Preparation process of antioxidant self-healing carbon aerogel reinforced high-silica composite thermal insulation material

Abstract

The application belongs to the technical field of composite thermal insulation material application, and particularly discloses a preparation process of an oxidation-resistant self-healing carbon aerogel reinforced high-silicon oxygen composite thermal insulation material, which comprises the following steps: 1) high-silicon oxygen fiber preform pretreatment; 2) organic aerogel precursor solution preparation; 3) vacuum impregnation and in-situ polymerization; 4) solvent replacement and supercritical drying; 5) inert atmosphere co-carbonization; 6) PIP method for preparing SiC / SiCO self-healing coating; and 7) high-temperature annealing post-treatment. The application has the beneficial effects that: vacuum impregnation combined with in-situ polymerization enables the organic aerogel precursor to be in-situ crosslinked on the surface and in the pores of the high-silicon oxygen fiber, forming a -Si-O-C covalent bond, thereby solving the problem of poor interface bonding; the SiC / SiCO coating generated by the PIP method melts to form a glass phase at 800-1200 DEG C, automatically fills cracks and defects, blocks oxygen diffusion, and realizes high-temperature self-healing oxidation resistance; the high-silicon oxygen fiber, carbon aerogel and SiC / SiCO ceramic membrane are three-dimensionally interconnected, and the comprehensive performance of the material is synergistically improved.

Description

Technical Field

[0001] This invention belongs to the field of composite thermal insulation material application technology, specifically relating to the preparation process of an antioxidant self-healing carbon aerogel-reinforced high-silica composite thermal insulation material. Background Technology

[0002] Thermal insulation composite materials refer to composite materials that have the function of preventing heat transfer or providing thermal insulation. They achieve their thermal insulation function through foam, fiber, hollow board, or coating structure. Typical materials include ultra-lightweight nanoporous thermal insulation composite materials (thermal conductivity / mK, density 0.25g / cm³), and their application fields cover extreme high-temperature thermal insulation scenarios such as thermal protection of new energy power batteries, external protection of aircraft, and industrial high-temperature kilns.

[0003] The high-temperature resistant coating developed in the industrialization project can withstand flames at 1000-1150℃ for 30 minutes, and the flexible thermal insulation material has a back-side temperature rise of less than 300℃ after being burned in a 1000℃ flame for 10 minutes. Professor Hong Changqing's team has made breakthroughs in the core technology of ultra-high temperature thermal protection composite materials, and the pilot production line they have established has GJB9001C-2017 quality management qualification. This material has applications in building insulation panels, lightweight automotive components, and electrical and electronic insulation fields. Commonly used matrices include phenolic resin and glass fiber / epoxy resin composite systems.

[0004] In actual research and development, carbon aerogel is a highly promising high-temperature insulation material due to its advantages such as nanoporous structure, ultra-low thermal conductivity, and low density. However, it has two major defects: (1) It is easily oxidized at high temperatures and rapidly ablates in an oxygen-rich environment above 600°C, which cannot meet the requirements for use above 1000°C; (2) It has poor interfacial bonding and is only physically bonded to the fiber reinforcement, making it easy to peel off and resulting in low mechanical strength, which limits its engineering applications. Existing technologies mostly use a single coating or physical composite, which makes it difficult to achieve synergistic optimization of strong interfacial bonding, high-temperature self-healing oxidation resistance, and low thermal conductivity at the same time.

[0005] To address the aforementioned issues, this invention provides a preparation process for an antioxidant, self-healing carbon aerogel-reinforced high-silica composite thermal insulation material. Summary of the Invention

[0006] Purpose of the invention: The purpose of this invention is to address the shortcomings of existing technologies by providing a preparation process for an antioxidant self-healing carbon aerogel-reinforced high-silica composite thermal insulation material. Through in-situ composite and self-healing coating technology, a ternary interpenetrating network structure is constructed to achieve a strong interfacial bond between carbon aerogel and high-silica fibers, thereby solving the problem of high-temperature oxidation and preparing a composite thermal insulation material with lightweight, low thermal conductivity, high strength, high-temperature self-healing and antioxidant properties.

[0007] Technical Solution: This invention provides a preparation process for an antioxidant self-healing carbon aerogel-reinforced high-silica composite thermal insulation material. Step 1) Pretreatment of the high-silica fiber preform: The high-silica fiber felt is degreased, surface activated, and vacuum dried to obtain a fiber preform with surface rich in -OH and -Si-OH active sites. Step 2) Preparation of the organic aerogel precursor solution: Phenolic resin is used as the carbon source, formaldehyde as the crosslinking agent, hexamethylenetetramine as the curing agent, and ethanol / ethylene glycol as the mixed solvent. A silane coupling agent is added, and the mixture is stirred and dispersed to obtain a uniform precursor sol. Step 3) Vacuum impregnation and in-situ polymerization: The pretreated high-silica fiber preform is placed in a vacuum impregnation kettle, and a vacuum is drawn to -0.098 °C. MPa, inject precursor sol and impregnate under pressure, then perform atmospheric pressure gelation and in-situ curing to form a fiber-organic aerogel interpenetrating network wet gel; Step 4) Solvent replacement and supercritical drying, use ethanol and acetone to replace the solvent in the wet gel in sequence, and then dry with supercritical CO2 to obtain high silica fiber-reinforced organic aerogel; Step 5) Inert atmosphere co-carbonization, carbonize under argon atmosphere with programmed temperature rise to convert organic aerogel into carbon aerogel to obtain high silica fiber-reinforced carbon aerogel matrix; Step 6) PIP method to prepare SiC / SiCO self-healing coating, using polycarbosilane as ceramic precursor, vacuum impregnation, curing, and high temperature pyrolysis cycle treatment to generate a continuous and dense SiC / SiCO ceramic coating in situ on the surface and pores of carbon aerogel, forming a ternary interpenetrating network composite thermal insulation material; Step 7) High temperature annealing post-treatment, anneal at high temperature under argon atmosphere to eliminate residual stress and stabilize the coating structure.

[0008] In this technical solution, in step 1), the degreasing process is to keep warm at 500°C in an air atmosphere for 2 hours; the surface activation is performed by oxygen plasma treatment with a power of 100W for 10 minutes; and the vacuum drying temperature is 120°C for 4 hours.

[0009] In step 2) of this technical solution, the precursor solution mass ratio is as follows: 100 parts phenolic resin, 30 parts 37% formaldehyde solution, 5 parts hexamethylenetetramine, 200 parts ethanol / ethylene glycol (volume ratio 7:3), and 2 parts silane coupling agent KH-550; the stirring time is 2 hours, and the ultrasonic dispersion time is 30 minutes.

[0010] In this technical solution, in step 3), the pressure impregnation time is 2 hours; the atmospheric pressure gel temperature is 80°C and the time is 6 hours; the in-situ curing temperature is 120°C and the time is 12 hours, and a -Si-OC-covalent bond interface is formed between the fiber and the carbon aerogel.

[0011] In step 5) of this technical solution, the carbonization heating program is room temperature → 300℃ → 800℃ → 1000℃, and the argon flow rate is 80-100mL / min.

[0012] In step 6) of this technical solution, the mass ratio of polycarbosilane to xylene is 1:4; PIP is cycled 3-5 times, the pyrolysis temperature is 1000℃, and the holding time is 2h; the SiC / SiCO coating thickness is 5-10μm, and it melts at 800-1200℃ to form a glass phase to achieve self-healing.

[0013] In this technical solution, in step 7), the annealing temperature is 1050-1200℃ and the holding time is 2h.

[0014] Compared with the prior art, the beneficial effects of the high-temperature resistant multi-doped modified high-silica fiber and its preparation method of the present invention are as follows: 1. Vacuum impregnation combined with in-situ polymerization enables the organic aerogel precursor to crosslink in situ on the surface and pores of the high-silica fiber, forming -Si-OC- covalent bonds, thus solving the problem of poor interfacial bonding; 2. The SiC / SiCO coating generated by the PIP method melts at 800-1200℃ to form a glass phase, which automatically fills cracks and defects, blocks oxygen diffusion, and achieves high-temperature self-healing and anti-oxidation; 3. The continuous reinforcing phase of the high-silica fiber, the nanoporous heat-insulating phase of the carbon aerogel, and the anti-oxidation and self-healing phase of the SiC / SiCO ceramic film are three-dimensionally integrated, synergistically improving the comprehensive performance of the material. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the process structure of the preparation method of the present invention. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0018] In the description of this invention, it should be noted that the terms "top," "bottom," "one side," "the other side," "front," "rear," "middle part," "inner," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0019] like Figure 1 The process for preparing an antioxidant self-healing carbon aerogel-reinforced high-silica composite thermal insulation material is shown. Step 1) Pretreatment of the high-silica fiber preform: The high-silica fiber felt is degreased, surface activated, and vacuum dried to obtain a fiber preform with surface rich in -OH and -Si-OH active sites. Step 2) Preparation of the organic aerogel precursor solution: Phenolic resin is used as the carbon source, formaldehyde as the crosslinking agent, hexamethylenetetramine as the curing agent, and ethanol / ethylene glycol as a mixed solvent. A silane coupling agent is added, and the mixture is stirred and dispersed to obtain a uniform precursor sol. Step 3) Vacuum impregnation and in-situ polymerization: The pretreated high-silica fiber preform is placed in a vacuum impregnation kettle, and a vacuum is drawn to -0.098 °C. MPa, inject precursor sol and impregnate under pressure, then perform atmospheric pressure gelation and in-situ curing to form a fiber-organic aerogel interpenetrating network wet gel; Step 4) Solvent replacement and supercritical drying, use ethanol and acetone to replace the solvent in the wet gel in sequence, and then dry with supercritical CO2 to obtain high silica fiber-reinforced organic aerogel; Step 5) Inert atmosphere co-carbonization, carbonize under argon atmosphere with programmed temperature rise to convert organic aerogel into carbon aerogel to obtain high silica fiber-reinforced carbon aerogel matrix; Step 6) PIP method to prepare SiC / SiCO self-healing coating, using polycarbosilane as ceramic precursor, vacuum impregnation, curing, and high temperature pyrolysis cycle treatment to generate a continuous and dense SiC / SiCO ceramic coating in situ on the surface and pores of carbon aerogel, forming a ternary interpenetrating network composite thermal insulation material; Step 7) High temperature annealing post-treatment, anneal at high temperature under argon atmosphere to eliminate residual stress and stabilize the coating structure.

[0020] In addition, preferably in step 1), the degreasing process is to keep warm at 500°C in an air atmosphere for 2 hours; the surface activation is carried out by oxygen plasma treatment with a power of 100W for 10 minutes; and the vacuum drying temperature is 120°C for 4 hours.

[0021] In addition, preferably in step 2), the precursor solution mass ratio is: 100 parts phenolic resin, 30 parts 37% formaldehyde solution, 5 parts hexamethylenetetramine, 200 parts ethanol / ethylene glycol (volume ratio 7:3), and 2 parts silane coupling agent KH-550; the stirring time is 2 hours, and the ultrasonic dispersion time is 30 minutes.

[0022] In addition, preferably in step 3), the pressure impregnation time is 2 hours; the atmospheric pressure gel temperature is 80°C for 6 hours; the in-situ curing temperature is 120°C for 12 hours, and a -Si-OC-covalent bond interface is formed between the fiber and the carbon aerogel.

[0023] In addition, preferably in step 5), the carbonization heating program is room temperature → 300℃ (2℃ / min, holding time is 2h) → 800℃ (5℃ / min, holding time is 3h) → 1000℃ (3℃ / min, holding time is 2h), and the argon flow rate is 80-100mL / min.

[0024] In addition, in step 6), the mass ratio of polycarbosilane to xylene is 1:4; the PIP cycle is 3-5 times, the pyrolysis temperature is 1000℃, and the holding time is 2h; the SiC / SiCO coating thickness is 5-10μm, and it melts at 800-1200℃ to form a glass phase to achieve self-healing.

[0025] Example

[0026] During the pretreatment of high-silica fiber preforms, the raw material is high-silica fiber felt (SiO2 content > 96%, diameter 8-12μm); degreasing is carried out at 500℃ in air atmosphere for 2h to remove surface slurry and impurities; during activation, oxygen plasma treatment (100W, 10min) is performed to introduce -OH and -Si-OH active sites; drying is carried out at 120℃ under vacuum for 4h for later use.

[0027] When preparing the organic aerogel precursor solution, use 100 parts of phenolic resin (Mw=800-1200), 30 parts of 37% formaldehyde, 5 parts of hexamethylenetetramine, 200 parts of ethanol / ethylene glycol (7:3), and 2 parts of KH-550. Stir at room temperature for 2 hours and sonicate for 30 minutes to obtain a transparent precursor sol.

[0028] During vacuum impregnation and in-situ polymerization, impregnation is performed first. Sol is injected under vacuum of -0.098 MPa and held at pressure for 2 hours to ensure complete penetration. Then, gelation is carried out at 80°C for 6 hours to form a wet gel. Finally, curing is performed at 120°C for 12 hours to crosslink in situ and construct a fiber-organic aerogel interpenetrating network.

[0029] During solvent replacement and supercritical drying, the temperature program was room temperature → 300℃ (2℃ / min, 2h) → 800℃ (5℃ / min, 3h) → 1000℃ (3℃ / min, 2h) to obtain high silica fiber reinforced carbon aerogel (specific surface area 400-600m² / g, porosity 90%-95%).

[0030] When preparing SiC / SiCO self-healing coatings using the PIP method, the precursor is polycarbosilane (Mw=1200-1500): xylene=1:4; the process involves cyclic processing (3-5 times); vacuum impregnation for 4 hours → curing at 180℃ for 6 hours → pyrolysis at 1000℃ for 2 hours to generate a SiC / SiCO coating (5-10μm); self-healing occurs when SiCO melts at 800–1200℃, sealing cracks and inhibiting oxidation.

[0031] The antioxidant self-healing carbon aerogel-reinforced high-silica composite thermal insulation material prepared using the above-mentioned process features covalent bonding, no interfacial debonding, and a mechanical strength increase of over 50%. Its oxidation weight loss at 1200℃ / 2h is <8%, breaking through the 600℃ oxidation bottleneck of carbon aerogels. Its room temperature thermal conductivity is 0.06-0.08 W / (m・K), superior to traditional ceramic fiber thermal insulation materials. It integrates lightweight (0.20-0.35 g / cm³), high strength (2-5 MPa), low thermal conductivity, and high oxidation resistance. The material's performance can be controlled by adjusting the PIP cycle number and carbonization temperature to suit different application scenarios.

[0032] It should be noted that, in this document, terms such as "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0033] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A preparation process for an antioxidant, self-healing carbon aerogel-reinforced high-silica composite thermal insulation material, characterized in that: Includes the following steps, Step 1) Pretreatment of high silica fiber preform: The high silica fiber felt is degreased, surface activated and vacuum dried to obtain a fiber preform with surface rich in -OH and -Si-OH active sites; Step 2) Preparation of organic aerogel precursor solution: using phenolic resin as carbon source, formaldehyde as crosslinking agent, hexamethylenetetramine as curing agent, ethanol / ethylene glycol as mixed solvent, adding silane coupling agent, and stirring to disperse to obtain uniform precursor sol. Step 3) Vacuum impregnation and in-situ polymerization: The pretreated high silica fiber preform is placed in a vacuum impregnation kettle, vacuumed to -0.098 MPa, the precursor sol is injected and impregnated under pressure, and then atmospheric pressure gelation and in-situ curing are carried out in sequence to form a fiber organic aerogel interpenetrating network wet gel. Step 4) Solvent replacement and supercritical drying: Ethanol and acetone are used to replace the solvent in the wet gel in sequence, and then supercritical CO2 drying is performed to obtain a high silica fiber reinforced organic aerogel. Step 5) Co-carbonization in an inert atmosphere: Carbonization is carried out under a programmed temperature rise in an argon atmosphere to convert the organic aerogel into a carbon aerogel and obtain a high silica fiber reinforced carbon aerogel matrix. Step 6) Prepare SiC / SiCO self-healing coating by PIP method. Using polycarbosilane as ceramic precursor, the coating is continuously and densely generated on the surface and pores of carbon aerogel through vacuum impregnation, curing and high-temperature pyrolysis cycle treatment, forming a ternary interpenetrating network composite thermal insulation material. Step 7) High-temperature annealing post-treatment: High-temperature annealing under argon atmosphere to eliminate residual stress and stabilize the coating structure.

2. The preparation process of the antioxidant self-healing carbon aerogel-reinforced high-silica composite thermal insulation material according to claim 1, characterized in that: In step 1), the degreasing process is to keep the temperature at 500°C in an air atmosphere for 2 hours; the surface activation is performed by oxygen plasma treatment with a power of 100W for 10 minutes; and the vacuum drying temperature is 120°C for 4 hours.

3. The preparation process of the antioxidant self-healing carbon aerogel-reinforced high-silica composite thermal insulation material according to claim 1, characterized in that: In step 2), the precursor solution has the following mass ratio: 100 parts phenolic resin, 30 parts 37% formaldehyde solution, 5 parts hexamethylenetetramine, 200 parts ethanol / ethylene glycol (volume ratio 7:3), and 2 parts silane coupling agent KH-550; the stirring time is 2 hours, and the ultrasonic dispersion time is 30 minutes.

4. The preparation process of an antioxidant self-healing carbon aerogel-reinforced high-silica composite thermal insulation material according to claim 1, characterized in that: In step 3), the pressure impregnation time is 2 hours; the atmospheric pressure gel temperature is 80°C for 6 hours; the in-situ curing temperature is 120°C for 12 hours, and a -Si-OC-covalent bond interface is formed between the fiber and the carbon aerogel.

5. The preparation process of an antioxidant self-healing carbon aerogel-reinforced high-silica composite thermal insulation material according to claim 1, characterized in that: In step 5), the carbonization heating program is room temperature → 300℃ → 800℃ → 1000℃, and the argon flow rate is 80-100 mL / min.

6. The preparation process of an antioxidant self-healing carbon aerogel-reinforced high-silica composite thermal insulation material according to claim 1, characterized in that: In step 6), the mass ratio of polycarbosilane to xylene is 1:4; PIP is cycled 3-5 times, the pyrolysis temperature is 1000℃, and the holding time is 2h; the SiC / SiCO coating thickness is 5-10μm, and it melts at 800-1200℃ to form a glass phase to achieve self-healing.

7. The preparation process of an antioxidant self-healing carbon aerogel-reinforced high-silica composite thermal insulation material according to claim 1, characterized in that: In step 7), the annealing temperature is 1050-1200℃ and the holding time is 2h.

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