JPS60133769A - Thermopower generation element - Google Patents

Abstract

PURPOSE:To offer the titled element of high sensitivity having a practically sufficient thickness by a method wherein a polycrystalline or amorphous thermoelectric semiconductor is constructed by using flame spraying. CONSTITUTION:A cooling body 3 cooled by a coolant 2 is provided in a closed container 1, and a cooling substrate 4 of glass or the like is placed on its surface. A plasma torch generator 5 is used to eject plasma to the substrate 4, and this generator is supplied with an actuation gas and the powder raw material of a thermoelectric material. The container 1 is exhausted by a vacuum pump 6 and then kept in an inert pressure reduction atmosphere. When the actuation gas and the powder raw material are supplied to a plasma torch 7 produced by the generator 5 by the use of such a pressure reduction flame spraying device, liquid drip fine particles attach on the substrate 4 by the fusion of the powder raw material, and are rapidly cooled at the same time, resulting in the formation of an amorphous thermoelectric semiconductor.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical field to which the invention pertains) The present invention relates to a thermoelectric generating element using a polycrystalline or amorphous thermoelectric semiconductor obtained by thermal spraying.

(Technical Background) Unlike solar cells and the like, thermoelectric materials have a characteristic that a polycrystalline structure containing grain boundaries has better thermoelectromotive force characteristics than a single crystal structure. This is expressed by the material property technique χ (χ: thermal conductivity, α: Seebeck coefficient, σ: electrical conductivity), so while χ becomes smaller due to scattering of 7 Omen at grain boundaries, σ depends on density. 1-, so the presence of grain boundaries does not reduce it much. Furthermore, as the crystal grains of the thermoelectric material become smaller, the scattering of 7 omene becomes larger, and if the thermoelectric material has an amorphous structure, the scattering of 7 omene becomes the maximum.

From these facts, it can be said that a necessary condition for a thermoelectric power generation material is that it has a polycrystalline structure containing many grain boundaries, or more preferably an amorphous structure.

By the way, amorphous thermoelectric materials require a bulk material with a thickness of several mm, but in the normal melt quenching method, only the surface is in contact with the refrigerant and the inside is difficult to cool, so crystallization easily occurs and thick There was a problem with not being able to get anything.

(Objective of the Invention) In view of the above points, the present invention aims to provide a highly sensitive thermoelectric power generation element having a practically sufficient thickness by constructing a polycrystalline or amorphous thermoelectric semiconductor using thermal spraying. That is.

(Embodiments of the Invention) 2- Hereinafter, embodiments of the thermoelectric power generating element according to the present invention will be described according to the drawings.

First, a reduced pressure thermal spraying apparatus as shown in FIG. 1 is prepared. In this figure, a cooling body 3 cooled by a pipe 2 through which a refrigerant such as water or liquid nitrogen passes is installed in a closed container 1, and a cooling substrate 4 made of glass or the like is placed on the cooling body 3. On the other hand, a plasma torch generator 5 is provided so as to face the cooling substrate 4, and is supplied with a working gas (an inert gas such as argon) and a powder raw material of a thermoelectric material. The powder raw material is a carfugen-based compound semiconductor material, a silicide-based semiconductor material, other compound semiconductor materials, simple silicon, simple germanium, or the like. The inside of the container 1 is evacuated by a vacuum pump 6 to maintain an inert reduced pressure atmosphere of about 0.1 Torr, and the entire container is also cooled.

Using the apparatus shown in FIG. 1, the operating gas and the powder raw material as described above are supplied to the plasma torch 7 by the plasma torch generator 5, and are injected onto the cooling substrate 4 and deposited on the substrate. At this time, when the droplet fine particles of the melted powder raw material adhere to the cooling substrate 4, they are rapidly cooled and become an amorphous thermoelectric semiconductor.

By performing such low-pressure spraying for a predetermined period of time, a bulk of the amorphous thermoelectric semiconductor 8 deposited several mm or more on the substrate 4 can be obtained as shown in FIG.

FIG. 3 shows an enlarged cross section of the amorphous thermoelectric semiconductor 8, in which individual droplet fine particles of melted powder raw material form a cooling substrate 4.
It can be seen that the boundary when adhered to constitutes a grain boundary 9. Therefore, compared to the conventional melt quenching method, an amorphous thermoelectric semiconductor formed by thermal spraying contains many grain boundaries unique to thermal spraying, which further increases the scattering of 7 Omen and reduces thermal conductivity. can do.

From the state in which the bulk of the amorphous thermoelectric semiconductor 8 is attached to the substrate 4 in FIG. 2, the bulk of the amorphous thermoelectric semiconductor 8 is peeled off, and the fourth
As shown in the figure, the amorphous thermoelectric semiconductor 8 is cut into predetermined dimensions, and the amorphous thermoelectric semiconductor 8 is further cut as shown in FIG.
Electrodes 10 for extracting thermoelectromotive force are formed on a pair of surfaces of A.

According to the above embodiment, the following effects can be achieved 3- be able to.

(1) Since the thermal spraying method is used, the starting material is droplet particles, and each melted particle adheres to the cooling substrate, allowing for a high cooling rate and the ability to obtain thick particles. At the same time, high-sensitivity materials that were previously difficult to become amorphous can be obtained in bulk form.

(2) By using the thermal spraying method, grain boundaries that occur when individual droplet particles adhere to the substrate can be included in the amorphous thermoelectric semiconductor, making it possible to significantly reduce thermal conductivity. . As a result, when used as a thermoelectric generator, it is possible to create a large temperature difference between the high temperature side and the low temperature side.
The device thickness can be reduced and the electrical resistance can also be reduced, providing excellent characteristics as a thermoelectric power generation device.

In the above embodiment, an amorphous thermoelectric semiconductor was obtained by thermal spraying, but a thermoelectric semiconductor containing at least a portion of a polycrystalline structure may also be obtained by thermal spraying.

(Effects of the Invention) 5-4- As explained above, according to the present invention, by forming a polycrystalline or amorphous thermoelectric semiconductor using thermal spraying, a highly sensitive material having a thickness sufficient for practical use can be produced. A thermoelectric power generating element can be obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a reduced pressure spraying apparatus for producing an amorphous thermoelectric semiconductor in an embodiment of the present invention, and FIG. 2 is a front view of a state in which a bulk of an amorphous thermoelectric semiconductor is formed on a substrate. Figure 3 is an enlarged cross-sectional view of the cross-section of the amorphous thermoelectric semiconductor viewed through a microscope, Figure 4 is a front view showing the bulk of the amorphous thermoelectric semiconductor after it has been peeled off from the substrate, and Figure 5 is the bulk divided. FIG. 2 is a front view showing a thermoelectric generating element in which a pair of electrodes are formed. 4... Substrate, 7... Plasma torch, 8... Amorphous thermoelectric semiconductor, 10... Electrode. Patent applicant TDC Co., Ltd. Patent attorney Takashi Murai 61

Claims (1)

[Claims] (1) A thermoelectric generating element characterized in that a polycrystalline or amorphous thermoelectric semiconductor is formed by thermal spraying, and a pair of electrodes for extracting thermoelectromotive force is provided on the thermoelectric semiconductor.