Colored titanium passive films preparation, characterization, applications, and surface modification

Abstract

Brightly and uniformly colored passive layers on Ti are prepared by application of AC polarization in aqueous NH4 BF4 . Such formed films reveal a wider spectrum of colors that those prepared by gas-phase techniques at elevated temperatures and can be formed within second. The influence of different experimental parameters (electrolyte pH and concentration, duration of polarization, type of applied voltage) on the coloration, uniformity, brightness, and morphology of the colored films is examined. The comparison with DC polarization was also studied. Electrochemical properties of the colored Ti passive layers are determined by recording polarization curves in the -0.8-3.2 V vs. RHE range and Tafel plots in the hydrogen evolution reaction (HER) region in 1.0 M aqueous H2 SO4 solution. Studies of morphology and electrochemical characterization of Ebonex ª are also carried out. One of the objectives of this work was the preparation of Ti-based electrode materials for Hydrogen Evolution Reaction (HER) by surface modification of colored Ti passive layers through RuO2 and/or IrO2 depositing/doping."--Résumé abrégé par UMI