JPH0697512A - Thermoelectric conversion element - Google Patents

Abstract

PURPOSE:To improve power generating capability (conversion efficiency) and productivity of a thermoelectric conversion element consisting of the structure where the PN junction is formed by a P-type semiconductor mainly composed of iron silicide (FeSi2) and an N-type semiconductor. CONSTITUTION:In view of joining a P-type semiconductor 11 mainly consisting of iron silicide (FeSi2) and an N-type semiconductor 12 through formation of the PN junction via a highly thermoconductive metal plate 13, the semiconductors 11, 12 and the highly thermoconductive metal plate 13 are integrated by the brazing by the brazing material 14, 14 of a titanium (Ti) system active metal to form a thermoelectric conversion element 10. Thereby, since the brazing can be done via the highly thermoconductive metal plate 13, the semiconductors 11, 12 can be easily and individually manufactured and moreover thermal energy from the heat source can be transmitted with high effectiveness to the PN junction area through the highly thermoconductive metal plate 13. Accordingly, thermoelectric conversion efficiency can be improved remarkably.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention relates to iron sulfide (FeSi
₂ ) Regarding improvement of a thermoelectric conversion element composed of a P-type semiconductor and an N-type semiconductor mainly composed of ₂ ), a PN junction is made into a titanium (Ti) -based active metal brazing material with a high thermal conductive metal plate interposed. The present invention relates to a thermoelectric conversion element which is formed by brazing to improve the power generation capacity (conversion efficiency) and facilitates manufacturing.

[0002]

2. Description of the Related Art A thermoelectric conversion element is a device which is highly demanded in recent industry and is expected to be put into practical use from the viewpoint of effective utilization of thermal energy. For example, exhaust heat is used to convert it into electric energy. A very wide range of applications are being investigated, such as systems, small portable power generators for easily obtaining electricity outdoors, and flame sensors for gas appliances. But,
The thermoelectric conversion elements that have been known so far are generally high in the price of semiconductors that make up the thermoelectric conversion element, but the operating temperature range is low, and the conversion efficiency is low and the manufacturing method is complicated. Has not been widely used since.

As a thermoelectric conversion element for solving these problems, there has been proposed a thermoelectric conversion element having a structure in which a P-type semiconductor mainly composed of iron silicide (FeSi ₂ ) and an N-type semiconductor are PN-junctioned, Attention is paid to the fact that the semiconductor is made of a relatively inexpensive material and has a high heat resistance of about 900 ° C.

In this thermoelectric conversion element, as shown in FIG. 9, usually, a P-type semiconductor 2 and an N-type semiconductor 3 in which an appropriate impurity such as manganese (Mn) or cobalt (Co) is added to iron silicide (FeSi ₂ ). U formed by PN joining at one end
It consists of a letter shape. In the thermoelectric conversion element 1 having such a configuration, when the PN junction 4 is heated, the P
Heat energy is supplied to the N-junction 4 and positive (+) and negative (-) voltages are generated on the open end side (low temperature end side) of each of the semiconductors 2 and 3 by the Seebeck effect, and electric power is generated from the open end. You can take it out.

Further, it is known that the thermoelectric conversion element 1 having this U-shaped shape is manufactured by the steps described below. That is, 1) An alloy for P-type semiconductor and an alloy for N-type semiconductor having a predetermined composition of Fe _1-X Mn _X Si ₂ and Fe _1-Y Co _Y Si ₂ are obtained by melt casting. 2) Each of the above semiconductor alloys is crushed to a predetermined particle size (about 1.5 μm) by a crusher such as a stamp mill or a ball mill. 3) A predetermined amount of binder (PVA) is kneaded and granulated. 4) Each of the above semiconductor alloy powders is filled in a die having a U-shaped through hole. However, when the alloy powder is filled, the lower punch is arranged in advance in the die, and the partition plate is arranged at the position to be the PN junction.
After filling a predetermined amount of each alloy powder for semiconductors, the partition plate is removed so that the alloy powders for semiconductors contact each other at the PN junction. 5) Pressure compression molding is performed with the upper punch and the lower punch arranged in the die to obtain a molded body having a U-shape. 6) The molded body is debindered in the atmosphere and then sintered at a predetermined temperature in vacuum (for example, 1150).
° C x 3 hours). 7) The sintered body is subjected to semiconductor heat treatment at a predetermined temperature in the atmosphere (for example, 750 ° C. × 50 to 200 hours).

[0006]

A U-shape in which a P-type semiconductor 2 and an N-type semiconductor 3 mainly composed of iron silicate (FeSi ₂ ) obtained by the above-described manufacturing method are joined to form a PN junction. The type thermoelectric conversion element 1 is superior to other conventionally known thermoelectric conversion elements in terms of price, heat resistance, etc. However, on the other hand, the following problems are caused by the PN junction configuration, the manufacturing method, and the like. Have a point. In the structure shown in FIG. 9, when the PN junction portion 4 is heated, heat energy is supplied to the PN junction portion 4 to generate an electron-hole pair which is a source of a current. At the same time, when the electron-hole pair is generated, Due to the so-called Peltier effect that robs thermal energy, the temperature of the PN junction 4 is lowered, and as a result, the frequency of generation of electron-hole pairs is reduced, and the semiconductors 2 and 3 can be taken out from the open end side (low temperature end side). Electric power is reduced, and the required power generation capacity (conversion efficiency) has not been realized.

In the manufacturing method described above, U
In order to obtain a shaped body of the V-shaped thermoelectric conversion element, it is necessary to simultaneously fill two dies, which are an alloy powder for P-type semiconductor and an alloy powder for N-type semiconductor, in one die without mixing them. Therefore, the filling work becomes very complicated. Further, since the two types of powders are integrated by pressure compression molding and sintering, the shape of the molded body is necessarily limited, and it may be a factor that hinders the expansion of applications of this thermoelectric conversion element. Has become.

Furthermore, even if great care is taken during the above-mentioned filling work, it is difficult to completely prevent the mixing of the powders at the joint portions of the alloy powders for semiconductors,
A good PN junction cannot be obtained depending on the junction state, which is a factor causing electrical characteristic deterioration and variation.

The present invention solves the above problems and provides a thermoelectric conversion element having a structure in which a P-type semiconductor mainly composed of iron silicide (FeSi ₂ ) and an N-type semiconductor are PN-junctioned. The purpose of the present invention is to provide a structure capable of improving the conversion efficiency) and an easy manufacturing method, and to greatly expand the application range of the thermoelectric conversion element.

[0010]

According to the present invention, as a result of repeating various investigations in order to achieve the above-mentioned object, a P-type semiconductor and an N-type semiconductor mainly containing iron silicide (FeSi ₂ ) are prepared in advance. After making them separately, we found that the objective can be achieved by brazing and integrating each of these semiconductors with a highly heat conductive metal plate such as a copper (Cu) plate with a titanium (Ti) based active metal brazing material, and propose To do.

That is, in order to facilitate manufacture, the present inventor can completely prevent the alloy powder for semiconductors from being mixed in the PN junction portion, and can arbitrarily select the shape of each semiconductor, the P type It was determined that it was essential to create the semiconductor and the N-type semiconductor separately. In order to efficiently supply the thermal energy to the PN junction in order to prevent the reduction of the generation of electron-hole pairs due to the Peltier effect, the inventor of the present application uses the PN junction in the conventional configuration in which the PN junction is directly heated. There is a limit in terms of the shape of the parts, etc., and high heat conductive metal plates such as copper (Cu) plates that can efficiently conduct the heat energy from the heat source to the PN junction are arranged at the semiconductor junctions. Was confirmed to be effective.

Further, various studies have been made on means for joining and integrating the separately prepared semiconductor and the high thermal conductive metal plate, and it has been found that the conventionally known solder has a low melting point even though the joining and integration are possible. Is difficult to use at high temperature, and iron sulfide (FeSi ₂ ) when used at low temperature
The characteristics originally possessed by the semiconductor mainly composed of were not fully expressed, and the target output power could not be obtained.

Since the silver (Ag) brazing material which has been widely used as a brazing material has a poor bonding strength with the oxide film (SiO ₂ ) formed on the surface of each semiconductor, the bonding strength is low, especially in a high temperature atmosphere. If a brazing strength that does not withstand the use of the above is not obtained, and after brazing with silver (Ag) brazing after removing the oxide film (SiO ₂ ), silver (Ag) diffuses inside each semiconductor, It was confirmed that not only the electrical characteristics of the semiconductor are deteriorated, but also the mechanical characteristics are deteriorated (becomes brittle).

Therefore, the present applicant has previously proposed a three-layer composite foil brazing material having titanium (Ti) as a core material, which has been proposed as a brazing material for joining metal and ceramics (Japanese Patent Laid-Open No. 2-93095).
In addition to the above, so-called titanium containing titanium (Ti) as a main component (T
When these semiconductors and the high thermal conductive metal plate were joined and integrated by using the i) -based active metal brazing material, extremely good joining could be obtained without removing the oxide film (SiO ₂ ) on the semiconductor surface.

The present invention completed on the basis of various findings as described above is, in short, iron sulfide (FeSi).
₂ ) In a thermoelectric conversion element composed of a P-type semiconductor and an N-type semiconductor mainly composed of ₂ ), a high thermal conductive metal plate is interposed between the pair of semiconductors, and a titanium (Ti) -based active metal brazing material is used. The thermoelectric conversion element is characterized in that a PN junction is formed by brazing.

[0016]

FIG. 1 is a schematic explanatory view showing an embodiment of the thermoelectric conversion element of the present invention. That is, iron silicide (FeSi
_In order to form a PN junction between the P-type semiconductor 11 and the N-type semiconductor 12 mainly composed of ₂ ) through a high thermal conductive metal plate 13 such as copper (Cu), the semiconductors 11 and 12 and the high thermal conductivity are respectively formed. The thermoelectric conversion element 10 has a structure in which a metal plate 13 and a titanium (Ti) -based active metal brazing material 14, 14 are integrally brazed together. The surface of the high thermal conductive metal plate 13 is provided with an oxidation resistant coating 17 such as TiN for preventing oxidation due to heating. Reference numerals 15 and 15 denote copper (Cu) plates joined to the open ends of the semiconductors 11 and 12, respectively, which also serve as an electrode plate and a heat dissipation plate, and the temperature of the joints is lower than that of the PN junction. To obtain a thermoelectric conversion element 10 having a desired characteristic even if they are joined and integrated with a brazing material 16 having a low melting point such as zinc-tin (Zn-Sn) solder without using a titanium (Ti) -based active metal. You can

In the above structure, the high thermal conductive metal plate 13
Is brought close to a heat source (not shown), the heat energy from the heat source is passed through the high thermal conductive metal plate 13 to form an iron sulfide (FeSi).
₂ ) is conducted and supplied to the P-type semiconductor 11 and the N-type semiconductor 12 which are mainly composed of ₂ ), and as described above, due to the Seebeck effect, the open ends (low temperature ends) of the respective semiconductors 11 and 12
Positive (+) and negative (-) voltages are generated in the electric field, and electric power can be taken out from the open end.

In this structure, each semiconductor 11,
A high thermal conductive metal plate 13 is disposed as a heat energy supply source at the joint of 12 and heat energy is constantly supplied efficiently from a heat source (not shown) located outside each of the semiconductors 11 and 12. It is possible to prevent a decrease in the generation of electron-hole pairs due to the effect, and it is possible to improve power generation efficiency. In addition, the P-type semiconductor 11 and the N-type semiconductor 1
Since 2 and 2 are manufactured separately and joined through the high thermal conductive metal plate 13, stable power can be taken out without mixing of the alloy powder for semiconductor in the PN junction.

Further, by connecting a heat dissipation plate made of a copper (Cu) plate to the open ends of the semiconductors 11 and 12, respectively, the temperature difference between the heating part (PN junction part) and the open ends of the semiconductors 11 and 12 is reduced. It will be possible to expand and further improve the power generation efficiency. Since the temperature sensing portions of the semiconductors 11 and 12 are substantially only the joint portion with the high thermal conductive metal plate 13, the total length (L) of the semiconductors 11 and 12 can be shortened. The electric resistance of 12 can also be reduced, which contributes to the improvement of power generation efficiency. Besides, the thermoelectric conversion element 10 of the present invention has various characteristics, and the specific characteristics thereof will be described in detail in combination with other embodiments described later.

Each member constituting the thermoelectric conversion element 10 of the present invention will be described in more detail below. Each of the semiconductors 11 and 12 constituting the thermoelectric conversion element 10 is separately filled in a die having a molding space (through hole) having a predetermined shape and press-compressed, and the conventional semiconductors described above are used. It can be obtained by a method substantially similar to the manufacturing method. That is, Fe _1-X Mn _X Si obtained by melt casting
_In a die having a molding space (through hole) having a predetermined shape after crushing and granulating a P-type semiconductor alloy and an N-type semiconductor alloy having a predetermined composition of ₂ and Fe _{1 -Y} Co _Y Si ₂ Then, the P-type semiconductor 11 and the N-type semiconductor 12 are obtained as independent individual products through the processes of pressure compression molding, binder removal processing, sintering, and heat treatment for semiconductorizing.

The high thermal conductive metal plate 13 disposed at the joint between the P-type semiconductor 11 and the N-type semiconductor 12 may be made of any material capable of efficiently conducting and supplying heat energy from a heat source to the semiconductor. ) Plate, copper (Cu) alloy plate, aluminum (Al) plate, aluminum (Al) alloy plate,
Nickel (Ni) plate, nickel (Ni) alloy plate, a clad material made of a combination thereof, or a material having an anti-oxidizing coating such as TiN on the surface of the material to prevent oxidation due to heating It is preferable to select from materials having good characteristics and having good compatibility with the titanium (Ti) -based active metal brazing material 14. A copper (Cu) plate or the like is preferable from the viewpoint of heat conduction, but a nickel (Ni) plate having excellent oxidation resistance is preferable when it is used as a single plate without an oxidation resistant coating. Further, it is preferable to select the shape and size of the high thermal conductive metal plate 13 in consideration of the mechanical strength thereof and the distance between the semiconductor and the heat source. For example, as heat sources, various heat sources such as exhaust heat of automobiles and boilers, internal combustion such as residual heat of stoves, energy of external combustion equipment, natural energy such as geothermal heat and solar heat can be assumed, but first, heat energy from heat source When using devices and jigs that efficiently collect heat, the heat energy from these devices and jigs can be efficiently conducted and supplied to the semiconductor, depending on the device or jig, or integrated with these. Since the material, shape, etc. of the high thermal conductive metal plate are appropriately selected to realize the high thermal conductive metal plate, the high thermal conductive metal plate can take various forms. Of course, even when the thermoelectric conversion element itself is configured to be adapted to a heat collecting device or the like, the high thermal conductive metal plate can take various forms.

Semiconductors 11 and 12 and a metal plate 1 having high thermal conductivity, respectively.
As the titanium (Ti) -based active metal brazing filler metal 14 that joins and integrates 3 and 3, titanium (Ti), which has been previously proposed by the applicant as a brazing filler metal for joining metal and ceramics, is used as a core material on both main surfaces thereof. Nickel (Ni) or nickel-copper (N
In addition to a three-layer composite foil brazing material (Japanese Patent Laid-Open No. 2-93095) obtained by pressure-bonding an i-Cu) alloy foil or the like, titanium (Ti) is used as a core material and both surfaces of the copper (Cu) foil are pressure-contacted. The so-called three-layer composite foil brazing material, such as a two-layer composite foil brazing material obtained by press-contacting titanium (Ti) with copper (Cu), nickel (Ni), nickel-copper (Ni-Cu) alloy foil, or the like. Composite foil brazing material, titanium (Ti) as the main component, cobalt (Co),
Liquid quenching alloy foil strip for brazing containing various additive elements other than nickel (Ni), iron (Fe), etc.
-116350), a liquid quenching alloy foil strip for brazing containing titanium (Ti) as a main component and various additive elements other than copper (Cu) (Japanese Patent Laid-Open No. 59-126739), and so-called liquid quenching. An alloy foil brazing material, an alloy powder mainly composed of titanium (Ti), or a mixed powder of titanium (Ti) powder and copper (Cu), nickel (Ni) powder, etc. is made into a paste using an organic binder. It is possible to use a titanium (Ti) -based active metal brazing material having various known forms such as the so-called pasty brazing material.

In any case, the titanium (Ti) -based active metal brazing material 14 makes the P-type semiconductor 11 and the N-type semiconductor 12 and the high thermal conductive metal plate 13 fit well, and is a joint that can be used at high temperatures. In order to obtain the strength, it is necessary to configure the brazing filler metal having the various forms described above so that the proportion of titanium (Ti) in the brazing filler metal when melted is 20 wt% or more. The upper limit is selected. As the constituent metals other than titanium (Ti), various metals as described above can be selected, but the inclusion of metals such as silver (Ag), which are feared to adversely affect various semiconductor characteristics, should be excluded as much as possible. Is preferred. Usually, under the above conditions, the ratio of titanium (Ti) in the brazing filler metal is 20w.
t% to 80 wt%, preferably 40 wt%
It is about 60 wt%.

It is desirable to select the form of these titanium (Ti) -based active metal brazing materials in consideration of workability to be arranged between the semiconductors 11 and 12 and the high thermal conductive metal plate 13. Further, since these titanium (Ti) -based active metal brazing materials have relatively high melting points, they can withstand use at high temperatures after completion of brazing, but on the other hand, brazing work temperature is also inevitable. Since the temperature is extremely high, it is necessary to consider the influence on the semiconductors 11 and 12 during the brazing work. That is, if each of the semiconductors 11 and 12 is heated above 900 ° C. after completion of the heat treatment for semiconducting, the original characteristics of the semiconductor are impaired and the desired power generation effect cannot be obtained.
When the high thermal conductive metal plate 13 is brazed to each of the semiconductors 11 and 12 that have once undergone the heat treatment for semiconductorizing, the brazing work temperature is preferably set to 900 ° C. or less.

On the other hand, the sintered bodies for the semiconductors 11 and 12 at the point of time when the so-called sintering process is completed before the semiconductor heat treatment is completed are not subject to the above restrictions.
High thermal conductive metal plate 13 at brazing work temperature exceeding ° C
Can be brazed, and the desired thermoelectric conversion element can be obtained by performing heat treatment for semiconductorizing after completion of these brazing operations. Therefore, it is necessary to determine whether to perform the brazing process before or after the semiconductor heat treatment, depending on the brazing temperature of the titanium (Ti) -based active metal brazing material to be used.

2 to 7 are schematic explanatory views showing another embodiment of the present invention. In the thermoelectric conversion element of the present invention, since the semiconductors forming the thermoelectric conversion element are individually and independently manufactured, it is possible to make them into various shapes. FIG. 1 shows a configuration in which each semiconductor is formed into a substantially prismatic shape and is joined through a high thermal conductive metal plate to form a substantially U-shaped thermoelectric conversion element. However, in FIGS. 1 shows a thermoelectric conversion element configured by arranging semiconductors made of a rectangular parallelepiped (substantially cubic).

FIG. 2 shows an iron silicide (FeSi) composed of a rectangular parallelepiped.
₂ ) mainly composed of a P-type semiconductor 21 and an N-type semiconductor 22 via a high thermal conductive metal plate 23 made of a copper (Cu) plate.
The thermoelectric conversion element 20 is configured by forming and joining the joints. Reference numerals 25 and 25 denote electrode plates made of a copper (Cu) plate which are joined to the low temperature end sides of the P-type semiconductor and the N-type semiconductor and also serve as a heat radiating plate. In order to facilitate electrical connection in the configuration in which a plurality of thermoelectric conversion elements 20 are connected as in the embodiments shown in FIGS. 3 and 4 described later, the electrode plates 25, 25 have open ends that open at predetermined angles. Are joined together. In this thermoelectric conversion element 20, the P-type semiconductor 21, the N-type semiconductor 22 and the high thermal conductive metal plate 23 are used.
The joining with the P-type semiconductor 21 and the N-type semiconductor 22 and the electrode plates 25, 25 are all integrated by brazing with a titanium (Ti) -based active metal brazing material 24. This is similar to the case of the thermoelectric conversion element 10 shown in FIG.

When the heat source covers a relatively wide range, a larger amount of electric power can be obtained by connecting a plurality of thermoelectric conversion elements 20 in series or in parallel. For example,
In the configuration shown in FIG. 3, the thermoelectric conversion elements 20a, 20b, 20c having the same configuration as the configuration shown in FIG. 2 are connected horizontally in a so-called side-by-side arrangement, and each has a high thermal conductivity close to or in contact with a heat source (not shown). Electric power corresponding to the total of thermal energy conducted and supplied from the metal plates 23a, 23b and 23c can be taken out from both ends of the electrode plates 25a and 25c. In the figure, reference numeral 26 is a connecting member such as a rivet that electrically connects the electrode plates 25a, 25b, 25c of the thermoelectric conversion elements 20a, 20b, 20c.

In the configuration shown in FIG. 4, thermoelectric conversion elements 20d, 20e, 20f having the same configuration as the configuration shown in FIG.
Are connected in a vertical direction in a so-called vertical direction, and each of the high thermal conductive metal plates 23d, 23 is close to or in contact with a heat source (not shown)
Electric power corresponding to the sum of the thermal energy conducted and supplied from e and 23f can be taken out from both ends of the electrode plates 25d and 25f.

In the thermoelectric conversion element 50 having the structure shown in FIG. 5, all of the thermoelectric conversion elements described so far are arranged so that P-type semiconductors and N-type semiconductors are vertically stacked with a high thermal conductive metal plate sandwiched therebetween. On the other hand, a P-type semiconductor and N
This is a configuration in which the type semiconductors are joined and arranged, and the same effects as those of the thermoelectric conversion element of the present invention described so far can be obtained. That is, one end of the single highly heat-conductive metal plate 53 has a narrow rectangular shape in order to efficiently approach or contact a heat source (not shown), and the P-type semiconductor 51.
The other end where the N-type semiconductor 52 and the N-type semiconductor 52 are joined and arranged has a wide square shape, and copper that also serves as a heat sink is provided on the low temperature end side (upper surface of the drawing) of the P-type semiconductor 51 and the N-type semiconductor 52, respectively. The electrode plates 55, 55 made of (Cu) plates are arranged in a joined state.

Also in the thermoelectric conversion element 50, the P-type semiconductor 51 and the N-type semiconductor 52 are joined to the high thermal conductive metal plate 53, and the P-type semiconductor 51 and the N-type semiconductor 52 are joined to the electrode plates 55 and 55. Is also integrated by brazing with a titanium (Ti) -based active metal brazing material 54. Thermal energy supplied from a heat source (not shown) is supplied to the P-type semiconductor 51 and the N-type semiconductor 5 through the high thermal conductive metal plate 53, respectively.
2 is conducted and supplied. At this time, the semiconductors 51, 5 of each other
2 is arranged on the same plane of the high thermal conductive metal plate 53, but since the PN junction is formed through the high thermal conductive metal plate 53, the semiconductors 51 and 52 are connected on the low temperature end side. It becomes possible to take out electric power from the upper surface of the drawing.

In any of the configurations shown in FIGS. 2 to 5,
The area of the electrode plate joined to the low temperature end side of the semiconductor is made relatively large so that it also serves as a heat sink.
Similar to the electrode plate 15 in the above configuration, the purpose is to increase the temperature difference between the heating portion (PN junction portion) and the open end of each semiconductor and improve the power generation efficiency. Further, by arranging the forced cooling means on these electrode plates, the effect can be further improved.

The thermoelectric conversion element 60 having the structure shown in FIG. 6 is composed mainly of a ring-shaped iron silicate (FeSi ₂ ).
Type semiconductors 61a, 61b, 61c and N type semiconductors 62a,
62b and 62c are formed on the inner peripheral portion and the outer peripheral portion, respectively, to form a PN junction via high thermal conductive metal plates 63a, 63b, 63c, 63d and 63e made of ring-shaped copper (Cu) plates. And joined together to form a cylindrical thermoelectric conversion element. 64a, 64b, 64 in the figure
Reference numerals c, 64d, and 64e are titanium (Ti) -based active metal brazing materials for joining the semiconductor and the high thermal conductive metal plate.
Further, reference numerals 65 and 65 are electrode members joined to the P-type semiconductor 61a located at the upper end and the N-type semiconductor 62c located at the lower end by a titanium (Ti) -based active metal brazing material 64, respectively.

In the cylindrical thermoelectric conversion element 60 having such a structure, the cylindrical member 66 arranged on the inner circumference thereof.
(For example, a ring-shaped high thermal conductive metal plate 63a that contacts the outer peripheral surface of the cylindrical member 66 by using the temperature of exhaust gas or the like that passes through an aluminum (Al) tube whose surface is oxidized to improve electrical insulation) as a heat source. , 63b, 63c to the P-type semiconductor 61
a, 61b, 61c and N-type semiconductors 62a, 62b, 6
Electric power can be generated from the electrode members 65, 65 by generating electric power according to the thermal energy conducted and supplied to the 2c. In this configuration, the ring-shaped high thermal conductive metal plate 63
Each of d and 63e does not directly contribute to the thermal energy supply to the semiconductor, but each plays the role of electrically connecting the electric power generated in the semiconductor in series.

The thermoelectric conversion element 70 having the structure shown in FIG. 7 is composed mainly of iron silicide (FeSi ₂ ) having a rectangular plate shape.
Type semiconductors 71a, 71b, 71c and N type semiconductors 72a,
PN junction is formed through high heat conductive metal plates 73a, 73b, 73c, 73d, 73e made of rectangular copper (Cu) plates alternately arranged at opposite ends of 72b and 72c. Then, they are joined together to form a rectangular parallelepiped thermoelectric conversion element. 74a, 74b in the figure,
74c, 74d, and 74e are titanium (Ti) -based active metal brazing materials for joining the semiconductor and the high thermal conductive metal plate. Also, 75 and 75 are P located at the upper end, respectively.
The electrode member is joined to the type semiconductor 71a and the N-type semiconductor 72c located at the lower end by a titanium (Ti) -based active metal brazing material 74.

In the rectangular parallelepiped thermoelectric conversion element 70 having such a structure, a heat source (not shown) located on one outer peripheral surface side of the thermoelectric conversion element 70 (right side of the thermoelectric conversion element 70 in the drawing) is used. The heat energy of the high thermal conductive metal plates 73a, 73b, 73c from the P-type semiconductors 71a, 71
b, 71c and the N-type semiconductors 72a, 72b, 72c can be conducted and supplied, electric power can be generated according to the thermal energy, and electric power can be taken out from the electrode members 75, 75. In this configuration, the high thermal conductive metal plates 73d and 73e do not directly contribute to the thermal energy supply to the semiconductors, but each plays a role of electrically connecting the electric power generated in the semiconductors in series.

[0037]

EXAMPLE A thermoelectric conversion element 10 of the present invention shown in FIG.
By measuring the load characteristics with the conventional thermoelectric conversion element 1 shown in FIG. 9, it was confirmed that the thermoelectric conversion element 10 of the present invention was excellent. In order to obtain the thermoelectric conversion element 10 of the present invention shown in FIG. 1, the following constituent members were prepared. P-type semiconductor 11 and N-type semiconductor 12 mainly composed of iron silicide (FeSi ₂ ) Composition (wt%): P-type → Fe _43.5 Mn ₄ Si _52.5 N
Mold → Fe _44.5 Co _3.5 Si _51.5 Dimensions: height 4 mm x width 4 mm x length 20 mm Specific resistance (ρ): 0.08 Ωcm High thermal conductive metal plate 13 Material: copper (Cu) plate Dimensions: thickness 0.5 mm x width 5 mm x length 10 mm Titanium (Ti) -based active metal brazing material 14 Structure: Cu-Ni / Ti / Cu-Ni (3-layer composite brazing material) Ti ratio 50 wt% Dimension: Thickness 0.08 mm x width 3 mm x length 5mm Melting point: 900 ° C Electrode 15 Material: Copper (Cu) plate Dimension: Thickness 0.5mm x Width 3mm x Length 10mm Oxidation resistant coating 17 Material: TiN Dimension: Thickness 2μm

The above semiconductors 11 and 12 and the high thermal conductive metal plate 13 are positioned with a predetermined pressure applied through a titanium (Ti) -based active metal brazing material 14 in the atmosphere at 900 ° C. After brazing under the condition of 15 min, the electrode 15 was joined with Zn—Sn solder at 250 ° C. to obtain the thermoelectric conversion element 10 of the present invention.

As the conventional thermoelectric conversion element 1, a pair of semiconductors integrally molded by the conventional powder metallurgy method is used so that the pair of semiconductors has the same composition and substantially the same size as the thermoelectric conversion element 10 of the present invention. As shown in FIGS. 1 and 9, an ammeter 5, a voltmeter 6, and a variable resistor 7 are connected to each thermoelectric conversion element 10 and 1, and in the thermoelectric conversion element 10 of the present invention, a high thermal conductive metal plate 13 is used. , In the conventional thermoelectric conversion element 1, the semiconductor PN junction is heated by the torch (about 800 ° C)
By doing so, the respective load characteristics were measured, and the characteristics shown in FIG. 8 were obtained. It is clear from FIG. 8 that the load characteristics of the thermoelectric conversion element 10 of the present invention are superior to the load characteristics of the conventional thermoelectric conversion element 1, and the power generation capacity (conversion efficiency) of the thermoelectric conversion element 10 of the present invention is It was confirmed to be high.

[0040]

According to the thermoelectric conversion element of the present invention, a P-type semiconductor mainly composed of iron silicide (FeSi ₂ ) and an N-type semiconductor are used.
A high thermal conductive metal plate is placed as a heat energy supply source at the junction of the semiconductors, and heat energy is constantly and efficiently supplied from the heat source located outside each semiconductor. Can be prevented, and power generation efficiency can be improved. In the case of the conventional direct heating type, since the elements other than the joint portion are heated, the element becomes long to separate the cold junction portion and the internal resistance increases, but in the thermoelectric conversion element of the present invention, the heat is a high heat conductive metal plate. Is supplied by heating, and only the PN junction is heated, so a temperature difference can be obtained near the cold junction,
The internal resistance is reduced and the power generation capacity is significantly improved.

Further, since the P-type semiconductor and the N-type semiconductor are manufactured separately and joined together through the high thermal conductive metal plate, mixing of the alloy powder for semiconductors or the like occurs in the PN junction as in the conventional structure. In addition, stable power can be taken out without deterioration of characteristics at the PN junction or variation in electrical characteristics. Furthermore, since it is possible to manufacture the P-type semiconductor and the N-type semiconductor separately, the manufacturing method (filling-molding step) becomes easy,
The configuration has excellent mass productivity. Further, since individual shapes of the P-type semiconductor and the N-type semiconductor can be arbitrarily manufactured according to the application, it is possible to provide the thermoelectric conversion element having various configurations as shown in the examples. Therefore, the applications of these thermoelectric conversion elements can be further expanded.

In the thermoelectric conversion element of the present invention, a heat radiating plate made of a copper (Cu) plate or the like is joined to the low temperature end side of each semiconductor to form a semiconductor heating portion (PN junction portion) and a low temperature end side. It is possible to widen the temperature difference and the power generation efficiency is further improved. Titanium (Ti), which has a relatively high melting point, is used for each member that constitutes the thermoelectric conversion element.
Since it is joined and integrated with a system-based active metal brazing material, it can withstand use in a high temperature atmosphere and can effectively utilize the heat resistance characteristic of a semiconductor mainly composed of iron silicate (FeSi ₂ ). One of the effects, especially 400 °
As a thermal sensor in the temperature range of C to 900 ° C,
It is also effective as a power source.

As described above, the thermoelectric conversion element of the present invention has many advantages. For example, by arranging the thermoelectric conversion element in the vicinity of the stove or the stove, the fan motor can be rotated based on these operations, By using the exhaust heat energy of the car to operate the linear actuator to drive various parts, for example, the thermoelectrically converted electric power is stored in a battery or the like and the battery is used as the power source, or the generated power is used directly. It can be used to operate electronic devices and be used for many purposes. In addition to the exhaust heat of automobiles and boilers, the residual heat of the stove, it is also possible to utilize natural energy such as geothermal heat and solar heat as the heat source, and high heat can be generated by using various heat collecting jigs and devices. It is possible to operate many electronic devices by transferring heat to the high thermal conductive metal plate of.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional explanatory view showing one structural example of a thermoelectric conversion element of the present invention.

2A and 2B are explanatory views showing another configuration example of the thermoelectric conversion element of the present invention, in which a is a top view and b is a longitudinal section.

FIG. 3 is an explanatory top view showing another configuration example of the thermoelectric conversion element of the present invention.

FIG. 4 is a vertical cross-sectional explanatory view showing another configuration example of the thermoelectric conversion element of the present invention.

5A and 5B are explanatory views showing another configuration example of the thermoelectric conversion element of the present invention, in which a is a top view and b is a longitudinal section.

FIG. 6 is a transverse cross-sectional view showing another configuration example of the thermoelectric conversion element of the present invention.

FIG. 7 is a vertical cross-sectional explanatory view showing another configuration example of the thermoelectric conversion element of the present invention.

FIG. 8 is a load characteristic curve diagram showing a result of measuring load characteristics of the thermoelectric conversion element of the present invention and the conventional thermoelectric conversion element.

FIG. 9 is a schematic explanatory diagram of a conventional thermoelectric conversion element.

[Explanation of symbols]

1, 10, 20, 20a, 20b, 20c, 20d, 2
0e, 20f, 50, 60, 70 Thermoelectric conversion element 2, 11, 21, 51, 61a, 61b, 61c, 71
a, 71b, 71c P-type semiconductor 3, 12, 22, 52, 62a, 62b, 62c, 72
a, 72b, 72c N-type semiconductor 4 PN junction part 5 Ammeter 6 Voltmeter 7 Variable resistance 13, 23, 23a, 23b, 23c, 23d, 23
e, 23f, 53, 63a, 63b, 63c, 63d,
63e, 73a, 73b, 73c, 73d, 73e High thermal conductive metal plate 14, 24, 54, 64a, 64b, 64c, 64d,
64e, 74, 74a, 74b, 74c, 74d, 74
e Titanium (Ti) -based active metal brazing material 15, 25, 25a, 25c, 25d, 25f, 55,
65,75 Electrode plate 16 Brazing material 17 Oxidation resistant coating 26 Connection member 66 Cylindrical member

Claims (1)

[Claims] 1. A P containing iron sulfide (FeSi ₂ ) as a main component.
In a thermoelectric conversion element having a PN junction structure of a N-type semiconductor and an N-type semiconductor, a high thermal conductive metal plate is interposed between the pair of semiconductors and brazed with a titanium (Ti) -based active metal brazing material to form a PN junction. A thermoelectric conversion element characterized by being formed.