Résistance au ternissement des alliages d’argent-germanium et d’argent-cuivre-germanium

Tarnishing resistance of silver-germanium and silver-copper-germanium alloys

Metaleurop Recherche, Trappes

Abstract

Tarnishing of silver alloys was appreciably delayed by adding germanium to the bulk. Both severe ISO corrosion tests for jewellery and accelerated atmospheric tests for electrical contacts were applied. It appears that the formation of Ag₂S and Cu₂S/CuS layers is delayed by a protective effect involving GeO_x species.

The color of samples’ surface turns slightly yellowish instead of black and the corrosion products are easily removable by a simple water washing.