Block nanometer material based on continuous solid-liquid interface conversion and preparation method and preparation system thereof

Abstract

The invention provides a preparation method of a block nano material based on continuous solid-liquid interface conversion, which comprises the following steps: A) simultaneously regulating and controlling a solid-liquid interface energy barrier of a solid-liquid conversion medium on the surface of a target area through a dynamic magnetic field and an ultrasonic standing wave to obtain a metastable state interface; the solid-liquid conversion medium is a magnetic nanofluid with a core-shell structure; and B) performing interface reaction on the metastable state interface and elements on the surface of the target area to generate a submicron intermetallic compound strengthening phase, thereby obtaining the block nano material. The preparation method provided by the invention is high in structural degree of freedom, supports direct forming on the surface of a curved surface / hollow structure, and can break through the plane limitation of a copper indium needle array. Moreover, zero pollution of an interface can be realized, the magnetic fluid is completely recovered, and the residual quantity is 1t; and 0.1%. Furthermore, the process temperature is reduced to 180 DEG C through ultrasonic-assisted diffusion, and energy consumption can be remarkably reduced and is reduced by 40% compared with the prior art.

Description

Technical Field

[0001] This invention belongs to the field of intelligent material manufacturing technology, specifically relating to a bulk nanomaterial based on continuous solid-liquid interface transition, its preparation method, and preparation system. Background Technology

[0002] In the current field of bulk nanomaterial fabrication, while traditional spray molding technology can achieve continuous material deposition, it suffers from the problem of disordered nanostructure orientation due to uncontrollable droplet solidification behavior. Interface control schemes based on acoustic levitation can achieve micro-region solid-liquid conversion, but are limited by single-point operation modes and cannot be applied on a large scale. Furthermore, photo-controlled solid-liquid conversion technology cannot fabricate large-size components due to limitations in light transmission depth. Existing technologies have failed to resolve the key contradiction between dynamic control of the solid-liquid interface and nano-precision forming of complex three-dimensional structures under large-scale production conditions. This results in defects such as grain coarsening (>200nm) and weakened interlayer bonding in bulk materials, severely restricting their application in precision aerospace components.

[0003] Therefore, providing a method for preparing bulk nanomaterials that can solve the problems of dynamic control of the solid-liquid interface and nano-precision forming of three-dimensional complex structures under large-scale production conditions has become an issue that needs to be addressed. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a bulk nanomaterial based on continuous solid-liquid interface transition, a preparation method thereof, and a preparation system thereof. The preparation method provided by the present invention can solve the problems of dynamic control of solid-liquid interface and nano-precision forming of three-dimensional complex structures under large-scale production conditions.

[0005] This invention provides a method for preparing bulk nanomaterials based on continuous solid-liquid interface transition, comprising:

[0006] A) A metastable interface is obtained by simultaneously modulating the solid-liquid interface energy barrier on the surface of the target region using a dynamic magnetic field and an ultrasonic standing wave with a solid-liquid conversion medium; the solid-liquid conversion medium is a core-shell magnetic nanofluid.

[0007] B) The metastable interface reacts with the elements on the surface of the target region to generate a submicron intermetallic compound reinforcing phase, thus obtaining a bulk nanomaterial.

[0008] Preferably, the core-shell magnetic nanofluid comprises core-shell magnetic nanoparticles;

[0009] The core-shell structured magnetic nanoparticles include a magnetic nanoparticle core and an alloy layer covering the surface of the magnetic nanoparticle core.

[0010] Preferably, the surface of the core-shell magnetic nanoparticles is modified with an oleylamine molecular layer.

[0011] Preferably, the magnetic nanoparticles have a particle size of 10~50 nm and a saturation magnetization of >80 emu / g;

[0012] Preferably, the magnetic nanoparticles are selected from at least one of Fe3O4@Co nanoparticles, Fe3O4 nanoparticles, Co nanoparticles, and Fe nanoparticles;

[0013] The alloy layer has a thickness of 6~10nm and a melting point of 20~60℃;

[0014] Preferably, the alloy layer is selected from at least one of Ga-In-Sn eutectic alloy and Bi-In-Sn alloy.

[0015] Preferably, the dynamic magnetic field includes at least one of a rotating magnetic field, an asymmetric magnetic field, and an oscillating magnetic field.

[0016] Preferably, the frequency of the dynamic magnetic field is 1-100Hz, the intensity is 0.1-0.8T, and the gradient is 30-60T / m.

[0017] Preferably, the frequency of the ultrasonic standing wave is 1-5MHz, and the power density is 20-80W / cm². 2 .

[0018] Preferably, the interface reaction is completed by at least one of laser instantaneous heating and low-temperature reaction methods.

[0019] Preferably, the target region includes at least one of iron, aluminum, and titanium.

[0020] Preferably, the target area is a planar structure or a non-planar structure, and the non-planar structure includes a curved surface structure, a hollow structure, and a three-dimensional mesh structure.

[0021] Preferably, the bulk nanomaterial further includes a reinforcing phase or a second phase material, wherein the reinforcing phase includes at least one of silicon carbide, alumina, silicon nitride, boron nitride, and boron carbide; the second phase material includes at least one of Al-10Si alloy, Sn-based alloy, In-based alloy, pure tin, and pure indium; and the reinforcing phase or the second phase material accounts for 10% to 50% of the volume percentage of the bulk nanomaterial.

[0022] Preferably, the reinforcing phase is sprayed onto the surface of the target region through a coaxial three-channel nozzle and a core-shell structured magnetic nanofluid. The middle layer of the coaxial three-channel nozzle delivers the reinforcing phase, the inner layer delivers the magnetic nanofluid, and the outer layer delivers the protective gas.

[0023] The present invention also provides a bulk nanomaterial prepared by the above preparation method.

[0024] This invention also provides a system for preparing bulk nanomaterials based on continuous solid-liquid interface transition, comprising:

[0025] A multi-physics coupling printhead integrating magnetic coils and piezoelectric transducer arrays;

[0026] Real-time topography monitoring system;

[0027] Adaptive feedback controller.

[0028] Compared with existing technologies, this invention provides a method for preparing bulk nanomaterials based on continuous solid-liquid interface transition, comprising: A) simultaneously modulating the solid-liquid interface energy barrier on the surface of a target region using a solid-liquid transition medium through a dynamic magnetic field and an ultrasonic standing wave to obtain a metastable interface; wherein the solid-liquid transition medium is a core-shell magnetic nanofluid; B) the metastable interface undergoes an interfacial reaction with elements on the surface of the target region to generate a submicron intermetallic compound reinforcing phase, thereby obtaining bulk nanomaterials. The preparation method provided by this invention offers high structural freedom, supporting direct forming on curved / hollowed-out structural surfaces, and can overcome the planar limitations of copper-indium needle arrays. Furthermore, this invention achieves zero interface contamination, complete recovery of the magnetic fluid, and a residual amount of <0.1%. Further, ultrasonic-assisted diffusion lowers the process temperature to 180°C, significantly reducing energy consumption by 40% compared to existing technologies. Detailed Implementation

[0029] This invention provides a method for preparing bulk nanomaterials based on continuous solid-liquid interface transition, comprising:

[0030] A) A metastable interface is obtained by simultaneously modulating the solid-liquid interface energy barrier on the surface of the target region using a dynamic magnetic field and an ultrasonic standing wave with a solid-liquid conversion medium; the solid-liquid conversion medium is a core-shell magnetic nanofluid.

[0031] B) The metastable interface reacts with the elements on the surface of the target region to generate a submicron intermetallic compound reinforcing phase, thus obtaining a bulk nanomaterial.

[0032] The present invention first prepares a solid-liquid conversion medium, wherein the solid-liquid conversion medium is a core-shell structured magnetic nanofluid.

[0033] In this invention, the core-shell magnetic nanofluid includes core-shell magnetic nanoparticles;

[0034] The core-shell structured magnetic nanoparticles include a magnetic nanoparticle core and an alloy layer covering the surface of the magnetic nanoparticle core.

[0035] In this invention, the magnetic nanoparticles must meet four essential conditions: high saturation magnetization, precise nanoscale size, monodispersity, and chemical stability. Preferably, the magnetic nanoparticles have a particle size of 10-50 nm, which can be any value between 10, 15, 20, 25, 30, 35, 40, 45, 50 nm, or 10-50 nm, and a saturation magnetization >80 emu / g.

[0036] Preferably, the magnetic nanoparticles are selected from at least one of Fe3O4@Co nanoparticles, Fe3O4 nanoparticles, Co nanoparticles, and Fe nanoparticles;

[0037] In this invention, the alloy layer material is a functional "active medium" that needs to meet three conditions: ultra-low melting point, high reactivity, and good fluidity. Preferably, the thickness of the alloy layer is 6~10 nm, which can be any value between 6, 7, 8, 9, 10, or 6~10 nm, and the melting point is 20~60℃, which can be any value between 20, 25, 30, 35, 40, 45, 50, 55, 60, or 20~60℃.

[0038] Preferably, the alloy layer is selected from at least one of Ga-In-Sn eutectic alloy and Bi-In-Sn alloy.

[0039] Preferably, the surface of the core-shell magnetic nanoparticles is modified with an oleylamine molecular layer. This can prevent the oxidation of the core-shell magnetic nanoparticles and enhance particle fluidity.

[0040] Metastable interfaces are obtained by simultaneously modulating the solid-liquid interface energy barrier of the solid-liquid conversion medium on the surface of the target region using a dynamic magnetic field and an ultrasonic standing wave.

[0041] The dynamic magnetic field includes at least one of a rotating magnetic field, an asymmetric magnetic field, and an oscillating magnetic field. This dynamic magnetic field can drive the nanofluid to precisely spread onto the surface of the target area, achieving precise positioning and shaping. Specifically, a dynamic magnetic field is used to drive the directional migration of magnetic nanofluid, forming a high-gradient interfacial energy field in the target area, enabling automatic positioning and spreading of the droplets (contact angle controllable range 30°-150°).

[0042] The frequency of the dynamic magnetic field is 1-100Hz, which can be 1, 3, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, or any value between 1-100Hz; the intensity is 0.1-0.8T, which can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or any value between 0.1-0.8T; and the gradient is 30-60T / m, which can be 30, 35, 40, 45, 50, 55, 60, or any value between 30-60T / m.

[0043] The ultrasonic standing wave can reduce the diffusion activation energy and accelerate the interfacial reaction. By using an ultrasonic standing wave array (phase difference 70~105°) to generate a periodic cavitation effect at the solid-liquid interface, the nucleation energy barrier of intermetallic compounds is reduced by 40%, and the diffusion time is shortened to 1 / 5 of that of conventional processes. Conventional processes include thermal diffusion / brazing, which mainly rely on long-term thermal diffusion to achieve interfacial bonding and reaction.

[0044] In this invention, the frequency of the ultrasonic standing wave is 1-5 MHz, and can be any value between 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, or 1-5 MHz, with a power density of 20~80 W / cm². 2 It can be 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, or 20~80 W / cm². 2 Any value between.

[0045] In some specific embodiments of the present invention, while the core-shell structured magnetic nanofluid is being transported to the surface of the target region, a reinforcing phase or a second phase material can also be transported. The reinforcing phase includes at least one of silicon carbide, alumina, silicon nitride, boron nitride, and boron carbide; the second phase material includes at least one of Al-10Si alloy, Sn-based alloy, In-based alloy, pure tin, and pure indium; the reinforcing phase or second phase material accounts for 10% to 50% of the mass of the bulk nanomaterial, and can be any value between 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or 10% to 50%.

[0046] The reinforcing phase is sprayed onto the target area surface via a coaxial three-channel nozzle and a core-shell structured magnetic nanofluid. The coaxial three-channel nozzle sequentially delivers the magnetic nanofluid (carrying phase), the reinforcing phase, and the protective gas from the inside out. That is, the magnetic nanofluid is delivered to the inner layer, the reinforcing phase to the middle layer, and the protective gas to the outer layer.

[0047] A single-step forming of component gradient materials is achieved through a coaxial three-channel nozzle, avoiding the problem of weakened interlayer bonding.

[0048] After obtaining the metastable interface, the metastable interface undergoes an interfacial reaction with the elements on the surface of the target region to generate a submicron intermetallic compound reinforcing phase, thus obtaining a bulk nanomaterial.

[0049] In this invention, the interfacial reaction is accomplished through at least one of laser instantaneous heating and low-temperature reaction methods. The interfacial reaction can induce explosive nucleation, resulting in a grain size of <50 nm.

[0050] In some specific embodiments of the present invention, the instantaneous temperature rise of the micro-area by laser instantaneous heating is ΔT=50℃ (pulse width <1ms).

[0051] In this invention, the target region includes at least one of iron, aluminum, and titanium.

[0052] The target area can be a planar structure or a non-planar structure, and the non-planar structure includes curved surface structure, hollow structure, and three-dimensional mesh structure.

[0053] By utilizing interfacial reactions, a submicron intermetallic compound reinforcing phase is generated, resulting in bulk nanomaterials. The size of the submicron intermetallic compound reinforcing phase ranges from 80 to 150 nm.

[0054] Throughout the entire preparation process described above, the interface morphology was measured in real time using a laser interferometer (accuracy ±0.1 μm). Furthermore, the magnetic field / acoustic field parameters were dynamically adjusted by optimizing them using a reinforcement learning algorithm (response time <5 ms). Since the reinforcement learning algorithm used in this invention dynamically optimizes the process parameters, any reinforcement learning algorithm known to those skilled in the art is applicable.

[0055] The present invention also provides a bulk nanomaterial prepared by the above preparation method.

[0056] This invention also provides a system for preparing bulk nanomaterials based on continuous solid-liquid interface transition, comprising:

[0057] A multi-physics coupling printhead integrating magnetic coils and piezoelectric transducer arrays;

[0058] Real-time topography monitoring system;

[0059] Adaptive feedback controller.

[0060] This invention provides a bulk material additive manufacturing method that achieves precise assembly of nanostructures through dynamic control of solid-liquid interface transition using a magnetoacoustic coupling field. The fabrication method provided by this invention offers high structural freedom, supporting direct forming on curved / hollowed-out surfaces, and overcoming the planar limitations of copper-indium needle arrays. Furthermore, this invention achieves zero interface contamination, complete recovery of magnetic fluids, and a residual amount of <0.1%. Moreover, ultrasonic-assisted diffusion lowers the process temperature to 180°C, significantly reducing energy consumption by 40% compared to existing technologies.

[0061] To further understand the present invention, the following embodiments illustrate the bulk nanomaterials based on continuous solid-liquid interface transition, their preparation methods, and preparation systems provided by the present invention. The scope of protection of the present invention is not limited by the following embodiments.

[0062] Example 1 - Preparation of curved surface structure nano-reinforced aluminum alloy components

[0063] First, a core-shell structured magnetic nanofluid was prepared: Fe3O4@Co nanoparticles (particle size 25±3nm) were dispersed in a molten Ga-In-Sn eutectic alloy (component ratio 62.5:21.5:16 wt%), and after surface modification with oleylamine, a stable suspension (solid content 20 vol%) was formed, thus obtaining the magnetic nanofluid.

[0064] Synchronous injection is achieved through a coaxial three-channel nozzle: the inner layer is injected with magnetic nanofluid, the middle layer delivers 40nm SiC nanoparticles (the mass fraction of silicon carbide in the final prepared curved component is 10%), and the outer layer is protected with argon gas (flow rate 15L / min).

[0065] A 0.6T rotating magnetic field (gradient 40T / m) was applied above a curved aluminum alloy substrate (curvature radius 5mm) to drive the precise spreading of nanofluids to form a 50μm thick liquid film; simultaneously, a 128-element phased-array ultrasonic array (3.2MHz, sound pressure 3.5MPa, power density 45W / cm²) was activated. 2 The cavitation effect induced at the solid-liquid interface increases the diffusion rate of Al atoms in aluminum alloys by 8 times.

[0066] Instantaneous heating with a micro-region pulsed laser (peak temperature 230℃, duration 0.8ms) triggers an explosive nucleation reaction to generate an Al3Ga strengthening phase (average size 120nm). The entire process involves real-time monitoring of the interface morphology using a laser interferometer, and dynamic adjustment of the magnetic field phase angle (accuracy ±0.5°) based on a reinforcement learning algorithm. Ultimately, a curved component with a grain size of 68±5nm and a density of 99.2% is obtained, representing a grain refinement rate of 300% compared to traditional spray forming processes.

[0067] Comparative Example 1 - Traditional Spray Molding Process

[0068] 1. Raw materials and equipment

[0069] Raw material: Aluminum-based alloy ingots with the same composition as in Example 1. (Al-10Si-Mg aluminum alloy ingot)

[0070] Equipment: Gas atomization jet molding system, including melting furnace, insulated crucible, gas atomizer, deposition substrate and its moving device.

[0071] 2. Specific steps

[0072] (1) Smelting and refining

[0073] The aluminum-based alloy ingot is heated to 750°C in a melting furnace (based on the liquidus temperature of approximately 577°C for Al-10Si-Mg alloy, with a superheat of approximately 173°C) and held at that temperature to ensure complete melting and homogeneous composition.

[0074] The melt is degassed and refined to remove hydrogen and inclusions.

[0075] (2) Gas atomization

[0076] The refined pure melt is transferred into a heat-insulating crucible and flows out through a guide tube.

[0077] Below the guide tube, a high-pressure (usually 3 MPa) inert gas (argon) is introduced to break the continuous flow of molten metal into droplets with a particle size of 50-200 μm.

[0078] This process does not add any nano-reinforcing phases (such as SiC particles).

[0079] (3) Ejection and deposition

[0080] The atomized droplets are sprayed onto the pre-placed deposition substrate by a high-speed airflow.

[0081] The substrate is typically planar and can be moved in two dimensions to scan and form a deposit of a specific shape.

[0082] After the molten droplet impacts the substrate, it flattens, solidifies, and accumulates. Its solidification depends entirely on the supercooling of the droplet itself and the heat exchange with the substrate / deposited layer, with a cooling rate of approximately 5000 K / s.

[0083] (4) Sediment formation

[0084] By continuously spraying and moving the substrate, layer by layer deposition is carried out to finally form a bulk deposition billet.

[0085] The deposition process was not interfered with or regulated by any external physical fields (such as rotating magnetic fields or ultrasonic standing waves).

[0086] (5) Follow-up processing

[0087] After deposition, subsequent densification treatments such as hot isostatic pressing or hot extrusion are usually required to eliminate the inherent porosity (porosity is usually 2-10%) inside the deposited billet.

[0088] Table 1 Comparison of processes in Example 1 and Comparative Example 1

[0089]

[0090] Example 2 - Manufacturing of Multi-Material Gradient Composite Armor Plates

[0091] 1. The preparation of magnetic nanofluids (Fe3O4@Ga-In-Sn) usually involves two core steps: the synthesis of magnetic nanoparticles and their dispersion and coating in low-melting-point liquid metal.

[0092] ① Preparation of nano Fe3O4 particles (coprecipitation method):

[0093] Reactants: An aqueous solution of FeCl2•4H2O and FeCl3•6H2O, wherein Fe... 3+ / Fe 2+ The molar ratio is precisely controlled at 1.75:1.

[0094] Reaction temperature: The reaction is carried out in a constant temperature water bath at 80°C to balance the reaction rate and particle uniformity.

[0095] pH control: Add 25% ammonia solution dropwise while stirring vigorously to adjust and maintain the pH of the solution at 11.

[0096] Dispersant: Add polyethylene glycol (PEG-6000) with a molecular weight of 6000, at a rate of 2% of the total mass of iron salts.

[0097] Reaction time: After the addition is complete, continue stirring at a constant temperature for 60 minutes.

[0098] Subsequent processing: After the reaction is complete, the precipitate is washed alternately with deionized water and ethanol until neutral, and then dried in a vacuum drying oven at 60°C for 12 hours to obtain Fe3O4 nanoparticles with uniform particle size and good dispersibility.

[0099] ② Coating with Ga-In-Sn eutectic alloy shell:

[0100] The prepared Fe3O4 nanoparticles were dispersed in a Ga-In-Sn eutectic alloy (component ratio of 62.5 wt%:21.5 wt%:16 wt%, melting point of about 10 °C) to obtain a magnetic nanofluid (Fe3O4@Ga-In-Sn).

[0101] 2. Synchronous injection via coaxial three-channel nozzle: In an inert atmosphere glove box (O2 < 0.1 ppm), magnetic nanofluid (Fe3O4@Ga-In-Sn) and WC-Co ceramic powder (80 nm particle size) are synchronously injected via a coaxial three-channel nozzle and loaded into a multi-bin feeding system in proportion. The inner layer is injected with magnetic nanofluid, the middle layer is conveyed with 40 nm WC-Co ceramic powder, and the outer layer is protected by argon gas (flow rate 15 L / min).

[0102] The magnetic-acoustic co-fabrication platform is activated: the substrate (low-carbon steel (Q235)) is preheated to 150°C, and the WC-Co component is driven to transition from 20 vol% to 50 vol% (this volume percentage is the volume percentage of the WC-Co component in the armor plate in the thickness direction) at an increasing rate of 1 vol% / mm through an asymmetric magnetic field (0.4T strong field region / 0.1T weak field region). Simultaneously, 2.8MHz ultrasound (power density 60W / cm²) is applied to promote ceramic / metal interface diffusion and eliminate interlayer stress concentration.

[0103] Introducing a pulsed thermal field (heating rate 10) in the critical transition region 4 (Temperature ℃ / s, peak temperature 1250℃, duration 2ms), induces in-situ generation of (Fe,Co)7W6 intermetallic compounds (size 90-150nm).

[0104] After confirming the phase composition using an online XRD analyzer, the zero-residue recovery system was activated: a reverse magnetic field (intensity 0.3T) was generated using a Helmholtz coil to capture free magnetic particles, achieving a 99.6% recovery rate. The final product was a 300×300×20mm sample. 3 The gradient armor plate (20mm thick) has an interfacial shear strength of 452MPa (170% higher than that of the lamination process). The armor plate exhibits a continuous and smooth distribution along its thickness, and the volume fraction of the WC-Co ceramic reinforcing phase transitions continuously from the projectile-facing surface (20 vol%) to the projectile-repellent surface (50 vol%) along the thickness direction.

[0105] Comparative Example 2 - Lamination Process

[0106] 1. Raw materials and equipment

[0107] raw material:

[0108] Reinforcing phase: WC-Co ceramic powder (particle size 80nm).

[0109] Matrix material: the same metal matrix powder (or foil) as in Example 2.

[0110] Adhesive: Polymer adhesive (epoxy resin system).

[0111] Equipment: mixing equipment, stacking molds, hot press (or vacuum hot press), drying oven.

[0112] 2. Preparation process

[0113] (1) Raw material preparation

[0114] WC-Co powder, metal matrix powder and organic binder (epoxy resin) are uniformly mixed to form a slurry or pressed into a sheet.

[0115] (2) Layering and powdering

[0116] In the mold, mixtures with different WC-Co contents are laid layer by layer according to the designed gradient composition. Starting from the first layer (20 vol% WC-Co), the WC-Co content is increased layer by layer until the last layer (50 vol%).

[0117] (3) Cold pressing and shaping

[0118] Apply a low pressure (~50 MPa) at room temperature.

[0119] Phase 1: Warm-up

[0120] Under a protective atmosphere, the preform is heated to above the binder melting temperature (approximately 140°C for epoxy resin systems), at a pressure of 4 MPa, and held at that temperature for 34 minutes.

[0121] Phase Two: Hot Pressing

[0122] When the resin is close to gel (judged by the stringing method), apply full pressure (9 MPa) and heat to the curing temperature (approximately 170°C for epoxy resin). The heat and pressure holding time is calculated based on the board thickness (≥4 min / mm).

[0123] Phase 3: Cooling

[0124] Cool the water to below 50°C while maintaining full pressure, then depressurize.

[0125] (4) Demolding and post-processing

[0126] Remove the laminated preform from the mold. For complete curing and to reduce internal stress, post-treatment in a 120°C oven for 48 hours may be necessary.

[0127] Table 2 Comparison of processes in Example 2 and Comparative Example 2

[0128]

[0129] Example 3 - Integrated molding of microchannel heat sink

[0130] 1. Preparation of magnetic nanofluids:

[0131] Co nanoparticles were dispersed in a Ga-In-Sn eutectic alloy (component ratio of 62.5 wt%:21.5 wt%:16 wt%, melting point of about 10 °C) to obtain a magnetic nanofluid (Co@Ga-In-Sn).

[0132] 2. Al-10Si matrix alloy and magnetic nanofluid (Co@Ga-In-Sn) were selected as raw materials. Molten droplets of matrix alloy (temperature 600℃) and magnetic nanofluid were co-sprayed onto a pre-placed micro-bump template at a volume ratio of 7:3 through an electromagnetic focusing nozzle (orifice diameter 100μm).

[0133] This pre-formed microbump template is a key mold and support substrate used to define the negative shape structure of the microchannel array. Its specific structure and features are as follows:

[0134] Substrate material: The main body of the template is made of high thermal conductivity oxygen-free copper to ensure rapid heat dissipation during the deposition process and maintain the instantaneous solidification characteristics of the interface.

[0135] Core structure - Microbump array:

[0136] A periodically arranged array of trapezoidal prism-shaped microbumps is fabricated on the surface of a copper substrate using a precision micro-electrolytic processing technique.

[0137] Individual microbump size:

[0138] Top edge width: 180 µm

[0139] Bottom width: 220 µm

[0140] Bump height: 20 µm

[0141] The angle between the side of the protrusion and the substrate is 80° (tilt angle).

[0142] Array layout parameters:

[0143] The micro-bump array is arranged at equal intervals along two mutually perpendicular directions.

[0144] The center-to-center distance between adjacent convex points (i.e., the pitch of the array) is 400 µm.

[0145] Thus, an initial groove with a width of 180 µm (measured from the top edge) and a depth of 20 µm is naturally formed between the two protrusions.

[0146] A three-dimensional ultrasonic standing wave field (4.5 MHz, phase difference 120°) was constructed in the deposition zone to maintain the solid-liquid interface in a metastable state for 1.5 ms on the sidewall of the microchannel; at the same time, an oscillating magnetic field (frequency 100 Hz, amplitude 0.2 T) was applied to suppress dendrite growth.

[0147] By utilizing the low melting point (15℃) of nanofluids, residual media in the channels were precisely removed at a low temperature of 120℃ using a magnetic field gradient (55T / m), forming a microchannel array with a width of 200μm and an aspect ratio of 10:1.

[0148] FIB-SEM characterization showed that a nano-AlSiFe reinforcement layer (1.2 μm thick, 55 ± 8 nm grain size) was formed on the inner wall of the channel, with a thermal conductivity 200% higher than that of pure aluminum, and the manufacturing process temperature was always below the critical temperature threshold (250 °C) of photocontrolled solid-liquid transition.

[0149] Comparative Example 3 - Traditional Photo-Controlled Solid-Liquid Conversion Process

[0150] 1. Raw materials and equipment

[0151] raw material:

[0152] Photosensitive material: (E)-4-((4-(hexyl)phenyl)diazepine)phenol.

[0153] Sacrificial layer material: Polyethylene glycol (PEG) is used to form microchannels.

[0154] Substrate: Usually a transparent glass or silicon wafer.

[0155] Equipment: Laser direct writing system, spin coater, photomask, vacuum coating equipment, precision heating table.

[0156] 2. Specific steps

[0157] (1) Substrate cleaning and pretreatment:

[0158] The substrate was ultrasonically cleaned and dried using acetone, ethanol, and deionized water.

[0159] The substrate surface is subjected to plasma treatment to enhance its hydrophilicity and adhesion to subsequent films.

[0160] (2) Preparation of photosensitive thin film:

[0161] A uniform (14 μm) photosensitive material film was prepared on a substrate by vacuum evaporation.

[0162] For spin coating, the photosensitive material solution is dropped onto the substrate and rotated at a set speed (3000 rpm) for 30 seconds, and then pretreated on an 80°C hot plate for 10 minutes to remove residual solvent.

[0163] (3) Photolithography and patterning (solid-liquid transition):

[0164] Place the prepared sample under a laser direct writing system or a mask.

[0165] A predetermined area of ​​the thin film is irradiated using a laser of a specific wavelength (ultraviolet light, 365nm).

[0166] Core mechanism: After the laser energy is absorbed, the local temperature is instantly raised to the phase transition temperature of the material (usually >250°C) through photothermal effect, or the melting point of the material is lowered through photoisomerization, causing the irradiated area to change from solid to liquid.

[0167] (4) Microchannel molding:

[0168] Template method: Before light exposure, a template with a microchannel pattern is placed in contact with a photosensitive film. After liquefaction by light exposure, the liquid material flows and fills the template cavity. This step requires heating on a hot plate at 260°C for 5 minutes to ensure sufficient material flow and filling.

[0169] (5) Curing and post-treatment:

[0170] Remove the laser or mask. The liquid area cools and solidifies as the light exposure stops.

[0171] Oxygen plasma etching is used to remove residual sacrificial layers or unreacted areas, forming the final microchannel structure.

[0172] Table 3 Comparison of processes in Example 3 and Comparative Example 3

[0173]

[0174] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing bulk nanomaterials based on continuous solid-liquid interface transition, characterized in that, include: A) A metastable interface is obtained by simultaneously modulating the solid-liquid interface energy barrier of the solid-liquid conversion medium on the surface of the target region using a dynamic magnetic field and an ultrasonic standing wave. The solid-liquid conversion medium is a core-shell structured magnetic nanofluid. B) The metastable interface reacts with the elements on the surface of the target region to generate a submicron intermetallic compound reinforcing phase, thus obtaining a bulk nanomaterial.

2. The preparation method according to claim 1, characterized in that, The core-shell magnetic nanofluid includes core-shell magnetic nanoparticles; The core-shell structured magnetic nanoparticles include a magnetic nanoparticle core and an alloy layer covering the surface of the magnetic nanoparticle core. Preferably, the surface of the core-shell magnetic nanoparticles is modified with an oleylamine molecular layer.

3. The preparation method according to claim 2, characterized in that, The magnetic nanoparticles have a particle size of 10~50nm and a saturation magnetization of >80 emu / g; Preferably, the magnetic nanoparticles are selected from at least one of Fe3O4@Co nanoparticles, Fe3O4 nanoparticles, Co nanoparticles, and Fe nanoparticles; The alloy layer has a thickness of 6~10nm and a melting point of 20~60℃; Preferably, the alloy layer is selected from at least one of Ga-In-Sn eutectic alloy and Bi-In-Sn alloy.

4. The preparation method according to claim 1, characterized in that, The dynamic magnetic field includes at least one of a rotating magnetic field, an asymmetric magnetic field, and an oscillating magnetic field.

5. The preparation method according to claim 1, characterized in that, The dynamic magnetic field has a frequency of 1-100Hz, an intensity of 0.1-0.8T, and a gradient of 30-60T / m.

6. The preparation method according to claim 1, characterized in that, The frequency of the ultrasonic standing wave is 1-5MHz, and the power density is 20~80W / cm². 2 .

7. The preparation method according to claim 1, characterized in that, The interface reaction is completed by at least one of laser instantaneous heating and low-temperature reaction methods.

8. The preparation method according to claim 1, characterized in that, The target region includes at least one of the elements iron, aluminum, and titanium.

9. The preparation method according to claim 1, characterized in that, The target area can be a planar structure or a non-planar structure. The non-planar structure includes curved surface structure, hollow structure, and three-dimensional mesh structure.

10. The preparation method according to claim 1, characterized in that, The bulk nanomaterial further includes a reinforcing phase or a second phase material, wherein the reinforcing phase includes at least one of silicon carbide, alumina, silicon nitride, boron nitride, and boron carbide; the second phase material includes at least one of Al-10Si alloy, Sn-based alloy, In-based alloy, pure tin, and pure indium; and the reinforcing phase or the second phase material accounts for 10% to 50% of the volume percentage of the bulk nanomaterial.

11. The preparation method according to claim 10, characterized in that, The reinforcing phase is sprayed onto the surface of the target region through a coaxial three-channel nozzle and a core-shell structured magnetic nanofluid. The middle layer of the coaxial three-channel nozzle delivers the reinforcing phase, the inner layer delivers the magnetic nanofluid, and the outer layer delivers the protective gas.

12. A bulk nanomaterial prepared by the preparation method according to any one of claims 1 to 11.

13. A system for preparing bulk nanomaterials based on continuous solid-liquid interface transition, characterized in that, include: A multi-physics coupling printhead integrating magnetic coils and piezoelectric transducer arrays; Real-time topography monitoring system; Adaptive feedback controller.

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