Method for treating or pre-treating components comprising aluminum surfaces

Abstract

A method for treating or pre-treating parts, profiles, strips, or wires comprising surfaces of aluminum, or other metal surfaces with an acidic, aqueous solution containing fluoride and phosphate.

1 - 13 . (canceled)  
   
   
       14 . A method comprising: 
 contacting an aluminum or aluminum alloy surface in a phosphatizing bath containing an acid aqueous solution containing fluoride and phosphate at a temperature of from 35 to 60° C.;    wherein the fluoride content of the solution in the bath is at least partly present in the solution as free fluoride and the free-fluoride content is maintained at a concentration in the range from 5 to 50 mg/l F free ;    maintaining an SiF 6  content in the aqueous solution in the bath in the range of from 1 to 3 g/L; and    maintaining the aluminum content of the aqueous solution in the bath at a concentration of ≦100 mg/l Al ions (including complex-bound Al), wherein the aluminum content in the bath is maintained by circulating the aqueous solution, when the aluminum content of the solution is greater than 100 mg/Al ions, to a precipitation tank outside the phosphatizing bath to decrease the aluminum content of the solution to ≦100 mg/l Al ions, and introducing the aqueous solution with the decreased aluminum ion content back into the bath, whereby precipitates of cryolithe and related precipitates do not occur or do not substantially occur in the phosphating bath such that said cryolithe or related precipitates do not settle or do not substantially settle on the surface to be coated, wherein the free-fluoride concentration in the precipitation tank or in a separate zone of the bath is 5 to 500 mg/L.    
   
   
       15 . A method according to  claim 14 , wherein, in the separate zone of the phosphatizing bath, increasing aluminum contents in the phosphatizing solution are decreased to contents ≦100 mg/l Al ions.  
   
   
       16 . A method according to  claim 14 , wherein the tank or in the separate zone of the bath, aluminum is precipitated in the phosphatizing solution by adding at least one of an alkali ion, a fluoride complex or fluoride ion.  
   
   
       17 . A method according to  claim 14 , wherein the alkali ion content in the bath is maintained at a concentration in the range from 1 to 20 g/l.  
   
   
       18 . A method according to  claim 14 , wherein the free-fluoride concentration in the precipitation tank or in the separate zone of the bath container is 5 to 500 mg/l free fluoride.  
   
   
       19 . A method according to  claim 14 , wherein the dwell time of the phosphatizing solution in the precipitation tank or in the separate precipitation zone is up to 1 h.  
   
   
       20 . A method according to  claim 14 , wherein prior to pickling/phosphatizing, the parts, sections, strips and/or wires to be treated or pretreated are cleaned, rinsed and, if appropriate and separately from the rinsing and cleaning stages, brought into contact with an activating solution, for example on the basis of colloidally dispersed titanium phosphate.  
   
   
       21 . A method according to  claim 14 , further comprising rinsing or passivating the treated surfaces with a passivating solution on the basis of a chromate-containing compound, titanium fluoride, zirconium fluoride, silane, self-organizing molecules for example on the basis of phosphonate, a polymer soluble and/or dispersible in solvent, a soluble rare-earth compound wherein the rare-earth element also includes scandium, yttrium and lanthanum.  
   
   
       22 . A method according to  claim 14 , wherein the treated or pretreated and/or passivated parts, sections, strips and/or wires are dried after pickling/phosphatizing or after passivation.  
   
   
       23 . A method according to  claim 14 , wherein the precipitation of the aluminum is effected under normal pressure.  
   
   
       24 . A method according to  claim 14 , wherein the formation of the conversion or passivation layer is effected under normal pressure.  
   
   
       25 . A method according to  claim 14 , wherein surface is on a treated or pretreated and/or passivated part, section, strip, and/or wire, optionally coated with at least one of a lacquer, a different organic coating, a film or with an adhesive layer, and optionally the surface is printed and if applicable reshaped, and wherein metal parts coated in this way can in addition be bonded, welded and/or otherwise connected together with other parts.  
   
   
       26 . The method of  claim 14 , wherein the surface is for the treatment or pretreatment of parts, sections, strips or wires with surfaces of aluminum or of alloys containing aluminum, optionally in the presence of surfaces of further metals or alloys an acid aqueous solution containing fluoride and phosphate.  
   
   
       27 . A method according to  claim 26 , modified in that, in a separate zone of the phosphatizing bath, increasing aluminum contents in the phosphatizing solution are decreased to contents ≦100 mg/l Al ions.  
   
   
       28 . A method according to  claim 27 , wherein the tank or in the separate zone of the bath, aluminum is precipitated in the phosphatizing solution by adding alkali ions, fluoride complexes and/or fluoride ions, in particular by means of Na or K ions or by means of at least one easily dissociating fluoride such as, for example, NaF, NH 4 F, NaHF 2  or KF.  
   
   
       29 . The method of  claim 26 , wherein the SiF 6  content is from 1.15 to 3 g/L.  
   
   
       30 . The method of  claim 29 , wherein the SiF 6  content is from 1.15 to 3 g/L.  
   
   
       31 . The method of  claim 16 , wherein Na ions, K ions, or at least one easily dissociating fluoride is added.  
   
   
       32 . The method of  claim 16 , wherein said easily dissociating fluoride is selected from the group consisting of NaF, NH 4 F, NaHF 2  and KF.