KR101323097B1 - Thermoelectric device with copper electrode and manufacturing method of the same - Google Patents

Abstract

The present invention has a structure in which a first metal plate, a second metal plate, and a copper (Cu) electrode are sequentially stacked and bonded to first and second surfaces of a CoSb ₃ thermoelectric semiconductor, and the first metal plate is made of aluminum. It is made of a metal or aluminum alloy, the second metal plate is at least one metal selected from titanium (Ti), zirconium (Zr) and tungsten or at least one metal selected from titanium (Ti), zirconium (Zr) and tungsten It relates to a thermoelectric element made of an alloy containing and a method of manufacturing the same. According to the present invention, there are almost no defects such as cracks or voids at the interface between the thermoelectric semiconductor and the electrode, and the interface is well matched, which is excellent in the stiffness against tensile force, and is lifted at the interface between the thermoelectric semiconductor and the electrode. Since mismatch of is small and interface separation does not occur, reliability at high temperature is high.

Description

Thermoelectric device with a copper electrode and a method of manufacturing the same {Thermoelectric device with copper electrode and manufacturing method of the same}

The present invention relates to an electrode for a thermoelectric element and a method of manufacturing the same, and more particularly, there is almost no defect such as cracks or voids at the interface between the thermoelectric semiconductor and the electrode, and the interface is well matched, so that the rigidity against tensile force is excellent. The present invention relates to a thermoelectric device having high reliability at a high temperature and a method of manufacturing the same because excellent misalignment such as lifting at the interface between the thermoelectric semiconductor and the electrode is not so small that interface separation does not occur.

Thermoelectric phenomena were first discovered by German physicist TJSeebeck. In a circuit consisting of two different conductors, a current or voltage is generated by applying different temperatures to the contacts between conductors. The heat flow from place to cold creates current. This phenomenon is called the Seebeck Effect.

Jean-Charles Atanas Peltier of France found another important thermoelectric phenomenon: when direct current flows through a circuit of different conductors, one side of the junction between the different conductors is heated, depending on the direction of the current, The other is the phenomenon of cooling. This is called the Peltier Effect.

William Thompson found that the existing Peltier and Seebeck effects were related and summarized the relationship between them.In this process, if a potential difference is applied at the ends of a single conductor rod, heat is absorbed at both ends of the conductor. The Thomson Effect was found to occur.

Thermoelectric elements, such as thermoelectric modules, peltier elements, thermoelectric coolers (TEC), and thermoelectric modules (TEM), are known as small heat pumps (heat pumps) that absorb heat from low-temperature heat sources. To heat the heat source of high temperature). When a direct current voltage is applied across the thermoelectric element, heat moves from the heat absorbing portion to the heat generating portion. Thus, as time passes, the temperature of the heat absorbing portion decreases and the heat generating portion increases temperature. At this time, if the polarity of the applied voltage is changed, the heat absorbing portion and the heat generating portion are changed to each other, and the flow of heat is reversed.

In general thermoelectric elements, a pair of N-type and P-type thermoconductor elements is the basic unit, and in the general model, 127 pairs of elements are used. When a direct current (DC) voltage is applied at both ends, heat moves in accordance with the flow of electrons in the N type and holes in the P type, thereby lowering the temperature of the heat absorbing portion. Since there is a difference in potential energy of electrons in a metal, in order to move electrons from a metal having a low potential energy to a metal having a high state, energy must be obtained from the outside, so that thermal energy is desorbed at the contact point and vice versa. It is a principle. This endotherm (cooling) is proportional to the flow of current and the number of thermoelectric couples (N, P type pair).

Currently used energy is fossil fuel, petroleum, nuclear power, etc. is used as a source of electric energy, but it is necessary to develop alternative energy due to exhaustion of resource energy. In addition, although most of the generator is converted to electrical energy through mechanical energy, such as energy conversion efficiency is difficult to exceed a certain limit (for example, 40%). Recently, thermoelectric power generation technology having advantages such as thermoelectric power generation using thermoelectric elements and recycling of waste thermal energy using thermoelectric elements has emerged as a new field of interest.

However, the thermoelectric device exhibits a low utilization rate compared to the use potential due to low thermoelectric material (thermoelectric material) properties, and has a problem in that an interface separation phenomenon occurs due to mismatch at high temperature due to a difference in thermal expansion coefficient between the electrode and the thermoelectric semiconductor.

The problem to be solved by the present invention is almost no defects such as cracks or voids at the interface between the thermoelectric semiconductor and the electrode, and the interface is well matched and excellent in the rigidity against the tensile force, it is excited at the interface between the thermal semiconductor and the electrode The present invention provides a thermoelectric device having high reliability at a high temperature and a method of manufacturing the same, because interface misalignment is not generated due to a small mismatch.

The present invention has a structure in which a first metal plate, a second metal plate, and a copper (Cu) electrode are sequentially stacked and bonded to first and second surfaces of a CoSb ₃ thermoelectric semiconductor, and the first metal plate is made of aluminum. It is made of a metal or aluminum alloy, the second metal plate is at least one metal selected from titanium (Ti), zirconium (Zr) and tungsten or at least one metal selected from titanium (Ti), zirconium (Zr) and tungsten It provides a thermoelectric element made of an alloy containing.

The first metal plate, which serves to enhance the bonding force between the thermoconductor and the second metal plate, has a thickness of 10 μm to 1 mm, and serves to prevent copper (Cu) from diffusing into the thermoconductor. The second metal plate is preferably made of 10㎛ ~ 1mm thickness.

In addition, the present invention, (a) preparing a CoSb ₃ thermoelectric semiconductor, a first metal plate, a second metal plate and a copper (Cu) electrode, (b) the thermoelectric semiconductor, the first metal plate, the first 2) the metal plate and the copper (Cu) electrode is brought into contact with each other to be in contact with each other to fill the mold and set in the chamber of the discharge plasma sintering apparatus, (c) evacuating the inside of the chamber to reduce the pressure, A target lower than the melting temperature of the thermoelectric semiconductor, the first metal, the second metal, and the copper (Cu) by applying a direct current pulse while pressing the copper (Cu) electrode, the second metal plate, the first metal plate, and the thermoelectric semiconductor. And (d) pressurizing the copper (Cu) electrode, the second metal plate, the first metal plate, and the thermoconductor at the junction temperature. 2 Joining the inner plate, the second metal plate and the first metal plate, the first metal plate and the thermoelectric semiconductor, and (e) cooling the temperature of the chamber to obtain a thermoelectric element. The first metal plate is made of an aluminum metal or an aluminum alloy, and the second metal plate is made of at least one metal selected from titanium (Ti), zirconium (Zr) and tungsten or from among titanium (Ti), zirconium (Zr) and tungsten. Provided is a method of manufacturing a thermoelectric element made of an alloy including at least one selected metal.

Preparation of the thermoelectric semiconductors, and the while filling the CoSb ₃ powder into a mold and pressure was evacuated steps and, within the chamber to set in a chamber of a spark plasma sintering apparatus, and pressing the CoSb ₃ powder DC pulse is CoSb ₃ raising to the sintering temperature to a low target than the melting temperature of the powder and the CoSb ₃ thermoelectric semiconductor by cooling the stage and the temperature of the chamber to the discharge plasma sintering of the CoSb ₃ powder and pressing the CoSb ₃ powder in the sintering temperature And obtaining.

Pressing of the copper (Cu) electrode, the second metal plate, the first metal plate, and the thermoelectric semiconductor is preferably performed in one axial direction, and the DC pulse is preferably applied in a direction parallel to the pressing direction.

The junction temperature at which the copper (Cu) electrode, the second metal plate, the second metal plate and the first metal plate, the first metal plate and the thermoelectric semiconductor are bonded is 500 to 580 ° C., and at the junction temperature It is preferable to hold | maintain and join for 5 to 30 minutes.

In the step (c), the pressure to be applied is in the range of 10 to 60 MPa, and the inside of the chamber is decompressed in the range of 1.0 × 10 ^{-7 to} 9.0 × 10 ^-2 torr, and the DC pulse is applied in the range of 0.1 to 2000 A. It is preferable.

The first metal plate, which serves to improve the bonding force between the thermoelectric semiconductor and the second metal plate, uses a plate having a thickness of 10 μm to 1 mm, and prevents copper (Cu) from diffusing into the thermoelectric semiconductor. As the second metal plate, which serves to play a role, it is preferable to use a plate having a thickness of 10 μm to 1 mm.

According to the thermoelectric device of the present invention, a copper (Cu) electrode, a second metal plate, a first metal plate, a thermoelectric semiconductor, a first metal plate, a second metal plate, and a copper (Cu) electrode sequentially form a continuous structure. Each interface has almost no defects such as cracks or voids, and the interface is well matched to provide excellent rigidity for tensile strength. There is an advantage in that reliability at high temperature is small because mismatches such as excitation at the interface of the thermoelectric semiconductor and the electrode are small.

Since the discharge plasma sintering method is used as the manufacturing method of the thermoelectric element, rapid temperature rising is possible, thereby suppressing the growth of particles, obtaining a compact sintered body or a joined body in a short time, and sintering or joining in a short time.

According to the method of manufacturing a thermoelectric device manufactured according to the present invention, a high density thermoelectric semiconductor having a very small gap between particles and almost no pores can be obtained.

1 is a view schematically showing a discharge plasma sintering apparatus.
2 is an exploded perspective view schematically illustrating a thermoelectric device.
3 is a scanning electron microscope (SEM) photograph showing an interface between a copper (Cu) electrode and a titanium foil of a thermoelectric device manufactured according to Example 2. FIG.
4 is a scanning electron microscope (SEM) photograph showing the interface between a titanium foil, an aluminum alloy foil, and a CoSb3 thermoelectric semiconductor.
5A to 5C are scanning electron microscope (SEM) photographs showing an interface between a titanium foil and an aluminum alloy foil of a thermoelectric device manufactured according to Example 2;
6A to 6C are scanning electron microscope (SEM) photographs showing an interface between an aluminum alloy foil and a CoSb ₃ thermoconductor of a thermoelectric device according to Example 2;
7 is an EDS analysis (Energy Dispersive Spectroscopy Analysis) photograph of a thermoelectric device manufactured according to Example 2. FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, it should be understood that the following embodiments are provided so that those skilled in the art will be able to fully understand the present invention, and that various modifications may be made without departing from the scope of the present invention. It is not. Wherein like reference numerals refer to like elements throughout.

According to the present invention, when one side generates heat and the other side absorbs heat when a direct current is applied between both ends of a material and a thermoelectric power generation using a voltage generated by a Seebeck effect when a temperature difference between both ends of a material is given. A thermoelectric device capable of directly converting thermal and electrical energy such as thermoelectric cooling using a Peltier effect and a method of manufacturing the same are provided.

The thermoelectric power generation using the Seebeck effect is not only reliable, high output stability, but also does not generate carbon dioxide (CO ₂ ), so it is eco-friendly, and thermoelectric cooling using Peltier effect enables precise temperature control and fast response speed. Not only does it make noise but it does not emit freon gas, so it is environmentally friendly.

However, despite these advantages, thermoelectric devices exhibit low utilization compared to their potential for use due to their low thermoelectric material (thermoelectric material) properties.

A parameter for evaluating the performance of the thermoelectric material is required, which can be expressed as a figure of merit Z (Figure of Merit), and the figure of merit Z can be expressed by Equation 1 below.

In Equation 1, α is a Seebeck coefficient, ρ is an electrical resistivity, and K is a thermal conductivity.

As shown in Equation 1, the characteristics of the thermoelectric material are excellent as the Seebeck coefficient is high, that is, the output voltage is large, the electrical resistivity is low, and the thermal conductivity is low. In general, the figure of merit Z is used by multiplying this value by the temperature T, rather than using it directly, to create a dimensionless parameter ZT.

In the thermoelectric device including the copper electrode according to the preferred embodiment of the present invention, the first metal plate, the second metal plate, and the copper (Cu) electrode are sequentially stacked on the first and second surfaces of the CoSb ₃ thermoelectric semiconductor. It has a bonded structure, the first metal plate is made of aluminum metal or aluminum alloy, the second metal plate is at least one metal or titanium (Ti) selected from titanium (Ti), zirconium (Zr) and tungsten, It consists of an alloy containing at least one metal selected from zirconium (Zr) and tungsten.

The thermoelectric device including the copper electrode according to the preferred embodiment of the present invention, a copper (Cu) electrode, the second metal plate, the first metal plate, the thermoelectric semiconductor, the first metal plate, the second metal plate and copper (Cu) The electrodes form a continuous structure, and each interface has almost no defects such as cracks or voids, and the interface is well matched, so it has excellent rigidity against tensile force and is excited at the interface with the thermoelectric semiconductor even at high temperatures. It is highly reliable at high temperature since the inconsistency, such as a small or less, is small and no interface separation occurs.

Hereinafter, a method of manufacturing a thermoelectric device according to a preferred embodiment of the present invention will be described.

First, a method of manufacturing a thermoelectric semiconductor will be described.

CoSb ₃ powder is sintered using the spark plasma sintering (SPS) method. 1 is a view schematically showing a discharge plasma sintering apparatus.

The discharge plasma sintering (SPS) method is a technique using plasma as a technique capable of synthesizing or sintering a desired material in a short time. In the discharge plasma sintering (SPS) method, the electrical energy of a pulse is directly injected into a gap between particles of a green compact, and high energy of a high-temperature plasma (discharge plasma) generated by a spark discharge in an instant is applied to thermal diffusion, action of an electric field, etc. It is an effective application process. The sintering temperature can be controlled from low temperature to 2000 ℃ or higher by the generated plasma, and it is a method that can be sintered or bonded within a short time including the temperature raising and holding time in the temperature range about 200 ~ 500 ℃ lower than other sintering processes. . In addition, since the rapid temperature rise is possible, the growth of particles can be suppressed, the bonding can be performed in a short time, and the sintered material can be easily sintered.

The method of sintering CoSb ₃ powder using the discharge plasma sintering (SPS) method will be described in more detail.

The CoSb ₃ powder 120 was charged into the mold 110 provided in the chamber 100, and a DC pulse current was applied in a direction parallel to the pressing direction while depressurizing the inside of the chamber 100 and pressing the punch 130. Sinter. Due to the increase in temperature due to the pressurization and high current application during sintering, a reaction occurs between the powders to obtain a CoSb ₃ sintered body.

The mold 110 filled with the CoSb ₃ powder is set in the chamber 100 of the discharge plasma sintering apparatus, and the plasma is gradually discharged while applying a DC pulse using a pulsed DC generator 140 while pressing after depressurization. Proceed with sintering. The reduced pressure is preferably about 1.0 × 10 ⁻⁷ to 9.0 × 10 ⁻² torr. In order to remove the impurity gas present in the chamber 100 and to reduce the pressure, a rotary pump (not shown) is operated to evacuate until it is in a vacuum state (for example, about 1.0 × 10 ⁻⁷ to 9.0 × 10 ⁻² torr). do. The DC pulse is preferably applied in the range of 0.1 ~ 2000A.

When a DC current is applied suddenly when a DC pulse is applied, it is difficult to control the sintering temperature because the temperature control is difficult. The temperature increase rate is preferably about 10 ~ 300 ℃ / min, when the temperature increase rate exceeds 300 ℃ / min it may be difficult to control the sintering temperature, if less than 10 ℃ / min takes a long time to reduce productivity There are disadvantages.

The mold 110 may be provided in a cylinder or a prismatic shape, and after the CoSb ₃ powder 120 is charged into the mold 110, compression is performed using the punch 130. The mold 110 is preferably made of a graphite material having a high hardness and a high melting point.

The pressure applied to the CoSb ₃ powder (pressure that is compressed by the mold), are of desired high density because the air gap lot between together preferably about 10 ~ 60MPa, when the pressing pressure is less than 10MPa, the CoSb ₃ powder CoSb ₃ sintered body It is difficult to obtain and high current must be applied for sintering, which can lead to high temperature rise.If the pressurization pressure exceeds 60MPa, further effect cannot be expected. The cost may increase.

The sintering temperature of the target (e.g., the 500 ~ 600 ℃ CoSb a temperature lower than the melting temperature of the powder ₃₎ rises to maintain a certain amount of time (e.g., 5-30 minutes) to sinter the powder CoSb _3. The sintering temperature is preferably about 500 ~ 600 ℃ in consideration of the diffusion of particles, necking (necking) between the particles, if the sintering temperature is too high, mechanical properties may be reduced due to excessive growth of the particles, If the sintering temperature is too low, it is preferable to sinter at the sintering temperature in the above range because the characteristics of the sintered body may be poor due to incomplete sintering. According to the sintering temperature, there are differences in the microstructure, particle size, etc. of the sintered body, because the surface diffusion is dominant when the sintering temperature is low, but the lattice diffusion and grain boundary diffusion are progressed when the sintering temperature is high. It is preferable that the sintering time is about 5 to 30 minutes. If the sintering time is too long, energy consumption is high, so it is not economical, and it is difficult to expect any further sintering effect and the size of the sintered body becomes large. If the time is small, the characteristics of the sintered body may be poor due to incomplete sintering. Even during sintering, the pressure inside the chamber is preferably kept constant at a reduced pressure of about 1.0 × 10 ⁻⁷ to 9.0 × 10 ⁻² torr. The pressure applied to the CoSb ₃ powder during sintering is preferably maintained at about 10 to 60 MPa. If the pressurization pressure is too small, it is difficult to obtain a desired high density CoSb ₃ sintered body, and if the pressurization pressure is too large, the sintering process is completed. Cracks may occur in the sintered body.

After the sintering process is performed, cooling is performed to unload the CoSb ₃ sintered body. It is preferable that the pressure inside the chamber and the pressure to be compressed by the mold are kept constant during cooling.

The thermoconductor prepared according to the preferred embodiment of the present invention is composed of a high density CoSb ₃ sintered body having very close spacing between particles and little pores.

The thermoelectric semiconductor is bonded to the electrode by the method described below to form an N type or P type thermoelectric element.

CoSb ₃ to form electrode The first metal plate 20, the second metal plate 30, and the copper (Cu) electrode 40 are sequentially stacked and bonded to the surface of the thermoelectric semiconductor 10. For example, the first metal plate 20, the second metal plate 30, and the copper (Cu) electrode 40 may be sequentially stacked on both surfaces of the thermoelectric semiconductor to form electrodes as shown in FIG. 2. .

It is preferable that the 1st metal plate 20 consists of aluminum or an aluminum alloy. Since the first metal plate 20 is disposed between the thermoelectric semiconductor 10 and the second metal plate 30, the bonding force between the thermoelectric semiconductor 10 and the second metal plate 30 may be enhanced. In consideration of enhancing the bonding force between the thermoelectric semiconductor 10 and the second metal plate 30, the first metal plate 20 preferably has a thickness of 10 μm to 1 mm.

The second metal plate 30 is made of an alloy containing at least one metal selected from titanium (Ti), zirconium (Zr) and tungsten or at least one metal selected from titanium (Ti), zirconium (Zr) and tungsten. desirable. The second metal plate 30 serves as a buffer layer between copper (Cu), which is an electrode for thermoelectric elements, and the thermoelectric semiconductor 10, and serves to prevent copper (Cu) from diffusing into the thermoelectric semiconductor. , And also serves to mitigate thermal stress between the copper (Cu) electrode 40 and the thermoelectric semiconductor 10. In consideration of preventing the diffusion of copper (Cu) into the thermoelectric semiconductor, the second metal plate 30 preferably has a thickness of 10 μm to 1 mm.

The bonding may use the above-described discharge plasma sintering (SPS) apparatus. The first metal plate 20, the second metal plate 30, and the copper (Cu) electrode 40 are sequentially stacked on the surface of the thermoconductor 10 to form the electrode, and the surfaces to be joined are brought into contact with each other. Charged into the mold 110 provided in the chamber 100, while decompressing the inside of the chamber 100 and pressurized by the punch 130, a DC pulse current is applied in a direction parallel to the pressing direction and bonded. Due to the increase in temperature due to the pressurization and the high current applied during the bonding, a reaction occurs between the copper (Cu) electrode 40, the second metal plate 30, the first metal plate 20, and the thermoelectric semiconductor 10. You can get it.

This will be described in more detail. The first metal plate 20, the second metal plate 30, and the copper (Cu) electrode 40 are sequentially stacked on the surface of the thermoelectric semiconductor 10 so that the surfaces to be joined are brought into contact with each other so as to contact each other. Is filled in, the mold 110 is set in the chamber 100 of the discharge plasma sintering apparatus, and a DC pulse is gradually applied using a DC pulse generator 140 while depressurizing and pressurizing. The reduced pressure is preferably about 1.0 × 10 ^{−7 to} 9.0 × 10 ⁻² torr. In order to remove the impurity gas present in the chamber 100 and to reduce the pressure, a rotary pump (not shown) is operated to evacuate until it is in a vacuum state (for example, about 1.0 × 10 ^{−7 to} 9.0 × 10 ⁻² torr). do. The direct current pulse is preferably applied in a range of 0.1 to 2000 A. When the current is rapidly applied when applying the DC pulse, it may be difficult to control the temperature, so it is preferable to raise the same width for a predetermined time. It is preferable that the temperature increase rate is about 10 to 300 ° C./min, and when the temperature increase rate exceeds 300 ° C./min, it may be difficult to control the temperature. There is this. The mold 110 is preferably made of a graphite material having a high hardness and a high melting point. The pressure (pressure compressed by the mold) applied to the copper (Cu) electrode, the second metal plate 30 and the first metal plate 20 is preferably about 10 to 60 MPa, but the pressurization pressure is less than 10 MPa. The interface between the copper (Cu) electrode and the second metal plate 30, the interface between the second metal plate 30 and the first metal plate 20 or the first metal plate 20 and the thermoconductor 10. Since there are many voids at the interface between them, it is difficult to obtain the desired high adhesiveness, and high current must be applied for the adhesion, which can lead to high temperature rise. The addition of designs such as molds, hydraulics, etc., can increase equipment fabrication costs. When it rises to target temperature (for example, 500-580 degreeC which is lower than the melting temperature of thermoelectric semiconductor, a 1st metal, a 2nd metal, and copper (Cu)), it maintains a fixed time (for example, 5 to 30 minutes). The thermoelectric semiconductor 10, the first metal plate 20, the second metal plate 30, and the copper (Cu) electrode 40 are bonded to each other. It is preferable that the junction temperature is about 500 to 580 ° C. If the junction temperature is too high, the second metal plate 30 may not serve as a buffer layer due to excessive diffusion, and incomplete if the junction temperature is too low. It is preferable to bond at a temperature in the above range because the properties of the bonding interface may not be good due to the bonding. According to the junction temperature, there is a difference in the microstructure of the interface, etc., because the surface diffusion is dominant when the junction temperature is low, while the lattice diffusion and grain boundary diffusion proceeds when the junction temperature is high. It is preferable that the joining time is about 5 to 30 minutes. If the joining time is too long, energy consumption is too high, so it is not economical and it is difficult to expect further joining effects. Due to this, the properties of the bonding interface may be poor. Even during bonding, the pressure inside the chamber 100 is preferably kept constant at a reduced pressure of about 1.0 × 10 ^{−7 to} 9.0 × 10 ⁻² torr. The pressure applied to the copper (Cu) electrode, the second metal plate 30 and the first metal plate 20 at the time of bonding is preferably kept constant at about 10 to 60 MPa.

After the joining process is performed, cooling is unloaded. It is preferable that the pressure inside the chamber and the pressure to be compressed by the mold are kept constant during cooling.

The invention is described in more detail with reference to the following examples, which do not limit the invention.

≪ Example 1 >

Spherical CoSb ₃ powder having an average particle diameter of 0.5 mu m was prepared.

CoSb ₃ powder was sintered using the discharge plasma sintering apparatus shown in FIG. 1.

Referring to the sintering process using the discharge plasma sintering (SPS) method, the CoSb ₃ powder is charged into a mold provided in the chamber, and the inside of the chamber is depressurized and pressurized in one axis to apply a DC pulse current in a direction parallel to the pressing direction. Authorized. More specifically, a mold filled with CoSb ₃ powder was set in a chamber of a discharge plasma sintering apparatus, and discharge plasma sintering was performed while gradually applying a DC pulse while pressing after depressurization. The decompression was set to about 5.0 × 10 ⁻² torr. The mold was made of graphite graphite, charged with CoSb ₃ powder, and then subjected to uniaxial compression, and the pressure applied to the CoSb ₃ powder (pressure compressed by the mold) was about 40 MPa. The DC pulse was applied to 1 ~ 1000 A, the temperature increase rate was set to about 100 ℃ / min. When it rose to the target sintering temperature of 580 ° C, the CoSb ₃ powder was sintered for 10 minutes. During the sintering, the pressure inside the chamber was kept constant at a reduced pressure of about 5.0 × 10 ⁻² torr, and the pressure applied to the CoSb ₃ powder during sintering was kept constant at about 40 MPa.

The reaction occurred between the powders due to the increase in temperature due to the pressurization and the application of a high current during sintering, thereby obtaining a CoSb ₃ sintered body. After performing the sintering process, cooling was performed to unload the CoSb ₃ sintered body to obtain a cylindrical thermoelectric semiconductor. Even during cooling, the pressure inside the chamber and the pressure compressed by the mold were kept constant.

<Example 2>

As shown in FIG. 2, aluminum alloy foil, which is a disc-shaped first metal plate, titanium (Ti) foil, and a disc-shaped copper (Cu) electrode, are formed on both surfaces of the thermoelectric semiconductor. Laminated and bonded sequentially. The aluminum alloy foil was used having a thickness of 100㎛, the titanium foil was used having a thickness of 100㎛.

The aluminum alloy foils used were two types and the components other than aluminum are shown in Table 1 below.

Aluminum alloy
Composition Si Fe Cu Mn Mg Zn 3003 0.6 0.7 0.05 to 0.2 1 to 1.5 - 0.1 5052 0.25 0.4 0.1 0.1 2.2 to 2.8 0.1

The bonding was performed using the discharge plasma sintering (SPS) apparatus described above. The thermoelectric semiconductor, the aluminum alloy foil, the titanium (Ti) foil, and the copper (Cu) electrode are brought into contact with each other to be in contact with each other, and charged into a mold provided in the chamber 100, and the inside of the chamber is decompressed and punched in one axis. While pressurizing, a DC pulse current was applied in the direction parallel to the pressing direction to bond.

More specifically, a mold filled in contact with the surfaces to which the thermoelectric semiconductor, the aluminum alloy foil, the titanium (Ti) foil, and the copper (Cu) electrode are to be contacted with each other is set in the chamber of the discharge plasma sintering apparatus, and pressurized after decompression. DC pulse was slowly applied. The decompression was set to about 5.0 × 10 ⁻² torr. The mold is made of a graphite graphite material, the copper (Cu) electrode, aluminum alloy foil, titanium (Ti) foil, thermoelectric semiconductor, aluminum alloy foil, titanium (Ti) foil and copper (Cu) electrode in the mold After charging sequentially, uniaxial compression was performed, and the pressure applied (pressure compressed by the mold) was about 40 MPa. The DC pulse was applied at 1 to 1000 A, and the temperature increase rate was set at about 100 ° C / min. When it rose to the target joining temperature of 500-580 degreeC, it hold | maintained for 10 minutes and made it join. The pressure inside the chamber was kept constant at a reduced pressure of about 5.0 × 10 ⁻² torr during the bonding, and the pressure applied during the bonding was kept constant at about 40 MPa.

Due to the temperature rise due to pressurization and high current application during bonding, reaction occurs at the interface between the copper (Cu) electrode and the titanium foil, at the interface between the titanium foil and the aluminum alloy foil, and at the interface between the aluminum alloy foil and the thermoelectric semiconductor. After the bonding, the sintering process was performed, the mixture was cooled and unloaded to obtain a cylindrical thermoelectric element. Even during cooling, the pressure inside the chamber and the pressure compressed by the mold were kept constant.

3 is a scanning electron microscope (SEM) photograph showing an interface between a copper (Cu) electrode and a titanium foil of a thermoelectric device manufactured according to Example 2. FIG.

Referring to FIG. 3, cracks did not occur at the interface between the copper (Cu) electrode and the titanium foil, and the bonding was well performed.

4 is a scanning electron microscope (SEM) photograph showing the interface between a titanium foil, an aluminum alloy foil, and a CoSb ₃ thermoelectric semiconductor. 4 shows a case where a titanium foil, an aluminum alloy foil, and a CoSb3 thermoelectric semiconductor were bonded at 550 ° C. for 10 minutes using a discharge plasma sintering (SPS) apparatus.

Referring to FIG. 4, it can be seen that cracks did not occur at the interface between the titanium foil and the aluminum alloy foil, and the interface between the aluminum alloy foil and the CoSb ₃ thermoelectric semiconductor and bonding was well performed.

5A to 5C are scanning electron microscope (SEM) photographs showing an interface between a titanium foil and an aluminum alloy foil of a thermoelectric device manufactured according to Example 2; Figure 5a shows a case where the bonding for 10 minutes at 500 ℃ using a discharge plasma sintering (SPS) apparatus, Figure 5b shows a case of bonding for 10 minutes at 550 ℃, Figure 5c at 10 minutes at 580 ℃ Shows the case of splicing.

5a to 5c, it can be seen that cracks did not occur at the interface between the titanium foil and the aluminum alloy foil, and bonding was performed well.

6A to 6C are scanning electron microscope (SEM) photographs showing an interface between an aluminum alloy foil and a CoSb ₃ thermoconductor of a thermoelectric device according to Example 2; Figure 6a shows a case where the bonding for 10 minutes at 500 ℃ using a discharge plasma sintering (SPS) apparatus, Figure 6b shows a case of bonding for 10 minutes at 550 ℃, Figure 6c is 10 minutes at 580 ℃ Shows the case of splicing.

6A to 6C, it can be seen that cracks did not occur at the interface between the aluminum alloy foil and the CoSb ₃ thermoconductor and bonding was well performed.

As can be seen in Figures 5a to 6c showed a smooth joint surface without defects at the interface at 500 ~ 580 ℃ temperature conditions. Secondary phases were observed at the interface between aluminum alloy foil and titanium foil and at the interface between CoSb ₃ thermoconductor and aluminum alloy foil at a temperature of 580 ° C.

7 is an EDS analysis (Energy Dispersive Spectroscopy Analysis) photograph of a thermoelectric device manufactured according to Example 2. FIG. In FIG. 7, the region indicated by '①' is a CoSb ₃ thermoelectric semiconductor, the region indicated by '②' is an aluminum alloy foil, and the region indicated by '③' is a titanium foil. The results of component analysis in each region shown in FIG. 7 are shown in Table 2 below.

domain ingredient weight% atom% ① Sb 86.75 76.02 Co 13.25 23.98 ② Al 43.69 75.45 Sb 44.21 15.68 Co 12.10 8.87 ③ Ti 100 100

As shown in FIG. 7, it can be seen that there is no crack at the interface between the thermoelectric semiconductor and the aluminum alloy foil, and the interface between the aluminum alloy foil and the titanium foil, and the bonding is performed well.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, This is possible.

100: chamber 110: mold
120: Powder 130: Punch
140: DC pulse oscillator

Claims (8)

A first metal plate, a second metal plate, and a copper (Cu) electrode are sequentially stacked and bonded to the first and second surfaces of the CoSb ₃ thermoelectric semiconductor,
The first metal plate is made of aluminum metal or aluminum alloy,
The second metal plate is made of an alloy containing at least one metal selected from titanium (Ti), zirconium (Zr) and tungsten or at least one metal selected from titanium (Ti), zirconium (Zr) and tungsten. Thermoelectric element.
The method of claim 1, wherein the first metal plate which serves to improve the bonding force between the thermoelectric semiconductor and the second metal plate is made of 10㎛ ~ 1㎜ thickness, copper (Cu) diffused into the thermoelectric semiconductor The second metal plate that serves to prevent being made is a thermoelectric element, characterized in that consisting of 10㎛ ~ 1㎜ thickness.
(a) preparing a CoSb ₃ thermoelectric semiconductor, a first metal plate, a second metal plate, and a copper (Cu) electrode;
(b) filling the mold by contacting the thermoelectric semiconductor, the first metal plate, the second metal plate, and the copper (Cu) electrode to be in contact with each other so as to contact each other, and setting the chamber in the discharge plasma sintering apparatus;
(c) vacuuming the inside of the chamber to reduce the pressure, and applying a direct current pulse while pressing the copper (Cu) electrode, the second metal plate, the first metal plate, and the thermoelectric semiconductor, thereby applying a thermoelectric semiconductor, a first metal, Raising to a desired junction temperature lower than the melting temperature of the second metal and copper (Cu);
(d) pressurizing the copper (Cu) electrode, the second metal plate, the first metal plate, and the thermoconductor at the junction temperature, and the copper (Cu) electrode, the second metal plate, and the second metal plate. And bonding the first metal plate, the first metal plate, and the thermoelectric semiconductor to each other; And
(e) cooling the temperature of the chamber to obtain a thermoelectric element,
The first metal plate is made of aluminum metal or aluminum alloy,
The second metal plate is made of an alloy containing at least one metal selected from titanium (Ti), zirconium (Zr) and tungsten or at least one metal selected from titanium (Ti), zirconium (Zr) and tungsten. Method of manufacturing a thermoelectric element.
The preparation of the thermoelectric semiconductor according to claim 3,
Filling CoSb ₃ powder into a mold and setting it in a chamber of a discharge plasma sintering apparatus;
Comprising: a reduced pressure to the interior of the evacuated chamber and raised to the sintering temperature for applying a DC pulse to a lower target than the melting temperature of the CoSb ₃ powder and pressing the powder CoSb _3;
Discharge plasma sintering the CoSb ₃ powder while pressing the CoSb ₃ powder at the sintering temperature; And
Cooling the temperature of the chamber to obtain a CoSb ₃ thermoelectric semiconductor manufacturing method comprising a.
The method of claim 3, wherein the copper (Cu) electrode, the second metal plate, the first metal plate, and the thermoelectric semiconductor are pressurized in one axial direction, and a direct current pulse is applied in a direction parallel to the pressurization direction. Method for producing a thermoelectric element, characterized in that.
The junction temperature of claim 3, wherein the copper (Cu) electrode, the second metal plate, the second metal plate, the first metal plate, the first metal plate, and the thermoelectric semiconductor are bonded to each other. And, the method of manufacturing a thermoelectric element characterized in that the bonding is maintained for 5 to 30 minutes at the junction temperature.
The method of claim 3, wherein in step (c),
The pressure to pressurize is in the range of 10 to 60 MPa, and the inside of the chamber is decompressed in the range of 1.0 × 10 ^{-7 to} 9.0 × 10 ^-2 torr, and the DC pulse is applied in the range of 0.1 to 2000 A. Manufacturing method.
4. The method of claim 3, wherein the first metal plate that serves to enhance the bonding force between the thermoelectric semiconductor and the second metal plate uses a plate made of a thickness of 10㎛ 1mm, Cu (Cu) is the thermoelectric The second metal plate, which serves to prevent diffusion into the semiconductor, is a method of manufacturing a thermoelectric element, characterized in that a plate made of 10 μm to 1 mm in thickness is used.

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