Abstract
The nucleation of tin electrodeposits on the cold rolled steel sheets with various surface conditions was studied in a solution containing stannous sulfate and sulfuric acid. It was found that the nucleus of electrodeposit on the rolled surface developed from the uneven edge caused by rolling, while it appeared at random on the buff-polished surface. On the surface with a crystal structure caused by etching after polishing, the electrodeposit developed at the grain boundary at a low current density and in the crystal grain at a high current density. On the surface with carbide caused by etching after polishing, the electrodeposit concentrated at carbide at a high current density and at random at a low current density.
In this case, when the specimen was dipped in the electrolyte for several seconds before electrodeposition, the electrodeposit developed except on carbide irrespective of current density.
These results show that the nucleation is greatly affected by the unevenness of the steel sheet surface, carbide, etc. It is assumed that the different behaviors of nucleation under various current densities and treating conditions are caused by the non-uniformity of characteristics of the passive layer exsisting on the surface before electrodeposition.
