JP4000023B2 - Thermoelectric material molded body and method for producing thermoelectric material molded body - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermoelectric material molded body and a method for producing a thermoelectric material molded body.
[0002]
[Prior art]
Conventionally, various materials such as metal-based, semiconductor-based, and oxide-based materials are known as thermoelectric materials. When a temperature difference is given to this type of thermoelectric material, heat can be converted into electricity by the Seebeck effect (thermoelectric power generation), and when a current is passed through the thermoelectric material, heat transfer is generated by the Peltier effect and cooling is performed. Can be performed (thermoelectric cooling).
[0003]
The thermoelectric material as described above is usually used after being processed into a small molded body (hereinafter, this molded body is referred to as a thermoelectric material molded body). For example, a large number of thermoelectric material molded bodies are arranged vertically and horizontally, and they are used. By connecting the thermoelectric material molded bodies in series, a planar thermoelectric conversion element (thermoelectric conversion module) is configured and used.
[0004]
More specifically, for example, a molded body of P-type semiconductor material that is a thermoelectric material and a molded body of N-type semiconductor material that is a thermoelectric material are arranged vertically and horizontally, and the molded body of P-type semiconductor material and N A planar thermoelectric conversion element can be configured by alternately connecting the molded semiconductor material molded bodies in series. In this case, the P-type semiconductor and the N-type semiconductor are connected via electrodes, but an electrode through which current flows from the P-type semiconductor side to the N-type semiconductor side when energized, and from the N-type semiconductor side when energized By disposing the electrode on which the current flows to the P-type semiconductor side separately on the front and back of the planar thermoelectric conversion element, the heat transfer in both the P-type semiconductor material molded body and the N-type semiconductor material molded body The directions are aligned, and either one of the front and back surfaces of the planar thermoelectric conversion element is cooled while the other is heated.
[0005]
[Problems to be solved by the invention]
By the way, as a method of processing the thermoelectric material as described above into a small molded body, conventionally, a raw material composition having the same composition as the desired thermoelectric material is heated to be melted or sintered, and then mechanical processing (cut processing) is performed. ), A rectangular parallelepiped shaped body was cut out.
[0006]
However, since many thermoelectric materials are brittle, the yield at the time of cutting out the molded body is low, which has been a factor that cannot reduce the unit price of the thermoelectric conversion element. In addition, if the thermoelectric material is brittle, it is difficult to carry out fine precision processing. Therefore, it is not easy to downsize the thermoelectric material molded body, and there is a problem that the mounting density of the thermoelectric material molded body cannot be improved.
[0007]
The present invention has been made to solve the above-mentioned problems, and its object is to provide a thermoelectric material molded body having a structure that has a higher processing yield and can be easily miniaturized than conventional products, and a method for manufacturing the same. There is to do.
[0008]
[Means for Solving the Problems and Effects of the Invention]
The features of the present invention made to achieve the above object will be described in detail below.
The thermoelectric material molded body according to claim 1 is a spherical thermoelectric material molded body having a structure in which a thermoelectric material is coated on an outer surface of a core made of an insulating material.
[0009]
The thermoelectric material molded body according to claim 2 ,
The outer diameter is 0.05 mm to 30 mm, and the coating thickness of the thermoelectric material is 1 μm to 50 μm.
[0010]
The thermoelectric material molded body according to claim 3 ,
The thermoelectric material is Bi-Te, Mg-Si, Mn-Si, Fe-Si, Si-Ge, Pb-Te, Fe-V-Al, chalcogenite, skutterudite, One type of material selected from filled skutterudite type and boron carbide type, or a material obtained by kneading two or more types is characterized.
[0011]
The thermoelectric material molded body according to claim 3 ,
The insulating material is any one of ZrO ₂ , Al ₂ O ₃ , Si ₃ N ₄ , SiO ₂ , mullite, steatite, or cordierite.
[0012]
The thermoelectric material molded body according to claim 4 ,
The insulating material and the thermoelectric material are a combination satisfying a relationship of α1 ≦ α2 with respect to a linear expansion coefficient α1 of the insulating material and a linear expansion coefficient α2 of the thermoelectric material.
[0013]
The method for producing a thermoelectric material molded body according to claim 5 comprises:
A method for producing a spherical thermoelectric material molded body having a structure in which a thermoelectric material is coated on an outer surface of a core made of an insulating material,
The powder composition is pulverized by stirring the ball made of the insulating material and the powder composition having the same composition as the thermoelectric material in a container, and pulverizing and kneading the powder composition with the ball. The thermoelectric material kneaded is coated on the outer surface of the ball serving as the core.
[0014]
According to the thermoelectric material molded body described in each of claims 1 to 4 , since it is a spherical thermoelectric material molded body and has a structure in which the outer surface of the core is coated with the thermoelectric material, it is manufactured. At this time, it is not necessary to produce a large thermoelectric material lump and cut out a small molded body from the lump, and it is only necessary to coat the outer surface of the core with a composition to be a coating layer of the thermoelectric material. Therefore, it is easier to increase the yield than the thermoelectric material molded body manufactured by the cutting process, the manufacturing cost can be reduced, and the unit price when configured as a thermoelectric conversion element can be reduced. In addition, by simply adjusting the core size and coating thickness, it is possible to obtain a minute thermoelectric material molded body that could not be manufactured by cutting, so the mounting density of the thermoelectric material molded body can be improved. Furthermore, some thermoelectric materials contain rare and expensive components, but even in that case, the core can be formed of an inexpensive material, so it is necessary to produce a compact of the same size. If it exists, raw material cost will be reduced and it will become cheap rather than manufacturing thermoelectric material alone.
[0015]
Moreover, by the thermoelectric material compact was spherical, individual thermoelectric material molded body, since hardly chipped than rectangular shape cut-out molded body, its handling is facilitated.
In addition, when the outer diameter is 0.05 mm to 30 mm and the coating thickness of the thermoelectric material is 1 μm to 50 mm, the handling when arranging using an automatic machine is easier than the one with an excessively small or large outer diameter. In addition to the excessively thin coating thickness, a significant thermoelectric conversion performance can be obtained as a thermoelectric material, and the raw material cost can be suppressed as compared with an excessively thick coating thickness. When the coating thickness is 1 μm or more, significant thermoelectric conversion performance as a thermoelectric material can be obtained. However, when the thickness is 10 μm or more, the thermoelectric conversion performance is stable, and it is more preferably about 20 μm. Of course, from the viewpoint of thermoelectric conversion performance, the coating thickness can be any thickness, but it is not necessary to make it excessively thick in consideration of raw material costs and the like.
[0016]
Thermoelectric materials are Bi-Te, Mg-Si, Mn-Si, Fe-Si, Si-Ge, Pb-Te, Fe-V-Al, chalcogenite, and skutterudite. It is desirable that the material is a kind of material selected from filled skutterudite and boron carbide, or a material obtained by kneading two or more, since the thermoelectric conversion performance can be relatively high.
[0017]
Further, it is desirable that the insulating material is any of ZrO ₂ , Al ₂ O ₃ , Si ₃ N ₄ , SiO ₂ , mullite, steatite, or cordierite.
Further, when the insulating material and the thermoelectric material are in a combination satisfying the relationship of α1 ≦ α2 with respect to the linear expansion coefficient α1 of the insulating material and the linear expansion coefficient α2 of the thermoelectric material, each material expands with heating. However, the core does not expand too much and the coating layer does not crack.
[0018]
Furthermore, according to the method for manufacturing a thermoelectric material molded body according to claim 6, the thermoelectric material molded body according to each of claims 1 to 4 can be manufactured.
[0019]
In particular, according to the method for producing a thermoelectric material molded body according to claim 5 , a ball made of an insulating material and a powder composition having the same composition as the thermoelectric material are stirred in a container, and the powder composition is made with the ball. By grinding and kneading the product, a thermoelectric material obtained by grinding and kneading the powder composition is coated on the outer surface of the core ball. If it is such a manufacturing method, the desired thermoelectric material molded object can be manufactured with the apparatus structure similar to the mechanical alloying method used for manufacture of various alloys.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described with an example.
(1) Production Example 1 of Thermoelectric Material Molded Body
By mixing a powder of Bi powder and Te powder and Sb, intended thermoelectric materials [compositional _{ratio: (Bi 2 Te 3) 0} . ₂₅ (Sb ₂ Te ₃ ) ₀ . ₇₅ ] was prepared.
[0021]
10 g of this powder composition and a ZrO ₂ ball (ball size: φ10 mm / 300 g, φ3 mm / 150 g, φ0.5 mm / 5 g), which is an insulating material, are placed in a container of a ball mill apparatus and stirred for 10 hours. The powder composition was pulverized and kneaded with a ball.
[0022]
As a result, grinding the powder composition, thermoelectric material by kneading ing is, spherical particles of φ0.5mm of coated on the outer surface of the ball comprising a core structure was obtained. When the cross section of this spherical particle was observed with a scanning electron microscope, as shown in FIG. 1, the spherical particle 1 has a structure in which a coating layer 1b of a thermoelectric material is formed on the outer surface of a core 1a made of an insulating material. The coating thickness was about 2 μm.
[0023]
Thermoelectric materials that form a coating layer has a characteristic of a P-type semiconductor.
[0024]
10 g of this powder composition and a ZrO ₂ ball (ball size: φ10 mm / 300 g, φ3 mm / 150 g, φ0.5 mm / 5 g), which is an insulating material, are placed in a container of a ball mill apparatus and stirred for 10 hours. The powder composition was pulverized and kneaded with a ball.
[0025]
As a result, spherical particles with a diameter of 0.5 mm were obtained in which a Bi-Te thermoelectric material obtained by pulverizing and kneading the powder composition was coated on the outer surface of the core ball. When the cross section of the spherical particles was observed with a scanning electron microscope, the coating thickness was about 2 μm.
[0026]
The Bi-Te thermoelectric material forming the coating layer has characteristics as an N-type semiconductor.
(3) Performance Experiment of Thermoelectric Conversion Element As shown in FIG. 2, spherical particles 1 (= thermoelectric material molded body which is a P-type semiconductor) produced in Production Example 1 and spherical particles 7 produced in Production Example 2 above. The thermoelectric conversion element 10 was configured by connecting (= thermoelectric material molded body which is an N-type semiconductor) in series via a conductive portion 9 made of indium.
[0027]
One end of the thermoelectric conversion element 10 was heated to 80 ° C., and the other end was air-cooled, and the electromotive force of the thermoelectric conversion element 10 was measured. The temperature on the air cooling side at this time was 50 ° C., and the electromotive force was 10 mV as a result of measurement.
As mentioned above, although embodiment of this invention was described, this invention is not limited to said specific one Embodiment, In addition, it can implement with a various form.
[0028]
For example, in the above embodiment, an example in which a thermoelectric material molded body is configured with a specific thermoelectric material has been shown. However, a thermoelectric material molded body can also be configured using other thermoelectric materials. Mg-Si, Mn-Si, Fe-Si, Si-Ge, Pb-Te, Fe-V-Al, chalcogenite, skutterudite, filled skutterudite, boron carbide A thermoelectric material molded body can be formed using a thermoelectric material such as a system in the same manner.
[0029]
These thermoelectric materials may be used alone or in combination of two or more. When two or more types are used, a coating layer made of a thermoelectric material formed by kneading two or more types may be formed by simultaneously grinding and kneading the two or more types of thermoelectric materials with a ball. The above thermoelectric materials may be sequentially pulverized and kneaded with balls to sequentially laminate the coating layers made of the thermoelectric materials.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a thermoelectric material molded body.
FIG. 2 is a schematic configuration diagram of a thermoelectric conversion element.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Spherical particle (thermoelectric material molded object), 1a ... Core (insulating material, ball), 1b ... Coating layer (thermoelectric material), 2 ... Spherical particle (thermoelectric material molded object), 3 ... Conductive part.

Claims (5)

A spherical thermoelectric material molded body,
A thermoelectric material molded body having a structure in which a thermoelectric material is coated on an outer surface of a core made of an insulating material.   2. The thermoelectric material molded body according to claim 1, wherein an outer diameter is 0.05 mm to 30 mm, and a coating thickness of the thermoelectric material is 1 μm to 50 μm.   The insulating material is ZrO. ₂ Series, Al ₂ O _Three System, Si _Three N _Four System, SiO ₂ 3. The thermoelectric material molded body according to claim 1, wherein the thermoelectric material molded body is one of a mullite system, a mullite system, a steatite system, and a cordierite system.   The insulating material and the thermoelectric material are a combination satisfying a relationship of α1 ≦ α2 with respect to a linear expansion coefficient α1 of the insulating material and a linear expansion coefficient α2 of the thermoelectric material. The thermoelectric material molded body according to claim 3.   A method for producing a spherical thermoelectric material molded body having a structure in which a thermoelectric material is coated on an outer surface of a core made of an insulating material,
  The powder composition is pulverized by stirring the ball made of the insulating material and the powder composition having the same composition as the thermoelectric material in a container, and pulverizing and kneading the powder composition with the ball. The thermoelectric material formed by kneading is coated on the outer surface of the ball serving as the core.

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