Coatings for SOFC metallic interconnects
Various methods of treating a chromium iron interconnect for a solid oxide fuel cell stack and coating the interconnect with a ceramic layer are provided.
1. A method of making an interconnect for a solid oxide fuel cell comprising:
providing an interconnect comprising Cr and Fe wherein the interconnect comprises an air side and a fuel side;
forming a Cr 2 O 3 layer on the fuel side of the interconnect coating the interconnect with manganese cobalt oxide precursors comprising MnO and one or more of CoO, Co metal or combinations thereof; and
sintering the manganese cobalt oxide precursors to form a manganese cobalt oxide spinel coating;
wherein:
the interconnect comprises a chromium iron alloy comprising 4 to 6 weight percent iron and balance chromium;
the manganese cobalt oxide spinel coating is formed on the air side of the interconnect; and
the sintering is performed at a temperature between 1300° C. and 1400° C., with an oxygen partial pressure between 10 −15 and 10 −17 atm such that the Cr 2 O 3 layer is reduced to chromium metal while the MnO remains as an oxide.
2. The method of claim 1 , further comprising removing a native oxide from at least one of the air side or the fuel side of the interconnect.
3. The method of claim 2 , wherein the step of removing comprises removing the native oxide from the air side and the fuel side of the interconnect.
4. The method of claim 2 , wherein the step of removing comprises grit blasting.
5. The method of claim 1 , wherein the manganese cobalt oxide precursors comprise the MnO and the CoO.
6. The method of claim 1 , wherein the manganese cobalt oxide precursors comprise the MnO and the Co metal.
7. The method of claim 1 , wherein the CoO comprises a binary oxide and the MnO comprises a binary oxide.