Influence of surface preparation on performance of chromate conversion coatings on Alclad 2024 aluminium alloy

Campestrini, P.; Westing, E.P.M. van; Wit, J.H.W. de

doi:10.1016/s0013-4686(01)00476-5

Cited by 112 publications

(57 citation statements)

References 15 publications

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“…Chromate conversion coatings (CCC) are largely used as pretreatments for aluminum alloys in aerospace applications [1][2][3][4][5][6][7]. Conversion treatments based on chromate compounds, containing hexavalent chromium, chromium (VI) or, simply Cr (VI), provide many advantages, such as low cost, easy application, promote excellent protection against localized corrosion, and favors adhesion to paints and adhesives [1][2][3][4][5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

“…Conversion treatments based on chromate compounds, containing hexavalent chromium, chromium (VI) or, simply Cr (VI), provide many advantages, such as low cost, easy application, promote excellent protection against localized corrosion, and favors adhesion to paints and adhesives [1][2][3][4][5][6][7][8][9][10]. However, chromate solutions cause large environmental and health related problems, because they contain Cr (VI) compounds that have several toxic effects.…”

Section: Introductionmentioning

confidence: 99%

“…However, chromate solutions cause large environmental and health related problems, because they contain Cr (VI) compounds that have several toxic effects. Due to pressures from health and environmental legislation, researchers have devoted attention in the development of alternative coatings of lower toxicity than yellow chromatizing conversion coating for corrosion protection of metallic materials [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Consequently, there has been an upsurge of interest in the corrosion prevention of aluminum alloys using nanostructured surface pre-treatments based on selfassembled molecules (SAMs) [15][16][17][18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

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Nanostructured surface pre‐treatment based on self‐assembled molecules for corrosion protection of Alclad 7475‐T761 aluminum alloy

Souza

Yoshikawa

Izaltino

et al. 2011

Materials & Corrosion

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Coatings based on self-assembled molecules (SAMs) for corrosion protection of aircraft aluminum alloys have been studied to evaluate their potentialities as replacements to yellow chromate conversion coatings (CCC), due to the toxicity of these leading to environmental problems. In this work, the influence of alkane diphosphonates self-assembling molecules on the corrosion resistance of the AA7475-T761 cladded with AA7072 was investigated by electrochemical impedance spectroscopy and cathodic and anodic polarization curves, in naturally aerated 0.5 mol/L Na 2 SO 4 aqueous solution, with pH adjusted to 4. Corrosion accelerated experiments (salt spray tests) were also carried out to examine the resistance of the SAM treated samples against corrosion. The results suggested that the development of boehmite (aluminum oxide) layer with incorporation of SAM was beneficial to the corrosion resistance of the tested aluminum alloy. Samples surface treated with SAM or aluminum oxide/ SAM (without and with subsequent polyester layer) showed better corrosion resistance results than samples with CCC, indicating that this last type of coating containing hexavalent chromium could be replaced by the environmentally friendly pre-treatment corresponding to boehmite growth followed by incorporation of SAM.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Nanostructured surface pre‐treatment based on self‐assembled molecules for corrosion protection of Alclad 7475‐T761 aluminum alloy

Souza

Yoshikawa

Izaltino

et al. 2011

Materials & Corrosion

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“…1 In industry, the classical treatment used to protect Al alloys from corrosion involves the application of a chromium oxide layer obtained either by anodisation or through chemical conversion procedures. [2][3][4][5][6][7] According to the literature, the presence of leachable Cr 6+ in the composition of the chromate layer guarantees corrosion protection to the alloy through a self-healing mechanism where these species diffuse to weaker spots of the layer recomposing its protective properties due to the precipitation of Cr 2 O 3.…”

Section: Introductionmentioning

confidence: 99%

“…Electrochemical impedance spectroscopy (EIS) has been largely used to characterise conversion coated Al alloys. [2][3][4][5]12,15,21,23,24,26 However, only few works have used EIS to characterise Al alloys coated with CeCL, 21,23,24 moreover in all of these works the use of EIS was mainly aimed to extract impedance values upon immersion of the converted samples in the electrolytic solutions. Mansfeld and co-workers [17][18][19] have also used EIS to investigate the corrosion behaviour of Al alloys covered with Ce conversion coatings, however, it seems that the results obtained by these authors are more linked to the thickening of the Al oxide layer than to the presence of a CeCL itself.…”

Section: Introductionmentioning

confidence: 99%

Microstructural and electrochemical characterization of environmentally friendly conversion layers on aluminium alloys

Palomino

Castro

Aoki

et al. 2003

J. Braz. Chem. Soc.

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Camadas de conversão ricas em Ce têm sido investigadas como possíveis substitutas às camadas de cromo na proteção contra a corrosão de ligas de alumínio. Neste trabalho a microestrutura e o comportamento eletroquímico da liga de alumínio 2024 com e sem camada de conversão de Ce foram investigados utilizando MEV-EDS e EIE. Resultados de EDS mostraram que a presença de partículas de Cu depositadas sobre a superfície da liga estimula a formação da camada de conversão aumentando a intensidade dos picos de Ce no espectro EDS. Os experimentos de EIE mostraram que a presença da camada de conversão aumenta o valor da impedância, e que a evolução das características da camada pode ser seguida pelas mudanças que ocorrem no ângulo de fases em alta freqüência. As curvas potentiodinâmicas mostraram que a proteção conferida pela camada de conversão deve-se ao bloqueio da reação de redução do oxigênio.Cerium conversion layers (CeCL) have been investigated as a replacement for chromium conversion layers to protect Al alloys against corrosion. In this work the microstructure and the electrochemical behaviour of aluminium alloy 2024 with and without CeCL were investigated using, respectively, SEM-EDX and EIS. EDX results have shown that the presence of dispersed plated Cu particles on the alloy surface enhances the formation of the CeCL increasing the intensity of Ce peaks in the EDX spectra. EIS measurements on conversion-coated samples have shown that the presence of the layer increases the impedance, and that its presence is detected by the presence of a high frequency time constant. Results of potentiodynamic experiments have shown that the corrosion protection afforded by the conversion layer is due to the hindrance of the oxygen reduction reaction and that the pitting potential of the alloy is not changed.

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Application of Inhibitor‐Loaded Halloysite Nanotubes in Active Anti‐Corrosive Coatings

Fix

Andreeva

Lvov

et al. 2009

Adv Funct Materials

251

138

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Halloysite particles are aluminum‐silicate hollow cylinders with a length of 0.5–1 µm, an outer diameter of ca. 50 nm and a lumen of 15 nm. These nanotubes are used for loading and sustained release of corrosion inhibitors. The inhibitor is kept inside the particles infinitely long under dry conditions. Here, halloysite nanotubes filled with anticorrosive agents are embedded into a SiOx–ZrOx hybrid film. An aluminum plate is dip‐coated and immersed into 0.1 M sodium chloride aqueous solution for corrosion tests. A defect in the sol–gel coating induces pitting corrosion on the metal accompanied by a strong anodic activity. The inhibitor is released within one hour from halloysite nanotubes at corrosion spots and suppresses the corrosion process. The anodic activity is successfully restrained and the protection remains for a long time period of immersion in NaCl water solution. The self‐healing effect of the sol–gel coating doped with inhibitor‐loaded halloysite nanotubes is demonstrated in situ via scanning vibrating electrode technique measurements.

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Influence of surface preparation on performance of chromate conversion coatings on Alclad 2024 aluminium alloy

Cited by 112 publications

References 15 publications

Nanostructured surface pre‐treatment based on self‐assembled molecules for corrosion protection of Alclad 7475‐T761 aluminum alloy

Nanostructured surface pre‐treatment based on self‐assembled molecules for corrosion protection of Alclad 7475‐T761 aluminum alloy

Microstructural and electrochemical characterization of environmentally friendly conversion layers on aluminium alloys

Application of Inhibitor‐Loaded Halloysite Nanotubes in Active Anti‐Corrosive Coatings

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