Process and apparatus for continuously anodizing aluminum

Abstract

Aluminum is continuously anodized using direct current in an anodizing cell having a cathode connected to the source of direct current which is succeeded by a cathodic contact cell having an anode connected to the same source of direct current. The anodizing direct current is introduced into the aluminum in the contact cell, the aluminum having an anodized oxide coating formed thereon in the anodizing cell before entering the contact cell.

What is claimed is:  .[.1. In a process for continuously electrolytically anodizing aluminum, the improvement which comprises introducing anodizing direct current into said aluminum in a cathodic contact cell having therein an anode connected to said source of direct current, said aluminum having an anodized oxide coating formed thereon before entering said cell through the action of the direct current introduced in the contact cell 
     
        itself..]. 2. In a process for continuously electrolytically anodizing aluminum, the improvement which comprises introducing anodizing direct current from two or more sources in a cathodic contact cell having therein anodes connected to said sources of direct current, the aluminum having an anodized oxide coating formed thereon before entering said cell through the action of the direct current introduced in the contact cell itself. .[.3. Process for continuously electrolytically anodizing aluminum web which comprises continuously passing said web through an anodizing cell having therein a cathode connected to a source of direct current, continuously passing said web from said anodizing cell into a cathodic contact cell having therein an anode connected to said source of direct current, and introducing anodizing direct current into said web in said contact cell, said web having an anodized oxide coating formed thereon in said anodizing cell before entering said contact cell through the action of the direct current introduced in the contact cell itself..]. .[.4. Process of claim 3 wherein said contact cell has a second anode connected to a second source of direct current and said web is continuously passed from said contact cell into a second cell having a cathode therein connected to said second source of direct current..]. .[.5. Process of claim 4 wherein said second cell is an anodizing cell..]. .[.6. Process of claim 4 wherein said second cell is a further electrolytic treatment cell..]. .[.7. Process of claim 3 wherein said aluminum strip is passed through at least two successive pairs of said anodizing cell followed by said contact cell..]. .[.8. Apparatus for continuously electrolytically anodizing aluminum web which comprises anodizing cell means containing a cathode connected to a source of direct current, cathodic contact cell means containing an anode connected to said source of direct current, and means for continuously passing said aluminum web first through said anodizing cell means and then through said contact cell means, the anodizing direct current entering said web in said contact cell means with an anodized oxide coating formed thereon through the action of the direct current introduced in the contact cell itself..]. .[.9. Apparatus of claim 8 wherein said contact cell means contains a second anode connected to a second source of direct current and a second cell means are provided containing a cathode connected to said second source of direct current, said means for passing being adapted to continuously pass said web through said second anodizing cell means after passing through said contact cell means..]. .[.10. Apparatus of claim 9 wherein said second cell means is an 
     
     
        anodizing cell means..]. .Iadd.11.  In a process for continuously electrolytically anodizing a moving aluminum web using the cathodic contact cell technique, the improvement which comprises introducing anodizing direct current from at least two direct current sources into said moving aluminum web into at least two cross-sections thereof, portion of the anodizing being carried out before the aluminum web enters the 
     
     
        contact cell. .Iaddend. .Iadd.12.  Process of claim 11 wherein the anodizing current is introduced by passing said moving aluminum web through at least two successive pairs of an anodizing cell followed by a 
     
     
        contact cell. .Iaddend. .Iadd.13.  Process of claim 11 wherein the anodizing current is introduced into said moving aluminum web by using a contact cell between two anodizing cells whereby anodizing current introduced from a first source of direct current into the first cross-section of said web flows in a direction opposite to the direction of movement of said web and anodizing current introduced from a second source of direct current into the second cross-section of the web flows in the direction of movement of said web. .Iaddend. .Iadd.14. Process for continuously forming a porous anodic oxide coating on aluminum which comprises: (i) passing aluminum through a cathodic contact cell, said aluminum having a portion of the thickness of said porous anodic oxide coating already formed thereon before entering said contact cell through the action of anodizing direct current from a first source of direct current introduced into said contact cell; and   (ii) further anodizing the already anodized aluminum to form the remaining portion of the thickness of the porous anodic oxide coating by introducing anodizing direct current from a second source of direct current into said   
     
     
        already anodized aluminum in said contact cell. .Iaddend. .Iadd.15. Process for continuously forming a porous anodic oxide coating on an aluminum web which comprises: (i) passing said web through a first anodizing cell having therein a cathode connected to a first source of direct current;   (ii) passing said web from said first anodizing cell into a cathodic contact cell having therein an anode connected to said first source of direct current and a second anode connected to a second source of direct current;   (iii) passing said web from said contact cell into a second anodizing cell having a cathode therein connected to said second source of direct current; and   (iv) introducing anodizing direct current from said sources into said web in said contact cell thereby forming a portion of the thickness of the porous oxide coating in said first cell and the remaining portion in said   
     
     
        second anodizing cell. .Iaddend. .Iadd.16.  Process of claim 15 wherein said second anodizing cell is replaced by a further electrolytic treatment cell. .Iaddend. .Iadd.17. Process for continuously forming a porous anodic oxide coating on an aluminum web which comprises: (i) passing said web through a first anodizing cell having therein a cathode connected to a first source of direct current;   (ii) passing said web from said first anodizing cell into a first cathodic contact cell having therein an anode connected to said first source of direct current;   (iii) passing said web from said first contact cell into a second anodizing cell having therein a cathode connected to a second source of direct current; and   (iv) passing said web from said second anodizing cell into a second cathodic contact cell having therein an anode connected to said second   
     
     
        source of direct current. .Iaddend. .Iadd.18.  Apparatus for continuously forming a porous anodic oxide coating on an aluminum web which comprises first anodizing cell means containing a cathode connected to a first source of direct current, cathodic contact cell means containing a first anode connected to said first source of direct current and a second anode connected to a second source of direct current, second anodizing cell means containing a cathode connected to said second source of direct current means for continuously passing said aluminum web through said first anodizing cell means, then through said contact cell means and lastly through said second anodizing cell means, the anodizing direct current from said sources entering said web in said contact cell means. .Iaddend. .Iadd.19. Apparatus of claim 18 wherein said second anodizing cell means is replaced by a further electrolytic treatment cell means. .Iaddend. .Iadd.20. Apparatus for continuously forming a porous anodic oxide coating on an aluminum web which comprises first anodizing cell means containing a cathode connected to a first source of direct current, first cathodic contact cell means containing an anode connected to said first source of direct current; second anodizing cell means containing a cathode connected to a second source of direct current, second contact cell means containing an anode connected to said second source of direct current, and means for passing said web successively through said first anodizing cell means, said first contact cell means, said second anodizing cell means, and said second contact cell means. .Iaddend.