KR20130047322A - The thermoelectric device having improved thermoelectric characteristics - Google Patents

Abstract

PURPOSE: A thermoelectric device with an improved thermoelectric property is provided to improve thermoelectric performance by maintaining a composition ratio of thermoelectric materials which are initially inputted. CONSTITUTION: Materials including two or more elements selected among a group of Bi, Te, Sb, and Se are weighted. The weighted materials are inputted to a furnace. An ingot is made by melting, cooling, and quenching the materials. One or more elements selected among the group of Bi, Te, Sb, and Se are added to the ingot. Thermoelectric powder is prepared by grinding and pulverizing the ingot and the materials. The thermoelectric powder is sintered. [Reference numerals] (AA) Input to a furnace by weighting materials; (BB) Make an ingot by melting, cooling, and quenching the materials; (CC) Add materials to the ingot; (DD) Make thermoelectric powder by grinding and pulverizing the ingot and the added materials; (EE) Sinter the thermoelectric powder; (FF) Thermoelement

Description

Thermoelectric device having improved thermoelectric characteristics

The present invention relates to a method of manufacturing a thermoelectric device having improved thermoelectric characteristics.

In general, a thermoelectric element refers to an energy conversion material in which electrical energy is generated when a temperature difference is applied between both ends of a device, and conversely, a temperature difference is generated between both ends of an element when an electric energy is applied to the device.

The efficiency of the thermoelectric element can be defined by the following equation, which is a dimensionless ZT value.

(S: 제백 계수, σ: 전기전도도, κ: 열전도도)

(S: Seebeck coefficient, σ: electrical conductivity, κ: thermal conductivity)

The ZT value is proportional to the electrical conductivity and the Seebeck coefficient, and inversely related to the thermal conductivity.

Recently, Bi-Te-based thermoelectric devices have been used as a means for solving heat dissipation problems of high-integrated devices and various sensors due to their excellent thermoelectric performance at room temperature, and are mainly manufactured by unidirectional solidification or single crystal growth. However, the thermoelectric element by the casting method such as the one-way solidification method or the single crystal growth method has a disadvantage of high cost due to the increase in the manufacturing cost due to the reduction of the recovery rate during processing and manufacturing of the module despite the excellent thermoelectric performance.

In order to overcome the problems of the casting method as described above, the research on powder metallurgy, which is excellent in mechanical strength and expected to be advantageous in terms of performance and manufacturing cost, is being actively conducted.

In the powder metallurgy process, an ingot is manufactured by melting and quenching or quenching a material, and then crushing and pulverizing the ingot to obtain a powder, and pressurizing and shaping the powder. It is a method of obtaining the product of the desired form by heating to temperature and solidifying (sintering).

However, even if a Bi-Te-based thermoelectric device is manufactured using a powder metallurgy process, the material is volatilized during melting of the material to manufacture an ingot. It is difficult to obtain a thermoelectric element having good performance.

Therefore, research to solve this problem is urgently required.

The present invention relates to a method of manufacturing a thermoelectric device having improved thermoelectric characteristics.

Specifically, the present invention is to add a material that is volatilized after the production of the ingot (ingot) when melting the material comprising at least two selected from the group consisting of Bi, Te, Sb and Se for the production of ingot (ingot), An object of the present invention is to provide a thermoelectric device having improved thermoelectric performance by maintaining a composition ratio of initially introduced thermoelectric materials.

The present invention provides a method of manufacturing a thermoelectric device comprising the following steps.

(a) weighing materials comprising at least two selected from the group consisting of Bi, Te, Sb, and Se and introducing them into a furnace;

(b) melting the furnace and quenching or quenching the ingot to produce an ingot;

(c) adding at least one material selected from the group consisting of Bi, Te, Sb and Se to the ingot;

(d) crushing and grinding the ingot and material of step (c) together to prepare thermoelectric powder; And

(e) sintering the thermoelectric powder;

The amount of one or more materials selected from the group consisting of Bi, Te, Sb, and Se added in step (c) may be 0.01 to 1.0 part by weight based on 100 parts by weight of the material added in step (a), but is not limited thereto. It doesn't happen.

In the method of manufacturing a thermoelectric device according to the present invention, in the step (a), Bi _x Sb _{2 - x} Te ₃ (where x is 0 <x <2) is weighed using a material of Bi, Sb and Te, The P-type thermoelectric device may be manufactured by adding the same to the furnace, and in step (a), Bi ₂ Te _y Se _{3 -y} using the materials of Bi, Se, and Te (where y is 0 <x <3). The N-type thermoelectric device may be manufactured by weighing to have a composition of and introducing the same into a furnace, but is not limited thereto. The materials may further include known materials.

The material of step (a) may be in the form of beads, but is not limited thereto.

The material of step (a) may be contained in one of the tubes selected from the group consisting of quartz, silica and pyrex tubes after weighing, and may be sealed after vacuum or inert atmosphere, but is not limited thereto. .

The inert atmosphere may be at least one gas atmosphere selected from the group consisting of He, N ₂ , Ne, Ar, and Kr, but is not limited thereto.

In the step (b), the materials may be melted for 8 to 12 hours at a temperature of 600 to 1000 ° C., but is not limited thereto.

The material added in step (c) may be in the form of a powder, but is not limited thereto.

The step (d) may proceed to a ball mill process, but is not limited thereto.

In the step (e), the sintering may be performed by a hot press method or a spark plasma sintering method, but is not limited thereto.

The present invention also includes a plurality of thermoelectric elements formed between the upper and lower insulating substrates and the upper and lower insulating substrates to which metal electrodes are formed, and the thermoelectric elements are thermoelectric devices manufactured according to the present invention. The thermoelectric device provides a thermoelectric module connected in series via metal electrodes of upper and lower insulating substrates.

The thermoelectric module is manufactured by alternately arranging the thermoelectric elements manufactured according to the present invention on the upper and lower insulating substrates on which metal electrodes are formed and electrically connecting them.

The present invention initially adds the volatilized materials after the production of the ingot to melt the materials comprising two or more selected from the group consisting of Bi, Te, Sb and Se for the production of the ingot, By maintaining the composition ratio of the injected thermoelectric materials, it is possible to provide a thermoelectric device having improved thermoelectric performance.

1 schematically illustrates a process of manufacturing a thermoelectric device of the present invention.
2 is a graph measuring ZT values according to temperatures of a P-type thermoelectric device (Comparative Example 1) and a P-type thermoelectric device (Example 1) according to an embodiment of the present invention.
3 is a graph measuring ZT values according to temperatures of an N-type thermoelectric element (Comparative Example 2) and an N-type thermoelectric element (Example 2) according to an embodiment of the present invention.

The present invention provides a method of manufacturing a thermoelectric device having improved thermoelectric performance.

Specifically, the thermoelectric device is manufactured by melting and furnace cooling or quenching a material including two or more selected from the group consisting of Bi, Te, Sb, and Se, and then forming the ingot. It is prepared by sintering the thermoelectric powder obtained by crushing and grinding.

At this time, the materials are melted by weighing each material according to the thermoelectric element to be manufactured, but a portion of the material is volatilized during the melting process, the content of the initial material is changed.

In the present invention, in order to solve the above problems, volatilized materials are added after fabrication of an ingot, thereby manufacturing a thermoelectric device having improved thermoelectric performance.

The method of manufacturing a thermoelectric device according to the present invention includes the following steps, and a manufacturing process of the thermoelectric device is schematically illustrated in FIG. 1.

(a) weighing materials comprising at least two selected from the group consisting of Bi, Te, Sb, and Se and introducing them into a furnace;

(b) melting the furnace and quenching or quenching the ingot to produce an ingot;

(c) adding at least one material selected from the group consisting of Bi, Te, Sb and Se to the ingot;

(d) crushing and grinding the ingot and material of step (c) together to prepare thermoelectric powder; And

(e) sintering the thermoelectric powder;

The thermoelectric element according to the present invention may be a P-type or N-type thermoelectric element.

In order to manufacture the P-type thermoelectric element, a material of Bi, Sb and Te is selected from the group consisting of Bi, Te, Sb, and Se, and Bi _x Sb _{2 - x} Te ₃ (where x is 0 <x < 2) is weighed to have a composition of 2) and put into a furnace,

In order to manufacture the N-type thermoelectric element, a material of Bi, Se, and Te is selected from the group consisting of Bi, Te, Sb, and Se, and Bi ₂ Te _y Se _{3 -y} (where y is 0 <x < It may be weighed to have a composition of 3) and added to the furnace, but is not limited thereto and may further include known materials in the materials.

In step (a), the materials may be weighed in a bead form and contained in a quartz tube, a silica tube, or a Pyrex tube, but are not limited thereto.

 In the step (a), the materials may be enclosed in a quartz tube, a silica tube or a Pyrex tube, sealed in a vacuum or inert atmosphere, and then put into a furnace, and thus sealed in a vacuum or inert atmosphere. In this case, it is preferable that the materials are inhibited from being oxidized when the materials are dissolved in the furnace.

The inert atmosphere may be at least one gas atmosphere selected from the group consisting of He, N ₂ , Ne, Ar, and Kr, but is not limited thereto.

As described above, through the step (a), materials for manufacturing a P-type or N-type thermoelectric element are introduced into a furnace.

In the step (b), ingots are manufactured by melting and furnace-quenching or quenching materials for manufacturing P-type or N-type thermoelectric elements put into a furnace.

The materials are preferably melted for 8 to 12 hours at a temperature of 600 to 1000 ° C., and if the melting occurs below the temperature range and time range, some of the materials remain unmelted and become agglomerates or have a desired composition. Synthesis cannot be achieved and if the melting takes place beyond the above temperature and time ranges, the volatilization of the component elements of the materials is greatly increased, which is undesirable.

When the melting of the materials is completed, the cooling is performed, where the cooling may be furnace cooling or quenching, which is also called furnace cooling, and means cooling the materials slowly in the furnace. Quenching means cooling a temperature above a critical region by immersing a hot metal or alloy in water or oil.

The step (c) is to make a thermoelectric device with improved thermoelectric performance according to the present invention, in the group consisting of Bi, Te, Sb and Se in the ingot (ingot) manufactured through the step (b) One or more materials selected may be added to maintain the composition ratio of the materials initially weighed in step (a).

The form of the material added in the step (c) can be used in the form used in the art, it is particularly preferred because it is possible to accurately weigh and add a small amount of powder (powder).

The amount of at least one material selected from the group consisting of Bi, Te, Sb, and Se added in step (c) will vary depending on the material added, but is usually from 0.01 to 100 parts by weight based on 100 parts by weight of the material added in step (a) 1.0 parts by weight is appropriate, and if added within this range, it compensates for the component elements volatilized upon melting the materials in step (b).

As the material added in the step (c), Te material and Se material are preferable, and Te material is particularly preferable.

Among the initially added Bi, Te, Sb and Se materials, the addition of Te and Se materials to the ingot through step (c) is preferable because the boiling point and vapor pressure of Bi, Te, Sb and Se elements Is related to.

Since the boiling point of Bi is 1564 ° C. and the boiling point of Sb is 1587 ° C., the boiling point of Te and Se is very small while the volatilization content is very small in the range of 600-1000 ° C., which is a temperature at which materials are melted in step (b). Since it is 988 ° C and 685 ° C, respectively, the volatilization is performed in the range of 600 to 1000 ° C, which is a temperature at which the materials are melted in step (b), and the composition ratio of the thermoelectric materials weighed in order to manufacture an initial P-type or N-type thermoelectric element is changed. .

Among them, Te has a very high volatility due to its low vapor pressure at high temperatures, and Te is usually included in the manufacturing process of P-type and N-type thermoelectric devices, so volatilization of Te is a great requirement for reducing the thermoelectric performance of thermoelectric devices. to be.

Therefore, in the present invention, the Te material and the Se material are further added to the ingot through step (c), and in particular, the Te material is added to provide a thermoelectric device having improved thermoelectric performance.

Step (d) is a step of preparing a thermoelectric powder by crushing and pulverizing the ingot and the material of step (c) together, the crushing and pulverization may be performed according to a conventional method in the art, non-limiting examples The ball mill process can be performed.

Step (e) is a step of manufacturing a thermoelectric device by sintering the thermoelectric powder of step (d), the sintering may be performed according to a conventional method in the art, for example, a hot press method or press Spark Plasma Sintering method may be used.

The present invention also provides a thermoelectric module including a thermoelectric device having improved thermoelectric performance.

The thermoelectric module including the thermoelectric element may be implemented according to a method conventionally employed in the art, but is not limited thereto. For example, a metal electrode may be formed between upper and lower insulating substrates facing each other, and the upper and lower insulating substrates. Including a plurality of thermoelectric elements, the thermoelectric element is a thermoelectric element manufactured according to the present invention, the thermoelectric element may have a structure that is connected in series through the metal electrode of the upper and lower insulating substrate.

The thermoelectric module may be manufactured in a conventional manner in the art. For example, the thermoelectric module manufactured according to the present invention may be alternately arranged on the upper and lower insulating substrates on which metal electrodes are formed and electrically connected to each other. It is mentioned to manufacture.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example  1. Fabrication of P-type thermoelectric element

After weighing the Bi, Sb, Te sample so as to have the composition of Bi _{0 .5} Sb _{1 .5} Te _3, put in a quartz (quartz) tube sealed in an inert atmosphere.

Thereafter, the samples contained in the quartz tube are placed in a furnace and melted at a temperature of 800 ° C. for 10 hours, and then quenched to prepare an ingot.

Thereafter, an ingot was placed in a jar containing a ball, and 0.07 parts by weight of a Te sample in the form of a powder based on 100 parts by weight of Bi, Sb, and Te samples, which were initially added. Jar).

Thereafter, the ball mill equipment is operated for 5 hours to grind the ingot and the Te sample to obtain a thermoelectric powder.

Subsequently, the thermoelectric powder was put in a sintered mold and sintered for 30 minutes at a pressure of 200 MPa and a temperature of 420 ° C. using a hot press equipment to manufacture a P-type thermoelectric device.

Example  2. Fabrication of N-type Thermoelectric Devices

After the Bi, Se, Te samples were weighed to have the composition of Bi ₂ Te _{2 .85 0 .15} Se, put in a quartz (quartz) tube sealed in an inert atmosphere.

Thereafter, the samples contained in the quartz tube are placed in a furnace and melted at a temperature of 800 ° C. for 10 hours, and then quenched to prepare an ingot.

Thereafter, an ingot was introduced into a jar containing a ball, and 0.07 parts by weight of a Te sample in the form of a powder based on 100 parts by weight of a Bi, Te, and Se sample was initially added. Jar).

Thereafter, the ball mill equipment is operated for 2 hours to grind the ingot and the Te sample to obtain a thermoelectric powder.

Subsequently, the thermoelectric powder was put in a sintered mold and sintered for 30 minutes at a pressure of 200 MPa and a temperature of 420 ° C. using a hot press equipment to prepare an N-type thermoelectric device.

Comparative example  1. Fabrication of conventional P-type thermoelectric elements

100 wt parts of Bi, Sb, and Te samples initially added in Example 1 P-type was prepared in the same manner as in Example 1 except that 0.07 parts by weight of Te sample in powder form was added to Jar. A thermoelectric device was manufactured.

Comparative example  2. Fabrication of Conventional N-type Thermoelectric Devices

100 wt parts of Bi, Te, Se samples initially added in Example 2 was prepared in the same manner as in Example 2 except that 0.07 parts by weight of Te sample in the form of a powder (powder) was added to Jar A thermoelectric device was manufactured.

Experimental Example

In order to determine the thermoelectric efficiency of the thermoelectric elements of Examples 1 and 2 and Comparative Examples 1 and 2, ZT values represented by the following equations were measured, which are shown in FIGS. 2 and 3.

(S: Seebeck coefficient, σ: electrical conductivity, κ: thermal conductivity)

Referring to FIG. 2, ZT values according to temperatures of the P-type thermoelectric elements of Example 1 and Comparative Example 1 are illustrated, and ZT values of the P-type thermoelectric elements according to Example 1 are P-type thermoelectric elements according to Comparative Example 1. It can be seen that the thermoelectric efficiency of the P-type thermoelectric device according to Example 1 is greater since it is larger than the ZT value of.

Referring to FIG. 3, ZT values according to temperatures of the N-type thermoelectric elements according to Example 2 and Comparative Example 2 are shown, and ZT values of the N-type thermoelectric elements according to Example 2 are compared with conventional N-type thermoelectric elements It can be seen that the thermoelectric efficiency is remarkably improved as compared with Example 2).

100 parts by weight of the material added in step (a) at least one material selected from the group consisting of Bi, Te, Sb and Se after ingot (ingot) according to the manufacturing method of the thermoelectric device of the present invention through the above experimental examples When added in a content of 0.01 to 1.0 parts by weight as a standard, it was confirmed that the thermoelectric efficiency of the thermoelectric element is greatly improved.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but are intended to be described. The scope of the present invention should be interpreted by the following claims, and all technical spirits within the equivalent scope thereof are It should be interpreted as being included in the scope of the present invention.

Claims (15)

(a) weighing materials comprising at least two selected from the group consisting of Bi, Te, Sb, and Se and introducing them into a furnace;
(b) melting the furnace and quenching or quenching the ingot to produce an ingot;
(c) adding at least one material selected from the group consisting of Bi, Te, Sb and Se to the ingot;
(d) crushing and grinding the ingot and material of step (c) together to prepare thermoelectric powder; And
(e) sintering the thermoelectric powder; a method of manufacturing a thermoelectric device comprising a.
The method of claim 1,
The amount of at least one material selected from the group consisting of Bi, Te, Sb and Se added in step (c) is 0.01 to 1.0 parts by weight based on 100 parts by weight of the material added in step (a). Method of manufacturing the device.
The method of claim 1,
The material of step (a) comprises a material of Bi, Sb and Te, the method of manufacturing a thermoelectric device, characterized in that for producing a P-type thermoelectric device.
The method of claim 1,
The materials of step (a) include materials of Bi, Sb and Te, and weighed to have a composition of Bi _x Sb _{2 - x} Te ₃ (where x is 0 <x <2) to manufacture a P-type thermoelectric element. A method of manufacturing a thermoelectric element.
The method of claim 1,
The material of step (a) comprises Bi, Se and Te, the method of manufacturing a thermoelectric device, characterized in that for producing an N-type thermoelectric device.
The method of claim 1,
The materials of step (a) include Bi, Se, and Te, and weighed to have a composition of Bi ₂ Te _y Se _{3 -y} (where y is 0 <x <3), thereby manufacturing an N-type thermoelectric device. Method of manufacturing a thermoelectric element.
The method of claim 1,
The material of step (a) is a method of manufacturing a thermoelectric element, characterized in that the (bead).
The method of claim 1,
The material of step (a) is weighed and then placed in one of the tubes selected from the group consisting of a quartz tube, a silica tube and a Pyrex tube, and manufactured in a vacuum or inert atmosphere and then sealed. Way.
The method of claim 8,
The inert atmosphere is a method of manufacturing a thermoelectric element, characterized in that at least one gas atmosphere selected from the group consisting of He, N ₂ , Ne, Ar and Kr.
The method of claim 1,
In step (b), the materials are melted for 8 to 12 hours at a temperature of 600 to 1000 ° C.
The method of claim 1,
The material added in step (c) is a method of manufacturing a thermoelectric element, characterized in that the powder (powder) form.
The method of claim 1,
The step (d) is a manufacturing method of the thermoelectric element, characterized in that the ball mill (Ball Mill) process.
The method of claim 1,
In the step (e), the sintering is a method of manufacturing a thermoelectric element, characterized in that the hot press (Hot Press) method or a pressure plasma sintering (Spark Plasma Sintering) method.
Upper and lower insulating substrates formed with metal electrodes facing each other;
Including a plurality of thermoelectric elements between the upper and lower insulating substrate,
The thermoelectric element is a thermoelectric element manufactured according to any one of claims 1 to 13,
The thermoelectric device is a thermoelectric module connected in series via the metal electrode of the upper and lower insulating substrate.
The method of manufacturing a thermoelectric module for electrically connecting the thermoelectric elements manufactured according to any one of claims 1 to 13, alternately arranged on the upper and lower insulating substrates on which metal electrodes are formed.

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