方钴矿表面高结合强度且低接触电阻率接触层研究

Conversion efficiency of thermoelectric device is determined by the contact layer on the surface of the thermoelectric materials. Study on the contact layer on the surface of skutterudites (SKUs) with relative high ZT value and excellent mechanical properties used for middle temperature thermoelectric device is investigated. Fe-based and CoSi2-based contact layer with good adhesion strength and low contact resistance are fabricated on the surface of p-type and n-type SKUs by one-spot spark plasma sintering, respectively. The fundamental physical properties and interface structure of the contact layer and the SKUs are studied. The relationship about interface structure, work function, carrier concentration of SKUs, adhesion strength and contact resistance is established. The internal mechanism on the good adhesion strength and low contact resistance is clarified. The evolution of interface structure is investigated under the service condition. The influence of service condition on the adhesion and contact resistance is also investigated. The internal relationship on the composition of contact layer, interface structure, adhesion strength and contact resistance is established. The design principle on the composition of contact layer with stable interface structure, good adhesion strength and low contact resistance under the long time service condition is optimized. This study will lay the foundation for the skutterudites thermoelectric devices for the electricity generation from the middle waste.

热电材料表面接触层直接决定着热电器件的转化效率。本项目针对兼具ZT值高且力学性能优异的中温热电器件用方钴矿热电材料的表面接触层开展研究。采用放电等离子烧结一步法在p型和n型方钴矿表面分别制备出结合力良好、低接触电阻率的Fe基和CoSi2基合金接触层。研究接触层和方钴矿的基本物性及界面结构，查明界面结构、功函数及方钴矿载流子浓度与结合力和接触电阻间的关系，揭示结合力良好和低接触电阻率的物理本质。研究服役条件下界面结构演化规律及其对结合力和接触电阻的影响规律及机制，建立接触层成分-界面结构-结合力和接触电阻间的内在联系，优化出长期服役下界面结构稳定、结合力良好和低接触电阻的接触层成分设计准则，为中温废热发电用方钴矿热电器件奠定基础。

制备了高结合强度且低接触电阻率的n型方钴矿TiAl接触层和p型方钴矿FeCrCo接触层，研究了接触层和方钴矿的基本物性及界面结构，查明了烧结和退火工艺参数对材料/接触层界面组织结构、结合强度和接触电阻率的影响规律，揭示了结合力良好和低接触电阻率的物理本质。通过改善制备方法，提高成材率，实现了方钴矿材料的放量制备。系统研究了方钴矿器件的高温端连接工艺，获得了高强低阻接头，通过有限元数值模拟优化结构尺寸设计，制备了具有高转化效率和高输出功率的方钴矿中温发电器件。突破传统接触层材料筛选方法，提出基于原位自生第二相的新型接触层材料筛选方案，开发出CoAl和Fe3Si等潜在的高温稳定高强低阻接触层材料。发表标注基金号SCI 收录论文40篇；获授权国家发明专利6项。培养了博士生7名，其中已毕业4名；硕士生5名，其中已毕业2名。