スプレー造粒粉末を用いたFeSi_2焼結熱電材料の熱電特性 Thermoelectric Properties of FeSi_2 Sintered Thermoelectric Using Granulated Powders by Spray Drying Method
FeSi<SUB>2</SUB> alloys doped with Mn or Co (p-type Fe<SUB>0.92</SUB>Mn<SUB>0.08</SUB>Si<SUB>2</SUB>, n-type Fe<SUB>0.98</SUB>Co<SUB>0.02</SUB>Si<SUB>2</SUB>) were prepared by vacuum induction melting. The ingots were pulverized in a jet mill, and the powders were granulated by spray drying method using aqueous polyvinylalcohol (PVA) binder, in order to investigate the possibility of production on a large scale. The powders granulated exhibited excellent characteristics of fluidity, leading to smoothly feed it into a die cavity. To remove the binder from a compacted body, it was debindered at 723K for lh in H2, and then sintered at 1423K for 5h in H<SUB>2</SUB>, so that the residual carbon and oxygen contents in a sintered body approached those of the starting powder. Subsequently it was annealed at 1113K for 100h in Ar, so that it was almost composed of β-FeSi<SUB>2</SUB>. The thermoelectric figures of merit (Z) for optimal p- and n-type FeSi<SUB>2</SUB> thermoelectric are 1.75×10<SUP>-4</SUP>(K<SUP>-1</SUP>) and 2.0×10<SUP>-4</SUP>(K<SUP>-1</SUP>), respectively, which are slightly higher than those obtained by H. Nagai on a laboratory scale.
粉体および粉末冶金 45(9), 866-871, 1998-09-15
Japan Society of Powder and Powder Metallurgy