STRONG ACID-RESISTANT AND ALKARI-RESISTANT TA2O5-ZRO2 FILMS PREPARED BY LOW-PRESSURE MOCVD

In order to obtain composite oxide films with corrosion resistances against both aqua regia and concentrated NaOH solutions, Ta2O5-ZrO2 films were formed on Pt and Si substrates by low pressure CVD techniques using tantalum pentamethoxide (Ta(OCH3)5), zirconium-tetra-isopropoxide (Zr(O-i-C3H7)4) and oxygen. The films obtained were composed of composite oxides of which the indepth composition was uniform. The changes in the corrosion resistance of the films were investigated as a function of film composition. The corrosion resistance of the films in aqua regia increased with increasing Ta(V) cation ratio but that in a 10.0 kmol.m-3 NaOH solution increased with increasing Zr(IV) cation ratio. The highest corrosion resistance aginst both aqua regia and 10.0 kmol.M-3 NaOH solutions was obtained at the Ta(V) cation ratios between 0.3 and 0.5. The films with such composition have fine and uniform structures.