US 5,344,552 AGranted

Process for electroplating a metal strip

AssigneeSollac

InventorsIsabelle Marolleau, Jean-Denis Girardier

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Abstract

According to this process, the strip runs through a bath of at least one electrolytic cell and two metal layers are successively deposited onto its surface by adjusting the current feeding the electrolytic cell so that the average value of the current density at the surface of the strip is less than a value called the limiting diffusion current of the ions of the metal to be deposited. In addition, during the formation of the first metal layer, the current is adjusted so as to prevent the appearance of localized overcurrents at the surface of the strip, it being possible for these overcurrents to exceed the limiting diffusion current. Such a process find particular application for electrogalvanizing. Application to an electrogalvanising process.

Claims12

Dependent claims

A process for electroplating a metal strip in a bath of at least one electrolyte cell comprising a solution of ions of a metal to be deposited onto the metal strip, comprising the steps of:

running the metal strip by a first conducting roller/anode pair in the bath comprising at least one electrically conducting roller, forming a cathode, in contact with the metal strip and at least one anode in a vicinity of each said conducting roller, the first conducting roller/anode pair being fed with a first adjustable current having a first current density at a surface of the metal strip which can exceed a limiting diffusion current Jl of the ions, wherein the first adjustable current of the first conducting roller/anode pair is adjusted so that a first average value Jm.sub.1 of the first current density at the surface of the metal strip satisfies the relationship:
10% Jl.ltoreq.Jm.sub.1 .ltoreq.40% Jl
and running the metal strip by a second conducting roller/anode pair in the bath comprising at least one electrically conducting roller, forming a cathode, in contact with the metal strip and at least one anode in a vicinity of each said conducting roller, the second conducting roller/anode pair being fed with a second adjustable current having a second current density at a surface of the metal strip which can exceed the limiting diffusion current Jl of the ions, wherein the second adjustable current of the second conducting roller/anode pair is adjusted so that a second average value Jm.sub.2 of the second current density at the surface of the metal strip satisfies the relationship:
50% Jl.ltoreq.Jm.sub.2 .ltoreq.90% Jl.

1 more element

Dependencies are inferred from the claim text.