【摘要】：熱電材料是一種能夠?qū)崿F(xiàn)熱能和電能直接相互轉(zhuǎn)換的功能材料，在溫差發(fā)電和半導(dǎo)體制冷等領(lǐng)域有著廣泛的商業(yè)應(yīng)用前景。Bi2Te3及其固溶體合金是室溫附近熱電性能最好的熱電材料，近幾十年來(lái)已經(jīng)有了較為成熟的發(fā)展。本文以高純單質(zhì)Bi，Sb，Te，Se為原料，采用真空熔煉、破碎、熔融旋甩并結(jié)合自主開發(fā)的通電加壓燒結(jié)(RPS)工藝制備Bi2Te3基熱電材料，研究了制備工藝和名義成份對(duì)Bi2Te3基熱電材料的微觀結(jié)構(gòu)和熱電性能的影響規(guī)律;并探索了制備公斤級(jí)P型Bi2Te3基熱電材料的可能性以及塊體樣品的均勻性；另外，本文以市售單晶棒切割廢粉料為原料，通過(guò)洗滌、還原、摻雜、熔煉再結(jié)合RPS燒結(jié)，探索了以廢料粉末為原料制備高性能P型(Bi,Sb)2Te3塊體的可能性。本文研究結(jié)果如下： (1)研究了制備工藝和名義成份對(duì)Bi2Te3基熱電材料的微觀結(jié)構(gòu)和熱電性能的影響規(guī)律。與采用真空熔煉再結(jié)合RPS工藝的樣品相比，采用真空熔煉、熔融旋甩并結(jié)合RPS工藝的樣品具有更低的熱導(dǎo)率。經(jīng)過(guò)RPS燒結(jié)塊體相對(duì)密度可達(dá)96%以上，證實(shí)RPS是一種非常有效的低溫快速致密化技術(shù)。在此工藝條件下制備P型(Bi, Sb)2Te3樣品最優(yōu)成份為Bi0.44Sb1.56Te3，N型Bi2(Te, Se)3最優(yōu)成份為Bi2Te2.7Se0.3，最大ZT值分別為1.17和0.84。與傳統(tǒng)熱壓(HP)和放電等離子燒結(jié)(SPS)相比，由于低投資和高效率使得RPS技術(shù)更適合于實(shí)際工業(yè)生產(chǎn)。 (2)采用真空熔煉結(jié)合RPS燒結(jié)工藝，成功制備了公斤級(jí)P型Bi2Te3基塊體大樣品,樣品尺寸為長(zhǎng)×寬×高100×60×26mm3。對(duì)尺寸為長(zhǎng)×寬×高50×30×13mm3的燒結(jié)樣品沿不同方向切割考察樣品的微觀結(jié)構(gòu)及熱電性能。針對(duì)樣品5個(gè)部位的熱電性能分析表明，熱電性能均勻性較好，電阻率在1.1~1.2×10-5.m范圍波動(dòng)，電動(dòng)勢(shì)率在200~220μＶ/Κ范圍波動(dòng)，熱導(dǎo)率在1.1~1.3W/m·K范圍波動(dòng)，室溫ZT在0.8~1.0范圍波動(dòng)。 (3)以Bi2Te3基單晶棒切片過(guò)程中的切割廢粉料為起始原料，通過(guò)后續(xù)洗滌、還原、摻雜、熔煉結(jié)合RPS燒結(jié)，成功制備了高性能P型(Bi,Sb)2Te3熱電材料。結(jié)果顯示，，通過(guò)洗滌，還原和熔煉過(guò)程可將切割廢料中的碳、氧元素在一定程度上去除，并未造成廢料中有益元素的損失；適當(dāng)添加高純單質(zhì)Sb, Te可以有效調(diào)節(jié)載流子濃度，其中名義成份為Bi0.44Sb1.56Te3樣品在90°C時(shí)獲得最大ZT值1.16。本回收工藝不僅可以普遍適用于制冷元件制備過(guò)程中產(chǎn)生的各種廢料，而且可以應(yīng)用于實(shí)際工業(yè)生產(chǎn)，提高材料利用率進(jìn)而降低制冷片生產(chǎn)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

本文編號(hào)：2420061