the oxidation of bornite to a secondary covellite and its reduction via different non stoichiometric copper sulphides intermediaries. EIS data for bornite were obtained in control medium up to 78 h of immersion, when a cellular suspension of A. ferrooxidans was added and the experiments continued up to a 192 h of test. The EIS response was different when bacteria were added in the beginning of the test or after some hours of immersion in acid solution. The experiments were performed in different cell configurations and a model of the electrode/electrolyte interface. The correspondent equivalent electrical circuit was used to fit impedance spectra for all studied conditions. A common equivalent circuit used for corrosion processes where anodic (degradation of the mineral) and cathodic (oxygen reduction) reactions occur in parallel...

Electrochemical impedance spectroscopy as a tool to estimate thickness in PB films

Gimenez-Romero, D.; Bueno, P. R.; Castano, C.; Gabrielli, C.; Perrot, H.; Garcia-Jareno, J. J.; Vicente, F.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 371-374
ENG
Relevância na Pesquisa
96.43%
The analysis of the faradaic impedance of electroactive films provides a characteristic point from which it is possible to estimate the thickness of thin films. Thus, electrochemical impedance spectroscopy was used in this paper as a fast and easy technique to estimate this thickness. The proposed method was checked on PB films. (c) 2006 Elsevier B.V. All rights reserved.

Poly(glutamic acid) nanofibre modified glassy carbon electrode: Characterization by atomic force microscopy, voltammetry and electrochemical impedance

Santos, Daniela Pereira; Zanoni, Maria Valnice Boldrin; Bergamini, Mdrcio Fernando; Chiorcea-Paquim, Ana-Maria; Diculescu, Victor Constantin; Brett, Ana-Maria Oliveira
Fonte: Pergamon-Elsevier B.V. Ltd Publicador: Pergamon-Elsevier B.V. Ltd
Tipo: Artigo de Revista Científica Formato: 3991-4000
ENG
Relevância na Pesquisa
86.39%
Glassy carbon electrodes (GCE) were modified with poly(glutamic acid) acid films prepared using three different procedures: glutamic acid monomer electropolymerization (MONO), evaporation of poly(glutamic acid) (PAG) and evaporation of a mixture of poly(glutamic acid)/glutaraldehyde (PAG/GLU). All three films showed good adherence to the electrode surface. The performance of the modified GCE was investigated by cyclic voltammetry and differential pulse voltammetry, and the films were characterized by atomic force microscopy (AFM) and electrochemical impedance spectroscopy (EIS). The three poly(glutamic acid) modified GCEs were tested using the electrochemical oxidation of ascorbic acid and a decrease of the overpotential and the improvement of the oxidation peak current was observed. The PAG modified electrode surfaces gave the best results. AFM morphological images showed a polymeric network film formed by well-defined nanofibres that may undergo extensive swelling in solution, allowing an easier electron transfer and higher oxidation peaks. (C) 2007 Elsevier Ltd. All rights reserved.

Oxidative dissolution of chalcopyrite by Acidithiobacillus ferrooxidans analyzed by electrochemical impedance spectroscopy and atomic force microscopy

Bevilaqua, D.; Diez-Perez, I; Fugivara, C. S.; Sanz, F.; Benedetti, A. V.; Garcia, O.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 79-84
ENG
Relevância na Pesquisa
96.47%
The microbiological leaching of chalcopyrite (CuFeS2) is of great interest because of its potential application to many CuFeS2-rich ore materials. However, the efficiency of the microbiological process is very limited because this mineral is one of the most refractory to bacterial attack. Knowledge of bacterial role during chalcopyrite oxidation is very important in order to improve the efficiency of bioleaching operation. The oxidative dissolution of a massive chalcopyrite electrode by Acidithiobacillus ferrooxidans was evaluated by electrochemical impedance spectroscopy (EIS) and atomic force microscopy (AFM). A massive chalcopyrite electrode was utilized in a Tait-type electrochemical cell in acid medium for different immersion times in the presence or absence of bacterium. The differences observed in the impedance diagrams were correlated with the adhesion process of bacteria on the mineral surface. (C) 2004 Elsevier B.V. All rights reserved.

Using the electrochemical impedance spectroscopy to characterize carbon steel in biodiesel medium

Akita, A. H.; Fugivara, C. S.; Aoki, I. V.; Benedetti, A. V.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência Formato: 71-77
ENG
Relevância na Pesquisa
96.62%
Electrochemical impedance spectroscopy measurements using two carbon steel electrodes in soybean biodiesel medium, produced by methylic route, were performed in an electrochemical cell that allows positioning the two electrodes face-to-face. To retain the biodiesel between the electrodes and prevent its leakage a porous membrane soaked in biodiesel was used. The amplitude of the AC potential and the area of the electrodes were varied. The linearity between disturbance and response signals was observed for tests when the amplitude of the AC potential was lower than 1500 mV (rms). The electrical resistance of biodiesel dominates the global response and carbon steel presents low corrosion, which is observed only at low frequency, and was confirmed by chemical tests performed in the membrane. In conclusion the electrical resistance of biodiesel can be estimated using electrochemical impedance spectroscopy with two electrodes set up. ©The Electrochemical Society.

Avaliação do estado de carga de baterias chumbo-acidas por espectroscopia de impedancia eletroquimica; Evaluation of lead-acid batteries state-of-charge by electrochemical impedance spectroscopy

Jose Rocha Andrade da Silva
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 27/10/2000 PT
Relevância na Pesquisa
96.43%
Os acumuladores de energia estacionários devem ser periodicamente avaliados quanto à sua capacidade de carga, visando assegurar que sua energia acumulada poderá ser prontamente utilizada, quando das falhas do sistema de alimentação convencional. Normalmente, essas avaliações são realizadas através dos testes de capacidade, que apresentam como principais desvantagens, o fato do banco de baterias permanecer indisponível, durante a realização do teste, e o desperdício da energia acumulada nas baterias. Neste trabalho á avaliada a potencialidade do método de espectroscopia de impedância eletroquímica como ferramenta na determinação do estado-de-carga de baterias chumbo-ácidas, através da análise das relações dos seus parâmetros eletroquímicos e sua quantidade de carga armazenada; Stationary lead-acid batteries must have their charge capacity periodically evaluated in order to assure that they are ready to supply energy during conventional supplier faults. Normally, these evaluations are conduct by capacity tests, which present these main disadvantages: batteries remain unavailable while tests are conducted and total energy accumulated in batteries is dissipate during the tests. In this work electrochemical impedance spectroscopy is evaluated as a tool to assess the lead....

Assessing cell polarity reversal degradation phenomena in PEM Fuel Cells by electrochemical impedance spectroscopy

Travassos, Maria Antónia; Lopes, Vitor V.; Novais, Augusto Q.; Rangel, C. M.
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em 12/12/2011 ENG
Relevância na Pesquisa
96.54%
The mechanisms of fuel cell degradation are multiple and not well understood. Irreversible changes in the kinetic and/or transport properties of the cell are fostered by thermal, chemical and mechanical issues which constrain stability, power and fuel cell lifetime. Within the in-situ diagnostics methods and tools available, in-situ electrochemical impedance spectroscopy (EIS) is within the most promising to better understand and categorize changes during fuel cell ageing. In this work, the degradation phenomena caused by cell polarity reversal due to fuel starvation of an open cathode 16 MEA (membrane-electrode assembly) –low power PEM fuel cell (15 W nominal power) is reported using EIS as a base technique. A frequency response analyzer from Solartron Model 1250 was used connected to an electrochemical interface also from Solartron, Model 1286. The range of covered frequencies spans from 37000 Hz to 0.01Hz. Hydrogen is supplied from a metallic hydride small reactor with a capacity of 50 NL H2 at a pressure of 0.2 bar. Measuring the potential of individual cells, while the fuel cell is on load, was found instrumental in assessing the “state of health” of cells at fixed current. Location of affected cells, those farthest away from hydrogen entry in the stack...

Assessing cell polarity reversal degradation phenomena in PEM fuel cells by electrochemical impedance sectroscopy

Travassos, Maria Antónia; Lopes, Vitor V.; Silva, R. A.; Novais, Augusto Q.; Rangel, C. M.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2013 ENG
Relevância na Pesquisa
86.39%
Electrochemical impedance spectroscopy (EIS) is identified as one of the most promising in-situ diagnostics tools available for assessing fuel cell ageing and degradation. In this work, the degradation phenomena caused by cell polarity reversal due to fuel starvation of an open cathode 16 membrane electrode assembly (MEA) – low power (PEM) fuel cell (15 W nominal power) – is reported using EIS as a base technique. Measuring the potential of individual cells, while the fuel cell is on load, was found instrumental in assessing the “state of health” of cells at fixed current. Location of affected cells, those farthest away from hydrogen entry in the stack, was revealed by very low or even negative potential values. EIS spectra were taken at selected break-in periods during fuel cell functioning. The analysis of impedance data was made using an a priori equivalent circuit describing the transfer function of the system in question –equivalent circuit elements were evaluated by a complex non-linear least square (CNLS) fitting algorithm, and by calculating and analyzing the corresponding distribution of relaxation times (DRT). Results and interpretation of cell polarity reversal due to hydrogen starvation were complemented with ex-situ MEA cross section analysis...

Characterization of self-assembled thiols monolayers on gold surface by electrochemical impedance spectroscopy

Mendes,Renata K.; Freire,Renato S.; Fonseca,Carla P.; Neves,Silmara; Kubota,Lauro T.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2004 EN
Relevância na Pesquisa
96.39%
Thiols with different alkyl chain length and containing COOH terminal group were self-assembled on gold electrodes. The electron transfer of Fe(CN)6(3-/4-) couple to the electrode was studied at different pH by means cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Changes in solution pH resulted in the charge variation of the self-assembled monolayer (SAM) terminal group and, consequently, the electrostatic interaction of SAM with the electroactive species in the solution.

Impedance spectroscopy study of nanopore arrays for biosensing applications

Kant, K.; Kurkuri, M.; Yu, J.; Shapter, J.G.; Priest, C.; Losic, D.
Fonte: American Scientific Publishers Publicador: American Scientific Publishers
Tipo: Artigo de Revista Científica
Publicado em //2014 EN
Relevância na Pesquisa
86.43%
Molecular or ion transport through a single nanopore or nanopore array is a key process in a number of applications including: molecular separation, biosensing, energy storage, nanofluidics and nanoelectronics. In this study, the electrochemical and electrical properties of nanopore arrays were investigated by electrochemical impedance spectroscopy (EIS), to explore their capability towards the development of improved nanopore biosensing devices. Anodic aluminum oxide (AAO) nanopore arrays with square patterns were fabricated by a photolithographic technique for use as a biosensing platform. To demonstrate the potential capability of these nanoporous arrays for biosensing applications, their internal surfaces were functionalized with a self-assembled monolayer of phosphonic acid; followed by covalent bonding with the model binding molecule streptavidin. The sensing performance of the prepared sensing device was characterized by EIS using different concentrations of biotin as probe molecule. The changes in impedance signal in response to the specific binding of biotin molecules to the streptavidin inside nanopores were monitored and explored depending on pore morphology. The results obtained for this system exhibit a high level of sensitivity and selectivity...

Evaluation of the dielectric properties of biodiesel fuels produced from different vegetable oil feedstocks through electrochemical impedance spectroscopy

M'Peko, Jean Claude; Reis, Diany L. S.; Souza, José E.; Caires, Anderson R. L.
Fonte: Elsevier; London Publicador: Elsevier; London
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
86.4%
Biodiesel fuels were prepared from different vegetable oil sources (canola, soybean, sunflower, and corn) and studied through electrochemical impedance spectroscopy. The dielectric constant from these biofuels evidenced no important dependence on feedstock, suggesting basically no change in fuels' polarity from varying the raw materials. In a different way, huge variations of the electrical resistivity and relaxation frequency were found when comparing among the studied biodiesels. Our findings demonstrate that these variations are closely associated with changes in the biodiesel viscosity, which is known to modulate charge mobility and was feedstock dependent. Accordingly, the impedance spectroscopy is here revealed to be a sensitive, alternative and reliable analytical approach for distinguishing among different feedstock-related biodiesels and monitoring certain biofuels' properties, like viscosity and interrelated parameters, usually connected with fatty acid structural profiles in biodiesel fuels.; FAPESP; FUNDECT; CNPq

Degradation characteristics of hydroxyapatite coatings on orthopedic TiAlV in simulated physiological media investigated by electrochemical impedance spectroscopy

Souto, R. M.; Laz, Maria M.; Reis, R. L.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em /10/2003 ENG
Relevância na Pesquisa
96.56%
This paper concentrates on the degradation characteristics of hydroxyapatite (HA) coatings on orthopaedic Ti-6Al-4V alloy while immersed in Ringer's salt solution, which were investigated by electrochemical impedance spectroscopy. Electrochemical impedance spectroscopy measurements were used to in situ characterize the electrochemical behavior of the passivated alloy covered with HA during aging in Ringer's solution. Comparison of the electrochemical data for the coated material with that for the uncoated metal substrate was also performed. The characteristic feature that describes the electrochemical behavior of the coated material is the coexistence of large areas of the coating itself with pores where the substrate is exposed to the aggressive media. The interpretation of results was thus performed in terms of a two-layer model of the film, in which the precipitation of hydrated oxide or phosphate compounds seals the pores left by the ceramic coating. The blocking effect due to salt precipitation inside the pores produces an enhancement of the resistance values, thus effectively diminishing the metal ion release in the system.; Collaborative Research Programme (Acción Integrada No. HP1995-0092 and HP1996-0109) between Spain and Portugal.

BARRIER PROPERTY DETERMINATION AND LIFETIME PREDICTION BY ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY OF A HIGH PERFORMANCE ORGANIC COATING

CALDERÓN-GUTIERREZ,JORGE ANDRÉS; BEDOYA-LORA,FRANKY ESTEBAN
Fonte: DYNA Publicador: DYNA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2014 EN
Relevância na Pesquisa
96.39%
The anticorrosion performance of an Epoxy-Mastic organic coating was evaluated during continuous immersion in saline solution using electrochemical impedance spectroscopy (EIS). The typical parameters of pore resistance and charge transfer resistance were determined employing an equivalent electric circuit. Constant phase elements (CPE) were used in order to determine fraction of water absorbed, mass diffusion, solubility and the swelling coefficients, as well as to predict the failure times of the coating. The results found by EIS measurements match very well with the high resistance to deterioration exhibited by the coating. It was also found that the excellent protection performance of the coating was mainly due to low water solubility and low permeability.

Studies on the Development of New Efficient Corrosion Inhibitors for Crude Oil Pipelines: Electrochemical Impedance Spectroscopy Results for 1,8-Naphthyridines

Álvarez-Manzo,Rodolfo; Mendoza-Canales,Joel; Castillo-Cervantes,Salvador; Marín-Cruz,Jesús
Fonte: Sociedad Química de México A.C. Publicador: Sociedad Química de México A.C.
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2013 EN
Relevância na Pesquisa
96.39%
Five 1,8-naphthyridines were tested as corrosion inhibitors, including three non-previously reported 3-alkyl-1,8-naphthyridines. All were produced via the extended Friedländer synthesis, that for 3-alkyl-1,8-naphthyridines involves the earliest use of aliphatic aldehydes. Fragmentation pattern in MS for 3-alkyl-1,8-naphthyridines shows a remarkable parallel with that exhibited by 3-alkylpyridines. Electrochemical Impedance Spectroscopy (EIS) was used to assess the inhibiting properties of these compounds on samples of API X52 carbon steel pipelines immersed in oilfield-related water. Except for one of the molecules tested, the inhibition efficiency (IE%) values were significantly higher than that calculated for a reference commercial inhibitor.

Effect of Process Parameters on Corrosion Resistance of Ni-P-Al2O3 Composite Coatings Using Electrochemical Impedance Spectroscopy

Gadhari,Prasanna; Sahoo,Prasanta
Fonte: Sociedade Portuguesa de Electroquímica Publicador: Sociedade Portuguesa de Electroquímica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2015 EN
Relevância na Pesquisa
96.43%
Electroless nickel composite coatings are developed by incorporating soft/hard particles into Ni-P coatings, to improve mechanical as well as tribological properties. The objective of the present work is to investigate the effect of various coating process parameters on the corrosion behavior of Ni-P-Al2O3 composite coating deposited on mild steel substrate. The electrochemical impedance spectroscopy test is used to evaluate the corrosion behavior of the heat treated composite coatings at various annealing temperatures (300 °C, 400 °C, and 500 °C). Corrosion properties, charge transfer resistance (Rct) and double layer capacitance (Cdl), are optimized using Taguchi based grey relational analysis to improve the corrosion resistance of the coating. Concentration of nickel source, concentration of reducing agent, concentration of alumina particles and annealing temperature, are considered as a main design factor for optimization of electrochemical properties. Analysis of variance (ANOVA) is used to find out the optimum combination of coating process parameters. From ANOVA result, it is found that the concentration of Al2O3 particles and annealing temperature have significant influence on the corrosion resistance of the composite coatings. Concentration of reducing agent has moderate influence on the corrosion resistance. Surface morphology of the coated surface is studied using SEM (scanning electron microscopy) and chemical composition of the coating is studied using EDX (energy dispersive X-ray analysis). The XRD (X-ray diffraction analysis) is used to understand the phase transformation behavior of the composite coatings.

Corrosion Study of Electroless Ni-P-W Coatings Using Electrochemical Impedance Spectroscopy

Roy,Supriyo; Sahoo,Prasanta
Fonte: Sociedade Portuguesa de Electroquímica Publicador: Sociedade Portuguesa de Electroquímica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/05/2012 EN
Relevância na Pesquisa
96.39%
The present study investigates the significance of different coating process parameters on the corrosion behaviour of electrolessly deposited Ni-P-W coatings on mild steel substrate. The process parameters considered are concentration of nickel source, concentration of reducing agent, concentration of tungsten source and annealing temperature. The corrosion characteristic is evaluated by electrochemical impedance spectroscopy technique. The responses considered are charge transfer resistance and double layer capacitance. The Taguchi technique coupled with grey analysis is employed to find out the optimum combination of the process parameters for better corrosion resistance. Analysis of variance (ANOVA) reveals the contribution of the process parameters on the corrosion property of Ni-P-W coating. Finally a validation test is performed to justify the experimental result. The microstructure of the surface is studied by scanning electron microscopy (SEM); energy dispersive x-ray analysis (EDX) reveals the chemical composition and the x-ray diffraction analysis (XRD) is used to identify the phase transformation behaviour of the coating.