金属连接体涂层材料MnCo_2O_4尖晶石的氧化动力学行为和电性能

OXIDATION KINETICS BEHAVIOR AND ELECTRICAL PROPERTY OF MnCO_2O_4 SPINEL AS A COATING MATERIAL FOR METALLIC INTERCONNECTS

采用溶胶-凝胶法在SUS 430合金表面制备Mn Co_2O_4尖晶石涂层,研究在固体氧化物燃料电池(SOFCs)阴极气氛下涂层对于SUS 430合金氧化动力学行为和电性能的效用.利用XRD,EDS和SEM对合金表面氧化物的相结构、表面和截面形貌以及成分进行表征,并采用四探针直流技术测量表面氧化物的面比电阻(ASR).结果表明,涂层合金在750℃空气中氧化1000 h形成2μm氧化物层,其主要由内层Mn-Cr尖晶石和外层掺杂的Mn-Co尖晶石构成;Cr_2O_3和Fe_2O_3的形成受到了抑制.氧化动力学曲线遵循抛物线规律,2段氧化速率常数分别为3.74×10^(-15)g^2/(cm4·s)(0~200 h)和7.06×10^(-15)g^2/(cm4·s)(200~1000 h),与无涂层SUS 430合金相比降低了1个数量级.在600~800℃范围内,氧化物层的ASR介于5.21~22.65 mΩ·cm^2范围内.Mn Co2O4涂层有效地增强了SUS 430合金的抗氧化能力和电性能.

Mn Co2O4 spinel was coated on the surface of SUS 430 alloy by using the sol-gel method. The oxidation kinetics behavior and electrical property of coated SUS 430 alloy in solid oxide fuel cells（SOFCs） cathode atmosphere were investigated. XRD, EDS and SEM were used to characterize the phase structure, surface and cross-section morphology, and composition of the surface oxides; the area specific resistance（ASR） of the surfaceoxides was measured by using the four- probe direct current technique. The result shows that a 2 mm thick oxide scale, mainly consisting of an inner layer of Mn-Cr spinel and an outer layer of doped Mn-Co spinel, was formed during cyclic oxidation at 750 ℃ in air for 1000 h. The growth of Cr2O3 and Fe2O3was depressed. The oxidation kinetics obeys the parabolic law with two rate constants 3.74×10-15g2/（cm·4s）（0-200 h） and 7.06×10-15g2/（cm·4s）（200-1000h）, respectively, which is 1 order of magnitude lower than that of the SUS 430 alloy without coating. The ASR is in the range of 5.21-22.65 mΩ·cm2at 600-800 ℃. Mn Co2O4 coating was proved to be effective in enhancing the oxidation resistance and electrical property of SUS 430 alloy.