THE GROWTH-KINETICS AND OPTICAL-PROPERTIES OF FILMS FORMED UNDER OPEN CIRCUIT CONDITIONS ON A TITANIUM SURFACE IN POTASSIUM HYDROXIDE SOLUTIONS

Open circuit film formation on titanium surfaces in potassium hydroxide solutions was studied using electrochemical techniques combined with ellipsometric in situ measurements. Some information about film structure and composition was obtained by X-ray diffraction, metallographic and spectroscopical measurements. It was shown that the thickness, inhomogeneity and porosity of open circuit film formation increase with increasing concentration of alkaline solutions. The complex index of refraction and thickness of generated film were determined by comparing the theoretical computed curve with experimental loci of DELTA vs psi obtained from in situ ellipsometric measurements. In each investigated concentration of potassium hydroxide solution the kinetics law of film thickness growth on titanium surface was determined and also the kinetic coefficients of rate of film growing were calculated. The film chemical composition was estimated as Ti(OH)3 and TiO2 . H2O. The microporous and porous films were found to be amorphous.