JP2006108419A - Manufacturing method of thermoelectric material and thermoelement - Google Patents

Manufacturing method of thermoelectric material and thermoelement Download PDF

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JP2006108419A
JP2006108419A JP2004293562A JP2004293562A JP2006108419A JP 2006108419 A JP2006108419 A JP 2006108419A JP 2004293562 A JP2004293562 A JP 2004293562A JP 2004293562 A JP2004293562 A JP 2004293562A JP 2006108419 A JP2006108419 A JP 2006108419A
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thermoelectric material
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Akihiro Nozue
章浩 野末
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Panasonic Holdings Corp
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Matsushita Electric Industrial Co Ltd
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<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a high performance thermoelectric material having uniform and minute crystal, which manufactures a plastic working article with sufficient yield without a crack in hot plastic work of the thermoelectric material in the thermoelectric material where heat used in electronic cooling and thermoelectric generation is converted into electricity and in the manufacturing method of the thermoelectric material. <P>SOLUTION: The thermoelectric material containing one type of element selected from a group formed of bismuth and antimony and at least one type of element selected from a group formed of tellurium and selenium is formed in a rolled stock 6 by a rolling method. Hot plastic deformation and formation are performed on the rolled stock 6 in a direction parallel to a rolling direction. Thus, the thermoelectric material superior in yield can be obtained without the crack. Crystal orientation after plastic deformation is improved much more and thermoelectric performance can be improved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、熱を電気に変換する熱電材料の製造方法および熱電素子に関するものである。   The present invention relates to a method for producing a thermoelectric material that converts heat into electricity and a thermoelectric element.

一般に、熱電素子は、Ｐ型半導体とＮ型半導体をＣｕ等の金属電極を介し、電気的に直列に接合し、電流を流すことにより一方の面が発熱し、一方の面が冷却する性質を有している。そして、電流の向きを反対にすると発熱と冷却も反対になる。   In general, a thermoelectric element has the property that one surface generates heat and the other surface cools by electrically connecting a P-type semiconductor and an N-type semiconductor in series via a metal electrode such as Cu and passing a current. Have. And if the direction of current is reversed, heat generation and cooling are also reversed.

このようなペルチェ効果あるいはゼーベック効果は、電子冷却や熱電発電に利用されている。具体的には、センサー素子や光素子、ＬＳＩ基板などの半導体回路、宇宙ステーションで使用される電子機器の冷却、レーザーダイオード等の精密温度制御が要求されるところに使用されている。   Such Peltier effect or Seebeck effect is used for electronic cooling and thermoelectric power generation. Specifically, it is used in places where precise temperature control is required for sensor elements, optical elements, semiconductor circuits such as LSI substrates, cooling of electronic equipment used in the space station, and laser diodes.

熱電材料には多くの系が存在するが、中でもテルル化ビスマス（Ｂｉ２Ｔｅ３）、セレン化ビスマス（Ｂｉ２Ｓｅ３）及びテルル化アンチモン（Ｓｂ２Ｔｅ３）のような熱電材料は、室温付近で使用できる材料である。前記Ｂｉ２Ｔｅ３系の化合物は、菱面体結晶の単位胞中に、ＢｉとＴｅの原子をそれぞれ２と３個を含む層状構造で物理的性質に大きな異方性を持つ。この構造は六方晶表示のＣ軸方向にＴｅ原子層の重なりが３組存在し、このＴｅ−Ｔｅ原子の結合は、ファン・デル・ワールス結合のため、共有結合やイオン結合およびそれらの混合結合で結合した他の原子間の結合より著しく弱く、容易に劈開する一方、Ｃ軸方向に垂直（Ｃ面に平行）な方向で電気特性が高い性質を備えている。熱電材料の特性を表す性能指数Ｚは（数１）で示すようにゼーベック係数αの２乗と電気伝導率σの積を熱伝導率κで割ったもので表される。 There are many systems of thermoelectric materials, among which thermoelectric materials such as bismuth telluride (Bi 2 Te 3 ), bismuth selenide (Bi 2 Se 3 ) and antimony telluride (Sb 2 Te 3 ) It is a material that can be used nearby. The Bi 2 Te 3 compound has a large anisotropy in physical properties with a layered structure containing 2 and 3 atoms of Bi and Te, respectively, in a unit cell of rhombohedral crystals. In this structure, there are three sets of overlapping Te atom layers in the C-axis direction of hexagonal display, and the Te-Te atom bond is a van der Waals bond. It is remarkably weaker than the bonds between other atoms bonded at, and is easily cleaved, while it has high electrical properties in a direction perpendicular to the C-axis direction (parallel to the C-plane). The figure of merit Z representing the characteristics of the thermoelectric material is expressed by the product of the square of the Seebeck coefficient α and the electrical conductivity σ divided by the thermal conductivity κ, as shown in (Equation 1).

Figure 2006108419
Figure 2006108419

したがって、Ｃ面方向では、性能指数も高くなる。   Therefore, the figure of merit also increases in the C-plane direction.

一般に、前記Ｂｉ２Ｔｅ３化合物のような異方性材料は、ブリッジマン法等で一方向凝固させて作製する。これらは結晶の配向性が整っている。 In general, an anisotropic material such as the Bi 2 Te 3 compound is produced by unidirectional solidification by the Bridgman method or the like. These have a well-oriented crystal orientation.

しかし、Ｔｅ−Ｔｅ原子の結合がファン・デル・ワールス結合のため、材料強度も脆く、劈開しやすいため、素子化する際の加工時に割れやすいという問題がある。   However, since the Te-Te atom bond is a van der Waals bond, the material strength is brittle and it is easy to cleave.

そこで、焼結法や塑性加工といった手段を用い、機械的特性が優れた熱電材料の作製法が考案された（例えば、特許文献１参照）。   Therefore, a method for producing a thermoelectric material having excellent mechanical properties has been devised using means such as a sintering method or plastic working (see, for example, Patent Document 1).

そして、さらに結晶配向性が高く、かつ十分な強度をもつ熱電材料の作製法として、塑性変形加工により、熱電材料粉末を熱間押出加工する作製方法（例えば、特許文献２参照）、あるいは一方向凝固材料を熱間押出加工する作製方法が提案された（例えば、特許文献３参照）。   Further, as a method for producing a thermoelectric material having higher crystal orientation and sufficient strength, a production method in which a thermoelectric material powder is hot-extruded by plastic deformation (for example, see Patent Document 2), or one-way. A production method for hot extruding a solidified material has been proposed (see, for example, Patent Document 3).

図４は、前記特許文献３に記載された従来の熱間押出加工の工程を示す概略図である。   FIG. 4 is a schematic view showing a conventional hot extrusion process described in Patent Document 3.

図４に示すように、Ｂｉ及びＳｂからなる群から選択された少なくとも１種の元素と、Ｔｅ及びＳｅからなる群から選択された少なくとも１種の元素とを含む組成又はこれにＩ、Ｃｌ、Ｈｇ、Ｂｒ、Ａｇ及びＣｕからなる群から選択された少なくとも１種の元素を含む組成の熱電材料の素材２０を用意する。この素材２０は丸棒であり、Ｃ軸方向が長手方向に直交し、Ｃ面方向が一方向に揃ったものである。このような素材は例えば、一方向凝固法により作製することができる。   As shown in FIG. 4, a composition comprising at least one element selected from the group consisting of Bi and Sb and at least one element selected from the group consisting of Te and Se, or I, Cl, A thermoelectric material 20 having a composition containing at least one element selected from the group consisting of Hg, Br, Ag, and Cu is prepared. The material 20 is a round bar in which the C-axis direction is orthogonal to the longitudinal direction and the C-plane direction is aligned in one direction. Such a material can be produced, for example, by a unidirectional solidification method.

この素材２０を、ダイス２１により素材の長手方向に押出加工する。この場合に、通常、押出加工においては、素材を軟化させるために、ヒーター５２により押出加工時の素材を加熱するが、このとき、加熱温度は加工後の熱電材料２３が再結晶しない程度のものとする。そうすることにより、Ｃ面方向が一方向に揃った素材２０を押出加工するので、押出後の材料２３は、そのＣ面方向が一方向に揃ったままで、結晶粒が微細化する。その結果、押出前の素材２０に対して、結晶粒が微細化し、これにより、押出前の素材２０に比して、押出後の材料２３は、熱伝導率κが低下し、電気抵抗ρは変化しない。
特開昭６２−２６４６８２号公報 特開平１０−５６２１０号公報 特開平１１−１６３４２２号公報 This material 20 is extruded in the longitudinal direction of the material by a die 21. In this case, normally, in the extrusion process, in order to soften the material, the material during the extrusion process is heated by the heater 52. At this time, the heating temperature is such that the thermoelectric material 23 after the process is not recrystallized. And By doing so, since the raw material 20 in which the C-plane direction is aligned in one direction is extruded, the extruded material 23 is finely crystallized while the C-plane direction is aligned in one direction. As a result, the crystal grains become finer than the raw material 20 before extrusion, and as a result, the material 23 after extrusion has a lower thermal conductivity κ and an electrical resistance ρ than the raw material 20 before extrusion. It does not change.
Japanese Patent Laid-Open No. 62-264682 JP-A-10-56210 JP-A-11-163422

しかしながら、上記従来の構成では、押出加工前の素材２０の結晶方向は揃っているが、結晶自体の粒径が一方向凝固材だと数ｍｍから数十ｍｍと非常に大きいため、押出加工の際に結晶が滑りにくくなり、クラックが生じるなど、歩留まりが悪くなる。   However, in the above conventional configuration, the crystal direction of the raw material 20 before extrusion is uniform, but the grain size of the crystal itself is very large, from several mm to several tens mm when it is a unidirectional solidified material. At this time, the crystal becomes difficult to slip and cracks are generated, resulting in poor yield.

また、押出加工による塑性変形で動的再結晶化による結晶の微細化効果も見られるが、ところどころ大きな結晶が残りやすく、性能にバラツキが生じる問題があった。   In addition, although there is an effect of refining the crystal by dynamic recrystallization due to plastic deformation by extrusion, there is a problem that large crystals tend to remain in some places and the performance varies.

また、一方向凝固材ではなく、熱電材料粉末を押出加工する場合、押出加工前の結晶配向方向がばらばらで、押出加工後の結晶配向度が低下する問題があった。   Further, when extruding a thermoelectric material powder instead of a unidirectionally solidified material, there is a problem that the crystal orientation direction before the extrusion process is different and the degree of crystal orientation after the extrusion process is lowered.

本発明は、熱電材料の熱間塑性加工において、クラックが生じることもなく、歩留まりの良い塑性加工品を作製するとともに、均一で微細な結晶をもち、高い結晶配向性を有することで高性能な熱電材料の作製方法を提供することを目的とする。   The present invention produces high-yield plastic processed products without cracks in hot plastic processing of thermoelectric materials, and has high performance by having uniform and fine crystals and high crystal orientation. An object is to provide a method for manufacturing a thermoelectric material.

上記従来の課題を解決するために、本発明の熱電材料の作製方法は、ビスマスおよびアンチモンからなる群から選択された少なくとも一種の元素と、テルルおよびセレンからなる群から選択された少なくとも一種の元素とを含有した熱電材料の製造方法であって、前記熱電材料を圧延法により圧延体を形成し、前記圧延体を圧延方向と平行な方向に熱間塑性変形を行い、形成するものである。   In order to solve the above-described conventional problems, a method for producing a thermoelectric material of the present invention includes at least one element selected from the group consisting of bismuth and antimony, and at least one element selected from the group consisting of tellurium and selenium. Is a method of producing a thermoelectric material containing the above-mentioned, wherein a rolled body is formed by rolling the thermoelectric material, and the rolled body is hot plastically deformed in a direction parallel to the rolling direction.

これによって、熱電材料は巨大な結晶粒を有しないため、熱間塑性加工により熱電材料はスムーズに塑性変形し、クラックも生じることがなく、歩留まりの優れた熱電材料を得ることができる。また、均一な組織を有するため、安定した性能の熱電材料を得ることができる。さらに、圧延法により塑性変形前の熱電材料のＣ面方向は、圧延方向と平行な方向に揃っており、圧延方向と平行な方向に熱間塑性変形することで、塑性変形後はさらにＣ面の配向性が向上し、熱電性能を向上させることができる。   As a result, since the thermoelectric material does not have huge crystal grains, the thermoelectric material is smoothly plastically deformed by hot plastic working, and cracks are not generated, and a thermoelectric material having an excellent yield can be obtained. Moreover, since it has a uniform structure, a thermoelectric material with stable performance can be obtained. Furthermore, the C-plane direction of the thermoelectric material before plastic deformation by the rolling method is aligned in a direction parallel to the rolling direction, and by further hot plastic deformation in the direction parallel to the rolling direction, the C-plane direction is further increased after plastic deformation. The orientation of can be improved and the thermoelectric performance can be improved.

また、ビスマス、アンチモン、テルル、セレンからなる群から少なくとも二つ以上を含有した熱電材料、具体例としてＢｉ２Ｔｅ３、Ｂｉ２Ｓｅ３、Ｓｂ２Ｔｅ３といった熱電材料の単体もしくは固溶体の熱電材料は、熱間塑性加工により変形方向と平行にＣ面が配向するため、歩留まりが良く、均質であるとともに、性能の向上を図ることができる。 Further, a thermoelectric material containing at least two or more from the group consisting of bismuth, antimony, tellurium, and selenium, specifically, a thermoelectric material of a thermoelectric material such as Bi 2 Te 3 , Bi 2 Se 3 , or Sb 2 Te 3 or a solid solution thermoelectric material Since the C-plane is oriented in parallel with the deformation direction by hot plastic working, the yield is good and uniform, and the performance can be improved.

また、本発明の熱電材料の作製方法は、前記熱電材料を粉末圧粉体とすることにより、巨大な結晶粒が混入することを防ぎ、より均質な性能の熱電材料を得ることができる。   Further, in the method for producing a thermoelectric material of the present invention, by using the thermoelectric material as a powder compact, enormous crystal grains can be prevented from being mixed, and a thermoelectric material with more uniform performance can be obtained.

また、本発明の熱電材料の作製方法は、前記粉末圧粉体を一軸加圧法で作製し、加圧方向と垂直な方向に圧延したもので、加圧方向とは垂直な方向にＣ面の結晶配向が揃うため、非常に簡便な方法で、さらに圧延体の結晶配向性を高めることができ、より高性能な熱電材料を作製することができる。   The thermoelectric material manufacturing method of the present invention is a method in which the powder compact is manufactured by a uniaxial pressing method and rolled in a direction perpendicular to the pressing direction. Since the crystal orientation is uniform, the crystal orientation of the rolled body can be further enhanced by a very simple method, and a higher performance thermoelectric material can be produced.

また、本発明の熱電材料の作製方法は、前記熱間塑性変形を、熱間押出加工としたもので、熱間押出加工では、押出方向と平行な方向にＣ面が配向するため、もとよりＣ面の配向性が高い熱電材料の圧延体を、さらに結晶配向性を高め、熱電性能を向上させると共に、歩留まりが良く、均質な熱電材料を作製することができる。   The method for producing a thermoelectric material according to the present invention is a method in which the hot plastic deformation is a hot extrusion process. In the hot extrusion process, the C plane is oriented in a direction parallel to the extrusion direction. A rolled body of a thermoelectric material with high surface orientation can further improve crystal orientation, improve thermoelectric performance, and can produce a uniform thermoelectric material with high yield.

また、本発明の熱電材料の製造方法により作製した熱電材料からなる熱電素子は、Ｃ面と平行な方向に電流が流れるように作製することで、高性能化がはかれる。   In addition, a thermoelectric element made of a thermoelectric material produced by the method for producing a thermoelectric material of the present invention can be improved in performance by producing so that a current flows in a direction parallel to the C plane.

本発明の熱電材料の製造方法は、従来の課題を解決するもので、ビスマス、アンチモン、テルル、セレンからなる群から少なくとも二つ以上を含有した熱電材料であって、圧延材を圧延材のＣ面と同方向に熱間塑性加工を行うことで、さらに結晶配向性が向上し、歩留まりが良く、均質であるとともに、結晶配向性が高く、高性能の熱電材料を作製することができる。   The method for producing a thermoelectric material of the present invention solves the conventional problems, and is a thermoelectric material containing at least two or more from the group consisting of bismuth, antimony, tellurium and selenium, and the rolled material is C By performing hot plastic working in the same direction as the surface, the crystal orientation is further improved, the yield is good, and the crystal orientation is high, and a high performance thermoelectric material can be produced.

さらに、初期素材を粉末圧粉体とすることで、結晶の不均質性をなくし、均質で微細な結晶群を有した高性能熱電材料を作製することができる。   Furthermore, by using a powder compact as the initial material, it is possible to eliminate the heterogeneity of crystals and to produce a high-performance thermoelectric material having a homogeneous and fine crystal group.

請求項１に記載の発明は、ビスマスおよびアンチモンからなる群から選択された少なくとも一種の元素と、テルルおよびセレンからなる群から選択された少なくとも一種の元素とを含有した熱電材料の製造方法であって、前記熱電材料を圧延法により圧延体を形成し、前記圧延体を圧延方向と平行な方向に熱間塑性変形を行い、形成するものである。   The invention according to claim 1 is a method for producing a thermoelectric material containing at least one element selected from the group consisting of bismuth and antimony and at least one element selected from the group consisting of tellurium and selenium. Then, a rolled body is formed by rolling the thermoelectric material, and the rolled body is subjected to hot plastic deformation in a direction parallel to the rolling direction.

その結果、熱電材料は巨大な結晶粒を有しないため、熱間塑性加工により熱電材料はスムーズに塑性変形し、クラックも生じることがなく、歩留まりの優れた熱電材料を得ることができる。また、均一な組織を有するため、安定した性能の熱電材料を得ることができる。さらに、圧延法により塑性変形前の熱電材料のＣ面方向は圧延方向と平行な方向に揃っており、圧延方向と平行な方向に熱間塑性変形することで、塑性変形後はさらにＣ面の配向性が向上し、熱電性能を向上させることができる。   As a result, since the thermoelectric material does not have huge crystal grains, the thermoelectric material is smoothly plastically deformed by hot plastic working, and cracks are not generated, and a thermoelectric material having an excellent yield can be obtained. Moreover, since it has a uniform structure, a thermoelectric material with stable performance can be obtained. Furthermore, the C-plane direction of the thermoelectric material before plastic deformation by the rolling method is aligned in a direction parallel to the rolling direction. By hot plastic deformation in the direction parallel to the rolling direction, the C-plane direction is further increased after plastic deformation. The orientation can be improved and the thermoelectric performance can be improved.

さらに、ビスマス、アンチモン、テルル、セレンからなる群から少なくとも二つ以上を含有した熱電材料、具体例としてＢｉ２Ｔｅ３、Ｂｉ２Ｓｅ３、Ｓｂ２Ｔｅ３といった熱電材料の単体もしくは固溶体の熱電材料は、熱間塑性加工により変形方向と平行にＣ面が配向するため、歩留まりが良く、均質であるとともに、性能の向上を図ることができる。 Further, a thermoelectric material containing at least two or more from the group consisting of bismuth, antimony, tellurium, and selenium, specifically, a thermoelectric material of a thermoelectric material such as Bi 2 Te 3 , Bi 2 Se 3 , Sb 2 Te 3 or a solid solution thermoelectric material Since the C-plane is oriented in parallel with the deformation direction by hot plastic working, the yield is good and uniform, and the performance can be improved.

請求項２に記載の発明は、前記熱電材料を、粉末圧粉体としたものである。   According to a second aspect of the present invention, the thermoelectric material is a powder compact.

これにより、巨大な結晶粒が混入することを防ぎ、より均質な性能の熱電材料を得ることができる。   Thereby, it is possible to prevent enormous crystal grains from being mixed, and to obtain a thermoelectric material with more uniform performance.

請求項３に記載の発明は、前記粉末圧粉体を一軸加圧法で作製し、加圧法方向と垂直な方向に圧延したものである。   According to a third aspect of the present invention, the powder compact is produced by a uniaxial pressing method and rolled in a direction perpendicular to the pressing method direction.

その結果、熱電材料粉末を一軸加圧法で成形することで、加圧方向とは垂直な方向にＣ面の結晶配向が揃うため、非常に簡便な方法で、さらに圧延体の結晶配向性を高めることができ、より高性能な熱電材料を作製することができる。   As a result, by forming the thermoelectric material powder by the uniaxial pressing method, the crystal orientation of the C-plane is aligned in a direction perpendicular to the pressing direction, so the crystal orientation of the rolled body is further enhanced by a very simple method. Therefore, a higher performance thermoelectric material can be produced.

請求項４に記載の発明は、前記熱間塑性変形を、熱間押出加工としたものである。   According to a fourth aspect of the present invention, the hot plastic deformation is a hot extrusion process.

この熱間押出加工では、押出方向と平行な方向にＣ面が配向するため、もとよりＣ面の配向性が高い熱電材料の圧延体を、さらに結晶配向性を高め、熱電性能を向上させると共に、歩留まりが良く、均質な熱電材料を作製することができる。   In this hot extrusion process, since the C plane is oriented in a direction parallel to the extrusion direction, a rolled body of a thermoelectric material with high orientation of the C plane is further enhanced, further improving the crystal orientation, improving the thermoelectric performance, The yield is good and a homogeneous thermoelectric material can be manufactured.

請求項５に記載の発明は、熱電素子を、上記請求項１から４に記載の熱電材料の製造方法により作製した熱電材料で作成し、さらに、Ｃ面と平行な方向に電流が流れるように作製したものである。   According to a fifth aspect of the present invention, the thermoelectric element is made of the thermoelectric material produced by the method for producing a thermoelectric material according to the first to fourth aspects, and a current flows in a direction parallel to the C plane. It was produced.

このように、Ｃ面と平行な方向に電流が流れるように熱電素子を作製することで、高性能な熱電素子を提供することができる。   Thus, a high-performance thermoelectric element can be provided by manufacturing the thermoelectric element so that a current flows in a direction parallel to the C plane.

以下、本発明の実施の形態について、図面を参照しながら説明する。なお、この実施の形態によってこの発明が限定されるものではない。   Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments.

（実施の形態１）
図１は本発明の実施の形態１における一軸加圧工程を示す概略図である。図１に示すように、本実施の形態１における一軸加圧工程は、ダイス１とパンチ２と結晶粒径が０．０１〜５００μｍである熱電材料の粉末３と、一軸加圧工程後に作製される圧粉体４とで構成されている。図１の（ａ）は一軸加圧工程前の状態を、（ｂ）は一軸加圧工程後の状態を表している。 (Embodiment 1)
FIG. 1 is a schematic diagram showing a uniaxial pressurizing step in Embodiment 1 of the present invention. As shown in FIG. 1, the uniaxial pressing step in the first embodiment is made after a die 1, a punch 2, a thermoelectric material powder 3 having a crystal grain size of 0.01 to 500 μm, and a uniaxial pressing step. And the green compact 4. FIG. 1A shows a state before the uniaxial pressing step, and FIG. 1B shows a state after the uniaxial pressing step.

以上のように構成された一軸加圧工程延工程について、具体例を用いてその動作を説明する。   The operation of the uniaxial pressurizing process extending process configured as described above will be described using a specific example.

まず、ダイス１中にパンチ２で上下を挟む形で、熱電材料の粉末３を設置する。前記熱電材料は、原料としてはＶ族元素であるＳｂやＢｉを、ＶＩ族元素であるＳｅやＴｅとを合金化して用いる。前記Ｖ族元素とＶＩ族元素の固溶体は、六方晶構造を有する。熱電材料の具体的な組成としては、Ｐ型熱電材料として、Ｂｉ２Ｔｅ３とＳｂ２Ｔｅ３との混晶系固溶体にＰ型のドーパントを添加して用いたり、Ｎ型熱電材料として、Ｂｉ２Ｔｅ３とＢｉ２Ｓｅ３との混晶系固溶体にＮ型のドーパントを添加して用いる。 First, a thermoelectric material powder 3 is placed in a die 1 so that the upper and lower sides are sandwiched by punches 2. As the raw material, the thermoelectric material uses Sb or Bi, which is a V group element, and Se or Te, which is a VI group element, as an alloy. The solid solution of the group V element and the group VI element has a hexagonal crystal structure. As a specific composition of the thermoelectric material, as a P-type thermoelectric material, a mixed crystal solid solution of Bi 2 Te 3 and Sb 2 Te 3 is used by adding a P-type dopant, or as an N-type thermoelectric material, Bi An N-type dopant is added to a mixed crystal solid solution of 2 Te 3 and Bi 2 Se 3 and used.

また、熱電材料の粉末３は粒径が小さければ小さい程良い。   The smaller the particle size of the thermoelectric material powder 3, the better.

次に、パンチ２を上下方向から２５０ＭＰａで一軸加圧する事で、熱電材料の粉末３は加圧方向と垂直方向にＣ面が配向し、圧粉体４が得られる。この時、圧粉体４は加圧方向とは垂直な方向にＣ面が配向する。   Next, the punch 2 is uniaxially pressed from above and below at 250 MPa, so that the C surface of the thermoelectric material powder 3 is oriented in the direction perpendicular to the pressing direction, and a green compact 4 is obtained. At this time, the green surface 4 of the green compact 4 is oriented in a direction perpendicular to the pressing direction.

図２は本発明の実施の形態１における圧延工程を示す概略図である。図２に示すように、本実施の形態１における圧延工程は、ロール５により熱電材料が、直方体形の圧延材６に形成する。圧延材６は圧延方向に平行にＣ面が配向する。   FIG. 2 is a schematic diagram showing a rolling process in the first embodiment of the present invention. As shown in FIG. 2, in the rolling process according to the first embodiment, a thermoelectric material is formed on a cuboid rolled material 6 by a roll 5. The rolled material 6 has a C-plane oriented parallel to the rolling direction.

なお、圧延材６は直方体に限らず、円柱でも構わない。   The rolled material 6 is not limited to a rectangular parallelepiped, and may be a cylinder.

図３は本発明の実施の形態１における熱間押出加工の工程を示す概略図である。図３に示すように、本実施の形態１における熱間押出工程は、ダイス７とダイス７の中に前記一軸加圧工程で作製した圧延材６とパンチ８とがあり、ダイス７の回りをヒーター７で取り囲み、加圧装置１０がパンチ８を上部から加圧するようになっており、加圧後、押出成型品１１がダイス７の下部から押し出されるように構成されている。   FIG. 3 is a schematic view showing a hot extrusion process in Embodiment 1 of the present invention. As shown in FIG. 3, the hot extrusion process in the first embodiment includes a die 7 and a rolled material 6 and a punch 8 produced in the uniaxial pressing process in the die 7. Surrounded by the heater 7, the pressurizing device 10 pressurizes the punch 8 from above, and the extrudate 11 is extruded from the bottom of the die 7 after pressurization.

以上のように構成された熱間押出工程について、以下その動作、作用を説明する。   About the hot extrusion process comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

まず、ダイス７を、ヒーター７で所定の温度にまで加熱する。所定の温度に達した後、ダイス７内に圧延材６をＣ面方向が押出方向と平行になるように入れ、その上にパンチ８を設置する。前記圧延材６の温度が上昇するまで数分間放置後、加圧装置１０にて前記パンチ８を押出方向に加圧する。それによりダイス７の下部から、押出成型品１１が押し出される。   First, the die 7 is heated to a predetermined temperature by the heater 7. After reaching a predetermined temperature, the rolled material 6 is placed in the die 7 so that the C-plane direction is parallel to the extrusion direction, and a punch 8 is placed thereon. After leaving for several minutes until the temperature of the rolling material 6 rises, the pressing device 10 pressurizes the punch 8 in the extrusion direction. Thereby, the extrusion-molded product 11 is extruded from the lower part of the die 7.

以上のようにして得られた熱電材料は、圧粉体から形成した圧延材が一方向凝固材のように結晶粒径が大きくないため、熱間押出加工により熱電材料はスムーズに塑性変形し、クラックも生じず、歩留まりの優れた熱電材料を得ることができる。また、均一な組織を有するため、安定した性能の熱電材料を得ることができる。   The thermoelectric material obtained as described above has a rolled material formed from a green compact, and the crystal grain size is not as large as a unidirectional solidified material. Therefore, the thermoelectric material is smoothly plastically deformed by hot extrusion, Cracks do not occur and a thermoelectric material excellent in yield can be obtained. Moreover, since it has a uniform structure, a thermoelectric material with stable performance can be obtained.

さらに、Ｂｉ２Ｔｅ３系の熱電材料は、押出方向にＣ面の結晶配向性が揃い、また圧延材のＣ面方向が押出方向と平行であることで、押出成型品の結晶配向性が効率よくかつ高くなり、それにより性能指数がさらに向上する効果も有する。 Furthermore, the Bi 2 Te 3 series thermoelectric material has the C-plane crystal orientation aligned in the extrusion direction, and the C-plane direction of the rolled material is parallel to the extrusion direction, so that the crystal orientation of the extruded product is efficient. It also has the effect of improving the figure of merit by improving the performance index.

熱電材料粉末の作製方法としては、メカニカルアロイング法、インゴットの熱電材料を機械的に粉砕するメカニカルグラインディング法、電気析出法、ガスアトマイズ法など種々存在するが、一つに限定されるものではない。   There are various methods for producing a thermoelectric material powder, such as a mechanical alloying method, a mechanical grinding method for mechanically pulverizing a thermoelectric material of an ingot, an electrodeposition method, and a gas atomization method, but is not limited to one. .

熱電材料粉末は、平均粒度分布が均一なほど均質性は増し、また、微細なほど熱伝導率を減少させる効果があり、かつ押出後の相対密度が増加し、より好ましい。   The homogeneity of the thermoelectric material powder is more preferable as the average particle size distribution is more uniform, and the finer the particle size is, the more effective the heat conductivity is and the relative density after extrusion increases.

また、圧延は、一軸加圧方向と垂直な方向に圧延を行うことによりＣ面配向の効率が良いが、ＣＩＰで形成した圧粉体や、圧粉後、焼結を行った焼結材でも構わない。   In addition, rolling is efficient in the C-plane orientation by rolling in a direction perpendicular to the uniaxial pressing direction, but even with a green compact formed by CIP or a sintered material that has been sintered after compacting I do not care.

さらに、圧延の圧延率を変えることにより、圧延材のＣ面配向率を変えることができ、また、圧延材の厚さが薄いときは、２枚以上の圧延材を重ねて熱間塑性変形を行っても構わない。   Furthermore, by changing the rolling rate of rolling, the C-plane orientation rate of the rolled material can be changed, and when the rolled material is thin, two or more rolled materials are stacked and subjected to hot plastic deformation. You can go.

また、熱電材料粉末は、表面積が増加するため、表面酸化されやすい。従って、水素還元等により、表面の還元処理を施す方がより好ましい。   Moreover, since the surface area of the thermoelectric material powder is increased, the surface is easily oxidized. Therefore, it is more preferable to perform surface reduction treatment by hydrogen reduction or the like.

一軸加圧は、ダイスの形状は問わず、円柱形でも四角柱形でも問題はない。   Uniaxial pressurization does not matter in the shape of the die, and there is no problem with either a cylindrical shape or a quadrangular prism shape.

さらに、押出成型品１１を押出方向に平行な方向に電流が流れるように加工し、素子を作製することで、材料強度に優れ、製造時の歩留まりも高く、また均質な性能の高性能熱電素子とすることができる。   Furthermore, the extruded product 11 is processed so that an electric current flows in a direction parallel to the extrusion direction, and an element is manufactured. Thus, a high-performance thermoelectric element having excellent material strength, high yield in manufacturing, and uniform performance. It can be.

また、熱間押出工程の際、押出温度は４７３Ｋ以上８２３Ｋ以下で行うことにより、熱間押出成形がさらに良好に行われ、動的再結晶により成型品の結晶粒はより微細化され、熱伝導率もより低減し、より高性能の熱電材料とすることができる。   In addition, during the hot extrusion process, the extrusion temperature is 473K or more and 823K or less, so that the hot extrusion is further improved, and the crystal grains of the molded product are further refined by dynamic recrystallization, and the heat conduction. The rate is further reduced, and a higher performance thermoelectric material can be obtained.

以上のように本発明にかかる熱電材料の製造方法によれば、熱電材料は巨大な結晶粒を有しないため熱間塑性加工により熱電材料はスムーズに塑性変形し、クラックも生じず、歩留まりの優れた熱電材料を得ることができ、また、前記熱電材料からなる熱電素子は、高性能化がはかれるため、センサー素子や光素子、ＬＳＩ基板などの半導体回路、宇宙ステーションで使用される電子機器の冷却、レーザーダイオード等の精密温度制御、熱電発電等の分野に広く適用できるものである。   As described above, according to the method of manufacturing a thermoelectric material according to the present invention, since the thermoelectric material does not have huge crystal grains, the thermoelectric material is smoothly plastically deformed by hot plastic processing, and cracks are not generated, and the yield is excellent. In addition, since thermoelectric elements made of the thermoelectric material are improved in performance, it is necessary to cool sensor elements, optical elements, semiconductor circuits such as LSI substrates, and electronic equipment used in space stations. It can be widely applied to the fields of precision temperature control such as laser diodes, thermoelectric power generation and the like.

（ａ）本発明の実施の形態１における一軸加圧工程前の状態を示す概略図（ｂ）同一軸加圧工程後の状態を示す概略図(A) Schematic which shows the state before the uniaxial pressurization process in Embodiment 1 of this invention (b) The schematic which shows the state after a uniaxial pressurization process 同実施の形態における圧延工程を示す概略図Schematic showing the rolling process in the same embodiment 同実施の形態における熱間押出加工の工程を示す概略図Schematic showing the process of hot extrusion in the same embodiment 従来の熱間押出加工の工程を示す概略図Schematic showing the conventional hot extrusion process

符号の説明Explanation of symbols

１ ダイス
２ パンチ
３ 熱電材料の粉末
４ 圧粉体
５ ロール
６ 圧延材
７ ダイス
８ パンチ
９ ヒーター
１０ 加圧装置
１１ 押出成型品 DESCRIPTION OF SYMBOLS 1 Dice 2 Punch 3 Thermoelectric material powder 4 Compact 5 Roll 6 Rolled material 7 Die 8 Punch 9 Heater 10 Pressurizer 11 Extrusion product

Claims (5)

ビスマスおよびアンチモンからなる群から選択された少なくとも一種の元素と、テルルおよびセレンからなる群から選択された少なくとも一種の元素とを含有した熱電材料の製造方法であって、前記熱電材料を圧延法により圧延体を形成し、前記圧延体を圧延方向と平行な方向に熱間塑性変形を行い、形成することを特徴とする熱電材料の製造方法。   A method for producing a thermoelectric material comprising at least one element selected from the group consisting of bismuth and antimony and at least one element selected from the group consisting of tellurium and selenium, wherein the thermoelectric material is obtained by rolling. A method for producing a thermoelectric material, comprising forming a rolled body, and forming the rolled body by hot plastic deformation in a direction parallel to a rolling direction. 前記熱電材料が粉末圧粉体であることを特徴とする請求項１記載の熱電材料の製造方法。   The method of manufacturing a thermoelectric material according to claim 1, wherein the thermoelectric material is a powder compact. 前記粉末圧粉体を一軸加圧法で作製し、加圧法方向と直角の方向に圧延することを特徴とする請求項２記載の熱電材料の製造方法。   The method for producing a thermoelectric material according to claim 2, wherein the powder compact is produced by a uniaxial pressing method and rolled in a direction perpendicular to the pressing method direction. 前記熱間塑性変形が熱間押出加工であることを特徴とする請求項１から３のいずれか一項に記載の熱電材料の製造方法。   The method for producing a thermoelectric material according to any one of claims 1 to 3, wherein the hot plastic deformation is hot extrusion. ビスマスおよびアンチモンからなる群から選択された少なくとも一種の元素と、テルルおよびセレンからなる群から選択された少なくとも一種の元素とを含有した熱電材料を、圧延法により圧延体とし、前記圧延体を圧延方向と平行な方向に熱間塑性変形を行い作製され、Ｃ面と平行な方向に電流が流れるように作製した熱電素子。   A thermoelectric material containing at least one element selected from the group consisting of bismuth and antimony and at least one element selected from the group consisting of tellurium and selenium is made into a rolled body by a rolling method, and the rolled body is rolled A thermoelectric element manufactured by performing hot plastic deformation in a direction parallel to the direction so that a current flows in a direction parallel to the C-plane.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006303427A (en) * 2005-03-23 2006-11-02 Shimane Univ Manufacturing method of thermoelectric semiconductor material

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006303427A (en) * 2005-03-23 2006-11-02 Shimane Univ Manufacturing method of thermoelectric semiconductor material

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