本文選題：Mg-Si-Sn單臂　切入點(diǎn)：多層電極　出處：《武漢理工大學(xué)》2015年碩士論文

【摘要】：Mg-Si-Sn熱電材料是重要的中溫?zé)犭姴牧象w系,在工業(yè)余熱和汽車尾氣回收發(fā)電領(lǐng)域具有廣闊應(yīng)用前景。關(guān)于Mg-Si-Sn器件的研究甚少,本論文以Mg2.16(Si0.3Sn0.7)0.98Sb0.02熱電單臂為研究對(duì)象,設(shè)計(jì)了一種與該熱電材料匹配的多層電極,優(yōu)化了多層電極的連接工藝;對(duì)Mg2.16(Si0.3Sn0.7)0.98Sb0.02熱電材料與多層電極的連接狀態(tài)進(jìn)行了表征,包括界面微觀結(jié)構(gòu)、化學(xué)成分、接觸電阻、剪切強(qiáng)度以及高溫穩(wěn)定性;在此基礎(chǔ)上組裝了n型Mg-Si-Sn/p型Cu2Se熱電單偶,測(cè)試了熱電單偶的熱電轉(zhuǎn)換效率和輸出功率,對(duì)焊接界面的高溫穩(wěn)定性進(jìn)行了研究,其主要工作的結(jié)果如下:n型Mg2.16(Si0.3Sn0.7)0.98Sb0.02熱電材料的多層電極滿足器件設(shè)計(jì)要求,該多層電極由第一Ni-Al合金層/第二Ni-Al合金層/Ag構(gòu)成,第一Ni-Al合金層熱膨脹系數(shù)可與Mg2.16(Si0.3Sn0.7)0.98Sb0.02熱電材料良好匹配,Ag層焊接性能良好;多層電極與熱電材料的結(jié)合界面良好,無(wú)明顯微裂紋,其無(wú)明顯元素互擴(kuò)散;界面接觸電阻介于0.07~0.13 m?之間,占熱電材料內(nèi)阻的3.5~8.3%,多層電極與熱電材料的剪切強(qiáng)度高于熱電材料自身強(qiáng)度。n型Mg2.16(Si0.3Sn0.7)0.98Sb0.02熱電材料/多層電極在573 K、673 K和773 K下分別退火一周熱穩(wěn)定性研究表明:當(dāng)退火溫度在673 K及以上時(shí),多層電極第一Ni-Al合金層會(huì)由Al,NiAl3,Ni2Al3和Ni多相組成轉(zhuǎn)變?yōu)锳l和NiAl3兩相穩(wěn)定結(jié)構(gòu),熱電材料/多層電極界面孔隙逐漸增多,Mg向多層電極中的擴(kuò)散加劇,熱電材料/多層電極的接觸電阻由退火前的0.10 m?增加到773 K退火后的0.21m?。n型Mg2.16(Si0.3Sn0.7)0.98Sb0.02熱電材料/多層電極在773 K下退火不同時(shí)間的熱穩(wěn)定性研究表明:當(dāng)退火時(shí)間達(dá)到27 h時(shí),多層電極的第一Ni-Al合金層物相得到穩(wěn)定結(jié)構(gòu),多層電極的第一Ni-Al合金層內(nèi)部及熱電材料/多層電極結(jié)合界面產(chǎn)生大量孔洞,這些孔洞分布于相界面處,Mg在多層電極的第一Ni-Al合金層中含量逐漸增大;接觸電阻由退火前的0.12 m?增大到0.16 m?,其增幅為33%。低溫Pb-Sn焊接可以成功組裝n型Mg-Si-Sn/p型Cu2Se熱電單偶。采用4點(diǎn)探針?lè)▽?duì)n型Mg-Si-Sn/p型Cu2Se熱電單偶的電連接性能進(jìn)行檢測(cè),得到用于熱電裝換效率測(cè)試的樣品。該單偶的熱電轉(zhuǎn)換性能測(cè)試結(jié)果表明:在ΔT=410 K時(shí),轉(zhuǎn)化效率達(dá)到峰值6.33%;而在ΔT=477 K時(shí),輸出功率達(dá)到最大值264.39 mW。n型Mg-Si-Sn單臂與導(dǎo)流銅片焊接頭在773 K下退火1 d、2 d和5 d熱穩(wěn)定性研究表明:Pb-Sn焊料在退火1 d后揮發(fā),隨著退火時(shí)間延長(zhǎng),焊接界面會(huì)緊密融合,Sn向焊接界面?zhèn)劝l(fā)生擴(kuò)散。p型Cu2Se單臂與導(dǎo)流銅片焊接頭在773 K下退火1 d和2 d熱穩(wěn)定性研究表明:隨著退火時(shí)間延長(zhǎng),電極側(cè)Ni和導(dǎo)流片Cu會(huì)向焊料層擴(kuò)散,形成Ni-Pb-Sn-Cu合金,該合金在773 K下穩(wěn)定存在,同時(shí)焊料層中產(chǎn)生大量孔洞,隨后發(fā)展為縫隙,造成焊接界面的脫離。
[Abstract]:Mg-Si-Sn thermoelectric material is an important medium temperature thermoelectric material system, which has a broad application prospect in the field of industrial waste heat and automobile exhaust recovery power generation. There are few researches on Mg-Si-Sn devices. In this paper, Mg2.16(Si0.3Sn0.7)0.98Sb0.02 thermoelectric single arm is the research object. A multilayer electrode matched with the thermoelectric material was designed, and the connection process of the multilayer electrode was optimized, and the connection state between the Mg2.16(Si0.3Sn0.7)0.98Sb0.02 thermoelectric material and the multilayer electrode was characterized, including interface microstructure, chemical composition, contact resistance. Based on the shear strength and high temperature stability, n-type Mg-Si-Sn/p Cu2Se thermoelectric single couple was assembled, the thermoelectric conversion efficiency and output power of the thermoelectric single pair were tested, and the high temperature stability of the welding interface was studied. The main results of this work are as follows: the multilayer electrode of the Mg2.16(Si0.3Sn0.7)0.98Sb0.02 thermoelectric material of type 1: n meets the design requirements of the device. The multilayer electrode is composed of the first Ni-Al alloy layer / the second Ni-Al alloy layer / Ag. The thermal expansion coefficient of the first Ni-Al alloy layer can match well with the Mg2.16(Si0.3Sn0.7)0.98Sb0.02 thermoelectric material, the bonding interface between the multilayer electrode and the thermoelectric material is good, there is no obvious microcrack, and there is no obvious element interdiffusion, and the interface contact resistance is between 0.07 and 0.13 m? Between, The shear strength of multilayer electrode and thermoelectric material is higher than that of thermoelectric material. N type Mg2.16(Si0.3Sn0.7)0.98Sb0.02 thermoelectric material / multilayer electrode annealed at 573K 673K and 773K respectively. When the fire temperature is 673 K and above, The first Ni-Al alloy layer of multilayer electrode will change from Al Ni Al 3N Ni 2AL 3 and Ni multiphase to Al and NiAl3 two phase stable structure, the interface pore of thermoelectric material / multilayer electrode will increase gradually and the diffusion of mg to multilayer electrode will be intensified. The contact resistance of thermoelectric material / multilayer electrode is 0.10 m? Increased to 0.21m? after annealing at 773K? The thermal stability of n type Mg2.16(Si0.3Sn0.7)0.98Sb0.02 thermoelectric material / multilayer electrode annealed at 773K for different time shows that the first Ni-Al alloy layer phase of the multilayer electrode is stable when annealing time is up to 27 h. In the first Ni-Al alloy layer of multilayer electrode and the interface of thermoelectric material / multilayer electrode, a large number of pores were produced, and the content of mg in the first Ni-Al alloy layer of multilayer electrode gradually increased, and the contact resistance was increased from 0.12 m? Increase to 0.16 m? Low temperature Pb-Sn welding can successfully assemble n type Mg-Si-Sn/p Cu2Se thermoelectric single pair. The electrical connection performance of n type Mg-Si-Sn/p Cu2Se thermoelectric single pair is tested by 4 point probe method. The results show that the conversion efficiency reaches a peak value of 6.33 at 螖 T _ (10) K, while at 螖 T _ (477) K, the conversion efficiency reaches a peak value of 6.33 at 螖 T _ (410K), while at 螖 T _ (477) K, the conversion efficiency reaches a peak value of 6.33. Thermal stability of 264.39 mW.n type Mg-Si-Sn single arm welding joint annealed at 773K for 1 d and 5 d the thermal stability of the 1: Pb-Sn solder evaporated after 1 day annealing and with the increase of annealing time. The thermal stability of welding joints annealed at 773K for 1 d and 2 days after annealing at 773K shows that the thermal stability increases with the increase of annealing time. On the electrode side, Ni and Cu can diffuse to the solder layer to form Ni-Pb-Sn-Cu alloy. The alloy exists stably at 773K, at the same time, a large number of holes are produced in the solder layer, and then it develops into a gap, which results in the breakaway of the welding interface.
【學(xué)位授予單位】：武漢理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TB34

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本文編號(hào)：1674277