The microstructure and the phase of Au-Sn and Ag-Sn alloys electrodeposited from cyanide baths were investigated by X-ray diffraction and transmission electron microscopy. On the solubility of α solid solution and the range of intermediate phase ζ Au-Sn and ζ Ag-Sn of the electrodeposited Au-Sn and Ag-Sn alloys in room temperature, the solubility was decreased and the range was shifted to Sn side by about 10at% as alloy composition in comparison with the thermally equilibrium alloys. The intermetallic compounds of AuSn, AuSn₂, and AuSn₄ were electrodeposited, but the superlattice ε phase in the Ag-Sn alloy was not formed. In both of electrodeposited Au-Sn and Ag-Sn alloys, coring structure by peritectic reaction could not be observed, instead, the homogeneously mixed structure consisting of α and ζ phase was observed. These α and ζ crystallites grew epitaxially with substrates, and no specific habit relationship between α and ζ crystallites was found. The morphology of the crystallites was also influenced by substrates; that is the slender ζ-crystallites in the Au-Sn alloy deposited on the (011) Cu substrate were elongated in the [011] Cu substrate direction. This phenomenon was caused by misfit between (200) Cu and (0111) ζ plane along the [100] Cu direction.

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Porous anodic oxide films formed on Al in an oxalic acid solution were hydrated for various periods by reaction with hot water. As reported earlier, the hydrous oxide is formed on the entire surface of the pore-walls to fill up the pores in about 10min, and then the hydration slowly continues from the outer surface so that the outermost part of the film becomes completely hydrated. Using gravimetric data and assuming the composition and density of the hydrous oxide to be Al₂O₃⋅2H₂O and 2.6, the thickness of the fully hydrated portion of the film, H_hy, the thickness of the film portion containing the unhydrated pore-wall, H_ox, and the thickness of the unhydrated pore-wall, δ, were calculated. In another series of experiments, the hydrated films were re-anodized with constant currents, i_r, of 0.01 and 0.5mA/cm² in a neutral borate solution to examine potential-time characteristics. For the smaller anodizing current, the steady potentials are related to the thicknesses of the barrier layers remaining unhydrated; they agree well with those estimated from capacitance measurements. Re-anodizing with the larger current causes dehydration of the hydrous oxide in the pores at the barrier layer/hydrous oxide layer interface, and voids produced by the dehydration are filled up with new oxide formed by the transport of Al³⁺ ion through the barrier layer. The growth of the barrier layer is reflected in the voltage-time characteristics. The transport number of Al³⁺ ion, T_Al³⁺, was found to be 0.24. Using this value, Hog was estimated from the voltage-time curve. The values of H_ox obtained as a function of the hydration time, t_h, were in good agreement with those estimated by gravimetry.

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The effect of the Mo content on the corrosion behavior of Zn-Mo electrogalvanized steel was investigated by polarization measurement and ESCA. The results obtained are as follows: 1) The corrosion potential of Zn-Mo electrogalvanized steel in 5% NaCl was temporalily shifted to more noble potential than Fe/Fe²⁺ potential with the dissolution of Zn and the degree of the potential shift was proportional to the Mo contents in the deposit. The initial corrosion current of Zn-Mo electrogalvanized steel in 5% NaCl was higher than that of the conventional electrogalvanized steel, and the corrosion current showed a tendency to decrease with time. 2) The Mo (OH)₃ formed on the surface of deposit in corrosive solution prevented the dissolution of Zn in the deposit. Even if all of Zn in the Zn-Mo deposit was dissolved, MoO₂ remained on the surface of steel and prevented the corrosion of base metal. 3) The Mo oxides (Mo(OH)₃, MoO₂) in contact with Zn in the deposit or base metal does not seem to be oxidized because of the galvanic action of Zn or Fe, and the corrosion of Zn in the deposit or base metal was accelerated to form the insulater of oxide layer between Mo oxides and Zn or Fe. The Mo oxides were not influenced by base metal and were oxidized further more to show smaller corrosion protective effect.

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Effective organic brighteners on the electroplating of tin-nickel alloy from an acidic chloride bath were found, and the electrochemical behaviors were investigated. When 3-4g/l N-1-naphthylethylenediamine dihydrochloride and 20vol% Ethylene glycol were added to the bath consisting of 30g/l SnCl₂⋅2H₂O, 300g/l NiCl₂⋅6H₂O and 30vol% HCl, clean bright alloy deposits over most of its length of Hull cell panel were obtained at 1A and 65°C. The potential of the alloy deposition in the bath shifted to more noble potential than that of the parent metals. Then, the hydrogen evolution potentials on the alloy deposits were compared with those obtained in the additive free bath. Ethylene glycol behaved as the assistant of the brightening agent. The electrolyte was stable for prolonged use and was readily controlled. The impurity ions in the plating solution, Cu⁺ of 0.1g/l, and Zn²⁺, Fe²⁺, and Cr³⁺ of 2.0g/l had little effect on the brightness.

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