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M. G. S. Ferreira - One of the best experts on this subject based on the ideXlab platform.

  • corrosion mechanism suggested based on electrochemical analysis and svet for uncoated tinplate and post coated with a hybrid film
    Materials Research-ibero-american Journal of Materials, 2017
    Co-Authors: Sandra Raquel Kunst, M. G. S. Ferreira, Lilian Vanessa Rossa Beltrami, Rosiana Boniatti, Marcela C Quevedo, A C Bastos, Claudia Trindade Oliveira, Tiago Lemos Menezes, Celia De Fraga Malfatti
    Abstract:

    , a tin layer and an oxide tin layer. Currently, packaging using surface treatment is based on the use of chromates because these metals provide an excellent corrosion resistance. Nontoxic alternatives to pre-treatments have been developed in recent years to replace the chromate process. The aim of this work is to analyze the performance of a new hybrid organic-inorganic film obtained from sol-gel consisting of the alkoxide precursors 3-(Trimethoxysilylpropyl)methacrylate (TMSM) and tetraethoxysilane (TEOS) with the addition of Cerium Nitrate with the scanning vibrating electrode technique (SVET), and electrochemical and morphological characterizations. Moreover, the evolution of the corrosion of the substrate was evaluated to propose a mechanism of corrosion. The results showed a galvanic coupling between the Sn/SnO

  • composition and corrosion resistance of Cerium conversion films on the az31 magnesium alloy and its relation to the salt anion
    Applied Surface Science, 2008
    Co-Authors: M F Montemor, M. G. S. Ferreira, A M Simoes, M J Carmezim
    Abstract:

    Abstract Pre-treatments based on different Cerium salts were applied to the AZ31 Mg alloy. The pre-treatments were performed by immersion in solutions of various Ce(III) salts: Cerium chloride, Cerium Nitrate, Cerium sulphate and Cerium phosphate. The chemical composition of the treated surfaces was investigated by X-ray photoelectron spectroscopy and Auger electron spectroscopy, whereas the corrosion behaviour of the pre-treated AZ31 substrates was investigated in 0.005 M NaCl solutions using potentiodynamic polarisation and open circuit potential monitoring. The surface film contained a mixture of Ce(IV) and Ce(III) salts. The film thickness depends upon the Cerium salt used. The electrochemical results show that all the conversion pre-treatments reduced the corrosion activity of the AZ31 Mg alloy substrates in the presence of chloride ions. The corrosion protection efficiency is related with the anion present in the Cerium salt.

  • Influence of inhibitor addition on the corrosion protection performance of sol-gel coatings on AA2024
    Progress in Organic Coatings, 2008
    Co-Authors: Kiryl Yasakau, O. V. Karavai, Mikhail L. Zheludkevich, M. G. S. Ferreira
    Abstract:

    Sol-gel films are actively investigated during the last decade as possible candidates for environmentally friendly pre-treatments. However, the important drawback in this case is the lack of active corrosion protection and self-healing ability. In this work a certain number of corrosion inhibitors for AA2024 was used as additives to the hybrid sol-gel formulations in order to confer active corrosion protection without damaging the coating. The 8-hydroxyquinoline, benzotriazole and Cerium Nitrate were added at different stages of the synthesis process to understand the role of possible interaction of the inhibitor with components of the sol-gel system. The Scanning Vibrating Electrode Technique and Electrochemical Impedance Spectroscopy were employed as two main techniques to characterize the corrosion protection performance of the hybrid sol-gel films doped with inhibitors and to understand the mechanisms of corrosion protection. The results demonstrate that 8-hydroxyquinoline and Cerium Nitrate do not affect the stability of sol-gel films and confer additional active corrosion protection effect. In contrast to this, benzotriazole leads to deterioration of the corrosion protection properties of hybrid sol-gel films. © 2008.

  • electrochemical study of modified bis triethoxysilylpropyl tetrasulfide silane films applied on the az31 mg alloy
    Electrochimica Acta, 2007
    Co-Authors: M F Montemor, M. G. S. Ferreira
    Abstract:

    Abstract This work investigates the protective behaviour of bis-[triethoxysilylpropyl] tetrasulfide silane pre-treatments on the AZ31 Mg alloy. The silane solution was modified by the addition of Cerium Nitrate or lanthanum Nitrate in order to introduce corrosion inhibition properties in the silane film. The corrosion behaviour of the pre-treated AZ31 magnesium alloy was studied during immersion in 0.005 M NaCl solution, using electrochemical impedance spectroscopy and the scanning vibrating electrode technique (SVET). The electrochemical experiments showed that the presence of Cerium ions or lanthanum ions improve the protective behaviour of the silane film. The SVET experiments evidenced that the presence Cerium in the silane film led to an important reduction of the corrosion activity. The results demonstrate that either Cerium ions or lanthanum ions can be used as additives to the silane solutions to improve the performance of the pre-treatments for the AZ31 magnesium alloy.

  • the use of pre treatments based on doped silane solutions for improved corrosion resistance of galvanised steel substrates
    Surface & Coatings Technology, 2006
    Co-Authors: W Trabelsi, Mikhail L. Zheludkevich, M. G. S. Ferreira, E Triki, L Dhouibi, M F Montemor
    Abstract:

    Abstract The present work aims at evaluating the corrosion resistance of galvanised steel substrates pre-treated with bis-[triethoxysilylpropyl] tetrasulfide silane doped with Cerium Nitrate or zirconium Nitrate. The corrosion resistance of the pre-treated substrates was evaluated by electrochemical impedance spectroscopy, during immersion in NaCl solutions. The chemical composition of the surface was assessed by X-ray photoelectron spectroscopy and the surface morphology was studied by atomic force microscopy. The electrochemical results show that pre-treatments based on doped silane solutions provide good corrosion protection of the galvanised steel substrates. The work also aims at discussing the role of the dopants on the protective properties of the silane coatings formed on galvanised steel substrates.

M F Montemor - One of the best experts on this subject based on the ideXlab platform.

  • composition and corrosion resistance of Cerium conversion films on the az31 magnesium alloy and its relation to the salt anion
    Applied Surface Science, 2008
    Co-Authors: M F Montemor, M. G. S. Ferreira, A M Simoes, M J Carmezim
    Abstract:

    Abstract Pre-treatments based on different Cerium salts were applied to the AZ31 Mg alloy. The pre-treatments were performed by immersion in solutions of various Ce(III) salts: Cerium chloride, Cerium Nitrate, Cerium sulphate and Cerium phosphate. The chemical composition of the treated surfaces was investigated by X-ray photoelectron spectroscopy and Auger electron spectroscopy, whereas the corrosion behaviour of the pre-treated AZ31 substrates was investigated in 0.005 M NaCl solutions using potentiodynamic polarisation and open circuit potential monitoring. The surface film contained a mixture of Ce(IV) and Ce(III) salts. The film thickness depends upon the Cerium salt used. The electrochemical results show that all the conversion pre-treatments reduced the corrosion activity of the AZ31 Mg alloy substrates in the presence of chloride ions. The corrosion protection efficiency is related with the anion present in the Cerium salt.

  • electrochemical study of modified bis triethoxysilylpropyl tetrasulfide silane films applied on the az31 mg alloy
    Electrochimica Acta, 2007
    Co-Authors: M F Montemor, M. G. S. Ferreira
    Abstract:

    Abstract This work investigates the protective behaviour of bis-[triethoxysilylpropyl] tetrasulfide silane pre-treatments on the AZ31 Mg alloy. The silane solution was modified by the addition of Cerium Nitrate or lanthanum Nitrate in order to introduce corrosion inhibition properties in the silane film. The corrosion behaviour of the pre-treated AZ31 magnesium alloy was studied during immersion in 0.005 M NaCl solution, using electrochemical impedance spectroscopy and the scanning vibrating electrode technique (SVET). The electrochemical experiments showed that the presence of Cerium ions or lanthanum ions improve the protective behaviour of the silane film. The SVET experiments evidenced that the presence Cerium in the silane film led to an important reduction of the corrosion activity. The results demonstrate that either Cerium ions or lanthanum ions can be used as additives to the silane solutions to improve the performance of the pre-treatments for the AZ31 magnesium alloy.

  • characterization of rare earth conversion films formed on the az31 magnesium alloy and its relation with corrosion protection
    Applied Surface Science, 2007
    Co-Authors: M F Montemor, A M Simoes, M J Carmezim
    Abstract:

    Abstract Two pre-treatments were studied for AZ31 Mg alloy substrates, consisting of immersion in Cerium Nitrate and lanthanum Nitrate solutions for various immersion times. The surface composition was investigated by X-ray photoelectron spectroscopy and Auger electron spectroscopy that revealed the presence of a surface film containing the rare-earth cation, with a composition which was time dependent in the case of the Cerium pre-treatment. The corrosion behaviour of the pre-treated substrates in 0.005 M NaCl solutions was assessed by potentiodynamic polarization, open circuit potential monitoring and the scanning vibrating electrode technique (SVET). The electrochemical results show that the pre-treatments reduced the corrosion activity of the AZ31 Mg alloy substrates in the presence of chloride ions. The corrosion protection efficiency is dependent on the treatment time.

  • the use of pre treatments based on doped silane solutions for improved corrosion resistance of galvanised steel substrates
    Surface & Coatings Technology, 2006
    Co-Authors: W Trabelsi, Mikhail L. Zheludkevich, M. G. S. Ferreira, E Triki, L Dhouibi, M F Montemor
    Abstract:

    Abstract The present work aims at evaluating the corrosion resistance of galvanised steel substrates pre-treated with bis-[triethoxysilylpropyl] tetrasulfide silane doped with Cerium Nitrate or zirconium Nitrate. The corrosion resistance of the pre-treated substrates was evaluated by electrochemical impedance spectroscopy, during immersion in NaCl solutions. The chemical composition of the surface was assessed by X-ray photoelectron spectroscopy and the surface morphology was studied by atomic force microscopy. The electrochemical results show that pre-treatments based on doped silane solutions provide good corrosion protection of the galvanised steel substrates. The work also aims at discussing the role of the dopants on the protective properties of the silane coatings formed on galvanised steel substrates.

  • electrochemical assessment of the self healing properties of ce doped silane solutions for the pre treatment of galvanised steel substrates
    Progress in Organic Coatings, 2005
    Co-Authors: W Trabelsi, M. G. S. Ferreira, P Cecilio, M F Montemor
    Abstract:

    Abstract The present work aims at assessing the electrochemical behaviour of galvanised steel (GS) substrates pre-treated with bis-[triethoxysilylpropyl] tetrasulfide silane (BTESPT) doped with Cerium Nitrate. Furthermore, the work aims at evaluating the self-healing properties of the dopant and discussing the possible mechanisms involved in this process. The study was performed by electrochemical impedance spectroscopy (EIS) and by the scanning vibrating electrode technique (SVET), during immersion in NaCl solutions. X-ray photoelectron spectroscopy (XPS) was also used to complement the electrochemical results. The results show that the protective behaviour of the pre-treatments based on Ce-doped silane solutions is dependent on the concentration of the dopant. The results also show that the dopant improves the anti-corrosion performance of the silane coatings formed on galvanised steel substrates.

R V Lakshmi - One of the best experts on this subject based on the ideXlab platform.

  • ceria nanoparticles vis a vis Cerium Nitrate as corrosion inhibitors for silica alumina hybrid sol gel coating
    Applied Surface Science, 2017
    Co-Authors: R V Lakshmi, S T Aruna, S Sampath
    Abstract:

    The present work provides a comparative study on the corrosion protection efficiency of defect free sol-gel hybrid coating containing ceria nanoparticles and Cerium Nitrate ions as corrosion inhibitors. Less explored organically modified alumina-silica hybrid sol-gel coatings are synthesized from 3-glycidoxypropyltrimethoxysilane and aluminium-tri-sec-butoxide. The microemulsion derived nanoparticles and the hybrid coatings are characterized and compared with coatings containing Cerium Nitrate. Corrosion inhibiting capability is assessed using electrochemical impedance spectroscopy. Scanning Kelvin probe measurements are also conducted on the coatings for identifying the apparent corrosion prone regions. Detailed X-ray photoelectron spectroscopy (XPS) analysis is carried out to comprehend the bonding and corrosion protection rendered by the hybrid coatings. (C) 2016 Elsevier B.V. All rights reserved.

  • effect of surface pre treatment by silanization on corrosion protection of aa2024 t3 alloy by sol gel nanocomposite coatings
    Surface & Coatings Technology, 2014
    Co-Authors: R V Lakshmi, G Yoganandan, Avn Mohan, Bharathibai J Basu
    Abstract:

    Abstract Corrosion protection behavior of sol–gel coating doped with Cerium Nitrate was investigated on AA2024. The sol–gel layer composed of methyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane and colloidal silica. The performance of the sol–gel coating with and without surface silanization was evaluated using electrochemical techniques and neutral salt spray test. The morphology and composition of the coatings were examined by FESEM and EDX techniques before and after corrosion. Electrochemical studies indicated that Cerium doped sol–gel coating with the additional APTEOS layer provided better corrosion resistance even after 168 h of exposure among all the developed coatings. Surface silanization provided additional protection to the metal surface.

  • effective corrosion inhibition performance of ce3 doped sol gel nanocomposite coating on aluminum alloy
    Progress in Organic Coatings, 2013
    Co-Authors: R V Lakshmi, G Yoganandan, K T Kavya, Bharathibai J Basu
    Abstract:

    Abstract Sol–gel nanocomposite coatings have been investigated for Alclad AA2024 as a potential replacement for the hazardous and banned hexavalent chromate conversion coatings. The sol–gel coatings were prepared using a sol obtained by the hydrolysis and condensation of methyltriethoxysilane and colloidal silica. They were doped with Cerium Nitrate inhibitor to provide active corrosion protection and were deposited by spray-coating method. The sol–gel process conditions were optimized to obtain smooth and homogenous crack free films. The chemical composition and microstructure of the coatings were studied using EDX and FESEM respectively. The effect of Cerium Nitrate concentration on the corrosion protection efficiency of the sol–gel coatings was evaluated using potentiodynamic polarization, electrochemical impedance spectroscopy and salt spray tests. The results indicated that Cerium Nitrate doped coatings were more resistant to corrosion than undoped coating. The coatings doped with 6000 ppm Cerium Nitrate rendered improved protection after longer immersions due to the inhibitive action of Ce 3+ .

Bharathibai J Basu - One of the best experts on this subject based on the ideXlab platform.

  • effect of surface pre treatment by silanization on corrosion protection of aa2024 t3 alloy by sol gel nanocomposite coatings
    Surface & Coatings Technology, 2014
    Co-Authors: R V Lakshmi, G Yoganandan, Avn Mohan, Bharathibai J Basu
    Abstract:

    Abstract Corrosion protection behavior of sol–gel coating doped with Cerium Nitrate was investigated on AA2024. The sol–gel layer composed of methyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane and colloidal silica. The performance of the sol–gel coating with and without surface silanization was evaluated using electrochemical techniques and neutral salt spray test. The morphology and composition of the coatings were examined by FESEM and EDX techniques before and after corrosion. Electrochemical studies indicated that Cerium doped sol–gel coating with the additional APTEOS layer provided better corrosion resistance even after 168 h of exposure among all the developed coatings. Surface silanization provided additional protection to the metal surface.

  • effective corrosion inhibition performance of ce3 doped sol gel nanocomposite coating on aluminum alloy
    Progress in Organic Coatings, 2013
    Co-Authors: R V Lakshmi, G Yoganandan, K T Kavya, Bharathibai J Basu
    Abstract:

    Abstract Sol–gel nanocomposite coatings have been investigated for Alclad AA2024 as a potential replacement for the hazardous and banned hexavalent chromate conversion coatings. The sol–gel coatings were prepared using a sol obtained by the hydrolysis and condensation of methyltriethoxysilane and colloidal silica. They were doped with Cerium Nitrate inhibitor to provide active corrosion protection and were deposited by spray-coating method. The sol–gel process conditions were optimized to obtain smooth and homogenous crack free films. The chemical composition and microstructure of the coatings were studied using EDX and FESEM respectively. The effect of Cerium Nitrate concentration on the corrosion protection efficiency of the sol–gel coatings was evaluated using potentiodynamic polarization, electrochemical impedance spectroscopy and salt spray tests. The results indicated that Cerium Nitrate doped coatings were more resistant to corrosion than undoped coating. The coatings doped with 6000 ppm Cerium Nitrate rendered improved protection after longer immersions due to the inhibitive action of Ce 3+ .

Mikhail L. Zheludkevich - One of the best experts on this subject based on the ideXlab platform.

  • Influence of inhibitor addition on the corrosion protection performance of sol-gel coatings on AA2024
    Progress in Organic Coatings, 2008
    Co-Authors: Kiryl Yasakau, O. V. Karavai, Mikhail L. Zheludkevich, M. G. S. Ferreira
    Abstract:

    Sol-gel films are actively investigated during the last decade as possible candidates for environmentally friendly pre-treatments. However, the important drawback in this case is the lack of active corrosion protection and self-healing ability. In this work a certain number of corrosion inhibitors for AA2024 was used as additives to the hybrid sol-gel formulations in order to confer active corrosion protection without damaging the coating. The 8-hydroxyquinoline, benzotriazole and Cerium Nitrate were added at different stages of the synthesis process to understand the role of possible interaction of the inhibitor with components of the sol-gel system. The Scanning Vibrating Electrode Technique and Electrochemical Impedance Spectroscopy were employed as two main techniques to characterize the corrosion protection performance of the hybrid sol-gel films doped with inhibitors and to understand the mechanisms of corrosion protection. The results demonstrate that 8-hydroxyquinoline and Cerium Nitrate do not affect the stability of sol-gel films and confer additional active corrosion protection effect. In contrast to this, benzotriazole leads to deterioration of the corrosion protection properties of hybrid sol-gel films. © 2008.

  • the use of pre treatments based on doped silane solutions for improved corrosion resistance of galvanised steel substrates
    Surface & Coatings Technology, 2006
    Co-Authors: W Trabelsi, Mikhail L. Zheludkevich, M. G. S. Ferreira, E Triki, L Dhouibi, M F Montemor
    Abstract:

    Abstract The present work aims at evaluating the corrosion resistance of galvanised steel substrates pre-treated with bis-[triethoxysilylpropyl] tetrasulfide silane doped with Cerium Nitrate or zirconium Nitrate. The corrosion resistance of the pre-treated substrates was evaluated by electrochemical impedance spectroscopy, during immersion in NaCl solutions. The chemical composition of the surface was assessed by X-ray photoelectron spectroscopy and the surface morphology was studied by atomic force microscopy. The electrochemical results show that pre-treatments based on doped silane solutions provide good corrosion protection of the galvanised steel substrates. The work also aims at discussing the role of the dopants on the protective properties of the silane coatings formed on galvanised steel substrates.

  • nanostructured sol gel coatings doped with Cerium Nitrate as pre treatments for aa2024 t3 corrosion protection performance
    Electrochimica Acta, 2005
    Co-Authors: Mikhail L. Zheludkevich, Kiryl Yasakau, M. G. S. Ferreira, R Serra, M F Montemor, I Miranda M Salvado
    Abstract:

    Nanostructured hybrid sol–gel coatings doped with Cerium ions were investigated in the present work as pre-treatments for the AA2024-T3 alloy. The sol–gel films have been synthesized from tetraethylorthosilicate (TEOS) and 3-glycidoxypropyltrimethoxysilane (GPTMS) precursors. Additionally the hybrid sol was doped with zirconia nanoparticles prepared from hydrolyzed tetra-n-propoxyzirconium (TPOZ). Cerium Nitrate, as corrosion inhibitor, was added into the hybrid matrix or into the oxide nanoparticles. The chemical composition and the structure of the hybrid sol–gel films were studied by XPS (X-ray photoelectron spectroscopy) and AFM (atomic force microscopy), respectively. The evolution of the corrosion protection properties of the sol–gel films was studied by EIS (electrochemical impedance spectroscopy), which can provide quantitative information on the role of the different pre-treatments. Different equivalent circuits, for different stages of the corrosion processes, were used in order to model the coating degradation. The models were supported by SEM (scanning electron microscopy) measurements. The results show that the sol–gel films containing zirconia nanoparticles present improved barrier properties. Doping the hybrid nanostructured sol–gel coatings with Cerium Nitrate leads to additional improvement of the corrosion protection. The zirconia particles present in the sol–gel matrix seem to act as nanoreservoirs providing a prolonged release of Cerium ions. The nanostructured sol–gel films doped with Cerium Nitrate can be proposed as a potential candidate for substitution of the chromate pre-treatments for AA2024-T3.