Potentiodynamic evaluation of sol–gel coatings with inorganic inhibitors

Voevodin, N.N.; Grebasch, N.T; Soto, W.S; Arnold, F. E.; Donley, M.S.

doi:10.1016/s0257-8972(01)00999-9

Cited by 153 publications

(61 citation statements)

References 4 publications

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“…Another challenging aspect associated with sol-gel coatings is the lack of active corrosion protection. To overcome this limitation different types of corrosion inhibitors have been incorporated into sol-gel coatings with the aim to confer active protection [5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Corrosion protection of AA2024 by sol–gel coatings modified with MBT-loaded polyurea microcapsules

Maia

Yasakau

Carneiro

et al. 2016

Chemical Engineering Journal

109

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In this work we report the synthesis of polyurea microcapsules loaded with corrosion inhibitor 2-mercaptobenzothiazole (MBT) for corrosion protection of 2024 aluminum alloy. The microcapsules were prepared by interfacial polycondensation. The resulting capsules exhibit spherical shape, with diameter ranging between 100 nm and 2 µm. The loading content of MBT was found to be 5 wt% and release studies showed that MBT is preferentially released under acidic and alkaline conditions and follows the Fickian diffusion model. This pH dependency seems suitable for protection of metallic alloys where corrosion processes are accompanied by local pH changes. Furthermore, the microcapsules were added to a hybrid sol-gel coating and its performance assessed by electrochemical and accelerated standard tests. The results obtained indicate that capsules loaded with MBT do not affect negatively the barrier properties of sol-gel coatings, and contribute for the enhancement of adhesion of coatings to the metallic substrate. More relevant, these additives impart active corrosion protection suppressing corrosion activity at defect sites, which opens prospects for application of polyurea microcapsules as additives for high-performance coatings.

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Section: Introductionmentioning

confidence: 99%

Corrosion protection of AA2024 by sol–gel coatings modified with MBT-loaded polyurea microcapsules

Maia

Yasakau

Carneiro

et al. 2016

Chemical Engineering Journal

109

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“…The current state of the art for protecting aluminium alloys involves the use of hexavalent chromium technology in the form of conversion coatings and pigmented anticorrosion primers [1]. However in the interest of human health [2,3] and environmental concerns, alternative solutions are being pursued. For engineering applications organic polymers (polyesters, polyamides, alkyds, and polyurethane) [4], conductive polymers (polyaniline and polypyrrole) [5] and sol-gel derived organicinorganic hybrid materials have emerged as promising Cr 6+ alternatives [6].…”

Section: Introductionmentioning

confidence: 99%

“…Some United States Air Force studies investigated various routes towards improving coating performance including the use of rare-earth metal salts [18], amine cross-linkers [19][20][21], supramolecular inclusion and organic corrosion inhibitors [22,23].…”

Section: Introductionmentioning

confidence: 99%

Corrosion protection of AA 2024-T3 aluminium alloys using 3, 4-diaminobenzoic acid chelated zirconium–silane hybrid sol–gels

Varma

Colreavy

Cassidy³

et al. 2010

Thin Solid Films

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Organic-inorganic polymers formed by hydrolysis/condensation reactions of alkoxide precursors, such as organically modified silanes (Ormosils) are used for several industrial applications such as electronic, optical and protective anticorrosion coatings. Such materials possess superior chemical stability, physical strength and scratch resistance characteristics when compared to organic polymers. Further performance improvement can be achieved through the incorporation of zirconium and titanium based nanoparticles, also formed through from precursors via the sol-gel process. However due to the inherent reactivity differences of the above precursors, they must be hydrolysed separately before being combined for final condensation. Zirconium precursors are commonly chelated using acetic acid or acetyl acetonate prior to hydrolysis, to lower the hydrolysis rate. In this body of work, 3,4-diaminobenzoic acid (DABA) and acetyl acetonate (acac) were compared as chelating ligands for controlling the hydrolysis reactions of zirconium n-propoxide to form nanoparticles within a silane sol matrix. The sols were applied as coatings on aerospace grade aluminium alloy AA 2024-T3 and characterised by physical, spectroscopical, microscopical, electrochemical and calorimetric techniques. The electrochemical properties of the coatings, as characterised by EIS and PDS, correlated with neutral salt spray evaluations confirming that the use of DABA as a chelating ligand significantly improved the coating performance when compared to the traditional diketone ligand. The data indicates the anticorrosion properties of the nitrogen rich chelate have a key role in protecting the alloy through the formation of smaller zirconium nanoparticles, thus improving the polymer network stability.

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“…Until recently the current state of art for protecting aluminium alloys involved the use of hexavalent chromium technology [1]. However in the interest of human health [2,3] and environmental concerns, alternative solutions are being pursued. For engineering applications organic polymers (polyesters, polyamides, alkyds, polyurethane) [4], con-ductive polymers (polyaniline and polypyrrole) [4,5] and sol-gel derived organic-inorganic hybrid materials have emerged as a promising Cr 6+ alternatives [6].…”

Section: Introductionmentioning

confidence: 99%

“…However the combination of ormosils and zirconium chemistries were found to improve the coatings performance considerably [17], especially alkali resistance. Some United States Air Force studies investigated several routes towards improving performance including the use of rare-earth metal salts [18], amine cross-linkers [19][20][21], supramolecular inclusion and organic inhibitors [22,23]. Similar approaches were investigated by Ferreira's group in Portugal which concentrated on epoxy functionalised silane-zirconium systems by adding cerium [24], azole based organic inhibitors in host molecules [25,26] and bis-silanes [27].…”

Section: Introductionmentioning

confidence: 99%

Effect of organic chelates on the performance of hybrid sol–gel coated AA 2024-T3 aluminium alloys

Varma

Colreavy

Cassidy³

et al. 2009

Progress in Organic Coatings

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a b s t r a c tSol-gels are organic-inorganic polymers formed by hydrolysis/condensation reactions of alkoxide precursors, primarily silanes, which have found applications as electronic, optical and protective coatings. These coatings possess important characteristics such as chemical stability, physical strength and scratch resistance. Further performance improvement is achieved through the incorporation of zirconium and titanium based nanoparticles, also formed through the sol-gel process. However due to the inherent difference in the reactivity of the precursors, the hydrolysis of each precursor must be carried out separately before being combined for final condensation. Zirconium precursors are commonly chelated using acetic acids, prior to hydrolysis, to lower the hydrolysis rate.In this body of work various ligands such as organic acids, acetyl acetone (AcAc) and 2,2 -bipyridine (Bipy) were used to control the zirconium hydrolysis reaction and form nanoparticles within the silane sol matrix.Nanoparticle modified coatings formed from the silane sol on AA 2024-T3 aluminium were characterised spectroscopically, electrochemically and calorimetrically to evaluate the potential effect of the different chelates on the final film properties while neutral salt spray tests were performed to study their anti-corrosion performance. Results indicate that the acid ligand modified coatings provided the best performance followed by AcAc, while Bipy was the poorest. In all cases the zirconium nanoparticle improved the protective properties of the sol-gel coating.

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Potentiodynamic evaluation of sol–gel coatings with inorganic inhibitors

Cited by 153 publications

References 4 publications

Corrosion protection of AA2024 by sol–gel coatings modified with MBT-loaded polyurea microcapsules

Corrosion protection of AA2024 by sol–gel coatings modified with MBT-loaded polyurea microcapsules

Corrosion protection of AA 2024-T3 aluminium alloys using 3, 4-diaminobenzoic acid chelated zirconium–silane hybrid sol–gels

Effect of organic chelates on the performance of hybrid sol–gel coated AA 2024-T3 aluminium alloys

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