Original scientific paper
https://doi.org/10.5599/jese.245
Ellipsometric study of passive and anodic oxide films formed on Ti and Nb electrodes
Ljubomir Arsov
; Faculty of Technology and Metallurgy, University Ss. Cyril and Methodius, Rudjer Boskovic 16, 1000 Skopje, Republic of Macedonia
Irena Mickova
; Faculty of Technology and Metallurgy, University Ss. Cyril and Methodius, Rudjer Boskovic 16, 1000 Skopje, Republic of Macedonia
Abstract
Electrochemical formation of passive films and active/passive transition on Ti and Nb metal surfaces in various concentrations of H2SO4 and KOH solutions was investigated using potentiostatic and cyclic voltammetry methods. By simultaneous electrochemical and in-situ ellipsometric measurements the coefficients of film thickness growth of passive films in the potential region from -1.5 V to 4 V were determined. Results indicate the strong influence of the concentration and electrolyte nature to the active/passive transitions and stability of passive films. The influence of cathodic pre-treatment on the passive films dissolution and appearance of the reactivation peaks during the reverse potential cycling were shown. By multiple cycle sequences in which the final anodic potential was gradually enlarged, the barrier properties of passive films on investigated electrodes were confirmed. The electrochemical and ellipsometric data showed that the passive films formed on Nb electrode are more resistant that passive films formed on Ti electrode, especially in higher concentrations of investigated aggressive solutions.
Keywords
Potentiostatic method; Cyclic voltammetry; Film thickness growth; Stability and reactivation of passive films
Hrčak ID:
153188
URI
Publication date:
31.12.2015.
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