Process for electrolytic coloration of anodized aluminium
AssigneeAlcan Research and Development Limited
InventorsWilliam E. Cooke, Robert A. Innes
Life of this patent
Estimating the term…
Abstract
A continuous length of aluminum is anodized during passage through an anodizing electrolyte and then colored during passage through an inorganic coloring electrolyte, in which a counterelectrode is immersed. In the electrolytic coloring stage alternating current with a superimposed D.C. compound is preferably passed between the anodized aluminum and the counterelectrode when the electrolyte is appropriate for such treatment. The alternating current circuit for the electrolytic coloring stage is preferably completed via an electrode immersed in the anodizing electrolyte at a position facing substantially unanodized aluminum so as to effect a liquid contact.
Claims25
A method of producing a colored anodized aluminum strip which comprises drawing aluminum in strip form successively through an anodizing stage and an electrolytic coloring stage comprising in the anodizing stage moving the strip successively past one or more anodes immersed in a sulphuric acid anodizing electrolyte and past one or more cathodes and passing direct current between said cathodes and said anodes through the strip so as to render the strip initially cathodic and subsequently anodic to develop an anodic oxide film on the surface thereof, the thus anodized strip being then passed through, in said electrolytic coloring stage, an acidic electrolyte containing a material selected from a salt of at least one of copper, tin, cobalt, nickel, chromium, iron, silver or lead, or a manganate, tellurite or selenite, and passing alternating current between at least one electrode immersed in said acidic electrolyte and said anodized strip, the circuit for said alternating current being completed through an electrode immersed in the electrolyte of the direct current anodizing stage.
A method of producing a colored anodized aluminum strip which comprises drawing aluminum in strip form successively through an anodizing electrolyte and an acidic coloring electrolyte containing a material selected from a salt of at least one of copper, tin, cobalt, nickel, chromium, iron, silver or lead or a manganate, tellurite or selenite, passing direct current between said strip and at least one cathode immersed in said anodizing electrolyte, direct current being introduced into said strip through an electrical contact at a location where said strip is substantially unanodized and passing alternating current between the anodized strip and at least one electrode immersed in the coloring electrolyte, the circuit for the alternating current being completed by contact with a substantially unanodized area of the surface of the aluminum strip to generate an asymmetric current wave form;
- the unanodized strip, before entry into the anodization stage, being in contact with a contact roll connected to the positive terminal of said direct current supply and an alternating current source being connected between said contact roll and the electrode in the coloring electrolyte;
- diode branches in parallel being included in the connection between the contact roll and the coloring electrolyte electrode, the diodes in said branches being conductive in opposite directions, the voltage drops across said diode branches when conductive being unequal whereby to generate an asymmetrical alternating current.
A method of producing a colored anodized aluminum strip which comprises drawing aluminum in strip form through an anodizing stage, contacting the strip with a sulphuric acid electrolyte in said anodizing stage, said strip being drawn successively past at least one anode electrode and at least one cathode electrode, a D.C. power source being established between said anode electrode and said cathode electrode whereby said strip in rendered initially cathodic and subsequently anodic during its passage through said anodizing stage, advancing the thus anodized strip to and through an electrolytic coloring stage, contacting said strip with an acidic electrolyte containing a material selected from a salt of at least one of copper, tin, cobalt, nickel, chromium, iron, silver or lead or a manganate, tellurite or selenite and establishing an A.C. power source between said anode electrode in said anodizing stage and a counterelectrode in contact with the electrolyte in the electrocoloring stage thereby to establish alternating current with a superimposed D.C. current component flowing between said anodized strip and said counterelectrode in the electrocoloring stage.
A method of producing a colored anodized aluminum strip which comprises drawing aluminum in strip form successively through an anodizing electrolyte and an acidic coloring electrolyte containing a material selected from a salt of at least one of copper, tin, cobalt, nickel, chromium, iron, silver or lead or a manganate, tellurite or selenite, passing direct current between said strip and at least one cathode immersed in said anodizing electrolyte, direct current being introduced into said strip through an electrical contact at a location where said strip is substantially unanodized and passing alternating current between the anodized strip and at least one electrode immersed in the coloring electrolyte, the circuit for the alternating current being completed by contact with a substantially unanodized area of the surface of the aluminum strip to generate an asymmetric current wave form;
- the alternating-current-passing step comprising passing alternating current through the strip between at least one electrode immersed in the coloring electrolyte and out of contact with said strip and at least one electrode immersed in the anodizing electrolyte and facing a substantially unanodized area of said strip.
A process for electrolytically treating aluminum or its alloy in the form of a strip, wire or foil material in a continuous manner which comprises continuously passing the material through an anodic oxidation treatment cell and an electrolytic coloring cell to carry out electrolysis in said cells to anodize and color the material in a continuous manner, characterized in that just prior to the anodizing stage, a circuit is formed by commonly connecting to the aluminum material a power source for anodizing and a power source for electrolytically coloring, said power source for anodizing being further connected to the anodizing cell and said power source for electrolytically coloring being further connected to the electrolytic coloring cell;
- said power source for anodizing being DC and the power source for electrolytically coloring being AC, or the power source for both of them being a single AC-superimposed direct current, whereby a current having an alternating wave form rich in positive component is supplied to the electrode of the electrolytic coloring cell.
A process for electrolytically treating aluminum or its alloy in the form of a continuous elongated material in a continuous manner which comprises continuously passing the material through an anodic oxidation treatment cell and an electrolytic coloring cell to carry out electrolysis in said cells to anodize and color the material in a continuous manner, characterized in that just prior to the anodizing stage, a circuit is formed by commonly connecting to the aluminum material a power source for anodizing and a power source for electrolytically coloring, said power source for anodizing being further connected to the anodizing cell and said power source for electrolytically coloring being further connected to the electrolytic coloring cell;
- said power source for anodizing being a current to anodize the aluminum material in the anodizing cell and said power source for electrolytically coloring being a current having an alternating wave form to color the aluminum material in the coloring cell.
A process for electrolytically treating aluminum or its alloy in the form of a strip material in a continuous manner which comprises continuously passing the material through an anodic oxidation treatment cell and an electrolytic coloring cell to carry out electrolysis in said cells to anodize and color the material in a continuous manner, characterized in that just prior to the anodizing stage, a circuit is formed by commonly connecting to the aluminum material a power source for anodizing and a power source for electrolytically coloring, said power source for anodizing being further connected to the anodizing cell and said power source for electrolytically coloring being further connected to the electrolytic coloring cell;
- said power source for anodizing being DC and the power source for electrolytically coloring being AC, whereby a current having an alternating wave form rich in positive component is supplied to the electrode of the electrolytic coloring cell.
Dependencies are inferred from the claim text.