Active corrosion protection by a smart coating based on a MgAl-layered double hydroxide on a cerium-modified plasma electrolytic oxidation coating on Mg alloy AZ31

•PEO with Ce salt sealing and LDHs composite coating was produced via hydrothermal treatment and was then modified by phytic acid.•PEO-Ce-LDH showed two different surface morphologies.•Due to the compact insoluble precipitate covered the entire defect, PEO-Ce-LDH-P had the best self-healing ability....

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Bibliographic Details
Published in:Corrosion science 2018-07, Vol.139, p.370-382
Main Authors: Zhang, Gen, Wu, Liang, Tang, Aitao, Ma, Yanlong, Song, Guang-Ling, Zheng, Dajiang, Jiang, Bin, Atrens, Andrej, Pan, Fusheng
Format: Article
Language:English
Subjects:
Aluminum
Aluminum manganese alloys
Cerium oxides
Corrosion
Corrosion effects
Corrosion prevention
Corrosion resistance
Hydrothermal treatment
Hydroxides
Immersion tests (corrosion)
Ion exchange
Layered double hydroxides
Magnesium alloys
Magnesium base alloys
Materials science
Oxidation
Phytic acid
Plasma electrolytic oxidation
Protective coatings
Self healing materials
Self-healing
Synergistic effect
X ray photoelectron spectroscopy
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Summary:•PEO with Ce salt sealing and LDHs composite coating was produced via hydrothermal treatment and was then modified by phytic acid.•PEO-Ce-LDH showed two different surface morphologies.•Due to the compact insoluble precipitate covered the entire defect, PEO-Ce-LDH-P had the best self-healing ability. A composite coating was produced via (i) plasma electrolytic oxidation (PEO) with Ce salt sealing, on which layered double hydroxides (LDHs) were deposited via a hydrothermal treatment, and (ii) then modified by phytic acid (PA) via an ion-exchange reaction. The final coating (characterized using XRD, XPS, FT-IR, SEM, EDS and GDOES) consisted of LDHs/Mg(OH)2/CeO2/Ce(OH)3 with a non-uniform Ce distribution. The corrosion protection and self-healing ability were investigated using polarization curves, EIS, immersion tests and SVET. The composite coating modified with PA showed the most superior corrosion protection and self-healing ability, attributed to the synergistic effect between Ce species and phosphate.
ISSN:0010-938X
1879-0496
DOI:10.1016/j.corsci.2018.05.010