A 3D-printed aramid wave-absorbing honeycomb material, a preparation method and application thereof

Abstract

The application discloses 3D printing aramid wave-absorbing honeycomb material and a preparation method and application thereof, utilizes wave-absorbing agents with nano-scale structure and excellent electrical properties and aramid nanofibers with excellent mechanical properties to be tightly combined through hydrogen bonds, and advantages that the surface of the wave-absorbing agents and the aramid nanofibers is easy to produce a strong network cross-linking structure, and the mechanical properties of the 3D printing aramid wave-absorbing honeycomb material are improved, a new aramid nanofiber-based material with good wave-absorbing performance and mechanical properties is developed, and the defects of the current wave-absorbing honeycomb material, such as a large weight of a surface coating and easy peeling, are solved, and the application demand in the fields of aerospace, radar stealth technology and the like can be met. The 3D printing technology is used to print aramid wave-absorbing honeycomb materials with different sizes and densities, energy consumption is low, printing precision is high, the process is simple, the 3D printing aramid wave-absorbing honeycomb material has excellent mechanical properties, good wave-absorbing performance, strong structure designability, and a wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of 3D printing method and wave-absorbing material, and particularly relates to a 3D printed aramid wave-absorbing honeycomb material, a preparation method and application thereof. BACKGROUND

[0002] With the development of electronic information technology, the massive use of various electronic and electrical products, the electromagnetic environment becomes more and more complex, and the problem of electromagnetic pollution is becoming more and more serious. At the same time, using radar wave-absorbing material can effectively reduce the radar wave reflection intensity of aircraft and ships, and thus achieve the purpose of "stealth". In order to solve the harm caused by electromagnetic radiation and meet the stealth demand of modern aerospace technology, it is of great practical significance to develop high-performance wave-absorbing materials.

[0003] Honeycomb structure has the characteristics of high compressive strength, high specific strength and high specific stiffness, and is a very potential material. Compared with bulk wave-absorbing materials, honeycomb wave-absorbing materials have better wave-absorbing efficiency under multi-polarization and large-angle oblique incidence, and have excellent mechanical properties, and are used as structure-function integrated materials in the field of electromagnetic wave absorption. The honeycomb wave-absorbing material is mostly made of aramid or glass fiber hexagonal or quadrangular honeycomb as a substrate, and is formed by impregnating a resin pre-impregnated material containing an electric loss type or a magnetic loss type absorbent, or directly filling a resistance layer or a foam body with electromagnetic loss function in the honeycomb. It is difficult to design the electromagnetic performance of the patterned structure of the honeycomb by traditional process. In recent years, some researchers have designed the electrical properties of the honeycomb structure by using 3D printing technology in order to further break through the wave-absorbing performance of the material.

[0004] 3D printing is a kind of additive manufacturing technology, and its basic principle is layer manufacturing. It is mainly based on digital model, and is accumulated according to the layer thickness and predetermined trajectory of the printing model. Through layer-by-layer stacking, a specific structure model can be finally manufactured, and rapid prototyping can be realized. 3D printing integrates digital modeling, material science, and electromechanical control and many other scientific fields, and is a multi-disciplinary frontier technology. Compared with traditional manufacturing methods, 3D printing technology has the advantages of saving materials, high efficiency, personalized customization, and realizing complex structure manufacturing, and has great development potential in aerospace, automobile, medical, building, sensing and many other fields.

[0005] The Chinese patent application with the publication number CN110315747A disclosed on October 11, 2019 provides a high-strength honeycomb structure and a 3D printing forming method thereof, which can solve the technical problems existing in the honeycomb core material in some prior art, but it does not involve the wave-absorbing performance of the honeycomb structure; the Chinese patent application with the publication number CN110982111A disclosed on April 10, 2020 provides a preparation method of 3D printing aramid aerogel, which has simple process and short flow, and the obtained 3D aramid aerogel has ultralow density, good mechanical properties, and designable structure, and can be applied in the fields of thermal insulation, catalysis, separation / adsorption, sensing and soft robot, etc., but its mechanical properties are poor; the Chinese patent application with the publication number CN115322430A disclosed on November 11, 2022 provides a wave-absorbing aerogel composite material and a preparation method thereof, which solves the problems of no interaction between the existing filling type wave-absorbing honeycomb filler and the honeycomb hollow wall, easy falling off, etc., but the process is relatively complex and not easy to control. In summary, there is no public report on using aramid nanofiber as 3D printing ink to prepare aramid wave-absorbing honeycomb material by 3D printing technology.

[0006] Therefore, there is a need to solve the problems of poor mechanical properties and complex preparation process of the existing wave-absorbing honeycomb material. SUMMARY

[0007] The main purpose of the present application is to solve the problems of poor mechanical properties and complex preparation process of the existing wave-absorbing honeycomb material, and to provide a 3D printing aramid wave-absorbing honeycomb material and a preparation method and application thereof, which expands the application range of 3D printing and aramid wave-absorbing honeycomb material.

[0008] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0009] A preparation method of a 3D printing aramid wave-absorbing honeycomb material, comprising the following steps:

[0010] Step one: uniformly mixing para-aramid nanofiber, a wave-absorbing agent and a solvent by high-pressure homogenization to obtain an aramid nanofiber dispersion liquid;

[0011] Step two: using a freeze-direct writing forming method, taking the aramid nanofiber dispersion liquid obtained in step one as 3D printing ink, placing the 3D printing ink in a 3D printer storage bin for 3D printing to obtain a 3D printing aramid cryogel;

[0012] Step three: performing solvent replacement on the 3D printing aramid cryogel obtained in step two by using displacement solvent to obtain a 3D printing aramid hydrogel;

[0013] Step four: performing heating and drying treatment on the 3D printing aramid hydrogel obtained in step three to obtain a 3D printing aramid wave-absorbing honeycomb material.

[0014] Further, the mass ratio of the para-aramid nanofiber to the wave-absorbing agent in step one is (65-85):(35-15), the homogenization pressure is 800-5000 bar, and the homogenization times are 5-30; the solid content of the aramid nanofiber dispersion liquid is 0.1-10 wt%.

[0015] Further, the wave-absorbing agent in step one is any one or a combination of two or more of carbon nanotubes, graphene, MXene, conductive carbon black, carbonyl iron absorber, ferrite absorber, and metal and oxide superfine powder, and the solvent is any one or a combination of two or more of methanol, ethanol, dimethyl sulfoxide, or acetone.

[0016] Further, the temperature of the 3D printing in step two is -50-15 ℃, the inner diameter of the needle of the 3D printing is 30 μm-5 mm, and the printing speed of the 3D printing is 100 mm / min-3000 mm / min; the 3D printed aramid cryogel is in a honeycomb shape.

[0017] Further, the replacement solvent in step three is any one or a combination of two or more of pure water, saline, or phosphate buffer; the temperature of the solvent replacement is 0 ℃-10 ℃; the solvent replacement time is 10-24 h; and the solvent replacement times are 3-5.

[0018] Further, the heating and drying treatment in step four is vacuum heating and drying or atmospheric pressure heating and drying; the drying treatment is performed at 50 ℃-120 ℃; and the drying treatment time is 10 h-36 h.

[0019] A 3D printed aramid wave-absorbing honeycomb material is prepared by the above method.

[0020] Further, the density of the 3D printed aramid wave-absorbing honeycomb material is 30-500 kg / m 3 , the cell side length of the 3D printed aramid wave-absorbing honeycomb material is 1.5-10 mm, and the height of the 3D printed aramid wave-absorbing honeycomb material is 0.5-5 cm.

[0021] Further, the 3D printed aramid wave-absorbing honeycomb material is composed of a plurality of topologically arranged honeycomb units, the honeycomb unit is a regular hexagonal prism, the regular hexagonal prism is a cavity with open ends and an empty interior, and the honeycomb unit is formed by 3D printing.

[0022] A 3D printed aramid wave-absorbing honeycomb material is used in the preparation of a 3D printed aramid wave-absorbing honeycomb aerogel composite material.

[0023] Compared with the prior art, the application has the following beneficial technical effects:

[0024] The preparation method of the 3D printing aramid wave-absorbing honeycomb material provided by the application is accurate, fast, programmable, does not require complex synthesis technology, can be used to prepare various complex shapes, and is universal for various materials. In addition, the 3D printing aramid wave-absorbing honeycomb material does not need to be assembled, shortens the supply chain, and saves the cost of manpower and transportation. Through the freeze-direct writing forming method, the 3D printing aramid wave-absorbing honeycomb material is obtained by using the aramid nanofiber dispersion liquid containing para-aramid nanofibers and a wave-absorbing agent as 3D printing ink, thereby avoiding the complex preparation process of the traditional aramid wave-absorbing honeycomb material, which is first prepared into a honeycomb and then coated with a wave-absorbing coating on the surface. The 3D printing aramid wave-absorbing honeycomb material is one-step formed, the process is simple, the flow is short, and the 3D printing aramid wave-absorbing honeycomb material has excellent wave-absorbing performance. Different densities, different cell side lengths, and different heights of the 3D printing aramid wave-absorbing honeycomb material can be prepared by controlling the computer program of the 3D printer, so as to meet the application of the 3D printing aramid wave-absorbing honeycomb material in different environments and specific fields. The aramid wave-absorbing honeycomb material is obtained by heating and drying. Compared with freeze-drying, the shrinkage rate is larger, the combination between fibers is more compact, the aramid wave-absorbing honeycomb material has higher compressive strength in the T direction and higher shear strength in the L and W directions, has excellent mechanical properties, and can meet the application requirements of the aramid wave-absorbing honeycomb material in the fields of aerospace and radar stealth technology.

[0025] The application realizes good blending of the wave-absorbing agent and the aramid nanofiber by high-pressure homogenization treatment of the wave-absorbing agent, the para-aramid nanofiber, and the solvent. Compared with mechanical stirring, the wave-absorbing agent and the aramid nanofiber are subjected to strong shearing, impact, and cavitation under high pressure, forming a uniformly mixed emulsion system with good stability, avoiding problems such as uneven dispersion in the mechanical stirring process and flocculation of the material after stopping stirring, and thereby preventing the 3D printing ink from being blocked in the needle during the 3D printing process.

[0026] The 3D printing technology can be used to print aramid wave-absorbing honeycomb materials with different sizes and densities, has low energy consumption, high printing precision, and a simple process. The obtained 3D printing aramid wave-absorbing honeycomb material has excellent mechanical properties and good wave-absorbing performance, has strong designability of the structure, and has wide application prospects. The application utilizes the advantages of the wave-absorbing agent with a nano-scale structure and excellent electrical properties and the aramid nanofiber with excellent mechanical properties, which are tightly combined through hydrogen bonds and easily produce a strong network cross-linking structure due to the rich functional groups on the surface, to cooperatively improve the mechanical properties of the 3D printing aramid wave-absorbing honeycomb material, develop a new aramid nanofiber-based material with good wave-absorbing performance and mechanical properties, solve the defects of the current wave-absorbing honeycomb material, such as large weight of the surface coating and easy peeling, and meet the application requirements of the material in the fields of aerospace, radar stealth technology, and the like. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a process flow chart for preparing the present application. DETAILED DESCRIPTION

[0028] Embodiments of the present application are described in further detail below with reference to the accompanying drawings:

[0029] Referring to Figure 1 A preparation method of a 3D-printed aramid wave-absorbing honeycomb material comprises the following steps:

[0030] Step (1): uniformly mix para-aramid nanofibers, a wave-absorbing agent, and a solvent by high-pressure homogenization, wherein the mass ratio of para-aramid nanofibers to the wave-absorbing agent is (65-85):(35-15), the homogenization pressure is 800-5000 bar, and the homogenization frequency is 5-30 times, to obtain an aramid nanofiber dispersion liquid; the solid content of the aramid nanofiber dispersion liquid is 0.1-10 wt.%. The wave-absorbing agent is any one or a combination of two or more of carbon nanotubes, graphene, MXene, conductive carbon black, carbonyl iron absorber, ferrite absorber, and metal and oxide superfine powder, and the solvent is methanol, ethanol, dimethyl sulfoxide, or acetone.

[0031] Step (2): using the aramid nanofiber dispersion liquid as 3D-printing ink, place the 3D-printing ink in a 3D-printer storage bin, and perform 3D printing at -50-15 ℃ according to a computer setting program, with a printing speed of 100 mm / min-3000 mm / min and a needle head inner diameter of 30 μm-5 mm, to obtain a 3D-printed aramid cryogel; wherein the 3D-printed aramid cryogel is in a honeycomb shape.

[0032] Step (3): perform solvent replacement on the 3D-printed aramid cryogel at 0 ℃-10 ℃ using a replacement solvent, with a replacement time of 10-24 h and a replacement frequency of 3-5 times, to obtain a 3D-printed aramid hydrogel; the replacement solvent is any one or a combination of two or more of pure water, saline, or a phosphate buffer, and is preferably pure water.

[0033] Step (4): perform drying treatment on the 3D-printed aramid hydrogel at 50 ℃-120 ℃, with a drying time of 10 h-36 h, to obtain a 3D-printed aramid wave-absorbing honeycomb material. The drying treatment is vacuum heating drying or atmospheric pressure heating drying; the drying treatment is performed at 50 ℃-120 ℃; and the drying treatment time is 10 h-36 h.

[0034] A 3D-printed aramid wave-absorbing honeycomb material is prepared using the above preparation method, and the density of the 3D-printed aramid wave-absorbing honeycomb material is 30-500 kg / m 3, the hole grid length is 1.5~10 mm, and the height is 0.5~5 cm; the 3D printing aramid wave-absorbing honeycomb material is composed of a plurality of topologically arranged hexagonal prism honeycomb units, which are cavities with both ends open and empty inside.

[0035] The application of a 3D printing aramid wave-absorbing honeycomb material in the preparation of a 3D printing aramid wave-absorbing honeycomb aerogel composite material.

[0036] The application will be further described in detail below in combination with examples:

[0037] Example 1

[0038] Step (1): uniformly mix para-aramid nanofibers, conductive carbon black and dimethyl sulfoxide by high-pressure homogenization, wherein the mass ratio of para-aramid nanofibers to conductive carbon black is 65:35, the homogenization pressure is 800 bar, and the homogenization frequency is 5 times, to obtain an aramid nanofiber dispersion liquid; wherein the solid content of the aramid nanofiber dispersion liquid is 0.1 wt.%.

[0039] Step (2): by a freeze-direct writing forming method, taking the aramid nanofiber dispersion liquid as a 3D printing ink, placing the 3D printing ink in a 3D printer storage bin, and according to a computer setting program, 3D printing is carried out at-50 DEG C, the printing speed is 100 mm / min, the inner diameter of the needle is 30 μm, and a 3D printing aramid cryogel is obtained; wherein the pattern of the 3D printing aramid cryogel is honeycomb-shaped.

[0040] Step (3): solvent replacement of the 3D printing aramid cryogel is carried out at 0 DEG C by taking a phosphate buffer as a replacement solvent, the replacement time is 10 h, and the replacement frequency is 3 times, to obtain a 3D printing aramid hydrogel;

[0041] Step (4): vacuum heating drying of the 3D printing aramid hydrogel is carried out at 50 DEG C, the drying time is 10 h, and a 3D printing aramid wave-absorbing honeycomb material is obtained.

[0042] The density of the 3D printing aramid wave-absorbing honeycomb material prepared according to Example 1 is 30 kg / m 3 , the hole grid length is 1.5 mm, and the height is 0.5 cm; the 3D printing aramid wave-absorbing honeycomb material is composed of a plurality of topologically arranged hexagonal prism honeycomb units, which are cavities with both ends open and empty inside.

[0043] Example 2

[0044] Step (1): para-aramid nanofibers, carbon nanotubes and ethanol were uniformly mixed by high-pressure homogenization, wherein the mass ratio of para-aramid nanofibers to carbon nanotubes was 85:15, the homogenization pressure was 5000 bar, and the homogenization times was 30, to obtain an aramid nanofiber dispersion; the solid content of the aramid nanofiber dispersion was 10 wt.%.

[0045] Step (2): a 3D-printed aramid cryogel was obtained by a freeze-direct writing forming method, taking the aramid nanofiber dispersion as a 3D printing ink, placing the 3D printing ink in a 3D printer storage bin, and performing 3D printing at 15 °C according to a computer setting program, the printing speed was 3000 mm / min, and the inner diameter of the needle was 5 mm; wherein the pattern of the 3D-printed aramid cryogel was honeycomb-shaped.

[0046] Step (3): solvent replacement was performed on the 3D-printed aramid cryogel at 10 °C using pure water as the replacement solvent, the replacement time was 24 h, and the replacement times was 5, to obtain a 3D-printed aramid hydrogel;

[0047] Step (4): the 3D-printed aramid hydrogel was vacuum heated and dried at 120 °C, the drying time was 36 h, to obtain a 3D-printed aramid wave-absorbing honeycomb material.

[0048] The density of the 3D-printed aramid wave-absorbing honeycomb material prepared according to Example 2 was 500 kg / m 3 , the cell grid side length was 10 mm, and the height was 5 cm; the 3D-printed aramid wave-absorbing honeycomb material was composed of a plurality of topologically arranged regular hexagonal prism-shaped honeycomb units, which were open at both ends and hollow cavities.

[0049] Example 3

[0050] Step (1): para-aramid nanofibers, carbon nanotubes and ethanol were uniformly mixed by high-pressure homogenization, wherein the mass ratio of para-aramid nanofibers to carbon nanotubes was 85:15, the homogenization pressure was 5000 bar, and the homogenization times was 30, to obtain an aramid nanofiber dispersion; the solid content of the aramid nanofiber dispersion was 10 wt.%.

[0051] Step (2): a 3D-printed aramid cryogel was obtained by a freeze-direct writing forming method, taking the aramid nanofiber dispersion as a 3D printing ink, placing the 3D printing ink in a 3D printer storage bin, and performing 3D printing at 15 °C according to a computer setting program, the printing speed was 3000 mm / min, and the inner diameter of the needle was 5 mm; wherein the pattern of the 3D-printed aramid cryogel was honeycomb-shaped.

[0052] Step (3): solvent exchange of the 3D-printed aramid cryogel was carried out at 5 ℃ with saline as the displacement solvent, the exchange time was 15 h, and the exchange times were 4, to obtain a 3D-printed aramid hydrogel;

[0053] Step (4): vacuum heating drying of the 3D-printed aramid hydrogel was carried out at 100 ℃, the drying time was 20 h, to obtain a 3D-printed aramid wave-absorbing honeycomb material.

[0054] The density of the 3D-printed aramid wave-absorbing honeycomb material prepared according to Example 3 was 100 kg / m 3 , the cell edge length was 5 mm, and the height was 2 cm; the 3D-printed aramid wave-absorbing honeycomb material was composed of a plurality of topologically arranged regular hexagonal prism-shaped honeycomb units, which were open at both ends and hollow cavities.

[0055] Example 4

[0056] Step (1): para-aramid nanofibers, MXene and dimethyl sulfoxide were uniformly mixed by high-pressure homogenization, wherein the mass ratio of para-aramid nanofibers to MXene was 70:30, the homogenization pressure was 2000 bar, and the homogenization times were 10, to obtain an aramid nanofiber dispersion; the solid content of the aramid nanofiber dispersion was 0.5 wt.%.

[0057] Step (2): a 3D-printed aramid cryogel was obtained by a freeze-straight writing forming method, taking the aramid nanofiber dispersion as a 3D-printing ink, placing the 3D-printing ink in a 3D-printing machine storage bin, and 3D-printing at -45 ℃ according to a computer setting program, the printing speed was 700 mm / min, and the inner diameter of the needle was 700 μm.

[0058] Step (3): solvent exchange of the 3D-printed aramid cryogel was carried out at 7 ℃ with phosphate buffer as the displacement solvent, the exchange time was 15 h, and the exchange times were 3, to obtain a 3D-printed aramid hydrogel;

[0059] Step (4): atmospheric pressure heating drying of the 3D-printed aramid hydrogel was carried out at 80 ℃, the drying time was 15 h, to obtain a 3D-printed aramid wave-absorbing honeycomb material.

[0060] Example 5

[0061] Step (1): para-aramid nanofibers, graphene and dimethyl sulfoxide were uniformly mixed by high-pressure homogenization, wherein the mass ratio of para-aramid nanofibers to graphene was 80:20, the homogenization pressure was 2000 bar, and the homogenization times were 20, to obtain an aramid nanofiber dispersion; the solid content of the aramid nanofiber dispersion was 2 wt.%.

[0062] Step (2): The 3D printing aramid fiber cryogel was obtained by freeze-direct writing method using the aramid fiber dispersion liquid as 3D printing ink, placing the 3D printing ink in the 3D printer storage bin, and performing 3D printing at -50 ℃ according to the computer setting program, the printing speed was 1000 mm / min, and the inner diameter of the needle was 1000 μm.

[0063] Step (3): The 3D printing aramid fiber cryogel was subjected to solvent replacement at 5 ℃ using pure water as the replacement solvent, the replacement time was 10 h, and the replacement number was 3 times, to obtain the 3D printing aramid fiber hydrogel.

[0064] Step (4): The 3D printing aramid fiber hydrogel was subjected to normal pressure heating drying treatment at 120 ℃, the drying time was 10 h, to obtain the 3D printing aramid fiber wave-absorbing honeycomb material.

[0065] Example 6

[0066] Step (1): The para-aramid nanofiber, carbonyl iron and ethanol were uniformly mixed by high-pressure homogenization, wherein the mass ratio of para-aramid nanofiber: carbon nanotube was 80:20, the homogenization pressure was 1000 bar, and the homogenization number was 20 times, to obtain the aramid fiber dispersion liquid; the solid content of the aramid fiber dispersion liquid was 1 wt.%.

[0067] Step (2): The 3D printing aramid fiber cryogel was obtained by freeze-direct writing method using the aramid fiber dispersion liquid as 3D printing ink, placing the 3D printing ink in the 3D printer storage bin, and performing 3D printing at -50 ℃ according to the computer setting program, the printing speed was 400 mm / min, and the inner diameter of the needle was 400 μm.

[0068] Step (3): The 3D printing aramid fiber cryogel was subjected to solvent replacement at 5 ℃ using pure water as the replacement solvent, the replacement time was 10 h, and the replacement number was 3 times, to obtain the 3D printing aramid fiber hydrogel.

[0069] Step (4): The 3D printing aramid fiber hydrogel was subjected to normal pressure heating drying treatment at 120 ℃, the drying time was 10 h, to obtain the 3D printing aramid fiber wave-absorbing honeycomb material.

[0070] Example 7

[0071] Step (1): The para-aramid nanofiber, carbonyl iron and ethanol were uniformly mixed by high-pressure homogenization, wherein the mass ratio of para-aramid nanofiber: carbon nanotube was 80:20, the homogenization pressure was 1000 bar, and the homogenization number was 20 times, to obtain the aramid fiber dispersion liquid; the solid content of the aramid fiber dispersion liquid was 1 wt.%.

[0072] Step (2): The 3D printing aramid fiber dispersion liquid was used as 3D printing ink, and the 3D printing ink was placed in a 3D printer storage bin. According to a computer setting program, 3D printing was performed at -50 DEG C, the printing speed was 300 mm / min, the inner diameter of the needle was 300 mu m, and a 3D printed aramid fiber cryogel was obtained.

[0073] Step (3): The 3D printed aramid fiber cryogel was subjected to solvent replacement at 5 DEG C with pure water as the replacement solvent, the replacement time was 10 h, and the replacement number was 3 times, and a 3D printed aramid fiber hydrogel was obtained.

[0074] Step (4): The 3D printed aramid fiber hydrogel was subjected to normal pressure heating drying at 120 DEG C, the drying time was 10 h, and a 3D printed aramid fiber wave-absorbing honeycomb material was obtained.

[0075] Example 8

[0076] Step (1): Para-aramid nanofibers, carbon nanotubes, graphene and dimethyl sulfoxide were uniformly mixed by high-pressure homogenization, wherein the mass ratio of para-aramid nanofibers: carbon nanotubes: graphene was 70:20:10, the homogenization pressure was 1000 bar, and the homogenization number was 20 times, to obtain an aramid nanofiber dispersion liquid; the solid content of the aramid nanofiber dispersion liquid was 2wt.%.

[0077] Step (2): The 3D printing aramid fiber dispersion liquid was used as 3D printing ink, and the 3D printing ink was placed in a 3D printer storage bin. According to a computer setting program, 3D printing was performed at -50 DEG C, the printing speed was 300 mm / min, the inner diameter of the needle was 300 mu m, and a 3D printed aramid fiber cryogel was obtained.

[0078] Step (3): The 3D printed aramid fiber cryogel was subjected to solvent replacement at 5 DEG C with pure water as the replacement solvent, the replacement time was 10 h, and the replacement number was 3 times, and a 3D printed aramid fiber hydrogel was obtained.

[0079] Step (4): The 3D printed aramid fiber hydrogel was subjected to vacuum heating drying treatment at 80 DEG C, the drying time was 15 h, and a 3D printed aramid fiber wave-absorbing honeycomb material was obtained.

[0080] The above is only a preferred embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent process transformation using the content of the specification and drawings of the present application, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A preparation method of 3D-printed aramid wave-absorbing honeycomb material, characterized in that, Comprising the following steps: Step one: uniformly mixing para-aramid nanofibers, wave-absorbing agents and solvents by high-pressure homogenization to obtain an aramid nanofiber dispersion; the mass ratio of the para-aramid nanofibers to the wave-absorbing agents in step one is (65-85):(35-15), the pressure of the homogenization is 800-5000 bar, and the number of homogenization is 5-30 times; the solid content of the aramid nanofiber dispersion is 0.1-10 wt%, the wave-absorbing agents in step one are any one or a combination of two or more of carbon nanotubes, graphene, MXene, conductive carbon black, carbonyl iron absorber, ferrite absorber and metal and oxide superfine powder, and the solvents are methanol, ethanol, dimethyl sulfoxide or acetone; Step two: using the aramid nanofiber dispersion obtained in step one as 3D printing ink, placing the 3D printing ink in a 3D printer storage bin to perform 3D printing by a freeze-direct writing forming method to obtain a 3D printed aramid cryogel, the 3D printed aramid cryogel is in a honeycomb shape, and the temperature of the 3D printing in step two is -50-15 ℃; Step three: performing solvent replacement on the 3D printed aramid cryogel obtained in step two by using a replacement solvent to obtain a 3D printed aramid hydrogel; the replacement solvent in step three is any one or a combination of two or more of pure water, saline or phosphate buffer; and the temperature of the solvent replacement is 0-10 ℃; Step four: heating and drying treatment is performed on the 3D-printed aramid hydrogel obtained in step three to obtain a 3D-printed aramid wave-absorbing honeycomb material, wherein the heating and drying treatment in step four is performed by vacuum heating and drying or normal pressure heating and drying; the drying treatment is performed at 50-120 DEG C; the drying treatment time is 10-36 h; the 3D-printed aramid wave-absorbing honeycomb material is composed of a plurality of topologically arranged honeycomb units, the honeycomb unit is a regular hexagonal prism, and the regular hexagonal prism is a cavity with open ends and an empty interior; the density of the 3D-printed aramid wave-absorbing honeycomb material is 30-500 kg / m 3 ; the cell side length of the 3D-printed aramid wave-absorbing honeycomb material is 1.5-10 mm; and the height of the 3D-printed aramid wave-absorbing honeycomb material is 0.5-5 cm.

2. The preparation method of the 3D-printed aramid wave-absorbing honeycomb material according to claim 1, characterized in that, The inner diameter of the 3D printed needle is 30 μm-5 mm, and the printing speed of the 3D printing is 100 mm / min-3000 mm / min.

3. The preparation method of the 3D-printed aramid wave-absorbing honeycomb material according to claim 1, characterized in that The solvent replacement time is 10-24 h, and the number of solvent replacement is 3-5 times.

4. A 3D printed aramid wave absorbing honeycomb material, characterized in that, Prepared by the preparation method of any one of claims 1-3.

5. The use of the 3D printed aramid wave-absorbing honeycomb material in any one of claim 4 in the preparation of a 3D printed aramid wave-absorbing honeycomb aerogel composite material, the field of aerospace and radar stealth.

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