METHOD FOR DARKENING A SUPERFICIAL LAYER WHICH CONTAINS ZINC AND WHICH IS OF A MATERIAL PIECE

METHOD FOR DARKENING A SUPERFICIAL LAYER WHICH CONTAINS ZINC AND WHICH IS OF A MATERIAL PIECE

The invention relates to a method for darkening a superficial layer of a workpiece which contains zinc by anodic oxidation. The workpiece is oxidized in a soaking bath containing an aqueous solution comprised of a hydroxide and of a nitrate. The anodic oxidation may be carried out in an aqueous solu...

Ausführliche Beschreibung

Gespeichert in:
Bibliographische Detailangaben
Hauptverfasser: MEISTERJAHN, PETER, KRUSE, THOMAS
Format: Patent
Sprache:eng ; fre ; ger
Schlagworte:
APPARATUS THEREFOR
CHEMICAL SURFACE TREATMENT
CHEMISTRY
COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
COATING MATERIAL WITH METALLIC MATERIAL
COATING METALLIC MATERIAL
DIFFUSION TREATMENT OF METALLIC MATERIAL
ELECTROFORMING
ELECTROLYTIC OR ELECTROPHORETIC PROCESSES
INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL
METALLURGY
PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTIONOF COATINGS
SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION
Online-Zugang:Volltext bestellen
Tags: Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
Beschreibung
Zusammenfassung:The invention relates to a method for darkening a superficial layer of a workpiece which contains zinc by anodic oxidation. The workpiece is oxidized in a soaking bath containing an aqueous solution comprised of a hydroxide and of a nitrate. The anodic oxidation may be carried out in an aqueous solution containing NH.sub.4 NO.sub.3 or NaNO.sub.3, and having a pH value ranging from 8 to 14, at a dipping bath temperature (T) ranging from 15 to 45.degree. C., and with a current density (i) ranging from 3.times.10.sup.-4 to 0.5 A/cm.sup.2. The workpiece is placed in the soaking bath at the beginning of the anodic oxidation after the voltage has already been applied.