Response of nanocrystalline cerium-based conversion coatings on Al 2024-T3 to chloride environments

You, Shaoxin; Jones, Philip S.; Padwal, Ajay; Yu, Ping; O’Keefe, Matthew J.; Fahrenholtz, William G.; O’Keefe, Thomas J.

doi:10.1016/j.matlet.2006.12.062

Cited by 46 publications

(55 citation statements)

References 3 publications

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“…Auger electron spectroscopy (AES; Perkin-Elmer 545) depth profiling was used to measure coating thickness. Coating thicknesses were judged by the point where the Ce and Al lines crossed [22,23]. A sputter rate of 9 nm/min was assumed based on results from a Ta 2 O 5 standard.…”

Section: Methodsmentioning

confidence: 99%

“…CeCCs have been deposited on Al alloy 2024-T3 using immersion methods [18][19][20]. Recently, CeCCs have also been deposited on Al alloy 2024-T3 using a spray process that employs a water-based solution containing cerium chloride and hydrogen peroxide [21][22][23][24][25][26]. Previous research has shown that processing parameters of CeCCs have a large impact on the corrosion resistance.…”

Section: Introductionmentioning

confidence: 99%

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Screening study of spray solution parameters for depositing cerium-based conversion coatings on Al alloy 2024-T3

Geng

O’Keefe

et al. 2009

J Appl Electrochem

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Cerium-based conversion coatings were deposited on aluminum alloy 2024-T3 by a spray process using a solution containing cerium chloride, hydrogen peroxide, and gelatin. As deposited coatings were composed of hydrated cerium oxide and were post-treated in a phosphate solution to improve corrosion performance. Coating solution parameters, including the pH (1-2.5), cerium chloride concentration (0.025-0.125 M), and hydrogen peroxide content (0-1.2 M), were varied to investigate the effect(s) of solution parameters on the corrosion performance of the post-treated coatings. Results indicated that thickness of coatings deposited from solutions with different pH values were similar, while coating thickness increased with increasing concentration of cerium chloride and hydrogen peroxide in the solutions. Electrochemical impedance spectroscopy and observations of the surface appearances of the coatings indicated that coatings deposited from solutions with a pH 2, a cerium concentration of 0.1 M, and a hydrogen peroxide concentration of 0.8 M exhibited the best corrosion resistance.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Screening study of spray solution parameters for depositing cerium-based conversion coatings on Al alloy 2024-T3

Geng

O’Keefe

et al. 2009

J Appl Electrochem

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“…Also, some other research was concentrated on obtaining bulk material with both high strength and low SCC susceptibility while just few ones have been attended to the surface treatments of these alloys despite the fact that the surface of the alloy has more severe responsibility in SCC initiation. However, the research was generally limited to explore different coatings or conventional shot-peening to avoid surface microcracks (Ref [14][15][16]. In one case, it was reported that pre-immersion in an alkaline 3.5% NaCl for 240 h can be a contributor for enhancement in SCC resistance.…”

Section: Introductionmentioning

confidence: 99%

The Effect of the Surface Treating and High-Temperature Aging on the Strength and SCC Susceptibility of 7075 Aluminum Alloy

Fooladfar

Hashemi

Younesi

2009

J. of Materi Eng and Perform

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A novel heat-treatment procedure combining the shot-peening with a two-step aging operation was proposed to improve both the strength and the stress corrosion cracking (SCC) resistance of the high-strength 7075 aluminium alloy. The heat treatment included one shot-peening stage before or between the two stages of aging at 120°C for 24 h and at 160°C for 1 h, respectively. The mechanical properties obtained during the aforementioned operations were extremely similar to those of the T6 sample owing to the unaffected bulk microstructure over such a low over-aging period. The SCC resistance of these samples was considerably improved compared to that of the T6 sample and of the conventional shot-peened T6 sample due to the over-aging of the surface like the T7 treatment leading from the diffusion acceleration by the dislocations generated in the surface layer during shot-peening. In spite of the further depth of deformation caused by shot-peening prior to the first step of aging, the sample shot-peened after the first step of aging showed no significant decrease in the SCC resistance because of its higher generated dislocation by shot-peening.

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“…14, 15 Hughes et al, 16 Hinton et al 17 and Mansfeld et al 18 achieved enhanced corrosion resistance for AA2024 and 7075 aluminum alloys after spontaneous deposition of conversion coatings in Ce(III) solutions at ambient temperature. Their results have been taken as a starting point for this research.…”

mentioning

confidence: 99%

Development of Cerium-Rich Layers on Anodic Films Formed on Pure Aluminium and AA7075 T6 Alloy

Gordovskaya

Hashimoto

Walton

et al. 2014

J. Electrochem. Soc.

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The development of cerium-rich layers on anodized pure aluminum and AA7075 T6 aluminum alloy has been investigated using scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The surfaces of pure aluminum and AA7075 T6 were pre-treated by alkaline etching and HNO 3 desmutting followed by anodizing in sulfuric acid electrolyte with and without addition of tartaric acid. The outer layer is created by immersion in a cerium (III) nitrate solution containing hydrogen peroxide. It is shown that anodizing in a mixture of sulfuric and tartaric acids prior to the immersion treatment leads to the formation of a thicker and a more uniform cerium-rich layer. The ultramicrotomed sections display the presence of cerium species within the pores of the anodic film. This treatment significantly improves the corrosion resistance of the material. Aluminium alloys are widely used in the aerospace industry because of their high strength to weight ratio. The high strength is achieved by alloying with copper, magnesium, silicon, manganese, and zinc.1,2 However, the resulting microstructure contains intermetallic particles that are more or less noble than the alloy matrix, thereby increasing the corrosion susceptibility of the alloy compared with high purity aluminum. Traditionally, anodizing in chromic acid electrolyte has been used for corrosion protection, with the presence of residual chromate ions within the pores of the anodic film providing corrosion inhibition.3,4 However, the use of chromic acid has associated health issues, as well as having a negative environmental impact.Recently, sulfuric acid (SA) and tartaric/sulfuric acid (TSA) electrolytes have been used as alternatives to chromic acid for anodizing. 5The effect of tartaric acid on the anodic film morphology and corrosion resistance of anodized AA 2024 T3 was studied by Boisier at al. 6 It was found that the addition of tartaric acid to the anodizing electrolyte generates anodic films with reduced porosity and with the pores better distributed over the filmed aluminum surfaces due to the reduced rate of chemical dissolution of the alumina in TSA electrolyte. Several studies have shown that films formed in TSA solution are more resistant to corrosion than films obtained in SA only, but the presence of tartaric acid in the anodizing electrolyte does not change the anodic film morphology. 7,8,9 The protective properties of the anodic oxide films formed in sulfuric acid, with or without tartaric addition, may be enhanced by addition of rare earth compounds (e.g cerium-based compounds) before, during or after anodizing. [10][11][12][13] The main benefits of cerium-based layers are high corrosion resistance, non-toxicity, and a relatively fast deposition process.14,15 Hughes et al., 16 Hinton et al. 17 and Mansfeld et al. 18 achieved enhanced corrosion resistance for AA2024 and 7075 aluminum alloys after spontaneous deposition of conversion coatings in Ce(III) solutions at ambient temperature. Their results have been taken as a ...

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Response of nanocrystalline cerium-based conversion coatings on Al 2024-T3 to chloride environments

Cited by 46 publications

References 3 publications

Screening study of spray solution parameters for depositing cerium-based conversion coatings on Al alloy 2024-T3

Screening study of spray solution parameters for depositing cerium-based conversion coatings on Al alloy 2024-T3

The Effect of the Surface Treating and High-Temperature Aging on the Strength and SCC Susceptibility of 7075 Aluminum Alloy

Development of Cerium-Rich Layers on Anodic Films Formed on Pure Aluminium and AA7075 T6 Alloy

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