Chronoamperometric study of the passive behaviour of tantalum in hostile media during water addition

The ability of tantalum to become passive through water addition in methanol solution during chronoamperometric experiments has been investigated. The achievement of passivity was found to be modulated according to the applied electrical potential and the nature of the aggressive anions. The chronoamperometric curves were interpreted as resulting from the balance between the influence of proton mobility in solution and the building of the passive film.

► Chronoamperometric study of the behaviour of tantalum in aggressive anhydrous media.
► Achievement of passivity is modulated according to the potential and the anion nature.
► The concomitant building of the passive film and influence of proton mobility are modelled.
► Anion-specific hydration effects play a crucial role in the corrosion/passive behaviour of valve metals.