Multi-field cooperative driving intelligent response foamed aluminum composite material and preparation method thereof

Abstract

The invention discloses a multi-field cooperative driving intelligent response foamed aluminum composite material and a preparation method thereof, and belongs to the technical field of intelligent metal composite materials. The preparation method comprises the following steps: weaving NiTi shape memory alloy fibers subjected to segmented stretching-low-temperature aging pretreatment into a three-dimensional skeleton; the preparation method comprises the following steps: mixing aluminum powder, Al-Mg alloy powder and core-shell structure functional filler (such as SiO2-coated Fe3O4-coated PEDOT) with a magnetic core, a conductive middle layer and an insulating protection outer layer, and adding a binder to prepare composite slurry; and injecting the slurry into the framework, and then carrying out vacuum degassing and hot pressed sintering. A pore-forming agent is not needed, and the process is green and simple. The prepared composite material has an integrated porous structure, has excellent mechanical properties (the compressive strength is greater than or equal to 30MPa, and the fracture toughness is greater than or equal to 4.5 kJ / m), can realize high-precision and high-stability multi-field cooperative driving of magnetic field pre-triggering, electric field fine tuning and thermal field recovery, and has a wide application prospect in the fields of intelligent driving and damping.

Description

Technical Field

[0001] This invention relates to the field of intelligent metal composite materials technology, specifically to an intelligent responsive aluminum foam composite material with synergistic driving capabilities of magnetic, electrical, and thermal fields, and its preparation method. Background Technology

[0002] Intelligent responsive aluminum foam materials have broad application prospects in fields such as flexible actuators, intelligent vibration damping, sensing and actuators because they combine the lightweight and high specific strength characteristics of porous metals with the ability to respond to external fields (such as magnetic fields, electric fields, and temperature fields).

[0003] Currently, the preparation of aluminum foam mostly employs the pore-forming agent method. For example, Chinese patent document CN200410020384.X discloses a "method for preparing aluminum foam by cold pressing-dissolution-vacuum sintering," which involves mixing a NaCl pore-forming agent, cold pressing, dissolving and removing the pore-forming agent in a water bath, and then vacuum sintering. This method has the following significant drawbacks: The process is complex and polluting: the steps of adding, dissolving and washing the pore-forming agent are lengthy, generating saline wastewater, increasing environmental protection costs and production cycle, and the residue of the pore-forming agent (which can easily exceed 0.1wt%) can cause intergranular corrosion of the matrix.

[0004] High sintering temperatures lead to performance degradation: Sintering temperatures as high as 540-560℃ result in coarse aluminum matrix grains (10-20μm) and low fracture toughness (typically ≤3kJ / m²). This high temperature also far exceeds the stable phase transformation temperature range of NiTi shape memory alloys, causing its shape memory effect to decay and making it unsuitable for preparing high-performance smart composite materials.

[0005] The process is limited to a single function and cannot achieve multi-field response because it does not consider the composite use of functional fillers. If magnetic or conductive fillers are forcibly added, the fillers will be severely lost (20-30%) during the water bath washing step, resulting in functional failure and uneven distribution.

[0006] Therefore, the development of a foamed aluminum composite material with simple process, green and environmentally friendly properties, excellent mechanical properties and stable multi-field driven response and its preparation method has become an urgent need in this field. Summary of the Invention

[0007] One of the objectives of this invention is to overcome the shortcomings of existing technologies and provide a method for preparing intelligent responsive aluminum foam composite materials driven by multi-field synergy. This method abandons traditional pore-forming agents and achieves pore formation through the synergistic interaction between NiTi fiber skeleton and composite slurry, simplifying the process, making it environmentally friendly, and realizing the precise integration of the material's magnetic, electrical, and thermal multi-field response functions.

[0008] A second objective of this invention is to provide a smart responsive aluminum foam composite material prepared by the above method. This material has an integrated porous structure, excellent mechanical properties, and exhibits high-precision and high-stability strain response under the influence of magnetic, electric, and temperature fields.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a multi-field synergistically driven intelligent responsive aluminum foam composite material, comprising the following steps: (1) A three-dimensional skeleton is woven from pretreated NiTi shape memory alloy fibers; (2) Preparation of composite slurry: Weigh aluminum powder, Al-Mg alloy powder and core-shell structure functional filler in a mass ratio of 7-9:0.5-1.5:0.5-1.5, wherein the core-shell structure functional filler is a composite structure with a magnetic core, a conductive intermediate layer and an insulating protective outer layer; add 10-20% of water-soluble binder by mass of total solids and mix to obtain a uniformly dispersed composite slurry; (3) Vacuum hot pressing sintering: The composite slurry from step (2) is injected into the NiTi fiber skeleton from step (1), and after degassing, it is hot pressed and sintered in a vacuum environment and cooled with the furnace to obtain the intelligent responsive aluminum foam composite material. The three-dimensional skeleton accounts for 10-20% of the volume of the composite material, and together with the composite slurry, it forms a porous structure that does not require the addition of a pore-forming agent.

[0010] Preferably, in step (1), the pretreatment process of the NiTi shape memory alloy fiber is as follows: the NiTi alloy wire is subjected to segmented stretching deformation, and then subjected to low temperature aging treatment at 50-100℃ for 1-4h to obtain pre-deformed NiTi fiber with phase transformation temperature Af fluctuation ≤ ±2℃.

[0011] More preferably, the segmented tensile deformation specifically involves: first stretching to 4-6% strain at a rate of 1-3% / min and holding at a temperature for 5-15min, and then continuing to stretch to a total strain of 8-12%.

[0012] Preferably, in step (2), the core-shell structured functional filler is a SiO2@Fe3O4@PEDOT structure.

[0013] More preferably, the SiO2@Fe3O4@PEDOT core-shell structure is prepared by a method including the following steps: first, Fe3O4 nanoparticles are synthesized by hydrothermal method, then PEDOT is polymerized in situ on its surface to form a conductive intermediate layer, and finally, the SiO2 outer layer is coated by sol-gel method.

[0014] More preferably, in the SiO2@Fe3O4@PEDOT core-shell structure, the Fe3O4 core particle size is 100-500nm, the PEDOT intermediate layer thickness is 10-50nm, and the SiO2 outer layer thickness is 5-10nm.

[0015] Preferably, in step (3), the hot-pressing sintering conditions are: heating to 420-480℃ at a heating rate of 3-8℃ / min, applying a pressure of 15-25MPa and holding at that temperature for 1-3 hours; the vacuum degree of the vacuum environment is ≤10. -2 Pa.

[0016] Secondly, the present invention provides a multi-field synergistically driven smart responsive aluminum foam composite material prepared by the above-described preparation method.

[0017] Preferably, the composite material has an integrated porous structure consisting of a three-dimensional NiTi fiber skeleton and an aluminum-based composite slurry, with a porosity of 25-40% and a pore size distribution of 50-600 μm.

[0018] Preferably, the composite material can generate controllable strain in response to magnetic field, electric field and temperature field, specifically: it can generate at least 10% basic compressive strain under a 100mT magnetic field; and when a 3VDC voltage is applied on the basis of the magnetic field driving, micro-strain control of more than ±1% can be achieved within 0.5s, with a strain accuracy of ≤±0.2%.

[0019] Preferably, the composite material is subjected to 5×10⁻⁶ cycles at 60°C / 90% relative humidity. 4 After the secondary magneto-electric co-drive cycle, the strain attenuation rate is ≤5% and the response time change rate is ≤8%.

[0020] Preferably, the compressive strength of the composite material is ≥30MPa and the fracture toughness is ≥4.5kJ / m².

[0021] The beneficial effects of this invention are: Integrated structure-function design: Using a three-dimensional NiTi fiber skeleton as the support and thermal driving element, combined with a composite slurry containing functional fillers, an integrated porous structure is directly formed without the need for pore-forming agents. This not only simplifies the process and shortens the production cycle by approximately 40%, avoiding wastewater pollution and impurity residues (metal ion residue ≤0.005wt%), but also achieves a perfect integration of structural load-bearing capacity and multi-field response functions (magnetic, electrical, and thermal).

[0022] Multi-field synergistic driving and high-precision control: An innovative synergistic driving mode of "magnetic field pre-triggering (macroscopic strain) + electric field fine-tuning (microscopic strain) + thermal field recovery" is proposed. This mode achieves a rapid response within 0.5s and a strain accuracy within ±0.2% under safe low voltage (3V), solving the problems of low response accuracy and high driving voltage of existing smart materials.

[0023] Excellent environmental stability: Thanks to the design of the SiO2 insulating protective layer in the core-shell filler, the corrosion of Fe3O4 and PEDOT by the humid and hot environment is effectively isolated. After 50,000 cycles in a harsh environment of 60℃ / 90% humidity, the performance degradation rate of the material is extremely low, and the lifespan is more than 5 times longer than that of unprotected materials.

[0024] Excellent comprehensive mechanical properties: The addition of Al-Mg alloy powder lowers the sintering temperature (420-480℃), inhibits grain growth, and at the same time, it synergistically strengthens with the NiTi skeleton, so that the composite material can maintain a porous structure (porosity 25-40%) while having high compressive strength (≥30MPa) and high fracture toughness (≥4.5kJ / m²), overcoming the contradiction that traditional aluminum foam has difficulty in balancing mechanical properties and functional characteristics. Detailed Implementation

[0025] The present invention will be further described below with reference to embodiments, but the scope of protection of the present invention is not limited thereto.

[0026] Example 1: Preparation of SiO2@Fe3O4@PEDOT core-shell structured functional filler Synthesis of Fe3O4 cores: 0.1 mol FeCl3·6H2O and 0.05 mol FeSO4·7H2O were dissolved in 200 mL of deionized water and stirred for 30 min under nitrogen protection. 10 mL of concentrated ammonia (28 wt%) was added dropwise to adjust the pH to 10, and the mixture was heated to 80 °C and reacted for 2 h. After the reaction was complete, the mixture was cooled and washed three times alternately by centrifugation with deionized water and ethanol (8000 r / min, 10 min each time). The mixture was then vacuum dried at 60 °C for 12 h to obtain Fe3O4 nanoparticles with a particle size of 100-500 nm.

[0027] Coating the PEDOT intermediate layer: 1 g of the above Fe3O4 nanoparticles were dispersed in 100 mL of deionized water and sonicated for 30 min (300 W). 0.5 mg of PEDOT monomer and 0.2 g of ammonium persulfate (APS) were added, and the mixture was stirred at room temperature for 24 h. After the reaction, the mixture was centrifuged, washed three times with ethanol, and vacuum dried at 60 °C for 8 h to obtain the Fe3O4@PEDOT core-shell structure. The PEDOT layer conductivity was measured to be 1200 S / cm, and the thickness was 10-50 nm.

[0028] SiO2 outer layer coating: 1 g of Fe3O4@PEDOT was weighed and dispersed in a mixed solution of 80 mL ethanol and 20 mL deionized water, and ultrasonically dispersed for 20 min. 0.2 mL of LTEOS and 0.5 mL of ammonia were added dropwise, and the mixture was stirred at room temperature for 6 h. After centrifugation, the mixture was washed three times with ethanol and vacuum dried at 60 °C for 12 h to obtain the SiO2@Fe3O4@PEDOT core-shell structure. TEM observation showed that the SiO2 layer thickness was 5-10 nm.

[0029] Example 2: Preparation of Smart Response Foamed Aluminum Composite Material NiTi fiber pretreatment and skeleton weaving: NiTi alloy wire with a diameter of 50 μm and a Ni:Ti atomic ratio of 50.8:49.2 was selected. Segmented tensile testing was performed using an electronic universal testing machine: first, the wire was stretched to 5% strain at a rate of 2% / min and held at that temperature for 10 min; then, it was stretched further to 10% of the total strain. Subsequently, it was aged in an 80℃ forced-air drying oven for 2 h. DSC analysis showed that the phase transition temperature (Af) of the pretreated fiber was 25±1℃. The fiber was then woven into a 5×5×5 mm cubic skeleton using a braiding machine, with the skeleton accounting for 15% of the total volume.

[0030] Preparation of composite slurry: Aluminum powder (particle size 5-10 μm, purity 99.9%), Al-Mg alloy powder (Mg content 5 wt%, particle size 3-8 μm), and SiO2@Fe3O4@PEDOT filler prepared in Example 1 were weighed at a mass ratio of 8:1:1. A 10 wt% PVA binder solution (15% of the total solids mass) was added, and the mixture was placed in a planetary ball mill and mixed at 200 r / min for 30 min to obtain a uniform composite slurry.

[0031] Vacuum hot pressing sintering: The composite slurry is injected into the NiTi fiber skeleton and placed in a vacuum drying oven for degassing at -0.095 MPa for 30 min. It is then transferred to a vacuum hot pressing furnace and evacuated to a vacuum level of 5 × 10⁻⁶. -3 The temperature was increased to 450℃ at a rate of 5℃ / min, and a pressure of 20MPa was applied for holding at that temperature for 2 hours. Heating was then stopped, and the sample was cooled to room temperature in the furnace. The sample was then removed to obtain the composite aluminum foam material.

[0032] Example 3: Composite Material Performance Testing Multi-field drive performance: Magnetic field driven: Under a uniform magnetic field of 100 mT, the material produces 15.2% compressive strain.

[0033] Magnetism-electric synergistic drive: When a 3VDC voltage is applied on a 100mT magnetic field, the material achieves a micro-strain of +1.8% within 0.28s, with a strain accuracy of ±0.08%.

[0034] Thermal recovery performance: In a 60℃ oil bath, the compressed sample recovered its initial shape within 2.3s, with a recovery rate of 98.5%.

[0035] Environmental stability: tested at 60℃ / 90%RH for 5×10 4 The secondary magneto-electric co-driven cycle. The response time changed from 0.28s to 0.29s (a change rate of 3.6%), and the strain decreased from 15.2% to 14.8% (a decrease rate of 2.6%).

[0036] Mechanical properties: compressive strength is 38 MPa, elastic modulus is 1.3 GPa, and fracture toughness is 5.5 kJ / m².

[0037] Comparative Example Aluminum foam was prepared using the method described in patent CN200410020384.X in the background art, and an attempt was made to add 20wt% Fe3O4@PEDOT filler. The results showed that: the preparation process generated a large amount of wastewater, and the filler loss rate reached 25%; the obtained material had uneven pores and no electric field response capability; the sintering temperature of 550℃ resulted in coarse aluminum grains and a fracture toughness of only 2.8kJ / m².

[0038] The above embodiments and comparative examples fully demonstrate the significant advantages of the present invention in terms of advanced technology, functional diversity, and comprehensive performance.

[0039] This invention is not limited to the above-described embodiments. Any changes, modifications, substitutions, or combinations made by those skilled in the art without departing from the spirit of this invention should be included within the scope of protection of this invention.

Claims

1. A method for preparing a multi-field synergistically driven intelligent response foam aluminum composite material, characterized in that, Includes the following steps: (1) A three-dimensional skeleton is woven from pretreated NiTi shape memory alloy fibers; (2) Preparation of composite slurry: Weigh aluminum powder, Al-Mg alloy powder and core-shell structure functional filler in a mass ratio of 7-9:0.5-1.5:0.5-1.5, wherein the core-shell structure functional filler is a composite structure with a magnetic core, a conductive intermediate layer and an insulating protective outer layer; add 10-20% of water-soluble binder by mass of total solids and mix to obtain a uniformly dispersed composite slurry; (3) Vacuum hot pressing sintering: The composite slurry from step (2) is injected into the NiTi fiber skeleton from step (1), and after degassing, it is hot pressed and sintered in a vacuum environment and cooled with the furnace to obtain the intelligent responsive aluminum foam composite material. The three-dimensional skeleton accounts for 10-20% of the volume of the composite material, and together with the composite slurry, it forms a porous structure that does not require the addition of a pore-forming agent.

2. The preparation method according to claim 1, characterized in that, The pretreatment process of NiTi shape memory alloy fiber in step (1) is as follows: NiTi alloy wire is subjected to segmented stretching deformation, and then subjected to low temperature aging treatment at 50-100℃ for 1-4h to obtain pre-deformed NiTi fiber with phase transformation temperature Af fluctuation ≤ ±2℃.

3. The preparation method according to claim 2, characterized in that, The segmented tensile deformation is specifically as follows: first, stretch at a rate of 1-3% / min to 4-6% strain and hold at temperature for 5-15 minutes, then continue stretching to a total strain of 8-12%.

4. The preparation method according to claim 1, characterized in that, The core-shell structured functional filler in step (2) is a SiO2@Fe3O4@PEDOT structure, which is prepared by a method including the following steps: first synthesizing Fe3O4 nanoparticles, then polymerizing PEDOT in situ on its surface to form a conductive intermediate layer, and finally coating the SiO2 outer layer by a sol-gel method.

5. The preparation method according to claim 4, characterized in that, In the SiO2@Fe3O4@PEDOT core-shell structure, the Fe3O4 core has a particle size of 100-500nm, the PEDOT intermediate layer has a thickness of 10-50nm, and the SiO2 outer layer has a thickness of 5-10nm.

6. The preparation method according to claim 1, characterized in that, The conditions of the hot-press sintering in step (3) are: increasing the temperature to 420-480℃ at a heating rate of 3-8℃ / min, applying a pressure of 15-25MPa and keeping for 1-3h; the vacuum degree of the vacuum environment is ≤10 -2 Pa.

7. A multi-field synergistically driven smart responsive aluminum foam composite material prepared by the preparation method according to any one of claims 1-6, characterized in that, The composite material has an integrated porous structure consisting of a three-dimensional NiTi fiber skeleton and an aluminum-based composite slurry, with a porosity of 25-40% and a pore size distribution of 50-600 μm. It can also generate controllable strain in response to magnetic, electric and temperature fields.

8. The smart responsive aluminum foam composite material according to claim 7, characterized in that, It can generate at least 10% basic compressive strain under a 100mT magnetic field; by applying a 3VDC voltage on the basis of the magnetic field driving, it can achieve micro-strain control of more than ±1% within 0.5s, with a strain accuracy of ≤±0.2%.

9. The smart responsive aluminum foam composite material according to claim 7, characterized in that, It should have a strain decay rate of ≤ 5% and a response time change rate of ≤ 8% after 5 x 10 4 cycles of magnetic-electric co-actuation at 60°C / 90% relative humidity.

10. The smart responsive aluminum foam composite material according to claim 7, characterized in that, Its compressive strength is ≥30MPa and its fracture toughness is ≥4.5kJ / m².