The dissolution behaviors of anodic oxide films during anodizing of Al at a constant current density in oxalic acid, orthophosphoric acid, and chromic acid solutions were investigated by measuring the change in anode potential with the anodizing time.
The structural features of anodic oxide films formed in oxalic acid solution were studied by eletron microscopy.
The results obtained were as follows.
1) Activation energies for the dissolution of the barrier layer were found to be 0.54eV for oxalic acid, 0.72eV for phosphoric acid, and 0.88eV for chromic acid.
2) In anodizing of Al in oxalic acid solution, both of the pore diameter and the cell size increased and the number of pores decreased with the increase in current density.
3) During the process in oxalic acid solution, in which anode potential of Al decreased with the anodizing time, the formation of pores in the oxide layers was found to be at the intersecting points of the ridges and also on the ridges themselves as seen in sulfuric acid solution.

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This paper describes the semi-conductive properties of flame-sprayed TiO₂ and TiO₂-BaTiO₃ coatings and discusses about the applicability of these coatings to thermistor elements.
The following conclusions were drawn from the results of various tests.
1) Specific resistance of the coatings increased with the increase in the addition amount of BaTiO₃. Then, the change of resistance with temperature was also greater; that is, the value of B (thermistor constant) increased.
2) The heat dissipation constant (k) of single TiO₂ was 0.5-1; but the value increased with the increasing addition of BaTiO₃ to TiO₂. It reached the maximum at a certain amount of BaTiO₃, and then, decreased with the increase of BaTiO₃. The maximum value of k would be at 50-60 wt% of BaTiO₃.
3) Coatings of low resistance with large values of B and k could be obtained by proper selection of blending ratio, temperature of heat treatment, and electrode material.
4) In almost all the cases, TiO₃-based coatings exhibited negative resistance.
5) Hall coefficient of flame-sprayed TiO₂ was extremely small so that it could not be measured by the ordinary direct-current method.

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Aluminum of 99.99% in purity was anodized in aqueous solutions of sulfuric, oxalic, and chromic acids. The behavior of the dissolution of these anodic oxide films dipped in sulfuric and various organic acids was examined. The relation between these results and the bath voltage during the anodizing in these acids was discussed.
The results obtained were as follows.
1) Among the acids of the same series, the dissolution rate of the film was higher and the bath voltage was lower when pk_a and pH of the acid were lower. However, among acids of different series, the dissolution rate could not be presumed from pk_a and pH, and the degree of bath voltage also could not be presumed from the dissolution rate.
2) It was known that the dissolution rate of anodic oxide films was not controlled by diffusion process, but by activation process.

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Decomposition mechanism of hexacyanoferrate (III) in sodium hydroxide solution, its corrosion inhibiting effect for aluminum etc. were investigated by potentiostatic studies and chemical analyses.
The results showed that hexacyanoferrate (III) was decomposed to Fe (II, III), CO₂, and NH₃ by electrolysis. The current-voltage (I-E) curve showed that the following decompisition occurred at about 0.5V on the anode.
Fe(CN)₆^3-→Fe³⁺+6CN^-
It was also observed on I-E curve that CN^- was decomposed at a higher voltage and the reducing reaction, Fe (CN)₆^3-→Fe(CN)₆^4-, occurred at about 0.1V.
The corrosion inhibiting effect of hexacyanoferrate (III) for aluminum in dilute alkaline solution was observed under the condition that the concentration of hexacyanoferratte (III) was equimolecular to or higher than that of sodium hydroxide. The effect was considerably great for 257S and pure Aluminum (99.50%), but very less for 52S.

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