Titanium carbide film with high electromagnetic shielding and infrared stealth performance and its preparation and application

Abstract

The present invention belongs to the field of material preparation, and discloses a preparation method and application of a titanium carbide film having both high electromagnetic shielding and infrared stealth performance. The preparation method is as follows: after vacuum filtration and forming a titanium carbide MXene film on a substrate, the titanium carbide MXene film and the substrate are isotropically stretched while being steam-treated, and then the substrate is removed to obtain a titanium carbide film having both high electromagnetic shielding and infrared stealth performance; the steam used in the steam treatment is plasticizing steam, and the plasticizing steam is evaporated from a plasticizing solvent having a plasticizing effect on the titanium carbide MXene film, and the plasticizing solvent is water and / or ethanol; the obtained titanium carbide film having both high electromagnetic shielding and infrared stealth performance can be applied to aircraft, ships and vehicle surfaces and protective clothing. The present invention can eliminate or reduce wrinkles, wrinkles and other irregular shapes of MXene sheets, achieve precise alignment and precise arrangement between sheets, and highly densified and optimized orientation of the inner and outer layers of the membrane.

Description

Technical Field

[0001] The invention belongs to the technical field of material preparation, and relates to a titanium carbide film with high electromagnetic shielding and infrared stealth performance, and the preparation and application thereof. Background Art

[0002] Two-dimensional nanomaterials (2DN), compared with one-dimensional (1D) and zero-dimensional (0D) nanomaterials, often exhibit unique surface morphologies such as ripples, wrinkles and folds, which are formed as a result of the combined effects of thermal vibrations, edge instabilities, interatomic thermodynamic instabilities, strain, thermal shrinkage, dislocations, solvent capture, relaxation of pre-strained substrates, surface anchoring, and high solvent surface tension. These factors jointly affect the internal structure of the two-dimensional sheets, resulting in the formation of uncontrollable ripples, bends and wrinkles.

[0003] Titanium carbide (Ti3C2Tx) MXene is a typical two-dimensional material with metallic conductivity, surface chemical activity, adjustable work function and excellent mechanical properties. These characteristics make it show great application potential in many fields such as energy storage, optoelectronics, electromagnetic absorption and shielding, wireless communication and seawater desalination. However, the key to realizing these applications lies in the macroscopic assembly of MXene. Although MXene sheets can be assembled into macroscopic membranes on a large scale through vacuum filtration, scraping, casting and slot die coating, the uncontrollable structures such as ripples, bends and wrinkles that are easily formed between sheets produce a large number of pores, which seriously weaken the mechanical strength, conductivity and stability of the MXene membrane. This limitation is particularly obvious in high-demand military applications such as electromagnetic shielding and infrared stealth.

[0004] In order to improve the performance of titanium carbide MXene films, researchers have tried various methods, such as enhancing the performance of MXene films by strengthening interlayer interactions and removing pores within the membrane.

[0005] The first method is to improve the connection between MXene layers through chemical cross-linking, introducing methods such as hydrogen bonding, ionic bonding, covalent bonding, and composite bridging (combining hydrogen bonding, ionic bonding, and covalent bonding).

[0006] The literature (Proc. Natl Acad. Sci. USA 111, 16676–16681 (2014)) introduced strong hydrogen bonds by inserting polyvinyl alcohol (PVA) into the MXene interlayer to improve the tensile strength of the film; the literature (Nat. Sustain. 3, 296–302 (2020).) used ionic bonding to enhance the mechanical properties of the MXene film; the literature (ACS Nano 14, 11722–11732 (2020).) constructed a strong and stable MXene-polydopamine film by introducing covalent bonds; the literature (Science 374, 96–99 (2021).) simultaneously introduced covalent bonds and hydrogen bonds to induce synergistic improvements in the tensile strength and toughness of the MXene film; the literature (Nature 2024, 634, 1103.) used hydrogen bonds to bridge with sericin (SS), and then used a roll-to-roll assisted blade coating process at 20 cm min -1 The macroscopic film is assembled continuously at a speed of 2+ ) bridges to freeze the alignment orientation of the film in the wet state, ultimately obtaining a scalable bridged MXene film with features such as highly aligned and compact microstructures.

[0007] Patent CN115732139A discloses a method for preparing MXene films using biomacromolecules as dispersants. This method allows MXene to be evenly dispersed in the system by adding a small amount of DNA, and introduces a CaCl2 solution, a coagulation liquid for wet spinning. The negatively charged phosphate groups in the DNA in the system can combine with the positively charged calcium ions in the coagulation liquid CaCl2 through electrostatic action to form calcium bridges, fix the MXene layers, and promote the formation of the MXene film, so that the prepared self-supporting MXene film layers have uniform orientation, few defects, and excellent mechanical, electrical and flexibility properties.

[0008] The literature (PNAS, 2020, 117(44): 27154) shows that a strong and highly conductive MXene film is made by continuous bridging of hydrogen and ionic bonds. The ionic bonding agent reduces the interplanar spacing and increases the arrangement of MXene nanosheets, while the hydrogen bonding agent increases the interplanar spacing and reduces the arrangement of MXene nanosheets, making the tensile strength of the MXene film as high as 436 MPa, and the conductivity and weight-normalized shielding efficiency are also as high as 2988 S / cm and 58929 dB·cm 2 / g.

[0009] In summary, although this type of method of enhancing the interlayer connection of MXene through different bonding forms can improve the performance of titanium carbide MXene films, they all have their own problems. For example, the introduction of hydrogen bonds makes it easier to operate but the strength improvement is limited, the introduction of ionic bonds improves the arrangement compactness but the flexibility of the film decreases, the introduction of covalent bonds improves the performance of the film but the preparation cost is high, and composite bridging achieves comprehensive performance optimization but the preparation difficulty is greatly increased.

[0010] The second approach is to densify MXene films by introducing small-scale one-dimensional / two-dimensional materials to improve their tensile strength and electrical conductivity.

[0011] Patent CN202311306221.7 discloses a MXene composite film and wireless communication antenna resistant to seawater corrosion. The composite film is prepared by compounding graphene oxide (GO) nanosheets and MXene nanosheets of different diameters to obtain a MXene composite film with a denser structure and a smoother surface, thereby improving conductivity and environmental stability. Patent CN202410907268.7 discloses the preparation of a self-supporting MXene / CNTs composite membrane electrode and the application of square wave exchange electrochemical method to remove uranium. The introduction of MWCNT-COOH can expand the interlayer spacing of the MXene film, expand more active sites, and the formed conductive network promotes ion accessibility, further improving the removal capacity of uranyl ions. However, although these two methods significantly improve the mechanical properties and conductive properties and broaden the application scenarios, GO will sacrifice a certain degree of flexibility after compounding, and the introduction of MWCNTs will increase the interlayer spacing and active sites, but it will affect the tightness and uniformity of the film. In addition, the complexity and cost of preparation will also increase accordingly.

[0012] The third method is to introduce functional components into the sheet and induce the sheet orientation based on the action of external field.

[0013] Patent CN118440522A discloses a magnetically induced oriented titanium carbide ferrite composite film and its preparation method and application. The developed magnetically induced orientation strategy can achieve homopolar arrangement of the introduced ferrite nanoparticle magnetic poles, control the material structure, enrich the pores of the MXene titanium carbide ferrite composite film, and induce the orientation of the MXene titanium carbide sheets. The prepared magnetically induced oriented MXene titanium carbide ferrite composite film exhibits an average electromagnetic shielding effectiveness of 62.8dB in the range of 2 to 18GHz, and a maximum Herman's orientation factor of 0.938. However, this method relies on the introduction of magnetic nanoparticles, which increases the complexity and cost of the composite material.

[0014] Patent CN115763087A discloses a method for preparing graphene titanium carbide cross-linked film materials and their application in supercapacitors. In order to solve the problem that the film experiences capillary shrinkage and weak interface effects during the drying process, resulting in low film orientation and density, a strategy of restricting a small amount of water molecules between graphene oxide and titanium carbide MXene nanosheets is adopted to achieve regular orientation of the nanosheets. After reducing graphene oxide to graphene, π-π interactions are introduced between the graphene layers to fix the regular structure of the graphene nanosheets, achieving the interface synergistic effect of covalent bonds and π-π interactions between graphene and titanium carbide MXene. The prepared graphene titanium carbide cross-linked composite film has a tensile strength of 1.63GPa and an electrical conductivity of 1423Scm -1 The volumetric capacity of the film is as high as 1382Fcm -3 The volume energy density of the asymmetric supercapacitor prepared with this film as the self-supporting negative electrode reached 47.62m Wh cm -3 However, this method requires precise control of the amount of water molecules and the treatment process, and the process is relatively complex.

[0015] Patent CN118919315A discloses an alkalized heterogeneous structure MXene membrane electrode material and its preparation method and process: the MXene membrane is immersed in an alkaline solution, washed and dried to obtain an alkaline-impregnated MXene membrane, and then an aqueous ammonium hydroxide solution is added to the reactor, and then the alkaline-impregnated MXene membrane is fixed horizontally or vertically just above the liquid surface of the aqueous ammonium hydroxide solution to perform a gas-phase hydrothermal reaction to improve the layered structure advantage of the MXene material. However, this method introduces additional chemical treatment steps, increases the preparation time, and the sensitivity to alkaline environments may limit the application range of the membrane.

[0016] The fourth method uses stress to increase the orientation of the sheets and reduce the porosity.

[0017] Patent CN117051506A discloses a method for preparing cross-linking agent-free titanium carbide fiber and its application. Since titanium carbide fiber has structural defects such as wrinkles and pores in its structure, as well as weak interface effects, its structure is relatively loose. Therefore, the preparation method uses the synergistic effect of thermal tensile stress and the nanosheet interlocking structure between the external polymer protective layer and the internal MXene fiber layer to form a cyclic olefin copolymer chain polymer protective layer in situ on the fiber surface. This process effectively enhances the orientation of the fiber and reduces the porosity. The prepared high-performance MXene fiber has a mechanical strength of 707.73MPa and a toughness of 125.12MJ·m -3 , the conductivity is 11959.4S·cm -1The fabric woven from this MXene fiber has high electromagnetic shielding performance and excellent durability against mechanical and harsh environments. However, the hot stretching method has high requirements for the process of fiber preparation and protective layer formation, and in-situ polymerization increases the difficulty and complexity of process stability.

[0018] The literature (Nano Research.2024,17,5651–5660) uses a scalable layer-by-layer coating (LbLBC) method to prepare highly oriented MXene / polyvinyl alcohol (PVA) films. During the layer-by-layer coating process, the colloid is subjected to a strong shear effect, and the MXene nanosheets are arranged in an orderly manner along the direction of blade movement. By changing the gap between the scrapers during layer-by-layer coating, the orientation of MXene can be effectively adjusted, and the Herman orientation factor F reaches 0.81. The tensile strength of the prepared MXene / PVA film is 145.5MPa, the fracture strain is 19.6%, and the toughness is 17.7MJ·m -3 , EMI shielding effectiveness is 36.7dB. The inherent low mid-infrared (mid-IR) emissivity of MXene, coupled with its densely oriented structure, makes the composite film infrared invisible, resulting in a significant reduction in the surface radiation temperature from 150°C to 66.1°C. Although the layer-by-layer coating method can improve the orientation of the sheet, its process parameters are highly dependent on the viscosity, concentration and dispersibility of the solution, and need to be finely adjusted for different solutions, which increases the complexity of the process and limits its universality and large-scale promotion in the preparation of MXene solution films.

[0019] In summary, although the existing technology has made some progress in the macroscopic assembly of high-performance MXene films, the performance of the macroscopic films currently prepared is still significantly lower than the theoretical performance of single-layer MXene nanosheets. This is mainly due to the presence of pores and defects of various sizes inside the MXene film. These pores and defects greatly hinder the performance transfer of the MXene film and limit its performance in high-performance applications. In particular, in the application of electromagnetic shielding and infrared stealth, pores and defects have a significant impact on the electromagnetic shielding performance and infrared stealth capability of the MXene film.

[0020] Therefore, the research and development of titanium carbide films with both high electromagnetic shielding and infrared stealth performance and their preparation methods are of great significance for solving the above problems. Summary of the invention

[0021] The purpose of the present invention is to solve the problems existing in the prior art and to provide a titanium carbide film having both high electromagnetic shielding and infrared stealth performance and its preparation and application.

[0022] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0023] The preparation method of titanium carbide film with high electromagnetic shielding and infrared stealth performance is as follows: after vacuum filtration and forming titanium carbide MXene film on a substrate, the titanium carbide MXene film and the substrate are isotropically stretched while being treated with steam, and then the substrate is removed, that is, the treated titanium carbide MXene film and the substrate are transferred as a whole to an ethanol solution, and the titanium carbide MXene film is separated from the filter membrane and transferred to a cellulose filter paper, and is placed at 35-45°C for 12-24 hours to obtain a titanium carbide film with high electromagnetic shielding and infrared stealth performance; the titanium carbide MXene film has low toughness and is prone to cracks when stretched directly, so the substrate is used to bear part of the stress to prevent stress concentration from causing crack expansion; the main reason for the low toughness of the titanium carbide MXene film is the chemical characteristics of its surface functional groups, weak interlayer interactions, more microscopic defects, and sensitivity to the environment. The typical structure of MXene is an alternating arrangement of metal layers (such as Ti, Nb) and carbon / nitrogen layers, and its surface usually contains functional groups such as hydroxyl (–OH), oxide (=O), and fluorine (–F). These functional groups give the MXene film a certain chemical activity, but they also weaken the van der Waals force between the sheets, making the interlayer bonding weaker and prone to slip or breakage under external force. Therefore, compared with graphene films and graphene oxide films, titanium carbide MXene films have lower toughness. Moreover, titanium carbide MXene is very sensitive to moisture and oxygen in the environment due to the presence of its surface active functional groups (such as –OH, –F). This will cause the material to deteriorate in a humid or oxidizing environment, further reducing its toughness. In addition, the preparation of titanium carbide MXene usually involves wet exfoliation or chemical treatment, which will introduce more micropores and defects, while increasing the inhomogeneity of the interlayer stacking, thereby reducing its toughness;

[0024] The steam used in the steam treatment is plasticizing steam, which is formed by evaporating a plasticizing solvent that has a plasticizing effect on the titanium carbide MXene film. The plasticizing solvent is water and / or ethanol. The mass area density (D) is introduced as a control parameter in the film formation process. According to the concentration (mg·mL -1 )×MXene solution volume (mL) / area (cm 2 ) is calculated, and the unit of D is mg cm -2 MXene films of different thicknesses are labeled as MXFm-XD. The theoretical density of the film (mg cm -3 ) = mass area density D (mg·cm -2 ) / film thickness (cm). Under the same mass area density, a smaller film thickness indicates a higher density of the film, and thus a higher mechanical strength and durability of the film. The volume of the plasticizing solvent is adjusted according to the thickness, and the mass area density range is 0.3 to 20 mg cm -2, the volume of plasticizing solvent ranges from 15 to 180 mL. When D<5, the volume of plasticizing solvent is 15 mL to 100 mL; when 5≤D<15, the volume of plasticizing solvent is 80 mL to 150 mL; when 15≤D≤20, the volume of plasticizing solvent is 150 to 180 mL.

[0025] like Figure 1 As shown in (a), the untreated titanium carbide MXene film has more pores in the film, lower density, lower conductivity, and more transmitted electromagnetic waves, resulting in lower electromagnetic shielding performance, and the uneven undulation of the MXene layer leads to poor infrared stealth performance;

[0026] like Figure 1 As shown in (b), the present invention performs steam plasticization-assisted isotropic stretching on the assembled titanium carbide MXene film, which involves two main reaction processes: 1. The plasticized solvent vapor molecules diffuse and penetrate into the MXene film, which on the one hand acts on the lamellae to cause topological changes, and on the other hand acts on the interlayer structure to weaken the interlayer van der Waals force, so that the interlayer spacing is expanded, thereby improving the deformation capacity of the lamellae; 2. While the solvent molecules are plasticized, the entire plane of the film is subjected to coplanar epitaxial stress stretching (isotropic stretching), eliminating or reducing the wrinkles, wrinkles and other irregular shapes of the MXene lamellae, while achieving precise alignment and precise arrangement between the lamellae, and achieving high densification and orientation optimization of the inner and outer layers of the membrane. Figure 1 As shown in (c), this structural adjustment significantly enhances the interlayer bonding force and reduces the interlayer spacing, thereby greatly improving the conductivity and mechanical strength of the MXene film. In addition, the optimized structure achieves diversification in the electromagnetic wave loss mechanism, significantly improving the electromagnetic shielding efficiency and infrared stealth capability (manifested as low emissivity in the infrared band). Therefore, the present invention overcomes the defects of the traditional MXene titanium carbide material, which has a single loss mode and insufficient shielding effectiveness, and greatly expands its potential in wide-band stealth applications.

[0027] The plasticization process of the solvent vapor molecules on the MXene film and the isotropic epitaxial stretching process of the MXene film occur simultaneously: first, the activation and redistribution process of the interlayer solvent molecules. In a closed environment, after the solvent reaches the boiling point, the solvent vapor molecules diffuse and penetrate into the layered MXene film. The entry of the solvent increases the content of free solvent molecules between the MXene layers, changing it from a partially inactivated state to an active state. The activated solvent molecules can act as lubricants, reduce the mutual friction between the layers, and promote the relative sliding and adjustment of the sheets during the stretching process; then the structural reorganization and interlayer weak welding process occur. In the isotropic epitaxial stretching process, the interlayer region plasticized by the solvent is like a free-flowing extrusion, rearranged and combined. After the solvent evaporates, the interlayer spacing of the MXene film recovers to a state close to its initial state through the capillary compression effect, completing a non-permanent welding process similar to the welding mechanism in metal materials. Finally, due to the plasticization and rearrangement caused by the solvent molecules, the MXene film is subjected to epitaxial isotropic tensile stress in the planar direction, and the interlayers fit tightly together, reducing the grain boundary pores, micropores, mesopores, and macropores. The density of the material is increased, and the directional arrangement of the repeating units is promoted, thereby achieving a significant improvement in performance.

[0028] As the preferred technical solution:

[0029] According to the method for preparing the titanium carbide film with both high electromagnetic shielding and infrared stealth performance, the titanium carbide MXene film has a thickness of 1 to 500 μm, an interlayer spacing of 1.3 to 1.72 nm, a Herman's orientation factor of 0.6 to 0.75, a porosity of 5 to 8%, and a conductivity of 3000 to 6000 S·cm -1 , tensile strength is 200~400MPa, toughness is 5~10MJ·m -3 .

[0030] According to the method for preparing a titanium carbide film having both high electromagnetic shielding and infrared stealth performance as described above, when the thickness of the titanium carbide MXene film is ≤10 μm, the device used for isotropically stretching the titanium carbide MXene film together with the substrate while treating with steam includes a solvent pool a and a heating device a; the top of the solvent pool a is a vertically arranged cylinder a, the cylinder a is divided into an upper and lower layer and is detachably connected by 2m membrane fixing screws a, m>2, and the 2m membrane fixing screws a are evenly distributed around the circumference of the central axis of the cylinder a; the heating device a is used to heat the solvent pool a;

[0031] The vertically arranged cylinder a and the membrane fixing screw a are fixed circumferentially to form a closed cylindrical reaction chamber. In the closed cylindrical reaction chamber, the titanium carbide MXene membrane is fixed by a rigid edge to form a closed interface. The volatile plasticizing solvent in the chamber is controlled to vaporize to produce saturated vapor pressure. Due to the system boundary constraints, the vapor pressure gradient induces uniformly distributed equibiaxial tensile stress in the upper membrane surface. This mechanical state satisfies the isotropic tensile condition.

[0032] When the thickness of the titanium carbide MXene film is >10 μm, the device used for isotropically stretching the titanium carbide MXene film together with the substrate while treating it with steam includes a solvent pool b, a heating device b, a deformable tube and a regulator; the bottom of the deformable tube is sealed and connected to the top of the solvent pool b, the top of the deformable tube is a vertically arranged cylinder b, the cylinder b is divided into two layers, the upper and lower layers are detachably connected by 2m membrane fixing screws b, m>2, and the 2m membrane fixing screws b are evenly distributed around the circumference of the central axis of the cylinder b; the regulator is used to control the radial outward expansion of the cylinder b along the cylinder b; the heating device b is used to heat the solvent pool b.

[0033] The method for preparing the titanium carbide film with both high electromagnetic shielding and infrared stealth performance as described above, the regulator includes a displacement bracket, a pressing plate, an upper bracket, a limiting structure and a lower bracket;

[0034] The displacement bracket is a conical cap-shaped structure with the tip at the top, comprising 2n inclined rods I, n>3, the upper ends of the 2n inclined rods I are simultaneously connected to the center of the lower surface of the pressing plate, and the lower ends are evenly distributed around a point o, the point o is located on the central axis of the pressing plate, and the pressing plate is coaxial with the cylinder b;

[0035] The upper support includes 2n horizontal rods, which are radially distributed around point o. The two ends of the horizontal rods are respectively marked as end a and end b. End a is closer to point o than end b. The ends a of the 2n horizontal rods are respectively hinged to the lower ends of the 2n oblique rods I in a one-to-one correspondence.

[0036] The limiting structure restricts the 2n horizontal rods to move only along their own length direction;

[0037] The b ends of two adjacent horizontal rods are each connected by an arc bar, and at least one set of opposite arc bars is composed of three sections: left, middle and right. The middle section is composed of a separated inner layer and outer layer. The outer layer of the middle section is fixedly connected to the left section, and the inner layer of the middle section is fixedly connected to the right section. All the arc bars form a circular ring, and the circular ring extends vertically downward to form a circular tube.

[0038] The lower support includes 2n oblique rods II, which are distributed in an umbrella shape around the central axis of the cylinder b. The angle between the oblique rods II and the central axis of the cylinder b is 100-105°. The lower layer of the cylinder b extends radially outward and is connected to the upper ends of the 2n oblique rods II, and the lower ends of the 2n oblique rods II are connected to the circular tube.

[0039] When the pressing plate is subjected to downward pressure, it will move downward. This displacement is transmitted to the upper bracket through the displacement bracket, causing the upper bracket to move outward. Then, the displacement of the upper bracket is transmitted to the lower bracket, causing the lower bracket to move outward as well. Finally, the displacement of the lower bracket is transmitted to the deformable tube, causing the deformable tube to extend outward. In the process of the deformable tube extending outward, it applies a coplanar tensile displacement to the edge of the membrane in contact with it, thereby generating tensile stress.

[0040] The lower support of the present invention is designed to include 2n oblique rods II, on the one hand to disperse the extended external force to the entire plane, reduce stress concentration in a single direction, and avoid stress overload in a local direction; on the other hand to provide a small displacement to cause a small deformation of the deformable tube.

[0041] For titanium carbide MXene films with a thickness greater than 10 μm, due to the large thickness, the steam penetration effect is weakened and the complete orientation of the inner and upper layers of the titanium carbide MXene film cannot be completed. It is necessary to start the stretching device to apply additional in-plane isotropic stretching to the titanium carbide MXene film to ensure that the titanium carbide MXene film completes the complete orientation process under a uniformly mixed steam environment and isotropic stretching. The maximum stretching displacement (△L) is determined by the initial diameter L0 of the titanium carbide MXene film, and the shrinkage rate of the unstretched film on the plane before and after complete orientation is ∈, and the maximum stretching displacement △L = (L0×∈) / 2.

[0042] The shrinkage rate of the titanium carbide MXene film on the plane ∈ (%) can be calculated experimentally (i.e., the titanium carbide MXene film is placed in a vacuum environment at 100 ° C for 12 hours, during which the vacuum is continuously drawn, and then the average diameter L is measured after cooling to room temperature after being taken out. T ), the shrinkage rate is calculated as follows:

[0043]

[0044] The stretching displacement is controlled by the pressing plate above the device. Below the pressing plate is the length S of the inclined rod I (the initial included angle between the inclined rod I and the pressing plate is 45°) that can control the outer edge to move outward, which is used to control the outward movement of the upper bracket and the lower bracket. When controlling the downward pressing distance (the height measuring bracket can record the change), the outward movement of the lower bracket causes the deformable tube to extend outward, and then generates an outward coplanar stretching displacement on the titanium carbide MXene film fixed on the deformable tube. Since the maximum stretching displacement is related to the maximum pressing displacement, the calculation formula for the maximum pressing displacement △H is as follows:

[0045]

[0046] In the formula, S is the length of the inclined rod I of the displacement bracket, and H is the initial height of the displacement bracket (i.e., the vertical distance between the pressing plate and the upper bracket);

[0047] Substituting into the calculation formulas of the plane shrinkage rate ∈ and the initial diameter L0 of the titanium carbide MXene film, the final calculation formula is:

[0048]

[0049] Therefore, after determining the length S of the displacement bracket and the initial height H of the displacement bracket, the maximum pressing displacement can be adjusted according to the initial diameter L0 of the titanium carbide MXene film and the diameter L of the titanium carbide MXene film after shrinkage T to adjust the maximum pressing displacement. The actual pressing displacement does not exceed the maximum pressing displacement, which is adjusted according to the required stretching ratio. The stretching ratio is y (0 < y < 1), and the actual pressing displacement is y×△H. Adjust the actual pressing displacement according to the application requirements.

[0050] For the preparation method of the titanium carbide film with both high electromagnetic shielding and infrared stealth performance as described above, the regulator further includes a height measuring bracket, which is vertically arranged on one side of the pressing plate and fixedly connected to the upper bracket.

[0051] For the preparation method of the titanium carbide film with both high electromagnetic shielding and infrared stealth performance as described above, the forming process of the titanium carbide MXene film is as follows: using a PP filter membrane (Celdard 3501, pore size 0.22μm) as the substrate, and subjecting the titanium carbide MXene film-forming aqueous solution with a concentration of 0.5 - 1.5mg·g -1 to vacuum filtration on the substrate to obtain a titanium carbide MXene film that has not been separated from the substrate.

[0052] For the preparation method of the titanium carbide film with both high electromagnetic shielding and infrared stealth performance as described above, the interlayer spacing of the titanium carbide film with both high electromagnetic shielding and infrared stealth performance is 1.2 - 1.38nm, the Herman's orientation factor is 0.75 - 0.95, the porosity is 3 - 6%, and the conductivity is 8000 - 9000S·cm -1, tensile strength is 400~800MPa, toughness is 15~20MJ·m -3 ; Compared with the titanium carbide MXene film before treatment, the layers are stacked more tightly and the interlayer spacing is reduced, which greatly improves the conductivity and mechanical strength of the MXene film; while the solvent molecules are plasticized, the entire plane of the film is subjected to coplanar epitaxial stress stretching (isotropic stretching), eliminating or reducing the wrinkles, wrinkles and other irregular shapes of the MXene layers, while achieving precise alignment and precise arrangement between the layers, and Herman's orientation factor increases from 0.7 to 0.85 to 0.9 to 0.95. Better layer alignment enhances the path continuity of electrons, ultimately increasing the conductivity by 1.5 to 3 times.

[0053] The present invention also provides the use of a titanium carbide film having both high electromagnetic shielding and infrared stealth performances obtained by the preparation method as described in any one of the above items, which is applied to the surfaces of aircraft, ships and vehicles and protective clothing, and can provide infrared stealth and radar stealth effects at the same time;

[0054] Titanium carbide film has both high electromagnetic shielding and infrared stealth performance. The infrared emissivity of the titanium carbide film in the 2.5-25μm band is 10-20%, and the electromagnetic shielding effectiveness (EMI SE, EMI SE>50dB indicates that the material can shield more than 99.999% of the incident electromagnetic waves) in the X-band (X-band is part of the electromagnetic wave frequency range, usually refers to the frequency range of 8GHz to 12GHz, the wavelength is about 2.5cm to 3.75cm, it is part of the microwave spectrum, and is widely used in radar, communication and sensor technology) is greater than 50dB, and the unit thickness specific shielding performance (SSE / t, which is a parameter normalized to the thickness of the specific shielding effectiveness, indicating the electromagnetic shielding effectiveness and density of the material under unit thickness. The higher the SSE / t value, the more effective the material is in shielding capability even when it is relatively thin and light. SSE / t=EMI SE / (ρ·t)) is 75000~90000dB·cm 2 ·g -1 .

[0055] Beneficial effects:

[0056] The present invention improves the deformation capacity of the MXene film by performing steam plasticization-assisted isotropic stretching on the assembled titanium carbide MXene film, and eliminates or reduces the wrinkles, wrinkles and other irregular shapes of the MXene film through coplanar epitaxial stress stretching, while achieving precise alignment and precise arrangement between the layers, and achieving high densification and orientation optimization of the inner and outer layers of the film. The optimized structure achieves diversification in the electromagnetic wave loss mechanism, significantly improving the electromagnetic shielding efficiency and infrared stealth capability. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a schematic diagram of the change of electromagnetic shielding and infrared stealth performance of the titanium carbide MXene film of the present invention before and after solvent vapor plasticization assisted isotropic epitaxial stretching orientation; in the figure, (a) is a schematic diagram of the electromagnetic shielding and infrared stealth performance of the untreated titanium carbide MXene film, (b) is a schematic diagram of the titanium carbide MXene film after solvent vapor plasticization assisted isotropic epitaxial stretching orientation, (c) is a schematic diagram of the electromagnetic shielding and infrared stealth performance of the titanium carbide film with both high electromagnetic shielding and infrared stealth performance;

[0058] Figure 2 is a schematic diagram of an isotropic stretching and steam treatment device in Example A1 of the present invention;

[0059] Figure 3 is a top view of the isotropic stretching and steam treatment device in Example A1 of the present invention;

[0060] Figure 4 Schematic diagram of the isotropic stretching and steam treatment device in Example A2 of the present invention; in the figure, 45° is the initial angle; S is the length of the inclined rod I of the displacement bracket; H is the initial height of the displacement bracket, that is, the vertical distance between the pressing plate and the upper bracket; △H is the maximum pressing displacement; △L is the maximum stretching displacement;

[0061] Figure 5 is a top view of the regulator in Example A2 of the present invention;

[0062] Figure 6 It is a side view of the middle section of the arc strip in the upper support of the present invention;

[0063] Among them, 1-solvent pool a, 2-cylinder a, 3-membrane fixing screw a, 4-arc bar, 5-solvent pool b, 6-height measuring bracket, 7-limiting structure, 8-membrane fixing screw b, 9-deformable tube, 10-displacement bracket, 11-pressing plate, 12-upper bracket, 13-lower bracket. DETAILED DESCRIPTION

[0064] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0065] The testing methods of the relevant performance indicators in the following embodiments and comparative examples are as follows:

[0066] Interlayer spacing: The titanium carbide MXene film prepared in each embodiment and the titanium carbide film with both high electromagnetic shielding and infrared stealth performance were used as samples, respectively, and then the samples were subjected to X-ray diffraction (XRD) test. According to the obtained diffraction pattern and the Bragg law equation (nλ=2dsinθ), the interlayer spacing d was calculated by substituting the ray wavelength λ, diffraction angle θ and diffraction order n (n is 1).

[0067] Herman's orientation factor: The titanium carbide MXene film prepared in each embodiment and the titanium carbide film with high electromagnetic shielding and infrared stealth performance were used as samples respectively, and then the samples were subjected to the small-angle X-ray scattering instrument (SAXS) of the BL16B1 beamline of the Shanghai Light Source Synchrotron Radiation Station to obtain the scattering intensity distribution of the diffraction spot. Finally, the scattering intensity distribution was processed and the azimuth angle φ was used as a variable to obtain the scattering intensity I(φ). The weighted average of the scattering intensity at different azimuth angles was obtained by integration〈cos 2 φ〉, Herman's orientation factor is obtained according to the Herman's orientation factor calculation formula, and its calculation formula is: Herman's orientation factor = (3〈cos 2 φ〉-1) / 2.

[0068] Conductivity: The titanium carbide MXene film prepared in each example and the titanium carbide film with both high electromagnetic shielding and infrared stealth performance were used as samples, and then the conductivity of the samples was measured by a four-probe conductivity tester.

[0069] Porosity: The titanium carbide MXene film prepared in each embodiment and the titanium carbide film with both high electromagnetic shielding and infrared stealth performance are used as samples, and then the porosity V of the sample is calculated. P (%), the calculation formula is as follows:

[0070]

[0071] Where V measured is the measured membrane volume, m measured is the measured film mass, ρ measured The unit is mg cm -3 ;

[0072] ρ Theoretical The unit is mg cm -3 .

[0073] Tensile strength: The high-efficiency separation and high ion selectivity graphene oxide membrane and the titanium carbide membrane with high electromagnetic shielding and infrared stealth performance prepared in each embodiment were used as samples, respectively. When the thickness of the sample was ≤10 μm, a tensile compression dynamometer (model: American Mark-10 IntelliMESUR 2.3.1) was used to test the tensile strength and toughness of the sample. When the thickness of the sample was >10 μm, an electronic universal materials testing machine (model: INSTRON 5969) was used to test the tensile strength and toughness of the sample.

[0074] Infrared emissivity in the 2.5-25 μm band: The titanium carbide films with high electromagnetic shielding and infrared stealth performance prepared in each embodiment were used as samples, and then the reflectance spectra of the samples under infrared radiation in the 2.5-25 μm band were tested by an infrared spectrometer (Thermo Nicolet NEXUS-470) equipped with a gold integrating sphere, and then the infrared emissivity was obtained according to the calculation formula of the infrared emissivity (ε), and the calculation formula is: ε=1-RT, where R is the reflectivity and T is the transmittance.

[0075] Electromagnetic shielding effectiveness (EMI SE) in the X-band: The titanium carbide films with high electromagnetic shielding and infrared stealth performance prepared in each embodiment were made into three circular films with a diameter of 10 cm as samples, and then the electromagnetic interference (EMI) shielding performance of the three samples in the frequency range of 2 to 18 GHz was tested on the AV3629 vector network analyzer using the coaxial air line method, and the average value was finally calculated. The reflection, transmission and absorption characteristics of the samples at different frequencies were evaluated, and the EMI shielding effectiveness (SE) was determined by obtaining the scattering parameters.

[0076] Shielding performance per unit thickness (SSE / t): The titanium carbide films with high electromagnetic shielding and infrared stealth performance prepared in each embodiment were made into three circular films with a diameter of 10 cm as samples, and then the coaxial air line method was used to measure the reflection, transmission and absorption characteristics of the three samples in the frequency range of 2 to 18 GHz on an AV3629 vector network analyzer, and then the EMI shielding effectiveness (SE) was determined by obtaining the scattering parameters, and finally the average value was calculated.

[0077] Example A1

[0078] The apparatus used for isotropic stretching and steam treatment of titanium carbide MXene films with a thickness of ≤10 μm is as follows Figure 2 , Figure 3 As shown, it includes a solvent tank a1 and a heating device a;

[0079] The top of the solvent pool a is a vertically arranged cylinder a 2, which is divided into two layers, upper and lower, and is detachably connected by 2m membrane fixing screws a 3, m>2, and the 2m membrane fixing screws a 3 are evenly distributed around the circumference of the central axis of the cylinder a 2;

[0080] The heating device a is used to heat the solvent tank a1.

[0081] Example A2

[0082] The apparatus used for isotropic stretching and steam treatment of titanium carbide MXene films with thickness > 10 μm is as follows Figure 4 , Figure 5 As shown, it includes a solvent tank b 5, a heating device b, a deformable tube 9 and a regulator;

[0083] The bottom of the deformable tube 9 is sealed and connected to the top of the solvent pool b 5. The top of the deformable tube 9 is a vertically arranged cylinder b. The cylinder b is divided into two layers, upper and lower, and is detachably connected by 2m membrane fixing screws b 8, m>2, and the 2m membrane fixing screws b 8 are evenly distributed around the circumference of the central axis of the cylinder b.

[0084] The heating device b is used to heat the solvent pool b 5;

[0085] The regulator is used to control the outward expansion of the cylinder b along the radial direction of the cylinder b;

[0086] The regulator includes a displacement bracket 10, a pressing plate 11, an upper bracket 12, a limiting structure 7, a lower bracket 13 and a height measuring bracket 6;

[0087] The displacement bracket 10 is a conical cap-shaped structure with the tip at the top, comprising 2n inclined rods I, n>3, the upper ends of the 2n inclined rods I are simultaneously connected to the center of the lower surface of the pressing plate 11, and the lower ends are evenly distributed around a point o, the point o is located on the central axis of the pressing plate 11, and the pressing plate 11 is coaxial with the cylinder b;

[0088] The upper support 12 includes 2n horizontal rods, which are radially distributed around point o. The two ends of the horizontal rods are respectively marked as end a and end b. End a is closer to point o than end b. End a of the 2n horizontal rods is hinged to the lower ends of the 2n oblique rods I in a one-to-one correspondence.

[0089] The limiting structure 7 restricts the 2n horizontal rods to move only along their own length direction;

[0090] like Figure 5 , Figure 6As shown, the ends b of two adjacent horizontal rods are connected by an arc bar 4, at least one group of relative arc bars 4 is composed of three sections: left, middle and right. The middle section is composed of a separated inner layer and outer layer. The outer layer of the middle section is fixedly connected to the left section, and the inner layer of the middle section is fixedly connected to the right section. All the arc bars 4 form a circular ring, which extends vertically downward to form a circular tube.

[0091] The lower support 13 includes 2n oblique rods II, which are distributed in an umbrella shape around the central axis of the cylinder b. The angle between the oblique rods II and the central axis of the cylinder b is 100-105°. The lower layer of the cylinder b extends radially outward and is connected to the upper ends of the 2n oblique rods II, and the lower ends of the 2n oblique rods II are connected to the circular tube.

[0092] Example B1

[0093] The preparation method of titanium carbide film with both high electromagnetic shielding and infrared stealth performance is as follows:

[0094] (1) Preparation of raw materials and equipment used;

[0095] The apparatus used for isotropic stretching and steam treatment was the apparatus described in Example A1, m was 3, the height of the solvent pool a was 8 cm, and the volume was 25 mL;

[0096] PP filter membrane: Celgard 3501 membrane, average pore size 0.22 μm, effective filtration diameter 4 cm, area 12.57 cm 2 ;

[0097] Plasticizing solvent: ethanol;

[0098] Lithium fluoride: CAS number is 7789-24-4;

[0099] Hydrochloric acid aqueous solution: concentration is 9 mol / L;

[0100] Ti3AlC2 powder: CAS number is 196506-01-1;

[0101] Deionized water;

[0102] Ethanol;

[0103] (2) preparing titanium carbide MXene powder;

[0104] (2.1) 3.2 g of lithium fluoride and 40 mL of hydrochloric acid aqueous solution were magnetically stirred in a PTFE beaker for 5 minutes, and then 2 g of Ti3AlC2 powder was added to the solution in batches at a rate of 0.2 g / min and stirred until completely dispersed. The PTFE beaker was then placed in a 40°C water bath and stirred continuously for 30 hours to obtain an etched solution;

[0105] (2.2) After adding deionized water to the etched solution, centrifuge and wash repeatedly until the pH value of the supernatant is 6, collect the precipitate after centrifugation, transfer the precipitate to a flask, add deionized water until the total volume is 200 mL, fill with argon gas, and perform ultrasonic peeling in a water bath at 0°C. After the ultrasonication, collect the upper suspension, centrifuge the suspension at 1500 rpm for 20 minutes, and collect the upper stably dispersed monolayer MXene dispersion. Then, freeze-dry the monolayer MXene dispersion and collect the powder to obtain titanium carbide MXene powder.

[0106] (3) The MXene powder prepared in step (2) was first prepared to a concentration of 0.5 mg g -1 The MXene film-forming aqueous solution is then prepared by using a PP filter membrane as a substrate, and the titanium carbide MXene film-forming aqueous solution is vacuum filtered on the substrate to obtain a titanium carbide MXene film that is not separated from the substrate;

[0107] The thickness of the obtained titanium carbide MXene film is 1 μm and the mass area density is 1 mg cm -2 , interlayer spacing of 1.3 nm, Herman's orientation factor of 0.75, porosity of 7%, and conductivity of 6000 S·cm -1 , tensile strength is 400MPa, toughness is 10MJ·m -3 ;

[0108] (4) When the titanium carbide MXene film obtained in step (3) that has not been separated from the substrate is isotropically stretched and steam treated, 15 mL of plasticizing solvent is first added to the solvent pool a, and then the titanium carbide MXene film that has not been separated from the substrate is fixed between the upper and lower cylinders a by the membrane fixing screw a (the PP filter membrane is close to the upper cylinder a) and the membrane fixing screw a is adjusted to keep the titanium carbide MXene film that has not been separated from the substrate in a taut state, and then heated by the heating device a until the plasticizing solvent is vaporized, and then kept warm at 90°C for 12 hours, and then the treated titanium carbide MXene film that has not been separated from the substrate is transferred to ethanol, and after the titanium carbide MXene film is detached from the PP filter membrane, it is transferred to cellulose filter paper and placed at 35°C for drying for 24 hours to obtain a titanium carbide film with both high electromagnetic shielding and infrared stealth performance.

[0109] The resulting titanium carbide film has both high electromagnetic shielding and infrared stealth performance, with an interlayer spacing of 1.2 nm, a Herman's orientation factor of 0.95, a porosity of 3%, and a conductivity of 9000 S·cm -1 , tensile strength is 550MPa, toughness is 18MJ·m -3; Titanium carbide film has both high electromagnetic shielding and infrared stealth performance. The infrared emissivity of the titanium carbide film in the 2.5-25μm band is 10%, the electromagnetic shielding effectiveness in the X-band is 55dB, and the unit thickness specific shielding performance is 89000dB·cm 2 ·g -1 .

[0110] The titanium carbide film with high electromagnetic shielding and infrared stealth performance can be applied to the surfaces of aircraft, ships and vehicles, as well as protective clothing.

[0111] Example B2

[0112] The preparation method of titanium carbide film with both high electromagnetic shielding and infrared stealth performance is as follows:

[0113] (1) Preparation of raw materials and equipment used;

[0114] The apparatus used for isotropic stretching and steam treatment was the apparatus described in Example A1, m was 4, the height of the solvent pool a was 8 cm, and the volume was 25 mL;

[0115] PP filter membrane: Celgard 3501 membrane, average pore size 0.22 μm, effective filtration diameter 4 cm, area 12.57 cm 2 ;

[0116] Plasticizing solvent: water;

[0117] Lithium fluoride: CAS number is 7789-24-4;

[0118] Hydrochloric acid aqueous solution: concentration is 9 mol / L;

[0119] Ti3AlC2 powder: CAS number is 196506-01-1;

[0120] Deionized water;

[0121] Ethanol;

[0122] (2) preparing titanium carbide MXene powder;

[0123] (2.1) 3.2 g of lithium fluoride and 40 mL of hydrochloric acid aqueous solution were magnetically stirred in a PTFE beaker for 5 minutes, and then 2 g of Ti3AlC2 powder was added to the solution in batches at a rate of 0.2 g / min and stirred until completely dispersed. The PTFE beaker was then placed in a 40°C water bath and stirred continuously for 30 hours to obtain an etched solution;

[0124] (2.2) After adding deionized water to the etched solution, centrifuge and wash repeatedly until the pH value of the supernatant is 6, collect the precipitate after centrifugation, transfer the precipitate to a flask, add deionized water until the total volume is 200 mL, fill with argon gas, and perform ultrasonic peeling in a water bath at 2°C. After the ultrasonication, collect the upper suspension, centrifuge the suspension at 1500 rpm for 20 minutes, and collect the upper stably dispersed monolayer MXene dispersion. Then, freeze-dry the monolayer MXene dispersion and collect the powder to obtain titanium carbide MXene powder.

[0125] (3) The MXene powder prepared in step (2) was first prepared to a concentration of 1 mg g -1 The MXene film-forming aqueous solution is then prepared by using a PP filter membrane as a substrate, and the titanium carbide MXene film-forming aqueous solution is vacuum filtered on the substrate to obtain a titanium carbide MXene film that is not separated from the substrate;

[0126] The thickness of the obtained titanium carbide MXene film is 10 μm and the mass area density is 2 mg cm -2 , interlayer spacing is 1.5 nm, Herman's orientation factor is 0.6, porosity is 6%, and conductivity is 5500 S·cm -1 , tensile strength is 300MPa, toughness is 8MJ·m -3 ;

[0127] (4) When the titanium carbide MXene film obtained in step (3) that has not been separated from the substrate is isotropically stretched and steam treated, 15 mL of plasticizing solvent is first added to the solvent pool a, and then the titanium carbide MXene film that has not been separated from the substrate is fixed between the upper and lower cylinders a by the membrane fixing screw a (the PP filter membrane is close to the upper cylinder a) and the membrane fixing screw a is adjusted to keep the titanium carbide MXene film that has not been separated from the substrate in a taut state, and then heated by the heating device a until the plasticizing solvent is vaporized, and then kept warm at 110°C for 24 hours, and then the treated titanium carbide MXene film that has not been separated from the substrate is transferred to ethanol, and after the titanium carbide MXene film is detached from the PP filter membrane, it is transferred to cellulose filter paper and placed at 40°C for 18 hours to obtain a titanium carbide film with both high electromagnetic shielding and infrared stealth performance.

[0128] The resulting titanium carbide film has both high electromagnetic shielding and infrared stealth performance, with an interlayer spacing of 1.38 nm, a Herman's orientation factor of 0.75, a porosity of 4%, and a conductivity of 8800 S·cm -1 , tensile strength is 400MPa, toughness is 17MJ·m -3; Titanium carbide film has both high electromagnetic shielding and infrared stealth performance. The infrared emissivity of the titanium carbide film in the 2.5-25μm band is 14%, the electromagnetic shielding effectiveness in the X-band is 52dB, and the unit thickness specific shielding performance is 85000dB·cm 2 ·g -1 .

[0129] The titanium carbide film with high electromagnetic shielding and infrared stealth performance can be applied to the surfaces of aircraft, ships and vehicles, as well as protective clothing.

[0130] Example B3

[0131] The preparation method of titanium carbide film with both high electromagnetic shielding and infrared stealth performance is as follows:

[0132] (1) Preparation of raw materials and equipment used;

[0133] The apparatus used for isotropic stretching and steam treatment was the apparatus described in Example A2, wherein n was 4, m was 3, the height of the solvent pool b was 10 cm, the volume was 150 mL, and the angle between the inclined rod II and the central axis of the cylinder b was 100°;

[0134] PP filter membrane: Celgard 3501 membrane, average pore size 0.22 μm, effective filtration diameter 4 cm, area 12.57 cm 2 ;

[0135] Plasticizing solvent: 50% ethanol aqueous solution;

[0136] Lithium fluoride: CAS number is 7789-24-4;

[0137] Hydrochloric acid aqueous solution: concentration is 9 mol / L;

[0138] Ti3AlC2 powder: CAS number is 196506-01-1;

[0139] Deionized water;

[0140] Ethanol;

[0141] (2) preparing titanium carbide MXene powder;

[0142] (2.1) 3.2 g of lithium fluoride and 40 mL of hydrochloric acid aqueous solution were magnetically stirred in a PTFE beaker for 5 minutes, and then 2 g of Ti3AlC2 powder was added to the solution in batches at a rate of 0.2 g / min and stirred until completely dispersed. The PTFE beaker was then placed in a 40°C water bath and stirred continuously for 30 hours to obtain an etched solution;

[0143] (2.2) After adding deionized water to the etched solution, centrifuge and wash repeatedly until the pH value of the supernatant is 6, collect the precipitate after centrifugation, then transfer the precipitate to a flask and add deionized water until the total volume is 200 mL, fill with argon gas and perform ultrasonic peeling in a water bath at 5°C. After the ultrasonication, collect the upper suspension, centrifuge the suspension at 1500 rpm for 20 minutes, collect the upper stably dispersed monolayer MXene dispersion, and then freeze-dry the monolayer MXene dispersion to collect the powder, thereby obtaining titanium carbide MXene powder;

[0144] (3) The MXene powder prepared in step (2) was prepared to a concentration of 1.5 mg g -1 The MXene film-forming aqueous solution is then prepared by using a PP filter membrane as a substrate, and the titanium carbide MXene film-forming aqueous solution is vacuum filtered on the substrate to obtain a titanium carbide MXene film that is not separated from the substrate;

[0145] The thickness of the obtained titanium carbide MXene film is 50 μm and the mass area density is 5 mg cm -2 , interlayer spacing is 1.55 nm, Herman's orientation factor is 0.7, porosity is 5%, and conductivity is 5000 S·cm -1 , tensile strength is 350MPa, toughness is 7.5MJ·m -3 ;

[0146] (4) When the titanium carbide MXene film that has not been separated from the substrate in step (3) is isotropically stretched and steam treated, 80 mL of plasticizing solvent is first added to the solvent pool b, and then the titanium carbide MXene film that has not been separated from the substrate is fixed between the upper and lower cylinders b by the membrane fixing screws b (the PP filter membrane is close to the upper cylinder a) and the membrane fixing screws b are adjusted to keep the titanium carbide MXene film that has not been separated from the substrate in a taut state, and then heated by the heating device b until the plasticizing solvent is vaporized, and at the same time, the pressing plate is pressed downward and kept warm at 90°C for 12 hours (the maximum tensile displacement of the two-dimensional sheet macroscopic assembly membrane after the insulation is completed is 2 mm), and then the treated titanium carbide MXene film that has not been separated from the substrate is transferred to ethanol, and after the titanium carbide MXene film is detached from the PP filter membrane, it is transferred to cellulose filter paper and placed at 45°C for drying for 12 hours to obtain a titanium carbide film with both high electromagnetic shielding and infrared stealth performance.

[0147] The resulting titanium carbide film has both high electromagnetic shielding and infrared stealth performance, with an interlayer spacing of 1.25 nm, a Herman's orientation factor of 0.78, a porosity of 3%, and a conductivity of 8500 S·cm -1 , tensile strength is 800MPa, toughness is 20MJ·m -3; Titanium carbide film has both high electromagnetic shielding and infrared stealth performance. The infrared emissivity of the titanium carbide film in the 2.5-25μm band is 13%, the electromagnetic shielding effectiveness in the X-band is 55dB, and the unit thickness specific shielding performance is 75000dB·cm 2 ·g -1 .

[0148] The titanium carbide film with high electromagnetic shielding and infrared stealth performance can be applied to the surfaces of aircraft, ships and vehicles, as well as protective clothing.

[0149] Example B4

[0150] The preparation method of titanium carbide film with both high electromagnetic shielding and infrared stealth performance is as follows:

[0151] (1) Preparation of raw materials and equipment used;

[0152] The apparatus used for isotropic stretching and steam treatment was the apparatus described in Example A2, with n being 5, m being 4, the height of the solvent pool b being 12 cm, the volume being 250 mL, and the angle between the inclined rod II and the central axis of the cylinder b being 103°;

[0153] PP filter membrane: Celgard 3501 membrane, average pore size 0.22 μm, effective filtration diameter 4 cm, area 12.57 cm 2 ;

[0154] Plasticizing solvent: water;

[0155] Lithium fluoride: CAS number is 7789-24-4;

[0156] Hydrochloric acid aqueous solution: concentration is 9 mol / L;

[0157] Ti3AlC2 powder: CAS number is 196506-01-1;

[0158] Deionized water;

[0159] Ethanol;

[0160] (2) preparing titanium carbide MXene powder;

[0161] (2.1) 3.2 g of lithium fluoride and 40 mL of hydrochloric acid aqueous solution were magnetically stirred in a PTFE beaker for 5 minutes, and then 2 g of Ti3AlC2 powder was added to the solution in batches at a rate of 0.2 g / min and stirred until completely dispersed. The PTFE beaker was then placed in a 40°C water bath and stirred continuously for 30 hours to obtain an etched solution;

[0162] (2.2) After adding deionized water to the etched solution, the mixture was centrifuged and washed repeatedly until the pH value of the supernatant reached 6. The precipitate after centrifugation was collected, and then the precipitate was transferred to a flask and deionized water was added until the total volume was 200 mL. After filling with argon, ultrasonic peeling was performed in a water bath at 3°C. After the ultrasonication, the upper suspension was collected, and then the suspension was centrifuged at 1500 rpm for 20 minutes to collect the upper layer of stably dispersed monolayer MXene dispersion. The monolayer MXene dispersion was then freeze-dried and the powder was collected to obtain titanium carbide MXene powder.

[0163] (3) The MXene powder prepared in step (2) was first prepared to a concentration of 0.5 mg g -1 The MXene film-forming aqueous solution is then prepared by using a PP filter membrane as a substrate, and the titanium carbide MXene film-forming aqueous solution is vacuum filtered on the substrate to obtain a titanium carbide MXene film that is not separated from the substrate;

[0164] The obtained titanium carbide MXene film has a thickness of 250 μm and a mass area density of 15 mg cm -2 , interlayer spacing is 1.65nm, Herman's orientation factor is 0.65, porosity is 7%, and conductivity is 4200S·cm -1 , tensile strength is 300MPa, toughness is 6.5MJ·m -3 ;

[0165] (4) When the titanium carbide MXene film that has not been separated from the substrate in step (3) is isotropically stretched and steam treated, 150 mL of plasticizing solvent is first added to the solvent pool b, and then the titanium carbide MXene film that has not been separated from the substrate is fixed between the upper and lower cylinders b by the membrane fixing screws b (the PP filter membrane is close to the upper cylinder a) and the membrane fixing screws b are adjusted to keep the titanium carbide MXene film that has not been separated from the substrate in a taut state, and then heated by the heating device b until the plasticizing solvent is vaporized, and at the same time, the pressing plate is pressed downward and kept warm at 100°C for 18 hours (the maximum tensile displacement of the two-dimensional sheet macroscopic assembly membrane after the insulation is completed is 1.5 mm), and then the treated titanium carbide MXene film that has not been separated from the substrate is transferred to ethanol, and after the titanium carbide MXene film is detached from the PP filter membrane, it is transferred to cellulose filter paper and placed at 35°C for 18 hours to obtain a titanium carbide film with both high electromagnetic shielding and infrared stealth performance.

[0166] The resulting titanium carbide film has both high electromagnetic shielding and infrared stealth performance, with an interlayer spacing of 1.3 nm, a Herman's orientation factor of 0.8, a porosity of 5.50%, and a conductivity of 8200 S·cm -1 , tensile strength is 700MPa, toughness is 18MJ·m-3 ; Titanium carbide film has both high electromagnetic shielding and infrared stealth performance. The infrared emissivity of the titanium carbide film in the 2.5-25μm band is 18%, the electromagnetic shielding effectiveness in the X-band is 58dB, and the unit thickness specific shielding performance is 80000dB·cm 2 ·g -1 .

[0167] The titanium carbide film with high electromagnetic shielding and infrared stealth performance can be applied to the surfaces of aircraft, ships and vehicles, as well as protective clothing.

[0168] Example B5

[0169] The preparation method of titanium carbide film with both high electromagnetic shielding and infrared stealth performance is as follows:

[0170] (1) Preparation of raw materials and equipment used;

[0171] The apparatus used for isotropic stretching and steam treatment was the apparatus described in Example A2, with n being 4, m being 3, the height of the solvent pool b being 12 cm, the volume being 250 mL, and the angle between the inclined rod II and the central axis of the cylinder b being 105°;

[0172] PP filter membrane: Celgard 3501 membrane, average pore size 0.22 μm, effective filtration diameter 4 cm, area 12.57 cm 2 ;

[0173] Plasticizing solvent: ethanol;

[0174] Lithium fluoride: CAS number is 7789-24-4;

[0175] Hydrochloric acid aqueous solution: concentration is 9 mol / L;

[0176] Ti3AlC2 powder: CAS number is 196506-01-1;

[0177] Deionized water;

[0178] Ethanol;

[0179] (2) preparing titanium carbide MXene powder;

[0180] (2.1) 3.2 g of lithium fluoride and 40 mL of hydrochloric acid aqueous solution were magnetically stirred in a PTFE beaker for 5 minutes, and then 2 g of Ti3AlC2 powder was added to the solution in batches at a rate of 0.2 g / min and stirred until completely dispersed. The PTFE beaker was then placed in a 40°C water bath and stirred continuously for 30 hours to obtain an etched solution;

[0181] (2.2) After adding deionized water to the etched solution, centrifuge and wash repeatedly until the pH value of the supernatant is 6, collect the precipitate after centrifugation, then transfer the precipitate to a flask and add deionized water until the total volume is 200 mL, fill with argon gas and perform ultrasonic peeling in a water bath at 5°C. After the ultrasonication, collect the upper suspension, centrifuge the suspension at 1500 rpm for 20 minutes, collect the upper stably dispersed monolayer MXene dispersion, and then freeze-dry the monolayer MXene dispersion to collect the powder, thereby obtaining titanium carbide MXene powder;

[0182] (3) The MXene powder prepared in step (2) was prepared to a concentration of 1.5 mg g -1 The MXene film-forming aqueous solution is then prepared by using a PP filter membrane as a substrate, and the titanium carbide MXene film-forming aqueous solution is vacuum filtered on the substrate to obtain a titanium carbide MXene film that is not separated from the substrate;

[0183] The obtained titanium carbide MXene film has a thickness of 500 μm and a mass area density of 20 mg cm -2 , interlayer spacing of 1.7 nm, Herman's orientation factor of 0.68, porosity of 8%, and conductivity of 3000 S·cm -1 , tensile strength is 200MPa, toughness is 5MJ·m -3 ;

[0184] (4) When the titanium carbide MXene film that has not been separated from the substrate in step (3) is isotropically stretched and steam treated, 180 mL of plasticizing solvent is first added to the solvent pool b, and then the titanium carbide MXene film that has not been separated from the substrate is fixed between the upper and lower cylinders b by the membrane fixing screws b (the PP filter membrane is close to the upper cylinder a) and the membrane fixing screws b are adjusted to keep the titanium carbide MXene film that has not been separated from the substrate in a taut state, and then heated by the heating device b until the plasticizing solvent is vaporized, and at the same time, the pressing plate is pressed downward and kept warm at 90°C for 24 hours (the maximum tensile displacement of the two-dimensional sheet macroscopic assembly membrane after the insulation is completed is 1 mm), and then the treated titanium carbide MXene film that has not been separated from the substrate is transferred to ethanol, and after the titanium carbide MXene film is detached from the PP filter membrane, it is transferred to cellulose filter paper and placed at 45°C for drying for 24 hours to obtain a titanium carbide film with both high electromagnetic shielding and infrared stealth performance.

[0185] The resulting titanium carbide film has both high electromagnetic shielding and infrared stealth performance, with an interlayer spacing of 1.35 nm, a Herman's orientation factor of 0.9, a porosity of 6%, and a conductivity of 8000 S·cm -1 , tensile strength is 550MPa, toughness is 15MJ·m -3; Titanium carbide film has both high electromagnetic shielding and infrared stealth performance. The infrared emissivity of the titanium carbide film in the 2.5-25μm band is 20%, the electromagnetic shielding effectiveness in the X-band is 60dB, and the unit thickness specific shielding performance is 90000dB·cm 2 ·g -1 .

[0186] The titanium carbide film with high electromagnetic shielding and infrared stealth performance can be applied to the surfaces of aircraft, ships and vehicles, as well as protective clothing.

Claims

1. A method for preparing a titanium carbide film having both high electromagnetic shielding and infrared stealth performance, characterized in that: After the titanium carbide MXene film is formed by vacuum filtration on the substrate, the titanium carbide MXene film and the substrate are isotropically stretched while being steam treated, and then the substrate is removed to obtain a titanium carbide film with both high electromagnetic shielding and infrared stealth performance; The steam used in the steam treatment is plasticizing steam, which is formed by evaporating a plasticizing solvent having a plasticizing effect on the titanium carbide MXene film, and the plasticizing solvent is water and / or ethanol; The thickness of the titanium carbide MXene film is 1~500μm, the porosity is 5~8%, and the tensile strength is 200~400MPa.

2. The method for preparing a titanium carbide film having both high electromagnetic shielding and infrared stealth performance according to claim 1, characterized in that: The interlayer spacing of titanium carbide MXene films is 1.3~1.72nm, the Herman's orientation factor is 0.6~0.75, and the conductivity is 3000~6000S·cm -1 , toughness is 5~10MJ·m -3 .

3. The method for preparing a titanium carbide film having both high electromagnetic shielding and infrared stealth performance according to claim 2, characterized in that: When the thickness of the titanium carbide MXene film is ≤10 μm, the device used for isotropically stretching the titanium carbide MXene film together with the substrate during steam treatment includes a solvent pool a and a heating device a; the top of the solvent pool a is a vertically arranged cylinder a, the cylinder a is divided into an upper and lower layer and is detachably connected by 2m membrane fixing screws a, m>2, and the 2m membrane fixing screws a are evenly distributed around the circumference of the central axis of the cylinder a; the heating device a is used to heat the solvent pool a; When the thickness of the titanium carbide MXene film is >10 μm, the device used for isotropically stretching the titanium carbide MXene film together with the substrate while treating it with steam includes a solvent pool b, a heating device b, a deformable tube and a regulator; the bottom of the deformable tube is sealed and connected to the top of the solvent pool b, the top of the deformable tube is a vertically arranged cylinder b, the cylinder b is divided into two layers, the upper and lower layers are detachably connected by 2m membrane fixing screws b, m>2, and the 2m membrane fixing screws b are evenly distributed around the circumference of the central axis of the cylinder b; the regulator is used to control the radial outward expansion of the cylinder b along the cylinder b; the heating device b is used to heat the solvent pool b.

4. The method for preparing a titanium carbide film having both high electromagnetic shielding and infrared stealth performance according to claim 3, characterized in that: The regulator includes a displacement bracket, a pressing plate, an upper bracket, a limiting structure and a lower bracket; The displacement bracket is a conical cap-shaped structure with the tip at the top, comprising 2n inclined rods I, n>3, the upper ends of the 2n inclined rods I are simultaneously connected to the center of the lower surface of the pressing plate, and the lower ends are evenly distributed around a point o, the point o is located on the central axis of the pressing plate, and the pressing plate is coaxial with the cylinder b; The upper support includes 2n horizontal rods, which are radially distributed around point o. The two ends of the horizontal rods are respectively marked as end a and end b. End a is closer to point o than end b. The ends a of the 2n horizontal rods are respectively hinged to the lower ends of the 2n oblique rods I in a one-to-one correspondence. The limiting structure restricts the 2n horizontal rods to move only along their own length direction; The b ends of two adjacent horizontal rods are each connected by an arc bar, and at least one set of opposite arc bars is composed of three sections: left, middle and right. The middle section is composed of a separated inner layer and outer layer. The outer layer of the middle section is fixedly connected to the left section, and the inner layer of the middle section is fixedly connected to the right section. All the arc bars form a circular ring, and the circular ring extends vertically downward to form a circular tube. The lower support includes 2n oblique rods II, which are distributed in an umbrella shape around the central axis of the cylinder b. The angle between the oblique rods II and the central axis of the cylinder b is 100-105°. The lower layer of the cylinder b extends radially outward and is connected to the upper ends of the 2n oblique rods II, and the lower ends of the 2n oblique rods II are connected to the circular tube.

5. The method for preparing a titanium carbide film having both high electromagnetic shielding and infrared stealth performance according to claim 4, characterized in that: The regulator also includes a height measuring bracket, which is vertically arranged on one side of the pressing plate and fixedly connected to the upper bracket.

6. The method for preparing a titanium carbide film having both high electromagnetic shielding and infrared stealth performance according to claim 1, characterized in that: The forming process of titanium carbide MXene membrane is as follows: using PP filter membrane as the substrate, -1 The titanium carbide MXene film-forming aqueous solution is vacuum filtered on the substrate to obtain a titanium carbide MXene film that is not separated from the substrate.

7. The method for preparing a titanium carbide film having both high electromagnetic shielding and infrared stealth performance according to claim 1, characterized in that: The interlayer spacing of the titanium carbide film with high electromagnetic shielding and infrared stealth performance is 1.2~1.38nm, the Herman's orientation factor is 0.75~0.95, the porosity is 3~6%, and the conductivity is 8000~9000S·cm -1 , tensile strength is 400~800MPa, toughness is 15~20MJ·m -3 .

8. Application of the titanium carbide film having both high electromagnetic shielding and infrared stealth performance obtained by the preparation method according to any one of claims 1 to 7, characterized in that: Applied to the surfaces of aircraft, ships and vehicles, as well as protective clothing; Titanium carbide film has both high electromagnetic shielding and infrared stealth performance. The infrared emissivity of the film in the 2.5~25μm band is 10~20%, the electromagnetic shielding effectiveness in the X-band is greater than 50dB, and the unit thickness specific shielding performance is 75000~90000dB·cm 2 ·g -1 .

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