Connection method of high-temperature thermoelectric material and metal electrode
By using high entropy MAX phase as the intermediate layer material, the problem of high interface contact resistance and insufficient strength in the connection between high-temperature thermoelectric materials and metal electrodes is solved, low-temperature interconnection and high-temperature stable connection are achieved, reducing interface resistance and improving the mechanical performance of the connector.
Patent Information
- Application Number
- CN202510544462.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-28
- Publication Date
- 2025-07-29
AI Technical Summary
In the existing connection methods of high-temperature thermoelectric materials and metal electrodes, the interface contact resistance is high and the strength is insufficient, and the high-temperature connection process is prone to element diffusion and structural failure.
The high-entropy MAX phase is used as the intermediate layer material. Through the design of the low-melting point liquid phase and the high-entropy treatment, low-temperature interconnection is achieved and element diffusion is suppressed. The MAX phase with excellent mechanical properties and thermal conductivity is used as the connecting intermediate layer to reduce interface resistance and improve joint strength.
The produced high-temperature thermoelectric material/metal joints have smaller interface resistance and higher strength to ensure stable connection under high temperature environments.
Smart Images
Figure CN120390577A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of welding technology, and in particular, to a method for connecting a high-temperature thermoelectric material and a metal electrode. Background Art
[0002] Thermoelectric devices can achieve efficient conversion between thermal energy and electrical energy through the Seebeck effect or Peltier effect of thermoelectric materials, and have important application potential in fields such as waste heat recovery, deep space exploration, solid-state refrigeration, and micro-region temperature control. However, the interfacial characteristics between the thermoelectric semiconductor and the metal electrode in thermoelectric devices often become the key bottleneck restricting the energy conversion efficiency. The physical property differences between the thermoelectric material and the metal electrode make the problem of interfacial compatibility particularly prominent. Especially for high-temperature thermoelectric devices, atomic interdiffusion, interfacial reactions, and thermal stress mismatches between metals / semiconductors under high-temperature working environments may lead to the degradation of the interfacial structure, seriously affecting the long-term stability of the device; on the contrary, high-temperature service interfaces are often connected at higher temperatures, and excessive connection temperatures are likely to cause performance damage to the thermoelectric material.
[0003] Existing connection methods for high-temperature thermoelectric materials and metal electrodes mainly focus on diffusion bonding and integrated sintering. Taking SiGe high-temperature thermoelectric materials as an example, Ti or graphite is usually used as the intermediate layer for diffusion bonding. During the connection process, elements diffuse significantly to form Kirkendall pores; or integrated sintering is achieved using titanium compound and silicide powders as the intermediate layer. The sintering interface is tortuous and uncontrollable, and the intermediate sintering layer is often very thick, introducing additional interfacial resistance problems. Therefore, there is an urgent need to develop a connection intermediate layer and connection process with interfacial compatibility, which can inhibit element diffusion and reduce the connection temperature to avoid high-temperature thermal damage, thereby reducing the interfacial contact resistance of the joint and improving the strength of the joint. Summary of the Invention
[0004] The problem solved by the present invention is: for the welding of high-temperature thermoelectric materials and metal electrodes, how to reduce the interfacial contact resistance of the joint and improve the strength of the joint.
[0005] To solve the above problems, the present invention provides a method for connecting a high-temperature thermoelectric material and a metal electrode, including:
[0006] Step S1: Assemble a high-temperature thermoelectric material, an intermediate layer, and a metal electrode material in sequence from top to bottom to obtain an assembled component; wherein, the material of the intermediate layer is a high-entropy MAX phase, and the high-entropy MAX phase is M n+1 AX n; M is selected from at least one of the elements in Group IIIB, Group IVB, Group VB and Group VIB, A is selected from at least two main group elements in Group IIIA, Group IVA and Group VIII, at least one of the at least two main group elements is selected from at least one of the elements in Group IIIA and Group IVA, X is selected from at least one of the elements C, N and B, and n is an integer from 1 to 3; the high-temperature thermoelectric material includes at least one of Half-Heusler thermoelectric materials, PbTe, SiGe and La2Te3;
[0007] Step S2: Heat the fitting to a preset temperature under a preset pressure, keep it warm for a preset time, and then cool it to room temperature to obtain a high-temperature thermoelectric material / metal joint.
[0008] Optionally, in step S1, the Half-Heusler thermoelectric material is selected from at least one of ZrNiSn, TiNiSn, NiFeSb, FeNbSb, ZrCoSb, TiCoSb and HfCoSb.
[0009] Optionally, in step S1, the metal electrode material is selected from at least one of W, W alloys, Mo, Mo alloys, Cu, Cu alloys, Ni and Ni alloys.
[0010] Optionally, in step S1, the thickness of the high-temperature thermoelectric material is 4 mm to 20 mm.
[0011] Optionally, in step S1, the thickness of the intermediate layer is 0.1 mm to 1 mm.
[0012] Optionally, in step S1, the thickness of the metal electrode material is 0.3 mm to 4 mm.
[0013] Optionally, in step S1, the preparation method of the intermediate layer includes:
[0014] Step S11: Mix the simple substance corresponding to M, the simple substance corresponding to A, and the simple substance corresponding to X in the M n+1 AX n in a molar ratio of (n + 1):1:n, and then perform ball milling to obtain intermediate layer powder;
[0015] Step S12: Press the intermediate layer powder to obtain the intermediate layer.
[0016] Optionally, in step S11, the rotation speed of the ball milling is 100 rpm to 150 rpm, and the time is 8 h to 12 h.
[0017] Optionally, in step S12, the pressure of the pressing is 10 MPa to 70 MPa, and the time is 5 min to 15 min.
[0018] Optionally, in the step S2, the preset pressure is 1 MPa to 70 MPa, the preset temperature is 700 °C to 1150 °C, and the preset time is 5 min to 120 min.
[0019] Compared with the related art, aiming at the problem of interconnecting existing high-temperature thermoelectric materials and metal electrodes, the present invention uses a high-entropy MAX phase as a connecting intermediate layer. By designing a low-melting-point liquid phase at the A site, low-temperature interconnection between the thermoelectric material and the metal electrode and element diffusion blocking are achieved, and good service stability at high temperatures at the interface is realized. Among them, the MAX phase has both metallic and ceramic properties, has good mechanical properties, high thermal conductivity, high thermal stability and corrosion resistance, and is an excellent intermediate layer for interconnecting high-temperature thermoelectric materials and metal electrodes. At the same time, the MAX phase can be element-modified at the M site or the A site to achieve solid-solution high-entropyization. By using the high-entropyization design of the connection interface and utilizing its diffusion retardation effect, the atomic diffusion rate is reduced, thereby suppressing excessive element diffusion during the connection or service process of the high-temperature thermoelectric material / metal electrode joint. Third, by designing elements in Group IIIA, Group IVA, and Group VIII (such as Sn, Ge, Al) with lower melting points at the A site in the MAX phase, a liquid phase can be formed during the connection process, eliminating the initial connection gap and providing a transmission channel for the connection process, greatly reducing the connection temperature. Compared with the related art, the high-temperature thermoelectric material / metal joint prepared by the method provided by the present invention has a smaller interface resistance and higher strength. Description of the Drawings
[0020] Figure 1 It is a scanning electron microscope picture of the high-temperature thermoelectric material / metal joint prepared in Example 2;
[0021] Figure 2 It is a scanning electron microscope picture of the high-temperature thermoelectric material / metal joint prepared in Comparative Example 1;
[0022] Figure 3 It is a scanning electron microscope picture of the high-temperature thermoelectric material / metal joint prepared in Comparative Example 2. Detailed Embodiments
[0023] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention is given with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments described herein. On the contrary, these embodiments are provided to more thoroughly and completely understand the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not used to limit the protection scope of the present invention.
[0024] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the present invention in the specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention.
[0025] As used herein, the term "comprising" and its variations are open-ended, i.e., "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiment". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts of "first", "second", etc. mentioned in the present invention are used to distinguish different objects and are not used to describe a specific order or primary-secondary relationship. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.
[0026] In the related art, there are high-temperature interconnect problems at the core interface between the high-temperature thermoelectric material and the metal electrode in high-temperature thermoelectric devices: (1) The compatibility of the heterogeneous interface is poor. Most thermoelectric materials belong to the category of ceramics, and there are physical property differences such as crystal structure, thermal expansion coefficient, and work function with the metal electrode. Poor interface compatibility easily increases the contact resistance of this interface and is prone to structural failure. (2) Traditional high-temperature connection processes are likely to cause damage to thermoelectric materials. For thermoelectric materials that require high-temperature service, their connection temperature is often higher than the service temperature, and too high a connection temperature is likely to cause thermal damage to the materials. (3) Element diffusion is severe at the thermoelectric material / metal electrode interface during high-temperature connection and service, resulting in continuous deterioration of the performance and bonding of the heterogeneous interface.
[0027] In view of the problems existing in the above-mentioned related art, the present embodiment provides a connection method for a high-temperature thermoelectric material and a metal electrode, including:
[0028] Step S1: Assemble a high-temperature thermoelectric material, an intermediate layer, and a metal electrode material in sequence from top to bottom to obtain an assembled part; wherein, the material of the intermediate layer is a high-entropy MAX phase, and the high-entropy MAX phase is M n+1 AX n; M is selected from at least one element of Group IIIB, Group IVB, Group VB and Group VIB elements, A is selected from at least two main group elements of Group IIIA, Group IVA and Group VIII elements, at least one of the at least two main group elements is selected from at least one of Group IIIA and Group IVA elements, X is selected from at least one of C, N and B elements, and n is an integer from 1 to 3; the high-temperature thermoelectric material includes at least one of Half-Heusler thermoelectric material, PbTe, SiGe and La2Te3;
[0029] Step S2: Heat the assembly to a preset temperature under a preset pressure, keep it warm for a preset time, and then cool it to room temperature to obtain a high-temperature thermoelectric material / metal joint.
[0030] In the embodiment of the present invention, a high-entropy MAX phase is used as the connection intermediate layer. By designing a low-melting-point liquid phase at the A site, low-temperature interconnection between the thermoelectric material and the metal electrode and element diffusion blocking are realized, and good service stability at high temperature at the interface is achieved. Among them, the MAX phase has both the characteristics of metals and ceramics, has good mechanical properties, high thermal conductivity, high thermal stability and corrosion resistance, and is an excellent intermediate layer for interconnecting high-temperature thermoelectric materials and metal electrodes. At the same time, the MAX phase can be elementally modified at the M site or A site to achieve solid solution high-entropyization. By using the diffusion retardation effect of the high-entropy design at the connection interface, the atomic diffusion rate is reduced, thereby suppressing excessive element diffusion during the connection or service process of the high-temperature thermoelectric material / metal electrode joint. Third, by designing Group IIIA, Group IVA and Group VIII elements (such as Sn, Ge, Al) with lower melting points at the A site in the MAX phase, a liquid phase can be formed during the connection process, eliminating the initial connection gap and providing a transmission channel for the connection process, greatly reducing the connection temperature. Compared with the related technology, the high-temperature thermoelectric material / metal joint prepared by the method provided in the embodiment of the present invention has a smaller interface resistance and higher strength.
[0031] In some embodiments of the present invention, in the step S1, the Half-Heusler thermoelectric material is selected from at least one of ZrNiSn, TiNiSn, NiFeSb, FeNbSb, ZrCoSb, TiCoSb and HfCoSb.
[0032] In some embodiments of the present invention, in the step S1, the metal electrode material is selected from at least one of W, W alloy, Mo, Mo alloy, Cu, Cu alloy, Ni and Ni alloy.
[0033] In some embodiments of the present invention, in the step S1, the thickness of the high-temperature thermoelectric material is 4 mm to 20 mm, the thickness of the intermediate layer is 0.1 mm to 1 mm, and the thickness of the metal electrode material is 0.3 mm to 4 mm.
[0034] In some embodiments of the present invention, in step S1, the preparation method of the intermediate layer includes:
[0035] Step S11: After mixing the corresponding single element of M, the corresponding single element of A, and the corresponding single element of X in the MAX phase in a molar ratio of (n + 1):1:n, perform ball milling to obtain intermediate layer powder; n+1 AX n In the MAX phase, the corresponding single element of M, the corresponding single element of A, and the corresponding single element of X are mixed in a molar ratio of (n + 1):1:n, and then ball milled to obtain intermediate layer powder;
[0036] Step S12: Press the intermediate layer powder to obtain the intermediate layer.
[0037] In some embodiments of the present invention, in step S11, the rotation speed of the ball milling is 100 rpm to 150 rpm, and the time is 8 h to 12 h.
[0038] In some embodiments of the present invention, in step S12, the pressure of the pressing is 10 MPa to 70 MPa, and the time is 5 min to 15 min.
[0039] In some embodiments of the present invention, in step S2, the preset pressure is 1 MPa to 70 MPa, the preset temperature is 700 °C to 1150 °C, and the preset time is 5 min to 120 min.
[0040] The present invention will be further described below with specific embodiments.
[0041] Example 1
[0042] A1: After mixing the single elements V, Sn, Ge and C powder in a molar ratio of 2:0.5:0.5:1, place them in a ball mill, add absolute ethanol to the ball mill, and perform ball milling under the protection of nitrogen to obtain intermediate layer powder; the rotation speed of the ball milling is 140 rpm, and the time is 8 h to 12 h.
[0043] A2: Press the intermediate layer powder to obtain a sheet-like intermediate layer; wherein, the pressure of the pressing is 40 MPa, the time is 10 min, and the thickness of the sheet-like intermediate layer is 0.3 mm.
[0044] A3: Mechanically polish the high-temperature thermoelectric material and the metal electrode material successively with 80#, 400#, 800#, and 1200# metallographic sandpaper; then place the polished high-temperature thermoelectric material and metal electrode material in acetone, and use ultrasonic method to clean and remove surface impurities and oil stains. Finally, dry at 40 °C for 40 min and perform drying treatment for standby; wherein, the material of the high-temperature thermoelectric material is SiGe, and the material of the metal electrode material is W.
[0045] Example 2
[0046] B1. Assemble the high-temperature thermoelectric material, the sheet-shaped intermediate layer, and the provided metal electrode material in sequence from top to bottom to obtain an assembly; wherein, the high-temperature thermoelectric material is made of SiGe, in the shape of a sheet, with a thickness of 4 mm, the metal electrode material is made of W, in the shape of a sheet, with a thickness of 1 mm; the sheet-shaped intermediate layer is the sheet-shaped intermediate layer prepared in Example 1.
[0047] B2. Place the assembly in a hot pressing and diffusion welding furnace, heat the assembly to a preset temperature under a preset pressure, keep it warm for a preset time, and then cool it to room temperature to obtain a high-temperature thermoelectric material / metal joint; wherein, the preset pressure is 20 MPa, the preset temperature is 1000 °C, and the preset time is 20 min.
[0048] Comparative Example 1
[0049] The difference from Example 2 is that the material of the sheet-shaped intermediate layer in step B1 is Al 0.3 CoCrFeNi. Al 0.3 All the constituent elements of the CoCrFeNi high-entropy alloy are metals, and their existence form is metallic bond, which is incompatible with the structure of the thermoelectric material. The constituent elements of the A-site and X-site in the high-entropy MAX phase used in Example 2 include non-metals, and M-X forms a strong covalent bond, having high stability, and M-A forms a metallic bond, having excellent electrical conductivity. The combination of ceramic and metal characteristics makes its compatibility with both the thermoelectric material and the electrode material very good. In addition, for alloy materials, their electrical conductivity decreases after high-entropy alloying, while after high-entropy alloying of the MAX phase, it still has good electrical conductivity as an interlayer for interconnecting the thermoelectric material and the electrode material. Compared with the Al 0.3 CoCrFeNi high-entropy alloy used in Comparative Example 1, the high-entropy MAX used in the embodiment of the present invention has a smaller interface resistance and higher strength than the Al 0.3 CoCrFeNi high-entropy alloy used in Comparative Example 1 when preparing the high-temperature thermoelectric material / metal joint in the embodiment of the present invention.
[0050] Comparative Example 2
[0051] The difference from Example 2 is that the material of the sheet-shaped intermediate layer in step B1 is FeCoNiCrMo. All the constituent elements of the FeCoNiCrMo high-entropy alloy are metals, and their existence form is metallic bond, which is incompatible with the structure of the thermoelectric material.
[0052] Experimental Example
[0053] Perform scanning electron microscope characterization on the high-temperature thermoelectric material / metal joints prepared in Example 2 and Comparative Examples 1 to 2, and the results are shown in Figures 1 to 3 , from Figure 1It can be seen that a good connection is formed for the high-temperature thermoelectric material / metal joint prepared in Example 2. The formation of W whiskers on the W side can further enhance the connection strength of the joint. From Figure 2 It can be seen that a large number of holes appear in the high-temperature thermoelectric material / metal joint prepared in Comparative Example 1. Due to the intense diffusion of the Si element, a brittle compound WSi2 is formed on one side of the electrode W, which affects the connection strength of the joint. From Figure 3 It can be seen that cracks parallel to the SiGe base material are generated in the high-temperature thermoelectric material / metal joint prepared in Comparative Example 2, and the cracks penetrate the entire interior of the joint, failing to form a good connection.
[0054] The test results of the room-temperature shear strength, high-temperature shear strength (at 1000 °C), and interfacial contact resistance of the high-temperature thermoelectric material / metal joints prepared in Example 2 and Comparative Examples 1 to 2 are shown in Table 1. It can be seen from Table 1 that compared with Comparative Examples 1 to 2, the high-temperature thermoelectric material / metal joint prepared in Example 2 has a higher room-temperature shear strength, a higher high-temperature shear strength, and a lower interfacial contact resistance.
[0055] Table 1
[0056]
[0057] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will all fall within the protection scope of the present invention.
Claims
1. A method for connecting a high-temperature thermoelectric material and a metal electrode, characterized in that Including: Step S1: Assemble the high-temperature thermoelectric material, the intermediate layer, and the metal electrode material in sequence from top to bottom to obtain an assembled component; wherein, the material of the intermediate layer is a high-entropy MAX phase, and the high-entropy MAX phase is M n+1 AX n ; M is selected from at least one of the elements in Group IIIB, Group IVB, Group VB, and Group VIB; A is selected from at least two main group elements in Group IIIA, Group IVA, and Group VIII, and at least one of the at least two main group elements is selected from at least one of the elements in Group IIIA and Group IVA; X is selected from at least one of the elements C, N, and B; n is an integer from 1 to 3; the high-temperature thermoelectric material includes at least one of Half-Heusler thermoelectric material, PbTe, SiGe, and La2Te3; Step S2: Heat the fitting to a preset temperature under a preset pressure, keep it warm for a preset time, and then cool it to room temperature to obtain a high-temperature thermoelectric material / metal joint.
2. The connection method of the high-temperature thermoelectric material and the metal electrode according to claim 1, characterized in that In the step S1, the Half-Heusler thermoelectric material is selected from at least one of ZrNiSn, TiNiSn, NiFeSb, FeNbSb, ZrCoSb, TiCoSb, and HfCoSb.
3. The method for connecting a high-temperature thermoelectric material and a metal electrode according to claim 1, characterized in that In the step S1, the metal electrode material is selected from at least one of W, W alloy, Mo, Mo alloy, Cu, Cu alloy, Ni, and Ni alloy.
4. The method for connecting a high-temperature thermoelectric material and a metal electrode according to claim 1, wherein In the step S1, the thickness of the high-temperature thermoelectric material is 4 mm to 20 mm.
5. The method for connecting a high-temperature thermoelectric material and a metal electrode according to claim 1, wherein In the step S1, the thickness of the intermediate layer is 0.1 mm to 1 mm.
6. The connection method of the high-temperature thermoelectric material and the metal electrode according to claim 1, characterized in that, In the step S1, the thickness of the metal electrode material is 0.3 mm to 4 mm.
7. The method for connecting a high-temperature thermoelectric material and a metal electrode according to claim 1, wherein In the step S1, the preparation method of the intermediate layer includes: Step S11: Mix the simple substances corresponding to M, A, and X in the n+1 n+1 AX n in a molar ratio of (n + 1):1:n, and then perform ball milling to obtain an intermediate layer powder; Step S12: Press the intermediate layer powder to obtain the intermediate layer.
8. The connection method of the high-temperature thermoelectric material and the metal electrode according to claim 7, characterized in that, In the step S11, the rotation speed of the ball milling process is 100 rpm to 150 rpm, and the time is 8 h to 12 h.
9. The method for connecting a high-temperature thermoelectric material and a metal electrode according to claim 7, characterized in that, In the step S12, the pressure of the pressing process is 10 MPa to 70 MPa, and the time is 5 min to 15 min.
10. The connection method of the high-temperature thermoelectric material and the metal electrode according to claim 1, characterized in that, In the step S2, the preset pressure is 1 MPa to 70 MPa, the preset temperature is 700 °C to 1150 °C, and the preset time is 5 min to 120 min.