A method for batch coaxial manufacturing of tungsten-rhenium coaxial thermocouples for measuring radiation heat flux

Abstract

The present invention provides a method for batch coaxial manufacturing of tungsten-rhenium coaxial thermocouples for measuring radiant heat flux, including: a coaxial spray coating step for forming a three-layer coaxial structure sensitive core body of an inner tungsten-rhenium wire, an intermediate dielectric insulating film, and an outer tungsten thermoelectric film, with the tungsten-rhenium wire as the tungsten-rhenium inner conductor layer of the sensitive core body of the tungsten-rhenium coaxial thermocouple; a sensitive core body sintering step to completely cure the insulating film and the tungsten thermoelectric film, forming the insulating layer and the tungsten outer conductor layer of the coaxial thermocouple sensitive core body; and a package housing assembly step for embedding the sensitive core body into a protective tube, grinding the top end of the sensitive core body to form a temperature measurement node, and coating a high emissivity coating on the probe end. By the method of the present invention, tungsten-rhenium coaxial thermocouples with a transient temperature measurement upper limit of up to 3000K and a radiant heat flux measurement upper limit of up to 100 MW / m<supgt;2< / supgt; can be rapidly batch prepared, with small size, low cost, and fast response, and can be applied to radiant heat flux measurement in extremely high temperature environments and environments with rapid temperature changes.

Description

Technical Field

[0001] The invention belongs to the technical field of sensor preparation, and in particular relates to a batch coaxial manufacturing method of tungsten-rhenium coaxial thermocouples for measuring radiation heat flux. Background Art

[0002] Radiative heat flux is the flow of heat transferred from the surface of an object in the form of electromagnetic waves. Its measurement is of great significance for thermal protection design, material thermal property research and thermal protection system evaluation in high temperature environments. In the fields of aerospace, nuclear energy and industrial manufacturing, accurate measurement of radiative heat flux is an important basis for evaluating heat load and optimizing design.

[0003] Existing radiation heat flux measurement technologies generally use sensors such as thermopile radiometers, photothermal radiometers, and infrared heat flux meters. These radiation heat flux sensors are usually large in size, inflexible in installation and application, and difficult to adapt to the application requirements of miniaturization or extreme environments. In addition, in high-temperature and rapid thermal shock environments, the response time of many sensors cannot meet the microsecond measurement requirements. In addition, the range of most radiation heat flux sensors is less than 40MW / m 2 , it is difficult to operate in ultra-high temperature environments (>2000K) and high-intensity radiation heat flux environments (50-100 MW / m 2 ) is used in

[0004] Low production efficiency and high cost are another significant problem of radiation heat flux sensors. The manufacturing process of many radiation heat flux sensors is complicated and requires a lot of machining operations, resulting in long production cycles and difficulty in large-scale production. This not only increases production costs, but also makes companies lack flexibility when facing changes in market demand. Especially in the production of radiation heat flux sensors, the selection of materials and processing technology are even more complicated, further increasing costs.

[0005] Existing coaxial thermocouples do not use the process of tungsten slurry coating and sintering to form tungsten grade. Generally, a tungsten alloy tube is used, which is directly sheathed on the tungsten rhenium wire and filled with insulating glue between the two.

[0006] In view of this, it is very meaningful to propose a batch coaxial manufacturing method of tungsten-rhenium coaxial thermocouples for radiation heat flux measurement. Summary of the invention

[0007] In order to solve the problem that the coaxial thermocouples in the prior art do not adopt the process of tungsten slurry coating and sintering to form tungsten grade, resulting in poor product performance consistency and insufficient insulation performance, the present invention provides a batch coaxial manufacturing method of tungsten-rhenium coaxial thermocouples for radiation heat flux measurement, which greatly improves the performance and insulation performance of the product, has significant measurement capabilities, and can realize rapid batch preparation of high-performance tungsten-rhenium coaxial thermocouples to meet the radiation heat flux measurement needs in extremely high temperature environments and environments with rapid temperature changes.

[0008] In the first aspect, the present invention proposes a method for manufacturing a tungsten-rhenium coaxial thermocouple for measuring radiation heat flux, the method comprising the following steps: a coaxial spray coating step, a sensitive core sintering step, and a packaging tube shell assembly, wherein the coaxial spray coating step specifically comprises:

[0009] S11, tightly connect one end of the coaxial needle to the mouth of a syringe filled with medium slurry, install the syringe on an electric syringe pump, and at the same time, adhere one end of the cleaned tungsten-rhenium wire to the precision displacement platform through tape, and make it pass through the heating tube and extend into the other end of the coaxial needle;

[0010] S12, start the electric injection pump, control the dielectric slurry to be uniformly injected at a rate of 8 to 12 μl / min, spray the dielectric slurry on the tungsten-rhenium wire at the coaxial needle mouth, then start the precision displacement platform, drive the tungsten-rhenium wire sprayed with the dielectric slurry to move at a uniform rate of 8 to 12 cm / min through the heating tube, so that the dielectric slurry is initially solidified to form a dielectric insulating film with a thickness of 20 to 30 μm;

[0011] S13, taking another new coaxial needle with a larger caliber, installing one end of the new coaxial needle on the electric syringe pump, and filling the syringe pump tube with tungsten slurry;

[0012] S14, repeat the above-mentioned tungsten-rhenium wire fixing and moving operations, spray the tungsten slurry on the dielectric insulating film of the tungsten-rhenium wire at the coaxial needle mouth, and the heating tube preliminarily solidifies the tungsten slurry to form a tungsten thermoelectric film with a thickness of 20 to 30 μm, thereby forming a three-layer coaxial structure sensitive core of the inner layer of the tungsten-rhenium wire, the middle layer of the dielectric insulating film, and the outer layer of the tungsten thermoelectric film, and the tungsten-rhenium wire serves as the tungsten-rhenium inner conductor layer of the tungsten-rhenium coaxial thermocouple sensitive core.

[0013] Preferably, in step S12, the injection rate of the electric injection pump is 10 μl / min, the displacement rate of the precision displacement platform is 10 cm / min, and the displacement range is 0.1 m.

[0014] Preferably, in step S12, the dielectric insulating film formed by the preliminary solidification of the dielectric slurry has a thickness of 20-25 μm and a length of 0.1 m.

[0015] Preferably, in step S14, the tungsten thermoelectric thin film formed by preliminarily solidifying the tungsten slurry in the heating tube has a thickness of 20 to 25 μm and a length of 0.1 m.

[0016] Preferably, in the coaxial printing coating step, the viscosity of the medium slurry is 50 ~ 100cP, the viscosity of the tungsten slurry is 80 ~ 150cP, and during the printing process, the ambient humidity is maintained at 40% ~ 60% to ensure the stability of the printing quality and film performance.

[0017] Preferably, before step S11, the method further includes: S10, using an alcohol solution to ultrasonically clean a tungsten-rhenium wire with a diameter of 0.5 mm, the cleaning time being not less than 10 minutes, so as to completely remove impurities on the surface of the wire.

[0018] Preferably, the sensitive core sintering step specifically includes:

[0019] S21, place the three-layer coaxial structure sensitive core into a tubular furnace, ventilate the tubular furnace through an argon bottle for at least 5 minutes to exhaust all the oxygen in the furnace, and adjust the air pressure valve to control the air intake rate at 10 ~ 20L / min;

[0020] S22, setting the starting temperature of the tubular furnace to 20-30°C, the heating rate in the range of 20-400°C to 8-12°C / min, keeping warm at 400°C for 50-70min, the heating rate in the range of 400-1200°C to 8-12°C / min, the heating rate in the range of 1200-1450°C to 4-6°C / min, keeping warm at 1450°C for 50-70min, then cooling naturally, closing the air pressure valve after the temperature drops to room temperature, and after sintering in the tubular furnace, completely solidifying the dielectric insulating film and the tungsten thermoelectric film to form an insulating layer of the sensitive core and a tungsten outer conductor layer;

[0021] S23, take a tungsten wire with a diameter of 0.4 ~ 0.6mm, put one end of it in close contact with the tungsten outer conductor layer of the sensitive core, and use high-temperature glue at a temperature of 180 ~ 220℃ to bond the tungsten wire and the tungsten outer conductor layer of the sensitive core into a stable conductive loop.

[0022] Further preferably, the packaging tube shell assembling step specifically includes:

[0023] S31, taking the high temperature adhesive as the dividing point, putting a heat shrink tube on the tungsten wire and tungsten-rhenium wire part under the high temperature adhesive, and using a hot air gun to tightly wrap the heat shrink tube with the tungsten wire and tungsten-rhenium wire, and the shrinkage rate of the heat shrink tube is 50% to 70%;

[0024] S32, inserting the sensitive core into a 304 stainless steel tube shell with a length of 0.08 to 0.12 m, filling an appropriate amount of the high temperature glue into the 304 stainless steel tube shell, heating the high temperature glue to expand it under the heat to fill the gap between the sensitive core and the stainless steel tube shell, and bonding the sensitive core and the stainless steel tube shell;

[0025] S33. Use an electric grinder to grind the tungsten-rhenium inner conductor layer and the tungsten outer conductor layer at the top of the sensitive core. The tungsten particles and the tungsten-rhenium particles generated by grinding are bridged with each other to form a temperature measuring node of the tungsten-rhenium coaxial thermocouple, and a high-emissivity coating with a thickness of 5 to 15 μm is coated on the temperature measuring node to improve the absorption efficiency of the radiation heat flow.

[0026] In a second aspect, an embodiment of the present invention provides a method for batch coaxial manufacturing of tungsten-rhenium coaxial thermocouples for radiation heat flux measurement, which is prepared according to the manufacturing method of tungsten-rhenium coaxial thermocouples for radiation heat flux measurement as described in the first aspect, and also includes: cutting the prepared sensitive core into multiple sections to achieve batch preparation.

[0027] In a third aspect, an embodiment of the present invention provides a batch coaxially manufactured tungsten-rhenium coaxial thermocouple for measuring radiation heat flux, which is prepared according to the batch coaxial manufacturing method of tungsten-rhenium coaxial thermocouples for measuring radiation heat flux as described in the second aspect, including:

[0028] The sensitive core is composed of a three-layer coaxial structure with an inner tungsten-rhenium wire, a middle dielectric insulating film and an outer tungsten thermoelectric film, wherein the inner tungsten-rhenium wire has a diameter of 0.5 mm, the dielectric insulating film has a thickness of 20 to 30 μm, and the tungsten thermoelectric film has a thickness of 20 to 30 μm;

[0029] The protective tube shell is made of 304 stainless steel, has a length of 0.08 to 0.12 m, and its inner diameter is adapted to the sensitive core body, and is used to accommodate and protect the sensitive core body. A high-temperature glue is filled between the protective tube shell and the sensitive core body, and the filling rate of the high-temperature glue is greater than 80%;

[0030] A temperature measuring node, the temperature measuring node is located at the top of the sensitive core, the surface roughness of the temperature measuring node is less than 0.5 μm, and a high emissivity coating with a thickness of 5 to 15 μm is coated on the temperature measuring node, and the emissivity of the coating is greater than 0.9;

[0031] The connecting wire comprises a tungsten wire connected to the tungsten outer conductor layer of the sensitive core and a homogeneous tungsten-rhenium wire connected to the inner tungsten-rhenium wire, wherein the diameter of the tungsten wire is 0.4-0.6 mm, the tungsten wire and the tungsten-rhenium wire are firmly bonded at the connection part with the sensitive core by the high-temperature adhesive, and heat shrink tubes are respectively provided at the non-connection parts for insulation protection, and the shrinkage rate of the heat shrink tubes is 50%-70%.

[0032] Compared with the prior art, the beneficial results of the present invention are:

[0033] Through the preparation process provided by the present invention, a sensitive core insulation layer and a tungsten outer conductor layer with a thickness of microns can be efficiently spray-printed on the tungsten-rhenium wire. The core feature of the process is the compatibility of the materials of each layer of the sensitive core, which allows the prepared sensitive core to be cut into multiple sections, thereby realizing batch preparation of the sensitive core. These sensitive cores can be packaged to quickly batch prepare high-performance tungsten-rhenium coaxial thermocouples. Further coating a high-emissivity coating with a thickness of microns on the surface of the probe can significantly enhance the sensitivity of the tungsten-rhenium coaxial thermocouple to radiant heat flux. Combined with the Seebeck effect and the Stefan-Boltzmann law, the voltage signal output by the thermocouple can be accurately converted into radiant heat flux data. The upper limit of the radiant heat flux measurement of the prepared tungsten-rhenium coaxial thermocouple can reach 100 MW / m 2 The diameter of the temperature measuring probe is less than 1mm, which significantly reduces the size and production cost compared with the traditional radiation heat flux sensor, greatly improves the response speed and measurement upper limit, and is more convenient to install. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated into and constitute a part of this specification. The accompanying drawings illustrate the embodiments and are used together with the description to explain the principles of the present invention. It will be easy to recognize other embodiments and many expected advantages of the embodiments because they become better understood by reference to the following detailed description. The elements of the drawings are not necessarily to scale with each other. The same reference numerals refer to corresponding similar parts.

[0035] Figure 1 It is a schematic flow chart of a method for manufacturing a tungsten-rhenium coaxial thermocouple for measuring radiation heat flux according to an embodiment of the present invention;

[0036] Figure 2 A schematic diagram of a sensitive core preparation device platform according to an embodiment of the present invention;

[0037] Figure 3 A schematic diagram of a coaxial needle syringe according to an embodiment of the present invention;

[0038] Figure 4 A schematic diagram of the structure of a sensitive core according to an embodiment of the present invention;

[0039] Figure 5 A coaxial thermocouple diagram of an embodiment of the present invention;

[0040] Figure 6 This is a laser 3000°C test diagram of an embodiment of the present invention.

[0041] Description of the drawings: 1. Tungsten-rhenium wire; 2. Coaxial needle side port; 3. Syringe barrel; 4. Syringe piston protrusion; 5. Electric injection pump groove; 6. Coaxial needle positive port; 7. Heating tube; 8. Precision displacement platform slide; 9. Tape; 10. Electric injection pump; 11. Precision displacement platform; 12. Coaxial needle port; 13. Insulation layer; 14. Tungsten outer conductor layer; 15. Tungsten wire; 16. High temperature glue; 17. Heat shrink tubing; 18. 304 stainless steel tube shell; 20. High emissivity coating. DETAILED DESCRIPTION

[0042] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the relevant invention are shown in the accompanying drawings.

[0043] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0044] In a first aspect, an embodiment of the present invention discloses a method for manufacturing a tungsten-rhenium coaxial thermocouple for measuring radiation heat flux, such as Figure 1 As shown, the method includes a coaxial spray coating step, a sensitive core sintering step and a packaging tube shell assembly step, referring to Figure 2 and Figure 3 The coaxial printing coating steps specifically include:

[0045] S10, using an alcohol solution to ultrasonically clean a tungsten-rhenium wire 1 having a diameter of 0.5 mm, the cleaning time being not less than 10 minutes, so as to completely remove impurities on the wire surface;

[0046] S11, tightly connect one end of the coaxial needle to the 3 ports of the syringe barrel filled with medium slurry, install the syringe on the electric injection pump 10, and at the same time, adhere one end of the cleaned tungsten-rhenium wire 1 to the precision displacement platform 11 through the tape 9, and make it pass through the heating tube 7 and extend into the other end of the coaxial needle;

[0047] S12, start the electric injection pump 10, control the medium slurry to be uniformly injected at a rate of 8 to 12 μl / min, spray the medium slurry on the tungsten-rhenium wire 1 at the coaxial needle port 12, and then start the precision displacement platform 11 to drive the tungsten-rhenium wire 1 with the medium slurry sprayed on it to move at a uniform rate of 8 to 12 cm / min through the heating tube 7, so that the medium slurry is initially solidified to form a dielectric insulating film with a thickness of 20 to 30 μm;

[0048] Specifically, as shown in Table 1 below, the injection rate of the electric syringe pump 10 is explored. When the injection rate of the electric syringe pump 10 is 8μl / min, the thickness uniformity deviation of the dielectric insulating film is ±12%. Due to the slow injection rate, the material distribution of the film may not be uniform during the formation process, making the internal porosity of the film relatively high, reaching 5%, and the bonding force with the tungsten-rhenium wire is weak, which is 3N. When the injection rate is increased to 10μl / min, the thickness uniformity is improved to ±8%, the internal porosity of the film is reduced to 3%, and the bonding force is enhanced to 5N. This is because the appropriate injection rate can make the dielectric slurry more stably coated on the tungsten-rhenium wire to form a better quality film. When the injection rate is 12μl / min, the thickness uniformity is ±10%, the porosity is 4%, and the bonding force is 4N. Although a fast injection rate can improve production efficiency, too fast may slightly affect the uniformity and quality of the film.

[0049] Therefore, in this embodiment, the best technical effect can be achieved by setting the injection rate of the electric injection pump 10 to 10μl / min. At this injection rate, the thickness uniformity deviation of the dielectric insulating film is controlled at ±8%, which is significantly improved compared to ±12% at 8μl / min, effectively ensuring the consistency of the film thickness and making the sensor performance more stable. At the same time, the internal porosity of the film is reduced to 3%, which is a significant reduction compared to 5% at 8μl / min, reducing the adverse effects of the pores on the insulation performance and thermal conductivity performance, and improving the insulation effect and thermal conductivity efficiency. In addition, the bonding force with the tungsten-rhenium wire is enhanced to 5N, which is significantly improved compared to 3N at 8μl / min, ensuring the firmness of the film during use and reducing the risk of performance degradation due to loose bonding, thereby improving the performance and reliability of the tungsten-rhenium coaxial thermocouple as a whole, so that it can work more accurately and stably in the measurement of radiation heat flow.

[0050] Table 1

[0051] Experimental Grouping Injection rate (μl / min) Dielectric insulation film thickness uniformity (%) Porosity inside the film (%) Bonding force between film and tungsten-rhenium wire (N) Group 1 8 ±12 5 3 Group 2 10 ±8 3 5 Group 3 12 ±10 4 4

[0052] As shown in Table 2 below, the displacement rate of the precision displacement platform 11 is explored. When the displacement rate of the precision displacement platform 11 is 8cm / min, the curing integrity of the dielectric insulating film is 90%. Due to the slow displacement rate, the film stays in the heating tube 7 for a relatively long time, which may cause a slight decrease in surface flatness to 5μm, but the production efficiency is low at this time, only 4.8m / h. When the displacement rate is 10cm / min, the curing integrity of the dielectric insulating film is improved to 95%, the surface flatness is 2μm, and the production efficiency is improved to 6m / h. At this time, the production efficiency can be improved while ensuring the quality of the film. When the displacement rate is 12cm / min, the curing integrity is 92%, the surface flatness is 3μm, and the production efficiency is 7.2m / h. Too fast a displacement rate may cause the film to stay in the heating tube 7 for insufficient time, affecting the curing effect and surface quality.

[0053] Therefore, in this embodiment, it is of significant advantage to determine the displacement rate of the precision displacement platform 11 to be 10cm / min. At this displacement rate, the curing integrity of the dielectric insulating film is as high as 95%, which is significantly improved compared to 90% at 8cm / min, ensuring the curing quality of the film, so that it can stably play an insulating role in the subsequent use process, and reducing performance problems that may be caused by incomplete curing. At the same time, the surface flatness reaches 2μm, which is greatly improved compared to 5μm at 8cm / min, ensuring the smoothness of the film surface, which is conducive to the subsequent close integration with other components and the stable performance of thermal conductivity and other properties. In addition, the production efficiency is increased to 6m / h. Under the premise of ensuring the high quality of the film, it is significantly improved compared to 4.8m / h at 8cm / min, achieving a good balance between production efficiency and product quality, which helps to improve the efficiency of the overall manufacturing process and the market competitiveness of the product, thereby better meeting the performance and production requirements of tungsten-rhenium coaxial thermocouples for radiation heat flux measurement.

[0054] Table 2

[0055] Experimental Grouping Displacement rate (cm / min) Dielectric insulation film curing integrity (%) Film surface smoothness (μm) Production efficiency (m / h) Group 1 8 90 5 4.8 Group 2 10 95 2 6 Group 3 12 92 3 7.2

[0056] Further, as shown in Table 3 below, the thickness of the dielectric insulating film is explored. When the thickness of the dielectric insulating film is 10μm, the insulation resistance is 500MΩ. Due to the thin thickness, the film has good flexibility, but the thermal stability is relatively low at 1000℃. As the thickness increases to 25μm, the insulation resistance increases to 800MΩ, the thermal stability increases to 1400℃, but the flexibility becomes general. When the thickness is 50μm, the insulation resistance is 600MΩ, the flexibility is poor, and the thermal stability is 1200℃. Too thick a film may affect its comprehensive performance due to internal stress and other problems.

[0057] Therefore, in this embodiment, the thickness of the dielectric insulating film formed by the preliminary curing of the dielectric slurry is set to about 25μm, which is an optimal choice after comprehensive consideration of various factors. The dielectric insulating film at this thickness performs well in terms of insulation performance, and its insulation resistance can reach 800MΩ, which is significantly improved compared to 500MΩ at a thickness of 10μm. It can effectively reduce the risk of leakage, ensure the stable operation of the thermocouple in a complex electromagnetic environment, and provide reliable electrical insulation protection for accurate measurement of radiant heat flow. In terms of thermal stability, it can withstand temperatures up to 1400°C, which greatly expands the applicable high temperature range of the sensor compared to the thermal stability of only 1000°C at a thickness of 10μm, allowing it to operate normally in more severe high temperature environments, meeting the extreme high temperature measurement needs in fields such as aerospace, nuclear energy, etc. Although its flexibility becomes average, in practical applications, under the premise of ensuring key performance, this moderate sacrifice of flexibility is acceptable, and through reasonable packaging and installation design, film damage caused by flexibility problems can be effectively avoided, thereby ensuring the reliability and durability of the entire tungsten-rhenium coaxial thermocouple device and achieving efficient and accurate radiation heat flux measurement.

[0058] Table 3

[0059] Experimental Grouping Film thickness (μm) Dielectric insulation properties (insulation resistance, MΩ) Film flexibility Film thermal stability (℃) Group 1 10 500 better 1000 Group 2 25 800 generally 1400 Group 3 50 600 Poor 1200

[0060] Furthermore, in the specific repeated experiments and operation process, it was found that it is very important to strictly control the viscosity of the dielectric slurry at 50-100cP and the viscosity of the tungsten slurry at 80-150cP in the coaxial inkjet coating step. The appropriate viscosity of the dielectric slurry can ensure that it can flow stably under the action of the electric injection pump 10, and be ejected from the coaxial needle at a uniform rate, thereby forming a dielectric insulating film with uniform thickness and no obvious defects on the tungsten rhenium wire 1. If the viscosity deviates from this range, too low may cause the slurry to flow too fast, making it difficult to form a film of the expected thickness and shape; too high will make injection difficult, and even clog the needle, affecting the continuity of the printing process and the quality of the film.

[0061] The viscosity of 80-150cP for tungsten paste can ensure good adhesion to the dielectric insulating film during printing, and form a tightly bonded and stable tungsten thermoelectric film after the initial curing of the heating tube. Similarly, inappropriate viscosity will cause problems such as uneven coating and weak bonding with the underlying film, which will damage the performance of the sensitive core.

[0062] At the same time, maintaining the humidity of the printing environment within the range of 40% - 60% can effectively reduce the adverse effects of moisture on the slurry. Too high humidity may dilute the slurry, change its original performance and printing effect; too low humidity can easily cause problems such as static electricity, interfere with the stability of the printing process, affect the quality and uniformity of the film, and ultimately have an adverse effect on the overall performance of the tungsten-rhenium coaxial thermocouple.

[0063] In summary, in this embodiment, after experimental testing and comparison, as preferred, the injection rate of the electric injection pump 10 is 10μl / min, the displacement rate of the precision displacement platform 11 is 10cm / min, and the displacement range is 0.1m. The thickness of the dielectric insulating film formed by the preliminary solidification of the dielectric slurry is 25μm and the length is 0.1m. The viscosity of the dielectric slurry is 50~100cP, the viscosity of the tungsten slurry is 80~150cP, and during the printing process, the ambient humidity is maintained at 40%~60% to ensure the stability of the printing quality and film performance.

[0064] S13, take another new coaxial needle with a larger caliber, install one end of the new coaxial needle on the electric syringe pump 10, and fill the syringe pump tube with tungsten slurry;

[0065] S14, repeat the above-mentioned tungsten-rhenium wire 1 fixing and moving operations, spray-print tungsten slurry on the dielectric insulating film of the tungsten-rhenium wire 1 at the coaxial needle mouth 12, and preliminarily solidify the tungsten slurry by the heating tube 7 to form a tungsten thermoelectric film with a thickness of 20 to 30, thereby forming a three-layer coaxial structure sensitive core of an inner layer of tungsten-rhenium wire 1, a middle layer of dielectric insulating film, and an outer layer of tungsten thermoelectric film, and the tungsten-rhenium wire 1 serves as the tungsten-rhenium inner conductor layer of the tungsten-rhenium coaxial thermocouple sensitive core.

[0066] The embodiment of the present invention adopts coaxial needle printing technology to sequentially print insulating slurry and tungsten slurry on a thin tungsten-rhenium wire 1 with a diameter of 0.5 mm. The electric injection pump 10 is used to accurately control the printing rate and the precision displacement platform 11 is used to adjust the moving speed of the tungsten-rhenium wire 1. This digital and refined operation can achieve precise control of the thickness of each layer, forming a three-layer coaxial thermocouple structure sensitive core with an inner layer of tungsten-rhenium wire 1, an intermediate layer of dielectric insulating film and an outer layer of tungsten thermoelectric film. However, the existing coaxial thermocouple does not use the process of tungsten slurry coating and sintering to form a tungsten grade. Generally, a tungsten alloy tube is used, which is directly sleeved on the tungsten-rhenium wire 1 and filled with insulating glue between the two. The use of coaxial needle printing technology greatly improves the performance and insulation performance of the product, and the measurement capability is significant.

[0067] Reference Figure 4 , the sensitive core sintering steps specifically include:

[0068] S21, place the three-layer coaxial structure sensitive core into a tubular furnace, ventilate the tubular furnace through an argon bottle for at least 5 minutes to exhaust all the oxygen in the furnace, and adjust the air pressure valve to control the air intake rate at 10 ~ 20L / min;

[0069] S22, setting the starting temperature of the tubular furnace to 20-30°C, heating up at a rate of 8-12°C / min in the range of 20-400°C, keeping at 400°C for 50-70min, heating up at a rate of 8-12°C / min in the range of 400-1200°C, heating up at a rate of 4-6°C / min in the range of 1200-1450°C, keeping at 1450°C for 50-70min, then cooling naturally, closing the air pressure valve after the temperature drops to room temperature, and after sintering in the tubular furnace, completely solidifying the dielectric insulating film and the tungsten thermoelectric film to form the insulating layer 13 of the sensitive core and the tungsten outer conductor layer 14;

[0070] S23, take a tungsten wire 15 with a diameter of 0.4-0.6 mm, put one end of it in close contact with the sensitive core tungsten outer conductor layer 14, and use high temperature glue 16 to bond the tungsten wire 15 and the sensitive core tungsten outer conductor layer 14 into a stable conductive loop at a temperature of 180-220°C.

[0071] Reference Figure 5 , the package shell assembly steps specifically include:

[0072] S31, with the high temperature glue 16 as the dividing point, the tungsten wire 15 and the tungsten-rhenium wire 1 partly covered with the heat shrink tube 17 under the high temperature glue 16, and the heat shrink tube 17, the tungsten wire 15 and the tungsten-rhenium wire 1 are tightly wrapped with a hot air gun, and the shrinkage rate of the heat shrink tube 17 is 50% to 70%;

[0073] S32, insert the sensitive core into a 304 stainless steel tube shell 18 with a length of 0.08 to 0.12 m, fill an appropriate amount of high temperature glue 16 into the 304 stainless steel tube shell 18, heat the high temperature glue 16 to expand due to heat to fill the gap between the sensitive core and the stainless steel tube shell, and bond the sensitive core and the stainless steel tube shell;

[0074] S33. Use an electric grinder to grind the tungsten-rhenium inner conductor layer and the tungsten outer conductor layer 14 at the top of the sensitive core. The tungsten particles and the tungsten-rhenium particles generated by grinding are bridged with each other to form a temperature measuring node of the tungsten-rhenium coaxial thermocouple, and a high-emissivity coating 20 with a thickness of 5 to 15 μm is coated on the temperature measuring node to improve the absorption efficiency of the radiation heat flow.

[0075] In a specific embodiment, a method for batch coaxial manufacturing of tungsten-rhenium coaxial thermocouples for measuring radiation heat flux is described in detail. Figure 2 and Figure 3 , including the following steps:

[0076] Step 1: Take a tungsten-rhenium wire 1 with a diameter of 0.5 mm and a length of 0.5 m, and immerse it completely in a glass measuring cylinder filled with alcohol solution. Put the glass measuring cylinder into an ultrasonic cleaner and set the cleaning time to 10 minutes. After cleaning, the surface of the tungsten-rhenium wire is smooth and free of impurities.

[0077] Step 2: Install the coaxial needle side port 2 at the outlet of the syringe barrel 3, fill the medium slurry into the syringe barrel 3, embed the syringe piston protrusion 4 into the groove 5 of the electric injection pump, insert the tungsten-rhenium wire 1 from the coaxial needle positive port 6, pass through the heating tube 7, and place it on the precision displacement platform slide 8. Use tape 9 to stick one end of the tungsten-rhenium wire 1 to the precision displacement platform slide 8.

[0078] Step 3: Set the injection rate of the electric injection pump 10 to 10 μl / min, the displacement rate of the precision displacement platform 11 to 10 cm / min, and the displacement range to 0.1 m. Start the electric injection pump 10. The groove 5 of the electric injection pump pushes the syringe piston protrusion 4 to move at a uniform speed, thereby controlling the uniform injection of the medium slurry into the coaxial needle side port 2. After the medium slurry flows out of the coaxial needle port 12 and is sprayed on the tungsten rhenium wire 1, start the precision displacement platform 11. The precision displacement platform slide 8 drives the tungsten rhenium wire 1 sprayed with the medium slurry to move 0.1 m to the left at a uniform speed. At the same time, the tungsten rhenium wire 1 sprayed with the medium slurry passes through the heating tube 7. The medium slurry is initially cured by heat to form a dielectric insulating film with a length of 0.1 m and a thickness of micrometers.

[0079] Step 4: Take another new coaxial needle with a larger caliber, repeat the above equipment setting parameters and steps, fill the syringe barrel 3 with tungsten slurry, and the groove 5 of the electric injection pump pushes the syringe piston protrusion 4 to move at a uniform speed, thereby controlling the tungsten slurry to be uniformly injected into the coaxial needle side port 2. After the tungsten slurry flows out from the coaxial needle port 12 and is sprayed on the tungsten rhenium wire 1 covered with a dielectric insulating film, start the precision displacement platform 11. The precision displacement platform slide 8 drives the tungsten rhenium wire 1 sprayed with tungsten slurry to move 0.1m to the left at a uniform speed, and passes through the heating tube 7. The tungsten slurry is heated and initially solidified on the dielectric insulating film to form a tungsten thermoelectric film with a length of 0.1m and a thickness of microns, forming a three-layer coaxial structure sensitive core with an inner tungsten rhenium wire 1, an intermediate dielectric insulating film, and an outer tungsten thermoelectric film. For details, refer to Figure 4 Schematic diagram of the sensitive core structure.

[0080] Step 5: Place the three-layer coaxial structure sensitive core into the tubular furnace, turn the argon bottle inlet valve, feed argon into the tubular furnace for 5 minutes, exhaust the oxygen in the furnace, set the starting temperature of the tubular furnace to 25°C, increase the temperature at a rate of 10°C / min in the range of 25°C ~ 400°C, keep it at 400°C for 1 hour, increase the temperature at a rate of 10°C / min in the range of 400°C ~ 1200°C, increase the temperature at a rate of 5°C / min in the range of 1200°C ~ 1450°C, keep it at 1450°C for 1 hour, then cool it down naturally, close the inlet valve after the temperature drops to room temperature, and after sintering in the tubular furnace, the dielectric insulating film and the tungsten thermoelectric film are completely solidified to form a sensitive core insulation layer 13 and a tungsten outer conductor layer 14 respectively. At this time, the sensitive core is a filament of an inner tungsten rhenium wire 1, an intermediate insulating layer 13, and an outer tungsten outer conductor layer 14.

[0081] Step 6: Take a tungsten wire 15 with a diameter of 0.5 mm and a length of 0.4 m, and place one end of the tungsten wire in contact with the tail end of the tungsten outer conductor layer 14. Use high-temperature glue 16 to bond the tungsten wire 15 to the tungsten outer conductor layer 14. The tungsten wire 15 and the tungsten outer conductor layer 14 are stably connected to form a conductive loop.

[0082] Step 7: Cover the tungsten wire 15 and the tungsten-rhenium wire 1 under the high-temperature adhesive 16 with heat shrink tubes 17 respectively, and use a hot air gun to heat the heat shrink tubes 17 so that they tightly wrap the tungsten wire 15 and the tungsten-rhenium wire 1.

[0083] Step 8: Insert the sensitive core into a 304 stainless steel tube shell 18 with a length of 0.1m. The 304 stainless steel tube shell 18 wraps the sensitive core at the position of the high-temperature glue 16. Fill a proper amount of alumina glue into the 304 stainless steel tube shell 18. Heat the alumina glue to make it expand when heated to fill the gap between the sensitive core and the 304 stainless steel tube shell 18.

[0084] Step 9: Use an electric grinder to grind the top of the sensitive core. By grinding the inner tungsten-rhenium wire 1 and the tungsten outer conductor layer 14 at the top, tungsten particles and tungsten-rhenium particles are bridged to form a temperature measurement node of the tungsten-rhenium coaxial thermocouple.

[0085] Step 10: Take a cotton swab and dip it into a small amount of high emissivity paint, and use the cotton swab to evenly apply the high emissivity paint on the surface of the tungsten-rhenium coaxial thermocouple temperature measurement node to form a high emissivity coating 20 with a thickness of microns. Figure 5 Diagram of a coaxial thermocouple is shown.

[0086] In a second aspect, an embodiment of the present invention further discloses a method for batch coaxial manufacturing of tungsten-rhenium coaxial thermocouples for radiation heat flow measurement, which is prepared according to the manufacturing method of tungsten-rhenium coaxial thermocouples for radiation heat flow measurement according to the first aspect. Figure 5 The coaxial thermocouple diagram of this embodiment is shown, and the method further includes: cutting the prepared sensitive core into multiple sections to achieve batch preparation.

[0087] The method for batch coaxial manufacturing of tungsten-rhenium coaxial thermocouples for radiation heat flux measurement disclosed in the present invention can cut the prepared sensitive core into multiple sections to achieve batch production based on the consistency of the sensitive core material. Traditional radiation heat flux sensor manufacturing technology is often difficult to achieve efficient batch production, and the production process is complicated and costly. The present invention can quickly batch prepare high-performance tungsten-rhenium coaxial thermocouples, greatly improve production efficiency, reduce production costs, and is conducive to large-scale promotion and application in the field of radiation heat flux measurement, meeting the needs of industrial production and other aspects for a large number of high-precision, high-performance radiation heat flux measurement thermocouples, and can ensure the consistency and stability of product performance during the batch production process.

[0088] In a third aspect, an embodiment of the present invention provides a batch coaxially manufactured tungsten-rhenium coaxial thermocouple for measuring radiation heat flux, which is prepared according to the batch coaxial manufacturing method of the tungsten-rhenium coaxial thermocouple for measuring radiation heat flux as in the second aspect, such as Figure 5 As shown, including:

[0089] The sensitive core is composed of a three-layer coaxial structure with an inner tungsten-rhenium wire 1, a middle dielectric insulating film and an outer tungsten thermoelectric film, wherein the inner tungsten-rhenium wire 1 has a diameter of 0.5 mm, the dielectric insulating film has a thickness of 20 to 30 μm, and the tungsten thermoelectric film has a thickness of 20 to 30 μm;

[0090] The protective tube shell is made of 304 stainless steel, with a length of 0.08 ~ 0.12m, and its inner diameter is adapted to the sensitive core body, and is used to accommodate and protect the sensitive core body. The protective tube shell and the sensitive core body are filled with high temperature glue 16, and the filling rate of the high temperature glue 16 is greater than 80%;

[0091] A temperature measuring node, the temperature measuring node is located at the top of the sensitive core, the surface roughness of the temperature measuring node is less than 0.5 μm, and a high emissivity coating 20 with a thickness of 5 to 15 μm is coated on the temperature measuring node, and the emissivity of the coating is greater than 0.9;

[0092] The connecting wire includes a tungsten wire 15 connected to the tungsten outer conductor layer 14 of the sensitive core and a homogeneous tungsten-rhenium wire 1 connected to the inner tungsten-rhenium wire 1. The diameter of the tungsten wire 15 is 0.4 to 0.6 mm. The tungsten wire 15 and the tungsten-rhenium wire 1 are firmly bonded at the connection position with the sensitive core by a high-temperature adhesive 16, and heat shrink tubes 17 are respectively provided at non-connection positions for insulation protection. The shrinkage rate of the heat shrink tube 17 is 50% to 70%.

[0093] The tungsten-rhenium coaxial thermocouple temperature measuring probe prepared in the embodiment of the present invention has a partial size of less than 1 mm, because only a 50-micron thick dielectric insulation layer 13 and a tungsten layer are spray-printed on a 0.5 mm tungsten-rhenium wire 1. Compared with other heat flow sensors, the size is significantly reduced. Another advantage brought by the small size is that the response time can be improved.

[0094] Figure 6 The laser 3000℃ test chart of the embodiment of the present invention is shown. The horizontal axis of the test chart is time (unit: seconds), ranging from 2.33 seconds to 2.38 seconds, and the vertical axis is temperature (unit: Celsius), ranging from 0℃ to 3500℃. It can be seen from the figure that the temperature is close to 0℃ at 2.33 seconds, and then the temperature rises sharply, reaching a peak of 3026.91℃ at around 2.35 seconds. After reaching the peak, the temperature drops rapidly, and the temperature has dropped significantly at 2.38 seconds. Further analysis of the technical effects is as follows:

[0095] Rapid temperature rise: It rises rapidly from nearly 0℃ to 3026.91℃, and the response time is more than 10 microseconds, indicating that the response time of the tungsten-rhenium coaxial thermocouple is in the microsecond level, and it can quickly absorb 3000℃ laser energy, and the heat absorption efficiency is high;

[0096] Rapid cooling: The cooling process is also relatively rapid, reflecting that the tungsten-rhenium coaxial thermocouple has good heat dissipation performance.

[0097] Combined with the test results, the rapid thermal response characteristics of the tungsten-rhenium coaxial thermocouples for measuring radiation heat flux produced in batches coaxially in the embodiments of the present invention under laser irradiation, including the upper limit of temperature measurement, response time, and rapid cooling performance, are significantly improved. It can withstand high temperatures of about 3000°C in a short period of time, and its further application in high temperature environments is of great significance.

[0098] The batch coaxial manufacturing method of tungsten-rhenium coaxial thermocouples for radiation heat flow measurement disclosed in the present invention and the batch coaxially manufactured tungsten-rhenium coaxial thermocouples for radiation heat flow measurement have the following advantages:

[0099] High-performance measurement capability: The transient temperature measurement limit of the prepared tungsten-rhenium coaxial thermocouple can reach 3000K, and the radiation heat flux measurement limit can reach 100MW / m 2 It can meet the precise measurement requirements of extremely high temperature and high-intensity radiation heat flow environments such as aerospace, nuclear energy, etc. The range is greatly improved compared to most existing sensors, providing more reliable data support for thermal protection design, material research and system evaluation in related fields.

[0100] Advantages of miniaturized design: The temperature probe is less than 1mm in size, which is significantly smaller than traditional radiation heat flux sensors. This makes it more advantageous in some applications with strict space requirements, such as more convenient installation and use in miniaturized equipment or small spaces, which broadens the application range of the sensor.

[0101] Fast response characteristics: The smaller size brings faster response time, which can meet the microsecond measurement requirements in high-temperature rapid thermal shock environments, ensure timely and accurate capture of temperature changes, provide strong support for real-time monitoring and control, and effectively overcome the shortcomings of traditional sensors in terms of response speed.

[0102] Efficient batch preparation: Based on the consistency of the sensitive core material, the prepared sensitive core can be cut into multiple sections for batch production. This batch preparation capability significantly improves production efficiency and reduces production costs. Compared with the complex manufacturing technology and long production cycle of traditional manufacturing, this application can more flexibly meet the needs of industrial production for a large number of high-precision, high-performance radiation heat flow measurement thermocouples, and enhance the competitiveness of enterprises in the market.

[0103] The above description is only a preferred embodiment of the present invention and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present invention is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above inventive concept. For example, the above features are replaced with the technical features with similar functions disclosed in the present invention (but not limited to) to form a technical solution.

Claims

1. A method for manufacturing a tungsten-rhenium coaxial thermocouple for measuring radiation heat flux, characterized in that: The method comprises the following steps: a coaxial printing and coating step, a sensitive core sintering step and a packaging tube shell assembly, wherein the coaxial printing and coating step specifically comprises: S11, tightly connect one end of the coaxial needle to the mouth of a syringe filled with medium slurry, install the syringe on an electric syringe pump, and at the same time, adhere one end of the cleaned tungsten-rhenium wire to the precision displacement platform through tape, and make it pass through the heating tube and extend into the other end of the coaxial needle; S12, start the electric injection pump, control the dielectric slurry to be uniformly injected at a rate of 8 to 12 μl / min, spray the dielectric slurry on the tungsten-rhenium wire at the coaxial needle mouth, then start the precision displacement platform, drive the tungsten-rhenium wire sprayed with the dielectric slurry to move at a uniform rate of 8 to 12 cm / min through the heating tube, so that the dielectric slurry is initially solidified to form a dielectric insulating film with a thickness of 20 to 30 μm; S13, taking another new coaxial needle with a larger caliber, installing one end of the new coaxial needle on the electric syringe pump, and filling the syringe pump tube with tungsten slurry; S14, repeat the above-mentioned tungsten-rhenium wire fixing and moving operations, spray the tungsten slurry on the dielectric insulating film of the tungsten-rhenium wire at the coaxial needle mouth, and the heating tube preliminarily solidifies the tungsten slurry to form a tungsten thermoelectric film with a thickness of 20 to 30 μm, thereby forming a three-layer coaxial structure sensitive core of the inner layer of the tungsten-rhenium wire, the middle layer of the dielectric insulating film, and the outer layer of the tungsten thermoelectric film, and the tungsten-rhenium wire serves as the tungsten-rhenium inner conductor layer of the tungsten-rhenium coaxial thermocouple sensitive core.

2. The method for manufacturing a tungsten-rhenium coaxial thermocouple for measuring radiation heat flux according to claim 1, characterized in that: In step S12, the injection rate of the electric injection pump is 10 μl / min, the displacement rate of the precision displacement platform is 10 cm / min, and the displacement range is 0.1 m.

3. The method for manufacturing a tungsten-rhenium coaxial thermocouple for measuring radiation heat flux according to claim 1, characterized in that: In step S12, the dielectric insulating film formed by the preliminary solidification of the dielectric slurry has a thickness of 20-25 μm and a length of 0.1 m.

4. The method for manufacturing a tungsten-rhenium coaxial thermocouple for measuring radiation heat flux according to claim 1, characterized in that: In step S14, the heating tube initially solidifies the tungsten slurry to form a tungsten thermoelectric film with a thickness of 20-25 μm and a length of 0.1 m.

5. The method for manufacturing a tungsten-rhenium coaxial thermocouple for measuring radiation heat flux according to claim 1, characterized in that: In the coaxial printing coating step, the viscosity of the medium slurry is 50-100 cP, the viscosity of the tungsten slurry is 80-150 cP, and during the printing process, the ambient humidity is maintained at 40%-60% to ensure the stability of the printing quality and film performance.

6. The method for manufacturing a tungsten-rhenium coaxial thermocouple for measuring radiation heat flux according to claim 1, characterized in that: Before step S11, the method further includes: S10. Use alcohol solution to ultrasonically clean the tungsten-rhenium wire with a diameter of 0.5 mm for no less than 10 minutes to completely remove impurities on the wire surface.

7. The method for manufacturing a tungsten-rhenium coaxial thermocouple for measuring radiation heat flux according to claim 1, characterized in that: The sensitive core sintering step specifically includes: S21. Place the three-layer coaxial structure sensitive core into a tubular furnace, ventilate the tubular furnace through an argon bottle for at least 5 minutes to exhaust all the oxygen in the furnace, and adjust the air pressure valve to control the air intake rate at 10-20 L / min; S22, setting the starting temperature of the tube furnace to 20-30°C, the heating rate in the range of 20°C-400°C to 8-12°C / min, keeping warm at 400°C for 50-70min, the heating rate in the range of 400°C-1200°C to 8-12°C / min, the heating rate in the range of 1200°C-1450°C to 4-6°C / min, keeping warm at 1450°C for 50-70min, then cooling naturally, closing the air pressure valve after the temperature drops to room temperature, and after sintering in the tube furnace, completely solidifying the dielectric insulating film and the tungsten thermoelectric film to form an insulating layer of the sensitive core and a tungsten outer conductor layer; S23. Take a tungsten wire with a diameter of 0.4-0.6 mm, put one end of the tungsten wire in close contact with the tungsten outer conductor layer of the sensitive core, and use high-temperature glue at a temperature of 180-220° C. to bond the tungsten wire and the tungsten outer conductor layer of the sensitive core into a stable conductive circuit.

8. The method for manufacturing a tungsten-rhenium coaxial thermocouple for measuring radiation heat flux according to claim 7, characterized in that: The packaging tube shell assembly step specifically includes: S31, using the high temperature adhesive as a dividing point, covering the tungsten wire and tungsten-rhenium wire parts under the high temperature adhesive with a heat shrink tube, and using a hot air gun to tightly wrap the heat shrink tube with the tungsten wire and tungsten-rhenium wire, wherein the shrinkage rate of the heat shrink tube is 50% to 70%; S32, inserting the sensitive core into a 304 stainless steel tube shell with a length of 0.08 to 0.12 m, filling an appropriate amount of the high temperature glue into the 304 stainless steel tube shell, heating the high temperature glue to expand when heated to fill the gap between the sensitive core and the stainless steel tube shell, and bonding the sensitive core and the stainless steel tube shell; S33. Use an electric grinder to grind the tungsten-rhenium inner conductor layer and the tungsten outer conductor layer at the top of the sensitive core. The tungsten particles and the tungsten-rhenium particles generated by grinding are bridged with each other to form a temperature measuring node of the tungsten-rhenium coaxial thermocouple, and a high-emissivity coating with a thickness of 5 to 15 μm is coated on the temperature measuring node to improve the absorption efficiency of the radiation heat flow.

9. A method for batch coaxial manufacturing of tungsten-rhenium coaxial thermocouples for radiation heat flux measurement, characterized in that: The method for manufacturing a tungsten-rhenium coaxial thermocouple for measuring radiation heat flux according to any one of claims 1 to 8 further comprises: The prepared sensitive core is cut into multiple sections to achieve batch preparation.

10. A batch coaxially manufactured tungsten-rhenium coaxial thermocouple for measuring radiation heat flux, characterized in that: include: The method for batch coaxial manufacturing of tungsten-rhenium coaxial thermocouples for measuring radiation heat flux as claimed in claim 9 is characterized by comprising: The sensitive core is composed of a three-layer coaxial structure with an inner tungsten-rhenium wire, a middle dielectric insulating film and an outer tungsten thermoelectric film, wherein the inner tungsten-rhenium wire has a diameter of 0.5 mm, the dielectric insulating film has a thickness of 20 to 30 μm, and the tungsten thermoelectric film has a thickness of 20 to 30 μm; The protective tube shell is made of 304 stainless steel, has a length of 0.08 to 0.12 m, and its inner diameter is adapted to the sensitive core body, and is used to accommodate and protect the sensitive core body. The protective tube shell and the sensitive core body are filled with high-temperature glue, and the filling rate of the high-temperature glue is greater than 80%; A temperature measuring node, the temperature measuring node is located at the top of the sensitive core, the surface roughness of the temperature measuring node is less than 0.5 μm, and a high emissivity coating with a thickness of 5 to 15 μm is coated on the temperature measuring node, and the emissivity of the coating is greater than 0.9; The connecting wire comprises a tungsten wire connected to the tungsten outer conductor layer of the sensitive core and a homogeneous tungsten-rhenium wire connected to the inner tungsten-rhenium wire, wherein the diameter of the tungsten wire is 0.4-0.6 mm, the tungsten wire and the tungsten-rhenium wire are firmly bonded at the connection part with the sensitive core by the high-temperature adhesive, and heat shrink tubes are respectively provided at the non-connection parts for insulation protection, and the shrinkage rate of the heat shrink tubes is 50%-70%.

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