The authors investigated the mechanism of the formation of Au-films, which had been thoroughly precipitated and developed all over Fe single crystals by galvanic substitution in hydrochloric acidic auric chloride solution. The following results were obtained.
1) The Au-films consisted of plate crystals, which had been coherently deposited all over the Fe surfaces, and needle crystals, which had been non-coherently deposited all over the plate crystals.
2) The growth of needle crystals was more retarded with the increase in the concentration of hydrochloric acid in the solution.
3) The coherencies between plate crystals of Au and Fe surfaces were found as follows.
(001)Fe||(001)Au [110]Fe||[100)Au} (1) (110)Fe||(110)Au [001]Fe//(110)Au} (2)
4) The plate crystals were macroscopically observed to be simgle crystals, but by electron microscopy and electron diffruction they were observed to be sub-grain boundaries rotated by the angle of less than about 5°.
5) It was considered that many defects were found in plate crystals, but very few in needle crystals.

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On Au plate crystals precipitated and developed over Fe surface by means of galvanic substitution of hydrochloric auric chloride solution, the initially precipitated states, lattice defects, and microstructure were observed by electron microscopy and discussed over the following items.
(1) In the initial stage, the Au crystals observed were micro-particles aggregates of micro-particles being connected one another, and the coherency between the Au crystals and Fe substrate was not still observed.
(2) With the lapse of dipping time, the Au crystals were developed to network structure and stable coherency was formed between Fe substrate and the Au crystals; then, turn spots were observed in diffraction N-patterns.
(3) The perfectly developed plate crystals consisted of many sab-grains of about 100-700Å in diameter and many micro-turns.
(4) The micro-turns were separated from each other by the distance of 50-150Å and they were about 17-30Å in width.
(5) In the plate crystals, there were formed some particles having different crystal orientations from that of Au crystals.

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The effects of plating on a screw were examined with respect to the factors of two adjacent faces; i.e., (1) the effect of the distance between the both faces and (2) the effect of the distance of each face from anode. Thickness distribution of plating on the screw was measured and the following results were obtained.
(1) The former effect
The following relation was found between the adjacent resistance of circuit and the distance between the adjacent faces.
R=R'+C/l², where l>3mm.
The current was expressed by the following formula under a set voltage; I=alogl+b
(2) The latter effect
The cathode farther from anode had higher potential than the other cathode, when l>2mm. (l is the distance between faces, or cathodes).
The ratio of thickness of plating between top and root of the screw was linearly proportional to the cathodic current dencity.
The distribution of plating thickness on the screw obtained from Watt's bath most depended upon the former effect, but the dependence on the latter effect and the effect of edge were very little.
High concentration of bath or low current density (low voltage) was effective for uniform plating on screws or other products having narrow slits.
The following conditions shall practically be planned for obtaining uniform plating.
(a) The distance between the adjacent faces shall be more than 10mm.
(b) Depth of pores or pits shall be less than 2mm.
Leveling power depended upon the effects of edge, and throwing power depended upon the above two effects relating to faces.

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Aluminum foil of 99.99% in purity was anodized in aqueous solution of sulfamic acid (1-10%, 20-50°C) under d.c. of 0.1-1.5A/dm² and local corrosion of anode during anodizing was examined. It was found that the corrosion more occurred, resulting the decrease in coating ratio at lower temperature or lower concentration of electrolytic bath or under higher current density. Loss of metal during anodizing was independent of the occurrence of corrosion. The critical current density for the occurrence of corrosion depended upon surface conditioning of aluminum. The addition of 0.2-1.0% of sodium bichromate to 5% sulfamic acid bath at 30°C was effective for preventing the corrosion. However, the addition of 0.1% of sodium bichromate, 0.1-1.0% of quinoline, or 0.1-0.5% of sodium hexametaphosphate was detrimental to that prevention.

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An analysis of flame-sprayed BaTiO₃ coatings was conducted by means of diffractometer and specific gravity method for further determination of structure of the coatings. The results obtained were as follows.
(1) When the distance for spraying was longer, the content of glassy phase was generally larger; for the distances of 6cm (minimum) and 18cm (maximum), the contents were 16.2 and 64.6%, respectively.
(2) Each coating consisted of crystalline BaTiO₃ having each distinct ratio of axes (c/a). The main ratio largely depended upon the spraying distance; it decreased with the increase of the distance.
(3) The contents of BaTi₃O₇, BaTi₄O₉, other hexagonal crystals, etc. somewhat decreased by flame spraying.
(4) When the spraying distance increased, the specific gravity of coatings decreased, but the porosity increased.
The value of porosity was calculated at 6% at minimum when the presence of glassy phase was neglected, but it was at 1.7% when that presence was taken into account.

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