Papers by Keyword: Pulse Discharge Sintering

Abstract: The direct extrusion process using the powder as raw materials was applied to prepare the thermoelectric materials. The mechanically alloyed powders of Ag added (Bi0.25Sb0.75)2Te3 were extruded by pulse discharge sintering method in the temperature range of 345°C ~ 425°C. High quality products were obtained by hot-extrusion method and their texture and thermoelectric properties were measured. The intensity of (110) plane increased with extrusion temperature up to 385°C and altered in the range of above 405°C
which coincided with the variation of power factor. The measured Power factor ranged from 3.5 ~ 4.0 × 10-3 W/K2·m. The figure of merit (Z) of the material extruded at 385°C was 3.1 × 10-3 /K, the highest value among the prepared materials.

Abstract: The bulk (Bi_0.2iSb_0.8)₂Te₃ thermoelectric alloys added with Ag up to 2.0 mass% were prepared by mechanical alloying and pulse discharge sintering (MA-PDS). Microstructures of the sintered samples were investigated. In the two samples with 1.0 and 2.0 mass% Ag, an abnormal growth of the (Bi,Sb)₂Te₃ phase, manifested by the formation of coarse crystals that are visible with eye, has been revealed during the PDS process of the alloyed powders. The local temperature rise in the compact induced by the compositional fluctuation as a result of Ag addition was suggested to be responsible for the observed abnormal growth. In addition, the electrical transport properties, i.e., electrical resistivity and Seebeck coefficient, of the sintered samples were studied.