SOFC封接材料的高温循环稳定性及其相关性能研究

发布时间：2018-01-29 23:01

  本文关键词： 固体氧化物燃料电池 封接材料 玻璃网络结构 化学稳定性　出处：《福州大学》2014年硕士论文　论文类型：学位论文

【摘要】：固体氧化物燃料电池(SOFC)是一种直接将储存在燃料和氧化剂中的化学能高效、环境友好地转化为电能的全固态化学发电装置。由于其具备较高的能量密度,燃料适应性强能量转换效率高、零污染、全固态模块化组装等优点而在能源领域备受瞩目。作为SOFC的关键技术之一,可靠的封接技术将对SOFC的发展具有重大的推进意义。SOFC的运行温度较高,因此封接材料必须在高温下保持各方面性能的稳定性,包括热性能、气密性、化学稳定性、电导率等。在燃料电池实际应用中已经发现,封接材料容易与金属连接体发生氧化还原反应,生成高膨胀系数的铬酸盐,导致界面开裂,影响封接性能尤其是高温循环稳定性。本课题在分析了封接材料的发展状况以及目前所存在问题的基础上,针对SrO-CaO-SiO2-B2O3体系的基础硼硅玻璃进行系统的探索和研究。首先,本论文研究了Al2O3含量对硼硅玻璃体系的结构与性能的影响。作为网络中性体的Al2O3在含量低于8 mole%时以网络形成体的形式存在于玻璃网络结构中,起到补网的作用。随着Al2O3含量的提高,玻璃的析晶趋势逐渐减弱。样品glass#6Al2O3 (含6 mole% Al2O3)和Cr2O3粉末在700℃下反应生成的Cr6+含量最高。样品glass#4Al2O3的不锈钢涂层在700℃下保温100小时后界面完整,显示出良好的封接性能。其次,研究了Zr02对硼硅封接材料的结构与封接性能,尤其是高温化学稳定性的影响。析晶温度的变化趋势表明,Zr02的添加提高了析晶温度,抑制玻璃的析晶过程。随着Zr02含量的增加,玻璃的软化温度和玻璃转变点逐渐增高,表明ZrOz的添加使得玻璃网络结构更加致密。在700℃下进行的模拟界面反应,由于ZrO2对玻璃网络结构的增强作用,产物中Cr6+的相对含量(即反应率)逐渐降低；而在750℃和800℃下,由于玻璃析晶的作用,界面反应率呈现出与700℃下相反的变化趋势。封接界面的微观分析表明,添加4 mole%和6 mole% ZrO2的玻璃具有良好的封接性能。最后,探索了ZnO对硼硅封接材料的结构与封接性能,尤其是在燃料电池工作环境中的热稳定性的影响规律。结果表明,ZnO的添加降低了封接材料玻璃转变点和软化温度,促进了玻璃的析晶。同时,ZnO含量的进一步增加(16 mole% ZnO)导致玻璃失重率提高,稳定性下降。相关结果为封接材料的设计提供思路。
[Abstract]:Solid oxide fuel cell (SOFC) is a kind of chemical energy which is stored directly in fuel and oxidant. Environmentally friendly all-solid-state chemical power generation device. Because of its high energy density, fuel adaptability, high energy conversion efficiency, zero pollution. As one of the key technologies of SOFC, all solid-state modular assembly has attracted much attention in the field of energy. Reliable sealing technology will be of great significance to the development of SOFC. The operating temperature of SOFC is high. Therefore, the sealing materials must maintain the stability of all aspects of performance, including thermal performance at high temperature. Gas tightness, chemical stability, conductivity and so on. In the practical application of fuel cell, it has been found that the sealing material is easy to redox with metal connectors, forming chromate with high expansion coefficient, which leads to interface cracking. This paper analyzes the development of sealing materials and the existing problems. The basic borosilicate glass of SrO-CaO-SiO2-B2O3 system is systematically explored and studied. First of all. In this paper, the effect of Al2O3 content on the structure and properties of borosilicate glass system has been studied. The content of Al2O3, as a network neutral, is lower than 8%. Mole% exists in the glass network structure in the form of network formation. Play the role of net. With the increase of Al2O3 content. The crystallization trend of the glass gradually decreased. Sample glass#6Al2O3 (containing 6 mol% Al _ 2O _ 3). The highest content of Cr6 was obtained by reaction with Cr2O3 powder at 700 鈩，

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