粉末冶金法制备Si80Ge20B1.2合金及其热电性能

Preparation of Si80Ge20B1.2 Alloy by Powder Metallurgy and Its Thermoelectric Properties

放射性同位素电池(Radioisotope thermoelectric generator,RTG)在深空探测中发挥着不可替代的作用。基于硅锗合金制备的温差发电器是RTG的核心部件,硅锗合金的热电性能对RTG的性能有重要影响。硅锗合金的热电性能和其制备工艺、杂质掺杂等因素密切相关,因此需要对其制备工艺研究与优化。本文采用熔炼和热压烧结制备了P型Si80Ge20B1.2合金,研究了热压烧结工艺参数(热压温度、热压压力、保温时间)对Si80Ge20B1.2合金密度的影响,对Si80Ge20B1.2合金进行了物相结构分析、微观组织分析,并对其热电性能进行了测试。结果表明:1703 K下熔炼2 h后硅和锗可以形成固溶体,热压烧结工艺参数中,热压温度对Si80Ge20B1.2合金密度影响更为明显;热压温度1523 K、热压压力60 MPa、保温时间为120 min时制备的Si80Ge20B1.2密度为2.99 g/cm3,达到其理论密度的99.7%,XRD和SEM分析表明,其结构致密,硅锗分布均匀;热压烧结制备的Si80Ge20B1.2有较低的热导率,在303 K^1073 K范围内,热导率介于2 W/(m·K)~3.2 W/(m·K)之间;Si80Ge20B1.2在1073 K时具备较佳的热电性能,在该温度下,其功率因子为1.76 mW/(m·K2),ZT值0.86。上述研究结果为RTG中温差发电器的研制提供了参考。

Radioisotope thermoelectric generator(RTG)plays an irreplaceable role in deep space exploration.The thermoelectric properties of silicon-germanium alloys have an important effect on the performance of RTG.The thermoelectric properties of silicon-germanium alloys are closely related to their preparation processes,impurity doping,so the preparation processes need to be optimized.P type Si80Ge20B1.2 alloy were prepared by melting and hot pressing sintering,the effects of hot-pressing sintering process parameters on the density of Si80Ge20B1.2 alloy were studied,the phase structure and microstructure,as well as the thermoelectric properties of Si80Ge20B1.2 alloy were investigated.The results show that silicon and germanium can form a solid solution after smelting at 1703 K for 2 h,the hot-pressing temperature has a more significant effect on the density of Si80Ge20B1.2 alloy.The Si80Ge20B1.2 was sintered at 1523 K for 120 min under a pressure of 60 MPa has a density of 2.99 g/cm3,reaching 99.7%of its theoretical density,XRD and SEM analysis showd that its structure is dense,silicon and germanium is evenly distributed;it has a good thermoelectric performance,thermal conductivity of 2 W/(m·K)-3.2 W/(m·K)at the range of 303 K-1073 K,power factor of 1.76 mW/(m·K2)and ZT value of 0.86 at 1073 K.The results provide a reference for the development of thermoelectric generators in RTG.