Comparative EIS study of titanium-based materials in high corrosive environments

Abstract

Electrochemical impedance spectroscopy (EIS) is a technique relatively complex and modern that owes its existence to the emergence of electronic circuits. In this work, the behaviour in HCl 20% of three materials, Ti, Ti-15 Mo and Ti-15Mo-5Al fabricated by laser beam melting, was analysed using EIS. Impedance spectra have been obtained at various potentials, from open circuit potential to +2.0 V vs. Ref. Once the profiles of the impedance spectra were analysed, the experimental data were adjusted to an equivalent electrical model. Two models of equivalent circuits were presented: at Ecorr simple circuit is used while in the passive potential range an equivalent circuit with 2-time constants was used for fit the experimental data. It was concluded that titanium and studied titanium alloys undergo spontaneous passivation due to the oxide film formed on their surface in the reducing acid solution.