| The solid oxide fuel cell?SOFC?in a high temperature working environment,the O2atmosphere on the cathode side of the cell,generating a Cr-oxides layer with poor electrical conductivity on the surface of ferrite stainless steel metal interconnect.Cr diffuses from the oxide layer to the cathode surface,formation of CrO2?OH?2 precipitates causes degradation of battery performance,a phenomenon known as cathode poisoning.The application of a cobalt-manganese spinel coating on the surface of ferritic stainless steel is the most effective solution.The cobalt manganese spinel coatings has excellent high-temperature conductivity and high-temperature oxidation resistance,and effectively inhibit the evaporation of Cr element,and matched with the thermal expansion coefficient?TEC?of the stainless steel substrate and other battery components,has become the most promising surface coating material for the SOFC metal interconnects.In this dissertation,Ni-Co-Mn,Ni-Co-Ni-Co-Mn,Ni-Co and Cu-Mn composite metal coatings were prepared by electrochemical process,and co-deposition process to prepare Co-Mn composite metal coating.In order to prepare a cobalt-manganese-based composite metal oxide coating on the surface of 430 stainless steel,which can inhibit the outward-diffusion of Cr and both have good high temperature conductivity,the results of the paper are as follows:?Mn,Co?3O4 spinel coating was prepared on 430 stainless steel substrate surface by electrochemical co-deposition of a Co-Mn composite metal coating followed by a high temperature oxidation treatment.The bath was prepared using 0.1mol/L CoSO4 and0.5mol/L MnSO4.The optimal parameter:the concentration of sodium gluconate is0.7mol/L,the pH of plating solution was 3,the current density parameter was 250mA·cm-2.The Co-Mn composite metal coating co-deposited under the current density of 250mA·cm-2,generating a uniform and dense?Mn,Co?3O4 spinel and Co3O4 oxide coating of 10?m thick after oxidized 100h in air at 800°C.?Mn,Co?3O4 spinel coating on the surface of substrate is uniformity,the average particle size of 1.41um.In the 800°C air environment,Co-Mn composite oxide coating effectively inhibited the diffusion of Cr element,and area specific resistance at 800°C was 16.30m?·cm-2.Electrodeposition process was used to sequentially plate Ni,Co,Cu,Mn,and electroplating Ni-Co-Mn,Ni-Co-Ni-Co-Mn,Ni-Co,and Cu-Mn composite metal coatings on the surface of 430stainless steel.Select the optimal parameters of electroplating Ni is:current density of 25mA·cm-2,PH=3.5;The optimal parameters of electroplating Co is:current density of 20mA·cm-2,PH=3.5;The optimal parameters of electroplating Mn is:Current density of is 200mA·cm-2,PH=3;The optimal parameters of electroplating Cu is::current density of 200mA·cm-2,PH=0.71.Ni-Co-Mn composite metal coatings was oxidized at 750°C for 100 hl,its area specific surface resistance at 800°C is 21.11m?·cm-2.Ni-Co-Ni-Co-Mn composite metal was oxidized in air conditions at 750°C for 100 h,its area specific surface resistance at 800°C is 21.63m?·cm-2.Ni-Co composite metal coating with a thickness of about 8.75um was prepared.The Ni-Co composite metal coating was oxidized for 100h,its area specific surface resistance at 800°C is 15.24m?·cm-2.After 300h and 500h oxidation,the diffusion of Co element increased,the composite metal oxide coating consisting of Co1.29Ni1.71O4 spinel coating and a Co3O4 oxide layer was formed.After 300h oxidation,its area specific resistance value at 800°C is 29.52m?·cm-2.After500h oxidation,its area specific resistance value at 800°C is 31.68m?·cm-22 and its area specific surface resistance at 900°C is 10.8m?·cm-2.Cu-Mn composite metal coating was oxidized for 100 h at 750?in air,a very thin CuMn2O4 spinel was formed.The surface resistivity of the coating composed of CuMn2O4 spinel and the CuO oxide layer,its area specific surface resistance at 800°C is 21.86m?·cm-2.With the increase of the oxidation time to 500h,the Cu element diffuses violently,forming the Cu-rich oxide on the surface of the coating and the CuMn2O4 spinel coating on the inner layer.A large number of holes defects appear in the Cu-Mn complex oxide coating.The area specific surface resistance of the Cu-Mn complex oxide coating at 800°C is 7.2m?·cm-2.Ni-Co-Mn,Ni-Co-Ni-Co-Mn,Ni-Co,Cu-Mn composite metal oxide coatings effectively inhibit the outward diffusion of Cr,forming a dense Cr-oxide layer thicker than 2um on the surface of substrate. |
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