STUDIES ON THE PASSIVATION OF TIN ANODE

概要

論文の詳細を見る
There are various difficulties in the electrolytic refining of tin. Among them, its anodic passivation is a fatal trouble. The author studied the passivation of pure as well as impure tin anodes in the electrolytes of H2SO4, H2SiF6, and their mixtures, each containing 0.5 N Sn. The present paper concerns to the pure tin anode alone. The anodic Dassivitv of tin is of a mechanical nature. caused by the formation of films of certain tin compounds op the anode surface. The formation of Such films is observed distinctly under microscope during electrolysis. The passivation is easy in H2SO4, and difficult in H2SiF6. This tendency is also the case in mixed electrolytes containing H2SO4 and H2SiF6 in varying proportions. The nature of passifying film is as follows: In H2SO4, basic SnSO4 deposited from oversaturated solution next to the anode surface; in H2SiF6, basic SnSiF6 deposited probably from unsaturated solution; in mixed electrolytes, normal SnSO4 crystal deposited from oversaturated solu-, tion (hydrolysis of SnSO4 is prevented by the presence of H2SiF6). In short, the tin electrolyte must have small hydrizing tendency and large solubility of tin salt. The electrolyte composed of more or less 0.5 N Sn, 1.0 N total H2SO4, 1.0 N total H2SiF6seems to be the most suitable one.
社団法人資源・素材学会の論文