Formation and Properties of Anodic Oxide Films of Titanium Formed under Discharge Conditions in an Electrolyte

Abstract

Anodic oxidation is a popular method to deposit an oxide film on titanium with a thickness on the order of several hundred nm. In this study formation and some properties of anodic films of titanium under discharge conditions were investigated. Treated titanium specimens served as an anode in several electrolytes, and voltage was applied using the direct current power source. The discharge threshold voltage in each electrolyte decreased as the concentration of the electrolyte increased. Anodic oxidation of titanium was carried out on applying the voltage above the discharge threshold voltage, for example, at 100-130 V for a phosphoric acid solution (30 wt. %). Surface films with a thickness on the order of pm were formed by this treatment. Adhesion of the oxide film was superior when the anodic oxidation was carried out under moderate discharge conditions. SEM observations appeared the featured microscopic surface topography with many small (pm order) holes on the surface of the specimen treated by anodic oxidation under discharge conditions. X-ray diffractory analysis revealed that titanium oxides (Ti.02,1) and an amorphous anatase (Ti02) were formed by the anodic oxidation under discharge conditions.