Journal of the Serbian Chemical Society (Jan 2013)

Electrochemical methods for corrosion testing of Ce-based coating prepared on AA6060 alloy by dip immersion method

  • Jegdić Bore V.,
  • Živković Ljiljana S.,
  • Popić Jovan P.,
  • Bajat Jelena B.,
  • Mišković-Stanković Vesna B.

DOI
https://doi.org/10.2298/JSC121212009J
Journal volume & issue
Vol. 78, no. 7
pp. 997 – 1011

Abstract

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Dip-immersion is simple and cost-effective method for the preparation of Ce-based conversion coatings (CeCCs), a promising alternative to the toxic chromate coatings, on the metal substrates. In this work CeCCs were prepared on Al-alloy AA6060 from aqueous solution of cerium chloride at room temperature. Effect of immersion time and post-treatment in phosphate solution on the microstructure and corrosion properties of the coatings was studied. The longer immersion time, the thicker but nonhomogeneous and cracked CeCCs. The post-treatment contributed to the sealing of cracks, as proven by an increase in corrosion resistance compared with as-deposited coatings. CeCCs prepared at longer deposition time and post-treated showed much better corrosion protection than those prepared at short deposition time. A detailed EIS study was undertaken to follow the evolution of corrosion behaviour of CeCCs with time of exposure to aggressive chloride environment (3.5 % NaCl). For the sake of comparison, the EIS properties of bare AA6060 were also investigated. A linear voltammetry was performed to complete the study. Results confirmed a formation of protective CeCCs on AA6060 surface. However, even CeCCs prepared at longer deposition time and post-treated provided a short term protection in aggressive environment, due to the small thickness. [Projekat Ministarstva nauke Republike Srbije, br. III 45019 i br. III 45012]

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