Inland Steel Company

Albert Ray Mullins

Griff W Froman

Brian A Sok

Lenin F Martinez

An apparatus for electrolytically treating an endless steel strip comprising an electrolytic treating tank having guide means associated therewith which are adapted to guide a continuously moving endless strip into and out of the interior of the tank and having at least one electrode disposed within the tank directly facing only one of the wide surfaces of the endless strip while the strip is being guided through said tank by the guide means and at least one cathodic electrode spaced from the anodic electrode and disposed within said tank directly facing only the opposite wide surface of said endless strip. The anodic electrode is connected with the positive terminal of a first source of direct current, such as a plating rectifier, and the cathodic electrode is connected with the negative terminal of a second source of direct current, such as an etching rectifier, which is independent of the first source of direct current. Each of the source of direct current has the remaining electrical terminal thereof in electrical connection with the endless strip, and each source of direct current has means for independently regulating the magnitude of the direct current supplied to said terminals. The electrodes are disposed within the tank relative to the guide means so that neither of the wide surfaces of the endless strip is directly exposed to electric current from both the anodic and the cathodic electrodes while the endless strip is being electrolytically treated. The apparatus can be used so as to provide one-side-only electroplating on the cathodic side of an endless metal strip and to control the amount of metal removed from the anodic surface of an endless metal strip.

Electrolytic treating apparatus

A process of making a one-side-only coated endless metal sheet in which a sheet initially having a protective metal coating, such as zinc, on both lateral surfaces thereof is subjected to an electrolytic treatment which removes the protective metal coating from only one side of the metal sheet by continuously passing the metal sheet through an electrolytic treating chamber containing as an electrolyte bath a strongly acidic aqueous solution, such as sulfuric acid, having a pH from about pH 0.1 to 2.0, and preferably about pH 1.0, or a strongly alkaline aqueous solution, such as sodium hydroxide, having a pH of at least about pH 11 and preferably above pH 11, with said metal sheet being guided between spaced anodic and cathodic electrodes immersed in said electrolyte bath so as to establish a cathodic current between said anodic electrode and the adjacent surface of said metal sheet which is made cathodic and establishing an anodic current from a second rectifier between said cathodic electrode and the adjacent surface of said metal sheet which is made anodic, and maintaining the anodic current at a current density level so as to maintain the surface of said metal sheet which is to remain coated completely cathodic and effects complete removal of said protective metal coating from the anodic surface during the period said sheet remains in said electrolytic treating chamber, and with the cathodic current maintained at a current density level below said anodic current density level but sufficiently high to neutralize the E.M.F. generated when the said protective metal coating is immersed in said electrolyte bath.

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Portage, IN, United States of America

Albert Ray Mullins