Ablation-resistant high-load-bearing reusable heat-resistant composite material and a preparation method thereof

Abstract

The present application belongs to the technical field of heat-resistant composite materials, and discloses a kind of ablation-resistant high bearing reusable heat-resistant composite material and preparation method thereof.The heat-resistant composite material of the present application comprises, from outside to inside, an ablation-resistant layer, a transition layer and a bearing layer;The ablation-resistant layer uses alumina fiber cloth as a reinforcing body, a phosphate solution as a matrix, and oxide ceramic particles as a filler;The transition layer uses quartz fiber cloth as a reinforcing body, silica sol as a matrix, and low-melting-point glass powder as a filler;The bearing layer uses carbon fiber cloth as a reinforcing body, boron-modified phenolic resin solution as a matrix, and inorganic non-metallic whiskers as a filler.The present application has excellent ablation resistance, high temperature bearing capacity and meets the reusable requirements through the design of functional layer, especially suitable for high-speed aircraft, reusable launch vehicle and other fields with high requirements for ablation resistance, bearing and reusability of materials.

Description

Technical Field

[0001] This invention belongs to the field of heat-resistant composite material technology, specifically relating to an ablation-resistant, high-load-bearing, reusable heat-resistant composite material and its preparation method. Background Technology

[0002] Current supersonic aircraft are exhibiting trends of high speed, high overload, and strong maneuverability, which leads to severe coupling effects of aerodynamic heat and structural loads under extreme conditions. Thermally insulating composite materials, with their comprehensive advantages of being lightweight, high-strength, erosion-resistant, capable of transmitting aerodynamic loads, and highly designable, have become a key fundamental material for overcoming the thermal barrier of aircraft.

[0003] Existing carbon fiber reinforced ceramic matrix composites possess high specific strength and achieve zero ablation under high-temperature oxygen-free conditions. However, carbon fibers suffer oxidation loss in oxygen-containing environments above 400°C, which leads to a significant reduction in the mechanical properties of the composites over a long period. Alumina fiber reinforced composites are resistant to high temperatures and oxidation, and exhibit good mechanical properties in high-temperature oxygen-containing environments. However, the specific strength of alumina fibers is lower than that of carbon fibers. Due to limitations in mechanical properties, alumina fiber reinforced composites are generally difficult to use as primary load-bearing heat-resistant structural materials. Quartz fiber reinforced composites have moderate density and good oxidation resistance, but a low upper limit for high temperature resistance, and are generally suitable for thermal environments with medium to low heat flux densities.

[0004] None of the above materials can simultaneously possess good ablation resistance and load-bearing capacity in high-temperature and oxygen-containing environments. Therefore, it is necessary to develop ablation-resistant, high-load-bearing, reusable heat-resistant composite materials to meet the external heat-resistant material requirements of hypersonic aircraft under unilateral heat flow scouring environments. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the shortcomings of the existing technology by providing an ablation-resistant, high-load-bearing, reusable heat-resistant composite material and its preparation method. The heat-resistant composite material contains different functional layers. Through the design of the functional layers, it can have both excellent ablation resistance and high-temperature load-bearing capacity, and meet the requirements for reusability. It is especially suitable for hypersonic aircraft, reusable launch vehicles and other fields where the requirements for the ablation resistance, load-bearing capacity and reusability of materials are high.

[0006] To address the technical problem proposed in this invention, this invention provides an ablation-resistant, high-load-bearing, reusable heat-resistant composite material, which comprises, from the outside in, an ablation-resistant layer, a transition layer, and a load-bearing layer.

[0007] In the above scheme, the ablation-resistant layer uses alumina fiber cloth as reinforcement, phosphate solution as matrix, and oxide ceramic particles as filler.

[0008] Furthermore, the alumina fiber cloth is a plain weave cloth with an areal density of 355~360 g / m³. 2 The thickness of a single layer is 0.3~0.4mm.

[0009] Furthermore, the phosphate solution is an aluminum dihydrogen phosphate solution, wherein the mass fraction of P2O5 is 30-35%, the mass fraction of Al2O3 is 7-10%, and the mass fraction of free H3PO4 is ≤2%.

[0010] Furthermore, the oxide ceramic particles are one or both of ZrO2 and HfO2, with a purity ≥99% and a particle size of 5~25μm.

[0011] Furthermore, the mass ratio of the alumina fiber cloth to the phosphate solution is 1:1.1 to 1:1.3, and the mass ratio of the phosphate solution to the oxide ceramic particles is 1:0.5 to 1:0.7.

[0012] In the above scheme, the transition layer uses quartz fiber cloth as reinforcement, silica sol as matrix, and low melting point glass powder as filler.

[0013] Furthermore, the quartz fiber cloth is a 2.5D woven fabric with a surface density of 800~805 g / m². 2 The thickness of a single layer is 0.9~1.1mm.

[0014] Furthermore, the silica sol contains 32-35% SiO2 by mass and ≤0.08% Na2O by mass.

[0015] Furthermore, the low-melting-point glass powder is one or both of B2O3 and Zn-B-Si glass material, with a purity ≥99% and a particle size of 3~10μm.

[0016] Furthermore, the mass ratio of the quartz fiber cloth to the silica sol is 1:1.2 to 1:1.5, and the mass ratio of the silica sol to the low melting point glass powder is 1:0.9 to 1:1.

[0017] In the above scheme, the load-bearing layer uses carbon fiber cloth as reinforcement, boron-modified phenolic resin solution as matrix, and inorganic non-metallic whiskers as filler.

[0018] Furthermore, the carbon fiber cloth is a plain weave cloth with an areal density of 270~275 g / m². 2 The thickness of a single layer is 0.3~0.4mm.

[0019] Furthermore, the boron-modified phenolic resin solution has a solid content of 66-70%, a boron mass fraction of 4-7%, and a free phenol mass fraction of ≤7%.

[0020] Furthermore, the inorganic non-metallic whiskers are one or both of BN whiskers and SiC whiskers, with a purity ≥99%, a diameter ≤1.5μm, and a length ≤25μm.

[0021] Furthermore, the mass ratio of the carbon fiber cloth to the boron-modified phenolic resin solution is 1:0.9 to 1:1.1, and the mass ratio of the boron-modified phenolic resin solution to the inorganic non-metallic whiskers is 1:0.7 to 1:0.9.

[0022] This invention also provides a method for preparing an ablation-resistant, high-load-bearing, reusable heat-resistant composite material, comprising the following steps: 1) After the phosphate solution and oxide ceramic particles are mixed evenly, the mixture is evenly brushed onto the alumina fiber cloth and allowed to dry naturally to obtain the ablation-resistant prepreg. 2) After mixing the silica sol and low melting point glass powder evenly, apply the mixture evenly to the quartz fiber cloth and allow it to dry naturally to obtain the transition layer prepreg. 3) After the boron-modified phenolic resin solution is mixed evenly with inorganic non-metallic whiskers, it is evenly coated onto carbon fiber cloth and allowed to dry naturally to obtain the load-bearing layer prepreg. 4) After the ablation-resistant prepreg, transition layer prepreg, and load-bearing layer prepreg are laid in sequence, they are hot-pressed and cured, and then subjected to thermal decomposition treatment in an inert atmosphere to obtain an ablation-resistant, high load-bearing, reusable heat-resistant composite material.

[0023] In the above scheme, the mixing of the matrix and filler in each layer is preferably carried out at 40~60℃.

[0024] In the above scheme, the ratio of the number of layers of the ablation-resistant prepreg, the transition layer prepreg, and the load-bearing layer prepreg is 2:(2~3):(3~7).

[0025] In the above scheme, the hot pressing curing molding adopts a gradient temperature rise process, which includes: holding at 80~120℃ for 1~2h, holding at 140~160℃ for 1~2h, holding at 170~190℃ for 2~3h, and holding at 210~230℃ for 1~2h; and applying a pressure of 10~15MPa in the second to fourth temperature ranges.

[0026] In the above scheme, the temperature of the thermal decomposition treatment is 800~1000℃, and the holding time is 10~30min.

[0027] Furthermore, the heating rate of the thermal pyrolysis treatment is controlled at 2~5℃ / min.

[0028] In the above scheme, the density of the heat-resistant composite material is 1.6~1.9 g / cm³. 3 Flexural strength 110~135MPa, tensile strength 115~140MPa.

[0029] In the above scheme, after the heat-resistant composite material undergoes repeated high-temperature heat testing at ≥1200℃ for ≥10 cycles, its density remains at 1.4~1.7 g / cm³. 3 Flexural strength 80~105MPa, tensile strength 85~110MPa.

[0030] In the above scheme, the heat-resistant composite material has a heat flux density of 4186.8±418.68 kW / m³. 2 Oxyacetylene flame ablation: mass ablation rate ≤ 0.009 g / s, linear ablation rate ≤ 0.01 mm / s.

[0031] The main technical concept of this invention is as follows: To address the problems of difficulty in simultaneously ensuring thermal insulation and load-bearing capacity, and low repeatability in aerodynamic thermal environments, single-fiber reinforced ceramic matrix composites are designed with an ablation-resistant layer, a transition layer, and a load-bearing layer. Specifically: The ablation-resistant layer uses alumina fiber cloth as reinforcement, phosphate solution as matrix, and oxide ceramic particles as filler. During the curing stage, the phosphate matrix undergoes dehydration and condensation to form PO-Al covalent bonds with the hydroxyl groups on the surface of alumina fibers, forming a strong bonding interface. During the nitrogen atmosphere thermal decomposition process, the oxide ceramic powders ZrO2 and HfO2 react with phosphate to generate stable zirconium pyrophosphate and hafnium pyrophosphate ceramic phases, which serve as a high-strength skeleton to resist thermal erosion. The transition layer uses quartz fiber cloth as reinforcement, silica sol as matrix, and low-melting-point glass powder as filler. During the curing stage, the silica sol dehydrates and condenses to form a continuous silica network structure, and forms Si-O-Si covalent bonds with the hydroxyl groups on the surface of the quartz fiber. During the oxygen-free thermal decomposition process, the low-melting-point glass powder B2O3 softens with the Zn-B-Si glass material to form a low-viscosity composite glass phase, which blocks the gas diffusion channels and forms a dense antioxidant protective layer. The load-bearing layer uses carbon fiber cloth as reinforcement, boron-modified phenolic resin solution as matrix, and inorganic non-metallic whiskers as filler. During the curing stage, the boron-modified phenolic resin undergoes a cross-linking reaction to form a dense three-dimensional organic network structure. During the oxygen-free thermal decomposition process, the boron-modified phenolic resin is transformed into a carbon matrix and forms a tight interface bond with carbon fiber and inorganic non-metallic whiskers, forming a "fiber-whisker-matrix" synergistic load-bearing system. During service, the heat-resistant composite material composed of the aforementioned functional layers exhibits excellent resistance to ablation and high-temperature load-bearing capacity. In the ablation-resistant layer, the pyrophosphate ceramic phase and alumina fibers bridge the thermal stress generated by the heat flow, and the viscous flow of phosphate at high temperatures enables dynamic self-healing of surface microcracks. In the transition layer, the low-melting-point glass frit softens upon heating, continuously filling the voids caused by matrix loss, forming a dense anti-oxidation layer, while simultaneously alleviating the thermal stress generated by the ablation-resistant and load-bearing layers. The load-bearing layer, protected by the transition and ablation-resistant layers, exists in a near-oxygen-free environment, where the carbon matrix, carbon fibers, and inorganic non-metallic whiskers work together to support the load, fully utilizing the mechanical properties of the carbon fibers. Thus, the material of this invention possesses both excellent ablation resistance and high-temperature load-bearing capacity, meets the requirements for reusability, and effectively resists unilateral heat flow erosion.

[0032] Furthermore, the phosphate, silica sol, and boron phenolic resin matrices used in this invention have similar curing temperatures, allowing for one-time co-curing. During curing, the phosphate groups in the ablation-resistant layer undergo dehydration condensation with the silanol groups in the transition layer, forming high-strength Si-OP chemical bonds. Simultaneously, the uniform coating properties of the silica sol effectively compensate for the volume shrinkage defects during the curing process of the phosphate, and the two work together to construct a dense and stable transition structure. The silanol groups in the transition layer undergo dehydration condensation with the phenolic hydroxyl and boronol groups in the load-bearing layer, forming high-strength Si-OC and Si-OB covalent bonds, thereby constructing a robust chemical bridging framework. At the same time, the silica particles in the silica sol can deeply penetrate and fill the micropores inside the boron phenolic resin, eliminating interface defects and significantly improving the density and bonding strength of the interface.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) The heat-resistant composite material provided by this invention achieves synergistic optimization of ablation resistance, load-bearing capacity, and reusability through a three-layer structure design consisting of an ablation-resistant layer, a transition layer, and a load-bearing layer. The density of this composite material is 1.6~1.9 g / cm³. 3 With a flexural strength of 110~135MPa and a tensile strength of 115~140MPa, it combines lightweight and high load-bearing capacity. After undergoing repeated high-temperature thermal tests at ≥1200℃ for ≥10 cycles, the material still maintains excellent structural integrity, with a density of 1.4~1.7g / cm³. 3 Flexural strength 80~105MPa, tensile strength 85~110MPa; heat flux density 2.4±0.24 MW / m 2 Under oxyacetylene flame ablation conditions, the mass ablation rate is ≤0.09 g / s and the linear ablation rate is ≤0.01 mm / s, exhibiting excellent ablation resistance. These properties enable the material of this invention to meet the requirements of ablation resistance, high load-bearing capacity, and reusability under extreme thermal environments, significantly extending the service life of the thermal protection structure.

[0034] 2) This invention employs a one-step molding process using prepregs with different functional layers for co-curing. Each functional layer undergoes simultaneous cross-linking during curing, and the interlayer interfaces form an integrated structure through chemical bonding and molecular chain entanglement. This avoids the interface weakness problem caused by secondary bonding in traditional multi-step molding processes. Simultaneously, this invention performs thermal decomposition treatment on the co-cured composite material under a nitrogen atmosphere, further enhancing the material's heat resistance and thermal stability, and endowing it with excellent reusability. The overall process is simple, controllable, and has a short preparation cycle. It can also achieve integrated molding of large-sized irregularly shaped components, demonstrating good engineering applicability and mass production prospects, making it suitable for widespread application in the aerospace thermal protection field. Attached Figure Description

[0035] Figure 1 The process flow diagram for preparing the heat-resistant composite material is shown in the example.

[0036] Figure 2 This is a photograph of the 10mm thick heat-resistant composite material prepared in Example 1.

[0037] Figure 3 The image shows the XRD pattern of the 4 mm thick heat-resistant composite material prepared in Example 1. Detailed Implementation

[0038] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0039] The raw materials used in the following embodiments include: Alumina fiber cloth is a plain weave fabric with an areal density of 355~360 g / m². 2 The thickness of a single layer is 0.4 mm; The phosphate solution is an aluminum dihydrogen phosphate solution, prepared by mixing and stirring phosphoric acid, aluminum hydroxide, and deionized water at 85°C for 2 hours. Its P2O5 mass fraction is 35%, Al2O3 mass fraction is 8%, and free H3PO4 mass fraction is ≤2%. The oxide ceramic particles include ZrO2 and HfO2, with a purity of ≥99% and a particle size of 5~25μm; Quartz fiber cloth is a 2.5D woven fabric with a surface density of 800~805 g / m². 2 Single layer thickness 1.0mm; The silica sol contains 34% SiO2 by mass and ≤0.08% Na2O by mass. Low melting point glass powders include B2O3 and Zn-B-Si glass frits, with a purity of ≥99% and a particle size of 3~10μm; The carbon fiber cloth is a plain weave fabric with an areal density of 270~275 g / m³. 2The thickness of a single layer is 0.38 mm; The boron-modified phenolic resin solution was prepared by mixing boron-modified phenolic resin powder with anhydrous ethanol at 56°C for 1-2 hours. Its solid content was 67%, boron mass fraction was 5%, and free phenol mass fraction was ≤7%. Inorganic non-metallic whiskers include BN whiskers and SiC whiskers, with a purity ≥99%, a diameter ≤1.5μm, and a length ≤25μm.

[0040] Example 1 This embodiment prepares an ablation-resistant, high-load-bearing, reusable, heat-resistant composite material. The specific steps are as follows: 1) Preparation of ablation-resistant prepreg: ZrO2 and HfO2 were mixed evenly at a mass ratio of 1:1 to obtain mixed oxide ceramic particles; phosphate solution and mixed oxide ceramic particles were added to a mixer at a mass ratio of 1:0.6 and mixed at 50℃ and 300 r / min for 45 min to obtain ablation-resistant mixed slurry; the ablation-resistant mixed slurry was manually and evenly brushed onto alumina fiber cloth, and the mass ratio of alumina fiber cloth to phosphate solution was controlled at 1:1.2 during brushing. After brushing, it was dried in a cool place for 12 h to obtain ablation-resistant prepreg. 2) Preparation of transition layer prepreg: B2O3 and Zn-B-Si glass filler were mixed evenly at a mass ratio of 1:1.5 to obtain mixed low-melting-point glass powder; silica sol and mixed low-melting-point glass powder were added to a mixer at a mass ratio of 1:0.9 and mixed at 50℃ and 300r / min for 30min to obtain transition layer mixed slurry; the transition layer mixed slurry was manually and evenly coated onto quartz fiber cloth, and the mass ratio of quartz fiber cloth to silica sol was controlled at 1:1.3 during coating. After coating, it was dried in a cool place for 12h to obtain transition layer prepreg. 3) Preparation of load-bearing layer prepreg: BN whiskers and SiC whiskers were mixed evenly at a mass ratio of 1:0.95 to obtain mixed inorganic non-metallic whiskers; boron-modified phenolic resin solution and mixed inorganic non-metallic whiskers were added to a mixer at a mass ratio of 1:0.8 and mixed at 50℃ and 400 r / min for 40 min to obtain load-bearing layer mixed slurry; the load-bearing layer mixed slurry was evenly coated onto carbon fiber cloth, and the mass ratio of carbon fiber cloth to boron-modified phenolic resin solution was controlled at 1:1 during coating. After coating, it was dried in a cool place for 12 h to obtain load-bearing layer prepreg. 4) Gradient lamination, curing, and heat treatment: To meet the needs of subsequent performance testing, two specifications of samples with finished product thicknesses of 4mm and 10mm were prepared. Specifically, the ablation-resistant layer prepreg, transition layer prepreg, and load-bearing layer prepreg were laid in sequence in a layer ratio of 2:2:5 (2 layers, 2 layers, and 5 layers respectively) and a layer ratio of 2:2:7 (4 layers, 4 layers, and 14 layers respectively) and placed into a molding die. The die was then placed in a hot press. The specific curing process was 100℃ for 1 hour and 150℃ for 12 hours under pressure. The pressure was maintained at 12 MPa for 1 hour, then at 180℃ for 3 hours, and at 220℃ for 1 hour. After natural cooling to room temperature, a ceramic matrix composite green body was obtained. The green body was placed in a tube furnace at room temperature, and nitrogen was introduced at a rate of 0.3 L / min. The temperature was then increased to 1000℃ at a rate of 10℃ / min and held for 20 minutes for heat treatment. After natural cooling to room temperature, the nitrogen valve was closed to obtain two specifications of ablation-resistant, high load-bearing, reusable heat-resistant composite material with thicknesses of 4 mm and 10 mm.

[0041] Figure 2 The image shows a physical picture of the 10mm thick heat-resistant composite material prepared in Example 1. As can be seen from the picture, the heat-resistant material consists of three functional layers, and there is no obvious boundary between adjacent functional layers, indicating that the ablation-resistant layer, transition layer and load-bearing layer are tightly bonded and have a complete and uniform appearance.

[0042] Figure 3 The image shows the XRD pattern of the 4mm thick heat-resistant composite material prepared in Example 1. The image shows that after the ablation layer pyrolyzes, HfO2, ZrO2, and ZrP2O7 are generated, indicating that the oxide ceramic particles react with phosphate to form a new ablation-resistant phase, thus improving the overall oxidation and ablation resistance of the ablation-resistant layer. After the transition layer pyrolyzes, B2O3-SiO2 and SiO2 are generated. The B2O3-SiO2 glass phase has self-healing and low expansion characteristics, indicating that during repeated thermal processes, the transition layer can continuously alleviate thermal stress and seal the voids generated by the decomposition of the high-temperature matrix, preventing oxygen from entering the load-bearing layer. After the load-bearing layer pyrolyzes, it contains SiC and BN whiskers, indicating that the inorganic non-metallic whisker structure is not destroyed during the ablation process and still plays a role in toughening and reinforcement.

[0043] Example 2 1) Preparation of ablation-resistant prepreg: Phosphate solution and HfO2 ceramic particles were added to a mixer at a mass ratio of 1:0.7 and mixed at 50℃ and 300 r / min for 45 min to obtain ablation-resistant slurry. The ablation-resistant slurry was manually and evenly coated onto alumina fiber cloth. During coating, the mass ratio of alumina fiber cloth to phosphate solution was controlled to be 1:1.3. After coating, the cloth was dried in a cool place for 12 h to obtain ablation-resistant prepreg. 2) Preparation of transition layer prepreg: Silica sol and B2O3 powder were added to a mixer at a mass ratio of 1:1 and mixed at 50℃ and 300 r / min for 30 min to obtain a transition layer slurry. The transition layer slurry was manually and evenly coated onto a quartz fiber cloth. During coating, the mass ratio of quartz fiber cloth to silica sol was controlled to be 1:1.5. After coating, the cloth was dried in a cool place for 12 h to obtain the transition layer prepreg. 3) Preparation of load-bearing layer prepreg: Add boron-modified phenolic resin solution and BN whiskers to a mixer at a mass ratio of 1:0.9 and mix for 40 minutes at 50℃ and 400 r / min to obtain load-bearing layer slurry; uniformly coat the load-bearing layer slurry onto carbon fiber cloth, controlling the mass ratio of carbon fiber cloth to boron-modified phenolic resin solution to be 1:1.1 during coating, and then air dry in a cool place for 12 hours to obtain load-bearing layer prepreg. 4) Gradient lamination, curing, and heat treatment: To meet the needs of subsequent performance testing, two specifications of samples with finished product thicknesses of 4mm and 10mm were prepared. Specifically, the ablation-resistant layer prepreg, transition layer prepreg, and load-bearing layer prepreg were laid in sequence in a layer ratio of 2:3:3 (2, 3, and 3 layers respectively) and a layer ratio of 2:2:7 (4, 4, and 14 layers respectively), and then the mold was placed in a hot press. The specific curing process was to hold at 120℃ for 2 hours and then pressurize at 160℃ for 14 hours. The pressure was maintained at 15 MPa for 2 hours, then at 190℃ for 2 hours, and at 230℃ for 1 hour. After natural cooling to room temperature, a ceramic matrix composite green body was obtained. The green body was placed in a tube furnace at room temperature, and nitrogen was introduced at a rate of 0.2 L / min. The temperature was then increased to 1000℃ at a rate of 10℃ / min and held for 30 minutes for heat treatment. After natural cooling to room temperature, the nitrogen valve was closed to obtain two specifications of ablation-resistant, high load-bearing, reusable heat-resistant composite material with thicknesses of 4 mm and 10 mm.

[0044] Example 3 1) Preparation of ablation-resistant prepreg: Phosphate solution and ZrO2 ceramic particles were added to a mixer at a mass ratio of 1:0.5 and mixed at 50℃ and 300 r / min for 45 min to obtain ablation-resistant slurry. The ablation-resistant slurry was manually and evenly coated onto alumina fiber cloth. During coating, the mass ratio of alumina fiber cloth to phosphate solution was controlled to be 1:1.1. After coating, the cloth was dried in a cool place for 12 h to obtain ablation-resistant prepreg. 2) Preparation of transition layer prepreg: Silica sol and Zn-B-Si glass filler were added to a mixer at a mass ratio of 1:0.9 and mixed at 50℃ and 300 r / min for 30 min to obtain a transition layer slurry. The transition layer slurry was manually and evenly coated onto a quartz fiber cloth, with the mass ratio of quartz fiber cloth to silica sol controlled at 1:1.2. After coating, the cloth was dried in a cool place for 12 h to obtain the transition layer prepreg. 3) Preparation of load-bearing layer prepreg: Boron-modified phenolic resin solution and SiC whiskers were added to a mixer at a mass ratio of 1:0.7 and mixed at 50℃ and 400 r / min for 40 min to obtain load-bearing layer slurry. The load-bearing layer slurry was uniformly coated onto carbon fiber cloth. During coating, the mass ratio of carbon fiber cloth to boron-modified phenolic resin solution was controlled at 1:0.9. After coating, the mixture was dried in a cool place for 12 h to obtain load-bearing layer prepreg. 4) Gradient lamination, curing, and heat treatment: To meet the needs of subsequent performance testing, two specifications of samples with finished product thicknesses of 4mm and 10mm were prepared. Specifically, the ablation-resistant layer prepreg, transition layer prepreg, and load-bearing layer prepreg were laid in sequence in a layer ratio of 2:2:5 (2 layers, 2 layers, and 5 layers respectively) and a layer ratio of 2:3:4 (4 layers, 6 layers, and 8 layers respectively) and placed into a molding die. The die was then placed in a hot press. The specific curing process was 80℃ for 1 hour and 140℃ for 12 minutes of pressure. The ceramic matrix composite green body was obtained by holding the pressure at 13 MPa at 170℃ for 3 hours, then at 14 MPa at 210℃ for 2 hours, and then naturally cooling to room temperature. The green body was then placed in a tube furnace at room temperature, and nitrogen was introduced at a rate of 0.4 L / min. The temperature was then increased to 1000℃ at 10℃ / min and held for 10 minutes for heat treatment. After naturally cooling to room temperature, the nitrogen valve was closed to obtain two specifications of ablation-resistant, high load-bearing, reusable heat-resistant composite material with thicknesses of 4 mm and 10 mm.

[0045] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that no ablation-resistant layer is prepared, and the resulting heat-resistant composite material contains only the two-layer structure of transition layer and load-bearing layer as in Example 1.

[0046] Comparative Example 2 The only difference between Comparative Example 2 and Example 1 is that no transition layer is prepared, and the resulting heat-resistant composite material contains only the two-layer structure of the ablation-resistant layer and the load-bearing layer in Example 1.

[0047] Comparative Example 3 The only difference between Comparative Example 3 and Example 1 is that no load-bearing layer is prepared, and the resulting heat-resistant composite material contains only the two-layer structure of the ablation-resistant layer and the transition layer in Example 1.

[0048] Comparative Example 4 The only difference between Comparative Example 4 and Example 1 is that no ablation-resistant layer and transition layer are prepared, and the resulting heat-resistant composite material contains only the load-bearing layer structure of Example 1.

[0049] Comparative Example 5 The only difference between Comparative Example 5 and Example 1 is that no transition layer and load-bearing layer are prepared, and the resulting heat-resistant composite material contains only one ablation-resistant layer structure as in Example 1.

[0050] Comparative Example 6 The only difference between Comparative Example 6 and Example 1 is that no ablation-resistant layer and load-bearing layer are prepared, and the resulting heat-resistant composite material contains only the transition layer structure of Example 1.

[0051] Performance tests were conducted on the heat-resistant composite materials prepared in each embodiment and comparative example, including: using 4mm thick specimens, the density, tensile strength, and flexural strength of the specimens and the specimens after thermal cycling were tested. Density testing was performed according to GB / T1463-2005, and tensile and flexural strength testing was performed according to GB / T 1447-2005 and GB / T 1449-2005, respectively. Using 10mm thick specimens, the finished specimens were processed into Φ30×10mm ablation specimens according to GJB323B-2018 standard, and ablation tests were performed on the specimens using an oxyacetylene flame in an air atmosphere. The thermal cycling test involved single-sided heating in air using a quartz lamp heating system, cycling from room temperature to 1200℃ 10 times, each cycle lasting 10 minutes; the oxyacetylene flame heat flux density for the ablation test was 4186.8±418.68 kW / m³. 2 The ablation duration was 20 seconds. Specific test results are shown in the table below.

[0052] Table 1

[0053] As can be seen from the table above, the ablation-resistant, high-load-bearing, reusable heat-resistant composite material prepared in the embodiments of the present invention has excellent mechanical properties. After 10 repeated thermal cycles, it still retains high mechanical strength, indicating that the internal structure of the heat-resistant composite material remains good after thermal cycling, and it has the integrated functions of ablation resistance, high load-bearing capacity and reusability.

[0054] In the comparison examples, Comparative Example 1, lacking an ablation-resistant layer, suffered damage to the surface transition layer after thermal cycling, allowing oxygen to enter the load-bearing layer and significantly reducing its mechanical properties. Comparative Example 2, also lacking a transition layer, exhibited slight delamination due to thermal stress after thermal cycling, resulting in a significant reduction in mechanical properties. Comparative Example 3, lacking a load-bearing layer, had a high mechanical retention rate, but its overall material mechanical properties were low, limiting its application scenarios. Comparative Example 4, an ablation-resistant layer composite material, showed only a slight decrease in mechanical strength after thermal cycling, but its mechanical properties were still low. Comparative Example 5, a transition layer composite material, experienced a significant reduction in mechanical properties after thermal cycling due to the crystallization and embrittlement of quartz fibers during long-term service at temperatures above 1000°C, caused by the significant reduction in mechanical properties. Comparative Example 6, a load-bearing layer composite material, showed that carbon fibers were easily oxidized at high temperatures, and after thermal cycling, oxygen reacted with the carbon fibers through the voids created by resin decomposition, resulting in almost no mechanical strength in the composite material.

[0055] The above embodiments are merely examples for clear illustration and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations, and any obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An ablation-resistant, high-load-bearing, reusable, heat-resistant composite material, characterized in that, From the outside in, it consists of an ablation-resistant layer, a transition layer, and a load-bearing layer. The ablation-resistant layer uses alumina fiber cloth as reinforcement, phosphate solution as matrix, and oxide ceramic particles as filler. The transition layer uses quartz fiber cloth as reinforcement, silica sol as matrix, and low melting point glass powder as filler. The load-bearing layer uses carbon fiber cloth as reinforcement, boron-modified phenolic resin solution as matrix, and inorganic non-metallic whiskers as filler.

2. The ablation-resistant, high-load-bearing, reusable, heat-resistant composite material according to claim 1, characterized in that, The mass ratio of the alumina fiber cloth to the phosphate solution is 1:1.1 to 1:1.3, and the mass ratio of the phosphate solution to the oxide ceramic particles is 1:0.5 to 1:0.7; the phosphate solution is aluminum dihydrogen phosphate solution; the oxide ceramic particles are one or both of ZrO2 and HfO2.

3. The ablation-resistant, high-load-bearing, reusable, heat-resistant composite material according to claim 2, characterized in that, The alumina fiber cloth is a plain weave cloth with a surface density of 355~360 g / m². 2 The single-layer thickness is 0.3~0.4mm; the aluminum dihydrogen phosphate solution has a P2O5 mass fraction of 30~35%, an Al2O3 mass fraction of 7~10%, and a free H3PO4 mass fraction of ≤2%; the oxide ceramic particles have a purity of ≥99% and a particle size of 5~25μm.

4. The ablation-resistant, high-load-bearing, reusable heat-resistant composite material according to claim 1, characterized in that, The mass ratio of the quartz fiber cloth to the silica sol is 1:1.2 to 1:1.5, and the mass ratio of the silica sol to the low melting point glass powder is 1:0.9 to 1:1; the silica sol contains 32-35% SiO2 and ≤0.08% Na2O; the low melting point glass powder is one or both of B2O3 and Zn-B-Si glass.

5. The ablation-resistant, high-load-bearing, reusable, heat-resistant composite material according to claim 4, characterized in that, The quartz fiber cloth is a 2.5D woven fabric with a surface density of 800~805 g / m². 2 The single-layer thickness is 0.9~1.1mm; the low-melting-point glass powder has a purity of ≥99% and a particle size of 3~10μm.

6. The ablation-resistant, high-load-bearing, reusable, heat-resistant composite material according to claim 1, characterized in that, The mass ratio of the carbon fiber cloth to the boron-modified phenolic resin solution is 1:0.9 to 1:1.1, and the mass ratio of the boron-modified phenolic resin solution to the inorganic non-metallic whiskers is 1:0.7 to 1:0.9; the inorganic non-metallic whiskers are one or both of BN whiskers and SiC whiskers.

7. The ablation-resistant, high-load-bearing, reusable heat-resistant composite material according to claim 6, characterized in that, The carbon fiber cloth is a plain weave cloth with an areal density of 270~275 g / m³. 2 The single-layer thickness is 0.3~0.4mm; the solid content of the boron-modified phenolic resin solution is 66~70%, the boron mass fraction is 4~7%, and the free phenol mass fraction is ≤7%; the purity of the inorganic non-metallic whiskers is ≥99%, the diameter is ≤1.5μm, and the length is ≤25μm.

8. A method for preparing an ablation-resistant, high-load-bearing, reusable, heat-resistant composite material as described in any one of claims 1 to 7, characterized in that, Includes the following steps: 1) After the phosphate solution and oxide ceramic particles are mixed evenly, the mixture is evenly brushed onto the alumina fiber cloth and allowed to dry naturally to obtain the ablation-resistant prepreg. 2) After mixing the silica sol and low melting point glass powder evenly, apply the mixture evenly to the quartz fiber cloth and allow it to dry naturally to obtain the transition layer prepreg. 3) After the boron-modified phenolic resin solution is mixed evenly with inorganic non-metallic whiskers, it is evenly coated onto carbon fiber cloth and allowed to dry naturally to obtain the load-bearing layer prepreg. 4) After the ablation-resistant prepreg, transition layer prepreg, and load-bearing layer prepreg are laid in sequence, they are hot-pressed and cured, and then subjected to thermal decomposition treatment in an inert atmosphere to obtain an ablation-resistant, high load-bearing, reusable heat-resistant composite material.

9. The method for preparing the ablation-resistant, high-load-bearing, reusable heat-resistant composite material according to claim 8, characterized in that, The ratio of the number of layers of the ablation-resistant prepreg, the transition layer prepreg, and the load-bearing layer prepreg is 2:(2~3):(3~7); the hot-press curing molding adopts a gradient temperature increase, which includes: holding at 80~120℃ for 1~2h, holding at 140~160℃ for 1~2h, holding at 170~190℃ for 2~3h, and holding at 210~230℃ for 1~2h; and applying a pressure of 10~15MPa in the second to fourth temperature ranges.

10. The method for preparing the ablation-resistant, high-load-bearing, reusable, heat-resistant composite material according to claim 8, characterized in that, The pyrolysis treatment temperature is 800~1000℃, and the holding time is 10~30min; the heating rate during the pyrolysis treatment is controlled at 2~5℃ / min; the density of the heat-resistant composite material is 1.6~1.9g / cm³. 3 Flexural strength 110~135MPa, tensile strength 115~140MPa.

Images