The Research Of Preparation Processes Of Y-doped CuMn₂O₄ Coating For SOFC Alloy Interconnect

Fe-Cr alloys are known as the most promising interconnect materials of solid oxide fuel cell?SOFC?due to their excellent performance.However,during long-term operation?600⁸00°C?,the Fe-Cr alloy interconnects have the problems of increased resistance caused by the growth of the surface oxide film,and the"Cr poisoning"of the cathode caused by Cr volatilization and the deterioration of the oxidation resistance.The preparation of a spinel coating on the surface of Fe-Cr alloy is one of the most efficient methods for solving these problems.Among all the spinel coatings,Cu-Mn spinel coating is considered to be the most promising coating because it matches the thermal expansion coefficient of the substerte,has good conductivity,and prevents Cr from volatilizing.However,the Cu-Mn spinel coating still has the problem of increase in electric resistance due to coating peeling and thickening after long-term oxidation.Studies have shown that the spinel coatings containing rare earth elements can effectively improve the adhesion of oxides to coating and reduce the area specific resistance of alloy interconnect.But so far,there are few reports focused on the rare earth doped CuMn₂O₄ spinel coating.In this paper,Y-doped CuMn₂O₄ spinel coating was prepared on the surface of SUS430Fe-Cr stainless steel by dip-coating and screen printing.The effects of process parameters on the microstructure and properties of the coating were studied.The mechnism of Y doping on the high temperature oxidation resistance and electrical conductivity of CuMn₂O₄ spinel coating were discussed.It was found that with copper nitrate and manganese nitrate as starting materials,drying at 90°C for 15 h,doping amount of rare earth Y element was as 0.02 mol·L^-1,sintering at 800°C,the Y-doped CuMn₂O₄ spinel powder with good crystallinity and stable phase was prepared;The Y-doped CuMn₂O₄ spinel coatings with uniform microstructure and well adhesion to SUS430 substrate could be prepared by both dip-coating and screen printing processes.However,the coating prepared by dip-coating process was denser than that prepared by screen printing processes.Compared with the undoped CuMn₂O₄ spinel coating sample,the Y-doped coating sample prepared by the dip-coating process owned the more lower oxidation rate constant(2.37326×10^-5mg²cm^-4h^-1)and area specific resistance value?22.7 m?·cm²?after oxidized in air atmosphere at 800°C for 168 h.