Corrosion Inhibition of Aluminum Alloy 2024-T3 by Sodium Molybdate

Lopez-Garrity, O.; Frankel, G. S.

doi:10.1149/2.044403jes

Cited by 68 publications

(38 citation statements)

References 51 publications

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“…Therefore, under the tested condition SDBS showed a mixed inhibitor effect and both the cathodic and the anodic reactions were inhibited. Similar result was recently reported by LopezGarrityz and Frankel [19] for AA 2024-T3 in naturally-aerated 0.1 M NaCl solution with Na 2 MoO 4 (pH 7.1-8.2). The results showed that molybdate provided a mixed inhibition effect at concentrations larger than 100 mM Na 2 MoO 4 .…”

Section: Tablesupporting

confidence: 91%

Evolution of the corrosion process of AA 2024-T3 in an alkaline NaCl solution with sodium dodecylbenzenesulfonate and lanthanum chloride inhibitors

Zhou

Wang

Zuo

2015

Applied Surface Science

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Section: Tablesupporting

confidence: 91%

Evolution of the corrosion process of AA 2024-T3 in an alkaline NaCl solution with sodium dodecylbenzenesulfonate and lanthanum chloride inhibitors

Zhou

Wang

Zuo

2015

Applied Surface Science

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“…49 Nevertheless, some support for this latter explanation is provided by the work of Lopez-Garrity and Frankel who observed that for aluminum alloy (AA2024-T3) in NaCl solution, molybdate may be reduced over the intermetallic particles and then subsequently reoxidized by dissolved oxygen to form polymolybdate species. 26 They estimated the reversible potential in neutral NaCl solution for the reduction of MoO 4 2− to MoO(OH) 2 at 0.1 M MoO 4 2− to be around −0.64 V vs. SCE. Considering that localized acidification may occur at active sites, this reversible potential should range from −0.40 V to −0.88 V vs. SCE for pH 5 to pH 9.…”

Section: Resultsmentioning

confidence: 99%

“…23,24 Molybdate is a non-oxidizing anodic inhibitor for Fe and Al alloys. 25,26 It has been used extensively as a corrosion inhibitor in neutral solutions such as cooling water systems, with much evidence attesting to its success in this role. 23,[27][28][29] Molybdate has also been used in paint formulations, engine coolants and metalworking fluids.…”

mentioning

confidence: 99%

Effect of Molybdate on the Passivation of Carbon Steel in Alkaline Solutions under Open-Circuit Conditions

Tan¹,

Wijesinghe

Blackwood

2016

J. Electrochem. Soc.

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The effect of molybdate on the passivation of AISI 1020 carbon steel under open-circuit conditions in pH 12.5 calcium hydroxide solutions containing chloride was investigated via electrochemical tests and surface characterization techniques. In the early stage, molybdate increased the rate of passivation, with inhibition efficiency being positive. During the later stage, after the carbon steel has passivated, precipitation of calcium molybdate over parts of the sample surface resulted in slight negative inhibition efficiency and the passive film was found to have a higher proportion of ferrous cations and a smaller thickness. However, the precipitation of a thick calcium molybdate film over the entire surface can reverse this situation, increasing the polarization resistance through a cathodic inhibition mechanism. The electrochemical and XPS results showed that regardless of its effect on the final polarization resistance, the presence of calcium molybdate precipitates led to a decrease in the total extent of carbon steel oxidation, indicating an overall beneficial effect. Molybdate was also shown to be effective against localized corrosion, with 14.6 mM molybdate sufficient in preventing passivity breakdown in pH 12.5 solution containing 564 mM chloride. Carbon steel is not a corrosion resistant alloy. However, in highly alkaline environments such as concrete, the formation of a passive oxide film on the surface reduces the corrosion rate to a very low level. 1In such environments, corrosion of carbon steel occurs mostly through two mechanisms: chloride contamination and carbonation by atmospheric CO 2 resulting in a pH drop.2-10 To counter the corrosion of carbon steel in highly alkaline environments, corrosion inhibitors can be added. Currently, calcium nitrite is being used in the construction industry as an admixed inhibitor for its set-accelerating and corrosion inhibition properties. 11Considerable research has been conducted on the inhibition of carbon steel corrosion in alkaline solutions by nitrite anions. 8,[12][13][14][15][16][17][18][19] Nitrite, being an oxidizing anodic inhibitor, oxidizes ferrous cations to ferric cations rapidly at anodic sites, which then precipitate out as ferric oxyhydroxides to repair defects in the passive film.11 Calcium nitrite works well for concrete with water to cement ratio less than 0.5 and the critical [ Despite its commercial use, concerns have been raised regarding the toxicity of calcium nitrite. 20,21 The oxidizing nature of nitrite that is essential for its corrosion inhibition effect leads to methemoglobin in humans, which is a reduction in the ability of red blood cells to transport oxygen due to Fe 2+ in hemoglobin being oxidized to Fe 3+ . This negative aspect of calcium nitrite is reflected in its being banned from use in immersed reinforced concrete structures due to toxicity and solubility issues.22 Therefore, despite calcium nitrite's commercial success as a concrete rebar inhibitor, there is an ongoing search for an alternative inhibitor for carbon st...

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“…[20][21][22] Over the years, extensive research has been conducted to find environmentally friendly alternative inhibitors that perform equal or better compared to Cr(VI)-containing inhibitors. 17,[23][24][25] Among them, inorganic inhibitors such as molybdates, 26 vanadates, 27,28 permanganates, 29 and rare-earth cations (such as cerium 30,31 and praseodymium 32 ) were investigated. Furthermore, several organic compounds, including benzotriazole, dibutylphosphate, and 2-mercaptobenzothiazole, and combinations with the inorganic inhibitors demonstrated corrosion inhibition on AA2024-T3.…”

Section: Introductionmentioning

confidence: 99%

Lithium salts as leachable corrosion inhibitors and potential replacement for hexavalent chromium in organic coatings for the protection of aluminum alloys

et al. 2016

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Lithium salts are being investigated as leachable corrosion inhibitor and potential replacement for hexavalent chromium in organic coatings. Model coatings loaded with lithium carbonate or lithium oxalate demonstrated active corrosion inhibition and the formation of a protective layer in a damaged area during neutral salt spray exposure. The present paper provides an abridged overview of the initial studies into this novel inhibitor technology for the active corrosion protection of aluminum alloys. Coating defects were investigated by microscopic techniques before and after exposure to corrosive conditions. Scanning electron microscopy analysis of cross-sections of the coating defect area demonstrated that the protective layer comprises a typical threelayered structure, which included a dense layer near the alloy surface, a porous middle layer, and a flakeshaped out layer. Potentiodynamic polarization measurements obtained with a microcapillary cell positioned in the coating defect area and electrochemical impedance spectroscopy confirmed the corrosion protective properties of these protective layers. The longterm corrosion inhibition of the lithium-based coating technology was tested in industrial coating systems.

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Corrosion Inhibition of Aluminum Alloy 2024-T3 by Sodium Molybdate

Cited by 68 publications

References 51 publications

Evolution of the corrosion process of AA 2024-T3 in an alkaline NaCl solution with sodium dodecylbenzenesulfonate and lanthanum chloride inhibitors

Evolution of the corrosion process of AA 2024-T3 in an alkaline NaCl solution with sodium dodecylbenzenesulfonate and lanthanum chloride inhibitors

Effect of Molybdate on the Passivation of Carbon Steel in Alkaline Solutions under Open-Circuit Conditions

Lithium salts as leachable corrosion inhibitors and potential replacement for hexavalent chromium in organic coatings for the protection of aluminum alloys

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