Corrosion inhibition of aluminium alloy AA6063-T5 by vanadates: Local surface chemical events elucidated by confocal Raman micro-spectroscopy


Kharitonov D. S. , Sommertune J., Ornek C. , Ryl J., Kurilo I. I. , Claesson P. M. , ...More

CORROSION SCIENCE, vol.148, pp.237-250, 2019 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 148
  • Publication Date: 2019
  • Doi Number: 10.1016/j.corsci.2018.12.011
  • Title of Journal : CORROSION SCIENCE
  • Page Numbers: pp.237-250
  • Keywords: Aluminium, Alloy, Raman spectroscopy, SEM, XPS, Vanadate inhibitor, OXIDE THIN-FILMS, IN-SITU, AQUEOUS VANADATE, GALVANIC CORROSION, AL-ALLOYS, VANADIUM, OXIDATION, 2024-T3, MECHANISMS, PROTECTION

Abstract

Chemical interactions between aqueous vanadium species and aluminium alloy AA6063-T5 were investigated in vanadate-containing NaCl solutions. Confocal Raman and X-ray photoelectron spectroscopy experiments were utilised to gain insight into the mechanism of corrosion inhibition by vanadates. A greenish-grey coloured surface layer, consisting of V+4 and V+5 polymerized species, was seen to form on the alloy surface, especially on top of cathodic micrometre-sized IMPs, whereby suppressing oxygen reduction kinetics. The results suggest a two-step mechanism of corrosion inhibition in which V+5 species are first reduced to V+4 or V+3 species above cathodic IMPs, and then oxidized to mixed-valence V+5/V+4 polymerized compounds.