【作者】 周华；

【导师】 赵文俞；

【作者基本信息】 武汉理工大学 ， 材料物理与化学， 2011， 硕士

【摘要】 Skutterudite是最受关注和最具应用前景的中温热电材料之一,但目前Skutterudite热电材料的研究仍停留于实验室阶段,规模化的批量生产仍无法开展。其原因在于现有的传统制备方法工艺复杂,耗时太长。本文采用SPS反应烧结工艺来实现填充方钴矿材料的快速制备,探讨了SPS烧结压力工艺参数和两段烧结工艺对快速制备样品的物相、结构和热电性能的影响。研究发现,SPS反应烧结工艺可用来制备填充方钴矿基热电材料。决定物相组成的关键因素是烧结温度,773 K以上烧结时所得样品为单相填充方钴矿。与传统熔融淬火退火工艺相比,快速制备工艺大大缩短了制备时间,降低了烧结温度和能耗。并且所制备的样品中含有独特的螺旋非平衡结构和广泛存在的几百纳米左右的晶须。通过在反应烧结时施加不同的压力快速制备所得样品的物相、结构和性能研究发现：在5～50MPa压力范围内,反应烧结所得样品仍为单相；结构中仍以晶须和螺旋非平衡结构为主；样品的热电性能较接近,在675 K时5 MPa反应所得样品ZT值最大为0.71。由此得出结论5～50MPa范围的压力变化对反应烧结样品的结构和性能较小。在反应烧结快速制备的基础上设计了低温合成高温烧结两步烧结工艺。结果显示：两步烧结工艺仍可制备出单相方钴矿基热电材料。随第二段烧结温度的增高,螺旋晶须结构逐渐长成螺旋块体结构。且样品的电性能增大,热导率降低,综合热电性能有所提高。这表明两步烧结工艺有助于提高快速制备样品的热电性能,快速制备工艺得到了优化。在第一段烧结温度为798 K第二段烧结温度为898 K时所制备样品在800 K时取得最大ZT值0.77。更多还原

【Abstract】 Skutterudite is one of the most promising thermoelectric materials in the moderate and high temperature range. But many studies of skutterudites are focusing on the methods to enhance its thermoelectric properties by filling atoms and lowering its dimensions at present, few researchs on batch preparation are studied although general preparation is time-consuming and energy-wasting. Now a high-efficiency rapid preparation by SPS reaction sintering is adopted to fabricate CoSb3-based thermoelectrical materials. And the effect of sintering pressure is studied as one of the most important parameter to the composition, structure and properties, as well as two-step-sintering process.Results show that a high-efficiency rapid preparation method of melting-quenching combined with Spark Plasma reaction Sintering(SPS) process was developed to fabricate single-phase Ba0.3In0.2Co4Sb12. Non-equilibrium structure such as crystal-whisker and helix structure were found in all SPS samples at different temperature by rapid preparation for nominal composition Ba0.3In0.2Co4Sb12. With SPS temperature increasing, electrical conductivity lowered, Seebeck coefficient increased and ZT improved subsequently. A ZT of 0.72 has been achieved for Ba0.3In0.2Co4Sb12 SPS samples by reaction sintering at 675 K when sintering at 823K.Study on samples prepared by rapid preparation with different sintering pressure indicates that all of the samples are single-phase filled skutterudites from 5 MPa to 50 MPa, with a crystal-whisker and helix non-equilibrium structure. Electrical conductivity, Seebeck coefficient, and thermal conductivity of all samples are no significant differences. A ZT of 0.71 has been achieved for Ba0.3In0.2Co4Sb12 SPS samples by reaction sintering at 675 K when sintering at 5 MPa. This demonstrates pressure is not such a important parameter to the rapid prepared samples.Two-step low-temperature-reaction-high-temperature-sintering rapid preparation process based on previous reaction sintering rapid preparation is studied too. Results show that single-phase filled skutterudites can obtained by two step process. With increasing second-step-sintering temperature, helix whisker non-equilibrium structure grows to be helix grain non-equilibrium structure, and thermoelectrical properties are improved. This indicates that rapid preparation is optimized by a two step process. A ZT of 0.77 has been achieved for Ba0.3In0.2Co4Sb12 SPS samples by two step process at 800 K when reacting at 798 K and consolidating at 898 K.更多还原