Stability of anodic tantalum oxide films in NaOH solutions

Abstract

The dissolution behaviour of the anodic oxide films formed on tantalum was investigated in NaOH solutions of different concentrations. In solutions of [OH-] < 3.0 M, no pronounced dissolution could be detected. However, in concentrated alkali solutions, [OH] > 3 M, the dissolution occurred to different extents depending on the alkali concentration. As observed from capacitance and potential measurements, the barrier film on Ta was found to be defective owing to the incorporation of OHions in the film. The nature of the barrier film and its dependence on formation rate, alkali concentration and solution temperature were investigated. Complex plane analysis illustrates the behaviour of the barrier film of different thickness, i.e. formation voltages, in NaOH solutions. The barrier film cannot be considered accurately as a perfect dielectric.

Bioactive tantalum metal prepared by micro-arc oxidation and NaOH treatment

“…The tantalum oxide passive layer rst reacts with the NaOH aqueous solution. 29 Then the tantalum metal substrate reacts with the NaOH aqueous solution. The negatively charged hydrated tantalate thus formed incorporates Na + ions to maintain electrical neutrality.…”

Clinical device‐related article surface characterization of explanted endovascular stents: Evidence of in vivo corrosion

“…Since the purpose of exposing control stents to NaOH was to assess its corrosive effect in terms of heavy metal ion release, we believe that the L605 CoCr control sufficed. Also, a Ta control was not available for testing in NaOH; however, Ta is known to show a passive behavior in concentrations of NaOH less than 3.0 M and therefore its surface would not be compromised by the lower concentration used for tissue removal in this study 17…”

Introduction to Corrosion - Basics and Advances

“…Allah and Moustafa studied quantum chemical calculations for amino pyrazole derivatives as inhibitors of corrosion of zinc, copper, and α-brass in an aqueous acid chloride solution [164]. They have performed the quantum mechanical calculations using the Dewar LCAO-SCF MO semi-empirical method, MNDO (modified neglect of differential overlap).…”