Cr2O3 sealing of anodized aluminum alloy by heat treatment

Lee, Junghoon; Kim, Yonghwan; Jang, Heuiun; Chung, Wonsub

doi:10.1016/j.surfcoat.2012.05.071

Cited by 51 publications

(12 citation statements)

References 19 publications

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“…The electrolyte is more difficult to infiltrate in the sealed film, and hence not only information about the barrier layer but also information of the porous layer can be obtained during the impedance spectroscopy test. Accordingly, the corrosion resistance of the sealed anodized film is better than that of the unsealed one …”

Section: Resultsmentioning

confidence: 99%

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Effect of NaAlO₂ sealing on corrosion resistance of 2024 aluminum alloy anodized film

Yang

Cheng

Liu

et al. 2018

Materials & Corrosion

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In order to effectively improve the corrosion resistance of aluminum alloys, anodic oxidation technique was used to generate the oxide film. Sealing after anodization is an important step to improve the corrosion resistance of aluminum alloys. In this paper, sealing effect of NaAlO2 solution on the oxalic acid anodized aluminum alloy was studied by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), and X‐ray photoelectron spectroscopy (XPS). Experimental results show that unsealed anodized aluminum alloys display a porous structure and have poor corrosion resistance but the pores are filled and the corrosion resistance of the sample is significantly improved when anodized aluminum alloy was immersed in 0.2 m/L NaAlO2 solution with pH of 7 for 5 min at 85 °C. Moreover, the anodized aluminum alloy with NaAlO2 sealing exhibited better corrosion resistance compared to the hydrothermally sealed sample, because of the formation of more AlOOH in NaAlO2 sealing treatment.

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Section: Resultsmentioning

confidence: 99%

“…Today, the most traditional sealing methods are boiling water, dichromate, and nickel salt sealing . However, boiling water sealing requires high energy consumption and the water quality must be relatively high .…”

Section: Introductionmentioning

confidence: 99%

Effect of NaAlO₂ sealing on corrosion resistance of 2024 aluminum alloy anodized film

Yang

Cheng

Liu

et al. 2018

Materials & Corrosion

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“…It is worth mentioning the ratio of Cr 2 O 3 to Cr(OH) 3 for passivated Ni–Cu–P coating (72:28) is obviously higher than the value for passivated Ni–P coating (52:48). Because of the more stable chemical property and the denser structure of Cr 2 O 3 , the passive film on Ni–Cu–P coating shows better anticorrosive property to resist attack of chloride ion in 3.5 wt.% NaCl solution. On the other hand, the hydroxyls of Cr(OH) 3 as hydrophilic group affect the wettability of passive film.…”

Section: Resultsmentioning

confidence: 99%

Effect of Cu in electroless Ni–Cu–P coating on passivation process

Gan

Zhao

Kang

et al. 2016

Surface & Interface Analysis

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Electroless Ni-P and Ni-Cu-P coatings were passivated by chromate conversion treatment respectively. The anticorrosive performances of passivated coatings were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy measurements. The passivated Ni-Cu-P coating exhibited a high corrosion resistance with the i corr of 0.236 μA/cm, 2 while the value of passivated Ni-P coating was only 1.030 μA/cm, 2 indicating the passive film could improve the corrosion resistance of Ni-Cu-P coating to a significant extent. High-resolution X-ray photoelectron spectroscopy was used to determine the chemical states of elements detected in the passive film. Compared with passivated Ni-P coating, the passive film on Ni-Cu-P coating exhibited a higher ratio of Cr 2 O 3 to Cr(OH) 3 with the value of 72:28, which was the main factor for passivated Ni-Cu-P coating showing excellent corrosion resistance. The effect of Cu in electroless Ni-Cu-P coating on passivation process was discussed by the contrast experiment.

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“…The most conventional sealing methods are dichromate, nickel acetate, boiling water, and cold nickel fluoride. However, hot water sealing requires high energy consumption, nickel fluoride sealing is expensive, and Cr (VI) used for dichromate sealing is recognized as toxic [12][13][14]. Recently, many green sealing methods have been proposed.…”

Section: Introductionmentioning

confidence: 99%

Influence of Sealing Treatment on the Corrosion Resistance of PEO Coated Al-Zn-Mg-Cu Alloy in Various Environments

et al. 2019

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In the present work, a coating was prepared on an Al alloy substrate by plasma electrolytic oxidation (PEO). To seal the micro defects in the oxide scale, a siloxane layer was prepared on the PEO coating by sol gel method. The polymer sealant was synthesized from Tetraethoxy silane (TEOS) and methacryloxy propyl trimethoxyl silane (MPTES). The chemical structure of the polymer was studied by Fourier transform infrared spectroscopy (FTIR). The morphologies and microstructure of the PEO coating and siloxane coating were investigated by scanning electron microscopy (SEM). The results showed that siloxane formed a continuous layer on the surface and effectively sealed the micro defects. The corrosion behavior of the coatings in three different corrosion solutions (NaCl, HCl, and NaOH) was examined by electrochemical impedance spectroscopy and potentiodynamic polarization. The corrosion resistance of the sealed coatings was superior to that of the PEO coating because it prevented the penetration of corrosive solutions. The corrosion resistance of the sealed coatings was found to decrease with increasing electrolyte concentration. The work demonstrated that siloxane sealing may greatly enhance the corrosion resistance of Al-based PEO coating in acidic, neutral, and alkaline environments.

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Cr2O3 sealing of anodized aluminum alloy by heat treatment

Cited by 51 publications

References 19 publications

Effect of NaAlO₂ sealing on corrosion resistance of 2024 aluminum alloy anodized film

Effect of NaAlO₂ sealing on corrosion resistance of 2024 aluminum alloy anodized film

Effect of Cu in electroless Ni–Cu–P coating on passivation process

Influence of Sealing Treatment on the Corrosion Resistance of PEO Coated Al-Zn-Mg-Cu Alloy in Various Environments

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Cr2O3 sealing of anodized aluminum alloy by heat treatment

Cited by 51 publications

References 19 publications

Effect of NaAlO2 sealing on corrosion resistance of 2024 aluminum alloy anodized film

Effect of NaAlO2 sealing on corrosion resistance of 2024 aluminum alloy anodized film

Effect of Cu in electroless Ni–Cu–P coating on passivation process

Influence of Sealing Treatment on the Corrosion Resistance of PEO Coated Al-Zn-Mg-Cu Alloy in Various Environments

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Effect of NaAlO₂ sealing on corrosion resistance of 2024 aluminum alloy anodized film

Effect of NaAlO₂ sealing on corrosion resistance of 2024 aluminum alloy anodized film