Zirconium Oxide Coating on Anodized Aluminum by the Sol‐Gel Process Combined with Ultraviolet Irradiation at Ambient Temperature

Hirai, Shinji; Shimakage, Kazuyoshi; Sekiguchi, Motoi; Wada, Kenji; Nukui, Akihiko

doi:10.1111/j.1151-2916.1999.tb02033.x

Cited by 47 publications

(16 citation statements)

References 16 publications

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“…7 UV radiation can induce additional densification at low temperature. 36 Coatings prepared on aluminum from zirconium tetra-n-butoxide, anhydrous ethanol and diethylene glycol and cured by UV irradiation at ambient temperature, showed better alkaline corrosion resistance (as measured by electromotive force measurements) than those prepared by conventional heat-treatment at 300…”

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confidence: 99%

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Corrosion Properties of UV Cured Hybrid Sol-Gel Coatings on AA7075-T6 Determined under Simulated Aircraft Conditions

Rodič

Milošev

2014

J. Electrochem. Soc.

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Novel hybrid sol-gel coatings have been developed for aluminum alloys as an alternative to the restricted use of chromate conversion coatings. They were prepared from two individual sols: zirconium tetrapropoxide (ZTP) and methacrylic acid (MAA) were added to siloxane sol prepared by mixing tetraethyl orthosilicate (TEOS) and organically modified silica 3-methacryloxypropyl trimethoxysilane (MAPTMS). The mixtures were deposited on alloy AA7075-T6 substrate and cured in air under daylight at room temperature or at 100 • C without the addition of photo-initiator. Different molar ratios of ZTP and MAA were investigated, as well as the effects of curing temperature and aging time. The corrosion behavior of the coated alloy was examined by electrochemical potentiodynamic measurements and six-month immersion tests in Harrison's solution, which simulates aircraft conditions. The coatings provided excellent corrosion protection in the atmospheric region and at high anodic potentials up to 7 V, as well as effective protection during long-term immersion. Curing under daylight improved the corrosion properties compared to curing in the dark. The corrosion behavior of synthesized coatings was compared to standard chromate coatings, including primer and topcoat. The morphology of the coatings was analyzed by scanning electron microscopy, and their adhesion to aluminum alloy surface measured using the X-cross cut test. Chromate conversion coatings (CCCs) have been used successfully for corrosion protection of aluminum alloys.1-3 The formation of CCCs involves the reduction of the oxy chromium species and consequent oxidation of aluminum. Stable, hydrophobic Cr(III) oxide/hydroxide film thus formed contains residual, releasable hexavalent chromium which maintains the active inhibition of the film. Due to rapid adsorption and passivation at the intermetallic sites, the main role of the inhibition process by Cr 6+ is to limit the oxygen reduction on intermetallics, which are the main initiation sites for localized corrosion of aluminum alloys.2,3 Further, the susceptibility to pit initiation is reduced, because the Cr 6+ compounds are adsorbed to aluminum oxide, minimizing the susceptibility to adsorption of chloride. Despite these excellent characteristics, the use of CCCs is restricted because of their hazards for the environment and humans. New alternatives include a broad spectrum of possibilities -from various cerium, molybdenum and organic inhibitors, barrier coatings including plasma deposited, sol-gel and electrodeposited coatings, to conducting polymers.3-6 An alternative yielding highly effective and long lasting protection that is fully comparable to CCCs is still to be found.Over the last decade, inorganic-organic (hybrid) sol-gel coatings have been studied as important alternatives to CCCs.7-13 They combine the properties of inorganic (scratch resistance, durability, adhesion, chemical and thermal stability) and organic (density, flexibility and functional capability) components. Of the one-component hybrid coatings...

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confidence: 99%

“…• C. 36 This was ascribed to the elimination of residual organic components, which was accelerated by UV irradiation, and to the densification of the coating layer.…”

mentioning

confidence: 99%

Corrosion Properties of UV Cured Hybrid Sol-Gel Coatings on AA7075-T6 Determined under Simulated Aircraft Conditions

Rodič

Milošev

2014

J. Electrochem. Soc.

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“…This bond has not been observed in our previous studies [9]. According to the references [23][24][25] the appearance of Zr-O-C bonds is due to the dissociation of the Zr-O-Si bonds after pyrolysis at 400…”

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confidence: 81%

Organic-inorganic hybrid materials based on N=C=O functionalised silan modified with titanium and zirconium

et al. 2005

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This work investigates the influence of the precursor trimethylsilil isocyanate on the sol-gel synthesis of hybrid materials. The obtained Si-O-C-N network is additionally modified by titanium and zirconium alcoxypropoxides in the range of 10 to 30 wt.%. The structure of the obtained hybrid materials before and after pyrolysis up to 1100 • C was investigated by methods of XRD, FTIR and 29 Si MAS NMR. We established that the hybrid structure was stable up to 600 • C based on IR study. The structural transformation of the hybrid materials into oxycarbonitrogen system started at 800 • C. The network of the hybrids modified by titanium remained stable and amorphous up to the final temperature of the pyrolysis (1100 • C) compared to the gels modified by more than 10 wt.% Zr. It was confirmed by XRD analysis that the last mentioned are nanocomposite materials, built from carbooxynitrogen vitreous matrix and ZrO 2 -nanocrystals (tetragonal). The NMR method verified the presence of heterometallic bonds (Si-O-Ti and Si-O-Zr) and Q 4 , ZrQ 3 or TiQ 3 , NSiO 3 and D structural units in the gels.

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“…Elimination of the residual organic components in the sol-gel coating film results from dissociation of residual organic molecules because of photo-excitation ; densification of the coating film is induced [24]. We adopted UV irradiation at ambient temperatures instead of heat treatment to eliminate residual organic chemicals in the coated calcium phosphate and to densify the coated calcium phosphate.…”

Section: Resultsmentioning

confidence: 99%

“…The coated silk fabrics were treated using UVirradiation at an ambient temperature for 2 h under a flow of N2 and the samples were cooled by refrigeration at 265 K during the treatment. Then a UV-irradiation was conducted using the same apparatus as that used in a previous report [24]. A U-shaped low-pressure mercury lamp of 500 W was used.…”

Section: Sol-gel Coating Processmentioning

confidence: 99%

Evaluation of Calcium Phosphate-Coated Silk Fabric Produced by Sol-Gel Processing as a Wound Cover Material

et al. 2009

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Zirconium Oxide Coating on Anodized Aluminum by the Sol‐Gel Process Combined with Ultraviolet Irradiation at Ambient Temperature

Cited by 47 publications

References 16 publications

Corrosion Properties of UV Cured Hybrid Sol-Gel Coatings on AA7075-T6 Determined under Simulated Aircraft Conditions

Corrosion Properties of UV Cured Hybrid Sol-Gel Coatings on AA7075-T6 Determined under Simulated Aircraft Conditions

Organic-inorganic hybrid materials based on N=C=O functionalised silan modified with titanium and zirconium

Evaluation of Calcium Phosphate-Coated Silk Fabric Produced by Sol-Gel Processing as a Wound Cover Material

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