A multi-layer material with wave-absorbing and impact-preventing functions and a preparation method thereof

Abstract

This invention relates to the field of composite material technology, and more particularly to a multilayer material with both microwave absorption and shock absorption functions, and its preparation method. The multilayer material, from the outside in, comprises a PMI foam absorbing layer, an ultra-high molecular weight polyethylene (UHMWPE) absorbing layer, a carbon fiber reflective layer, a ceramic layer, and an UHMWPE consumable layer. This invention utilizes the structural design of various material properties to design and fabricate a multilayer structure that combines microwave absorption and shock absorption functions. It exhibits excellent microwave absorption performance in the 2-18 GHz and 26.5-40 GHz bands, while also possessing a certain degree of shock absorption. This multilayer structure can be designed and adjusted according to different microwave absorption and shock absorption requirements, demonstrating significant practicality.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, and in particular to a multilayer material with both wave absorption and shock protection functions, and its preparation method. Background Technology

[0002] To meet the demand for multifunctional materials that combine wave absorption and shock protection, a single material type is often insufficient. Separate design approaches for wave absorption and shock protection frequently result in increased structural thickness and weight, limiting their application in engineering projects. Based on research and analysis, composite materials are considered a more ideal multifunctional material type. Integrated composite material design can fully utilize material properties to achieve lightweight and reduced structural thickness. Wave absorbing materials can generally be divided into two types: coating and structural. While coating materials offer advantages such as ease of use and production, the low strength, cracking susceptibility, and narrow absorption bandwidth of the coating have become core issues limiting their further application. Structural wave absorbing materials can generally be divided into multi-layer and sandwich structures, characterized by their ability to control wave absorption while maintaining a certain load-bearing capacity. Meanwhile, for impact-resistant materials, there is already a relatively mature research foundation for ceramic materials, ultra-high molecular weight polyethylene fibers, Kevlar fibers, and steel plates. Through a survey of existing impact-resistant designs and in combination with the demand for lightweight materials, existing technologies are mostly based on the "ceramic + ultra-high molecular weight polyethylene" structure. The hardness of the ceramic dissipates the impact kinetic energy, so the ceramic is generally placed on the outermost layer. However, the ceramic materials with strong impact resistance generally have the problem of high dielectric constant, which makes it difficult to achieve good impedance matching with air. As a result, when conducting wave absorption design, electromagnetic waves are difficult to penetrate the thick ceramic structure to enter the interior of the material, affecting the electromagnetic loss capacity of the internal wave absorption layer.

[0003] CN108166151A discloses a braided fabric made of ultra-high molecular weight polyethylene (UHMWPE) fibers, comprising a composite layer and polyurethane yarns woven around the composite layer. The composite layer is composed of UHMWPE fiber layers and carbon fiber layers. Several braided blocks made of polyurethane yarns are arranged on one side of the composite layer. The surface of the fabric is coated with a high-temperature resistant nano-coating. The UHMWPE fiber layers undergo surface treatment, which involves grafting acrylic monomers and acrylonitrile onto the polyethylene links of the UHMWPE fiber layers. The grafted acrylonitrile is then subjected to a amine oxime reaction and subsequently chelates metal ions. This invention provides a three-dimensional braided fabric with excellent physical properties, including high strength, high elastic modulus, high shear modulus, long-term high-temperature resistance, good corrosion resistance, and wear resistance. It is also resistant to aging. Furthermore, the modified UHMWPE fibers exhibit good moisture absorption, breathability, flame retardancy, and antibacterial properties.

[0004] CN111811324A discloses a composite material comprising, from the inside out, an inner layer, a transition layer, and an outer layer; the transition layer is fixed to both the inner and outer layers by epoxy resin; the inner layer is composed of carbon fiber and epoxy resin; the transition layer includes a corrugated ceramic plate and ultra-high molecular weight polyethylene fiber cloth surrounding the ceramic plate; hollow rubber microspheres are disposed in the gaps between the ceramic plate and the ultra-high molecular weight polyethylene fiber cloth and filled with epoxy resin; the outer layer is a modified boron carbide ceramic plate; the modified boron carbide ceramic plate is prepared by mixing 50-60 parts by weight of boron carbide fiber, 1-2 parts by weight of cerium oxide, 30-40 parts by weight of silicon carbide, and 6-12 parts by weight of graphene, grinding the mixture in a grinding mill for 58-65 minutes, pressing the ground mixture into shape, and then hot-pressing and sintering it.

[0005] All of the above materials have the problem of being difficult to integrate into a single design. Therefore, how to fully utilize the performance of shock-resistant materials while adhering to the principles of impedance matching and electromagnetic loss in wave-absorbing design, and how to solve the problem of integrating shock-resistant materials and wave-absorbing structures into a single design, is currently a challenge. Summary of the Invention

[0006] The technical problem to be solved by this invention is that existing materials are difficult to integrate wave absorption and shock protection into a single design. To address the shortcomings of existing technologies, this invention provides a multilayer material that combines wave absorption and shock protection functions, as well as its preparation method.

[0007] To address the aforementioned technical problems, in a first aspect, the present invention provides a multilayer material that combines wave absorption and shock absorption functions. The multilayer material comprises, from the outside in, a PMI foam wave-absorbing layer, an ultra-high molecular weight polyethylene wave-absorbing layer, a carbon fiber reflective layer, a ceramic layer, and an ultra-high molecular weight polyethylene consumable layer.

[0008] In this invention, the PMI foam absorbing layer is a combination design of PMI foam and absorbing functional paper. The PMI foam is the dielectric layer of the combined design structure, and the absorbing functional paper is the dielectric loss absorption layer of the combined design structure. As a low dielectric material, the PMI foam acts as the dielectric layer to achieve impedance matching with air, guide electromagnetic waves to penetrate, and thus give full play to the loss capacity of the absorbing functional paper.

[0009] The ultra-high molecular weight polyethylene (UHMWPE) absorbing layer is a combination design of UHMWPE and absorbing functional paper. UHMWPE is the dielectric layer of the combined design structure, and the absorbing functional paper is the dielectric loss absorption layer of the combined design structure. UHMWPE plays a role in impedance matching with PMI foam.

[0010] The microwave-absorbing functional paper, serving as a dielectric loss absorbing layer, is prepared by mixing a certain concentration of carbon-based absorber into a microwave-transparent matrix. Different concentrations of microwave-absorbing functional paper are prepared for combined design of microwave absorption performance. By designing the thickness of the two dielectric layers (PMI foam and ultra-high molecular weight polyethylene) and the concentration of the microwave-absorbing functional paper, electromagnetic impedance matching and electromagnetic loss capabilities are improved, thereby achieving broadband microwave absorption performance. The carbon-based absorber in this invention can be materials such as carbon fiber, graphene, and carbon nanotubes.

[0011] The design of the outer PMI foam absorbing layer is more conducive to achieving high-frequency absorbing performance in the 26.5-40GHz band, while the design of the inner ultra-high molecular weight polyethylene absorbing layer is more conducive to achieving absorbing performance in the 2-18GHz band. Different concentrations of absorbing functional paper are organically combined with PMI foam and ultra-high molecular weight polyethylene medium respectively. By designing the thickness of the medium layer, the concentration of the absorbing functional paper, and the laying order, a broadband absorbing effect is achieved.

[0012] The carbon fiber reflective layer is located at the end of the wave absorption design, so that the remaining electromagnetic waves are reflected back. At the same time, the remaining electromagnetic waves are absorbed a second time by the PMI foam wave absorption layer and the ultra-high molecular weight polyethylene wave absorption layer.

[0013] Ceramic structures are characterized by high hardness and low density, and the thickness of ceramic materials can be adjusted according to the requirements of impact resistance.

[0014] Ultra-high molecular weight polyethylene (UHMWPE) has excellent material toughness and impact resistance. As a UHMWPE consumable layer, it can compensate for the poor toughness of ceramic materials. It consumes impact kinetic energy through material deformation, and the thickness of UHMWPE material can be adjusted according to the impact resistance requirements.

[0015] Preferably, the PMI foam absorbing layer is prepared by the following steps: PMI foam is bonded to the microwave absorbing functional paper with an adhesive film to obtain the PMI foam absorbing layer, which consists of PMI foam, adhesive film and microwave absorbing functional paper from the outside to the inside.

[0016] In this invention, the PMI (polymethacrylimide) foam is selected with a low dielectric constant and cut to the appropriate size. In the multilayer structure of this invention, multiple layers of PMI foam absorbing material can be provided, for example, it can be one layer, two layers, or three layers. The absorbing paper can be any number of sheets, for example, one, two, or three sheets, etc.

[0017] Preferably, the thickness of the PMI foam is 0.5~2mm, for example, it can be 0.5mm, 1mm, 1.5mm or 2mm.

[0018] Preferably, the number of sheets of the microwave-absorbing functional paper in the PMI foam microwave-absorbing layer is 1 to 3, for example, 1, 2 or 3.

[0019] Preferably, the concentration of the microwave-absorbing functional paper in the PMI foam microwave-absorbing layer is 0~3%, for example, it can be 0.1%, 0.5%, 1%, 2% or 3%, etc.

[0020] Preferably, the ultra-high molecular weight polyethylene (UHMWPE) microwave absorbing layer is prepared by the following steps: molding UHMWPE fibers to obtain an UHMWPE fiber plate, and then bonding the UHMWPE fiber plate to the microwave absorbing functional paper through an adhesive film. From the outside to the inside, the structure consists of an UHMWPE fiber plate, an adhesive film, and microwave absorbing functional paper, thus obtaining the UHMWPE microwave absorbing layer.

[0021] In this invention, unidirectional ultra-high molecular weight polyethylene (UHMWPE) fiber fabric is cut to the appropriate size, and the number of layers laid is determined according to the designed thickness. The UHMWPE absorbing layer can be a single layer or multiple layers. The number of sheets of absorbing functional paper in the UHMWPE absorbing layer can be 1, 2, 3, etc.

[0022] Preferably, the thickness of the ultra-high molecular weight polyethylene fiber laminate is 1 to 3 mm, for example, it can be 1 mm, 2 mm or 3 mm.

[0023] Preferably, the number of the microwave-absorbing functional paper sheets in the ultra-high molecular weight polyethylene microwave-absorbing layer is 1 to 3, for example, 1, 2 or 3.

[0024] Preferably, the concentration of the microwave-absorbing functional paper in the ultra-high molecular weight polyethylene microwave-absorbing layer is 3% to 15%, for example, it can be 3%, 5%, 10%, 13% or 15%, etc.

[0025] Preferably, the molding temperature is 100~140℃, for example, it can be 100℃, 110℃, 120℃, 130℃ or 140℃.

[0026] Preferably, the molding pressure is 8~12MPa, for example, it can be 8MPa, 9MPa, 10MPa, 11MPa or 12MPa.

[0027] Preferably, the molding time is 80-100 minutes, for example, it can be 80 minutes, 90 minutes or 100 minutes.

[0028] Preferably, the ceramic layer is prepared by the following steps: mixing ceramic powder, molding it into a green body, performing vacuum debinding, then sintering at high temperature, and polishing to obtain the ceramic layer.

[0029] In this invention, alumina can be selected as the ceramic. The main components of the powder mixture are 99.8% alumina ceramic powder, 0.1% yttrium oxide powder and 0.1% magnesium carbonate powder, which are mixed evenly using a ball mill to obtain a mixed powder.

[0030] Preferably, the temperature of the vacuum degumming is 700~1000℃, for example, it can be 700℃, 800℃, 900℃ or 1000℃.

[0031] Preferably, the high-temperature sintering temperature is 1500~1700℃, for example, 1500℃, 1600℃ or 1700℃, and the time is 4~6h, for example, 4h, 5h or 6h.

[0032] In a second aspect, the present invention provides a method for preparing the multilayer material described in the first aspect. The method comprises: sequentially laying a PMI foam absorbing layer, an ultra-high molecular weight polyethylene absorbing layer, a carbon fiber reflective layer, a ceramic layer, and an ultra-high molecular weight polyethylene consumable layer, bonding and curing them with an adhesive film, and molding them to obtain the multilayer material.

[0033] Preferably, the curing temperature is 80~100℃, for example, it can be 80℃, 90℃ or 100℃.

[0034] Preferably, the curing time is 2 to 5 hours, for example, 2 hours, 3 hours, 4 hours or 5 hours.

[0035] Preferably, the curing pressure is 0.5~1MPa, for example, it can be 0.5MPa, 0.7MPa, 0.9MPa or 1MPa.

[0036] In this invention, the microwave-absorbing functional paper is a carbon-based absorbent of a certain concentration. The microwave-transparent matrix and dispersion are mixed evenly and thoroughly stirred to prepare a slurry. The slurry is then vacuum dehydrated and dried to obtain the following: multiple concentrations and multiple layers can be designed, such as two sheets of 0.2% concentration microwave-absorbing functional paper, two sheets of 0.5% concentration microwave-absorbing functional paper, one sheet of 1.0% concentration microwave-absorbing functional paper, one sheet of 2.0% concentration microwave-absorbing functional paper, two sheets of 3.0% concentration microwave-absorbing functional paper, two sheets of 5.0% concentration microwave-absorbing functional paper, one sheet of 7.0% concentration microwave-absorbing functional paper, two sheets of 10.0% concentration microwave-absorbing functional paper, and one sheet of 12.0% concentration microwave-absorbing functional paper. The thickness of a single layer of microwave-absorbing functional paper is approximately 60 μm. In this invention, the concentration of the microwave-absorbing functional paper refers to the mass percentage of the carbon-based absorbent in the paper.

[0037] The carbon fiber in the carbon fiber reflective layer can be a common carbon fiber in the field, such as the carbon fiber plain weave fabric W-7011 from Haiguangwei Composite Materials Co., Ltd.

[0038] Implementing this invention has the following beneficial effects: The multilayer material provided by this invention reduces or minimizes the increase in structural thickness or weight caused by focusing on a single performance through integrated design. It organically combines a PMI dielectric layer and an ultra-high molecular weight polyethylene dielectric layer with microwave-absorbing functional paper to prepare dielectric absorbing layers with different microwave absorption efficiencies. By selecting materials and designing the layup sequence of the absorbing layers, a broadband microwave absorption effect is achieved. Simultaneously, ultra-high molecular weight polyethylene can serve as both an absorbing dielectric layer and an impact-resistant material, effectively reducing the weight and thickness of the overall structure that integrates microwave absorption and impact resistance. This invention utilizes the structural design of various material properties to design and fabricate a multilayer structure that integrates microwave absorption and impact resistance, exhibiting excellent microwave absorption performance in the 2-18GHz and 26.5-40GHz bands, while also possessing a certain degree of impact resistance. This multilayer structure can be designed and adjusted according to different microwave absorption and impact resistance requirements, demonstrating significant practicality. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of a multi-layer material structure with compatible wave absorption and shock protection functions provided in Embodiment 1 of the present invention.

[0040] Figure 2 This is a flowchart of the preparation process of a multilayer material with compatible wave absorption and shock protection functions provided in Embodiment 1 of the present invention.

[0041] Figure 3A This is a schematic diagram of the reflectivity test performance (2-18GHz) of a multilayer material with compatible wave absorption and shock protection functions provided in Embodiment 1 of the present invention.

[0042] Figure 3B This is a schematic diagram of the reflectivity test performance (26.5~40GHz) of a multilayer material with compatible wave absorption and shock protection functions provided in Embodiment 1 of the present invention.

[0043] Figure 4 A photograph of the back side of the multilayer material with wave-absorbing and shock-resistant functions provided in Embodiment 1 of the present invention, showing its shock resistance performance test. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] Example 1 This embodiment provides a multilayer material that combines wave absorption and shock absorption functions. Generally, in multi-layer structures with compatible wave absorption and shock absorption functions, the density of the wave-absorbing functional paper is designed to increase sequentially from the outside to the inside, with the direction of electromagnetic wave arrival defined as the outer layer. However, since the structure of each layer needs to be matched according to its wave absorption performance, the order of laying the wave-absorbing functional paper density may deviate from the above order and be adjusted locally. This is an adaptive adjustment for those skilled in the art and will not affect understanding and implementation.

[0046] like Figure 1 As shown, by combining the properties of multiple materials in the layering design, it is required to simultaneously possess broadband wave absorption performance of 2-18GHz and 26.5-40GHz, as well as the ability to withstand Type 95 common bullets.

[0047] In this embodiment, there are 9 types of absorbing functional paper: 2 sheets of 0.2% concentration absorbing functional paper, 2 sheets of 0.5% concentration absorbing functional paper, 1 sheet of 1.0% concentration absorbing functional paper, 1 sheet of 2.0% concentration absorbing functional paper, 2 sheets of 3.0% concentration absorbing functional paper, 2 sheets of 5.0% concentration absorbing functional paper, 1 sheet of 7.0% concentration absorbing functional paper, 2 sheets of 10.0% concentration absorbing functional paper, and 1 sheet of 12.0% concentration absorbing functional paper. The thickness of a single layer of absorbing functional paper is approximately 60μm.

[0048] In this embodiment, there are three PMI foam absorbing layers: PMI foam absorbing layer 11, which includes 1mm thick PMI foam and two sheets of 0.2% concentration absorbing functional paper; PMI foam absorbing layer 12, which includes 1mm thick PMI foam and two sheets of 0.5% concentration absorbing functional paper; and PMI foam absorbing layer 13, which includes 1mm thick PMI foam, one sheet of 1.0% concentration absorbing functional paper, and one sheet of 2.0% concentration absorbing functional paper. When the concentration of the absorbing functional paper in a certain PMI foam absorbing layer is two or more, they are laid out in order of increasing concentration from the outside to the inside.

[0049] In this embodiment, there are four ultra-high molecular weight polyethylene (UHMWPE) absorbing layers: UHMWPE absorbing layer 21, comprising 2mm thick UHMWPE and two sheets of 3.0% concentration absorbing functional paper; UHMWPE absorbing layer 22, comprising 2mm thick UHMWPE and two sheets of 5.0% concentration absorbing functional paper; UHMWPE absorbing layer 23, comprising 2mm thick UHMWPE, one sheet of 1.0% concentration absorbing functional paper and one sheet of 10.0% concentration absorbing functional paper; and UHMWPE absorbing layer 24, comprising 2mm thick UHMWPE, one sheet of 10.0% concentration absorbing functional paper and one sheet of 12.0% concentration absorbing functional paper. When the concentration of the absorbing functional paper in a certain UHMWPE absorbing layer is two or more, they are laid out in order of increasing concentration from the outside to the inside.

[0050] In this embodiment, there is one carbon fiber reflective layer 3, with a single layer thickness of 0.2 mm.

[0051] In this embodiment, the ceramic structure 4 consists of 1 layer with a single layer thickness of 8.0 mm.

[0052] In this embodiment, there is one ultra-high molecular weight polyethylene consumption layer 5, with a single layer thickness of 4.0 mm.

[0053] In this embodiment, the layers are bonded and fixed together with epoxy film, and the fixing method can be selected according to the actual situation.

[0054] In this embodiment, the material layup sequence from the outside to the inside is as follows: PMI foam absorbing layer 11, PMI foam absorbing layer 12, PMI foam absorbing layer 13, ultra-high molecular weight polyethylene (UHMWPE) absorbing layer 21, UHMWPE absorbing layer 22, UHMWPE absorbing layer 23, UHMWPE absorbing layer 24, carbon fiber reflective layer 3, 8mm alumina ceramic structure 4, and 4mm UHMWPE consumable layer 5. The laid-up layers are then cured and laminated on a molding machine to obtain an integrated board.

[0055] like Figure 2 As shown, a specific method for preparing a multilayer material with both wave absorption and shock absorption functions is carried out according to the following steps: (1) Preparation of microwave absorbing functional paper A certain concentration of carbon-based absorbent, a microwave-transparent matrix, and a dispersion are mixed evenly and stirred thoroughly to prepare a slurry. The dispersion slurry is then vacuum dehydrated and dried to prepare microwave-absorbing functional papers of different concentrations. The prepared microwave-absorbing functional papers are then cut into 300×300mm pieces. In this embodiment, nine types of microwave absorbing functional paper were prepared: two sheets of 0.2% concentration microwave absorbing functional paper, two sheets of 0.5% concentration microwave absorbing functional paper, one sheet of 1.0% concentration microwave absorbing functional paper, one sheet of 2.0% concentration microwave absorbing functional paper, two sheets of 3.0% concentration microwave absorbing functional paper, two sheets of 5.0% concentration microwave absorbing functional paper, one sheet of 7.0% concentration microwave absorbing functional paper, two sheets of 10.0% concentration microwave absorbing functional paper, and one sheet of 12.0% concentration microwave absorbing functional paper, totaling 14 sheets. The thickness of a single layer of microwave absorbing functional paper is approximately 60 μm. Adaptive adjustments can be made based on the different concentrations of the microwave absorbing functional paper required for the microwave absorbing design.

[0056] (2) Preparation of PMI foam absorbing layer Select PMI foam with low dielectric constant and cut it into 300×300mm pieces; Epoxy film was selected as the adhesive layer and cut into 300×300mm pieces; The adhesive film is laid on one side of the PMI foam. According to the design plan, a certain concentration and quantity of microwave absorbing functional paper are selected and pasted on the adhesive film to form a PMI foam microwave absorbing layer together with the PMI. The PMI foam microwave absorbing layer is arranged from the outside to the inside as follows: PMI foam, adhesive film, microwave absorbing functional paper of the required concentration. When there are two or more types of microwave absorbing functional paper in a certain PMI foam microwave absorbing layer, they are laid in order of increasing concentration from the outside to the inside. In this embodiment, three types of PMI foam absorbing layers 11-13 are designed. PMI foam absorbing layer 11, from the outside in, consists of 1mm thick PMI foam, a film, and two sheets of 0.2% concentration absorbing functional paper. PMI foam absorbing layer 12, from the outside in, consists of 1mm thick PMI foam, a film, and two sheets of 0.5% concentration absorbing functional paper. PMI foam absorbing layer 13, from the outside in, consists of 1mm thick PMI foam, a film, one sheet of 1.0% concentration absorbing functional paper, and one sheet of 2.0% concentration absorbing functional paper. The thickness of the PMI foam and the concentration and quantity of the absorbing functional paper can be adjusted according to different absorption performance requirements.

[0057] (3) Preparation of ultra-high molecular weight polyethylene layer (this ultra-high molecular weight polyethylene layer can be directly used as an ultra-high molecular weight polyethylene consumption layer, and at the same time as the basis for the preparation of ultra-high molecular weight polyethylene microwave absorbing layer) The ultra-high molecular weight polyethylene fiber unidirectional fabric is cut into the corresponding size, and the number of layers is determined according to the design thickness. In this specific embodiment, the ultra-high molecular weight polyethylene fiber unidirectional fabric is cut into 300×300mm. The cut fiber cloth is placed in the molding machine according to the number of layers, and the ultra-high molecular weight polyethylene fiber layer is cured by molding process. The curing process is 120℃, pressure 10MPa, and heat and pressure holding for 90min. After curing, cool to room temperature, remove the layer, and trim the edges. In this embodiment, four 2mm thick UHMWPE layers and one 4mm thick UHMWPE layer were designed. The thickness and quantity of UHMWPE can be adjusted according to different requirements for wave absorption performance and impact resistance.

[0058] (4) Preparation of ultra-high molecular weight polyethylene microwave absorbing layer Epoxy film was selected as the adhesive layer and cut into 300×300mm pieces; Determine the required thickness and size of the ultra-high molecular weight polyethylene layer, attach the adhesive film to one side, select a certain concentration and quantity of microwave absorbing functional paper and attach it to the adhesive film, together with the ultra-high molecular weight polyethylene to form an ultra-high molecular weight polyethylene microwave absorbing layer. The ultra-high molecular weight polyethylene (UHMWPE) microwave absorbing layer consists of, from the outside in, UHMWPE, film, and microwave absorbing functional paper of the required concentration. In this embodiment, four types of ultra-high molecular weight polyethylene (UHMWPE) absorbing layers 21-24 are designed. UHMWPE absorbing layer 21 consists of, from the outside in, 2mm thick UHMWPE, a film, and two sheets of 3.0% concentration absorbing functional paper. UHMWPE absorbing layer 22 consists of, from the outside in, 2mm thick UHMWPE, a film, and two sheets of 5.0% concentration absorbing functional paper. UHMWPE absorbing layer 23 consists of, from the outside in, 2mm thick UHMWPE, a film, one sheet of 1.0% concentration absorbing functional paper, and one sheet of 10.0% concentration absorbing functional paper. UHMWPE absorbing layer 24 consists of, from the outside in, 2mm thick UHMWPE, a film, one sheet of 10.0% concentration absorbing functional paper, and one sheet of 12.0% concentration absorbing functional paper. When the concentration of the absorbing functional paper in a certain UHMWPE absorbing layer is two or more, they are laid out in order of increasing concentration from the outside in.

[0059] (5) Preparation of ceramic structures Alumina was selected as the ceramic in this embodiment. 99.8% alumina ceramic powder, 0.1% yttrium oxide powder and 0.1% magnesium carbonate powder were mixed evenly in a ball mill to obtain a mixed powder, and then stirred and ground for 24-36 hours. The powder, after grinding and mixing, is pressed into alumina green blanks of the required size using a dry pressing method. The alumina billet was placed in a vacuum degumming furnace for vacuum degumming at a temperature of 800℃. The degummed alumina blanks were stacked in a high-temperature sintering furnace and sintered at a temperature of 1650℃ for 5 hours. The sintered ceramic blank is then ground to the required thickness. In this embodiment, an 8mm thick alumina ceramic layer 4 is designed, consisting of one piece. The thickness of the ceramic layer can be adjusted according to different impact resistance requirements.

[0060] (6) Preparation of multilayer materials with compatible wave absorption and shock absorption functions In this embodiment, carbon fiber reflective layer 3 is selected as the reflective layer at the end of the wave absorption design. In this specific embodiment, an epoxy film is selected as the interlayer adhesive film, but other adhesive films are allowed to be used. The epoxy film was cured using a molding process. The curing parameters were: temperature 90℃, holding time 3h, and pressure 0.7MPa. After curing, the pressure was maintained and the temperature was lowered to room temperature to complete the preparation of a multilayer material with compatible wave absorption and shock protection functions.

[0061] The multilayer material provided in this embodiment was tested: the absorption performance was verified using a radar reflectivity testing system, with test frequencies of 2-18 GHz and 26.5-40 GHz. The test performance was that the average reflectivity of the flat plate was ≤-8 dB for 2-4 GHz, ≤-10 dB for 4-18 GHz, and ≤-10 dB for 26.5-40 GHz.

[0062] like Figure 3A and Figure 3B As shown, the prepared broadband absorbing and shockproof integrated multilayer material has good absorbing effect in the 2-18GHz and 26.5-40GHz broadband range.

[0063] The prepared multi-layered material, compatible with wave absorption and shock protection functions, withstood two Type 95 ordinary bullets with a bullet velocity of 940±15 m / s without penetration.

[0064] Example 2 The difference between this embodiment and Embodiment 1 is that in the multilayer material provided in this embodiment, there is only one PMI foam absorbing layer and one ultra-high molecular weight polyethylene absorbing layer. The absorbing performance and impact resistance of the multilayer material are significantly reduced, and it has virtually no absorbing performance.

[0065] Example 3 The difference between this embodiment and Embodiment 1 is that in the multilayer material provided in this embodiment, there are two PMI foam absorbing layers and three ultra-high molecular weight polyethylene absorbing layers. The absorption bandwidth of the multilayer material is narrower.

[0066] Comparative Example 1 The difference between this comparative example and Example 1 is that the multilayer material provided in this comparative example does not contain a PMI foam absorbing layer. The impact resistance of this multilayer material is not significantly affected, but its wave absorption performance is deteriorated.

[0067] Comparative Example 2 The difference between this comparative example and Example 1 is that the multilayer material provided in this comparative example does not contain an ultra-high molecular weight polyethylene (UHMWPE) microwave absorbing layer. This multilayer material exhibits reduced impact resistance and microwave absorption performance.

[0068] Comparative Example 3 The difference between this comparative example and Example 1 is that the multilayer material provided in this comparative example does not contain an ultra-high molecular weight polyethylene (UHMWPE) consumption layer. The microwave absorption performance of this multilayer material is unaffected, but its impact resistance is reduced.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-layer material with wave-absorbing and impact-preventing functions, characterized in that, The multilayer material, from the outside in, includes a PMI foam absorbing layer, an ultra-high molecular weight polyethylene absorbing layer, a carbon fiber reflective layer, a ceramic layer, and an ultra-high molecular weight polyethylene consumable layer.

2. The multi-layer material of claim 1, wherein, The PMI foam absorbing layer is prepared by the following steps: PMI foam is bonded to the microwave absorbing functional paper with an adhesive film to obtain the PMI foam absorbing layer, which consists of PMI foam, adhesive film and microwave absorbing functional paper from the outside to the inside.

3. The multilayer material according to claim 2, characterized in that, The thickness of the PMI foam is 0.5~2mm; Preferably, the number of sheets of the microwave-absorbing functional paper is 1 to 3; Preferably, the concentration of the microwave absorbing functional paper is 0-3%.

4. The multilayer material according to claim 1, characterized in that, The ultra-high molecular weight polyethylene (UHMWPE) microwave absorbing layer is prepared by the following steps: UHMWPE fibers are molded to obtain an UHMWPE fiber plate, and then the UHMWPE fiber plate is bonded to the microwave absorbing functional paper through an adhesive film. From the outside to the inside, the structure consists of an UHMWPE plate, an adhesive film, and microwave absorbing functional paper, thus obtaining the UHMWPE microwave absorbing layer.

5. The multilayer material according to claim 4, characterized in that, The thickness of the ultra-high molecular weight polyethylene fiber laminate is 1~3mm; Preferably, the number of sheets of the microwave-absorbing functional paper is 1 to 3; Preferably, the concentration of the microwave absorbing functional paper is 3% to 15%.

6. The multilayer material according to claim 4, characterized in that, The molding temperature is 100~140℃; Preferably, the molding pressure is 8~12MPa; Preferably, the molding time is 80-100 minutes.

7. The multilayer material according to claim 1, characterized in that, The ceramic layer is prepared by the following steps: mixing ceramic powder, molding it into a green body, vacuum debinding, high-temperature sintering, and polishing to obtain the ceramic layer.

8. The multilayer material according to claim 7, characterized in that, The temperature for vacuum degumming is 700~1000℃; Preferably, the high-temperature sintering temperature is 1500~1700℃ and the time is 4~6h.

9. The method for preparing multilayer materials according to claim 1, characterized in that, The preparation method is as follows: PMI foam absorbing layer, ultra-high molecular weight polyethylene absorbing layer, carbon fiber reflective layer, ceramic layer and ultra-high molecular weight polyethylene consumable layer are sequentially laid, bonded and cured with adhesive film, and then molded to obtain the multilayer material.

10. The preparation method according to claim 9, characterized in that, The curing temperature is 80~100℃; Preferably, the curing time is 2-5 hours; Preferably, the curing pressure is 0.5~1MPa.

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