Since copper plating is mainly used as a base deposit for decorative platings of nickel, chrome, gold, etc., copper deposits are not only required to be brilliant, but should have a good uniform luster, which can further be brightened and leveled to the highest degree by the subsequent bright plating. However, there have been few reports on leveled copper deposits from cyanide baths and the mechanism of such leveling action has not yet been clarified. Then, the author has investigated the effects of various plating conditions and additives on leveling action of copper deposits from cyanide baths.
The results were summarized as follows:
1) There were little effects of concentrations of copper and free cyanide in the bath, bath temperature, stirring, and interrupted current on leveling action.
2) The use of periodic reverse current exhibited excellent results.
3) Leveling action was improved in some degree by the operation with extremely low current density.
4) There were little effects of additives on leveling action for micro-grooves of more than 10μ in depth.

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Titanium tetrachloride carried by argon gas was reduced by sponge titanium to lower chloride; and then, the chloride was spread over hign carbon steel to make titanium carbide film formed on the steel surface at 850-1000°C.
The properties of titanium carbide layer formed at above 900°C were fairly good in adhesive power and no porosity. The thickness of the layer attained to about 14μ at 1000°C for 225min. with considerably large leveling power. The growth rate was in accordance with the Law of √t and the activation energy was found to be 48Kcal/mol. The rate determining step was supposed to be the diffusion process of carbon from high carbon steel. As the results of electron probe microanalyzer, it was found that the intensity of titanium diffraction in titanium carbide layer was 80-85% of that of pure titanium. That value corresponded to the concentration of titanium in titanium carbide in consideration of that titanium lattice points were partly replaced by 2-7% of iron impurities.

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It is significant to examine the properties of electrodeposited silver-copper alloys for electrical contacts. At first, plating conditions and bath compositions for electroplating of the alloys were studied. Since cyanide solutions were widely used for silver or copper plating, a cyanide bath was used in this study. Two kinds of anodes, consisting of copper and silver, were used. One was that, in which silver was connected with copper at the same electric potential (designated as “non-separated anode”) and the other was that, in which connected at different electric potentials (designated as “separated anode”).
The results obtained were as follows:
(1) Bath compositions agreed qualitatively with the calculated results from equilibrium dissociation constant.
(2) In the experiments of “separated anode”, each of silver and copper was dissolved, corresponding to anode current under optimum conditions, because each potential of silver and copper anodes could be controlled.
(3) Plating conditions and bath compositions for good finishing were investigated with “non-separated anode” as follows:
metallic silver 1.29g/l, metallic copper 47.7g/l, K₂CO₃ 18.2g/l, free KCN 1.7g/l, pH=12.4, cathode current density 0.10-0.33A/dm², cathode current efficiency 55-91%. Chemical compositions of deposited layers were in the range of 20-92% of Cu.
(4) The above investigations with “separated anode” were as follows:
metallic silver 0.15g/l, metallic copper 65.1g/l, K₂CO₃ 18.1g/l, free KCN 1.9g/l, pH=12.3, anode current density of silver 0.01-0.20A/dm² and that of copper 0.72-0.92A/dm², cathode current efficiency 90-96%. Chemical compositions of deposited layers were in the range of 79-96% of Cu.

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