JP3235386B2 - Thermoelectric material and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a lightweight material utilizing the thermoelectric properties of quasicrystals and the electrical conductivity of aluminum.
The present invention relates to a thermoelectric material such as a thermoelectric element suitable for environmental protection and a method for manufacturing the same.

[0002]

2. Description of the Related Art A typical Peltier effect element (thermoelectric element) suitable for use at room temperature has a composition mainly composed of Bi, Sb, Te or Se. That is, Bi-Sb-Te-based and Bi-Sb-Te-Se-based thermoelectric materials are widely used as room temperature devices.

FIG. 1 is a schematic diagram showing a thermoelectric element module. P-type thermoelectric material 3 between a pair of ceramic plates 1
And the n-type thermoelectric material 4 are sandwiched between the ceramic plate 1 and the p-type thermoelectric material 3 and the n-type thermoelectric material 4.
Is provided.

[0004] The p-type and n-type thermoelectric materials 3 and 4 are B
It is made of a material mainly composed of i, Sb, Te or Se.

[0005]

However, since these conventional thermoelectric materials are toxic elements such as Bi, Sb, Te, and Se, they have a drawback that they are liable to adversely affect the environment. Further, these thermoelectric materials have a specific gravity of 6.7 g.
/ Cm ³ , and has the disadvantage of being heavy.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a thermoelectric material which is lightweight and suitable for environmental protection, and a method for manufacturing the same.

[0007]

In the thermoelectric material according to the present invention, Q is an element selected from the group consisting of V, Cr, Mn and Mo, and M is selected from the group consisting of Fe, Co, Ni and Si. And R is Ti, Zr, Y, Ce, N
d and Sm, and T is M
g, Mn, Fe, Re, Ru, Os, an element selected from the group consisting of Li, Co, Cr, Mn, Fe,
When the element is selected from the group consisting of V, the general formula has a composition selected from the group of compositions represented by the following chemical formulas 1 to 5, and includes a quasicrystal in the structure. I do.

[0008]

[Image Omitted] Al _100-X Q _X (however, 3 ≦ X ≦ 20 atomic%)

[0009]

## STR2 ## Al _100-XYZ Q _X M _Y R _Z (where 3 ≦ X ≦ 2
0 atomic%, 0 ≦ Y ≦ 15 atomic%, 0 ≦ Z ≦ 2 atomic%)

[0010]

[Image Omitted] Al _100-XY Pd _X T _Y (where 5 ≦ X <20
Atomic%, 2 ≦ Y <10 atomic%)

[0011]

_{Embedded image} Al _100-XY Cu _X D _Y (where 5 ≦ X <17
Atomic%, 3 ≦ Y <12 atomic%)

[0012]

[Image Omitted] Al _100-XY Ni _X Co _Y (provided that 5 ≦ X <1
5 atomic%, 5 ≦ Y <15 atomic%)

[0013] In the method for producing a thermoelectric material according to the present invention, an aluminum-based alloy having a general formula selected from the group of compositions represented by the above chemical formulas 1 to 5 is quenched by a liquid quenching method or a gas atomizing method. After obtaining the ribbon, flake or powder, and as it is or heat-treated to a quasicrystalline phase,
It is characterized by being solidified by hot pressing or extrusion.

The quasicrystal may have a structure selected from the group consisting of an icosahedral phase, a regular decagonal phase, and an approximate crystal phase thereof. The approximate crystal phase of the quasicrystal refers to a crystal whose local structure is similar to the quasicrystal.

[0015]

In the present invention, since the quasicrystal composed of an aluminum-based alloy is used as the thermoelectric material, the specific gravity is 2.5 to 2.5.
As light as 3.5 g / cm ³ , it is suitable for environmental protection. Also, this thermoelectric material has an excellent figure of merit.

In Formula 1, X is less than 3, X in Formula 2 is less than 3, X in Formula 3 is less than 5, X in Formula 4 is less than 5 or Y is less than 3, and in Formula 5, X is less than 5 or Y is less than 3. If it is less than 5, a quasicrystalline phase will not be obtained, and the thermoelectromotive force α will decrease, resulting in a lower Z value. In the latter two cases, and when X is less than 5 or Y is less than 2 in Chemical Formula 3, in addition to the above-mentioned difficulties, Al
The number of phases increases, κ increases, and the figure of merit Z decreases.

In Formula 1, X is 20 or more;
X is 20 or more or Y is 15 or more, in Chemical Formula 3, X is 20 or more or Y is 10 or more, in Chemical Formula 4, X is 17 or more or Y is 12 or more, and in Chemical Formula 5, X is 15 or more or Y is 15 or more. In this case, an intermetallic compound phase is generated, the quasicrystalline phase is reduced, the thermoelectromotive force α is reduced, and the figure of merit Z is reduced.

Further, in the chemical formula 2, when Z exceeds 2, the amorphous phase and the intermetallic compound phase increase, the quasicrystalline phase decreases, the thermoelectromotive force α decreases, and the figure of merit Z decreases.

[0019]

Next, embodiments of the present invention will be described in more detail. Quasicrystals of the thermoelectric material made of these aluminum-based alloys can be obtained by a liquid quenching method.

This quasi-crystalline phase is formed into a ribbon,
It can be obtained by obtaining a slab or a powder or by further heat treating it. Further, instead of the liquid quenching method, a gas atomizing method can be applied.
Then, the quasi-crystal phase is solidified and formed by a hot press or an extrusion method or the like, whereby a thermoelectric material can be obtained.

Next, a method for producing the quasicrystalline phase composed of the aluminum-based alloy will be specifically described. FIG. 2 is a diagram illustrating the liquid quenching method. And quartz nozzle 5 is disposed above the copper roll 6, the quartz nozzle 5 melt 7 of the aluminum base alloy is stored.

Then, the molten metal 7 from the lower end 9 of the quartz nozzle 5
Was supplied onto the copper roll 6 and rotates the copper roll 6 in the direction of the arrow, the molten metal 7 is quenched by the copper roll 6, the ribbon 8 is obtained.

FIG. 3 is a view showing a gas atomizing method.
The molten metal is stored in the molten metal holding crucible 11, and a small stream 14 of the molten metal flows out from the center of the lower wall of the crucible 11. The spray nozzle 1 is provided on the lower surface of the crucible 11.
A high-pressure gas is sprayed from the spray nozzle 13 toward the molten metal narrow stream 14.

In this gas atomizing method, the molten metal fine stream 14 is formed at a powdering point 15 where the high-pressure gas 12 is blown.
Is quenched and powdered. This powdered aluminum-based alloy is cooled in the process of falling from powdering point 15.

The quenched ribbon 8 obtained in FIG. 2 or the powder 16 obtained in FIG. 3 is pulverized and classified as it is or after heat treatment, and then solidified.

This solidification can be performed by a press method or an extrusion method. For example, the solidification molding conditions by pressing are as follows: press pressure P and press temperature T are set to 10 under the following conditions.
Process for more than a minute.

[0027] 29.4 MPa ≦ P ≦ 784 MPa at room temperature ≦ T ≦ 450 ° C. On the other hand, if the solidified molded by extrusion process, to condition the following <br/> under the temperature extrusion. That is, in the extrusion, the extrusion temperature is set to room temperature or higher, for example, 450 ° C. (723 K) or lower. The extrusion ratio is, for example, 5 to 20.

It is preferred that preheating be performed before the extrusion step. The preheating condition is, for example, 240 seconds for an oil bath of 573K or less, and 900 seconds for an electric furnace of 573 to 725K.

The extrusion ratio is 5 to 20. The extrusion ratio is a measure of the degree of deformation of the material in the extrusion process.
If the cross-sectional area after extrusion is a, it is represented by A / a. In some cases, the extrusion ratio is evaluated based on the cross-sectional reduction rate. Also,
The extrusion ratios 5 to 20 are obtained when the die half angle is 30 ° and the extrusion speed (ram speed) is 5 mm / sec.

The extruded billet has the structure shown in FIG.
That is, the container 20 is made of aluminum or copper having an outer diameter of 23 mm and an inner diameter of 20 mm. In this container 20, a total of 20 to 25 g of the powder 21 is added by about 78% by cold pressing at a pressure of 250 MPa. Packed with the filling rate of
After arranging the spacers 22, the chamber is evacuated for about 21.6 ks at a degree of vacuum of 1 × 10 ⁻³ Pa, and then replaced with Ar gas.
Thereafter, the plug 23 is disposed, and the space between the plug 23 and the inner surface of the container 20 is sealed with an epoxy-based or ceramic-based adhesive 24. In this way, an extruded billet is obtained.

FIG. 5 is a diagram showing an outline of the impact molding method.
A sparring ring 3 is attached to one end of the cylindrical holder 31.
A container 33 is installed with its opening directed toward the other end of the holder 31 via a container 2. A powder 34 is stored in the container 33, and a plug 35 encapsulates the powder 34. Then, the propulsion body 37 is fired from the impact gun toward the plug 35, and the flyer 36 fixed to the propulsion body 37 collides with the plug 35 at a predetermined speed. The impact pressure is 20 to 200 GPa, and the powder 34 is instantaneously solidified and formed by the impact force.

The solidified aluminum base alloy is cut into a predetermined shape and then modularized.

The figure of merit Z of the thermoelectric material is represented by Z = α ² σ / κ. Here, α is the thermoelectromotive force, σ is the electrical conductivity, and κ is the thermal conductivity. In the present embodiment, since a quasi-crystal is included, the thermoelectromotive force is 20 to 5 different from a normal crystal material.
It increases 0 times, and the thermoelectromotive force κ decreases to 1/50 to 1/100. In addition, the Al phase improves the conductivity σ, and as a result, the figure of merit Z improves.

Next, the result of actually manufacturing the thermoelectric material according to the embodiment of the present invention and examining the characteristics thereof will be described in comparison with a comparative example. However, the measurement temperatures are all room temperature.
The properties of these thermoelectric materials are shown in Table 1 below (Examples of the present invention).
And Table 2 (Comparative Example). | Α | is the thermoelectromotive force α
, Ρ is a specific resistance, and Z is a figure of merit.

[0035]

[Table 1]

[0036]

[Table 2]

From the comparison of Tables 1 and 2, the thermoelectric materials according to the examples of the present invention all have a high figure of merit, whereas the thermoelectric material of the comparative example has a low figure of merit.

[0038]

As described above, since the present invention is a thermoelectric material made of a quasicrystal of an aluminum-based alloy having a specific composition, it has an excellent effect of being lightweight and having high conductivity. Further, these constituent elements have an advantage that they do not pollute the environment.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an example of a thermoelectric element.

FIG. 2 is a schematic diagram illustrating a liquid quenching method.

FIG. 3 is a schematic diagram illustrating a gas atomizing method.

FIG. 4 is a diagram illustrating a method for producing an extruded billet.

FIG. 5 is a diagram illustrating an impact molding method.

[Explanation of symbols]

1: ceramic plate, 2: electrode, 3: p-type thermoelectric material, 4:
n-type thermoelectric material, 5: quartz nozzle, 6: copper roll, 7:
Molten metal, 8: thin ribbon, 11: molten metal holding crucible, 12: high pressure gas, 13: spray nozzle, 14: melt flow, 15: powdering point, 16: powder, 20: container, 21: powder, 22: Spacer, 23: plug, 24: adhesive, 31: holder, 3
2: sparring ring, 33: container, 34: powder, 35: plug, 36: flyer, 37: propulsion body

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C22C 45/08 C22C 21/00-21/18 H01L 35/14 H01L 35/32 H01L 35/34

Claims (7)

(57) [Claims] The method according to claim 1] Q V, Cr, Mn, in the case of the elements selected from the group consisting of Mo, the general formula has a set formed represented by the following formula, including a quasi-crystals in the structure A thermoelectric material, characterized in that: Al _100-X Q _X (however, 3 ≦ X ≦ 20 atomic%) 2. Q is a group consisting of V, Cr, Mn and Mo.
M is Fe, Co, Ni, Si
R is Ti, Zr,
An element selected from the group consisting of Y, Ce, Nd, and Sm
In the case, the general formula has a composition represented by the following formula,
A thermoelectric material comprising a quasicrystal in a structure. _{Al 100-X-Y-Z} Q X M Y R Z, ( where, 3 ≦ X
≦ 20 atomic%, 0 ≦ Y ≦ 15 atomic%, 0 ≦ Z ≦ 2 atoms
%) 3. T represents Mg, Mn, Fe, Re, Ru, O
When the element selected from the group consisting of s
Has a composition represented by the following formula, and contains a quasicrystal in the structure.
Thermoelectric material characterized in that: _{Al 100-X-Y Pd X} T Y, ( where, 5 ≦ X <20
Atomic%, 2 ≦ Y <10 atomic%) 4. D is Li, Co, Cr, Mn, Fe, V
When the element selected from the group consisting of
It has a composition represented by the following formula and contains quasicrystals in its structure
A thermoelectric material, characterized in that: Al _100-XY Cu _X D _Y (provided that 5 ≦ X <17
Atomic%, 3 ≦ Y <12 atomic%) 5. The composition according to claim 1, wherein said composition has a composition represented by the following formula :
And a quasicrystal in the structure. Al _100-XY Ni _X Co _Y (provided that 5 ≦ X <1
5 atomic%, 5 ≦ Y <15 atomic%) Wherein said quasi-crystals have an icosahedral phase, regular decagon phase and any one of claims 1 to 5, characterized in that it has a structure selected from the group consisting of approximate crystal phase <br />. 7. Q is an element selected from the group consisting of V, Cr, Mn, Mo, M is an element selected from the group consisting of Fe, Co, Ni, Si, and R is Ti, Zr,
Y is an element selected from the group consisting of Ce, Nd, and Sm; T is an element selected from the group consisting of Mg, Mn, Fe, Re, Ru, and Os; and D is Li, Co, Cr, M
When an element selected from the group consisting of n, Fe, and V is used, an aluminum-based alloy having a composition selected from a group represented by the following general formula is quenched by a liquid quenching method or a gas atomizing method. To obtain a ribbon, flake or powder,
A method for producing a thermoelectric material, wherein the thermoelectric material is directly or heat-treated to obtain a quasi-crystalline phase and then solidified by hot pressing or extrusion. Al _{100-X Q X,} (where, 3 ≦ X ≦ 20 _{atomic%) Al 100-X-Y} -Z Q X M Y R Z, ( where, 3 ≦ X
≦ 20 at%, 0 ≦ Y ≦ 15 at%, 0 ≦ Z ≦ 2 at%) Al _100-XY Pd _X T _Y , where 5 ≦ X <20
Atomic%, 2 ≦ Y <10 atomic%) Al _100-XY Cu _X D _Y (provided that 5 ≦ X <17
Atomic%, 3 ≦ Y <12 atomic%) Al _100-XY Ni _X Co _Y (provided that 5 ≦ X <1
5 atomic%, 5 ≦ Y <15 atomic%)