Antioxidant composite ceramic aerogel and preparation method thereof

Abstract

The application discloses an antioxidant composite ceramic aerogel and a preparation method thereof, and belongs to the technical field of composite ceramic aerogels.The main body of the antioxidant composite ceramic aerogel is a silicon nitride aerogel, the nanostructure of the silicon nitride aerogel is one of one-dimensional silicon nitride nanowires and two-dimensional silicon nitride nanobands or a combination of the two nanostructures, and a mullite coating and a copper-nickel metal coating are sequentially coated on the nanostructure of the silicon nitride aerogel from inside to outside.The application can solve the technical problem that the prior art cannot prepare silicon nitride ceramic aerogels which can stably serve in a high-temperature oxygen environment at low cost and in batches.

Description

Technical Field

[0001] This invention belongs to the field of composite ceramic aerogel technology, specifically relating to an antioxidant composite ceramic aerogel and its preparation method. Background Technology

[0002] Ceramic aerogels possess ultra-low density, ultra-high porosity, ultra-low thermal conductivity, and high-temperature resistance, making them a promising next-generation thermal insulation material. Currently, ceramic aerogels are mainly divided into two categories: oxide ceramic aerogels and non-oxide ceramic aerogels (such as nitride, carbide, and boride aerogels). Oxide aerogels suffer from high-temperature crystallization embrittlement and high-temperature structural collapse, limiting their service temperature to below 1000℃. In contrast, among non-oxide ceramic aerogels, silicon nitride aerogels exhibit excellent mechanical flexibility and high-temperature resistance. However, silicon nitride aerogels face two major problems: firstly, existing preparation techniques are costly and unsuitable for large-scale production; secondly, they exhibit oxidation failure in oxygen-rich environments above 1100℃, hindering long-term stable service. For example, the journal *Materials Research Express* (2019, 1250c4) reported that Yang et al. found that silicon nitride nanowires rapidly oxidize and fail in oxygen-rich environments above 1100℃, completely transforming into silicon dioxide at 1500℃. Only by solving these two problems can we achieve the large-scale preparation of ceramic aerogels with higher temperature resistance.

[0003] Currently, there are few reported patents and papers on simultaneously achieving low-cost, large-scale preparation of silicon nitride aerogels and improved antioxidant properties. For example, Chinese invention patent CN 108328586 A – a compressible and recoverable silicon nitride aerogel and its preparation method – uses siloxane as a raw material, first preparing a silicon nitride nanowire film on graphite paper, then peeling the film off the graphite paper and stacking them layer by layer to form a silicon nitride aerogel. This method is not suitable for large-scale aerogel preparation. Another example is Chinese invention patent CN 113929470 A – a silicon nitride nanoribbon aerogel and its preparation method – which mixes and solidifies short-cut carbon fibers and polysiloxane, then heats it in nitrogen to prepare silicon nitride nanofiber aerogel. This method is suitable for large-scale preparation of silicon nitride aerogels, but the prepared aerogel will undergo oxidation failure in an oxygen-rich environment at 1100℃. Chinese invention patent CN 113929470 A, "Preparation Method of Anisotropic Porous Silicon Nitride Ceramics and Aerogels with Directionally Arranged Nanoarrays," obtains silicon nitride aerogels by chemically treating, freeze-drying, and carbothermic reducing natural wood. While this method uses low-cost natural wood as a raw material, the freeze-drying process consumes a lot of energy, resulting in high preparation costs. Furthermore, the aerogels prepared cannot be used in an aerobic environment at temperatures exceeding 1100℃. Chinese invention patent CN 112047742 A, "A Low-Cost Preparation Method of Large-Size Silicon Nitride Nanoribbon Aerogels," directly synthesizes silicon nitride using low-cost silicon powder and nitrogen as raw materials. Although this method achieves low-cost preparation, the oxidation resistance temperature of the prepared aerogels is only 1000℃. Chinese invention patent CN 111205106 A, entitled "Silicon Nitride@Carbon Microwave Absorbing Foam and Its Preparation Method and Application", and the journal ACS Nano (2024, 4c03816) reported a method of coating pyrolytic carbon onto the surface of silicon nitride aerogel using hydrothermal and chemical vapor deposition methods. Although the two methods improve the heat resistance temperature of silicon nitride aerogel to some extent in an inert atmosphere, the pyrolytic carbon coating layer will be rapidly oxidized in an aerobic environment above 400°C.

[0004] In summary, research on the low-cost, large-scale preparation of silicon nitride ceramic aerogels that can stably operate in high-temperature and oxygen-rich environments is still in a technological gap stage. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide an antioxidant composite ceramic aerogel and its preparation method, so as to solve the technical problem that it is impossible to prepare silicon nitride ceramic aerogels that can be stably used in high-temperature oxygen environments at low cost and in large quantities.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] This invention provides an antioxidant composite ceramic aerogel, wherein the main body of the antioxidant composite ceramic aerogel is silicon nitride aerogel, and the nanostructure of the silicon nitride aerogel is one of the following nanostructures: one-dimensional silicon nitride nanowires and two-dimensional silicon nitride nanoribbons, or a combination of two nanostructures.

[0008] The nanostructure of the silicon nitride aerogel is coated with a mullite coating and a copper-nickel metal coating from the inside out.

[0009] In one embodiment, after the melting temperature of silica is reached, the silica in the mullite coating forms a flowing molten silica liquid, and the alumina nanoparticles in the mullite coating, the copper oxide nanoparticles formed by the oxidation of the copper-nickel metal coating, and the nickel oxide nanoparticles dissolve in the molten silica liquid to jointly form an oxide film.

[0010] In one embodiment, the elemental composition of the antioxidant composite ceramic aerogel is nitrogen, silicon, aluminum, oxygen, copper and nickel.

[0011] This invention also provides a method for preparing the aforementioned antioxidant composite ceramic aerogel, comprising the following steps:

[0012] S1: Mix polysiloxane sol, plant sugar, foaming agent, metal catalyst and water, stir and let stand to solidify, then perform the first drying to form a dry gel, and then perform the first heat treatment to obtain silicon nitride aerogel.

[0013] S2: Prepare a mullite mixed sol, immerse silicon nitride aerogel in the mullite mixed sol, remove it after adsorption saturation, and then perform a second drying and a second heat treatment to obtain mullite / silicon nitride composite ceramic aerogel.

[0014] S3: Mix copper-containing compound, nickel-containing compound and water to obtain a mixed solution. Immerse mullite / silicon nitride composite ceramic aerogel into the mixed solution. After adsorption saturation, remove it and perform a third drying and a third heat treatment to obtain copper-nickel / mullite / silicon nitride composite ceramic aerogel.

[0015] In one embodiment, in S1, the mass ratio of the polysiloxane sol, plant sugar, foaming agent, metal catalyst and water is (1-30):(1-30):(1-8):(1-5):(80-200).

[0016] In one embodiment, in S1, the plant sugar is one or a combination of several of glucose, sucrose, starch, fructose, maltose and xylose;

[0017] The foaming agent is one or a combination of several of the following: animal protein foaming agent, plant protein foaming agent, sodium bicarbonate, nitrosamine, and sodium dodecyl sulfate.

[0018] The metal catalyst is one or a combination of several of the following: platinum catalyst, palladium catalyst, copper catalyst, and nickel catalyst.

[0019] In one embodiment, in S2, the mullite mixed sol is prepared from aluminum nitrate, tetraethyl orthosilicate, boric acid and deionized water;

[0020] The mass ratio of aluminum nitrate, tetraethyl orthosilicate, boric acid, and deionized water is (0.1–1):(1–10):(0.05–1):(100–300).

[0021] In one embodiment, in step S3, the mass ratio of the copper-containing compound, the nickel-containing compound, and water is (0.1–10):(1–10):(50–200).

[0022] In one embodiment, in step S3, the copper-containing compound is one or a combination of copper nitrate, copper chloride, and copper sulfate; the nickel compound is one or a combination of nickel nitrate, nickel chloride, and nickel sulfate.

[0023] In one embodiment, in step S1, the temperature of the first drying step is 30–150°C;

[0024] The temperature of the first heat treatment is 1350-1650℃, and the first heat treatment is carried out in a nitrogen-containing atmosphere.

[0025] In step S2, the temperature of the second drying is 40–200°C; the temperature of the second heat treatment is 500–1200°C, and the second heat treatment is carried out in an air atmosphere.

[0026] In step S3, the temperature of the third drying is 35–180°C; the temperature of the third heat treatment is 600–1200°C, and the third heat treatment is carried out in a reducing atmosphere.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] This invention provides an antioxidant composite ceramic aerogel. The main component of the aerogel is silicon nitride, and the structural components constituting the silicon nitride aerogel are one-dimensional silicon nitride nanowires and two-dimensional silicon nitride nanoribbons. Compared with granular and nanosheet structural components, these nanowires and nanoribbons with a large aspect ratio have higher mechanical deformation capacity, giving the silicon nitride aerogel excellent compression resilience and bending resistance. Furthermore, a mullite coating and a copper-nickel metal coating (a mullite and copper-nickel metal binary antioxidant coating) are sequentially coated from the inside to the outside on the nanostructure surface of the silicon nitride aerogel. The outer copper-nickel metal coating utilizes the sweating cooling of the metal to achieve active thermal protection, effectively reducing the direct damage of high temperature to the aerogel structure; at the same time, the uniformly coated inner mullite coating can block the contact between oxygen and silicon nitride, preventing oxidation and performance degradation, effectively improving the high-temperature antioxidant performance of the aerogel, increasing the antioxidant temperature by 300°C compared to pure silicon nitride aerogel. Therefore, the antioxidant composite ceramic aerogel prepared by this invention has higher temperature resistance and antioxidant properties, and can be stably used in high-temperature oxygen-containing environments.

[0029] In practical use, the silica in the mullite coating forms a flowing molten liquid. The nano-alumina particles in the mullite and the copper oxide and nickel oxide nanoparticles formed by the oxidation of the metal coating dissolve in the molten liquid and act as anchors, increasing the viscosity of the molten silica. The molten liquid not only enhances the bonding between the coating and silicon nitride, but also gives the coating a certain self-healing ability, which can fill in some uncoated areas, thus better protecting the silicon nitride. In addition, the nano-alumina particles in the mullite and the nanoparticles formed by the oxidation of the metal coating together with the molten silica form a dense composite oxide film, thereby improving its ability to resist the impact of high-temperature airflow or high-temperature flame.

[0030] Another aspect of this invention provides a method for preparing antioxidant composite ceramic aerogels. Using low-cost plant sugars and polysiloxanes for foaming, precursor frameworks containing carbon and silicon sources of any size can be prepared. Silicon nitride aerogels can be rapidly and efficiently prepared using a carbothermal reduction method. A mullite and copper-nickel binary antioxidant coating is applied to the surface of the silicon nitride nanostructure using a precursor impregnation and pyrolysis method. The prepared aerogel, due to its high porosity, exhibits excellent adsorption of the precursor solution or sol for the coating, facilitating efficient coating and thus promoting the large-scale preparation of composite ceramic aerogels. In summary, the preparation method provided by this invention has advantages such as low cost and large-scale preparation. Attached Figure Description

[0031] Figure 1 An optical photograph of the antioxidant composite ceramic aerogel prepared in Example 1 of the present invention;

[0032] Figure 2This is an EDS energy dispersive spectroscopy (EDS) analysis diagram of the antioxidant composite ceramic aerogel prepared in Example 1 of the present invention;

[0033] Figure 3 Figure (a) is an optical photograph of the antioxidant composite ceramic aerogel prepared in Example 1 after being sprayed with a butane spray gun (about 1300°C); Figures (b-f) are infrared thermal images of the antioxidant composite ceramic aerogel prepared in Example 1 after being sprayed with a butane spray gun (about 1300°C) for 1, 5, 10, 15 and 20 minutes, respectively.

[0034] Figure 4 The images show a comparison of SEM images of silicon nitride aerogel and antioxidant composite ceramic aerogel prepared in Example 1 of the present invention after oxidation treatment at 1400℃ for 30 min; wherein, Figure a is the SEM image of silicon nitride aerogel after oxidation treatment at 1400℃ for 30 min; Figure b is the SEM image of antioxidant composite ceramic aerogel after oxidation treatment at 1400℃ for 30 min.

[0035] Figure 5 The image shows a TGA comparison of the silicon nitride aerogel and the antioxidant composite ceramic aerogel prepared in Example 1 of this invention. Detailed Implementation

[0036] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0037] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0038] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0039] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0040] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0041] This invention provides an antioxidant composite ceramic aerogel and its preparation method.

[0042] The present invention provides an antioxidant composite ceramic aerogel, wherein the main body of the antioxidant composite ceramic aerogel is silicon nitride aerogel, and the surface of the nanostructure of silicon nitride aerogel is coated with a copper-nickel metal and mullite dual antioxidant coating.

[0043] More specifically, the structural components constituting the silicon nitride aerogel are one-dimensional silicon nitride nanowires and two-dimensional silicon nitride nanoribbons; in other words, the nanostructure of the silicon nitride aerogel is one of the two nanostructures, namely one-dimensional silicon nitride nanowires and two-dimensional silicon nitride nanoribbons, or a combination of both. Furthermore, the nanostructure of the silicon nitride aerogel is coated with a mullite coating and a copper-nickel metal coating sequentially from the inside out. The main elemental composition of the aforementioned antioxidant composite ceramic aerogel is nitrogen, silicon, aluminum, oxygen, copper, and nickel.

[0044] In one embodiment, an antioxidant composite ceramic aerogel is provided, the main component of which is silicon nitride. The structural components constituting the silicon nitride aerogel are one-dimensional silicon nitride nanowires and two-dimensional silicon nitride nanoribbons. A copper-nickel metal and mullite dual-element antioxidant coating is uniformly coated on the surface of the silicon nitride aerogel's nanostructure. The main elemental composition of the antioxidant composite ceramic aerogel is nitrogen, silicon, aluminum, oxygen, copper, and nickel. The above-mentioned antioxidant composite ceramic aerogel has extremely low thermal conductivity, ranging from 0.025 to 0.042 W / mK; it also exhibits excellent antioxidant properties, with no significant change in its microstructure after treatment in an aerobic environment at 1400°C for 30 minutes.

[0045] In one implementation, such as Figure 1 As shown, the antioxidant composite ceramic aerogel is a grayish-white three-dimensional block with a density of 15–50 mg / cm³. 3 .

[0046] This invention provides a method for preparing an antioxidant composite ceramic aerogel, comprising the following steps: preparing a polysiloxane sol, mixing the sol with plant sugar, a foaming agent, a metal catalyst, and water in a certain proportion, stirring and allowing it to stand and solidify, drying to form a dry gel, and then subjecting it to high-temperature heat treatment to obtain a silicon nitride aerogel; immersing the prepared silicon nitride aerogel in a mullite mixed sol, removing it, and then subjecting it to drying and high-temperature heat treatment to obtain a mullite / silicon nitride composite ceramic aerogel; mixing a copper-containing compound, a nickel-containing compound, and water in a certain proportion, immersing the prepared mullite / silicon nitride composite ceramic aerogel in the mixed solution, removing it, and then subjecting it to drying and high-temperature heat treatment to obtain a copper-nickel / mullite / silicon nitride composite ceramic aerogel, i.e., an antioxidant composite ceramic aerogel.

[0047] The specific steps of the above preparation method are as follows:

[0048] Step 1) Prepare polysiloxane sol. Mix the sol with plant sugar, foaming agent, metal catalyst and water in a certain proportion. Stir for 30 minutes and let it stand to solidify for 24 hours. Dry at 30-150℃ to form a dry gel. Then, perform high-temperature heat treatment at 1350-1650℃ in a nitrogen atmosphere to obtain silicon nitride aerogel.

[0049] Step 2) Prepare a mullite mixed sol, immerse the silicon nitride aerogel prepared in step 1 into the mixed sol, remove it, dry it at 40-200℃ and heat it in air at 500-1200℃ to obtain a mullite / silicon nitride composite ceramic aerogel.

[0050] Step 3) Mix the copper-containing compound, the nickel-containing compound and water in a certain proportion. Immerse the mullite / silicon nitride composite ceramic aerogel prepared in Step 2 into the mixed solution. After taking it out, dry it at 35-180℃ and heat treat it at 600-1200℃ in a reducing atmosphere to obtain copper-nickel / mullite / silicon nitride composite ceramic aerogel, that is, antioxidant composite ceramic aerogel.

[0051] The specific dosage and process conditions are as follows:

[0052] In step 1), the process of preparing the polysiloxane sol is as follows: silicone resin, ethanol and water are mixed evenly in a mass ratio of 3:10:8 to obtain the polysiloxane sol.

[0053] In step 1), the mass ratio of the polysiloxane, plant sugar, foaming agent, metal catalyst, and water is (1-30):(1-30):(1-8):(1-5):(80-200); the plant sugar can be one or a combination of glucose, sucrose, starch, fructose, maltose, and xylose; the foaming agent can be one or a combination of animal protein foaming agent, plant protein foaming agent, sodium bicarbonate, nitrosamine, and sodium dodecyl sulfate; the metal catalyst can be one or a combination of platinum catalyst, palladium catalyst, copper catalyst, and nickel catalyst; the nitrogen-containing atmosphere can be one or a combination of nitrogen and ammonia; and the high-temperature heat treatment temperature is 1350-1650℃.

[0054] In step 2), the mullite mixed sol is prepared from aluminum nitrate, tetraethyl orthosilicate, boric acid and deionized water; the mass ratio of aluminum nitrate, tetraethyl orthosilicate, boric acid and water in the mullite mixed sol is (0.1~1):(1~10):(0.05~1):(100~300).

[0055] In step 3), the copper-containing compound can be one or a combination of copper nitrate, copper chloride, and copper sulfate; the nickel-containing compound can be one or a combination of nickel nitrate, nickel chloride, and nickel sulfate; the ratio of the copper-containing compound, the nickel-containing compound, and water is (0.1-10):(1-10):(50-200).

[0056] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0057] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0058] Example 1:

[0059] Step 1) Prepare 8g of polysiloxane sol, mix the sol with 10g of glucose, 5g of animal protein foaming agent, 3g of platinum catalyst and 180g of water, stir for 30min and let stand to solidify for 24h, dry at 100℃ to form a dry gel, and then heat treat at 1550℃ in a nitrogen atmosphere to obtain silicon nitride aerogel.

[0060] Step 2) Mix 0.5g aluminum nitrate, 5g tetraethyl orthosilicate, 0.2g boric acid and 150g water evenly to prepare a mullite mixed sol. Immerse the silicon nitride aerogel prepared in Step 1 into the mixed sol. After taking it out, dry it at 160℃ and heat-treat it at 900℃ in air atmosphere to obtain mullite / silicon nitride composite ceramic aerogel.

[0061] Step 3) Mix 1g of copper chloride, 3g of nickel nitrate and 180g of water evenly. Immerse the mullite / silicon nitride composite ceramic aerogel prepared in Step 2 into the mixed solution. After taking it out, dry it at 80℃ and heat treat it at 1000℃ in an argon-hydrogen mixed atmosphere to obtain copper-nickel / mullite / silicon nitride composite ceramic aerogel, that is, antioxidant composite ceramic aerogel.

[0062] The prepared antioxidant composite ceramic aerogel has a density of 20 mg / cm³. 3 The thermal conductivity at room temperature is 0.028 W / mK. Figure 1 As can be seen, the antioxidant composite ceramic aerogel appears as a grayish-white three-dimensional block. (The last sentence appears to be incomplete and possibly refers to a different topic.) Figure 2 It is evident that the main elements of the antioxidant composite ceramic aerogel are nitrogen, silicon, aluminum, oxygen, copper, and nickel. (From...) Figure 3 It is evident that the antioxidant composite ceramic aerogel maintains excellent thermal insulation performance even after being subjected to a butane flame at 1300℃; the temperature on the back of the aerogel stabilizes at 95℃ after 20 minutes of rinsing. Figure 4 It is evident that the microstructure of the antioxidant composite ceramic aerogel remains unchanged after treatment in an aerobic environment at 1400℃ for 30 minutes. From... Figure 4 A comparison of Figures (a) and (b) shows that the microstructure of the uncoated silicon nitride aerogel undergoes melting deformation (i.e., silicon nitride nanowires or nanoribbons are oxidized to silicon dioxide in a high-temperature aerobic environment, and silicon dioxide melts into a liquid state at high temperature). However, the aerogel coated with an antioxidant coating (i.e., antioxidant composite ceramic aerogel) can still maintain its original microstructure after heat treatment in the same high-temperature aerobic environment. This is because the mullite and copper-nickel dual antioxidant coating on the surface of the silicon nitride aerogel nanostructure provides antioxidant effect.

[0063] Figure 5This is a comparison of the thermogravimetric curves of silicon nitride aerogel and antioxidant composite ceramic aerogel (i.e., silicon nitride aerogel coated with an antioxidant coating). It can be seen that pure silicon nitride aerogel undergoes rapid oxidation in an aerobic environment above 1100℃; while the antioxidant composite ceramic aerogel remains unoxidized even at 1500℃ (oxidation at 300-900℃ is the oxidation process of the copper-nickel coating). This figure can be compared with... Figure 4 The combined results demonstrate that the antioxidant composite ceramic aerogel exhibits superior high-temperature antioxidant properties compared to pure silicon nitride aerogel.

[0064] Example 2:

[0065] Step 1) Prepare 8g of polysiloxane sol, mix the sol with 15g of sucrose, 3g of plant protein foaming agent, 3g of copper catalyst and 120g of water, stir for 30min and let stand to solidify for 24h, dry at 120℃ to form a dry gel, and then heat treat at 1500℃ in a nitrogen atmosphere to obtain silicon nitride aerogel.

[0066] Step 2) Mix 0.5g aluminum nitrate, 8g tetraethyl orthosilicate, 0.3g boric acid and 180g water evenly to prepare a mullite mixed sol. Immerse the silicon nitride aerogel prepared in Step 1 into the mixed sol. After taking it out, dry it at 120℃ and heat treat it at 1100℃ in air atmosphere to obtain mullite / silicon nitride composite ceramic aerogel.

[0067] Step 3) Mix 0.5 g of copper chloride, 4 g of nickel nitrate and 120 g of water evenly. Immerse the mullite / silicon nitride composite ceramic aerogel prepared in Step 2 into the mixed solution. After taking it out, dry it at 75°C and heat treat it at 1000°C in an argon-hydrogen mixed atmosphere to obtain copper-nickel / mullite / silicon nitride composite ceramic aerogel, that is, antioxidant composite ceramic aerogel.

[0068] Example 3:

[0069] Step 1) Prepare 15g of polysiloxane sol, mix the sol with 20g fructose, 6g sodium bicarbonate, 1g platinum catalyst and 140g water, stir for 30min and let stand to solidify for 24h, dry at 130℃ to form a dry gel, and then heat treat at 1450℃ in a nitrogen atmosphere to obtain silicon nitride aerogel.

[0070] Step 2) Mix 1g aluminum nitrate, 6g tetraethyl orthosilicate, 0.1g boric acid and 200g water evenly to prepare a mullite mixed sol. Immerse the silicon nitride aerogel prepared in Step 1 into the mixed sol. After taking it out, dry it at 100℃ and heat-treat it at 800℃ in air atmosphere to obtain mullite / silicon nitride composite ceramic aerogel.

[0071] Step 3) Mix 4g of copper chloride, 4g of nickel nitrate and 180g of water evenly. Immerse the mullite / silicon nitride composite ceramic aerogel prepared in Step 2 into the mixed solution. After taking it out, dry it at 150℃ and heat treat it at 700℃ in an argon-hydrogen mixed atmosphere to obtain copper-nickel / mullite / silicon nitride composite ceramic aerogel, that is, antioxidant composite ceramic aerogel.

[0072] Example 4:

[0073] Step 1) Prepare 10g of polysiloxane sol, mix the sol with 20g xylose, 4g plant protein foaming agent, 3g nickel catalyst and 100g water, stir for 30min and let stand to solidify for 24h, dry at 60℃ to form a dry gel, and then heat treat at 1580℃ in a nitrogen atmosphere to obtain silicon nitride aerogel.

[0074] Step 2) Mix 0.6g aluminum nitrate, 3g tetraethyl orthosilicate, 0.3g boric acid and 220g water evenly to prepare a mullite mixed sol. Immerse the silicon nitride aerogel prepared in Step 1 into the mixed sol. After taking it out, dry it at 120℃ and heat treat it at 750℃ in air atmosphere to obtain mullite / silicon nitride composite ceramic aerogel.

[0075] Step 3) Mix 4g of copper chloride, 10g of nickel nitrate and 150g of water evenly. Immerse the mullite / silicon nitride composite ceramic aerogel prepared in Step 2 into the mixed solution. After taking it out, dry it at 80℃ and heat treat it at 700℃ in an argon-hydrogen mixed atmosphere to obtain copper-nickel / mullite / silicon nitride composite ceramic aerogel, that is, antioxidant composite ceramic aerogel.

[0076] Example 5:

[0077] Step 1) Prepare 1g of polysiloxane sol, mix the sol with 10g of maltose, 1g of sodium dodecyl sulfate, 1g of nickel catalyst and 80g of water, stir for 30min and let stand to solidify for 24h, dry at 30℃ to form a dry gel, and then heat treat at 1350℃ in a nitrogen atmosphere to obtain silicon nitride aerogel.

[0078] Step 2) Mix 0.1g aluminum nitrate, 1g tetraethyl orthosilicate, 0.05g boric acid and 100g water evenly to prepare a mullite mixed sol. Immerse the silicon nitride aerogel prepared in Step 1 into the mixed sol. After taking it out, dry it at 40℃ and heat-treat it at 500℃ in air atmosphere to obtain mullite / silicon nitride composite ceramic aerogel.

[0079] Step 3) Mix 0.1g copper sulfate, 1g nickel chloride and 50g water evenly. Immerse the mullite / silicon nitride composite ceramic aerogel prepared in Step 2 into the mixed solution. After taking it out, dry it at 35℃ and heat treat it at 600℃ in an argon-hydrogen mixed atmosphere to obtain copper-nickel / mullite / silicon nitride composite ceramic aerogel, that is, antioxidant composite ceramic aerogel.

[0080] Example 6:

[0081] Step 1) Prepare 30g of polysiloxane sol, mix the sol with 30g of starch, 8g of nitrosamine, 5g of palladium catalyst and 200g of water, stir for 30min and let stand to solidify for 24h, dry at 150℃ to form a dry gel, and then heat treat at 1650℃ in a nitrogen atmosphere to obtain silicon nitride aerogel.

[0082] Step 2) Mix 1g aluminum nitrate, 10g tetraethyl orthosilicate, 1g boric acid and 300g water evenly to prepare a mullite mixed sol. Immerse the silicon nitride aerogel prepared in Step 1 into the mixed sol. After taking it out, dry it at 200℃ and heat treat it at 1200℃ in air atmosphere to obtain mullite / silicon nitride composite ceramic aerogel.

[0083] Step 3) Mix 10g copper nitrate, 10g nickel sulfate and 200g water evenly. Immerse the mullite / silicon nitride composite ceramic aerogel prepared in Step 2 into the mixed solution. After taking it out, dry it at 180℃ and heat treat it at 1200℃ in an argon-hydrogen mixed atmosphere to obtain copper-nickel / mullite / silicon nitride composite ceramic aerogel, that is, antioxidant composite ceramic aerogel.

[0084] In summary, the antioxidant composite ceramic aerogel prepared by this invention has excellent compression resilience and bending resistance, thermal insulation performance and antioxidant properties. At the same time, it can be prepared at low cost and on a large scale, and has great application potential in thermal insulation fields such as aerospace, high-temperature kilns and fire protection engineering.

[0085] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. An antioxidant composite ceramic aerogel, characterized in that, The main body of the antioxidant composite ceramic aerogel is silicon nitride aerogel, and the nanostructure of the silicon nitride aerogel is one of the following nanostructures: one-dimensional silicon nitride nanowires and two-dimensional silicon nitride nanoribbons, or a combination of the two nanostructures. The nanostructure of the silicon nitride aerogel is coated with a mullite coating and a copper-nickel metal coating from the inside out. The preparation method of the antioxidant composite ceramic aerogel includes the following steps: S1: Mix polysiloxane sol, plant sugar, foaming agent, metal catalyst and water, stir and let stand to solidify, then perform the first drying to form a dry gel, and then perform the first heat treatment to obtain silicon nitride aerogel. S2: Prepare a mullite mixed sol, immerse the silicon nitride aerogel in the mullite mixed sol, remove it and dry it a second time, and then perform a second heat treatment to obtain a mullite / silicon nitride composite ceramic aerogel. S3: Mix copper-containing compound, nickel-containing compound and water to obtain a mixed solution. Immerse mullite / silicon nitride composite ceramic aerogel in the mixed solution, remove it and dry it for the third time. Then perform a third heat treatment to obtain copper-nickel / mullite / silicon nitride composite ceramic aerogel.

2. A method for preparing the antioxidant composite ceramic aerogel according to claim 1, characterized in that, Includes the following steps: S1: Mix polysiloxane sol, plant sugar, foaming agent, metal catalyst and water, stir and let stand to solidify, then perform the first drying to form a dry gel, and then perform the first heat treatment to obtain silicon nitride aerogel. S2: Prepare a mullite mixed sol, immerse the silicon nitride aerogel in the mullite mixed sol, remove it and dry it a second time, and then perform a second heat treatment to obtain a mullite / silicon nitride composite ceramic aerogel. S3: Mix copper-containing compound, nickel-containing compound and water to obtain a mixed solution. Immerse mullite / silicon nitride composite ceramic aerogel in the mixed solution, remove it and dry it for the third time. Then perform a third heat treatment to obtain copper-nickel / mullite / silicon nitride composite ceramic aerogel.

3. The preparation method of the antioxidant composite ceramic aerogel according to claim 2, characterized in that, In S1, the mass ratio of the polysiloxane sol, plant sugar, foaming agent, metal catalyst and water is (1~30):(1~30):(1~8):(1~5):(80~200).

4. The preparation method of the antioxidant composite ceramic aerogel according to claim 2, characterized in that, In S1, the plant sugar is one or a combination of several of glucose, sucrose, starch, fructose, maltose and xylose; The foaming agent is one or a combination of several of the following: animal protein foaming agent, plant protein foaming agent, sodium bicarbonate, nitrosamine, and sodium dodecyl sulfate. The metal catalyst is one or a combination of several of the following: platinum catalyst, palladium catalyst, copper catalyst, and nickel catalyst.

5. The method for preparing the antioxidant composite ceramic aerogel according to claim 2, characterized in that, In S2, the mullite mixed sol is prepared from aluminum nitrate, tetraethyl orthosilicate, boric acid and deionized water; The mass ratio of aluminum nitrate, tetraethyl orthosilicate, boric acid and deionized water is (0.1~1):(1~10):(0.05~1):(100~300).

6. The method for preparing the antioxidant composite ceramic aerogel according to claim 2, characterized in that, In step S3, the mass ratio of the copper-containing compound, the nickel-containing compound, and water is (0.1~10):(1~10):(50~200).

7. The method for preparing the antioxidant composite ceramic aerogel according to claim 2, characterized in that, In step S3, the copper-containing compound is one or a combination of copper nitrate, copper chloride, and copper sulfate; the nickel compound is one or a combination of nickel nitrate, nickel chloride, and nickel sulfate.

8. The method for preparing the antioxidant composite ceramic aerogel according to claim 2, characterized in that, In step S1, the temperature of the first drying step is 30~150℃; The temperature of the first heat treatment is 1350~1650 ℃, and the first heat treatment is carried out in a nitrogen-containing atmosphere; In step S2, the temperature of the second drying is 40~200 ℃; the temperature of the second heat treatment is 500~1200 ℃, and the second heat treatment is carried out in an air atmosphere; In step S3, the temperature of the third drying is 35~180 ℃; the temperature of the third heat treatment is 600~1200 ℃, and the third heat treatment is carried out in a reducing atmosphere.

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