Method for the electrodeposition of an iron-zinc alloy coating and bath therefor
AssigneeUnited States Steel Corporation
InventorsWilliam R. Johnson, Larry E. Pfister
Life of this patent
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Abstract
In the electrodeposition of iron-zinc alloy coatings, a lustrous, adherent iron-zinc coating containing 10-20% iron is achieved over a current density range of 400-1600 amps/ft.sup.2 and line speeds of 100-500 ft/min. by employing an electrolyte maintained at a temperature of 130.degree. to 160.degree. F. which contains FeCl.sub.2, ZnCl.sub.2, KCl, K.sub.2 SO.sub.4, a chelating agent such as citric acid, and a minor amount of an adduct composed primarily of polyalkylene glycols.
Claims8
An electrolyte for the electrodeposition of an Fe-Zn alloy coating, consisting essentially of 4-10 g/l of Fe.sup.2+, 50-80 g/l Zn.sup.2+, 240-300 g/l Cl.sup.-, 6-12 g/l SO.sub.4.sup.2-, 0.05-5 g/l of a chelating agent in an amount sufficient to prevent the formation of ferric ion precipitates, 0.5 to 2 ml/l of an adduct containing one or more polyalkylene glycols having a molecular weight of 600-1050, balance H.sub.2 O.
In the electrodeposition of Fe-Zn alloy coatings onto a steel strip travelling at a line speed of 100 to 500 ft/min., in which such deposition is effected by supplying a current density of 400 to 1600 amps/ft.sup.2 to the strip through a soluble zinc-base anode and a chloride-base electrolyte which is circulated between the strip and the anode at a flow-rate sufficiently high to support such current density,
- the improvement for effecting the electrodeposition of a lustrous Fe-Zn coating containing 10 to 20% Fe over said line speed range and said current density range, wherein the electrolyte is maintained at a temperature of 130.degree. to 160.degree. F. and consists essentially of 4-10 g/l of Fe.sup.2+, 50-80 g/l Zn.sup.2+, 240-300 g/l Cl.sup.-, 6-12 g/l SO.sub.4.sup.2-, 0.5-5 g/l of a chelating agent in an amount sufficient to prevent the formation of ferric ion precipitates, 0.5 to 2 ml/l of an adduct containing one or more polyalkylene glycols having a molecular weight of 600-1050, balance H.sub.2 O.
Dependencies are inferred from the claim text.