Laser-assisted connecting device for silicon nitride tungsten alloy heating sheet

Abstract

The invention discloses a laser auxiliary connecting device for a silicon nitride tungsten alloy heating sheet, the laser auxiliary connecting device comprises a placing table, a laser head and a pretreatment device, a winding assembly, a fixing assembly and a laser spot welding head are arranged in the pretreatment device, the winding assembly comprises a driving unit, a top plate, two combined cylinders and a bottom plate, and the two combined cylinders are rotationally connected with the bottom plate; the surface of the combined cylinder is connected with the driving unit through a top plate; the diameter of the inner wall of the combined cylinder is equal to the sum of the diameter of tungsten alloy and the thickness of reaction foil; the transition layer is generated through the reaction foil, meanwhile, the transition layer is densified, the residual thermal stress in silicon nitride is low, the transition layer can be connected with the tungsten alloy and the silicon nitride plate, the problem of base material difference is avoided, the cutting and winding processes of the reaction foil are integrated through the pretreatment device, the position stability of the tungsten alloy is improved through the fixing assembly, and the machining precision is improved. Therefore, the reaction foil can be tightly wound on the surface of the tungsten alloy, meanwhile, the reaction foil is connected with the tungsten alloy through the laser spot welding head, and the stability is improved.

Description

Technical Field

[0001] This invention relates to the field of laser connection device technology, specifically to a laser-assisted connection device for silicon nitride tungsten alloy heating elements. Background Technology

[0002] Silicon nitride tungsten alloy heating elements are widely used in aerospace, semiconductor thermal management, and industrial precision heating. The core requirements are high-strength metallurgical connections, low contact resistance, resistance to thermal fatigue, and narrow-gap fit. Silicon nitride ceramics possess high hardness, low thermal conductivity, excellent insulation, and high-temperature resistance, while tungsten alloys have high melting points, good electrical conductivity, and thermal stability. The combination of the two can meet the synergistic heating and insulation requirements under extreme operating conditions.

[0003] Currently, silicon nitride tungsten alloy heating elements are mostly produced using high-temperature brazing technology. For example, Chinese patent CN106695141B discloses a method for laser high-temperature brazing assisted by the self-propagating reaction of a nano-multilayer film, belonging to the field of laser welding technology. This method involves alternately depositing bimetallic nanofilms on a substrate using magnetron sputtering; peeling the deposited bimetallic nano-multilayer film from the substrate; placing the peeled multilayer film between two layers of brazing filler metal to form a composite intermediate layer; pre-treating the surface of the base material to be welded; placing the composite intermediate layer between the obtained base materials; and welding using an lap joint method, employing laser scanning welding of the composite intermediate layer. After laser ignition, the nano-multilayer film undergoes a self-propagating reaction, releasing a large amount of heat that melts the low-melting-point brazing filler metal. This allows the welding process to form a connection not only at the lap joint but also across the entire lap surface, increasing the joint strength and completing the material connection. This invention can improve the uneven heating caused by laser as a local heat source, resulting in a more uniform interface reaction and improving joint density.

[0004] However, the aforementioned patent requires the overall temperature to be heated to over 800 degrees Celsius in the process flow, and the melting cycle of the solder using the self-propagating reaction of the bimetallic nano-multilayer film is relatively long. This will generate huge residual thermal stress in the silicon nitride, which is prone to cracking. In addition, the solder layer after connection is usually soft, and due to the large difference in its composition from the base material, the reliability of the connection is insufficient when used in high-temperature environments. Summary of the Invention

[0005] The purpose of this invention is to provide a laser-assisted connection device for silicon nitride tungsten alloy heating elements, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a laser-assisted connection device for silicon nitride tungsten alloy heating elements, comprising: A placement stage for fixing silicon nitride plates, tungsten alloys, and reaction foils; A laser head is disposed on one side of the placement platform, and the laser head has an ignition layer, an airflow layer and a jet layer coaxially arranged from the inside to the outside. A pretreatment device is fixedly connected to a placement platform and is equipped with a winding assembly, a fixing assembly, and a laser spot welding head to make the reaction foil adhere to the surface of the tungsten alloy. And a preheating conduit is disposed between the silicon nitride plate and the pretreatment device so that the tungsten alloy and the reaction foil can enter the silicon nitride plate; The winding assembly includes a drive unit, a top plate, a combined cylinder, and a bottom plate. There are two combined cylinders, both of which are rotatably connected to the bottom plate. The surface of the combined cylinder is connected to the drive unit through the top plate. The diameter of the inner wall of the combined cylinder is equal to the sum of the diameter of the tungsten alloy and the thickness of the reaction foil.

[0007] Preferably, in the laser head, the airflow layer is inclined inward, the output direction of the airflow layer is towards the ignition layer, and a lens is fixedly connected to the end of the inner wall of the ignition layer.

[0008] Preferably, a silicon nitride plate is detachably mounted on the surface of the placement platform, and a through connection hole is opened on the side of the silicon nitride plate. One side of the placement platform is fixedly connected to the laser head, and the laser head is coaxially aligned with the connection hole. The other side of the placement platform is fixedly connected to the pretreatment device.

[0009] Preferably, the drive unit is fixedly connected to the bottom of the pretreatment device, the output end of the drive unit is fixedly connected to a sliding frame, the two ends of the sliding frame are fixedly connected to Y-shaped limiting frames, the inner arc surface of the limiting frame is fixedly connected to a T-shaped top plate, and the surfaces of the limiting frame and the top plate are uniformly in contact with the two combined cylinders.

[0010] Preferably, the cross-sections of the two combined cylinders are both semi-circular. The two ends of the combined cylinders are hinged to the two ends of the bottom plate and a row of evenly arranged through holes are opened on the surface. The two ends of the bottom plate are fixedly connected to the pretreatment device. Several gas guide pipes are fixedly connected to the lower side of the bottom plate. The other end of the gas guide pipes passes through the pretreatment device. The upper side of the bottom plate is in contact with the reaction foil. There is a negative pressure between the reaction foil and the gas guide pipes.

[0011] Preferably, a plurality of laser spot welding heads are fixedly connected to the upper end of the inner wall of the pretreatment device. When the two combined cylinders are combined, the laser spot welding heads are located directly above the through hole. An inlet pipe is fixedly connected to the surface of the pretreatment device. An electric push rod is fixedly connected to the end of the inlet pipe away from the pretreatment device. The inlet pipe, the preheating conduit and the connecting hole are coaxially aligned.

[0012] Preferably, the preheating conduit is convex, with one end in contact with the silicon nitride plate and the inner wall diameter of this end being equal to the diameter of the connecting hole, and the other end of the preheating conduit being fixedly connected to the pretreatment device and the inner wall diameter of this end being greater than the diameter of the connecting hole, and the middle part of the inner wall of the preheating conduit being a smooth curved surface.

[0013] Preferably, both ends of the tungsten alloy are fixedly connected with pins, the surface of the tungsten alloy is in contact with the reaction foil, the reaction foil is a Ni-Al self-propagating reaction foil, its two ends are beveled, and the whole is a parallelogram shape.

[0014] Preferably, the fixing assembly includes a lead screw, a connecting rod, a clamp, and a guide rod fixedly connected to the pretreatment device. The surface of the lead screw is threaded with two symmetrically arranged sliders, and the surface of the guide rod is slidably connected with two symmetrically arranged sliders. The two sliders on the same horizontal plane are fixedly connected by the connecting rod. A clamp is fixedly connected to one side of each slider, and the clamp contacts the pin.

[0015] Preferably, the pretreatment device is provided with a cutting assembly, including: a lead screw and a cutter. The lead screw is rotatably connected to the pretreatment device, and its surface is threadedly connected to the cutter. The cutter is slidably connected to the inner wall of the pretreatment device, and the cutting surface of the cutter is a right-angled triangle.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. The present invention ignites the reaction foil through the ignition layer to generate a transition layer, and at the same time, the transition layer is impacted by the shock wave formed by the jet layer, which makes the transition layer denser. During this process, the reaction of the reaction foil is relatively mild, and the residual thermal stress in the silicon nitride is low. At the same time, the generated transition layer can connect the tungsten alloy and the silicon nitride plate, making the two less likely to separate and avoiding the problem of differences in the base material. 2. The pretreatment device integrates the cutting, fixing, and winding components of the reaction foil, allowing the connection between the reaction foil and the tungsten alloy to be completed with a single device. The foil is automatically pushed into the silicon nitride plate for connection. The fixing component ensures the positional stability of the tungsten alloy during the winding process, allowing the reaction foil to be tightly wound onto the surface of the tungsten alloy. At the same time, a laser spot welding head is used to initially connect the reaction foil and the tungsten alloy, preventing them from detaching or separating and improving the stability of subsequent operations. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the internal structure of the pretreatment device of the present invention; Figure 3 This is a schematic diagram of the tungsten alloy structure of the present invention; Figure 4 This is a schematic diagram of the internal structure of the laser head of the present invention; Figure 5 This is a schematic diagram of the silicon nitride plate structure of the present invention; Figure 6 This is a schematic diagram of the structure of the present invention, in which the tungsten alloy and the reaction foil are both located inside the silicon nitride plate; Figure 7 This is a schematic diagram of the winding assembly structure of the present invention; Figure 8 This is a schematic diagram of the air duct structure of the present invention; Figure 9 This is a schematic diagram of the combined cylinder structure of the present invention; Figure 10 This is a schematic diagram of the fixed component structure of the present invention.

[0018] In the diagram: 1. Placement platform; 2. Silicon nitride plate; 3. Connecting hole; 4. Laser head; 41. Ignition layer; 42. Gas flow layer; 43. Jet layer; 44. Lens; 5. Preheating conduit; 6. Pretreatment device; 61. Laser spot welding head; 62. Inlet pipe; 63. Electric push rod; 64. Fixing assembly; 641. Lead screw one; 642. Slider; 643. Connecting rod one; 644. Fixture; 645. Guide rod; 65. Winding assembly; 651. Sliding frame; 652. Drive unit; 653. Limiting frame; 654. Top plate; 655. Combined cylinder; 656. Bottom plate; 657. Gas duct; 66. Cutting assembly; 661. Cutter; 662. Lead screw two; 7. Reaction foil; 8. Bevel; 9. Tungsten alloy; 10. Needle. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example: Please see Figure 1-10This embodiment provides a technical solution: a laser-assisted connection device for silicon nitride tungsten alloy heating elements, including a placement stage 1, a laser head 4, a pretreatment device 6, and a preheating conduit 5. The pretreatment device 6 is equipped with a control module, which is signal-connected to the laser head 4, electric push rod 63, drive unit 652, laser spot welding head 61, and the heating unit of the preheating conduit 5. The module has a complete preset process program, which can coordinate the action sequence and timing of each actuator. After the laser head 4 is started, the control module starts a high-precision internal timer. After a preset delay time, it automatically triggers the operation of the emission layer 43 and the airflow layer 42, thereby controlling the action of each component in the device and facilitating the adjustment of the coordinated action time. The placement stage 1 is used to fix and adjust the position of the silicon nitride plate 2, and also provides a platform for connecting the tungsten alloy 9 and the silicon nitride plate. A coaxial vision system can be integrated near the placement stage 1. The inspection system can immediately acquire images of the weld morphology at the connection hole after connection is completed, which facilitates preliminary judgment by algorithms on whether there are defects such as incomplete connection or spatter between tungsten alloy 9 and silicon nitride plate 2, thereby achieving process quality control. The surface of the placement table 1 is fixed with a common adjustable silicon nitride plate 2 position holder, which facilitates the disassembly, assembly and quick positioning of silicon nitride plate 2. A through connection hole 3 is opened on the side of silicon nitride plate 2, which provides a precise installation position for the connection between tungsten alloy 9 and silicon nitride plate 2. One side of the placement table 1 is fixedly connected to the laser head 4, which is connected to the laser generator and other devices. The laser head 4 is coaxially aligned with the connection hole 3 to ensure that the laser energy can be accurately applied to the designated reaction area and avoid deviation. The other side of the placement table 1 is fixedly connected to the pre-treatment device 6, thereby achieving seamless connection between component pre-treatment and laser connection process, thus ensuring processing continuity.

[0021] The preheating conduit 5 is a component used to connect the pretreatment device 6 and the silicon nitride plate 2. It is also a key transition component for ensuring the accurate delivery and preheating of materials for generating silicon nitride tungsten alloy heating elements. The conduit has a unique convex structure. The inner diameter of its inlet near the silicon nitride plate 2 is precisely machined to be exactly equal to or slightly larger than the diameter of the connecting hole 3 on the silicon nitride plate, thus forming a gapless docking channel. This ensures that the components delivered from the conduit can be directly introduced into the connecting hole 3 without deviation or jamming, achieving final positioning.

[0022] The other end of the conduit 5 is fixedly connected to the outlet of the pretreatment device 6. The inner cavity of this end is designed in a trumpet shape, with its inner diameter significantly larger than the diameter of the connecting hole 3. The two ends of the conduit 5 are smoothly connected by a tapered curved surface with a smooth inner wall and continuously changing curvature. This streamlined inner cavity design greatly reduces the frictional resistance experienced by the components during transportation and provides adaptive guidance for the initial entry section of the components, thereby effectively correcting deviations and ensuring coaxiality of the transportation. A surrounding heating rod and temperature sensor are integrated and embedded in the inner wall of the conduit 5, forming a precise preheating module. During the process of the tungsten alloy rod wrapped with the reaction foil 7 being pushed into the conduit 5, the heating rod is activated, thereby uniformly and controllably preheating the tungsten alloy 9 and the reaction foil 7 wrapped around its surface as it passes through at a constant speed. The thermal process can raise the temperature of the reaction foil 7 to a relatively stable initial value, such as 150-300℃, thereby removing water vapor adsorbed on the surface of the reaction foil 7 and preventing the generation of steam and resulting pores during subsequent reactions. At the same time, preheating can also slightly soften the low-melting-point components in the reaction foil 7, thereby increasing the adhesion of the winding. In addition, preheating can raise the overall material to a stable thermal state, reducing the impact of ambient temperature fluctuations on the energy and propagation speed of the self-propagating reaction, improving the process repeatability to above 1.33. Furthermore, reducing heat capacity differences, the self-propagating reaction starts more smoothly and rapidly during the subsequent laser ignition process, and the propagation of the reaction wave is more consistent and sufficient, thereby significantly improving the process stability and uniformity of the joint performance.

[0023] The pretreatment device 6 is fixedly connected to the placement platform 1. An inlet tube 62 is fixedly connected to its surface. An electric push rod 63 is fixedly connected to the end of the inlet tube 62 away from the pretreatment device 6. The electric push rod 63 is small in size and has a long stroke. Its output end is provided with a buffer rubber layer, which contacts the pin 10. The buffer rubber layer can prevent damage to the pin 10. When the electric push rod 63 is started, it can push the tungsten alloy 9 to move through the pin. The stroke of the electric push rod 63 is controlled by the control module each time. The first push of the electric push rod 63 can push the tungsten alloy 9 into the pretreatment device 6. At this time, there are clamps 644 on the upper and lower sides of each pin 10, and the reaction foil 7 is located on the bottom surface of the tungsten alloy 9. The two ends of the tungsten alloy 9 are connected to the combined cylinder 65. When the two ends of 5 are flush, the electric push rod 63 can continue to push the pin 10 when it is started for the second time, so that the tungsten alloy 9 passes through the preheating conduit 5 into the connecting hole 3 of the silicon nitride plate 2. Then it can be reset. The inlet tube 62, the preheating conduit 5 and the connecting hole 3 are coaxially aligned. The electric push rod 63 can push the tungsten alloy 9 placed in the inlet tube into the pretreatment device along the coaxial path. The stroke data of the electric push rod can be used to ensure the movement distance of the tungsten alloy 9, avoid abnormalities in subsequent operations, and thus complete the automated and precise feeding. The pretreatment device 6 integrates the winding component 65, the fixing component 64, the laser spot welding head 61 and the cutting component 66, which completes the multiple pretreatment processes for bonding the reaction foil 7 and the tungsten alloy 9, thereby ensuring that the two are tightly bonded and accurately positioned.

[0024] The winding assembly 65 includes a drive unit 652, a top plate 654, a combined cylinder 655, and a bottom plate 656. The drive unit 652 is fixedly connected to the bottom of the pretreatment device 6, and its output end is fixedly connected to a sliding frame 651. Both ends of the sliding frame 651 are fixedly connected to Y-shaped limiting frames 653. The driving unit can drive the limiting frames to slide vertically. The inner arc surface of the limiting frame 653 is fixedly connected to a T-shaped top plate 654. The surfaces of the limiting frame 653 and the top plate 654 are in contact with the two combined cylinders 655. The surface of the combined cylinder 655 is polished and coated with diamond-like carbon tool steel to make it both wear-resistant and low-friction. The friction coefficient is controlled by the sliding frame 651 and the top plate 654, which enable the merging and separation of the two combined cylinders 655. Both sides of the upper end of the top plate 654 are arc-shaped to prevent sharp corners from damaging the surface of the combined cylinders 655. When the sliding frame 651 slides upward, the top plate 654 presses against the arc surfaces of the two combined cylinders 655. Under the action of the oblique force, they begin to rotate upward. During this process, the limiting frame 653 limits the movement of the combined cylinders 655. Both combined cylinders 655 are rotatably connected to the bottom plate 656 and have semi-circular cross-sections. After merging, they form a complete cylindrical shape, the diameter of which is equal to the diameter of the tungsten alloy 9 and the diameter of the reaction foil 7. The sum of the thicknesses is used to adapt to the state after the reaction foil 7 is tightly wound around the surface of the tungsten alloy 9. The two ends of the base plate 656 are fixedly connected to the pretreatment device 6, and several gas guide pipes 657 are fixedly connected to its lower side. The other end of the gas guide pipes 657 passes through the pretreatment device 6 and is connected to a low-power air pump. The upper side of the base plate 656 is in contact with the reaction foil 7 and there is a slight negative pressure between them. The slight negative pressure of the gas guide pipes 657 can adsorb the reaction foil 7. This slight negative pressure will not cause deformation of the reaction foil 7, thereby avoiding its displacement during the winding process. A row of uniform through holes is opened on the surface of the combined cylinder 655. The upper end of the inner wall of the pretreatment device 6 is fixedly connected to There are several laser spot welding heads 61. The laser spot welding head 61 is a pulsed fiber laser spot welding device with a single pulse energy of no more than 10J, a peak power of no less than 1kW, and a spot diameter of no more than 100μm. This enables instantaneous micro-spot welding of the overlapping area of ​​the reaction foil 7, while ensuring that it is firmly fixed and does not trigger a self-propagating reaction of the entire reaction foil 7. When the combined cylinder 655 is merged, the laser spot welding head 61 is facing the through hole. At this time, the laser spot welding head 61 emits laser light, and the laser light passes through the through hole to spot weld and fix the overlapping area of ​​the reaction foil 7 and the tungsten alloy 9 after they are bonded together, preventing the reaction foil 7 from falling off or from sliding and separating relative to the tungsten alloy 9 in subsequent processes.

[0025] The fixing component 64 is the core mechanism for achieving precise positioning and reliable clamping of tungsten alloy 9 during pretreatment. Its specific structure includes: a lead screw 641, a guide rod 645, a connecting rod 643, and a clamp 644. The surface of the lead screw 641 has two types of threads with only opposite directions of rotation. Two sliders 642 on its surface are each connected to one of these threads, and the distance between the two sliders 642 at the connection points of the two threads is equal, thus ensuring synchronous movement. The connecting rod 643 is connected to the pretreatment device 644. The lead screw 641 is connected to the inner wall of the pretreatment device 6 via bearings. The rotating connection has a surface machined with bidirectional threads, and two sliders 642 are symmetrically threaded together. A guide rod 645, which is parallel to the lead screw 641, is fixed to the inner wall of the device. Its surface is smooth. Each slider 642 cooperates with both the lead screw 641 and the guide rod 645, that is, it is threadedly connected to the lead screw 641. In this way, it forms a sliding pair with the guide rod 645. At this time, the movement of the slider 642 will be strictly controlled by the rotation of the lead screw 641, and the rotational degree of freedom will be eliminated by the guide rod 645, thereby providing high-precision linear motion guidance and ensuring smooth and wobbly movement.

[0026] Two sliders 642 on the same horizontal plane are fixedly connected by a rigid connecting rod 643. This structure ensures that the two sliders 642 always move synchronously, equidistantly, and in opposite directions under the drive of the lead screw 641. This is the key to achieving symmetrical clamping. A clamp 644 is fixedly installed on the outside of each slider 642, i.e., in the direction facing the tungsten alloy 9. The distance between the two clamps 644 is greater than the length of the tungsten alloy 9. The shape of the clamping surface of the clamp 644 matches the shape of the pins 10 extending from both ends of the tungsten alloy 9. It can be designed as a V-groove or a semi-circular bayonet to increase the contact area, thereby ensuring stable clamping without damaging the surface of the pins 10.

[0027] The control module starts the drive motor connected to the end of the lead screw 641, driving the lead screw 641 to rotate. Since the threads are opposite, the two sliders 642 can move precisely towards each other along the guide rod 645 under the rigid connection of the connecting rod 643, thereby driving the two sets of clamps 644 to approach synchronously until their clamping surfaces are in complete contact with the pins 10 of the tungsten alloy 9 and a preset clamping force is applied, thus completing the position fixation and center positioning of the tungsten alloy 9. This fixed state provides an absolute reference for the subsequent precision winding of the reaction foil 7, thereby effectively preventing any deviation or vibration. After the winding and spot welding fixing processes are completed, the drive motor rotates in the opposite direction, which can drive the clamps 644 to separate synchronously, releasing the workpiece so that the next process can be carried out.

[0028] The cutting component 66 in the pretreatment device 6 includes a lead screw 662 and a cutter 661. The lead screw 662 is rotatably connected to the pretreatment device 6 and its surface is threadedly connected to the cutter 661. The cutter 661 is slidably connected to a long groove on the inner wall of the pretreatment device 6. The groove is square to prevent the cutter 661 from rotating. The lead screw 662 is connected to a motor in the pretreatment device. Its rotation can drive the cutter 661 to slide along the inner wall of the device. The cutting surface of the cutter 661 is a right-angled triangle, which facilitates precise cutting of the reaction foil 7. After cutting by the triangular cutting surface, both ends of the reaction foil 7 are 45-degree bevels 8. The reaction foil 7 is a Ni-Al self-propagating reaction foil. Its self-propagating reaction is extremely fast. Its overall shape is a parallelogram. When the reaction foil 7 is wrapped around the surface of the tungsten alloy 9, the bevels 8 on both sides are connected to each other and form an overlap area.

[0029] In actual use, the silicon nitride plate 2 is first fixed to the surface of the placement stage 1 and calibrated so that the connecting hole 3 is coaxially aligned with the laser head 4, the preheating conduit 5, and the inlet tube 62. Then, the tungsten alloy 9 is placed in the inlet tube 62. At this time, the reaction foil 7 is placed through the side opening of the pretreatment device 6 and cut by the cutting component 66. Then, it is placed on the base plate 656. At this time, the gas duct 657 starts to exhaust gas, thereby adsorbing the reaction foil 7 through a slight negative pressure. At this time, the electric push rod 63 is activated, pushing the tungsten alloy 9 into the pretreatment device 6. Then, the clamp 644 of the fixing component 64 clamps the pin 10 to complete the fixing of the tungsten alloy 9. The drive unit 652 drives the combined cylinder 655 to rotate and merge through the upward movement of the sliding frame 651 and the top plate 654. During this process, the inner arc surface of the combined cylinder 655 gradually contacts the edge of the flat reaction foil 7. The combined cylinder 655 continues to rotate and drives the reaction foil 7 to bend upward by friction, so that it... Gradually, the tungsten alloy 9, which is fixed in the center, is wrapped around the tungsten alloy 9. When the drive unit 652 reaches the preset end point of the stroke, the two combined cylinders 655 rotate to the closed state. Their inner arc surfaces together form a complete cylinder. The inner diameter of this cylinder is exactly equal to the sum of the diameter of the tungsten alloy 9 and the thickness of the single-layer reaction foil 7, thereby ensuring that the reaction foil 7 is tightly and gaplessly wrapped around the surface of the tungsten alloy 9. At the same time, the 45-degree beveled edges 8 at both ends of the reaction foil 7 are also precisely aligned in this process to form an overlapping area. At this time, the beveled edges 8 on both sides are located below the through hole. The laser spot welding head 61 spot welds and fixes the two through the through hole. At this time, the fixing component 64 starts to release the pin 10 and continues to push the tungsten alloy 9 wrapped with the reaction foil 7 through the electric push rod 63. During this process, the preheating conduit 5 will preheat the reaction foil 7 and the tungsten alloy 9. After it is introduced into the connection hole 3 of the silicon nitride plate 2 through the preheating conduit 5, the laser head 4 is activated.

[0030] The laser head 4 is coaxially arranged from the inside out with an ignition layer 41, an airflow layer 42, and a jet layer 43. The airflow layer 42 is inclined inward and its output direction is towards the ignition layer 41. The ignition layer 41 is the central laser channel, responsible for emitting pulses to ignite and trigger the self-propagating reaction of the reaction foil 7. A high-temperature resistant sapphire protective lens 44 is fixedly connected to the end of the inner wall of the ignition layer 41 to ensure accurate and rapid ignition of the reaction foil 7. The jet layer 43 is equipped with a ring-shaped array of plasma nozzles, which are composed of several microporous electrodes. The plasma nozzle electrodes are preferably made of copper-tungsten alloy and are cooled by circulating deionized water to ensure their operation. When the control module receives a signal, it will synchronously generate a uniform and converging plasma jet at the center, thereby generating a high-intensity shock wave on the burned reaction foil 7. At the same time that the jet layer 43 receives the working signal, the airflow layer 42 will also start working simultaneously, that is, continuously spraying argon-like inert gas, thereby forming an argon curtain wall on the ignition layer 41. The argon curtain wall can generate a negative pressure area at the front end of the lens 44, effectively preventing damage and contamination of the lens 44 by the high temperature of the plasma and splashes. At the same time, argon can continue to be sprayed out along the ignition layer 41, which helps to disperse smoke and dust and clean the processing area.

[0031] When the laser head 4 is activated, the ignition layer 41 emits a laser with a wavelength of 1070 nm, a single pulse energy of 1-5 joules (J), a pulse width of 1-10 milliseconds, and a spot diameter of 0.5-1.5 mm. After passing through the lens 44, the laser ignites the reaction foil 7. The overlapping area of ​​the reaction foil 7 is ignited first. At this time, the Ni-Al reaction foil 7 undergoes a self-propagating reaction, and the reaction foil 7 will spread from one end near the laser head 4 towards the other end near the pretreatment device 6. Due to the inherent characteristics of the reaction foil 7, the reaction foil 7 will be completely burned within 10 to 50 milliseconds. During the combustion process, the reaction foil 7 releases high temperatures and generates a NiAl transition layer. From the start of the self-propagating reaction to the complete formation of the transition layer, the NiAl transition layer remains in a high-temperature plastic state. Within 30 milliseconds of transition layer formation, the jet layer 43 and the gas flow layer 42 are activated. This 30-millisecond delay is determined based on the combustion wave velocity of the Ni-Al reaction foil 7, the length of the connecting hole, and the high-temperature plastic window period of the high-temperature NiAl intermetallic compound above 1200 degrees Celsius. Simultaneously, a preset high-speed camera and thermocouple are used... Monitoring and confirmation can be performed. During this window, impact compaction can be implemented to increase the density of the transition layer by more than 15% and reduce the interface porosity to below 2%. Within these 30 milliseconds, the NiAl transition layer remains in a high-temperature plastic state. When the high-energy pulse emitted by the jet layer 43 contacts the surface of the NiAl transition layer, the medium on the surface of the NiAl transition layer is instantly ionized, thereby generating high-pressure plasma. At this time, the plasma begins to expand, and during the expansion process, it is restricted by the tungsten alloy 9 and the silicon nitride plate 2. At this time, it will form a high-intensity shock wave in the connecting hole 3, thereby generating an impact pressure of not less than 2 gigapascals on the interior of the transition layer. Through this impact pressure, the NiAl transition layer can be compacted and strengthened, causing it to undergo microscopic plastic deformation. Then, the NiAl transition layer is used to achieve the fusion of the tungsten alloy 9 and the silicon nitride plate 2. After the overall connection is completed, the silicon nitride tungsten alloy heating element can be removed, thereby completing the overall processing. At the same time, multiple devices can be arranged to simultaneously perform connection operations between multiple connecting holes 3 of the silicon nitride plate 2 and the tungsten alloy 9, thereby improving production efficiency.

[0032] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A laser-assisted connection device for silicon nitride tungsten alloy heating elements, characterized in that: include: Placement stage (1) for fixing silicon nitride plate (2), tungsten alloy (9) and reaction foil (7); The laser head (4) is disposed on one side of the placement platform (1). The laser head (4) is coaxially disposed with an ignition layer (41), an airflow layer (42) and a jet layer (43) from the inside to the outside. The pretreatment device (6) is fixedly connected to the placement platform (1) and is equipped with a winding assembly (65), a fixing assembly (64) and a laser spot welding head (61) to make the reaction foil (7) adhere to the surface of the tungsten alloy (9); And a preheating conduit (5) is disposed between the silicon nitride plate (2) and the pretreatment device (6) so that the tungsten alloy (9) and the reaction foil (7) can enter the silicon nitride plate (2); The winding assembly (65) includes a drive unit (652), a top plate (654), a combination cylinder (655), and a bottom plate (656). There are two combination cylinders (655), both of which are rotatably connected to the bottom plate (656). The surface of the combination cylinder (655) is connected to the drive unit (652) through the top plate (654). The diameter of the inner wall of the combination cylinder (655) is equal to the sum of the diameter of the tungsten alloy (9) and the thickness of the reaction foil (7).

2. The laser-assisted connection device for a silicon nitride tungsten alloy heating element according to claim 1, characterized in that: In the laser head (4), the airflow layer (42) is inclined inward, the output direction of the airflow layer (42) is towards the ignition layer (41), and a lens (44) is fixedly connected to the end of the inner wall of the ignition layer (41).

3. The laser-assisted connection device for a silicon nitride tungsten alloy heating element according to claim 1, characterized in that: A silicon nitride plate (2) is detachably mounted on the surface of the placement platform (1). A through connection hole (3) is provided on the side of the silicon nitride plate (2). One side of the placement platform (1) is fixedly connected to the laser head (4). The laser head (4) is coaxially aligned with the connection hole (3). The other side of the placement platform (1) is fixedly connected to the pretreatment device (6).

4. The laser-assisted connection device for a silicon nitride tungsten alloy heating element according to claim 1, characterized in that: The drive unit (652) is fixedly connected to the bottom of the pretreatment device (6). The output end of the drive unit (652) is fixedly connected to a sliding frame (651). Both ends of the sliding frame (651) are fixedly connected to Y-shaped limiting frames (653). The inner arc surface of the limiting frame (653) is fixedly connected to a T-shaped top plate (654). The surfaces of the limiting frame (653) and the top plate (654) are evenly in contact with the two combined cylinders (655).

5. The laser-assisted connection device for a silicon nitride tungsten alloy heating element according to claim 1, characterized in that: Both of the combined cylinders (655) have semi-circular cross sections. The two ends of the combined cylinder (655) are hinged to the two ends of the bottom plate (656) and a row of evenly arranged through holes are opened on the surface. The two ends of the bottom plate (656) are fixedly connected to the pretreatment device (6). Several gas guide pipes (657) are fixedly connected to the lower side of the bottom plate (656). The other end of the gas guide pipe (657) passes through the pretreatment device (6). The upper side of the bottom plate (656) is in contact with the reaction foil (7). There is a negative pressure between the reaction foil (7) and the gas guide pipe (657).

6. The laser-assisted connection device for a silicon nitride tungsten alloy heating element according to claim 5, characterized in that: Several laser spot welding heads (61) are fixedly connected to the upper end of the inner wall of the pretreatment device (6). When the two combined cylinders (655) are combined, the laser spot welding heads (61) are located directly above the through hole. An inlet pipe (62) is fixedly connected to the surface of the pretreatment device (6). An electric push rod (63) is fixedly connected to the end of the inlet pipe (62) away from the pretreatment device (6). The inlet pipe (62), the preheating conduit (5), and the connecting hole (3) are coaxially aligned.

7. The laser-assisted connection device for a silicon nitride tungsten alloy heating element according to claim 1, characterized in that: The preheating conduit (5) is convex, with one end in contact with the silicon nitride plate (2) and the inner wall diameter of this end being equal to the diameter of the connecting hole (3). The other end of the preheating conduit (5) is fixedly connected to the pretreatment device (6) and the inner wall diameter of this end is greater than the diameter of the connecting hole (3). The middle part of the inner wall of the preheating conduit (5) is a smooth curved surface.

8. The laser-assisted connection device for a silicon nitride tungsten alloy heating element according to claim 6, characterized in that: Both ends of the tungsten alloy (9) are fixedly connected with pins (10). The surface of the tungsten alloy (9) is in contact with the reaction foil (7). The reaction foil (7) is a Ni-Al self-propagating reaction foil with beveled edges (8) at both ends and a parallelogram shape overall.

9. The laser-assisted connection device for a silicon nitride tungsten alloy heating element according to claim 6, characterized in that: The fixing assembly (64) includes a lead screw (641), a connecting rod (643), a clamp (644), and a guide rod (645) fixedly connected to the pretreatment device. The lead screw (641) has two symmetrically arranged sliders (642) threadedly connected to its surface. The guide rod (645) has two symmetrically arranged sliders (642) slidably connected to its surface. The two sliders (642) on the same horizontal plane are fixedly connected to each other by the connecting rod (643). The clamp (644) is fixedly connected to one side of each slider (642), and the clamp (644) contacts the pin (10).

10. The laser-assisted connection device for a silicon nitride tungsten alloy heating element according to claim 6, characterized in that: The pretreatment device (6) is provided with a cutting component (66), including: a lead screw (662) and a cutter (661). The lead screw (662) is rotatably connected to the pretreatment device (6), and its surface is threadedly connected to the cutter (661). The cutter (661) is slidably connected to the inner wall of the pretreatment device (6), and the cutting surface of the cutter (661) is a right-angled triangle.

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