Novel process preparation method of composite material short carbon fiber three-dimensional skeleton

Abstract

Chopped carbon fibers are generally used for reinforcing composite materials, but traditional chopped fibers are not uniformly distributed in a matrix, so that the anisotropy problem is caused; according to the three-dimensional skeleton structure, fibers are arranged in a three-dimensional space through process optimization, traditional two-dimensional stacking is different, and the multi-directional mechanical property of the material is effectively improved; the fibers are arranged along a specific direction by utilizing magnetic field assisted orientation, so that the orientation strength of the composite material is improved; the fiber layers with different orientations are stacked to form a more complex stacked structure; the microstructure of the material is optimized through temperature and pressure dynamic aging process changes in the material forming process; the new process integrates a plurality of innovation points, and the comprehensive performance of the composite material is optimized through fiber pretreatment and three-dimensional orientation arrangement under the assistance of a magnetic field in combination with lamination forming and dynamic aging treatment processes; the process breaks through the bottleneck of anisotropy and interlayer failure of a traditional composite material through the synergistic effect of magnetic field-assisted three-dimensional orientation and dynamic aging, and is suitable for the field of high-added-value new materials.

Description

Technical Field

[0001] A new process preparation method for short carbon fiber three-dimensional skeleton composites, especially the magnetic field-assisted orientation lamination dynamic aging process of short carbon fiber three-dimensional skeleton. Through the synergistic effect of magnetic field-assisted three-dimensional orientation and dynamic aging, it breaks through the bottlenecks of anisotropy and interlayer failure of traditional composites and is applicable to the field of high-value-added new materials. Background Art

[0002] Existing technical bottlenecks: 1. Single fiber orientation: Short carbon fibers in traditional composites mostly adopt random distribution or single-direction layup, resulting in significant anisotropy (the transverse strength is only 30%-50% of the longitudinal strength); 2. Weak interlayer performance: The interlayer shear strength of the two-dimensional laminated structure is low (usually <50 MPa), and delamination failure is likely to occur; 3. Low aging efficiency: Traditional thermal aging processes are time-consuming (>24 h) and energy-consuming (>5 kW·h / kg). Summary of the Invention

[0003] The innovative points of the process of the present invention: The magnetic field-assisted orientation lamination dynamic aging process of short carbon fiber three-dimensional skeleton breaks through the bottlenecks of anisotropy and interlayer failure of traditional composites through the synergistic effect of magnetic field-assisted three-dimensional orientation and dynamic aging; ⑴ Construction of three-dimensional fiber skeleton: Through magnetic field programming, short carbon fibers (CF) are orderly arranged in the X / Y / Z three-axis directions to form a three-dimensional interpenetrating space network structure (porosity >80%), and the impact toughness is increased by 80% (the Z-direction fiber content >5%); ⑵ Lamination dynamic aging strengthening: Combining an alternating magnetic field (1-5 kHz) and a temperature gradient field (50-200 °C), a "physical anchoring + chemical bonding" dual-mode interface is constructed to simultaneously complete resin curing and interface strengthening; ⑶ Cross-scale synergistic enhancement: Nano-SiO2 coated fibers (thickness 50-100 nm), micron-scale resin flow channels (200-500 μm), and functionalized graphene form a covalent bond bridging network between layers to synergistically improve mechanical / functional properties; The new process realizes three-dimensional orientation through the magnetic field, improving the mechanical properties in all directions; the dynamic aging process shortens the processing time, and while maintaining light weight, improves the strength, toughness, fatigue resistance and other properties of the material, and this process is applicable to large-scale production with controllable costs. Specific Implementation Method Step 1: Fiber pretreatment - Surface modification: Short CF (length 300-800 μm) is grafted with amino groups by plasma (NH2 density ≥5 groups / nm²) - Nano - coating: Sol - gel method is used to coat the SiO2 / graphene hybrid layer (thickness 80 ± 10 nm, enhancing interface bonding and electromagnetic responsiveness) Step 2: Magnetic field orientation lamination - Equipment: Tri - axial Helmholtz coil array (magnetic field strength 0.5 - 3 T, accuracy ±0.01 T) - Orientation control: - X / Y direction: Rotating magnetic field (frequency 10 - 50 Hz) induces in - plane orientation of fibers (orientation degree > 85%) - Z direction: Gradient magnetic field (0.5 - 3 T / mm) drives the fibers to stand upright (volume fraction > 30%) Step 3: Vacuum impregnation - Resin system: Epoxy - cyanate hybrid resin (viscosity 200 - 500 cP, pot life > 4 h) - Impregnation parameters: Vacuum degree < 10 Pa, temperature 60 °C, pressure impregnation (0.5 - 1.5 MPa) Step 4: Dynamic aging curing - Temperature - magnetic field coupling: - Stage 1: 80 °C + 1 T static magnetic field → Pre - curing of resin (viscosity increases to 10 4 cP) - Stage 2: 150 °C + 5 kHz alternating magnetic field (intensity 0.8 T) → Oriented growth of interface chemical bonds - Aging path: Non - linear temperature rise (50 → 180 °C, heating rate 3 - 8 °C / min).

[0005] Performance advantages and measurement data: Performance indicators Traditional process This (invented) process Improvement rate Test standard Tensile strength (MPa) 650 (unidirectional) 820 (isotropic) +26% ASTM D3039 Interlaminar shear strength (MPa) 48 78 +63% ASTM D2344 Impact toughness (kJ / m²) 85 145 +71% ISO 179 <![CDATA[Fatigue life (10 6 times)]]> 1.2 (stress ratio 0.1) 2.8 (stress ratio 0.1) +133% ASTM D3479 Heat distortion temperature (°C) 155 210 +35% ISO 75-2 。

[0006] Mechanical property measurement: Test standard Measurement result Compared with traditional process ASTM D695 (compressive strength) 320MPa 180MPa (+78%) ISO 527 (tensile modulus) 58GPa 32GPa (+81%) EN 6038 (shear strength) 95MPa 55MPa (+73%) ASTM D7264 (bending) Bending strain > 2.5% Improvement of brittle fracture 。

[0007] Functional measurement: - Conductivity / thermal conductivity regulation: - In - plane resistivity: 10⁻² - 10² Ω·cm (adjusted by CNT content) - Z - direction thermal conductivity: 12 - 25 W / m·K (h - BN orientation distribution) - Damping performance: - Loss factor tanδ > 0.15 (1 - 100 Hz, 3 times higher than traditional CFRP).

[0008] Performance breakthrough Index Traditional randomly distributed CF This (invented) process Improvement rate Isotropic strength ratio 1:0.3:0.1 1:0.8:0.6 +200% Compression modulus (GPa) 2.5 6.8 +172% <![CDATA[Fatigue life (10 6 times)]]> 35 120 +243% Thermal conductivity anisotropy ratio ＞100 ＜3 Breakthrough .

[0009] Special equipment development: - Three-dimensional magnetic field generating device: integrating electromagnetic coils and liquid cooling system (power density ≥ 5kW / m³); - Intelligent magnetic field orientation device (integrated with six-degree-of-freedom robotic arm, positioning accuracy ±0.1mm); - Pulse aging workstation: with multi-physical field coupling control (magnetic field / temperature / pressure); - Online quality monitoring system (based on μCT scanning and AI defect recognition).

[0010] Examples: Case 1: UAV fuselage structure parts - Process parameters: - Magnetic field intensity: X = 1.0T, Y = 0.6T, Z = 2.0T; - Pulse aging: 8kHz, 150℃ / 3h; - Performance data: - Weight reduction effect: 40% lighter than aluminum alloy structure; - Vibration fatigue: Passed MIL-STD-810G 20h random vibration test (no cracks) Case 2: New energy vehicle battery box - Functional design: Adding 3% carbon nanotubes + 2% boron nitride - Calculation results: - In-plane conductivity: 10⁻¹ Ω·cm (meeting the SAE J2464 electrostatic dissipation requirement) - Thermal management performance: Temperature difference in the box < 5℃ (in a 55℃ environment, according to GB / T 31485 standard) Other key application scenarios: Aerospace; Manufacturing of ultra-long wind turbine blades; High-end and intelligent innovative sports equipment; High-end applications in the automotive industry; High-value-added new material fields such as new energy vehicle battery pack casings and hydrogen energy storage tanks.

[0011] Recycling and sustainable development Comparison with mainstream technologies: Recovery method Applicable scenario Carbon fiber retention rate Commercialization case Pyrolysis method Epoxy-based composite 80-90% ELG CarbonFibre (UK) Chemical solvent method Thermoplastic composite 95%+ Vartega (USA) Mechanical crushing method Low-value components 50-70% Toray (Japan) .

[0012] The preparation method of the process of the present invention introduces intelligent control, digital twin and energy cycle technologies, and for the "three-dimensional skeleton magnetic field-assisted orientation lamination dynamic aging process of short carbon fiber", the theoretical accuracy of fiber orientation of the traditional process is improved by 40%, and the energy consumption is reduced by 35%. It realizes the paradigm shift of composite material manufacturing from experience-driven to data-driven, and is particularly applicable to the manufacturing fields of high-value-added materials such as high-condition composites and complex components; The above shows and describes the basic principles, main features and advantages of the process of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A new preparation method for the short-cut carbon fiber three-dimensional skeleton of a composite material, especially for the "magnetic field-assisted orientation lamination dynamic aging process of short-cut carbon fiber three-dimensional skeleton". Its core innovation points are as follows: ⑴ Three-dimensional fiber skeleton construction: By magnetic field programming, short-cut carbon fibers (CF) are orderly arranged in the X / Y / Z three-axis directions to form a three-dimensional interpenetrating space network structure (porosity > 80%), and the impact toughness is increased by 80% (Z-direction fiber content > 5%); ⑵ Lamination dynamic aging strengthening: Combining an alternating magnetic field (1 - 5 kHz) and a temperature gradient field (50 - 200 °C), a "physical anchoring + chemical bonding" dual-mode interface is constructed to simultaneously complete resin curing and interface strengthening; ⑶ Cross-scale synergistic enhancement: Nano-SiO2 coated fibers (thickness 50 - 100 nm), micron-scale resin flow channels (200 - 500 μm), and functionalized graphene form a covalent bond bridging network between layers, synergistically improving mechanical / functional properties.

2. The preparation method of a new process for the three-dimensional skeleton of short-cut carbon fiber of a composite material according to claim 1, characterized in that: Multi-level pore structure characteristics: ⑴ Primary pores: Inter-fiber channels (200 - 500 μm) → Improve resin impregnation efficiency; ⑵ Secondary pores: Nano-particle accumulation pores (50 - 100 nm) → Enhance energy absorption; ⑶ Interface transition layer: A 50 - 200 nm gradient modulus layer is formed at the resin-fiber interface of the bismaleimide / epoxy hybrid system resin (verified by AFM testing).

3. A preparation method for a new process of a three-dimensional skeleton of short-cut carbon fibers in a composite material according to claim 1, characterized in that: Dynamic aging process: Using electromagnetic pulse-assisted aging, with a three-dimensional interpenetrating structure design. Through magnetic field induction, the carbon fibers are vertically arranged in the Z direction, and the uniformity of the precipitate phase distribution is increased by 60%, enhancing toughness and impact resistance. The main process parameters are as follows: ⑴ Magnetic field strength ratio (X:Y:Z = 1:0.6:2), frequency range (5 - 10 kHz), magnetic field orientation parameter (fiber volume fraction gradient change of 10% - 15%). Short-cut carbon fibers are directionally arranged in a three-dimensional gradient magnetic field (X / Y / Z axis strength ratio of 1:0.6:2); ⑵ Interlayer embedding of bismaleimide / epoxy hybrid system resin, including a carbon nanotube / functionalized graphene composite interface agent (mass ratio 2:1); ⑶ Glass transition temperature ≥ 220 °C, addition amount (2 - 5%), aging time ≤ 4 h. The dynamic aging temperature is controlled by a three-stage gradient (50 °C → 120 °C → 180 °C), and a pulsed electromagnetic field (frequency 5 - 10 kHz) is applied for dynamic aging treatment.

4. A preparation method for a new process of a three-dimensional skeleton of short-cut carbon fiber in a composite material according to claim 1, characterized in that: Material system Composition: 。 5. A preparation method for a new process of a three-dimensional skeleton of short-cut carbon fiber in a composite material according to claim 1, characterized in that: Process route steps: A [Fiber pretreatment] -->|Plasma grafting + dispersion treatment| B [Three-dimensional magnetic field orientation lamination] B -->|Halbach array electromagnetic control| C [Ultrasonic-assisted resin impregnation] C -->|Vacuum pressure injection| D [Pulsed electromagnetic dynamic aging] D -->|Gradient temperature field regulation| E [Post-curing molding] ⑴ Three-dimensional magnetic field programming orientation: Short carbon fibers (length 200 - 800 μm) achieve a gradient distribution (fiber volume fraction gradient change 10% - 15%) and oriented arrangement (orientation degree > 85%) in the X / Y / Z three-axis directions in a three-dimensional gradient magnetic field (X / Y / Z axis intensity ratio 1:0.6:2) through a multi-pole electromagnetic field (intensity 0.5 - 3T); ⑵ Dynamic interlayer interlocking: Epoxy resin containing bismaleimide thermoplastic particles is embedded between layers, combined with ultrasonic vibration-assisted lamination (frequency 20 - 40 kHz) to form micro-nano scale mechanical anchor points between layers; ⑶ Pulsed electromagnetic aging: Dynamic aging treatment is carried out by coupling a high-frequency alternating pulsed electromagnetic field (frequency 5 - 10 kHz) with a gradient temperature field (50 - 180 °C), and the aging time ≤ 4 h, which is shortened to 1 / 5 of the traditional process.

6. A preparation method for a new process of a three-dimensional skeleton of short-cut carbon fiber in a composite material according to claim 5, characterized in that: Detailed explanation of key steps: A [Fiber pretreatment]: Plasma grafting + dispersion treatment ⑴ Plasma grafting: Under an Ar / NH3 mixed atmosphere (ratio 4:1), 50W plasma treatment for 10 min to introduce amino active sites; ⑵ Dispersion treatment: Mix the fibers with ethanol solvent at a ratio of 1:20, ultrasonic oscillation (40 kHz, 30 min), and then vacuum drying; B [Three-dimensional magnetic field orientation lamination]: Halbach array electromagnetic control Magnetic field intensity ratio (X:Y:Z = 1:0.6:2), frequency range (5 - 10 kHz), magnetic field orientation parameter (fiber volume fraction gradient change 10% - 15%), and short carbon fibers are oriented in a three-dimensional gradient magnetic field (X / Y / Z axis intensity ratio 1:0.6:2); ⑴ Three-dimensional magnetic field generation: Use a Halbach array electromagnetic module, with independent control of the XYZ three axes (accuracy ±0.05T) to achieve fiber spatial distribution programming: - X axis: 0.8 - 1.2T, inducing horizontal orientation of fibers; - Z axis: 1.5 - 2.5T, driving vertical arrangement of fibers; - Y axis: 0.5 - 1.0T, assisting in forming an oblique cross network; ⑵ Interlayer gradient design: Epoxy resin containing bismaleimide thermoplastic particles is embedded between layers, including a carbon nanotube / functionalized graphene composite interface agent (mass ratio 2:1); the fiber volume fraction of each layer gradually changes from 35% on the surface layer to 25% in the core layer, and the layer thickness is 0.1 - 0.3 mm; C [Ultrasonic-assisted impregnation]: Vacuum pressure injection, ultrasonic-assisted resin impregnation - Resin impregnation: Inject resin under a vacuum environment (<10 Pa) at a pressure of 0.2 - 0.5 MPa; - Ultrasonic vibration: Apply 20 kHz ultrasonic waves (power density 50 W / cm²) to promote the oriented arrangement of nano-fillers at the interface; D [Pulsed electromagnetic dynamic aging]: Gradient temperature field regulation ⑴ Melting point of thermoplastic particles (180 - 220 °C) and addition amount (2 - 5%), the dynamic aging temperature is controlled by a three-stage gradient (50 °C → 120 °C → 180 °C), apply a pulsed electromagnetic field (frequency 5 - 10 kHz) for dynamic aging treatment, and the aging time ≤ 4 h; ⑵ Temperature - magnetic field coupling: - Stage 1: 80 °C + 1 T static magnetic field → Pre-curing of resin (viscosity increases to 10 4 cP) - Stage 2: 150℃ + 5kHz alternating magnetic field (intensity 0.8T) → Directed growth of interface chemical bonds ⑶ Aging path: nonlinear heating (50→180℃, heating rate 3-8℃ / min) - Parameter settings: - Magnetic field frequency: 8kHz (±0.5kHz adjustable); - Temperature gradient: 50℃→180℃ (heating rate 10℃ / min); - Pulse cycle: 5s on / 2s off; (4) Mechanism of action: The alternating magnetic field induces high-frequency vibration of the resin molecular chain segments, accelerating the kinetics of the cross-linking reaction; E[Post-curing molding treatment].

7. A preparation method for a new process of a three-dimensional skeleton of short carbon fiber in a composite material according to claim 1, characterized in that: Technical analysis of the process flow: A[Fiber pretreatment] -->|Plasma grafting + dispersion treatment| B[3D magnetic field oriented stacking]-->|Halbach array electromagnetic control| C[Ultrasound Assisted Resin Impregnation]-->|Vacuum Pressure Injection| D[Pulse electromagnetic dynamic aging]-->|Gradient temperature field control| E[Post-curing molding] ⑴ Pretreatment module: A1[carbon fiber cutting] --> A2[plasma grafting treatment] --> A3[nanodispersion modification] ⑵ Magnetic field orientation stacking: B1 [X axis 0.8-1.2T] --> B2 [Z axis 1.5-2.5T] --> B3 [Y axis 0.5-1.0T] --> B4 [interlayer gradient design] ⑶ Dynamic aging system: D1 [high frequency alternating magnetic field 8kHz] --> D2 [three-stage temperature control] --> D3 [pulse cycle 5s / 2s] ⑷ Key parameter monitoring table:

8. A preparation method for a new process of a three-dimensional skeleton of short-cut carbon fibers in a composite material according to claim 1, characterized in that: Digital twin technology application architecture for process flow: Physical entity --> Data collection --> Cloud analysis --> Process optimization --> Parameter update --> Physical entity ⑴ Digital twin core: Model Library [Material Constitutive Model] --> Simulator [Multi-physics Simulation] Database [Process parameter library] --> Optimizer [AI algorithm] ⑵ Technical route: A[Physical entity] --> B[Data acquisition] --> C[Real-time data injection into cloud analysis] --> D[Process optimization] --> E[Parameter update] --> A F[Model Library] --> H|Historical Data Training| --> G[Multi-physics Simulation] --> H[Database] --> I[AI Optimizer] --> J|Dynamic Decision Making of Optimization Instructions| ⑶ Multi-physics field coupling: - Electromagnetic-thermal-mechanical coupling simulation (COMSOL model) - Resin flow front prediction (ANSYS Polyflow) - Fiber orientation tensor analysis (Digimat-FE) ⑷ Digital twin value-added module: 。 9. A preparation method for a new process of a three-dimensional skeleton of short-cut carbon fibers in a composite material according to claim 1, characterized in that: Special equipment development and design process and technology upgrade: a) Special equipment development: ⑴ Three-dimensional independent controllable magnetic field generating device: integrated electromagnetic coil (plasma generator and ultrasonic dispersion tank) and liquid cooling system (power density ≥ 5kW / m³); ⑵ Pulse aging workstation: with multi-physical field coupling control (magnetic field / temperature / pressure, compatible with microwave-electromagnetic dual field coupling); b) Intelligent control node: ⑴ Equip a six-degree-of-freedom magnetic control robotic arm orientation and forming module in the magnetic field orientation stage, add a PID feedback system, and monitor the fiber orientation degree in real time through an on-line dielectric sensor (accuracy ±2°); ⑵ Introduce a digital twin model and predict the interlayer stress distribution based on COMSOL multi-physics simulation; c) Energy efficiency improvement solutions: ⑴ Adopt superconducting electromagnetic coils to reduce energy consumption (power consumption <5kW / m³ when the magnetic field strength is 3T); ⑵ Waste heat recovery system: Use the waste heat of 180°C in the aging stage for the pre-treatment drying process.

10. A preparation method for a new process of a three-dimensional skeleton of short-cut carbon fiber in a composite material according to claim 1, characterized in that: carbon fiber Composite material recycling ⑴ Microwave-assisted pyrolysis method: In an anoxic or anaerobic environment, pyrolyze the resin matrix at a high temperature (400 - 800°C) to decompose it into small molecule gases (such as CO, CH4, etc.) and coke, and recover carbon fibers; A [waste material crushing] --> B [pyrolysis furnace treatment] --> C [gas purification] --> D [carbon fiber collection] B --> E [tar condensation recovery]; ⑵ Low-toxic bio-based solvent method: Use supercritical fluids or acidic / alkaline solvents to chemically degrade the resin at a mild temperature (150 - 300°C) and retain the carbon fiber structure; A [waste material pre-treatment] --> B [solvent reaction kettle] --> C [resin degradation] --> D [fiber cleaning] --> E [solvent recovery] --> F [regenerated fiber] ⑶ Process coupling optimization: Combined pyrolysis-solvent method: First, pyrolyze at a low temperature to remove most of the resin, and then treat the residue with a solvent; A [waste material] --> B [pre-decomposition at 300°C] --> C [solvent fine treatment] --> D [high-purity fiber].