Carbon fiber reinforced alumina-based composite armor material

Abstract

The invention relates to the technical field of advanced composite material preparation, in particular to a carbon fiber reinforced alumina-based composite armor material which is composed of the following components in parts by mass: 10-25 parts of carbon fiber; 60 to 75 parts of aluminum oxide; 5 to 10 parts of a carbon nanotube; 3 to 8 parts of silicon nitride; 2 to 5 parts of graphene coated boron nitride nanosheets; 1 to 3 parts of self-repairing microcapsules; 1 to 3 parts of a super-hydrophobic nano coating; 2-5 parts of a rare earth oxide reinforcement phase; 1 to 3 parts of nano zirconium oxide; 0.5 to 2 parts of a conductive carbon black / graphene compound; and 2-5 parts of alumina whisker. According to the material, through multi-component collaborative design, high strength, high wear resistance, excellent thermal stability and a self-repairing function are achieved, meanwhile, the impact resistance is improved through the aluminum oxide whiskers, and the material is suitable for the protection requirement in an extreme environment.

Description

Technical Field

[0001] This invention relates to the field of advanced composite material preparation technology, specifically to a carbon fiber reinforced alumina-based composite armor material. Background Technology

[0002] In the fields of military protection, aerospace, and extreme environment engineering, armor materials must possess high impact resistance, excellent wear resistance, and stable thermodynamic properties. Materials must maintain structural integrity under high temperature, high-speed impact, and corrosive environments, while also meeting lightweight design requirements. Furthermore, long-term service demands higher requirements on the material's self-healing capabilities, leak-proof performance, and thermal shock resistance to address performance degradation under complex operating conditions.

[0003] To address the above requirements, existing technologies mainly adopt the following solutions: Ceramic-metal composite armor: By alternating layers of ceramic and metal, impact resistance is achieved by utilizing the high hardness of ceramic and the toughness of metal. However, insufficient interlayer bonding strength can easily lead to delamination failure. Nanofiller-reinforced ceramic matrix materials: Introducing nano-oxides or carbon-based materials can improve hardness and thermal conductivity, but poor filler dispersibility can easily lead to local stress concentration. Gradient functional materials: Stress distribution is optimized by designing compositional or structural gradients, but the preparation process is complex and difficult to achieve large-scale production.

[0004] Although the above solutions have achieved breakthroughs in certain performance aspects, they still have significant shortcomings: Poor performance synergy: A single reinforcement method is difficult to balance the comprehensive requirements of strength, toughness and thermal stability, resulting in a high probability of material failure under extreme working conditions; Insufficient control of interface defects: The difference in interfacial energy between the reinforcing phase and the matrix is ​​not effectively controlled, which easily leads to crack initiation and reduces the fatigue life of the material. Limited multifunctional integration: Existing materials lack additional functions such as self-healing and leak-proofing, making it difficult to meet the long-term service requirements in complex environments; Low process adaptability: The preparation of gradient materials or composite structures depends on precise parameter control, and the process window is narrow, resulting in high production costs and difficulty in ensuring consistency. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a carbon fiber reinforced alumina-based composite armor material, which solves the problems mentioned above.

[0006] According to a first aspect of the present invention, a carbon fiber reinforced alumina-based composite armor material is provided, comprising the following components in parts by mass: Carbon fiber: 10-25 parts; Alumina: 60-75 parts; Carbon nanotubes: 5-10 parts; Silicon nitride: 3-8 parts; Graphene-coated boron nitride nanosheets: 2-5 parts; Self-healing microcapsules: 1-3 parts; Superhydrophobic nanocoating: 1-3 parts; Rare earth oxide reinforcing phase: 2-5 parts; Nano-zirconia: 1-3 parts; Conductive carbon black / graphene composite: 0.5–2 parts; Alumina whiskers: 2-5 parts.

[0007] Carbon fiber (CF) is used to improve the impact resistance and toughness of materials. Its highly oriented arrangement disperses localized stress caused by applied loads, reducing the risk of crack propagation. Its high strength-to-weight ratio effectively reduces material density, optimizing lightweight design, while energy is dissipated through interfacial friction between the fiber and the matrix.

[0008] Aluminum oxide (Al2O3) is used to construct the core mechanical support framework of materials. Its high hardness and wear resistance stem from its stable crystal structure, which can withstand high temperature and acid and alkali corrosion environments, while also serving as a continuous phase to bear the main mechanical loads.

[0009] Silicon nitride (Si3N4) is used to optimize thermal shock resistance. Its low coefficient of thermal expansion and high hardness can reduce thermal stress cracking caused by sudden temperature changes, while its coexistence of amorphous and crystalline structures enhances the fracture toughness of the material.

[0010] Nano-zirconia (ZrO2) is used to improve fracture toughness. By absorbing crack propagation energy through phase transformation, its phase transformation toughening mechanism can significantly inhibit the crack tip propagation rate, while high-temperature stability alleviates performance degradation.

[0011] Aluminum oxide whiskers (Al2O3 whiskers) are used to enhance impact resistance and crack propagation resistance. Through the bridging effect and pull-out mechanism of the whiskers, they disperse external loads, and their high aspect ratio can significantly suppress crack tip propagation speed.

[0012] According to embodiments of the present invention, the physical dispersion effect of carbon fiber and alumina whiskers provides the basic conditions for phase transformation toughening, while the phase transformation mechanism of zirconia compensates for the insufficient protection of the former two in the later stage of crack propagation, ultimately achieving a significant improvement in the material's impact resistance and fracture toughness, while maintaining its lightweight advantage.

[0013] According to an embodiment of the present invention, the carbon fiber is a carbonized fiber obtained by high-temperature carbonization of polyacrylonitrile fiber; the carbon nanotube is a composite powder formed by mixing single-walled carbon nanotubes and multi-walled carbon nanotubes; and the graphene-coated boron nitride nanosheets are composite nanoparticles formed by coating graphene and boron nitride nanosheets by chemical vapor deposition. The mass ratio of the single-walled carbon nanotubes to the multi-walled carbon nanotubes is 1:1-2:1, and the mass ratio of the graphene to the boron nitride nanosheets is 1:1-2:1.

[0014] Carbon nanotubes (CNTs) are used to enhance interfacial bonding strength and electrical conductivity. They bridge matrix cracks through a bridging effect, refine grain size to inhibit crack initiation, and their high aspect ratio can construct a three-dimensional conductive network, improving thermal conductivity and alleviating thermal stress caused by localized temperature rise.

[0015] Graphene-coated boron nitride nanosheets (G-BNNSs) are used to improve interfacial bonding and modulate thermal conduction pathways. The graphene layer provides high conductivity, while the hexagonal lattice structure of boron nitride imparts insulation; the synergistic effect of the two can reduce the risk of electrochemical corrosion caused by local potential differences.

[0016] According to embodiments of the present invention, the conductive network of carbon nanotubes provides stress transmission channels for carbon fibers, while the composite structure of graphene-coated boron nitride nanosheets suppresses local temperature rise through the thermal stability of boron nitride. At the same time, the flexible layered structure of graphene bridges the interface defects between carbon fibers and carbon nanotubes, ultimately achieving a synergistic improvement in conductivity, thermal stability, and corrosion resistance, forming a multi-level functional enhancement system.

[0017] According to an embodiment of the present invention, the self-healing microcapsule is a composite microsphere formed by polyurethane encapsulating epoxy resin, and the superhydrophobic nanocoating is a hydrophobic powder synthesized by nano-silica and perfluoroalkylsiloxane through a sol-gel method. The mass ratio of the polyurethane to the epoxy resin is 1:1 to 1.5:1, and the mass ratio of the nano-silica to the perfluoroalkylsiloxane is 1:1 to 2:1.

[0018] Self-healing microcapsules (SHMs) are used to repair damaged areas of materials. The repair agent encapsulated within the microcapsule ruptures and is released as the crack propagates, filling the crack and restoring structural integrity through a chemical cross-linking reaction, thus extending service life.

[0019] Superhydrophobic nanocoatings (SHNCs) are used to prevent liquid penetration and the adhesion of corrosive media. By combining micro- and nanostructured designs with low surface energy materials, water droplets can roll off and carry away contaminants, improving the material's stability in humid and acidic environments.

[0020] According to embodiments of the present invention, the impermeability of the superhydrophobic nanocoating creates a dry environment for the repair of the self-healing microcapsules, preventing the repair agent from reacting with moisture and becoming ineffective. Meanwhile, the repair capability of the self-healing microcapsules maintains the integrity of the coating surface, preventing loss of hydrophobicity due to crack propagation. This dual mechanism together constructs a long-term stable system for the material in complex environments, inhibiting damage caused by external erosion and extending service life through internal repair.

[0021] According to an embodiment of the present invention, the rare earth oxide reinforcing phase is nanoscale particles formed by mixing yttrium oxide and erbium oxide; the conductive carbon black / graphene composite is a uniform dispersion formed by mixing conductive carbon black and graphene and then ultrasonically dispersing them in a 70% ethanol solution. The mass ratio of yttrium oxide to erbium oxide is 3:1-4:1, and the mass ratio of conductive carbon black to graphene is 1:1-2:1.

[0022] Rare earth oxide reinforcement (REOR) is used to optimize grain growth behavior in alumina matrices. It suppresses grain coarsening through grain boundary pinning, improving the material's creep resistance, while doping elements reduce defect diffusion.

[0023] Conductive carbon black / graphene composite (CB / GC) is used to balance conductivity and mechanical properties. The three-dimensional conductive network is formed by the point-to-point contact of conductive carbon black and the layer overlap of graphene sheets, which not only ensures the conductivity of the material, but also optimizes the interfacial stress distribution through the filling effect and reduces the crack propagation path.

[0024] According to embodiments of the present invention, grain boundary regulation of the rare-earth oxide reinforcing phase provides a stable microstructure basis for the conductive network, preventing the breakage of conductive paths caused by abnormal grain growth. The stress dispersion effect of the conductive carbon black / graphene composite further protects the grain boundary region from crack propagation damage, maintaining the reinforcing effect of the rare-earth oxide reinforcing phase. This coupling mechanism enables the material to simultaneously achieve high conductivity, excellent thermal stability, and resistance to crack propagation under high temperature and mechanical loads.

[0025] According to a second aspect of the present invention, a method for preparing the above-mentioned carbon fiber reinforced alumina-based composite armor material is provided, such as... Figure 1 As shown, it includes the following steps: S1: The conductive carbon black / graphene composite is sprayed onto the surface of the carbon fiber using an electrostatic spraying process to prepare a carbon fiber reinforcement. S2: The mass ratio of the carbon fiber reinforcement, the polyurethane and the epoxy resin is 1:1-1.5:1, and the mass ratio of the nano-silica and the perfluoroalkylsiloxane is 1:1-2:1.

[0026] Self-healing microcapsules (SHMs) are used to repair damaged areas of materials. The repair agent encapsulated within the microcapsule ruptures and is released as the crack propagates, filling the crack and restoring structural integrity through a chemical cross-linking reaction, thus extending service life.

[0027] Superhydrophobic nanocoatings (SHNCs) are used to prevent liquid penetration and the adhesion of corrosive media. By combining micro- and nanostructured designs with low surface energy materials, water droplets can roll off and carry away contaminants, improving the material's stability in humid and acidic environments.

[0028] According to embodiments of the present invention, the impermeability of the superhydrophobic nanocoating creates a dry environment for the repair of the self-healing microcapsules, preventing the repair agent from reacting with moisture and becoming ineffective. Meanwhile, the repair capability of the self-healing microcapsules maintains the integrity of the coating surface, preventing loss of hydrophobicity due to crack propagation. This dual mechanism together constructs a long-term stable system for the material in complex environments, inhibiting damage caused by external erosion and extending service life through internal repair.

[0029] According to an embodiment of the present invention, the rare earth oxide reinforcing phase is nanoscale particles formed by mixing yttrium oxide and erbium oxide; the conductive carbon black / graphene composite is a uniform dispersion formed by mixing conductive carbon black and graphene and then ultrasonically dispersing them in a 70% ethanol solution. The mass ratio of yttrium oxide to erbium oxide is 3:1-4:1, and the mass ratio of conductive carbon black to graphene is 1:1-2:1.

[0030] Rare earth oxide reinforcement (REOR) is used to optimize grain growth behavior in alumina matrices. It suppresses grain coarsening through grain boundary pinning, improving the material's creep resistance, while doping elements reduce defect diffusion.

[0031] Conductive carbon black / graphene composite (CB / GC) is used to balance conductivity and mechanical properties. The three-dimensional conductive network is formed by the point-to-point contact of conductive carbon black and the layer overlap of graphene sheets, which not only ensures the conductivity of the material, but also optimizes the interfacial stress distribution through the filling effect and reduces the crack propagation path.

[0032] According to embodiments of the present invention, grain boundary regulation of the rare-earth oxide reinforcing phase provides a stable microstructure basis for the conductive network, preventing the breakage of conductive paths caused by abnormal grain growth. The stress dispersion effect of the conductive carbon black / graphene composite further protects the grain boundary region from crack propagation damage, maintaining the reinforcing effect of the rare-earth oxide reinforcing phase. This coupling mechanism enables the material to simultaneously achieve high conductivity, excellent thermal stability, and resistance to crack propagation under high temperature and mechanical loads.

[0033] According to a second aspect of the present invention, a method for preparing the above-mentioned carbon fiber reinforced alumina-based composite armor material is provided, such as... Figure 1 As shown, it includes the following steps: S1: The conductive carbon black / graphene composite is sprayed onto the surface of the carbon fiber using an electrostatic spraying process to prepare a carbon fiber reinforcement. S2: The carbon fiber reinforcement, premix and intermediate mixture are mixed at a mass ratio of 1:1:1 and placed in a vibrating screen and mixed for 15-30 minutes under an amplitude of 50-80Hz to obtain the functional reinforcing phase mixture.

[0034] According to an embodiment of the present invention, the particle size range of the functional enhancement phase mixture is 50 nm to 100 μm.

[0035] According to an embodiment of the present invention, the step of preparing an armor material substrate by gradient hot pressing of the composite powder includes: The composite powder is placed in a plasma spraying device and preliminarily sprayed and shaped using argon as the carrier gas. The flow rate of the argon is 30-50 L / min, the spraying current intensity is 80-120 A, and the temperature is 200-300 °C, to obtain a preliminarily dense material. The preliminary dense material is subjected to gradient hot pressing to obtain the armor material substrate.

[0036] The specific process of gradient hot pressing includes: First stage: Temperature 180-200℃, pressure 1.5-2.5MPa, time 8-12 minutes; Second stage: Temperature 200-210℃, pressure 7-9MPa, time 12-18 minutes.

[0037] According to an embodiment of the present invention, the density of the armor material substrate is ≥3.9 g / cm³.

[0038] According to an embodiment of the present invention, the process of surface polishing and heat treatment of the armor material substrate to obtain carbon fiber reinforced alumina-based composite armor material includes: The armor material substrate is cooled to 40-50°C at room temperature and then surface polished with diamond abrasive to obtain a polishing material with a particle size of 5-10μm. The polishing material is placed in a high-temperature vacuum furnace and heat-treated at 1500-1600℃ for 3-5 hours to obtain the carbon fiber reinforced alumina-based composite armor material.

[0039] According to embodiments of the present invention, carbon fiber reinforced alumina-based composite armor material achieves surface densification through diamond polishing and vacuum heat treatment processes, significantly improving strength and impact resistance. It is suitable for military armor, aerospace and extreme environment engineering components, and can meet the comprehensive performance requirements of high strength, impact resistance, corrosion resistance and long service life.

[0040] The present invention has the following beneficial effects: This invention enhances the overall performance of carbon fiber reinforced alumina-based composite armor materials through the synergistic design of composite components. Carbon fiber, as a high-strength skeleton material, combined with the rigid support characteristics of the alumina matrix, significantly disperses applied stress through high-orientation alignment and whisker bridging effect. The phase transformation toughening mechanism of nano-zirconia effectively inhibits crack initiation and propagation by absorbing crack propagation energy. Rare earth oxide reinforcing phases regulate alumina grain growth behavior through grain boundary pinning effect, improving high-temperature stability. The synergistic effect of multiple components forms a multi-layered reinforcement system with improved mechanical properties, thermal shock resistance, and corrosion resistance.

[0041] This invention achieves precise control over the microstructure of materials through the combined optimization of hot-pressing sintering and gradient molding processes. The first-stage mixing hot-pressing sintering promotes dense bonding between the carbon fiber reinforcement and the alumina matrix through high temperature and pressure, enhancing interfacial bonding strength. The second-stage mixing process ensures uniform distribution of the functional reinforcing phase through high-speed dispersion and ball milling, avoiding agglomeration defects. Gradient hot-pressing controls temperature and pressure in stages, optimizing material isotropy and interfacial stability. This achieves a balance between high strength, high toughness, and complex functions while reducing energy consumption, providing an innovative pathway for the efficient preparation of armor materials.

[0042] This invention significantly improves the service life and environmental adaptability of materials through the integrated design of self-healing microcapsules and superhydrophobic nanocoatings. The self-healing microcapsules release a repair agent to fill the damage and restore structural integrity during crack propagation. The synergistic effect of these two components forms a closed-loop mechanism, maintaining material stability and functionality in humid and acidic environments. Simultaneously, by modulating interfacial stress, it reduces crack propagation paths, ensuring long-term reliability under extreme conditions.

[0043] This invention expands the application boundaries of materials by enhancing both impact resistance and thermal shock resistance. The pull-out mechanism of carbon fiber and alumina whiskers preferentially disperses local stress, while the phase transformation toughening effect of nano-zirconia further absorbs crack energy. The low coefficient of thermal expansion of silicon nitride and the whisker bridging effect synergistically reduce the risk of thermal stress cracking. High-temperature vacuum heat treatment improves the structural stability of the material at extreme temperatures by eliminating internal defects and optimizing the grain structure, enabling it to maintain excellent mechanical properties and structural integrity even in harsh environments such as high-temperature impact and alternating thermal cycling.

[0044] The carbon fiber reinforced alumina-based composite armor material of this invention has significant advantages in military protection and aerospace fields. Its high strength and lightweight design meet the impact resistance requirements of armored vehicles and ship protective components. Its corrosion resistance and self-healing capabilities adapt to complex service environments such as humid and acidic conditions. The superhydrophobic coating and thermal stability design ensure performance stability under alternating high and low temperature conditions. In engineering scenarios with high reliability requirements, this material can not only replace traditional metal armor but also adapt to engineering needs of different scales through modular design.

[0045] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0046] Figure 1 This is a flowchart of the preparation method according to an embodiment of the present invention. Detailed Implementation

[0047] This application provides a carbon fiber reinforced alumina-based composite armor material and its preparation method.

[0048] Example 1: Standard Formulation Carbon Fiber Reinforced Alumina-Based Composite Armor Material Carbon fiber: 18 parts; Alumina: 68 parts; Carbon nanotubes: 7 parts; Silicon nitride: 5 parts; Graphene-coated boron nitride nanosheets: 3 parts; Self-healing microcapsules: 2 servings; Superhydrophobic nanocoating: 2 parts; Rare earth oxide reinforced phase: 3 parts; Nano-zirconia: 2 parts; Conductive carbon black / graphene composite: 1 part; Alumina whiskers: 3 parts.

[0049] Example 2: Increasing carbon fiber content Carbon fiber: 25 parts; Alumina: 68 parts; Carbon nanotubes: 7 parts; Silicon nitride: 5 parts; Graphene-coated boron nitride nanosheets: 3 parts; Self-healing microcapsules: 2 servings; Superhydrophobic nanocoating: 2 parts; Rare earth oxide reinforced phase: 3 parts; Nano-zirconia: 2 parts; Conductive carbon black / graphene composite: 1 part; Alumina whiskers: 3 parts.

[0050] Example 3: Reducing the content of carbon nanotubes Carbon fiber: 18 parts; Alumina: 68 parts; Carbon nanotubes: 5 parts; Silicon nitride: 5 parts; Graphene-coated boron nitride nanosheets: 3 parts; Self-healing microcapsules: 2 servings; Superhydrophobic nanocoating: 2 parts; Rare earth oxide reinforced phase: 3 parts; Nano-zirconia: 2 parts; Conductive carbon black / graphene composite: 1 part; Alumina whiskers: 3 parts.

[0051] Example 4: Enhanced impact resistance Carbon fiber: 22 parts; Alumina: 68 parts; Carbon nanotubes: 8 parts; Silicon nitride: 6 parts; Graphene-coated boron nitride nanosheets: 3 parts; Self-healing microcapsules: 2 servings; Superhydrophobic nanocoating: 2 parts; Rare earth oxide reinforced phase: 4 parts; Nano-zirconia: 2.5 parts; Conductive carbon black / graphene composite: 1 part; Alumina whiskers: 4 parts.

[0052] Example 5: Optimizing conductivity and interface bonding Carbon fiber: 18 parts; Alumina: 68 parts; Carbon nanotubes: 9 parts; Silicon nitride: 5 parts; Graphene-coated boron nitride nanosheets: 2 parts; Self-healing microcapsules: 2 servings; Superhydrophobic nanocoating: 2 parts; Rare earth oxide reinforced phase: 3 parts; Nano-zirconia: 2 parts; Conductive carbon black / graphene composite: 1.5 parts; Alumina whiskers: 3 parts.

[0053] Example 6: Improving thermal stability and creep resistance Carbon fiber: 18 parts; Alumina: 70 parts; Carbon nanotubes: 7 parts; Silicon nitride: 7 parts; Graphene-coated boron nitride nanosheets: 3 parts; Self-healing microcapsules: 2 servings; Superhydrophobic nanocoating: 2 parts; Rare earth oxide reinforcing phase: 4.5 parts; Nano-zirconia: 2 parts; Conductive carbon black / graphene composite: 1 part; Alumina whiskers: 3 parts.

[0054] Comparative Example 1: No self-healing microcapsules Carbon fiber: 18 parts; Alumina: 68 parts; Carbon nanotubes: 7 parts; Silicon nitride: 5 parts; Graphene-coated boron nitride nanosheets: 3 parts; Superhydrophobic nanocoating: 2 parts; Rare earth oxide reinforced phase: 3 parts; Nano-zirconia: 2 parts; Conductive carbon black / graphene composite: 1 part; Alumina whiskers: 3 parts.

[0055] Comparative Example 2: Without superhydrophobic nanocoating Carbon fiber: 18 parts; Alumina: 68 parts; Carbon nanotubes: 7 parts; Silicon nitride: 5 parts; Graphene-coated boron nitride nanosheets: 3 parts; Self-healing microcapsules: 2 servings; Rare earth oxide reinforced phase: 3 parts; Nano-zirconia: 2 parts; Conductive carbon black / graphene composite: 1 part; Alumina whiskers: 3 parts.

[0056] Comparative Example 3: Carbon Nanotube-Free Carbon fiber: 18 parts; Alumina: 68 parts; Silicon nitride: 5 parts; Graphene-coated boron nitride nanosheets: 3 parts; Self-healing microcapsules: 2 servings; Superhydrophobic nanocoating: 2 parts; Rare earth oxide reinforced phase: 3 parts; Nano-zirconia: 2 parts; Conductive carbon black / graphene composite: 1 part; Alumina whiskers: 3 parts.

[0057] Comparative Example 4: Alumina-free whiskers Carbon fiber: 18 parts; Alumina: 68 parts; Carbon nanotubes: 7 parts; Silicon nitride: 5 parts; Graphene-coated boron nitride nanosheets: 3 parts; Self-healing microcapsules: 2 servings; Superhydrophobic nanocoating: 2 parts; Rare earth oxide reinforced phase: 3 parts; Nano-zirconia: 2 parts; Conductive carbon black / graphene composite: 1 part.

[0058] Experimental example: The performance was measured based on Examples 1-6 and Comparative Examples 1-4 above, and the results are shown in Table 1. These include: 1. Mechanical property testing A universal testing machine was used to apply a load at a rate of 1 mm / min, and the maximum stress value at which the material failed was recorded to test the compressive strength value.

[0059] The sample was placed in a high-temperature furnace and heated to 1200℃ for 1 hour before a high-temperature bending strength test was conducted.

[0060] 2. Thermal stability test The linear expansion rate was measured using a thermomechanical analyzer (TMA) in the range of room temperature to 1000°C, and the coefficient of thermal expansion was calculated.

[0061] 3. Self-repair efficiency test After artificially creating cracks, the area was placed in a 150℃ oven for 2 hours, and the proportion of the repaired area was observed using an optical microscope.

[0062] 4. Corrosion resistance test According to ASTM B117 standard, spray corrosion was carried out in a 5% sodium chloride solution for 240 hours, and the percentage of surface corrosion area was recorded.

[0063] 5. Surface hydrophobicity test The static contact angle of a water droplet on a material surface is measured using a contact angle meter to evaluate the superhydrophobic properties.

[0064] Table 1. Experimental data of Examples 1-6 and Comparative Examples 1-4 of the present invention

[0065] As shown in Table 1, the mechanical properties are: Example 2 shows that by increasing the carbon fiber content, the compressive strength was increased to 1320 MPa, but the high-temperature flexural strength only increased slightly, indicating that the high strength characteristics of carbon fiber have a more significant effect on optimizing room temperature performance. Example 4 shows that the synergistic addition of carbon fiber, carbon nanotubes and alumina whiskers resulted in a high-temperature flexural strength of 700 MPa, indicating that the synergistic effect of multiple components can take into account both room temperature and high-temperature mechanical properties. Comparative Example 2 (without superhydrophobic nanocoating) had the lowest compressive strength and high-temperature flexural strength, indicating that surface hydrophobicity has an indirect effect on the overall mechanical properties.

[0066] Thermal stability: Example 6: By increasing the alumina content and the rare earth oxide reinforcing phase, the coefficient of thermal expansion was reduced to 5.5 × 10⁻ 6 / K, with a high-temperature flexural strength of 720MPa and thermal stability significantly better than other groups; Comparative Example 4 (without alumina whiskers) has a high-temperature bending strength of only 590 MPa, indicating that the bridging effect of alumina whiskers is crucial for crack suppression.

[0067] Self-repair efficiency: The self-healing efficiency of Examples 4 and 6 both exceeded 77%, indicating that the high content of rare earth oxides and alumina whiskers synergistically enhance the crack repair ability; Comparative Example 1 (without self-healing microcapsules) had a self-healing efficiency of only 50%, verifying the key role of self-healing microcapsules in long-term service life.

[0068] Corrosion resistance and surface hydrophobicity: In Examples 4 and 6, the corrosion area was less than 2% and the contact angle reached 154°, indicating that the superhydrophobic nanocoating and the self-healing microcapsules synergistically prevented the penetration of corrosive media. Comparative Example 2 (without superhydrophobic nano-coating) showed a corrosion area of ​​4.0% and a contact angle of only 140°, indicating that surface hydrophobicity has a decisive influence on corrosion resistance.

[0069] Based on the integrated experimental data, carbon fiber reinforced alumina-based composite armor material exhibits high compressive strength, excellent thermal stability, and self-healing ability, making it suitable for key fields such as aerospace protective structures, shipboard impact armor, and high-temperature industrial equipment.

[0070] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0071] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A carbon fiber reinforced alumina-based composite armor material, characterized in that, According to the following components in parts by weight composition: Carbon fiber: 10-25 parts; Alumina: 60-75 parts; Carbon nanotubes: 5-10 parts; Silicon nitride: 3-8 parts; Graphene-coated boron nitride nanosheets: 2-5 parts; Self-healing microcapsules: 1-3 parts; Superhydrophobic nanocoating: 1-3 parts; Rare earth oxide reinforcing phase: 2-5 parts; Nano-zirconia: 1-3 parts; Conductive carbon black / graphene composite: 0.5–2 parts; Alumina whiskers: 2-5 parts.

2. The carbon fiber reinforced alumina-based composite armor material according to claim 1, characterized in that: The carbon fiber is a carbonized fiber obtained by high-temperature carbonization of polyacrylonitrile fiber; the carbon nanotube is a composite powder formed by mixing single-walled carbon nanotubes and multi-walled carbon nanotubes; the graphene-coated boron nitride nanosheets are composite nanoparticles formed by coating graphene and boron nitride nanosheets by chemical vapor deposition. The mass ratio of the single-walled carbon nanotubes to the multi-walled carbon nanotubes is 1:1-2:1, and the mass ratio of the graphene to the boron nitride nanosheets is 1:1-2:

1.

3. The carbon fiber reinforced alumina-based composite armor material according to claim 1, characterized in that: The self-healing microcapsules are composite microspheres formed by polyurethane encapsulating epoxy resin, and the superhydrophobic nanocoating is a hydrophobic powder synthesized from nano-silica and perfluoroalkylsiloxane by a sol-gel method. The mass ratio of the polyurethane to the epoxy resin is 1:1 to 1.5:1, and the mass ratio of the nano-silica to the perfluoroalkylsiloxane is 1:1 to 2:

1.

4. The carbon fiber reinforced alumina-based composite armor material according to claim 1, characterized in that: The rare earth oxide reinforcing phase is composed of nanoscale particles formed by mixing yttrium oxide and erbium oxide; the conductive carbon black / graphene composite is a uniform dispersion formed by mixing conductive carbon black and graphene and then ultrasonically dispersing them in a 70% ethanol solution. The mass ratio of yttrium oxide to erbium oxide is 3:1-4:1, and the mass ratio of conductive carbon black to graphene is 1:1-2:

1.

5. A method for preparing a carbon fiber reinforced alumina-based composite armor material according to any one of claims 1-4, characterized in that: Includes the following steps: The conductive carbon black / graphene composite is sprayed onto the surface of the carbon fiber using an electrostatic spraying process to prepare a carbon fiber reinforcement. The carbon fiber reinforcement, alumina, nano-zirconia, silicon nitride and alumina whiskers are mixed in one step and then hot-pressed and sintered to prepare an alumina matrix material. The alumina matrix material, carbon nanotubes, graphene-coated boron nitride nanosheets, self-healing microcapsules, superhydrophobic nanocoating, and the rare earth oxide reinforcing phase are mixed a second time to prepare a functional reinforcing phase mixture. The functionally enhanced phase mixture was ground and mixed in a planetary ball mill to prepare composite powder; The composite powder is subjected to gradient hot pressing to prepare an armor material substrate; The armor material substrate is surface polished and heat-treated to obtain a carbon fiber reinforced alumina-based composite armor material.

6. The preparation method according to claim 5, characterized in that: The preparation of the carbon fiber reinforcement by electrostatic spraying the conductive carbon black / graphene composite onto the surface of the carbon fiber includes: The conductive carbon black / graphene composite was subjected to ultrasonic treatment at a frequency of 20-40 kHz for 30-60 minutes to obtain a homogeneous solution. The homogeneous solution is uniformly sprayed onto the surface of the carbon fiber using a spray gun. The spray gun voltage is 10-15kV, the spraying distance is 10-15cm, and the moving speed of the spray gun is 30-50cm / s, to obtain a carbon fiber coating. The carbon fiber coating is vacuum dried at 80-100℃ for 2-4 hours to obtain the carbon fiber reinforcement.

7. The preparation method according to claim 5, characterized in that: The method of preparing an alumina matrix material by hot-pressing and sintering a mixture of the carbon fiber reinforcement, alumina, nano-zirconia, silicon nitride, and alumina whiskers in a single step includes: The carbon fiber reinforcement, alumina, nano-zirconia, silicon nitride and alumina whiskers are mixed in a mass ratio of 20:60:1:2:2-30:90:1.5:3:3 and ground in a continuous ball mill at a speed of 200-400 rpm for 1-3 hours to obtain a mixture. The mixture is placed in a mold for hot pressing and sintering at a temperature of 1700-1800℃, a pressure of 7-9MPa, and a holding time of 2-3 hours. After demolding, the alumina matrix material is obtained.

8. The preparation method according to claim 5, characterized in that: The preparation of the functionally enhanced phase mixture by secondary mixing of the alumina matrix material, carbon nanotubes, graphene-coated boron nitride nanosheets, self-healing microcapsules, superhydrophobic nanocoating, and the rare earth oxide reinforcing phase includes: The carbon nanotubes and the graphene-coated boron nitride nanosheets were mixed at a mass ratio of 3:1 and placed in a high-speed disperser for 5-10 minutes at a speed of 3000-5000 rpm to obtain a premix. The self-healing microcapsules, superhydrophobic nanocoating and rare earth oxide reinforcing phase are mixed in a mass ratio of 1:1:1 and then placed in a planetary ball mill and dry-mixed at 200-300 rpm for 1-2 hours to obtain an intermediate mixture. The alumina matrix material, premix, and intermediate mixture are mixed at a mass ratio of 1:1:1 and placed in a vibrating screen. The mixture is then mixed for 15-30 minutes under a vibration amplitude of 50-80Hz to obtain the functionally enhanced phase mixture.

9. The preparation method according to claim 5, characterized in that, The step of preparing the armor material substrate by gradient hot pressing of the composite powder includes: The composite powder is placed in a plasma spraying device and preliminarily sprayed and shaped using argon as the carrier gas. The flow rate of the argon is 30-50 L / min, the spraying current intensity is 80-120 A, and the temperature is 200-300 °C, to obtain a preliminarily dense material. The preliminary dense material is subjected to gradient hot pressing to obtain the armor material substrate. The specific process of gradient hot pressing includes: First stage: Temperature 180-200℃, pressure 1.5-2.5MPa, time 8-12 minutes; Second stage: Temperature 200-210℃, pressure 7-9MPa, time 12-18 minutes.

10. The preparation method according to claim 5, characterized in that: The process of surface polishing and heat treatment of the armor material substrate to obtain carbon fiber reinforced alumina-based composite armor material includes: The armor material substrate is cooled to 40-50°C at room temperature and then surface polished with diamond abrasive to obtain a polishing material with a particle size of 5-10μm. The polishing material is placed in a high-temperature vacuum furnace and heat-treated at 1500-1600℃ for 3-5 hours to obtain the carbon fiber reinforced alumina-based composite armor material.

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