Navegação IPEN por assunto "tartaric acid"

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  • IPEN-PUB-3

    VASCONCELLOS, M.B.A. ; LIMA, F.W. . Coprecipitation with ferric hydroxide: an application to the separation of copper and arsenic and of arsenic and antimony. 1979. 24 p.

    Palavras-Chave: activation analysis; ammonium hydroxides; antimony; arsenic; copper; coprecipitation; iron hydroxides; tartaric acid

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  • IPEN-DOC 22769

    COSTENARO, HELLEN; QUEIROZ, FERNANDA M.; TERADA, MAYSA; MARIE-GEORGES, OLIVIER; COSTA, ISOLDA ; MELO, HERCILIO G. de. Corrosion protection of AA2524-T3 anodized in tartaric-sulfuric acid bath and protected with hybrid sol-gel coating. Key Engineering Materials, v. 710, p. 210-215, 2016. DOI: 10.4028/www.scientific.net/KEM.710.210

    Abstract: 2xxx Al alloys are particularly sensitive to localized corrosion in chloride environments and in order to maintain their integrity, minimize maintenance needs and repairs, and to maximize component life, protective treatments are required. Anodizing is an electrochemical process based on the growth of the Al oxide layer by applying anodic potentials. One of the alternatives is tartaric/sulphuric acid (TSA) anodizing, which is environmentally compliant and provides corrosion resistance properties, compatible with the requirements of the aerospace industry with appropriate paint adhesion. In this study, AA2524-T3 specimens were anodized in a tartaric-sulfuric acid bath (TSA) and subsequently protected by application of a hybrid sol–gel coating. The sol–gel coating was prepared using a solution with high water content (58 %v/v) and obtained by the hydrolysis and condensation of tetraethoxysilane (TEOS) and 3-glycidoxypropyltrimethoxysilane (GPTMS). The corrosion resistance evaluation of both unsealed and coated samples was carried out in a sodium chloride solution by EIS as a function of immersion time. The results were also fitted using electrical equivalent circuits.

    Palavras-Chave: corrosion protection; tartaric acid; sulfuric acid; sol-gel process; alloys; corrosion; coatings; anodization

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  • IPEN-DOC 23661

    COSTENARO, HELLEN; QUEIROZ, FERNANDA M.; TERADA, MAYSA; OLIVIER, MARIE-GEORGES; COSTA, ISOLDA ; MELO, HERCILIO G. de. Corrosion protection of AA2524-T3 anodized in tartaric-sulfuric acid bath and protected with hybrid sol–gel coating. In: INTERNATIONAL ALUMINIUM CONFERENCE, 13th, September 21-23, 2016, Naples, Italy. Proceedings... 2016.

    Abstract: 2xxx Al alloys are particularly sensitive to localized corrosion in chloride environments and in order to maintain their integrity, minimize maintenance needs and repairs, and to maximize component life, protective treatments are required. Anodizing is an electrochemical process based on the growth of the Al oxide layer by applying anodic potentials. One of the alternatives is tartaric/sulphuric acid (TSA) anodizing, which is environmentally compliant and provides corrosion resistance properties, compatible with the requirements of the aerospace industry with appropriate paint adhesion. In this study, AA2524-T3 specimens were anodized in a tartaric-sulfuric acid bath (TSA) and subsequently protected by application of a hybrid sol–gel coating. The sol–gel coating was prepared using a solution with high water content (58 %v/v) and obtained by the hydrolysis and condensation of tetraethoxysilane (TEOS) and 3-glycidoxypropyltrimethoxysilane (GPTMS). The corrosion resistance evaluation of both unsealed and coated samples was carried out in a sodium chloride solution by EIS as a function of immersion time. The results were also fitted using electrical equivalent circuits.

    Palavras-Chave: sol-gel process; corrosion; aluminium alloys; corrosion protection; tartaric acid; sulfuric acid; hybridization; hydrolysis; anodization

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  • IPEN-DOC 25752

    TERADA, M. ; QUEIROZ, F.M.; AGUIAR, D.B.S.; AYUSSO, V.H. ; COSTENARO, H.; OLIVIER, M.G.; MELO, H.G. de; COSTA, I. . Corrosion resistance of tartaric-sulfuric acid anodized AA2024-T3 sealed with Ce and protected with hybrid sol–gel coating. Surface & Coatings Technology, v. 372, p. 422-426, 2019. DOI: 10.1016/j.surfcoat.2019.05.028

    Abstract: 2024 aluminum alloys are widely used in the aerospace industry due to properties as lightweight, high specific strength and durability. However, they are prone to localized corrosion due to its high amount of intermetallics. A promising method to protect the exposed metal surface is to use eco-friendly alternative corrosion inhibitors in combination with a barrier coating system. In this study, a treatment in an aqueous solution with the addition of cerium ions has been proposed and its effects on the corrosion resistance of the AA2024-T3 alloy were investigated. Samples were anodized, hydrothermally treated in aqueous solutions, containing or not cerium ions at the boiling temperature and then coated with sol-gel. The effect of Ce ions in the characteristics of the surface film formed, such as morphology and corrosion resistance, was investigated by scanning electron microscopy and electrochemical impedance spectroscopy (EIS). The EIS results showed that the addition of Ce(III) ions improved the corrosion resistance of the AA 2024-T3 TSA anodized and hydrothermally treated.

    Palavras-Chave: aluminium alloys; corrosion; anodization; tartaric acid; sulfuric acid; cerium ions; sol-gel process; electrochemistry

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  • IPEN-DOC 23664

    ALMEIDA, THALLIS L.; QUEIROZ, FERNANDA M. ; TERADA, MAYSA ; COSTA, ISOLDA ; CAPELOSSI, VERA R.. Efeito da selagem hidrotérmica com adição de íons Ce (III) na proteção à corrosão da liga de alumínio AA7475-T761 anodizada em banho ácido tartárico-sulfúrico. In: CONGRESSO BRASILEIRO DE CORROSAO, 36.; INTERNATIONAL CORROSION MEETING, 6th; CONCURSO DE FOTOGRAFIA DE CORROSAO E DEGRADAÇAO DE MATERIAIS, 20.; EXPOSIÇAO DE TECNOLOGIAS PARA PREVENÇAO E CONTROLE DA CORROSAO, 36., 16-20 de maio, 2016, Búzios, RJ. Anais... Rio de Janeiro, RJ: ABRACO, 2016. p. 1-13.

    Abstract: The aluminum alloys of series 7XXX have excellent mechanical properties combined with low density and are often used in the aeronautic industry. However, their susceptibility to localized corrosion requires the use of protective coatings to ensure their long-term life. In the aircraft industry, the anodization process is an effective corrosion control method. Besides, the anodized layer sealing treatment of parts that are not used with coatings, provide further protection. However, both processes, anodization and sealing, generally employ baths containing Cr (VI) ions. These are highly toxic to the environment and carcinogenic. In this work, the AA7475-T761 alloy was anodized in a solution of tartaric-sulfuric acid (TSA) and then the anodic layer was hydrothermally sealed in aqueous solutions, either with or without the addition of Ce (III) ions. The effect of sealing time on the corrosion protection of the anodic layer was investigated for periods of sealing corresponding to 2.5 min, 5 min, 7.5 min and 10 min. The corrosion resistance of the anodized alloy samples was evaluated by electrochemical impedance spectroscopy (EIS) as a function of exposure time to a sodium chloride electrolyte. Higher impedances were associated with anodic layers hydrothermally sealed for 7.5 min and 10 min in Ce (III) ions containing solution. Surface observation was carried out by scanning electron microscopy (SEM) and the results indicated that hydrothermal treatments in solution with Ce (III) ions leads to anodic layers with decreased porosity.

    Palavras-Chave: aluminium alloys; anodization; electrochemical coating; sealing materials; hydrothermal systems; tartaric acid; sulfuric acid; cerium oxides

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  • IPEN-DOC 26654

    TERADA, MAYSA ; QUEIROZ, FERNANDA M.; COSTENARO, HELEN; AYUSSO, VICTOR H. ; OLIVIER, MARJORIE; COSTA, ISOLDA ; MELO, HERCILIO G. de. Effect of cerium addition to a hydrothermal treatment on the corrosion protection of the tartaric-sulfuric acid anodized AA2524-T3. Corrosion, v. 75, n. 9, p. 1110-1117, 2019. DOI: 10.5006/3063

    Abstract: To protect Al alloys from corrosion, standard procedures in the aerospace industry use chromium-based acid anodizing with subsequent post-treatment steps also containing hexavalent chromium (Cr(VI)) ions. However, environmental and health related concerns associated with Cr(VI) have encouraged the search for new surface treatments providing effective corrosion protection without the drawback of generating toxic residues. In this investigation, a hydrothermal treatment in aqueous solution with cerium ions is proposed as a post-treatment for tartaric-sulfuric acid (TSA) anodizing, and its effects on the AA2524-T3 alloy corrosion resistance investigated. The effect of Ce on the characteristics of the surface film formed, such as morphology and corrosion resistance, is investigated by scanning electron microscopy and electrochemical impedance spectroscopy (EIS). The results show that the hydrothermal treatment in solution containing Ce(III) ions presents a less stable behavior than the treatment in boiling water. However, the results of the EIS experiments show recovery of the protective properties of the system, indicating that some self-healing properties must be imparted to the system.

    Palavras-Chave: cerium; corrosion protection; hydrothermal systems; tartaric acid; sulfuric acid; aluminium alloys; corrosion fatigue; scanning electron microscopy

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  • IPEN-DOC 23658

    QUEIROZ, F.M.; TERADA, M.; COSTENARO, H.; AYUSSO, V.H. ; OLIVIER, M.G.; COSTA, I. ; MELO, H.G. de. Effect of hydrothermal treatments with Ce (III) ions on the corrosion resistance of AA2524-T3 alloy anodized in TSA and protected with hybrid sol–gel coating. In: INTERNATIONAL SYMPOSIUM ON ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY, 10th, June 19-24, 2016, A Toxa, Galicia, Spain. Abstract... 2016. p. 1.

    Abstract: Aircraft parts made of aluminum alloys are protected by organic coatings in order to avoid their exposure to the corrosive environment. Prior to organic coating, aluminum alloys are anodized usually by a process that generates toxic residues leading to environmental and health related problems [1,2]. Recently, chromium free anodizing processes have been proposed as viable alternatives to commercial chromic acid anodizing processes. The AA2524-T3 alloy was originally developed as a replacement for AA2024-T3. It presents high damage-tolerance and excellent fatigue properties. However, it also presents high susceptibility to localized corrosion, such as pitting corrosion and stress corrosion cracking. In this study, AA2524-T3 specimens were anodized in a tartaric-sulfuric acid (TSA) bath, and then exposed to hydrothermal treatment in aqueous solutions containing cerium ions at the boiling temperature. Samples with hydrothermal treatment in boiling water were also prepared for comparison reasons. Subsequently to hydrothermal treatments, the samples were coated by a hybrid sol–gel coating. The sol–gel coating was prepared using a solution with high water content (58 %v/v) and was obtained by hydrolysis and condensation of TEOS and GPTMS. The corrosion resistance of both systems was evaluated in a NaCl solution by EIS as a function of immersion time. The EIS results showed that the addition of Ce(III) ions improved the corrosion resistance of the TSA anodized AA2524-T3 alloy with sol-gel coating. The EIS results were fitted and interpreted using electrical equivalent circuits.

    Palavras-Chave: aluminium alloys; coatings; toxic materials; sol-gel process; tartaric acid; sulfuric acid; hydrothermal systems; corrosion; cerium oxides

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  • IPEN-DOC 23665

    COSTENARO, HELLEN; QUEIROZ, FERNANDA M.; TERADA, MAYSA; PAINT, YOANN; RENAUD, ALEXIS; OLIVIER, MARIE-GEORGE; COSTA, ISOLDA ; MELO, HERCILIO G. de. EIS and Salt-Spray study of AA2524 anodized in tartaric-sulfuric acid bath and protected with hybrid sol–gel coating. In: CONGRESSO BRASILEIRO DE CORROSAO, 36.; INTERNATIONAL CORROSION MEETING, 6th; CONCURSO DE FOTOGRAFIA DE CORROSAO E DEGRADAÇAO DE MATERIAIS, 20.; EXPOSIÇAO DE TECNOLOGIAS PARA PREVENÇAO E CONTROLE DA CORROSAO, 36., 16-20 de maio, 2016, Búzios, RJ. Proceedings... Rio de Janeiro, RJ: ABRACO, 2016. p. 1-14.

    Abstract: AA2524 is a relatively new brand of aluminum alloy designed to build lightweight structural components in aerospace industry. To be employed in aircrafts, high strength Al alloys need to be protected from corrosion by a robust protection system. One of the steps applied in the protection protocol is anodizing, which is known to greatly improve the corrosion resistance of Al alloys. In the present investigation, a sol-gel hybrid layer was applied as a post-treatment step for anodized AA2524 and the corrosion resistance of the system evaluated by means of EIS measurements and salt-spray tests. The anodizing process was performed in a tartaric-sulfuric acid (TSA) bath, which is more environmentally friendly than the traditional chromic acid anodizing baths, and the sol–gel solution was prepared by mixing tetraethoxysilane (TEOS) and 3-glycidyloxypropyl-trimethoxysilane (GPTMS) precursors in a solution with high water content. For comparison reasons, TSA anodized samples were also hydrothermally sealed in boiling deionized water. The results of both EIS and salt-spray tests demonstrated superior corrosion resistance for the anodized samples post-treated with the hybrid sol-gel layer. Electrical equivalent circuit fitting of the EIS data indicated that the hybrid sol-gel layer strongly hinders electrolyte penetration through the porous layer, better protecting the underlying substrate.

    Palavras-Chave: aluminium alloys; sol-gel process; coatings; corrosion protection; anodization; sulfuric acid; tartaric acid

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  • IPEN-DOC 23560

    QUEIROZ, F.M. ; BUGARIN, A.F.S. ; HAMMEL, N.P. ; CAPELOSSI, V.R.; TERADA, M.; COSTA, I. . EIS behavior of anodized and primer coated AA2198–T851 compared to AA2024–T3 exposed to salt spray CASS test. Surface and Interface Analysis, v. 48, n. 8, p. 755-766, 2016. DOI: 10.1002/sia.5982

    Abstract: In this investigation, the corrosion behavior of AA2198–T851 was compared to AA2024–T3 by electrochemical impedance spectroscopy and the surface of both alloys was analyzed by Field Emission Gun (FEG) scanning electron microscopy (SEM) and Xray energy dispersive analysis (EDX). Electrochemical impedance spectroscopy (EIS) results for the uncoated surface of both alloys showed higher pitting susceptibility associated to the AA2198–T851 alloy comparatively to the AA2024–T3. In order to improve the corrosion resistance of both alloys, tartaric sulphuric acid anodising (TSA) was carried out with both alloys followed by primer application. The corrosion resistance of the anodized and primer coated samples was also evaluated by CASS salt spray test followed by EIS tests at increasing periods of exposure to the CASS test. The results showed larger amounts of corrosion products associated to the primer coated AA2198–T851 alloy comparatively to the AA2024–T3 alloy. Diffusionwas only indicated in the EIS results of the AA2198–T851 samples likely because of large amounts of porous corrosion products on the exposed surface of this alloy to the corrosive environment.

    Palavras-Chave: aluminium alloys; electrochemistry; impedance; spectroscopy; tartaric acid; sulfuric acid; corrosion; corrosion resistance; corrosion products; anodes; layers

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  • IPEN-DOC 25862

    RAMIREZ, OSCAR M.P.; QUEIROZ, FERNANDA M.; TERADA, MAYSA; DONATUS, UYIME ; COSTA, ISOLDA ; OLIVIER, MARIE-GEORGES; MELO, HERCILIO G. de. EIS investigation of a Ce‐based posttreatment step on the corrosion behaviour of Alclad AA2024 anodized in TSA. Surface and Interface Analysis, v. 51, n. 12, SI, p. 1260-1275, 2019. DOI: 10.1002/sia.6633

    Abstract: In the aircraft industry, anodizing and posttreatment steps use Cr (VI) compounds, which, despite offering good corrosion resistance and self‐healing properties, are highly toxic and carcinogenic. Ce compounds are recognized as efficient corrosion inhibitors for Al alloys, and several works report self‐healing ability for these chemicals. In this investigation, the corrosion resistance of Alclad AA2024‐T3 alloy anodized in tartaric‐sulphuric acid (TSA) bath and posttreated in a solution comprising cerium nitrate without and with hydrogen peroxide was evaluated. The purpose is to investigate the potentiality of using hydrothermal treatment in Ce nitrate solution as candidate to replace Cr (VI) posttreatment. The aim is to provide a posttreatment step which, while improving the corrosion resistance, does not plug the mouths of the pores maintaining the adhesion properties of the porous anodic layer. Microstructural characterization was carried out by SEM‐EDS whereas corrosion resistance was evaluated by EIS. The surface analysis showed that the posttreatments, all performed at 50°C, kept the open structure of the pores. EIS analysis showed that the posttreatments performed in the H2O2 solution for short immersion times were the most effective in improving the corrosion resistance of the samples, whereas electrical equivalent circuit (EEC) fitting of the data indicated sealing of the porous layer during the immersion of the different samples in the test solution. SEM‐EDS analysis of the samples posttreated in the H2O2 containing solution, prior and after the corrosion test, showed the presence of Ce oxy‐hydroxide randomly deposited on the sample surface, indicating that Ce could be incorporated/stored in the anodic layer.

    Palavras-Chave: aluminium alloys; anodization; cerium nitrates; equivalent circuits; impedance; spectroscopy; electrochemical cells; corrosion resistance; tartaric acid; sulfuric acid

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