Effect of native air-formed oxidation on the corrosion behavior of AA 7075 aluminum alloys

Ryl, Jacek; Wysocka, Joanna; Jarzynka, Magdalena; Zieliński, A.; Orlikowski, Juliusz; Darowicki, Kazimierz

doi:10.1016/j.corsci.2014.06.022

Cited by 67 publications

(37 citation statements)

References 32 publications

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“…In dry atmosphere, the surface of metals is usually covered by a dense and protective (passive) metal-oxide layer which impedes corrosion reactions [67][68][69]. It has been reported that the surface of Mg 2 Si can form a passive oxide layer [70][71][72], which grows with time and results in an enhanced electrochemical nobility in both ambient air and corrosive environments [71]. The investigated sample was exposed to laboratory air for 2 months, allowing the formation of oxide/hydroxide on the surface (aging).…”

Section: Discussionmentioning

confidence: 99%

Volta Potential Evolution of Intermetallics in Aluminum Alloy Microstructure Under Thin Aqueous Adlayers: A combined DFT and Experimental Study

et al. 2018

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In this work, first-principle density functional theory (DFT) was used to calculate the work function and Volta potential differences between aluminum alloy matrix and two intermetallic phases (Mg 2 Si and Al 2 Cu) with varying surface terminations as a function of adhering monolayers (ML) of water. The calculated data were compared with experimental local Volta potential data obtained by the scanning Kelvin probe force microscopy (SKPFM) on a commercial aluminum alloy AA6063-T5 in atmospheric environments with varying relative humidity (RH). The calculations suggest that the surface termination has a major effect on the magnitude and polarity of the Volta potential of both intermetallic phases (IMP's). The Volta potential difference between the IMP's and the aluminum matrix decreases when the surface is gradually covered by water molecules, and may further change as a function of adhering ML's of water. This can lead to nobility inversions of the IMP's relative to the aluminum matrix. The measured Volta potential difference between both IMP's and their neighboring matrix is dependent on RH. Natural oxidation in ambient indoor air for 2 months led to a nobility inversion of the IMP's with respect to the aluminum matrix, with the intermetallics showing anodic nature already in dry condition. The anodic nature of Al 2 Cu remained with the introduction of RH, whereas Mg 2 Si became cathodic at high RH, presumably due to de-alloying of Mg and oxide dissolution. The DFT calculations predicted an anodic character of both IMP's in reference to the oxidized aluminum matrix, being in good agreement with the SKPFM data. The DFT and SKPFM data were discussed in light of understanding localized corrosion of aluminum alloys under conditions akin to atmospheric exposure.

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Section: Discussionmentioning

confidence: 99%

Volta Potential Evolution of Intermetallics in Aluminum Alloy Microstructure Under Thin Aqueous Adlayers: A combined DFT and Experimental Study

et al. 2018

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“…The substantial increase in magnitude of the semi-circle loop results in the decrease of the active surface of the coating and the formation of a protective layer simultaneously. This phenomenon is attributed to the deposition of corrosion products, which block the defects due to a reaction between the coating surface and the ions (chloride and carbonate) available in the solution [41]. After 384 h (Figure 8a) of exposure, the enlargement of the semi-circle loop is the highest, which means the formation of passive film is uniform, dense and very protective, and that this film exhibited more resistance to electrochemical reaction.…”

Section: Electrochemical Impedance Spectroscopy (Eis) Evaluation Of Cmentioning

confidence: 87%

Corrosion Resistance Properties of Aluminum Coating Applied by Arc Thermal Metal Spray in SAE J2334 Solution with Exposure Periods

Lee

Singh

Ismail

et al. 2016

Metals

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Arc thermal metal spray coating provides excellent corrosion, erosion and wear resistance to steel substrates. This paper incorporates some results of aluminum coating applied by this method on plain carbon steel. Thereafter, coated panels were exposed to an environment known to form stable corrosion products with aluminum. The coated panels were immersed in Society of Automotive Engineers (SAE) J2334 for different periods of time. This solution consists of an aqueous solution of NaCl, CaCl 2 and NaHCO 3 . Various electrochemical techniques, i.e., corrosion potential-time, electrochemical impedance spectroscopy (EIS) and the potentiodynamic were used to determine the performance of stimulants in improving the properties of the coating. EIS studies revealed the kinetics and mechanism of corrosion and potentiodynamic attributed the formation of a passive film, which stifles the penetration of aggressive ions towards the substrate. The corrosion products that formed on the coating surface, identified using Raman spectroscopy, were Dawsonite (NaAlCO 3 (OH) 2 ) and Al(OH) 3 . These compounds of aluminum are very sparingly soluble in aqueous solution and protect the substrate from pitting and uniform corrosion. The morphology and composition of corrosion products determined by scanning electron microscopy and energy dispersive X-ray analyses indicated that the environment plays a decisive role in improving the corrosion resistance of aluminum coating.

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“…Besides, various modeling studies have indicated that a localized pH (near cathodic particle) approaching 10 is possible for a neutral solution [76,77]. And, it is widely accepted that aluminum and its solid solutions dissolve readily at elevated pH values (>9) [7,53,78,79]. Therefore, the localized alkalization caused by oxygen reduction leads to the breakdown of passive film and the active dissolution of aluminum metal matrix near the cathodic particles; and thus pits initiate and propagate.…”

Section: Effects Of Particles Microchemistry On Pittingmentioning

confidence: 97%

“…10a). Compared to R ct , the R hf was relatively small, and was far smaller than the resistance of passive film on aluminum alloys [53,54]. In fact, the R hf was the parallel resistance of passive film (on uncorroded surface) and corrosion products on pit site (or solution resistance in pits cavity), its value was determined by the smaller one in the parallel connection, i.e., determined by the resistance on pit initiation site; therefore, if the alloys underwent pitting corrosion, the R hf would be relatively small.…”

Section: Eis Measurementmentioning

confidence: 97%

Pitting corrosion of naturally aged AA 7075 aluminum alloys with bimodal grain size

Tian

Wang

et al. 2016

Corrosion Science

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Effect of native air-formed oxidation on the corrosion behavior of AA 7075 aluminum alloys

Cited by 67 publications

References 32 publications

Volta Potential Evolution of Intermetallics in Aluminum Alloy Microstructure Under Thin Aqueous Adlayers: A combined DFT and Experimental Study

Volta Potential Evolution of Intermetallics in Aluminum Alloy Microstructure Under Thin Aqueous Adlayers: A combined DFT and Experimental Study

Corrosion Resistance Properties of Aluminum Coating Applied by Arc Thermal Metal Spray in SAE J2334 Solution with Exposure Periods

Pitting corrosion of naturally aged AA 7075 aluminum alloys with bimodal grain size

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