The Preparation And Performance Study Of Rare Earth Elements Y Modified NiMn₂O₄ Spinel Coating By Electrophoretic Deposition

Solid oxide fuel cells（SOFCs）is becoming an important breakthrough to solve the global environmental pollution and energy crisis,because of its green,environmental protection and high efficiency,and received more and more attention.However,as an important component of SOFC,alloy interconnects are suffering from two major degradation problem: the poor high temperature oxidation resistance in the working temperature,and “Cr poisoning" which caused by the volatilization of Cr.Due to above problems,the performance of the battery stack is greatly damaged.At present,the application of protective coating on the alloy substrate surface has been proven as an effective method to reduce corrsion rates and inhibit the evaporation of Cr.And in the study of the protective coating of the alloy interconnector,spinel coating has been widely concerned because of its good comprehensive properties.But in the working environment after a long period of high temperature oxidation,the thickness of the transition layer between the coating and the substrate will increase with Cr,which not only increases the surface Area Specific Resistance（ASR）of the coating/alloy interface,reduces the conductivity,but also leads to the decrease of the adhesion between the coating and the substrate,which causes the coating to peel off and make the battery failure.The addition of a small amount of rare earth elements in Spinel coating can increase the bonding strength between the coating and the substrate,and significantly improve the oxidation resistance and electrical conductivity of the substrate.But so far,there are few reports on rare earth elements in improving the performance of Ni-Mn spinel coating of solid oxide fuel cell.In this paper,rare earth Y modified NiMn₂O₄ powder with good crystallinity was obtained by Sol-gel process,On this basis,the rare earth Y modified NiMn₂O₄ spinel protective coating was successfully prepared on the surface of SUS430 ferritic stainless steel by low cost and good electrophoretic deposition process,and discussed the effects of rare earth doping on the phase,microstructure,morphology and high-temperature properties of the coating.The main conclusions are as follows:1、When the doping amount of rare earth is 0.5 mol·L^-1,the phase structure of Y doped NiMn₂O₄ spinel powder is stable and the crystallinity is good.With acetone as the liquid base,the spinel powder loading capacity is 30 g·L^-1,and the concentration of nuclear power regulator is about 0.8 mmol·L^-1,the suspension with good stability can be obtained for a long time;2、The deposition time is 360 s,the deposition voltage is about 100 V,the drying time is about 24 h,the drying temperature is about 75℃,and the calcination temperature is first obtained by calcination at a reductive atmosphere of 800℃ for 2 h,followed by calcined at a temperature of 1000℃ for 2 h in an air atmosphere,can prepared uniform and dense Y modified spinel NiMn₂O₄ protective coating on the surface of the substrate,and the layer thickness is 3⁴ μm.The metallurgical bonding between the coating and the substrate is good;3 、The rare earth elements can effectively refine the grains and improve the microstructure density,the coating and the substrate with more closely.The oxidation rate constant of the Y modified NiMn₂O₄ coating after high temperature oxidation is 1.02×10^-15 g²·cm^-4·s^-1,only 1/9 of the uncoated substract.The ASR value of the Y modified NiMn₂O₄ coating was basically stable at 14.3 mΩ·cm²,which was significantly lower than 15.2 mΩ·cm² of the uncoated substract.