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Cross-sectional characterization of the conversion layer formed on AA2024-T3 by a lithium-leaching coating Vrije Universiteit Brussel

Ali Kosari, Peter Visser, Frans Tichelaar, S. Eswara, J. N. Audinot, T. Wirtz, H. Zandbergen, Herman Terryn, Johannes M. C. Mol

This work focuses on the cross-sectional characterization of the protective conversion layer formed on AA2024-T3 by lithium-leaching from a polyurethane coating in a corrosive environment. The layer shows a multi-layered arrangement comprising nanoscopic local phases. Transmission electron microscopy (TEM) and complementary high-resolution secondary ion mass spectroscopy (SIMS) were employed to observe the cross-sections of the entire layer ...

On the importance of irreversibility of corrosion inhibitors for active coating protection of AA2024-T3 Vrije Universiteit Brussel

Peter Visser, Herman Terryn, Johannes M. C. Mol

Inhibitor leaching, fast, effective and irreversible passivation are essential for active protective coatings to protect aluminium alloys. This study presents the comparison of the active protective properties of lithium carbonate and two organic corrosion inhibitors, benzotriazole and 2-mercaptobenzothiazole, on aluminium alloy 2024-T3 with a special focus on the irreversibility of the inhibition. A combined approach of electrochemical ...

Mechanism of Passive Layer Formation on AA2024-T3 from Alkaline Lithium Carbonate Solutions in the Presence of Sodium Chloride Vrije Universiteit Brussel

Peter Visser, Yaiza Gonzalez-Garcia, Johannes M. C. Mol, Herman Terryn

This study focuses on the elucidation of the formation mechanism of passive layers on AA2024-T3 during the exposure to alkaline lithium carbonate solutions in the presence of sodium chloride. Under controlled conditions, in an electrochemical cell, a protective layer was generated comprising an amorphous inner layer and a crystalline outer-layer. In order to resolve the formation mechanism, the layers were characterized using surface ...

The corrosion protection of AA2024-T3 aluminium alloy by leaching of lithium-containing salts from organic coatings Vrije Universiteit Brussel

Peter Visser, Yanwen Liu, Xiaorong Zhou, Teruo Hashimoto, George E. Thompson, Stuart B. Lyon, Leendert G. J. van der Ven, Arjan J. M. C. Mol, Herman Terryn
Lithium carbonate and lithium oxalate were incorporated as leachable corrosion inhibitors in model organic coatings for the protection of AA2024-T3. The coated samples were artificially damaged with a scribe. It was found that the lithium-salts are able to leach from the organic coating and form a protective layer in the scribe on AA2024-T3 under neutral salt spray conditions. The present paper shows the first observation and analysis of these ...

Evolution of dislocation patterns inside the plastic zone introduced by fatigue in an aged aluminium alloy AA2024-T3 KU Leuven

Eric Breitbarth, Stefan Zaefferer, Fady Archie, Michael Besel, Dierk Raabe, Guillermo Requena
© 2018 Elsevier B.V. The formation of dislocations patterns within the plastic zone ahead of a crack tip introduced by fatigue loading in AA2024-T3 sheets is studied by electron channelling contrast imaging (ECCI) and electron backscatter diffraction (EBSD). The aim lies in correlating local plastic effects at grain level with digital image correlation (DIC) results obtained at coarser resolution. While dislocation patterns are observed already ...

Bending properties of locally laser heat treated AA2024-T3 aluminium alloy KU Leuven

Amirahmad Mohammadi, Hans Vanhove, Albert Van Bael, Joost Duflou
The bending properties of AA2024-T3 aluminium alloy after localized laser assisted softening have been studied and compared to untreated material. Single and multi-path laser scanning strategies are applied for achieving a predictable and minimized springback. Process parameters for softening have been chosen based on FE modeling. In order to investigate the softening, and to characterize the size of this softened region, hardness measurements ...

Validation of a fast scanning technique for corrosion inhibitor selection: influence of cross-contamination on AA2024-T3 Vrije Universiteit Brussel

S.j. Garcia, P. Corrigan, M. Glenn, Herman Terryn, S. Hardin
Aiming the assessment of novel, environmentally friendly corrosion inhibitors that can substitute chromate-based ones, this work describes and validates a method for the rapid screening of water-soluble inhibitors. The technique involves a fixed potential being applied between identical electrodes while immersed in an inhibitive solution and with the absence of a reference electrode. The current flowing between the electrodes is measured and the ...

The chemical throwing power of lithium-based inhibitors from organic coatings on AA2024-T3 Vrije Universiteit Brussel

Peter Visser, Kristof Marcoen, Gustavo F. Trindade, Marie-Laure Abel, John F. Watts, Tom Hauffman, Johannes M. C. Mol, Herman Terryn

Chemical throwing power, being the distance over which an inhibitor is able to protect a defect effectively, is an important parameter for active protective coatings. This study investigates the chemical throwing power of lithium-based leachable corrosion inhibitors exhibiting different leaching kinetics, from coatings at different inhibitor loading concentrations. The results demonstrate that Li-salt loaded coatings provide corrosion ...

Compositional study of a corrosion protective layer formed by leachable lithium salts in a coating defect on AA2024-T3 aluminium alloys Vrije Universiteit Brussel

Kristof Marcoen, Peter Visser, Gustavo F. Trindade, Marie-Laure Abel, John F. Watts, Johannes M. C. Mol, Herman Terryn, Tom Hauffman

Organic primer coatings loaded with environmentally harmful Cr(VI) corrosion inhibitive pigments still play an important role in corrosion protection of aluminium alloys for the aerospace industry. A potential “green” alternative coating system has recently been developed, loaded with lithium salt corrosion inhibitors. Under exposure to neutral salt spray, lithium salts leach from the organic coating into coating defects to induce the ...