Dépouillements

Microstructural properties of the bulk matrix and the steel/cement paste interface in reinforced concrete, maintained in conditions of corrosion and cathodic protection / D. A. Koleva in Materials and corrosion, Vol. 61 N° 7 (Juillet 2010) 

Public ISBD [article]  in Materials and corrosion > Vol. 61 N° 7 (Juillet 2010) . - pp. 561–567 Titre : Microstructural properties of the bulk matrix and the steel/cement paste interface in reinforced concrete, maintained in conditions of corrosion and cathodic protection Type de document : texte imprimé Auteurs : D. A. Koleva, Auteur ; Z. Guo, Auteur ; K. van Breugel, Auteur Année de publication : 2010 Article en page(s) : pp. 561–567 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : permeability;  porosity;  pore  size;reinforced  concrete;  steel/cement  paste  interface Résumé : Although rarely considered, especially within the investigation of steel corrosion phenomena or electrochemical protection techniques in reinforced concrete structures, the concrete bulk matrix has a significant contribution in the global performance of the system “reinforced concrete.” This is especially the case when chloride-induced corrosion or electrical current flow [as within impressed current cathodic protection (CP)] are involved. In the latter cases, the concrete bulk matrix undergoes significant alterations in chemical composition, electrical properties, and microstructures, thus influencing the overall performance of the system. This work reports on the microstructural investigation of the bulk concrete matrix and the steel/cement paste interface in reinforced concrete, previously subjected to corrosion and CP for 460 days. The emphasis hereby is to evaluate the altered structural properties, i.e., porosity, pore size, permeability of the bulk cement matrix, and the steel/cement paste interface (translated to bond strength) as a result of chloride-induced corrosion and two types of CP (conventional and pulse), compared to control (non-corroding, non-protected) conditions. The research revealed a major contribution and close dependence of all microlevel interfaces on the global performance of reinforced concrete. The electrical current flow (as in CP applications) was found to bring about unfavorable modifications to the material structure, both in the bulk matrix (reducing porosity) and at the steel/cement paste interface (enlarging interfacial gaps). The derived microstructural parameters show that the conventional CP leads to a higher level of structural heterogeneity, whereas the pulse CP exerts minimal or no effects, maintaining the material properties close to the reference (control) conditions, the underlying mechanism being a more homogeneous material microstructure. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905423/abstract [article] Microstructural properties of the bulk matrix and the steel/cement paste interface in reinforced concrete, maintained in conditions of corrosion and cathodic protection [texte imprimé] / D. A. Koleva, Auteur ; Z. Guo, Auteur ; K. van Breugel, Auteur . - 2010 . - pp. 561–567. Génie mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 61 N° 7 (Juillet 2010) . - pp. 561–567 Mots-clés : permeability;  porosity;  pore  size;reinforced  concrete;  steel/cement  paste  interface Résumé : Although rarely considered, especially within the investigation of steel corrosion phenomena or electrochemical protection techniques in reinforced concrete structures, the concrete bulk matrix has a significant contribution in the global performance of the system “reinforced concrete.” This is especially the case when chloride-induced corrosion or electrical current flow [as within impressed current cathodic protection (CP)] are involved. In the latter cases, the concrete bulk matrix undergoes significant alterations in chemical composition, electrical properties, and microstructures, thus influencing the overall performance of the system. This work reports on the microstructural investigation of the bulk concrete matrix and the steel/cement paste interface in reinforced concrete, previously subjected to corrosion and CP for 460 days. The emphasis hereby is to evaluate the altered structural properties, i.e., porosity, pore size, permeability of the bulk cement matrix, and the steel/cement paste interface (translated to bond strength) as a result of chloride-induced corrosion and two types of CP (conventional and pulse), compared to control (non-corroding, non-protected) conditions. The research revealed a major contribution and close dependence of all microlevel interfaces on the global performance of reinforced concrete. The electrical current flow (as in CP applications) was found to bring about unfavorable modifications to the material structure, both in the bulk matrix (reducing porosity) and at the steel/cement paste interface (enlarging interfacial gaps). The derived microstructural parameters show that the conventional CP leads to a higher level of structural heterogeneity, whereas the pulse CP exerts minimal or no effects, maintaining the material properties close to the reference (control) conditions, the underlying mechanism being a more homogeneous material microstructure. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905423/abstract

Lanthanide salts as thermal conversion coatings on silicon carbide reinforced AA5A06 aluminium metal matrix composite / I. Aziz in Materials and corrosion, Vol. 61 N° 7 (Juillet 2010) 

Public ISBD [article]  in Materials and corrosion > Vol. 61 N° 7 (Juillet 2010) . - pp. 568–573 Titre : Lanthanide salts as thermal conversion coatings on silicon carbide reinforced AA5A06 aluminium metal matrix composite Type de document : texte imprimé Auteurs : I. Aziz, Auteur ; Q. Zhang, Auteur Année de publication : 2010 Article en page(s) : pp. 568–573 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : EIS;  lanthanide  chloride;  silicon  carbide/AA5A06  aluminium  composite;  thermal  conversion  coating;  XPS Résumé : In this study, cerium and lanthanum chloride binary mixtures conversion coatings were investigated as corrosion inhibitors for silicon carbide particulates reinforced AA5A06 aluminium composite and AA5A06 aluminium alloy. Electrochemical impedance spectroscopy and potentiodynamic polarization tests revealed that cerium (III) chloride additions markedly improved the pitting corrosion resistance as compared to lanthanum (III) chloride additions, with maximum increase noted for samples treated with 750 ppm cerium (III) + 250 ppm lanthanum (III) chlorides. Scanning electron microscopy, energy dispersion spectroscopy and X-ray photoelectron spectroscopy examinations revealed the existence of a heterogeneous layer formed by precipitation of cerium/lanthanum oxide/hydroxide on the cathodic intermetallics and an aluminium oxide film on the rest of the metal matrix. Improved corrosion resistance was attained for SiC particulates reinforced aluminium composite by means of the cerium/lanthanum conversion treatment, due to the presence of mainly cerium (IV) species as a result of oxidation of cerium (III), which provides auto-protection properties. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905387/abstract [article] Lanthanide salts as thermal conversion coatings on silicon carbide reinforced AA5A06 aluminium metal matrix composite [texte imprimé] / I. Aziz, Auteur ; Q. Zhang, Auteur . - 2010 . - pp. 568–573. Génie mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 61 N° 7 (Juillet 2010) . - pp. 568–573 Mots-clés : EIS;  lanthanide  chloride;  silicon  carbide/AA5A06  aluminium  composite;  thermal  conversion  coating;  XPS Résumé : In this study, cerium and lanthanum chloride binary mixtures conversion coatings were investigated as corrosion inhibitors for silicon carbide particulates reinforced AA5A06 aluminium composite and AA5A06 aluminium alloy. Electrochemical impedance spectroscopy and potentiodynamic polarization tests revealed that cerium (III) chloride additions markedly improved the pitting corrosion resistance as compared to lanthanum (III) chloride additions, with maximum increase noted for samples treated with 750 ppm cerium (III) + 250 ppm lanthanum (III) chlorides. Scanning electron microscopy, energy dispersion spectroscopy and X-ray photoelectron spectroscopy examinations revealed the existence of a heterogeneous layer formed by precipitation of cerium/lanthanum oxide/hydroxide on the cathodic intermetallics and an aluminium oxide film on the rest of the metal matrix. Improved corrosion resistance was attained for SiC particulates reinforced aluminium composite by means of the cerium/lanthanum conversion treatment, due to the presence of mainly cerium (IV) species as a result of oxidation of cerium (III), which provides auto-protection properties. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905387/abstract

Effects of coolant chemistry on corrosion of 3003 aluminum alloy in automotive cooling system / Y. Liu in Materials and corrosion, Vol. 61 N° 7 (Juillet 2010) 

Public ISBD [article]  in Materials and corrosion > Vol. 61 N° 7 (Juillet 2010) . - pp. 574–579 Titre : Effects of coolant chemistry on corrosion of 3003 aluminum alloy in automotive cooling system Type de document : texte imprimé Auteurs : Y. Liu, Auteur ; Y. F. Cheng, Auteur Année de publication : 2010 Article en page(s) : pp. 574–579 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : aluminum  alloys;  automotive  cooling  system;  cation  impurities;  corrosion;  ethylene  glycol Résumé : In this work, effects of coolant chemistry, including concentrations of chloride ions and ethylene glycol and addition of various ions, on corrosion of 3003 Al alloy were investigated by electrochemical impedance spectroscopy measurements and scanning electron microscopy characterization. In chloride-free, ethylene glycol–water solution, a layer of Al-alcohol film is proposed to form on the electrode surface. With the increase of ethylene glycol concentration, more Al-alcohol film is formed, resulting in the increase in film resistance and charge-transfer resistance. In the presence of Cl− ions, they would be involved in the film formation, decreasing the stability of the film. In 50% ethylene glycol–water solution, the threshold value of Cl− concentration for pitting initiation is within the range of 100 ppm to 0.01 M. When the ethylene glycol concentration increases to 70%, the threshold Cl− concentration for pitting is from 0.01 to 0.1 M. In 100% ethylene glycol, there is no pitting of 3003 Al alloy even at 0.1 M of Cl−. Even a trace amount of impurity cation could affect significantly the corrosion behavior of 3003 Al alloy in ethylene glycol–water solution. Addition of Zn2+ is capable of increasing the corrosion resistance of Al alloy electrode, while Cu2+ ions containing in the solution would enhance corrosion, especially pitting corrosion, of Al alloy. The effect of Mg2+ on Al alloy corrosion is only slight. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905323/abstract [article] Effects of coolant chemistry on corrosion of 3003 aluminum alloy in automotive cooling system [texte imprimé] / Y. Liu, Auteur ; Y. F. Cheng, Auteur . - 2010 . - pp. 574–579. Génie mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 61 N° 7 (Juillet 2010) . - pp. 574–579 Mots-clés : aluminum  alloys;  automotive  cooling  system;  cation  impurities;  corrosion;  ethylene  glycol Résumé : In this work, effects of coolant chemistry, including concentrations of chloride ions and ethylene glycol and addition of various ions, on corrosion of 3003 Al alloy were investigated by electrochemical impedance spectroscopy measurements and scanning electron microscopy characterization. In chloride-free, ethylene glycol–water solution, a layer of Al-alcohol film is proposed to form on the electrode surface. With the increase of ethylene glycol concentration, more Al-alcohol film is formed, resulting in the increase in film resistance and charge-transfer resistance. In the presence of Cl− ions, they would be involved in the film formation, decreasing the stability of the film. In 50% ethylene glycol–water solution, the threshold value of Cl− concentration for pitting initiation is within the range of 100 ppm to 0.01 M. When the ethylene glycol concentration increases to 70%, the threshold Cl− concentration for pitting is from 0.01 to 0.1 M. In 100% ethylene glycol, there is no pitting of 3003 Al alloy even at 0.1 M of Cl−. Even a trace amount of impurity cation could affect significantly the corrosion behavior of 3003 Al alloy in ethylene glycol–water solution. Addition of Zn2+ is capable of increasing the corrosion resistance of Al alloy electrode, while Cu2+ ions containing in the solution would enhance corrosion, especially pitting corrosion, of Al alloy. The effect of Mg2+ on Al alloy corrosion is only slight. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905323/abstract

The electrochemical behavior of Sn–Ag binary alloys in sulfate solutions / M. A. Ameer in Materials and corrosion, Vol. 61 N° 7 (Juillet 2010) 

Public ISBD [article]  in Materials and corrosion > Vol. 61 N° 7 (Juillet 2010) . - pp. 580–589 Titre : The electrochemical behavior of Sn–Ag binary alloys in sulfate solutions Type de document : texte imprimé Auteurs : M. A. Ameer, Auteur ; A. A. Ghoneim, Auteur ; A. M. Fekry, Auteur Année de publication : 2010 Article en page(s) : pp. 580–589 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : corrosion;  impedance;  Na2SO4  solutions;  pure  Ag;  pure  Sn;  Sn–Ag  alloys Résumé : The corrosion and passivation behavior of four binary xSn–Ag (x = 26, 50, 70, and 96.5 wt%) alloys and their pure metal components was investigated in sodium sulfate solutions using electrochemical techniques. The influence of two different electrolytic parameters, namely, concentration (0.01–1.0 m) and pH (3.0–11.0) were studied while the specimens were potentiodynamically polarized between −1000 and 500 mV versus saturated calomel electrode (SCE). The results showed that the corrosion current density (icorr) increases with increasing either the tin content in the alloy or the ions concentration in the electrolyte. Increasing the pH value of a constant composition sulfate solution was found to improve the corrosion resistance of the tin-richer alloys (x = 50–96.5 wt%), and decreases a little the stability of the silver-rich one (74 wt% Ag). Impedance measurements at the free corrosion potential (Ecorr) give good support for these results, where a small addition of tin to silver up to the intermetallic ratio (x = 26 wt%) gives an alloy with better corrosion resistance to the aggressive sulfate medium. In terms of the tin ratio, the order of surface film stability on the tested samples, generally follows the ranking: 26 > 96.5 > 50 > Ag > 70 > Sn. The good corrosion resistance of the tin-rich alloy (x = 96.5 wt%), surpassing those for the pure constituents tin and silver can be attributed to the homogenous phase structure of this eutectic mixture. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905395/abstract [article] The electrochemical behavior of Sn–Ag binary alloys in sulfate solutions [texte imprimé] / M. A. Ameer, Auteur ; A. A. Ghoneim, Auteur ; A. M. Fekry, Auteur . - 2010 . - pp. 580–589. Génie mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 61 N° 7 (Juillet 2010) . - pp. 580–589 Mots-clés : corrosion;  impedance;  Na2SO4  solutions;  pure  Ag;  pure  Sn;  Sn–Ag  alloys Résumé : The corrosion and passivation behavior of four binary xSn–Ag (x = 26, 50, 70, and 96.5 wt%) alloys and their pure metal components was investigated in sodium sulfate solutions using electrochemical techniques. The influence of two different electrolytic parameters, namely, concentration (0.01–1.0 m) and pH (3.0–11.0) were studied while the specimens were potentiodynamically polarized between −1000 and 500 mV versus saturated calomel electrode (SCE). The results showed that the corrosion current density (icorr) increases with increasing either the tin content in the alloy or the ions concentration in the electrolyte. Increasing the pH value of a constant composition sulfate solution was found to improve the corrosion resistance of the tin-richer alloys (x = 50–96.5 wt%), and decreases a little the stability of the silver-rich one (74 wt% Ag). Impedance measurements at the free corrosion potential (Ecorr) give good support for these results, where a small addition of tin to silver up to the intermetallic ratio (x = 26 wt%) gives an alloy with better corrosion resistance to the aggressive sulfate medium. In terms of the tin ratio, the order of surface film stability on the tested samples, generally follows the ranking: 26 > 96.5 > 50 > Ag > 70 > Sn. The good corrosion resistance of the tin-rich alloy (x = 96.5 wt%), surpassing those for the pure constituents tin and silver can be attributed to the homogenous phase structure of this eutectic mixture. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905395/abstract

Influence of ball-milling on the oxidation behavior of Ag–Zn alloy powders / D. Q. Yi in Materials and corrosion, Vol. 61 N° 7 (Juillet 2010) 

Public ISBD [article]  in Materials and corrosion > Vol. 61 N° 7 (Juillet 2010) . - pp. 590–598 Titre : Influence of ball-milling on the oxidation behavior of Ag–Zn alloy powders Type de document : texte imprimé Auteurs : D. Q. Yi, Auteur ; C. P. Wu, Auteur ; S. Goto, Auteur Année de publication : 2010 Article en page(s) : pp. 590–598 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Ball-milling;  diffusion;  oxidation;  silver–zinc  alloy Résumé : The gas atomized Ag–15.2 at% Zn alloy powders were treated using ball-milling. The effect of ball-milling on surface morphology, microstructure, and oxidation behavior of the alloy powders was investigated. The results showed that ball-milling treatment enhanced the oxidation rate of Ag–Zn alloy powders due to the increase of dislocation density and the decrease of the diffusion distance of oxygen during internal oxidation. The fully oxidized time of Ag–Zn alloy powders decreases with the ball-milling time. In addition, the ball-milling treatment not only changes the oxidation mechanism but also improves microstructure and properties of the Ag–ZnO materials fabricated by internal oxidation. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905334/abstract [article] Influence of ball-milling on the oxidation behavior of Ag–Zn alloy powders [texte imprimé] / D. Q. Yi, Auteur ; C. P. Wu, Auteur ; S. Goto, Auteur . - 2010 . - pp. 590–598. Génie mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 61 N° 7 (Juillet 2010) . - pp. 590–598 Mots-clés : Ball-milling;  diffusion;  oxidation;  silver–zinc  alloy Résumé : The gas atomized Ag–15.2 at% Zn alloy powders were treated using ball-milling. The effect of ball-milling on surface morphology, microstructure, and oxidation behavior of the alloy powders was investigated. The results showed that ball-milling treatment enhanced the oxidation rate of Ag–Zn alloy powders due to the increase of dislocation density and the decrease of the diffusion distance of oxygen during internal oxidation. The fully oxidized time of Ag–Zn alloy powders decreases with the ball-milling time. In addition, the ball-milling treatment not only changes the oxidation mechanism but also improves microstructure and properties of the Ag–ZnO materials fabricated by internal oxidation. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905334/abstract

Electrochemical behavior of some copper alloys in sulfuric acid solutions / H. E. El-Feky in Materials and corrosion, Vol. 61 N° 7 (Juillet 2010) 

Public ISBD [article]  in Materials and corrosion > Vol. 61 N° 7 (Juillet 2010) . - pp. 599–610 Titre : Electrochemical behavior of some copper alloys in sulfuric acid solutions Type de document : texte imprimé Auteurs : H. E. El-Feky, Auteur ; N. H. Helal, Auteur ; M. R. Negem, Auteur Année de publication : 2010 Article en page(s) : pp. 599–610 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : copper  alloys;  corrosion;  impedance;  potentiodynamic  polarization Résumé : In this article, the corrosion behavior of CuFe and CuAlFe was studied in H2SO4 solutions in the absence and presence of different concentrations of some inorganic additives, Na2MoO4, K2Cr2O7, KIO3, and Na2B4O7. The techniques of measurements used were open-circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy. The polarization measurements indicated that the corrosion current, Icorr, of CuFe is less than that of CuAlFe. The investigated additives in H2SO4 shifted Ecorr to more positive values and increases Icorr. Impedance measurements indicated that Nyquist plots for CuFe may be regarded as a semi-circle in early stages of immersion and tends to be a part of semi-circle with elapse of time and a well-defined inductive loop appears. In case of CuAlFe, the Nyquist plots tends to be semi-circle or depressed semi-circle. The values of Rp for CuFe are higher than those for CuAlFe. On the other hand, the values of Cdl for CuFe are lower than those obtained for CuAlFe. The presence of these additives in H2SO4 solutions decreases the values of polarization resistance (Rp) and increases the values of corrosion current density (Icorr) and capacitance of double layer (Cdl). En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905345/abstract [article] Electrochemical behavior of some copper alloys in sulfuric acid solutions [texte imprimé] / H. E. El-Feky, Auteur ; N. H. Helal, Auteur ; M. R. Negem, Auteur . - 2010 . - pp. 599–610. Génie mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 61 N° 7 (Juillet 2010) . - pp. 599–610 Mots-clés : copper  alloys;  corrosion;  impedance;  potentiodynamic  polarization Résumé : In this article, the corrosion behavior of CuFe and CuAlFe was studied in H2SO4 solutions in the absence and presence of different concentrations of some inorganic additives, Na2MoO4, K2Cr2O7, KIO3, and Na2B4O7. The techniques of measurements used were open-circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy. The polarization measurements indicated that the corrosion current, Icorr, of CuFe is less than that of CuAlFe. The investigated additives in H2SO4 shifted Ecorr to more positive values and increases Icorr. Impedance measurements indicated that Nyquist plots for CuFe may be regarded as a semi-circle in early stages of immersion and tends to be a part of semi-circle with elapse of time and a well-defined inductive loop appears. In case of CuAlFe, the Nyquist plots tends to be semi-circle or depressed semi-circle. The values of Rp for CuFe are higher than those for CuAlFe. On the other hand, the values of Cdl for CuFe are lower than those obtained for CuAlFe. The presence of these additives in H2SO4 solutions decreases the values of polarization resistance (Rp) and increases the values of corrosion current density (Icorr) and capacitance of double layer (Cdl). En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905345/abstract

Electrochemical corrosion behavior of plasma sprayed Al2O3-13%TiO2 coatings in aqueous hydrochloric acid solution / Y. Wang in Materials and corrosion, Vol. 61 N° 7 (Juillet 2010) 

Public ISBD [article]  in Materials and corrosion > Vol. 61 N° 7 (Juillet 2010) . - pp. 611–617 Titre : Electrochemical corrosion behavior of plasma sprayed Al2O3-13%TiO2 coatings in aqueous hydrochloric acid solution Type de document : texte imprimé Auteurs : Y. Wang, Auteur ; W. Tian, Auteur ; T. Zhang, Auteur Année de publication : 2010 Article en page(s) : pp. 611–617 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Al2O3-13%TiO2  coatings;  electrochemical  corrosion;  plasma  spray Résumé : One kind of conventional and two kinds of nanostructured Al2O3-13%TiO2 coatings were prepared by plasma spray process. The phase composition and microstructure of coatings were examined by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). The potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used to investigate the corrosion behavior of coatings in aqueous hydrochloric acid solution. The results showed that nanostructured coatings had superior corrosion resistance compared to conventional Metco 130 coating. The corrosion resistance of coatings was mainly related to their microstructure and defects density. The EIS measurement for long time immersion in hydrochloric acid solution revealed that the corrosion resistance of coatings decreased with the increasing of immersion time. During the immersion period, electrochemical corrosion mainly occurred on the carbon steel substrate under NiCrAl coatings. In addition, the Al2O3-13%TiO2 coatings were also failed during corrosion in aqueous hydrochloric acid solution. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905335/abstract [article] Electrochemical corrosion behavior of plasma sprayed Al2O3-13%TiO2 coatings in aqueous hydrochloric acid solution [texte imprimé] / Y. Wang, Auteur ; W. Tian, Auteur ; T. Zhang, Auteur . - 2010 . - pp. 611–617. Génie mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 61 N° 7 (Juillet 2010) . - pp. 611–617 Mots-clés : Al2O3-13%TiO2  coatings;  electrochemical  corrosion;  plasma  spray Résumé : One kind of conventional and two kinds of nanostructured Al2O3-13%TiO2 coatings were prepared by plasma spray process. The phase composition and microstructure of coatings were examined by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). The potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used to investigate the corrosion behavior of coatings in aqueous hydrochloric acid solution. The results showed that nanostructured coatings had superior corrosion resistance compared to conventional Metco 130 coating. The corrosion resistance of coatings was mainly related to their microstructure and defects density. The EIS measurement for long time immersion in hydrochloric acid solution revealed that the corrosion resistance of coatings decreased with the increasing of immersion time. During the immersion period, electrochemical corrosion mainly occurred on the carbon steel substrate under NiCrAl coatings. In addition, the Al2O3-13%TiO2 coatings were also failed during corrosion in aqueous hydrochloric acid solution. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905335/abstract

Electrochemical corrosion behaviors and protective properties of Ni–Co–TiO2 composite coating prepared on sintered NdFeB magnet / X. K. Yang in Materials and corrosion, Vol. 61 N° 7 (Juillet 2010) 

Public ISBD [article]  in Materials and corrosion > Vol. 61 N° 7 (Juillet 2010) . - pp. 618–625 Titre : Electrochemical corrosion behaviors and protective properties of Ni–Co–TiO2 composite coating prepared on sintered NdFeB magnet Type de document : texte imprimé Auteurs : X. K. Yang, Auteur ; Q. Li, Auteur ; S. Y. Zhang, Auteur Année de publication : 2010 Article en page(s) : pp. 618–625 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Electrochemical  impedance  spectroscopy;  NdFeB  magnet;  Ni–Co–TiO2  composite  coating;  potentiodynamic  polarization Résumé : In this paper, a protective Ni–Co–TiO2 composite coating was prepared on the sintered NdFeB magnet by direct current electrodeposition. The surface morphologies, microstructure, and chemical composition of the composite coating were studied using scanning electron microscope (SEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS), respectively. The surface morphologies and microstructure analysis showed that the composite coating possessed cauliflower-like grain colonies, and formed face-centered cubic (fcc) solid solution. The electrochemical corrosion behaviors of the composite coating in 0.5 mol/L H2SO4, 0.6 mol/L NaOH, 0.6 mol/L Na2SO4, and neutral 3.5 wt% NaCl solutions were evaluated by potentiodynamic polarization measurements and electrochemical impedance spectroscopy (EIS), showing good protection for NdFeB magnet. In order to further investigate the protective properties of the composite coating for NdFeB magnet and the practicability of the composite coating, the long-term immersion test was carried out in neutral 3.5 wt% NaCl solutions using EIS. The results of long-term corrosion test showed that the Ni–Co–TiO2 composite coating could provide long-term protection in neutral 3.5 wt% NaCl solutions for NdFeB magnet. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905449/abstract [article] Electrochemical corrosion behaviors and protective properties of Ni–Co–TiO2 composite coating prepared on sintered NdFeB magnet [texte imprimé] / X. K. Yang, Auteur ; Q. Li, Auteur ; S. Y. Zhang, Auteur . - 2010 . - pp. 618–625. Génie mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 61 N° 7 (Juillet 2010) . - pp. 618–625 Mots-clés : Electrochemical  impedance  spectroscopy;  NdFeB  magnet;  Ni–Co–TiO2  composite  coating;  potentiodynamic  polarization Résumé : In this paper, a protective Ni–Co–TiO2 composite coating was prepared on the sintered NdFeB magnet by direct current electrodeposition. The surface morphologies, microstructure, and chemical composition of the composite coating were studied using scanning electron microscope (SEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS), respectively. The surface morphologies and microstructure analysis showed that the composite coating possessed cauliflower-like grain colonies, and formed face-centered cubic (fcc) solid solution. The electrochemical corrosion behaviors of the composite coating in 0.5 mol/L H2SO4, 0.6 mol/L NaOH, 0.6 mol/L Na2SO4, and neutral 3.5 wt% NaCl solutions were evaluated by potentiodynamic polarization measurements and electrochemical impedance spectroscopy (EIS), showing good protection for NdFeB magnet. In order to further investigate the protective properties of the composite coating for NdFeB magnet and the practicability of the composite coating, the long-term immersion test was carried out in neutral 3.5 wt% NaCl solutions using EIS. The results of long-term corrosion test showed that the Ni–Co–TiO2 composite coating could provide long-term protection in neutral 3.5 wt% NaCl solutions for NdFeB magnet. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905449/abstract

Electrochemical study of stainless steels used in an oil company by electrochemical impedance / Y. Boudinar in Materials and corrosion, Vol. 61 N° 7 (Juillet 2010) 

Public ISBD [article]  in Materials and corrosion > Vol. 61 N° 7 (Juillet 2010) . - pp. 626–634 Titre : Electrochemical study of stainless steels used in an oil company by electrochemical impedance Type de document : texte imprimé Auteurs : Y. Boudinar, Auteur ; F. Innal, Auteur ; H. Chadli, Auteur Année de publication : 2010 Article en page(s) : pp. 626–634 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Corrosion;  electrochemical  impedance;  potentiodynamic  polarization;  stainless  steel Résumé : Localized corrosion is a serious problem for stainless steel exposed in a chloride solution. In this context, the present work concerns the study of electrochemical behavior of 316 (A and B) and 430 (C and D) stainless steels, where A and C are laboratory steels, while steels B and D were taken from heat exchangers tubes (after 10 years of operation). This study has addressed three different aqueous environments: (1) monoethanolamine (MEA) 15%, (2) natural seawater (NSW), and (3) NaCl 3%, using the technique of potentiodynamic polarization curve complemented by electrochemical impedance spectroscopy (EIS). The obtained experimental electrochemical parameters (Ecorr, Jcorr, Er, Cd, Rtc, and constant phase element) were used to compare the corrosion resistance of the tested steels. As a result, the nobility of these steels in NaCl 3% and in MEA 15% solutions is established in the following order: 316 (A) > 316 (B) > 430 (C) > 430 (D), where Er moves increasingly toward the positive direction, indicating a good protection against corrosion. In addition, the results show that the effect of the electrolyte (aggression) is characterized by increased corrosion potential and a decrease in the passivity domain for all samples. The hierarchy of the nobility of steels A and C in these electrolytes can be determined as follows: MEA 15% > NSW > NaCl 3%. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905411/abstract [article] Electrochemical study of stainless steels used in an oil company by electrochemical impedance [texte imprimé] / Y. Boudinar, Auteur ; F. Innal, Auteur ; H. Chadli, Auteur . - 2010 . - pp. 626–634. Génie mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 61 N° 7 (Juillet 2010) . - pp. 626–634 Mots-clés : Corrosion;  electrochemical  impedance;  potentiodynamic  polarization;  stainless  steel Résumé : Localized corrosion is a serious problem for stainless steel exposed in a chloride solution. In this context, the present work concerns the study of electrochemical behavior of 316 (A and B) and 430 (C and D) stainless steels, where A and C are laboratory steels, while steels B and D were taken from heat exchangers tubes (after 10 years of operation). This study has addressed three different aqueous environments: (1) monoethanolamine (MEA) 15%, (2) natural seawater (NSW), and (3) NaCl 3%, using the technique of potentiodynamic polarization curve complemented by electrochemical impedance spectroscopy (EIS). The obtained experimental electrochemical parameters (Ecorr, Jcorr, Er, Cd, Rtc, and constant phase element) were used to compare the corrosion resistance of the tested steels. As a result, the nobility of these steels in NaCl 3% and in MEA 15% solutions is established in the following order: 316 (A) > 316 (B) > 430 (C) > 430 (D), where Er moves increasingly toward the positive direction, indicating a good protection against corrosion. In addition, the results show that the effect of the electrolyte (aggression) is characterized by increased corrosion potential and a decrease in the passivity domain for all samples. The hierarchy of the nobility of steels A and C in these electrolytes can be determined as follows: MEA 15% > NSW > NaCl 3%. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905411/abstract

Exemplaires

Bibliothèque Ecole Nationale Polytechnique d'Alger

Accueil

Se connecter

Météo

Adresse