The effect of ammonium bifluoride as an addition agent to the bath composed of ferrous sulfamate and sulfamic acid for iron deposition was studied.
Furthermore, the effects of the concentration of ferrous ion, amount of the addition agent, pH, cathodic current density, and bath temperature on current efficiency and surface state of the deposited iron were also investigated.
As the results, the optimum conditions found were as follows.
Bath composition: ferrous ion 95g/l
saccharin 0.1g/l
ammonium bifluoride 10g/l
pH3.0
Depositing conditions: bath temperature 60-70°C
cathodic current density 5-10Amp./dm²
Under the above conditions, the current efficiency was 75-85% and the deposition rate was varied with the current efficiency, but was calculated to be in the range of 40-110μ/hr. The throwing power of the bath was nearly equal to that of copper sulfate bath.
The deposit of up to 0.5mm thick had a non-bright rugged surface, but its structure showed uniform appearance with no cracks or pits. Therefore, the addition agent, ammonium bifluoride, had an effect of preventing cracks or pits, but no effect on improving brightness.

抄録全体を表示

The polarization potentials of anode and cathode, when iron was electrolyzed with an electro-chemical machining equipment in various solutions were measured by the reference electrode of metals.
The results obtained were summarized as follows.
1) It was found that the polarization potentials of anode were controlled by specific resistance of the electrolytes, when iron was activly dissolved in the electrolytes.
2) It was also found that the time for keeping the anode potential during the active dissolution of iron in sulfuric acid solutions was affected by convection of the solutions.

抄録全体を表示

The relationship between adhesive strength and surface contaminations was studied by several experimental methods of surface chemistry including tracer technique. Electropolished metal surfaces were used as specimens because of their good reproducibility. They were quantatively contaminated with organic materials, for instance, by applying Langmuir-Blodgett technique. The results obtained were summarized as follows.
1) Copper: With the increase in the amount of adsorbed stearic acid, the adhesive strength between copper and polyvinyl acetate film was decreased. However, no further decrease of the strength was caused for the contamination of more than 3-molecular layers of stearic acid. Peeling of adhesive from the metal took place at the interface between the adhesive and the monolayer of stearic acid; while, it took place between the contaminated layers in the presence of multilayers of stearic acid. In the case of multilayer contamination by oleic acid, peeling occurred at the interface between the 1st and 2nd layers adherent to the metal surface.
2) Iron: The results similar to those in copper were obtained for stearic acid. The decrease in the adhesive strength by oleic acid was not so remarkable as in copper.
3) Stainless steel: For monolayer contamination of stearic acid, peeling took place between the monolayer and the metal surface; while, for the contamination by oleic acid, about a half of the monolayer remained on the metal surface after peeling.

抄録全体を表示

A simple and economical process for boriding metal surfaces was found. The process was only to immerse the metal in a hot salt bath containing borax and carborundum, where no special atmosphere was needed.
Optimum conditions found for boriding of mild steel were to dip the steel in a bath containing 60-50wt% of borax and 40-50wt% of carborundum at 1, 000°C for 6hrs. The boride layer produced by this process was composed of Fe₂B, which was 170μ in thickness, having about 1, 200 of Vickers hardness.
The mild steel lying beneath the boride layer was also observed hardened. The results of chemical analysis and electron probe microanalysis showed that the hardening of the interior mild steel was attributed to the boron and carbon penetrating through the boride layer.

抄録全体を表示

The bonding of several kinds of pure metals and commercial steels was conducted in a hot salt bath containing 40wt% of carborundum and 60wt% of borax at 1, 000°C.
Boride layers having hardness higher than 2, 000VHN and of less than 15μ in thickness were produced by this process for W, Mo, Ta, and Cr; while for Co, Ni, Zr, and V, the hardness was 1, 200-1, 600VHN and the thickness was more than 100μ.
The boride layers in the former group of metals were composed of higher boride compounds such as WB, CrB, and TaB; while the latter were lower boride compounds such as CO₂B, Ni₂B, Zr₂B, arid V₂B.
As for commercial steels, thin boride layers were produced for some steels such as 18-8 stainless steel, 13-Cr stainless steel, and high speed steels; while thick layers were produced for other steels such as steel used for nitriding and high carbon steels. The difference between the both groups of steels would be due to the difference in W, Mo, or Cr content of the steels.

抄録全体を表示

The following results were obtained on the formation and morphology of electrodeposited Au-films on iron substrate surfaces by electron microscopy and scanning electron microscopy.
1) The electrodeposited Au-films consisted of two layers. One was a layer of Au plate crystals, which were bright golden colored and had been coherently developed over the iron substrate surfaces. The other was a layer of spindle dendrites, which were dark brown colored by irregular reflectron on their rugged surfaces and had been developed over the Au plate crystals.
2) In the initial stage of the growth of dendrites, they were observed in the shape of sphere or semi-sphere on the Au plate crystals.
3) The dendrites were developed to spindle shape having twigs and branches with the lapse of deposition time.
4) No difference was observed in the shape of Au dendrites for substrates with different Miller's indices.
5) The coherences found between Au plate crystals and iron substrate surfaces were as follows.
(001) Fe||(001)Au [110]Fe||[010]Au} (1) (110)Fe||(110)Au [001]Fe||[110]Au} (2)
6) Some micro-particles, which had different crystal orientations from those of the plate crystals, had been observed on the outside of the plate crystals since the initial stage of deposition.

抄録全体を表示

The throwing power of various nickel plating baths were measured by the Hull cell method, in which throwing powers were expressed in terms of thickness of deposits measured at various points across the cathode, and of primary current distributions derived from the conventional Hull cell current density formula.
The effects of current density and of bath compositions on the throwing power of nickel were studied. Among the nickel plating baths, studied, the highest throwing powers were given by dull nickel, all-chloride, NaCl, and high-sulfate nickel solutions. However, Watts, sulfamate, high-sulfamate, and KCl nickel plating baths gave moderate throwing powers, and fluoborate and citrate baths gave low throwing powers.
The effects of sulfates on the throwing power and electrolytic conductivity were studied in the Watts bath. It was found that the throwing power and conductivity were improved by raising the concentration of sulfate such as K₂SO₄, Na₂SO₄, (NH₄₎₂SO₄ and MgSO₄.

抄録全体を表示