Effect of processing time on thermoelectric properties of AgPbmSbTem+2 alloy by vacuum smelting
碩士 === 國立中興大學 === 材料工程學系所 === 94 === In this study, the Ag18PbSbTe20 thermoelectric alloy was prepared for various smelting time and various cooling time by using vibration vacuum smelting. The effects of smelting time and cooling time on thermoelectric properties, microstructures and compositions...
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| Format: | Others |
| Language: | zh-TW |
| Published: |
2006
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| Online Access: | http://ndltd.ncl.edu.tw/handle/07673633855174679334 |
| Summary: | 碩士 === 國立中興大學 === 材料工程學系所 === 94 === In this study, the Ag18PbSbTe20 thermoelectric alloy was prepared for various smelting time and various cooling time by using vibration vacuum smelting. The effects of smelting time and cooling time on thermoelectric properties, microstructures and compositions of the AgPb18SbTe20 alloy were studies.
The results of thermoelectric properties show that the optimal electrical conductivity is 4.95× 10² (Ω-cm)‾¹ for specimens smelted 14 hours and cooled from 850℃ to 450℃ for 40 hours. The electrical conductivity increase with the amount of Ag increasing in matrix. The optimal Seebeck coefficient is 268 (μV/K) for specimens smelted for 14 hours and cooled for 80 hours. As the amount of impurities in the semiconductive PbTe phase increases, the Seebeck coefficient increases. The lowest of thermal conductivity is 1.58 (W/K•m) for specimen smelted for 14 hours and cooled for 40 hours. In the microstructural aspect, the major phase of AgPb18SbTe20 is PbTe phase. Precipitates at some conditions. The amount of doping Ag and Sb atom in the precipitates and matrix affects the thermoelectric properties of AgPb18SbTe20 alloy greatly. The optimum parameters of AgPb18SbTe20 alloy by smelting are smelting time of 14 hours and cooling time of 40 hours at this condition that the best figure of merit is 0.056.
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