Absorbing power of anodized oxide coating of aluminium (alumite) is destroyed by boiling water or super heated steam sealing. The sealing is performed by hydration of alumina (anhydrous and amorphous γ-Al₂O₃) formed by anodizing. The hydrated products have been considered to bear a resemblance to boehmite in crystallins structure. In this study, the hydrated products of sulfuric or oxalic acid alumite were examined by electron microscope, electron diffraction, and X-ray diffraction, and they were confirmed to be quasi-boehmite. As the results of the observation of the coating surface by electron microscope, it was known that the sealing of pores was caused by the expansion of alumite by hydration.

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The magnetic thin film of Fe-Ni alloy (Fe/Ni=20/80) available to the element of electronic computer was deposited from sulfamate solution. The composition of electrolyte and operating conditions were investigated by using the apparatus of continuous flow system shown in Fig. 1. As the results Fe-Ni alloy thin film (about 1μthick) of bright surface and excellent magnetic characteristics were obtained with good reproducibility under the following conditions;
electrolyte composition: as shown in Table 1 cathode current density: 25A/dm²
temperature: 45°C cell voltage: 2.8V
pH: 1.0 wire sending velocity: 1.5cm/s

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