Insight into relationship between composition,thickness and electrochemistry behavior of oxide film formed on TA15under different potentials in 0.5 mol·L^(-1)H_(2)SO_(4)

The oxide film formed on TA15 alloy in0.5 mol·L^(-1)H_(2)SO_(4)at different applied potentials is investigated by evaluating the film formation current density,film thickness,surface film composition,valence state,and the electrochemical characteristics.The relative quantitative spectral analysis revealed by X-ray photoelectron spectroscopy(XPS)and X-ray absorption spectra(XAS)shows that the increasing applied potential promotes the formation of thick and high-valence state films.By contrasting with XAS of the reference titanium oxides,it is found that TiO_(2)within the oxide film changes from anatase type to rutile type with the potential increases to 2.00 V.The oxide film formed at passive region has better protection performance,and with the increase of applied potential,the corrosion resistance of passive film increases,whereas the ND(donor density)values obtained from the Mott-Schottky(MS)results decrease with the increasing applied potential,indicating a better uniformity and protective effect of the oxide film.Based on above facts,the model of the oxide films formed on TA15 at different applied potentials in passive region and dissolve region is proposed.Besides,the existence forms of all the TA15alloying elements under the most corrosion resistant condition are confirmed.