Atomic emission spectroelectrochemical investigation of the anodization of AA7050T74 aluminum alloy

Mokaddem, M.; Tardelli, Joffrey; Ogle, K.; Rocca, Emmanuel; Volovitch, P.

doi:10.1016/j.elecom.2010.11.008

Cited by 14 publications

(8 citation statements)

References 13 publications

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“…This interaction enhances the rate of diffusion of metal ions from the metal/film interface to the film/solution interface, leading to the formation of cation vacancies, which lead in turn to breakdown of the passive film. [60,61] Figures 17(a) and (b) show XRD data of alloy IV treated at 0.10 and +0.420 V vs SCE (at breakdown potential of oxide layer). The data of the oxide film formed on the alloy surface at the two potentials are compared.…”

Section: Eis Measurementsmentioning

confidence: 98%

Corrosion Study of Zinc, Nickel, and Zinc-Nickel Alloys in Alkaline Solutions by Tafel Plot and Impedance Techniques

El-Sayed

Mohran

El‐Lateef

2011

Metall Mater Trans A

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The article describes the use of Tafel plot and electrochemical impedance spectroscopy (EIS) techniques, in order to study the corrosion process of pure zinc, nickel, and synthetic Zn-Ni alloys in various concentrations (0.25 to 1 M) of KOH solution in a temperature range 298 K to 328 K (25°C to 55°C). The corrosion rate increases with increasing both concentration of KOH and temperature for all investigated electrodes. The results showed that the increase in Ni content improves the corrosion resistance and increases the barrier of activation energy, and the higher value of corrosion resistance is obtained at 10 pct Ni. The electrochemical measurements using two mentioned techniques are in good agreement with the results of microhardness in that the microhardness gradually increases with increasing Ni content in the alloy. Thus, the corrosion rate of these alloys is significantly reduced compared with that of pure zinc. It is observed that the Warburg tail at low frequency completely disappears at the applied potentials in the case of alloy IV (10 pct Ni) only. This indicates that the diffusion of Zn ion species is strongly reduced. Therefore, addition of Ni to Zn has a beneficial effect, because it leads to lower loss of anode material. The results obtained at certain positive potential (+420 mV vs SCE) exhibited that the semicircle diameter in the case of alloys is lower compared with that of pure zinc. This result means that the values of the charge transfer resistance (R ct ) in the case of alloys are decreased, due to the breakdown of the oxide layer at this potential. This behavior can be considered as an important criterion for a good battery anode, due to reactivation of the alloy surface at certain positive potential (+0.420 V vs SCE) and suppression of hydrogen gas compared with those of pure zinc.

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Section: Eis Measurementsmentioning

confidence: 98%

Corrosion Study of Zinc, Nickel, and Zinc-Nickel Alloys in Alkaline Solutions by Tafel Plot and Impedance Techniques

El-Sayed

Mohran

El‐Lateef

2011

Metall Mater Trans A

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“…In order to do this, an in situ methodology is required, as methods to date involve analysis ex situ of the pretreatment electrolyte, and analysis subsequent to the pretreatment process. The aim of the present work is to demonstrate the utility of atomic emission spectroelectrochemistry (AESEC) to monitor the kinetics of Al alloy surface pretreatment (which is possible at open circuit using AESEC) in terms of alloy dissolution, residual film formation, and particle release.35 AESEC analysis of surface treatment processes have been previously performed in the context of chromating, phosphating, degreasing or anodization; [36][37][38][39][40] however the works to date have involved only single step treatments and comparatively low dissolution rates. The novelty of the work herein as concerning AESEC is to combine two different steps with respect to electrolyte exposure, and to analyze a system experiencing significantly rapid dissolution rates.…”

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confidence: 99%

In-Situ Monitoring of Alloy Dissolution and Residual Film Formation during the Pretreatment of Al-Alloy AA2024-T3

Gharbi

Birbilis

Ogle

2016

J. Electrochem. Soc.

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The dissolution of intermetallic phases in AA 2024-T3 aluminum alloy sheet was investigated during a coating pretreatment sequence. The atomic emission spectroelectrochemistry (AESEC) technique was used to quantitatively measure the dissolution rates of individual alloying elements during a complete pretreatment sequence. The results demonstrate the significant selective dissolution of Al in 1.25 M NaOH, leading to the enrichment of alloying elements such as Cu. Subsequent 2.8 M HNO 3 treatment contributes toward dissolving the excess residual layer and passivates the alloy matrix, however the presence of a residual Cu layer at the alloy surface was evidenced. The real-time alloy dissolution profiles are presented herein, and discussed in the context of the surface morphology via microscopy. The surface treatment of aluminum (Al) alloys is required prior to the application of corrosion protective coatings.1 Protective coatings are essential in order to allow microstructurally complex alloys, which are nominally prone to localized corrosion, 2-7 to be used in service; particularly in aerospace applications.8 Coatings for Al-alloys are nominally multilayered coating 'systems', with the first coating being a chemical conversion coating. The surface treatment prior to this chemical conversion coating is as important as the coating itself, since it determines the efficacy of any conversion coating.1,9 Such surface treatment, often termed pre-treatment, generally involves alkaline etching and acid pickling. Sodium hydroxide (NaOH) is often used to remove any organic residue and also to remove several micrometers of the alloy surface.10 This is followed by acid pickling, usually performed in nitric acid (HNO 3 ) to remove any residue, products, films, or particles remnant from -or caused by -the prior alkaline step. The purpose of surface pretreatment is to provide a chemically homogeneous surface chemistry prior to subsequent coating processes. The chemical heterogeneity of the Al-alloy surfaces is due to the many alloying elements present, such as copper (Cu), magnesium (Mg), iron (Fe) and manganese (Mn). Cu improves the mechanical properties of AA 2024-T3 11 however decreases corrosion resistance due to stimulating various phases which serve as local electrochemical entities, in addition to raising the alloy potential to above the pitting potential of the matrix phase 7,[12][13][14][15][16] . This element is considered to be a major contributor to the localized corrosion of Al 2,17,18 and its elimination is one of primary goals of aluminum alloy surface pretreatment.Knowledge of the elementary dissolution kinetics during the pretreatment sequence would be very useful for the development of surface treatment formulations, however, this information is often very difficult to obtain. In situ monitoring of the corrosion reactions during surface treatment is difficult as the corrosion reactions occur within a relatively short time with large reaction rates and may involve extensive precipitation of dissolution products a...

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“…1,2 Anodization is a convenient and important method of oxide film formation owing to low cost, flexibility and easiness. [3][4][5][6][7] There are several anodization processes that are currently used: conventional anodic oxidation (potentiostatic or galvanostatic) and plasma electrolytic oxidation (PEO). [3][4][5]7 The conventional anodization is well studied and allows growing oxide films of controlled thickness and quality.…”

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confidence: 99%

“…[3][4][5]7 The conventional anodization is well studied and allows growing oxide films of controlled thickness and quality. 5,7 The films can be partially hydrated. 5 The other method, PEO, which utilizes potentials above the breakdown voltage of the oxide film growing on the anode surface, makes possible to prepare well adherent, hard, ceramic-like coatings.…”

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confidence: 99%

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Aluminum Anodization in Deionized Water as Electrolyte

Lisenkov

Poznyak

Zheludkevich

et al. 2016

J. Electrochem. Soc.

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Thin oxide films were prepared electrochemically on the aluminum surface using the high-voltage discharge and potentiostatic methods in deionized water as an electrolyte. The growth of continuous films occurred only at potentials lower than the breakdown potential. The films obtained by the discharge method are more uniform and can grow to a higher thickness in comparison to those formed by the potentiostatic mode, as demonstrated by electrochemical impedance spectroscopy (EIS), transmission electron microscopy (TEM), and scanning Kelvin probe force microscopy (SKPFM). The data herein obtained can be used as a reference to understand better the properties of the films produced in conventional electrolytes where apart from water other species are present.

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Atomic emission spectroelectrochemical investigation of the anodization of AA7050T74 aluminum alloy

Cited by 14 publications

References 13 publications

Corrosion Study of Zinc, Nickel, and Zinc-Nickel Alloys in Alkaline Solutions by Tafel Plot and Impedance Techniques

Corrosion Study of Zinc, Nickel, and Zinc-Nickel Alloys in Alkaline Solutions by Tafel Plot and Impedance Techniques

In-Situ Monitoring of Alloy Dissolution and Residual Film Formation during the Pretreatment of Al-Alloy AA2024-T3

Aluminum Anodization in Deionized Water as Electrolyte

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