Role of Tartaric Acid on the Anodizing and Corrosion Behavior of AA 2024 T3 Aluminum Alloy

Curioni, Michele; Skeldon, P.; Королева, Е. В.; Thompson, G.E.; Ferguson, John F.

doi:10.1149/1.3077602

Cited by 91 publications

(83 citation statements)

References 11 publications

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“…The anodizing solution was 0.46 M sulfuric acid and 0.53 M tartaric acid, which is the standard solution for the industrial TSA process and is used in numerous previous studies on the topic. 28,29 As reference electrode, a saturated calomel electrode was employed, whereas the counter electrode was pure aluminum. The anodizing process was performed at 37…”

Section: Methodsmentioning

confidence: 99%

Development of a Chromium-Free Post-Anodizing Treatment Based on 2-Mercaptobenzothiazole for Corrosion Protection of AA2024T3

Yang¹,

Yang²,

Balaskas³

et al. 2017

J. Electrochem. Soc.

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The anticorrosion performance provided by new anodizing and sealing methods for the AA2024T3 aluminum alloy is discussed in this work. Two anti-corrosion post-anodizing treatments based on immersion in an ethanol solution containing 2-mercapto-benzothiazole (2-MBT) were applied. Both treatments consisted of the immersion of the anodized specimens in 2-MBT ethanol solution, but the second was followed by hydrothermal sealing in water. Electrochemical Impedance Spectroscopy (EIS) and an immersion test show that both treatments exhibited improved corrosion resistance compared with anodized AA2024-T3 that was only hot water sealed. Considering that these novel anti-corrosion methods appear to provide enhanced, long-term and stable corrosion resistance to the AA2024T3 aluminum alloy, the use of 2-mercaptobenzothiazole (2-MBT) is proposed as a promising inhibitor in sealing treatments. AA2024T3 aluminum alloy is widely used in the aerospace industry due to its high strength to weight ratio.1 However, high amounts of copper, together with magnesium and other alloying elements, generate second-phase particles that cause microgalvanic coupling in the presence of moisture or aqueous electrolyte, thereby reducing corrosion resistance.Anodizing is an electrochemical method that converts the aluminum surface into a corrosion-resistant, durable oxide layer with a porous structure. The pore diameter, thickness, structure and morphology of the oxide layer depend on the applied anodizing conditions, such as anodizing potential, temperature and electrolyte.2 Traditionally, anodizing of aluminum alloys is usually performed in chromic acid electrolytes, and it is followed by sealing in dichromate solution. However, as a result of its toxicity, 3 legislation will severely restrict the use of sodium dichromate, which has led to the development of alternative dichromate-free sealing treatments. [4][5][6] The restriction on the use of chromium Cr (IV) compounds has also led to the development of alternative chromium-free anodizing methods, including the sulfuric-tartaric process (TSA), a typical anodizing method used in aerospace industries. [7][8][9][10] In simple terms, the anodizing process is used to obtain a thick aluminum oxide layer with a porous structure, whereas the sealing process is used to close the pores with hydrated products, thereby further increasing the corrosion resistance. A detailed discussion of the complex effects of pore morphology, film thickness, sealing time and nature of the sealing solution can be found elsewhere and it is not reported in detail here.11-15 Different types of sealing methods have been studied, including dichromate sealing, hot water sealing, and nickel acetate sealing. 16 Commonly quoted sealing treatments are hot water or aqueous nickel acetate, but neither is as good as hexavalent chromiumbased processes; moreover, both are energy consuming as the sealing takes place at 95• C. In addition, new sealing techniques such as cerium sealing have been developed during the last decade, 10,[17][18...

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Section: Methodsmentioning

confidence: 99%

Development of a Chromium-Free Post-Anodizing Treatment Based on 2-Mercaptobenzothiazole for Corrosion Protection of AA2024T3

Yang¹,

Yang²,

Balaskas³

et al. 2017

J. Electrochem. Soc.

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“…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.…”

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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“…Currently, different electrolytes are typically mixed in the anodizing bath to create the conditions that will result in film features similar to CAA anodic oxides. Some examples include boric-sulfuric acid anodizing (BSA) 4 , phosphoric acid modified boric-sulfuric and anodizing 5 , tartaric-sulfuric acid anodizing (TSA) 6 and phosphoric and sulfuric acid (PSA) anodizing 7 . In this paper, we focus on the latter option being the prime Cr(VI)-free candidate for bonded components that will serve as part of the loadcarrying primary aircraft structure.…”

Section: Introductionmentioning

confidence: 99%

Adhesive Bonding and Corrosion Performance Investigated as a Function of Aluminum Oxide Chemistry and Adhesives

Abrahami

Hauffman

Kok³

et al. 2017

CORROSION

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Role of Tartaric Acid on the Anodizing and Corrosion Behavior of AA 2024 T3 Aluminum Alloy

Cited by 91 publications

References 11 publications

Development of a Chromium-Free Post-Anodizing Treatment Based on 2-Mercaptobenzothiazole for Corrosion Protection of AA2024T3

Development of a Chromium-Free Post-Anodizing Treatment Based on 2-Mercaptobenzothiazole for Corrosion Protection of AA2024T3

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

Adhesive Bonding and Corrosion Performance Investigated as a Function of Aluminum Oxide Chemistry and Adhesives

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