SOFC interconnect barriers and methods of making same
A novel method to produce thin films spatially disposed on desired areas of workpieces is disclosed. Examples of include the formation of a yttria stabilized zirconia (YSZ) film formed on a desired portion of a stainless steel interconnect for solid oxide fuel cells by Atomic Layer Deposition (ALD). A number of methods to produce the spatially disposed YSZ film structures are described including polymeric and silicone rubber masks. The thin film structures have utility for preventing the reaction of glasses with metals, in particular alkali-earth containing glasses with ferritic stainless steels, allowing high temperature bonding of these materials.
1. A barrier layer on a metallic substrate, the metallic substrate comprising a first portion adjacent to a vitreous reactive solid and a second portion adjacent to an electrode, the barrier layer being on the first portion between the metallic substrate and the vitreous reactive solid, the barrier layer not being between the second portion and the electrode, the barrier layer substantially reducing chemical reaction between the metallic substrate and the reactive solid, and the barrier layer comprising an insulating thin film material deposited by atomic layer deposition.
2. The barrier layer of claim 1 , wherein the barrier layer reduces chemical reaction by at least a factor of 10.
3. The barrier layer of claim 1 , wherein the barrier layer reduces chemical reaction by at least a factor of 5.
4. The barrier layer of claim 1 , wherein the barrier layer comprises at least one of a group III oxide and zirconia.
5. The barrier layer of claim 1 , wherein the barrier layer comprises at least one of yttria and zirconia.
6. The barrier layer of claim 5 , wherein the barrier layer comprises layers of each of yttria and zirconia, each layer deposited by an atomic layer deposition cycle.
7. The barrier layer of claim 6 , wherein the layers of each of yttria and zirconia are deposited in a ratio of between and including 4 cycles of zirconia to 1 cycle of yttria and 8 cycles of zirconia to 1 cycle of yttria.
8. The barrier layer of claim 6 , wherein the layers of each of yttria and zirconia are deposited in a ratio of between and including 5 cycles of zirconia to 1 cycle of yttria and 7 cycles of zirconia to 1 cycle of yttria.
9. The barrier layer of claim 1 , wherein the barrier layer comprises at least one of yttria and zirconia and the first atomic layer is yttria.
10. The barrier layer of claim 9 , wherein up to the first 15 atomic layers are yttria.
11. The barrier layer of claim 1 , wherein the barrier layer comprises at least one of yttria and zirconia and further comprises an alumina layer.
12. The barrier layer of claim 1 , wherein the metallic substrate comprises ferritic stainless steel.
13. The barrier layer of claim 1 , wherein the reactive solid comprises an alkali-earth containing glass.
14. The barrier layer of claim 1 , wherein the metallic substrate and reactive solid comprise a portion of the structure of a solid oxide fuel cell.
15. The barrier layer of claim 1 , wherein the substantial reduction of the chemical reaction between the metallic substrate and the reactive solid by the barrier layer is in the temperature range from approximately 650° C. and 850° C.
16. The barrier layer of claim 15 , wherein the barrier layer reduces chemical reaction by at least a factor of 10.
17. The barrier layer of claim 15 , wherein the barrier layer reduces chemical reaction by at least a factor of 5.