In Situ Formation of Anticorrosive Mg-Al Layered Double Hydroxide-Containing Magnesium Hydroxide Film on Magnesium Alloy by Steam Coating

Ishizaki, Takahiro; Chiba, Satoshi; Suzuki, Hikaru

doi:10.1149/2.006305eel

Cited by 36 publications

(16 citation statements)

References 17 publications

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“…Steam coating technology was originally developed to improve the corrosion resistance of Mg alloys [20][21][22]. Steam coating technology produces a dense film on the surface of a metal using steam, which is produced in a pressure vessel, i.e., an autoclave.…”

Section: Introductionmentioning

confidence: 99%

“…The type of metal determines the resulting layer. In the case of AZ31 magnesium alloy, the film which forms on the substrate as a result of the steam coating consists of Mg(OH) 2 and Mg-Al LDH [20,21]. In contrast, in AZX612 magnesium alloy, AlOOH is simultaneously formed with the Mg(OH) 2 and Mg-Al LDH, due to the different compositions of solute elements in the alloy [23].…”

Section: Introductionmentioning

confidence: 99%

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Formation of Anticorrosive Film for Suppressing Pitting Corrosion on Al-Mg-Si Alloy by Steam Coating

et al. 2018

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Al alloys offer excellent physical and mechanical properties, such as a low density, high specific strength, and good ductility. However, their low corrosion resistance has restricted their application in corrosive environments. There is a need, therefore, for a novel coating technology that is capable of improving the corrosion resistance of Al alloys. In the present study, we examined a steam-based method of forming a corrosion-resistant film on Al alloys. Al-Mg-Si alloy was used as the substrate. The cleaned substrates were set in an autoclave with ultrapure water as the steam source and processed using different temperatures and holding times, resulting in the formation of anticorrosive films on the alloy. FE-SEM images of the film surfaces showed that plate-like nanocrystals were densely formed over the entire surface. XRD patterns indicated that the film was composed mainly of AlOOH crystals. The potentiodynamic polarization curves revealed that the corrosion current density of the film-coated substrates significantly decreased, and that the pitting corrosion was completely suppressed, indicating that the corrosion resistance of the Al-Mg-Si alloy was improved by the film formed by means of steam coating.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Formation of Anticorrosive Film for Suppressing Pitting Corrosion on Al-Mg-Si Alloy by Steam Coating

et al. 2018

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“…We have developed an environmentally friendly method of surface treatment, referred to as steam coating, for the magnesium alloy AZ31 [35,36]. A steam-coated film was formed directly on AZ31, which was then used as the Mg and Al sources of the film composed of Mg(OH) 2 and Mg-Al LDH, and it showed good corrosion resistance in 5 wt% NaCl solution at temperature of 273-308 K. This method of direct growth of the film on a substrate can considerably improve the adherence and mechanical stability of the resulting film over films formed by other methods such as spin-coating and dip-coating [37].…”

Section: Introductionmentioning

confidence: 99%

Corrosion resistance of Mg(OH)2/Mg–Al layered double hydroxide composite film formed directly on combustion-resistant magnesium alloy AMCa602 by steam coating

et al. 2015

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a b s t r a c tFilms of the Mg(OH) 2 /Mg-Al layered double hydroxide composite were formed on the combustionresistant magnesium alloy AMCa602 by steam coating and characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy. The corrosion-resistance performances of the films in a 5 wt% NaCl solution were investigated using electrochemical measurements. The corrosion current density of the sample that was steam-coated at 433 K for 6 h using the aqueous solution containing 200 mM Al(NO 3 ) 3 decreased significantly more than that of the bare AMCa602. The correlations between the Mg-Al LDH content in the films, Al(NO 3 ) 3 concentration in the aqueous solutions, and corrosion current densities were investigated.

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“…A chemical-free "steam coating" process has been developed to prepare an anticorrosion film on the surface of Mg alloys [7]. The steam coating creates an anticorrosion film mainly composed of Mg(OH) 2 and Mg-Al layered double hydroxide, such a film can provide excellent corrosion resistance [7][8][9]. In addition, this process has also been applied to improve the corrosive resistant Al alloys [10], because of the formation of a continuous Zn-rich amorphous layer and Zn-Al layered double hydroxide (LDH) with a dual-layer structure (a continuous amorphous layer on inside and a polycrystalline hydroxide layer on the outside) [11].…”

Section: Introductionmentioning

confidence: 99%

In Situ Scanning Electron Microscopy Observation of Crack Initiation and Propagation in Hydroxide Films Formed by Steam Coating on Aluminum-Alloy Sheets

Takata

Kobashi

et al. 2020

Materials

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Hydroxide film was formed on 6061 Al-alloy (Al-1.00Mg-0.62Si(wt.%)) sheets by steam coating with the temperature of 220 °C for 24 h. During bending test of the coated specimens, the crack initiation and propagation processes in the hydroxide film were investigated using in situ SEM observations. The hydroxide film formed exhibited a dual-layer structure composed of an inner amorphous layer and an outer polycrystalline γ-AlO(OH)-phase layer. On the compressively strained surface, lateral cracks are preferentially initiated inside the inner amorphous layer, and propagate either inside this layer or on its interface with the outer γ-AlO(OH) layer. Digital image correlation analyses of the in situ observed SEM images suggested that the concentrated tensile strain along the surface normal localized at some parts of the amorphous layer could contribute to the crack initiation. On the tensile-strained surface, a number of cracks were initiated inside the inner amorphous layer along the surface normal and propagate into the outer γ-AlO(OH) layer. No cracks were found along the interface of the amorphous layer with the Al-alloy substrate. As a result, the anticorrosion hydroxide film adhered on the Al sheet after bending deformation. Such strong adhesion contributes to the excellent corrosion resistance of the Al-alloy parts provided by the steam coating.

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In Situ Formation of Anticorrosive Mg-Al Layered Double Hydroxide-Containing Magnesium Hydroxide Film on Magnesium Alloy by Steam Coating

Cited by 36 publications

References 17 publications

Formation of Anticorrosive Film for Suppressing Pitting Corrosion on Al-Mg-Si Alloy by Steam Coating

Formation of Anticorrosive Film for Suppressing Pitting Corrosion on Al-Mg-Si Alloy by Steam Coating

Corrosion resistance of Mg(OH)2/Mg–Al layered double hydroxide composite film formed directly on combustion-resistant magnesium alloy AMCa602 by steam coating

In Situ Scanning Electron Microscopy Observation of Crack Initiation and Propagation in Hydroxide Films Formed by Steam Coating on Aluminum-Alloy Sheets

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