Comparison of corrosion resistances between Fe2O3-TiO2 artificial passivation film and passivation film on Fe-Ti alloy

Fe2O3-TiO2 double-oxide films were formed on Pt substrates by low-pressure metallorganic chemical vapor deposition using iron acetylacetonate and tetraisopropoxytitanium as precursors and O-2 as a reaction gas. Fe-Ti alloys were fabricated by an ion-beam sputter and an are-melting process. The corrosion resistances of the Fe2O3-TiO2 films and the Fe-Ti alloys were examined in acid solutions. The thinning rate of the Fe2O3-TiO2 films in 5 M HCl decreased with an increase in the formation temperature. Likewise, the dissolution rate decreased with increasing titanium cationic fraction in the films. The films hardly dissolved at anodic potentials, while significant dissolution occurred at cathodic potentials in 1 M H2SO4 owing to the selective reduction of iron oxide components in the films. Sputter-deposited Fe-Ti alloy films containing more than 39 atom % Ti and are-melted Fe-Ti alloys containing, more than 57 atom % Ti showed high corrosion resistance when passivated anodically in 5 M HCl. The dissolution rates of the Fe2O3-TiO2 films in 5 M HCl appear to be significantly small er than those of the passive films on the Fc-Ti alloy films and the Fe-Ti alloys in the same solution.