JPH06204572A - Manufacture of thermal generator element - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing a thermal generator element by which a thermal generator element having an excellent junction strength can be made regardless what material a p-type and an n-type semiconductors are made of. CONSTITUTION:CuO child particles 15 are attached around a mother particle 13 which is formed of material powder of a p-type semiconductor, to form a p-type capsule particle 16. On the other hand, CuO child particles 15 are attached around a mother particle 14 which is made of material powder 12 of an n-type semiconductor. The p-type capsule particles 16 and the n-type capsule particles 17 are separately put into one and the same molding die and then are baked.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a thermoelectric generator used for a thermocouple or the like.

[0002]

2. Description of the Related Art As is well known, a thermoelectric power generation element is an element that converts thermal energy into electrical energy by utilizing the thermoelectric effect or vice versa. Typical examples are thermocouples and electronic refrigeration elements (Peltier elements). Element) and the like. This thermocouple uses the Seebeck effect in which two types of metal wires are connected to form a closed circuit, and when two contacts are kept at different temperatures, a thermoelectromotive force is generated between these contacts. It measures and measures the temperature. On the other hand, the electronic refrigeration element generates heat other than Joule heat at the contact surface when a current flows through the contact surface between different kinds of conductors or semiconductors.
It utilizes the Peltier effect in which absorption occurs, and is often used when precise temperature control is required in the range of -20 ° C to + 70 ° C.

This thermoelectric generator is formed of a p-type semiconductor and an n-type semiconductor made of a thermoelectric material. Specifically, as shown in FIG. 5A, the p-type semiconductor 1 and the n-type semiconductor 2 are sinter-molded in a predetermined molding die, and these are directly joined to each other to form the pn junction 3 The direct-junction type thermoelectric generator 4 having the above was formed.

Further, as shown in FIG. 5 (b), the p-type semiconductor 1 and the n-type semiconductor 2 are separately sintered and formed, and these are indirectly joined by a conductive metal plate 5 to form an indirect joint type. Was formed. The metal plate 5 is provided with a thermal strain relaxation portion 5a, and the metal plate 5 and the semiconductors 1 and 2 are formed.
And were joined by brazing 7.

[0005]

By the way, the conventional techniques have the following problems. That is, the p-type semiconductor 1 and the n-type semiconductor 2 that can be used for the direct-junction type thermoelectric generator 4 are limited to materials having the same structure such as SiGe and FeSi ₂ and having a small difference in thermal expansion coefficient. There was a problem that

The material for the p-type semiconductor 1 and the n-type semiconductor 2 is not selected for the indirect junction type thermoelectric generator 6, but there is a problem in that the heat resistance of the metal plate 5 and its joint strength are poor. It was

In view of the above problems, an object of the present invention is to provide a method for manufacturing a thermoelectric power generation element, which can obtain a thermoelectric power generation element excellent in bonding strength, regardless of the materials forming the p-type semiconductor and the n-type semiconductor. To do.

[0008]

[Means for Solving the Problems] In order to achieve the above object,
In the method for manufacturing a thermoelectric generator according to the present invention, CuO child particles are attached to the periphery of mother particles made of p-type semiconductor raw material powder to form p-type capsule particles, and at the same time, made of n-type semiconductor raw material powder. CuO child particles are attached to the periphery of the mother particles to form n-type capsule particles, and the p-type capsule particles and the n-type capsule particles are separately charged into one molding die and then sintered and molded. The p-type semiconductor and the n-type semiconductor are directly joined to each other.

[0009]

According to the above construction, the p-type capsule particles are formed by adhering CuO child particles around the mother particles made of the p-type semiconductor raw material powder. On the other hand, the n-type capsule particles have C particles around the mother particles made of the n-type semiconductor raw material powder.
It is formed by attaching child particles of uO.

Therefore, when the p-type capsule particles and the n-type capsule particles are separately charged into one molding die and then sintered and molded, the p-type semiconductor and the n-type semiconductor are directly bonded. However, in reality, CuO intervenes in the pn junction and CuOs are joined together.

The reason why CuO is used as the child particles of the capsule particles is that the CuO has excellent slipperiness and electrical conductivity. That is, when CuO is used as the child particles, CuO uniformly dispersed in the grain boundaries of the mother particles improves the slidability during sintering and improves the sintering density,
This shows excellent bonding strength.

Further, due to the conductivity of CuO, for example, when a plasma sintering method is used as a sintering method, CuO uniformly dispersed in the grain boundaries of the mother particles prevents local conduction.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a method for manufacturing a thermoelectric generator according to the present invention will be described in detail below with reference to the accompanying drawings.

As shown in FIG. 1, first, a small amount of Mn is added to Fe and Si powders, and this is put in a crucible and melted by high frequency heating to produce a p-type alloy solution and a small amount of Co. An n-type alloy solution added and melted was produced. At this time, the amount of Si mixed is about 50 with respect to Fe.
About wt% is preferable. The melting temperature is 1300 ° C to 1
It shall be in the range of 600 ° C.

Next, the p-type alloy solution and the n-type alloy solution are respectively used as a raw material powder for p-type semiconductor and a raw material powder for n-type semiconductor of α-FeSi ₂ by using a gas atomizing apparatus as shown in FIG. . The particle size of these powders is, for example, about 1 to 10 μm.

As shown in FIG. 3, the p-type semiconductor raw material powder 11 and the n-type semiconductor raw material powder 12 are used as mother particles 13 and 14, and C around the mother particles 13 and 14.
The child particles 15 made of uO are encapsulated by a well-known technique such as an electrostatic adhesion method or a mechanical impact method to form p-type capsule particles 16 and n-type capsule particles 17. The mixing ratio of CuO in these capsule particles 16 and 17 is 3 wt.
%. In addition, the particle size of the child particles 15 is
For example, it is desirable to set the particle size of 4 to as small as about 1/10 to 1/20.

Next, the p-type capsule particles 16 and the n-type capsule particles 17 were separately charged into one mold of the plasma sintering apparatus. That is, this molding die is formed, for example, in a U shape, and the mold is divided and charged so that the p-type capsule particles 16 and the n-type capsule particles 17 are in contact with each other at the bent portion.

After this charging, the above-mentioned plasma sintering apparatus was used to sinter at about 650 ° C. in a vacuum atmosphere to obtain α-FeSi.
₂ metal phase to beta-FeSi ₂ semiconductor phases were phase transition. Explaining this phase transition, the α phase is a tetragonal metal, while the β phase is an orthorhombic intrinsic semiconductor. β-FeSi ₂ is formed by the encapsulation reaction between α-FeSi ₂ and FeSi _2, and this process is usually called a phase transition.

Thus, the thermoelectric generator in which the p-type semiconductor and the n-type semiconductor are directly joined is manufactured.

Next, the operation of the above embodiment will be described.

According to the method of manufacturing the thermoelectric generator of this embodiment, the p-type capsule particles 16 have CuO child particles 15 around the mother particles 13 made of the p-type semiconductor raw material powder 11.
Are formed by adhering. On the other hand, the n-type capsule particles 17 are formed by adhering CuO child particles 15 around the mother particles 14 made of the n-type semiconductor raw material powder 12. These capsule particles 16 and 17 are separately charged into a single U-shaped mold so that they come into contact with each other at their bent portions, and then sintered and molded by a plasma sintering device.

When sintered and formed in this manner, a p-type semiconductor and an n-type semiconductor that have undergone a phase transition to the β-FeSi ₂ semiconductor phase as described above are formed, and these semiconductors are directly bonded to each other to form a thermoelectric generator. Will be formed.

Actually, however, as shown in FIG. 4, CuO as the child particles 15 is present in the pn junction 18a of the thermoelectric generator 18, and the CuOs are joined together. It has become.

As in this embodiment, the capsule particles 16,
The reason why CuO is used as the child particles 15 of No. 17 is that the slidability and electric conductivity during plasma sintering are taken into consideration. That is,
CuO is easy to obtain a fine powder. On the other hand, Cu
Is easily oxidized when made into fine powder, and it is difficult to obtain fine powder as Cu itself. As described above, since CuO is a fine powder, it is expected to be uniformly dispersed in the powder grain boundaries to improve the slidability at the time of sintering and the sintering density, whereby excellent bonding strength can be obtained. Is. In addition, the electric conductivity in the plasma sintering method also shows that CuO dispersed uniformly in the powder grain boundaries.
Because of this, local energization is hard to occur. Furthermore, from the experiment, CuO
It is known that the α-FeSi ₂ encapsulated in (3) easily undergoes a phase transition to β-FeSi ₂ .

Further, although leading to large amounts performance degradation of the FeSi ₂ The addition of CuO into FeSi _2, as shown in Table 1, if the range of a few wt% case of no addition and its physical properties are similar Therefore, there is no problem in the performance of the thermoelectric generator 18.

[0026]

[Table 1]

As described above, the thermoelectric generator 18 manufactured according to the present embodiment exhibits excellent thermoelectric characteristics, but pn
Since the joining portion 18a has excellent mechanical characteristics, it is suitable for use particularly in a place where there is a lot of vibration such as an automobile, and can have a longer life.

[0028]

As described above, according to the method of manufacturing a thermoelectric power generation element of the present invention, a thermoelectric power generation element having excellent bonding strength can be obtained regardless of the materials forming the p-type semiconductor and the n-type semiconductor. It has the excellent effect of being able to.

[Brief description of drawings]

FIG. 1 is a process chart showing a manufacturing process of raw material powders of a p-type semiconductor and an n-type semiconductor in an embodiment of a method for manufacturing a thermoelectric generator according to the present invention.

FIG. 2 is a cross-sectional view showing an example of a gas atomizing apparatus used in this embodiment.

FIG. 3 is a schematic view showing p-type capsule particles and n-type capsule particles in this example.

FIG. 4 shows a pn of the thermoelectric generator manufactured by this example.
It is a schematic diagram showing a joined state.

FIG. 5 is a schematic view showing a conventional thermoelectric generator.

[Explanation of Codes] 11 p-type semiconductor raw material powder 12 n-type semiconductor raw material powder 13,14 mother particle 15 child particle 16 p-type capsule particle 17 n-type capsule particle 18 thermoelectric power generation element

Front page continuation (72) Inventor Shigeo Takita 8 Tsutana, Fujisawa City Kanagawa Prefecture, Isuzu Central Research Institute Co., Ltd. (72) Inventor Eiji Okumura 8th, Tsunatan Fujisawa City Kanagawa Prefecture, Isuzu Central Research Center Co., Ltd. (72 ) Inventor Hiroshi Matsumi 8 Tsutana, Fujisawa City, Kanagawa Prefecture Isuzu Central Research Institute

Claims (1)

[Claims] 1. A p-type capsule particle is formed by adhering CuO child particles around mother particles made of p-type semiconductor raw material powder, and CuO particles are made around the mother particles made of n-type semiconductor raw material powder. Sub-particles are attached to form n-type capsule particles, and the p-type capsule particles and the n-type capsule particles are separately charged into one molding die, and then sintered and molded to form a p-type semiconductor and an n-type capsule particle. A method for manufacturing a thermoelectric generator, characterized in that it is directly joined to a semiconductor.