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-pres sure metallorganic chemical vapor deposition using iron acetylacetonat e and tetraisopropoxytitanium as precursors and O-2 as a reaction gas. Fe-Ti alloys were fabricated by an ion-beam sputter and an are-meltin g process. The corrosion resistances of the Fe2O3-TiO2 films and the F e-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 formatio n temperature. Likewise, the dissolution rate decreased with increasin g titanium cationic fraction in the films. The films hardly dissolved at anodic potentials, while significant dissolution occurred at cathod ic potentials in 1 M H2SO4 owing to the selective reduction of iron ox ide components in the films. Sputter-deposited Fe-Ti alloy films conta ining more than 39 atom % Ti and are-melted Fe-Ti alloys containing, m ore 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 passi ve films on the Fc-Ti alloy films and the Fe-Ti alloys in the same sol ution.