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Thermoelectric conversion module and production method therefor

a technology of thermal conversion module and production method, which is applied in the manufacture/treatment of thermoelectric devices, thermoelectric devices with peltier/seeback effect, electrical apparatus, etc., can solve the problems of low power density and low energy conversion efficiency of power generation systems, fracture at the bonding portion between, and leakage of soft soldering materials, so as to reduce the difference in amount, prevent fracturing, and heat and electricity are efficiently conducted

Inactive Publication Date: 2012-06-28
HITACHI POWDERED METALS COMPANY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0009]In view of these circumstances, an object of the present invention is to provide a thermoelectric conversion module and a production method therefor. In the thermoelectric conversion module, thermal stress occurs when it is used, but the degree of the thermal stress is decreased. Therefore, in the thermoelectric conversion module, the bonding portion between the thermoelectric conversion element and the electrode and its vicinity are prevented from fracturing. Moreover, the thermoelectric conversion module can be used at high temperatures.
[0014]According to the thermoelectric conversion module of the present invention, the porous metal layer, which is made of nickel or silver and has a density ratio of 50 to 90%, is provided between the thermoelectric conversion element and the electrode. The porous metal layer decreases the difference in the amounts of the thermal expansion of the thermoelectric conversion element and the electrode. Therefore, the bonding portion between the thermoelectric conversion element and the electrode and its vicinity are prevented from fracturing. Since the porous metal layer is metallurgically bonded to both the thermoelectric conversion element and the electrode, heat and electricity are efficiently conducted between the thermoelectric conversion element and the electrode. Moreover, the porous metal layer made of nickel or silver has a high melting point, thereby providing a thermoelectric conversion module in which melting and leaking of the bonding portion do not occur at high temperatures.

Problems solved by technology

However, the power generation system has low power density and low energy conversion efficiency.
The large thermal stress easily causes fracture at the bonding portion between the thermoelectric conversion element and the electrode and its vicinity.
In this case, if the temperature of the heating side is set to be not less than the melt temperature of the soft soldering material, the soft soldering material is melted and leaks.
Therefore, in this kind of thermoelectric conversion module, the temperature of the heating side is limited, and the amount of the power generation is limited.

Method used

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  • Thermoelectric conversion module and production method therefor
  • Thermoelectric conversion module and production method therefor
  • Thermoelectric conversion module and production method therefor

Examples

Experimental program
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Effect test

first example

[0043]Nickel powder particles having an average particle diameter of 1 μm and a maximum particle diameter of not more than 10 μm were prepared. Then, 35 volume % of the nickel powder particles were dispersed in normal methyl pyrolidone including 8 volume % of hydroxyl propyl cellulose, whereby a paste was prepared. The paste had a viscosity of approximately 40 Pa·s. The paste was applied to both end surfaces of a thermoelectric conversion element made of silicon germanium. The both end surfaces of the thermoelectric conversion element were abutted with electrodes made of molybdenum. Then, the paste was arranged between the thermoelectric conversion element and the electrode, whereby a thermoelectric conversion module was assembled. A weight of 50 g (corresponding to 1 kPa) was applied to the thermoelectric conversion module and it was placed in a sintering furnace. The thermoelectric conversion module was heated at 500° C. in a hydrogen gas atmosphere so as to remove the paste excep...

second example

[0050]The thermoelectric conversion element used in the First Example was changed to a thermoelectric conversion element made of Mg2Si, in which both end surfaces were covered with nickel. This thermoelectric conversion element was prepared as follows. First, a bulk sintered compact made of Mg2Si was prepared. The bulk sintered compact was plated with nickel and was cut into the shape of the thermoelectric conversion element. Then, a thermoelectric conversion module was made and was evaluated as in the case of the First Example. As a result, although the thermoelectric conversion element was changed, when the density ratio of the porous metal layer was 50 to 90%, the thermal stress was sufficiently decreased, and good bonding condition was maintained. In addition, by performing sintering at 650 to 850° C., the above density ratio was obtained.

third example

[0051]Several kinds of nickel powder particles having an average particle diameter shown in Table 2 were prepared, and pastes were made as in the case of the First Example. Then, thermoelectric conversion modules were assembled by using the pastes as in the case of the First Example. The thermoelectric conversion modules were sintered at 800° C. so as to remove the paste except for the metal powder particles, and to sinter and diffusion bond the metal powder particles as in the case of the First Example. Accordingly, two sets of samples of the thermoelectric conversion modules of the sample Nos. 08 to 13 were prepared. In these samples, the density ratio of the porous metal layer was measured, and the bonding portion before and after the heat test was evaluated. These results are also shown in Table 2.

TABLE 2Densityratio ofMetal powder particles μmporous metalBonding conditionSampleAverageMaximumlayerBeforeAfterNo.particle sizeparticle size%heat testheat test080.0110.096∘x090.110.09...

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Abstract

A thermoelectric conversion module has a thermoelectric conversion element and an electrode, which are metallurgically bonded together via a porous metal layer. The porous metal layer is made of nickel or silver and has a density ratio of 50 to 90%.

Description

BACKGROUND OF THE INVENTION[0001]1. Technical Field[0002]The present invention relates to a thermoelectric conversion module that converts thermal energy to electric energy, and relates to a production method therefor. The thermoelectric conversion module has a bonding portion between a thermoelectric conversion element and an electrode, and thermal stress may occur in the bonding portion. Therefore, specifically, the present invention relates to a thermoelectric conversion module with a function to decrease the thermal stress, and relates to a production technique therefor.[0003]2. Background Art[0004]A power generation system provided with a thermoelectric conversion module using thermoelectric conversion elements directly generates electricity. This power generation system has a simple structure and does not have a movable part, thereby having high reliability and facilitating maintenance thereof. However, the power generation system has low power density and low energy conversio...

Claims

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Application Information

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IPC IPC(8): H01L35/30H01L35/34H01L35/08
CPCH01L35/34H01L35/08H10N10/817H10N10/01
Inventor JINUSHI, TAKAHIROISHIJIMA, ZENZO
Owner HITACHI POWDERED METALS COMPANY
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