FORMATION OF FE2O3-TIO2 THIN OXIDE-FILMS BY LOW-PRESSURE MOCVD AND EVALUATION OF THEIR CORROSION-RESISTANCE

Thin Fe2O3-TiO2 films were formed on Pt by a low pressure MOCVD techni que and their corrosion resistance was examined in HCl and H2SO4 solut ions by immersion tests, dynamic polarization tests, and in-situ ellip sometry under potentiostatic polarization. in the immersion tests, dis solution rate of the films was determined by ellipsometry. The dissolu tion rate of the films in 5 kmol . m(-3) HCl decreased with increasing cationic fraction of Ti4+ ions, X(Ti), in the films and formation tem peratures of the films. When the value of X(Ti) exceeded 0.32, the fil ms formed at 673 K did not dissolve in 5 kmol . m(-3) HCl and showed e xellent corrosion resistance. The films did not dissolve in 1 kmol . m (-3) H2SO4 under anodic polarization, but dissolved owing to the catho dic reduction of Fe2O3 under cathodic polarization. The dissolution ra te of the films under cathodic polarization decreased with an increase in potential and also in the cationic fraction of Ti4+ ions, X(Ti), i n the films.