Hybrid sealing for anodized metal
Disclosed is a method of providing corrosion protection to an anodized metal including providing a metal having an anodization layer wherein the anodization layer includes a barrier portion; contacting the anodization layer with a first solution at a first temperature to seal the barrier portion; and contacting the anodization layer with the sealed barrier portion with a second solution at a second temperature to deposit a precipitated rare earth compound in the anodization layer with the sealed barrier portion; wherein the first solution includes a transition metal oxyanion and has a pH of 3 to 6 and the second solution includes a trivalent rare earth cation.
1. A method of providing corrosion protection to an anodized metal comprising:
providing a metal having an anodization layer wherein the anodization layer includes a barrier portion;
contacting the anodization layer with a first solution at a first temperature to seal the barrier portion; and
contacting the anodization layer with the sealed barrier portion with a second solution at a second temperature to deposit a precipitated rare earth compound in the anodization layer with the sealed barrier portion;
wherein the first solution includes a transition metal oxyanion and has a pH of 3 to 6 wherein the transition metal oxyanion comprises one or more of tungstate, molybdate, vanadate, chromate, and dichromate and the second solution includes a trivalent rare earth cation;
further comprising rinsing the anodization layer with the sealed barrier portion before contacting it with the second solution, and wherein the rinsing occurs at a temperature of 10 to 35° C. for 0.5 to 5 minutes;
wherein the second solution has a rare earth cation concentration greater than or equal to 1 mM and less than or equal to 50 mM and wherein the second solution further comprises 10 to 100 mM of an oxidant, and
wherein the trivalent rare earth cation includes one or more of the following cations: Pr 3+ , Nd 3+ , Sm 3+ , Eu 3+ , Gd 3+ , Tb 3+ , Dy 3+ , Ho 3+ , Er 3+ , Tm 3+ , Yb 3+ , Lu 3+ , Y 3+ , and Sc 3± .
2. The method of claim 1 , wherein the transition metal oxyanion is present in the first solution in an amount of 0.1 mM to 30 mM.
3. The method of claim 1 , wherein the first temperature is 60 to 100° C.
4. The method of claim 1 , wherein the anodization layer is contacted with the first solution for 15 to 30 minutes.
5. The method of claim 1 , wherein the second solution has a pH of 3.5 to 6.5.
6. The method of claim 1 , wherein the second temperature is 10° C. to 70° C.
7. The method of claim 1 , wherein the anodized metal is aluminum or an aluminum alloy.