Corrosion inhibiting additive

Abstract

A corrosion resistant article includes an aluminum substrate having greater than 0.25 wt % zinc, and a protective coating on the aluminum substrate. The protective coating includes a non-tungstate anodic corrosion inhibitor and a cathodic corrosion inhibitor.

1 . A corrosion resistant article comprising:
 an aluminum substrate having greater than 0.25 wt % zinc; and   a protective coating on the aluminum substrate, the protective coating comprising a non-tungstate anodic corrosion inhibitor and a cathodic corrosion inhibitor.   
   
   
       2 . The corrosion resistant article as recited in  claim 1 , wherein the aluminum substrate includes greater than 5 wt % zinc. 
   
   
       3 . The corrosion resistant article as recited in  claim 2 , wherein the aluminum substrate includes about 5.1-6.1 wt % of the zinc. 
   
   
       4 . The corrosion resistant article as recited in  claim 1 , wherein the aluminum substrate includes about 2 wt % or less of copper. 
   
   
       5 . The corrosion resistant article as recited in  claim 4 , wherein the aluminum substrate includes about 1.2-2 wt % of the copper. 
   
   
       6 . The corrosion resistant article as recited in  claim 5 , wherein the aluminum substrate comprises about 0.3 wt % manganese, about 2.1-2.9 wt % magnesium, about 0.4 wt % silicon, about 0.5 wt % iron, about 5.1-6.1 wt % of the zinc, about 0.18-0.35 wt % chromium, about 0.2 wt % titanium, and a balance of aluminum. 
   
   
       7 . The corrosion resistant article as recited in  claim 1 , wherein the non-tungstate anodic corrosion inhibitor comprises at least one of a vanadate compound or a molybdate compound. 
   
   
       8 . The corrosion resistant article as recited in  claim 7 , wherein the non-tungstate anodic corrosion inhibitor consists of zinc molybdate. 
   
   
       9 . The corrosion resistant article as recited in  claim 1 , wherein the cathodic corrosion inhibitor comprises a Group IIIB Periodic Table element. 
   
   
       10 . The corrosion resistant article as recited in  claim 9 , wherein the cathodic corrosion inhibitor consists of cerium citrate. 
   
   
       11 . The corrosion resistant article as recited in  claim 1 , wherein the protective coating comprises a conversion coating, primer, paint, adhesive, or sealant. 
   
   
       12 . The corrosion resistant article as recited in  claim 1 , wherein the non-tungstate anodic corrosion inhibitor and the cathodic corrosion inhibitor comprise about 1-50 wt % of the protective coating. 
   
   
       13 . A method of selecting a corrosion-inhibiting substance, comprising:
 selecting a corrosion-inhibiting substance to include a non-tungstate anodic corrosion inhibitor based upon an amount of at least one alloying element in an aluminum alloy substrate that is to be coated with the corrosion-inhibiting substance.   
   
   
       14 . The method as recited in  claim 13 , wherein the at least one alloying element comprises zinc, and further including selecting the corrosion inhibiting substance to include the non-tungstate anodic corrosion inhibitor based upon the amount of the zinc being between greater than 0.25 wt % of the aluminum alloy. 
   
   
       15 . The method as recited in  claim 13 , wherein the at least one alloying element comprises zinc, and further including selecting the corrosion inhibiting substance to include the non-tungstate anodic corrosion inhibitor based upon the amount of the zinc being between about 5.1 and 6.1 wt % of the aluminum alloy. 
   
   
       16 . The method as recited in  claim 13 , including selecting the non-tungstate anodic corrosion inhibitor to include at least one of vanadium and molybdenum. 
   
   
       17 . The method as recited in  claim 16 , including selecting the non-tungstate anodic corrosion inhibitor to include zinc molybdate. 
   
   
       18 . The method as recited in  claim 13 , including selecting the corrosion inhibiting substance to include a cathodic corrosion inhibitor comprising at least one Group IIIB Periodic Table element. 
   
   
       19 . A corrosion-inhibiting substance comprising:
 a carrier fluid;   a cathodic corrosion inhibitor within the carrier fluid; and   a zinc-inert anodic corrosion inhibitor within the carrier fluid for protecting aluminum alloys having greater than 0.25 wt % zinc.   
   
   
       20 . The corrosion-inhibiting substance as recited in  claim 19 , wherein the carrier fluid comprises at least one of water, alcohol, primer, paint, adhesive, or sealant. 
   
   
       21 . The corrosion-inhibiting substance as recited in  claim 19 , wherein the zinc-inert anodic corrosion inhibitor consists of zinc molybdate. 
   
   
       22 . The corrosion-inhibiting substance as recited in  claim 21 , wherein the cathodic corrosion inhibitor consists of cerium citrate. 
   
   
       23 . The corrosion-inhibiting substance as recited in  claim 19 , comprising about 0.1 to 100 grams per liter of each of the cathodic corrosion inhibitor and the zinc-inert anodic corrosion inhibitor within the carrier fluid.