A fast heating ultra-large hot isostatic pressing equipment for powder metallurgy

Abstract

The present application relates to the technical field of hot isostatic pressing equipment, and provides a fast-heating, ultra-large hot isostatic pressing equipment for powder metallurgy. The hot isostatic pressing equipment includes a cylindrical high-pressure vessel with a hollow interlayer formed between its inner and outer walls; a charging rack disposed inside the high-pressure vessel for carrying powder metallurgy charge; and a composite heating coil disposed within the hollow interlayer, comprising: an outer high-frequency coil, spirally wound along the axial direction of the high-pressure vessel; and a middle medium-frequency coil, cross-arranged along the axial and circumferential directions of the high-pressure vessel. Powder metallurgy is an advanced manufacturing technology that manufactures parts by preparing, molding, and sintering metal powder. Hot isostatic pressing equipment is a machine used for pressurized heating in this process. The accelerated heating ultra-large hot isostatic pressing equipment of the present application improves the heating efficiency of powder metallurgy.

Description

Technical Field

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

[0002] Powder metallurgy is an advanced manufacturing technology that manufactures materials or parts through the preparation, molding and sintering of metal powders. Its core lies in achieving near-net-shape formation of complex shapes and high-performance materials through precise control of powder and process optimization.

[0003] Hot isostatic pressing (HIP) equipment is an advanced metal powder processing device that densifies metal powder materials, eliminates internal defects, and improves their mechanical properties by treating them under high temperature and high pressure. HIP utilizes an inert gas (such as argon) as a medium to isostatically press the workpiece under high temperature and high pressure. Specifically, a heating system heats the metal powder to a specific temperature, softening or melting it, thereby facilitating the closure of internal pores and promoting material flow. By filling a sealed container with high-pressure inert gas, the metal powder is subjected to uniform pressure in all directions, closing the pores within the metal powder and achieving densification.

[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, even reaching 5 meters or more. It is able to raise the internal cavity temperature to the level required by the process in a short period of time, usually ranging from 1000℃ to 2000℃. Despite the huge size of the equipment, it is still necessary to maintain a high working pressure, generally between 100MPa and 200MPa, 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 vessel, a heating system, a gas supply, and a vacuum pump. Among them, the heating system is used to quickly raise the temperature inside the high-pressure vessel to the level required by the process in a short period of time. Common heaters include resistance heaters, induction heaters, and microwave heaters.

[0005] The hot isostatic pressing equipment currently using induction heaters is lacking in heating speed and uniformity. Summary of the Invention

[0006] The purpose of this application is to propose a fast-heating ultra-large hot isostatic pressing equipment for powder metallurgy, so as to solve the technical problems that the existing hot isostatic pressing equipment is insufficient in heating speed and uniformity.

[0007] To achieve the above objectives, the technical solution adopted in this application is to provide a rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy, comprising:

[0008] A cylindrical high-pressure container with a hollow sandwich formed between the inner and outer walls;

[0009] A charging rack provided inside the high-pressure vessel for carrying powder metallurgy charge;

[0010] The composite heating coil disposed in the hollow interlayer includes:

[0011] An outer high-frequency coil is spirally wound along the axial direction of the high-pressure container;

[0012] The middle-layer medium-frequency coil is arranged crosswise along the axial direction and circumferential direction of the high-pressure container;

[0013] The inner layer power frequency coils are evenly arranged along the circumference of the high-pressure container.

[0014] Furthermore, the outer high-frequency coil has an operating frequency of 20kHz±2kHz and is spirally wound using a copper tube with a rectangular cross-section;

[0015] The middle-layer intermediate frequency coil has an operating frequency of 10kHz±1kHz and is arranged with silver-clad copper wires at a cross angle;

[0016] The operating frequency of the inner layer power frequency coil is 50 Hz ± 5 Hz, and a circumferentially uniformly distributed copper bar winding is used.

[0017] Furthermore, a controller is included, and the outer high-frequency coil, the middle medium-frequency coil and the inner power-frequency coil are independently controlled by the controller.

[0018] Furthermore, it also includes:

[0019] Multiple groups of infrared temperature measuring sensors distributed along the axial direction of the high-pressure container;

[0020] a plurality of groups of magnetic flux detectors distributed along the circumference of the high-pressure container;

[0021] The infrared temperature sensor and the magnetic flux detector are connected to the controller, and the controller includes a dynamic power regulation 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.

[0022] In some embodiments, the hollow interlayer of the high-pressure container is filled with a silicon nitride ceramic honeycomb structure, and the outer high-frequency coil, the middle medium-frequency coil and the inner power frequency coil are embedded in the silicon nitride ceramic honeycomb structure.

[0023] Furthermore, the distance between the silicon nitride ceramic honeycomb structure and the outer high-frequency coil, the middle medium-frequency coil and the inner power-frequency coil is 0.1-0.3 mm.

[0024] 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 container.

[0025] Furthermore, a graphite buffer layer is provided between the silicon nitride ceramic honeycomb structure and the inner wall of the high-pressure container.

[0026] In some embodiments, the charging rack is a graphene-coated silicon carbide grid structure, and a boron nitride heat conducting sheet is integrated on the grid surface of the charging rack.

[0027] In some embodiments, a heat-insulating layer is provided inside the high-pressure container, and the heat-insulating layer is made of a high-efficiency heat-insulating material, including ceramic fiber or alumina foam.

[0028] The beneficial effects of the ultra-large hot isostatic pressing equipment for rapid heating of powder metallurgy provided by the present application are at least as follows: the outer high-frequency coil provided in the present application can quickly heat the surface layer, improve axial uniformity, and shorten the surface heating time; the middle-layer medium-frequency coil is arranged axially and circumferentially crosswise, which can suppress the axial temperature gradient and reduce the axial temperature difference; the inner-layer industrial frequency coil is arranged uniformly circumferentially to eliminate the temperature difference between the core and the circumference of the multi-layer material; through the coordinated 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; the multi-layer coil greatly improves the heating efficiency of the powder metallurgy in the loading rack. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0030] Figure 1 A schematic diagram of the external structure of a rapid heating ultra-large hot isostatic pressing device for powder metallurgy provided in an embodiment of the present application;

[0031] Figure 2 This is a diagram of the internal structure of a rapid heating ultra-large hot isostatic pressing device for powder metallurgy provided in an embodiment of the present application;

[0032] Figure 3 for Figure 2 A schematic diagram of the structure after a silicon nitride ceramic honeycomb structure is set;

[0033] Figure 4 A schematic diagram of the structure of an outer high-frequency coil provided in an embodiment of the present application being arranged on a high-pressure vessel;

[0034] Figure 5 A schematic diagram of the structure of a middle-layer medium-frequency coil provided in an embodiment of the present application provided on a high-pressure vessel;

[0035] Figure 6 A schematic diagram of the structure of an inner power frequency coil provided in an embodiment of the present application provided on a high-pressure vessel;

[0036] Figure 7 A schematic diagram of the structure of an infrared temperature sensor and a magnetic flux detector provided in an embodiment of the present application arranged on a high-pressure vessel;

[0037] Figure 8 A schematic diagram of the circuit connections of the controller provided in an embodiment of the present application.

[0038] Among them, the reference numerals in the figures are,

[0039] 1. High-pressure vessels;

[0040] 11. Hollow interlayer;

[0041] 12. Outer high-frequency coil;

[0042] 13. Middle layer medium frequency coil;

[0043] 14. Inner power frequency coil;

[0044] 15. Infrared temperature sensor;

[0045] 16. Magnetic flux detector;

[0046] 17. Controller; 171. Dynamic power regulation module;

[0047] 18. Silicon nitride ceramic honeycomb structure; 181. Graphite buffer layer;

[0048] 2. Loading rack; 21. Boron nitride thermal conductive sheet;

[0049] 3. Thermal insulation layer. DETAILED DESCRIPTION

[0050] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0051] It should be noted that when a component is referred to as being "fixed on" or "disposed on" another component, it may be located directly or indirectly on the other component. When a component is referred to as being "connected to" another component, it may be directly or indirectly connected to the other component. The directions or positions indicated by the terms "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the directions or positions shown in the accompanying drawings and are only for the convenience of description and cannot be understood as limitations on this technical solution. The terms "first" and "second" are only used for the purpose of convenience of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0052] At present, the hot isostatic pressing equipment using induction heaters has a high-pressure container set as a cylinder, and an induction coil is set on the outside of the cylindrical high-pressure container. A single conductive wire is wound around the outside of the high-pressure container in a spiral form, and the spiral coil is also correspondingly constructed in a cylindrical shape. However, since the cylindrical spiral coil mainly generates a magnetic field on one plane, it is only suitable for cylindrical or long high-pressure containers. In addition, the magnetic field of the cylindrical spiral coil is mainly concentrated in the winding area, so the heating in this area is relatively uniform, but a temperature gradient may appear in the area away from the coil. Taking a cylindrical high-pressure container as an example, the heating speed in the middle of the cylindrical high-pressure container is faster, while the heating speed at the bottom and top is relatively slow, which will cause a temperature gradient, making the existing hot isostatic pressing equipment lacking in both heating speed and uniformity.

[0053] The following describes the rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy according to an embodiment of the present application in conjunction with the accompanying drawings.

[0054] See also Figure 1 , Figure 1 The external structure diagram of the rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy of the present application is shown. Figure 1-Figure 3 The rapid heating ultra-large hot isostatic pressing equipment includes a cylindrical high-pressure vessel 1 and a charging rack 2 arranged inside the high-pressure vessel 1. A hollow interlayer 11 is formed between the inner wall and the outer wall of the high-pressure vessel 1, and the charging rack 2 is used to carry powder metallurgy charge.

[0055] Continue reading Figure 2-Figure 3 A composite heating coil is arranged in the hollow interlayer 11, and the composite heating coil includes an outer high-frequency coil 12, a middle medium-frequency coil 13 and an inner power-frequency coil 14. The outer high-frequency coil 12 is spirally wound along the axial direction of the high-pressure vessel 1; the middle medium-frequency coil 13 is cross-arranged along the axial and circumferential directions of the high-pressure vessel 1; and the inner power-frequency coil 14 is evenly arranged along the circumference of the high-pressure vessel 1.

[0056] The working steps of the ultra-large hot isostatic pressing equipment after opening involve multiple links, including pretreatment, heating, pressurization, insulation and cooling. The following are the working steps after the equipment is opened:

[0057] Step 1: Place the metal powder workpiece to be processed into the high-pressure vessel 1 of the HIP equipment, paying attention to the position to ensure uniform heating and pressure distribution.

[0058] Step 2: Start the equipment and enter the standby state, ready for heating and pressurizing operations.

[0059] Step 3: Based on the metal powder material and process requirements, the initial heating power, frequency, and target temperature are set in controller 17. The outer high-frequency coil 12, the middle intermediate-frequency coil 13, and the inner power-frequency coil 14 are sequentially activated to begin heating the workpiece. The alternating magnetic field generated by the induction coils creates eddy currents within the workpiece, enabling rapid heating.

[0060] Step 4: After reaching the predetermined temperature, gradually increase the pressure to make the metal powder undergo isostatic pressing under high temperature and high pressure conditions.

[0061] Step 5: Maintain the metal powder under high temperature and high pressure conditions for a certain period of time to fully improve the internal structure of the metal powder.

[0062] Step 6: After the heat preservation is completed, the metal powder needs to be cooled to restore to normal temperature and pressure.

[0063] Step 7: After cooling and decompression, the formed workpiece made of metal powder is taken out and processed subsequently.

[0064] The outer high-frequency coil 12 provided in this application can quickly heat the surface layer, improve axial uniformity, and shorten the surface heating time. The middle-layer medium-frequency coil 13 is arranged axially and circumferentially cross-wise, which can suppress the axial temperature gradient and reduce the axial temperature difference. The inner-layer industrial frequency coil 14 is arranged uniformly circumferentially to eliminate the temperature difference between the core and the circumference of the multi-layer material. Through the coordinated 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. The multi-layer coils greatly improve the heating efficiency of the powder metallurgy in the loading rack 2.

[0065] Furthermore, a hollow interlayer 11 with a width of 80 mm is formed between the inner wall and the outer wall of the cylindrical high-pressure container 1. The diameter of the high-pressure container 1 is 2.8 m, the height is 5.5 m, and the material is SA-723 Gr.3 steel.

[0066] The charging rack 2 is made of a high-temperature resistant alloy grid and is installed vertically on the central axis of the high-pressure vessel 1. The grid layer spacing of the charging rack 2 is 150 mm, and the maximum load of a single layer is 2.5 tons. It is used for stacking powder metallurgy charges.

[0067] The outer high-frequency coil 12 is made of a rectangular copper tube. Figure 4 It is spirally wound along the axial direction of the high-pressure vessel 1, with a pitch of 5mm, an operating frequency of 20kHz, a coverage depth of 5mm, and is used for rapid heating of the charge surface.

[0068] The middle-layer intermediate frequency coil 13 adopts a circular cross-section silver-clad copper conductor, see Figure 5 , arranged at a 45° cross angle along the axial and circumferential directions of the high-pressure vessel 1, with an operating frequency of 10kHz and a coverage depth of 12mm, to compensate for the axial temperature gradient.

[0069] The inner power frequency coil 14 is made of flat copper bar, see Figure 6 , evenly arranged along the circumference of the high-pressure vessel 1, with a total of 8 independent windings; the operating frequency is 50Hz, the penetration depth is ≥50mm, and it is used to eliminate the heat conduction bottleneck when multiple layers of materials are stacked.

[0070] Taking the sintering of Ti-6Al-4V titanium alloy powder with a diameter of 2.8m as an example, the coil collaborative working mode is:

[0071] The outer high-frequency coil 12 is supplied with 20kHz alternating current, generating eddy current within 5mm depth of the charge surface, heating up to 500℃ within 30 seconds. The spiral winding structure ensures uniform axial heat distribution.

[0072] A 10kHz current is passed through the middle-layer medium-frequency coil 13 to generate a medium-frequency magnetic field that penetrates to a depth of 12mm, compensating for the temperature attenuation caused by the axial length of the container. The cross-arrangement forms a mesh thermal field, making the axial temperature difference ≤±10°C.

[0073] The inner layer power frequency coil 14 penetrates 50mm deep through the 50Hz low-frequency magnetic field, directly heating the core of the multi-layer stacked material. The 8 groups of windings evenly arranged circumferentially generate a rotating magnetic field to eliminate circumferential temperature differences.

[0074] Through recording, the heating effect was obtained: it took 7 minutes and 30 seconds to heat up from 0 to 1200℃, the heating rate reached an average of 160℃ / min, the maximum deviation of the axial temperature difference was 8.3℃ (the traditional single-coil structure was ±25℃); the maximum deviation of the circumferential temperature difference was 4.7℃ (the traditional structure was ±15℃).

[0075] It can be found that the heating speed is improved, the axial temperature difference and the circumferential temperature difference are reduced, the heating speed is faster, and the heating uniformity is higher.

[0076] In some embodiments, the outer high-frequency coil 12 is constructed from a rectangular copper tube with dimensions of 10 mm x 5 mm and a wall thickness of 1 mm. The outer high-frequency coil 12 is helically wound along the axial direction of the high-pressure vessel 1 with a pitch of 5 mm and a winding density of 200 turns per meter. The outer high-frequency coil 12 operates at a frequency of 20 kHz ± 2 kHz, a current density of 50 A / mm², and a skin depth of 5 mm, covering the charge surface to a depth of 0-5 mm.

[0077] The middle-layer IF coil 13 uses silver-clad copper conductors with a diameter of 8 mm and a silver layer thickness of 0.1 mm. The conductors are arranged alternately axially and circumferentially at a crossing angle of 45°±5°, forming a diamond-shaped grid structure. The middle-layer IF coil 13 operates at a frequency of 10 kHz±1 kHz, a current density of 30 A / mm², and a magnetic field penetration depth of 12 mm, covering the furnace charge to a depth of 5-17 mm.

[0078] The inner power-frequency coil 14 utilizes flat copper bars with a cross-sectional area of ​​50 mm x 20 mm, evenly spaced along the circumference of the high-pressure vessel 1. Eight independent windings are arranged, each separated by 45°, with a copper bar spacing of 10 mm. The inner power-frequency coil 14 operates at a frequency of 50 Hz ± 5 Hz, with a three-phase current phase difference of 120° ± 5°. The magnetic field penetrates 50 mm or more, covering the core area of ​​the charge.

[0079] Still taking the sintering of Ti-6Al-4V titanium alloy powder with a diameter of 2.5m as an example:

[0080] The 20kHz high-frequency current of the outer high-frequency coil 12 produces a skin effect in the copper tube, and the 0-5mm area on the surface of the charge rises to 480℃ within 25 seconds. The spiral winding structure makes the axial heat distribution uniform, and the axial temperature difference is ≤±8℃.

[0081] The 10kHz intermediate frequency magnetic field of the middle 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, reducing the circumferential temperature difference from ±18°C to ±6°C.

[0082] The 50Hz low-frequency magnetic field of the inner power-frequency coil 14 directly heats the core of the charge, causing the core to heat up at a rate of 85°C / min. The eight circumferentially evenly distributed windings generate a rotating magnetic field, and the circumferential temperature difference of the core is ≤±4°C.

[0083] The records show the heating effect: it takes 7 minutes and 15 seconds to heat up from 0 to 1200°C, with an average heating rate of 165°C / min; the density obtained is 99.95% for the surface layer and 99.92% for the core of the charge powder (ASTM B962 standard).

[0084] In some embodiments, see Figure 1 and Figure 8The ultra-large hot isostatic pressing equipment for rapid heating of powder metallurgy further includes a controller 17 , and the outer high-frequency coil 12 , the middle intermediate-frequency coil 13 and the inner power-frequency coil 14 are independently controlled by the controller 17 .

[0085] Further, see Figure 7 The rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy also includes multiple groups of infrared temperature sensors 15 distributed along the axial direction of the high-pressure vessel 1; multiple groups of magnetic flux detectors 16 distributed along the circumferential direction of the high-pressure vessel 1; the infrared temperature sensors 15 and the magnetic flux detectors 16 are connected to a controller 17, and the controller 17 includes a dynamic power adjustment module 171 for adjusting the current phase difference of the outer high-frequency coil 12, the middle intermediate frequency coil 13 and the inner power frequency coil 14 according to real-time detection data.

[0086] Exemplarily, the controller 17 adopts a multi-core industrial PLC, model SIEMENS S7-1500. The controller 17 has a built-in 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°~180° and an adjustment accuracy of ±0.5°; the controller 17 also includes a data fusion unit with a processing frequency of 1kHz, which is used to synchronously analyze temperature and magnetic flux signals.

[0087] The infrared temperature sensors 15 are distributed along the axial direction of the high-pressure container 1 at intervals of 200 mm, with a total of 32 groups;

[0088] A single group contains 4 temperature measurement points, including 0°, 90°, 180°, and 270° circumferential positions. The temperature detection range is 20~1500℃, and the accuracy is ±2℃.

[0089] The magnetic flux detectors 16 are distributed in a group every 30° along the circumference of the high-pressure container, with a total of 12 groups; using Hall effect sensors, the magnetic flux detectors 16 have a range of 0~2T and a resolution of 1mT.

[0090] The infrared temperature sensor 15 and the magnetic flux detector 16 are connected to the controller 17 via the PROFIBUS bus. The dynamic power regulation module 171 adjusts the current phase difference of the outer high-frequency coil 12 ( ); The current phase difference of the middle layer intermediate frequency coil 13 ( ); The inner layer power frequency coil 14 current phase difference ( ).

[0091] Take the sintering of Inconel 718 alloy powder with a diameter of 3m as an example:

[0092] During the detection phase, the infrared temperature sensor 15 detected a temperature difference of -12°C at 1.5m in the axial direction; the magnetic flux detector 16 showed that the magnetic field intensity deviation in the circumferential area of ​​90°~180° was as high as 18%.

[0093] Then, the adjustment phase is performed, and the dynamic power adjustment module 171 performs the following operations:

[0094] The outer high frequency coil 12 Adjust from 120° to 90°, increase the local power density by 15%; Adjust from 60° to 45° to enhance the uniformity of the circumferential magnetic field; maintain the inner layer power frequency coil 14 =120°, maintain stable heating of the core.

[0095] Control effect: The axial temperature difference was reduced to ±5°C within 30 seconds; the circumferential magnetic field deviation was reduced from 18% to 6%; compared with open-loop control, the total energy consumption was reduced by 22%.

[0096] In some embodiments, see Figure 2 and Figure 3 The hollow interlayer 11 of the high-pressure container 1 is filled with a silicon nitride ceramic honeycomb structure 18 , and the outer high-frequency coil 12 , the middle intermediate frequency coil 13 and the inner power frequency coil 14 are embedded in the silicon nitride ceramic honeycomb structure 18 .

[0097] Specifically, the silicon nitride ceramic honeycomb structure 18 is filled in the hollow interlayer 11 of the high-pressure vessel 1. The honeycomb unit is a regular hexagon with a porosity of 40%. The lattice arrangement direction is parallel to the axis of the high-pressure vessel 1. A silicon carbide coating is formed on the inner surface of the honeycomb unit by chemical vapor deposition (CVD).

[0098] The outer high-frequency coil 12 is embedded in the long side direction of the honeycomb unit and spirals through the honeycomb channel along the axial direction; the middle medium-frequency coil 13 is embedded in the diagonal direction of the honeycomb unit and penetrates the honeycomb structure at a 45° cross angle; the inner power frequency coil 14 is embedded in the short side direction of the honeycomb unit, and alumina insulation is filled between the copper bar and the honeycomb wall. It is evenly arranged along the circumference, and a group of copper bar windings is set every 90°.

[0099] The silicon nitride ceramic honeycomb structure 18 is prepared by 3D printing technology to form a silicon nitride ceramic honeycomb blank, which is then densified by gas pressure sintering at 1600°C.

[0100] Furthermore, the outer high-frequency coil 12 uses laser cutting to form a spiral guide groove in the honeycomb wall, which is then embedded in a copper tube and filled with silicon nitride slurry for curing. The middle intermediate-frequency coil 13 is formed by pre-placed silver-clad copper wires in the cross-channel and vacuum-impregnated with silica sol to enhance the bonding strength. The inner power-frequency coil 14 is formed by pressing the copper busbar into the honeycomb unit through high-pressure injection molding, and the alumina insulating glue is polished and smoothed after curing.

[0101] Comparison with the solution without honeycomb structure, vibration suppression test:

[0102] Under the working condition of 200MPa, the vibration amplitude of the coil is reduced by 85%; the resonance peak shifts from 850Hz to 1350Hz, far away from the operating frequency range of 20kHz / 10kHz / 50Hz.

[0103] Thermal field uniformity verification, 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 can be reduced to ±3°C.

[0104] After thermal cycle test, 20℃↔1200℃, 1000 times: the honeycomb structure has no cracks, the displacement of copper tube / wire is less than 0.02mm, and the deformation rate of honeycomb structure is less than 0.01%;

[0105] Furthermore, the distance between the silicon nitride ceramic honeycomb structure 18 and the outer high-frequency coil 12 , the middle intermediate-frequency coil 13 and the inner power-frequency coil 14 is 0.1-0.3 mm.

[0106] Specifically, the silicon nitride ceramic honeycomb structure 18 is filled in the hollow interlayer of the high-pressure container, and the honeycomb unit is a regular hexagon with a pore diameter of 2.0 mm, a wall thickness of 0.4 mm, and a porosity of 40%.

[0107] The outer high-frequency coil 12 is made of a rectangular copper tube, with a spacing of 0.2 mm ± 0.05 mm from the honeycomb wall, a spiral winding pitch of 5 mm, and a full-length gap fluctuation of ≤ ± 0.03 mm.

[0108] The middle-layer intermediate frequency coil 13 uses silver-clad copper wire, with a spacing of 0.25mm±0.05mm from the honeycomb wall, a cross-arrangement angle of 45°, and a spacing uniformity error of <5%.

[0109] The inner layer power frequency coil 14 is made of flat copper busbar, with a spacing of 0.15mm±0.05mm from the honeycomb wall, 8 groups of which are evenly distributed in the circumferential direction, and a spacing consistency deviation of <0.02mm.

[0110] Silicon nitride honeycomb blanks were prepared by 3D printing, and the inner cavity size of the honeycomb unit was designed according to the following formula:

[0111] D 腔 =D 线圈外径 +2G(G=0.1-0.3mm)

[0112] Among them, D 线圈外径 is the outer diameter of each layer of coil, and G is the design gap.

[0113] Compared to the zero-spacing control scheme, by setting the spacing between the silicon nitride ceramic honeycomb structure 18 and the outer high-frequency coil 12, the middle intermediate-frequency coil 13, and the inner power-frequency coil 14 to 0.1-0.3mm, magnetic field uniformity is optimized. At a spacing of 0.2mm, the circumferential magnetic field deviation is reduced from 18% to 3%, and the axial magnetic field attenuation rate is improved from 20dB / m to 6dB / m. Vibration suppression is also improved. At 200MPa, the peak amplitude is reduced from 130μm (zero-spacing control) to 15μm (0.2mm spacing), and the vibration energy transfer rate is reduced by 89%.

[0114] Furthermore, the lattice axis of the silicon nitride ceramic honeycomb structure 18 is arranged at an angle of 30°-60° with the axis of the high-pressure vessel 1 , forming a spiral heat flow channel.

[0115] Specifically, the lattice arrangement is achieved by preparing the honeycomb blank using 3D printing technology, and the printing path is designed according to the following rules:

[0116] The angle between the honeycomb unit lattice axis and the container axis 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℃, the bending strength of the honeycomb structure is ≥400MPa.

[0117] 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 .

[0118] The installation process of the graphite buffer layer 11 is as follows: a boron nitride transition layer is sprayed on the contact surface between the silicon nitride ceramic honeycomb structure 18 and the inner wall of the high-pressure vessel 1; the graphite buffer layer 11 is bonded to the interfaces on both sides using a high-temperature adhesive (aluminum phosphate-based). The curing conditions are a temperature of 800°C, a pressure of 5 MPa, and a time of 2 hours.

[0119] Further, see Figure 2 and Figure 3 The loading rack 2 is a graphene-coated silicon carbide grid structure, and a boron nitride heat conducting sheet 21 is integrated on the grid surface of the loading rack 2.

[0120] The silicon carbide grid matrix is ​​woven from silicon carbide fibers, with a grid porosity of 65% and a multi-layer stacked structure. The graphene coating is applied to the surface of the silicon carbide grid by chemical vapor deposition, with a coverage rate of ≥99%.

[0121] The boron nitride heat conducting sheet 21 is integrated at the grid node. The boron nitride heat conducting sheet 21 is connected to the silicon carbide grid by high temperature brazing. The brazing material is Ag-Cu-Ti alloy (melting point 780°C).

[0122] In some embodiments, see Figure 2 and Figure 3A heat insulation layer 3 is provided inside the high-pressure container 1. The heat insulation layer 3 is made of high-efficiency heat insulation material, including ceramic fiber or alumina foam.

[0123] The provided heat insulation layer 3 can reduce heat loss, maintain a uniform temperature inside the high-pressure container 1, and protect the structure of the high-pressure container 1 from being affected by high temperatures.

[0124] Furthermore, ceramic fiber / alumina foam is chemically inert at high temperatures, which can prevent intergranular corrosion and creep fracture of the high-pressure vessel 1 caused by long-term high-temperature exposure, thereby extending the life of the high-pressure vessel 1 and reducing maintenance costs.

[0125] In some embodiments, the high-pressure container 1 is provided with a first feed port, and the loading rack 2 is provided with a second feed port for putting in powder to be processed and taking out the processed workpiece.

[0126] The above are only 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 principles of the present application should be included in the scope of protection of the present application.

Claims

1. A rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy, characterized by: include A cylindrical high-pressure container with a hollow sandwich formed between the inner and outer walls; A charging rack provided inside the high-pressure vessel for carrying powder metallurgy charge; The composite heating coil disposed in the hollow interlayer includes: The outer high-frequency coil is made of a copper tube with a rectangular cross section and is spirally wound along the axial direction of the high-pressure container; The middle-layer medium-frequency coil is made of silver-clad copper wire and arranged at a cross angle along the axial and circumferential directions of the high-pressure container; The inner power frequency coil adopts copper bar winding and is evenly arranged along the circumference of the high-pressure container; The hollow interlayer of the high-pressure container is filled with a silicon nitride ceramic honeycomb structure, and the outer high-frequency coil, the middle medium-frequency coil and the inner power frequency coil are embedded in the silicon nitride ceramic honeycomb structure.

2. The rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy according to claim 1, characterized in that: The operating frequency of the outer high-frequency coil is 20kHz±2kHz; The operating frequency of the middle-layer intermediate frequency coil is 10kHz±1kHz; The operating frequency of the inner power frequency coil is 50 Hz±5 Hz.

3. The rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy according to claim 1, characterized in that: It also includes a controller, and the outer high-frequency coil, the middle medium-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: Also includes: Multiple groups of infrared temperature measuring sensors distributed along the axial direction of the high-pressure container; a plurality of groups of magnetic flux detectors distributed along the circumference of the high-pressure container; The infrared temperature sensor and the magnetic flux detector are connected to the controller, and the controller includes a dynamic power regulation 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 distance between the silicon nitride ceramic honeycomb structure and the outer high-frequency coil, the middle medium-frequency coil and the inner power-frequency coil is 0.1-0.3 mm.

6. The rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy according to claim 1, 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 container.

7. The rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy according to claim 1, characterized in that: A graphite buffer layer is provided between the silicon nitride ceramic honeycomb structure and the inner wall of the high-pressure container.

8. The rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy according to claim 1, characterized in that: The charging rack is a graphene-coated silicon carbide grid structure, and a boron nitride heat conducting sheet is integrated on the grid surface of the charging rack.

9. The rapid heating ultra-large hot isostatic pressing equipment for powder metallurgy according to claim 1, characterized in that: A heat insulation layer is provided inside the high-pressure container, and the heat insulation layer is made of high-efficiency heat insulation material, including ceramic fiber or alumina foam.

Images