Effect of Surface Pretreatment on the Underpaint Corrosion of AA2024-T3 at Various Temperatures

Little, D. A.; Jakab, M. A.; Scully, John R.

doi:10.5006/1.3280663

Cited by 29 publications

(27 citation statements)

References 59 publications

(131 reference statements)

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“…A three-electrode cell was used for all electrochemical measurements, with a Solarton described elsewhere [15,16] the Cu(0)/Cu(I) peak in the last scan, i.e. in step (vi), were used to determine the relative amounts of electroactive copper [15,16].…”

Section: Electrochemical Measurementsmentioning

confidence: 99%

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Influence of pre- and post-treatments on formation of a trivalent chromium conversion coating on AA2024 alloy

Němcová

Walton

et al. 2016

Thin Solid Films

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A comparison has been made of the influence of two alloy pre-treatments and two coating post-treatments on the formation, composition and corrosion protection of a trivalent chromium conversion coating on AA 2024-T351 alloy. The investigation employed analytical electron microscopies, ion beam analysis, X-ray photoelectron spectroscopy (XPS) and electrochemical tests. The pre-treatments used alkaline etching followed by de-oxidizing in either nitric acid or a commercial de-oxidizer. The conversion coatings were formed in SurTec 650 chromitAL and revealed two-layers, comprising an inner aluminium-rich layer and an outer chromium-and zirconium-rich layer, with a Cr:Zr atomic ratio in the range ~0.73 -0.93. XPS indicated a chromium-enriched near-surface region that contained ~2 at.% of Cr (VI) species. Potentiodynamic polarization and electrochemical impedance spectroscopy revealed an improved corrosion protection for a pre-treatment that left copperrich sponges, probably de-alloyed S phase, and fewer residues of other intermetallic particles on the alloy surface. Post-coating immersion treatments in deionized water at 20 °C or 40 °C resulted in a significant difference in the zirconium species in the region adjacent to the coating surface that is accessible to XPS, with oxide and hydroxide dominating at the respective temperatures.

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Section: Electrochemical Measurementsmentioning

confidence: 99%

“…in step (vi), were used to determine the relative amounts of electroactive copper [15,16]. Figure 1 shows scanning electron micrographs of the pre-treated alloy surfaces.…”

Section: Electrochemical Measurementsmentioning

confidence: 99%

Influence of pre- and post-treatments on formation of a trivalent chromium conversion coating on AA2024 alloy

Němcová

Walton

et al. 2016

Thin Solid Films

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“…The atomistic origin of these events and nanoscale pitting mechanism remain an active area of study [10,11]. Most corrosion models at continuum or atomistic scale focus on either ion adsorption or transport through passive oxides [12][13][14]. While the continuum scale kinetic models such as the point defect models [15][16][17] can capture the description of the growth and breakdown of the passive oxide film, the atomistic details involving bond formation and bond breakage in a reactive aqueous environment cannot be elucidated.…”

Section: Introductionmentioning

confidence: 99%

Strong correlations between structural order and passive state at water–copper oxide interfaces

Narayanan

Deshmukh

Sankaranarayanan

et al. 2015

Electrochimica Acta

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A B S T R A C TA fundamental understanding of coupled electrochemical processes including metal dissolution, structural evolution and solvation dynamics at the atomic level is of interest to corrosion research and electrochemistry in general. Using molecular dynamics (MD) simulations based on a reactive force field (ReaxFF), we evaluate the impact of non-stoichiometry in a model system of copper oxide passive films on the local fluctuation of the chloride ion density and structure and dynamics of interfacial water layers. We investigate (a) the interplay of oxygen content in the passive oxide film and the solvation dynamics of halide ions in the aqueous interfacial layers during breakdown of the oxide film, and (b) their combined effects on the dissolution kinetics of copper and adsorption of chloride ions on the copper-oxide surface. We demonstrate that the solvation behavior, particularly near the oxide/aqueous medium interface, is strongly correlated with the interfacial chloride ion concentration, which in turn is influenced by the oxygen stoichiometry in the passive oxide. Residence probability and hydrogen-bond correlations show that water present in the aqueous media forms ordered layers on oxide films with high oxygen content; and as the oxygen content is reduced, this order gets disrupted due to increased chloride ion adsorption. Interfacial molecular order is, therefore, strongly correlated with stoichiometry of the passive oxide film.Published by Elsevier Ltd.

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“…Filiform corrosion typically occurs at ambient temperatures and relative humidity (RH) range of 65-90%. The solution in the anodic active head of a filament is deaerated and acidic, with a pH range of 1-4, while the cathodic filament tail is aerated and alkaline [4]. The potential difference between the head and the tail can be up to 0.4 V, and this differential is the driving force for filiform corrosion [1].…”

Section: Introductionmentioning

confidence: 99%

Chromate replacement in coatings for corrosion protection of aerospace aluminium alloys

Markley

Mardel

Hughés

et al. 2011

Materials & Corrosion

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Mixed rare earth organophosphates have been investigated as potential corrosion inhibitors for AA2024-T3 with the aim of replacing chromate-based technologies. Cerium diphenyl phosphate (Ce(dpp) 3 ) and mischmetal diphenyl phosphate (Mm(dpp) 3 ) were added to epoxy coatings applied to AA2024-T3 panels and they were effective in reducing the amount and rate of filiform corrosion in high humidity conditions. Ce(dpp) 3 was the most effective and characterisation of the coating formulations showed approximately a factor of 5 reduction in both the number of corrosion filaments initiated as well as the length of these. Mm(dpp) 3 appeared to reduce the corrosion growth rate by a factor of 2 although it was the more effective inhibitor in solution studies. Spectroscopic characterisation of the coatings indicated that the cerium based inhibitor may disrupt network formation in the epoxy thus resulting in a coating that absorbed more water and allowed greater solubilisation of the corrosion inhibiting compound.

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Effect of Surface Pretreatment on the Underpaint Corrosion of AA2024-T3 at Various Temperatures

Abstract: The effects of surface pretreatment on the rate of scribe-creep caused by underpaint corrosion on coated AA2024-T3 (UNS

Cited by 29 publications

References 59 publications

Influence of pre- and post-treatments on formation of a trivalent chromium conversion coating on AA2024 alloy

Influence of pre- and post-treatments on formation of a trivalent chromium conversion coating on AA2024 alloy

Strong correlations between structural order and passive state at water–copper oxide interfaces

Chromate replacement in coatings for corrosion protection of aerospace aluminium alloys

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