Annealing behavior of Au films was examined by electron microscopy. The specimens were prepared from KCN bath by electrodeposition on pure iron and quenched carbon steel, and heated to 600°C under the electron microscope with JEM-AHG stage and in an electric vacuum furnace under reduced pressure of about 10^-5mmHg. The films were 600-2, 000Å in thickness. During this experiment, annealing behavior such as recrystallization was not observed and the initial orientation of as-deposited films was maintained. When a specimen obtained on pure iron was heated at 250°C, the dislocation density decreased and the sub-grains grew up in size. The dislocation density of the films was about 5-8×10⁹cm^-2 after annealing at 360°C for 1hr. Stacking faults and micro-twins, which had been formed during electrodeposition, disappeared by heating at above 300°C. The annealing behavior of Au films electrodeposited on quenched carbon steel was identical with that of the films deposited on pure iron. Consequently, the morphology of Au films, which had been inherited from martensite, showed little change after annealing.

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The formation and morphology of electrodeposited Au-Pd alloy films, which had been deposited from single hydrochloric acid baths on single and poly-crystal Cu substrates, were studied by electron microscopy and the following results were obtained. The films formed a solid solution alloy since the early stage of nucleation, and the density for nucleation was about 3×10¹²cm^-2. The alloy nuclei of 20-40Å in diameter, which had been deposited in the early stage, showed no orientation to Cu substrate; but they gradually showed an epitaxy with the substrate in the process of their growth. The coherencies between electrodeposited films and Cu substrates were found to be of (001), (011), and (111) orientations and (111) Cu//{112} Au-Pd and ‹110›Cu/‹110› Au-Pd. In the films were observed many micro-twins, which contributed to relax the stress caused by the misfit between the film and substrate. When the current density for electrodeposition was low, plate crystals containing fine non-oriented crystallites in size of several tens of Å were formed; on the other hand, the crystals formed under a high current density were constituted by subgrains of uniform size. Under any current densities, a small number of fine nonoriented crystallites tended to coexist in the films deposited from the baths of rich in Au, but the number of such crystallites tended to increase in the films deposited from the baths of rich in Pd. The alloy constituents of electrodeposited films included more Au on the side of low current density, and the Pd content increased with the increase of current density. However, on the side of high current density, the alloy constituents of films were nearly identical with the composition of bath.

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The coagulation treatment of Cr₂(SO₄)₃-Ca(OH)₂-H₂O system was made, and the effects of CaSO₄ produced in the coagulation and the structure of sediment were investigated to make clear the coagulation mechanism of that system. The optimum condition of additional amount of Ca(OH)₂ to Cr(SO₄)₃ concentration was at the mol ratio of Ca²⁺/Cr₂³⁺=3.0, according to the following equation: Cr₂(SO₄)₃+3Ca(OH)₂→2Cr(OH)₃+3CaSO₄. The pH value was at 7-8, at which the highest rate of sedimentation was observed, and the concentration of residual Cr³⁺ in the supernatant was less than 10^-6mol/l under the above condition. When Cr₂(SO₄)₃ concentration was varied under the above optimum condition, there was a difference in the composition of sediment between higher and lower concentrations of Cr₂(SO₄)₃. On the side of the concentration lower than 10.2×10^-3mol/l, water content and chromium hydroxide concentration were high, but calcium sulfate concentration was low. Whereas, on the side of the concentration higher than 12.75×10^-3mol/l, the inverse results were obtained. Consequently, it was recognized that the relation between water content and calcium sulfate concentration in the sediment was in inversely proportional. After calcination of the sediments, the structures of these hydroxides were investigated by DTA. X-ray diffraction, and infrared absorption spectroscopy. The results of investigations showed that the structure of sediment on the lower side of concentration was chromium hydroxide containing Ca²⁺ and SO₄^2-, and that on the higher side of concentration was the mixture of chromium hydroxide and CaSO₄·2H₂O.

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The authors pursued the change in built- in color of alumina film anodized in sulfuric acid according to pulse shape; and its coloring mechanism was compared with those of the films obtained from organic acids such as oxalic acid oxidation film, Kalcolor film, and oxalic sulfuric acid oxidation film. The causes of coloring of these films were studied by X-ray microanalyzer and X-ray diffraction for the samples before and after the heat-treatment. The following conclusions were drawn from the above results of experiments. When aluminum was anodized in single sulfuric acid bath by a current with pulse shape of msec, unit in pulse width, a brownish colored film was obtained. The decreasing order of electrolytes for coloring tendency determined by the relation between film thickness and color difference (NBS) was arranged as follows: mixed acid (sulfuric+organic)>sulfuric acid>oxalic acid. Foreign atoms in the aluminum material were likely to decrease the brightness of colored film.

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This paper describes the relation between the constituents of aluminum alloys, JIS 1080-H18, 1100-H24, 5052-H34, 2017-F and 2017-T3, and the formation of abnormal layer in anodic oxidation coatings, which are obtained by electrolyzing at -5°C for a prolonged period in a bath of H₂SO₄ containing H₂C₂O₄. Concerning high-purity aluminum (1080) abnormal phenomena was noticed neither in V-T curve nor in coating structure observed by optical microscope. However, abnormal layers of 40μ and 10-20μ were found with 1100 and 5052 alloys respectively. The layer is likely to be observed more often with high strength alloy (2017-F etc.) containing more precipitations of CuAl₂ than 2017-T3 alloy. Swells like island were found by scanning electron microscope on the surfaces of anodic oxidation coatings of 1100, 2017-F and 2017-T3 alloys having the abnormal layers. Excess oxygen in anodizing reaction of prolonged electrolysiss where the current is locally concentrated, makes the coatings thick but partially leaves surface swells. It was found that the cell size of anodic oxidation coatings of pure aluminum and aluminum alloys is linearly proportional to the bath voltage regardless of the thickness of the coatings. Thickness of barrier layer was also proportional to the anodizing time, if the electrolysis was conducted at constant current density and insulation of the barrier layer is high enough. As to 1100, 2017-F and 2017-T3 having the abnormal layers, a rise of leakage current was recognized at low voltage after a break-down of the insulation of barrier layer.

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