A multi-layer antioxidant carbon aerogel composite material and a preparation method and application thereof

Abstract

This invention relates to a multilayer antioxidant carbon aerogel composite material, its preparation method, and its application, belonging to the technical field of heat insulation materials. It aims to solve at least one of the following problems in existing carbon aerogel composite materials: poor antioxidant performance, poor ablation resistance, and easy cracking and peeling of the coating under thermal shock conditions due to the mismatch in thermal expansion coefficients between the ceramic coating and the carbon aerogel composite matrix. The composite material of this invention uses thermosetting phenolic resin as a binder for the ablation-resistant putty, significantly enhancing the interfacial bonding strength between the ceramic particles and the carbon aerogel composite matrix, effectively inhibiting cracking and peeling of the coating under thermal coupling. Simultaneously, utilizing the synergistic effect of the various raw materials at high temperatures, a dense composite barrier of ceramic and glass phases is generated in situ within the coating, possessing high-temperature melting and sealing functions, blocking oxygen penetration, and significantly improving the protective capability of the composite material under extreme oxidative ablation environments.

Description

Technical Field

[0001] This invention relates to the field of heat insulation materials technology, and in particular to a multilayer antioxidant carbon aerogel composite material, its preparation method and application. Background Technology

[0002] Carbon aerogel composites, with their low density, low thermal conductivity, high strength, and excellent structural stability in extreme environments up to 2000°C, have become indispensable materials in key fields such as aerospace propulsion systems and spacecraft thermal protection systems. Their superior mechanical properties and high-temperature stability make them one of the most promising candidate materials for ultra-high temperature thermal protection structures.

[0003] However, carbon aerogel composites are extremely sensitive to oxidizing environments, especially in oxygen-containing atmospheres above 500°C, where they are prone to oxidative weight loss, leading to microstructural damage and decreased mechanical properties, severely restricting their long-term reliability as high-temperature structural components. Therefore, how to effectively improve the oxidation and ablation resistance of carbon aerogel composites under harsh thermal oxidizing environments remains a core scientific problem and technological bottleneck for achieving their ultra-high temperature long-term service.

[0004] To overcome the aforementioned problems, researchers have extensively explored methods for matrix modification or surface coating protection of ultra-high temperature ceramics (such as silicon powder, ZrB2, and HfC). Ceramic materials, with their excellent thermal stability, high melting point, and good oxidation resistance, can exert a synergistic reinforcing effect when combined with carbon aerogel composites, significantly improving the oxidation and ablation resistance of the composites. However, existing ceramic coating systems generally suffer from high intrinsic brittleness and a mismatch in thermal expansion coefficients with the carbon aerogel composite matrix. This leads to easy crack initiation and even spalling failure of the coating under thermal shock conditions, making it difficult to meet the requirements for long-life and high-reliability use in extreme environments. Summary of the Invention

[0005] Based on the above analysis, the present invention aims to provide a multilayer antioxidant carbon aerogel composite material, its preparation method and application, to solve at least one of the following problems in existing carbon aerogel composite materials: poor antioxidant performance, poor ablation resistance, and easy cracking and peeling of the coating under thermal shock conditions caused by the mismatch of the thermal expansion coefficients between the ceramic coating and the carbon aerogel composite material matrix.

[0006] In a first aspect, the present invention provides a multilayer antioxidant carbon aerogel composite material, wherein the composite material comprises, from top to bottom, a multi-component ceramic matrix anti-ablation coating, an organosilicon resin transition layer and a carbon aerogel composite material layer; The raw materials for the multi-component ceramic-based ablation-resistant coating include zirconium boride, silicon powder, molybdenum silicide, low-melting-point glass powder, and thermosetting phenolic resin.

[0007] Furthermore, the mass ratio of zirconium boride, silicon powder, molybdenum silicide, low-melting-point glass powder, and thermosetting phenolic resin is 1~3:1~3:0.5~2:1.5~5:1~3.

[0008] Furthermore, the raw material for the organosilicon resin transition layer includes organosilicon resin, which includes one or more of methyl silicone resin, phenyl silicone resin, and methylphenyl silicone resin.

[0009] Secondly, the present invention provides a method for preparing the aforementioned multilayer antioxidant carbon aerogel composite material, comprising the following steps: (1) Zirconium boride, silicon powder, molybdenum silicide and low melting point glass powder are mixed and ball-milled to obtain mixed powder. Then thermosetting phenolic resin is added and stirred in a water bath to obtain ceramic-based anti-ablation putty. (2) Dissolve the organosilicon resin in an organic solvent and add a catalyst, stir to obtain an organosilicon resin solution; (3) The surface of the carbon aerogel composite material is polished, cleaned and dried to obtain the surface-treated carbon aerogel composite material; (4) The silicone resin solution described in step (2) is coated on the surface of the carbon aerogel composite material after surface treatment to form a silicone resin transition layer; (5) The ceramic-based anti-ablation putty described in step (1) is coated on the surface of the silicone resin transition layer and subjected to gradient curing treatment to obtain the multilayer anti-oxidation carbon aerogel composite material.

[0010] Furthermore, in step (2), the mass fraction of the organosilicon resin in the organosilicon resin solution is 30-60%, and the mass fraction of the catalyst is 0.2-0.8%.

[0011] Furthermore, in step (2), the catalyst is tetramethylammonium hydroxide, and the organic solvent includes one or more of anhydrous ethanol, toluene, xylene, isopropanol, and ethylene glycol.

[0012] Furthermore, in step (4), the coating amount of the silicone resin solution is 0.05~0.1 g / cm³. 2 .

[0013] Furthermore, in step (5), the coating amount of the ceramic-based anti-ablation putty is 0.08~0.2 g / cm³. 2 .

[0014] Furthermore, in step (5), the gradient curing process is to maintain the temperature at 80~100℃ for 8~15h and at 130~180℃ for 5~10h.

[0015] Thirdly, the present invention provides an application of the aforementioned multilayer antioxidant carbon aerogel composite material in high-temperature antioxidant and / or ablation-resistant protective materials.

[0016] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: 1. The composite material of this invention uses thermosetting phenolic resin as the binder for the ablation-resistant putty, which significantly enhances the interfacial bonding strength between ceramic particles and the carbon aerogel composite matrix, effectively suppressing cracking and peeling of the coating under thermo-coupling effects. Simultaneously, by utilizing the high-temperature synergistic effect of ZrB2, silica powder, MoSi2, low-melting-point glass powder, and thermosetting phenolic resin, a dense composite barrier of ceramic and glass phases is generated in situ within the coating. This barrier has a high-temperature melting and sealing function, preventing oxygen penetration and significantly improving the composite material's protective capability under extreme oxidative ablation environments.

[0017] 2. In this invention, silicone resin is used as the transition layer material. The moderate thermal expansion characteristics of silicone resin effectively alleviate the interfacial stress concentration caused by the difference in thermal expansion coefficients between the ceramic coating and the carbon aerogel composite matrix, preventing delamination failure of the coating under thermal shock conditions. Furthermore, silicone resin can partially penetrate the pores on the matrix surface and can be in-situ transformed into an inorganic ceramic phase with a Si-OC structure during high-temperature pyrolysis, further enhancing the mechanical interlocking effect between the transition coating and the matrix, and improving the overall interfacial bonding performance and thermal compatibility of the coating. This invention achieves synergistic optimization of interfacial thermal compatibility control and high-temperature self-healing protection through the synergistic design of the silicone resin transition layer and the multi-component ceramic ablation-resistant layer.

[0018] 3. The preparation method of the present invention significantly improves the performance and stability of multilayer antioxidant carbon aerogel composite materials through reasonable raw material selection and precise preparation process control, giving them good protective capabilities in extreme oxidative ablation environments and making them of significant practical application value.

[0019] 4. In the preparation method of the present invention, a specific amount of silicone resin transition layer is selected. When the amount of coating is too low, it is difficult to form a continuous and effective transition layer on the surface of the carbon aerogel composite material, which leads to the failure to effectively alleviate the thermal expansion mismatch problem. At the same time, the penetration depth is insufficient, the interfacial mechanical interlocking effect is weakened, and it is easy to debond or peel off during thermal shock. When the amount of coating is too high, it is easy to form an excessively thick resin enrichment layer on the surface, which will produce a large shrinkage and gas release during high-temperature pyrolysis, thereby introducing pores and cracks, reducing interfacial stability and coating adhesion.

[0020] 5. The preparation method of the present invention selects a specific coating amount of anti-ablation putty. When the coating amount is too low, the coating thickness is insufficient, making it difficult to form a continuous and dense anti-oxidation barrier, which makes it easy for oxygen to penetrate into the carbon aerogel composite matrix, thereby reducing the anti-oxidation performance of the material. When the coating amount is too high, the coating thickness is too large, which is prone to generating large thermal stress during thermal cycling and causing cracking or peeling. At the same time, the gas inside the thick coating is not easy to escape, which is easy to form defect structure, and may cause glass phase flow instability at high temperature, reducing the overall structural stability of the coating.

[0021] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0022] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0023] Figure 1 Thermogravimetric curve of the ceramic-based anti-ablation putty prepared in Example 1 of this invention after curing; Figure 2 The surface morphology of the multilayer antioxidant carbon aerogel composite material prepared in Example 1 of the present invention before oxyacetylene ablation test at 1800℃ for 300s. Figure 3 The surface morphology of the multilayer antioxidant carbon aerogel composite material prepared in Example 1 of the present invention after oxyacetylene ablation test at 1800℃ for 300s. Detailed Implementation

[0024] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0025] To improve the service stability of low-density carbon aerogel composites under high-temperature oxidizing environments, existing technologies disclose the use of ultra-high temperature ceramics as coatings to enhance the oxidation resistance of carbon aerogel composites. However, due to the significant difference in thermal expansion coefficients and interfacial bonding defects between the carbon aerogel composite matrix and the ceramic coating, the coating is prone to cracking and peeling during thermal cycling or ablation, leading to protective failure.

[0026] A specific embodiment of the present invention discloses a multilayer antioxidant carbon aerogel composite material, wherein the composite material comprises, from top to bottom, a multi-component ceramic matrix anti-ablation coating, an organosilicon resin transition layer, and a carbon aerogel composite material layer; The raw materials for the multi-component ceramic-based ablation-resistant coating include zirconium boride (ZrB2), silicon powder, molybdenum silicide (MoSi2), low-melting-point glass powder, and thermosetting phenolic resin.

[0027] Compared with existing technologies, the composite material of this invention uses thermosetting phenolic resin as the binder for the ablation-resistant putty, which significantly enhances the interfacial bonding strength between ceramic particles and the carbon aerogel composite matrix, effectively suppressing cracking and peeling of the coating under thermo-coupling effects. Simultaneously, by utilizing the high-temperature synergistic effect of ZrB2, silica powder, MoSi2, low-melting-point glass powder, and thermosetting phenolic resin, a dense composite barrier of ceramic and glass phases is generated in situ within the coating. This barrier possesses high-temperature melting and sealing capabilities, preventing oxygen penetration and significantly improving the composite material's protective ability under extreme oxidative ablation environments.

[0028] Specifically, the mass ratio of zirconium boride, silicon powder, molybdenum silicide, low-melting-point glass powder, and thermosetting phenolic resin is 1~3 (e.g., 1, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, 3): 1~3 (e.g., 1, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, 3): 0.5~2 (e.g., 0.5, 0.7, 0.9, ...). 1.0, 1.2, 1.4, 1.6, 1.8, 2): 1.5~5 (e.g., 1.5, 1.7, 1.9, 2.0, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, 4.4, 4.6, 4.8, 5): 1~3 (e.g., 1, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, 3).

[0029] Preferably, the mass ratio of zirconium boride, silicon powder, molybdenum silicide, low-melting-point glass powder, and thermosetting phenolic resin is 2:2:1:3:2.

[0030] It should be noted that the multi-component ceramic coating of this invention uses ZrB2 (1-3) as the core component of the ultra-high temperature ceramic skeleton, which has a high melting point (~3200℃) and good thermochemical stability. In a high-temperature oxygen-containing environment, ZrB2 preferentially oxidizes to form ZrO2 and B2O3. ZrO2 forms a high-melting-point skeleton, giving the coating structural strength; B2O3 melts and fills the pores, forming a dense barrier layer. When the proportion of ZrB2 is too high, due to its high intrinsic brittleness and high coefficient of thermal expansion, it will aggravate the mismatch between the coating and the substrate, making it prone to cracking during thermal shock; when the proportion of ZrB2 is too low, the high-melting-point ceramic skeleton in the coating is insufficient, making it difficult to maintain the structural integrity under extreme high-temperature environments.

[0031] Silica powder (1-3) serves as a reinforcing phase in the antioxidant framework. After high-temperature oxidation, it forms a SiO2 glass film with an extremely low oxygen diffusion coefficient, effectively preventing oxygen atoms from penetrating inward. Simultaneously, the addition of silica powder can adjust the coating's coefficient of thermal expansion, alleviating thermal stress. If the silica powder content is too high, the formation of SiO2 under ultra-high temperature conditions will cause the coating's protective mechanism to become overly reliant on the SiO2 glass phase, leading to a decrease in protective capability during prolonged ablation. Conversely, if the silica powder content is too low, the SiO2 glass phase generated during high-temperature oxidation is insufficient, making it difficult to form a continuous and dense oxygen barrier layer. This allows oxygen to easily diffuse inward, thus reducing the coating's antioxidant performance.

[0032] The introduction of MoSi2 (0.5~2) can significantly improve the infrared emissivity of the coating surface, enhancing its heat dissipation capacity at high temperatures. This allows the coating to carry away heat through radiation, thereby reducing the surface temperature and mitigating the impact of heat flow on the substrate. However, excessive MoSi2 ratios can lead to the formation of MoO3, creating gas escape channels and compromising the coating's density. Conversely, insufficient MoSi2 ratios result in relatively low surface emissivity, hindering its ability to reduce surface temperature.

[0033] Low-melting-point glass powder (1.5~5%) acts as a high-temperature sealing agent. It melts first at relatively low temperatures (<1000℃), filling any initial cracks and pores in the coating and blocking the rapid path of early oxidation. It also ensures the coating maintains a certain degree of fluidity at different stages, guaranteeing continuous repair capabilities. If the proportion of low-melting-point glass powder is too high, the overall melting point of the coating will be low, resulting in high fluidity at high temperatures, uneven coating thickness, or even loss of coating, reducing the coating's temperature resistance limit and rendering it ineffective. Conversely, if the proportion is too low, the high-temperature repair capability will be poor.

[0034] Thermosetting phenolic resins (1-3) serve as binders and carbon-forming precursors. After high-temperature pyrolysis, they transform into amorphous carbon. In the initial stages of oxidation, carbon is preferentially consumed, acting as a "sacrificial anode" to inhibit corrosion. An excessively high proportion leads to excessive carbon content in the coating, resulting in severe weight loss under high-temperature oxidation conditions, accompanied by drastic volume shrinkage and gas escape, thus compromising coating integrity. An excessively low proportion results in insufficient adhesion, low coating strength, and a tendency for powdering during coating and curing.

[0035] Preferably, the viscosity (30°C) of the thermosetting phenolic resin is 3-10 Pa·s, for example, 3 Pa·s, 3.5 Pa·s, 4 Pa·s, 4.5 Pa·s, 5 Pa·s, 5.5 Pa·s, 6 Pa·s, 6.5 Pa·s, 7 Pa·s, 7.5 Pa·s, 8 Pa·s, 8.5 Pa·s, 9 Pa·s, 9.5 Pa·s, and 10 Pa·s.

[0036] Specifically, the raw material for the organosilicon resin transition layer includes organosilicon resin, which includes one or more of methyl silicone resin, phenyl silicone resin, and methylphenyl silicone resin.

[0037] In this invention, silicone resin is used as the transition layer material. The moderate thermal expansion characteristics of silicone resin effectively alleviate the interfacial stress concentration caused by the difference in thermal expansion coefficients between the ceramic coating and the carbon aerogel composite matrix, preventing delamination failure of the coating under thermal shock conditions. Furthermore, silicone resin can partially penetrate the pores of the matrix surface and can be in-situ transformed into an inorganic ceramic phase with a Si-OC structure during high-temperature pyrolysis, further enhancing the mechanical interlocking effect between the transition coating and the matrix, and improving the overall interfacial bonding performance and thermal compatibility of the coating. This invention achieves synergistic optimization of interfacial thermal compatibility control and high-temperature self-healing protection through the synergistic design of the silicone resin transition layer and the multi-component ceramic ablation-resistant layer.

[0038] It should be noted that the organosilicon resin of the present invention can penetrate into the pores on the surface of the carbon aerogel composite matrix and can be transformed in situ into an inorganic ceramic phase with a Si-OC structure during high-temperature pyrolysis, thereby enhancing the mechanical interlocking effect between the transition coating and the matrix, thus improving the interfacial bonding and alleviating the thermal expansion mismatch between the ceramic coating and the matrix.

[0039] The carbon aerogel composite materials described in this invention are all made from commercially available raw materials or prepared using existing methods.

[0040] For example, the carbon aerogel composite material is prepared by the following method: S1: Mix phenolic resin, curing agent and organic solvent evenly to obtain carbonaceous precursor solution; S2: Place the carbon fiber preform in a mold, inject the carbon precursor solution into the mold, seal it, and carry out a sol-gel reaction; S3: Remove the wet gel from the mold and dry it under normal pressure; S4: The gel dried in S3 is subjected to high-temperature pyrolysis and cooled to room temperature to obtain the carbon aerogel composite material.

[0041] Specifically, in S1, the mass fraction of phenolic resin in the carbonaceous precursor solution is 20-60%, for example, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, and the amount of curing agent added is 5-15% of the phenolic resin, for example, 5%, 7%, 9%, 11%, 13%, 15%.

[0042] Preferably, the curing agent includes one or more of urea, ammonia, and hexamethylenetetramine; the organic solvent includes one or more of anhydrous ethanol, isopropanol, ethylene glycol, and n-butanol.

[0043] Specifically, in S2, the carbon fiber preform is carbon fiber cloth and / or mesh.

[0044] Preferably, the carbon fiber preform has dimensions of 220mm × 220mm and a thickness of 10mm.

[0045] Specifically, in S2, the temperature of the sol-gel reaction is 80~130℃, for example, 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃, and the reaction time is 12~36h, for example, 12h, 14h, 16h, 18h, 20h, 22h, 24h, 26h, 28h, 30h, 32h, 34h, 36h.

[0046] Specifically, in S3, the drying temperature is 80~120℃, for example, 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, and the drying time is 12~24h, for example, 12h, 14h, 16h, 18h, 20h, 22h, 24h.

[0047] Specifically, in S4, the high-temperature pyrolysis involves raising the temperature from 25°C to 200-300°C (e.g., 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C) at a rate of 2-5°C / min (2°C / min, 2.5°C / min, 3°C / min, 3.5°C / min, 4°C / min, 4.5°C / min, 5°C / min), and then raising the temperature at a rate of 1-2°C / min (1°C / min, 1.1°C / min, 1.2°C / min, 1.3°C / min, 1.4°C / min, 1.5°C / min, 1.6°C / min, 1.7°C / min, 1.8°C / min). The temperature is increased at a rate of 1.9℃ / min or 2℃ / min from 200~300℃ (e.g., 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃) to 700~1000℃ (700℃, 720℃, 740℃, 760℃, 780℃, 800℃, 820℃, 840℃, 860℃, 880℃, 900℃, 920℃, 940℃, 960℃, 980℃, 1000℃), and held for 1~3h (e.g., 1h, 1.2h, 1.4h, 1.6h, 1.8h, 2.0h, 2.2h, 2.4h, 2.6h, 2.8h, 3h).

[0048] Another specific embodiment of the present invention discloses a method for preparing the above-mentioned multilayer antioxidant carbon aerogel composite material, comprising the following steps: (1) Zirconium boride, silicon powder, molybdenum silicide and low melting point glass powder are mixed and ball-milled to obtain mixed powder. Then thermosetting phenolic resin is added and stirred in a water bath to obtain ceramic-based anti-ablation putty. (2) Dissolve the organosilicon resin in an organic solvent and add a catalyst, stir to obtain an organosilicon resin solution; (3) The surface of the carbon aerogel composite material is polished, cleaned and dried to obtain the surface-treated carbon aerogel composite material; (4) The silicone resin solution described in step (2) is coated on the surface of the carbon aerogel composite material after surface treatment to form a silicone resin transition layer; (5) The ceramic-based anti-ablation putty described in step (1) is coated on the surface of the silicone resin transition layer and subjected to gradient curing treatment to obtain the multilayer anti-oxidation carbon aerogel composite material.

[0049] The preparation method of this invention significantly improves the performance and stability of multilayer antioxidant carbon aerogel composite materials through reasonable raw material selection and precise preparation process control, giving them good protective capabilities in extreme oxidative ablation environments and making them of significant practical application value. Specifically, in step (1), the temperature of the water bath is 30~60℃, for example, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, the stirring speed is 800~2000r / min, for example, 800r / min, 900r / min, 1000r / min, 1100r / min, 1200r / min, 1300r / min, 1400r / min, 1500r / min, 1600r / min, 1700r / min, 1800r / min, 1900r / min, 2000r / min, and the stirring time is 3~8h, for example, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h.

[0050] Specifically, in step (2), the mass fraction of the organosilicon resin in the organosilicon resin solution is 30-60%, for example, 30%, 35%, 40%, 45%, 50%, 55%, 60%, and the mass fraction of the catalyst is 0.2-0.8%, for example, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%.

[0051] Preferably, the catalyst is tetramethylammonium hydroxide (TMAH), and the organic solvent includes one or more of anhydrous ethanol, toluene, xylene, isopropanol, and ethylene glycol.

[0052] Specifically, in step (3), the cleaning is performed in an organic solvent. Preferably, the organic solvent includes one or more of anhydrous ethanol, isopropanol, acetone, and ethylene glycol. More preferably, the drying temperature is 90~120℃, for example, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, and the time is 8~12h, for example, 8h, 8.5h, 9h, 9.5h, 10h, 10.5h, 11h, 11.5h, 12h.

[0053] Specifically, in step (4), the coating amount of the silicone resin solution is 0.05~0.1 g / cm³. 2 For example, 0.05 g / cm 2 0.06g / cm 2 0.07g / cm 2 0.08g / cm 2 0.09g / cm 2 0.1g / cm 2 Preferably, the coating amount is 0.08 g / cm³. 2 .

[0054] It should be noted that the coating amount of the silicone resin transition layer has a significant impact on the interfacial bonding performance. When the coating amount is too low, it is difficult to form a continuous and effective transition layer on the surface of the carbon aerogel composite material, resulting in the failure to effectively alleviate the thermal expansion mismatch problem. At the same time, insufficient penetration depth weakens the interfacial mechanical interlocking effect, making it prone to debonding or peeling during thermal shock. When the coating amount is too high, an excessively thick resin-rich layer is easily formed on the surface, which will produce greater shrinkage and gas release during high-temperature pyrolysis, thereby introducing pores and cracks, reducing interfacial stability and coating adhesion.

[0055] Specifically, in step (5), the coating amount of the ceramic-based anti-ablation putty is 0.08~0.2 g / cm³. 2 For example, 0.08 g / cm³ 2 0.09g / cm 2 0.10 g / cm 2 0.11 g / cm 2 0.12g / cm 2 0.13g / cm 2 0.14 g / cm 2 0.15g / cm 2 0.16g / cm 2 0.17g / cm 2 0.18g / cm 2 0.19g / cm 2 0.2g / cm 2 .

[0056] It should be noted that the amount of ablation-resistant putty applied has a significant impact on the protective performance of the coating. When the application amount is too low, the coating thickness is insufficient, making it difficult to form a continuous and dense antioxidant barrier. This allows oxygen to easily penetrate into the carbon aerogel composite matrix, thereby reducing the material's antioxidant performance. When the application amount is too high, the coating thickness is too large, which can easily generate significant thermal stress during thermal cycling, leading to cracking or peeling. At the same time, the gas inside the thick coating is not easily discharged, which can easily form defect structures and may cause glass phase flow instability at high temperatures, reducing the overall structural stability of the coating.

[0057] Specifically, in step (5), the gradient curing process involves maintaining the temperature at 80~100℃ (e.g., 80℃, 82℃, 84℃, 86℃, 88℃, 90℃, 92℃, 94℃, 96℃, 98℃, 100℃) for 8~15h (e.g., 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h), and at 130~180℃ (e.g., 130℃, 1...). The curing temperature gradient is maintained at 35℃, 140℃, 145℃, 150℃, 155℃, 160℃, 165℃, 170℃, 175℃, and 180℃ for 5 to 10 hours (e.g., 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, and 10h). Preferably, the curing temperature gradient is maintained at 80℃ for 12 hours and at 150℃ for 8 hours.

[0058] It should be noted that the present invention employs a gradient curing process, which pre-cures the coating system at a low temperature stage to gradually release the solvent and small molecules, avoiding the formation of pores or bubbling defects due to internal gas retention; then, it performs complete curing at a higher temperature to fully cross-link the resin system and form a stable and dense structure, thereby improving the overall density and interfacial bonding strength of the coating.

[0059] Another embodiment of the present invention discloses the application of the above-mentioned multilayer antioxidant carbon aerogel composite material in high-temperature antioxidant and / or ablation-resistant protective materials.

[0060] The technical solution of the present invention will be further explained below with reference to specific embodiments. The manufacturers and grades of some raw materials used in the present invention are listed below; however, the present invention is not limited to these grades and other grades may also be used. The manufacturer of the low-melting-point glass powder is Anmi Micro-Nano New Materials Co., Ltd., and the grade is D290 low-melting-point glass powder.

[0061] Example 1 This embodiment provides a multilayer antioxidant carbon aerogel composite material, which, from top to bottom, comprises a multi-component ceramic matrix anti-ablation coating, an organosilicon resin transition layer, and a carbon aerogel composite material layer. The preparation method of the multilayer antioxidant carbon aerogel composite material in this embodiment is as follows: (1) Zirconium boride, silicon powder, molybdenum silicide and low melting point glass powder are mixed and ball-milled in a ball mill jar with a ball-to-material ratio of 4:1. The mixture is ball-milled at 500 rpm for 3 hours to obtain a mixed powder. Then, thermosetting phenolic resin is added as a binder and the mixture is placed in a 50°C water bath and stirred for 5 hours at a stirring rate of 1400 r / min to obtain ceramic-based anti-ablation putty. The mass ratio of zirconium boride, silicon powder, molybdenum silicide, low-melting-point glass powder, and thermosetting phenolic resin (viscosity of 7 Pa·s at 30℃) is 2:2:1:3:2.

[0062] (2) Dissolve the organosilicon resin in an organic solvent, add the catalyst, and stir at room temperature to obtain an organosilicon resin solution; The organosilicon resin solution contains 50% methyl silicone resin (manufactured by Anhui Aiyota Silicone Oil Co., Ltd., brand name IOTA 6070) by mass, the catalyst is tetramethylammonium hydroxide (TMAH) and the amount of catalyst used is 0.5% of the mass of the organosilicon resin solution, and the organic solvent is anhydrous ethanol. (3) The surface of the carbon aerogel composite material is polished, cleaned and dried to obtain the surface-treated carbon aerogel composite material; The cleaning is carried out in anhydrous ethanol, and the drying temperature is 105°C for 10 hours. (4) The silicone resin solution described in step (2) is coated on the surface of the carbon aerogel composite material after surface treatment to form a silicone resin transition layer; The coating amount of silicone resin is 0.08 g / cm³. 2 ; (5) The ceramic-based anti-ablation putty described in step (1) is coated on the surface of the silicone resin transition layer and subjected to gradient curing treatment to obtain the multilayer antioxidant carbon aerogel composite material. The coating amount of the ablation-resistant putty is 0.15 g / cm³. 2 The gradient curing temperature is 80℃ for 12 hours and 150℃ for 8 hours.

[0063] The preparation method of the carbon aerogel composite material in this embodiment is as follows: S1: Phenolic resin, hexamethylenetetramine curing agent, and isopropanol organic solvent are mechanically stirred at 45°C for 5 hours to obtain a carbonaceous precursor solution; wherein, in the carbonaceous precursor solution, the mass fraction of phenolic resin is 40%, and the amount of curing agent added is 10% of the phenolic resin; S2: A material with dimensions of 220 mm × 220 mm × 10 mm and a density of 0.4 g / cm³. 3 The needle-punched and woven carbon fiber preform was placed in a 220 mm × 220 mm × 10 mm mold, and the carbon precursor solution was injected into the mold. After sealing, the sol-gel reaction was carried out at 90°C for 24 h. S3: After cooling to room temperature, remove the wet gel from the mold and dry it at 80°C under normal pressure for 12 hours; S4: The gel dried in S3 is subjected to high-temperature pyrolysis in a carbonization furnace under an inert atmosphere. The high-temperature pyrolysis is carried out by heating from 25°C to 300°C at a heating rate of 2°C / min, and then heating from 300°C to 800°C at a heating rate of 1°C / min, holding at the temperature for 2 hours, and then cooling to room temperature to obtain the carbon aerogel composite material.

[0064] The thermogravimetric curve of the ceramic-based ablation-resistant putty prepared in this embodiment after curing was tested, as follows: Figure 1 As shown in the figure, the thermogravimetric analysis results under air atmosphere indicate that the ceramic-based anti-ablation putty exhibits obvious staged mass changes during heating. Within the range of room temperature to 200℃, the mass remains basically stable, with only a small amount of volatile components released. Slight weight loss occurs near 200~600℃, corresponding to the pyrolysis of phenolic resin. When the temperature exceeds 600℃, the curve changes from weight loss to weight gain, indicating that the ceramic components in the system undergo oxidation in air, generating oxides such as SiO2 and ZrO2. These oxidation products can form a dense protective layer on the material surface, thereby inhibiting further diffusion of oxygen in the material, demonstrating the coating's excellent high-temperature oxidation and ablation resistance potential.

[0065] The surface morphology of the multilayer antioxidant carbon aerogel composite material prepared in this embodiment before the oxyacetylene ablation test at 1800℃ for 300 s is as follows. Figure 2 As shown, the surface morphology after 300 seconds of evaluation is as follows. Figure 3 As shown.

[0066] Figure 2 and Figure 3 In comparison, the image of the material after ablation shows that a continuous and dense molten layer has formed on its surface, with an intact overall structure and no obvious peeling or through cracks. This molten layer originates from the oxidation of low-melting-point glass phase and components such as silicon carbide, zirconium boride, and silicides at high temperatures. During ablation, this layer softens or even melts, flowing and filling pores and defects on the surface, forming a dense protective layer upon cooling. This process effectively prevents oxygen from diffusing into the interior and reduces the rate of further ablation, demonstrating excellent self-healing ability and ablation resistance.

[0067] Example 2 The multilayer antioxidant carbon aerogel composite material and its preparation method in this embodiment are similar to those in Example 1, except that the mass ratio of zirconium boride, silicon powder, molybdenum silicide, low melting point glass powder and thermosetting phenolic resin (viscosity of 3 Pa·s at 30°C) is 3:3:0.5:1.5:1.

[0068] The multilayer antioxidant carbon aerogel composite material prepared in this embodiment was tested in Example 1, and the results were basically the same. Due to space limitations, they will not be listed one by one.

[0069] Example 3 The multilayer antioxidant carbon aerogel composite material and its preparation method in this embodiment are similar to those in Example 1, except that the mass ratio of zirconium boride, silicon powder, molybdenum silicide, low melting point glass powder and thermosetting phenolic resin (viscosity of 10 Pa·s at 30°C) is 1:1:2:5:3.

[0070] The multilayer antioxidant carbon aerogel composite material prepared in this embodiment was tested in Example 1, and the results were basically the same. Due to space limitations, they will not be listed one by one.

[0071] Example 4 The multilayer antioxidant carbon aerogel composite material and its preparation method in this embodiment are similar to those in Example 1, except that in step (2), the mass fraction of the organosilicon resin in the organosilicon resin solution is 30%.

[0072] The multilayer antioxidant carbon aerogel composite material prepared in this embodiment was tested in Example 1, and the results were basically the same. Due to space limitations, they will not be listed one by one.

[0073] Example 5 The multilayer antioxidant carbon aerogel composite material and its preparation method in this embodiment are similar to those in Example 1, except that in step (2), the mass fraction of the organosilicon resin in the organosilicon resin solution is 60%.

[0074] The multilayer antioxidant carbon aerogel composite material prepared in this embodiment was tested in Example 1, and the results were basically the same. Due to space limitations, they will not be listed one by one.

[0075] Example 6 The multilayer antioxidant carbon aerogel composite material and its preparation method in this embodiment are similar to those in Example 1, except that in step (4), the coating amount of organosilicon resin is 0.05 g / cm³. 2 .

[0076] The multilayer antioxidant carbon aerogel composite material prepared in this embodiment was tested in Example 1, and the results were basically the same. Due to space limitations, they will not be listed one by one.

[0077] Example 7 The multilayer antioxidant carbon aerogel composite material and its preparation method in this embodiment are similar to those in Example 1, except that in step (4), the coating amount of organosilicon resin is 0.1 g / cm³. 2 .

[0078] The multilayer antioxidant carbon aerogel composite material prepared in this embodiment was tested in Example 1, and the results were basically the same. Due to space limitations, they will not be listed one by one.

[0079] Example 8 The multilayer antioxidant carbon aerogel composite material and its preparation method in this embodiment are similar to those in Example 1, except that in step (5), the coating amount of the ceramic-based anti-ablation putty is 0.08 g / cm³. 2 .

[0080] The multilayer antioxidant carbon aerogel composite material prepared in this embodiment was tested in Example 1, and the results were basically the same. Due to space limitations, they will not be listed one by one.

[0081] Example 9 The multilayer antioxidant carbon aerogel composite material and its preparation method in this embodiment are similar to those in Example 1, except that in step (5), the coating amount of the ceramic-based anti-ablation putty is 0.2 g / cm³. 2 .

[0082] The multilayer antioxidant carbon aerogel composite material prepared in this embodiment was tested in Example 1, and the results were basically the same. Due to space limitations, they will not be listed one by one.

[0083] Example 10 The multilayer antioxidant carbon aerogel composite material and preparation method of this embodiment are similar to those of Example 1, except that in step (2), the mass fraction of phenyl silicone resin (manufacturer is Anhui Aiyota Silicon Oil Co., Ltd., brand name IOTA GT3) in the organosilicon resin solution is 30%, the catalyst is tetramethylammonium hydroxide (TMAH), the amount of catalyst is 0.2% of the mass of the organosilicon resin solution, and the organic solvent is toluene; In step (5), the gradient curing temperature is maintained at 90℃ for 15 hours and at 130℃ for 10 hours.

[0084] The multilayer antioxidant carbon aerogel composite material prepared in this embodiment was tested in Example 1, and the results were basically the same. Due to space limitations, they will not be listed one by one.

[0085] Example 11 The multilayer antioxidant carbon aerogel composite material and its preparation method in this embodiment are similar to those in Example 1. The difference is that in step (2), the mass fraction of methylphenyl silicone resin (manufacturer: IOTA Silicon Oil Co., Ltd., brand name: IOTA 6156C) in the silicone resin solution is 60%, the catalyst is tetramethylammonium hydroxide (TMAH), the amount of catalyst is 0.8% of the mass of the silicone resin solution, and the organic solvent is ethylene glycol.

[0086] In step (5), the gradient curing temperature is maintained at 100℃ for 8 hours and at 180℃ for 5 hours.

[0087] The multilayer antioxidant carbon aerogel composite material prepared in this embodiment was tested in Example 1, and the results were basically the same. Due to space limitations, they will not be listed one by one.

[0088] Comparative Example 1 The multilayer antioxidant carbon aerogel composite material and its preparation method in this comparative example are similar to those in Example 1, except that in step (1), the raw materials of the multi-component ceramic-based ablation-resistant coating do not include molybdenum silicide.

[0089] Comparative Example 2 The multilayer antioxidant carbon aerogel composite material and its preparation method in this comparative example are similar to those in Example 1, except that in step (1), the mass ratio of zirconium boride, silicon powder, molybdenum silicide, low melting point glass powder and thermosetting phenolic resin is 4:2:1:3:2.

[0090] Comparative Example 3 The multilayer antioxidant carbon aerogel composite material and its preparation method in this comparative example are similar to those in Example 1, except that in step (2), the mass fraction of the organosilicon resin in the organosilicon resin solution is 20%.

[0091] Comparative Example 4 The multilayer antioxidant carbon aerogel composite material and its preparation method in this comparative example are similar to those in Example 1, except that in step (4), the coating amount of the organosilicon resin solution is 0.15 g / cm³. 2 .

[0092] Comparative Example 5 The multilayer antioxidant carbon aerogel composite material and its preparation method in this comparative example are similar to those in Example 1, except that in step (5), the coating amount of the ceramic-based anti-ablation putty is 0.06 g / cm³. 2 .

[0093] Comparative Example 6 The multilayer antioxidant carbon aerogel composite material and its preparation method in this comparative example are similar to those in Example 1. The difference is that in step (5), gradient curing is not used, but only curing treatment is performed at 80°C for 20 hours.

[0094] Experimental Example 1 The density of the carbon aerogel composite matrix, the multilayer antioxidant carbon aerogel composites prepared in the examples and comparative examples, and the linear ablation rate, mass loss, and surface condition (cracking or peeling) after 300s of oxyacetylene testing at 1800℃ were tested respectively. The results are shown in Table 1. The ablation test was conducted according to GJB 323B-2018 "Ablation Test Method for Ablation Materials", with an ablation sample diameter of Φ30mm and a thickness of 10mm. The ablation retreat amount = material thickness before ablation - material thickness after ablation; linear ablation rate = ablation retreat amount / ablation time; mass loss = mass before ablation - mass after ablation; mass loss rate = mass loss / ablation time.

[0095] Table 1

[0096] As shown in Table 1, the density of the multilayer antioxidant carbon aerogel composite material prepared by the method of the present invention is ≤0.79 g / cm³. 3 Preferably, the density is 0.71~0.79 g / cm³. 3 The ablation retreat is ≤0.208mm, preferably 0.072~0.208mm; the linear ablation rate is ≤0.693μm / s, preferably 0.240~0.693μm / s; the mass loss is ≤0.672g, preferably 0.494~0.672g; and the mass loss rate is ≤2.24mg / s, preferably 1.65~2.24mg / s.

[0097] The multilayer antioxidant carbon aerogel composite material prepared by this invention has an intact overall surface structure and is in good condition, forming a relatively dense protective layer. The coating does not show obvious peeling or cracks, exhibiting good structural stability and ablation resistance.

[0098] Compared to Example 1, when the ceramic formulation does not contain molybdenum silicide, the SiO2 content generated during the high-temperature ablation process is reduced. This makes it difficult to form a continuous and dense glassy protective layer on the surface, resulting in insufficient fluidity of the molten phase. Consequently, cracks and pores are difficult to fill effectively, reducing self-healing ability and weakening the barrier effect against oxygen diffusion. Simultaneously, due to the lack of high-emissivity components such as Mo oxide, the surface emissivity of the material decreases, weakening radiative heat dissipation. This leads to heat accumulation on the surface, further exacerbating the ablation process, ultimately resulting in increased ablation retreat and a significant decrease in ablation resistance.

[0099] Compared to Example 1, when the zirconium boride content in Comparative Example 2 was increased beyond a reasonable range, the proportion of the refractory ceramic phase in the system increased significantly, resulting in a relative decrease in the glass phase formed at high temperatures. This weakened the fluidity and densification ability of the molten layer, making it difficult to fill cracks and pores in a timely manner, and reducing the self-healing ability. In addition, excessively high zirconium boride content exacerbates the thermal stress concentration of the coating, reduces its thermal shock resistance, and makes it prone to cracking or even localized peeling during ablation.

[0100] Compared with Example 1, when the mass fraction of the silicone resin in the silicone resin solution is too low, it is difficult to form a continuous and dense transition layer structure on the substrate surface, resulting in incomplete interfacial bonding, reduced bonding strength between the coating and the substrate, and reduced buffering effect against thermal stress. This makes it easy to cause cracking or peeling during the ablation process, thereby reducing the overall ablation resistance of the material.

[0101] Compared with Example 1, when the coating amount of silicone resin solution is too high, an excessively thick organic phase layer will be formed on the substrate surface, which will reduce the high temperature resistance of the interface and make it prone to shrinkage or cracking during the ablation process. Compared to Example 1, in Comparative Example 5, an insufficient coating amount of ceramic-based anti-ablation putty leads to incomplete coating coverage or insufficient thickness, making it difficult to form an effective anti-oxidation and anti-ablation protective layer. This manifests as insufficient anti-ablation performance, severe ablation regression, and significant quality loss.

[0102] Compared with Example 1, if gradient curing is not performed, the coating may not cure completely, resulting in weak bonding between the coating and the substrate, and easy peeling during the ablation process.

[0103] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A multilayer antioxidant carbon aerogel composite material, characterized in that, The composite material comprises, from top to bottom, a multi-component ceramic-based ablation-resistant coating, an organosilicon resin transition layer, and a carbon aerogel composite material layer; The raw materials for the multi-component ceramic-based ablation-resistant coating include zirconium boride, silicon powder, molybdenum silicide, low-melting-point glass powder, and thermosetting phenolic resin.

2. The multilayer antioxidant carbon aerogel composite material according to claim 1, characterized in that, The mass ratio of zirconium boride, silicon powder, molybdenum silicide, low-melting-point glass powder, and thermosetting phenolic resin is 1~3:1~3:0.5~2:1.5~5:1~3.

3. The multilayer antioxidant carbon aerogel composite material according to claim 1 or 2, characterized in that, The raw material for the organosilicon resin transition layer includes organosilicon resin, which includes one or more of methyl silicone resin, phenyl silicone resin, and methylphenyl silicone resin.

4. A method for preparing the multilayer antioxidant carbon aerogel composite material according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Zirconium boride, silicon powder, molybdenum silicide and low melting point glass powder are mixed and ball-milled to obtain mixed powder. Then thermosetting phenolic resin is added and stirred in a water bath to obtain ceramic-based anti-ablation putty. (2) Dissolve the organosilicon resin in an organic solvent and add a catalyst, stir to obtain an organosilicon resin solution; (3) The surface of the carbon aerogel composite material is polished, cleaned and dried to obtain the surface-treated carbon aerogel composite material; (4) The silicone resin solution described in step (2) is coated on the surface of the carbon aerogel composite material after surface treatment to form a silicone resin transition layer; (5) The ceramic-based anti-ablation putty described in step (1) is coated on the surface of the silicone resin transition layer and subjected to gradient curing treatment to obtain the multilayer anti-oxidation carbon aerogel composite material.

5. The preparation method according to claim 4, characterized in that, In step (2), the mass fraction of the organosilicon resin in the organosilicon resin solution is 30-60%, and the mass fraction of the catalyst is 0.2-0.8%.

6. The preparation method according to claim 4, characterized in that, In step (2), the catalyst is tetramethylammonium hydroxide, and the organic solvent includes one or more of anhydrous ethanol, toluene, xylene, isopropanol, and ethylene glycol.

7. The preparation method according to claim 4, characterized in that, In step (4), the coating amount of the silicone resin solution is 0.05~0.1 g / cm³. 2 .

8. The preparation method according to claim 4, characterized in that, In step (5), the coating amount of the ceramic-based anti-ablation putty is 0.08~0.2 g / cm³. 2 .

9. The preparation method according to claim 4, characterized in that, In step (5), the gradient curing process is to maintain the temperature at 80~100℃ for 8~15h and at 130~180℃ for 5~10h.

10. The application of a multilayer antioxidant carbon aerogel composite material according to any one of claims 1-3 or a multilayer antioxidant carbon aerogel composite material prepared by any one of claims 4-9 in high-temperature antioxidant and / or ablation-resistant protective materials.

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