Correlating X-ray computed tomography observations with respirometric measurement of aluminium alloy 6063 corrosion under FeCl3 droplets.

Corrosion of aluminium alloy 6063-T6 with exposure to simulated steel corrosion products using ferric chloride droplets was investigated. Focus of these experiments was to understand the role of oxygen in the redox process; therefore, samples were exposed to standard atmospheric conditions as well as to oxygen-derived conditions. Respirometric measurements indicate that the hydrogen evolution reaction (HER) is the dominant cathodic reaction. Especially in the initial stages when the corrosion rates are the highest, the HER occurs almost exclusively. At the later stages the oxygen reduction reaction (ORR) barely takes over as the main cathodic reaction. The dissolved volumes and maximum corrosion depths determined with X-ray Computed Tomography (XCT) were more significant for those samples deprived of oxygen. The composition of iron-rich deposits formed consisted of magnetite and maghemite, supporting exposure conditions where reactions were deprived of oxygen. • Respirometric measurements highlight the critical role of the hydrogen evolution reaction (HER) in the studied process. • The HER emerges as the primary cathodic reaction during the initial exposure stages, leading to the highest corrosion rates. • Utilising XCT and Respirometric measurements; researchers uncover valuable insights into the role of O 2 in the redox process. • O 2 deprived conditions exhibit amplified dissolved volumes and corrosion depths, indicating the HER's dominance. [ABSTRACT FROM AUTHOR]