KR102070644B1 - Mixed metalizing structure for skutterudite thermoelectric materials, metalizing method for skutterudite thermoelectric materials, skutterudite thermoelectric materials with mixed metalizing structure and manufacturing method for the same - Google Patents

Abstract

The present invention relates to a mixed metallizing structure for the skutterrudite thermoelectric material, which is a metallizing structure formed on the surface of the skutterrudite thermoelectric material, characterized in that the CoSi ₂ compound and the pure metal Co is mixed. do.
The present invention, by using CoSi2 which can prevent the diffusion of the skutterrudite thermoelectric material, by using Co mixed to solve the problem of low contact resistance, even if used for a long time at high temperatures Not only can it be operated stably without degrading performance due to diffusion, it has an excellent effect of improving the efficiency of the thermoelectric module due to low contact resistance.
Finally, the lifespan, stability and efficiency of the thermoelectric power module using the scrutherite thermoelectric material are all improved, so that the power generation efficiency of the thermoelectric power module is greatly improved in the long term.

Description

MIXED METALIZING STRUCTURE FOR SKUTTERUDITE THERMOELECTRIC MATERIALS, METALIZING METHOD FOR SKUTTERUDITE THERMOELECTRIC MATERIALS, SKUTTERUDITE THERMOELECTRIC MATERIALS WITH MIXED METALIZING STRUCTURE AND MANUFACTURING METHOD FOR THE SAME}

The present invention relates to a metallizing method for a thermoelectric material constituting a thermoelectric generator module, and more particularly, to a metallizing method for a scrutherite thermoelectric material.

In general, a thermoelectric material is a material capable of converting thermal energy into electrical energy, and is used for thermoelectric power by constructing a thermoelectric power module. Thermoelectric power generation technology is an energy harvesting technology that converts thermal energy into electrical energy. It is also attracting attention in the field of renewable energy technology because it can be used in industrial and various waste heat generation.

Thermoelectric power generation technology, known as low-efficiency energy conversion technology for decades, is reported to be capable of more than 10% efficiency in the mid-temperature (300 ~ 700 ℃) area. In particular, the thermoelectric material in the mid-temperature region is suitable for converting the exhaust heat (400 ~ 600 ℃), etc. discarded in automobiles, it is expected to contribute significantly to energy saving when commercialized.

Among the thermoelectric materials, SKD (SKD) thermoelectric material is a promising material showing good thermoelectric and mechanical properties in the mid-temperature range, so many institutions around the world are developing mid-temperature thermoelectric power modules using scutterteite. Metallizing (metallization), one of the core technologies of the medium temperature thermoelectric power module, prevents mechanical cracking due to the difference in thermal expansion coefficient between the thermoelectric material and the electrode when joining the thermoelectric material to the electrode and prevents continuous diffusion of the bonding interface in the medium temperature region. It is a technique of forming a metal layer on the surface of a thermoelectric material.

Ti, which can exhibit low contact resistance while solving the problem of thermal expansion coefficient, is a representative metallizing material. Ti is thermally expanded in a similar behavior to n-type scutterite thermoelectric materials from room temperature to 973K, so that no cracking occurs between the metallizing layer and the thermoelectric material after metallization, and shows low contact resistance as shown in FIG. 3. gave. However, as shown in the EDS analysis result shown in FIG. 4, it can be seen that the inter-diffusion between Ti and n-type scudrudite thermoelectric material elements is formed to form the third intermetallic compound. Formation of such an intermetallic compound results in a drastic deterioration in the efficiency of the thermoelectric module while changing the composition of the scuderiteite thermoelectric material.

United States Patent 4855810

An object of the present invention is to provide a metallizing structure capable of improving the efficiency of a thermoelectric module because the contact resistance is low while preventing the diffusion of the scuderiteite thermoelectric material.

The mixed metallizing structure for the scutterrudite thermoelectric material according to the present invention for achieving the above object is a metallizing structure formed on the surface of the scuderudite thermoelectric material, the CoSi ₂ compound and the pure metal Co is mixed Characterized in that the material.

In order to solve the diffusion problem caused in the conventional metal material such as Ti metalizing layer, a study has been conducted to use a Si compound such as CoSi ₂ to prevent the diffusion. Metals and Si compounds function to prevent the diffusion of elements contained in the scuderiteite thermoelectric material, but Si is a semiconductor material having a higher resistivity than a conductor, and the molar ratio of the metal and Si compound CoSi ₂ is higher than that of Co. 10 ^-6 μΩcm ² measured in Ti metallization layer due to 2 times more Si Level contact resistance of 10 ^-4 μΩcm ² As a result, the efficiency of the thermoelectric material is lowered as a result. Since the conventional technology has not solved the problem of efficiency reduction due to the increase in contact resistance caused by the Si compound, the technique using the Si compound as the metallizing layer has not been put to practical use.

The inventors of the present invention have developed the present invention using a mixture of, CoSi ₂ and pure Co to solve the other hand, the high contact resistance problem using the CoSi _2, a compound of Co and Si.

The present invention is applied to a metallizing structure by mixing a material of CoSi ₂ and pure Co to the metallizing structure, thereby preventing the diffusion between the elements of the scutterrudite thermoelectric material and the elements of the metallizing layer and at the same time due to the CoSi ₂ metallizing layer To solve the problem of increasing the contact resistance, to propose a metalizing structure suitable for practical use.

On the other hand, what is described herein as a "skutterrudite thermoelectric material" does not refer only to the scutterrudite thermoelectric material of the CoSb ₃ or FeSb ₃ composition, but a variety of materials in various basic compositions represented by the scutterrudite system It is used including both the case of addition or doping.

At this time, the mixing ratio of CoSi ₂ compound and Co is preferably in the range of 0.9 to 1.1: 0.9 to 1.1 in molar ratio.

Further, good to apply the foil is formed by applying pressure to the CoSi ₂ compound and a mixture of Co of the pure metal state mixed ingredients in metallizing structure, the foil is recommended mixed with CoSi ₂ compound and the powdery Co respectively, CoSi ₂ It is preferable that the average particle diameter of powder and Co powder is 1/10 or less of foil thickness.

According to another aspect of the present invention, a metallized scutterrudite thermoelectric material is a scutterrudite thermoelectric material having a metallization layer formed on a surface thereof, in which the metallization layer is a CoSi ₂ compound and a pure metal Co. Characterized in that the material.

At this time, the mixing ratio of CoSi ₂ compound and Co is preferably in the range of 0.9 to 1.1: 0.9 to 1.1 in molar ratio.

In addition, the metallizing layer is preferably a foil formed by applying pressure to a mixed material of CoSi ₂ compound and Co in a pure metal state, and the foil is preferably a mixture of CoSi ₂ compound and Co in powder form, and CoSi ₂ powder and It is preferable that the average particle diameter of Co powder is 1/10 or less of foil thickness.

And it is preferable that the thickness of a metallizing layer is 400 micrometers-600 micrometers.

According to still another aspect of the present invention, a metallizing method of a scutterrudite thermoelectric material is a method of performing metallization on the surface of a scutterrudite thermoelectric material, wherein the CoSi ₂ compound and It is characterized in that to form a metallizing layer of a material in which Co in a pure metal state is mixed.

At this time, the mixing ratio of CoSi ₂ compound and Co is preferably in the range of 0.9 to 1.1: 0.9 to 1.1 in molar ratio.

In addition, it is preferable that the foil is formed by applying pressure to a mixed material in which a CoSi ₂ compound and Co in a pure metal state are mixed, and then attaching the foil to the surface of the scuderudite thermoelectric material.

The process of forming the foil by applying pressure to the mixed material in which the CoSi ₂ compound is mixed with Co in the pure metal state is preferably performed at a temperature range of 900 to 1000 ° C. and a pressure range of 40 to 60 MPa.

In the process of forming a foil by applying pressure to a mixed material of CoSi ₂ compound and pure metal Co, the CoSi ₂ compound and Co are preferably mixed in a powder state, and the average particle diameter of CoSi ₂ powder and Co powder is foil. It is preferable that it is 1/10 or less of thickness.

The thickness of the formed foil is preferably in the range of 400 μm to 600 μm.

In the method for producing a metallized scrutherite thermoelectric material according to the last aspect of the present invention, in the method for producing a scrutherite thermoelectric material by sintering scrutherite powder, a CoSi ₂ compound and a pure metal state A foil forming step of forming a foil by applying pressure to a mixed material in which Co is mixed; And a sintering step of pressurizing and sintering the foil on the casterutite powder charged for sintering, wherein the casterutite powder is sintered and at the same time a CoSi ₂ compound is formed on the surface of the casterutite thermoelectric material. It is characterized in that the metallization layer of a material in which Co in a pure metal state is mixed.

At this time, the mixing ratio of CoSi ₂ compound and Co is preferably in the range of 0.9 to 1.1: 0.9 to 1.1 in molar ratio.

The foil forming step is preferably performed at a temperature range of 900 to 1000 ° C and a pressure range of 40 to 60 MPa.

In the foil forming step, it is preferable that the CoSi ₂ compound and Co are each mixed in a powder state, and the average particle diameter of the CoSi ₂ powder and the Co powder is preferably 1/10 or less of the foil thickness.

It is preferable that the thickness of the foil formed in the foil forming step is in the range of 400 μm to 600 μm.

According to the present invention configured as described above, by using CoSi2 which can prevent the diffusion of the scutterrudite thermoelectric material, but using a mixture of Co to solve the problem of low contact resistance, by using a high temperature scutterrudite thermoelectric material Even if it is used for a long time, it can be operated stably without degrading performance due to diffusion, and there is an excellent effect of improving the efficiency of the thermoelectric module due to the low contact resistance.

Finally, the lifespan, stability and efficiency of the thermoelectric power module using the scrutherite thermoelectric material are all improved, so that the power generation efficiency of the thermoelectric power module is greatly improved in the long term.

FIG. 1 is an electron micrograph of the mixed metalizing structure formed on the surface of an n-type scrutherite thermoelectric material according to the present embodiment.
2 is a result of measuring the contact resistance between the mixed metallizing structure and the n-type scrutherite thermoelectric material according to the present embodiment.
FIG. 3 is an electron microscope photograph of a conventional Ti-based metallizing structure formed on the surface of an n-type scrutherite thermoelectric material.
4 is a result of measuring the contact resistance between the conventional Ti metallizing structure and the n-type skaterudite thermoelectric material.

With reference to the accompanying drawings will be described embodiments of the present invention;

Thermoelectric power generation module using a thermoelectric material is installed in a place where heat is generated, it is divided into a high temperature part in contact with the heat generating portion and a low temperature part that performs cooling through the cooling facility on the other side. The high temperature part is exposed to a high temperature for a long time for thermoelectric power generation, and elements are mutually diffused between the thermoelectric material and the electrode due to the high temperature, thereby deteriorating the thermoelectric properties of the thermoelectric material. For this reason, in order to ensure long-term stability at high temperature, it is preferable to metalize a material capable of sufficiently inhibiting interdiffusion between the electrode or the metallizing layer and the thermoelectric material and to apply it as a diffusion barrier layer.

The present invention is characterized by using a mixed material in which CoSi ₂ and Co are mixed as a metallizing material. As an embodiment of the present invention, a method of forming a metalizing layer in which CoSi ₂ and Co are mixed is described.

First, in the present embodiment, CoSi ₂ and Co are mixed for 1 hour in an agate mortar to prepare a mixed raw material.

CoSi ₂ (Alfa, 99% metal basis) and Co (Alfa, 99.8% metal basis), respectively, were prepared in powder form. CoSi ₂ powder had an average particle diameter of 50㎛, and the average particle size of Co powder was -100 ± 325mesh. to be. When the size of the powder is too large, CoSi ₂ and Co may not be uniformly dispersed during foil or sheet production, and thus, sufficient performance may not be obtained, and the powder may be mixed evenly as the size of the powder is reduced. However, the manufacturing cost increases. In addition, the size of the powder is also related to the thickness of the metallizing layer to be formed, and a powder having a size that can be uniformly dispersed within the thickness of the metallizing layer should be used. In view of this, it is preferable that the particle size of the CoSi ₂ powder and the particle size of the Co powder are 1/10 or less than the thickness of the metallizing layer. In the present embodiment, a powder having the same size as described above was used to form a metallizing layer having a thickness of 500 μm.

On the other hand, if the difference in the particle size of the CoSi ₂ powder and Co powder is large, it is not evenly dispersed in the metallizing layer, the particle size distribution is high, there is a problem that mechanical cracking occurs when metallized on the surface of the skutterrudite thermoelectric material, The difference between the average particle diameter of the CoSi ₂ powder and the average particle diameter of the Co powder is preferably within 20%.

In this example, CoSi ₂ and Co were mixed at a ratio of 1: 1. In the present invention, the mixing ratio of CoSi ₂ and Co is preferably in the range of 0.9 to 1.1: 0.9 to 1.1 as the molar ratio (mass). If the ratio of CoSi ₂ is too high, there is a disadvantage that the contact resistance is high, and if the ratio of Co is too high, there is a problem that the diffusion prevention efficiency is low.

In this embodiment, the mixed raw material mixed with CoSi ₂ and Co is first compressed to make a foil of the mixed material.

In general, since a method of manufacturing a scutterite thermoelectric material is often used to sinter the material powder, a method of sintering the powder together with the material constituting the metallization layer may be applied during the sintering process of the thermoelectric material. Since CoSi ₂ and Co used in the present invention have a high melting point, it is difficult to sinter together with a thermoelectric material. In this embodiment, a mixed foil is made using CoSi ₂ and Co mixed raw materials.

500 μm thick foil was prepared by compressing a mixed raw material mixed with CoSi ₂ and Co powder at a pressure of 50 MPa at a temperature of 950 ° C. The compression process for fabricating the foil is preferably carried out at a temperature range of 900 ~ 1000 ℃ and a pressure range of 40 ~ 60 MPa.

On the other hand, the metallizing layer of the present invention, in which CoSi ₂ and Co powder are mixed, has a disadvantage in that mechanical cracking occurs when metallization on the surface of the scuderudite thermoelectric material when the thickness is too thin. When the above thickness is required and the thickness is too thick, it is preferable to form it with a thickness of 600 µm or less because there is a problem that cracks due to thermal shock occur when metallization on the surface of the scuderiteite thermoelectric material. Therefore, the thickness of the foil should be selected in consideration of the thickness of the metallizing layer. In the method of the present embodiment, since the thickness of the foil hardly decreases in the process of attaching the foil, the thickness of the metallizing layer is 400 μm to 600 μm. Fabricate the foil to thickness.

The metallized layer may be formed by attaching the foil of CoSi ₂ and Co mixed by the above method to the surface of the previously prepared scutterrudite thermoelectric material ingot (lump) in various ways. In addition, in the process of sintering the powdered scutterrudite thermoelectric material to produce an ingot, the foil of the mixed material of CoSi ₂ and Co is placed on one side of the scutterrudite thermoelectric material powder to sinter the thermoelectric material powder. At the same time, the metallizing layer may be formed by hot pressing.

In the present embodiment, in the process of charging the sinter tertite thermoelectric material powder, the prepared foils are laminated and placed together, and a spark plasma sintering (SPS) process is applied to a temperature of 950 ° C. By pressure sintering at a pressure of 50 MPa for 10 minutes, Scutterrudite thermoelectric material having a metallization layer in which CoSi ₂ and Co were mixed was prepared.

FIG. 1 is an electron micrograph of a mixed metalizing structure formed on the surface of an n-type scrutherite thermoelectric material according to the present embodiment, and the EDS analysis results are also displayed.

It can be seen that the metallization layer in which CoSi ₂ and Co are mixed on the left has a structure in which dark and light Co are mixed. In addition, as can be seen in the EDS analysis, unlike the metallization layer made of Ti, it can be seen that diffusion did not substantially progress between the scudrudite thermoelectric material and the metallization layer, and no intermetallic compound was formed.

2 is a result of measuring the contact resistance between the mixed metallizing structure and the n-type scrutherite thermoelectric material according to the present embodiment.

As a result of measuring the contact resistance at the interface where the metallized layer mixed with CoSi ₂ and Co and the n-type scriberite contacted, the contact resistance was lower than that when the metallized layer made of Ti was applied.

As shown in FIG. 1, the contact resistance between the metallizing layer and the scrutherite thermoelectric material is very small, without causing an element diffusion problem between the metallizing layer and the scrutherite thermoelectric material. By doing so, it can be seen that in the case of applying the metallizing layer of the present embodiment, stability will be exhibited even in long-term use with efficiency improvement due to low contact resistance.

While the present invention has been described through the preferred embodiments, the above-described embodiments are merely illustrative of the technical idea of the present invention, and various changes are possible within the scope without departing from the technical idea of the present invention. Those of ordinary skill will understand. Therefore, the protection scope of the present invention should be interpreted not by the specific embodiments, but by the matters described in the claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

Claims (26)

As a metallizing structure formed on the surface of a scarteriteite thermoelectric material,
A mixed metallizing structure for a scutterrudite thermoelectric material, characterized in that the CoSi ₂ compound and pure metal Co are simply mixed in a molar ratio of 0.9 to 1.1: 0.9 to 1.1.
delete The method according to claim 1,
Said metallizing structure is a mixed metallizing structure for scutterrudite thermoelectric material, characterized in that the foil formed by applying pressure to a mixed material of CoSi ₂ compound and Co in the pure metal state.
The method according to claim 3,
A mixed metallizing structure for a scarterudite thermoelectric material, characterized in that the CoSi ₂ compound and Co are each mixed in a powder state.
The method according to claim 4,
A mixed metallizing structure for a scarterudite thermoelectric material, wherein an average particle diameter of the CoSi ₂ powder and the Co powder is 1/10 or less of the foil thickness.
As a sciderrudite thermoelectric material having a metallization layer formed on its surface,
The metallizing scutterrudite thermoelectric material, characterized in that the metallizing layer is a material in which the CoSi ₂ compound and the pure metal Co are simply mixed at a molar ratio in the range of 0.9 to 1.1: 0.9 to 1.1.
delete The method according to claim 6,
And the metallizing layer is a foil formed by applying pressure to a mixed material in which CoSi ₂ compound and Co in a pure metal state are mixed.
The method according to claim 8,
Scutterrudite thermoelectric material, characterized in that the CoSi ₂ compound and Co each mixed in a powder state.
The method according to claim 9,
Scutterrudite thermoelectric material, characterized in that the average particle diameter of CoSi ₂ powder and Co powder is 1/10 or less of the foil thickness.
The method according to claim 6,
The metallized scutterrudite thermoelectric material, characterized in that the thickness of the metallizing layer is in the range of 400㎛ ~ 600㎛.
As a metallizing method of forming a metallizing layer on the surface of a scarrudite thermoelectric material,
Scutterrudite thermoelectric, characterized in that to form a metallization layer of a simple mixed material CoSi ₂ compound and pure metal Co in the molar ratio of 0.9 to 1.1: 0.9 to 1.1 on the surface of the scutterrudite thermoelectric material Metallizing method of the material.
delete Claim 14 has been abandoned upon payment of a set-up fee. The method according to claim 12,
After forming a foil by applying pressure to a mixed material in which a CoSi ₂ compound and Co in a pure metal state are mixed, the foil is adhered to the surface of the scarterudite thermoelectric material. Metallizing method.
Claim 15 was abandoned upon payment of a set-up fee. The method according to claim 14,
A method of metallizing a scutterite thermoelectric material, characterized in that the step of forming a foil by applying pressure to a mixed material of CoSi ₂ compound and Co in the pure metal state is carried out in the temperature range of 900 ~ 1000 ℃.
Claim 16 was abandoned upon payment of a set-up fee. The method according to claim 14,
The method of forming a foil by applying pressure to a mixed material in which a CoSi ₂ compound and Co in a pure metal state is mixed is carried out in a pressure range of 40 to 60 MPa.
Claim 17 was abandoned upon payment of a set-up fee. The method according to claim 14,
CoSi ₂ compound and hibiscus Teruel metallizing method of die bit thermoelectric material that in a process for the Co in the pure metal state by applying pressure on a mixed material mixture to form a foil, characterized in that the mixture to CoSi ₂ compound and a Co powder state, respectively.
Claim 18 has been abandoned upon payment of a set-up fee. The method according to claim 17,
A metallizing method for a scutterrudite thermoelectric material, characterized in that the average particle diameter of CoSi ₂ powder and Co powder is 1/10 or less of the thickness of the foil.
Claim 19 was abandoned upon payment of a set-up fee. The method according to claim 14,
The thickness of the foil is 400㎛ ~ 600㎛ metallizing method of thermoelectric material, characterized in that the thermoelectric material.
In the method of sintering the scrutherite powder to produce a scrutherite thermoelectric material,
A foil forming step of applying a pressure to a mixed material in which the CoSi ₂ compound and the pure metal Co are simply mixed at a molar ratio in a range of 0.9 to 1.1: 0.9 to 1.1 to form a foil; And
A sintering step of pressure sintering in a state in which the foil is placed on the charged scudrudite powder for sintering,
The metallizing scutterrudite thermoelectric, characterized in that the metallization layer of the CoSi ₂ compound and the pure metal Co is formed on the surface of the scrudderite powder at the same time as the sinter territe powder is sintered. Method of manufacturing the material.
delete Claim 22 was abandoned upon payment of a set-up fee. The method of claim 20,
The foil forming step is a method of manufacturing a metallized scutterrudite thermoelectric material, characterized in that carried out at a temperature range of 900 ~ 1000 ℃.
Claim 23 was abandoned upon payment of a set-up fee. The method of claim 20,
The foil forming step is a method of manufacturing a metallized scutterrudite thermoelectric material, characterized in that carried out in a pressure range of 40 ~ 60 MPa.
Claim 24 was abandoned when the set registration fee was paid. The method of claim 20,
In the foil forming step, the CoSi ₂ compound and Co is a method for producing a scutterrudite thermoelectric material, characterized in that each of the powder is mixed.
Claim 25 was abandoned upon payment of a set-up fee. The method of claim 24,
A method for producing a scutterrudite thermoelectric material, characterized in that the average particle diameter of CoSi ₂ powder and Co powder is 1/10 or less of the thickness of the foil.
Claim 26 was abandoned upon payment of a set-up fee. The method of claim 20,
The thickness of the foil formed in the foil forming step is 400㎛ ~ 600㎛ manufacturing method of the metallized scutterrudite thermoelectric material characterized in that the range.

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