Anodic titanium oxide and its pphotoelectrochemical and ttribocorrosion behavior

Abstract

The obtained oxide films are continuous, amorphous, and the smoothest surface is obtained after Ti anodizing in 2 M H3PO4 + 0.05 M NH4F solution. At concentration of NH4F 0.2M, the nanotubes of TiO2 are formed at the temperatures 10-20°C and voltage 20V. The length of nanotubes determined by FIB technique is in the range 650-730 nm, and the diameter of pores is 60-80 nm. The photocurrents and photopotentials correlate with luorine incorporation into film, and the values of ones were obtained for films not included fluorine, i.e. for films obtained in pure 2M H3PO4. The anodic photovoltage up to 2 V (at constant current 1 A/cm2) and photocurrent up to 5 A/cm2 (at constant anodic potential 1.8 V) have been detected in 0.05M NaOH solution. Tribocorrosion tests were performed in a neutral solution, and changes of open-circuit potential as well as electrochemical impedance spectra were recorded with/without 0.4 N load. The metallic Ti (“as is”) and anodized Ti covered by TiO2 films immersed into 0.05 M H2SO4 + 0.2 M K2SO4 (pH 7) solution show passive behavior. TiO2 films destroyed during sliding tend to restore within 300–400 s after unloading.