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Effect of cerium (IV) ions on the anticorrosion properties of siloxane-poly(methyl methacrylate) based film applied on tin coated steel

SUEGAMA, P. H.; SARMENTO, V. H. V.; MONTEMOR, M. F.; BENEDETTI, A. V.; MELO, H. G. de; AOKI, I. V.; SANTILLI, C. V.
Fonte: PERGAMON-ELSEVIER SCIENCE LTD Publicador: PERGAMON-ELSEVIER SCIENCE LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.67%
This work investigates the influence of the addition of cerium (IV) ions on the anticorrosion properties of organic-inorganic hybrid coatings applied to passivated tin coated steel. In order to evaluate the specific effect of cerium (IV) addition on nanostructural features of the organic and inorganic phases of the hybrid coating, the hydrolytic polycondensation of silicon alkoxide and the radical polymerization of the methyl methacrylate (MMA) function were induced separately. The corrosion resistance of the coatings was evaluated by means of linear polarization, Tafel type curves and electrochemical impedance measurements. The impedance results obtained for the hybrid coatings were discussed based on an electrical equivalent circuit used to fit the experimental data. The electrochemical results clearly showed the improvement of the protective properties of the organic-inorganic hybrid coating mainly when the cerium (IV) was added to the organic phase solution precursor, which seemed to be due to the formation of a more uniform and densely reticulated siloxane-PMMA film. (C) 2010 Elsevier Ltd. All rights reserved.; FAPESP[05/51851-4]; FAPESP[07/53073-4]; CNPq[310860/2005-9]; CNPq[300728/2007-7]; CNPq[305073/2008-7]; CAPES[BEX-3167-08-9]

Effect of cerium (IV) ions on the anticorrosion properties of siloxane-poly(methyl methacrylate) based film applied on tin coated steel

Suegama, P. H.; Sarmento, V. H. V.; Montemor, M. F.; Benedetti, A. V.; de Melo, H. G.; Aoki, I. V.; Santilli, C. V.
Fonte: Pergamon-Elsevier B.V. Ltd Publicador: Pergamon-Elsevier B.V. Ltd
Tipo: Artigo de Revista Científica Formato: 5100-5109
ENG
Relevância na Pesquisa
36.64%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Processo FAPESP: 05/51851-4; Processo FAPESP: 07/53073-4; This work investigates the influence of the addition of cerium (IV) ions on the anticorrosion properties of organic-inorganic hybrid coatings applied to passivated tin coated steel. In order to evaluate the specific effect of cerium (IV) addition on nanostructural features of the organic and inorganic phases of the hybrid coating, the hydrolytic polycondensation of silicon alkoxide and the radical polymerization of the methyl methacrylate (MMA) function were induced separately. The corrosion resistance of the coatings was evaluated by means of linear polarization, Tafel type curves and electrochemical impedance measurements. The impedance results obtained for the hybrid coatings were discussed based on an electrical equivalent circuit used to fit the experimental data. The electrochemical results clearly showed the improvement of the protective properties of the organic-inorganic hybrid coating mainly when the cerium (IV) was added to the organic phase solution precursor...

Highly corrosion resistant siloxane-polymethyl methacrylate hybrid coatings

Hammer, Peter; dos Santos, Fabio C.; Cerrutti, Bianca M.; Pulcinelli, Sandra H.; Santilli, Celso V.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica Formato: 266-274
ENG
Relevância na Pesquisa
56.46%
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Siloxane-polymethyl methacrylate hybrid films were deposited on carbon steel substrates by dip-coating from a sol prepared by acid-catalyzed hydrolytic co-polycondensation of tetraethoxysilane (TEOS) and 3-methacryloxy propyl-trimethoxysilane (MPTS), followed by radical polymerization of methyl methacrylate (MMA). Structural properties of the hybrids were studied using Si-29 and C-13 nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA), as a function of the MMA/MPTS ratio, which ranged between 2 and 10. The efficiency of corrosion protection of hybrid-coated carbon steel was investigated by XPS, potentiodynamic polarization curves and electrochemical impedance spectroscopy after immersion of the material in acidic and neutral saline aqueous solution. The NMR and TGA results indicate a high degree of polycondensation (84%) and elevated thermal stability of 410 A degrees C for the hybrid film with a MMA/MPTS ratio of 8, exhibiting also and excellent adhesion to the substrate. The XPS analysis confirmed the variation of the MMA phase in the hybrid...

Improvement of the corrosion resistance of polysiloxane hybrid coatings by cerium doping

Hammer, P.; Schiavetto, M. G.; dos Santos, F. C.; Benedetti, A. V.; Pulcinelli, S. H.; Santilli, C. V.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 2606-2612
ENG
Relevância na Pesquisa
56.42%
Polysiloxane hybrid films were deposited on stainless steel by dip-coating using a sol prepared by hydrolytic co-polycondensation of tetraethoxysilane (TEOS) and 3-methacryloxy propyltrimethoxysilane (MPTS), followed by radical polymerization of methacrylic moieties. The TEOS/MPTS ratio was chosen equal to 2 and the Ce/Si ratio varied between 0.01 and 0.1. The effects of cerium concentration and valence (Ce(III) and Ce (IV)) on the structural features of polysiloxane films were studied by X-ray photoelectron spectroscopy (XPS) and (29)Si nuclear magnetic resonance (NMR). The corrosion protection of stainless steel by the hybrid coatings was investigated by XPS, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves, after immersion in saline and acid solutions. The NMR results have shown for Ce(IV) doped films a high degree of polycondensation of up to 89%. Electrochemical analysis has evidenced that hybrid films with the lowest Ce concentration act as an efficient diffusion barrier by increasing the corrosion resistance and reducing the current densities up to 3 orders of magnitude compared to bare stainless steel. The analysis of structural effects induced by Ce(III) and Ce(IV) species, performed by XPS...

Corrosion protection of stainless steel by polysiloxane hybrid coatings prepared using the sol-gel process

Sarmento, V. H. V.; Schiavetto, M. G.; Hammer, P.; Benedetti, A. V.; Fugivara, C. S.; Suegama, P. H.; Pulcinelli, S. H.; Santilli, C. V.
Fonte: Elsevier B.V. Sa Publicador: Elsevier B.V. Sa
Tipo: Artigo de Revista Científica Formato: 2689-2701
ENG
Relevância na Pesquisa
56.44%
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Polysiloxane hybrid films were deposited on 316 L stainless steel substrates by dip-coating in a sol prepared by acid-catalyzed hydrolytic co-polycondensation of tetraethoxysilane (TEOS) and 3-methacryloxy propyltrimethoxysilane (MPTS), followed by radical polymerization of methacrylic moieties. Structural features of the polysiloxane hybrids were studied using (13)C and (29)Si nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA), as a function of the TEOS/MPTS ratio, which ranged between 0 and 2. The efficiency of corrosion protection of hybrid-coated stainless steel was investigated by X-ray photoelectron spectroscopy (XPS), potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) after immersion of the material in acidic and neutral saline aqueous solutions. The NMR and TGA results indicated a high degree of polymerization and polycondensation (85%) for the hybrid film with a TEOS/MPTS ratio of 2, as well as elevated thermal stability of 410 C and excellent adhesion. The XPS analysis confirmed the hybridized structure of the polysiloxane network...

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

Hammer, P.; Dos Santos, F. C.; Cerrutti, B. M.; Pulcinelli, S. H.; Santilli, C. V.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 601-608
ENG
Relevância na Pesquisa
56.63%
Siloxane-polymethyl methacrylate hybrid films containing functionalized multiwall carbon nanotubes (CNTs) were deposited by dip-coating on carbon steel substrates from a sol prepared by radical polymerization of methyl methacrylate and 3-methacryloxy propyl-trimethoxysilane, followed by hydrolytic co-polycondensation of tetraethoxysilane. The correlation between the structural properties and corrosion protection efficiency was studied as a function of the molar ratio of nanotubes carbon to silicon, varied in the range between 0.1% and 5%. 29Si nuclear magnetic resonance and thermogravimetric measurements have shown that hybrids containing carbon nanotubes have a similar degree of polycondensation and thermal stability as the undoped matrix and exhibit and excellent adhesion to the substrate. Microscopy and X-ray photoelectron spectroscopy results revealed a very good dispersion of carbon nanotubes in the hybrid matrix and the presence of carboxylic groups allowing covalent bonding with the end-siloxane nodes. Potentiodynamic polarization curves and electrochemical impedance spectroscopy results demonstrate that CNTs containing coatings maintain the excellent corrosion protection efficiency of the hybrids, showing even a superior performance in acidic solution. The nanocomposite structure acts as efficient corrosion barrier...

Estudos da preparação de superfície da liga AA6063T5 e do desenvolvimento de revestimentos híbridos orgânico-inorgânicos a base de siloxano-PMMA para aplicação anticorrosiva

Teixeira, Dilton Gonçalves
Fonte: Universidade Estadual Paulista (UNESP) Publicador: Universidade Estadual Paulista (UNESP)
Tipo: Tese de Doutorado Formato: 122 f. : il., color., grafs., tabs.
POR
Relevância na Pesquisa
46.5%
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Pós-graduação em Química - IQ; Este trabalho está basicamente dividido em duas partes. A primeira está relacionada à limpeza da superfície da liga de alumínio AA6063T5 e sua influência na proteção contra a corrosão. A segunda parte se refere à preparação de revestimentos híbridos orgânicoinorgânico pelo processo sol-gel e deposição sobre a superfície da liga de alumínio por dipcoating. Três amostras de liga AA6063T5 foram investigadas: como recebida, debastada e polida mecanicamente e tratada quimicamente. O tratamento mecânico foi realizado utilizando lixas SiC de granulometria 320 a 4000 e o químico foi realizado utilizando uma solução aquosa contendo uma mistura de hidróxido, sulfato e cloreto de sódio. Todas as amostras foram caracterizadas fisicamente por difratometria de raios X (XRD), medidas de dureza, microscopia eletrônica de varredura (SEM) e microscopia óptica (MO), e por medidas de potencial de circuito aberto (OCP) e espectroscopia de impedância eletroquímica (EIS) em solução 3,5% NaCl. As imagens SEM mostraram que a presença de partícula intermetálicas na superfície da liga diminui após o tratamento químico comparado ao tratamento mecânico. Os resultados de EIS mostraram que o tratamento químico oferece maior resistência à corrosão do que as submetidas aos outros tratamentos...

Organic-inorganic hybrid coatings for corrosion protection of galvanized steel and electroplated ZnFe steel

Souza, M. E. P.; Ariza, E.; Ballester, M.; Yoshida, I. V. P.; Rocha, L. A.; Freire, C. M. A.
Fonte: Associação Brasileira de Metalurgia e Materiais [etc.] Publicador: Associação Brasileira de Metalurgia e Materiais [etc.]
Tipo: Artigo de Revista Científica
Publicado em /05/2005 ENG
Relevância na Pesquisa
46.6%
The development of hybrids materials by the sol-gel process has been extensively investigated in recent years. The combination a wide variety of compositions and production processes had permit the use of these materials in different applications like coatings for corrosion protection of metals and abrasion resistant coatings. In this work organic-inorganic hybrid materials have been prepared from the hydrolysis of tetraethylorthosilicate (TEOS) and silanol-terminated polidymetilmetoxysilane (PDMS) using a sol-gel process. The composition evaluated was 50% TEOS- 50% PDMS. These materials have been applied on galvanized steel and on steel electroplated with a ZnFe alloy. In order to evaluate the degradation behaviour of these coatings, electrochemical techniques were used. They consisting in the monitoring of the open-circuit potential (Ecorr), and in the realization of potentiodynamic polarization measurements of the samples, which was performed in a 3% NaCl aqueous solution. Additionally, electrochemical impedance spectroscopy (EIS) was used as a complementary technique for the evaluation of the corrosion mechanisms of the coating system. The surface of the samples, before and after the electrochemical tests, have been inspected by SEM and EDS. EIS data was fitted to an equivalent circuit from which the electrochemical parameters were obtained. Results show a good protective character of the hybrid films...

Organic-inorganic hybrid coatings for corrosion protection of galvanized steel and electroplated znfe steel

Souza, M. E. P.; Ariza, E.; Ballester, M.; Yoshida, I. V. P.; Rocha, L. A.; Freire, C. M. A.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em //2004 ENG
Relevância na Pesquisa
46.6%
The development of hybrids materials by the sol-gel process has been extensively investigated in recent years. The combination a wide variety of compositions and production processes had permit the use of these aterials in different applications like coatings for corrosion protection of metals and abrasion resistant coatings. In this work organic-inorganic hybrid materials have been prepared from the hydrolysis of tetraethylorthosilicate (TEOS) and silanol-terminated polidymetilmetoxysilane (PDMS) using a sol-gel process. The composition evaluated was 50% TEOS- 50% PDMS. These materials have been applied on galvanized steel and on steel electroplated with a ZnFe alloy. In order to evaluate the degradation behaviour of these coatings, electrochemical techniques were used. They consisting in the monitoring of the open-circuit potential (Ecorr), and in the realization of potentiodynamic polarization measurements of the samples, which was performed in a 3% NaCl aqueous solution. Additionally, electrochemical impedance spectroscopy (EIS) was used as a complementary technique for the evaluation of the corrosion mechanisms of the coating system. The surface of the samples, before and after the electrochemical tests, have been inspected by SEM and EDS. EIS data was fitted to an equivalent circuit from which the lectrochemical parameters were obtained. Results show a good protective character of the hybrid films...

Incorporation of proteins with different isoelectric points into biomimetic Ca-P coatings : a new approach to produce hybrid coatings with tailored properties

Azevedo, Helena S.; Leonor, I. B.; Reis, R. L.
Fonte: Trans Tech Publications Publicador: Trans Tech Publications
Tipo: Parte de Livro
Publicado em //2006 ENG
Relevância na Pesquisa
46.6%
This work aims to study the effect of incorporating proteins with different isoelectric points (pI) on the structure, composition and morphology of biomimetic calcium-phosphate (Ca-P) coatings. For that, bovine serum albumin (BSA) and lysozyme, having respectively acidic and basic pIs, were used as model proteins. It was observed that the incorporation of positively charged proteins, such as lysozyme, was able to significantly change the structure of the coatings, possibly due to the preferential interactions between the protein and negatively charged phosphate ions. These results indicated that proteins with different characteristics can be incorporated into biomimetic Ca-P coatings in order to obtain a hybrid coating and at the same tailoring their properties.

Influence of experimental parameters using the dip-coating method on the barrier performance of hybrid sol-gel coatings in strong alkaline environments

Figueira, R. B.; Silva, Carlos J. R.; Pereira, Elsa V.
Fonte: MDPI Publicador: MDPI
Tipo: Artigo de Revista Científica
Publicado em //2015 ENG
Relevância na Pesquisa
36.62%
Previous studies have shown that the barrier effect and the performance of organic-inorganic hybrid (OIH) sol-gel coatings are highly dependent on the coating deposition method as well as on the processing conditions. However, studies on how the coating deposition method influences the barrier properties in alkaline environments are scarce. The aim of this experimental research was to study the influence of experimental parameters using the dip-coating method on the barrier performance of an OIH sol-gel coating in contact with simulated concrete pore solutions (SCPS). The influence of residence time (Rt), a curing step between each dip step and the number of layers of sol-gel OIH films deposited on hot-dip galvanized steel to prevent corrosion in highly alkaline environments was studied. The barrier performance of these OIH sol-gel coatings, named U(400), was assessed in the first instants of contact with SCPS, using electrochemical impedance spectroscopy and potentiodynamic methods. The durability and stability of the OIH coatings in SCPS was monitored during eight days by macrocell current density. The morphological characterization of the surface was performed by Scanning Electronic Microscopy before and after exposure to SCPS. Glow Discharge Optical Emission Spectroscopy was used to investigate the thickness of the U(400) sol-gel coatings as a function of the number of layers deposited with and without Rt in the coatings thickness.

Characterization of organic-inorganic hybrid coatings for corrosion protection of galvanized steel and electroplated ZnFe steel

Souza,Maria Eliziane Pires de; Ariza,Edith; Ballester,Margarita; Yoshida,Inez Valéria Pagotto; Rocha,Luis Augusto; Freire,Célia Marina de Alvarenga
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2006 EN
Relevância na Pesquisa
46.52%
The development of hybrids materials has been extensively investigated in recent years. The combination of a wide variety of compositions and production processes had permitted the use of these materials in different applications like coatings for corrosion protection of metals. In this work organic-inorganic hybrid materials have been prepared from the hydrolysis of tetraethylorthosilicate and silanol-terminated polidymetilmetoxysilane using a sol-gel process. These materials have been applied on galvanized steel and on steel electroplated with a ZnFe. In order to evaluate the degradation behavior of these coatings, electrochemical techniques (Electrochemical Impedance Spectroscopy and Potentiodynamic Polarization) were used. EIS data was fitted to an equivalent circuit from which the electrochemical parameters were obtained. Results show a good protective character of the hybrid films, when compared with uncovered specimens. The overall performance of the coating systems appears to be highly dependent on the kind of metallic coating applied to the steel.

An approach to design new coatings for biomedical applications

El-Hadad, Amir Abdel-Samie
Fonte: Universidade Carlos III de Madrid Publicador: Universidade Carlos III de Madrid
Tipo: Tese de Doutorado Formato: application/pdf
ENG
Relevância na Pesquisa
56.79%
Ti6Al4V alloy is widely used as implants for orthopedic and dental applications because of its superior mechanical properties, excellent corrosion resistance and good biocompatibility. However, it takes long period of several months for Ti6Al4V implants to integrate with the bone tissue due to their bio-inert feature in nature. An innovating and incipient method to solve the above mentioned drawbacks consist of the development of new coatings which could improve both the biological and corrosion protection performance of the Ti6Al4V alloy. Thus, a variety of strategies have been implemented to modify the surface of Ti6Al4V-based implants and enhance bone growth and their initial stability. A common approach is the deposition of bioactive hybrid coatings including inorganic and organic units on the surface of the Ti6Al4V alloy via sol-gel method. The sol–gel route is of great interest as it offers the possibility of tailoring the material properties by variation of the relative composition of the precursors used. The aim of this thesis is focused on the development of new coatings, starting with inorganic hydroxyapatite (HAp) deposited onto Ti6Al4V substrate prepared through solgel route. The effect of thermal treatment temperature on both in-vitro bioactivity and corrosion performance has been studied in simulated body fluid solution (SBF). A complete physical-chemical characterization was done in all the thermally treated coatings obtained. In-vitro tests in SBF were carried out in order to investigate the biological performance of the films. Due to the high temperature required for synthesizing HAp in crystalline form...

Triethylphosphite as a network forming agent enhances in-vitro biocompatibility and corrosion protection of hybrid organic-inorganic sol-gel coatings for Ti6Al4V alloys

El Hadad, Amir; Barranco, V.; Jiménez Morales, Antonia; Hickman, G. J.; Galván, J. C.; Perry, C. C.
Fonte: Royal Society of Chemistry Publicador: Royal Society of Chemistry
Tipo: info:eu-repo/semantics/acceptedVersion; info:eu-repo/semantics/article
Publicado em /10/2014 ENG
Relevância na Pesquisa
46.6%
The biocompatibility and life of metallic implants can be enhanced through improving the biocompatibility and corrosion protection characteristics of the coatings used with these materials. In this study, triethylphosphite (TEP) was used to introduce phosphorus into organic-inorganic hybrid silica based sol-gel coatings prepared using gamma-methacryloxypropyltrimethoxysilane and tetramethylorthosilicate. Addition of TEP dramatically increased the rate of intermolecular condensation and resulted in materials showing greater cross-linking. Protein (fibrinogen) uptake, osteoblast in vitro biocompatibility and corrosion resistance was enhanced in coatings containing TEP. Although higher concentrations of phosphorus supported the greatest improvement in biocompatibility, a compromise in the phosphorus concentration used would be required if corrosion resistance was most desirable parameter for optimisation. Films prepared by dip coating on Ti6Al4V alloys from these sols offer a promising alternative to wholly metallic prostheses.; This work was supported by the Ministerio de Economía y Competitividad (Project MAT2012-30854).; In Press, Accepted Manuscript

Structural properties of cerium doped siloxane-PMMA hybrid coatings with high anticorrosive performance

Harb, S. V.; Santos, F. C. dos; Caetano, B. L.; Pulcinelli, S. H.; Santilli, C. V.; Hammer, P.
Fonte: Royal Soc Chemistry Publicador: Royal Soc Chemistry
Tipo: Artigo de Revista Científica Formato: 15414-15424
ENG
Relevância na Pesquisa
46.45%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); This study reports on the characterization of cerium doped organic-inorganic hybrid coatings by correlating their structural properties with the corrosion protection efficiency of coated carbon steel. The films were prepared via the sol-gel route from radical polymerization of methyl methacrylate (MMA) with 3-methacryloxy propyltrimethoxysilane (MPTS) followed by acidic hydrolysis and condensation of tetraethoxysilane (TEOS). After identifying the optimum proportion of polymeric and silica phase for the formation of a highly ramified structure (MMA/TEOS = 4), increasing concentration of Ce(IV) ions (0.1% < Ce/Si < 5%) was added to the inorganic precursor to enhance the passivating character of the films. Nuclear magnetic resonance, X-ray photoelectron spectroscopy, small angle X-ray scattering, atomic force microcopy and thermogravimetry were used to characterize the structural properties and electrochemical impedance spectroscopy, potentiodynamic polarization curves and field emission scanning electron microscopy were employed to evaluate the corrosion resistance of the coated samples in a standard saline environment. Structural analysis revealed a high degree of connectivity of the hybrid network...

Recubrimientos sol-gel obtenidos por deposición electroforética (EPD) sobre metales; Sol-gel coatings obtained from electrophoretic depositions (EPD) on metals

Ferrari, B.; Moreno Botella, Rodrigo María; Durán, A.; Castro Martín, Mª Yolanda
Fonte: Sociedad Española de Cerámica y Vidrio Publicador: Sociedad Española de Cerámica y Vidrio
Tipo: Artículo Formato: 668514 bytes; application/pdf
SPA
Relevância na Pesquisa
36.64%
[ES] El proceso sol-gel es un método de gran interés para la producción de películas vítreas sobre metales, que actúan como barrera protectora frente a la oxidación y aumentan su resistencia a la corrosión. Se han obtenido recubrimientos inorgánicos e híbridos de distintas composiciones sobre distintos metales usando técnicas como inmersión, centrifugado y pulverización. Aunque estos métodos proporcionan recubrimientos con buenas propiedades los espesores obtenidos son bajos (inferiores a 2 mm), lo que limita sus posibilidades de aplicación. La deposición electroforética (EPD) se perfila como una técnica de gran versatilidad para la obtención de recubrimientos homogéneos de mayor espesor. El objetivo de este trabajo es la preparación de recubrimientos sobre metal por EPD a partir de soluciones híbridas de SiO2 (TEOS, MTES) y de suspensiones coloidales de SiO2 en las que las propias soluciones híbridas actúan como medio de dispersión. Tanto las soluciones como las suspensiones se han estudiado mediante medidas de viscosidad, densidad y conductividad. Asimismo, se han estudiado los parámetros físicos asociados a la EPD, tales como el tiempo de deposición y la densidad de corriente, teniendo en cuenta el efecto adicional de formación de capa por inmersión durante la extracción. Los recubrimientos se han caracterizado mediante perfilometría y microscopía óptica...

Síntesis y estructura de recubrimientos híbridos de ZrO2-SiO2 obtenidos por sol-gel; Synthesis and structure of hybrid sol-gel ZrO2-SiO2 coatings

Durán, A.; Lópes, A. C.; Gallardo Serra, Ivonne Janet
Fonte: Sociedad Española de Cerámica y Vidrio Publicador: Sociedad Española de Cerámica y Vidrio
Tipo: Artículo Formato: 602630 bytes; application/pdf
SPA
Relevância na Pesquisa
36.55%
[ES] La resistencia a la corrosión de aceros inoxidables en medios acuosos neutros, ácidos y ricos en Cl- mejora notablemente con la aplicación de recubrimientos híbridos de SiO2 preparados por sol-gel. La incorporación de ZrO2 a estos recubrimientos permitiría su empleo en medios alcalinos, siempre que se obtenga una composición homogénea. En este trabajo se ha estudiado dentro del sistema ZrO2/SiO2 el efecto de la variación de las condiciones de preparación del sol precursor y de sinterización en las características finales de las capas. Se prepararon soles por hidrólisis y policondensación de tetrabutóxido de Zr y metiltrietóxisilano (MTES). La naturaleza híbrida de los recubrimientos permitió obtener espesores críticos aproximados a 0.5μm para la composición con mayor contenido de MTES. Por FT-IR y DRX se determinaron altas concentraciones de enlaces Si-O-Zr para temperaturas de síntesis Ts<700ºC, con cristalización de ZrO2(t) a temperaturas superiores. La resistencia electroquímica, evaluada mediante polarización cíclica del acero AISI304 recubierto con estas capas, revela estabilidad en medio alcalino, conservando la resistencia a medios ricos en Cl- característica de los recubrimientos de SiO2.; [EN] Corrosion resistance of stainless steel can be enhanced through the application of SiO2 coatings. However...

Estructura y porosidad de recubrimientos híbridos de SiO2; Structure and porosity of hybrid SiO2 coatings

Durán, A.; Gallardo Serra, Ivonne Janet; Galliano, P.
Fonte: Sociedad Española de Cerámica y Vidrio Publicador: Sociedad Española de Cerámica y Vidrio
Tipo: Artículo Formato: 339906 bytes; application/pdf
SPA
Relevância na Pesquisa
36.52%
[ES] El estudio de la porosidad de los recubrimientos h bridos de SiO2 obtenidos por sol-gel es importante dado que tanto el porcentaje como la morfolog a de los poros determinan sus propiedades m s significativas. En este trabajo se presentan dos metodolog as para caracterizar la porosidad en capas de MTES/TEOS en funci n del tratamiento t rmico y la composici n. En primer lugar se ha determinado el porcentaje de porosidad mediante elipsometr a, modificando el ndice de refracci n del SiO2 v treo para un sistema h brido, utilizando el concepto de propiedades molares aditivas, empleado habitualmente en el estudio de mezclas polim ricas. Por otro lado, se analiz y optimiz un m todo que involucra el an lisis de los espectros FT-IR de las capas de SiO2 en la regi n comprendida entre 1300 y 960 cm-1. El ajuste y deconvoluci n de los espectros ha permitido determinar cuando son necesarias una o dos curvas para ajustar el hombro que afecta a la banda principal del SiO2 (a 1080cm-1 aproximadamente), y su evoluci n con la temperatura. Una de las bandas se ha asignado a la porosidad de la capa y la otra a la densificaci n de la red. Ambas metodolog as conducen a resultados coherentes y similares, probando la consistencia de los modelos.; [EN] Morphology and volumetric fraction of pores (Vp)...

EIS Study of Amine Cured Epoxy-silica-zirconia Sol-gel Coatings for Corrosion Protection of the Aluminium Alloy EN AW 6063

Fontinha,I. Rute; Salta,M. Manuela; Zheludkevich,Mikhail L; Ferreira,Mário G.S.
Fonte: Sociedade Portuguesa de Electroquímica Publicador: Sociedade Portuguesa de Electroquímica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/11/2013 EN
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46.61%
The organic-inorganic hybrid sol-gel films, the structure of which comprises interconnected inorganic and organic networks have been reported as an environmentally friendly anti-corrosion pre-treatment for several metals, including aluminium alloys. In this paper, an epoxy-silica-zirconia hybrid sol-gel coating was synthesized from glycidoxypropyltrimethoxysilane (GPTMS) and zirconium npropoxide (TPOZ) precursors and applied to EN AW-6063 alloy by dip-coating. To promote the organic network formation through the epoxy group polymerization at room temperature, two types of amine crosslinkers were added during synthesis: diethylenetriamine (DETA), in different concentrations, and a tri-functional aminosilane. The evolution of the curing process and the corrosion behaviour of the coated aluminium alloy specimens were evaluated by Electrochemical Impedance Spectroscopy (EIS) in 0.5 M NaCl. The morphology and surface chemistry of the hybrid coatings were characterized by Energy Dispersive Spectroscopy (EDS) coupled with Scanning Electron Microscopy (SEM) and by Fourier Transform Infrared Spectroscopy (FTIR). The results obtained revealed that the sol-gel coatings with lower amine ratios required longer curing times, but showed the best anticorrosive performance with time. The increase in amine concentration has led to a more cross linked organic network...

Synthesis and characterization of new hybrid copolymers for high performance coatings application

Carvalho,A.; Veludo,E.; Machado,J.; Coelho,J. F. J.; Gil,M. H.
Fonte: LNEG - Laboratório Nacional de Energia e Geologia, I.P. Publicador: LNEG - Laboratório Nacional de Energia e Geologia, I.P.
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2012 EN
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Polymeric hybrid materials and their specific functionalization have attracted great interest, due to their chemical, thermal and mechanical properties performance, in relation to their equivalent non hybrids. Siloxane based materials offer great interest due to their excellent chemical, physical and electric properties. The primary structure of the siloxane could be modified either by side chain functionalization or by changing the main chain, forming hybrid materials. This kind of materials could be used in several and diverse areas, namely in protective and high performance coatings. The enhancement of their properties can be achieved by incorporating materials such as polyhedral oligomeric silsesquioxanes (POSS) into their polymeric chain. In this paper are presented two new hybrid polymers, the poly(methyl methacrylate-co-isobutyl acrylate-co-glycidyl methacrylate-co-vinyltriethoxysilane) (POSS_0) and the poly(methyl methacrylate-co-isobutyl acrylate-co-glycidyl methacrylate-co-vinyltriethoxysilane-co-(isobutyl)propyl methacrylate(polisilsesquioxane)(POSS_15). These copolymers were prepared by a radical polymerization, and were designed to have the same structure acrylic, epoxy, silane and POSS fractions, which lead to offer multiple properties with high interest to coating systems due to their epoxy and siloxane groups. The presence of the POSS cage in the hybrid polymeric structure increases the hydrophobic character and the thermal stability. When applied in commercial bi-component anti-corrosive paint formulations...