Chromium Electrolyte Research Articles

Anion incorporation and migration during barrier film formation on aluminium

Surface analysis, using Auger electron spectroscopy with ion etching, and direct electronoptical examination have been employed to determine the relative contributions to solid film development during anodizing of aluminium, initially supporting a xenon implanted thin alumina film, in individual electrolytes containing phosphate, oxalate and chromate species. Under the anodizing conditions selected, film formation in the phosphate and chromate electrolytes proceeds at the metal/film and film/electrolytes interfaces, by O 2−/OH − ion ingress and Al 3+ egress, respectively. In the oxalate electrolyte, little or no contribution to solid film growth is evident at the film/electrolyte interface, migrating Al 3+ ions being ejected directly into the bulk electrolyte at that interface. Both phosphate and oxalate species are incorporated within the film material and are subsequently mobile inward under the field. Their respective migration rates are lower than that of O 2−/OH − ions such that a region of film material, free of the anion of the forming electrolyte, is developed adjacent to the metal/film interface.

The effect of selected additives upon potential characteristics in chromium electrolytes

Etude de differents additifs a un electrolyte standard 450 g/l CrO 3 , 4,5 g/l H 2 SO 4 , par balayage lineaire et voltammetrie cyclique. On constate que chaque additif a un effet sur l'efficacite du procede et sur la morphologie du depot de chrome