Zirconium boride-carbon hybrid aerogel composite material and preparation method thereof

Abstract

The invention discloses a zirconium boride-carbon hybrid aerogel composite material and a preparation method thereof, and belongs to the technical field of aerogel materials. In order to solve the problem of insufficient oxidation resistance of a carbon aerogel material, a co-gel method is mainly adopted to introduce a zirconium boride precursor network, zirconium boride is generated in situ through pyrolysis reduction, and matrix oxidation resistance modification of carbon aerogel is realized. A stable anti-oxidation protection layer can be formed in a high-temperature aerobic environment, the high-temperature-resistant and anti-oxidation performance of the material is improved, and the material can be applied to the field of light thermal protection.

Description

Technical Field

[0001] The present invention relates to a zirconium boride-carbon hybrid aerogel composite material and a preparation method thereof, belonging to the technical field of aerogel materials. Background Art

[0002] Aerogel is a nano-porous material. Due to its unique properties such as light weight, heat insulation, and wave absorption, aerogel and its composite materials have wide applications in the field of thermal protection. According to the different materials, aerogel materials can be generally divided into organic aerogel materials, inorganic oxide aerogel materials, non-oxide ceramic aerogel materials, etc. Organic aerogels mainly include cellulose aerogel, phenolic aerogel, polybenzoxazine aerogel, etc. Due to the characteristics of their own organic substances, the non-ablative service temperature of organic aerogels is generally lower than 500°C. For inorganic oxide aerogel materials such as silica, alumina, and zirconia, the temperature at which sintering or phase transformation occurs can reach about 1000°C, and the upper limit of the service temperature is relatively high. The emerging non-oxide ceramic aerogels such as silicon carbide and silicon nitride have good dielectric properties and have important applications in functional thermal protection fields such as electromagnetic shielding and wave absorption and stealth, but their service temperature is generally not higher than 1500°C. With the development of thermal protection materials towards applications in more severe high-temperature environments, there is an urgent need to develop aerogel materials with higher heat resistance.

[0003] Carbon aerogel material is an inorganic aerogel material with a high temperature resistance of over 2000 °C. In an inert or vacuum environment, the carbon aerogel material can still maintain a good micro-nano pore structure after long-term high-temperature treatment. However, when the temperature is higher than 500 °C, the carbon aerogel material will be rapidly oxidized in an aerobic environment. To meet the requirements of practical applications, antioxidant modification of the carbon aerogel material is needed. The antioxidant modification methods of carbon aerogel materials can be divided into two types: coating modification and matrix modification. Coating modification is to isolate oxygen by coating a dense layer on the surface of the carbon aerogel material for antioxidant protection. Matrix modification is to introduce antioxidant components into the carbon aerogel material matrix. The antioxidant components can coat and protect the carbon aerogel material skeleton in the early stage of introduction, or actively oxidize when the carbon aerogel material is eroded by oxygen, capture and dilute oxygen, and form a skeleton coating layer. Currently, based on the technical foundation and mature application of coating modification in the antioxidant modification of dense carbon materials such as carbon / carbon, the coating modification of carbon aerogel materials has developed rapidly (patent applications CN118405942A and CN117585981A), while there are few reports on the research of matrix antioxidant modification of carbon aerogel materials (Wu Kede, Zhou Qi, Cao Junxiang, et al. Ultrahigh-strength carbon aerogels for high temperature thermal insulation. Journal of Colloid and Interface Science, 2022, 609, 667–675). This is mainly because it is difficult to fully introduce antioxidant components into the carbon aerogel material skeleton, resulting in poor antioxidant effect of matrix modification. Therefore, it is necessary to develop a matrix modification method for carbon aerogel materials that can effectively resist oxidation. Summary of the Invention

[0004] The object of the present invention is to propose a zirconium boride-carbon hybrid aerogel composite material and its preparation method. By co-gel introducing an antioxidant component precursor network and then pyrolytically reducing to in-situ introduce zirconium boride as the antioxidant component, the matrix antioxidant modification of the carbon aerogel material is realized, making up for the deficiency of insufficient oxygen resistance in the matrix antioxidant modification of the existing carbon aerogel material, and it can be applied to high-temperature thermal insulation materials in the field of lightweight thermal protection.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A preparation method of a zirconium boride-carbon hybrid aerogel composite material, comprising the following steps:

[0007] (1) Prepare a zirconium boride precursor sol and a phenolic resin sol;

[0008] (2) Mix the zirconium boride precursor sol and the phenolic sol, then impregnate the pre-oxidized fiber reinforcement by vacuum assistance, and then place it in an oven for curing to obtain a wet gel of the zirconium boride-carbon hybrid aerogel material organic precursor;

[0009] (3) Immerse the wet gel of the zirconium boride-carbon hybrid aerogel material organic precursor in ethanol for solvent replacement, and then air-dry until the mass no longer changes to obtain the zirconium boride-carbon hybrid aerogel organic precursor;

[0010] (4) Pyrolyze and carbonize the zirconium boride-carbon hybrid aerogel organic precursor in an inert atmosphere to obtain the zirconium boride-carbon hybrid aerogel composite material.

[0011] Further, the phenolic sol in step (1) is one or more of resorcinol-formaldehyde phenolic sol and resorcinol-furfural sol.

[0012] Further, the molar ratio of phenol to aldehyde in the phenolic sol in step (1) ranges from 2:1 to 1:3.

[0013] Further, the density of the pre-oxidized fiber reinforcement in step (2) ranges from 0.05 to 0.25 g / cm 3 .

[0014] Further, the curing temperature in step (2) ranges from 80 to 120 °C, and the total curing duration is 24 to 96 h.

[0015] Further, the solvent replacement method in step (3) is: replace the ethanol every 48 h, and a total of 3 to 6 rounds of replacement are carried out.

[0016] Further, the pyrolysis carbonization temperature in step (4) ranges from 1300 to 1700 °C.

[0017] Further, the heating rate of pyrolysis carbonization in step (4) is 1 to 5 °C / min.

[0018] A zirconium boride-carbon hybrid aerogel composite material is prepared by the above preparation method.

[0019] The principle of the present invention is: Mix the zirconium boride precursor sol and the phenolic sol evenly. During the heating process, the zirconium boride precursor and the phenolic sol will gel synergistically to form a double-network skeleton structure. During the pyrolysis process, zirconium oxide and boron oxide in the zirconium boride precursor will react with the carbon formed by the pyrolysis of the phenolic sol to generate zirconium boride (see the reaction formula below). Thanks to the double-network structure, zirconium boride will be evenly embedded in the carbon skeleton to form a zirconium boride-carbon hybrid aerogel. In a high-temperature aerobic environment, zirconium boride will oxidize to form liquid boron oxide and solid zirconium oxide. The liquid boron oxide can form a liquid film that isolates oxygen to coat the carbon skeleton, and zirconium oxide can improve the stability of the liquid film and promote the antioxidant effect.

[0020] ZrO2(s) + B2O3(I) + C(s) → ZrB2(s) + CO(g)

[0021] The present invention has the following advantages compared with the prior art:

[0022] 1. The present invention does not involve supercritical drying and has no requirement for expensive equipment.

[0023] 2. The present invention can achieve uniform and sufficient distribution of zirconium boride, an antioxidant component, in the carbon skeleton, improving the antioxidant effect.

[0024] 3. Zirconium boride, the antioxidant component used in the present invention, belongs to ultra-high temperature ceramics with a melting point above 3000 °C, and will not affect the temperature resistance of the carbon aerogel itself under inert or vacuum conditions. Description of the Drawings

[0025] Figure 1 is the preparation flow chart of the zirconium boride-carbon hybrid aerogel composite material of the present invention. Detailed Embodiments

[0026] To make the technical features, advantages or technical effects in the above technical solutions of the present invention more obvious and understandable, the following will be described in detail through examples.

[0027] Example 1

[0028] A method for preparing a zirconium boride-carbon hybrid aerogel composite material includes the following steps:

[0029] (1) Weigh 1780 g of zirconium oxychloride octahydrate and 192 g of citric acid, add them to a mixed solution of 1500 g of absolute ethanol and 1000 g of pure water and stir to dissolve. Then weigh 1488 g of boric acid, add it to a mixed solution of 1500 g of absolute ethanol and 1000 g of pure water and stir evenly. Mix the above two solutions and stir evenly to obtain a zirconium boride precursor sol. Weigh 1100 g of resorcinol and 1920 g of furfural, add them to a mixed solution of 3000 g of absolute ethanol and 2000 g of pure water and stir to dissolve to obtain a phenolic sol.

[0030] (2) Mix the zirconium boride precursor sol and the phenolic sol evenly, impregnate a pre-oxidized fiber reinforcement (size 450 mm × 450 mm × 60 mm) under vacuum until no more bubbles are discharged, and then place it in an oven to cure at 80 °C for 24 h and at 120 °C for 24 h to obtain a wet gel of the zirconium boride-carbon hybrid aerogel material organic precursor.

[0031] (3) Immerse the wet gel of the zirconium boride-carbon hybrid aerogel material organic precursor in sufficient ethanol for solvent replacement, change the ethanol every 48 h, and perform a total of 3 rounds of replacement. Then, leave the replaced wet gel to dry at room temperature until the mass no longer changes, obtaining the zirconium boride-carbon hybrid aerogel organic precursor.

[0032] (4) Pyrolytic carbonize the zirconium boride-carbon hybrid aerogel organic precursor in an argon atmosphere by heating it to 1500 °C at a heating rate of 3 °C / min and holding for 3 h to obtain the zirconium boride-carbon hybrid aerogel composite material.

[0033] The density of the finally prepared zirconium boride-carbon hybrid aerogel composite material is 0.52 g / cm 3 , the residual weight after being treated at 1000 °C for 1000 s in an air atmosphere is not less than 90%, and the linear shrinkage after being treated at 2000 °C for 1000 s in an inert atmosphere is not more than 3%.

[0034] Example 2

[0035] A preparation method of a zirconium boride-carbon hybrid aerogel composite material, comprising the following steps:

[0036] (1) Weigh 1780 zirconium oxychloride octahydrate and 192 g of citric acid, add them to a mixed solution of 1500 g of absolute ethanol and 1000 g of pure water and stir to dissolve. Then weigh 1488 g of boric acid and add it to a mixed solution of 1500 absolute ethanol and 1000 g of pure water and stir evenly. Mix the above two solutions and stir evenly to obtain the zirconium boride precursor sol. Weigh 1100 g of resorcinol and 1600 g of formaldehyde (formalin solution), add them to a mixed solution of 3000 g of absolute ethanol and 1000 g of pure water and stir to dissolve to obtain the phenolic sol.

[0037] (2) Mix the zirconium boride precursor sol and the phenolic sol evenly, impregnate the pre-oxidized fiber reinforcement (size 450 mm × 450 mm × 60 mm) under vacuum until no more bubbles are discharged, and then place it in an oven at 90 °C for curing for 24 h to obtain the wet gel of the zirconium boride-carbon hybrid aerogel material organic precursor.

[0038] (3) Immerse the wet gel of the zirconium boride-carbon hybrid aerogel material organic precursor in sufficient ethanol for solvent replacement, change the ethanol every 48 h, and perform a total of 4 rounds of replacement. Then, leave the replaced wet gel to dry at room temperature until the mass no longer changes, obtaining the zirconium boride-carbon hybrid aerogel organic precursor.

[0039] (4) Pyrolytic carbonize the zirconium boride-carbon hybrid aerogel organic precursor in an argon atmosphere by heating it to 1700 °C at a heating rate of 5 °C / min and holding for 3 h to obtain the zirconium boride-carbon hybrid aerogel composite material.

[0040] The density of the finally prepared zirconium boride-carbon hybrid aerogel composite is 0.48 g / cm 3 , and the residual weight after treatment at 1000 °C for 1000 s in an air atmosphere is not less than 90%, and the linear shrinkage after treatment at 2000 °C for 1000 s in an inert atmosphere is not more than 3%.

[0041] Example 3

[0042] A preparation method of a zirconium boride-carbon hybrid aerogel composite, comprising the following steps:

[0043] (1) Weigh 1780 zirconium oxychloride octahydrate and 192 g of citric acid, add them to a mixed solution of 1500 g of absolute ethanol and 1000 g of pure water, stir and dissolve. Then weigh 1488 g of boric acid, add it to a mixed solution of 1500 absolute ethanol and 1000 g of pure water, stir evenly. Mix the above two solutions and stir evenly to obtain a zirconium boride precursor sol. Weigh 1880 g of phenol and 1600 g of formaldehyde (formalin solution), add them to a mixed solution of 3000 g of absolute ethanol and 1000 g of pure water, stir and dissolve to obtain a phenolic sol.

[0044] (2) Mix the zirconium boride precursor sol and the phenolic sol evenly, impregnate a pre-oxidized fiber reinforcement (size 450 mm × 450 mm × 60 mm) under vacuum until no more bubbles are discharged, and then place it in an oven at 90 °C for 96 h to cure, obtaining a wet gel of the zirconium boride-carbon hybrid aerogel material organic precursor.

[0045] (3) Immerse the wet gel of the zirconium boride-carbon hybrid aerogel material organic precursor in sufficient ethanol for solvent replacement, change the ethanol every 48 h, and perform a total of 6 replacements. Then air-dry the replaced wet gel at room temperature until the mass no longer changes, obtaining a zirconium boride-carbon hybrid aerogel organic precursor.

[0046] (4) Heat the zirconium boride-carbon hybrid aerogel organic precursor in an argon atmosphere at a heating rate of 1 °C / min to 1300 °C and hold for 3 h for pyrolytic carbonization to obtain a zirconium boride-carbon hybrid aerogel composite.

[0047] The density of the finally prepared zirconium boride-carbon hybrid aerogel composite is 0.45 g / cm 3 , and the residual weight after treatment at 1000 °C for 1000 s in an air atmosphere is not less than 90%, and the linear shrinkage after treatment at 2000 °C for 1000 s in an inert atmosphere is not more than 3%.

[0048] Although the present invention has been disclosed as above by way of examples, it is not intended to limit the present invention. Any appropriate modifications or equivalent replacements made by those of ordinary skill in the art to the technical solutions of the present invention shall be covered within the protection scope of the present invention. The protection scope of the present invention shall be subject to that defined by the claims.

Claims

1. A preparation method of a zirconium boride-carbon hybrid aerogel composite material, characterized in that, It includes the following steps: (1) Prepare zirconium boride precursor sol and phenolic sol; (2) After mixing the zirconium boride precursor sol and the phenolic sol, vacuum-assisted impregnate the pre-oxidized fiber reinforcement, and then place it in an oven for curing to obtain a wet gel of the zirconium boride-carbon hybrid aerogel material organic precursor; (3) Immerse the wet gel of the zirconium boride-carbon hybrid aerogel material organic precursor in ethanol for solvent replacement, and then air-dry until the mass no longer changes to obtain the zirconium boride-carbon hybrid aerogel organic precursor; (4) Pyrolyze and carbonize the zirconium boride-carbon hybrid aerogel organic precursor in an inert atmosphere to obtain the zirconium boride-carbon hybrid aerogel composite material.

2. The preparation method according to claim 1, characterized in that, The phenolic sol in step (1) is one or more of resorcinol-formaldehyde phenolic sol and resorcinol-furfural sol.

3. The preparation method according to claim 1 or 2, characterized in that, In the phenolic sol in step (1), the molar ratio of phenol to aldehyde ranges from 2:1 to 1:

3.

4. The preparation method according to claim 1, characterized in that, The density range of the pre-oxidized fiber reinforcement in step (2) is 0.05 to 0.25 g / cm 3 .

5. The preparation method according to claim 1, characterized in that, In step (2), the curing temperature ranges from 80 to 120 °C, and the total curing duration is 24 to 96 h.

6. The preparation method according to claim 1, characterized in that, The solvent replacement method in step (3) is: replace ethanol every 48 h, and a total of 3 to 6 rounds of replacement are carried out.

7. The preparation method according to claim 1, characterized in that, In step (4), the pyrolysis carbonization temperature ranges from 1300 to 1700 °C.

8. The preparation method according to claim 1 or 7, characterized in that, In step (4), the heating rate of pyrolysis carbonization is 1 to 5 °C / min.

9. A zirconium boride-carbon hybrid aerogel composite material, characterized in that, Prepared by the preparation method described in any one of claims 1-9.

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