Koji Tachibana

Distribution of Cobalt in Surface Oxide Film of Type 304 Stainless Steel Exposed to High-Temperature Water Quantitative Analysis by Glow Discharge Optical Emission Spectrometry

The glow discharge optical emission spectrometry (GDS) was applied to determine the cobalt distribution accumulated in the corrosion film of type 304 stainless steel that was exposed to demineralized water with below 5 ppb of dissolved oxygen content at 561K. The exposure test was carried out using two parallel high-temperature and high-pressure water experimental loops, one with 3 ppb non-active cobalt added and the other without. The structure and element depth distributions of the corroded specimen surfaces were analyzed by EPMA, XRD, XPS and GDS. The corrosion film of the specimen exposed for 1,000 h had a clear double layer structure consisting of an iron-rich outer layer 3 μm in thickness and a chromium-rich inner layer 0.5 μm in thickness. The cobalt distributions in the corrosion film could successfully be determined by GDS. The distribution of cobalt was peculiar in the corrosion film and the distribution curves had a peak around the boundary between the two layers. The cobalt concentration tended to increase linearly with the exposure time.

Changes in the power spectral density of noise current on type 304 stainless steels during the long time passivation in sulfuric acid solutions

The anodic current fluctuation during long time passivation on type 304SS in H2SO4 aq. solutions without aggressive ions was analyzed by FFT method. The observed dependence of power spectral density (PSD) on passivation potential and time can be described in terms of the nature of two kinds of bound water incorporated in the passive film.

Enhancement of photorefractive effect in the isotropic phase of liquid crystalline polymers

Abstract The photorefractive effect of the isotropic phase of liquid crystalline polymers was investigated. A large photorefractivity was observed in polymers which exhibit a liquid crystalline phase even though they were in the isotropic phase. The photorefractivity was compared between the liquid crystalline polymers and amorphous polymers. The photorefractive effect was found to be significantly enhanced in the isotropic phase of the liquid crystalline polymers compared to that of the amorphous polymers with almost the same molecular structure.