Protective coatings for metal alloys and methods incorporating the same

1. An electrochemical device comprising:

(a) one or more solid oxide fuel cells (SOFCs), each of the SOFCs having a cathode, an anode, and an electrolyte layer positioned between the cathode and anode; and

(b) at least one additional component which is not an electrode, said additional component comprising a metallic substrate having an electronically conductive, chromium-free perovskite coating deposited directly thereon;

wherein the perovskite coating has the formula A x Ni y Co 1-y O 3 , wherein A is La, 0.9 ≦x ≦1, and y <1, with the A site undoped by any alkaline earth element, and

further wherein the perovskite coating exhibits an oxygen transference number of about 0.1 or less at a temperature of 600-1000° C., and is non-porous such that there is no continuous gas path through the thickness of the coating.

2. The electrochemical device of claim 1 , wherein the perovskite coating exhibits n-type conductivity at a temperature of 600-1000° C.

3. The electrochemical device of claim 1 , wherein the perovskite coating has a conductivity of at least about 50 S/cm at 700° C.

4. The electrochemical device of claim 3 , wherein the perovskite coating has a conductivity of at least about 100 S/cm at 700° C.

5. The electrochemical device of claim 1 , wherein the at least one additional component is an interconnect, a current collector, or a gas separator.

6. The electrochemical device of claim 1 , wherein y is greater than 0.4.

7. The electrochemical device of claim 6 , wherein x =1.

8. The electrochemical device of claim 1 , wherein y is greater than 0.5 and less than 0.7.

9. The electrochemical device of claim 8 , wherein L is lanthanum, x is 1, and y is 0.6.

10. The electrochemical device of claim 1 , wherein the perovskite coating has a thickness of between 1 and 40 micrometers.

11. The electrochemical device of claim 10 , wherein the variation in the thickness of the perovskite is less than 20% of the nominal coating thickness.

12. The electrochemical device of claim 1 wherein the perovskite coating further comprises a transition metal oxide, the coating comprising greater than 0% by volume and up to 10% by volume of said transition metal oxide.

13. The electrochemical device of claim 12 , wherein said transition metal oxide comprises CuO, the coating comprising greater than 0% by volume and up to 5% by volume CuO.

14. An electrochemical device comprising:

(a) one or more solid oxide fuel cells (SOFCs), each of the SOFCs having a cathode, an anode, and an electrolyte layer positioned between the cathode and anode; and

(b) at least one additional component chosen from the group consisting of an interconnect, a current collector and a gas separator, said additional component comprising a metallic substrate having an electronically conductive, chromium-free perovskite coating deposited directly thereon, said perovskite having the formula A x Ni y Co 1-y O 3 , wherein A is La, 0.9 ≦x ≦1, and 0.4 <y <1, with the A site undoped by any alkaline earth element;

wherein the perovskite coating—

exhibits an oxygen transference number of about 0.1 or less at a temperature of 600-1000° C.,

is non-porous such that there is no continuous gas path through the thickness of the coating, and

has a thickness of between 1 and 40 micrometers.

15. The electrochemical device of claim 14 , wherein the perovskite coating comprises La x Ni 0.6 Co 0.4 O 3 .

16. The electrochemical device of claim 15 , wherein the perovskite coating comprises LaNi 0.6 Co 0.4 O 3 .

17. The electrochemical device of claim 15 , wherein the perovskite coating comprises La 0.95 Ni 0.6 Co 0.4 O 3 .

18. The electrochemical device of claim 14 , wherein the metallic substrate comprises stainless steel.