A new technique of anodizing of aluminum in acid solution was developed in order to avoid ‘burning’ and ‘powdering’ of the formed oxide films. The technique is characterized by alternate application of two voltages, E₁ (higher) and E₂ (lower), for periods of t₁ and t₂. On switching the voltage from E₁ to E₂, a large steady current, i₁ flowing at E₁, drops to a very small value, i₂, but thereafter it gradually becomes appreciable to attain a steady value corresponding to E₂. The phenomenon is called as ‘the recovery effect’ by Murphy. It was found that one can prevent ‘powdering’ by applying a high voltage of E₁ and ‘burning’ by choosing proper values for t₁, E₂ and t₂. The mechanism of explaining this was discussed in terms of ‘chemical dissolution’ of pore-wall during anodization and ‘healing of defects’ in the barrier layer during the period of E₂. Advantage of the new technique was described in comparison with common techniques so far adopted.

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It was found, from the double layer capacity (C) measured by using the charging-up method during the electrodeposition of nickel from a Ni(CF₃COO)₂-halide-MeOH bath, that the degree of anion adsorption increased in the order of Cl^-<Br^-<I^- and that the cathode-potential decreased in this order. This adsorption reaction was found to be irreversible. The hydrogen evolution reaction was markedly promoted by the adsorption of I^-. The adsorption of K⁺ made the cathode-potential less noble, while the adsorption of NH₄⁺ did not take place. The adsorption of anions and cations on the electrode surface influenced the electrode potential and the hydrogen evolution reaction, and hence the electrodeposition of nickel. It was found that the adsorption and electric discharge of nickel ions on the electrode surface were in equilibrium when the charge transfer reaction was a rate determining step.

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The effects of plating conditions and the concentration of suspended particles were studied on the amount of particles contained in the coatings. It was found that the amount increased with increasing current density and the concentrations of phenol resin particles and of zinc ions in the plating bath, and with decreasing relative velocity between the cathode and the electrolyte. This can be explained in terms of the collision of the phenol resin particles with the cathode. SEM observation revealed that the surfaces of the composite coatings are classified into four; 1) surfaces having no particles, 2) surfaces with some projections where phenol resin particles are caught, 3) surfaces with no projections but with more phenol resin particles, 4) smooth zinc surfaces where a number of phenol resin particles are contained. The adhesion of polymers coatings to the surfaces of the composite films is discussed in terms of the surface roughness and affinity of the particles for the polymer coatings.

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Thermal deformation is frequently observed with less heat-resistant materials to be metal-deposited in vacuum evaporation. The heat produced is supposedly due to kinetic, condensation, and predominently radiation energies. This paper describes experiments made by using thermometer and SEM to characterize the radiation heat and to assess the ways to reduce it. The evaporation source installed in a glass bell jar (10l) is a conical basket (5mm in diameter) made of tungsten filament (0.8mm in diameter). The effects of a glass cylinder sealing the filament, an aluminum plate inserted between the evaporation source and the thermometer, and an iron plate placed 1mm beneath the filament have been examined on shielding radiation heat. It was found that the radiated heat in the bell jar did not obey the radiation law, especially when the vessel was contaminated with evaporated metals, and that the heat incident upon the materials emerged not only from the evaporator but inall the directions of 360°. The heat was 140% more with the cylinder-sealed evaporator than with the bare tungsten filament. The iron plate beneath the evaporator, on the other hand, reduced the radiation heat to the extent of less than 60%; the heat was radiated only from the evaporator. SEM observations also revealed that the iron plate was effective to reduce the heat radiated onto the less heatresistant materials which were otherwise subjected to heat deformation.

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A new chemical conversion coating process using aluminum biphosphate has been proposed, and the film formation behavior and mechanism of thermally polymerized aluminum phosphate have been studied. The chemical conversion film formed by heating the aluminum biphosphate coating on zinc-plated steel sheets provides good protection against corrosion. Reaction for the film formation is a condensation polymerization caused by the dehydration of bound water in aluminum biphosphate. The experimental results obtained by using DSC, TGA, IR spectrometry and X-ray diffractometry showed that the dehydration at about 150°C is most important to form the anticorrosive film. Accordingly, for the production of the chemically converted film it is required to heat up to at least about 180°C, at which most of the dehydration reaction ends. However, the dehydration and hydration of the film occured reversibly. The reason for this rehydration is assumed that thermally polymerized film possesses a non-stoichiometrical aluminum phosphate structure.

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The effects of various phosphates on the repression of the decomposition of hydrogen peroxide and pitting have been investigated for anodizing pure aluminum and its alloys in hydrogen peroxide sodium hydroxide baths. The influence of the addition of phosphates was examined on the properties of the andioc oxide films formed in the baths. Pitting which otherwise took place during anodization in the baths was repressed by phosphates. Polyphosphates such as pyrophosphate reduced the number of pits to a greater extent than orthophosphate. Rate of the decomposition of hydrogen peroxide by polyphosphates showed a maximum with an addition of 0.05% sodium pyrophosphate. The surface roughness of the anodic oxide films produced in sulfuric acid baths was greater than that of the anodic oxide films produced in hydrogen peroxide-sodium hydroxide baths. Increasing the amount of alloying constituents resulted in a marked increase in surface roughness. The roughness of aluminum substrates was much greater than that of anodic films.

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