新型中温SOFC连接体TaC/Ni-Ta复合材料的原位制备与性能优化研究

连接体是固体氧化物燃料电池（SOFC）的关键部件之一，常用的中温SOFC金属连接体有热膨胀系数不匹配与铬中毒的缺点，严重降低电池堆的运行效率，急需开发新型连接体材料。基于此，本项目提出热膨胀系数可调且不含铬的TaC/Ni-Ta复合材料，并围绕其原位制备和性能优化展开研究。首先，采用无压反应烧结法制备TaC/Ni-Ta复合材料，结合物相演变过程和收缩曲线，探明原位反应机理及烧结制度以制备致密复合材料；进而分析其中温热膨胀、抗氧化与导电性能，根据膨胀系数与Ni含量关系，明确Ni含量范围，结合氧化动力学曲线、氧化膜结构、电导率曲线与电导激活能，揭示其氧化机制与导电机理；在此基础上，通过引入CeO2及调控粒径分布优化复合材料的中温抗氧化和导电性能，并阐明二者的协同作用机制，最终制得具有合适热膨胀系数，强抗氧化与高电导的TaC/Ni-Ta复合材料，为新型中温SOFC连接体的制备和性能优化提供参考。

Interconnect is one key component of solid oxide fuel cell (SOFC). However, the commonly used metallic interconnects of intermediate temperature SOFC have two disadvantages, i.e., coefficient of thermal expansion mismatch and chromium poisoning, which cause serious degradation of operation efficiency of SOFC. Therefore, it is urgent to explore new kinds of interconnects materials. On this basis, TaC/Ni-Ta composite with adjustable coefficient of thermal expansion and no chromium is proposed in this project, and the in-situ preparation and properties optimization of composite will be studied. Firstly, TaC/Ni-Ta composite is fabricated by pressureless reactive sintering. The in-situ reaction mechanism and sintering schedule are obtained by analyzing the phases evolution process and shrinkage curve, in order to prepare the dense composites. Then, the intermediate temperature thermal expansion, oxidation resistance and electrical conductivity of composites are investigated. The range of Ni content is confirmed by analyzing the relation between coefficient of thermal expansion and Ni content. The oxidation mechanism of TaC/Ni-Ta composites is revealed by analyzing the oxidation kinetics curve and oxide scale structure. Meanwhile, the conducting mechanism of composites is illustrated by analyzing the electrical conductivity curve and conductivity activation energy. Based on this, the oxidation resistance and electrical properties of TaC/Ni-Ta composites will be optimized by adding CeO2 and regulating the particle size distribution. Moreover, their synergistic effect mechanism will also be clarified. Lastly, the TaC/Ni-Ta composites with suitable coefficient of thermal expansion, excellent oxidation resistance and high electrical conductivity will be prepared, which can provide reference to the preparation and properties optimization of new kinds of intermediate temperature SOFC interconnects.