Etch-pits of various shapes are formed when aluminum is anodically dissolved in chloride solutions. Studies were conducted on predicting by computer simulation the morphology of etchpits formed under various conditions.
A local dissolution model was applied to pit growth in the direction of pit depth, in which it was assumed that active dissolution of Al takes place at the tunnel tip and that the pit wall is covered with passive film. Current density was assumed to be proportional to the growth rate. The computer simulation showed that pit depth increases in temperature, current density, and etching time, and with a decrease in pit diameter.
Aluminum specimens of 99.99% purity were electrolytically etched in HCl solutions, and the empirica results showed good agreement with the simulation. Equally the theoretical growth rate showed good agreement with the empirical rate.

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When electroless plated silver was used as the undercoating on 96% Al₂O₃ ceramics, an improvement in the adhesion of copper plating on the ceramics was obtained. SEM photographs confirmed that electroless silver plating was useful in obtaining smooth and uniform electroless copper plating. Furthermore, the adhesion was greatly increased by etching the ceramics by both mechanical and chemical techniques.
It was found from electrochemical measurements that the mechanism of electroless silver deposition was explained by the mixed potential theory. The effect of additives-3, 5-diiodotyrosine and potassium iodide-was studied using i-E and E-t curves. The 3, 5-diiodotyrosine stabilized electroless silver plating baths by decreasing both the rate of silver deposition and the creation of silver nuclei, which grow to silver particles in the bath.

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This study concerns development of material for welded cans made of 0.7-0.8g/m² dewy spread lightly tin coated steel. It has been well known that more than 0.1g/m² of free tin results in good weldability. Low-tin steel, however readily forms alloys during baking, resulting in degradation in both weldability and corrosion resistance. These properties were improved by: 1) covering the steel surface with a continuous dense layer of Fe (Ni)-Sn alloy; 2) distributing the tin like islands a few micrometer in diameter to provide a surface coverage of 10-50%; 3) forming a uniform chromate film, consisting of 4-10mg/m² chromium as Cr^EC and 6-15mg/m² chromium as oxide. The material, thus produced exhibits out-standing results weldability and corrosion resistance and it could replace tin plate as a material for welded cans.

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The double layer effect of an electroless plated CoNiReP alloy medium in combination with an electroless plated NiP underlayer was investigated by a system consisting of a flexible disk with a VTR ring head (gap length 0.3-0.4μm). The underlayer of NiP improved the recording characteristics and the D₅₀ changed from 76kFRPI (single layer) to 85kFRPI (double layer). When using a pH6 NiP underlayer of amorphous state, even the addition of a film only 0.03μm thick effectively improved the output voltage. The increase in the thickness of the underlayer made the second peak of higher recording density clear. When using a pH 10 NiP underlayer of quasi-soft magnetic crystalline state, the same improvement was observed, and an additional increase in output voltage due to the so-called “double layer effect” was observed even at a thickness of 0.03μm. In contrast to the pH 6 NiP underlayer, the improvement at higher recording density by underlayer addition was reduced as underlayer thickness increased. The above results were discussed from the viewpoint of variations in magnetic medium structure.

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Zinc was electrodeposited on pure silver plates 1mm in thickness, which were then annealed at 473K in an argon atmosphere in order to obtain a corrosion resistant Ag-Zn alloy layer.
Observasion after annealing revealed a η phase (the solid solution of Ag in Zn), and three intermediate phases, ε, γ and ζ. After prolonged annealing the η solid solution layer supplied zinc atoms to the inner intermediate phase layers, thereby becoming porous.
When the electrodeposited zinc layer was 10μm in thickness, difficulty of the supply of zinc atoms from the porous layer lying on the specimen surface resulted in disapperance of the ε phase layer after 83ks annealing, and of the γ phase layer after 115ks annealing.
The porous surface layer was easily removed by buff polishing. The silver plates with zinc deposited layers 200μm in thickness were clamped to prevent void formation and used as a diffusion couple. The interdiffusion coefficient obtained were: 7.9×10^-15-3.7×10^-16m²/s at 13-30 at% Ag in the ε phase, 6.0×10^-15-4.0×10^-15m²/s at 34.9-37.9 at% Ag in the γ phase and 1.7×10^-14-6.8×10^-16 m²/s at 46.9-59.0 at% Ag in the ζ phase.

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Outdoor exposure tests were carried out on four kinds of resin coatings on steel (polyester, acrylic, polyurethane and melamine) for one year at five locations in Japan-Asahikawa, Tsukuba, Tokyo, Choshi and Naha-and the relationships between the physical-chemical changes on the surfaces of the films and weather factors were evaluated. It was found that polyester resins did not deteriorate under the tests but that the acrylic, polyurethane and melamine resin specimens showed chalking, discoloration and decrease of gloss retention. The degree of deterioration differed in accordance with the test site. Deterioration was minimal at Asahikawa, which is located in the north of Japan, but was marked at Naha in the south. Occurrence of the -CO radical and increases in the amount of oxygen on the deteriorated surfaces of the acrylic resin were noticed. It was found that air temperature and humidity affected the deterioration of the films, but the product of mean air temerature and mean absolute humidity showed the effect on the deterioration more clearly than the individual values. While it was found that air temperature, humidity, precipitation and ultraviolet rays all were factors in the deterioration of the films, the correlation between the individual factors and film deterioration was low, and it was assumed that film deterioration was caused by the synergistic effect of all the factors.

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