Sandoz Gmbh

Schweizerische Aluminium Ag

Gunther Tscheulin

Hans Bohler

Jean-Francois Paulet

Fritz Schneeberger

Bruno Boetsch

In acidic Sn(II)-containing electrolytes for coloring oxide layers on anodized aluminum or aluminum alloys, or for electroplating, the Sn(II)-ions are oxidized. By the addition of substances, so called stabilizers, to the electrolytes this oxidation can be more or less prevented i.e. Sn(II) can be more or less stabilized. Furthermore, the effectiveness of the stabilizer can be decisive for the quality of the deposit or the coloring of the oxide layer. It is known that the presence of substantial amounts of Sn(IV) along with Sn(II), as a result of inadequate stabilization of the Sn(II), impairs the quality of the surface treatment. An acidic, Sn(II)-containing electrolyte containing an addition of at least one soluble diphenylamine or substituted diphenylamine derivative stabilizes the Sn(II) and produces flawless coloring.

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Frick, Switzerland

Gunther Tscheulin