Mechanism of the formation of pores in the anodic oxide films on Al in sulfuric acid solution was studied by electron microscopic examination of the films in the stage of the decrease of anode potential with anodizing time in the secondary electrolysis.
The results obtained were as follows.
1) The pores of andic oxide films on Al, formed in the anodizing process in sulfuric acid solution, were found to be produced by the dissolution of intersecting points of the ridges (which had previously been formed in the primary electrolysis) of oxide layers and also of the ridges themselves, when the time of electrolysis was very short.
2) With the progress of electrolysis, the structural features of oxide films was observed to be formed into hexagonal unit cells, of which the dimensions were proportimal to the ratio of 10A/V of the cell voltage measured in the primary electrolysis.
3) When the electrolysis further proceeded in the same electrolyte, the pores, which would be formed under the condition of secondary electrolysis, were also formed by the result of further dissolution of intersecting points of the ridges (which had previously been formed in the primary electrolysis) of oxide layers and also of the ridges themselves.
4) The rate of the formation of pores in the anodic oxide films was found to depend upon the temperature of electrolyte, but not upon the current density.

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The wettability and the bonding strength of soft solders were studied. An electric furnace was used for heating to avoid the changes in the compositions of the solders by mixing with impurities.
The following results were obtained by experiments.
(1) The highest wettability of solders was given at 45-50% of tin content and at 40-50°C above the liquidus temperature.
(2) For obtaining high bonding strength, it was desirable that the soldering should be done as rapidly as possible and the soldered section should immediately be cooled. It was also observed that the bonding strength was higher with the increase in lead content; the reverse was the case with the tensile strength of the solder itself.

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Current-voltage characteristics of TiO₂ and TiO₂-BaTiO₃ films produced by flame spraying were measured. It was found that the film of TiO₂ had semi-conductivity. Various kinds of semiconductive films having various resistivities and other properties were obtained by heat-treatment of TiO₂ with which BaTiO₃ had been blended in various ratios.
The resistivity of the composite films was higher than that of single TiO₂. When a proper electrode was applied to the surface of a film thus produded, there would be a diode between the electrode and the substrate which served as an opposite electrode.
The effect of thickness of the films on current-voltage characteristics was considerably great; commutating ratio was rapidly decreased with the increase in thickness of the films.
It was also found that the effect of electrode was very little; very similar results were given by fired-on silver electrode and flame-sprayed metal electrodes (such as Cu and Al).
The backword current was lower with the rise of ambient temperature up to 250°C. The mechanism of commutation was considered to be attributed to the gradient of oxygen concentration in the films.
The highest commutating ratio ever obtained was as low as 95; but the value will be further raised by some proper surface treatments.

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