A multi-scale three-dimensional network carbon skeleton structure-assisted composite material and its preparation method

Abstract

This invention belongs to the field of composite material preparation technology, and discloses a multi-scale three-dimensional network carbon skeleton structure-assisted composite material and its preparation method: A low-density fiber preform composite material is impregnated in a precursor solution to obtain an impregnated low-density fiber preform composite material; the precursor solution is a mixture of resorcinol, formaldehyde solution, distilled water, and hexadecyltrimethylammonium bromide; the impregnated low-density fiber preform composite material is subjected to curing treatment, carbonization treatment, and active reaction melt infiltration treatment to obtain the multi-scale three-dimensional network carbon skeleton structure-assisted composite material. This invention introduces a three-dimensional network carbon skeleton structure into the low-density preform composite material, effectively dividing large pores, enhancing capillary action, and simultaneously allowing the molten alloy to fully react, reducing residual metal inside the composite material, and refining the grain size of the ceramic product to prepare a high-performance ceramic-modified composite material.

Description

Technical Field

[0001] This invention belongs to the field of composite material preparation technology, and relates to a multi-scale three-dimensional network carbon skeleton structure-assisted composite material and its preparation method. Background Technology

[0002] Carbon / carbon composites are widely used in thermal protection components of aerospace vehicles due to their low density, high specific strength, high modulus, and excellent high-temperature mechanical properties. However, they oxidize in oxygen-rich environments exceeding 400 °C, easily leading to premature failure due to structural instability. Therefore, ultra-high temperature ceramic components (such as HfC, ZrC, HfB2, and ZrB2) are typically used for modification to improve their oxidation / ablation resistance. Among these, reactive melt infiltration (RMI) technology has become the preferred method due to its advantages such as short preparation cycle, high design flexibility of composition and structure, and near-net-shape molding. This technology mainly utilizes capillary forces to infiltrate molten metal or alloys into a fiber preform. The infiltrated component reacts chemically with other components in the preform (pyrolytic carbon or resin carbon, etc.) to generate a ceramic matrix, thus preparing the composite material. The main factor affecting capillary forces in this process is the capillary radius; the smaller the radius, the greater the capillary force, specifically reflected in the pore size of the fiber preform used. Liu et al. (Liu Yue, Research on Preparation of Ultra-High Temperature Ceramic Modified C / C Composites by Reactive Melting Method, Doctoral Dissertation of Northwestern Polytechnical University, 2017) found that when preparing C / C-SiC-ZrB2 composites using the RMI process, high-density composites (low porosity and small pore size) were not conducive to melt infiltration, while low-density composites (high porosity and large pore size) suffered severe erosion of the original carbon fibers and carbon matrix after melt infiltration, thus damaging their mechanical properties. Meanwhile, for composite materials prepared from complex preforms, such as 2.5D needle-punched preforms, 3D fine-knitted preforms, 3D yarn-wound preforms, three-dimensional four-dimensional preforms, and meshless preforms, large-sized pore structures still exist between fiber bundles and between layers. On the one hand, the melt is prone to loss due to insufficient carbon source, leaving unfilled pores. On the other hand, a large amount of residual metal will exist inside the composite material, affecting its ablation performance. Therefore, the regulation of the internal pore structure of composite materials is one of the problems that urgently need to be solved to achieve high-efficiency and high-performance reactive melting infiltration. In addition, Liu et al. (Zhiqiang Liu, Qiangang Fu, Huilun Shi, et al., Comparative study of microstructure and ablation behavior of C / C-HfC-SiC composites prepared under two different conditions, Materials Characterization, 194 (2022) 112467) prepared C / C-HfC-SiC composites using RMI technology. It was found that the surface of the material is composed of large ceramic blocks, which are prone to defects such as a large number of cracks due to stress concentration. This makes it easy for the oxide layer to peel off during the ablation process, and it cannot fully exert its protective performance.Therefore, how to refine the ceramic particles generated during the melting and infiltration process, alleviate the thermal stress during the ablation process, and maintain the stability of the oxide film remains one of the key challenges that RMI technology urgently needs to overcome. Summary of the Invention

[0003] To overcome the shortcomings of existing technologies, the present invention aims to propose a multi-scale three-dimensional network carbon skeleton structure-assisted composite material and its preparation method. The present invention aims to introduce a three-dimensional network carbon skeleton structure into a low-density preform composite material to effectively divide large pores, enhance capillary action, and at the same time allow the molten alloy to fully react, reduce residual metal inside the composite material, and refine the grain size of the ceramic product, so as to prepare a high-performance ceramic-modified composite material.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for preparing a multi-scale three-dimensional network carbon skeleton structure-assisted composite material, comprising:

[0006] The low-density fiber preform composite material is impregnated in a precursor solution to obtain the impregnated low-density fiber preform composite material; the precursor solution is a mixture of resorcinol, formaldehyde solution, distilled water and hexadecyltrimethylammonium bromide;

[0007] The impregnated low-density fiber preform composite material is cured, and after curing, it is finally carbonized in a protective atmosphere to form a phenolic resin carbon skeleton structure with a three-dimensional network structure in the low-density fiber preform composite material.

[0008] The low-density fiber preform composite material that has undergone carbonization is subjected to reactive melt infiltration treatment to obtain the multi-scale three-dimensional network carbon skeleton structure assisted composite material.

[0009] Preferably, the density of the low-density fiber preform composite material is 1.0-1.3 g / cm³. 3 .

[0010] Preferably, the low-density fiber preform composite material is one or more of the following: 2.5D needle-punched preform, 3D puncture preform, 3D yarn-wound structure preform, three-dimensional four-way preform, and meshless structure preform.

[0011] The fibers in the low-density fiber preform composite material are one or more of polyacrylonitrile-based carbon fibers, mesophase pitch-based carbon fibers, and SiC fibers.

[0012] Preferably, in the precursor solution, the mass ratio of resorcinol, formaldehyde solution, distilled water and hexadecyltrimethylammonium bromide is (5-8):(7-10):(7-12):(0.05-0.24), and the mass concentration of the formaldehyde solution is 37 wt.%.

[0013] Preferably, when the low-density fiber preform composite material is impregnated in the precursor solution, it is impregnated for 30-50 min under a pressure of 0.01-0.09 MPa.

[0014] Preferably, when curing the impregnated low-density fiber preform composite material, it is baked at 60-100℃ for 24-36 h.

[0015] Preferably, after curing, the final carbonization treatment under a protective atmosphere is carried out at 900-1900 °C for 2-4 hours.

[0016] Preferably, when performing reactive melting treatment on the low-density fiber preform composite material that has undergone carbonization, an alloy compound powder is coated on the surface of the low-density fiber preform composite material that has undergone carbonization, and then it is treated at 1800-2000 °C for 0.5-2 h in a protective atmosphere to obtain the multi-scale three-dimensional network carbon skeleton structure assisted composite material.

[0017] Preferably, the alloy compound powder includes at least one of ZrSi2 and HfSi2.

[0018] The present invention also provides a multi-scale three-dimensional network carbon skeleton structure-assisted composite material, which is prepared by the preparation method of the present invention as described above.

[0019] The present invention has the following beneficial effects:

[0020] This invention utilizes resorcinol and formaldehyde as reactants and CTAB (hexadecyltrimethylammonium bromide) as a catalyst to prepare a phenolic resin carbon skeleton with a three-dimensional network structure within a low-density composite material, such as... Figure 1 As shown in the figure, the low-density composite material has a preform-like structure with a large number of large pores that are difficult to be filled by pyrolytic carbon. After the introduction of phenolic resin, the large pores are divided into many three-dimensional small mesh structures (see the embodiments of the present invention). Figure 2 , Figure 3 and Figure 4The three-dimensional network structure of the phenolic resin carbon skeleton enhances the capillary force during the melting and infiltration process, which is beneficial to the infiltration of the melt. The introduced three-dimensional network structure of the phenolic resin carbon skeleton has a high specific surface area, which can act as an external carbon source to react with the infiltrated alloy melt, preventing melt loss. Simultaneously, due to the high specific surface area of ​​the carbon skeleton, more sites are provided, allowing the carbon skeleton to fully react with the melt, reducing metal residue and refining the grain size of the resulting ceramic product. In subsequent ablation tests, the small-sized ceramic particles reduce the thermal stress during ablation, improve the density and stability of the oxide film, and thus enhance the ablation resistance of the composite material. The introduced three-dimensional network structure of the phenolic resin carbon skeleton has advantages such as high hardness and strong support. By adjusting the carbonization temperature, the reactivity of the carbon skeleton can be further controlled to achieve precise control of the composite material structure after melting and infiltration. When the carbonization temperature is low (e.g., 900 ℃), the crystallinity of the carbon skeleton is low, with many defects and high reactivity. After fully reacting with the melt, the carbon skeleton is completely transformed into ceramic, which refines the grain size of the ceramic (see the embodiments of this invention). Figure 7 The role of carbonization is that when the carbonization temperature is high (e.g., 1900 ℃), carbon atoms rearrange, the crystallinity of the carbon skeleton increases, defects decrease, and reactivity weakens. After fully reacting with the melt, some residual carbon will still remain to form a uniformly interlocking structure of "hard carbon-ceramic-pyrolytic carbon" (see the embodiments of this invention). Figure 8 Compared to a pure ceramic matrix, this structure has two advantages: first, carbon is the only material that can operate in environments above 3000 °C, and its presence helps maintain the overall structural stability of the composite material; second, ceramics are brittle, and large ceramic blocks are prone to cracking and other defects, while the presence of a carbon structure helps improve toughness. Therefore, based on the requirements of the service environment, the activity of the carbon skeleton is controlled by adjusting the carbonization temperature, thereby controlling its consumption during the reaction and infiltration process, ultimately achieving precise control over the ratio of ceramic to carbon structure in the composite material. The three-dimensional network carbon skeleton structure prepared using resorcinol and formaldehyde has a controllable and adjustable network structure size, which can be adjusted by changing the amount of catalyst CTAB added. This allows for the construction of multi-scale three-dimensional network structures from nanoscale to microscale, meeting the application requirements of different preform structures, different melt characteristics, and different infiltration conditions. The raw materials used in this preparation process are inexpensive, the preparation process is simple and easy to scale up, and it is not limited by the shape and size of the composite material, showing strong industrial application prospects. Attached Figure Description

[0021] Figure 1 Scanning electron microscope image of a three-dimensional network carbon skeleton introduced into the low-density composite material in Embodiment 2 of the present invention;

[0022] Figure 2Scanning electron microscope image of a three-dimensional network carbon skeleton introduced into the low-density composite material in Embodiment 1 of the present invention;

[0023] Figure 3 Scanning electron microscope image of a three-dimensional network carbon skeleton introduced into the low-density composite material in Embodiment 2 of the present invention;

[0024] Figure 4 Scanning electron microscope image of a three-dimensional network carbon skeleton introduced into the low-density composite material in Example 3 of this invention;

[0025] Figure 5 Scanning electron microscope image of a three-dimensional network carbon skeleton introduced into the low-density composite material in Comparative Example 1 of this invention;

[0026] Figure 6 Scanning electron microscope image of the three-dimensional network carbon skeleton introduced into the low-density composite material in Comparative Example 2 of this invention;

[0027] Figure 7 Scanning electron microscope image of the composite material after reactive melting infiltration in Example 1 of this invention;

[0028] Figure 8 Scanning electron microscope image of the composite material after reactive melting infiltration in Example 2 of this invention;

[0029] Figure 9 Scanning electron microscope image of the composite material after reactive melting infiltration in Example 3 of this invention;

[0030] Figure 10 Scanning electron microscope image of the composite material after reactive melting infiltration in Comparative Example 1 of this invention;

[0031] Figure 11 Scanning electron microscope image of the composite material after reactive melting infiltration in Comparative Example 2 of this invention. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0033] Addressing the two major challenges faced in RMI technology, this invention introduces carbonaceous materials with high specific surface area and strong supporting structures into the composite material to achieve full reaction of the molten alloy, reduce residual metal, and refine the grain size of the resulting ceramic, thus solving the problems encountered in RMI technology. This invention introduces a carbon skeleton structure with three-dimensional network characteristics into a low-density carbon fiber preform composite material, effectively dividing the large pores within the composite material into a small network structure to assist in the preparation of high-performance ceramic-modified composite materials using reactive infiltration technology. The specific scheme of this invention is as follows.

[0034] The present invention discloses a method for preparing multi-scale three-dimensional network carbon skeleton structure-assisted composite materials, comprising the following steps:

[0035] Step 1: Preparation of precursor solution: Mix 5-8 g of resorcinol, 7-10 g of formaldehyde solution and 7-12 g of distilled water for 30-50 min to obtain a homogeneous solution. Then add 0.05-0.24 g of hexadecyltrimethylammonium bromide (CTAB) as a catalyst to the homogeneous solution and continue stirring for 20-40 min to obtain the precursor solution.

[0036] The formaldehyde solution had a mass concentration of 37 wt.%.

[0037] Step 2: Impregnation of low-density fiber preform composite material: Impregnate with fiber preforms having a density of 1.0-1.3 g / cm³. 3 The low-density fiber preform composite material (hereinafter referred to as low-density composite material) is immersed in the precursor solution prepared in step one, and then placed in a vacuum chamber and impregnated for 30-50 min under a pressure of 0.01-0.09 MPa; wherein, the low-density fiber preform includes one or more of the following composite materials: 2.5D needle-punched preform, 3D puncture preform, 3D yarn-wound structure preform, three-dimensional four-dimensional preform, and meshless structure preform; the low-density preform can be prepared using polyacrylonitrile-based carbon fiber, mesophase pitch-based carbon fiber, and SiC fiber, etc.

[0038] Step 3: Curing and Carbonization: The impregnated composite material obtained in Step 2 is placed in an oven at 60-100 ℃ for curing treatment for 24-36 h. Subsequently, the cured composite material is placed in a tube furnace at 900-1900 ℃ for heat treatment under a protective atmosphere for 2-4 h for carbonization. The tube furnace is filled with argon gas at a flow rate of 2-4 L / min. After carbonization, a phenolic resin carbon skeleton structure with a three-dimensional network structure is obtained in the low-density fiber preform composite material.

[0039] Step 4: Reactive infiltration treatment: The composite material with a three-dimensional carbon skeleton structure obtained in Step 3 is placed in a graphite crucible, and its surface is covered with alloy compound powder. The graphite crucible is then placed in a heat treatment furnace at 1800-2000 °C for 0.5-2 h to finally obtain the ceramic-modified composite material, namely the multi-scale three-dimensional network carbon skeleton structure-assisted composite material of this invention. The alloy compound powder includes one or both of ZrSi2 and HfSi2, and the heat treatment furnace is in an argon atmosphere with an argon flow rate of 8-10 L / min.

[0040] Example 1:

[0041] The preparation method of the multi-scale three-dimensional network carbon skeleton structure-assisted composite material in this embodiment includes the following steps:

[0042] Step 1: Mix 5 g of resorcinol, 7 g of formaldehyde solution and 7 g of distilled water for 30 min to obtain a homogeneous solution. Then add 0.05 g of hexadecyltrimethylammonium bromide as a catalyst to the homogeneous solution and continue stirring for 20 min to obtain a homogeneous solution.

[0043] Step 2: [The following appears to be a separate, unrelated sentence:] The density is 1.0 g / cm³ 3 The 3D low-density composite material with polyacrylonitrile-based carbon fiber as reinforcement was immersed in the precursor solution prepared in step one, and then placed in a vacuum chamber and impregnated for 30 min under a pressure of 0.01 MPa.

[0044] Step 3: The impregnated composite material obtained in Step 2 was placed in an oven at 60 ℃ for 36 h for curing. Subsequently, the cured composite material was placed in a tube furnace at 900 ℃ for 4 h for carbonization. The tube furnace was in an argon atmosphere with a flow rate of 2 L / min. After carbonization, a phenolic resin carbon skeleton structure with a three-dimensional network structure was prepared in the low-density fiber preform composite material. The pore structure of the prepared carbon skeleton was 20-25 μm.

[0045] Step 4: The composite material with a three-dimensional carbon skeleton structure obtained in Step 3 is placed in a graphite crucible, and HfSi2 powder is covered on its surface. Then, the graphite crucible is placed in a heat treatment furnace at 1800℃ for 2 h. The heat treatment furnace is in an argon atmosphere with a flow rate of 8 L / min. Finally, the ceramic-modified composite material is prepared.

[0046] The results show that the large pores inside the low-density C / C composite are filled by a three-dimensional network of carbon skeletons formed by stacked spherical particles (e.g., Figure 2 As shown), the pore size of the framework is 20-25 μm. After reactive infiltration, the pores in the low-density C / C are filled with ceramic particles. The ceramic particles have fine and uniform grain size. Figure 7 The black portion represents unreacted carbon, the gray portion represents the SiC phase, and the white portion represents the HfC phase. (4.2 MW / m) 2 After high-flow-rate ablation of oxyacetylene, the mass ablation rate and linear ablation rate are only -0.63 mg / s and 3.47 μm / s, respectively, demonstrating excellent ablation resistance.

[0047] Example 2:

[0048] The preparation method of the multi-scale three-dimensional network carbon skeleton structure-assisted composite material in this embodiment includes the following steps:

[0049] Step 1: Mix 8 g of resorcinol, 10 g of formaldehyde solution and 10 g of distilled water for 50 min to obtain a homogeneous solution. Then add 0.14 g of hexadecyltrimethylammonium bromide as a catalyst to the homogeneous solution and continue stirring for 40 min to obtain a homogeneous solution.

[0050] Step 2: [The following appears to be a separate, unrelated sentence:] The density is 1.3 g / cm³ 3 The 2.5D low-density composite material with polyacrylonitrile-based carbon fiber as reinforcement was immersed in the precursor solution prepared in step one, placed in a vacuum chamber, and impregnated for 50 min under a pressure of 0.09 MPa.

[0051] Step 3: The impregnated composite material obtained in Step 2 is placed in an oven at 100 ℃ for 24 h of curing treatment. Subsequently, the cured composite material is placed in a heat treatment furnace at 1900 ℃ for 2 h of carbonization. The tube furnace is filled with an argon atmosphere at a flow rate of 4 L / min. After carbonization, a phenolic resin carbon skeleton structure with a three-dimensional network structure is prepared in the low-density fiber preform composite material. The pore structure of the prepared carbon skeleton is 10-15 μm.

[0052] Step 4: The composite material with a three-dimensional carbon skeleton structure obtained in Step 3 is placed in a graphite crucible, and ZrSi2 powder is covered on its surface. Then, the graphite crucible is placed in a heat treatment furnace at 2000℃ for 0.5 h. The heat treatment furnace is in an argon atmosphere with a flow rate of 10 L / min. Finally, the ceramic-modified composite material is prepared.

[0053] The results show that the large pores inside the low-density C / C composite are filled by a three-dimensional network of carbon skeletons (such as...). Figure 3 As shown), the pore size of the skeleton is 10-15 μm; after reactive infiltration, the pores in the low-density C / C are filled with ceramic particles, which are fine-sized and uniformly distributed. Figure 8 The black portion represents unreacted carbon, the gray portion represents the SiC phase, and the white portion represents the ZrC phase. (4.2 MW / m) 2 After high-flow-rate ablation of oxyacetylene, the mass ablation rate and linear ablation rate are only -0.42 mg / s and 3.56 μm / s, respectively, demonstrating excellent ablation resistance.

[0054] Example 3:

[0055] The preparation method of the multi-scale three-dimensional network carbon skeleton structure-assisted composite material in this embodiment includes the following steps:

[0056] Step 1: Mix 7 g of resorcinol, 9 g of formaldehyde solution and 12 g of distilled water for 40 min to obtain a homogeneous solution. Then add 0.24 g of hexadecyltrimethylammonium bromide as a catalyst to the homogeneous solution and continue stirring for 30 min to obtain a homogeneous solution.

[0057] Step 2: [The following appears to be a separate, unrelated sentence:] The density is 1.2 g / cm³ 3 The 2.5D low-density composite material with polyacrylonitrile-based carbon fiber as reinforcement was immersed in the precursor solution prepared in step one, placed in a vacuum chamber, and impregnated for 40 min under a pressure of 0.05 MPa.

[0058] Step 3: The impregnated composite material obtained in Step 2 is placed in an oven at 80 ℃ for 34 h for curing. Then, the cured composite material is placed in a tube furnace at 1100 ℃ for 3 h for carbonization. The tube furnace is in an argon atmosphere with a flow rate of 3 L / min. After carbonization, a phenolic resin carbon skeleton structure with a three-dimensional network structure is prepared in the low-density fiber preform composite material. The pore structure of the prepared carbon skeleton is 5-8 μm.

[0059] Step 4: The composite material with a three-dimensional carbon skeleton structure obtained in Step 3 is placed in a graphite crucible, and ZrSi2 powder is covered on its surface. Then, the graphite crucible is placed in a heat treatment furnace at 1900 °C for 1 h. The heat treatment furnace is in an argon atmosphere with a flow rate of 9 L / min. Finally, the ceramic-modified composite material is prepared.

[0060] The results show that the large pores inside the low-density C / C composite are filled by a three-dimensional network of carbon skeletons (such as...). Figure 4 As shown), the pore size of the skeleton is 5-8 μm. After reactive infiltration, the pores in the low-density C / C are filled with ceramic particles. The ceramic particles have fine and uniform grain size. Figure 9 The black portion represents unreacted carbon, the gray portion represents the SiC phase, and the white portion represents the ZrC phase. (4.2 MW / m) 2 After high-flow-rate ablation of oxyacetylene, the mass ablation rate and linear ablation rate are only -0.48 mg / s and 3.77 μm / s, respectively, demonstrating excellent ablation resistance.

[0061] Comparative Example 1:

[0062] The preparation method of this comparative composite material includes the following steps:

[0063] Step 1: Mix 8 g of resorcinol, 10 g of formaldehyde solution and 18 g of distilled water for 50 min to obtain a homogeneous solution. Then add 0.14 g of hexadecyltrimethylammonium bromide as a catalyst to the homogeneous solution and continue stirring for 40 min to obtain a homogeneous solution.

[0064] Step 2: [The following appears to be a separate, unrelated sentence:] The density is 1.3 g / cm³ 3 The 2.5D low-density composite material with polyacrylonitrile-based carbon fiber as reinforcement was immersed in the precursor solution prepared in step one, placed in a vacuum chamber, and impregnated for 50 min under a pressure of 0.09 MPa.

[0065] Step 3: The impregnated composite material obtained in Step 2 is placed in an oven at 100 ℃ for 24 h of curing treatment. Then, the cured composite material is placed in a heat treatment furnace at 1900 ℃ for 2 h of heat treatment for carbonization. The tube furnace is in an argon atmosphere with a flow rate of 4 L / min.

[0066] Step 4: Place the composite material obtained in Step 3 into a graphite crucible, cover its surface with ZrSi2 powder, and then place the graphite crucible in a heat treatment furnace at 2000 ℃ for 0.5 h. The heat treatment furnace is in an argon atmosphere with a flow rate of 10 L / min. Finally, the ceramic-modified composite material is obtained.

[0067] Depend on Figure 5 It is known that a three-dimensional network carbon skeleton structure was not introduced into the composite material, resulting in a discontinuously distributed spherical carbon structure. Compared with the three-dimensional network structure, this structure failed to allow the melt to fully react with the introduced carbon during infiltration, resulting in a ceramic product with a continuous, large-scale distribution and many cracks and defects (such as...). Figure 10 ), after 4.2MW / m 2 After high-flow-rate ablation of oxyacetylene, the mass ablation rate and linear ablation rate were -1.76 mg / s and 4.98 μm / s, respectively, which showed poor ablation resistance compared to Example 2.

[0068] Comparative Example 2:

[0069] The preparation method of this comparative composite material includes the following steps:

[0070] Step 1: Mix 8 g of resorcinol, 10 g of formaldehyde solution and 25 g of distilled water for 50 min to obtain a homogeneous solution. Then add 0.14 g of hexadecyltrimethylammonium bromide as a catalyst to the homogeneous solution and continue stirring for 40 min to obtain a homogeneous solution.

[0071] Step 2: [The following appears to be a separate, unrelated sentence:] The density is 1.3 g / cm³3 The 2.5D low-density composite material with polyacrylonitrile-based carbon fiber as reinforcement was immersed in the precursor solution prepared in step one, placed in a vacuum chamber, and impregnated for 50 min under a pressure of 0.09 MPa.

[0072] Step 3: The impregnated composite material obtained in Step 2 is placed in an oven at 100 ℃ for 24 h of curing treatment. Then, the cured composite material is placed in a heat treatment furnace at 1900 ℃ for 2 h of heat treatment for carbonization. The tube furnace is in an argon atmosphere with a flow rate of 4 L / min.

[0073] Step 4: Place the composite material obtained in Step 3 into a graphite crucible, cover its surface with ZrSi2 powder, and then place the graphite crucible in a heat treatment furnace at 2000 ℃ for 0.5 h. The heat treatment furnace is in an argon atmosphere with a flow rate of 10 L / min. Finally, the ceramic-modified composite material is obtained.

[0074] Depend on Figure 6 It is known that a three-dimensional network carbon skeleton structure was not introduced into the composite material, resulting in a discontinuous distribution of large spherical carbon structures. Compared with the three-dimensional network structure, this structure failed to allow the melt to fully react with the introduced carbon during melting and infiltration, resulting in a ceramic product with a continuous, large-scale distribution and many cracks and defects (such as...). Figure 11 As shown), after 4.2 MW / m 2 After high-flow-rate ablation of oxyacetylene, the mass ablation rate and linear ablation rate were -1.56 mg / s and 4.23 μm / s, respectively, which showed poor ablation resistance compared to Example 2.

[0075] The specific embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a multi-scale three-dimensional network carbon skeleton structure-assisted composite material, characterized in that, include: The low-density fiber preform composite material is impregnated in a precursor solution to obtain the impregnated low-density fiber preform composite material. The precursor solution is a mixture of resorcinol, formaldehyde solution, distilled water and hexadecyltrimethylammonium bromide; The impregnated low-density fiber preform composite material is cured, and after curing, it is finally carbonized in a protective atmosphere to form a phenolic resin carbon skeleton structure with a three-dimensional network structure in the low-density fiber preform composite material. The low-density fiber preform composite material that has undergone carbonization is subjected to reactive melt infiltration treatment to obtain the multi-scale three-dimensional network carbon skeleton structure assisted composite material. In the precursor solution, the mass ratio of resorcinol, formaldehyde solution, distilled water and hexadecyltrimethylammonium bromide is (5-8):(7-10):(7-12):(0.05-0.24), and the mass concentration of the formaldehyde solution is 37 wt.%. After curing, when performing the final carbonization treatment in a protective atmosphere, carbonize at 900-1900 ℃ for 2-4 h; When performing reactive melting treatment on the low-density fiber preform composite material that has undergone carbonization, the surface of the low-density fiber preform composite material that has undergone carbonization is covered with alloy compound powder, and then treated at 1800-2000 °C for 0.5-2 h in a protective atmosphere to obtain the multi-scale three-dimensional network carbon skeleton structure assisted composite material. The alloy compound powder includes at least one of ZrSi2 and HfSi2.

2. The method for preparing a multi-scale three-dimensional network carbon skeleton structure-assisted composite material according to claim 1, characterized in that, The density of the low-density fiber preform composite material is 1.0-1.3 g / cm³. 3 .

3. The method for preparing a multi-scale three-dimensional network carbon skeleton structure-assisted composite material according to claim 1, characterized in that, The low-density fiber preform composite material is a composite material made of one or more of the following: 2.5D needle-punched preform, 3D punctured preform, 3D yarn-wound structure preform, three-dimensional four-way preform, and meshless structure preform. The fibers in the low-density fiber preform composite material are one or more of polyacrylonitrile-based carbon fibers, mesophase pitch-based carbon fibers, and SiC fibers.

4. The method for preparing a multi-scale three-dimensional network carbon skeleton structure-assisted composite material according to claim 1, characterized in that, When impregnating the low-density fiber preform composite material in the precursor solution, the impregnation is carried out at a pressure of 0.01-0.09 MPa for 30-50 min.

5. The method for preparing a multi-scale three-dimensional network carbon skeleton structure-assisted composite material according to claim 1, characterized in that, When curing the impregnated low-density fiber preform composite material, bake it at 60-100℃ for 24-36 h.

6. A multi-scale three-dimensional network carbon skeleton structure-assisted composite material, characterized in that, The multi-scale three-dimensional network carbon skeleton structure-assisted composite material is prepared by the preparation method described in any one of claims 1-5.

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