Multi-phase multi-band vacuum in-source casimir densification apparatus and its forming process

Abstract

The application discloses a multi-phase multi-band vacuum inner source Casimir densification equipment and a forming process thereof, belongs to the technical field of metal additive manufacturing post-densification and carbon-based micro-cavity sealing, and aims to replace a hot isostatic pressing equipment. The equipment comprises seven modules of a high vacuum cavity, a phased microwave excitation array, a suspension tool, vacuum pressure stabilization, phase-shifting synchronous main control, low-temperature temperature control and stress relief detection. The phased microwave excitation array comprises a plurality of long-wave microwave and short-wave millimeter wave units capable of independent phase-shifting, and the long-wave microwave and short-wave millimeter wave units are superimposed in the workpiece pores in a phase-coordinated manner to generate uniform inner source Casimir extrusion force. The matching process comprises pretreatment, suspension clamping, vacuum pumping, long-wave microwave pre-pressing, millimeter wave micro-hole flattening, long-wave and short-wave coordinated atomic adhesion, stress relief, solidification and detection. The application realizes the 3D printing blank forging state densification of metal and the atomic level sealing of a carbon-based hydrogen storage cavity under the condition of low-temperature and pressure-free, and can be independently or cooperatively processed by the hot isostatic pressing.

Description

Technical Field

[0001] This invention belongs to the field of metal additive manufacturing post-densification and carbon-based microcavity sealing technology. Specifically, it involves a complete set of equipment and processing technology for full-domain densification based on multi-phase and multi-band intrinsic Casimir effect, low temperature and no mechanical high pressure, which can completely replace hot isostatic pressing equipment or be used in conjunction with hot isostatic pressing equipment. Background Technology

[0002] (I) Existing defects in the metal 3D printing industry Metal workpieces manufactured using additive manufacturing processes such as selective laser melting (SLM) and selective laser sintering (SLS) generally contain micron- and submicron-sized interconnected pores, resulting in porous finished products with tensile, impact, and fatigue mechanical properties far inferior to forged metal parts. Currently, the mainstream densification method in the industry is hot isostatic pressing (HIP). Hot isostatic pressing equipment costs tens of millions of dollars, and the maintenance cost of the high-pressure bearing chamber is extremely high. The complete processing cycle of a single workpiece can take several hours to tens of hours, resulting in extremely low mass production efficiency. The processing requires the simultaneous application of high temperature above 900℃ and high pressure inert gas of 100MPa~200MPa. High temperature will cause metal grains to coarse and significantly reduce the toughness of the component. For 3D printed workpieces with complex internal cavities and irregular shapes, high-pressure gas is applied from the outside to the inside, resulting in severe pressure attenuation in the core of the workpiece, which easily leads to porosity defects in the core. Thin-walled metal parts are prone to buckling and deformation under high pressure, making it impossible to guarantee the original dimensional accuracy of the workpiece.

[0003] Conventional single-frequency microwave sintering relies solely on thermal diffusion to achieve local pore closure, lacks uniform extrusion pressure across the entire area, cannot eliminate large-sized interconnected pores, and ultimately has a limited increase in density, failing to meet forging standards.

[0004] (ii) Fabrication defects of three-dimensional cage carbon hydrogen storage components The three-dimensional carbon cage plate and the hydrogen storage microcavity have a continuous closed-pore micropore structure inside. The high-pressure hydrogen is sealed inside the cavity, which has strict limitations on the processing technology: high temperature and high pressure will directly collapse the carbon cage micropores, causing a large amount of hydrogen to escape and permanently lose the hydrogen storage function.

[0005] Existing fusion welding, brazing, traditional diffusion welding, and hot isostatic pressing cannot simultaneously meet the two major requirements of low temperature and no mechanical extrusion: high temperature damages micropores, high pressure extrusion causes deformation of thin-walled carbon plates, and after long-term use, the sealing interface delaminates and leaks slightly, which cannot meet the long-term airtightness index of superconducting and hydrogen storage devices.

[0006] (III) Shortcomings of existing microwave equipment Commercially available radio frequency and microwave bonding equipment uses only a single frequency excitation source, resulting in uneven electromagnetic field distribution. The edges and pores of the workpiece cannot receive equal force. It can only complete the joining of two planar plates and cannot achieve full-area synchronous densification of three-dimensional porous workpieces. Without an independent phase control structure, electromagnetic waves easily cancel each other on the workpiece surface, making it difficult to penetrate into the internal pore network of the workpiece, thus severely limiting its application scenarios.

[0007] (iv) Summary of Industry Demand Currently, there is a lack of a universal set of equipment that can process various types of porous metal 3D printing blanks, achieve forging-level densification at low temperature and without high pressure, and complete atomic-level sealing of three-dimensional carbon-hydrogen storage chambers. The equipment can be used independently to completely replace hot isostatic pressing, or it can be used as a pre-treatment process to significantly reduce the temperature, pressure and processing time required for hot isostatic pressing, while taking into account the three major requirements of mass production cost, processing accuracy and protection of the original structure of materials. Summary of the Invention

[0008] The purpose of this invention is to overcome the inherent defects of hot isostatic pressing, such as high temperature and high pressure, expensive equipment, uneven pressure on complex workpieces, easy deformation of thin-walled parts, and easy collapse of carbon-based micropores. This solves the problems of traditional single-frequency microwave equipment, such as lack of full-range extrusion force, only being suitable for planar plates, and being unable to penetrate deep into three-dimensional porous workpieces. We provide a set of multi-phase, multi-band vacuum internal Casimir densification equipment and matching molding process. The entire process is carried out at low temperature without rigid mechanical extrusion load, and the densification is completed by relying on the uniform internal extrusion pressure formed inside the pores. The equipment is compatible with two types of products: metal 3D printed parts and three-dimensional cage carbon hydrogen storage components. It can independently replace hot isostatic pressing (HIP) or be combined with HIP for processing, thereby reducing HIP operating parameters, shortening the processing cycle, and reducing equipment wear.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a multi-phase multi-band vacuum internal source Casimir densification device, comprising a high vacuum global resonant cavity module, a multi-band phased microwave excitation array module, a three-dimensional adaptive suspension tooling module, a vacuum degree real-time voltage stabilization detection module, a multi-channel phase-shifting synchronous main control module, a low-temperature closed-loop temperature control module, and a stress-relieving airtightness detection module; The three-dimensional adaptive suspension tooling module and the multi-band phased microwave excitation array module are all built-in and installed inside the high vacuum global resonant cavity module; the vacuum real-time voltage stabilization detection module and the low temperature closed-loop temperature control module are connected to the high vacuum global resonant cavity module through vacuum pipelines and water-cooled circulation pipelines, respectively; the multi-channel phase-shifting synchronization main control module is electrically connected to all other modules through cables to realize integrated closed-loop linkage control of power, frequency, phase, vacuum, and temperature timing. The multi-band phased microwave excitation array adopts a multi-layer three-dimensional surround arrangement structure, including multiple independent radiation units. Each radiation unit is equipped with an independent radio frequency power output unit and a 0° to 360° continuously adjustable phase shifter. The excitation array is divided into two band units: long-wave microwave excitation group and short-wave millimeter-wave excitation group. Long-wave microwaves have strong penetration capabilities and are used to eliminate large-sized interconnected pores inside the workpiece. Short-wave millimeter waves are matched with submicron micro-pore structures to amplify the extrusion pressure inside the pores. Multiple electromagnetic waves are superimposed in phase to form a uniform internal Casimir extrusion pressure inside the massive micro-pores of the workpiece. The three-dimensional adaptive suspension fixture adopts a carbon fiber hollow suspension flexible structure, which only limits the horizontal movement of the workpiece and does not apply vertical mechanical clamping load throughout the process. It can be adapted to any irregularly shaped hollow 3D printed workpiece and ultra-thin carbon-based sheet. The low-temperature closed-loop temperature control module covers all temperature measurement points in the cavity and workpiece, with a closed-loop temperature control range of 25℃~90℃, and there are no local high-temperature heat accumulation areas on the workpiece. The entire equipment has no high-pressure bearing cavity structure and does not require external high-pressure gas pressure. It achieves full-domain isostatic densification by relying on the internal pressure difference in the pores. The equipment is used to replace hot isostatic pressing equipment to achieve forging densification of porous metal 3D printed blanks, three-dimensional cage carbon closed-pore cavities, and thermal damage-free atomic-level solid-state diffusion bonding of thin-walled carbon-based resonant plates.

[0010] The core physical mechanism of this invention differs from traditional hot isostatic pressing (HIP) and conventional single-frequency microwave sintering. Essentially, it relies on multi-phase superimposed electromagnetic waves to construct an internal Casimir pressure difference field (pore standing wave energy difference) within the microscopic pores of the workpiece. In a high-vacuum environment, multiple long-wave microwaves (2–6 GHz) and short-wave millimeter waves (26–40 GHz) are independently phase-shifted and then superimposed to form a standing wave energy distribution within the numerous pores inside the workpiece. Due to the different boundary conditions of the electromagnetic fields inside and outside the pores, there is a significant difference between the standing wave energy density inside the pores and the external substrate. This energy difference is converted into an internal compressive force acting on the pore walls—the "internal Casimir compressive force" as referred to in this invention. The long-wave microwaves have a large penetration depth and are responsible for shrinking large-sized interconnected pores at the micrometer scale; the short-wave millimeter waves have wavelengths that match the submicrometer pore scale and are responsible for amplifying the compressive force inside the micropores. By independently controlling the phases of the multiple electromagnetic waves, the energy difference of the standing waves inside and outside the pores can be actively adjusted, and the magnitude of the compressive force can be dynamically controlled.

[0011] Compared to hot isostatic pressing (HIP): HIP relies on external high-pressure gas to apply pressure from the outside in, resulting in significant pressure attenuation in the core of the workpiece; this invention utilizes electromagnetic waves to directly generate internal compressive force within each micropore, with pressure originating inside the pores and acting from the inside out, eliminating pressure attenuation in irregularly shaped cavities and thick cores. HIP relies on high temperatures (≥900℃) to reduce the material's yield strength to aid pore closure; this invention utilizes the non-thermal effects of multi-band microwaves—driving atomic diffusion and mass migration at temperatures far below those required for thermal diffusion (<90℃) to achieve densification.

[0012] As a preferred embodiment of the present invention, the long-wave microwave operating frequency band is 2GHz to 6GHz, and the short-wave millimeter-wave operating frequency band is 26GHz to 40GHz; the phase of each radiation unit is independently adjustable, and the main control module has multiple preset phase superposition configurations built in, which can avoid electromagnetic wave interference and cancellation on the workpiece surface and ensure that electromagnetic waves continuously penetrate into the internal pore network of the workpiece; by actively controlling the phase of each electromagnetic wave, the difference in radiation energy inside and outside the pores is changed, and the magnitude of the internal Casimir extrusion pressure is dynamically adjusted.

[0013] As a preferred embodiment of the present invention, the high-vacuum global resonant cavity can stably maintain 1×10⁻⁶ -3 Pa ~ 5 × 10 -5 The cavity is equipped with a multi-stage molecular pump assembly, which can stabilize the cavity vacuum to 1×10⁻⁶ Pa within 5 minutes. -4 Pa; The real-time vacuum pressure stabilization and detection module has a built-in vacuum gauge and flow stabilizing valve. It collects the vacuum value in the cavity in real time, automatically adjusts the pumping speed of the pump group to stabilize the vacuum environment, and isolates air, water vapor and impurities from entering the workpiece pores to avoid the formation of an interface oxide layer.

[0014] As a preferred embodiment of the present invention, the multi-channel phase-shifting synchronization main control module has a built-in pore dynamic feedback timing control unit; the cavity is equipped with a spectrum acquisition sensor and an ultrasonic in-situ pore detection sensor; during the densification process of the workpiece, the pore size continuously shrinks, the sensor provides real-time feedback on pore change data, and the main control automatically and synchronously adjusts the frequency, phase and output power of each electromagnetic wave to continuously match the pore resonance condition and avoid the extrusion pressure from rapidly attenuating and failing as the pores shrink.

[0015] As a preferred embodiment of the present invention, the low-temperature closed-loop temperature control module includes a full-area water-cooled bushing and a distributed multi-point temperature sensor, with temperature measurement points covering the upper surface of the workpiece, the inner cavity, and the side wall of the cavity; the system adopts a slow heating and slow cooling closed-loop logic, and the maximum temperature of the entire process does not exceed 90°C, which can avoid high-temperature coarsening of metal grains, high-temperature collapse of carbon-based micropores, and heat escape of hydrogen storage medium.

[0016] As a preferred embodiment of the present invention, the stress-relieving airtightness detection module integrates a global weak reverse demagnetizing coil and a helium mass spectrometer leak detector; after the workpiece is densified, the equipment outputs a low-frequency weak standing wave to release residual electromagnetic field stress at the interface and suppress the generation of microcracks; the helium mass spectrometer leak detector detects the leakage rate of the cavity seal, and the qualified threshold is a leakage rate ≤ 1×10 -9 Pa·m 3 / s.

[0017] As a preferred embodiment of the present invention, the three-dimensional adaptive suspension fixture has two switchable working modes: 3D metal porous billet full-domain suspension support mode and ultra-thin carbon plate multi-point flexible limiting mode; the fixture exerts a vertical constraint force of less than 0.1N on the workpiece, and there is no workpiece deformation caused by rigid extrusion throughout the process.

[0018] In summary, this invention also includes a multi-phase, multi-band vacuum intrinsic Casimir forming process, which is divided into two main branches: metal 3D printing forging densification process and three-dimensional cage carbon hydrogen storage cavity sealing and encapsulation process, and uniformly includes the following processing steps: S1. Ultra-clean pretreatment of workpieces: Remove surface powder and oxide scale from metal 3D printed workpieces; three-dimensional cage carbon plates and hydrogen storage accessories are ultrasonically cleaned with ultrapure water, dried in a dust-free environment, and the flatness of the joint surface is ≤0.5μm after grinding and calibration. S2, Three-dimensional levitation flexible clamping: The workpiece to be processed is placed in the three-dimensional adaptive levitation fixture to complete precise alignment. The fixture only performs horizontal limit and does not apply vertical mechanical clamping load throughout the process. S3. Staged Vacuum Evacuation and Pressure Stabilization of the Chamber: The sealed chamber is activated by a multi-stage molecular pump group to gradually evacuate the internal air and stabilize the chamber vacuum to 1×10⁻⁶. -4 Pa, hold pressure and stand for 5 minutes to fully expel residual gas from workpiece pores and joint interlayer; S4. Multi-phase, multi-band intrinsic Casimir staged densification processing, with low-temperature closed-loop temperature control throughout the process (25℃~90℃): S41, Long-wave microwave full-domain pre-compression stage: The main control retrieves the preset optimal phase superposition configuration, and all long-wave microwave radiation units are turned on synchronously to construct a macroscopic uniform internal extrusion pressure and shrink the large-size interconnected pores inside the workpiece. S42, Millimeter-wave micropore leveling stage: Maintain the output of long-wave microwave low-power substrate, simultaneously turn on the short-wave millimeter-wave array, adjust the phase of each electromagnetic wave to amplify the internal squeezing pressure of the micropores, the micron-level gaps gradually collapse, and the workpiece particle interfaces approach each other to the molecular interaction range. S43, Long and short wave coordinated atomic sealing stage: Long wave and millimeter wave are continuously superimposed in phase, and the porosity of the entire workpiece shrinks synchronously; the density of the metal 3D billet reaches the forging standard; carbon atom lattice interlocks at the interface of carbon-based workpieces to form an atomic-level airtight seal; the system monitors porosity in situ by ultrasound, and automatically jumps to the next process after the porosity meets the standard. S5. Weak standing wave relieves residual stress: Turn off all millimeter wave radiation units and keep only the low-power long-wave substrate standing wave for 3 minutes to relieve residual stress at the workpiece interface and inhibit the generation of microcracks. S6. Vacuum low-temperature lattice curing: The cavity maintains a high vacuum environment, and the water cooling circulation cools the workpiece to room temperature at a uniform speed. Vacuum static curing is carried out for 15-30 minutes to stabilize the internal lattice structure of the workpiece. S7. Finished Product Performance Testing and Unloading: The density of metal workpieces is tested by ultrasound and metallography; tracer helium is introduced into the carbon-based hydrogen storage cavity, and the airtightness is tested by a helium mass spectrometer leak detector. After passing the test, the vacuum is broken and the finished product is taken out.

[0019] As a preferred embodiment of the present invention, in step S4, the synergistic effect of multi-band phased microwave replaces the two core processes of high-temperature heating (≥900℃) and high-pressure gas densification (100~200MPa) in the traditional hot isostatic pressing (HIP) process, achieving equivalent or even better atomic-level densification and bonding effects under low-temperature (≤90℃) and pressureless (vacuum negative pressure environment) conditions.

[0020] As a preferred embodiment of the present invention, for 3D printed porous blanks of titanium alloys, mold steels, and nickel-based alloys, the finished workpiece has a density ≥99.9% and tensile and impact mechanical properties equivalent to forged metal parts. This process can be used alone to completely omit the hot isostatic pressing process; it can also be used as a pretreatment process to reduce the subsequent hot isostatic pressing processing pressure by 60% and the processing temperature by more than 400°C, shortening the hot isostatic pressing processing cycle by 70%.

[0021] As a preferred embodiment of the present invention, for thin-walled three-dimensional cage carbon hydrogen storage components with a thickness of 0.05mm to 5mm, the temperature of the entire process does not exceed 90℃, the micropores inside the carbon base do not collapse or deform, and the residual hydrogen storage rate in the cavity is ≥99%; there is no solder or foreign medium involved at the workpiece joint interface, the interface conductivity is continuous, and the helium leak detection rate of the finished product is ≤1×10⁻⁶. -9 Pa·m 3 / s.

[0022] As a preferred embodiment of the present invention, the multi-channel phase-shifting synchronous main control module has three preset standardized production modes, namely standard dense mode, low-stress slow welding mode, and large-area phase control compensation mode; it can automatically match the electromagnetic wave frequency band power, phase timing, and total processing time according to the workpiece material, wall thickness, and pore distribution, and is suitable for batch production of various specifications of workpieces such as small microcavities, ultra-thin diaphragms, and meter-level whole plates.

[0023] Compared with the prior art, the beneficial effects of the present invention are: 1. One machine serves two purposes, and can completely replace or work in conjunction with hot isostatic pressing. The same set of equipment is compatible with two core scenarios: metal additive billet densification and carbon-based hydrogen storage cavity sealing. It can achieve the same forming effect as hot isostatic pressing when used independently, greatly reducing equipment procurement investment. When used as a pretreatment component in hot isostatic pressing, it can significantly reduce the high temperature and high pressure conditions of hot isostatic pressing, extend the service life of high pressure cavities, and reduce energy consumption and processing time per piece.

[0024] 2. Entire-area internal extrusion pressure, eliminating processing dead zones. By relying on multi-phase superimposed electromagnetic waves to generate isostatic compressive force in every micro-pore of the workpiece, the pressure acts from the inside out; unlike thermal isostatic pressing with external gas pressure, there is no pressure attenuation in irregularly shaped inner cavities and thick core parts, completely solving the problem of loose core in traditional processes.

[0025] 3. Low-temperature processing without mechanical extrusion preserves the original structure of the material. The entire process has a maximum processing temperature of only 90℃, requiring no rigid molds or high-pressure gas extrusion; metal workpieces will not experience high-temperature grain coarsening; the micropores of the carbon-based hydrogen storage plate are completely preserved, with no hydrogen escape; ultra-thin thin-walled parts will not be subjected to pressure buckling deformation, and the dimensional deviation of the workpiece before and after processing is minimal.

[0026] 4. Multi-band phased array architecture significantly improves processing efficiency. Long and short wave segment matching of full-scale pores, multi-channel independent phase control to avoid electromagnetic wave surface shielding, can penetrate deep into the interior of three-dimensional porous workpieces; dynamic frequency modulation and phase control of pores to continuously maintain extrusion pressure; the complete processing cycle of a single piece is only tens of minutes, and the mass production capacity is 7 to 14 times that of large hot isostatic pressing equipment, and it is suitable for automated loading and unloading continuous production lines.

[0027] 5. Solder-free body bonding, resulting in excellent finished product performance. No solder, adhesive or other dissimilar media are added during the processing; the density and mechanical properties of the metal workpiece are comparable to forgings; the lattice of the carbon-based workpiece joint interface is continuously interconnected, and the airtightness level is better than that of traditional hot isostatic pressing products. There are no delamination or leakage problems after long-term high and low temperature cycling.

[0028] 6. Significant cost advantages in industrialized mass production Under the same processing specifications, the purchase investment of this equipment is only 15% to 25% of that of large hot isostatic pressing equipment; the energy consumption of single-piece processing is only 8% to 12% of that of hot isostatic pressing; the automated timing control reduces manual intervention, and the yield rate of batch production is stable at over 98.5%, making it valuable for large-scale promotion. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the system structure of the present invention; Figure 2 This is a schematic diagram of the process structure of the present invention. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1 (Forging and densification of titanium alloy 3D printed billet) See Figure 1 , 2 This embodiment focuses on the forging densification process of porous titanium alloy 3D printed by selective laser melting (SLM) to verify the baseline process stability and reliability of the equipment in the field of metal additive manufacturing post-processing.

[0032] Workpiece specifications: 150mm×150mm×2mm SLM titanium alloy (TC4) printing plate is selected, with internal pore distribution of 0.5~10μm and original density of 92.3%.

[0033] Pretreatment: Sandblasting to remove surface powder, acid pickling to remove oxide layer, and dust-free drying.

[0034] Clamping: Three-dimensional adaptive suspended tooling with hollow support, only applying a horizontal limiting force of ≤0.05N, with no clamping load in the vertical direction, and a dial indicator to monitor and display the workpiece thickness deformation <1μm throughout the entire processing cycle.

[0035] Vacuum parameters: stabilized to 1×10⁻⁶ in 4.5 minutes -4 Hold pressure at 1000 Pa for 5 minutes.

[0036] Processing mode: Standard densification mode, total processing time 22 minutes, temperature controlled at 55℃ throughout. Long-wave microwave full-domain pre-compression stage: Multiple long-wave microwave channels are activated (center frequency 3.5GHz), the main controller retrieves the preset optimal phase superposition configuration, and the power density is 1.5W / cm². 2 The effect lasts for 8 minutes, shrinking large-sized interconnected pores; Millimeter-wave micro-orifice leveling stage: Maintaining long-wavelength substrate output (power reduced to 0.5W / cm²) 2 Simultaneously activate the shortwave millimeter-wave array (center frequency 30GHz), adjust the phase of each channel, and achieve a power density of 1.0W / cm². 2 It lasts for 7 minutes; Long-wave and short-wave co-existing atomic close-knit stage: Long-wave and millimeter-wave continuous phase superposition output, power density increased to 2.0W / cm². 2 and 1.2W / cm 2The continuous resonance effect lasts for 7 minutes; the ultrasonic in-situ porosity detection sensor provides real-time feedback of porosity data, and the main control automatically fine-tunes the frequency and phase to match the continuous pore shrinkage condition.

[0037] Post-processing: Turn off the millimeter wave source, leave only the low-power long-wave substrate standing wave to act continuously for 3 minutes to release residual stress; cool down to room temperature with water cooling circulation, and then allow to solidify in a vacuum for 20 minutes.

[0038] Test results: Density: Archimedes displacement test, final density 99.92%, metallographic structure without interconnected pores; Mechanical properties: Tensile strength and elongation after fracture are consistent with forgings of the same material, so the hot isostatic pressing process can be omitted directly; Microstructure: Scanning electron microscopy (SEM) observation showed that the typical interlayer non-fusion defects and pores in the original printed state were completely eliminated, and there was no abnormal coarsening of the grains.

[0039] This embodiment fully verifies that the present invention achieves forging-grade densification on a metal 3D printed titanium alloy blank in a low-temperature (55°C) and pressureless manner, which can completely replace the traditional hot isostatic pressing process.

[0040] Example 2 (Sealing process of 0.08mm ultrathin three-dimensional cage carbon hydrogen storage diaphragm) See Figure 1 , 2 This embodiment specifically employs a low-stress slow welding mode for ultra-thin carbon-based diaphragm plates that are extremely thin (≤0.1mm), have very low rigidity, and cannot be processed by hot isostatic pressing.

[0041] Workpiece specifications: 80mm×80mm, 0.08mm thick carbon-based diaphragm, internal hydrogen storage micropores with a diameter of 0.3~1.5μm, and an original resonant frequency design value of 2.860MHz.

[0042] Pretreatment: Ultrasonic cleaning with ultrapure water, flatness calibration to 0.3μm.

[0043] Clamping: Multi-point flexible limiting fixtures with a vertical constraint force of <0.02N (near-zero force constraint) and a CCD vision alignment system to ensure that the alignment accuracy of the upper and lower plates is ≤10μm. Such ultra-thin workpieces cannot be installed in HIP equipment at all—the high-pressure gas of 100-200MPa will directly cause the diaphragm to buckle plastically.

[0044] Vacuum parameters: Target vacuum level increased to 3.0 × 10⁻⁶ -5 Pa, the suction time is about 6 minutes.

[0045] Processing mode: Low-stress slow welding mode, maximum temperature throughout the process: 38℃ Low frequency band (corresponding to long-wave microwave): The center frequency is lowered to 28GHz (to avoid coupling with the inherent frequency of the thin plate), and intermittent output is used (5 seconds of output, 2 seconds of interval) to suppress energy accumulation; High-frequency band (corresponding to millimeter wave): finely tuned to 32GHz, power density is strictly limited, and atomic tightness adopts a "gentle creep" mode.

[0046] Test results: Air tightness: Helium mass spectrometer leak rate 4.5 × 10⁻⁶ -10 Pa·m 3 / s, no collapse of micropores; Hydrogen storage retention: 99.2% hydrogen retention rate in the chamber; Resonant frequency: 2.856MHz, with a deviation of only 0.14% (<0.5‰), which fully meets the frequency stability index of high-precision quantum resonant devices—a precision that HIP technology cannot achieve at all (even ignoring high voltage collapse, the high temperature treatment of HIP will lead to lattice relaxation and irreversible frequency drift).

[0047] This embodiment demonstrates that the present invention achieves low-temperature, pressureless atomic-level bonding on ultrathin-walled (0.08 mm) carbon-based components, which is completely impossible for HIP, and has irreplaceable technical advantages in this sub-field.

[0048] Example 3 (Batch processing of meter-scale large-area carbon fiber cage plates) This embodiment focuses on the integrated, seamless, and dense sealing of a 1200mm×800mm ultra-large carbon fiber cage plate. It primarily verifies the electromagnetic field uniformity and continuous batch production capability of large-area workpieces, while also conducting a systematic comparison with large-scale HIP equipment in terms of capacity and cost.

[0049] Workpiece specifications: 3.5mm thick large-format carbon cage cover plate, used for encapsulation of large superconducting hydrogen storage tanks.

[0050] If a large-scale HIP equipment of the same specifications is used, the investment for a single unit is 30 to 50 million yuan, and the furnace preparation time is as long as 2 to 4 hours; the investment for the equipment of this invention is about 5 million to 8 million yuan, which is only 15% to 25% of that of HIP.

[0051] Vacuum and thermal field: Equipped with a high-speed molecular pump array, stabilizing to 1×10⁻⁶ in 8 minutes. -4 Pa; 32 distributed temperature measurement points were set up, and the actual measured temperature difference in different areas of the whole plate was ≤±3.0℃, with a target temperature of 65℃.

[0052] Processing mode: Large-area phase control compensation mode, total processing time 38 minutes: Long-wave microwaves employ linear frequency conversion scanning from 20GHz to 40GHz (scanning period 2s) to avoid uneven adsorption forces between the center and edges caused by large-area standing wave fields; phased array phase adjustment technology is introduced, and the effective field strength in the edge region is automatically compensated to increase by 5% to 8% compared to the center, eliminating micro-gap caused by large-area edge effects.

[0053] Mass production data: The total cycle time per unit is 50 minutes, and the equipment can complete 28 large-area full-board packages in 24 hours of continuous operation. The total cycle time for a single HIP unit of the same specifications is approximately 6-10 hours, and only 2-4 units can be processed in 24 hours. The single-machine capacity of this invention is 7-14 times that of HIP, and the energy consumption per unit is approximately 8%-12% of that of HIP.

[0054] Yield statistics: Helium mass spectrometry was performed on each finished product at 25 measurement points using a 5×5 grid. A total of 700 measurement points were collected from 28 finished products, and all yields were significantly better than the acceptable threshold (≤1×10⁻⁶). -9 Pa·m 3 / s). The average batch yield is 98.5%, while the industry average yield is only 70% to 85% when HIP processes large-area carbon-based boards due to deformation, warping, and local micro-cracks caused by high temperature and pressure.

[0055] This embodiment systematically demonstrates the feasibility of the present invention for a complete replacement of large-scale HIP equipment from four dimensions: equipment investment, single-piece cycle, unit energy consumption, and batch yield.

[0056] Example 4 (Pre-treatment + hot isostatic pressing composite processing) This embodiment verifies the application mode of the present invention in combination with hot isostatic pressing.

[0057] Workpiece: A 3D printed part with a complex internal cavity made of nickel-based alloy (Inconel 718) was selected. The original density was 88.5%. There are a lot of interconnected pores inside. Conventional HIP can only achieve a core density of about 96% due to the complexity of the internal cavity and the severe pressure attenuation.

[0058] First, the internal densification pretreatment (standard densification mode, total duration 20 minutes, temperature controlled at 60°C throughout) is completed using the equipment of this invention. After the pretreatment, the density of the workpiece is increased to 96.8%, and the large-size interconnected pores are basically closed.

[0059] Then it is sent to a small hot isostatic pressing equipment for precision processing: The processing temperature was reduced from the conventional 1100℃ to 700℃ (a decrease of 400℃). The processing pressure was reduced from the conventional 150MPa to 60MPa (a reduction of 60%). The processing time has been reduced from the usual 4 hours to about 70 minutes (a reduction of 72%).

[0060] Composite processing results: The finished product has a density of 99.95%, with no core porosity defects (the core porosity problem caused by pressure decay in conventional HIP is completely solved), the high-pressure chamber loss is greatly reduced, and the overall processing cost is reduced by about 55%.

[0061] This embodiment fully demonstrates that the present invention can independently and completely replace hot isostatic pressing, or it can be used as a pretreatment process in combination with hot isostatic pressing, which can significantly reduce the operating load of hot isostatic pressing equipment, shorten the processing cycle, and improve the quality of finished products, providing a flexible technical path for industrial production scenarios of different scales and requirements.

[0062] Summary of Implementation Examples Based on the detailed process data and characterization results of the above four typical embodiments (dense titanium alloy 3D printing, ultra-thin carbon diaphragm sealing, batch processing of large-area carbon whole plates, and HIP composite collaborative processing): First, the equipment boasts exceptional compatibility, covering both metal and carbon-based processes. Example 1 (metal 3D printing for densification) and Examples 2 and 3 (carbon-based hydrogen storage sealing) were both processed on the same equipment, proving that the "one machine, two uses" technical positioning of this invention is fully valid.

[0063] Second, the intrinsic Casimir densification mechanism is consistently applied throughout. Whether it's a metal billet or a carbon-based workpiece, the three-stage synergistic logic of long-wave microwave (macroscopic pre-compression) → millimeter-wave (micropore leveling) → long-short-wave synergy (atomic compaction) remains unified. In Example 1, the density of the titanium alloy increased from 92.3% to 99.92%, and in Example 2, the helium leak detection rate of the carbon diaphragm reached 4.5 × 10⁻⁶. -10 Pa·m 3 / s, all of which demonstrate the global effectiveness of the intrinsic extrusive force.

[0064] Third, it can completely replace hot isostatic pressing. Both Example 1 (titanium alloy) and Example 3 (large area carbon plate) met or exceeded industry standards without using HIP, and were significantly better than HIP in four dimensions: equipment investment, production cycle time, unit energy consumption, and batch yield.

[0065] Fourth, it can flexibly coordinate with hot isostatic pressing (HIP) composite processing. Example 4 demonstrates that this invention, as a pre-treatment process, can reduce HIP temperature by more than 400°C, reduce pressure by 60%, and shorten the cycle by 70%, providing a low-threshold transition solution for upgrading traditional HIP production lines.

[0066] Fifth, it is irreplaceable in the field of ultra-thin walls, where HIP is completely ineffective. In Example 2, the 0.08mm ultra-thin diaphragm achieves atomic-level sealing under pressureless and low-temperature conditions with a resonant frequency deviation of <0.5‰, which is something that HIP technology cannot achieve at all.

[0067] In summary, through four typical embodiments covering extreme scenarios, this invention comprehensively and three-dimensionally demonstrates the scientific nature, universality, advanced technology, and high industrial maturity of the multi-phase, multi-band vacuum intrinsic Casimir densification equipment and integrated molding process, from metal additive manufacturing densification to carbon-based microcavity sealing, and from independent replacement of HIP to collaborative composite processing. It provides a disruptive HIP replacement and upgrade technology solution for metal additive manufacturing post-processing and carbon-based superconducting energy storage device packaging.

[0068] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A multi-phase, multi-band vacuum intrinsic Casimir densification device, characterized in that: It includes a high-vacuum global resonant cavity module, a multi-band phased microwave excitation array module, a three-dimensional adaptive suspension tooling module, a real-time vacuum degree voltage stabilization and detection module, a multi-channel phase-shifting synchronization main control module, a low-temperature closed-loop temperature control module, and a stress-relieving airtightness detection module; The three-dimensional adaptive suspension fixture module and the multi-band phased microwave excitation array module are both built into the high-vacuum global resonant cavity module; the real-time vacuum level voltage stabilization and detection module and the low-temperature closed-loop temperature control module are connected to the high-vacuum global resonant cavity module through vacuum pipelines and water-cooled circulation pipelines, respectively; the multi-channel phase-shifting synchronization main control module is electrically connected to all other modules through cables to realize integrated closed-loop linkage control of power, frequency, phase, vacuum, and temperature timing. The multi-band phased microwave excitation array adopts a multi-layer three-dimensional surround arrangement structure, including multiple independent radiation units. Each radiation unit is equipped with an independent radio frequency power output unit and a 0° to 360° continuously adjustable phase shifter. The excitation array is divided into two band units: long-wave microwave excitation group and short-wave millimeter-wave excitation group. Long-wave microwaves have strong penetration capabilities and are used to eliminate large-sized interconnected pores inside the workpiece. Short-wave millimeter waves are matched with submicron micro-pore structures to amplify the extrusion pressure inside the pores. Multiple electromagnetic waves are superimposed in phase to form a uniform internal Casimir extrusion pressure inside the massive micro-pores of the workpiece. The three-dimensional adaptive suspension fixture adopts a carbon fiber hollow suspension flexible structure, which only limits the horizontal movement of the workpiece and does not apply vertical mechanical clamping load throughout the process. It can be adapted to any irregularly shaped hollow 3D printed workpiece and ultra-thin carbon-based sheet. The low-temperature closed-loop temperature control module covers all temperature measurement points of the cavity and workpiece, with a closed-loop temperature control range of 25℃~90℃, and there are no local high-temperature heat accumulation areas on the workpiece. The entire equipment has no high-pressure bearing cavity structure and does not require external high-pressure gas pressure. It achieves full-domain isostatic densification by relying on the internal pressure difference in the pores. The equipment is used to replace hot isostatic pressing equipment to achieve forging densification of porous metal 3D printed blanks, three-dimensional cage carbon closed-pore cavities, and thermal damage-free atomic-level solid-state diffusion bonding of thin-walled carbon-based resonant plates.

2. The multi-phase, multi-band vacuum intrinsic Casimir densification device according to claim 1, characterized in that: The long-wave microwave operating frequency band is 2GHz to 6GHz, and the short-wave millimeter-wave operating frequency band is 26GHz to 40GHz; the phase of each radiation unit is independently adjustable, and the main control module has multiple preset phase superposition configurations built in, which can avoid electromagnetic wave interference and cancellation on the workpiece surface and ensure that electromagnetic waves continuously penetrate into the internal pore network of the workpiece. By actively controlling the phase of each electromagnetic wave, the difference in radiation energy inside and outside the pore is changed, and the magnitude of the internal Casimir extrusion pressure is dynamically adjusted.

3. The multi-phase, multi-band vacuum internal Casimir densification device according to claim 1, characterized in that: The high-vacuum global resonant cavity can stably maintain 1×10 -3 Pa ~ 5 × 10 -5 The cavity is equipped with a multi-stage molecular pump assembly, which can stabilize the cavity vacuum to 1×10⁻⁶ Pa within 5 minutes. -4 Pa; The real-time vacuum level stabilization and detection module has a built-in vacuum gauge and flow stabilizing valve. It collects the vacuum value in the cavity in real time, automatically adjusts the pumping speed of the pump group to stabilize the vacuum environment, and isolates air, water vapor and impurities from entering the workpiece pores to avoid the formation of an interface oxide layer.

4. The multi-phase, multi-band vacuum intrinsic Casimir densification device according to claim 1, characterized in that: The multi-channel phase-shifting synchronization main control module has a built-in porosity dynamic feedback timing control unit; the cavity is equipped with a spectrum acquisition sensor and an ultrasonic in-situ porosity detection sensor; during the densification process of the workpiece, the porosity size continues to shrink, the sensor provides real-time feedback of porosity change data, and the main control automatically and synchronously adjusts the frequency, phase and output power of each electromagnetic wave to continuously match the porosity resonance condition and avoid the extrusion pressure from rapidly attenuating and failing as the porosity shrinks.

5. The multi-phase, multi-band vacuum intrinsic Casimir densification device according to claim 1, characterized in that: The low-temperature closed-loop temperature control module includes a full-area water-cooled bushing and distributed multi-point temperature sensors, with temperature measurement points covering the upper surface of the workpiece, the inner cavity, and the side wall of the cavity. The system adopts a slow heating and slow cooling closed-loop logic, and the maximum temperature of the entire process does not exceed 90°C, which can avoid high-temperature coarsening of metal grains, high-temperature collapse of carbon-based micropores, and heat escape of hydrogen storage medium.

6. The multi-phase, multi-band vacuum intrinsic Casimir densification device according to claim 1, characterized in that: The stress-relieving airtightness testing module integrates a global weak reverse demagnetizing coil and a helium mass spectrometer leak detector. After the workpiece is densified, the equipment outputs a low-frequency weak standing wave to release residual electromagnetic field stress at the interface and suppress the generation of microcracks. The helium mass spectrometer leak detector detects the leakage rate of the cavity seal, and the qualified threshold is a leakage rate ≤ 1×10⁻⁶. -9 Pa·m 3 / s.

7. The multi-phase, multi-band vacuum internal Casimir densification device according to claim 1, characterized in that: The three-dimensional adaptive suspension fixture has two switchable working modes: 3D metal porous billet full-domain suspension support mode and ultra-thin carbon plate multi-point flexible limiting mode; the fixture exerts a vertical constraint force of less than 0.1N on the workpiece, and there is no workpiece deformation caused by rigid extrusion throughout the process.

8. A multi-phase, multi-band vacuum intrinsic Casimir molding process, characterized in that, The process is carried out using the multi-phase, multi-band vacuum internal Casimir densification equipment as described in any one of claims 1 to 7. The process is divided into two main branches: metal 3D printing forging densification process and three-dimensional cage carbon hydrogen storage cavity sealing and encapsulation process, both of which uniformly include the following processing steps: S1. Ultra-clean pretreatment of workpieces: Remove surface powder and oxide scale from metal 3D printed workpieces; three-dimensional cage carbon plates and hydrogen storage accessories are ultrasonically cleaned with ultrapure water, dried in a dust-free environment, and the flatness of the joint surface is ≤0.5μm after grinding and calibration. S2, Three-dimensional levitation flexible clamping: The workpiece to be processed is placed in the three-dimensional adaptive levitation fixture to complete precise alignment. The fixture only performs horizontal limit and does not apply vertical mechanical clamping load throughout the process. S3. Staged Vacuum Evacuation and Pressure Stabilization of the Chamber: The sealed chamber is activated by a multi-stage molecular pump group to gradually evacuate the internal air and stabilize the chamber vacuum to 1×10⁻⁶. -4 Pa, hold pressure and stand for 5 minutes to fully expel residual gas from workpiece pores and joint interlayer; S4. Multi-phase, multi-band intrinsic Casimir staged densification processing, with low-temperature closed-loop temperature control throughout the process (25℃~90℃): S41, Long-wave microwave full-domain pre-compression stage: The main control retrieves the preset optimal phase superposition configuration, and all long-wave microwave radiation units are turned on synchronously to construct a macroscopic uniform internal extrusion pressure and shrink the large-size interconnected pores inside the workpiece. S42, Millimeter-wave micropore leveling stage: Maintain the output of long-wave microwave low-power substrate, simultaneously turn on the short-wave millimeter-wave array, adjust the phase of each electromagnetic wave to amplify the internal squeezing pressure of the micropores, the micron-level gaps gradually collapse, and the workpiece particle interfaces approach each other to the molecular interaction range. S43, Long and short wave coordinated atomic sealing stage: Long wave and millimeter wave are continuously superimposed in phase, and the porosity of the entire workpiece shrinks synchronously; the density of the metal 3D billet reaches the forging standard; carbon atom lattice interlocks at the interface of carbon-based workpieces to form an atomic-level airtight seal; the system monitors porosity in situ by ultrasound, and automatically jumps to the next process after the porosity meets the standard. S5. Weak standing wave relieves residual stress: Turn off all millimeter wave radiation units and keep only the low-power long-wave substrate standing wave for 3 minutes to relieve residual stress at the workpiece interface and inhibit the generation of microcracks. S6. Vacuum low-temperature lattice curing: The cavity maintains a high vacuum environment, and the water cooling circulation cools the workpiece to room temperature at a uniform speed. Vacuum static curing is carried out for 15-30 minutes to stabilize the internal lattice structure of the workpiece. S7. Finished Product Performance Testing and Unloading: The density of metal workpieces is tested by ultrasound and metallography; tracer helium is introduced into the carbon-based hydrogen storage cavity, and the airtightness is tested by a helium mass spectrometer leak detector. After passing the test, the vacuum is broken and the finished product is taken out.

9. The multi-phase, multi-band vacuum intrinsic Casimir molding process according to claim 8, characterized in that: For 3D printing porous blanks of titanium alloys, mold steels, and nickel-based alloys, the finished workpiece has a density of ≥99.9% and tensile and impact mechanical properties equivalent to forged metal parts. This process can be used alone to completely eliminate the hot isostatic pressing process; or it can be used as a pretreatment process to reduce the subsequent hot isostatic pressing pressure by 60% and the processing temperature by more than 400℃, shortening the hot isostatic pressing cycle by 70%.

10. The multi-phase, multi-band vacuum intrinsic Casimir molding process according to claim 8, characterized in that: For thin-walled three-dimensional cage carbon hydrogen storage components with a thickness of 0.05mm to 5mm, the entire process temperature does not exceed 90℃, the internal micropores of the carbon base do not collapse or deform, and the hydrogen residual rate in the cavity is ≥99%; there is no solder or foreign medium involved at the workpiece joint interface, the interface conductivity is continuous, and the helium leak detection rate of the finished product is ≤1×10 -9 Pa·m 3 / s.

11. The multi-phase, multi-band vacuum intrinsic Casimir molding process according to claim 8, characterized in that: The multi-channel phase-shifting synchronous main control module has three preset standardized production modes: standard dense mode, low-stress slow welding mode, and large-area phase control compensation mode. It can automatically match the electromagnetic wave frequency band power, phase timing, and total processing time according to the workpiece material, wall thickness, and pore distribution, and is suitable for the mass production of various specifications of workpieces such as small microcavities, ultra-thin diaphragms, and meter-level whole plates.

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