The density of electrodeposited nuclei had remarkable effects on the brightness and corrosion resistance of electroplated products.
At first, the effects of the conditions of electroplating on the number of electrodeposited nuclei were investigated on the buffed cold rolled steel plate from stannous sulfate bath. It was found that the number of nuclei increased with the increase of current density, with the decrease of the concentration of stannous ion, with the depression of bath temperature, and with the increase of the concentration of sulfuric acid. Howewer, no effects of the distance between electrodes were observed in the range of 3.5-5cm.
In the double electrodeposition test, it was found that the thin layer of the primary deposit had deep effects on the brightness and corrosion resistance of the secondary deposit.

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By using Cu single crystals with the surfaces oriented in (100), (110), and (111) directions as substrate, the cathode polarization potential was measured in electrodeposition of Cu from acid Cu sulfate bath, and the formation of Cu electrodeposits was analyzed by microscopic and electron diffraction method.
It was found at higher current density that the polarization potentials of single crystal substrate were arranged in the order of (111)>(100)>(110) and each difference of polarizations between the orientations became less by the addition of thiourea.
It was confirmed that the formation of crystal growth from acid Cu sulfate bath was in step and pyramidal form at c.d. of 1 and 10mA/cm² on (100) plane and the pyramidal form became smaller at 10mA/cm²; and in ridge form at 1 and 10mA/cm² on (110) plane. However, crystals were found in triangular or hexagonal layer at 1mA/cm² and in nodistinct form at 10mA/cm² on (111) plane.
Formation of octahedral twin crystals was observed at 10mA/cm² on (111) plane.

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The effects of urea and boric acid were studied being added as brighteners to the bath composed of ferrous sulfamate and sulfamic acid. The additives were effective for buffers as well as brighteners.
It was examined on the effects of ferrous ion concentration, pH, amounts of additives, temperature, and current density on current efficiency and surface imperfections. As the result, a bright deposit was obtained with no cracks or pits under the following conditions:
Bath composition ferrous ion 2.8g/l
urea 180g/l
boric acid 25g/l
pH 2.2
Temperature 50°C
Cathode current density 7-10A/dm²
The Current density under the above conditions was ranged between 80 and 90%.
Formation of ferric ion by oxidation caused many troubles such as decrease of current density, growth of surface imperfections, and poor adhesion. On the other hand, sulfate ion formed by hydrolysis of sulfamic acid had no harmful effects on the deposit even if its concentration was as high as 20g/l.

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