Discharge plasma sintering-brazing integrated device and process for thermoelectric device connection

Abstract

The invention relates to the technical field of welding, and particularly discloses a discharge plasma sintering-brazing integrated device and process for connection of thermoelectric devices, the discharge plasma sintering-brazing integrated device comprises a hearth, a carrying mechanism, a pressure head mechanism, a base mechanism, a clamping mechanism and a feeding pipe, and the interior of the hearth communicates with a vacuum pump. The pressure head mechanism comprises a pressure head body, a driving assembly, a graphite boss and an upper graphite column; the base mechanism comprises a base body and a lower graphite column; the feeding pipe is obliquely inserted into the hearth downwards from the outside of the hearth; the clamping mechanism comprises a clamping device and a power assembly. The carrying mechanism comprises a carrying platform and a transmission assembly. A mechanical system and an electric control unit are deeply fused, the spark plasma sintering-brazing integrated device is created for the first time, the sintering process and the brazing process are seamlessly integrated, the production efficiency and the yield are both improved, and the comprehensive manufacturing cost of thermoelectric devices is comprehensively reduced.

Description

Technical Field

[0001] This invention relates to the field of brazing equipment technology, specifically to an integrated device and process for connecting thermoelectric devices using discharge plasma sintering and brazing. Background Technology

[0002] Discharge plasma sintering is an advanced material sintering technology widely used in the fabrication of thermoelectric devices across various temperature ranges. It rapidly heats, densifies, and sintersects thermoelectric material alloy powder into the desired solid material under high-voltage pulsed current, reducing voids and pores, thereby improving important properties of thermoelectric devices such as thermal conductivity and electrical conductivity. Brazing is a welding process that uses a metal filler metal to join two or more substrates together at high temperatures. For thermoelectric devices, brazing effectively connects thermoelectric materials to other components (such as electrodes, thermally conductive materials, etc.), ensuring the mechanical strength and interfacial properties of the thermoelectric device, thus completing the assembly of the thermoelectric device.

[0003] However, discharge plasma sintering (SPSS) has certain limitations in thermoelectric device bonding. During SPSS, the heat distribution generated by the discharge may be uneven, leading to temperature differences and thermal gradients at the thermoelectric material / electrode interface. This can cause cracks, deformation, or other defects, especially in large-sized or complex-shaped thermoelectric devices. Simultaneously, welding processes also have limitations in thermoelectric device bonding, such as high interfacial thermal resistance, high interfacial resistance, and low bond strength. This results in uneven heat conduction, unstable current transmission, and short service life, thus affecting the long-term operational stability and efficiency of the entire thermoelectric device. The trend towards high-performance and high-yield thermoelectric devices in aerospace, electronics, and transportation equipment fields has led to the increasingly widespread application of SPSS and brazing composite processes in thermoelectric device fabrication. The SPSS and brazing composite process fully leverages the high-speed processing advantages of SPSS while also showcasing the high precision of brazing. This further densifies thermoelectric materials and compensates for the functional and performance deficiencies of brazed joints in thermoelectric devices, leveraging the performance advantages of both processes. SPSS and brazing composite processes have become an inevitable trend for the future development of the thermoelectric industry. Therefore, the combined process of discharge plasma sintering and brazing for the preparation of thermoelectric devices has important application value.

[0004] Discharge plasma sintering and brazing share common characteristics in their processing methods and principles, namely, temperature control under high vacuum conditions, which makes their organic combination possible. Currently, research reports on discharge plasma sintering and brazing in the thermoelectric device industry, both domestically and internationally, mainly focus on optimizing sintering processes and brazing parameters. Traditional characterization and analysis methods are used to study the physicochemical properties and microstructure evolution of thermoelectric device samples prepared by sintering followed by brazing. However, the brazed joints of thermoelectric devices prepared using this traditional two-step method exhibit unstable quality and low joint strength. Summary of the Invention

[0005] The purpose of this invention is to solve the technical problems of poor quality and short service life of thermoelectric devices prepared by discharge plasma sintering and brazing processes, and to provide an integrated discharge plasma sintering-brazing device and process for connecting thermoelectric devices.

[0006] To address the shortcomings of the aforementioned technical problems, the present invention adopts the following technical solution: an integrated discharge plasma sintering-brazing device for connecting thermoelectric devices, comprising a furnace chamber, a loading mechanism, a pressure head mechanism, a base mechanism, a clamping mechanism, and a feeding pipe, wherein a vacuum pump is connected inside the furnace chamber.

[0007] The pressure head mechanism includes a pressure head body, a drive assembly, a graphite boss, and an upper graphite column. The pressure head body can move vertically under the drive of the drive assembly, and the bottom of the pressure head body is connected to the upper graphite column through the graphite boss.

[0008] The base mechanism includes a base body and a lower graphite column. The base body is fixedly installed at the bottom of the furnace, and the lower graphite column is fixedly installed on the upper end face of the base body. The axes of the lower graphite column and the upper graphite column coincide. A processing groove is provided on the upper end face of the lower graphite column. The upper graphite column and the lower graphite column are connected to form a processing cavity.

[0009] The feeding pipe is inserted into the furnace from the outside of the furnace at a downward angle. The discharge end of the feeding pipe is located above the side of the processing tank, and the feed end of the feeding pipe is equipped with a shut-off valve.

[0010] The pressure head body and the base body are respectively connected to a pulsed DC power supply through a circuit to form a current loop for discharge plasma sintering.

[0011] The clamping mechanism includes a clamp and a power assembly. The clamp is located inside the furnace and can move horizontally under the drive of the power assembly and can open / close.

[0012] The loading mechanism includes a loading platform and a transmission assembly. The upper surface of the loading platform is on the same horizontal plane as the upper surface of the lower graphite column, and the loading platform can move horizontally under the drive of the transmission assembly.

[0013] As a further optimization of the discharge plasma sintering-brazing integrated device for connecting thermoelectric devices of the present invention: a temperature sensor is provided on the outer wall of the lower graphite column.

[0014] As a further optimization of the discharge plasma sintering-brazing integrated device for connecting thermoelectric devices of the present invention: the driving assembly includes a driving column and a transmission assembly. The driving column is located on the top of the pressure head body. The top of the furnace has a channel for the driving column to move up and down. The driving column has a capsule-shaped through hole arranged in the horizontal direction. A shaft is inserted through the capsule-shaped through hole. One end of the shaft is fixedly connected to the upper end of the crank arm. The lower end of the crank arm is connected to a rotating shaft. The rotating shaft is rotatably supported on the side wall of the furnace. A driven gear is fixedly sleeved on the rotating shaft. A driving rack that meshes with the driven gear is arranged below the driven gear. One end of the driving rack passes through the furnace and meshes with the driving gear. The driving gear is driven by a motor.

[0015] As a further optimization of the discharge plasma sintering-brazing integrated device for connecting thermoelectric devices of the present invention: the power component includes a worm gear drive shaft, a worm wheel, a rack and a servo motor. The worm gear drive shaft and the worm wheel are both disposed in the inner wall of the furnace. The worm gear drive shaft is connected to the worm wheel. One end of the rack passes through the side wall of the furnace and meshes with the worm wheel. The other end of the rack extends into the furnace and is connected to the gripper. The servo motor is used to drive the gripper to open / close.

[0016] As a further optimization of the discharge plasma sintering-brazing integrated device for connecting thermoelectric devices according to the present invention: the transmission assembly includes a transmission rack, a transmission gear, a transmission shaft, a first bevel gear, a second bevel gear, and a drive shaft. The transmission rack is mounted on the side wall of the furnace via a slide rail and can reciprocate in the horizontal direction. One end of the transmission rack is fixedly connected to the loading platform. The transmission shaft is vertically rotatably mounted inside the side wall of the furnace. The transmission gear is fixedly sleeved on the lower end of the transmission shaft and meshes with the transmission rack. The first bevel gear is fixedly sleeved on the upper end of the transmission shaft. The drive shaft is rotatably mounted in the horizontal direction through the side wall of the furnace. The end of the drive shaft located outside the furnace is connected to the power source. The second bevel gear is fixedly sleeved on the end of the drive shaft located inside the furnace and meshes with the first bevel gear.

[0017] As a further optimization of the discharge plasma sintering-brazing integrated device for connecting thermoelectric devices of the present invention: the upper graphite column and the graphite boss are connected by two connecting frames. The side wall of the upper graphite column is symmetrically provided with two grooves. The connecting frame consists of an upper frame, a lower frame and a vertical frame connecting the upper and lower frames. The lower frame is embedded in the groove, the vertical frame is attached to the outer wall of the upper graphite column, and the upper frame is fixedly connected to the graphite boss by bolts.

[0018] As a further optimization of the discharge plasma sintering-brazing integrated device for connecting thermoelectric devices according to the present invention: the furnace chamber includes, from the inside out, a heat reflective layer, a support layer and a heat insulation layer.

[0019] This invention also provides an integrated discharge plasma sintering-brazing connection process for thermoelectric devices, utilizing the aforementioned apparatus for connection processing, and the process includes the following:

[0020] Place a circular metal electrode block on the stage, the diameter of which matches the machining groove at the top of the lower graphite column;

[0021] Control the pressure head body to move upward so that the lower graphite column will not affect the material conveying of the feeding tube and ensure that there is no interference between the gripper and the platform;

[0022] The mechanically alloyed thermoelectric masterbatch mixed powder and brazing powder are sequentially fed into the processing groove at the top of the lower graphite column through the feeding pipe, and then the stop valve of the feeding pipe is closed.

[0023] Through the horizontal coordinated movement of the stage and the gripper, and the gripping and releasing action of the gripper, the circular metal electrode block on the stage is placed above the mixed powder and embedded in the processing tank.

[0024] Control the stage and gripper to return to the initial position, and at the same time lower the pressure head body to the set height to apply pre-pressure to the metal electrode block according to the process requirements;

[0025] Start the pulsed DC power supply, adjust the output current according to the process parameters, and complete the sintering-welding integrated forming.

[0026] This invention offers the following advantages: Compared to traditional thermoelectric device connection methods (such as welding and mechanical pressing), which involve complex steps, high manual labor time, and high costs, this invention deeply integrates the mechanical system and the electronic control unit, pioneering an integrated discharge plasma sintering-brazing device that seamlessly integrates the sintering and brazing processes. This device can continuously complete sintering and brazing within the same sealed cavity without requiring sample removal midway, completely eliminating the risk of contaminants such as oxygen and water vapor intrusion and ensuring interface cleanliness. Simultaneously, it significantly shortens the process chain, reduces manual intervention, and achieves a dual improvement in production efficiency and yield, comprehensively reducing the overall manufacturing cost of thermoelectric devices. Attached Figure Description

[0027] Figure 1 A schematic diagram of the integrated discharge plasma sintering-brazing device;

[0028] Figure 2 This is a schematic diagram of the power assembly structure;

[0029] Figure 3 This is a schematic diagram of the drive component.

[0030] Figure 4 Microstructure diagram of the TiNiSn / TiZrCuNi / AgCu / WCu joint after sintering-brazing treatment;

[0031] Marked in the image:

[0032] 1. Furnace chamber;

[0033] 101. Heat-reflective layer;

[0034] 102. Support layer;

[0035] 103. Insulation layer;

[0036] 2. Carrying mechanism;

[0037] 201. Cargo platform;

[0038] 202. Transmission components;

[0039] 3. Press head mechanism;

[0040] 301. Indenter body;

[0041] 302. Graphite boss;

[0042] 303. Graphite column;

[0043] 304, drive column;

[0044] 305. Capsule-shaped through-hole;

[0045] 306. Curved arm;

[0046] 307. Driven gear;

[0047] 308. Drive rack;

[0048] 309. Drive gear;

[0049] 4. Clamping mechanism;

[0050] 401. Gripper;

[0051] 402. Power components;

[0052] 4021. Worm gear drive shaft;

[0053] 4022, worm gear;

[0054] 4023, rack and pinion;

[0055] 5. Vacuum pump;

[0056] 6. Base mechanism;

[0057] 601. Base body;

[0058] 602. Lower graphite column;

[0059] 7. Feeding tube;

[0060] 8. Temperature sensor. Detailed Implementation

[0061] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0062] Integrated Discharge Plasma Sintering-Brazing Device

[0063] like Figure 1-3 As shown: A discharge plasma sintering-brazing integrated device for connecting thermoelectric devices, characterized in that it includes a furnace chamber 1, a loading mechanism 2, a pressure head mechanism 3, a base mechanism 6, a clamping mechanism 4, and a feeding pipe 7, and a vacuum pump 5 is connected inside the furnace chamber 1.

[0064] The furnace chamber 1 comprises, from the inside out, a heat-reflective layer 101, a support layer 102, and an insulation layer 103. The support layer 102 is the main load-bearing structure of the furnace wall, typically made of high-temperature resistant metal material, providing mechanical strength and rigid support for the entire furnace body. Its inner side is covered by the heat-reflective layer 101, which is composed of a polished metal material with high reflectivity. Its main function is to reflect the thermal radiation energy generated inside the furnace back to the sintering area, thereby reducing heat loss through the furnace wall in the form of radiation and improving thermal efficiency. The innermost layer is the insulation layer 103, which uses a lightweight ceramic fiber material with low thermal conductivity. Its porous structure effectively inhibits heat conduction, significantly reducing heat loss from the furnace wall. The three layers work synergistically to effectively isolate and maintain the high-temperature environment inside the furnace, ensuring the uniformity and stability of the thermal field during sintering, while also considering the strength of the furnace structure and the energy-saving insulation effect.

[0065] Vacuum pump 5 is connected to the furnace cavity of the sintering furnace via a vacuum pipeline made of stainless steel, and a flange connection is used to ensure a high vacuum seal between the pipeline and the furnace body interface. Vacuum pump 5 is configured with a common high vacuum unit suitable for SPS sintering furnaces, with the main pump being a molecular pump, such as the Pfeiffer HIPace 700, and the forepump being a rotary vane mechanical vacuum pump, such as the Leybold Trivac D 16B. During operation, the system first evacuates to a low vacuum using the forepump, and then the molecular pump evacuates the furnace cavity to the required high vacuum state, thereby effectively removing gases from the furnace and providing a clean and stable low-pressure environment for the discharge plasma sintering process. This prevents the material from oxidizing at high temperatures and is conducive to the uniform generation of plasma and the discharge activation between particles, ultimately ensuring the density and performance of the sintered products.

[0066] The pressure head mechanism 3 includes a pressure head body 301, a drive assembly, a graphite boss 302, and an upper graphite column 303. The pressure head body 301 can move vertically under the drive of the drive assembly. The bottom of the pressure head body 301 is connected to the upper graphite column 303 through the graphite boss 302.

[0067] The upper graphite column 303 and the graphite boss 302 are connected by two connecting frames. The side wall of the upper graphite column 303 is symmetrically provided with two grooves. The connecting frame consists of an upper frame, a lower frame, and a vertical frame connecting the upper and lower frames. The lower frame is embedded in the groove, and the vertical frame is attached to the outer wall of the upper graphite column 303. The upper frame is fixedly connected to the graphite boss 302 by bolts.

[0068] The drive assembly includes a drive column 304, which is located on the top of the pressure head body 301. The top of the furnace chamber 1 has a channel for the drive column 304 to move up and down. The drive column 304 has a capsule-shaped through hole 305 arranged in the horizontal direction. A shaft is inserted through the capsule-shaped through hole 305. One end of the shaft is fixedly connected to the upper end of the crank arm 306. The lower end of the crank arm 306 is connected to a rotating shaft. The rotating shaft is rotatably supported on the side wall of the furnace chamber 1. A driven gear 307 is fixedly sleeved on the rotating shaft. A drive rack 308 is arranged below the driven gear 307 and meshes with it. One end of the drive rack 308 extends out of the furnace chamber 1 and meshes with the driving gear 309. The driving gear 309 is driven by a motor.

[0069] Through the transmission action of the driving gear 309, the driving rack 308 is driven to move linearly, which in turn drives the driven gear 307 to rotate, causing the crank arm connecting shaft to revolve around the center of the gear and achieve constrained trajectory movement inside the capsule-shaped through hole 305; at the same time, with the help of the pulley group installed on the side of the cylindrical section of the support layer and the pressure head body 301, the pressure head body 301 is radially positioned, so that the pressure head body 301 only produces vertical displacement during the movement, thereby achieving its stable vertical feed function.

[0070] The base mechanism 6 includes a base body 601 and a lower graphite column 602. The base body 601 is fixedly installed at the bottom of the furnace chamber 1, and the lower graphite column 602 is fixedly installed on the upper end face of the base body 601. The axes of the lower graphite column 602 and the upper graphite column 303 coincide. A processing groove is provided on the upper end face of the lower graphite column 602. The upper graphite column 303 and the lower graphite column 602 are connected to form a processing cavity.

[0071] The lower graphite column 602 has a pair of symmetrical rectangular grooves on its cylindrical outer surface. Each groove contains a double L-shaped connecting bracket. The bottom end of each connecting bracket, away from the graphite column, has a threaded through hole. This hole is the same size and aligned with the threaded hole near the circumference of the base body 601, and is secured with bolts. The base body 601 is fixed in place. This connection method provides stable support and positioning for the lower graphite column 602. A temperature sensor 8 is installed on the outer wall of the lower graphite column 602.

[0072] The feeding pipe 7 is inserted into the furnace 1 from the outside of the furnace 1 at a downward angle. The discharge end of the feeding pipe 7 is located on the side above the processing tank, and the feed end of the feeding pipe 7 is equipped with a shut-off valve.

[0073] The feeding pipe 7 is welded to a long straight conduit at a 45° angle to the vertical direction and a short conduit at a vertical direction at the end, forming an integrated continuous feeding channel. A shut-off valve is provided on the side of the short conduit. Thermoelectric material and brazing powder enter through the opening at the upper end of the vertical short conduit. Under the action of gravity and external conveying, they pass through the short conduit and the inclined long straight conduit in sequence, and are finally accurately conveyed to the cylindrical groove at the top of the lower graphite column 602 to complete the filling operation. After the filling is completed, the shut-off valve is closed to cut off the connection between the feeding channel and the external environment, realize the reliable sealing of the sintering system, effectively prevent external gas from entering and maintain the stability of the atmosphere inside the cavity.

[0074] The pressure head body 301 and the base body 601 are respectively connected to the pulsed DC power supply through circuits to form a current loop for discharge plasma sintering.

[0075] During the sintering process, pulsed DC current is introduced through the pressure head body 301, passes through the powder and metal block material located in the groove at the top of the lower graphite column 602, and then returns to the power source through the base body 601, forming a closed loop. Under the action of this high current pulse, discharge plasma is generated between the powder particles, and at the same time, it is subjected to axial mechanical pressure, thereby achieving purification and activation of the particle surface and significant enhancement of bulk diffusion. The temperature change of the sample during this process is monitored in real time by the temperature sensor 8, and finally the rapid densification sintering process and welding process of the thermoelectric material are completed.

[0076] The clamping mechanism includes a clamp 401 (model: Festo DHLE-16-20-P) and a power unit 402. The clamp 401 is disposed inside the furnace chamber 1 and can move horizontally under the drive of the power unit 402 to open / close the clamp 401.

[0077] The power assembly 402 includes a worm gear drive shaft 4021, a worm wheel 4022, a rack 4023, and a servo motor. The worm gear drive shaft 4021 and the worm wheel 4022 are both disposed in the inner wall of the furnace chamber 1. The worm gear drive shaft 4021 is connected to the worm wheel 4022 for transmission. One end of the rack 4023 passes through the side wall of the furnace chamber 1 and meshes with the worm wheel 4022. The other end of the rack 4023 extends into the furnace chamber 1 and is connected to the gripper 401. The servo motor is used to drive the gripper 401 to open / close.

[0078] A servo motor for controlling the opening and closing action of the gripper is installed on the smooth section of the rack 4023. The servo motor is a miniature SG90 model. A pulley group is provided at the bottom of the rack to support the rack and ensure its smooth movement in the horizontal direction. The servo motor independently controls the opening and closing state of the gripper 401 and works together to complete the operation of picking up and placing samples from the loading platform 201.

[0079] The loading mechanism 2 includes a loading platform 201 and a transmission component 202. The upper end face of the loading platform 201 is on the same horizontal plane as the upper end face of the lower graphite column 602. The loading platform 201 can move horizontally under the drive of the transmission component 202.

[0080] The transmission assembly 202 includes a transmission rack, a transmission gear, a transmission shaft, a first bevel gear, a second bevel gear, and a drive shaft. The transmission rack is mounted on the side wall of the furnace 1 via a slide rail and can reciprocate horizontally. One end of the transmission rack is fixedly connected to the loading platform 201. The transmission shaft is vertically rotatably mounted inside the side wall of the furnace 1. The transmission gear is fixedly sleeved on the lower end of the transmission shaft and meshes with the transmission rack. The first bevel gear is fixedly sleeved on the upper end of the transmission shaft. The drive shaft is rotatably mounted horizontally through the side wall of the furnace 1. The end of the drive shaft located outside the furnace 1 is connected to the power source. The second bevel gear is fixedly sleeved on the end of the drive shaft located inside the furnace 1 and meshes with the first bevel gear.

[0081] When the drive shaft rotates under the drive of the motor, it drives the second bevel gear connected to it to rotate. Through the meshing of the bevel gear pair, the direction of power transmission is changed, thereby driving the transmission shaft with the first bevel gear fixed to rotate. Finally, the transmission gear meshing with the rack generates rotational motion, thereby precisely driving the transmission rack and the loading platform 201 fixed to it to move smoothly in the lateral direction. At the same time, a pulley is installed on the side of the transmission gear. The pulley is supported on the platform formed by the extension of the support layer, providing rolling support and axial limit for the lateral movement of the rack and the loading platform, effectively ensuring the smoothness of the movement process and the guiding accuracy.

[0082] <Integrated Spark Plasma Sintering-Brazing Connection Process>

[0083] The integrated device provided in this embodiment can be used for the preparation of TiNiSn / WCu alloy joints in the aerospace and military fields, including the following steps:

[0084] Based on the TiNiSn ternary phase diagram and DSC data from the thermoelectric materials database, and referring to the loss rate in relevant literature, its composition was optimized. The TiNiSn matrix composition, by atomic percentage, is as follows: 34.4% Ti, 32.8% Ni, and 32.8% Sn.

[0085] A. Place a circular metal WCu block with a diameter equal to that of the cylindrical groove at the top of the lower graphite column on the stage;

[0086] B. The pressure head is moved upward by an external servo motor to maintain an unobstructed space between the end of the feeding tube and the lower graphite column, and to ensure that there is no interference between the gripper and the stage.

[0087] C. Mechanically alloyed TiNiSn thermoelectric masterbatch mixed powder, TiZrCuNi brazing powder, and AgCu brazing powder are sequentially loaded into the cylindrical groove at the top of the lower graphite column through the feeding pipe, and then the feeding pipe shut-off valve is closed.

[0088] D. Through the horizontal coordinated movement of the stage and the gripper, the gripper is controlled by the servo motor to perform the grasping and releasing actions, so that the circular metal electrode WCu block on the stage is accurately placed above the mixed powder and fitted into the cylindrical groove.

[0089] E. Control the motion mechanism to return the stage and gripper to the initial position, and at the same time lower the pressure head to the set height, and apply a pre-pressure (9.8kN) to the metal electrode block according to the process requirements;

[0090] F. Start the pulsed DC power supply, adjust the output current according to the process parameters, and complete the sintering-welding integrated forming process. The detailed processing parameters are as follows: pressure 50MPa, temperature 850℃, and holding time 10min.

[0091] After processing, the brazed sample was ground and polished and characterized to obtain the microstructure of the sintered-brazed sample (e.g., ...). Figure 4 The brazed joint prepared by this invention has no obvious pores or cracks at the interface.

[0092] The discharge plasma sintering-brazing technology of the present invention promotes the sintering and brazing of thermoelectric materials under high temperature and high pressure, which can effectively reduce the voids in the powder raw materials, enhance the density and thermal conductivity of the brazed joint, and avoid the decrease in thermoelectric conversion efficiency due to poor connection or poor contact.

[0093] The invention, through precise control of sintering and brazing processes, ensures the stability and durability of the connection points, achieving a defect-free and tightly bonded thermoelectric device connection interface. Figure 4 This improves the long-term stability and service life of thermoelectric devices.

[0094] The application effects of the integrated discharge plasma sintering and brazing device of this invention are as follows: On the one hand, discharge plasma sintering is a highly efficient solid-state sintering technology that uses plasma generated by pulsed current to heat, compress, and heterogeneously connect thermoelectric materials, and is widely used in the manufacturing of thermoelectric devices in various temperature ranges. On the other hand, brazing is a commonly used precision joining process that uses molten brazing filler metal at temperatures below the melting points of thermoelectric materials and electrodes, and employs heating and other means to fill the joints of the base materials, ensuring good mechanical properties and thermal contact. Brazing technology shows broad application prospects in the field of heterogeneous joining of thermoelectric materials, electrodes, and thermally conductive materials. The integrated discharge plasma sintering-brazing device for thermoelectric device joining provided by this application utilizes the common advantages of precise temperature control under high vacuum conditions in brazing and sintering processes, combining the advantages of high-quality sintered products and small heat-affected zones in brazing. This allows for a more precise and rapid combination of the advantages of both, efficiently producing brazed joints of thermoelectric devices with superior overall performance, enabling the composite process to be more widely used in thermoelectric devices in aerospace, vehicle engineering, and related fields.

[0095] Compared to traditional thermoelectric device connection methods (such as welding and mechanical pressing), which are cumbersome, time-consuming, and costly, this invention deeply integrates the mechanical system and the electronic control unit, pioneering an integrated discharge plasma sintering-brazing device that seamlessly combines the two processes. This device can continuously complete sintering and brazing within the same sealed chamber without removing samples midway, completely eliminating the risk of contaminants such as oxygen and moisture intrusion and ensuring interface cleanliness. Simultaneously, it significantly shortens the process chain, reduces manual intervention, and achieves a dual improvement in production efficiency and yield, comprehensively reducing the overall manufacturing cost of thermoelectric devices. It is mainly used in the processing and manufacturing of complex components with high stability requirements for thermoelectric devices in applications such as aerospace, flexible wearable electronics, thermoelectric power generation, refrigeration, and waste heat recovery and reuse from aero-engines.

[0096] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. An integrated discharge plasma sintering-brazing apparatus for connecting thermoelectric devices, characterized in that, It includes a furnace chamber (1), a loading mechanism (2), a pressing head mechanism (3), a base mechanism (6), a clamping mechanism (4), and a feeding pipe (7). The furnace chamber (1) is connected to a vacuum pump (5). The pressure head mechanism (3) includes a pressure head body (301), a drive assembly, a graphite boss (302), and an upper graphite column (303). The pressure head body (301) can move vertically under the drive of the drive assembly. The bottom of the pressure head body (301) is connected to the upper graphite column (303) through the graphite boss (302). The base mechanism (6) includes a base body (601) and a lower graphite column (602). The base body (601) is fixedly installed at the bottom of the furnace (1). The lower graphite column (602) is fixedly installed on the upper end face of the base body (601). The axes of the lower graphite column (602) and the upper graphite column (303) coincide. A processing groove is provided on the upper end face of the lower graphite column (602). The upper graphite column (303) and the lower graphite column (602) are connected to form a processing cavity. The feeding pipe (7) is inserted into the furnace (1) from the outside of the furnace (1) at an angle downwards. The discharge end of the feeding pipe (7) is located above the side of the processing tank. The feed end of the feeding pipe (7) is equipped with a shut-off valve. The pressure head body (301) and the base body (601) are respectively connected to a pulsed DC power supply through a circuit to form a current loop for discharge plasma sintering; The clamping mechanism includes a clamp (401) and a power assembly (402). The clamp (401) is disposed inside the furnace (1) and can move horizontally under the drive of the power assembly (402) and can open / close. The loading mechanism (2) includes a loading platform (201) and a transmission assembly (202). The upper surface of the loading platform (201) is on the same horizontal plane as the upper surface of the lower graphite column (602). The loading platform (201) can move horizontally under the drive of the transmission assembly (202).

2. The integrated discharge plasma sintering-brazing apparatus for connecting thermoelectric devices as described in claim 1, characterized in that, A temperature sensor (8) is provided on the outer wall of the lower graphite column (602).

3. The integrated discharge plasma sintering-brazing apparatus for connecting thermoelectric devices as described in claim 1, characterized in that, The drive assembly includes a drive column (304), which is located on the top of the pressure head body (301). The top of the furnace (1) has a channel for the drive column (304) to move up and down. The drive column (304) has a capsule-shaped through hole (305) arranged in the horizontal direction. A shaft is inserted through the capsule-shaped through hole (305). One end of the shaft is fixedly connected to the upper end of the crank arm (306). The lower end of the crank arm (306) is connected to a rotating shaft. The rotating shaft is rotatably supported on the side wall of the furnace (1). A driven gear (307) is fixedly sleeved on the rotating shaft. A drive rack (308) meshes with the driven gear (307) below it. One end of the drive rack (308) passes through the furnace (1) and meshes with the driving gear (309). The driving gear (309) is driven by a motor.

4. The integrated discharge plasma sintering-brazing device for connecting thermoelectric devices as described in claim 1, characterized in that, The power assembly (402) includes a worm gear drive shaft (4021), a worm wheel (4022), a rack (4023), and a servo motor. The worm gear drive shaft (4021) and the worm wheel (4022) are both disposed in the inner wall of the furnace chamber (1). The worm gear drive shaft (4021) is connected to the worm wheel (4022) for transmission. One end of the rack (4023) passes through the side wall of the furnace chamber (1) and meshes with the worm wheel (4022). The other end of the rack (4023) extends into the furnace chamber (1) and is connected to the gripper (401). The servo motor is used to drive the gripper (401) to open / close.

5. The integrated discharge plasma sintering-brazing apparatus for connecting thermoelectric devices as described in claim 1, characterized in that, The transmission assembly (202) includes a transmission rack, a transmission gear, a transmission shaft, a first bevel gear, a second bevel gear, and a drive shaft. The transmission rack is mounted on the side wall of the furnace (1) via a slide rail and can reciprocate in the horizontal direction. One end of the transmission rack is fixedly connected to the loading platform (201). The transmission shaft is rotatably mounted vertically inside the side wall of the furnace (1). The transmission gear is fixedly mounted on the lower end of the transmission shaft and meshes with the transmission rack. The first bevel gear is fixedly mounted on the upper end of the transmission shaft. The drive shaft is rotatably mounted horizontally through the side wall of the furnace (1). The end of the drive shaft located outside the furnace (1) is connected to the power source. The second bevel gear is fixedly mounted on the end of the drive shaft located inside the furnace (1) and meshes with the first bevel gear.

6. The integrated discharge plasma sintering-brazing apparatus for connecting thermoelectric devices as described in claim 1, characterized in that, The upper graphite column (303) and the graphite boss (302) are connected by two connecting frames. The side wall of the upper graphite column (303) is symmetrically provided with two grooves. The connecting frame (2035) consists of an upper frame, a lower frame and a vertical frame connecting the upper and lower frames. The lower frame of the connecting frame (2035) is embedded in the groove, and the vertical frame is attached to the outer wall of the upper graphite column (303). The upper frame is fixedly connected to the graphite boss (302) by bolts.

7. The integrated discharge plasma sintering-brazing apparatus for connecting thermoelectric devices as described in claim 1, characterized in that, The furnace chamber (1) consists of a heat reflective layer (101), a support layer (102), and an insulation layer (103) from the inside out.

8. A discharge plasma sintering-brazing integrated connection process for thermoelectric devices, comprising using the apparatus described in claim 1 for connection processing, characterized in that, The process includes the following: Place a circular metal electrode block on the stage, the diameter of which is adapted to the machining groove at the top of the lower graphite column; Control the pressure head body to move upward so that the lower graphite column will not affect the material conveying of the feeding tube and ensure that there is no interference between the gripper and the platform; The mechanically alloyed thermoelectric masterbatch mixed powder and brazing powder are sequentially fed into the processing groove at the top of the lower graphite column through the feeding pipe, and then the stop valve of the feeding pipe is closed. Through the horizontal coordinated movement of the stage and the gripper, and the gripping and releasing action of the gripper, the circular metal electrode block on the stage is placed above the mixed powder and embedded in the processing tank. Control the stage and gripper to return to the initial position, and at the same time lower the pressure head body to the set height to apply pre-pressure to the metal electrode block according to the process requirements; Start the pulsed DC power supply, adjust the output current according to the process parameters, and complete the sintering-welding integrated forming.

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