Sealing process for an anodized aluminum-alloy surface
A sealing process includes applying a first reactant to a substrate having a porous structure, the first reactant comprising a chromium (III) precursor and a transition metal precursor and applying a second reactant to the first reactant, the second reactant comprising a rare earth element precursor and an alkaline earth element precursor to form reservoirs of trivalent chromium in pore space of the porous structure, and a physical barrier over the substrate and the reservoirs.
1. A substrate, comprising:
an anodized layer disposed on the substrate; where the anodized layer has a porous structure that comprises pores filled with a trivalent chromium corrosion inhibitor; and
a physical barrier disposed over the anodized layer that seals the trivalent chromium corrosion inhibitor within the pores; wherein the physical barrier comprises a crystalline structure with chromium, a transition metal element, a rare earth element and an alkaline earth element; and where the transition metal element is derived from Ti(OC 3 H 7 ) 4 .
2. The substrate as recited in claim 1 , wherein the physical barrier seals the pores in the porous structure to form reservoirs in the porous structure filled with corrosion inhibitors.
3. The substrate as recited in claim 1 , wherein the anodized layer comprises an aluminum-alloy surface and wherein the physical barrier comprises an oxide film.
4. The substrate as recited in claim 1 , wherein a precursor to the trivalent chromium corrosion inhibitor includes at least one of chromium (III) nitrate and chromium (III) sulfate.
5. The substrate as recited in claim 1 , wherein the physical barrier is formed at a surface of the substrate.
6. The substrate as recited in claim 1 , wherein the physical barrier is formed within a pore space of the porous structure.
7. The substrate as recited in claim 1 , wherein the physical barrier comprises a doped perovskite structure or a doped pyrochlore crystalline structure.
8. The substrate as recited in claim 1 , wherein the physical barrier comprises a perovskite material having the formula ABO 3 , wherein A=Ca or Sr and wherein B is Al.
9. The substrate as recited in claim 1 , wherein the physical barrier is formed as a result of a reaction between a first reactant and a second reactant; wherein the first reactant comprises Cr 2 (SO 4 ) 3 ·XH 2 O, Cr 2 (SO 4 ) 3 ·H 2 O, (Cr 2 (H 2 O) 6 (OH) 4 )SO 4 Cr(NO 3 ) 3 ·9H 2 O, ZrO(NO 3 ) 2 ·XH 2 O, Zr(OC 3 H 7 ) 4 , K 2 ZrF 6 or Ti(OC 3 H 7 ) 4 , and wherein the second reactant comprises a rare earth element precursor and an alkaline earth element precursor.
10. The substrate as recited in claim 1 , wherein the physical barrier comprises La (1-x) A x Cr (1-y) B y O 3 wherein A=Ca or Sr; B=Al or Mg, with x=0 to 1 and y=0 to 1.
11. The substrate as recited in claim 10 , wherein x is 0.05 to 0.8 and y is 0.05 to 0.8.
12. The substrate as recited in claim 9 , wherein the rare earth element precursor includes LaCl 3 ·7H 2 O, La(NO 3 ) 3 · 6 H 2 O, Y(NO 3 ) 3 · 6 H 2 O, or Ce(NO 3 ) 3 · 6 H 2 O.
13. The substrate as recited in claim 9 , wherein the alkaline earth element precursors include Mg(NO 3 ) 2 ·6H 2 O, CaCl 2 · 2 H 2 O, Ca(NO 3 ) 2 · 4 H 2 O, Sr(NO 3 ) 2 , or SrCl 2 ·6H 2 O.