通电加压烧结制备碲化铋基热电材料的微观结构和热电性能研究
发布时间：2019-02-11 20:07
【摘要】：热电材料是一种能够实现热能和电能直接相互转换的功能材料，在温差发电和半导体制冷等领域有着广泛的商业应用前景。Bi2Te3及其固溶体合金是室温附近热电性能最好的热电材料，近几十年来已经有了较为成熟的发展。本文以高纯单质Bi，Sb，Te，Se为原料，采用真空熔炼、破碎、熔融旋甩并结合自主开发的通电加压烧结(RPS)工艺制备Bi2Te3基热电材料，研究了制备工艺和名义成份对Bi2Te3基热电材料的微观结构和热电性能的影响规律;并探索了制备公斤级P型Bi2Te3基热电材料的可能性以及块体样品的均匀性；另外，本文以市售单晶棒切割废粉料为原料，通过洗涤、还原、掺杂、熔炼再结合RPS烧结，探索了以废料粉末为原料制备高性能P型(Bi,Sb)2Te3块体的可能性。本文研究结果如下： (1)研究了制备工艺和名义成份对Bi2Te3基热电材料的微观结构和热电性能的影响规律。与采用真空熔炼再结合RPS工艺的样品相比，采用真空熔炼、熔融旋甩并结合RPS工艺的样品具有更低的热导率。经过RPS烧结块体相对密度可达96%以上，证实RPS是一种非常有效的低温快速致密化技术。在此工艺条件下制备P型(Bi, Sb)2Te3样品最优成份为Bi0.44Sb1.56Te3，N型Bi2(Te, Se)3最优成份为Bi2Te2.7Se0.3，最大ZT值分别为1.17和0.84。与传统热压(HP)和放电等离子烧结(SPS)相比，由于低投资和高效率使得RPS技术更适合于实际工业生产。 (2)采用真空熔炼结合RPS烧结工艺，成功制备了公斤级P型Bi2Te3基块体大样品,样品尺寸为长×宽×高100×60×26mm3。对尺寸为长×宽×高50×30×13mm3的烧结样品沿不同方向切割考察样品的微观结构及热电性能。针对样品5个部位的热电性能分析表明，热电性能均匀性较好，电阻率在1.1~1.2×10-5.m范围波动，电动势率在200~220μＶ/Κ范围波动，热导率在1.1~1.3W/m·K范围波动，室温ZT在0.8~1.0范围波动。 (3)以Bi2Te3基单晶棒切片过程中的切割废粉料为起始原料，通过后续洗涤、还原、掺杂、熔炼结合RPS烧结，成功制备了高性能P型(Bi,Sb)2Te3热电材料。结果显示，，通过洗涤，还原和熔炼过程可将切割废料中的碳、氧元素在一定程度上去除，并未造成废料中有益元素的损失；适当添加高纯单质Sb, Te可以有效调节载流子浓度，其中名义成份为Bi0.44Sb1.56Te3样品在90°C时获得最大ZT值1.16。本回收工艺不仅可以普遍适用于制冷元件制备过程中产生的各种废料，而且可以应用于实际工业生产，提高材料利用率进而降低制冷片生产成本。
[Abstract]:Thermoelectric material is a kind of functional material which can directly convert heat energy and electric energy into each other. Bi2Te3 and its solid solution alloys are the best thermoelectric materials near room temperature and have been developed in recent decades. In this paper, high purity Bi,Sb,Te,Se was used as raw material to prepare Bi2Te3 based thermoelectric materials by vacuum melting, crushing, melt spinning and self-developed (RPS) process. The effects of preparation process and nominal composition on microstructure and thermoelectric properties of Bi2Te3 based thermoelectric materials were studied. The possibility of preparing Bi2Te3 based thermoelectric materials with kg class P and the homogeneity of bulk samples were explored. In addition, the possibility of preparing high performance P type (Bi,Sb) 2Te3 bulk by washing, reducing, doping, melting and sintering with scrap powder as raw material has been explored in this paper. The results are as follows: (1) the effects of preparation process and nominal composition on microstructure and thermoelectric properties of Bi2Te3 based thermoelectric materials are studied. Compared with the samples using vacuum melting and rebonding RPS process, the samples with vacuum melting, melt spinning and RPS process have lower thermal conductivity. The relative density of RPS sintered bulk is over 96%, which proves that RPS is a very effective low temperature rapid densification technique. Under this condition, the optimum composition of P-type (Bi, Sb) 2Te3 is Bi0.44Sb1.56Te3,N type Bi2 (Te, Se) _ 3 and the maximum ZT value of Bi2Te2.7Se0.3, is 1.17 and 0.84, respectively. Compared with traditional hot pressing (HP) and spark plasma sintered (SPS), RPS technology is more suitable for industrial production due to its low investment and high efficiency. (2) by vacuum melting combined with RPS sintering process, the large bulk sample of P type Bi2Te3 was successfully prepared. The size of the sample was 100 脳 60 脳 26mm 3mm in length 脳 width 脳 height. The microstructure and thermoelectric properties of sintered samples with length 脳 width 脳 high 50 脳 30 脳 13mm3 cutting along different directions were investigated. The thermoelectric properties of the five parts of the samples are analyzed. The results show that the thermoelectric properties are uniform, the resistivity fluctuates in the range of 1.1 脳 10 ~ (-5) m, and the EMF is in the range of 200 ~ 220 渭 V / K. The thermal conductivity fluctuates in the range of 1.1~1.3W/m K and the range of ZT at room temperature is 0.8 鈩
本文编号：2420061
[Abstract]:Thermoelectric material is a kind of functional material which can directly convert heat energy and electric energy into each other. Bi2Te3 and its solid solution alloys are the best thermoelectric materials near room temperature and have been developed in recent decades. In this paper, high purity Bi,Sb,Te,Se was used as raw material to prepare Bi2Te3 based thermoelectric materials by vacuum melting, crushing, melt spinning and self-developed (RPS) process. The effects of preparation process and nominal composition on microstructure and thermoelectric properties of Bi2Te3 based thermoelectric materials were studied. The possibility of preparing Bi2Te3 based thermoelectric materials with kg class P and the homogeneity of bulk samples were explored. In addition, the possibility of preparing high performance P type (Bi,Sb) 2Te3 bulk by washing, reducing, doping, melting and sintering with scrap powder as raw material has been explored in this paper. The results are as follows: (1) the effects of preparation process and nominal composition on microstructure and thermoelectric properties of Bi2Te3 based thermoelectric materials are studied. Compared with the samples using vacuum melting and rebonding RPS process, the samples with vacuum melting, melt spinning and RPS process have lower thermal conductivity. The relative density of RPS sintered bulk is over 96%, which proves that RPS is a very effective low temperature rapid densification technique. Under this condition, the optimum composition of P-type (Bi, Sb) 2Te3 is Bi0.44Sb1.56Te3,N type Bi2 (Te, Se) _ 3 and the maximum ZT value of Bi2Te2.7Se0.3, is 1.17 and 0.84, respectively. Compared with traditional hot pressing (HP) and spark plasma sintered (SPS), RPS technology is more suitable for industrial production due to its low investment and high efficiency. (2) by vacuum melting combined with RPS sintering process, the large bulk sample of P type Bi2Te3 was successfully prepared. The size of the sample was 100 脳 60 脳 26mm 3mm in length 脳 width 脳 height. The microstructure and thermoelectric properties of sintered samples with length 脳 width 脳 high 50 脳 30 脳 13mm3 cutting along different directions were investigated. The thermoelectric properties of the five parts of the samples are analyzed. The results show that the thermoelectric properties are uniform, the resistivity fluctuates in the range of 1.1 脳 10 ~ (-5) m, and the EMF is in the range of 200 ~ 220 渭 V / K. The thermal conductivity fluctuates in the range of 1.1~1.3W/m K and the range of ZT at room temperature is 0.8 鈩
本文编号：2420061
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