Fuel Cell and Hydrogen technology is a key technology to the commercialization of high expectations in order to construct the society to utilize the next- generation type energy. Fuel Cell Vehicle, which is one of the next generation cars and considered as an ultimate clean energy vehicle, has been developed vigorously for practical use. Also, the Hydrogen Refueling Stations have been positioning important as an infrastructure for the hydrogen energy spread. This report introduces the situation of the Technology Development to accomplish the low-cost and high-durability hydrogen refueling stations.

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Polarization curves of aluminum alloy 1050 were measured to obtain electrochemical parameters such as electron number, change transfer and exchanged current density of hydrogen evolution reaction in the conditions of deareated and open-to-air 0.1 mol dm^－3 NaCl solutions. The polarization behaviors are expressed by polarization resistance curves and quantitatively analyzed by using the differential polarization method which differentiated the experimental polarization curves into polarization resistance curves. The polarization resistance curves are interpreted and expressed as a parallel circuit of anodic and cathodic resistance curves for another expression of electrochemical system. It was found that electrochemical parameters of water reduction reaction such as electron number(n), charge transfer(α), and exchanged current density(i₀), are calculated as n=1, α=0.4～0.5 and about i₀=3×10^－3～4×10^－3 mA cm^－2, respectively.

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THz wave reflected from metal surface covered by invisible paint can be detected, because THz wave possesses both characteristics of radio wave and light. When the paint layer is not transparent in visible light region, the reflection of THz wave possibly detects the corrosion products underneath the paint layer. In this study, the reflection-absorption imaging of THz wave was applied to detection of corrosion products on hot-dip galvanizing steel sheets which was covered by epoxy resin.
The specimen of this study was hot-dip galvanizing steel sheets with scratch damage on the surface, and it was corroded by 5wt% NaCl solution spraying before the measurement. Frequency tunable THz light was generated by difference frequency generation from a GaP crystal. Large absorption was observed at area around the scratch zone at 2.0 THz and 2.8 THz imaging. From the comparison of the THz imaging with XRF mapping, zinc hydroxylchloride and zinc chloride was estimated as the corrosion products.
It was found that the THz wave technique is very available for non-destructive novel corrosion diagnosis of metal surface covered with invisible insulators or painted films.

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