The effect of temperature on the growth of anodic oxide film on titanium

Abstract

The effect of temperature on the growth and properties of anodic oxide films on titanium has been studied by electrochemical and impedance measurements combined with solution analysis by inductively coupled plasma emission spectrometry. Under potentiostatic conditions, the current efficiency is almost close to unity in the early film growth stage, but beyond this stage, significant film dissolution occurs. The charge for l h film growth was determined from the difference between the total charge passed and the charge equivalent to titanium ions dissolved in the solution; the charge for film growth increases linearly with potential. The reciprocal capacitance of the film also has a linear dependence on potential. By using these data, the dielectric constant for the anodic film was estimated. The dielectric constant increases with temperature and the value of the dielectric constant for the film formed at 323 K or 333 K is close to that for anatase, suggesting that the anodic films formed above 323 K became crystalline.