1993 Volume 42 Issue 5 Pages 283-290
The dependence of passive current noise on passivation potential and Passivation time was investigated for SUS 304 in 0.05M H2SO4 and in ethanol solutions of different H2O concentration. The effect of Cl- addition was also examined for H2SO4. It was found that the power spectral density (PSD) resulted from FFT analysis of the current noise depended on the passivation potential and the passivation time in H2SO4 solution in the absence of Cl-, with respect to the PSD level and its changing mode. Moreover, the PSD level was confirmed to change markedly corresponding to a little change of H2O concentration in the ethanol solution even in the passivation under a constant potential. From the above facts along with the effect of Cl- addition on the PSD, the PSD level and its changing mode were interpreted in terms of the nature of two kinds of bound water incorporated in the passive film.