Bulletproof multi-layer nested shuttlecock structure mechanical unit and preparation method thereof

Abstract

The invention discloses a bulletproof multilayer nested shuttlecock structure mechanical unit and a preparation method thereof, and belongs to the technical field of bulletproof composite material structures. The structural mechanics unit comprises a ceramic base, a first ceramic chip, a second ceramic chip, a first metal buffer layer, a second metal buffer layer and a third metal buffer layer, wherein the first ceramic chip and the second ceramic chip are integrally formed on the ceramic base in a layered mode. The ceramic base 1 is located at the bottommost part, and the first metal buffer layer, the first ceramic chip, the second metal buffer layer, the second ceramic chip and the third metal buffer layer are sequentially placed on the ceramic base from bottom to top. The preparation method of the structural mechanical unit comprises the steps of base blank preparation, primary sintering, dipping, forming and secondary sintering. The bulletproof device solves the problems that an existing bulletproof device is not resistant to abrasion and high temperature and poor in impact resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of bulletproof composite material structures, and in particular to a bulletproof multi-layer nested shuttlecock structural mechanical unit and a preparation method thereof. Background Art

[0002] With the development of military weaponry, bulletproof equipment and structures have become crucial safeguards for the safety of personnel involved in counter-terrorism, riot control, and even military operations. In bulletproof structures, impact-resistant materials play a key role in absorbing kinetic energy, providing stopping power, and providing shock absorption and buffering, and they also determine the ballistic performance of the equipment. Different structures and materials have different ballistic performance characteristics. Existing bulletproof equipment often suffers from various issues, including heat resistance, abrasion resistance, and easy breakage and shattering when struck. In the field of military protective equipment, there is an urgent need for high-impact bulletproof structures with stable performance and sustained protection.

[0003] Chinese patent CN119374415A discloses a three-way woven bulletproof structure that achieves structural solidification through high-temperature pressing and glue coating. The aramid fiber in the bulletproof structure, a representative material for new bulletproof fibers, possesses high strength and toughness. It can undergo significant elastic deformation upon impact to prevent the fiber layer from breaking and mitigate the impact force generated by the projectile. The three-way woven structure in the bulletproof structure guides stress propagation, creating a three-dimensional stress propagation pattern, avoiding stress concentration and effectively enhancing the bulletproof material's penetration resistance. However, this bulletproof fiber material suffers from thermal denaturation at high temperatures. When exposed to high-speed projectiles, it experiences aerodynamic friction and stalling, generating significant heat release and causing a rapid temperature rise, further leading to failure of the bulletproof structure.

[0004] Chinese patent CN114750469B discloses a bullet-resistant composite material containing a negative Poisson's ratio ceramic structure and its preparation method. The composite intermediate layer is formed by filling a polyurethane structural adhesive between hourglass-shaped ceramic units and connecting them to upper and lower ceramic block layers. During bullet penetration, the hard phase ceramic achieves impact resistance with its stable physicochemical properties and extremely high hardness. The polyurethane structural adhesive layer provides excellent elastic buffering. When subjected to ceramic forces, it can further absorb the transmitted kinetic energy by strengthening elastic deformation. The weight of this structure is reduced by 15-20% compared to ordinary ceramic bulletproof layers, and the anti-ballistic performance is improved by more than 20% compared to ceramic plates of equal mass, achieving a comprehensive improvement in the lightness and strength of the bulletproof structure. However, the bonding strength of the polyurethane-ceramic interface is relatively low. When facing high-speed projectiles, the reverse impulse generated by the stressed ceramic block layer causes it to break and fragment, making it difficult to withstand secondary impacts.

[0005] Considering that existing bulletproof materials are difficult to have both continuous impact resistance and high-temperature stable structure, developing a bulletproof structure with high hardness, high temperature resistance and resistance to continuous strikes is of great significance in the field of military protective equipment. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the present invention provides a bulletproof multi-layer nested shuttlecock structural mechanical unit and a preparation method thereof, which solves the problems of poor wear resistance, high temperature resistance and impact resistance of existing bulletproof devices.

[0007] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows: A multi-layer, nested, bulletproof shuttlecock structural mechanical unit comprises a ceramic base, a first and second ceramic sheet integrally formed on the base, a first metal buffer layer, a second metal buffer layer, and a third metal buffer layer. The ceramic base is located at the bottom, and the first metal buffer layer, first ceramic sheet, second metal buffer layer, second ceramic sheet, and third metal buffer layer are placed on the ceramic base in this order, from bottom to top.

[0008] The vertical projection of the ceramic base is a regular hexagon with a side length of 11.2-11.8 mm, a distance from the opposite side of 19.7-20.3 mm, and a height of 3.8-4.2 mm; A square pillar with a side length of 3.8-4.2 mm and a height of 10.7-11.3 mm is provided in the center of the ceramic base; The vertical projections of the first metal buffer layer, the first ceramic sheet, the second metal buffer layer, the second ceramic sheet, and the third metal buffer layer are all regular hexagons, with side lengths of 11.2-11.8 mm and opposite side distances of 19.7-20.3 mm; The center of each of the first metal buffer layer, the first ceramic sheet, the second metal buffer layer, the second ceramic sheet, and the third metal buffer layer has a square with a side length of 3.8-4.2 mm.

[0009] A method for preparing the aforementioned bulletproof multi-layer nested shuttlecock structural mechanical unit comprises preparing a base blank, primary sintering, impregnation, molding, and secondary sintering; The base green body is prepared by mixing raw material powder with a sintering aid and drying to obtain a mixed raw material powder; the mixed raw material powder is filled into a rubber mold, vibrated and compacted, and then vacuum-sealed, and cold isostatically pressed and polished to obtain the base green body; In the preparation of the base blank, the raw material powder is one of high-purity α-SiC powder, high-purity B4C powder, and high-purity Al2O3 powder; The purity of the raw material powder is ≥99.9%, and the particle size D50 is 1.2 μm; The sintering aid is one of a Y2O3-Al2O3 sintering aid or a MgO-Y2O3 sintering aid; When the sintering aid is a Y2O3-Al2O3 sintering aid, the mass ratio of Y2O3 to Al2O3 is 1:0.8-1.2; When the sintering aid is MgO-Y2O3 sintering aid, the mass ratio of MgO to Y2O3 is 1:0.8-1.2; The mass fraction of the sintering aid in the mixed raw material powder is 0.8-1.2%; The inner cavity of the rubber mold is a regular hexagon with a side length of 12.2-12.8 mm, a distance from the opposite sides of 21.5-22.5 mm, a height of 4.2-4.6 mm, and a square pillar hole with a side length of 4.3-4.7 mm and a height of 11.7-12.3 mm reserved in the center; The cold isostatic pressing pressure is 180-220 MPa, and the holding time is 25-35 min; The primary sintering is to sinter the base body by first heating it to 1650-2050°C, keeping it at 1650-2050°C for 3-4 hours, then cooling it to 750-850°C, and then naturally cooling it to room temperature to obtain a ceramic base; During the primary sintering, the heating rate when the temperature reaches 1650-2050°C is 10-15°C / min; The sintering is carried out in an argon protective atmosphere or an air atmosphere; The cooling rate when cooling to 750-850℃ is 4-6℃ / min; When cooling to room temperature, natural cooling method is adopted; The impregnation comprises impregnating the carbon fiber bundle with a high-temperature resistant polyimide resin. During the impregnation, the carbon fiber bundle is first pretreated and then impregnated with the resin using a solution impregnation method to obtain an impregnated carbon fiber bundle; and high-temperature curing is performed on the impregnated carbon fiber bundle to obtain a carbon fiber prepreg. In the impregnation, the high-temperature resistant polyimide resin is model 705-292A, has a brown-red viscous liquid appearance, a solid content of 62%±2%, and a dynamic viscosity of 420 mPa·s at 25°C; The carbon fiber bundle is a 24K carbon fiber bundle; Each of the carbon fiber bundles contains 24,000 single filaments, the single filament diameter is 7 μm, and the carbon fiber length is 5 mm; The carbon fiber bundle has a tensile strength of 5.2 GPa and a modulus of 240 GPa; The pretreatment is to remove the sizing agent on the surface of the carbon fiber by oxidation in an oven at 150-170°C; The resin impregnation is performed by pulling the carbon fiber bundle at a constant speed through a thermostatic resin tank at a temperature of 35-45°C, and then extruding and penetrating the resin and pre-curing at 95-105°C to evaporate the solvent; The high temperature curing is carried out under nitrogen atmosphere protection, and the impregnated carbon fiber bundle is kept warm and pressurized at 220-230° C. and 3.4-3.6 MPa for 110-130 minutes; The volume fraction of the carbon fiber bundle in the carbon fiber prepreg is 60-70%; The molding method comprises the following steps: preparing a final mold by combining the flexible rubber and the ceramic base; taking the ceramic base as the bottom, firstly evenly laying a 1.9-2.1mm thick treated aluminum alloy powder on the ceramic base, and evenly laying a 0.2-0.22mm thick carbon fiber prepreg on the treated aluminum alloy powder as the raw material of the first metal buffer layer; after vibrating and compacting the raw material of the first metal buffer layer, evenly laying a 3.2-3.4mm thick mixed raw material powder on the top as the raw material of the first ceramic sheet; after vibrating and compacting the raw material of the first ceramic sheet, evenly laying a 1.9-2.1mm thick treated aluminum alloy powder on the top, and evenly laying a 0.2-0.22mm thick carbon fiber prepreg on the top as the raw material of the first metal buffer layer; A 0.2-0.22 mm thick carbon fiber prepreg is evenly laid on the top layer of the alloy powder as the second metal buffer layer; after the raw materials for the second metal buffer layer are vibrated and compacted, a 3.2-3.4 mm thick mixed raw material powder is evenly laid on top of it as the raw material for the second ceramic sheet; after the raw materials for the silicon carbide ceramic layer are vibrated and compacted, a 2.8-3.2 mm thick processed aluminum alloy powder is evenly laid on top of it, and a 0.3-0.33 mm thick carbon fiber prepreg is evenly laid on the top layer of the aluminum alloy powder as the raw material for the third metal buffer layer; the entire mold is vibrated and compacted, then vacuum-sealed, cold isostatically pressed, and polished to obtain the final blank; In the molding process, the mixed raw material powder is prepared by mixing the raw material powder with a sintering aid and drying; The raw material powder is one of high-purity α-SiC powder, high-purity B4C powder, and high-purity Al2O3 powder; The purity of the raw material powder is ≥99.9%, and the particle size D50 is 1.2 μm; The sintering aid is one of a Y2O3-Al2O3 sintering aid or a MgO-Y2O3 sintering aid; When the sintering aid is a Y2O3-Al2O3 sintering aid, the mass ratio of Y2O3 to Al2O3 is 1:0.8-1.2; When the sintering aid is MgO-Y2O3 sintering aid, the mass ratio of MgO to Y2O3 is 1:0.8-1.2; The mass fraction of the sintering aid in the mixed raw material powder is 0.8-1.2%; The method for preparing the treated aluminum alloy powder comprises: performing hydrogenation degreasing pretreatment on the aluminum alloy powder and drying; The preparation method of the final mold is as follows: the mold is designed with the upper surface of the ceramic base as the bottom, and the other surfaces are composed of rubber. The inner cavity is a regular hexahedron with a side length of 12.3-12.7 mm, a distance from the opposite sides of 21.7-22.3 mm, and a height of 14.2-14.5 mm.

[0010] The secondary sintering is to fix the final green body in a mold and perform sintering, first heating to 1650-2050°C, keeping at 1650-2050°C for 3-4 hours, then cooling to 750-850°C, and then naturally cooling to room temperature to obtain a bulletproof multi-layer nested shuttlecock structural mechanical unit; During the secondary sintering, the heating rate when the temperature reaches 1650-2050°C is 10-15°C / min; The sintering is carried out in an argon protective atmosphere or an air atmosphere; The cooling rate when cooling to 750-850℃ is 4-6℃ / min; When cooling to room temperature, natural cooling method is adopted; The material of the mold is graphite; When the final green body is fixed in the mold, the gap between the inner wall of the mold and the final green body is controlled to be less than 0.05 mm, and the ceramic base is facing downward.

[0011] Compared with the prior art, the present invention has the following beneficial effects: (1) The bulletproof multi-layer nested shuttlecock structural mechanical unit of the present invention uses ceramic as a base. Utilizing the wear resistance, corrosion resistance, and high temperature resistance of ceramic, it achieves stable physical and chemical properties, improves its applicability to different environments and projectiles, and simultaneously utilizes its high hardness to effectively block high-speed projectiles. Through metal-ceramic lamination and gap filling, the ductility of the metal is utilized to toughen the bulletproof structure and enhance elastic deformation. Furthermore, the high bonding strength of the metal-ceramic interface is utilized to exert a strong constraint on the ceramic unit on the load-bearing surface, limiting the shedding of broken ceramic blocks under impact, improving the durability of the bulletproof structure, achieving resistance to multiple hits, and significantly improving the ballistic performance of existing protective equipment.

[0012] (2) The bulletproof multi-layer nested shuttlecock structural mechanical unit of the present invention solves the problems of poor wear resistance, poor high temperature resistance and poor impact resistance of existing bulletproof devices. According to NIJ Standard-0101.06 / NATO STANAG The bulletproof multi-layer nested shuttlecock ball structure mechanical unit of the present invention was fired three times in a row according to the 4569 standard, and the bullets did not penetrate and no fragments collapsed. The bulletproof multi-layer nested shuttlecock ball structure mechanical unit of the present invention was subjected to a high temperature resistance test. The unit was kept at 600°C, 800°C, and 1000°C (argon protection) for 2 hours. The bending strength retention rate at 600°C was 85-90%, the bending strength retention rate at 800°C was 70-80%, and the bending strength retention rate at 1000°C was 50-60%. In an air atmosphere, the unit was kept at 800°C and 1000°C for 50 hours, and then air-cooled to room temperature. The mass loss rate at 800°C was 1.5-4.0%, and the mass loss rate at 1000°C was 4.0-7.0%. The wear resistance test of the bulletproof multi-layer nested shuttlecock ball structure mechanical unit of the present invention was carried out. The wear rate at room temperature was 1.0×10 -6 -1.8×10 -6 mm 3 / N•m, friction coefficient 0.2-0.35; at high temperature (400°C), the wear rate increases by 20-30%, and the friction coefficient fluctuates by 12-18%; the surface hardness test of the bulletproof multi-layer nested shuttlecock structural mechanical unit of the present invention is carried out, and the room temperature hardness is 2000-3500HV (dominated by silicon carbide phase), and the hardness retention rate at 400°C is 85-90%. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The three views and cross-sectional views of the mechanical unit of the bulletproof multi-layer nested shuttlecock structure of the present invention are shown; wherein a is a front view, b is a left view, c is a top view, and d is a cross-sectional view; Figure 2 The following are component diagrams and assembly diagrams of the bulletproof multi-layer nested shuttlecock structural mechanical unit of the present invention; wherein a is a component diagram of the ceramic base and ceramic sheet, b and c are assembly diagrams of the base and ceramic sheet, and d is an assembly diagram of the base, ceramic sheet, and metal buffer layer; Figure 1 and Figure 2 The descriptions of the labels are as follows: 1-ceramic base, 2-first ceramic sheet, 3-second ceramic sheet, 4-first metal buffer layer, 5-second metal buffer layer, 6-third metal buffer layer. DETAILED DESCRIPTION

[0014] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described.

[0015] The following detailed description of the embodiments of the present invention is provided in conjunction with the accompanying drawings and examples, which is intended to more clearly illustrate the technical solutions of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art may adjust the materials, process parameters or structural design according to actual needs, and such adjustments shall fall within the scope of the claims of the present invention.

[0016] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0017] It should be noted that in the description of the embodiments of the present application, the terms "front, rear", "left, right", "up, down", etc. indicating directions or positional relationships are all based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present application. The terms "install", "connect", and "connected" should be understood in a broad sense. For example, they can be fixedly connected, detachably connected, or integrally connected; they can be directly connected, or indirectly connected through an intermediate medium, or they can be internal connections between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0018] The embodiment of the present invention provides a bulletproof multi-layer nested shuttlecock structural mechanical unit, such as Figure 1 and Figure 2 As shown, it includes a ceramic base 1, a first ceramic sheet 2 and a second ceramic sheet 3, which are layered and integrally formed on the ceramic base, a first metal buffer layer 4, a second metal buffer layer 5, and a third metal buffer layer 6. The ceramic base 1 is located at the bottom, and from bottom to top, the first metal buffer layer 4, the first ceramic sheet 2, the second metal buffer layer 5, the second ceramic sheet 3, and the third metal buffer layer 6 are placed on the ceramic base 1 in this order.

[0019] The vertical projection of the ceramic base 1 is a regular hexagon with a side length of 11.5 mm, a distance from the opposite side of 20 mm, and a height of 4 mm; A square pillar with a side length of 4 mm and a height of 11 mm is provided in the center of the ceramic base 1; The vertical projections of the first metal buffer layer 4, the first ceramic sheet 2, the second metal buffer layer 5, the second ceramic sheet 3, and the third metal buffer layer 6 are all regular hexagons, each with a side length of 11.5 mm and a distance between opposite sides of 20 mm; The center of the first metal buffer layer 4 , the first ceramic sheet 2 , the second metal buffer layer 5 , the second ceramic sheet 3 , and the third metal buffer layer 6 all have a square with a side length of 4 mm.

[0020] The aforementioned bulletproof multi-layer nested shuttlecock structural mechanical unit can utilize metal-ceramic lamination and gap-filling design to increase the impact resistance of the bulletproof structure and achieve structural sustainability.

[0021] The embodiment of the present invention further provides a method for preparing the aforementioned bulletproof multi-layer nested shuttlecock structural mechanical unit, comprising preparing a base blank, primary sintering, impregnation, molding, and secondary sintering; The base green body is prepared by mixing raw material powder with a sintering aid and drying to obtain a mixed raw material powder; the mixed raw material powder is filled into a rubber mold, vibrated and compacted, and then vacuum-sealed, and cold isostatically pressed and polished to obtain the base green body; In the preparation of the base blank, the raw material powder is one of high-purity α-SiC powder, high-purity B4C powder, and high-purity Al2O3 powder; The purity of the raw material powder is ≥99.9%, and the particle size D50 is 1.2 μm; The sintering aid is one of a Y2O3-Al2O3 sintering aid or a MgO-Y2O3 sintering aid; When the sintering aid is a Y2O3-Al2O3 sintering aid, the mass ratio of Y2O3 to Al2O3 is 1:1; When the sintering aid is MgO-Y2O3 sintering aid, the mass ratio of MgO to Y2O3 is 1:1; The mass fraction of the sintering aid in the mixed raw material powder is 1%; The inner cavity of the rubber mold is a regular hexagon with a side length of 12.5 mm, a distance from the opposite side of 22 mm, and a height of 4.4 mm. A square support hole with a side length of 4.4 mm and a height of 12 mm is reserved in the center. The cold isostatic pressing pressure is 200 MPa and the holding time is 30 min; The primary sintering is to sinter the base body by first heating it to 1650-2050°C, keeping it at 1650-2050°C for 3 hours, then cooling it to 800°C, and then naturally cooling it to room temperature to obtain a ceramic base 1; During the primary sintering, the heating rate when the temperature reaches 1650-2050°C is 10-15°C / min; The sintering is carried out in an argon protective atmosphere or an air atmosphere; The cooling rate when cooling to 800°C is 5°C / min; When cooling to room temperature, natural cooling method is adopted; The impregnation comprises impregnating the carbon fiber bundle with a high-temperature resistant polyimide resin. During the impregnation, the carbon fiber bundle is first pretreated and then impregnated with the resin using a solution impregnation method to obtain an impregnated carbon fiber bundle; and high-temperature curing is performed on the impregnated carbon fiber bundle to obtain a carbon fiber prepreg. The model of the high-temperature resistant polyimide resin is 705-292A, and its appearance is a brown-red viscous liquid with a solid content of 62%±2% and a dynamic viscosity of 420 mPa·s at 25°C. The carbon fiber bundle is a 24K carbon fiber bundle; Each of the carbon fiber bundles contains 24,000 single filaments, the single filament diameter is 7 μm, and the carbon fiber length is 5 mm; The carbon fiber bundle has a tensile strength of 5.2 GPa and a modulus of 240 GPa; The pretreatment is to remove the sizing agent on the surface of the carbon fiber by oxidation in an oven at 150°C; The resin impregnation is performed by pulling the carbon fiber bundle at a constant speed through a thermostatic resin tank at a temperature of 40°C, and then extruding and penetrating the resin and pre-curing at 100°C to evaporate the solvent; The high temperature curing is carried out under nitrogen atmosphere protection, and the impregnated carbon fiber bundle is kept warm and pressurized at 225° C. and 3.5 MPa for 120 minutes; The volume fraction of the carbon fiber bundle in the carbon fiber prepreg is 65%; The molding is to prepare the final mold together with the flexible rubber and the ceramic base 1, with the ceramic base 1 as the bottom, first evenly laying a 2mm thick layer of processed aluminum alloy powder on the ceramic base 1, and evenly laying a 0.2mm thick carbon fiber prepreg on the treated aluminum alloy powder as the raw material of the first metal buffer layer 4; after the raw material of the first metal buffer layer 4 is vibrated and compacted, a 3.3mm thick mixed raw material powder is evenly laid on it as the raw material of the first ceramic sheet 2; after the raw material of the first ceramic sheet 2 is vibrated and compacted, a 2mm thick layer of processed aluminum alloy powder is evenly laid on it, and the treated carbon fiber prepreg is evenly laid on the top. A 0.2 mm thick carbon fiber prepreg is evenly laid on the upper layer of the aluminum alloy powder to serve as the second metal buffer layer 5. After the raw materials for the second metal buffer layer 5 are vibrated and compacted, a 3.3 mm thick mixed raw material powder is evenly laid on top of it to serve as the raw material for the second ceramic sheet 3. After the raw materials for the silicon carbide ceramic layer 3 are vibrated and compacted, a 3 mm thick treated aluminum alloy powder is evenly laid on top of it, and a 0.3 mm thick carbon fiber prepreg is evenly laid on the upper layer of the aluminum alloy powder to serve as the raw material for the third metal buffer layer 6. The mold is vibrated and compacted as a whole, then vacuum-sealed, cold isostatically pressed, and polished to obtain the final blank. In the molding process, the mixed raw material powder is prepared by mixing the raw material powder with a sintering aid and drying; The raw material powder is one of high-purity α-SiC powder, high-purity B4C powder, and high-purity Al2O3 powder; The purity of the raw material powder is ≥99.9%, and the particle size D50 is 1.2 μm; The sintering aid is one of a Y2O3-Al2O3 sintering aid or a MgO-Y2O3 sintering aid; When the sintering aid is a Y2O3-Al2O3 sintering aid, the mass ratio of Y2O3 to Al2O3 is 1:1; When the sintering aid is MgO-Y2O3 sintering aid, the mass ratio of MgO to Y2O3 is 1:1; The mass fraction of the sintering aid in the mixed raw material powder is 1%; The method for preparing the treated aluminum alloy powder comprises: performing hydrogenation degreasing pretreatment on the aluminum alloy powder and drying; The preparation method of the final mold is as follows: the mold is designed with the upper surface of the ceramic base 1 as the bottom, and the other surfaces are composed of rubber. The inner cavity is a regular hexahedron with a side length of 12.5 mm, a distance from the opposite side of 22 mm, and a height of 14.3 mm.

[0022] The secondary sintering is to fix the final green body in a mold and perform sintering, first heating to 1650-2050°C, keeping at 1650-2050°C for 3 hours, then cooling to 800°C, and then naturally cooling to room temperature to obtain a bulletproof multi-layer nested shuttlecock structural mechanical unit; During the secondary sintering, the heating rate when the temperature reaches 1650-2050°C is 10-15°C / min; The sintering is carried out in an argon protective atmosphere or an air atmosphere; The cooling rate when cooling to 800°C is 5°C / min; When cooling to room temperature, natural cooling method is adopted; The material of the mold is graphite; When the final green body is fixed in the mold, the gap between the inner wall of the mold and the final green body is controlled to be less than 0.05 mm, and the ceramic base 1 is facing downward.

[0023] Example 1 This embodiment provides a bulletproof multi-layer nested shuttlecock structural mechanical unit, such as Figure 1 and Figure 2 As shown, it includes a ceramic base 1, a first ceramic sheet 2 and a second ceramic sheet 3, which are layered and integrally formed on the ceramic base, a first metal buffer layer 4, a second metal buffer layer 5, and a third metal buffer layer 6. The ceramic base 1 is located at the bottom, and from bottom to top, the first metal buffer layer 4, the first ceramic sheet 2, the second metal buffer layer 5, the second ceramic sheet 3, and the third metal buffer layer 6 are placed on the ceramic base 1 in this order.

[0024] The vertical projection of the ceramic base 1 is a regular hexagon with a side length of 11.5 mm, a distance from the opposite side of 20 mm, and a height of 4 mm; The center of the ceramic base 1 is also provided with a square pillar with a side length of 4 mm and a height of 11 mm; The vertical projections of the first metal buffer layer 4 , the first ceramic sheet 2 , the second metal buffer layer 5 , the second ceramic sheet 3 , and the third metal buffer layer 6 are all regular hexagons, each with a side length of 11.5 mm and a distance between opposite sides of 20 mm.

[0025] This embodiment takes the preparation of a shuttlecock structural mechanical unit made of silicon carbide-aluminum alloy-carbon fiber as an example, and provides a method for preparing the aforementioned bulletproof multi-layer nested shuttlecock structural mechanical unit, specifically: 1. Preparation of the base body: A silicon carbide ceramic base 1 body was prepared using a cold isostatic pressing process. High-purity α-SiC powder (purity ≥99.9%, particle size D50 = 1.2 μm) was selected, and a Y2O3-Al2O3 sintering aid with a mass fraction of 1% was added thereto. The mass ratio of Y2O3 to Al2O3 in the Y2O3-Al2O3 sintering aid was 1:1. The mixture was evenly mixed and dried to obtain a mixed SiC powder for later use. A rubber mold was prepared using flexible rubber. The total shrinkage of the material was measured to be 9% through a mold design shrinkage compensation experiment. Therefore, the inner cavity of the rubber mold was designed to be a regular hexagon with a side length of 12.5 mm, a distance from the opposite side of 22 mm, and a height of 4.4 mm. A square pillar hole with a side length of 4.4 mm and a height of 12 mm was reserved in the center. The mixed SiC powder is filled into a rubber mold, vibrated to compact it, and then vacuum-sealed. The mold is then placed in a cold isostatic press, applying a pressure of 200 MPa for 30 minutes. After the cold isostatic pressing process, the rubber mold is removed and the surface is polished to ensure dimensional accuracy (tolerance ±0.1 mm). This results in a base blank. The base blank has a density of 3.05 g / cm³ and a flexural strength of 50 MPa.

[0026] 2. Primary sintering: Place the base body obtained in step 1 in an argon-protected sintering furnace, heat it to 1950°C at a heating rate of 15°C / min, with the oxygen content in the argon protective atmosphere ≤10ppm, keep it at 1950°C for 3 hours, cool it to 800°C at a cooling rate of 5°C / min, and then cool it naturally to room temperature to obtain a ceramic base 1. The density of the ceramic base 1 is 3.10g / cm 3 , Vickers hardness is 2800HV and flexural strength is 500MPa.

[0027] 3. Impregnation: The carbon fibers are impregnated with high-temperature resistant polyimide resin (model 705-292A, brownish-red viscous liquid, solid content 62%±2%, dynamic viscosity 420mPa•s at 25°C) to impregnate 24K carbon fiber bundles (24,000 filaments per bundle, 7μm diameter, 5mm length, 5.2GPa tensile strength, 240GPa modulus). During the impregnation, the 24K carbon fiber bundles are first pretreated, specifically in the After removing the sizing agent on the surface of the carbon fiber by oxidation in an oven at 150°C, the resin is impregnated by a solution impregnation method. Specifically, the fiber bundle is pulled through a constant temperature resin tank (40°C) at a uniform speed, extruded and infiltrated, and pre-cured at 100°C to evaporate the solvent. The impregnated fiber bundle enters the high-temperature curing stage, specifically, under the protection of a nitrogen atmosphere at 225°C and 3.5MPa for 120 minutes to complete cross-linking and obtain a carbon fiber prepreg. The volume fraction of 24K carbon fiber bundles in the carbon fiber prepreg is 65%.

[0028] 4. Molding: A blank for the shuttlecock structural mechanical unit, made of silicon carbide-aluminum alloy-carbon fiber, was prepared using a cold isostatic pressing process. High-purity α-SiC powder (purity ≥99.9%, particle size D50 = 1.2 μm) was selected, to which a 1% by mass Y2O3-Al2O3 sintering aid was added, with a Y2O3:Al2O3 mass ratio of 1:1. The mixture was uniformly mixed and dried to obtain a mixed SiC powder for later use. 6061 aluminum alloy powder (particle size 39 μm, sphericity 90%) was selected and pretreated by hydrogenation degreasing (degreasing rate 99%) to an oxygen content of 0.1%. The powder was then dried to obtain the treated aluminum alloy powder for later use. A mold is prepared by using flexible rubber and the ceramic base 1 obtained in step 2. The total shrinkage of the material is measured to be 9% through the mold design shrinkage compensation experiment. Therefore, the mold is designed with the upper surface of the ceramic base 1 as the bottom, and the other surfaces are composed of rubber. The inner cavity is a regular hexagonal prism with a side length of 12.5mm, a distance from the sides of 22mm, and a height of 14.3mm. First, a 2mm thick layer of treated aluminum alloy powder is evenly laid on the ceramic base 1, and a 0.2mm thick carbon fiber prepreg is evenly laid on the upper layer of the treated aluminum alloy powder as the raw material for the first metal buffer layer 4. After the raw material of the first metal buffer layer 4 is vibrated and compacted, a 3.3mm thick mixed SiC powder is evenly laid on it as the raw material for the first ceramic sheet 2. After the raw material of the first ceramic sheet 2 is vibrated and compacted, a 2mm thick layer of treated aluminum alloy powder is evenly laid on it, and a 0.2mm thick carbon fiber prepreg is evenly laid on the upper layer of the treated aluminum alloy powder as the second metal buffer layer 5. After the raw materials of the second metal buffer layer 5 are vibrated and compacted, a 3.3 mm thick mixed SiC powder is evenly laid on top of it as the raw material for the second ceramic sheet 3. After the raw materials of the silicon carbide ceramic layer 3 are vibrated and compacted, a 3 mm thick treated aluminum alloy powder is evenly laid on top of it, and a 0.3 mm thick carbon fiber prepreg is evenly laid on the upper layer of the aluminum alloy powder as the raw material for the third metal buffer layer 6. After the mold is vibrated and compacted as a whole, it is vacuum-sealed and placed in a cold isostatic press. A pressure of 200 MPa is applied and the holding time is 30 minutes. After the cold isostatic pressing is completed, the rubber mold is removed to obtain the final blank, and the surface of the final blank is polished to ensure dimensional accuracy (tolerance ±0.1 mm). The density of the final blank is 2.75 g / cm 3 , the flexural strength is 60MPa.

[0029] 5. Secondary Sintering: The final green body obtained in Step 4 was fixed in a graphite mold, with the gap between the mold inner wall and the final green body controlled to be less than 0.05 mm. With the ceramic base 1 facing downward, the mold was placed in an argon-protected sintering furnace. In an argon-protected atmosphere (oxygen content ≤ 10 ppm), the temperature was raised to 1950°C at a rate of 15°C / min. The temperature was then held at 1950°C for 3 hours. The temperature was then lowered to 800°C at a rate of 5°C / min, followed by natural cooling to room temperature. This resulted in a bulletproof multi-layer nested shuttlecock structural mechanical unit. The density of the bulletproof multi-layer nested shuttlecock structural mechanical unit was 2.8 g / cm³.

[0030] The ballistic performance of the multi-layer nested shuttlecock structural mechanical unit obtained in this example was tested. Specifically, at a ballistic test range equipped with a high-speed camera and velocimeter, according to NIJ Standard-0101.06 / NATOSTANAG 4569, the structural mechanical unit specimen was fixed to an aluminum backing plate and fired three times consecutively with a 7.62×51mm NATO bullet (bullet mass 9.7g, muzzle velocity 830m / s). None of the bullets penetrated the aluminum backing plate, with a ballistic limit velocity (V50) of 1300m / s and a backing plate depression depth of 15mm. The first, second, and third metal buffer layers 4, 5, and 6 absorbed energy through plastic deformation, and surface cracks in the silicon carbide ceramic sheet were constrained by the dense metal matrix, preventing fragmentation.

[0031] The bulletproof multi-layer nested shuttlecock structural mechanical unit obtained in this example was tested for its high-temperature resistance. The high-temperature flexural strength retention of the structural mechanical unit was tested using a high-temperature universal material testing machine. Specifically, the sample was placed in a high-temperature universal material testing machine and held at 600°C, 800°C, and 1000°C (under argon atmosphere) for 2 hours. A three-point bending test was then performed on the structural unit at a loading rate of 1 mm / min. The maximum load and fracture displacement were recorded, and the flexural strength retention was calculated (high-temperature strength / room temperature strength × 100%). The experimental results showed a flexural strength retention rate of 90% at 600°C, 80% at 800°C, and 60% at 1000°C, indicating good flexural performance at high temperatures. The high-temperature oxidation stability of the structural mechanical unit was also tested using a high-temperature oxidation test chamber. The initial mass of the sample structure unit was measured (accuracy: 0.1 mg). The sample structure unit was then placed in a high-temperature oxidation test chamber (air atmosphere) and held at 800°C and 1000°C for 50 hours. The unit was then cooled to room temperature in air. The mass change was measured and the surface oxide layer morphology was observed (SEM / EDS analysis). The experimental results showed a mass loss rate of 1.5% at 800°C and 4.0% at 1000°C. Silicon carbide oxidized to form a SiO2 protective layer. The aluminum alloy oxidation at the interface was controllable, with no delamination failure, indicating excellent high-temperature oxidation stability.

[0032] The wear resistance of the multi-layer nested shuttlecock structural mechanical unit obtained in this example was tested. A ball-on-disc friction and wear tester (equipped with a high-temperature module) was used to test the surface durability of the structural unit under friction and wear conditions. The loads were 50N, 100N, and 150N, the sliding speeds were 0.2m / s and 0.5m / s, the sliding distance was 1000m, and the grinding material was a SiC ball (diameter 6mm). The test was carried out at room temperature and high temperature (400℃), and the friction coefficient was recorded in real time. The wear volume was measured using a 3D profilometer. The experimental results showed that the wear rate at room temperature was 1.2×10 -6 mm 3 / N•m, friction coefficient 0.25; at high temperature (400℃), the wear rate increases by 20%, the friction coefficient fluctuates by 12%, and the wear resistance is good.

[0033] The surface hardness of the multi-layer nested shuttlecock structure mechanical unit obtained in this example was tested using a Vickers hardness tester (equipped with a high-temperature module). The tests were conducted under loads of 1 kg and 5 kg, at room temperature and 400°C. Different loads were applied to the sample surface at different temperatures, with a holding time of 15 seconds. The Vickers hardness (HV) was calculated. The room temperature hardness was 2800 HV (dominated by the silicon carbide phase), and the hardness retention at 400°C was 90%.

[0034] The above tests indicate that the bulletproof multi-layer nested shuttlecock structural mechanical unit obtained in this embodiment has excellent high temperature resistance, wear resistance and impact resistance, and has the advantage of being lightweight, and can meet the engineering application requirements in extreme environments.

[0035] Example 2 This embodiment provides a bulletproof multi-layer nested shuttlecock structural mechanical unit, such as Figure 1 and Figure 2 As shown, it includes a ceramic base 1, a first ceramic sheet 2 and a second ceramic sheet 3, which are layered and integrally formed on the ceramic base, a first metal buffer layer 4, a second metal buffer layer 5, and a third metal buffer layer 6. The ceramic base 1 is located at the bottom, and from bottom to top, the first metal buffer layer 4, the first ceramic sheet 2, the second metal buffer layer 5, the second ceramic sheet 3, and the third metal buffer layer 6 are placed on the ceramic base 1 in this order.

[0036] The vertical projection of the ceramic base 1 is a regular hexagon with a side length of 11.5 mm, a distance from the opposite side of 20 mm, and a height of 4 mm; The center of the ceramic base 1 is also provided with a square pillar with a side length of 4 mm and a height of 11 mm; The vertical projections of the first metal buffer layer 4 , the first ceramic sheet 2 , the second metal buffer layer 5 , the second ceramic sheet 3 , and the third metal buffer layer 6 are all regular hexagons, each with a side length of 11.5 mm and a distance between opposite sides of 20 mm.

[0037] This embodiment takes the preparation of a shuttlecock structural mechanical unit made of boron carbide-aluminum alloy-carbon fiber as an example, and provides a method for preparing the aforementioned bulletproof multi-layer nested shuttlecock structural mechanical unit, specifically: 1. Preparation of the Base Body: The boron carbide ceramic base 1 body was prepared using a cold isostatic pressing process. High-purity α-boron carbide (B4C) powder (purity ≥99.9%, particle size D50 = 1.2μm) was selected. A 1% by mass fraction of a Y2O3-Al2O3 sintering aid (Y2O3:Al2O3 in a 1:1 mass ratio) was added to the powder. The mixture was then dried to obtain a mixed B4C powder for later use. A flexible rubber mold was prepared. Shrinkage compensation experiments conducted on the rubber mold design revealed a total shrinkage of 9%. The mold cavity was designed to have a regular hexagonal shape with a side length of 12.5mm, a width across the sides of 22mm, and a height of 4.4mm. A central square support hole with a side length of 4.4mm and a height of 12mm was reserved. The mixed B4C powder was filled into the mold, compacted by vibration, and then sealed with a vacuum seal. The mold was placed in a cold isostatic press, applying a pressure of 200 MPa for 30 minutes. After the cold isostatic pressing process, the rubber mold was removed and the surface polished to ensure dimensional accuracy (tolerance ±0.1 mm). This resulted in a base blank. The base blank had a density of 2.45 g / cm³ and a flexural strength of 45 MPa.

[0038] 2. Primary sintering: Place the base body obtained in step 1 in an argon-protected sintering furnace, heat it to 2050°C at a heating rate of 15°C / min, with the oxygen content in the argon protective atmosphere ≤10ppm, keep it at 2050°C for 3 hours, cool it to 800°C at a cooling rate of 5°C / min, and then cool it naturally to room temperature to obtain a ceramic base 1. The density of the ceramic base 1 is 2.52g / cm 3 , Vickers hardness is 3500HV and flexural strength is 480MPa.

[0039] 3. Impregnation: The carbon fibers were impregnated with high-temperature resistant polyimide resin (model 705-292A, brown-red viscous liquid, solid content 62%±2%, dynamic viscosity 420mPa•s at 25°C) to impregnate 24K carbon fiber bundles (24,000 filaments per bundle, 7μm filament diameter, 5mm carbon fiber length, 5.2GPa tensile strength, 240GPa modulus). During the impregnation, the 24K carbon fiber bundles were first pretreated, specifically: After removing the sizing agent on the surface of the carbon fiber by oxidation in an oven at 150°C, the resin is impregnated by a solution impregnation method. Specifically, the fiber bundle is pulled at a uniform speed through a constant temperature resin tank (40°C), extruded and infiltrated, and pre-cured at 100°C to evaporate the solvent. The impregnated fiber bundle enters the high-temperature curing stage, specifically, under the protection of a nitrogen atmosphere at 225°C and 3.5MPa for 120 minutes to complete cross-linking and obtain a carbon fiber prepreg. The volume fraction of 24K carbon fiber bundles in the carbon fiber prepreg is 65%.

[0040] 4. Molding: Cold isostatic pressing was used to prepare a blank for the shuttlecock structural mechanical unit made of boron carbide-aluminum alloy-carbon fiber. High-purity α-boron carbide (B4C) powder (purity ≥99.9%, particle size D50 = 1.2 μm) was selected, and a Y2O3-Al2O3 sintering aid with a mass fraction of 1% was added thereto. The mass ratio of Y2O3 to Al2O3 in the Y2O3-Al2O3 sintering aid was 1:1. The mixture was mixed and dried to obtain a mixed B4C powder for later use. 6061 aluminum alloy powder (particle size 39 μm, sphericity 90%) was selected and pretreated by hydrogenation degreasing (degreasing rate 99%) to an oxygen content of 0.1%. The powder was then dried to obtain the treated aluminum alloy powder for later use. A mold is prepared by using flexible rubber and the ceramic base 1 obtained in step 2. The total shrinkage of the material is measured to be 9% through the mold design shrinkage compensation experiment. Therefore, the mold is designed with the upper surface of the ceramic base 1 as the bottom, and the other surfaces are composed of rubber. The inner cavity is a regular hexagonal prism with a side length of 12.5mm, a distance from the sides of 22mm, and a height of 14.3mm. First, a 2mm thick layer of treated aluminum alloy powder is evenly laid on the ceramic base 1, and a 0.2mm thick carbon fiber prepreg is evenly laid on the upper layer of the treated aluminum alloy powder as the raw material for the first metal buffer layer 4. After the raw material of the first metal buffer layer 4 is vibrated and compacted, a 3.3mm thick mixed B4C powder is evenly laid on it as the raw material for the first ceramic sheet 2. After the raw material of the first ceramic sheet 2 is vibrated and compacted, a 2mm thick layer of treated aluminum alloy powder is evenly laid on it, and a 0.2mm thick carbon fiber prepreg is evenly laid on the upper layer of the treated aluminum alloy powder as the second metal buffer layer 5. After the raw materials for the second metal buffer layer 5 were vibrated and compacted, a 3.3 mm thick layer of mixed B4C powder was evenly laid on top, serving as the raw materials for the second ceramic sheet 3. After the raw materials for the silicon carbide ceramic layer 3 were vibrated and compacted, a 3 mm thick layer of treated aluminum alloy powder was evenly laid on top, and a 0.3 mm thick layer of carbon fiber prepreg was evenly laid on top of the aluminum alloy powder, serving as the raw materials for the third metal buffer layer 6. The entire mold was vibrated and compacted, then vacuum-sealed and placed in a cold isostatic press. A pressure of 200 MPa was applied and the pressure was held for 30 minutes. After the cold isostatic pressing was completed, the rubber mold was removed to obtain the final blank, which was then surface-polished to ensure dimensional accuracy (tolerance ±0.1 mm). The final blank had a density of 2.6 g / cm³ and a flexural strength of 55 MPa.

[0041] 5. Secondary Sintering: The final green body obtained in step 4 was fixed in a graphite mold, with the gap between the inner wall of the mold and the final green body controlled to be less than 0.05 mm. With the ceramic base 1 facing downward, the mold was placed in an argon-protected sintering furnace. In an argon-protected atmosphere (oxygen content ≤ 10 ppm), the temperature was raised to 2050°C at a rate of 15°C / min. The temperature was maintained at 2050°C for 3 hours. The temperature was then lowered to 800°C at a rate of 5°C / min, and then naturally cooled to room temperature to obtain a bulletproof multi-layer nested shuttlecock structural mechanical unit. The density of the bulletproof multi-layer nested shuttlecock structural mechanical unit was 2.65 g / cm³.

[0042] The ballistic performance of the multi-layer nested shuttlecock structural mechanical unit obtained in this example was tested. Specifically, at a ballistic test range equipped with a high-speed camera and velocimeter, the structural unit specimen was fixed to an aluminum backing plate according to NIJ Standard-0101.06 / NATO STANAG4569. The structural unit was fired three times consecutively with a 7.62×51mm NATO bullet (bullet mass 9.7g, muzzle velocity 830m / s). None of the bullets penetrated the ballistics, reaching a ballistic limit velocity (V50) of 1200m / s and a backing plate indentation depth of 18mm. The aluminum alloy layer absorbed energy through plastic deformation, and surface cracks in the boron carbide ceramic sheet were constrained by the dense metal matrix, preventing fragmentation.

[0043] The high-temperature performance of the multi-layer nested shuttlecock structural mechanical unit obtained in this example was tested. The high-temperature flexural strength retention of the structural mechanical unit was tested using a high-temperature universal material testing machine. Specifically, the sample was placed in a high-temperature universal material testing machine and held at 600°C, 800°C, and 1000°C (under argon protection) for 2 hours. A three-point bending test was performed on the structural unit at a loading rate of 1 mm / min. The maximum load and fracture displacement were recorded, and the flexural strength retention was calculated (high-temperature strength / room temperature strength × 100%). The experimental results showed a flexural strength retention of 85% at 600°C, 70% at 800°C, and 50% at 1000°C. The high-temperature oxidation stability of the structural unit was tested using a high-temperature oxidation test chamber. The initial mass of the sample structure unit was measured (accuracy: 0.1 mg). The sample structure unit was then placed in a high-temperature oxidation test chamber (air atmosphere) and held at 800°C and 1000°C for 50 hours. The unit was then cooled to room temperature in air. The mass change was measured, and the surface oxide layer morphology was observed (SEM / EDS analysis). The experimental results showed a mass loss rate of 4.0% at 800°C and 7.0% at 1000°C. Silicon carbide oxidized to form a SiO2 protective layer. The aluminum alloy oxidation at the interface was controllable, with no delamination failure, indicating excellent high-temperature oxidation stability.

[0044] The wear resistance of the multi-layer nested shuttlecock structural mechanical unit obtained in this example was tested. A ball-on-disc friction and wear tester (equipped with a high-temperature module) was used to test the surface durability of the structural unit under friction and wear conditions. The loads were 50N, 100N, and 150N, the sliding speeds were 0.2m / s and 0.5m / s, the sliding distance was 1000m, and the grinding material was a SiC ball (diameter 6mm). The test was carried out at room temperature and high temperature (400℃), and the friction coefficient was recorded in real time. The wear volume was measured using a 3D profilometer. The experimental results showed that the wear rate at room temperature was 1.0×10 -6 mm 3 / N·m, friction coefficient 0.2; at high temperature (400°C), the wear rate increased by 25% and the friction coefficient fluctuated by 15%.

[0045] The surface hardness of the multi-layer nested shuttlecock structure mechanical unit obtained in this example was tested using a Vickers hardness tester (equipped with a high-temperature module). The tests were conducted under loads of 1 kg and 5 kg, at room temperature and 400°C. Different loads were applied to the sample surface at different temperatures, with a holding time of 15 seconds. The Vickers hardness (HV) was calculated. The room temperature hardness was 3500 HV (dominated by the boron carbide phase), and the hardness retention at 400°C was 85%.

[0046] The above tests indicate that the bulletproof multi-layer nested shuttlecock structural mechanical unit obtained in this embodiment has excellent high temperature resistance, wear resistance and impact resistance, and has the advantage of being lightweight, and can meet the engineering application requirements in extreme environments.

[0047] Example 3 This embodiment provides a bulletproof multi-layer nested shuttlecock structural mechanical unit, such as Figure 1 and Figure 2 As shown, it includes a ceramic base 1, a first ceramic sheet 2 and a second ceramic sheet 3, which are layered and integrally formed on the ceramic base, a first metal buffer layer 4, a second metal buffer layer 5, and a third metal buffer layer 6. The ceramic base 1 is located at the bottom, and from bottom to top, the first metal buffer layer 4, the first ceramic sheet 2, the second metal buffer layer 5, the second ceramic sheet 3, and the third metal buffer layer 6 are placed on the ceramic base 1 in this order.

[0048] The vertical projection of the ceramic base 1 is a regular hexagon with a side length of 11.5 mm, a distance from the opposite side of 20 mm, and a height of 4 mm; The center of the ceramic base 1 is also provided with a square pillar with a side length of 4 mm and a height of 11 mm; The vertical projections of the first metal buffer layer 4 , the first ceramic sheet 2 , the second metal buffer layer 5 , the second ceramic sheet 3 , and the third metal buffer layer 6 are all regular hexagons, each with a side length of 11.5 mm and a distance between opposite sides of 20 mm.

[0049] This embodiment takes the preparation of a shuttlecock structural mechanical unit made of alumina-aluminum alloy-carbon fiber as an example, and provides a method for preparing the aforementioned bulletproof multi-layer nested shuttlecock structural mechanical unit, specifically: 1. Preparation of the Base Body: The alumina ceramic base 1 body was prepared using a cold isostatic pressing process. High-purity α-alumina (Al2O3) powder (purity ≥99.7%, particle size D50 = 1.5 μm) was selected, and a 1% mass fraction of MgO-Y2O3 sintering aid (MgO:Y2O3) was added to the powder. The mixture was uniformly mixed and dried to obtain a mixed Al2O3 powder for later use. A mold was prepared using flexible rubber. A mold design shrinkage compensation experiment revealed a total shrinkage of 9%. Therefore, the rubber mold cavity was designed to have a regular hexagonal shape with a side length of 12.5 mm, a 22 mm width across the sides, and a height of 4.4 mm. A central square support hole with a side length of 4.4 mm and a height of 12 mm was reserved. The mixed Al2O3 powder was filled into the rubber mold, vibrated to compact the powder, and then vacuum-sealed. The mold was placed in a cold isostatic press, applying a pressure of 200 MPa for 30 minutes. After the cold isostatic pressing process, the rubber mold is removed and the surface is polished to ensure dimensional accuracy (tolerance ±0.1mm), resulting in a base blank. The base blank has a density of 3.75g / cm³ and a flexural strength of 40MPa.

[0050] 2. Primary Sintering: The base body obtained in step 1 was placed in an air atmosphere sintering furnace and heated to 1650°C at a heating rate of 10°C / min. The temperature was maintained at 1650°C for 3 hours. The temperature was then cooled to 800°C at a cooling rate of 5°C / min. The base body was then naturally cooled to room temperature to obtain a ceramic base 1. The ceramic base 1 had a density of 3.85 g / cm³, a Vickers hardness of 2000 HV, and a flexural strength of 380 MPa.

[0051] 3. Impregnation: The carbon fibers were impregnated with high-temperature resistant polyimide resin (model 705-292A, brown-red viscous liquid, solid content 62%±2%, dynamic viscosity 420mPa•s at 25°C) to impregnate 24K carbon fiber bundles (24,000 filaments per bundle, 7μm filament diameter, 5mm carbon fiber length, 5.2GPa tensile strength, 240GPa modulus). During the impregnation, the 24K carbon fiber bundles were first pretreated, specifically: After removing the sizing agent on the surface of the carbon fiber by oxidation in an oven at 150°C, the resin is impregnated by a solution impregnation method. Specifically, the fiber bundle is pulled at a uniform speed through a constant temperature resin tank (40°C), extruded and infiltrated, and pre-cured at 100°C to evaporate the solvent. The impregnated fiber bundle enters the high-temperature curing stage, specifically, under the protection of a nitrogen atmosphere at 225°C and 3.5MPa for 120 minutes to complete cross-linking and obtain a carbon fiber prepreg. The volume fraction of 24K carbon fiber bundles in the carbon fiber prepreg is 65%.

[0052] 4. Molding: A blank for the shuttlecock structural mechanical unit, made of alumina-aluminum alloy-carbon fiber, was prepared using cold isostatic pressing. High-purity α-alumina (Al2O3) powder (purity ≥ 99.7%, particle size D50 = 1.5 μm) was used. A 1% by mass MgO-Y2O3 sintering aid (MgO:Y2O3 in a 1:1 mass ratio) was added to the blank. The mixture was then dried to obtain a mixed Al2O3 powder for later use. 6061 aluminum alloy powder (particle size 39 μm, sphericity 90%) was pretreated by hydrogenation degreasing (degreasing rate 99%) to an oxygen content of 0.1%, and then dried to obtain the treated aluminum alloy powder for later use. A mold was prepared using flexible rubber and the ceramic base 1 obtained in step 2. A mold design shrinkage compensation experiment revealed a total shrinkage of 9%. Therefore, the mold is designed with the upper surface of the ceramic base 1 as the bottom, and the other surfaces are made of rubber. The inner cavity is a regular hexagonal prism with a side length of 12.5mm, a distance from the sides of 22mm, and a height of 14.3mm. First, a 2mm thick layer of processed aluminum alloy powder is evenly laid on the ceramic base 1, and a 0.2mm thick carbon fiber prepreg is evenly laid on the upper layer of the processed aluminum alloy powder as the raw material for the first metal buffer layer 4. After the raw material of the first metal buffer layer 4 is vibrated and compacted, a 3.3mm thick mixed Al2O3 powder is evenly laid on it as the raw material for the first ceramic sheet 2. After the raw material of the first ceramic sheet 2 is vibrated and compacted, a 2mm thick layer of processed aluminum alloy powder is evenly laid on it, and a 0.2mm thick carbon fiber prepreg is evenly laid on the upper layer of the processed aluminum alloy powder as the second metal buffer layer 5. After the raw material of the second metal buffer layer 5 is vibrated and compacted, a 3.3mm thick mixed Al2O3 powder is evenly laid on it as the raw material for the second ceramic sheet 3. After the raw materials of the silicon carbide ceramic layer 3 are vibrated and compacted, a 3mm thick layer of processed aluminum alloy powder is evenly laid on top of it, and a 0.3mm thick carbon fiber prepreg is evenly laid on the upper layer of the aluminum alloy powder as the raw material of the third metal buffer layer 6. After the mold is vibrated and compacted as a whole, it is vacuum-sealed and placed in a cold isostatic press. A pressure of 200MPa is applied and the holding time is 30min. After the cold isostatic pressing is completed, the rubber mold is removed to obtain the final blank, and the surface of the final blank is polished to ensure dimensional accuracy (tolerance ±0.1mm). The density of the final blank is 3.2g / cm 3 , the flexural strength is 40MPa.

[0053] 5. Secondary Sintering: The final green body obtained in step 4 is fixed in a graphite mold, with the gap between the inner wall of the mold and the final green body controlled to be less than 0.05 mm. With the ceramic base 1 facing downward, the mold is placed in an air atmosphere and heated to 1650°C at a rate of 10°C / min. The temperature is then maintained at 1650°C for 3 hours. The temperature is then cooled to 800°C at a rate of 5°C / min, followed by natural cooling to room temperature. This results in a bulletproof multi-layer nested shuttlecock structural mechanical unit. The density of the bulletproof multi-layer nested shuttlecock structural mechanical unit is 3.1 g / cm³.

[0054] The ballistic performance of the multi-layer nested shuttlecock structural mechanical unit obtained in this example was tested. Specifically, at a ballistic test range equipped with a high-speed camera and velocimeter, according to NIJ Standard-0101.06 / NATO STANAG4569, the structural unit specimen was fixed to an aluminum backing plate and fired three times consecutively with a 7.62×51mm NATO bullet (bullet mass 9.7g, muzzle velocity 830m / s). None of the bullets penetrated the ballistics, reaching a ballistic limit velocity (V50) of 1100m / s and a backing plate indentation depth of 25mm. The aluminum alloy layer absorbed energy through plastic deformation, and surface cracks in the alumina ceramic sheet were constrained by the dense metal matrix, preventing fragmentation.

[0055] The high-temperature performance of the multi-layer nested shuttlecock structural mechanical unit obtained in this example was tested. The high-temperature flexural strength retention of the structural unit was tested using a high-temperature universal material testing machine. The sample structural unit was placed in a high-temperature universal material testing machine and held at 600°C, 800°C, and 1000°C (under argon atmosphere) for 2 hours. A three-point bending test was performed on the structural unit at a loading rate of 1 mm / min. The maximum load and fracture displacement were recorded, and the flexural strength retention was calculated (high-temperature strength / room temperature strength × 100%). The experimental results showed a flexural strength retention of 90% at 600°C, 75% at 800°C, and 50% at 1000°C. The high-temperature oxidation stability of the structural unit was tested using a high-temperature oxidation test chamber. The initial mass of the sample structure unit was measured (accuracy: 0.1 mg). The sample structure unit was then placed in a high-temperature oxidation test chamber (air atmosphere) and held at 800°C and 1000°C for 50 hours, respectively. After cooling to room temperature, the mass change was measured and the surface oxide layer morphology was observed (SEM / EDS analysis). The experimental results showed a mass loss rate of 2.0% at 800°C and 6.0% at 1000°C. The Al2O3 protective layer was relatively stable, and oxidation of the aluminum alloy at the interface was controllable, with no delamination failure.

[0056] The wear resistance of the multi-layer nested shuttlecock structural mechanical unit obtained in this example was tested. A ball-on-disc friction and wear tester (equipped with a high-temperature module) was used to test the surface durability of the structural unit under friction and wear conditions. The loads were 50N, 100N, and 150N, the sliding speeds were 0.2m / s and 0.5m / s, the sliding distance was 1000m, and the grinding material was a SiC ball (diameter 6mm). The test was carried out at room temperature and high temperature (400℃), and the friction coefficient was recorded in real time. The wear volume was measured using a 3D profilometer. The experimental results showed that the wear rate at room temperature was 1.8×10 -6 mm 3 / N·m, friction coefficient 0.35; at high temperature (400°C), the wear rate increased by 30% and the friction coefficient fluctuated by 18%.

[0057] The surface hardness of the multi-layer nested shuttlecock structure mechanical unit obtained in this example was tested using a Vickers hardness tester (equipped with a high-temperature module). The tests were conducted at loads of 1 kg and 5 kg, and at temperatures of 400°C and 15 seconds, respectively. Different loads were applied to the sample surface at different temperatures, and the load was maintained for 15 seconds. The Vickers hardness (HV) was calculated. The room temperature hardness was 2000 HV (dominated by the alumina phase), and the hardness retention at 400°C was 85%.

[0058] The above tests show that the performance indicators of the bulletproof multi-layer nested shuttlecock ball structure mechanical unit obtained in this embodiment, such as hardness, high temperature resistance, impact resistance, wear resistance, and lightweight, are inferior to those of the bulletproof multi-layer nested shuttlecock ball structure mechanical unit obtained in Example 1. However, the bulletproof multi-layer nested shuttlecock ball structure mechanical unit obtained in this embodiment has a cost advantage and is suitable for scenarios with high economic requirements, such as police protective equipment and civilian bulletproof vehicles.

[0059] The above embodiments are typical implementations of the present invention, but the technical solutions of the present invention are not limited to the above details. Any modification, replacement or improvement made within the design ideas and principles of the present invention should be included in the scope of protection of the present invention.

[0060] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A bulletproof multi-layer nested shuttlecock structural mechanical unit, characterized in that: It comprises a ceramic base (1), a first ceramic sheet (2) and a second ceramic sheet (3) formed in layers and integrally on the ceramic base, a first metal buffer layer (4), a second metal buffer layer (5), and a third metal buffer layer (6); The ceramic base 1 is located at the bottom, and from bottom to top, a first metal buffer layer (4), a first ceramic sheet (2), a second metal buffer layer (5), a second ceramic sheet (3), and a third metal buffer layer (6) are placed on the ceramic base (1) in sequence.

2. The bulletproof multi-layer nested shuttlecock structural mechanical unit according to claim 1, characterized in that: The vertical projection of the ceramic base (1) is a regular hexagon with a side length of 11.2-11.8 mm, a distance from the opposite side of 19.7-20.3 mm, and a height of 3.8-4.2 mm; A square pillar with a side length of 3.8-4.2 mm and a height of 10.7-11.3 mm is provided in the center of the ceramic base (1).

3. The bulletproof multi-layer nested shuttlecock structural mechanical unit according to claim 1, characterized in that: The vertical projections of the first metal buffer layer (4), the first ceramic sheet (2), the second metal buffer layer (5), the second ceramic sheet (3), and the third metal buffer layer (6) are all regular hexagons, with side lengths of 11.2-11.8 mm and opposite side distances of 19.7-20.3 mm; The first metal buffer layer (4), the first ceramic sheet (2), the second metal buffer layer (5), the second ceramic sheet (3), and the third metal buffer layer (6) all have a square with a side length of 3.8-4.2 mm in the center.

4. A method for preparing a bulletproof multi-layer nested shuttlecock structural mechanical unit according to any one of claims 1 to 3, characterized in that: Including preparation of base body, primary sintering, impregnation, molding, and secondary sintering; The base blank is prepared by mixing raw material powder with a sintering aid and drying to obtain a mixed raw material powder; the mixed raw material powder is filled into a rubber mold, vibrated and compacted, and then vacuum-sealed, and cold isostatically pressed and polished to obtain the base blank; The primary sintering is to sinter the base body by first heating it to 1650-2050°C, keeping it at 1650-2050°C for 3-4 hours, then cooling it to 750-850°C, and then naturally cooling it to room temperature to obtain a ceramic base (1); The impregnation comprises impregnating the carbon fiber bundle with a high-temperature resistant polyimide resin. During the impregnation, the carbon fiber bundle is first pretreated and then impregnated with the resin using a solution impregnation method to obtain the impregnated carbon fiber bundle; The impregnated carbon fiber bundles are subjected to high temperature curing to obtain carbon fiber prepreg; The molding method comprises the following steps: preparing a final mold by combining the flexible rubber and the ceramic base (1), taking the ceramic base (1) as the bottom, first evenly laying a 1.9-2.1 mm thick treated aluminum alloy powder on the ceramic base (1), and evenly laying a 0.2-0.22 mm thick carbon fiber prepreg on the treated aluminum alloy powder as the raw material of the first metal buffer layer (4); after vibrating and compacting the raw material of the first metal buffer layer (4), evenly laying a 3.2-3.4 mm thick mixed raw material powder on the top as the raw material of the first ceramic sheet (2); after vibrating and compacting the raw material of the first ceramic sheet (2), evenly laying a 1.9-2.1 mm thick treated aluminum alloy powder on the top, and evenly laying a 0.2-0.22 mm thick carbon fiber prepreg on the top as the raw material of the first metal buffer layer (4). A 0.2-0.22 mm thick carbon fiber prepreg is evenly laid on the upper layer of the aluminum alloy powder as the second metal buffer layer (5); after the raw material of the second metal buffer layer (5) is vibrated and compacted, a 3.2-3.4 mm thick mixed raw material powder is evenly laid on it as the raw material of the second ceramic sheet (3); after the raw material of the silicon carbide ceramic layer (3) is vibrated and compacted, a 2.8-3.2 mm thick processed aluminum alloy powder is evenly laid on it, and a 0.3-0.33 mm thick carbon fiber prepreg is evenly laid on the upper layer of the aluminum alloy powder as the raw material of the third metal buffer layer (6); the mold is vibrated and compacted as a whole, and then vacuum-sealed, and cold isostatic pressing and polishing are performed to obtain the final blank.

5. The method for preparing the bulletproof multi-layer nested shuttlecock structural mechanics unit according to claim 4, wherein: In the preparation of the base blank, the raw material powder is one of high-purity α-SiC powder, high-purity B4C powder, and high-purity Al2O3 powder; The purity of the raw material powder is ≥99.9%, and the particle size D50 is 1.2 μm; The sintering aid is one of a Y2O3-Al2O3 sintering aid or a MgO-Y2O3 sintering aid; When the sintering aid is a Y2O3-Al2O3 sintering aid, the mass ratio of Y2O3 to Al2O3 is 1:0.8-1.2; When the sintering aid is MgO-Y2O3 sintering aid, the mass ratio of MgO to Y2O3 is 1:0.8-1.2; The mass fraction of the sintering aid in the mixed raw material powder is 0.8-1.2%; The inner cavity of the rubber mold is a regular hexagon with a side length of 12.2-12.8 mm, a distance from the opposite sides of 21.5-22.5 mm, a height of 4.2-4.6 mm, and a square pillar hole with a side length of 4.3-4.7 mm and a height of 11.7-12.3 mm reserved in the center; The cold isostatic pressing pressure is 180-220 MPa, and the holding time is 25-35 min; During the primary sintering, the heating rate when the temperature reaches 1650-2050°C is 10-15°C / min; The sintering is carried out in an argon protective atmosphere or an air atmosphere; The cooling rate when cooling to 750-850℃ is 4-6℃ / min; When cooling to room temperature, natural cooling is used.

6. The method for preparing the bulletproof multi-layer nested shuttlecock structural mechanics unit according to claim 4, wherein: In the impregnation, the high-temperature resistant polyimide resin is model 705-292A, has a brown-red viscous liquid appearance, a solid content of 62%±2%, and a dynamic viscosity of 420 mPa·s at 25°C; The carbon fiber bundle is a 24K carbon fiber bundle; Each of the carbon fiber bundles contains 24,000 single filaments, the single filament diameter is 7 μm, and the carbon fiber length is 5 mm; The carbon fiber bundle has a tensile strength of 5.2 GPa and a modulus of 240 GPa; The pretreatment is to remove the sizing agent on the surface of the carbon fiber by oxidation in an oven at 150-170°C; The resin impregnation is performed by pulling the carbon fiber bundle at a constant speed through a thermostatic resin tank at a temperature of 40°C, and then extruding and penetrating the resin and pre-curing at 95-105°C to evaporate the solvent; The high temperature curing is carried out under nitrogen atmosphere protection, and the impregnated carbon fiber bundle is kept warm and pressurized at 220-230° C. and 3.4-3.6 MPa for 110-130 minutes; The volume fraction of the carbon fiber bundles in the carbon fiber prepreg is 60-70%.

7. The method for preparing the bulletproof multi-layer nested shuttlecock structural mechanics unit according to claim 4, wherein: In the molding process, the mixed raw material powder is prepared by mixing the raw material powder with a sintering aid and drying; The raw material powder is one of high-purity α-SiC powder, high-purity B4C powder, and high-purity Al2O3 powder; The purity of the raw material powder is ≥99.9%, and the particle size D50 is 1.2 μm; The sintering aid is one of a Y2O3-Al2O3 sintering aid or a MgO-Y2O3 sintering aid; When the sintering aid is a Y2O3-Al2O3 sintering aid, the mass ratio of Y2O3 to Al2O3 is 1:0.8-1.2; When the sintering aid is MgO-Y2O3 sintering aid, the mass ratio of MgO to Y2O3 is 1:0.8-1.2; The mass fraction of the sintering aid in the mixed raw material powder is 0.8-1.2%; The method for preparing the treated aluminum alloy powder comprises the following steps: pre-treating the aluminum alloy powder by hydrogenation and degreasing, and then drying the powder.

8. The method for preparing the bulletproof multi-layer nested shuttlecock structural mechanics unit according to claim 4, wherein: During the molding, the preparation method of the final mold is as follows: the mold is designed with the upper surface of the ceramic base 1 as the bottom, and the other surfaces are composed of rubber. The inner cavity is a regular hexahedron, the side length of the regular hexahedron is 12.3-12.7 mm, the distance between the sides is 21.7-22.3 mm, and the height is 14.2-14.5 mm.

9. The method for preparing the bulletproof multi-layer nested shuttlecock structural mechanics unit according to claim 1, wherein: The secondary sintering is to fix the final green body in a mold and perform sintering, first heating to 1650-2050°C, keeping the temperature at 1650-2050°C for 3-4 hours, then cooling to 750-850°C, and then naturally cooling to room temperature to obtain a bulletproof multi-layer nested shuttlecock structural mechanical unit.

10. The method for preparing the bulletproof multi-layer nested shuttlecock structural mechanical unit according to claim 9, characterized in that: During the secondary sintering, the heating rate when the temperature reaches 1650-2050°C is 10-15°C / min; The sintering is carried out in an argon protective atmosphere or an air atmosphere; The cooling rate when cooling to 750-850℃ is 4-6℃ / min; When cooling to room temperature, natural cooling method is adopted; The material of the mold is graphite; When the final green body is fixed in the mold, the gap between the inner wall of the mold and the final green body is controlled to be less than 0.05 mm, and the ceramic base (1) is facing downward.

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