Trivalent chromium electrolyte and process employing vanadium reducing agent
AssigneeOccidental Chemical Corporation
InventorThaddeus W. Tomaszewski
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Abstract
An aqueous acidic trivalent chromium electrolyte and process for electrodepositing chromium platings comprising an electrolyte containing trivalent chromium ions, a complexing agent, halide ions, ammonium ions and a reducing agent comprising vanadium ions present in an amount effective to maintain the concentration of hexavalent chromium ions formed in the bath at a level at which satisfactory chromium electrodeposits are obtained.
Claims35
An aqueous acidic trivalent chromium electrolyte containing trivalent chromium ions, a complexing agent for maintaining the trivalent chromium ions in solution, halide ions, ammonium ions, hydrogen ions to provide a pH on the acid side, and a reducing agent comprising vanadiums ions present in at least an amount effective to maintain the concentration of hexavalent chromium ions at a level which is not in excess of 0.4 grams/liter.
The process for rejuvenating an aqueous acidic trivalent chromium electrolyte which has been impaired in effectiveness due to the contamination by excessive quantities of hexavalent chromium, said electrolyte containing trivalent chromium ions, a complexing agent for maintaining the trivalent chromium ions in solution, halide ions, ammonium ions and hydrogen ions to provide a pH on the acid side, said process comprising the steps of adding to said electrolyte a reducing agent comprising vanadiums ions in at least an amount sufficient to reduce the concentration of hexavalent chromium ions to a level which is not in excess of 0.4 grams/liter.
Dependencies are inferred from the claim text.