| The wide-temperature range thermoelectric (TE) material, which is fabricated by connecting several homogeneous TE materials, can make each TE materials work in them optimum temperature ranges, resulting in remarkable enhancement in the TE conversion efficiency. In this thesis, the n-type and p-type Bi2Te3/CoSb3wide-temperature range TE materials, which are fabricated with the homogeneously TE materials of low-temperature Bi2Te3(room temperature～200℃) and intermediate-temperature CoSb3(200～500℃), are used as research objects. The interfacial thermal stabilities of n-type and p-type Bi2Te3/CoSb3wide-temperature range TE materials containing three gradient layers with FS/BT volume ratio3:7-5:5-7:3from FS side to BT side (namely3GLs-II gradient interface) have been investigated under the conditions of constant temperature heat treatment. The effects of heat treatment time (0day,1day,3days,10day) on the interfacial phase compositions, microstructures, chemical compositions, mechanical and electrical properties of n-type and p-type Bi2Te3/CoSb3wide-temperature range TE materials with different have been studied. In addition, the preparations of the high-temperature ceramic frame and Mo50Cu50alloy powders as well as the integrated technology of Bi2Te3/CoSb3thermoelectric device have also been investigated.The interfacial thermal stability of n-type Bi2Te3/CoSb3wide-temperature range TE materials was investigated during heat treatment at573K. The results show that the interfacial microstructures and phase composition are stable as the heat treatment time increased. The diffusion of Te and Bi elements on the interface nearby the FS material side enhanced slightly, while the diffusion of Se,Sb and Te elements in transition layers significantly aggravated. There is no diffusion of elements on the interface nearby the BT material side. Both the interfacial resistivity and interfacial flexural strength decreased as the heat treatment time increased. Having heat treatment for10days, the interfacial resistivity dropped18.7%from4.23mΩ·mm to3.44mΩ·mm, while the interfacial flexural strength dropped34.45%from42.87MPa to28.1MPa.The interfacial thermal stability ofp-type Bi2Te3/CoSb3wide-temperature range TE materials was investigated during heat treatment at573K. The results show that the interface pores increased, the interfacial microstructures and phase composition are stable as the heat treatment time increased. The diffusion of Sb element to the BT material enhanced, while there is no diffusion of other elements. The interfacial resistivity decreased slightly then increased, while the interfacial flexural strength decreased as the heat treatment time increased. Having heat treatment for10days, the interfacial resistivity increased143.4%from13.14mΩ·mm to31.98mΩ·mm, while the interfacial flexural strength dropped37.3%from30.23MPa to18.94MPa.The high-temperature ceramic frame for Bi2Te3/CoSb3wide-temperature range TE device was prepared by sintering the mixture of calcined kaolin, suzhou clay, potash feldspar and calcite at900℃. The results indicate that the optimal sintering time is about8hours and the flexural strength is3.7MPa. Mo50Cu50alloy powders were prepared by mechanical ball grinding method. The optimized ball grinding time is12hours. The particle size of the powder was about0.12～50μm and the average particle size was about10μm, after choosing. Bi2Te3/CoSb3wide-temperature range TE materials were integrated with ceramic frame and wide-temperature range TE materials. |
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