JP4850083B2 - Thermoelectric conversion module, power generation device and cooling device using the same - Google Patents

Description

  The present invention relates to a thermoelectric conversion module suitably used for power generation and cooling, and a power generation device and a cooling device using the same.

  The thermoelectric conversion element has a characteristic that a potential difference is generated when a temperature difference is given to both ends of a PN junction pair composed of a P-type semiconductor and an N-type semiconductor, and is expected to be used for exhaust heat recovery power generation and the like. Yes.

  In addition, when a current is passed through the thermoelectric conversion element, the Peltier effect that one end generates heat and the other end absorbs heat is a module. The thermoelectric conversion module that is modularized enables precise temperature control, is compact, and has a structure. Due to its simplicity, it is expected to be widely used for electronic cooling elements such as freonless cooling devices, light detection elements, semiconductor manufacturing equipment, and laser diode temperature control.

  The structure of a basic thermoelectric conversion module is shown in FIG. In the thermoelectric conversion module 7, wiring conductors 3a and 3b are formed on the surfaces of the support substrates 1a and 1b, respectively. A plurality of thermoelectric conversion elements 2 composed of an N-type thermoelectric conversion element 2 a and a P-type thermoelectric conversion element 2 b are bonded via wiring layers 6 between the wiring conductors 3 a and 3 b.

  These thermoelectric conversion elements 2 are connected by wiring conductors 3 a and 3 b so as to be electrically in series, and further connected to the external connection terminal 4. A lead wire 5 is connected to the external connection terminal 4 by a bonding layer 6 and is electrically connected to the outside.

  As a technique for using the thermoelectric conversion element 2 as described above in a wide range of temperatures, high temperature type thermoelectric conversion elements 2c and 2d and low temperature type thermoelectric conversion elements 2a and 2b as shown in FIG. 4 are laminated and integrated. A technique using a segment type element is known. Further, as shown in FIG. 5, there is known a technique of making the thermoelectric conversion elements 2a and 2b into a cascade type with multiple stages through a support substrate 1c.

The following materials are used as materials for the thermoelectric conversion module as described above. The thermoelectric conversion module _{2 made of} A ₂ B ₃ type crystal (A is Bi and / or Sb, B is Te and / or Se) from the viewpoint of excellent cooling characteristics for the cooling thermoelectric conversion module used near room temperature. Is generally used.

A solid solution of Bi ₂ Te ₃ and Sb ₂ Te ₃ is shown for the N-type thermoelectric conversion element 2a, and a solid solution of Bi ₂ Te ₃ and Bi ₂ Se ₃ shows a particularly good performance for the P-type thermoelectric conversion element 2b. Therefore, this A ₂ B ₃ type crystal (A is Bi and / or Sb, B is Te and / or Se) is widely used for the thermoelectric conversion element 2.

  For power generation use, Bi-Te system is mainly used up to 200 to 300 ° C. as in the cooling application, and in a temperature range higher than that, Mn-Si system, Mg-Si system, Si-Ge system are used. Pb—Te, TAGS (GeTe—AgSbTe), Zn—Sb, skutterudite, and the like are widely used for the thermoelectric conversion element 2.

Regarding the thermoelectric conversion module 7 using the segment type module described above, a technique for laminating a sintered material having high strength and a melted material having high performance (for example, see Patent Document 1) and two thermoelectric conversion elements having different thermal expansions A technique of inserting a material having an intermediate thermal expansion between them (for example, see Patent Document 2) has been proposed. By using these techniques, it is possible to relieve stress inside the thermoelectric conversion module that is generated due to thermal strain or thermal expansion difference due to heat.
JP-A-8-148725 JP 2005-19910 A

  However, the thermoelectric conversion module of Patent Document 1 is effective in stacking a high-strength sintered material and a high-performance melted material, increasing the strength while maintaining the performance, and suppressing the destruction of the thermoelectric conversion element. However, it was still insufficient in performance and strength.

  In addition, the thermoelectric conversion module of Patent Document 2 stacks different thermoelectric conversion elements to improve performance, and inserts a material having intermediate thermal expansion between two thermoelectric conversion elements having different thermal expansions. Although effective in reducing the thermal expansion difference and suppressing the destruction of the thermoelectric conversion element, there is a problem in that the output fluctuates due to vibration or impact and current cannot be supplied stably.

  As a result of earnest investigation and analysis of this phenomenon, the inventor changed the particle size, relative density, or porosity of a plurality of thermoelectric conversion elements, and produced and laminated thermoelectric conversion elements having different hardnesses, thereby increasing the output. It has been found that a stable thermoelectric conversion module can be obtained.

  Accordingly, an object of the present invention is to provide a thermoelectric conversion module, a power generation device, and a cooling device that are excellent in output stability.

Thermoelectric conversion module according to the present invention, the wiring conductors for connecting the plurality of P-type thermoelectric conversion elements, and a plurality of N-type thermoelectric conversion elements, alternately in series with the P-type thermoelectric conversion elements and the N-type thermoelectric conversion element When, a thermoelectric conversion module comprising a said thermoelectric conversion element, the electrode layers includes two or more thermoelectric layers having different hardness, of two or more different thermoelectric layer of the hardness, the highest hardness high The hardness thermoelectric layer is characterized by having a particle size smaller than any one of the other low hardness thermoelectric layers.

Further, other of the thermoelectric conversion module according to the present invention includes a plurality of P-type thermoelectric conversion elements, and a plurality of N-type thermoelectric conversion element, series alternating with said P-type thermoelectric conversion element and the N-type thermoelectric conversion element a thermoelectric conversion module comprising a wiring conductor connecting said thermoelectric conversion element, the electrode layers includes two or more thermoelectric layers having different hardness, of two or more different thermoelectric layer of the hardness, the most A high-hardness thermoelectric layer with high hardness is characterized by a higher density than any one of the other low-hardness thermoelectric layers.

Further, other of the thermoelectric conversion module according to the present invention includes a plurality of P-type thermoelectric conversion elements, and a plurality of N-type thermoelectric conversion element, series alternating with said P-type thermoelectric conversion element and the N-type thermoelectric conversion element a thermoelectric conversion module comprising a wiring conductor connecting said thermoelectric conversion element, the electrode layers includes two or more thermoelectric layers having different hardness, of two or more different thermoelectric layer of the hardness, the most A high hardness thermoelectric layer with high hardness is characterized by a lower porosity than any one of the other low hardness thermoelectric layers.

In the above present invention, and the high-hardness thermoelectric layer, between the high-hardness thermoelectric layer and adjacent the low-hardness thermoelectric layer, wherein the high-hardness hardness than the thermoelectric layer is high intermediate layer is provided It is preferable.

  In the present invention, the intervening layer is preferably made of a metal material.

  In the present invention, the intervening layer is at least one selected from the group consisting of Ti, Ni, Al, Cu, Fe, Ag, Au, Mo, Mn, W, Sn, Si, Pt, Nb, Cr, and Co. It is preferable that it consists of a seed | species or its alloy.

  By using the present invention, the low-hardness thermoelectric conversion element is appropriately deformed while the high-hardness thermoelectric conversion element retains its shape. Therefore, stress and strain generated at the interface between the thermoelectric conversion elements can be relaxed, and thereby loss of heat transfer and disturbance of the flow of electrons or holes can be suppressed. Therefore, current fluctuation is suppressed and current can be supplied stably. In particular, in a thermoelectric conversion element having a small particle size, the number of grain boundaries increases, so that the effect of absorbing the occurrence of stress and strain by the grain boundary sliding is produced. Therefore, the stress and strain applied between the particles are alleviated, and the flow of electrons and holes is hardly disturbed. Therefore, the synergistic effect with the above effect can further reduce the output fluctuation and stably supply the current. Further, it is particularly effective when the performance is improved by stacking thermoelectric conversion elements having different compositions.

  One embodiment of the present invention will be described below. In any of the embodiments, it is possible to use an insulating substrate in which an electrode and an insulator such as ceramics such as alumina, aluminum nitride, silicon nitride, and silicon carbide are integrated in order to strengthen the structure retention of the module. .

  FIG. 1 shows an embodiment of a cross-sectional view of a thermoelectric conversion module 7 of the present invention.

  According to this figure, the thermoelectric conversion element 2 consists of N-type thermoelectric conversion elements 2a and 2c and P-type thermoelectric conversion elements 2b and 2d. This thermoelectric conversion module 7 electrically connects a plurality of P-type and N-type alternately arranged thermoelectric conversion elements 2 and the thermoelectric conversion elements 2 adjacent to the upper end surface and the lower end surface of these thermoelectric conversion elements 2. Wiring conductors 3a and 3b to be connected, a bonding layer 6 for bonding the wiring conductors 3a and 3b and the upper end surface or the lower end surface of the thermoelectric conversion element 2, and a lead wire 5 for supplying electricity to the outside.

  Here, in the thermoelectric conversion element 2, low temperature side thermoelectric conversion elements 2a and 2b and high temperature side thermoelectric conversion elements 2c and 2d are laminated. The low temperature side thermoelectric conversion elements 2a, 2b and the high temperature side thermoelectric conversion elements 2c, 2d need only be laminated, and need not be fixed by a technique such as bonding or adhesion.

Conventionally used materials can be used for the thermoelectric element of the present invention. In particular, in cooling applications and power generation applications at 300 ° C. or lower, Bi—Te system having the most excellent thermoelectric conversion performance near normal temperature is preferable. Thereby, good power generation performance and cooling effect can be obtained. Bi _0.4 Sb _1.6 Te ₃ , Bi _0.5 Sb _1.5 Te _3, etc. as P type, Bi ₂ Te _2.85 Se _0.15 , Bi ₂ Te _2.9 Se _0.1 as N type Etc. are preferably used. At higher temperatures, Mn—Si, Mg—Si, Si—Ge, Pb—Te, TAGS (GeTe—AgSbTe), Zn—Sb, skutterudite, and the like can be suitably used.

  In the thermoelectric conversion module 7 of the present invention, the stacked low temperature side thermoelectric conversion elements 2a and 2b and the high temperature side thermoelectric conversion elements 2c and 2d in FIG. 1 are different in hardness. It is important that the particle size is smaller than any one of the other low-hardness thermoelectric layers. The high-hardness thermoelectric conversion element has an action of maintaining and maintaining the entire shape, and maintains the structure of the entire module, and has an effect of resisting excessive vibration, impact, and strain. On the other hand, the thermoelectric conversion element on the low hardness side moderates stress and strain generated at the interface between the thermoelectric conversion elements by being appropriately deformed. Therefore, loss of heat transfer and disturbance of the flow of electrons or holes can be suppressed, so that current fluctuation is suppressed and current can be supplied stably. In particular, in the thermoelectric conversion element 2 having a small particle size, the number of grain boundaries increases, so that the effect of absorbing the occurrence of stress and strain by the grain boundary sliding is produced. Therefore, the stress and strain applied between the particles are relaxed, and the disturbance of the flow of electrons and holes is less likely to occur. Therefore, the output is further increased due to the synergistic effect of the loss of heat transfer and the disturbance of the flow of electrons or holes. Fluctuation can be reduced and current can be supplied stably. Further, it is particularly effective when the thermoelectric conversion elements 2 having different compositions and the like are stacked to improve performance. The difference in particle size is 5% or more, preferably 10% or more, more preferably 20% or more.

  Further, the thermoelectric conversion module 7 of the present invention is different in hardness from the stacked low temperature side thermoelectric conversion elements 2a, 2b and high temperature side thermoelectric conversion elements 2c, 2d in FIG. It is important that the density is relatively high compared to any one of the other low-hardness thermoelectric layers. In a thermoelectric conversion element having a high density, the density of electrons or holes is high, so that even if stress or strain occurs, the flow of electrons or holes is not easily disturbed. Due to the synergistic effect with the flow disturbance suppression effect, the output fluctuation can be further reduced and the current can be supplied stably. This is particularly effective when the thermoelectric conversion elements 2 having different compositions and the like are stacked to improve performance. The difference in density is 5% or more, preferably 10% or more, more preferably 20% or more.

  In the thermoelectric conversion module of the present invention, the laminated low temperature side thermoelectric conversion elements 2a and 2b and the high temperature side thermoelectric conversion elements 2c and 2d in FIG. It is important that the porosity is relatively low compared to any one of the other low-hardness thermoelectric layers. Since the thermoelectric conversion element 2 having a low porosity has few grain boundary defects, electrons and holes easily flow, and even if stress or distortion occurs, the flow of electrons or holes is not easily disturbed. Therefore, the synergistic effect of the loss of heat transfer and the effect of suppressing the disturbance of the flow of electrons or holes can further reduce output fluctuations and supply current stably. Further, it is particularly effective when the thermoelectric conversion elements 2 having different compositions are laminated to improve the performance. The difference in porosity is 2% or more, preferably 5% or more, more preferably 10% or more.

Furthermore, said high-hardness thermoelectric layer, wherein adjacent to the high hardness thermoelectric layer between the low hardness thermoelectric layer, it is important that the high-hardness thermoelectric layer interposed layer 8 having a high hardness than is provided . It is preferable that the high-hardness intervening layer 8 is disposed between the low temperature side thermoelectric conversion elements 2a and 2b and the high temperature side thermoelectric conversion elements 2c and 2d. As a result, the interstitial layer tries to maintain the structure, and the two thermoelectric conversion elements on both sides of the intervening layer are appropriately deformed on both sides, so that the amount of deformation or distortion can be further reduced and heat transfer loss can be reduced. Can be suppressed. In addition, it is possible to prevent disturbance of the flow of electrons or holes. As a result, output fluctuations can be suppressed and current can be supplied stably. Moreover, destruction and breakage of the thermoelectric conversion element 2 due to deformation and strain can be reduced. The hardness of the intervening layer 8 is desirably 1.2 times or more that of the high-hardness material, preferably 1.5 times or more, and more preferably 2 times or more.

  The intervening layer 8 is preferably made of a metal material. By inserting a high-hardness metal layer between low-hardness materials, the metal layer tries to maintain its structure, and the two thermoelectric conversion elements on both sides of the intervening layer are appropriately deformed on both sides. The amount of deformation or distortion can be reduced. In addition, it is possible to prevent disturbance of the flow of electrons or holes. As a result, output fluctuations can be suppressed and current can be supplied stably. Moreover, destruction and breakage of the thermoelectric conversion element 2 due to deformation and strain can be reduced. Here, the thickness of the intervening layer 8 is desirably 5 mm or less. If it is thicker than 5 mm, the heat transfer becomes large, so the efficiency drops. Further, since the intervening layer 8 does not contribute to power generation, the output per unit volume is reduced. Preferably it is 3 mm or less, more preferably 1 mm or less.

  The intervening layer 8 disposed between the low temperature side thermoelectric conversion elements 2a, 2b and the high temperature side thermoelectric conversion elements 2c, 2d is Ti, Ni, Al, Cu, Fe, Ag, Au, Mo, Mn, W , Sn, Si, Pt, Nb, Cr, and Co are preferable. Thereby, the site | part which deform | transforms further can be made smaller. Therefore, the amount of deformation or distortion can be reduced, so that heat transfer loss can be suppressed. In addition, it is possible to prevent disturbance of the flow of electrons or holes. As a result, output fluctuations can be suppressed and current can be supplied stably. The intervening layer 8 is obtained by sintering the thermoelectric conversion element 2 and simultaneously sintering the powder. Alternatively, a plate-like, mesh-like, or strip-like metal can be used.

  Moreover, it is preferable to have the reaction layer 9 in the contact interface between the low-hardness thermoelectric conversion element and the intervening layer 8 as shown in FIG. Since the hardness of the reaction layer 9 is intermediate between that of the low-hardness thermoelectric conversion element, the buffering action works, and the deformation amount or strain can be reduced. In addition, it is possible to prevent disturbance of the flow of electrons or holes. As a result, output fluctuations can be suppressed and current can be supplied stably. This reaction layer 9 is obtained by sintering the thermoelectric conversion element 2 and simultaneously sintering the powder. Alternatively, it can be obtained by heat treatment after inserting a plate-like, mesh-like, or strip-like metal. In the reaction layer, the composition of the low-hardness material and the intervening layer is present in an amount of 0.1% or more, and the thickness is 0.1 μm or more.

  Moreover, it is preferable to have the reaction layer 9 in the contact interface between the high hardness thermoelectric conversion element and the intervening layer 8 as shown in FIG. Since the hardness of the reaction layer 9 is intermediate between that of the high-hardness thermoelectric conversion element, a buffering action works, and the deformation amount or strain can be reduced. In addition, it is possible to prevent disturbance of the flow of electrons or holes. As a result, output fluctuations can be suppressed and current can be supplied stably. This reaction layer 9 is obtained by sintering the thermoelectric conversion element and simultaneously sintering the powder. Alternatively, it can be obtained by heat treatment after inserting a plate-like, mesh-like, or strip-like metal. In the reaction layer, the composition of the high-hardness material and the intervening layer is present in an amount of 0.1% or more, and the thickness is 0.1 μm or more.

  In addition, the hardness of the reaction layer 9 existing on the contact surface between the low-hardness thermoelectric conversion element and the intervening layer 8 may gradually and continuously change from the low-hardness thermoelectric conversion element to the center of the intervening layer 8. preferable. Thereby, the buffering action is large, and the deformation amount or distortion can be reduced. In addition, it is possible to prevent disturbance of the flow of electrons or holes. This reaction layer 8 is obtained by sintering the thermoelectric conversion element 2 and simultaneously sintering the powder. Alternatively, it can be obtained by heat treatment after inserting a plate-like, mesh-like, or strip-like metal.

  Further, the hardness of the reaction layer 9 existing on the contact surface between the high-hardness thermoelectric conversion element and the intervening layer 8 continuously and gradually changes from the high-hardness thermoelectric conversion element to the center of the intervening layer 8. It is preferable. Thereby, the buffering action is large, and the deformation amount or distortion can be reduced. In addition, it is possible to prevent disturbance of the flow of electrons or holes. This reaction layer 9 is obtained by sintering the thermoelectric conversion element 2 and simultaneously sintering the powder. Alternatively, it can be obtained by heat treatment after inserting a plate-like, mesh-like, or strip-like metal.

  Further, it is preferable to use a heat exchange device such as a fin joined or integrated with the above-described thermoelectric module. Since heat recovery and heat dissipation can be performed efficiently with little heat transfer loss, a module with high conversion efficiency can be obtained. The heat exchange device has a function of transferring heat to the thermoelectric conversion module 7 or releasing the heat. In addition to the fins, the heat exchange device has any shape such as a rod shape, a mesh shape, a honeycomb shape, a cylindrical shape, and a rotating body. Can be used.

  Moreover, the said thermoelectric conversion module can be used as an electric power generation means using exhaust heat, such as a motor vehicle or a cogeneration. Thereby, the power generator excellent in long-term stability can be provided.

  Further, the thermoelectric conversion module can be used as a cooling means for, for example, a laser or a semiconductor manufacturing apparatus. Thereby, the cooling device excellent in long-term stability can be provided.

  Next, the manufacturing method of the thermoelectric conversion module of this invention is demonstrated below.

  The method for producing a thermoelectric conversion module of the present invention comprises a step of laminating powders, molded bodies or sintered bodies having different particle diameters, and then gradually raising the temperature from a temperature 5 ° C. or more lower than the target temperature for 1 to 500 minutes to sinter and bond Let By baking after lamination, the integrated laminated thermoelectric conversion element 2 having different hardness can be produced. By gradually increasing the temperature from a temperature lower than the target temperature, it is possible to prevent an excessive increase in temperature, and it is possible to manufacture a stable thermoelectric conversion element 2. It is desirable to gradually raise the temperature from a temperature that is preferably 20 ° C. or higher, more preferably 50 ° C. or higher.

  Specifically, first, raw material powder for the thermoelectric conversion element 2 is prepared. The raw material powder is obtained by weighing a raw material having a predetermined composition, putting it in a crucible or the like, melting and alloying it, and then pulverizing it. After weighing the raw material, it is mixed and pulverized to obtain a uniform fine raw material, whereby a more uniform alloy can be obtained. Further, melting and alloying are effective for obtaining an alloy with less composition fluctuation and less oxidation by sealing in a vacuum or an inert gas. Furthermore, for the purpose of reducing the amount of oxygen in the raw material, the raw material powder or the compact can be reduced in hydrogen.

  The raw material of the thermoelectric conversion element 2 and the raw material of the intervening layer thus obtained are packed in a die in layers and stacked. For this raw material powder, known methods such as hot press (HP), hot forge, spark plasma sintering (SPS), atmospheric pressure sintering, gas pressure sintering (GPS), hot isostatic pressing (HIP), etc. By this method, a sintered body can be obtained. The sintered body is processed into a desired shape to obtain the thermoelectric conversion element 2.

  Next, a brazing material is applied on the wiring conductor 3, is placed on the N-type and P-type thermoelectric conversion elements 2, and is joined by being heated under pressure. Here, the brazing material is selected from the solder such as silver brazing, copper brazing, brass brazing, aluminum brazing, nickel brazing, phosphoric copper brazing, active metal brazing, Au—Sn, Sn—Sb, etc. Depending on the heat resistance, it can be selected as appropriate. Moreover, a formwork can also be used from a viewpoint of workability | operativity and a structure retainability improvement. The mold is made of ceramics such as alumina, aluminum nitride, silicon nitride, silicon carbide, diamond, metals such as Ti, Ni, Al, Fe, Cu, and alloys thereof depending on the operating temperature and the thermal expansion coefficient of the thermoelectric conversion element 2. It can be selected as appropriate. The thermoelectric conversion elements 2 are arranged so that the N-type and P-type thermoelectric conversion elements 2 are alternately arranged, and are arranged so as to be electrically connected in series. Further, the wiring conductor 3 can be installed by a conventional method such as a thermal spraying method, a pressure welding method, or a bolt fastening. Moreover, the wiring conductor 3 can improve the holding | maintenance of a structure and intensity | strength by using the board | substrate integrated with ceramics. As the substrate 1, ceramics such as alumina, aluminum nitride, silicon nitride, silicon carbide, diamond, or an insulating plate can be used.

  The thermoelectric conversion module 7 is obtained by joining the obtained thermoelectric conversion module 7 with the lead wire 5 that takes out electricity or supplies current to the outside. Instead of the lead wire 5, a pillar, a plate, or a block can be used.

  Moreover, in the thermoelectric conversion module 7 using a frame, atmosphere gas is enclosed inside, and deterioration by oxidation, corrosion, etc. of thermoelectric conversion module 7 structural members, such as the thermoelectric conversion element 2 or the wiring conductor 3, can be prevented.

  When the low temperature side and the high temperature side can be joined with the same brazing material or solder due to the low use temperature or the high heat resistance of the thermoelectric conversion element 2, the low temperature side and high temperature side support substrates 1 are simultaneously attached. The thermoelectric conversion module 7 can also be obtained by bonding.

  Thus, the thermoelectric conversion module 7 excellent in the electrical stability of the present invention can be provided.

  Examples of the present invention will be described below.

  As a starting material of the thermoelectric exchange element used in the present invention, a Co-Sb-Te-based material and a Bi-Sb-Te-Se-based material are prepared, and a predetermined amount is weighed, put in a crucible, and melted, Alloyed. The alloy was used after pulverization and mesh passing. In the firing, Ti serving as the intervening layer 8 is first packed in a die, and then the Co—Sb—Te alloy raw material is packed and laminated. The temperature was raised to 570 ° C. in an SPS firing furnace, and then raised to 600 ° C. in 30 minutes to obtain a sintered body. Next, Bi—Sb—Te—Se alloy material is packed in a die, and the Co—Sb—Te sintered body is placed thereon so that the intervening layer 8 is in contact with the Bi—Sb—Te—Se alloy material. Laminate. The temperature was raised again to 350 ° C. in the SPS firing furnace, and then the temperature was raised to 380 ° C. in 30 minutes to obtain a sintered body. The obtained sintered body was cut into dimensions of 3 mm in length, 3 mm in width, and 5 mm in height to obtain a thermoelectric conversion element 2 constituting the thermoelectric conversion module 7.

  The P-type and N-type thermoelectric conversion elements 2 obtained as described above are arranged, the wiring conductor 3 coated with the brazing material and dried is covered from above, heated while being pressurized, and the thermoelectric conversion element 2 and the wiring conductor 3 are covered. Were joined. In order to improve the wettability of the brazing material, the joining surface of the thermoelectric conversion element 2 is plated, or when the thermoelectric conversion element is sintered, a layer of Ni, Cu, Au or the like is simultaneously sintered to join the joining surface. It can be.

  The thermoelectric conversion module 7 can be manufactured by arranging the P-type and N-type thermoelectric conversion element pairs thus obtained, joining the low-temperature side wiring conductors with solder, and joining the lead wires to the wiring conductors at the ends. The wiring conductor 3 can be integrated with the support substrate 1 such as alumina in order to improve the structural strength.

  The thermoelectric conversion module 7 thus obtained was cooled by flowing cooling water through the heat sink on the lower surface and kept at a constant temperature. Moreover, a temperature difference (ΔT) was given to the upper and lower surfaces of the thermoelectric conversion module 7 by attaching and heating a heater on the upper surface. The output was measured while applying vibration to this apparatus, and the number of noises generated in 10 minutes was measured.

  In addition, about the measurement of hardness, it measured with the micro Vickers hardness meter based on JIS-R1610. At this time, the time for pressing the indenter with a load of 25 gf was 15 seconds. Then, after removing the load, the hardness was calculated from the indentation formed on the element surface.

The density and porosity were measured by Archimedes method based on JIS-R1634. For the particle size, take a SEM picture of the fracture surface or polished surface of the device, select 100 or more particles from them, convert the particle shape into a circle by image processing, and average the diameters It is.

  In Table 1, for No. 1 to No. 6, the particle size and hardness of the high hardness thermoelectric layer are changed, and for No. 7 to No. 28, the differences described in Table 1 are different between the low hardness thermoelectric layer and the high hardness thermoelectric layer. For each of Nos. 29 to 33, a high-hardness thermoelectric layer was prepared by a different manufacturing method described in Table 1 as a firing method other than the discharge plasma sintering (SPS) method, and Nos. 34 to 39, respectively. These are the results of conducting an experiment using a thermoelectric conversion module using different materials described in Table 1 as the high hardness thermoelectric layer.

  For No1 and No6 where the high hardness thermoelectric layer / low altitude thermoelectric layer was 1.0, the number of noises was 40 times or more. On the other hand, in the other examples, the number of noises was 15 or less, and good results could be obtained.

  In addition, when Al, Cu, Ag, Au, or Sn having relatively close hardness to the high-hardness thermoelectric layer was used as the intervening layer, the number of noises could be reduced.

  In addition, No. 32, which produced a high-hardness thermoelectric layer using the hot isostatic pressing (HIP) method, reduced the number of noises compared to the hot press (HP) method, gas sintering (GPS) method, and hot forge method. I was able to.

Furthermore, the number of noises can be reduced by using Fe—Si as the material for the high-hardness thermoelectric layer as compared with materials using other materials.

  In Table 2 above, for No. 40 to 45, the particle size and density of the high hardness thermoelectric layer were changed, and for No. 46 to 65, the differences described in Table 2 were different between the low hardness thermoelectric layer and the high hardness thermoelectric layer. For each of No. 66 and No. 67, the thickness of the intermediate layer was changed, and for No. 68 to No. 72, a high hardness thermoelectric layer was used as a firing method other than the discharge plasma sintering (SPS) method. No73 is a result of experiments using a thermoelectric conversion module using Pb-Te as a high-hardness thermoelectric layer.

For No40 and No45 where the high-hardness thermoelectric layer / low-altitude thermoelectric layer was 1.0, the number of noises was 40 times or more. On the other hand, in the other examples, the number of noises was 14 or less, and good results could be obtained. Also, as the intervening layer, Al, Cu, Ag, Au having relatively close hardness with the high-hardness thermoelectric layer When Sn, Ti-Ni, Al-Cu, Ti-Al, and Fe-Al were used, the number of noises could be reduced.

  Moreover, No66 and No67 which increased the thickness of the intervening layer was able to reduce the number of noises compared with No46 and No47 having the intervening layer made of the same material.

In addition, No. 32, which produced a high-hardness thermoelectric layer using the hot isostatic pressing (HIP) method and gas sintering (GPS) method, reduced the number of noises compared to the hot press (HP) method and hot forge method. I was able to.

  In Table 2, for No. 74 to 79, the particle size and hardness of the high hardness thermoelectric layer are changed, and for No. 80 to 101, the differences described in Table 1 are different between the low hardness thermoelectric layer and the high hardness thermoelectric layer. For each of Nos. 102 to 106, a high-hardness thermoelectric layer was prepared by a different manufacturing method described in Table 1 as a firing method other than the discharge plasma sintering (SPS) method, and Nos. 107 to 112 were respectively interposed. These are the results of conducting an experiment using a thermoelectric conversion module using different materials described in Table 1 as the high hardness thermoelectric layer.

For No. 74 and No. 79 where the high-hardness thermoelectric layer / low-altitude thermoelectric layer was 1.0, the number of noises was 40 times or more. On the other hand, in the other examples, the number of noises was 14 or less, and good results could be obtained. Also, as the intervening layer, Al, Cu, Ag, Au having relatively close hardness with the high-hardness thermoelectric layer When Sn, Ti-Ni, Al-Cu, Ti-Al, and Fe-Al were used, the number of noises could be reduced.

  Moreover, No100 and No101 which increased the thickness of the intervening layer were able to reduce the number of noises compared to No80 and No81 having the intervening layer made of the same material.

Furthermore, the number of noises can be reduced by using Fe—Si and Zn—Sb as materials for the high-hardness thermoelectric layer as compared with those using other materials.

It is sectional drawing of the thermoelectric conversion module of one Embodiment of this invention. It is sectional drawing of the segment type thermoelectric conversion element of one Embodiment of this invention. It is a perspective perspective view of a thermoelectric conversion module. It is sectional drawing of the conventional segment type thermoelectric conversion module. It is a perspective view of the conventional two-stage thermoelectric conversion module.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Support substrate 1a ... Lower support substrate 1b ... Upper support substrate 1c ... Intermediate support substrate 2 ... Thermoelectric conversion element 2a ... Low temperature N type thermoelectric conversion element 2b ... Low temperature P-type thermoelectric conversion element 2c ... High-temperature N-type thermoelectric conversion element 2d ... High-temperature P-type thermoelectric conversion element 3a, 3b ... Wiring conductor 4 ... External connection terminal 5 ... Lead wire 6 ... Junction layer 7 ... Thermoelectric conversion module 8 ... Intervening layer 9 ... Reaction layer 9a ... Low temperature side reaction layer 9b ... High temperature side reaction layer

Claims (9)

A thermoelectric conversion module comprising a plurality of P-type thermoelectric conversion elements, and a plurality of N-type thermoelectric conversion element, and a wiring conductor connected in series alternately with the P-type thermoelectric conversion elements and the N-type thermoelectric conversion element The thermoelectric conversion element includes two or more thermoelectric layers having different hardnesses, and among the two or more thermoelectric layers having different hardnesses, the high-hardness thermoelectric layer having the highest hardness is any one of the other low-power thermoelectric layers. A thermoelectric conversion module characterized in that the particle size is smaller than the hardness thermoelectric layer. A thermoelectric conversion module comprising a plurality of P-type thermoelectric conversion elements, and a plurality of N-type thermoelectric conversion element, and a wiring conductor connected in series alternately with the P-type thermoelectric conversion elements and the N-type thermoelectric conversion element The thermoelectric conversion element includes two or more thermoelectric layers having different hardnesses, and among the two or more thermoelectric layers having different hardnesses, the high-hardness thermoelectric layer having the highest hardness is any one of the other low-power thermoelectric layers. Thermoelectric conversion module characterized in that the density is higher than the hardness thermoelectric layer. A thermoelectric conversion module comprising a plurality of P-type thermoelectric conversion elements, and a plurality of N-type thermoelectric conversion element, and a wiring conductor connected in series alternately with the P-type thermoelectric conversion elements and the N-type thermoelectric conversion element The thermoelectric conversion element includes two or more thermoelectric layers having different hardnesses, and among the two or more thermoelectric layers having different hardnesses, the high-hardness thermoelectric layer having the highest hardness is any one of the other low-power thermoelectric layers. A thermoelectric conversion module characterized by a lower porosity than a hardness thermoelectric layer. And said high-hardness thermoelectric layer, between the high-hardness thermoelectric layer and adjacent the low-hardness thermoelectric layer, claims, characterized in that said high hardness hardness than the thermoelectric layer is high intermediate layer is provided The thermoelectric conversion module according to any one of 1 to 3.   The thermoelectric conversion module according to claim 4, wherein the intervening layer is made of a metal material.   The intervening layer is made of at least one selected from the group consisting of Ti, Ni, Al, Cu, Fe, Ag, Au, Mo, Mn, W, Sn, Si, Pt, Nb, Cr, and Co, or an alloy thereof. The thermoelectric conversion module according to claim 5. Thermoelectric conversion module, characterized in that it has joined or integrated with the heat exchanger to the thermoelectric conversion module according to any one of claims 1 to 6. Power generator, characterized in that the power generating means thermoelectric conversion module according to any one of claims 1 to 6. Cooling device, characterized in that the cooling means the thermoelectric conversion module according to any one of claims 1 to 6.

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