SOFC金属连接体Mn-Cu氧化物涂层制备及性能研究

发布时间：2018-10-31 08:51

【摘要】：固体氧化物燃料电池(SOFCs)是将储存于燃料中的化学能转化为电能的装置。连接体是SOFC的重要部件之一,起着串联单电池,分隔燃料气与氧化剂等作用。金属连接体,尤其是铁素体不锈钢,以其良好的电导率、热导率以及与其它电池组件相匹配的热胀系数、便于加工等优点,已成为主流的连接体材料。然而铁素体不锈钢在SOFC的工作环境中会产生Cr挥发性并使阴极Cr中毒,且表面生成导电性较差的氧化膜,造成电池性能衰减。在不锈钢连接体表面制备(Mn,Cu)3O4尖晶石涂层是目前最有希望的解决方案之一。本文采用直流磁控溅射技术在SUS 430不锈钢表面溅射Mn-Cu涂层,经高温氧化使其转变为(Mn,Cu)3O4尖晶石等氧化物,研究了溅射涂层在SOFC阴极环境(800-C空气)中的氧化行为,利用SEM/EDS和XRD等手段对氧化1周、5周、10周后氧化物的形貌及相结构进行分析,并研究了表面氧化膜的电性能。同时对比并讨论了基体不锈钢未预氧化与预氧化处理对涂层氧化行为的影响。结果表明：(1)溅射涂覆Mn-Cu涂层的未预氧化和预氧化不锈钢的高温氧化(800-C的空气中)增重在氧化初期增重明显,随后增重缓慢。氧化后表面均生成了双层氧化物结构,外层主要为(Mn,Cu)3O4尖晶石,内层为富Cr氧化物。(2)溅射涂覆Mn-Cu涂层的未预氧化和预氧化不锈钢在氧化过程中生成的(Mn,Cu)3O4尖晶石层均有效阻止了Cr向外扩散。(3)预氧化处理使基体在高温下生成的连续、致密的Cr203层,构成了Fe的扩散障,使其在溅射后的氧化过程中很好的抑制了Fe由基体向表面的迁移。但未预氧化样品不能抑制Fe的扩散,在(Mn,Cu)3O4尖晶石中存在Fe元素。(4)预氧化样品较未预氧化样品的面比电阻大,但随时间变化趋势更加平稳。
[Abstract]:Solid oxide fuel cell (SOFCs) is a device that converts chemical energy stored in fuel into electric energy. Connectors are one of the important components of SOFC. They act as single cell in series and separate fuel gas from oxidant. Metal connectors, especially ferrite stainless steels, have become mainstream connectors due to their good conductivity, thermal conductivity and thermal expansion coefficient matching with other battery components. However, ferrite stainless steel in the working environment of SOFC will produce Cr volatility and make cathode Cr poisoning, and the surface formation of poor conductivity oxide film, resulting in cell performance attenuation. The preparation of (Mn,Cu) 3O4 spinel coatings on stainless steel connectors is one of the most promising solutions. In this paper, Mn-Cu coating was deposited on the surface of SUS 430 stainless steel by DC magnetron sputtering technique, and it was transformed into (Mn,Cu) 3O4 spinel and other oxides by oxidation at high temperature. The oxidation behavior of sputtering coating in SOFC cathodic environment (800-C air) was studied. The morphology and phase structure of the oxide after 1 week, 5 weeks and 10 weeks of oxidation were analyzed by SEM/EDS and XRD. The electrical properties of the surface oxide film were also studied. At the same time, the effects of unpreoxidized and preoxidized stainless steel on the oxidation behavior of the coatings were compared and discussed. The results show that: (1) the weight gain of pre-oxidation and high-temperature oxidation of pre-oxidized stainless steel (800-C in air) after sputtering Mn-Cu coating is obvious at the beginning of oxidation, then the weight gain is slow. After oxidation, double oxide structure was formed on the surface, the outer layer was (Mn,Cu) 3O4 spinel, and the inner layer was rich in Cr oxide. (2) unoxidized and pre-oxidized stainless steel (Mn,) formed during oxidation by sputtering Mn-Cu coating. Cu) 3O4 spinel layer effectively prevented Cr from diffusing outward. (3) the continuous and dense Cr203 layer formed in the matrix at high temperature formed by preoxidation formed the diffusion barrier of Fe. It can inhibit the migration of Fe from matrix to surface in the oxidation process after sputtering. However, the diffusion of Fe could not be inhibited by the unpreoxidized sample, and there was Fe element in (Mn,Cu) 3O4 spinel. (4) the surface specific resistance of the preoxidized sample was larger than that of the unpreoxidized sample, but the trend of change with time was more stable.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TG174.4;TM911.4

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