METHOD FOR ELECTRODEPOSITING ZINC AND ZINC ALLOY COATINGS FROM AN ALKALINE COATING BATH WITH REDUCED DEPLETION OF ORGANIC BATH ADDITIVES

摘要

The present invention relates to a method for electrodepositing zinc and zinc alloy coatings from an alkaline coating bath with reduced depletion of organic bath additives. This involves using as an anode an electrode which is insoluble in the bath, contains metallic manganese and/or manganese oxide and is produced from metallic manganese or a manganese-containing alloy, wherein the manganese-containing alloy contains at least 5 pcnt by weight manganese, or is produced from an electrically conductive carrier and a coating containing metallic manganese and/or manganese oxide that is applied thereto, or is produced from a composite material, wherein both the coating containing metallic manganese and/or manganese oxide and the composite material contain with respect to the total amount of manganese at least 5 pcnt by weight of manganese that is obtained from metallic manganese and manganese oxide. The method according to the invention is particularly suitable for the electrodepositing of zinc-nickel alloy coatings from alkaline zinc-nickel baths, since the formation of cyanides can be suppressed very effectively.