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Journal of Electrochemical Science and Engineering, Vol. 12 No. 4, 2022.

Original scientific paper

https://doi.org/10.5599/jese.1305

Cerium-based conversion films developed on LiAl-layered double hydroxide coatings for corrosion protection of AA7075 aluminum alloys

Aurora Petica ; Center of Surface Science and Nanotechnology, University Politehnica of Bucharest, Splaiul Independentei 313, 060042 Bucharest, Romania
Adrian Cristian Manea ; Center of Surface Science and Nanotechnology, University Politehnica of Bucharest, Splaiul Independentei 313, 060042 Bucharest, Romania
Geanina Mihai ; Center of Surface Science and Nanotechnology, University Politehnica of Bucharest, Splaiul Independentei 313, 060042 Bucharest, Romania
Ioana Nicola ; ICPE-SA, Splaiul Unirii 313, 030138, Bucharest, Romania
Victoria Ceara ; ICPE-SA, Splaiul Unirii 313, 030138, Bucharest, Romania
Liana Anicai ; Center of Surface Science and Nanotechnology, University Politehnica of Bucharest, Splaiul Independentei 313, 060042 Bucharest, Romania

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Abstract

The paper presents several experimental results regarding the influence of various procedures applied to incorporate Ce species in hydrotalcite–type chemical conver­sion coatings on the overall corrosion performance for AA 7075 aluminum alloy as a metallic substrate. Two routes were envisaged: (i) chemical incorporation of Ce by immersion in cerium nitrate solutions and (ii) electrochemical deposition of hydro­phobic Ce - based layer involving ethanolic solutions of stearic acid and cerium nitrate. The chemical route involving immersion in cerium nitrate solutions led to the incorpo­ration of 2.46 – 6.84 wt.% Ce in the composition of the porous conversion layer. The electrochemical process facilitated the formation of a hydrophobic cerium stearate layer on porous hydrotalcite conversion coating showing water contact angles of about 132o and a higher Ce content incorporated of 6.55 – 9.73 wt.%. The corrosion performance of the Ce-based conversion coatings is also discussed.

Keywords

Conversion coatings; chromium-free conversion coatings; aluminum alloys; corrosion behavior; hydrophobic layers

Hrčak ID:

283679

URI

https://hrcak.srce.hr/283679

Publication date:

18.9.2022.

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