US2013230425A1PendingUtilityA1

Two-step zinc phosphating process

39
Individually held — no corporate assignee on recordPriority: Sep 2, 2011Filed: Aug 30, 2012Published: Sep 5, 2013
Est. expirySep 2, 2031(~5.1 yrs left)· nominal 20-yr term from priority
Inventors:James A. DechantRichard PremoMark W. Simpson
C23C 22/362C23C 22/83C23C 22/73C23C 22/365C23F 11/00C25D 13/20
39
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Claims

Abstract

Described are methods for treating a multi-metal assembly. The assembly has a first portion that includes an aluminum substrate and a second portion that includes a non-aluminum metal substrate. The methods include treating the multi-metal assembly by contacting the assembly with a zinc-phosphate composition and contacting the treated assembly with a composition that includes a Group IIIB and/or IVB metal and free fluoride.

Claims

exact text as granted — not AI-modified
We claim: 
     
         1 . A method for treating a multi-metal assembly comprising: (i) a first portion comprising an aluminum substrate and (ii) a second portion comprising a non-aluminum metal substrate, the method comprising:
 (a) treating the multi-metal assembly by contacting the assembly with a zinc-phosphate composition comprising:
 (1) phosphate ions; 
 (2) zinc ions; 
 (3) free fluoride; and 
 (4) a Group IIIB and/or IVB metal; and 
   (b) contacting the treated multi-metal assembly with a composition comprising:
 (1) fluorozirconic acid; and 
 (2) a second source of fluoride ions. 
   
     
     
         2 . The method of  claim 1 , wherein the aluminum substrate comprises an aluminum alloy. 
     
     
         3 . The method of  claim 2 , wherein the aluminum alloy comprises at least 0.25% by weight copper. 
     
     
         4 . The method of  claim 3 , wherein the aluminum alloy comprises 0.50% to 0.90% by weight copper. 
     
     
         5 . The method of  claim 1 , wherein the zinc-phosphate composition comprises a Group IIIB and/or IVB metal comprising zirconium. 
     
     
         6 . The method of  claim 5 , wherein a ratio of the concentration of free fluoride in the zinc-phosphate composition, in ppm, to the concentration of zirconium in the zinc-phosphate composition, in ppm, is at least 2.5 to 1. 
     
     
         7 . The method of  claim 5 , wherein the zirconium is present in the zinc-phosphate composition in a concentration of no more than 100 ppm. 
     
     
         8 . The method of  claim 5 , wherein a ratio of the moles per liter of free fluoride in the zinc-phosphate composition to the square root of the moles per liter of zirconium in the zinc-phosphate composition is greater than 10. 
     
     
         9 . The method of  claim 8 , wherein the ratio is at least 11. 
     
     
         10 . The method of  claim 9 , wherein the zinc-phosphate composition does not comprise titanium. 
     
     
         11 . The method of  claim 5 , wherein the source of zirconium in the zinc-phosphate composition comprises hexafluorozirconic acid. 
     
     
         12 . The method of  claim 1 , wherein the zinc-phosphate composition is immersion applied at a temperature of 49-52° C. and the concentration of free fluoride, in ppm, in the zinc-phosphate composition is at least 8010/T, wherein T is the temperature of the zinc-phosphate composition in ° C. 
     
     
         13 . The method of  claim 1 , wherein the composition of step (b) comprises at least 100 ppm zirconium and no more than 300 ppm zirconium. 
     
     
         14 . The method of  claim 1 , wherein the composition of step (b) further comprises an electropositive metal selected from nickel, copper, silver, gold, or a mixture thereof. 
     
     
         15 . The method of  claim 1 , wherein the composition of step (b) has at least 50 ppm and no more than 300 ppm zirconium, and the second source of fluoride ions comprises HF, NH 4 F, NH 4 HF 2 , NaF, and/or NaHF 2 . 
     
     
         16 . A method for treating a multi-metal assembly comprising: (i) a first portion comprising an aluminum substrate and (ii) a second portion comprising a non-aluminum metal substrate, the method comprising:
 (a) treating the multi-metal assembly by contacting the assembly with a zinc-phosphate composition comprising:
 (1) phosphate ions; 
 (2) zinc ions; 
 (3) free fluoride; and 
 (4) a Group IIIB and/or IVB metal comprising zirconium, wherein a ratio of the moles per liter of free fluoride in the zinc-phosphate composition to the square root of the moles per liter of zirconium in the zinc-phosphate composition is greater than 10; and 
   (b) contacting the treated multi-metal assembly with a composition comprising:
 (1) a Group IIIB and/or IVB metal, and 
 (2) free fluoride. 
   
     
     
         17 . The method of  claim 16 , wherein the aluminum substrate comprises an aluminum alloy. 
     
     
         18 . The method of  claim 17 , wherein the aluminum alloy comprises at least 0.25% by weight copper. 
     
     
         19 . The method of  claim 18 , wherein the aluminum alloy comprises 0.50% to 0.90% by weight copper. 
     
     
         20 . The method of  claim 16 , wherein the zirconium is present in the zinc-phosphate composition in a concentration of no more than 100 ppm. 
     
     
         21 . The method of  claim 16 , wherein the ratio is at least 11. 
     
     
         22 . The method of  claim 21 , wherein the zinc-phosphate composition does not comprise titanium. 
     
     
         23 . The method of  claim 16 , wherein the zinc-phosphate composition is immersion applied at a temperature of 49-52° C. and the concentration of free fluoride, in ppm, in the zinc-phosphate composition is at least 8010/T, wherein T is the temperature of the zinc-phosphate composition in ° C. 
     
     
         24 . The method of  claim 16 , wherein the composition of step (b) comprises at least 100 ppm zirconium and no more than 300 ppm zirconium. 
     
     
         25 . The method of  claim 24 , wherein the composition of step (b) comprises: (1) fluorozirconic acid; and (2) a second source of fluoride ions. 
     
     
         26 . The method of  claim 25 , wherein the composition of step (b) has at least 50 ppm and no more than 300 ppm zirconium, and the second source of fluoride ions comprises HF, NH 4 F, NH 4 HF 2 , NaF, and/or NaHF 2 . 
     
     
         27 . The method of  claim 16 , wherein the composition of step (b) further comprises an electropositive metal selected from nickel, copper, silver, gold, or a mixture thereof. 
     
     
         28 . A method for treating a multi-metal assembly comprising: (i) a first portion comprising an aluminum alloy substrate, wherein the aluminum alloy comprises at least 0.25% by weight copper, and (ii) a second portion comprising a non-aluminum metal substrate, the method comprising:
 (a) treating the multi-metal assembly by contacting the assembly with a zinc-phosphate composition comprising:
 (1) phosphate ions; 
 (2) zinc ions; 
 (3) free fluoride; and 
 (4) a Group IIIB and/or IVB metal; and 
   (b) contacting the treated multi-metal assembly with a composition comprising:
 (1) a Group IIIB and/or IVB metal, and 
 (2) free fluoride. 
   
     
     
         29 . The method of  claim 28 , wherein the aluminum alloy comprises 0.50% to 0.90% by weight copper. 
     
     
         30 . The method of  claim 28 , wherein the zinc-phosphate composition comprises a Group IIIB and/or IVB metal comprising zirconium. 
     
     
         31 . The method of  claim 30 , wherein a ratio of the concentration of free fluoride in the zinc-phosphate composition, in ppm, to the concentration of zirconium in the zinc-phosphate composition, in ppm, is at least 2.5 to 1. 
     
     
         32 . The method of  claim 30 , wherein the zirconium is present in the zinc-phosphate composition in a concentration of no more than 100 ppm. 
     
     
         33 . The method of  claim 30 , wherein the ratio of the moles per liter of free fluoride in the zinc-phosphate composition to the square root of the moles per liter of zirconium in the zinc-phosphate composition is greater than 10. 
     
     
         34 . The method of  claim 33 , wherein the ratio is at least 11. 
     
     
         35 . The method of  claim 34 , wherein the zinc-phosphate composition does not comprise titanium. 
     
     
         36 . The method of  claim 30 , wherein the source of zirconium in the zinc-phosphate composition comprises hexafluorozirconic acid. 
     
     
         37 . The method of  claim 28 , wherein the zinc-phosphate composition is immersion applied at a temperature of 49-52° C. and the concentration of free fluoride, in ppm, in the zinc-phosphate composition is at least 8010/T, wherein T is the temperature of the zinc-phosphate composition in ° C. 
     
     
         38 . The method of  claim 28 , wherein the composition of step (b) comprises at least 100 ppm zirconium and no more than 300 ppm zirconium. 
     
     
         39 . The method of  claim 28 , wherein the source of fluoride ions in the composition of step (b) comprises fluorozirconic acid and a second source of fluoride ions. 
     
     
         40 . The method of  claim 39 , wherein the composition of step (b) has at least 50 ppm and no more than 300 ppm zirconium, and the second source of fluoride ions comprises HF, NH 4 F, NH 4 HF 2 , NaF, and/or NaHF 2 . 
     
     
         41 . The method of  claim 28 , wherein the composition of step (b) further comprises an electropositive metal selected from nickel, copper, silver, gold, or a mixture thereof.

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