Papers by Author: Hiroshi Nanjo

Abstract: The titanium anodizations in 0.1 M sulfuric acid solution at different treated potentials and the effects of UV-irradiation on the anodized films were investigated by spectroscopic ellipsometry (SE), atomic force microscopy (AFM) and scanning tunneling microscopy (STM). The results showed that the thickness of anodized films decreased in air within 280 min over 500 mV vs. Ag/AgCl. The features of parameters tanΨ and cosΔ in SE were in accord with the polarization curve and the thickness of anodized films, respectively. UV-irradiation could greatly decrease the thickness of the anodized films and provably assisted the reconstruction of anodized titanium films from an amorphous and porous structure to a compact structure. Regardless of UV-irradiation, the cosΔ and tanΨ were still in good agreements with the thickness of anodized films and the polarization curve, respectively. It was also found that UV-irradiation could decrease the surface roughness and make a wider atomically flat terrace on the anodized titanium surface.

Abstract: We propose a multi-element hopping model, which shows the flux equations of various cations under high electric field. The model is applied to the initial oxidation of binary alloys which produces a homogeneous single layer solid solution oxide film. The flux equations by this model for two kinds of cations were substituted to the oxidation growth rate definition equation. Finally, it is shown that the initial oxidation rate law of dilute binary alloys can be obtained as a type of inverse logarithmic rate law.