Preparation method of carbon nanotube aerogel filled porous titanium anti-explosion composite material

Abstract

The invention relates to the technical field of design, preparation and application of anti-explosion composite materials, in particular to a preparation method of a carbon nanotube aerogel filled porous titanium anti-explosion composite material, which comprises the following steps: mixing and sintering titanium powder and a pore forming agent into a porous titanium matrix, treating with a solution containing fluorine ammonium titanate, hydrogen peroxide and nano-silver, and growing Ag-TiO2 nanotubes on pore walls; the preparation method comprises the following steps: acidifying and aminating a carbon nanotube, preparing a dispersion liquid from the carbon nanotube, chitosan and the like, carrying out vacuum impregnation on porous titanium, and carrying out cross-linking curing through glutaraldehyde and HDI (Hexamethylene Diisocyanate); carrying out supercritical CO2 drying to form aerogel, and carrying out high-temperature treatment to carbonize chitosan and generate B4C nanoparticles; a gradient structure can be formed, and self-repairing and intelligent monitoring functions are integrated. The composite material prepared by the method has the advantages of excellent anti-explosion performance, capability of efficiently attenuating shock waves, strong interface bonding, stable structure, self-repairing and intelligent monitoring functions, corrosion resistance, low cost and suitability for industrial application.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of design, preparation and application of anti-blast composites, in particular to a preparation method of carbon nanotube aerogel filled porous titanium anti-blast composite. BACKGROUND

[0002] Anti-blast composites bear the key mission of efficiently attenuating blast shock waves, dissipating energy and achieving lightweight in the fields of aerospace, national defense and industry safety, but the limitations of traditional materials restrict their development. The density of aluminum foam in metal foam is ≥200 kg / m 3 , and it is easy to collapse under impact, with an energy absorption efficiency often below 100 kJ / m 3 . Ceramic matrix composites, although high in hardness, are difficult to meet the lightweight demand due to their brittleness and high cost. Porous titanium has advantages such as low density of 4.5 g / cm 3 , but a single structure will quickly fail due to stress concentration when facing shock waves.

[0003] The difficulties of existing technologies further exacerbate application challenges. Traditional porous titanium preparation processes use powder metallurgy, which is difficult to precisely control porosity and pore size distribution, with porosity fluctuation of ±10% and pore size deviation of ±50 μm, resulting in uneven distribution of filling materials and interface bonding strength of less than 2 MPa. Even if the carbon nanotube aerogel has excellent performance, the filling rate in the porous titanium channel is less than 50%, and there is a lack of effective anchoring means. Carbon nanotubes themselves are prone to agglomeration due to van der Waals forces, and traditional acid treatment introduces few functional groups. The existing filling process cannot overcome the surface tension of the dispersion liquid, and the aerogel structure collapses and the density increases sharply during drying. In addition, existing composites have single function, cannot repair microcracks generated by impact, are difficult to monitor damage in real time, and have poor corrosion resistance, which cannot adapt to harsh environments.

[0004] To overcome these difficulties, the present application develops an integrated process of "functionalization of porous titanium surface-multi-modification of carbon nanotubes-vacuum pulse impregnation-supercritical drying". TiO2 nanotube arrays are grown on the pore walls of porous titanium using a mixed solution of ammonium fluorotitanate and hydrogen peroxide, and the interface bonding strength is increased to more than 5 MPa by combining nano-silver particles with carbon nanotube amination treatment. Carbon nanotubes are triple-modified by mixed acid oxidation, APTES amination and polydopamine coating, and combined with pulse pressure vacuum impregnation to achieve high filling rate of 85-95% and uniform distribution with deviation <5% of the aerogel in the porous titanium channel. Carbon borane derivatives and piezoelectric nanofibers are introduced, the former decomposes to achieve microcrack self-repairing with strength recovery rate exceeding 80%, and the latter converts impact energy into electrical signals to achieve real-time damage monitoring.

[0005] (I) Technical problems solved

[0006] In view of the deficiencies of the prior art, the application provides a preparation method of a carbon nanotube aerogel filled porous titanium blast-resistant composite material.

[0007] (ii) Technical solutions

[0008] The preparation method of the carbon nanotube aerogel filled porous titanium blast-resistant composite material comprises the following steps:

[0009] S1: Pretreatment of a porous titanium matrix

[0010] Titanium powder is mixed with a pore-forming agent, cold-pressed into a shape, and then sintered under the protection of argon to form a porous titanium matrix; then the matrix is immersed in a mixed solution containing ammonium fluoride, hydrogen peroxide and nano silver particles, and TiO2 nanotube arrays are grown in situ on the surface of the pore wall, the nano silver particles are uniformly distributed on the surface of the nanotube, an Ag-TiO2 heterojunction is formed, and the reaction is as follows:

[0011]

[0012] S2: Preparation of a functionalized carbon nanotube dispersion

[0013] Multi-walled carbon nanotubes are added to mixed acid, ultrasonically dispersed and then subjected to acid treatment; then 3-aminopropyltriethoxysilane APTES and dopamine are added, and reflux reaction is carried out at 80-100 DEG C for 6-12 hours to realize amino functionalization and form a polydopamine coating layer, and the reaction formula is as follows:

[0014]

[0015] The functionalized carbon nanotubes are dispersed in deionized water, and chitosan, graphene quantum dots GQDs and carborane derivatives are added, ultrasonic homogenization is carried out, and a stable dispersion is formed; the structure formula of the carborane derivative is as follows:

[0016]

[0017] S3: Vacuum impregnation and cross-linking curing

[0018] The pretreated porous titanium matrix is placed in a vacuum impregnation tank, vacuum injection of the carbon nanotube dispersion is carried out, and the pressure is kept at 0.5-1 MPa for 2-4 hours; then the temperature is raised to 60-80 DEG C, nitrogen containing glutaraldehyde vapor and hexamethylene diisocyanate HDI is introduced, cross-linking curing is carried out, and a double cross-linking network is formed;

[0019] S4: Supercritical drying and formation of carbon aerogel

[0020] The impregnated and solidified composite material is transferred to a high-pressure reactor, replaced with liquid CO2, and then heated to 35-40°C and slowly depressurized. Finally, it is heat-treated at 800-1000°C in an argon atmosphere, carbonizing the chitosan and decomposing the carborane derivative to form B4C nanoparticles uniformly distributed in the carbon nanotube network, forming a B4C@CNT reinforcing phase.

[0021] Preferably, the process further comprises a S0 pretreatment step: annealing the titanium powder in an argon atmosphere containing 5-10 vol% hydrogen at 400-600°C for 1-3 hours to form a TiH2 activation layer with a thickness of 5-20 nm on the surface of the titanium powder.

[0022] Preferably, the process further comprises a S2.5 in-situ polymerization step: adding 0.5-2 wt% aniline monomer and 0.05-0.2 wt% ammonium persulfate initiator to the functionalized carbon nanotube dispersion, and stirring at 20-30°C for 6-12 hours to allow in-situ polymerization of polyaniline PANI on the surface of the carbon nanotube to form a CNT@PANI core-shell structure, with a polyaniline coating layer thickness of 10-50 nm.

[0023] Preferably, the vacuum impregnation in S3 uses a pulse pressure mode: cyclically increasing and decreasing the pressure at a rate of 0.1 MPa / s in the range of 0.1-1 MPa, with a 30-second holding time for each cycle, and a total of 10-30 cycles.

[0024] Preferably, during the supercritical drying process in S4, ultrasonic vibrations with a frequency of 20-50 kHz and a power of 50-200 W are introduced during the depressurization stage.

[0025] Preferably, in the prepared composite material, the interfacial bonding strength between the carbon nanotube aerogel and the porous titanium matrix is ≥5 MPa, and through nanoindentation testing, the interface region exhibits a gradient in mechanical properties, with the hardness gradually decreasing from the titanium matrix to the aerogel, with a gradient range of 1-5 GPa / mm.

[0026] Preferably, the prepared composite material has a layered gradient structure, divided into three layers along the thickness direction: an outer dense titanium layer, a middle carbon nanotube aerogel-filled porous titanium layer, and an inner honeycomb-shaped porous titanium layer, with a transition zone between the three layers to achieve a gradual change in performance.

[0027] Preferably, the prepared composite material has a areal density of 5-10 kg / m 2 and a peak pressure attenuation rate of 70-90% and an energy absorption efficiency of 150-300 kJ / kg against 1-10 MPa explosive shock waves.

[0028] Preferably, the prepared composite material has self-repairing function: when the material is impacted to generate micro-cracks, the carbon borane derivative at the crack tip decomposes to generate B2O3 glass phase at high temperature, which flows to fill the cracks at 500-800 DEG C to realize self-repairing.

[0029] Preferably, the prepared composite material can be used as an intelligent anti-explosion structure, and through integration of 0.1-1 wt% piezoelectric nanofibers in the carbon nanotube network, impact energy can be collected and monitored, and the output voltage signal has linear relationship with impact strength, so that the damage state of the material can be monitored in real time.

[0030] (III) Beneficial effects

[0031] Compared with the prior art, the beneficial effects of the present application are:

[0032] 1. When the areal density is 5-10 kg / m 2 , the peak pressure attenuation rate of 1-10 MPa explosion shock wave is extremely high, and the attenuation rate is greatly improved compared with that of pure porous titanium. The three-dimensional network structure of the carbon nanotube aerogel cooperates with the porous titanium, reflects and scatters the impact wave energy multiple times, and realizes multi-stage dissipation of "wave energy-thermal energy-mechanical energy". At the same time, the compression strength and impact toughness of the composite material are improved compared with those of pure titanium, and the performance retention rate is still extremely high, and the fatigue resistance is excellent.

[0033] 2. Through the dual action of chemical bonding (Si-O-Ti) and physical entanglement between TiO2 nanotube array (tube length 1-3 um) and carbon nanotube, the interfacial shear strength is improved, and the enhancement is higher than that of traditional mechanical embedding. The supercritical drying process effectively avoids the shrinkage and collapse of the aerogel by replacing CO2 at a rate of 0.1-0.5 MPa / min, so that the material maintains a low density of 0.03-0.15 g / cm 3 and a high specific surface area of 500-1000 m 2 / g, and the structural integrity is much higher than that of the material dried at normal pressure. In addition, a three-layer gradient structure design of outer dense titanium layer, intermediate filling layer and inner honeycomb-shaped porous titanium is adopted, so that the performance gradually changes from high stiffness to high energy absorption, the stress transfer efficiency is improved, and the stress concentration problem of traditional single structure is successfully avoided.

[0034] 3. The B2O3 glass phase generated by the decomposition of carbon borane derivative flows to fill the micro-cracks at 500-800 DEG C, and the strength recovery rate of the repaired material is extremely high, which greatly prolongs the service life; the integrated ZnO piezoelectric nanofiber can convert the impact energy into an electric signal, and the output voltage has a high linear relationship with the impact pressure (R 2>0.99), achieving real-time impact strength monitoring. In terms of corrosion resistance, the Ag-TiO2 heterojunction and carbon nanotube aerogel form a physical barrier, reducing the corrosion rate of the material in a 3.5wt% NaCl solution to ≤0.01mm / year, higher than that of pure titanium; the high thermal conductivity of the carbon nanotube network 5-15W / (m·K) can quickly conduct impact heat and prevent performance degradation caused by local overheating.

[0035] 4. Precise control of porosity ±2% is achieved by the quantitative relationship between pore-forming agent content and porosity (porosity = 40 + 40 × pore-forming agent mass / titanium powder mass); the filling efficiency is greatly improved and the production cycle is shortened through 10-30 cycles of pulse pressure vacuum impregnation process. In green manufacturing and cost control, the solvent recovery rate of supercritical CO2 drying process is extremely high, combined with the low-cost large-scale preparation technology of carbon nanotube aerogel, the overall cost of the composite material is lower than that of ceramic-based blast-resistant materials, and it has outstanding industrialization promotion value. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is a preparation flowchart of carbon nanotube aerogel filled porous titanium blast-resistant composite material;

[0037] Figure 2 is a comparative bar chart of porosity and average pore size of examples and comparative examples;

[0038] Figure 3 is a comparative line chart of performance retention rate and shock wave attenuation rate of examples and comparative examples after 5 cycles;

[0039] Figure 4 is a comparative bar line chart of aerogel density and specific surface area of examples and comparative examples. DETAILED DESCRIPTION

[0040] According to Figures 1 to 4 , the specific embodiments of the present application are as follows:

[0041] I. Material and equipment preparation

[0042] Raw material specifications: provided by the company, purity ≥99.5%, particle size 5-30μm; ammonium bicarbonate is an analytical pure product with a particle size of 50-200μm, supplied by the National Pharmaceutical Group Chemical Reagent Co., Ltd.; ammonium fluorotitanate is provided by Shanghai Aladdin Biochemical Technology Co., Ltd., with a purity of ≥98% and a particle size of ≤50μm; multi-walled carbon nanotubes provided by Shenzhen Nanonets Co., Ltd., with a tube diameter of 10-30nm, a length of 5-20μm, and a purity of ≥95%; 3-aminopropyltriethoxysilane (APTES) with a purity of ≥98% is supplied by Nanjing Chuangshi Chemical Co., Ltd.; carbon borane derivatives (C2B 10 H 12) prepared by self-made vapor deposition method, purity ≥95%; Nanometer silver particles with particle size of 10-50 nm and purity ≥99.9% are provided by Suzhou Nanometer Technology Co., Ltd.

[0043] Main equipment: ZSK-1200 vacuum sintering furnace, maximum temperature 1300℃, argon flow rate 5-20 L / min; KQ-500DE ultrasonic dispersing instrument, power 500W, frequency 40 kHz; GSH-100 high-pressure reaction kettle, volume 100 L, maximum pressure 20 MPa, temperature application range from room temperature to 200℃; TI950 nano indenter, load range 0.1-100 mN, displacement resolution 0.1 nm; and Mastersizer 3000 laser particle size analyzer, detection range covering 0.01-3500 μm.

[0044] Example 1: Preparation by standard process

[0045] Formulation

[0046] 100 parts of titanium powder (particle size 20 μm), 40 parts of ammonium bicarbonate (as a pore-forming agent, porosity target 56%), 1.5 parts of ammonium fluorotitanate (solution concentration 1.5 wt%), 2.0 parts of hydrogen peroxide (solution concentration 2 wt%), 0.05 parts of nanometer silver particles (particle size 30 nm), 5 parts of multi-walled carbon nanotubes (acidified carboxyl content 1.3 mmol / g), 0.8 parts of APTES (amino reagent), 0.3 parts of chitosan (molecular weight 100,000, solution concentration 0.3 wt%) and 0.03 parts of carborane derivative (C2B 10 H 12 , purity 95%).

[0047] Preparation steps

[0048] Pre-treatment of porous titanium matrix (S1)

[0049] Titanium powder and ammonium bicarbonate were mixed at a ratio of 1:0.4 and cold-pressed into a Φ50 mm×10 mm cylindrical blank under a pressure of 80 MPa. The blank was placed in a vacuum sintering furnace and sintered at 1250℃ for 3 hours under an argon atmosphere (oxygen content ≤5 ppm), and then cooled in the furnace to obtain a matrix with a porosity of 56% and an average pore size of 200 μm. The matrix was immersed in a mixed solution containing 1.5 wt% ammonium fluorotitanate, 2 wt% hydrogen peroxide and 0.05 wt% nanometer silver, and stirred in a 70℃ water bath for 1.5 hours to form a 50-100 nm TiO2 nanotube array on the pore wall and load Ag particles (particle size 30 nm) on the surface.

[0050] Preparation of functionalized carbon nanotube dispersion (S2)

[0051] Carbon nanotubes were mixed with a mixture of concentrated sulfuric acid and concentrated nitric acid (3:1) at a mass ratio of 1:10, ultrasonically dispersed for 3 hours, and washed by centrifugation until neutral to obtain carboxylated CNT (-COOH content 1.3 mmol / g). APTES (16% of the mass of CNT) and 0.3 wt% dopamine were added, and refluxed at 85°C for 8 hours to obtain a polydopamine coating layer with an amino content of 0.9 mmol / g. The dispersion was obtained by dispersing in deionized water, adding 0.3 wt% chitosan, 0.1 wt% graphene quantum dots, and 0.03 wt% carborane derivative, and ultrasonically homogenizing (600 W) for 1.5 hours to form a dispersion of 8 mg / mL (zeta potential +40 mV).

[0052] Vacuum impregnation and cross-linking curing (S3)

[0053] The porous titanium matrix was pumped to 5 Pa in a vacuum tank, and after maintaining for 30 minutes, the dispersion was injected. The pressure was increased to 0.8 MPa at a rate of 0.1 MPa / s, and the pressure was cycled (0.1-0.8 MPa) for 20 times, and the pressure was maintained for 3 hours. The temperature was increased to 70°C, and nitrogen containing 3 vol% glutaraldehyde and 0.5 vol% HDI was introduced, and cross-linking curing was performed for 18 hours to form a double cross-linking network.

[0054] Supercritical drying and high-temperature treatment (S4)

[0055] The reaction kettle was transferred to a high-pressure reaction kettle, and the solvent was replaced with liquid CO2 (45°C, 9 MPa), and the replacement was performed 6 times, each time 3 times the volume of the kettle. The temperature was increased to 38°C (supercritical state), and the pressure was released at a rate of 0.2 MPa / min, and at the same time, 30 kHz, 100 W ultrasonic waves were applied to form an aerogel with a density of 0.12 g / cm 3 The temperature was increased to 900°C in an argon atmosphere for 3 hours, and the carbonization rate of chitosan was 45%, and the carborane was decomposed to form B4C nanoparticles with a size of 50 nm.

[0056] Example 2: High filling rate process

[0057] Formulation

[0058] The formulation included 100 parts of titanium powder (particle size 20 μm), 50 parts of ammonium bicarbonate (as a pore-forming agent, with a porosity target of 60%), 1.5 parts of ammonium fluorotitanate (solution concentration 1.5 wt%), 2.0 parts of hydrogen peroxide (solution concentration 2 wt%), 0.05 parts of silver nanoparticles (particle size 30 nm), 5 parts of multi-walled carbon nanotubes (carboxyl content 1.3 mmol / g after acidification), 0.8 parts of APTES (amino reagent), 0.3 parts of chitosan (molecular weight 100,000, solution concentration 0.3 wt%), and 0.03 parts of carborane derivative (C2B 10 H 12 , purity 95%).

[0059] Preparation steps

[0060] Porous titanium matrix pretreatment (S1)

[0061] Titanium powder was mixed with ammonium bicarbonate at a ratio of 1:0.5 and cold-pressed into a Φ50 mm x 10 mm cylindrical blank under a pressure of 80 MPa. The blank was placed in a vacuum sintering furnace and sintered at 1250°C for 3 hours in an argon atmosphere (oxygen content ≤5 ppm). After furnace cooling, a matrix with a porosity of 60% and an average pore size of 150 μm was obtained. The matrix was immersed in a mixed solution containing 1.5 wt% ammonium fluorotitanate, 2 wt% hydrogen peroxide, and 0.05 wt% nano-silver, and stirred in a water bath at 70°C for 1.5 hours. A 50-100 nm TiO2 nanotube array was formed on the pore wall, and Ag particles (particle size 30 nm) were loaded on the surface.

[0062] Preparation of functionalized carbon nanotube dispersion (S2)

[0063] Carbon nanotubes were mixed with mixed acid (concentrated sulfuric acid: concentrated nitric acid = 3:1) at a mass ratio of 1:10, ultrasonically dispersed for 3 hours, and washed by centrifugation until neutral to obtain carboxylated CNT (-COOH content 1.3 mmol / g). APTES (16% of the mass of CNT) and 0.3 wt% dopamine were added, and refluxed at 85°C for 8 hours. The amino content was 0.9 mmol / g, and a polydopamine coating layer was formed on the surface. The dispersion was dispersed in deionized water, and 0.3 wt% chitosan, 0.1 wt% graphene quantum dots, and 0.03 wt% carborane derivative were added, and ultrasonically homogenized (600 W) for 1.5 hours to form a dispersion of 8 mg / mL (Zeta potential +40 mV).

[0064] Vacuum impregnation and crosslinking curing (S3)

[0065] The porous titanium matrix was evacuated to 5 Pa in a vacuum tank, and after holding for 30 minutes, the dispersion was injected. The pressure was increased to 1 MPa at a rate of 0.1 MPa / s, and a cyclic pulse pressure (0.1-1 MPa) was applied for 30 times, and the pressure was maintained for 3 hours. The temperature was increased to 70°C, and nitrogen gas containing 3 vol% glutaraldehyde and 0.5 vol% HDI was introduced, and crosslinking curing was performed for 18 hours to form a double crosslinking network.

[0066] Supercritical drying and high temperature treatment (S4)

[0067] The reaction kettle was transferred to a high pressure reaction kettle, and liquid CO2 (45°C, 9 MPa) was used to replace the solvent. The replacement was performed 6 times, each time 3 times the volume of the kettle. The temperature was increased to 38°C (supercritical state), and the pressure was released at a rate of 0.2 MPa / min, while applying 30 kHz, 200 W ultrasonic waves to form an aerogel with a density of 0.08 g / cm 3 The reaction kettle was transferred to a high pressure reaction kettle, and liquid CO2 (45°C, 9 MPa) was used to replace the solvent. The replacement was performed 6 times, each time 3 times the volume of the kettle. The temperature was increased to 38°C (supercritical state), and the pressure was released at a rate of 0.2 MPa / min, while applying 30 kHz, 200 W ultrasonic waves to form an aerogel with a density of 0.08 g / cm

[0068] Key performance

[0069] Carbon nanotube filling rate 95%, interface bonding strength 5.2 MPa (nanoindentation test).

[0070] Impact energy absorption efficiency 280 kJ / kg, 20% higher than Example 1.

[0071] Example 3: Intelligent monitoring process

[0072] Formulation

[0073] Titanium powder 100 parts (particle size 20 μm), ammonium bicarbonate 40 parts (as a pore-forming agent, porosity target 56%), ammonium fluorotitanate 1.5 parts (solution concentration 1.5 wt%), hydrogen peroxide 2.0 parts (solution concentration 2 wt%), nano-silver particles 0.05 parts (particle size 30 nm), multi-walled carbon nanotubes 5 parts (carboxyl content 1.3 mmol / g after acidification), APTES 0.8 parts (amino reagent), chitosan 0.3 parts (molecular weight 100,000, solution concentration 0.3 wt%), carborane derivative 0.03 parts (C2B 10 H 12 , purity 95%) and ZnO piezoelectric nanowires 0.5 parts (addition amount in dispersion liquid 0.5 wt%, diameter 50 nm, length 2 μm).

[0074] Preparation steps

[0075] Porous titanium matrix pretreatment (S1)

[0076] Titanium powder and ammonium bicarbonate were mixed at a ratio of 1:0.4 and cold-pressed into a Φ50 mm x 10 mm cylindrical blank under a pressure of 80 MPa (outer dense titanium layer thickness 1.5 mm, intermediate filling layer and inner layer composite structure). Placed in a vacuum sintering furnace, sintered at 1250°C for 3 hours under argon atmosphere (oxygen content ≤5 ppm), and after furnace cooling, a gradient matrix was obtained with an outer dense titanium layer (no obvious pores), an intermediate filling layer with a porosity of 55%, and an inner layer with a honeycomb-shaped titanium porosity of 75%. The matrix was immersed in a mixed solution containing 1.5 wt% ammonium fluorotitanate, 2 wt% hydrogen peroxide and 0.05 wt% nano-silver, and stirred in a 70°C water bath for 1.5 hours, forming a 50-100 nm TiO2 nanotube array on the pore wall and loading Ag particles (particle size 30 nm) on the surface.

[0077] Preparation of functionalized carbon nanotube dispersion (S2)

[0078] Carbon nanotubes were mixed with a mixture of concentrated sulfuric acid and concentrated nitric acid (3:1) at a mass ratio of 1:10, ultrasonically dispersed for 3 hours, and washed by centrifugation until neutral to obtain carboxylated CNTs (-COOH content 1.3 mmol / g). APTES (16% of the mass of CNTs) and 0.3 wt% dopamine were added, and refluxed at 85°C for 8 hours to obtain a polydopamine coating layer with an amino content of 0.9 mmol / g. The dispersion was obtained by dispersing in deionized water, adding 0.3 wt% chitosan, 0.1 wt% graphene quantum dots, 0.03 wt% carborane derivatives, and 0.5 wt% ZnO piezoelectric nanowires, and ultrasonically homogenizing (600 W) for 1.5 hours to form a dispersion of 8 mg / mL (zeta potential +40 mV).

[0079] Vacuum impregnation and cross-linking curing (S3)

[0080] The porous titanium matrix was pumped to 5 Pa in a vacuum tank, and after maintaining for 30 minutes, the dispersion was injected. The pressure was increased to 0.8 MPa at a rate of 0.1 MPa / s, and the microchannels (pore size 50 μm) of the outer dense titanium layer were preferentially filled. The dispersion was allowed to penetrate into the inner macroporous structure by recirculating pulse pressure (0.1-0.8 MPa) for 20 times, and the pressure was maintained for 3 hours. The temperature was increased to 70°C, and nitrogen containing 3 vol% glutaraldehyde and 0.5 vol% HDI was introduced for cross-linking and curing for 18 hours to form a double cross-linked network.

[0081] Supercritical drying and high-temperature treatment (S4)

[0082] The reaction kettle was transferred to a high-pressure reaction kettle, and the solvent was replaced with liquid CO2 (45°C, 9 MPa) for 6 times, each time 3 times the volume of the kettle. The temperature was increased to 38°C (supercritical state), and the pressure was released at a rate of 0.2 MPa / min while applying 30 kHz, 100 W ultrasonic waves to form an aerogel with a density of 0.12 g / cm 3 The temperature was increased to 900°C in an argon atmosphere for 3 hours, and the carbonization rate of chitosan was 45%. The carborane was decomposed to form B4C nanoparticles with a size of 50 nm.

[0083] Comparative example: traditional process

[0084] Formulation and process

[0085] Porous titanium matrix: TiO2 nanotubes were not grown, and non-functionalized carbon nanotubes (not aminated, dispersion concentration 3 mg / mL) were directly filled.

[0086] Filling process: atmospheric pressure impregnation, oven drying (80°C, 24 hours), and no supercritical treatment. The carbon pore structure performance of the examples and the comparative example is compared as follows:

[0087] Table 1

[0088] Group Example 1 Example 2 Comparative Example Porosity (%) 56 60 55 Average pore size (pm) 200 150 220 Aerogel density (g / cm 3 )]]> 0.12 0.08 0.60 Specific surface area (m 2 / g) 800 900 150

[0089] Mechanical properties of the examples and comparative examples were tested as follows:

[0090] Table 2

[0091] Group Example 1 Example 3 Comparative Example Compressive strength (MPa) 220 250 100 impact strength (kJ / m 2 ) 45 50 20 Interfacial shear strength (MPa) 5.1 5.3 1.0 Strength recovery rate after repair 85％ 88％ None

[0092] The blast resistance of the examples and comparative examples were compared as follows:

[0093] Table 3

[0094]

[0095]

[0096] Summary: This table presents the performance of the materials at different carbon nanotube filling rates. Example 1 and Example 2 correspond to carbon nanotube filling rates of 92% and 95% respectively, and the comparative example is at a filling rate of 45%. Compared to the comparative example, the examples have significant improvements in peak pressure decay rate, energy absorption efficiency, mass efficiency, performance retention after 5 cycles, and shock wave decay rate. This shows that increasing the carbon nanotube filling rate can effectively enhance the energy absorption, impact resistance, and cyclic use performance of the material.

[0097] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a carbon nanotube aerogel-filled porous titanium blast- resistant composite material, characterized by, Comprising the following steps: S1: porous titanium substrate pretreatment Mix titanium powder with pore-forming agent, cold-pressing forming, then sintering under argon protection to form a porous titanium substrate; then immerse the substrate in a mixed solution containing ammonium fluoride, hydrogen peroxide and nano silver particles, grow TiO2 nanotube arrays in situ on the pore wall surface, nano silver particles are uniformly distributed on the surface of nanotube, form Ag-TiO2 heterojunction, reaction: S2: preparation of functionalized carbon nanotube dispersion Add multi-walled carbon nanotubes to mixed acid, ultrasonic dispersion and acid treatment; then add 3-aminopropyl triethoxysilane APTES and dopamine, reflux at 80-100℃ for 6-12 hours to realize amino functionalization and form a polydopamine coating layer, the reaction formula is: The functionalized carbon nanotubes are dispersed in deionized water, and chitosan, graphene quantum dots GQDs and carborane derivatives are added, and ultrasonic homogenization is performed to form a stable dispersion liquid; the structural formula of the carborane derivative is: S3: vacuum impregnation and cross-linking curing Place the pretreated porous titanium substrate in a vacuum impregnation tank, inject carbon nanotube dispersion after vacuumizing, keep at 0.5-1MPa pressure for 2-4 hours; then heat to 60-80℃, introduce nitrogen containing glutaraldehyde vapor and hexamethylene diisocyanate HDI, cross-linking and curing to form a double cross-linking network; S4: supercritical drying and carbon aerogel formation Transfer the impregnated and cured composite material to a high-pressure reaction kettle, replace the solvent with liquid CO2, then heat to 35-40℃ and slowly release the pressure; finally heat treat at 800-1000℃ in argon atmosphere, chitosan carbonizes and carbon borane derivative decomposes to form B4C nanoparticles uniformly distributed in the carbon nanotube network, forming a B4C@CNT reinforcing phase.

2. The method for preparing the carbon nanotube aerogel-filled porous titanium explosion-resistant composite material according to claim 1, characterized in that, Also includes S0 pretreatment step: anneal titanium powder in argon atmosphere containing 5-10vol% hydrogen at 400-600℃ for 1-3 hours to form a TiH2 activation layer with a thickness of 5-20nm on the surface of the titanium powder.

3. The preparation method of the carbon nanotube aerogel-filled porous titanium explosion-resistant composite material according to claim 1, characterized in that, Also includes S2.5 in-situ polymerization step: add 0.5-2wt% aniline monomer and 0.05-0.2wt% ammonium persulfate initiator to the functionalized carbon nanotube dispersion, stir at 20-30℃ for 6-12 hours to allow polyaniline PANI to in-situ polymerize and coat on the surface of the carbon nanotube, forming a CNT@PANI core-shell structure, the polyaniline coating layer is 10-50nm thick.

4. The preparation method of the carbon nanotube aerogel-filled porous titanium explosion-resistant composite material according to claim 1, characterized in that, The vacuum impregnation in S3 uses pulse pressure mode: cyclically increase and decrease the pressure at a rate of 0.1MPa / s in the range of 0.1-1MPa, each cycle includes a 30-second pressure holding time, and the total number of cycles is 10-30.

5. The method of making a carbon nanotube aerogel filled porous titanium blast- resistant composite material of claim 1, wherein, In the supercritical drying process in S4, introduce ultrasonic vibration with a frequency of 20-50kHz during the pressure release stage, and the ultrasonic power is 50-200W.

6. The method of making a carbon nanotube aerogel filled porous titanium blast- resistant composite material of claim 1, wherein, The interface bonding strength between the carbon nanotube aerogel and the porous titanium substrate in the prepared composite material is ≥5MPa, and the interface region shows a gradient mechanical property through nanoindentation testing, the hardness gradually decreases from the titanium substrate to the aerogel, and the gradient range is 1-5GPa / mm.

7. The method of making a carbon nanotube aerogel filled porous titanium blast- resistant composite material of claim 1, wherein, The prepared composite material has a layered gradient structure, which is divided into three layers along the thickness direction: the outer layer is a dense titanium layer, the middle layer is a carbon nanotube aerogel filled porous titanium, and the inner layer is a honeycomb-shaped porous titanium, and the three layers are connected through a transition zone to realize performance gradient.

8. The method for preparing the carbon nanotube aerogel-filled porous titanium explosion-resistant composite material according to claim 1, characterized in that, The prepared composite material has a peak pressure attenuation rate of 70-90% and an energy absorption efficiency of 150-300 kJ / kg to a peak pressure of 1-10 MPa explosion shock wave when the areal density is 5-10 kg / m 2 2.

9. The method of making a carbon nanotube aerogel filled porous titanium blast- resistant composite material of claim 1, wherein, The prepared composite material has a self-repairing function: when the material is impacted to generate micro-cracks, the carbon borane derivative at the crack tip is decomposed to generate B2O3 glass phase at high temperature, which flows to fill the cracks under the condition of 500-800 ℃, so that self-repairing is realized.

10. The method for preparing the carbon nanotube aerogel-filled porous titanium explosion-resistant composite material according to claim 1, characterized in that, The prepared composite material can be used as an intelligent anti-explosion structure, through integrating 0.1-1 wt% piezoelectric nanofibers in the carbon nanotube network, the impact energy can be collected and monitored, the output voltage signal has a linear relationship with the impact strength, and the damage state of the material can be monitored in real time.

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