The early stage of oxide film formation on aluminum in sulfuric acid solutions was studied by measuring transient anode potential in the second electrolysis.
The significance of maximum potential appeared in the early stage of polarization was explained in relation to the dissolution of barrier layer on anodic oxide film of aluminum.
The results obtained were as follows.
1) It was found that the maximum value of anode potential on potential-time curves was independent of the current density.
2) When high electric field was applied across the barrier layer during electrolysis, the rate of dissolution of that layer was expressed by the following equation.
-dx/dt=Kx……for constant concentration of sulfuric acid
or -dx/dt=K1/Tx……for constant temperature of the electrolyte during electolysis

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It was found that reaction products from amines and epoxides were suitable to be used for brighteners in zincate baths.
A typical synthetic process was a reaction of 1mol of ethylene diamine with 1mol of epichlorhydrin with no addition of water at 80-120°C. As for brightener, 50% aqueous solution of the above reaction product was used.
The reaction product was a polymer, which was yellow colored and soluble in water, but insoluble in alcohols or ethers. During the reaction, epoxy group was converted into hydroxyl group, and chlorine in epichlorhydrin was converted into amine hydrochloride by dehydrochlorination.

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The microstructures of anodic oxide coatings of aluminum, which had been treated for coloring in aq. solutions of various inorganic salts, was studied with an electron microscope and an electron microdiffractometer of high resolving power.
Aluminum had previously been coated with porous anodic films by the electrolysis in sulfuric acid bath for the following 4 experiments.
(1) By electrolysis of the anodic films with alternating current in aq. solution of NiSO₄, Ni and NiO crystals were deposited in the coatings and the color of films was changed to brown.
(2) By the same treatment as (1) in aq. solution of CuSO₄, the films turned to reddish brown color and the crystallization of copper was observed in the layers.
(3) Reddish yellow films were observed when the coatings were continuously dipped in aq. solution of (NH₄₎₃ Fe(C₂O₄₎₃, and the precipitations of Fe₃O₄ was observed in the oxide layers.
(4) When the coatings were alternately immersed in aq. solutions of Cd(Ac)₂ and (NH₄₎₂S, the formation of CdS pigments was observed in the yellow coatings.

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The phase changes in electroless Ni-B deposits during heat treatment are reported in this paper.
The experiments were conducted by thermal and X-ray analyses in nearly the same method as in the previous reports.
The results obtained were as follows:
1) The hardness after heat treatment of electroless Ni-B deposits exhibited its maximum at about 400°C as shown in the curves.
2) Exothermic change was observed at about 270°C in the curves plotted by thermal analysis of electroless Ni-B deposits.
3) It was possible to comfirm the formation of nickel boride at the temperature of exothermic change, judging from the X-ray diffraction pattern of electroless Ni-B deposits.

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Investigations were made on the formation of chelate by the reaction between cupric ion and ethylene diamine (En), and the effect of pH on the structure of chelates.
The following results were obtained.
1) The chelate compound (CuEn)²⁺ was formed by the reaction between En and cupric ion in the pH range of 3.5-5.5 and the compound (CuEn₂)²⁺ was formed in the range of above 6.0. However, in the range of 5.5-6.0, the both complex ions, (CuEn)²⁺ and (CuEn₂)²⁺, were formed.
2) Bright deposit of copper was obtained on steel with good adhesion from (CuEn₂)²⁺ chelate solution.
The optimum condition of the electrolysis was as follows.
CuSO₄·5H₂O……75-125g/l pH …… 6.5-8.7
En ……40-65g/l Temperature …… 10-50°C
Na₂SO₄·10H₂O …… 50g/l Cathodic current density…… 1.5-2.5amp./dm²
(NH₄₎₂ SO₄ ……50g/l
The current efficieney under the above condition was above 95%.

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Investigations were made on the relation between salt bath nitriding and crystal grain size of steel, which had been annealed at various temperatures and refined.
The results obtained were summarized as follows.
(1) The relation between nitriding temperature and hardness was as follows.
After some specimens of SACM 1 and S45C steels, having various crystal grain sizes, were subjected to nitriding, the change in their surface hardness did not depend on their initial grain sizes, but was found to be almost in the same trend for every size.
However, the depth of hardened layer was decreased with the increase in crystal grain size.
(2) The surface of every specimen was mose rough with the rise in nitriding temperature.
(3) The surface hardness after re-heating for diffusion was indifferent to the crystal grain size, but was in the same trend for every specimen.
(4) The fatigue limit was more improved when the grain size was finer.

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