Multi-Scale Modeling of the Initial Stages of Anodic Oxidation of Titanium

Abstract

The present paper describes the nanoscale modeling of the adsorption and dissociation of water molecules on the titanium Ti (001) surface at different applied potentials and its connection to a previously proposed continuum scale approach to the growth and dissolution of thin barrier films on Ti in water-containing electrolytes. The theoretical study of titanium/water interactions is presented as combination of static and molecular dynamics calculations using density functional theory (DFT). The vibration frequencies of adsorbed H2O put emphasis on its interaction with the titanium surface and provide further information about the bond strength and the changes in the molecular structure. The adsorption and dissociation geometry of water molecules on Ti (001) surface in an electrochemical environment is investigated using the double reference method that allows assessing the elementary steps of water dissociation as depending on the applied potential. The dependence of the free energy of the Ti/water system on potential is obtained and discussed in terms of sequential dissociation of water to adsorbed hydroxyl and oxygen.

Parameterization and Extension of a Model of Oxide Growth by a Multi-Method Approach

“…Since reactive metals are in practice always covered with a thin oxide film, the only possibility to assess their direct interaction with electrolytes is via quantum chemical simulations. 10,11 Further, as scanning probe microscopies and quantum mechanical simulations have contributed to a considerable insight in anodic behavior of metals at the atomic scale, contemporary modeling needs to develop bridges across different scales. [12][13][14] In the present paper, parameterization of a kinetic model of oxide growth and dissolution on titanium in ethylene glycol-water-fluoride electrolytes is described.…”

Characterization and Modeling of Anodic Oxide Films on a Ti Alloy in Fluoride-Containing Electrolyte

“…[24][25][26][27][28][29] In the past 15 years, a detailed study of the growth and dissolution of barrier and porous oxides on Ti and other valve metals (Nb, W and Al) in aqueous and non-aqueous fluoridecontaining electrolytes was undertaken in our group. [30][31][32][33][34][35][36][37][38][39][40] The goal of that study was to propose and parameterize a kinetic model for the growth and dissolution of such materials 31,32,35,36 to serve as a base for a quantitative approach to nanopore nucleation and growth.…”

“…[34][35][36] Ways of extracting parameters at the metal/film interface were sought by modeling the initial Ti-water interaction process by density functional theory (DFT) calculations. 37,38 Very recently, further in situ methods such as high-frequency dynamic impedance and modulated photocurrent measurements were also employed. 39 An extension of the model to characterize the initial stages of anodic oxidation of several Ti alloys in an ethylene glycol-water-fluoride electrolyte at low applied potentials was attempted.…”