Downstream analytics quantification of ion release during high-voltage anodisation of niobium

Abstract

In operando quantification of field-assisted ion release during high-voltage anodisation (up to 100 V SHE) of Nb in 0.1 M sulphuric acid was performed. Electrochemical high-field oxide formation under both potential and current control was studied separately. The quantification of in situ ion release via ICP-MS revealed an increase of the oxide dissolution factor (from 337 to 422 fm V −1) when decreasing the potential scan rate from 200 to 100 mV s −1. Dissolution rates measured during galvanostatic oxide formation allowed measuring oxide dissolution factors of 719 and 837 fm V −1 for current densities of 1.0 and 0.5 mA cm −2 , respectively. As compared to the potentiodynamic case, higher dissolution rates and oxide dissolution factors were measured for galvanostatic anodisation. The overall fraction of the charge used for generation of soluble Nb species was below 0.4% for all oxide growth regimes. Cross-sectional SEM imaging proofs an oxide formation factor of 2.1 nm V −1. The surface of anodised films was extremely smooth and featureless without any cracks or voids. Based on X-ray diffraction, the films were found to be amorphous, indicating that no field crystallisation is occurring under the applied oxide growth conditions even at higher voltages.

Atomic Emission Spectroelectrochemistry: Real-Time Rate Measurements of Dissolution, Corrosion, and Passivation

“…Continuous in-line experiments have been conducted using ICP-MS in particular using a scanning droplet cell (SDC) as developed at the Max Planck Institute in Düsselorf by Klemm, et al [25][26][27][28] Using either the SDC or a conventional flow cell, ICP-MS has been used to investigate the corrosion of Mg, Al, and Ni alloys, [29][30][31][32][33][34] the kinetics of the degradation of heterogeneous catalysts, [26][27][35][36][37][38] and to detect partial currents during anodization. [39][40][41][42][43][44] Recently, Lopes, et al, 45 moved away from the flow cell technique to directly sample the electrolyte in the vicinity of a rotating disk electrode with transfer to an ICP-MS to investigate the dissolution of Pt single crystals.…”

Impact of Femtosecond Laser Treatment Accompanied with Anodization of Titanium Alloy on Fibroblast Cell Growth

“…Nevertheless, the dissolution of vanadium and aluminum (that are considered as toxic materials) into the body is a matter of concern for future usage . The ionic dissolution is dependent upon the corrosion rate and it is a well‐known fact that the corrosion rate of valve metals can be significantly decreased by anodization …”

Porous‐Alumina‐Assisted Growth of Nanostructured Anodic Films on Ti−Nb Alloys

“…The O 2 evolution has been associated with an amorphousto-crystalline transition of the bottom oxide (hereafter the 'field crystallization'), [16] the phenomenon being generally known for barrier-type anodic film growth on Ti surface at relatively low potentials of less than~15-20 V. [19][20][21] However, anodic oxides on other valve metals like Ta, Nb, or W grow generally amorphous during the barrier-type anodizing up to substantially higher potentials, [22][23][24][25] and their PAA-assisted anodizing results in long-aspect-ratio amorphous and stable nanocolumns or rods, [26][27][28][29] without obvious O 2 evolution. It is anticipated that alloying of titanium with one of these metals could suppress the field crystallization and void formation in the anodic oxide, as well as minimize the incorporation of alumina in the root composition and, therefore, improve the stability of the column arrays.…”