Yan Yonggao

Crystal Structures and Thermoelectric Properties of Sm-Filled Skutterudite Compounds Smy Fex Co4 - x Sb12

Abstract Polycrystalline samples of Sm partially filled skutterudites Sm y Fe x Co 4 - x Sb 12 were prepared by melting and Spark Plasma Sintering technique. The results of Rietveld refinement showed that the obtained Sm y Fe x Co 4 - x Sb 12 samples possessed filled skutterudite structures. The thermal parameter ( B ) of Sm is larger than that of Sb, Fe, and Co, indicating that Sm “rattled” in Sb-icosahedron voids. The effects of filling atom Sm on thermoelectric properties of these compounds were investigated. With the increase of Sm filling fraction ( y ), electrical conductivity decreased, Seebeck coefficient increased and had a maximum value when y was 0.38; thermal conductivity reduced and had a minimum value when y was 0. 32. At 750 K, the highest figure of merit of 0.68 was obtained for Sm 0.32 Fe 1.47 Co 2.53 Sb 12 .

Effect of SiO2 on the preparation and properties of Pure Carbon Reaction Bonded Silicon Carbide ceramics

Effect of SiO2 content and sintering process on the composition and properties of Pure Carbon Reaction Bonded Silicon Carbide (PCRBSC) ceramics prepared with C−SiO2 green body by infiltrating silicon was presented. The infiltrating mechanism of C−SiO2 preform was also explored. The experimental results indicate that the shaping pressure increases with the addition of SiO2 to the preform, and the pore size of the body turned finer and distributed in a narrower range, which is beneficial to decreasing the residual silicon content in the sintered materials and to avoiding shock off, thus increasing the conversion rate of SiC. SiO2 was deoxidized by carbon at a high temperature and the gaseous SiO and CO produced are the main reason to the crack of the body at an elevated temperature. If the green body is deposited at 1800°C in vacuum before infiltration crack will not be produced in the preform and fully dense RBSC can be obtained. The ultimate material has the following properties: a density of 3.05–3.12 g/cm3, a strength of 580±32MPa and a hardness of (HRA)91–92.3.

Mg-Si-Sn基热电器件电极材料的优化选择与连接工艺

Metal (Ni, Cu, Ag, Al) electrode was connected with Mg-Si-Sn based thermoelectric materials by Spark Plasma Sintering (SPS) process. Microstructure of interface, sintering process and transport properties, including elec- trical conductivity, thermal conductivity and thermal expansion coefficient, of electrode materials were investigated. The results showed that composites of Ni-Al /Al (60:40) and Cu-Al/Cu (45:55) displayed high electrical conductivity, high thermal conductivity and suitable thermal expansion coefficient to Mg-Si-Sn based materials. It is indicated that the two composites have potential to be used as good electrode materials for, and to be connected by SPS sintering to, Mg-Si-Sn based materials.

快速急冷法对β-Zn 4+ x Sb 3 材料热电及力学性能的影响

β-Zn 4 Sb 3 是一种重要的中温热电材料, 但其较差的力学强度和可加工性限制了其实际应用. 本文采用熔体旋甩法结合放电等离子烧结技术快速制备了一系列具有高热电性能和高力学强度的β-Zn 4+ x Sb 3 块体材料. 通过调节Zn的含量, 优化了其热电性能, 随着Zn含量的增加, 电导率增大, Seebeck系数有所下降, 热导率增加. 在700K时, Zn 4.32 Sb 3 样品的 ZT 值达到1.13, 相比熔融法制备的样品提高了约40%. 该制备方法所得到的样品具有极高的抗压强度, 与熔融法制备的样品相比较, 所有样品的抗压强度均提高了一倍以上, 这种高热电性能和高力学强度的β-Zn 4+ x Sb 3 块体材料具有很好的应用前景.β-Zn 4 Sb 3 是一种重要的中温热电材料, 但其较差的力学强度和可加工性限制了其实际应用. 本文采用熔体旋甩法结合放电等离子烧结技术快速制备了一系列具有高热电性能和高力学强度的β-Zn 4+ x Sb 3 块体材料. 通过调节Zn的含量, 优化了其热电性能, 随着Zn含量的增加, 电导率增大, Seebeck系数有所下降, 热导率增加. 在700K时, Zn 4.32 Sb 3 样品的 ZT 值达到1.13, 相比熔融法制备的样品提高了约40%. 该制备方法所得到的样品具有极高的抗压强度, 与熔融法制备的样品相比较, 所有样品的抗压强度均提高了一倍以上, 这种高热电性能和高力学强度的β-Zn 4+ x Sb 3 块体材料具有很好的应用前景.