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

• Published in: Journal of Electrochemical Science and Engineering Vol. 12; no. 4; p. 703
• Main Authors: Petica, Aurora, Manea, Adrian Cristian, Mihai, Geanina, Nicola, Ioana, Ceara, Victoria, Anicai, Liana
• Format: Paper Journal Article
• Language: English
• Published: Međunarodna udruga fizikalnih kemičara 01.01.2022; International Association of Physical Chemists (IAPC)
• Subjects: aluminum alloys; chromium free conversion coatings; Conversion coatings; corrosion behavior; hydrophobic layers
• ISSN: 1847-9286
• DOI: 10.5599/jese.1305

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.