Improvement and Practical Application of FeSi_2 Thermoelectric Materials with Dispersion of Fine Particles by Liquid Phase Sintering.

热电材料的性能由品质因数Z表示：Z=α^2/ρκ，其中α是塞贝克系数，ρ是电阻率，κ是热导率。为了获得高的品质因数，需要大的塞贝克系数和低的电阻率，以及低的热导率。本文研究了液相烧结和微粒分散对热电性能的影响。结果表明：（1）采用机械合金化和液相烧结法制备了颗粒弥散分布的β-FeSi_2。(2)将FeSi_2、Si和C粉末进行机械合金化，得到了SiC超细分散的β-FeSi_2。通过降低导热系数，性能得到显著改善。(3)低电阻率的金属相颗粒的分散显著降低了β-FeSi_2的电阻率和热导率。(4)Cu的添加显著地加速了液相烧结的致密化。(5)SiC和Cu的同时加入使β-FeSi_2的品质因数Z显著提高。FeSi_2-SiC-Cu体系的优值比未添加的β-FeSi_2提高了4倍。

The performance of the thermoelectric materials is represented by the figure of merit Z : Z=α^2/ρκ, where α is Seebeck coefficient, ρ is electrical resistivity, and κ is thermal conductivity. In order to obtain a high figure of merit, a large Seebeck coefficient and low electrical resistivity is required, as well as a low thermal conductivity. The effects of liquid phase sintering and dispersion of fine particles on the thermoelectric propeties are investigated in this study. The results obtained are as follows :(1) β-FeSi_2 with dispersion of fine particles are obtained by mechanical alloying (MA) and liquid phase sintering method. (2) β-FeSi_2 with ultra-fine SiC dispersion was obtained by MA of FeSi_2, Si and C powders. The performance was markedly improved by decreasing the thermal conductivity. (3) Electrical resistivity and thermal conductivity of β-FeSi_2 were markedly decreased by the dispersion of metallic phase particles with low resistivity. (4) Cu addition significantly accelerated densification by liquid phase sintering. (5) The figure of merit Z of β-FeSi_2 was markedly improved by the simultaneous addition of SiC and Cu. The figure of merit of FeSi_2-SiC-Cu system was 4 times larger than that of β-FeSi_2 without addition.