Design method for alleviating interface stress of multilayer heterogeneous materials in thermoelectric power generation devices

Abstract

The present invention proposes a design method for alleviating the interface stress of multilayer heterogeneous materials in thermoelectric power generation devices, wherein the high temperature end of the thermoelectric arm is chamfered or rounded, and the first-level conductive transition layer connected to it is connected in a concave surface, and the phase change material is filled between the two; the other end face of the first-level conductive transition layer is connected to the remaining conductive transition layers, and the parameters of these conductive transition layer materials are gradually changed; the outermost conductive transition layer is connected to the conductive electrode; the conductive electrode is connected to the concave insulating ceramic through an outward convex configuration, and the phase change material is filled between the two. This method can reduce the thermal stress of the interface of heterogeneous materials of thermoelectric power generation devices in a large temperature gradient service environment, reduce the damage to the high temperature end of the thermoelectric device caused by the concentration of stress on the interface of heterogeneous materials during engineering application, and improve the service stability and reliability of the thermoelectric device.

Description

Technical Field

[0001] The invention relates to the field of thermoelectric device structure design, and in particular to a design method for alleviating interface stress of multilayer heterogeneous materials of a thermoelectric power generation device. Background Art

[0002] Thermoelectric conversion technology uses the Seebeck effect to directly convert waste heat into electrical energy. As a green and environmentally friendly way of energy production, it has attracted widespread attention from academia and industry. Thermoelectric conversion technology has significant advantages such as small size, all-solid state (no moving parts, no working medium), noise-free operation, and no emissions. It has shown important application potential in the fields of special power sources and green energy.

[0003] Due to the Seebeck effect of the material, the carriers in the thermoelectric material move and accumulate rapidly under the action of the temperature difference, forming a thermoelectric potential. The N-type thermoelectric arm and the P-type thermoelectric arm are connected in series / parallel through electrodes and other materials, and further integrated between electrically insulating and thermally conductive ceramic plates to form a thermoelectric device. In order to achieve a higher thermoelectric energy conversion efficiency, thermoelectric power generation devices usually need to serve for a long time under large temperature gradient conditions. However, differences in thermal expansion coefficients and high structural loads will induce changes in the composition and microstructure of each component material in the device, resulting in gradual degradation of the structure and function of the device, and even failure. A large number of practical application cases have shown that under high temperature and high load service environments, element diffusion often occurs at the interface between the high-temperature end electrode material and the thermoelectric material in the thermoelectric device, causing the device performance to decay; in addition, the difference in thermodynamic properties of the two materials and poor connectivity result in low connection strength at the heterogeneous interface, making the thermoelectric device very prone to heterogeneous interface damage during high-temperature service, which seriously hinders the further engineering application of thermoelectric power generation devices.

[0004] In order to solve the problem of good connection between thermoelectric materials and electrode materials and high-temperature interface stability, an appropriate transition layer can be introduced at the interface of the two materials or a special connection process can be used. For example, for bismuth telluride-based thermoelectric devices, nickel can be plated between the bismuth telluride thermoelectric arm and the welding surface as a transition layer, which can improve the wettability of the material and the solder, thereby improving the connection performance between the thermoelectric arm and the electrode material. In terms of process, the thermal spraying process can increase the bonding strength of the heterogeneous interface in thermoelectric devices from 10MPa under traditional electrochemical deposition or electroless plating processes to 18~24MPa. However, the existing methods are highly dependent on specific materials and processes, and thermoelectric devices will still gradually produce interface cracks in long-term high-temperature service environments, affecting the thermoelectric output performance. Therefore, a general design strategy is urgently needed to alleviate the stress concentration at the interface of heterogeneous materials in thermoelectric devices and slow down the expansion of heterogeneous material interface cracks at the high-temperature end of the device, thereby improving the reliability of interface connection and promoting the long-term stable scale engineering application of thermoelectric devices. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention proposes a design method for alleviating the interface stress of multilayer heterogeneous materials in a thermoelectric power generation device, and proposes a thermoelectric power generation device. This method can reduce the thermal stress of the heterogeneous material interface of the thermoelectric power generation device in a large temperature gradient service environment, reduce the damage to the high temperature end of the thermoelectric device caused by the stress concentration of the heterogeneous material interface during the engineering application process, and improve the service stability and reliability of the thermoelectric device.

[0006] The technical solution of the present invention is:

[0007] A design method for alleviating interface stress of multilayer heterogeneous materials in a thermoelectric power generation device comprises the following steps:

[0008] Step 1: Design the end surface of the high-temperature end of the thermoelectric arm to have a circular arc chamfer or a convex circular arc end surface; according to the design form of the end surface of the high-temperature end of the thermoelectric arm, design the butt joint surface between the first-level conductive transition layer and the high-temperature end of the thermoelectric arm accordingly;

[0009] Step 2: Calculate the minimum gap between the high-temperature end surface of the thermoelectric arm and the first-level conductive transition layer based on the difference in thermal deformation between the thermoelectric arm material and the first-level conductive transition layer material under the service temperature gradient. :

[0010]

[0011] in, is the thermal expansion coefficient of the thermoelectric arm material, is the service temperature gradient, is the thickness of the thermoelectric arm along the temperature gradient direction, is the thermal expansion coefficient of the first-level conductive transition layer material, is the overall thickness of the first-level conductive transition layer;

[0012] Step 3: According to the service temperature of the high temperature end of the thermoelectric arm, a first phase change material is selected and filled in the gap between the end surface of the high temperature end of the thermoelectric arm and the first-level conductive transition layer; when the temperature is lower than the service temperature of the high temperature end of the thermoelectric arm, the physical state of the first phase change material is solid; when the temperature is higher than or equal to the service temperature of the high temperature end of the thermoelectric arm, the physical state of the first phase change material is liquid with conductive properties;

[0013] Step 4: A transition is achieved between the first phase change material and the conductive electrode through an n-level conductive transition layer with a gradient material property, and the thermal expansion coefficient of the n-level conductive transition layer is designed according to the difference in material property parameters between the first-level conductive transition layer and the conductive electrode, so that the thermal stress between adjacent conductive transition layers and the thermal stress between the n-level conductive transition layer and the conductive electrode are lower than the set requirements;

[0014] Step 5: Design the end face of the conductive electrode facing the insulating ceramic to have a circular arc chamfer or a convex circular arc end face; and design the butt joint surface of the insulating ceramic and the conductive electrode accordingly according to the design form of the end face of the conductive electrode facing the insulating ceramic;

[0015] Step 6: Calculate the minimum gap between the conductive electrode and the insulating ceramic according to the difference in thermal deformation between the insulating ceramic material and the conductive electrode material under the service temperature gradient. :

[0016]

[0017] in, is the thermal expansion coefficient of the insulating ceramic material, is the overall thickness of the insulating ceramic, is the overall thickness of the conductive electrode, is the thermal expansion coefficient of the conductive electrode material;

[0018] Step 7: According to the service temperature of the high temperature end of the thermoelectric arm, select a second phase change material, and fill the second phase change material in the gap between the conductive electrode and the insulating ceramic; when the temperature is lower than the service temperature of the high temperature end of the thermoelectric arm, the physical state of the second phase change material is solid, and when the temperature is greater than or equal to the service temperature of the high temperature end of the thermoelectric arm, the physical state of the second phase change material is liquid with conductive properties.

[0019] Furthermore, in step 4, the specific process of designing the thermal expansion coefficient of the n-level conductive transition layer is:

[0020] According to the formula

[0021]

[0022] Calculate the thermal stress between the first conductive transition layer and the conductive electrode ,in is the Poisson’s ratio of the first-level conductive transition layer material, is the Young's modulus of the first-level conductive transition layer material, is the thermal expansion coefficient of the conductive electrode material;

[0023] According to thermal stress And the setting requirements, determine n, so that Not greater than the stated requirements;

[0024] According to the formula

[0025]

[0026] Calculate the thermal expansion coefficient of the j-th conductive transition layer material , j=1, 2,…, n.

[0027] Furthermore, the middle area of ​​the end surface of the high-temperature end of the thermoelectric arm is a plane, and the intersection area with the side wall of the high-temperature end of the thermoelectric arm is transitioned through an arc chamfer.

[0028] Furthermore, the end surface of the high-temperature end of the thermoelectric arm is designed as a convex arc end surface as a whole, or a plurality of spherical protrusions are designed on the end surface of the high-temperature end of the thermoelectric arm.

[0029] Furthermore, the surface roughness of the end surface of the high-temperature end of the thermoelectric arm and the butt surface between the first-level conductive transition layer and the high-temperature end of the thermoelectric arm is lower than Ra0.1.

[0030] Furthermore, the middle area of ​​the end surface of the conductive electrode facing the insulating ceramic is a plane, and the intersection area with the side wall of the conductive electrode is transitioned by an arc chamfer.

[0031] Furthermore, the end surface of the conductive electrode opposite to the insulating ceramic is designed as a convex arc end surface as a whole, or a plurality of spherical protrusions are designed on the end surface of the conductive electrode opposite to the insulating ceramic.

[0032] Furthermore, the surface roughness of the end faces of the conductive electrode and the insulating ceramic facing each other and the butt joint surface of the insulating ceramic and the conductive electrode is lower than Ra0.1.

[0033] Furthermore, adjacent conductive transition layers and the n-th conductive transition layer and the conductive electrode are planarly matched and connected by a welding process.

[0034] The present invention also proposes a temperature difference power generation device, including a thermoelectric arm, a conductive electrode, and an insulating ceramic, and a multi-level conductive transition layer is arranged between the high-temperature end of the thermoelectric arm and the conductive electrode; the matching relationship between the thermoelectric arm and the multi-level conductive transition layer, the thermal expansion coefficient of the multi-level conductive transition layer and the matching relationship between the conductive electrode and the insulating ceramic are determined according to the above-mentioned design method.

[0035] Beneficial effects:

[0036] Compared with the prior art, the present invention has the following advantages:

[0037] (1) After the high-temperature end of the thermoelectric arm of the present invention is provided with an arc chamfer or designed as a convex arc end face, the stress concentration at the high-temperature end can be reduced; in a long-term high-temperature service environment, the gap between the high-temperature end of the thermoelectric arm and the first-level conductive transition layer can not only accommodate the phase change material, but also this gap can reduce the crack propagation between heterogeneous materials, produce a crack arresting effect, and thus improve the long-term service stability of the thermoelectric device.

[0038] (2) Through the design of the present invention, the thermal stress between the two-phase interface can be released, which can alleviate the device function failure caused by damage to the high-temperature end of the thermoelectric arm during the service process of the thermoelectric device.

[0039] (3) Through theoretical calculations, a gradient design of material properties is carried out for the multi-level conductive transition layer at the high-temperature end of the thermoelectric arm. This can effectively reduce the thermal stress between each level of the conductive transition layer and between the conductive electrode, thereby reducing the interface damage of the thermoelectric device during long-term service.

[0040] (4) This design method can adjust the configuration complexity of the high-temperature end of the thermoelectric arm according to the boundary constraints of the thermoelectric device during application, thereby taking into account the stress relief of the high-temperature end of the thermoelectric device and the requirements of the installation conditions of the thermoelectric device.

[0041] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0043] Figure 1 : The structural design diagram of the high temperature end of the thermoelectric arm in the present invention;

[0044] Among them: 1. thermoelectric arm; 2. first phase change material; 3. conductive transition layer group; 3.1. first level conductive transition layer; 3.2. second level conductive transition layer; 3.9. ninth level conductive transition layer; 4. conductive electrode; 5. second phase change material; 6. insulating ceramic. DETAILED DESCRIPTION

[0045] Embodiments of the present invention are described in detail below. The embodiments are exemplary and intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0046] Thermoelectric devices (i.e., thermoelectric power generation devices) generally include thermoelectric arms, conductive electrodes, and insulating substrates. The thermoelectric arms are usually rectangular or cylindrical bodies made of thermoelectric materials, and the electrodes and insulating substrates are usually plate-like sheets. When there is a temperature difference between the two ends of the N-type and P-type thermoelectric arms, the carriers inside them move rapidly and accumulate to form an electromotive force. The N-type and P-type thermoelectric arm elements are connected through electrode materials and integrated between insulating substrates. The heat flow is transmitted in a direction perpendicular to the ceramic plate, thereby forming a thermoelectric device.

[0047] Traditional thermoelectric devices have the problem of poor service stability at the interface of heterogeneous materials at the high-temperature end. To address this problem, this embodiment proposes a design method for alleviating the interface stress of multi-layer heterogeneous materials in thermoelectric power generation devices, wherein the high-temperature end of the thermoelectric arm is chamfered or rounded, and the first-level conductive transition layer connected to it is connected in a concave-convex manner, and phase change material is filled between the two; the other end face of the first-level conductive transition layer is connected to the remaining conductive transition layers, and the parameters of these conductive transition layer materials are gradient-changing; the outermost conductive transition layer is connected to the conductive electrode; the conductive electrode is connected to the concave insulating ceramic through a convex configuration, and phase change material is filled between the two.

[0048] The specific design method is as follows:

[0049] Step 1: Design the high-temperature end face of the thermoelectric arm to have a circular arc chamfer or a convex circular arc end face, so as to reduce the internal stress of the high-temperature end of the thermoelectric arm, avoid the stress concentration area, and avoid stress damage during high-temperature and high-load service.

[0050] like Figure 1 As shown, in this embodiment, the middle area of ​​the high-temperature end surface of the thermoelectric arm is a plane, and the intersection area with the side wall of the high-temperature end of the thermoelectric arm is transitioned by an arc chamfer, and the chamfer radius is 0.3mm. In addition, the high-temperature end surface of the thermoelectric arm can also be designed as a convex arc end surface as a whole, or a number of spherical protrusions can be designed on the high-temperature end surface of the thermoelectric arm to avoid stress concentration through arc surface design.

[0051] According to the design form of the end face of the high temperature end of the thermoelectric arm, the interface between the first-level conductive transition layer and the high temperature end of the thermoelectric arm is designed accordingly. In this embodiment, the interface between the first-level conductive transition layer and the high temperature end of the thermoelectric arm is designed as a concave surface structure with a flat center bottom and curved surfaces around. The other side of the first-level conductive transition layer is a flat surface for connecting with the second-level conductive transition layer.

[0052] The end surface of the high-temperature end of the thermoelectric arm and the interface between the first-level conductive transition layer and the high-temperature end of the thermoelectric arm should be smooth. In this embodiment, the surface roughness of the two is lower than Ra0.1.

[0053] Step 2: Calculate the minimum gap between the high-temperature end surface of the thermoelectric arm and the first-level conductive transition layer based on the difference in thermal deformation between the thermoelectric arm material and the first-level conductive transition layer material under the service temperature gradient. .

[0054] The specific calculation formula is:

[0055]

[0056] in, is the thermal expansion coefficient of the thermoelectric arm material, which is ; is the service temperature gradient, that is, the temperature difference between the high temperature end and the low temperature end when the thermoelectric arm is working. In this embodiment, the temperature of the low temperature end of the thermoelectric arm is 273K and the temperature of the high temperature end is 973K when the thermoelectric arm is working. ; is the thickness of the thermoelectric arm along the temperature gradient direction, that is, Figure 1 In the y direction, in this embodiment ; is the thermal expansion coefficient of the first-level conductive transition layer material. ; is the overall thickness of the first-level conductive transition layer. .

[0057] Therefore, the minimum gap reserved between the high-temperature end surface of the thermoelectric arm and the first-level conductive transition layer in this embodiment is

[0058]

[0059] Step 3: According to the service temperature of the high temperature end of the thermoelectric arm, select the first phase change material and fill it in the gap between the end surface of the high temperature end of the thermoelectric arm and the first-level conductive transition layer. When the temperature is lower than the service temperature of the high temperature end of the thermoelectric arm, the physical state of the first phase change material is solid. When the temperature is greater than or equal to the service temperature of the high temperature end of the thermoelectric arm, the physical state of the first phase change material is liquid with conductive properties, and the thermal stress of the interface of heterogeneous materials under large temperature difference is released through fluidity.

[0060] In this embodiment, the service temperature of the high temperature end of the thermoelectric arm is 973K, so the copper-tin compound is selected as the first phase change material: when the temperature is less than 973K, its physical state is solid; when the temperature is equal to 973K, its physical state is conductive liquid.

[0061] Step 4: A transition is achieved between the first phase change material and the conductive electrode through an n-level conductive transition layer with a gradient material property, and the thermal expansion coefficient of the n-level conductive transition layer is designed according to the difference in material property parameters between the first-level conductive transition layer and the conductive electrode, so that the thermal stress between adjacent conductive transition layers and the thermal stress between the n-level conductive transition layer and the conductive electrode are lower than the set requirements.

[0062] In this embodiment, adjacent conductive transition layers and the n-th conductive transition layer and the conductive electrode are connected by conventional welding process.

[0063] The specific process of designing the thermal expansion coefficient of the n-level conductive transition layer is:

[0064] According to the formula

[0065]

[0066] Calculate the thermal stress between the first conductive transition layer and the conductive electrode ,in is the Poisson’s ratio of the first-level conductive transition layer material, is the Young's modulus of the first-level conductive transition layer material. is 0.2, is 172 GPa, is the thermal expansion coefficient of the conductive electrode material.

[0067] In order to reduce the high-temperature thermal stress at the interface of heterogeneous materials in thermoelectric devices, n (n ≥ 2) level conductive transition layers (the thermal expansion coefficient of the material is gradient) with gradient material properties are filled between the first phase change material and the conductive electrode, so that the thermal stress between the interfaces of heterogeneous materials (i.e., the thermal stress between adjacent conductive transition layers and the thermal stress between the nth level conductive transition layer and the conductive electrode) is reduced to no more than the thermal stress 1 / n of. That is, according to the thermal stress And the setting requirements determine n, so that Not greater than the stated requirements.

[0068] By calculating the difference in thermal expansion coefficient between the first-level conductive transition layer material and the conductive electrode material, according to the formula

[0069]

[0070] Calculate the thermal expansion coefficient of the j-th conductive transition layer material , j=1, 2,…, n.

[0071] In this embodiment, the conductive electrode material is copper, and its thermal expansion coefficient is , according to the formula

[0072]

[0073] Calculate the thermal stress between the first conductive transition layer and the conductive electrode Since this embodiment requires that the thermal stress of the interface of the heterogeneous connection material at the high temperature end of the thermoelectric arm be reduced to below 85 MPa, n=9 is designed, that is, 9 levels of conductive transition layers with gradient material properties are used, and the thermal expansion coefficient of the material of the j-th conductive transition layer is

[0074]

[0075] Step 5: The mating surface between the conductive electrode and the n-th conductive transition layer is a plane, while the back end surface of the conductive electrode is designed with a circular arc chamfer or a convex circular arc end surface, thereby reducing internal stress and avoiding stress concentration areas.

[0076] Like the high-temperature end face of the thermoelectric arm, in this embodiment, the middle area of ​​the back end face of the conductive electrode is a plane, and the intersection area with the side wall of the conductive electrode is transitioned by an arc chamfer, and the chamfer radius is 0.3mm. In addition, the back end face of the conductive electrode can also be designed as a convex arc end face as a whole, or a number of spherical protrusions can be designed on the back end face of the conductive electrode to avoid stress concentration through arc surface design.

[0077] According to the design of the back end surface of the conductive electrode, the butt joint surface of the insulating ceramic and the conductive electrode is designed accordingly. In this embodiment, the butt joint surface of the insulating ceramic and the conductive electrode is designed as a concave surface structure with a flat center bottom and curved surfaces around.

[0078] The back end surface of the conductive electrode and the butt surface between the insulating ceramic and the conductive electrode should be smooth. In this embodiment, the surface roughness of the two surfaces is lower than Ra0.1.

[0079] Step 6: Calculate the minimum gap between the conductive electrode and the insulating ceramic according to the difference in thermal deformation between the insulating ceramic material and the conductive electrode material under the service temperature gradient. The specific formula is

[0080]

[0081] in, is the thermal expansion coefficient of the insulating ceramic material. In this embodiment, , is the overall thickness of the insulating ceramic (in the thickness direction Figure 1 y direction), in this embodiment , is the overall thickness of the conductive electrode (in the thickness direction Figure 1 y direction), in this embodiment , then the minimum gap between the conductive electrode and the insulating ceramic is for

[0082]

[0083] Step 7: According to the service temperature of the high temperature end of the thermoelectric arm, select the second phase change material, and fill the second phase change material in the gap between the conductive electrode and the insulating ceramic. When the temperature is lower than the service temperature of the high temperature end of the thermoelectric arm, the physical state of the second phase change material is solid, and when the temperature is greater than or equal to the service temperature of the high temperature end of the thermoelectric arm, the physical state of the second phase change material is liquid with conductive properties, and the thermal stress of the heterogeneous material interface under large temperature difference is released through fluidity.

[0084] In this embodiment, the second phase change material is the same as the first phase change material, and both use a copper-tin compound with a phase change temperature of 973 K. When the temperature is less than 973 K, the physical state is solid; when the temperature is equal to 973 K, the physical state is conductive liquid.

[0085] Finally, according to the requirements of the actual installation conditions of the thermoelectric device, the thermoelectric arm, the first-level conductive transition layer, and the insulating ceramic are fixed separately or connected with other insulating materials to meet the installation requirements of the overall thermoelectric device.

[0086] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A design method for alleviating the interface stress of multilayer heterogeneous materials in a thermoelectric power generation device, characterized in that: The following steps are involved: Step 1: Design the end surface of the high-temperature end of the thermoelectric arm to have a circular arc chamfer or a convex circular arc end surface; according to the design form of the end surface of the high-temperature end of the thermoelectric arm, design the butt joint surface between the first-level conductive transition layer and the high-temperature end of the thermoelectric arm accordingly; Step 2: Calculate the minimum gap between the high-temperature end surface of the thermoelectric arm and the first-level conductive transition layer based on the difference in thermal deformation between the thermoelectric arm material and the first-level conductive transition layer material under the service temperature gradient. : in, is the thermal expansion coefficient of the thermoelectric arm material, is the service temperature gradient, is the thickness of the thermoelectric arm along the temperature gradient direction, is the thermal expansion coefficient of the first-level conductive transition layer material, is the overall thickness of the first-level conductive transition layer; Step 3: According to the service temperature of the high temperature end of the thermoelectric arm, a first phase change material is selected and filled in the gap between the end surface of the high temperature end of the thermoelectric arm and the first-level conductive transition layer; when the temperature is lower than the service temperature of the high temperature end of the thermoelectric arm, the physical state of the first phase change material is solid; when the temperature is higher than or equal to the service temperature of the high temperature end of the thermoelectric arm, the physical state of the first phase change material is liquid with conductive properties; Step 4: A transition is achieved between the first phase change material and the conductive electrode through an n-level conductive transition layer with a gradient material property, and the thermal expansion coefficient of the n-level conductive transition layer is designed according to the difference in material property parameters between the first-level conductive transition layer and the conductive electrode, so that the thermal stress between adjacent conductive transition layers and the thermal stress between the n-level conductive transition layer and the conductive electrode are lower than the set requirements; Step 5: Design the end face of the conductive electrode facing the insulating ceramic to have a circular arc chamfer or a convex circular arc end face; and design the butt joint surface of the insulating ceramic and the conductive electrode accordingly according to the design form of the end face of the conductive electrode facing the insulating ceramic; Step 6: Calculate the minimum gap between the conductive electrode and the insulating ceramic according to the difference in thermal deformation between the insulating ceramic material and the conductive electrode material under the service temperature gradient. : in, is the thermal expansion coefficient of the insulating ceramic material, is the overall thickness of the insulating ceramic, is the overall thickness of the conductive electrode, is the thermal expansion coefficient of the conductive electrode material; Step 7: According to the service temperature of the high temperature end of the thermoelectric arm, select a second phase change material, and fill the second phase change material in the gap between the conductive electrode and the insulating ceramic; when the temperature is lower than the service temperature of the high temperature end of the thermoelectric arm, the physical state of the second phase change material is solid, and when the temperature is greater than or equal to the service temperature of the high temperature end of the thermoelectric arm, the physical state of the second phase change material is liquid with conductive properties.

2. The design method according to claim 1, characterized in that: In step 4, the specific process of designing the thermal expansion coefficient of the n-level conductive transition layer is: According to the formula Calculate the thermal stress between the first conductive transition layer and the conductive electrode ,in is the Poisson’s ratio of the first-level conductive transition layer material, is the Young's modulus of the first-level conductive transition layer material, is the thermal expansion coefficient of the conductive electrode material; According to thermal stress And the setting requirements, determine n, so that Not greater than the stated requirements; According to the formula Calculate the thermal expansion coefficient of the j-th conductive transition layer material , j=1, 2,…, n.

3. The design method according to claim 1 or 2, characterized in that: The middle area of ​​the end surface of the high-temperature end of the thermoelectric arm is a plane, and the intersection area with the side wall of the high-temperature end of the thermoelectric arm is transitioned through an arc chamfer.

4. The design method according to claim 1 or 2, characterized in that: The high-temperature end surface of the thermoelectric arm is designed as a convex arc end surface as a whole, or a plurality of spherical protrusions are designed on the high-temperature end surface of the thermoelectric arm.

5. The design method according to claim 1 or 2, characterized in that: The surface roughness of the end surface of the high-temperature end of the thermoelectric arm and the butt surface between the first-level conductive transition layer and the high-temperature end of the thermoelectric arm is lower than Ra0.

1.

6. The design method according to claim 1 or 2, characterized in that: The middle area of ​​the end surface of the conductive electrode opposite to the insulating ceramic is a plane, and the intersection area with the side wall of the conductive electrode is transitioned by an arc chamfer.

7. The design method according to claim 1 or 2, characterized in that: The end surface of the conductive electrode opposite to the insulating ceramic is designed as a convex arc end surface as a whole, or a plurality of spherical protrusions are designed on the end surface of the conductive electrode opposite to the insulating ceramic.

8. The design method according to claim 1 or 2, characterized in that: The surface roughness of the end surface of the conductive electrode facing the insulating ceramic and the butt surface of the insulating ceramic and the conductive electrode is lower than Ra0.

1.

9. The design method according to claim 1 or 2, characterized in that: Adjacent conductive transition layers and the n-th conductive transition layer and the conductive electrode are planarly matched and connected by a welding process.

10. A thermoelectric power generation device, characterized in that: It includes a thermoelectric arm, a conductive electrode, and an insulating ceramic, and a multi-level conductive transition layer is arranged between the high-temperature end of the thermoelectric arm and the conductive electrode; the matching relationship between the thermoelectric arm and the multi-level conductive transition layer, the thermal expansion coefficient of the multi-level conductive transition layer, and the matching relationship between the conductive electrode and the insulating ceramic are determined according to the design method according to claim 1.

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