A study was made on electrodeposition of nickel from nickel ethylene-diamine chelate solution for the purpose of determining the optimum condition of electrolysis.
The following results were obtained.
(1) Ethylene-diamine (En) and nickel ion formed chelate compound of Ni(En)₂ in pH range of 6.0-7.8 and of Ni(En)₃ in the range of above 7.8. The latter compound Ni(En)₃ was found to give no nickel deposit on electrolysis.
(2) Bright nickel deposits were obtained from chelate solutions of pH 6.0-7.2 and the brightness was found to increase with the increase of the addition amount of En, but current efficiency decreased with the increase of En.
The optimum condition of the electrolysis was as follows.
NiCl₂⋅6H₂O(or NiSO₄⋅7H₂O)……0.4mol/l
En……0.8-1.0mol/l
pH……6.0-7.2
Temperature……room temperature
Current density 0.5-1.25amp./dm²
The current efficiency was about 80% at the density of 0.5amp./dm² and about 60% at 1.25 amp./dm².
(3) The nickel deposits obtained from Ni-En baths were fine grains in crystal structure with preferred orientation of (111).

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Paintin g properties on various zinc-coated surfaces, such as surfaces of electroplated zinc, hot dipping galvanized zinc, flame sprayed zinc (metallikon) etc. were studied.
The results showed that corrosion resistance of painted surface on base steel was higher than that of zinc-coated+painted surface when the surfaces were non-scratched. Accordingly, the plating may be assumed as foundation coat for rust prevention.
However, in case of scratched surfaces, corrosion resistance of the latter was higher than that of the former. Then, the latter would be more advantageous in consideration of repair painting and life.
Corrosion and adhesive properties of coated zinc surfaces mainly depended upon conditions of pretreatment before coating and sorts of paints. In general, it was shown that the coatings of acrylic resin paint on chromate treated zinc surface gave excellent properties.
The above results were obtained by salt spray corrosion tests. The results of long term out-door exposure tests will be reported later.

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A modified process of electrodeposition of tungsten-iron alloys from a tartrate bath was proposed to produce more uniform and thicker deposit of superior quality, containing as high as 43wt.% of tungsten.
This process was developed with respect to the following three conditions.
(1) The most preferred concentrations of tungsten and iron in the plating solution were such that the concentration of iron was extremely low (0.047mol/l) and that of tungsten was high (0.213mol/l) for preventing co-deposition of powdered iron and yielding alloy deposit of uniform quality.
(2) The setting of soluble anodes combined with an insoluble anode under suitable current densities was favorable to keep the concentrations of metallic ions constant in the bath.
(3) The single use and a slight excess (0.42, 0.53mol/l) of ammonium tartrate as a complexing agent were more effective for preventing iron anode from passive state.

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It is well known that electrolytic zinc in aqueous solution of pH 6-12.5 has low corrosion rate, because the film of corroded zinc salt is stable, which is not dissolved and remains on the surface.
The investigation was undertaken to compare the corrosion characteristics among the following four kinds of products:
(a) Castings of electrolytic zinc.
(b) Castings of spelter containing 1% of Pb.
(c) Coating which has been galvanized in zinc bath containing natural admixture of 0.04% of Fe.
(d) Coating which has been galvanized in zinc bath containing natural admixtures of 0.04% of Fe and 1.05% of Pb.
The experiments were conducted by electrochemical method in 3% NaCl solution of pH 6-7, in which the surface film is rather stable and prevents diffusion of dissolved oxygen (the oxygen accelerates corrosion as mentioned above), and also in running water having resistivity of 7000Ω-cm.
Corrosion rate was determined by cathodic polarization curve obtained by galvanostatic method at the beginning of and at 1000hr after dipping. In addition, the change of corrosion potential with time was also measured for a long period.
As the results, it was found that the effects of iron and lead were negligibly little on all castings and coatings, for which protective film compactly adheres to the surface. Corrosion rate was about 0.1mm/year in 3% NaCl solution and 0.04mm/year in running water.
Accordingly, Corrosion resistance of galvanized steel produced by practical hot dipping (low carbon steel is used for galvanizing tank, of which a layer of lead lies at the bottom) was independent of the grade of zinc in the range of pH, where protective film was stable.

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