The Experts below are selected from a list of 141 Experts worldwide ranked by ideXlab platform
Akram Alfantazi - One of the best experts on this subject based on the ideXlab platform.
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Evaluating the Passivation of Corrosion of API-X100 Steel with Cyclic Voltammetry
Metallurgical and Materials Transactions B, 2017Co-Authors: Faysal Fayez Eliyan, Akram AlfantaziAbstract:In this research, cyclic voltammetry, in oxygen-free low bicarbonate-carbonate solutions, was used to study the corrosion reactions of a high-strength steel, API-X100. With cycles of different scan ranges, the effects of cycling, Transpassivation, and cathodic reduction on the electrochemistry of the passive films were analyzed. It was found that carbonate in higher concentrations reduces the anodic activity and the cathodic reactions of the surface. Bicarbonate in small concentrations in solutions that contained low carbonate concentrations catalyzed dissolution and disrupted the formation of the passive films, in reference to the measured anodic currents. From the experiments, there was electrochemical evidence that with more cycles, the passive films were growing thicker, the Transpassivation deteriorated the passive films, and during the cathodic reduction, the dissolution was occurring at lower potentials to facilitate later the passivation at higher potentials.
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Corrosion of New-Generation Steel in Outer Oil Pipeline Environments
Journal of Materials Engineering and Performance, 2017Co-Authors: Faysal Fayez Eliyan, J. R. Kish, Akram AlfantaziAbstract:New-generation high-strength pipeline steels are susceptible to corrosion attacks at their outer surfaces, from bicarbonate and carbonate in the hydrated soils in which pipelines are buried. The nature of the corrosion attacks requires implementing modified electrochemical methods by which the corrosion reactions can be studied comprehensively. From that, the findings can be linked to the alloying elements of the new pipeline materials, to modify them from both the strength and corrosion resistance perspectives. This paper presents an electrochemical study on the corrosion of API-X100 steel, in aerated bicarbonate-carbonate solutions, with cyclic voltammetry. At a fast 10 mV/s scan, over ten cycles, the passive films appeared as transparent layers, regardless of bicarbonate and carbonate concentrations. The surface controlled the reactions more than the passive films. The passive films showed evidence of forming gradually with increased cycling. Carbonate competed with bicarbonate during dissolution, decreasing its rate and making passivation faster. Bicarbonate in carbonate solutions catalyzed dissolution and disrupted passivation. The passive films with increased bicarbonate concentrations had higher Transpassivation potentials.
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Effect of bicarbonate concentration on corrosion of high strength steel
Corrosion Engineering Science and Technology, 2014Co-Authors: Faysal Fayez Eliyan, Akram AlfantaziAbstract:AbstractThis research evaluates the passivation process, in relation to the anodic and cathodic reactions, in deoxygenated solutions of different bicarbonate concentrations. Two types of API-X100 steel microstructures were examined. They are similar to near fusion heat affected zones (HAZs) which were produced by special thermal cycles. By monitoring the open circuit potentials, the passivation process exhibited electrochemical signs that it forms faster with higher bicarbonate concentration. During cyclic voltammetry, bicarbonate in concentrations less than 0·1M impedes the passivation, by catalysing the anodic dissolution. In higher concentrations, bicarbonate seemed more protective in facilitating the development of thicker passive films, from an electrochemical perspective that encourages corresponding physicochemical investigations in the future. The Transpassivation seemed to depend more on the chemistry of the passive film than on the formation of FeCO3. Cooling down the HAZs at high rates could ma...
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Corrosion Cyclic Voltammetry of Two Types of Heat-Affected Zones (HAZs) of API-X100 Steel in Bicarbonate Solutions
Metallurgical and Materials Transactions B, 2014Co-Authors: Faysal Fayez Eliyan, Akram AlfantaziAbstract:This paper examined the electrochemical corrosion behavior and corrosion products of two types of heat-affected HAZs made from API-X100 steel. Cyclic voltammetry, with different scan rates and potential ranges at 10 cycles, was applied to analyze the interdependent corrosion reactions of cathodic reduction, anodic dissolution, passivation, and Transpassivation. The HAZ cooled at 60 K/s, from a peak temperature of 1470 K (1197 °C) that was held for 15 seconds, exhibited better passivation and lower cathodic activity than the HAZ cooled at 10 K/s. Increasing bicarbonate concentration, from 0.05 and 0.2 to 0.6 M, increases the anodic activity and cathodic reduction, but accordingly protects the active surfaces and enhances passivation.
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Influence of temperature on the corrosion behavior of API-X100 pipeline steel in 1-bar CO2-HCO3− solutions: An electrochemical study
Materials Chemistry and Physics, 2013Co-Authors: Faysal Fayez Eliyan, Akram AlfantaziAbstract:Abstract This paper addresses on the influence of temperature, elucidated with a number of electrochemical methods and immersion tests, on the corrosion behavior of API-X100 steel in CO2-saturated bicarbonate solutions. Investigated by cyclic potentiodynamic polarization, the corrosion rates, which showed a sensible increase with 10 g L−1 (0.16 mol L−1), 30 g L−1 (0.5 mol L−1) and 50 g L−1 (0.82 mol L−1) bicarbonate concentrations, increased from about 500, to 1500 and 1800 μA cm−2 at 20, 50 and 90 °C, respectively. Passivation at 50 and 90 °C showed resistance to deteriorate against 100 ppm chloride ions, of which anodic 0.5 V vs. SCE peaks exclusively appeared. Moreover, Transpassivation occurred at 0.9 and 0.7 V vs. SCE, respectively, unlike with the 20 °C cases whose chloride-induced-pitting-vulnerable, gradually-forming passive films transpassivated at 1 V vs. SCE. At different potentials, the potentiostatic currents increased with temperature, but their profiles suggested more effective passivation, accordingly. The charge transfer resistance, calculated by electrochemical impedance spectroscopy, decreased with temperature at the open circuit potentials and 0.6 V vs. SCE, where the interfacial interactions were governed by adsorption, and diffusion-limited processes, respectively.
Silvia Maria Leite Agostinho - One of the best experts on this subject based on the ideXlab platform.
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The influence of albumin on the anodic dissolution of chromium present in UNS S31254 stainless steel in chloride environment
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2020Co-Authors: Mónica L. Afonso, Elizabeth P. G. Arêas, E. Oliveira, R.f.v. Villamil Jaimes, M.r. Capri, Silvia Maria Leite AgostinhoAbstract:The influence of bovine serum albumin (BSA) on the anodic dissolution of chromium present in UNS S31254 stainless steel (SS) in 0.15 mol L-1 NaCl at 37.0 +/- 0.5 degrees C has been studied, using anodic potentiostatic polarization curves and optical emission spectroscopy. Electrochemical results have shown that BSA has little effect on the Transpassivation potential (E-T) and on the passivation current density values. However on the passivation range, BSA diminishes the intensity of the anodic wave seen at about E=750mV versus SCE attributed to Cr(III)/Cr(VI) oxidation. Optical emission spectroscopy results have shown that BSA prevents the anodic dissolution of chromium to occur and minimizes iron dissolution above the Transpassivation potential (E=1160 mV versus SCE). (C) 2007 Elsevier B.V. All rights reserved
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Surface characterization, electrochemical behaviour and cytotoxicity of UNS S31254 stainless steel for orthopaedic applications
Materials Letters, 2015Co-Authors: Mónica L. Afonso, Ruth Flavia Vera Villamil Jaimes, Sizue O. Rogero, Pedro A.p. Nascente, Silvia Maria Leite AgostinhoAbstract:Abstract The surface characterization and electrochemical behaviour of UNS S31254 (254 SS) have been performed in 0.15 mol L −1 NaCl medium in order to evaluate its application as orthopaedic implants. Polarization curves, chronoamperometry, electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy were used for characterizing the samples. A cytotoxicity test was also performed to study the biocompatibility of the proposed steel as biomaterial. The electrochemical behaviour of 254 SS was compared to that observed for ISO 5832-9 and ASTM F138 stainless steels, used in orthopaedic implants. 254 SS is similar to ISO 5832-9 SS: it is passivated on the potential range between the corrosion and the Transpassivation potential. Mo (VI) forms an outer layer which blocks Cr (VI) dissolution. Cytotoxicity test showed no cytotoxic character of 254 SS.
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New material for orthopedic implants: Electrochemical study of nickel free P558 stainless steel in minimum essential medium
Materials Letters, 2010Co-Authors: Ruth Flavia Vera Villamil Jaimes, Mónica L. Afonso, Silvia Maria Leite Agostinho, Sizue Otta Rogero, Celso Antonio BarbosaAbstract:Abstract Nickel, a component of stainless steels (SS) applied in orthopedic implants may cause allergic processes in human tissues. P558 nickel free SS was studied to verify its viability as a substitute for stainless steel containing nickel. Its performance is compared to ISO 5832-9 and F138 most used nowadays grades in implants fabrications, in minimum essential medium, MEM, at 37 °C. Potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and “in vitro” cytotoxicity were used as techniques. From the electrochemical point of view P558 SS is comparable to ISO 5832-9 SS in MEM. It remains passivated until the Transpassivation potential, above which generalized corrosion occurs. F138 presents pitting corrosion at 370 mV/SCE. The cytotoxicity results showed that P558, ISO 5832-9 and F138 do not present cytotoxic character. Therefore, these results suggest that P558 SS can be applied in orthopedic implants.
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Estudo eletroquímico comparativo do aço ISO 5832-9 em diferentes meios de interesse biológico
Rem-revista Escola De Minas, 2010Co-Authors: Ruth Flavia Vera Villamil Jaimes, Mónica L. Afonso, Sizue O. Rogero, Celso Antonio Barbosa, Alexandre Sokolowski, Silvia Maria Leite AgostinhoAbstract:The electrochemical behavior of ISO 5832-9 stainless steel at 37 oC in 0.9% NaCl, Ringer Lactate and minimum essential medium (MEM) has been studied, using linear voltammetry, and surface analysis by SEM and EDS. Mechanical and toxicity tests were made. ISO 5832-9 is passivated at corrosion potential (Ecorr) and it does not present pitting corrosion on the media studied from Ecorr to 50 mV above the Transpassivation potential (Ei). SEM and EDS analysis have shown that the sample previously immersed in MEM presents a different behavior at 50 mV above Ei: the manganese oxide inclusions are absent in the surface. Ecorr values and passivation current density values jpass changed according to the following. Ecorr, RL < Ecorr,NaCl < Ecorr, MEM and jMEM
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The influence of albumin on the anodic dissolution of chromium present in UNS S31254 stainless steel in chloride environment
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2008Co-Authors: Mónica L. Afonso, R.f.v. Villamil Jaimes, Elizabeth P. G. Arêas, Maria Da Rosa Capri, E. Oliveira, Silvia Maria Leite AgostinhoAbstract:Abstract The influence of bovine serum albumin (BSA) on the anodic dissolution of chromium present in UNS S31254 stainless steel (SS) in 0.15 mol L−1 NaCl at 37.0 ± 0.5 °C has been studied, using anodic potentiostatic polarization curves and optical emission spectroscopy. Electrochemical results have shown that BSA has little effect on the Transpassivation potential (ET) and on the passivation current density values. However on the passivation range, BSA diminishes the intensity of the anodic wave seen at about E = 750 mV versus SCE attributed to Cr(III)/Cr(VI) oxidation. Optical emission spectroscopy results have shown that BSA prevents the anodic dissolution of chromium to occur and minimizes iron dissolution above the Transpassivation potential (E = 1160 mV versus SCE).
Faysal Fayez Eliyan - One of the best experts on this subject based on the ideXlab platform.
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Evaluating the Passivation of Corrosion of API-X100 Steel with Cyclic Voltammetry
Metallurgical and Materials Transactions B, 2017Co-Authors: Faysal Fayez Eliyan, Akram AlfantaziAbstract:In this research, cyclic voltammetry, in oxygen-free low bicarbonate-carbonate solutions, was used to study the corrosion reactions of a high-strength steel, API-X100. With cycles of different scan ranges, the effects of cycling, Transpassivation, and cathodic reduction on the electrochemistry of the passive films were analyzed. It was found that carbonate in higher concentrations reduces the anodic activity and the cathodic reactions of the surface. Bicarbonate in small concentrations in solutions that contained low carbonate concentrations catalyzed dissolution and disrupted the formation of the passive films, in reference to the measured anodic currents. From the experiments, there was electrochemical evidence that with more cycles, the passive films were growing thicker, the Transpassivation deteriorated the passive films, and during the cathodic reduction, the dissolution was occurring at lower potentials to facilitate later the passivation at higher potentials.
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Corrosion of New-Generation Steel in Outer Oil Pipeline Environments
Journal of Materials Engineering and Performance, 2017Co-Authors: Faysal Fayez Eliyan, J. R. Kish, Akram AlfantaziAbstract:New-generation high-strength pipeline steels are susceptible to corrosion attacks at their outer surfaces, from bicarbonate and carbonate in the hydrated soils in which pipelines are buried. The nature of the corrosion attacks requires implementing modified electrochemical methods by which the corrosion reactions can be studied comprehensively. From that, the findings can be linked to the alloying elements of the new pipeline materials, to modify them from both the strength and corrosion resistance perspectives. This paper presents an electrochemical study on the corrosion of API-X100 steel, in aerated bicarbonate-carbonate solutions, with cyclic voltammetry. At a fast 10 mV/s scan, over ten cycles, the passive films appeared as transparent layers, regardless of bicarbonate and carbonate concentrations. The surface controlled the reactions more than the passive films. The passive films showed evidence of forming gradually with increased cycling. Carbonate competed with bicarbonate during dissolution, decreasing its rate and making passivation faster. Bicarbonate in carbonate solutions catalyzed dissolution and disrupted passivation. The passive films with increased bicarbonate concentrations had higher Transpassivation potentials.
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Effect of bicarbonate concentration on corrosion of high strength steel
Corrosion Engineering Science and Technology, 2014Co-Authors: Faysal Fayez Eliyan, Akram AlfantaziAbstract:AbstractThis research evaluates the passivation process, in relation to the anodic and cathodic reactions, in deoxygenated solutions of different bicarbonate concentrations. Two types of API-X100 steel microstructures were examined. They are similar to near fusion heat affected zones (HAZs) which were produced by special thermal cycles. By monitoring the open circuit potentials, the passivation process exhibited electrochemical signs that it forms faster with higher bicarbonate concentration. During cyclic voltammetry, bicarbonate in concentrations less than 0·1M impedes the passivation, by catalysing the anodic dissolution. In higher concentrations, bicarbonate seemed more protective in facilitating the development of thicker passive films, from an electrochemical perspective that encourages corresponding physicochemical investigations in the future. The Transpassivation seemed to depend more on the chemistry of the passive film than on the formation of FeCO3. Cooling down the HAZs at high rates could ma...
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Corrosion Cyclic Voltammetry of Two Types of Heat-Affected Zones (HAZs) of API-X100 Steel in Bicarbonate Solutions
Metallurgical and Materials Transactions B, 2014Co-Authors: Faysal Fayez Eliyan, Akram AlfantaziAbstract:This paper examined the electrochemical corrosion behavior and corrosion products of two types of heat-affected HAZs made from API-X100 steel. Cyclic voltammetry, with different scan rates and potential ranges at 10 cycles, was applied to analyze the interdependent corrosion reactions of cathodic reduction, anodic dissolution, passivation, and Transpassivation. The HAZ cooled at 60 K/s, from a peak temperature of 1470 K (1197 °C) that was held for 15 seconds, exhibited better passivation and lower cathodic activity than the HAZ cooled at 10 K/s. Increasing bicarbonate concentration, from 0.05 and 0.2 to 0.6 M, increases the anodic activity and cathodic reduction, but accordingly protects the active surfaces and enhances passivation.
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Influence of temperature on the corrosion behavior of API-X100 pipeline steel in 1-bar CO2-HCO3− solutions: An electrochemical study
Materials Chemistry and Physics, 2013Co-Authors: Faysal Fayez Eliyan, Akram AlfantaziAbstract:Abstract This paper addresses on the influence of temperature, elucidated with a number of electrochemical methods and immersion tests, on the corrosion behavior of API-X100 steel in CO2-saturated bicarbonate solutions. Investigated by cyclic potentiodynamic polarization, the corrosion rates, which showed a sensible increase with 10 g L−1 (0.16 mol L−1), 30 g L−1 (0.5 mol L−1) and 50 g L−1 (0.82 mol L−1) bicarbonate concentrations, increased from about 500, to 1500 and 1800 μA cm−2 at 20, 50 and 90 °C, respectively. Passivation at 50 and 90 °C showed resistance to deteriorate against 100 ppm chloride ions, of which anodic 0.5 V vs. SCE peaks exclusively appeared. Moreover, Transpassivation occurred at 0.9 and 0.7 V vs. SCE, respectively, unlike with the 20 °C cases whose chloride-induced-pitting-vulnerable, gradually-forming passive films transpassivated at 1 V vs. SCE. At different potentials, the potentiostatic currents increased with temperature, but their profiles suggested more effective passivation, accordingly. The charge transfer resistance, calculated by electrochemical impedance spectroscopy, decreased with temperature at the open circuit potentials and 0.6 V vs. SCE, where the interfacial interactions were governed by adsorption, and diffusion-limited processes, respectively.
A. G. Maslennikov - One of the best experts on this subject based on the ideXlab platform.
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Electrochemical properties and dissolution of URu_3 in nitric acid solutions
Radiochemistry, 2016Co-Authors: S. V. Zavarzin, A. G. Maslennikov, K. N. Gedgovd, D. S. BulatovAbstract:The electrochemical properties of URu_3 intermetallic compound (IMC) in 0.5–8 M HNO_3 solutions were studied by linear voltammetry and galvanostatic electrolysis. In 0.5–2 M HNO_3, URu_3 occurs in the passive state at potentials lower than +1.3 V (here and hereinafter, vs. SHE), and in 4–8 M HNO_3, an anodic oxidation peak is observed at potentials from +1.0 to +1.2 V. This process, however, leads to IMC passivation and not to its dissolution. At potentials higher than +1.4 V, URu_3 passes into the transpassive state and starts to actively dissolve. The principal possibility of electrochemical dissolution of IMC at potentials exceeding the Transpassivation potential was demonstrated by galvanostatic electrolysis. The rate of uranium leaching during electrolysis depends to a greater extent on the current density than on the HNO_3 concentration and reaches 35 mg cm^–2 h^–1 in 6 M HNO_3 at a current density of 182 mA cm^–2.
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Electrochemical properties and dissolution of UPd3 in nitric acid solutions
Radiochemistry, 2016Co-Authors: S. V. Zavarzin, A. G. Maslennikov, K. N. Gedgovd, G. S. Bulatov, Irina E. VlasovaAbstract:The electrochemical properties of URu3 intermetallic compound (IMC) in 0.5–8 M HNO3 solutions were studied by linear voltammetry and galvanostatic electrolysis. In 0.5–2 M HNO3, URu3 occurs in the passive state at potentials lower than +1.3 V (here and hereinafter, vs. SHE), and in 4–8 M HNO3, an anodic oxidation peak is observed at potentials from +1.0 to +1.2 V. This process, however, leads to IMC passivation and not to its dissolution. At potentials higher than +1.4 V, URu3 passes into the transpassive state and starts to actively dissolve. The principal possibility of electrochemical dissolution of IMC at potentials exceeding the Transpassivation potential was demonstrated by galvanostatic electrolysis. The rate of uranium leaching during electrolysis depends to a greater extent on the current density than on the HNO3 concentration and reaches 35 mg cm–2 h–1 in 6 M HNO3 at a current density of 182 mA cm–2.
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An electrochemical study of the corrosion and dissolution of Tc-Ru alloys in HNO_3 solutions
Radiochemistry, 2015Co-Authors: K. V. Rotmanov, A. G. Maslennikov, E. M. Pichuzhkina, V. F. PeretrukhinAbstract:Electrochemical oxidation of Tc-Ru alloys in 0.5–6.0 M HNO_3 solutions was studied by linear voltammetry. Quantitative characteristics of the corrosion and dissolution processes were determined, namely: corrosion potentials E _corr, exchange current densities j _e and the corresponding corrosion rates v _corr, and Transpassivation potentials E _tp. The electrode reactions occurring in the course of electrochemical dissolution of Tc-Ru alloy differ essentially from those occurring on the surface of Tc metal electrodes. The exchange current density j _e and corrosion rate v _corr drastically decrease on alloying technetium with ruthenium. The corrosion potential E _corr of Tc-Ru alloys in HNO_3 solutions increases with an increase in the HNO_3 concentration and, at the same time, is virtually independent of the alloy composition. Comparison of the Transpassivation potentials of Tc-Ru alloys with those on electrodes made of pure Tc and Ru shows that Transpassivation potentials of Tc-Ru alloys were closer to E _tp of Ru metal throughout the examined range of HNO_3 concentrations. Thus, alloying of technetium with ruthenium enhances the resistance of the alloy to electrochemical oxidation in HNO_3 solutions.
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Electrochemical properties and dissolution of U-5 wt % Zr Alloy in HNO_3 solutions
Radiochemistry, 2014Co-Authors: S. A. Nikitin, A. G. MaslennikovAbstract:The main parameters of dissolution of U-5 wt % Zr alloy in HNO_3 solutions were determined by linear voltammetry. Without applying external potential, the electrode potential E ^0 in 0.5–6.0 M HNO_3 solutions increases. Its value is determined by the formation of a film containing hydrated Zr(IV) and U(IV) oxides and by the cathodic reduction of the acid. The reduction of NO_3 — ions on the surface of U-5 wt % Zr alloy in 0.5–6.0 M HNO_3 occurs with high overvoltage. In experiments without applying external potential, an increase in the HNO_2 yield in accordance with this reaction leads to an increase in the alloy dissolution rate with an increase in the HNO_3 concentration in the electrolyte from 0.5 to 6.0 M. At potentials higher than 450 mV vs. Ag/AgCl electrode, the U-5 wt % Zr electrode undergoes Transpassivation. Data on the electrolysis at controlled potential in the region close to the Transpassivation potential showed that an increase in the electrode potential at the given HNO_3 concentration leads to an increase in the alloy dissolution rate.
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Uranium and U-ZR and U-Ru alloy corrosion rates in the transpassive state
Journal of Alloys and Compounds, 2007Co-Authors: A. G. Maslennikov, A. A. Bessonov, Vladimir F. Peretroukhine, Natalya Budanova, K. N. Gedgovd, G. S. Bulatov, A. Y. Tsivadze, Calvin H. DelegardAbstract:Abstract Electrochemical studies of reactor-grade uranium metal and its alloys with Zr and Ru in neutral electrolyte (0.1 M NaClO 4 , pH 3.0–9.0) in the potential region close to uranium's Transpassivation threshold were performed. Transpassivation potentials from 320 mV/Ag/AgCl (U–1.3 at.% Zr) to 470 mV (U–10.5 at.% Ru) were found to be weakly affected by added alloying element concentration and electrolyte pH. Comparison of I – t curves registered on U metal, U–1.3 at.% Zr, and –1.2 at.% Ru electrodes indicate that the electrochemical oxidation rate of alloyed uranium was lower than that of pure U metal. The difference of the electrochemical oxidation rates was dependent on electrolyte pH. The calculated corrosion rates of uranium metal and alloy increased from 0.89 mg cm −2 h −1 (U–1.3 at.% Zr, E = 300 mV/Ag/AgCl) to 40.4 mg cm −2 h −1 (U metal, E = 600 mV/Ag/AgCl) and were found to be independent of alloy addition and electrolyte pH. The contribution of spallation of non-oxidized uranium species from the electrode surface to the observed corrosion rates was made.
Mónica L. Afonso - One of the best experts on this subject based on the ideXlab platform.
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The influence of albumin on the anodic dissolution of chromium present in UNS S31254 stainless steel in chloride environment
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2020Co-Authors: Mónica L. Afonso, Elizabeth P. G. Arêas, E. Oliveira, R.f.v. Villamil Jaimes, M.r. Capri, Silvia Maria Leite AgostinhoAbstract:The influence of bovine serum albumin (BSA) on the anodic dissolution of chromium present in UNS S31254 stainless steel (SS) in 0.15 mol L-1 NaCl at 37.0 +/- 0.5 degrees C has been studied, using anodic potentiostatic polarization curves and optical emission spectroscopy. Electrochemical results have shown that BSA has little effect on the Transpassivation potential (E-T) and on the passivation current density values. However on the passivation range, BSA diminishes the intensity of the anodic wave seen at about E=750mV versus SCE attributed to Cr(III)/Cr(VI) oxidation. Optical emission spectroscopy results have shown that BSA prevents the anodic dissolution of chromium to occur and minimizes iron dissolution above the Transpassivation potential (E=1160 mV versus SCE). (C) 2007 Elsevier B.V. All rights reserved
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Surface characterization, electrochemical behaviour and cytotoxicity of UNS S31254 stainless steel for orthopaedic applications
Materials Letters, 2015Co-Authors: Mónica L. Afonso, Ruth Flavia Vera Villamil Jaimes, Sizue O. Rogero, Pedro A.p. Nascente, Silvia Maria Leite AgostinhoAbstract:Abstract The surface characterization and electrochemical behaviour of UNS S31254 (254 SS) have been performed in 0.15 mol L −1 NaCl medium in order to evaluate its application as orthopaedic implants. Polarization curves, chronoamperometry, electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy were used for characterizing the samples. A cytotoxicity test was also performed to study the biocompatibility of the proposed steel as biomaterial. The electrochemical behaviour of 254 SS was compared to that observed for ISO 5832-9 and ASTM F138 stainless steels, used in orthopaedic implants. 254 SS is similar to ISO 5832-9 SS: it is passivated on the potential range between the corrosion and the Transpassivation potential. Mo (VI) forms an outer layer which blocks Cr (VI) dissolution. Cytotoxicity test showed no cytotoxic character of 254 SS.
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New material for orthopedic implants: Electrochemical study of nickel free P558 stainless steel in minimum essential medium
Materials Letters, 2010Co-Authors: Ruth Flavia Vera Villamil Jaimes, Mónica L. Afonso, Silvia Maria Leite Agostinho, Sizue Otta Rogero, Celso Antonio BarbosaAbstract:Abstract Nickel, a component of stainless steels (SS) applied in orthopedic implants may cause allergic processes in human tissues. P558 nickel free SS was studied to verify its viability as a substitute for stainless steel containing nickel. Its performance is compared to ISO 5832-9 and F138 most used nowadays grades in implants fabrications, in minimum essential medium, MEM, at 37 °C. Potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and “in vitro” cytotoxicity were used as techniques. From the electrochemical point of view P558 SS is comparable to ISO 5832-9 SS in MEM. It remains passivated until the Transpassivation potential, above which generalized corrosion occurs. F138 presents pitting corrosion at 370 mV/SCE. The cytotoxicity results showed that P558, ISO 5832-9 and F138 do not present cytotoxic character. Therefore, these results suggest that P558 SS can be applied in orthopedic implants.
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Estudo eletroquímico comparativo do aço ISO 5832-9 em diferentes meios de interesse biológico
Rem-revista Escola De Minas, 2010Co-Authors: Ruth Flavia Vera Villamil Jaimes, Mónica L. Afonso, Sizue O. Rogero, Celso Antonio Barbosa, Alexandre Sokolowski, Silvia Maria Leite AgostinhoAbstract:The electrochemical behavior of ISO 5832-9 stainless steel at 37 oC in 0.9% NaCl, Ringer Lactate and minimum essential medium (MEM) has been studied, using linear voltammetry, and surface analysis by SEM and EDS. Mechanical and toxicity tests were made. ISO 5832-9 is passivated at corrosion potential (Ecorr) and it does not present pitting corrosion on the media studied from Ecorr to 50 mV above the Transpassivation potential (Ei). SEM and EDS analysis have shown that the sample previously immersed in MEM presents a different behavior at 50 mV above Ei: the manganese oxide inclusions are absent in the surface. Ecorr values and passivation current density values jpass changed according to the following. Ecorr, RL < Ecorr,NaCl < Ecorr, MEM and jMEM
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The influence of albumin on the anodic dissolution of chromium present in UNS S31254 stainless steel in chloride environment
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2008Co-Authors: Mónica L. Afonso, R.f.v. Villamil Jaimes, Elizabeth P. G. Arêas, Maria Da Rosa Capri, E. Oliveira, Silvia Maria Leite AgostinhoAbstract:Abstract The influence of bovine serum albumin (BSA) on the anodic dissolution of chromium present in UNS S31254 stainless steel (SS) in 0.15 mol L−1 NaCl at 37.0 ± 0.5 °C has been studied, using anodic potentiostatic polarization curves and optical emission spectroscopy. Electrochemical results have shown that BSA has little effect on the Transpassivation potential (ET) and on the passivation current density values. However on the passivation range, BSA diminishes the intensity of the anodic wave seen at about E = 750 mV versus SCE attributed to Cr(III)/Cr(VI) oxidation. Optical emission spectroscopy results have shown that BSA prevents the anodic dissolution of chromium to occur and minimizes iron dissolution above the Transpassivation potential (E = 1160 mV versus SCE).
