Effects of composition and pH of electroless cobalt plating bath on structure of cobalt plating films were studied mainly by X-ray diffraction method. Cobalt deposits of electroless plating had polycrystalline structure of α-cobalt with close packed hexagonal lattices, and the grain size and orientation of the crystals greatly depended upon the composition and pH of the plating bath. Deposits of finer grain size were obtained, when the growth of crystals was inhibited by adsorbed hypophosphite ions or reduced phosphorus atoms adsorbed on the surface. As the formation and diffusion velocities of cobalt atoms on the crystal plane controlled preferred orientation of cobalt crystals, the deposits with fiber structure were produced.

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Mechanism of synergistic effects between amines and anions as inhibitors was studied from the curves showing the relation between electrode potential and differential capacity of Fe-HClO₄ system containing mono-ethyl amine, tri-ethyl amine or di-methyl aniline together with or without bromide or propionate. The amines adsorbed on iron surface in acid solutions differed in their froms as to the availability of unshared electron-pair of N-atom and also to negative field intensity produced by preadsorbed anions.
In Fe-HClO₄ system containing no other anions than ClO₄^-, amines were always adsorbed on iron surface as ammonium cations only in cathode potential region. However, in Fe-HClO₄-Br^- system, primary amines were adsorbed as ammonium cations over the pre-adsorbed Br^-, while tertiary or ring amines were adsorbed as amine molecules together with Br^-. In Fe-HClO₄-propionate system, all kinds of amines were adsorbed as ammonium cations together with propionate anions, but not as amine molecules.
From the above findings, the mechanism of synergistic effects between amines and anions were explained as co-adsorption or overlap adsorption of these additives on iron surface.

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Rates of Dissolution and Formation of Oxide Films
For the purpose of studying hard anodizing process, the rates of dissolution and formation of oxide films on aluminum were examined in the baths consisting of mixed solutions of sulfuric, oxalic, and citric acids.
The results obtained were as follows.
(1) The rate of dissolution of films in electrolytes decreased with the fall of temperature. The dissolution of films remarkably decreased by the addition of oxalic acid to sulfuric acid.
(2) The rate of formation of films in sulfuric-oxalic acid baths was maximum when the concentration of sulfuric acid was high and that of oxalic acid was low. However, the concentration of the former was necessarily maintained at lower than 10-20g/l, or it would give an uneven film at more than 0.1% (by weight) against the latter.
(3) The rate of formation increased by the addition of more than 30g/l of citric acid to sulfuricoxalic acid baths. In particular, the rate remarkably increased when the concentration of sulfuric acid was less than 10g/l and that of oxalic acid was also low.
(4) The rate of formation was maximum at around room temperature, which were most effective for obtaining hard anodized films.
(5) It was observed that the rate of dissolution during electrolysis increased twofold with each temperature rise of 25°C, which was very smaller than that in other baths. However, the value was 2-5 times as large as that during immersion.

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The object of these experiments was to obtain Fe-Ni-Cr alloys, having higher corrosion resistance. The first step for this object was the investigation on the deposition of Fe-Cr alloys, which is reported in this paper.
From the standpoints of abating the public nuisance, the study was performed with a bath containing an electrolyte of sulfate, and the following results were obtained.
(1) A bright deposit of Fe-Cr alloys, containing about 20% of chromium, was obtained.
(2) Current efficiency was 20-30%.
(3) The hardness of the deposit was above 700 in Vickers value.
(4) The addition of aluminum sulfate was effective among inorganic addition agents.
(5) The optimum condition of bath composition and electrolysis available was as follows.
Ferrous sulfate 83g/l Sulfuric acid 30-50g/l
Chromic sulfate 140g/l pH 1.8
Urea 180g/l Current density 30-35A/dm²
Ammonium sulfate 265g/l Temperature 40-50°C
Sulfuric acid was used for adjusting pH.

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The change in dimensions after heat treatment, in most cases, has been expressed by elongation or shrinkage obtained by measuring the distance between two sides of the specimen.
In this paper, change in dimensions and change in profiles on sections and cubic surfaces after heat treatment by oil cooling, air cooling, marquenching, etc. were studied by using micrometer and surface roughness gauge.
Three kinds of tool steels (SKS 2, SKD 11, and SKS 31+Mo in JIS) were selected and worked into rectangular parallelopipeds of 150×45×22mm for test pieces.
The results obtained were as follows.
(1) The surface profile of each face changed in three dimensions. For example, after SKS 2 was oil cooled, two corrugated ranges of mountains appeared in one direction and only one range in the perpendicular direction on 150×22mm face. However, on 150×45 face, there appeared V shaped corrugations in one direction and one range of mountains in the perpendicular direction.
(2) Change in dimensions was the largest in SKS 2, and next in order were SKS+Mo and SKD 11.
(3) SKS 2 showed the best results among the test pieces on which profiles were symmetrically distorted. The surface profiles were more accurately measured with roughness gauge than micrometer.

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