The current efficiency is an important matter in plating shops; that is, the relation between the amount of deposited metal and plating time or consumption of electric power, etc. at cathode and the relation between the amount of dissolved metal and maintenance of bath composition at anode. However, there have been few reports on current efficiency at cathode or anode of copper cyanide plating baths. The author determined the current efficiency at anode or cathode in the baths by changing the plating conditions such as concentrations of primary chemicals, electrolytic conditions, and additives.
The results were summarized as follows.
(1) Increase of copper concentration and decrease of free cyanide concentration improved the cathode efficiency, but concentrations of alkali metal carbonate and hydroxide had little effects.
(2) The cathode efficiency was remarkably improved at high temperature and with air agitation, but it decreased at high cathode current density; and little effects were given by employing PR current.
(3) Most additives had little effects on the cathode efficiency. However, the addition of compounds containing sulfur and having good effects on brightness, such as thiosulfate, thiocyanide, etc. improved the cathode efficiency.
(4) Contrary to the cathode, at anode, increase of concentration of both copper and free cyanide improved anode efficiency and also good effects were given at high temperature, with air agitation, and by employing PR current.
(5) As to additives; addition of compounds containing sulfur also had good effects on the anode efficiency as the same as at the cathode.
(6) As to anode materials; electrolytic copper showed better results for improving the anode efficiency as compared with rolled copper and phosphor copper.
(7) As the results mentioned above, it may be suggested that the cathode efficiency is mainly controlled by concentration of cuprons ion near the cathode surface, and the anode efficiency is mainly controlled by passive film produced on the anode surface.

抄録全体を表示

The conditions of polishing of 18-8 stainless steel have mainly relied upon experimentations. There have been no definite values as to the force exerted in polishing. As the results, too strong force caused overheating, or too weak force could not remove imperfections from the surface.
The object of the authors' study was to technically determine the exerting force on emery cloth and polishing compounds of grease-base which are used in manufacturing table and kitchen wares in Japan.
The polishing wheel used in this experiment was made of canvas; its diameter was 1.1 in., its peripheral speed was 6, 000-7, 000ft./min., and its grain size of polishing grit was #180.
The following results were obtained.
1. When the force of 7.1lb./in² was exerted in dry polishing, polishing burn was caused; but the burn was not caused for the force of 24lb/in² when tripolite was used as lubricating abrasives.
The depth of polishing was 10μ in the former case and 30μ in the latter case.
2. The maintenance time of buffing was longer when the grain size of tripolite was finer or neutralization value of the grease was larger.

抄録全体を表示

The following surface treatments were conducted on cast iron by the following processes; i.e., manganese phosphate coating, electroless lead plating on manganese phosphate coating, electroless lead plating, and copper-tin alloy immersion plating. Then, frictional and wear resistances of the above coated surfaces were studied.
The results obtained were summarized as follows.
(1) These surfaces showed lower frictional coefficients, and particularly, manganese phosphate coating showed the lowest coefficient by its excellent property of preventing adhesion of metallic substances.
(2) Manganese phosphate coating showed very high wear resistance due to its high scuff resistance.
(3) Electroless lead plating on manganese phosphate coating showed higher wear resistance than manganese phosphate resistance.
(4) When the rotor coated with manganese phosphate or electroless lead plated rotor on manganese phosphate coating was combined with the stator which had been immersion plated with copper-tin alloy, showed higher wear resistance.

抄録全体を表示

Structure and constitution of titanium carbide layer formed on mild steel were analyzed by microscope, X-ray, electron-probe microanalyzer, and microhardness tester.
It was found that the adherence of titanium carbide layer to substrate was perfect when the thickness of intermediate cobalt layer was more than 10μ. When the cobalt layer was above 20μ, the boundary layer between titanium carbide and Co-Fe alloy was more than 10μ and β-Co-Fe alloy was detected by X-ray diffraction on carbide surface.
When the coating was formed at 950°C, the concentration of iron at the point 20μ away from the interface was limited to under 0.7%, and the concentration of cobalt was limited to under 0.8%.
Derived from X-ray diffraction data, titanium carbide was detected at the coating temperature of above 900°C, though the temperature was limited to above 950°C for obtaining a strong layer.
By measuring microhardness, the values of 2400-3700kg/mm² were obtained. It was confirmed that the hardness was apt to be higher with the rise of coating temperature. A coating formed at 950°C under high partial pressure of titanium tetrachloride (0.24 atm.) had selective orientation of {110} and {113} planes, and its value of microhardness was 3200kg/mm².

抄録全体を表示

The mobilities of resins and pigments were determined, respectively, by changing pH, temperature, concentration, current density, and conditions of preparation for electrophoretic painting bath. In addition, electrode potential was chronopotentiometrically traced under constant current painting.
The following results were obtained.
The mobilities of paints were most affected by temperature. It would be due to the fact that conductivity largely depended upon temperature. Furthermore, mobilities had effects on the increasing rate of electrode potential at the end of electrophoretic painting. The ionization or oxidation of electrode metal should be unavoidable especially at the end of electrophoretic painting. It was found that the above defect would be prevented to some extent by changing the bath composition.

抄録全体を表示