| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 1998: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1997: ¥3,100,000 (Direct Cost: ¥3,100,000)
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| Research Abstract |
Surface electronic states of passivatlon oxide films on metals have been investigated for understanding the corrosion resistivity of the films. The resistivity of the passivation oxide films may be greatly connected with the energy position and density of the surface state. In this investigation, the change of the passivation films on titanium and iron was examined by ellipsometry and impedance during the ultra-violet (uv) light irradiation which may induces new surface states through the hole excitation.
An ellipsometric measurement system has been developed In which the passivation oxide films on metals can be measured under uv light irradiation. By using the ellipsometer, the changes of the passivation films was measured with the simultaneous uv light Irradiation. The change of titanium passivation films depends on solution pH : Above pH 2, decrease of refractive index of the film and thickening of the film are observed. This observation means that the oxide film changes to a hydrous form. At an acidic solution of pH 1, same observation is Initially seen, however, the thinning of the film takes place during prolonged uv light irradiation. The hole generation by the uv light irradiation induces new electronic surface states and then hydration of the oxide. This reactions depend on solution pH values. From impedance measurement, it is seen that the electric capacitance changes with the uv light irradiation. The capacitance change corresponds to generation of the surface state on the film, hydration of the film, and light-Induced dissolution, For the passivation film on Iron, similar measurement was done. Although the film Is too thin to discuss the change of the passivation oxide films In detail, the hydration of the oxide films was observed with the uv light irradiation.
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