Rapid heating ultra-large type hot isostatic pressing equipment for powder metallurgy

Abstract

The invention relates to the technical field of hot isostatic pressing equipment, and provides rapid heating ultra-large type hot isostatic pressing equipment for powder metallurgy. The hot isostatic pressing equipment comprises a cylindrical high-pressure container, and a hollow interlayer is formed between the inner wall and the outer wall of the high-pressure container; the loading frame is arranged in the high-pressure container and is used for bearing powder metallurgy furnace charge; the composite heating coil is arranged in the hollow interlayer and comprises an outer-layer high-frequency coil which is spirally wound along the axial direction of the high-pressure container; and the middle-layer intermediate-frequency coils are crosswise arranged along the axial direction and the circumferential direction of the high-pressure container. Powder metallurgy is an advanced manufacturing technology for manufacturing parts through preparation, forming and sintering of metal powder, hot isostatic pressing equipment is a machine used for pressurizing and heating in the process, and the heating efficiency of powder metallurgy is improved through the accelerated heating ultra-large type hot isostatic pressing equipment.

Description

Technical Field

[0001] The present application relates to the technical field of hot isostatic pressing equipment, and more specifically, to a rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy. Background Art

[0002] Powder metallurgy is an advanced manufacturing technology for manufacturing materials or parts through the preparation, forming, and sintering of metal powders. Its core lies in achieving near-net shaping of complex-shaped, high-performance materials through fine control of powders and process optimization.

[0003] Hot Isostatic Pressing (HIP) equipment is an advanced metal powder material processing equipment that processes metal powder materials under high temperature and high pressure conditions to achieve densification of materials, elimination of internal defects, and improvement of their mechanical properties. Hot isostatic pressing uses an inert gas (such as argon) as a medium to perform isostatic pressing on workpieces under high temperature and high pressure. Specifically: The metal powder is heated to a specific temperature by a heating system, causing the metal powder material to soften or melt, which is conducive to the closure of internal pores and material flow. By filling a high-pressure inert gas into a sealed container, the metal powder is subjected to uniform pressure in all directions, prompting the closure of pores inside the metal powder material and achieving a densification effect.

[0004] The internal cavity diameter of ultra-large hot isostatic pressing equipment is usually 2 meters or larger. In addition to the diameter, the height or length of the equipment may need to exceed 3 meters, and even reach 5 meters or more. It can raise the temperature of the internal cavity to the process requirement level within a short time, usually ranging from 1000°C to 2000°C. Despite the large size of the equipment, it still needs to maintain a high working pressure, generally between 100 MPa and 200 MPa, to ensure that the material can be fully densified. Ultra-large hot isostatic pressing equipment mainly consists of several parts such as a high-pressure container, a heating system, a gas supply, and a vacuum pumping device. Among them, the heating system is used to quickly raise the temperature inside the high-pressure container to the process requirement level within a short time. Common ones include resistance heaters, induction heaters, and microwave heaters, etc.

[0005] Currently, the hot isostatic pressing equipment using induction heaters lacks both heating speed and uniformity. Summary of the Invention

[0006] The purpose of the present application is to propose a rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy to solve the technical problems that the existing hot isostatic pressing equipment lacks both heating speed and uniformity.

[0007] To achieve the above purpose, the technical solution adopted by the present application is: to provide a rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy, including A cylindrical high-pressure vessel with a hollow interlayer formed between its inner wall and outer wall; A loading rack disposed inside the high-pressure vessel for carrying powder metallurgy furnace charge; A composite heating coil disposed inside the hollow interlayer, including: An outer high-frequency coil helically wound along the axial direction of the high-pressure vessel; A middle-frequency coil helically wound along the axial and circumferential directions of the high-pressure vessel; An inner power-frequency coil evenly arranged along the circumferential direction of the high-pressure vessel.

[0008] Further, the working frequency of the outer high-frequency coil is 20 kHz ± 2 kHz, and it is helically wound with a copper tube having a rectangular cross-section; The working frequency of the middle-frequency coil is 10 kHz ± 1 kHz, and it is arranged with a cross angle using silver-coated copper wire; The working frequency of the inner power-frequency coil is 50 Hz ± 5 Hz, and it is wound with a circumferentially evenly distributed copper bar winding.

[0009] Further, it further includes a controller, and the outer high-frequency coil, middle-frequency coil, and inner power-frequency coil are independently controlled by the controller.

[0010] Further, it further includes: Multiple groups of infrared temperature sensors distributed along the axial direction of the high-pressure vessel; Multiple groups of magnetic flux detectors distributed along the circumferential direction of the high-pressure vessel; The infrared temperature sensors and the magnetic flux detectors are connected to the controller, and the controller includes a dynamic power adjustment module for adjusting the current phase difference of the outer high-frequency coil, middle-frequency coil, and inner power-frequency coil according to real-time detection data.

[0011] In some embodiments, the hollow interlayer of the high-pressure vessel is filled with a silicon nitride ceramic honeycomb structure, and the outer high-frequency coil, middle-frequency coil, and inner power-frequency coil are embedded in the silicon nitride ceramic honeycomb structure.

[0012] Further, the distance between the silicon nitride ceramic honeycomb structure and the outer high-frequency coil, middle-frequency coil, and inner power-frequency coil is 0.1 - 0.3 mm.

[0013] In some embodiments, the lattice axis of the silicon nitride ceramic honeycomb structure is arranged at an angle of 30° - 60° with the axis of the high-pressure vessel.

[0014] Further, a graphite buffer layer is provided between the silicon nitride ceramic honeycomb structure and the inner wall of the high-pressure vessel.

[0015] In some embodiments, the loading rack is a graphene-coated silicon carbide grid structure, and boron nitride heat-conducting sheets are integrated on the grid surface of the loading rack.

[0016] In some embodiments, an insulating layer is provided inside the high-pressure vessel. The insulating layer is made of a highly efficient insulating material, including ceramic fiber or alumina foam.

[0017] The beneficial effects of the rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy provided by this application are at least as follows: By setting the outer high-frequency coil, the surface layer can be rapidly heated, the axial uniformity can be improved, the surface layer heating time can be shortened, the middle-frequency coil in the middle layer is arranged in a cross pattern axially and circumferentially, which can inhibit the axial temperature gradient and reduce the axial temperature difference, and the inner power-frequency coil is arranged circumferentially uniformly to eliminate the core and circumferential temperature difference of multi-layer materials. Through the collaborative design of the three-layer coils of axial spiral + cross + circumferential, the axial and circumferential temperature uniformity is improved in the ultra-large hot isostatic pressing equipment, and the multi-layer coils greatly improve the heating efficiency of the powder metallurgy in the loading rack. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of this application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the following drawings are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0019] Figure 1 It is a schematic external structure diagram of the rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy provided by the embodiment of this application; Figure 2 It is a schematic internal structure diagram of the rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy provided by the embodiment of this application; Figure 3 For Figure 2 the structural schematic diagram after setting the silicon nitride ceramic honeycomb structure in Figure 4 It is a schematic structure diagram of the outer high-frequency coil provided by the embodiment of this application arranged on the high-pressure vessel; Figure 5 It is a schematic structure diagram of the middle-frequency coil in the middle layer provided by the embodiment of this application arranged on the high-pressure vessel; Figure 6 It is a schematic structure diagram of the inner power-frequency coil provided by the embodiment of this application arranged on the high-pressure vessel; Figure 7 It is a schematic structure diagram of the infrared temperature sensor and the magnetic flux detector provided by the embodiment of this application arranged on the high-pressure vessel; Figure 8Schematic diagram of the circuit connection of the controller provided by the embodiment of the present application.

[0020] Among them, each reference numeral in the figure 1. High-pressure vessel; 11. Hollow interlayer; 12. Outer high-frequency coil; 13. Middle-frequency intermediate coil; 14. Inner power-frequency coil; 15. Infrared temperature sensor; 16. Magnetic flux detector; 17. Controller; 171. Dynamic power regulation module 18. Silicon nitride ceramic honeycomb structure; 181. Graphite buffer layer; 2. Loading rack; 21. Boron nitride heat-conducting sheet; 3. Heat insulation layer. Detailed implementation manners

[0021] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0022] It should be noted that when a component is referred to as "fixed to" or "disposed on" another component, it can be directly or indirectly located on the other component. When a component is referred to as "connected to" another component, it can be directly or indirectly connected to the other component. The orientations or positions indicated by the terms "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientations or positions shown in the drawings, and are only for the convenience of description and cannot be construed as limiting the technical solution of the present application. The terms "first" and "second" are only used for the purpose of convenient description and cannot be construed as indicating or implying relative importance or implicitly indicating the quantity of technical features. The meaning of "a plurality" is two or more unless otherwise specifically defined.

[0023] Currently, in the hot isostatic pressing equipment using induction heaters, the high-pressure container is set to be cylindrical, and an induction coil is arranged outside the cylindrical high-pressure container. A single wire is wound around the outside of the high-pressure container in a spiral form, and the spiral coil is also correspondingly formed into a cylindrical shape. However, since the cylindrical spiral coil mainly generates a magnetic field in one plane, it is only applicable to cylindrical or long-strip high-pressure containers. Moreover, the magnetic field of the cylindrical spiral coil is mainly concentrated in the winding area. Therefore, the heating in this area is relatively uniform, but temperature gradients may occur in the areas far from the coil. Taking the cylindrical high-pressure container as an example, the heating speed in the middle of the cylindrical high-pressure container is faster, while the heating speeds at the bottom and top are relatively slower, resulting in temperature gradients, making the existing hot isostatic pressing equipment lacking in both heating speed and uniformity.

[0024] The following describes the rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy according to the embodiments of the present application with reference to the accompanying drawings.

[0025] Please refer to Figure 1 , Figure 1 which shows the external structural schematic diagram of the rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy of the present application. Further, referring to Figures 1 - 3 , the rapid heating ultra-large hot isostatic pressing equipment includes a cylindrical high-pressure container 1 and a loading rack 2 arranged inside the high-pressure container 1. A hollow interlayer 11 is formed between the inner wall and the outer wall of the high-pressure container 1, and the loading rack 2 is used to carry the powder metallurgy furnace charge.

[0026] Continuing to refer to Figures 2 - 3 , a composite heating coil is arranged in the hollow interlayer 11. The composite heating coil includes an outer high-frequency coil 12, a middle-frequency coil 13 in the middle layer, and an inner power-frequency coil 14. The outer high-frequency coil 12 is spirally wound along the axial direction of the high-pressure container 1; the middle-frequency coil 13 in the middle layer is arranged in a cross pattern along the axial and circumferential directions of the high-pressure container 1; the inner power-frequency coil 14 is evenly arranged along the circumferential direction of the high-pressure container 1.

[0027] The working steps of the ultra-large hot isostatic pressing equipment after startup involve multiple links, including pretreatment, heating, pressurization, heat preservation, and cooling, etc. The following are the working steps after the equipment is started: Step 1: Place the metal powder workpiece to be processed into the high-pressure container 1 of the HIP equipment, and pay attention to the placement position to ensure uniform heating and pressure distribution.

[0028] Step 2: Start the equipment and enter the standby state to prepare for heating and pressurization operations.

[0029] Step 3: Set the initial heating power, frequency, and target temperature in the controller 17 according to the metal powder material and process requirements; start the outer high-frequency coil 12, the middle-frequency coil 13, and the inner power-frequency coil 14 in sequence to start heating the workpiece. The alternating magnetic field generated by the induction coil will generate eddy currents inside the workpiece, thereby achieving rapid heating.

[0030] Step 4: After reaching the predetermined temperature, gradually increase the pressure to perform isostatic pressing on the metal powder under high temperature and high pressure conditions.

[0031] Step 5: Maintain for a certain period of time under high temperature and high pressure conditions to fully improve the internal structure of the metal powder.

[0032] Step 6: After completing heat preservation, it is necessary to cool the metal powder to restore it to normal temperature and pressure.

[0033] Step 7: After completing cooling and pressure reduction, take out the formed workpiece made of metal powder and perform subsequent processing.

[0034] Through the provided outer high-frequency coil 12 in this application, the surface layer can be rapidly heated, the axial uniformity can be improved, and the surface layer heating time can be shortened. The middle-frequency coil 13 is arranged in a cross pattern axially and circumferentially, which can suppress the axial temperature gradient and reduce the axial temperature difference. The inner power-frequency coil 14 is arranged circumferentially uniformly to eliminate the temperature difference between the core and the circumference of the multi-layer material. Through the collaborative design of the three-layer coils of axial helix + cross + circumferential, the axial and circumferential temperature uniformity is improved in the ultra-large hot isostatic pressing equipment. The multi-layer coils greatly improve the heating efficiency of powder metallurgy in the loading rack 2.

[0035] Further, a hollow sandwich layer 11 with a width of 80 mm is formed between the inner wall and the outer wall of the cylindrical high-pressure vessel 1. The diameter of the high-pressure vessel 1 is 2.8 m, the height is 5.5 m, and the material is SA-723 Gr.3 steel.

[0036] The loading rack 2 is composed of a high-temperature-resistant alloy grid, is vertically installed on the inner central axis of the high-pressure vessel 1. The grid layer spacing of the loading rack 2 is 150 mm, and the maximum load per layer is 2.5 tons, which is used for stacking powder metallurgy furnace charges.

[0037] The outer high-frequency coil 12 uses a rectangular-sectioned copper pipe, refer to Figure 4 , and is helically wound along the axis of the high-pressure vessel 1 with a pitch of 5 mm, a working frequency of 20 kHz, and a penetration depth of 5 mm, which is used for rapid heating of the surface layer of the furnace charge.

[0038] The middle-frequency coil 13 uses a silver-clad copper wire with a circular cross-section, refer to Figure 5 , and is arranged axially and circumferentially on the high-pressure vessel 1 at a 45° crossing angle, with a working frequency of 10 kHz and a penetration depth of 12 mm, which is used to compensate the axial temperature gradient.

[0039] The inner layer power frequency coil 14 is made of flat copper bars, see Figure 6 , and is evenly arranged circumferentially along the high-pressure vessel 1, with a total of 8 independent windings; the working frequency is 50 Hz, and the penetration depth is ≥50 mm, which is used to eliminate the heat conduction bottleneck when multiple layers of materials are stacked.

[0040] Taking the sintering of Ti-6Al-4V titanium alloy powder with a diameter of 2.8 m as an example, the coil cooperative working mode is as follows: The outer layer high-frequency coil 12 is energized with an alternating current of 20 kHz, generating eddy currents within a depth of 5 mm on the surface of the charge, and heating up to 500 °C within 30 seconds. The spiral winding structure ensures uniform axial heat distribution.

[0041] The middle layer intermediate frequency coil 13 is energized with a current of 10 kHz to generate an intermediate frequency magnetic field, which penetrates to a depth of 12 mm, compensating for the temperature attenuation caused by the axial length of the container. The cross arrangement forms a mesh-like thermal field, making the axial temperature difference ≤±10 °C.

[0042] The inner layer power frequency coil 14 penetrates a depth of 50 mm through a 50 Hz low-frequency magnetic field, directly heating the core of the multi-layer stacked material. The 8 circumferentially evenly arranged windings generate a rotating magnetic field to eliminate the circumferential temperature difference.

[0043] Through recording, the heating effect is obtained: it takes 7 minutes and 30 seconds to heat up from 0 to 1200 °C, and the heating rate reaches an average of 160 °C / min. The maximum deviation of the axial temperature difference is 8.3 °C (±25 °C for the traditional single-coil structure); the maximum deviation of the circumferential temperature difference is 4.7 °C (±15 °C for the traditional structure).

[0044] It can be found that the heating speed has been increased, the axial temperature difference and the circumferential temperature difference have both been reduced, the heating speed is faster, and the heating uniformity is higher.

[0045] In some embodiments, the outer layer high-frequency coil 12 is made of a rectangular-sectioned copper tube with a cross-sectional size of 10 mm×5 mm and a wall thickness of 1 mm. The outer layer high-frequency coil 12 is spirally wound along the axis of the high-pressure vessel 1 with a pitch of 5 mm and a winding density of 200 turns per meter. The working frequency of the outer layer high-frequency coil 12 is 20 kHz±2 kHz, the current density is 50 A / mm², the skin depth is 5 mm, covering the surface layer of the charge with a depth of 0-5 mm.

[0046] The middle layer intermediate frequency coil 13 is made of silver-coated copper wire with a diameter of 8 mm and a silver layer thickness of 0.1 mm. The wires are alternately arranged along the axis and circumferentially at an intersection angle of 45°±5°, forming a rhombic grid structure. The working frequency of the middle layer intermediate frequency coil 13 is 10 kHz±1 kHz, the current density is 30 A / mm², the magnetic field penetration depth is 12 mm, covering the charge with a depth of 5-17 mm.

[0047] The inner layer power frequency coil 14 is made of flat copper bars with a cross-sectional size of 50mm×20mm, and is evenly arranged circumferentially along the high-pressure vessel 1; a total of 8 groups of independent windings are provided, with each group spaced 45°, and the copper bar spacing is 10mm. The operating frequency of the inner layer power frequency coil 14 is 50Hz±5Hz, the three-phase current phase difference is 120°±5°, the magnetic field penetration depth is ≥50mm, covering the core area of the charge.

[0048] Still taking the sintering of Ti-6Al-4V titanium alloy powder with a diameter of 2.5m as an example: The 20kHz high-frequency current of the outer layer high-frequency coil 12 generates a skin effect in the copper tube. The area of the charge surface layer from 0 to 5mm is heated to 480°C within 25 seconds. The spiral winding structure makes the axial heat distribution uniform, and the axial temperature difference ≤±8°C.

[0049] The 10kHz intermediate frequency magnetic field of the middle layer intermediate frequency coil 13 penetrates to a depth of 12mm, compensating for the temperature attenuation caused by the axial length of the container. The cross-arranged diamond grid eliminates the circumferential cold zone, and the circumferential temperature difference is reduced from ±18°C to ±6°C.

[0050] The 50Hz low-frequency magnetic field of the inner layer power frequency coil 14 directly heats the core of the charge, making the core heating rate reach 85°C / min. The 8 groups of windings evenly distributed circumferentially generate a rotating magnetic field, and the circumferential temperature difference of the core ≤±4°C.

[0051] Through recording, the heating effect is obtained: it takes 7 minutes and 15 seconds to heat from 0 to 1200°C, and the heating rate reaches an average of 165°C / min; the obtained density: 99.95% on the surface layer of the charge powder and 99.92% in the core (ASTM B962 standard).

[0052] In some embodiments, referring to Figure 1 and Figure 8 , the rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy further includes a controller 17. The outer layer high-frequency coil 12, the middle layer intermediate frequency coil 13, and the inner layer power frequency coil 14 are independently controlled by the controller 17.

[0053] Furthermore, referring to Figure 7 , the rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy further includes multiple groups of infrared temperature sensors 15 distributed axially along the high-pressure vessel 1; multiple groups of magnetic flux detectors 16 distributed circumferentially along the high-pressure vessel 1; the infrared temperature sensors 15 and the magnetic flux detectors 16 are connected to the controller 17, and the controller 17 includes a dynamic power adjustment module 171 for adjusting the current phase difference of the outer layer high-frequency coil 12, the middle layer intermediate frequency coil 13, and the inner layer power frequency coil 14 according to the real-time detection data.

[0054] Exemplarily, the controller 17 employs a multi-core industrial PLC, model SIEMENS S7-1500. The controller 17 is built-in with a dynamic power regulation module 171. The dynamic power regulation module 171 supports independent adjustment of the three-phase current phase difference, with an adjustment range of 0° to 180° and an adjustment accuracy of ±0.5°. The controller 17 also includes a data fusion unit with a processing frequency of 1 kHz for synchronously analyzing temperature and magnetic flux signals.

[0055] One group of infrared temperature sensors 15 is distributed axially along the high-pressure vessel 1 at intervals of 200 mm, with a total of 32 groups. A single group contains 4 temperature measurement points, including circumferential positions of 0°, 90°, 180°, and 270°. The temperature detection range is 20 to 1500 °C, with an accuracy of ±2 °C.

[0056] One group of magnetic flux detectors 16 is distributed circumferentially along the high-pressure vessel 1 every 30°, with a total of 12 groups. Using Hall effect sensors, the range of the magnetic flux detector 16 is 0 to 2 T, and the resolution is 1 mT.

[0057] The infrared temperature sensors 15 and the magnetic flux detectors 16 are connected to the controller 17 via a PROFIBUS bus. The dynamic power regulation module 171 adjusts according to real-time data: the current phase difference of the outer high-frequency coil 12 ( ); the current phase difference of the middle-frequency coil 13 ( ); the current phase difference of the inner power-frequency coil 14 ( ).

[0058] Taking the sintering of Inconel 718 alloy powder with a diameter of 3 m as an example: During the detection stage, the infrared temperature sensors 15 detect a temperature difference of -12 °C at an axial position of 1.5 m. The magnetic flux detectors 16 show that the magnetic field strength deviation in the circumferential area of 90° to 180° reaches 18%.

[0059] Then, during the adjustment stage, the following operations are performed through the dynamic power regulation module 171: Adjust the of the outer high-frequency coil 12 from 120° to 90°, increasing the local power density by 15%; adjust the of the middle-frequency coil 13 from 60° to 45°, enhancing the circumferential magnetic field uniformity; keep the of the inner power-frequency coil 14 = 120°, maintaining stable heating of the core.

[0060] Control effect: The axial temperature difference drops to ±5 °C within 30 seconds; the circumferential magnetic field deviation drops from 18% to 6%; compared with open-loop control, the total energy consumption is reduced by 22%.

[0061] In some embodiments, refer to Figure 2 andFigure 3 , the hollow interlayer 11 of the high-pressure vessel 1 is filled with a silicon nitride ceramic honeycomb structure 18, and the outer high-frequency coil 12, the middle-frequency coil 13 in the middle layer, and the inner power-frequency coil 14 are embedded in the silicon nitride ceramic honeycomb structure 18.

[0062] Specifically, the silicon nitride ceramic honeycomb structure 18 is filled in the hollow interlayer 11 of the high-pressure vessel 1. The honeycomb cells are regular hexagons, the porosity is 40%, the lattice arrangement direction is parallel to the axis of the high-pressure vessel 1, and a silicon carbide coating is formed on the inner surface of the honeycomb cells by chemical vapor deposition (CVD).

[0063] The outer high-frequency coil 12 is embedded in the long side direction of the honeycomb cells and spirally passes through the honeycomb channels along the axis; the middle-frequency coil 13 in the middle layer is embedded in the diagonal direction of the honeycomb cells and penetrates the honeycomb structure at a 45° crossing angle; the inner power-frequency coil 14 is embedded in the short side direction of the honeycomb cells, and alumina insulation is filled between the copper bars and the honeycomb wall, and they are evenly arranged circumferentially, and a set of copper bar windings is set every 90°.

[0064] Among them, the silicon nitride ceramic honeycomb structure 18 is prepared by 3D printing technology to prepare a silicon nitride ceramic honeycomb green body, and is densified by gas pressure sintering at 1600°C.

[0065] Furthermore, the outer high-frequency coil 12 forms a spiral guiding groove by laser cutting the honeycomb wall, fills silicon nitride slurry after embedding a copper tube and cures it; the middle-frequency coil 13 in the middle layer pre-sets silver-coated copper wires in the cross channels and vacuum impregnates silica sol to enhance the bonding strength; the inner power-frequency coil 14 presses the copper bars into the honeycomb cells by high-pressure injection molding, and polishes them flat after the alumina insulating glue is cured.

[0066] Compared with the scheme without honeycomb structure, vibration suppression test: Under the condition of 200 MPa, the vibration amplitude of the coil is reduced by 85%; the resonance peak shifts from 850 Hz to 1350 Hz, away from the working frequency range of 20 kHz / 10 kHz / 50 Hz.

[0067] Verification of the thermal field uniformity, taking a 3m diameter container and Ti-6Al-4V powder as an example, the axial temperature difference can be reduced to ±5°C, and the circumferential temperature difference is reduced to ±3°C.

[0068] After thermal cycle testing, 20°C ↔ 1200°C, 1000 times: the honeycomb structure has no cracks, the displacement of the copper tube / wire is <0.02 mm, and the deformation rate of the honeycomb structure is <0.01% Furthermore, the distance between the silicon nitride ceramic honeycomb structure 18 and the outer high-frequency coil 12, the middle-frequency coil 13 in the middle layer, and the inner power-frequency coil 14 is 0.1 - 0.3 mm.

[0069] Specifically, the silicon nitride ceramic honeycomb structure 18 is filled in the hollow interlayer of the high-pressure vessel. The honeycomb cells are regular hexagons, with a pore diameter of 2.0 mm, a wall thickness of 0.4 mm, and a porosity of 40%.

[0070] The outer high-frequency coil 12 is made of rectangular copper tubing, with a distance of 0.2 mm ± 0.05 mm from the honeycomb wall, a spiral winding pitch of 5 mm, and the gap fluctuation throughout the process ≤ ±0.03 mm.

[0071] The middle-frequency coil 13 in the middle layer is made of silver-coated copper wire, with a distance of 0.25 mm ± 0.05 mm from the honeycomb wall, a cross-arrangement angle of 45°, and the non-uniformity error of the distance < 5%.

[0072] The inner power-frequency coil 14 in the inner layer is made of flat copper bars, with a distance of 0.15 mm ± 0.05 mm from the honeycomb wall, and 8 groups are circumferentially evenly distributed, with the deviation of the distance consistency < 0.02 mm.

[0073] The silicon nitride honeycomb green body is prepared by 3D printing. The inner cavity size of the honeycomb cells is designed according to the following formula: D 腔 =D 线圈外径 +2G (G = 0.1 - 0.3 mm) Among them, D 线圈外径 is the outer diameter of each layer of coil, and G is the designed gap.

[0074] Compared with the non-spacing control scheme, by setting the distance between the silicon nitride ceramic honeycomb structure 18 and the outer high-frequency coil 12, the middle-frequency coil 13 in the middle layer and the inner power-frequency coil 14 in the inner layer to be 0.1 - 0.3 mm, the magnetic field uniformity is optimized. Among them, when the distance is 0.2 mm, the circumferential magnetic field deviation drops from 18% to 3%, and the axial magnetic field attenuation rate improves from 20 dB / m to 6 dB / m. The vibration suppression effect is also improved. Under the condition of 200 MPa, the peak amplitude drops from 130 μm (without spacing control) to 15 μm (spacing 0.2 mm), and the vibration energy transfer rate decreases by 89%.

[0075] Furthermore, the lattice axes of the silicon nitride ceramic honeycomb structure 18 are arranged at an angle of 30° - 60° with the axis of the high-pressure vessel 1 to form a spiral heat flow channel.

[0076] Specifically, the lattice arrangement is realized by preparing the honeycomb green body using 3D printing technology, and the printing path is designed according to the following rules: The angle between the lattice axis of the honeycomb cell and the axis of the container is set to 45°, and the lattice directions of adjacent layers are alternately deflected by ±5° to form a spiral reinforcement structure. After gas pressure sintering at 1600 °C, the bending strength of the honeycomb structure ≥ 400 MPa.

[0077] In some embodiments, a graphite buffer layer 11 is provided between the silicon nitride ceramic honeycomb structure 18 and the inner wall of the high-pressure vessel 1.

[0078] The installation process of the graphite buffer layer 11 is as follows: spray a boron nitride transition layer on the contact surface between the silicon nitride ceramic honeycomb structure 18 and the inner wall of the high-pressure vessel 1; bond the graphite buffer layer 11 to the two side interfaces with a high-temperature adhesive (aluminum phosphate-based), and the curing conditions are a temperature of 800 °C, a pressure of 5 MPa, and a time of 2 h.

[0079] Further, referring to Figure 2 and Figure 3 , the loading rack 2 is a graphene-coated silicon carbide grid structure, and boron nitride heat-conducting sheets 21 are integrated on the grid surface of the loading rack 2.

[0080] The silicon carbide grid matrix is woven from silicon carbide fibers, the grid porosity is 65%, and the overall is a multi-layer stacked structure; the graphene coating is coated on the surface of the silicon carbide grid by chemical vapor deposition, and the coverage rate: ≥99% The boron nitride heat-conducting sheets 21 are integrated at the grid nodes, and the boron nitride heat-conducting sheets 21 are connected to the silicon carbide grid by high-temperature brazing, and the brazing filler is an Ag-Cu-Ti alloy (melting point 780 °C).

[0081] In some embodiments, referring to Figure 2 and Figure 3 , an insulating layer 3 is provided inside the high-pressure vessel 1, and the insulating layer 3 is made of a high-efficiency insulating material, including ceramic fibers or alumina foam.

[0082] The provided insulating layer 3 can reduce heat loss, keep the temperature inside the high-pressure vessel 1 uniform, and at the same time protect the structure of the high-pressure vessel 1 from the influence of high temperature.

[0083] Further, the ceramic fiber / alumina foam is chemically inert at high temperatures, which can avoid grain boundary corrosion and creep fracture of the high-pressure vessel 1 caused by long-term high-temperature exposure, extend the life of the high-pressure vessel 1, and reduce the maintenance cost.

[0084] In some embodiments, a first feed inlet is provided on the high-pressure vessel 1, and a second feed inlet is provided on the loading rack 2 for putting in the powder to be processed and taking out the processed and formed workpiece.

[0085] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A rapid heating ultra-large hot isostatic pressing device for powder metallurgy, characterized in that: including a cylindrical high-pressure vessel with a hollow interlayer formed between its inner wall and outer wall; a loading rack disposed inside the high-pressure vessel for carrying powder metallurgy furnace charge; a composite heating coil disposed inside the hollow interlayer, including: an outer high-frequency coil spirally wound along the axial direction of the high-pressure vessel; a middle intermediate-frequency coil arranged in a cross pattern along the axial and circumferential directions of the high-pressure vessel; an inner power-frequency coil evenly arranged along the circumferential direction of the high-pressure vessel.

2. The rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy according to claim 1, characterized in that the working frequency of the outer high-frequency coil is 20 kHz ± 2 kHz, and it is spirally wound with a rectangular cross-section copper tube; the working frequency of the middle intermediate-frequency coil is 10 kHz ± 1 kHz, and it is arranged with silver-coated copper wires at a cross angle; the working frequency of the inner power-frequency coil is 50 Hz ± 5 Hz, and it is a circumferentially evenly distributed copper bar winding.

3. The rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy according to claim 1, characterized in that, It further includes a controller, and the outer high-frequency coil, the middle intermediate-frequency coil and the inner power-frequency coil are independently controlled by the controller.

4. The rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy according to claim 3, characterized in that, It further includes: multiple groups of infrared temperature sensors distributed along the axial direction of the high-pressure vessel; multiple groups of magnetic flux detectors distributed along the circumferential direction of the high-pressure vessel; the infrared temperature sensors and the magnetic flux detectors are connected to the controller, and the controller includes a dynamic power adjustment module for adjusting the current phase difference of the outer high-frequency coil, the middle intermediate-frequency coil and the inner power-frequency coil according to real-time detection data.

5. The rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy according to claim 1, characterized in that, The hollow interlayer of the high-pressure vessel is filled with a silicon nitride ceramic honeycomb structure, and the outer high-frequency coil, the middle intermediate-frequency coil and the inner power-frequency coil are embedded in the silicon nitride ceramic honeycomb structure.

6. The rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy according to claim 5, characterized in that, The distance between the silicon nitride ceramic honeycomb structure and the outer high-frequency coil, the middle intermediate-frequency coil and the inner power-frequency coil is 0.1 - 0.3 mm.

7. The rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy according to claim 5, characterized in that, The lattice axis of the silicon nitride ceramic honeycomb structure is arranged at an angle of 30° - 60° with the axis of the high-pressure vessel.

8. The rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy according to claim 5, characterized in that A graphite buffer layer is provided between the silicon nitride ceramic honeycomb structure and the inner wall of the high-pressure vessel.

9. The rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy according to claim 1, wherein, The loading rack is a graphene-coated silicon carbide grid structure, and boron nitride heat-conducting sheets are integrated on the grid surface of the loading rack.

10. The rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy according to claim 1, wherein, An insulating layer is provided inside the high-pressure vessel, and the insulating layer is made of a high-efficiency insulating material, including ceramic fiber or alumina foam.

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