US2007017602A1PendingUtilityA1

Two-stage conversion treatment

49
Individually held — no corporate assignee on recordPriority: Dec 11, 2003Filed: Jun 9, 2006Published: Jan 25, 2007
Est. expiryDec 11, 2023(expired)· nominal 20-yr term from priority
Inventors:Alina KochMarian PawlikHeike QuellhorstPatrick Droniou
C23C 22/83C23C 22/34C23C 22/44C23C 22/73
49
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Claims

Abstract

The invention relates to a chromium-free, corrosion prevention treatment for steel, zinc or zinc alloys, aluminum, magnesium or alloys thereof in which the metal surfaces are contacted in a first step with a first aqueous solution having a pH of 1.5 to 5 which contains Ti and/or Zr and/or Si ions and at least such a quantity of fluoride that the atomic ratio of Ti to F and/or Zr to F and/or Si to F is in the range from 1:1 to 1:6 and then, optionally after rinsing with water, and thereafter in a second step are contacted with a second aqueous solution having a pH of 1.5 to 5 which contains Ti and/or Zr and/or Si ions and at least such a quantity of fluoride that the atomic ratio of Ti to F and/or Zr to F and/or Si to F is in the range from 1:1 to 1:6, and which additionally contains such a quantity of soluble anions of oxo acids of Mo (VI) and/or W (VI) that the total concentration of molybdenum and/or tungsten is in the range from 5 to 1500 mg/l.

Claims

exact text as granted — not AI-modified
1 . A process for the two-step corrosion prevention treatment of metal surfaces, comprising: 
 a) contacting a metal surface with a chromium-free, first aqueous solution having a pH of 1.5 to 5 which contains 0.01 g/l to 10 g/l of one or more first metal ions selected from Ti, Zr and Si ions, and at least a quantity of fluoride such that the atomic ratio of the first metal ions to the fluoride is in the range from 1:1 to 1:6 and then, optionally after rinsing with water,    b) contacting the metal surface from a), with a chromium-free, second aqueous solution having a pH of 1.5 to 5 which contains 0.01 g/l to 10 g/l of said one or more first metal ions and at least a quantity of fluoride such that, in the second aqueous solution, the atomic ratio of the first metal ions to the fluoride is in the range from 1:1 to 1:6, said second aqueous solution additionally comprising a quantity of soluble anions of oxo acids of Mo (VI) and/or W (VI), such that the total concentration of molybdenum and/or tungsten, expressed as MoO 2   2−  and/or WO 4   2− , is in the range from 5 to 1500 mg/l.    
   
   
       2 . The process as claimed in  claim 1 , wherein metal surfaces are selected from surfaces of steel, galvanized or alloy-galvanized steel, aluminized steel, zinc, aluminum, magnesium or alloys of which at least 50 atom-% consists of zinc, aluminum or magnesium.  
   
   
       3 . The process as claimed in  claim 1 , wherein the first aqueous solution additionally contains at least 0.005 g/l and up to 20 g/l organic polymers.  
   
   
       4 . The process as claimed in  claim 3 , wherein the first aqueous solution contains at least 0.01 g/l and up to 1 g/l organic polymers.  
   
   
       5 . The process as claimed in  claim 1 , wherein the second aqueous solution additionally contains complexing agents.  
   
   
       6 . The process as claimed in  claim 1 , wherein the first and/or the second aqueous solution has a pH of at least 1.7 and up to 4.  
   
   
       7 . The process as claimed in  claim 1 , wherein the second aqueous solution additionally contains buffer substances for the pH range of 1.5 to 5.  
   
   
       8 . The process as claimed in  claim 1 , wherein the second aqueous solution contains no more than 5 mg/l organic polymers.  
   
   
       9 . The process as claimed in  claim 1 , wherein, in the second step b), the metal surfaces are contacted with the second aqueous solution for 5 seconds to 10 minutes.  
   
   
       10 . The process as claimed in  claim 1 , wherein the second aqueous solution has a temperature of at least 20° C. and no more than 60° C.  
   
   
       11 . A process for producing a structural element containing painted metal parts in which 
 I) cutting and/or stamping and/or forming sheets of metal carrying a coating based on organic polymers into metal parts and fitting together the metal parts obtained to form a structural element, areas of metal surface which are not covered by the coating based on organic polymers being produced thereby;    II) cleaning the assembled structural element,    III) subjecting the cleaned, assembled structural element to a process sequence which produces a passivation layer that is not a zinc phosphate layer on said areas of the metal parts which are not covered by the coating based on organic polymers formed in step I), said process sequence comprising:    a) contacting the cleaned, assembled structural element in a first step with a chromium-free first aqueous solution having a pH of 1.5 to 5 which contains at least 0.01 g/l and up to 10 g/l Ti and/or Zr and/or Si ions and at least a quantity of fluoride such that the atomic ratio of Ti to F and/or Zr to F and/or Si to F is in the range from 1:1 to 1:6, and then, optionally after rinsing with water;    b) contacting the cleaned, assembled structural element in a second step with a chromium-free second aqueous solution having a pH of 1.5 to 5 which contains at least 0.01 g/l and up to 10 g/l Ti and/or Zr and/or Si ions and at least such a quantity of fluoride that the atomic ratio of Ti to F and/or Zr to F and/or Si to F is in the range from 1:1 to 1:6 and said second aqueous solution additionally comprising a quantity of soluble anions of oxo acids of Mo (VI) and/or W (Vl), such that the total concentration of molybdenum and/or tungsten, expressed as MoO 2   2−  and/or WO 4   2− , is in the range from 5 to 1500 mg/l;    IV) optionally, rinsing the structural element treated in step b) one or more times with water, and    V) coating the treated structural element with a layer of paint.    
   
   
       12 . The process as claimed in  claim 11 , wherein the metal surfaces are selected from surfaces of steel, galvanized or alloy-galvanized steel, aluminized steel, zinc, aluminum, magnesium or alloys of which at least 50 atom-% consists of zinc, aluminum or magnesium.  
   
   
       13 . The process as claimed in  claim 11 , wherein the first aqueous solution additionally contains at least 0.005 g/l and up to 20 g/l organic polymers.  
   
   
       14 . The process as claimed in  claim 13 , wherein the first aqueous solution contains at least 0.01 g/l and up to 1 g/l organic polymers.  
   
   
       15 . The process as claimed in  claim 11 , wherein the second aqueous solution additionally contains complexing agents.  
   
   
       16 . The process as claimed in  claim 11 , wherein the first and/or the second aqueous solution has a pH of at least 1.7 and up to 4.  
   
   
       17 . The process as claimed in  claim 11 , wherein the second aqueous solution additionally contains buffer substances for the pH range of 1.5 to 5.  
   
   
       18 . The process as claimed in  claim 11 , wherein the second aqueous solution contains no more than 5 mg/l organic polymers.  
   
   
       19 . The process as claimed in  claim 11 , wherein, in the second step b), the metal surfaces are contacted with the second aqueous solution for 5 seconds to 10 minutes.  
   
   
       20 . The process as claimed in  claim 11 , wherein the second aqueous solution has a temperature of at least 20° C. and no more than 60° C.

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