MA/SPSプロセスによるFeSi系熱発電素子の作製とその熱電特性

Abstract

P-type and n-type β-FeSi2 was produced by utilizing the process of mechanical alloying (MA) and spark plasma sintering (SPS) technique. Raw powders of pure iron, silicon, manganese and cobalt were mixed and mechanically alloyed for 72 ks using planetary ball mill. The mixing fractions of the powders were in accord with the mole fractions of the Fe0.92Mn0.08Si2 (p-type) and Fe0.98Co0.02Si2 (n-type), respectively. The SPS temperature for producing p-type β-FeSi2 was 1073-1153 K and n-type β-FeSi2 was 1073-1173 K, and the holding time was 0.3 ks. When the sintering temperature was over these temperature, α-FeSi2 was produced and thermoelectric properties was reduced. The density of p-type β-FeSi2 sintered at 1153 K was 4.64 g/cm3 (the relative density was 94.1%), and the maximum powerfactor was 0.30 mW/mK2 at 850 K. The density of n-type β-FeSi2 sintered at 1173 K was 4.71 g/cm3 (the relative density was 95.5%), and the maximum powerfactor was 0.058 mW/mK2 at 650 K.