Insulated thermionic subassembly and method of making same, magnetron cathode

Abstract

The application discloses an insulating hot subassembly and a preparation method thereof and a magnetron cathode. The insulating hot subassembly comprises a hot sub and an insulating cylinder. The hot sub comprises a spiral hot sub body wound by metal wires. The insulating cylinder is in a cylindrical shape with a hollow interior and open ends. The insulating cylinder is provided with an internal thread groove along the inner wall, which is matched with the hot sub body. The hot sub body is screwed into the internal thread groove of the insulating cylinder and forms mechanical self-locking. The application adopts a split structure of screwing the hot sub and the insulating cylinder, completely solves the problem of easy cracking and peeling of the traditional insulating coating, eliminates the high-temperature damage in the hot sub preparation process, has the advantages of reliable insulation, excellent heat conduction, long service life, convenient assembly, single replacement of the hot sub, high assembly yield and the like, and can significantly improve the working stability when applied to the magnetron cathode.

Description

Technical Field

[0001] This invention relates to the field of magnetron technology, and in particular to an insulated thermal component and its preparation method, and a magnetron cathode. Background Technology

[0002] A magnetron is a vacuum electronic device that generates microwave energy and is widely used in microwave ovens, radar, medical equipment, and industrial heating. The cathode thermoelectric assembly is one of the core components of the magnetron; its function is to generate heat when energized, heating the cathode to its electron emission temperature. The magnetron cathode operates in a high-temperature vacuum environment and must withstand high-frequency pulse vibrations; therefore, the thermoelectric insulation layer requires high thermal shock resistance, insulation reliability, and service life.

[0003] In existing technologies, the heat source is typically made of tungsten or molybdenum wire wound into a spiral structure. To prevent short circuits between the heat source and the cathode cylinder, the surface of the heat source needs to be coated with an alumina insulating layer. Currently, the insulating layer is mainly prepared using electrophoresis or spraying processes, which involves attaching insulating material powder to the surface of the heat source through electrophoresis or spraying, and then sintering and curing it at high temperature to form a continuous insulating coating.

[0004] However, the aforementioned existing technologies still have the following objective shortcomings: First, the bonding force between the insulating coating formed by electrophoresis or spraying processes and the magnetron substrate is limited. Under the repeated thermal shocks generated by the frequent start-stop of the magnetron and the high-frequency vibration during operation, the insulating coating is prone to cracking and peeling, leading to insulation failure and affecting the normal operation of the magnetron. Second, the preparation process of the insulating coating requires high-temperature sintering treatment. The high-temperature environment will cause thermal damage to the magnetron wire and introduce residual stress, reducing the mechanical strength and toughness of the magnetron and shortening its service life. Third, the magnetron and the insulating coating need to be prepared and inspected simultaneously, and it is impossible to conduct separate quality inspections on both, making it difficult to improve the final yield of the component.

[0005] Therefore, how to ensure reliable insulation between the heat source and the cathode cylinder while avoiding cracking and peeling of the insulation layer, eliminating thermal damage to the heat source during the insulation layer preparation process, and achieving independent quality control of the heat source and the insulation layer are technical problems that urgently need to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to solve the above-mentioned problems existing in the prior art and to provide an insulated thermal component and its preparation method, as well as a magnetron cathode, so as to overcome the defects of easy cracking and peeling of the insulation layer, easy damage of the thermal component to high temperature and low component yield in the prior art.

[0007] The technical solution adopted by the present invention to solve its technical problem is: an insulating heat element assembly, including a heat element and an insulating cylinder. The heat element includes a spiral heat element body made of metal wire. The insulating cylinder is a cylindrical shape with a hollow interior and open ends. The insulating cylinder has an internal thread groove along its inner wall that matches the heat element body. The heat element body is screwed into the internal thread groove of the insulating cylinder and forms a mechanical self-locking mechanism.

[0008] As a further improvement of the present invention, the insulating cylinder is made of aluminum nitride.

[0009] As a further improvement of the present invention, the pitch of the internal thread groove is equal to the winding pitch of the heat source body, and the cross-sectional profile of the internal thread groove is adapted to the outer surface profile of the metal wire constituting the heat source body, so that each turn of the metal wire of the heat source body can be tightly embedded in the corresponding internal thread groove.

[0010] As a further improvement of the present invention, the two ends of the internal thread groove extend to the two end faces of the insulating cylinder, and the axial length of the internal thread groove is not less than the axial length of the heat source body, so that the heat source body can be completely accommodated in the insulating cylinder.

[0011] As a further improvement of the present invention, the heat source further includes a first lead-out rod and a second lead-out rod respectively connected to both ends of the heat source body. The first lead-out rod and the second lead-out rod are both integrally formed by the metal wire constituting the heat source body. The metal wires at both ends of the heat source body are first bent radially inward, and then extended axially in a direction opposite to each other to form the first lead-out rod and the second lead-out rod respectively. The first lead-out rod and the second lead-out rod extend axially from both end faces of the insulating cylinder.

[0012] As a further improvement of the present invention, the metal wire is a tungsten wire or a molybdenum wire.

[0013] This invention also provides a method for preparing an insulating thermal component, which includes the following steps: S1. Prepare insulating cylinder; Aluminum nitride powder is loaded into an insulating cylinder forming mold and sintered at high temperature. After demolding, an insulating cylinder with an internal thread groove on the inner wall is obtained. S2. Assemble the insulated thermal module; A heat element integrally wound with metal wire is provided. The heat element body is screwed into the internal thread groove from one end of the insulating cylinder until the heat element body is completely contained in the insulating cylinder, thus obtaining an insulating heat element assembly.

[0014] As a further improvement of the present invention, step S1 specifically includes the following steps: S11. Take aluminum nitride micro powder with a purity ≥99.5% and a median particle size D50 between 0.8μm and 2.0μm, add yttrium oxide as a sintering aid, and ball mill and mix with anhydrous ethanol as the ball milling medium for 16h~30h. After drying, sieve to obtain aluminum nitride powder. S12. The aluminum nitride powder obtained in S11 is loaded into the insulating cylinder forming mold and isostatically compacted under a pressure of 200MPa~250MPa for 1min~3min to obtain the insulating cylinder blank. S13. Place the insulating cylinder blank together with the insulating cylinder forming mold into a protective atmosphere furnace and sinter at 1700℃~1800℃ for 2h~3h; S14. After sintering, cool to room temperature, remove and demold to obtain an insulating cylinder with internal threaded grooves on the inner wall.

[0015] As a further improvement of the present invention, the insulating cylinder forming mold includes: Mold cylinder; A threaded mandrel has external thread teeth on its outer circumferential surface that are similar in shape to the internal thread groove. The threaded mandrel is coaxially disposed inside the mold cylinder and forms a cavity between the two for forming the insulating cylinder. The positioning base has an inner positioning frustum and an outer positioning ring coaxially arranged on its top. The mold cylinder and the threaded mandrel are both installed on the positioning base in a vertical direction. The mold cylinder is embedded in the inner side of the outer positioning ring, and the threaded mandrel is fitted on the inner positioning frustum.

[0016] The present invention also provides a magnetron cathode, comprising: a cathode cylinder, a cathode emitter disposed on the outer circumferential surface of the cathode cylinder, a thermoelectric ceramic tube, a cover plate, and an insulating thermoelectric assembly as described above. The cathode cylinder is a hollow cylindrical structure with one end closed and the other end open. The insulating thermoelectric assembly is installed inside the cathode cylinder. One end of the insulating cylinder abuts against the inner wall of the closed end of the cathode cylinder. The thermoelectric body and the inner wall of the cathode cylinder are completely insulated and isolated by the insulating cylinder. The thermoelectric ceramic tube is installed inside the open end of the cathode cylinder and pressed against the other end of the insulating cylinder. The cover plate is fixedly placed inside the open end of the cathode cylinder and presses against the thermoelectric ceramic tube. The first lead-out rod of the thermoelectric element passes through the thermoelectric ceramic tube and the cover plate and extends outward. The second lead-out rod of the thermoelectric element passes through the closed end of the cathode cylinder and extends outward.

[0017] The beneficial effects of this invention are: 1. This invention provides an insulated thermal component and its preparation method, and a magnetron cathode. The thermal component body is screwed into the internal thread groove of the insulating cylinder to form a mechanically self-locking split structure, which can withstand repeated thermal shocks generated by the start and stop of the magnetron and high-frequency vibrations during operation, ensuring long-term stable and reliable insulation performance, without cracking or peeling, and significantly extending the service life of the insulated thermal component. 2. After the heat source expands due to heat, it comes into close physical contact with the inner wall of the internal thread groove of the insulating cylinder, which greatly reduces the interfacial thermal resistance, has high heat transfer efficiency and uniform heat conduction, avoids heat accumulation inside the heat source, effectively protects the heat source and improves the thermal response speed. 3. In this invention, the heat element and the insulating cylinder are independent components. Therefore, the heat element does not need to undergo a high-temperature coating and sintering process during manufacturing, completely eliminating the thermal damage and stress effects of the high-temperature environment on the heat element, and preserving the original mechanical strength and toughness of the heat element. Both can be manufactured and quality inspected independently, and then assembled after passing the inspection, which greatly improves the final yield of the insulating heat element assembly. At the same time, the threaded assembly method is simple and convenient to operate, with high assembly efficiency and a firm connection. If the heat element burns out and is damaged, it can be simply unscrewed from the insulating cylinder and replaced with a new heat element. The insulating cylinder can be reused, making maintenance simple and cost-effective. 4. The insulating cylinder is made of aluminum nitride, which has excellent high thermal conductivity. It can quickly and evenly conduct the heat generated by the thermoelectric element to the insulating cylinder, thereby heating the cathode. This effectively avoids problems such as excessive heat temperature and shortened lifespan caused by heat accumulation inside the thermoelectric element. At the same time, it improves the thermal response speed, enabling the cathode to quickly reach the electron emission temperature. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a perspective view of the insulating thermoelectric assembly of the present invention; Figure 2 This is a cross-sectional view of the insulating thermoelectric assembly of the present invention; Figure 3 This is an exploded view of the insulator thermoelectric assembly of the present invention; Figure 4 This is a flowchart illustrating the steps of the method for preparing the insulating thermoelectric component of the present invention. Figure 5 This is a flowchart illustrating the steps involved in preparing the insulating cylinder in the method for preparing the insulating thermoelectric component of the present invention. Figure 6This is a perspective view of the insulating cylinder forming mold in Embodiment 2 of the present invention; Figure 7 This is a cross-sectional view of the insulating cylinder forming mold in Embodiment 2 of the present invention; Figure 8 This is a perspective view of the magnetron cathode of the present invention; Figure 9 This is a cross-sectional view of the magnetron cathode of the present invention.

[0020] Referring to the accompanying drawings, the following explanations are provided: 1. Heater; 101. Heater body; 102. First lead-out rod; 103. Second lead-out rod; 2. Insulating cylinder; 201. Internal threaded groove; 3. Mold cylinder; 4. Threaded mandrel; 401. External thread; 5. Cavity; 6. Positioning base; 601. Inner positioning frustum; 602. Outer positioning ring; 7. Cathode cylinder; 8. Cathode emitter; 9. Heater ceramic tube; 10. Cover plate. Detailed Implementation

[0021] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0023] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The illustrations only show the components related to this application and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the shape, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0024] Additionally, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that practice can be carried out without these specific details.

[0025] The technical solutions provided by the various embodiments of this application are described below with reference to the accompanying drawings.

[0026] Example 1

[0027] See Figures 1 to 3 The present invention provides an insulated heat element assembly, comprising: a heat element 1 and an insulating cylinder 2. The heat element 1 includes a spiral heat element body 101 made of metal wire. The insulating cylinder 2 is a cylindrical shape with a hollow interior and open ends. The insulating cylinder 2 has an internal thread groove 201 along its inner wall that matches the heat element body 101. The heat element body 101 is screwed into the internal thread groove 201 of the insulating cylinder 2 and forms a mechanical self-locking mechanism.

[0028] The present invention completely abandons the existing process of coating the surface of the heat element with an insulating coating. Instead, it adopts a split structure in which the heat element body 101 is screwed into the internal thread groove 201 of the insulating cylinder 2 to form a mechanically self-locking structure. This completely avoids the problem of interface stress concentration caused by the mismatch of thermal expansion coefficients. This threaded structure can absorb the thermal stress caused by the mismatch of thermal expansion coefficients through slight elastic deformation, so as to withstand the repeated thermal shocks generated by the start and stop of the magnetron and the high-frequency vibration during the operation, ensuring long-term stable and reliable insulation performance, without cracking or peeling, and significantly extending the service life of the insulating heat element assembly.

[0029] During operation, the heat source body 101 expands under heat and comes into close physical contact with the inner wall of the internal thread groove 201 of the insulating cylinder 2, which greatly reduces the interfacial thermal resistance, has high heat transfer efficiency and uniform heat conduction, avoids heat accumulation inside the heat source 1, effectively protects the heat source and improves the thermal response speed.

[0030] Furthermore, since the heat element 1 and the insulating cylinder 2 are independent components, the heat element 1 does not require a high-temperature coating and sintering process during manufacturing, completely eliminating the thermal damage and stress effects of the high-temperature environment on the heat element 1, and preserving its original mechanical strength and toughness. Both can be manufactured and quality inspected independently, and only assembled after passing inspection, significantly improving the final yield of the insulated heat element assembly. At the same time, the threaded assembly method is simple and convenient to operate, with high assembly efficiency and a secure connection. If the heat element 1 burns out, it can simply be unscrewed from the insulating cylinder 2 and replaced with a new one. The insulating cylinder 2 is reusable, making maintenance simple and cost-effective.

[0031] In this invention, the heat source body 101 is continuously wound from metal wire with constant winding parameters. The inner diameter, outer diameter, and pitch of each turn of the spiral are completely consistent, forming a continuous spiral structure with equal diameter and equal pitch. This structure ensures a high-precision full-circumference fit between the heat source body 101 and the internal thread groove 201 on the inner wall of the insulating cylinder 2. This allows each turn of the metal wire in the heat source body 101 to be uniformly and tightly embedded in the corresponding internal thread groove 201, resulting in a large contact area and uniform stress. This facilitates the rapid conduction of heat generated by the heat source 1 to the insulating cylinder 2 through the contact interface, thereby uniformly heating the cathode. It also effectively avoids problems such as assembly jamming and local stress concentration caused by uneven dimensions of each turn of the heat source. At the same time, it ensures that the heating power of each part of the heat source body 101 is consistent, achieving uniform heating of the cathode and improving the stability of cathode electron emission.

[0032] The insulating layer in the existing technology is usually made of alumina material, which has low thermal conductivity. Heat tends to accumulate on the surface of the heat source, resulting in excessively high local temperature, slow thermal response, and shortened service life.

[0033] Optionally, the metal wire wound into the heat source 1 can be made of tungsten wire or molybdenum wire. Tungsten wire and molybdenum wire have extremely high melting points and excellent high-temperature mechanical properties, which can work stably for a long time in the high-temperature working environment of the magnetron cathode and are not easily deformed or melted. At the same time, they have good electrical conductivity and high heating efficiency, which can heat the cathode to the required electron emission temperature with lower power and reduce the energy consumption of the magnetron.

[0034] In existing technologies, alumina is commonly used to prepare the insulating layer of the thermoelectric generator. However, alumina has a low thermal conductivity, making it difficult for the heat generated during operation to be quickly conducted outwards. This results in a large amount of heat accumulating inside the thermoelectric generator, causing excessively high operating temperatures, significantly shortening its lifespan, and slowing down the thermal response, thus prolonging the time required for the cathode to reach electron emission temperature. Although beryllium oxide has a high thermal conductivity, which can solve the above-mentioned heat accumulation problem, beryllium oxide powder is highly toxic. Its production, coating, and subsequent waste disposal all pose a serious threat to the health of operators and the natural environment. Therefore, its application in industrial production is subject to increasingly stringent restrictions.

[0035] Therefore, in this invention, the insulating cylinder 2 is made of aluminum nitride. Aluminum nitride has excellent thermal conductivity, which is higher than that of aluminum oxide. It can quickly and evenly conduct the heat generated by the heat source 1 to the insulating cylinder 2, thereby heating the cathode. This effectively avoids problems such as excessive heat accumulation inside the heat source 1, leading to excessively high temperature and shortened lifespan of the heat source 1. At the same time, it improves the thermal response speed, enabling the cathode to quickly reach the electron emission temperature. In addition, aluminum nitride is a non-toxic and environmentally friendly material. Its production, use, and waste disposal will not cause harm to human health or the environment. It replaces the highly toxic beryllium oxide material, meeting the requirements of green production.

[0036] Preferably, the two ends of the internal threaded groove 201 extend to the end faces of both ends of the insulating cylinder 2, so that the heat source body 101 can be screwed into the insulating cylinder 2 from either end, making assembly more flexible and convenient, improving production efficiency, and also facilitating the forming and demolding of the insulating cylinder 2, reducing the manufacturing difficulty of the insulating cylinder 2. In addition, the axial length of the internal threaded groove 201 (or the length of the insulating cylinder 2) is not less than the axial length of the heat source body 101, so that the heat source body 101 can be completely accommodated inside the insulating cylinder 2, avoiding the risk of short circuit between the heat source body 101 exposed to the outside and the cathode, and ensuring the reliability of insulation.

[0037] See Figure 2 and Figure 3 The pitch of the internal thread groove 201 is equal to the winding pitch of the heat source body 101, and the cross-sectional profile (semi-circular) of the internal thread groove 201 is adapted to the outer surface profile of the metal wire constituting the heat source body 101, so that each turn of the metal wire of the heat source body 101 can be uniformly and tightly embedded in the corresponding internal thread groove 201, which increases the contact area between the heat source 1 and the insulating cylinder 2, reduces the contact thermal resistance, and further improves the heat conduction efficiency; at the same time, the uniform contact also makes the force on each part of the heat source 1 consistent, avoiding the problem of metal wire breakage caused by local stress concentration.

[0038] Furthermore, the thermoelectric element 1 also includes a first lead-out rod 102 and a second lead-out rod 103 respectively connected to both ends of the thermoelectric element body 101. The first lead-out rod 102 and the second lead-out rod 103 are both integrally formed by the metal wire constituting the thermoelectric element body 101. The metal wires at both ends of the thermoelectric element body 101 are first bent radially inward, and then extended axially in opposite directions to form the first lead-out rod 102 and the second lead-out rod 103 respectively. The first lead-out rod 102 and the second lead-out rod 103 extend axially from the end faces of both ends of the insulating cylinder 2, so that the first lead-out rod 102 and the second lead-out rod 103 can pass through the cathode and connect to the external circuit.

[0039] Example 2

[0040] See Figures 1 to 7 The present invention also provides a method for preparing an insulating thermal component, which is used to prepare an insulating thermal component as described in Example 1, comprising the following steps: S1. Prepare insulating cylinder 2; Aluminum nitride powder is loaded into an insulating cylinder forming mold and sintered at high temperature. After demolding, an insulating cylinder 2 with an internal thread groove 201 on the inner wall is obtained. S2. Assemble the insulated thermal module; A heat element 1 is provided, which is integrally wound with metal wire. The heat element body 101 of the heat element 1 is screwed from one end of the insulating cylinder 2 into the internal thread groove 201 until the heat element body 101 is completely contained in the insulating cylinder 2, thus obtaining an insulating heat element assembly.

[0041] It should be noted that the hot element 1 is well known to those skilled in the art as being integrally wound with metal wire, and this invention does not improve the winding process of the hot element 1. The hot element 1 typically uses high-temperature resistant metal wires such as tungsten or molybdenum wires, which are continuously wound into a helical hot element body 101 using specialized winding equipment according to a preset pitch and diameter. The two ends are integrally bent to form a first lead-out rod 102 and a second lead-out rod 103 extending axially. Those skilled in the art can select any suitable diameter metal wire and adjust the corresponding winding parameters according to the power requirements and operating temperature of the magnetron; therefore, the specific winding process of the hot element 1 will not be described in detail here.

[0042] The method for preparing the insulating heat element assembly of this invention involves directly obtaining an insulating cylinder 2 with an internally threaded groove 201 on its inner wall by forming it using a dedicated insulating cylinder forming mold and high-temperature sintering. The heat element body 101 of the heat element 1 is then screwed into the insulating cylinder 2 to complete the assembly. This process is simple, highly efficient, and suitable for large-scale industrial production. This preparation method eliminates the need for coating and sintering the insulating coating on the surface of the heat element 1, fundamentally solving the industry problem of easy cracking and peeling of the insulating coating leading to insulation failure. It also avoids high-temperature damage to the heat element 1, ensuring its performance. Furthermore, the separate preparation of the heat element 1 and the insulating cylinder 2 facilitates individual quality control of each component, improving the product qualification rate.

[0043] See Figure 6 and Figure 7 The insulating cylinder forming mold includes a mold cylinder 3, a threaded mandrel 4, and a positioning base 6.

[0044] The mold cylinder 3 is a hollow cylinder with open ends. The threaded mandrel 4 is also a hollow cylinder with open ends, but its outer diameter is smaller than the inner diameter of the mold cylinder 3. The outer circumferential surface of the threaded mandrel 4 is provided with external thread teeth 401 that are similar in shape to the internal thread groove 201. The threaded mandrel 4 is coaxially disposed inside the mold cylinder 3, forming a cavity 5 between the two for molding the insulating cylinder 2.

[0045] Considering that shrinkage will occur during sintering, the inner diameter and height of the mold cylinder 3 need to be enlarged according to the finished size of the insulating cylinder 2. That is, the inner diameter (or height) of the mold cylinder 3 is equal to the outer diameter (or height) of the finished insulating cylinder 2 multiplied by (1 + sintering shrinkage rate) to compensate for the sintering shrinkage and ensure that the size of the insulating cylinder 2 after molding meets the design requirements.

[0046] Furthermore, the top of the positioning base 6 is coaxially provided with an inner positioning frustum 601 and an outer positioning ring 602. The outer diameter of the inner positioning frustum 601 is adapted to the inner diameter of the threaded mandrel 4, and the inner diameter of the outer positioning ring 602 is adapted to the outer diameter of the mold cylinder 3. Both the mold cylinder 3 and the threaded mandrel 4 are installed vertically on the positioning base 6, with the mold cylinder 3 embedded inside the outer positioning ring 602 and the threaded mandrel 4 fitted onto the inner positioning frustum 601. By coaxially setting the inner positioning frustum 601 and the outer positioning ring 602 on the positioning base 6, this invention can ensure the coaxiality of the threaded mandrel 4 and the mold cylinder 3, making the wall thickness of the molded insulating cylinder 2 uniform and avoiding the problems of inconsistent heat conduction and reduced strength caused by uneven wall thickness. At the same time, this mold structure is convenient to assemble and disassemble, easy to demold, and reduces manufacturing costs.

[0047] Preferably, the mold cylinder 3, the threaded mandrel 4, and the positioning base 6 are all made of high-temperature resistant and non-stick ceramic powder materials, such as graphite and silicon carbide.

[0048] Furthermore, step S1 of the present invention, preparing the insulating cylinder 2, specifically includes the following steps: S11. Take aluminum nitride micro powder with a purity ≥99.5% and a median particle size D50 between 0.8μm and 2.0μm, add yttrium oxide as a sintering aid, and ball mill and mix with anhydrous ethanol as the ball milling medium for 16h~30h (preferably 24h). After drying, sieve to obtain aluminum nitride powder and store it under vacuum. S12. The aluminum nitride powder obtained in S11 is loaded into the cavity 5 of the insulating cylinder forming mold, and isostatically compacted under a pressure of 200MPa~250MPa for 1min~3min to obtain the insulating cylinder blank. S13. Place the insulating cylinder blank together with the insulating cylinder forming mold into a protective atmosphere furnace and sinter at 1700℃~1800℃ for 2h~3h. S14. After sintering, cool to room temperature, remove and demold to obtain an insulating cylinder 2 with an internal threaded groove 201 on the inner wall.

[0049] Example 3

[0050] See Figure 8 and Figure 9 The present invention also provides a magnetron cathode, comprising: a cathode cylinder 7, a cathode emitter 8 disposed on the outer peripheral surface of the cathode cylinder 7, a thermal ceramic tube 9, a cover plate 10, and an insulating thermal assembly as described in Embodiment 1.

[0051] The cathode cylinder 7 is a cylindrical structure that is hollow inside, closed at the bottom, and open at the top. The insulated heat element assembly is installed axially inside the cathode cylinder 7. The lower end of the insulating cylinder 2 abuts against the inner wall of the closed end of the cathode cylinder 7. The outer wall of the insulating cylinder 2 is fitted with the inner wall of the cathode cylinder 7 with a small gap. The heat element body 101 and the inner wall of the cathode cylinder 7 are completely insulated and isolated from each other by the insulating cylinder 2.

[0052] During operation, the main body of the heat source 101 is energized and generates heat. The heat generated is rapidly conducted to the insulating cylinder 2 through the contact interface between each metal wire and the internal thread groove 201. A continuous and uniform radial heat conduction channel is formed inside the insulating cylinder 2, which rapidly conducts the heat to the cathode cylinder 7. Finally, the cathode emitter 8 on the outer circumference of the cathode cylinder 7 is uniformly heated, making the overall temperature distribution of the cathode emitter 8 uniform and consistent. This effectively improves the stability and consistency of cathode electron emission, significantly enhances the thermal response speed, and shortens the time for the cathode to reach the working temperature. At the same time, it avoids heat accumulation inside the heat source 1, effectively protecting the heat source.

[0053] Furthermore, the heat-generating ceramic tube 9 is installed inside the open end of the cathode cylinder 7 and pressed against the upper end of the insulating cylinder 2. The cover plate 10 is fixedly placed inside the open end of the cathode cylinder 7 and presses the heat-generating ceramic tube 9, thereby fixing the insulating heat-generating assembly and effectively preventing displacement of the insulating heat-generating assembly during operation. Both the heat-generating ceramic tube 9 and the cover plate 10 have through holes in their middle sections. The first lead-out rod 102 of the heat-generating element 1 passes through the through holes of the heat-generating ceramic tube 9 and the cover plate 10 and extends outwards, without contacting the cover plate 10. The second lead-out rod 103 of the heat-generating element 1 passes through the closed end of the cathode cylinder 7 and extends outwards, and is welded and fixed to the closed end of the cathode cylinder 7.

[0054] The magnetron cathode of this invention is coaxially mounted inside the cathode cylinder 7 using the insulating thermoelectric assembly described in Embodiment 1. One end of the insulating cylinder 2 abuts against the inner wall of the closed end of the cathode cylinder 7, while the other end is pressed and fixed by the thermoelectric ceramic tube 9 and the cover plate 10. The insulating cylinder 2 completely isolates the thermoelectric body 101 of the thermoelectric element 1 from the inner wall of the cathode cylinder 7, providing excellent insulation performance and preventing short-circuit faults. The first lead-out rod 102 and the second lead-out rod 103 of the thermoelectric element 1 extend from both ends of the cathode cylinder 7, facilitating connection to external circuits. This magnetron cathode has advantages such as reliable insulation, long service life, uniform heating, and stable electron emission, significantly improving the overall performance and reliability of the magnetron.

[0055] The same or similar parts between the various embodiments in this specification can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments.

[0056] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An insulated thermal assembly, comprising a thermal element (1), said thermal element (1) comprising a spiral thermal element body (101) formed of wound metal wire, characterized in that, The insulating heat source assembly also includes an insulating cylinder (2), which is a cylindrical shape with a hollow interior and open ends. The insulating cylinder (2) has an internal thread groove (201) along its inner wall that matches the heat source body (101). The heat source body (101) is screwed into the internal thread groove (201) of the insulating cylinder (2) and forms a mechanical self-locking mechanism.

2. The insulator assembly according to claim 1, characterized in that, The insulating cylinder (2) is made of aluminum nitride.

3. The insulated thermal assembly according to claim 1, characterized in that, The pitch of the internal thread groove (201) is equal to the winding pitch of the heat source body (101), and the cross-sectional profile of the internal thread groove (201) is adapted to the outer surface profile of the metal wire constituting the heat source body (101), so that each turn of the metal wire of the heat source body (101) can be tightly embedded in the corresponding internal thread groove (201).

4. The insulator assembly according to claim 1, characterized in that, The two ends of the internal thread groove (201) extend to the two end faces of the insulating cylinder (2), and the axial length of the internal thread groove (201) is not less than the axial length of the heat source body (101), so that the heat source body (101) can be completely accommodated in the insulating cylinder (2).

5. The insulated thermal assembly according to claim 1, characterized in that, The heat source (1) also includes a first lead-out rod (102) and a second lead-out rod (103) respectively connected to both ends of the heat source body (101). The first lead-out rod (102) and the second lead-out rod (103) are both integrally formed by the metal wire constituting the heat source body (101). The metal wires at both ends of the heat source body (101) are first bent radially inward, and then extended axially in the direction opposite to each other to form the first lead-out rod (102) and the second lead-out rod (103) respectively. The first lead-out rod (102) and the second lead-out rod (103) extend axially from both end faces of the insulating cylinder (2).

6. The insulated thermal assembly according to claim 1, characterized in that, The metal wire is a tungsten wire or a molybdenum wire.

7. A method for preparing an insulated thermal component, used to prepare the insulated thermal component as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Prepare the insulating cylinder (2); Aluminum nitride powder is loaded into an insulating cylinder forming mold and sintered at high temperature. After demolding, an insulating cylinder (2) with an internal thread groove (201) on the inner wall is obtained. S2. Assemble the insulated thermal module; A heat element (1) integrally wound with metal wire is provided. The heat element body (101) of the heat element (1) is screwed from one end of the insulating cylinder (2) into the internal thread groove (201) until the heat element body (101) is completely contained in the insulating cylinder (2) to obtain an insulating heat element assembly.

8. The method for preparing the insulator thermal module according to claim 7, characterized in that, Step S1 specifically includes the following steps: S11. Take aluminum nitride micro powder with a purity ≥99.5% and a median particle size D50 between 0.8μm and 2.0μm, add yttrium oxide as a sintering aid, and ball mill and mix with anhydrous ethanol as the ball milling medium for 16h~30h. After drying, sieve to obtain aluminum nitride powder. S12. The aluminum nitride powder obtained in S11 is loaded into the insulating cylinder forming mold and isostatically compacted under a pressure of 200MPa~250MPa for 1min~3min to obtain the insulating cylinder blank. S13. Place the insulating cylinder blank together with the insulating cylinder forming mold into a protective atmosphere furnace and sinter at 1700℃~1800℃ for 2h~3h; S14. After sintering, cool to room temperature, remove and demold to obtain an insulating cylinder (2) with an internal thread groove (201) on the inner wall.

9. The method for preparing the insulator thermal module according to claim 7, characterized in that, The insulating cylinder forming mold includes: Mold cylinder (3); The threaded mandrel (4) has an external thread tooth (401) on its outer circumferential surface that is similar in shape to the internal thread groove (201). The threaded mandrel (4) is coaxially disposed inside the mold cylinder (3) and forms a cavity (5) between the two for forming the insulating cylinder (2). The positioning base (6) has an inner positioning frustum (601) and an outer positioning ring (602) coaxially arranged on its top. The mold cylinder (3) and the threaded mandrel (4) are both installed on the positioning base (6) in the vertical direction. The mold cylinder (3) is embedded in the inner side of the outer positioning ring (602), and the threaded mandrel (4) is fitted on the inner positioning frustum (601).

10. A magnetron cathode, characterized in that, The device includes a cathode cylinder (7), a cathode emitter (8) disposed on the outer circumferential surface of the cathode cylinder (7), a thermal ceramic tube (9), a cover plate (10), and an insulating thermal assembly as described in any one of claims 1 to 6. The cathode cylinder (7) is a hollow cylindrical structure with one end closed and the other end open. The insulating thermal assembly is installed inside the cathode cylinder (7). One end of the insulating cylinder (2) abuts against the inner wall of the closed end of the cathode cylinder (7). The thermal body (101) and the inner wall of the cathode cylinder (7) are separated. The insulating cylinder (2) provides complete insulation and isolation; the heat source ceramic tube (9) is installed inside the open end of the cathode cylinder (7) and pressed against the other end of the insulating cylinder (2); the cover plate (10) is fixedly placed inside the open end of the cathode cylinder (7) and presses against the heat source ceramic tube (9); the first lead-out rod (102) of the heat source (1) passes through the heat source ceramic tube (9) and the cover plate (10) and leads outward; the second lead-out rod (103) of the heat source (1) passes through the closed end of the cathode cylinder (7) and leads outward.

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