Passive film formed on 304 stainless steel in 2.5 mol/L H~2SO~4 solution by using alternating voltage (A. V. ) passivation have been investigated by measuring capacitance and photoelectrochemical parameters. The investigation of the effect of measure frequency on the slope of Mott-Schottky curve has been carried out. The photoelectrochemical measurements were consistent with the capacitance measurement. Analysis of the experimental results showed that the passive film formed 304 stainless steel by using A. V. passivation exhibits semiconducting properties. Using the simple model of semiconductor rather than the multi-donor level model can explain satisfactorily the semiconducting behavior of the film formed on 304 stainless steel by using A. V. passivation.

Key words: STAINLESS STEEL, PASSIVATION FILMS, PHOTO-ELECTROCHEMISTRY