JP2003138332A - Sintered compact of compound of zinc, antimony and cadmium and its manufacturing method - Google Patents
Sintered compact of compound of zinc, antimony and cadmium and its manufacturing methodInfo
- Publication number
- JP2003138332A JP2003138332A JP2001331630A JP2001331630A JP2003138332A JP 2003138332 A JP2003138332 A JP 2003138332A JP 2001331630 A JP2001331630 A JP 2001331630A JP 2001331630 A JP2001331630 A JP 2001331630A JP 2003138332 A JP2003138332 A JP 2003138332A
- Authority
- JP
- Japan
- Prior art keywords
- temperature
- compound
- pressure
- sintering
- chemical formula
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 150000001875 compounds Chemical class 0.000 title claims abstract description 27
- 229910052793 cadmium Inorganic materials 0.000 title claims abstract description 21
- 229910052787 antimony Inorganic materials 0.000 title claims abstract description 17
- 229910052725 zinc Inorganic materials 0.000 title claims abstract description 17
- 238000004519 manufacturing process Methods 0.000 title abstract description 8
- 239000011701 zinc Substances 0.000 title description 39
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 title description 14
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 title description 11
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 title description 11
- 238000005245 sintering Methods 0.000 claims abstract description 41
- 239000000126 substance Substances 0.000 claims abstract description 23
- 239000000843 powder Substances 0.000 claims abstract description 17
- 238000002844 melting Methods 0.000 claims abstract description 9
- 230000008018 melting Effects 0.000 claims abstract description 9
- 238000000280 densification Methods 0.000 claims abstract description 8
- 230000003247 decreasing effect Effects 0.000 abstract 1
- 238000007789 sealing Methods 0.000 abstract 1
- 238000007711 solidification Methods 0.000 abstract 1
- 230000008023 solidification Effects 0.000 abstract 1
- 239000000463 material Substances 0.000 description 16
- 238000006243 chemical reaction Methods 0.000 description 10
- 238000010248 power generation Methods 0.000 description 9
- 239000002994 raw material Substances 0.000 description 6
- 238000001816 cooling Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- 239000011521 glass Substances 0.000 description 4
- 239000007789 gas Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000003708 ampul Substances 0.000 description 1
- CZJCMXPZSYNVLP-UHFFFAOYSA-N antimony zinc Chemical compound [Zn].[Sb] CZJCMXPZSYNVLP-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 239000011812 mixed powder Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 238000010587 phase diagram Methods 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Landscapes
- Powder Metallurgy (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、亜鉛、アンチモン
及びカドミウムからなる化合物の焼結体及びその製造方
法に関するものである。TECHNICAL FIELD The present invention relates to a sintered body of a compound composed of zinc, antimony and cadmium, and a method for producing the same.
【０００２】[0002]
【従来の技術】熱エネルギーを電気エネルギーに、或い
は電気エネルギーを熱エネルギーに変換させる熱電変換
モジュールは、エネルギー変換モジュルールとして注目
されている。このモジュールを利用した熱電発電を行う
ための機構は、図１に示されている。この熱電発電は、
熱電発電を構成するモジュールの一方に熱を供給し、高
温部分を形成し、他の一方の低温部分から熱を放熱さ
せ、貫流する熱の一部を電気として取り出す発電方式で
ある。熱電発電のモジュールには、p型材料とn型材料が
使用される。発電変換効率は、各材料の性能を表す下式
により決定される。
ここで、 TH、TL、
は、夫々、高温部温度、低温部温度及びそれらの平均温
度であり、Zは、材料の性能指数（単位はK-1）である。
Zの値が高いほど、熱電発電の変換効率も高くなる。こ
の熱電変換効率により熱発電の性能は定まる。この材料
の一つとして、亜鉛及びアンチモンからなる化合物が知
られており、具体的には、化学式β-Zn4Sb3 で示され
る化合物は良好な材料であることが知られている。図２
は、従来知れている各熱電材料の性能指数と温度の関係
を示すものである。β-Zn4Sb3は、500Kから700Kの間
で、他の材料に比較して高い性能指数Zの値を示してお
り、発電用材料として高いポテンシャルを有しているこ
とがわかる。また、Znの一部をCdにより置換することに
よって得られる化合物は、結晶格子中を伝播するフォノ
ンの散乱を増加させ、熱伝導をさらに低減させることに
より、熱電変換材料としての性能を向上させる事ができ
ると考えられている。このように、亜鉛及びアンチモン
からなる化合物およびその合金は高いポテンシャルを有
していることがわかる。従来、β-Zn4Sb3緻密固体は、
通常の均一に加熱を行う溶融法では合成できないとされ
ている。図３は、Ｚｎ−Ｓｂの状態図である。この状態
図を見ると、β相は調和溶融せず、他の相を生成しなが
らγ相を生成し、より低温でβ相となることがわかる。
このために、Ｚｎ−Ｓｂの単相を得ることは難しいこと
もわかる。また、単相に類似する、性能の良い材料が得
られたとしても、γ相からβ相への相変態温度が４９２
℃であり、冷却時に体積変化を経験することから、内部
に気泡やクラックが多量に存在し、機械的に非常に弱い
ために、熱電発電モジュールとして使用することは不可
能である。このような事情で，確実に均質な材料を得る
ためには、亜鉛及びアンチモンの各単体元素の混合粉体
を、３００℃〜４００℃の反応温度としては低い温度
で、長時間かけて固相反応を進めるか、もしくは、不均
一な溶融凝固試料を一度粉砕し、長時間かけて上記温度
で熱処理する事が必要と考えられる。β-Zn4Sb3のZn原
子の一部をCd原子により置換した化学式β-(Zn1-xCdx)4
Sb3（式中、Ｘ＝０〜０．３であり、０を含まない。）で
示される化合物の焼結体を製造するにしても、その困難
性は同様である。上記各材料は粉体であるため、通常は
加圧焼結を行い、密度を上げて、機械的に丈夫な材料か
らなる素子として、熱電発電に利用する。このようなこ
とから、例えば、温度４００℃、圧力３５MPaという条
件下に、一軸加圧の放電プラズマ焼結により、焼結体を
合成することは可能であると考えられる。しかしなら
が、上記焼結体でも、焼結体内部に微細なクラックが多
く発生する事が報告されており、焼結体は機械的な特性
を測定する事が困難なほどに脆弱であり、熱電発電モジ
ュールに利用するのに十分な強度が得られない。また、
場合によっては、焼結装置から取り出した状態で、割れ
てしまうなど、機械的な信頼性に乏しい状態にある。こ
のようなことから、化学式β-(Zn1-xCdx)4Sb3（式中、Ｘ
＝０〜０．３であり、０を含まない。）の化合物の焼結
体に関し、内部に気泡やクラックが多量に存在せず、機
械的に十分な強度がある、熱電発電モジュールに使用す
ることができる焼結材料及びその製法が求められてい
る。2. Description of the Related Art A thermoelectric conversion module for converting heat energy into electric energy or electric energy into heat energy is drawing attention as an energy conversion module rule. A mechanism for thermoelectric power generation using this module is shown in FIG. This thermoelectric generation
This is a power generation system in which heat is supplied to one of the modules constituting the thermoelectric power generation to form a high temperature portion, and the heat is radiated from the other one of the low temperature portions, and a part of the flowing heat is taken out as electricity. P-type and n-type materials are used in thermoelectric modules. The power generation conversion efficiency is determined by the following equation representing the performance of each material. Where T H , T L , Are the hot part temperature, the cold part temperature and their average temperatures, respectively, and Z is the figure of merit of the material (unit is K −1 ).
The higher the value of Z, the higher the conversion efficiency of thermoelectric generation. The thermoelectric conversion efficiency determines the performance of thermoelectric generation. As one of the materials, a compound composed of zinc and antimony is known, and specifically, a chemical formula β-Zn 4 Sb 3 It is known that the compound represented by is a good material. Figure 2
Shows the relationship between the performance index and temperature of each conventionally known thermoelectric material. β-Zn 4 Sb 3 has a high figure of merit Z between 500 K and 700 K as compared with other materials, and it can be seen that it has a high potential as a power generation material. In addition, the compound obtained by substituting a part of Zn by Cd is to increase the scattering of phonons propagating in the crystal lattice and further reduce the heat conduction, thereby improving the performance as a thermoelectric conversion material. Is believed to be possible. Thus, it can be seen that the compound of zinc and antimony and its alloy have a high potential. Conventionally, β-Zn 4 Sb 3 dense solid is
It is said that it cannot be synthesized by the usual melting method that heats uniformly. FIG. 3 is a state diagram of Zn-Sb. From this state diagram, it can be seen that the β phase does not undergo harmonic melting, but forms the γ phase while forming other phases, and becomes the β phase at a lower temperature.
Therefore, it is also difficult to obtain a Zn-Sb single phase. Even if a material with good performance similar to a single phase is obtained, the phase transformation temperature from γ phase to β phase is 492.
Since it has a temperature of ℃ and undergoes a volume change during cooling, it has a large amount of bubbles and cracks inside and is mechanically very weak, so it cannot be used as a thermoelectric power generation module. Under these circumstances, in order to reliably obtain a homogeneous material, the mixed powder of each elemental element of zinc and antimony is solid-phased for a long time at a low reaction temperature of 300 ° C to 400 ° C. It is considered necessary to proceed with the reaction or to pulverize the non-uniform melt-solidified sample once and heat-treat at the above temperature for a long time. Chemical formula β- (Zn 1-x Cd x ) 4 in which some Zn atoms in β-Zn 4 Sb 3 are replaced by Cd atoms
Even if a sintered body of the compound represented by Sb 3 (where X = 0 to 0.3 and does not include 0) is produced, the difficulty is the same. Since each of the above materials is a powder, it is usually subjected to pressure sintering to increase the density and is used for thermoelectric power generation as an element made of a mechanically strong material. From this, it is considered possible to synthesize a sintered body by uniaxial pressure discharge plasma sintering under the conditions of a temperature of 400 ° C. and a pressure of 35 MPa, for example. However, even in the above sintered body, it has been reported that many fine cracks are generated inside the sintered body, and the sintered body is so fragile that it is difficult to measure mechanical properties, Insufficient strength is available for use in thermoelectric power modules. Also,
In some cases, mechanical reliability is poor, such as cracking when taken out from the sintering apparatus. For this reason, the formula β- (Zn 1-x Cd x ) 4 Sb 3 ( wherein, X
= 0 to 0.3, not including 0. ) Regarding the sintered body of the compound of (1), there is a demand for a sintered material which does not have a large amount of bubbles and cracks inside and has mechanically sufficient strength, and which can be used for a thermoelectric power generation module, and a manufacturing method thereof. .
【０００３】[0003]
【発明が解決しようとする課題】本発明の課題は，特定
の温度範囲及び圧力範囲の中の、一定条件下に焼結操作
を行い、その結果、従来製造時に不可避的に発生する残
留応力が低減され、クラックが存在せず、かつ、機械的
強度の大きな亜鉛アンチモン及びカドミウムからなる化
学式β-(Zn1-xCdx)4Sb3（式中、Ｘ＝０〜０．３であり、
０を含まない。）で示される化合物の焼結体及びその製
造法を提供することである。The object of the present invention is to carry out a sintering operation under constant conditions within a specific temperature range and pressure range, and as a result, residual stress that is inevitably generated during conventional manufacturing is generated. Chemical formula β- (Zn 1-x Cd x ) 4 Sb 3 (where X = 0 to 0.3, which is reduced, has no cracks, and has high mechanical strength, and which is composed of zinc antimony and cadmium.
Does not include 0. The present invention provides a sintered body of the compound represented by the formula (1) and a method for producing the same.
【０００４】[0004]
【課題を解決する手段】本発明者らは，前記課題を研究
し、Ｚｎ、Ｃｄ及びＳｂ各成分の組み合わせからなり、
その割合がモル比で４．０対０以上（ただし、０を含ま
ない。）対３〜２．８対１．２対３．０の割合で混合さ
れた単体原料を、真空封入後、６５０〜７００℃の温度
下に溶融凝固させて得られる化学式β-(Zn1-xCdx)4Sb3
（式中、Ｘ＝０〜０．３であり、０を含まない。）の化
合物を、粉砕して粉体とし、引き続いて、圧力範囲が50
Mpa〜100MPaであり、かつ焼結温度が400℃以上、500℃
以下の一定条件下に緻密化処理を行い、終了後、温度が
焼結温度の９５％に到達する前迄に、前記圧力を解除す
ることにより得られる化学式β-(Zn1-xCdx)4Sb3（式中、
Ｘ＝０〜０．３であり、ただし、０を含まない。）の化
合物の焼結体は、従来知られている焼結体に不可避的に
見られた残留応力が低減され、かつクラックは存在せ
ず、機械的強度の大きな亜鉛、アンチモン及びカドミウ
ムからなる化学式β-(Zn1-xCdx)4Sb3（式中、Ｘ＝０〜
０．３であり、ただし、０を含まない。）で示される化
合物の焼結体が得られることを実験的に見出して、本発
明を完成させた。Means for Solving the Problems The present inventors have studied the above problems and formed a combination of Zn, Cd and Sb components,
A single raw material mixed in a molar ratio of 4.0: 0 or more (excluding 0): 3 to 2.8: 1.2: 3.0 was vacuum-enclosed at 650. Chemical formula β- (Zn 1-x Cd x ) 4 Sb 3 obtained by melting and solidifying at a temperature of ~ 700 ° C
The compound of the formula (where X = 0 to 0.3, not including 0) is pulverized into a powder, and subsequently, the pressure range is 50.
Mpa-100MPa, and sintering temperature is 400 ℃ or more, 500 ℃
The chemical formula β- (Zn 1-x Cd x ) obtained by performing the densification treatment under the following constant conditions and releasing the pressure after the completion and before the temperature reaches 95% of the sintering temperature 4 Sb 3 (where
X = 0 to 0.3, but 0 is not included. ) Is a chemical formula composed of zinc, antimony, and cadmium, which has a reduced residual stress, which is inevitable in conventionally known sintered bodies, has no cracks, and has high mechanical strength. β- (Zn 1-x Cd x ) 4 Sb 3 (where X = 0 to
0.3, but not including 0. The present invention has been completed by experimentally finding that a sintered body of the compound represented by the formula (1) can be obtained.
【０００５】本発明によれば、以下の発明が提供され
る。
（１）Ｚｎ、Ｃｄ及びＳｂ各成分の組み合わせからな
り、その割合がモル比で４．０対０以上（ただし、０を
含まない。）対３．０〜２．８対１．２対３．０の割合
で混合された粉体を真空封入後、６５０〜７００℃程度
の温度下で溶融凝固させて得られる化学式β-(Zn1-xC
dx)4Sb3（式中、Ｘ＝０〜０．３であり、ただし、０を含
まない。）で示される化合物を、粉砕して粉体とし、引
き続いて、圧力範囲が50MPa以上〜100MPa以下であり、
かつ焼結温度範囲が400℃〜500℃の、一定条件下に緻密
化処理を行い、終了後、温度がその温度の９５％に到達
する前迄に、前記圧力を解除することにより得られるこ
とを特徴とする化学式β-(Zn1-xCdx)4Sb3（式中、Ｘ＝０
〜０．３であり、ただし、０を含まない。）で示される
化合物の焼結体。
（２）Ｚｎ、Ｃｄ及びＳｂ各成分の組み合わせからな
り、その割合がモル比で、４対０以上（ただし、０を含
まない。）対３．０〜２．８対１．２対３．０の割合で
混合された粉体を真空封入後に、６５０〜７００℃程度
の温度に溶融凝固させて化学式β-(Zn1-xCdx)4Sb3（式
中、Ｘ＝０〜０．３であり、ただし、０を含まない。）
で示される化合物を製造し、引き続いて、圧力範囲が50M
Pa以上100MPa以下であり、かつ焼結温度範囲が400℃以
上、500℃以下の、一定条件下に緻密化処理を行い、終
了後、焼結温度がその温度の９５％に到達する前迄に、
前記圧力を解除することを特徴とする化学式β-(Zn1-xC
dx)4Sb3（式中、Ｘ＝０〜０．３であり、ただし、０を含
まない。）で示される化合物の焼結体の製造方法According to the present invention, the following inventions are provided. (1) It consists of a combination of each of Zn, Cd, and Sb components, and the molar ratio thereof is 4.0: 0 or more (however, 0 is not included): 3.0-2.8: 1.2: 3 Chemical formula β- (Zn 1-x C obtained by melting and solidifying powder mixed in a ratio of 0.0 in a vacuum and melting and solidifying at a temperature of about 650 to 700 ° C.
d x ) 4 Sb 3 (in the formula, X = 0 to 0.3, but does not include 0) is pulverized into a powder, and subsequently, the pressure range is 50 MPa or more. 100MPa or less,
Also, it can be obtained by performing a densification treatment under a constant condition of a sintering temperature range of 400 ° C to 500 ° C, and releasing the pressure after the completion and before the temperature reaches 95% of the temperature. The chemical formula β- (Zn 1-x Cd x ) 4 Sb 3 (where X = 0
~ 0.3, but not including 0. ) A sintered body of the compound represented by. (2) Consists of a combination of each of Zn, Cd, and Sb components, the molar ratio of which is 4: 0 or more (however, 0 is not included): 3.0 to 2.8: 1.2: 3. The powder mixed in a ratio of 0 was vacuum sealed, and then melted and solidified at a temperature of about 650 to 700 ° C. to obtain a chemical formula β- (Zn 1-x Cd x ) 4 Sb 3 (where X = 0 to 0. 3. However, 0 is not included.)
To produce a compound with a pressure range of 50M
Densification treatment is carried out under a certain condition of Pa or more and 100 MPa or less and sintering temperature range of 400 ° C or more and 500 ° C or less, and after completion, before the sintering temperature reaches 95% of that temperature. ,
The chemical formula β- (Zn 1-x C is characterized in that the pressure is released.
d x ) 4 Sb 3 (wherein X = 0 to 0.3, but does not include 0).
【０００６】[0006]
【発明の実施の形態】本発明の焼結体の原料には、亜鉛
とカドミウム及びアンチモンの各微紛体を用いる。原料
の純度は９９．９％以上、望ましくは９９．９９％以
上、より望ましくは９９．９９９％の原料を用いる。こ
れらは、１ｍｍ〜５ｍｍ程度の固体の粉体である。紛体
の形状については特に限定されるところはない。BEST MODE FOR CARRYING OUT THE INVENTION Fine powders of zinc, cadmium and antimony are used as raw materials for the sintered body of the present invention. A raw material having a purity of 99.9% or higher, preferably 99.99% or higher, and more preferably 99.999% is used. These are solid powders of about 1 mm to 5 mm. There is no particular limitation on the shape of the powder.
【０００７】原料である各粉体の亜鉛、カドミウム及び
アンチモンの割合が、モル比で化学式(Zn1-xCdx)4Sb
3（式中、Ｘ＝０〜０．３である。ただし、０を含まな
い。）で示される化合物となるように秤量し、ガラス製
の容器内に入れ、ガラス容器内を真空ポンプにより引
き、真空状態として、封じ切る。このガラス製容器を高
温保持が可能な炉の中に静置し、６５０〜７００℃程度
の温度で、原料の溶融混合を進行させる。通常５時間か
ら１０時間程度の溶融を行い、通常毎分１℃程度の割合
で除冷し、化学式β-(Zn1-xCdx)4Sb3（Ｘ＝０〜０．３
であり、ただし、０は含まない。）で示される化合物を
合成する。凝固した化学式β-(Zn1-xCdx)4Sb3（式中、
Ｘ＝０〜０．３であり、ただし、０を含まない。）で示
される化合物をインゴットに取り出した後、空気等の酸
化性ガスが存在しない条件下に粉砕し、粉体とする。The proportions of zinc, cadmium and antimony in each raw material powder are represented by chemical formula (Zn 1-x Cd x ) 4 Sb in molar ratio.
3 (in the formula, X = 0 to 0.3, but does not include 0) is weighed so as to be a compound, placed in a glass container, and the inside of the glass container is pulled by a vacuum pump. , As a vacuum state, seal off. This glass container is allowed to stand in a furnace capable of maintaining high temperature, and the melting and mixing of the raw materials proceeds at a temperature of about 650 to 700 ° C. Usually, it is melted for about 5 to 10 hours, and is usually cooled at a rate of about 1 ° C. per minute to obtain the chemical formula β- (Zn 1-x Cd x ) 4 Sb 3 (X = 0 to 0.3.
However, 0 is not included. ) Is synthesized. Solidified chemical formula β- (Zn 1-x Cd x ) 4 Sb 3 (where
X = 0 to 0.3, but 0 is not included. After taking out the compound represented by (4) into an ingot, it is pulverized in the absence of an oxidizing gas such as air to obtain a powder.
【０００８】このようにして得られる、化学式β-(Zn
1-xCdx)4Sb3（式中、Ｘ＝０〜０．３であり、ただし、０
を含まない。）の化合物の焼結処理を行う。焼結操作
は，圧力範囲が50MPa以上100MPa以下であり、かつ焼結
温度範囲が400℃以上500℃以下の、温度及び圧力が一定
の条件下に行う緻密化処理である。この緻密化処理を行
う装置としては，加圧及び加熱するための手段を有する
ものが用いられる。簡便には、一軸加圧式のホットプレ
スが用いられるが、より大型で均質な焼結を目指す場合
には等方的な加圧方式であるＨＩＰ焼結も利用すること
ができる。焼結操作の温度・圧力のプロフイルは図５に
示すとおりである。最高温度に達するまでの昇温速度
は、１０〜２０℃／ｍｉｎ．の範囲に設定される。焼結
操作の一定温度（４００〜５００℃）に到達したあと
は，この温度を保つように制御される。焼結操作に要す
る時間は適宜決定する。焼結温度に高い温度を採用し、
またカドミウム比率が多いほど、焼結時間は短い。また
焼結温度に低い温度を採用し、カドミウム比率が少ない
ほど、緻密化に要する時間は長くなる。具体的には、化
学式(Zn1-xCdx)4Sb3（式中，Ｘ＝０．１）で示される化
合物を、４５０℃の焼結温度により処理する場合におい
ては、焼結時間は８〜１０時間の時間をかけて行うこと
が望ましい。焼結操作が終了した後に、放置して、冷却
操作を開始する。冷却速度は、１０℃から２０℃／ｍｉ
ｎ．の範囲である。全体の温度が、焼結操作の温度であ
る９５％程度の温度になる前迄に、焼結操作の圧力を解
除する。この温度は重要な意味をもつ。この温度を過ぎ
て圧力を解除したのでは，残留応力が低減されていない
状態で、クラックが生じてしまったりして、効果を達成
することができない。The thus obtained chemical formula β- (Zn
1-x Cd x ) 4 Sb 3 (where X = 0 to 0.3, where 0
Does not include. ) Sintering treatment of the compound is performed. The sintering operation is a densification treatment performed under the conditions of constant pressure and temperature of 50 MPa to 100 MPa and sintering temperature range of 400 ° C to 500 ° C. As a device for performing this densification treatment, a device having means for pressurizing and heating is used. For simplicity, a uniaxial press hot press is used, but if a larger and more uniform sintering is aimed at, isotropic press HIP sintering can also be used. The temperature / pressure profile of the sintering operation is as shown in FIG. The temperature rising rate until reaching the maximum temperature is 10 to 20 ° C./min. It is set to the range of. After reaching the constant temperature (400 to 500 ° C.) of the sintering operation, the temperature is controlled to be kept at this temperature. The time required for the sintering operation is appropriately determined. Adopting a high sintering temperature,
Also, the higher the cadmium ratio, the shorter the sintering time. A low sintering temperature is adopted, and the smaller the cadmium ratio, the longer the time required for densification. Specifically, when the compound represented by the chemical formula (Zn 1-x Cd x ) 4 Sb 3 (where X = 0.1) is treated at a sintering temperature of 450 ° C., the sintering time is It is desirable to perform it for 8 to 10 hours. After the sintering operation is completed, it is left to stand and the cooling operation is started. Cooling rate is 10 ℃ to 20 ℃ / mi
n. Is the range. The pressure of the sintering operation is released before the whole temperature reaches a temperature of about 95% which is the temperature of the sintering operation. This temperature has important implications. If the pressure is released after this temperature is exceeded, the effect cannot be achieved because cracks may occur in the state where the residual stress is not reduced.
【０００９】本発明により得られる焼結体は、従来の加
圧焼結による焼結体の合成時に見られた不可避的に発生
する残留応力が低減され、クラックが存在しない、機械
的強度の大きな化学式β-(Zn1-xCdx)4Sb3（式中、Ｘ＝０
〜０．３であり、ただし、０を含まない。）で示される
化合物の焼結体である。The sintered body obtained according to the present invention has a reduced residual stress, which is inevitably generated when the sintered body is synthesized by conventional pressure sintering, is reduced, has no cracks, and has a large mechanical strength. Chemical formula β- (Zn 1-x Cd x ) 4 Sb 3 (where X = 0
~ 0.3, but not including 0. ) It is a sintered compact of the compound shown by.
【００１０】[0010]
【実施例】以下に，本発明について実施例により更に説
明する。本発明はこの実施例により限定されるものでは
ない。
実施例１
まず、亜鉛、カドミウム、アンチモン各単体元素を、亜
鉛3.2：カドミウム：0.8：アンチモン3のモル比となる
ように秤量し、ガラス製アンプルに１０−２Torrで真空
封入し、マッフル炉の中央に静置して６５０℃、１０時
間加熱溶融した後、開封してインゴットを取り出し、ア
ルゴンガスを満たしたグローブボックス内で、乳ばちを
用いて粉砕した。このようにして原料となるβ-(Zn0.8C
d0.2)4Sb3化合物の粉体を合成した。上記粉体を、グラ
ファイト製の一軸加圧プレス用のダイスに充填した。こ
の実施例では、直径１５mmφの円筒形のダイスであり、
上下からグラファイト製のパンチで加圧する仕組みのも
のを用いた。粉体は、焼結体の仕上がりの状態で厚さ３
mm程度となるように秤量し、充填した。このダイスを１
軸加圧式のホットプレス装置にセットし、アルゴンガス
雰囲気内でダイス温度４３３℃、７時間、１００MPaの
条件で焼結した。室温から４３３℃までの昇温速度は１
５℃/min.とした。この条件下に、７時間の焼結を行い、
その密度は十分に緻密化することができた。そして、７
時間の焼結後、速やかに圧力を解除し、その後、１５℃/
min.で除冷を開始した。このことで、加圧軸方向への体
積膨張の自由度が許され、内部応力が緩和されるること
となった。この条件で作製した試料の密度は6.53g／cm3
まで上がっており、顕微鏡観察によってもクラックが発
見されず、室温における抵抗率が4×10-5Ωm、ゼーベッ
ク係数が170μV/K、熱伝導率が0.7W/mKと、良好な熱電
特性を有することが確認できた。EXAMPLES The present invention will be further described below with reference to examples. The invention is not limited to this example. Example 1 First, each elemental element of zinc, cadmium, and antimony was weighed so as to have a molar ratio of zinc 3.2: cadmium: 0.8: antimony 3, vacuum-sealed in a glass ampoule at 10 -2 Torr, and placed in a muffle furnace. After standing still in the center and heating and melting at 650 ° C. for 10 hours, the container was opened, the ingot was taken out, and crushed with a bee in a glove box filled with argon gas. In this way, the raw material β- (Zn 0.8 C
were synthesized powder d 0.2) 4 Sb 3 compound. The above powder was filled in a die for uniaxial pressure press made of graphite. In this embodiment, a cylindrical die having a diameter of 15 mmφ,
A structure in which a graphite punch was used to apply pressure from above and below was used. The powder has a thickness of 3 in the finished state of the sintered body.
It was weighed and filled to a size of about mm. This die is 1
It was set in an axial press hot press and sintered in an argon gas atmosphere at a die temperature of 433 ° C. for 7 hours at 100 MPa. The rate of temperature rise from room temperature to 433 ° C is 1
It was set to 5 ° C./min. Sintering for 7 hours under these conditions,
The density could be sufficiently densified. And 7
After sintering for a period of time, the pressure is quickly released and then 15 ° C /
Cooling started at min. As a result, the degree of freedom of volume expansion in the direction of the pressing axis is allowed, and the internal stress is relaxed. The density of the sample produced under these conditions is 6.53 g / cm 3
No cracks were found by microscopic observation, the resistivity at room temperature was 4 × 10 -5 Ωm, the Seebeck coefficient was 170 μV / K, and the thermal conductivity was 0.7 W / mK, with good thermoelectric properties. I was able to confirm that.
【００１１】実施例２
実施例１の焼結方法の有効性を確認するために、実施例
１と同じ方法、作製条件により、焼結処理を行って緻密
化を行い、焼結圧力と同じ１００MPaの圧力をかけ続け
て、除冷をした結果、得られる焼結体の写真を図４aに示
す。比較のため、本発明の実施例１で製造した素子を図
４bに示す。圧力をかけながら除冷した前者の焼結体
は、ダイスから取り出した時点で無数のクラックを有し
ており、わずかな力で簡単に破砕された。このことか
ら、実用化は困難である事がわかった。本発明を適用し
た焼結体は、研削砥石による、厚み１ｍｍ以下の切り出
し作業やメッキ作業にも全く破砕する事なく、実用化に
必要な強度を有している事が確認できた。Example 2 In order to confirm the effectiveness of the sintering method of Example 1, sintering was performed under the same method and production conditions as Example 1 to densify it, and the sintering pressure was the same as 100 MPa. 4a shows a photograph of a sintered body obtained as a result of cooling by continuously applying the pressure. For comparison, the device manufactured in Example 1 of the present invention is shown in FIG. 4b. The former sintered body, which was cooled while applying pressure, had numerous cracks when it was taken out from the die, and was easily crushed with a slight force. From this, it was found that practical application is difficult. It was confirmed that the sintered body to which the present invention was applied had the strength required for practical use without being crushed at all by the grinding wheel even in the cutting work or plating work having a thickness of 1 mm or less.
【００１２】実施例３
実施例１の焼結方法が、他の異なるカドミウム含有量の
化学式β-(Zn1-xCdx)4Sb 3で示される化合物のＲウェル
関しても有効であることを確認するために、表１に示す
ようなカドミウム置換量の異なる試料を作製した。各焼
結体は、十分に緻密かつ機械的に頑丈であり、これらの
カドミウム置換量においても、本焼結方法が有効である
事を示すものである。Embodiment 3
The sintering method of Example 1 was applied to other different cadmium contents.
Chemical formula β- (Zn1-xCdx)FourSb 3R well of compound represented by
In order to confirm that it is also effective,
Samples with different amounts of cadmium substitution were prepared. Each grill
The union is compact and mechanically sturdy enough that these
This sintering method is effective even for the amount of cadmium substitution
It shows things.
【００１３】[0013]
【表１】 [Table 1]
【００１４】[0014]
【発明の効果】本発明により得られる焼結体は、加圧焼
結による焼結体の合成時に不可避的に発生する残留応力
が低減され、クラックが存在しない、機械的強度の大き
な亜鉛、アンチモン及びカドミウムからなる化学式β-
(Zn1-xCdx)4Sb3で表される焼結体であり、熱電特性、お
よび機械的な特性に優れた焼結体であり、熱電発電の材
料として用いることができる。INDUSTRIAL APPLICABILITY The sintered body obtained according to the present invention has reduced residual stress unavoidably generated during synthesis of the sintered body by pressure sintering, has no cracks, and has high mechanical strength, such as zinc and antimony. And the chemical formula β- consisting of cadmium
(Zn 1-x Cd x) is a sintered body represented by 4 Sb 3, a sintered body having excellent thermoelectric properties and mechanical properties, it can be used as the material of the thermoelectric generator.
【図１】熱電変換素子及び熱電変換素子を用いた熱電発
電の原理図FIG. 1 is a principle diagram of a thermoelectric conversion element and thermoelectric power generation using the thermoelectric conversion element.
【図２】熱電材料の性能指数[Figure 2] Performance index of thermoelectric materials
【図３】Ｚｎ−Ｓｂ系状態図FIG. 3 Zn-Sb system phase diagram
【図４】焼結体を示す図FIG. 4 is a diagram showing a sintered body.
【図５】本発明による焼結の温度／圧力のプロフイルを
示す図FIG. 5 is a diagram showing a sintering temperature / pressure profile according to the present invention.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 李 哲虎 茨城県つくば市東１−１−１ 独立行政法 人産業技術総合研究所つくばセンター内 Ｆターム(参考） 4K018 AA40 EA02 EA13 KA32 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Lee Tetsutora 1-1-1 Higashi 1-1-1 Tsukuba City, Ibaraki Prefecture Inside the Tsukuba Center, National Institute of Advanced Industrial Science and Technology F term (reference) 4K018 AA40 EA02 EA13 KA32
Claims (2)
らなり、その割合がモル比で４．０対０以上（ただし、
０を含まない。）対３．０〜２．８対１．２対３．０の
割合で混合された粉体を真空封入後、６５０〜７００℃
程度の温度下で溶融した後に凝固させて得られるβ-(Zn
1-xCdx)4Sb3（Ｘ＝０〜０．３であり、ただし、０を含
まない。）で示される化合物を、粉砕して粉体とし、引
き続いて、圧力範囲が50MPa以上〜100MPa以下であり、
かつ焼結温度範囲が400℃〜500℃の、一定条件下に緻密
化処理を行い、終了後、温度が焼結温度の９５％に到達
する前迄に、前記圧力を解除することにより得られるこ
とを特徴とする化学式β-(Zn 1-xCdx)4Sb3（式中、Ｘ＝０
〜０．３であり、ただし、０を含まない。）で示される
化合物の焼結体。1. A combination of Zn, Cd and Sb components
The molar ratio is 4.0: 0 or more (however,
Does not include 0. ) 3.0 to 2.8 to 1.2 to 3.0
After vacuum encapsulating the powder mixed in the ratio, 650-700 ℃
Β- (Zn obtained by melting at a certain temperature and then solidifying
1-xCdx)FourSb3(X = 0 to 0.3, including 0
I'm sorry. The compound represented by
Subsequently, the pressure range is 50 MPa or more to 100 MPa or less,
And the sintering temperature range is 400 ℃ ~ 500 ℃, dense under certain conditions
After the chemical treatment, the temperature reaches 95% of the sintering temperature after completion.
The pressure can be obtained by releasing the pressure before
The chemical formula β- (Zn 1-xCdx)FourSb3(In the formula, X = 0
~ 0.3, but not including 0. )
Compound sintered body.
らなり、その割合がモル比で、４対０以上（ただし、０
を含まない。）対３．０〜２．８対１．２対３．０の割
合で混合された粉体を真空封入後、６５０〜７００℃程
度の温度に溶融した後に凝固させてβ-(Zn1-xCdx)4Sb3
（Ｘ＝０〜０．３であり、ただし、０を含まない。）で
示される化合物を製造し、引き続いて、圧力範囲が50MPa
以上100MPa以下であり、かつ焼結温度範囲が400℃以
上、500℃以下の、一定条件下に緻密化処理を行い、終
了後、焼結温度がその温度の９５％に到達する前迄に、
前記圧力を解除することを特徴とする化学式β-(Zn1-xC
dx)4Sb3（式中、Ｘ＝０〜０．３であり、ただし、０を含
まない。）で示される化合物の焼結体の製造方法2. A combination of Zn, Cd, and Sb components, the molar ratio of which is 4: 0 or more (provided that 0:
Does not include. ): 3.0 to 2.8: 1.2: powder mixed in a ratio of 3.0 to 3.0 is vacuum sealed, melted at a temperature of about 650 to 700 ° C., and then solidified to form β- (Zn 1- x Cd x ) 4 Sb 3
(X = 0 to 0.3, but not including 0) was prepared, and subsequently, the pressure range was 50 MPa.
The densification treatment is performed under a constant condition of not less than 100 MPa and not less than 100 MPa and a sintering temperature range of not less than 400 ° C. and not more than 500 ° C., and after completion, before the sintering temperature reaches 95% of that temperature,
The chemical formula β- (Zn 1-x C is characterized in that the pressure is released.
d x ) 4 Sb 3 (wherein X = 0 to 0.3, but does not include 0).
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