CN106938934B - A kind of ultra-high temperature ceramic-based aerogel material and preparation method thereof - Google Patents

Abstract

The present invention relates to a kind of ultra-temperature ceramic-based aerogel materials and preparation method thereof, the preparation method includes: to be dissolved in solvent and obtain mixed solution soluble transition metal presoma, organosilicon, soluble carbon source and boron source, precursor sol is obtained in 30~80 DEG C of reactions, or soluble transition metal presoma, organosilicon and soluble carbon source are dissolved in solvent and obtain mixed solution, precursor sol is obtained in 30~80 DEG C of reactions；Gained composite precursor is solidified, aeroge precast body is obtained；Gained aeroge precast body is carried out to ceramic conversion under atmosphere protection, at 1000~1800 DEG C and obtains ultra-temperature ceramic-based aerogel material.

Description

A kind of ultra-high temperature ceramic-based aerogel material and preparation method thereof

technical field

The invention relates to an ultra-high temperature ceramic-based aerogel material, in particular to a method for preparing an ultra-high temperature ceramic-based aerogel material by controlling the composition of a precursor sol of ultra-high temperature ceramics and its drying process, which belongs to non- The technical field of oxide ceramic material preparation.

Background technique

Ultra-high temperature ceramics refers to a class of ceramic materials that can maintain physical and chemical stability in high temperature environments (>1800 ° C) and reaction atmospheres. compounds and nitrides. Ultra-high temperature ceramics have the advantages of high melting point, low saturated vapor pressure, and good chemical and microstructural stability in thermal ablation environments. Therefore, ultra-high temperature ceramics are considered to be powerful for high-temperature structural components and thermal protection system components of hypersonic aircraft. candidate material.

The more traditional preparation method of ultra-high temperature ceramics is to use the corresponding oxide powder, carbon black or graphite, boron oxide, etc. as raw materials, after ball milling and mixing, under the protection of atmosphere (vacuum or argon atmosphere), heat treatment in a high temperature furnace That is, the powder of the ultra-high temperature ceramic is obtained. Due to the strong covalent bonds and low bulk diffusion coefficient of ultra-high temperature ceramics, the densification of ultra-high temperature ceramics is difficult, and generally requires the assistance of external pressure or sintering aids to achieve densification at lower temperatures. As a common second phase in ultra-high temperature ceramics, silicon carbide is usually introduced into ultra-high temperature ceramic powder in powder form through ball milling process, and then densified ultra-high temperature ceramic is obtained through subsequent heat treatment. Since the particle size of the powder used is micron or submicron, it is difficult to mix the two phases of silicon carbide and ultra-high temperature ceramics uniformly. In recent years, a large number of patents and literatures have reported the preparation of ultra-high temperature ceramic powders using the liquid phase precursor method, which can obtain multi-phase powders in which ultra-high temperature ceramics and silicon carbide are uniformly mixed. However, most of the current research is limited to the preparation of nano-scale ultra-high temperature ceramic single-phase and composite powders by liquid precursor method, and only a few works have combined foaming technology to prepare ultra-high temperature porous ceramics. It may be due to the fact that the precursors are easily powdered during the drying and heat-treating ceramic conversion process.

In the traditional method of preparing aerogel materials, the drying process needs to be strictly controlled to prevent cracking and pulverization of the material, and more stringent preparation processes such as supercritical drying and freeze drying are required.

SUMMARY OF THE INVENTION

In view of the above-mentioned problems and demands existing in the prior art, the purpose of the present invention is to provide an ultra-high temperature ceramic-based aerogel material and a preparation method thereof, so as to expand the application of the current liquid phase precursor method in the field of ultra-high temperature ceramic preparation and make up for The current application of aerogel materials in the ultra-high temperature field is blank.

In one aspect, the present application provides a method for preparing an ultra-high temperature ceramic-based aerogel material, wherein the ultra-high temperature ceramic-based aerogel material is a composite aerogel material, the composition of which includes transition metal borides and/or transition metal carbides material, and silicon carbide, the preparation method includes the steps:

1) Dissolve the soluble transition metal precursor, organosilicon, soluble carbon source and boron source in a solvent to obtain a mixed solution, and react at 30-80 °C to obtain a precursor sol, wherein the carbon element in the carbon source and the transition metal precursor are The molar ratio of the transition metal element in the boron source is 5 to 10:1, the molar ratio of the boron element in the boron source to the transition metal element in the transition metal precursor is 2 to 10:1, the carbon element in the carbon source and the silicon source. The molar ratio of silicon element is 3:1 to 6:1; or

Dissolving soluble transition metal precursor, organosilicon, and soluble carbon source in a solvent to obtain a mixed solution, and reacting at 30-80 °C to obtain a precursor sol, wherein the carbon element in the carbon source and the transition metal in the transition metal precursor are The molar ratio of the elements is 3-10:1, and the molar ratio of the carbon element in the carbon source to the silicon element in the silicon source is 3:1-6:1;

2) curing the obtained composite precursor (precursor sol) to obtain an aerogel preform;

3) The obtained aerogel preform is subjected to ceramic transformation at 1000-1800° C. under the protection of atmosphere to obtain an ultra-high temperature ceramic-based aerogel material.

The above preparation method uses the liquid phase precursor technology to prepare the ultra-high temperature ceramic material, obtains the xerogel of the ultra-high temperature ceramic material by controlling the composition of the precursor and the drying process of the precursor, and uses the precursor sol to dehydrate and solidify during the heat preservation process. The xerogel is obtained through subsequent high-temperature ceramic transformation to obtain an ultra-high-temperature ceramic-based bulk aerogel material. In the above preparation method, the block-shaped aerogel material can be obtained only by conventional atmospheric drying, which is easy to operate and has a wide range of applications.

Preferably, the transition metal is at least one of zirconium, hafnium and tantalum.

Preferably, the transition metal precursor is at least one of transition metal oxychloride, transition metal hydroxide, and an organic complex formed by transition metal and organic ligand, wherein the organic ligand is preferably an alcohol or ketones.

Preferably, the organosilicon is at least one of silicate monomer and hydroxyl-terminated polydimethylsiloxane, wherein the silicate monomer is preferably ethyl orthosilicate and/or orthosiloxane methyl acid.

Preferably, in step 1), the solvent is at least one of ethanol, methanol and acetone.

Preferably, the soluble carbon source is a polyalcohol, preferably at least one of glycerol, pentaerythritol, xylitol, and furfuryl alcohol; the boron source is boric acid and/or boric acid ester, wherein the boric acid The ester is preferably tri-n-butyl borate and/or triethyl borate.

Preferably, the transition metal boride is zirconium boride and/or hafnium boride, and the transition metal carbide is at least one of zirconium carbide, hafnium carbide, and tantalum carbide.

Preferably, in step 1), the precursor sol is obtained by reacting at 30-80° C. for 0.5-4 hours.

Preferably, in step 2), the curing is performed under normal pressure, and the curing temperature is 40-120°C.

In another aspect, the present application provides an ultra-high temperature ceramic-based aerogel material prepared by the above preparation method.

Description of drawings

Figure a in Figure 1 is a real photo of the zirconium boride/silicon carbide aerogel obtained in Example 1 through a high-temperature carbothermic reduction reaction; Figure b in Figure 1 is a high-temperature carbothermic reduction reaction obtained in Example 12. The physical photo of zirconium carbide/silicon carbide aerogel;

Figure (a) in Figure 2 is the XRD diffraction pattern of the zirconium boride/silicon carbide aerogel obtained in Example 1 through a high-temperature carbothermic reduction reaction;

Figure (b) in Figure 2 is the XRD diffraction pattern of the zirconium carbide/silicon carbide aerogel obtained in Example 12 through a high temperature carbothermic reduction reaction;

Fig. 3 is the SEM image of the zirconium boride/silicon carbide aerogel obtained by the high temperature carbothermic reduction reaction obtained in Example 1;

Figure 4 is the SEM images of the materials obtained in Comparative Example 1 (Figure a) and Comparative Example 2 (Figure b);

FIG. 5 is an XRD diffraction pattern of the zirconium carbide/zirconium boride/silicon carbide aerogel obtained in Example 20 through a high-temperature carbothermic reduction reaction.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and the following embodiments. It should be understood that the accompanying drawings and the following embodiments are only used to illustrate the present invention, but not to limit the present invention.

An embodiment of the present invention provides an ultra-high temperature ceramic-based aerogel material, the ultra-high temperature ceramic-based aerogel material includes transition metal borides (hereinafter also referred to as borides) and/or transition metal carbides ( Also referred to as carbide hereinafter), and silicon carbide, for example, aerogel materials composed of transition metal carbide and/or transition metal boride and silicon carbide (ie, transition metal boride/silicon carbide composite aerogel material, transition metal carbide/silicon carbide composite aerogel material, transition metal boride/transition metal carbide/silicon carbide composite aerogel material). The transition metal involved in the present invention can be at least one of zirconium, hafnium and tantalum. In one example, the transition metal boride is at least one of zirconium boride and hafnium boride. In another example, the transition metal carbide is at least one of zirconium carbide, hafnium carbide, and tantalum carbide.

In the transition metal boride/silicon carbide composite aerogel material, the molar ratio of transition metal boride to silicon carbide may be 1:(1-4). In the transition metal carbide/silicon carbide composite aerogel material, the molar ratio of transition metal carbide to silicon carbide may be 1:(1-4). In the transition metal boride/transition metal carbide/silicon carbide composite aerogel material, the molar ratio of transition metal boride, transition metal carbide and silicon carbide can be 1:(1~4):(1~4) .

The microstructure of the ultra-high temperature ceramic-based aerogel material is an open-pore mesh structure, the pore diameter can be 1-20 μm, and the porosity can be 60-85%. The density of the ultra-high temperature ceramic-based aerogel material may be 0.2˜1 g/cm ³ .

In one embodiment of the present invention, a liquid phase precursor technique is used to prepare the ultra-high temperature ceramic-based aerogel material. Specifically, the aerogel preforms of boride/silicon carbide, carbide/silicon carbide, boride/carbide/silicon carbide are obtained by controlling the composition of the precursor sol of the ultra-high temperature ceramic and its drying process, so that the The boride/silicon carbide, carbide/silicon carbide, boride/carbide/silicon carbide aerogel preforms are subjected to ceramic transformation (for example, ceramic transformation under atmosphere protection at 1000-1800 ° C) to obtain the corresponding ultra-high temperature Ceramic based aerogel materials.

Preparation of Precursor Sol

In one embodiment, in order to prepare a transition metal boride/silicon carbide composite aerogel material, or a transition metal boride/transition metal carbide/silicon carbide composite aerogel material, a soluble transition metal precursor, an organosilicon ( Silicon source), soluble carbon source and boron source are dissolved in the solvent to form a mixed solution. In another embodiment, in order to prepare the transition metal carbide/silicon carbide composite aerogel material, the soluble transition metal precursor, the organosilicon and the soluble carbon source are dissolved in a solvent to form a mixed solution. "Solubility" here means being soluble in the above-mentioned solvent. When forming the mixed solution, the order of adding the raw materials is not limited, as long as the raw materials are mixed uniformly.

The soluble transition metal precursor can be an oxychloride or hydroxide containing the transition metal, or an organic complex formed by the metal and alcohol (such as ethanol, n-butanol, isopropanol), ketone (such as acetylacetone), etc. . The organosilicon can be at least one of ethyl orthosilicate, methyl orthosilicate, and hydroxyl-terminated polydimethylsiloxane. The soluble carbon source can be at least one of glycerol, pentaerythritol, xylitol, and furfuryl alcohol. The boron source can be at least one of boric acid, tri-n-butyl borate, and triethyl borate. The solvent used can be at least one of ethanol, methanol and acetone.

The above mixed solution is reacted for a period of time to obtain a precursor sol. The reaction temperature may be 30-80°C. The reaction at this temperature can promote the hydrolysis and polycondensation of the precursor. The reaction time may be 0.5 to 4 hours.

The composition of the precursor sol can be controlled by controlling the ratio of each raw material. In one embodiment, the carbon/metal molar ratio of the carbon source to the transition metal precursor is 5-10:1, preferably 6-8:1, and the molar ratio of the boron source to the metal is 2-10:1, preferably 4 to 8:1, and the carbon/silicon molar ratio of the carbon source to the silicon source is 3:1 to 6:1 (preferably 3:1). The aerogel preform prepared by the above formula can be ceramicized at a relatively low temperature (1200-1400 ° C) to obtain a boride/carbide/silicon carbide three-phase composite aerogel material; at a temperature above 1400 ° C, a boride can be obtained. / Silicon carbide aerogel material. In another embodiment, the carbon source/metal molar ratio of the carbon source to the transition metal precursor is 3 to 10:1, preferably 4 to 8:1, and the carbon/silicon molar ratio of the carbon source to the silicon source is 3: 1 to 6:1 (preferably 3:1). By selecting the above-mentioned ratio of raw materials, a precursor sol with a suitable composition can be obtained, and then the aerogel preform can be obtained by subsequent conventional atmospheric drying.

Preparation of aerogel preforms

The precursor sol is cured to obtain an aerogel preform (boride/silicon carbide aerogel preform, carbide/silicon carbide aerogel preform, or boride/carbide/silicon carbide aerogel preform) . The solidification can be carried out under normal atmospheric pressure without the need for severe drying processes such as supercritical drying, freeze drying, and the like. Of course, these drying processes are also possible. In one example, the precursor sol is cured under normal pressure at 40-120° C. (preferably 40-90° C.) for a period of time (eg, 1 hour to 12 hours).

In one example, soluble transition metal precursor and organosilicon are first dissolved in ethanol solvent, then soluble carbon source and boron source are added, and reacted in a water bath at 30-80°C for 0.5-4 hours to obtain a certain viscosity. The precursor of boride/silicon carbide; pour the precursor into a beaker, heat the precursor at 40-120° C. to solidify, and then release the mold naturally to obtain a boride/silicon carbide aerogel preform. In another example, the soluble transition metal precursor and organosilicon are first dissolved in an ethanol solvent, then a soluble carbon source is added, and the carbide with a certain viscosity is obtained after reacting in a water bath at 30-80°C for 0.5-4 hours /Precursor of silicon carbide; pour the precursor into a beaker, heat the precursor at 40-120° C. to solidify it, and then naturally demold it to obtain a carbide/silicon carbide aerogel preform. As a further preferred solution, the molar ratio of B/transition metal element (such as Zr) in the boride/silicon carbide precursor is 2-10, and the molar ratio of C/transition metal element in the boride/silicon carbide precursor is The ratio is 5 to 10, and the C/Si molar ratio is 3. As a further preferred solution, the C/transition metal element molar ratio in the carbide/silicon carbide precursor is 3-10, and the C/Si molar ratio is 3.

Preparation of aerogels

The aerogel preform is subjected to ceramic transformation (carbothermic reduction reaction) to obtain ultra-high temperature ceramic-based aerogel materials (transition metal boride/silicon carbide composite aerogel materials, transition metal carbide/silicon carbide composite aerogel materials , transition metal boride/transition metal carbide/silicon carbide composite aerogel material). In one example, the ceramic transformation is carried out under the protection of the atmosphere at 1000-1800° C. (preferably 1400-1600° C.) for a period of time (eg, 0.5-3 hours). The protective atmosphere can be one of argon and vacuum.

In the present invention, when preparing the ultra-high temperature ceramic aerogel material, the block-shaped aerogel material can be obtained only by conventional normal pressure drying, and the operation is simple and the scope of application is wide. Compared with the traditional methods for preparing aerogel materials (such as supercritical drying, freeze drying, etc.), the present invention has the advantages of simple operation, wide application and the like, and the prepared ultra-high temperature ceramic-based aerogel material has a uniform microscopic pore structure. As well as the advantages of good machinability, it is expected to be used in the ultra-high temperature field.

The following further examples are given to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention, and should not be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art according to the above content of the present invention belong to the present invention. scope of protection. The specific process parameters and the like in the following examples are only an example of a suitable range, that is, those skilled in the art can make selections within the suitable range through the description herein, and are not intended to be limited to the specific numerical values exemplified below.

Example 1

Add 50g of zirconium n-butoxide and 10g of ethyl orthosilicate dropwise to 50g of ethanol and stir and mix. After stirring for 30 minutes, add 44.42g of glycerol according to the C/Zr molar ratio of 10 and the C/Si molar ratio of 3. , according to the B/Zr molar ratio of 3, add 56.95 g of triethyl borate, and react in a water bath at 40 °C for 2 hours to obtain the precursor of zirconium boride/silicon carbide; pour the precursor into a beaker and place it in a 90 °C oven for curing 12 After curing, it was naturally cooled to room temperature and demolded to obtain a zirconium boride/silicon carbide precursor xerogel; the xerogel was placed in an electric furnace and heated to 1600 °C under an argon atmosphere for 2 hours to allow it to proceed. Carbothermal reduction reaction; after the reaction, naturally cooled to room temperature.

In the experiment, the physical photo of the zirconium boride/silicon carbide aerogel obtained by the high-temperature carbothermic reduction reaction is shown in Figure a in Figure 1, its XRD diffraction pattern is shown in Figure 2a, and its microscopic morphology is shown in Figure 3. Show. It can be seen from the figure that a zirconium boride/silicon carbide composite aerogel material with zirconium boride as the main crystal phase can be obtained by the method provided by the present invention, and its microstructure is an open mesh type structure. Its porosity, pore size distribution and density are measured by mercury intrusion method, wherein the porosity is 74.3%, the pore size is 5-20 μm, and the density is 0.6 g/cm ³ .

Example 2

In order to prepare the zirconium boride/silicon carbide aerogel material, 50 g of zirconium n-butoxide and 10 g of ethyl orthosilicate were added dropwise to 50 g of ethanol and stirred and mixed. After stirring for 30 minutes, the C/Zr molar ratio was 10, The C/Si molar ratio is 3, 44.42 g of glycerol is added, and 189.8 g of triethyl borate is added according to the B/Zr molar ratio of 10. The rest of the operations are the same as described in Example 1. The porosity, pore size distribution and density of the prepared aerogel material were measured by mercury intrusion method, wherein the porosity was 80.9%, the pore size was 0.8-1.2 μm, and the density was 0.76 g/cm ³ .

Example 3

In order to prepare the zirconium boride/silicon carbide aerogel material, 50 g of zirconium n-butoxide and 10 g of ethyl orthosilicate were added dropwise to 50 g of ethanol and stirred and mixed. After stirring for 30 minutes, the C/Zr molar ratio was 10, The C/Si molar ratio is 3, 44.42 g of glycerol is added, and 94.9 g of triethyl borate is added according to the B/Zr molar ratio of 5. The rest of the operations are the same as described in Example 1. The porosity, pore size distribution and density of the prepared aerogel material were measured by mercury intrusion method, wherein the porosity was 81.6%, the pore size was 0.6-1.0 μm, and the density was 0.70 g/cm ³ .

Example 4

In order to prepare the zirconium boride/silicon carbide aerogel material, 50 g of zirconium n-butoxide and 10 g of ethyl orthosilicate were added dropwise to 50 g of ethanol and stirred and mixed. After stirring for 30 minutes, the C/Zr molar ratio was 5, The C/Si molar ratio is 3, 15.53 g of furfuryl alcohol is added, and 25.5 g of boric acid is added according to the B/Zr molar ratio of 5. The rest of the operations are the same as described in Example 1. The porosity, pore size distribution and density of the prepared aerogel material were measured by mercury intrusion method, wherein the porosity was 75%, the pore size was 2-10 μm, and the density was 0.83 g/cm ³ .

Example 5

In order to prepare the zirconium boride/silicon carbide aerogel material, 50 g of zirconium n-butoxide and 10 g of ethyl orthosilicate were added dropwise to 50 g of ethanol and stirred and mixed. After stirring for 30 minutes, the C/Zr molar ratio was 5, The C/Si molar ratio is 3, 24.22 g of xylitol is added, and 25.5 g of boric acid is added according to the B/Zr molar ratio of 5. The rest of the operations are the same as described in Example 1. The porosity, pore size distribution and density of the prepared aerogel material were measured by mercury intrusion method, wherein the porosity was 85%, the pore size was 2-10 μm, and the density was 0.63 g/cm ³ .

Example 6

In order to prepare the zirconium boride/silicon carbide aerogel material, 50 g of zirconium n-butoxide and 10 g of methyl orthosilicate were added dropwise to 50 g of ethanol and stirred and mixed. After stirring for 30 minutes, the C/Zr molar ratio was 5, The C/Si molar ratio is 3, 26.05 g of glycerol is added, and 25.5 g of boric acid is added according to the B/Zr molar ratio of 5. The rest of the operations are the same as described in Example 1. The porosity, pore size distribution and density of the prepared aerogel material were measured by mercury intrusion method, wherein the porosity was 81%, the pore size was 2-14 μm, and the density was 0.68 g/cm ³ .

Example 7

In order to prepare the zirconium boride/silicon carbide aerogel material, 50 g of zirconium n-butoxide and 10 g of methyl orthosilicate were added dropwise to 50 g of ethanol and stirred and mixed. After stirring for 30 minutes, the C/Zr molar ratio was 5, When the C/Si molar ratio is 3, 25.83 g of xylitol is added, and 25.5 g of boric acid is added according to the B/Zr molar ratio of 5. The rest of the operations are the same as described in Example 1. The porosity, pore size distribution and density of the prepared aerogel material were measured by mercury intrusion method, wherein the porosity was 87%, the pore size was 0.5-14 μm, and the density was 0.53 g/cm ³ .

Example 8

In order to prepare the hafnium boride/silicon carbide aerogel material, 50 g of hafnium acetylacetonate and 10 g of methyl orthosilicate were added dropwise to 50 g of ethanol and stirred and mixed. After stirring for 30 minutes, the molar ratio of C/Zr was 5, C When the /Si molar ratio is 3, 17.16 g of glycerol is added, and according to the B/Zr molar ratio of 5, 25.5 g of boric acid is added. The rest of the operations were the same as described in Example 1, but the temperature of the carbothermic reduction reaction was selected as 1700°C. The porosity, pore size distribution and density of the prepared aerogel material were measured by mercury intrusion method, wherein the porosity was 80%, the pore size was 0.5-20 μm, and the density was 0.64 g/cm ³ .

Example 9

In order to prepare the hafnium boride/silicon carbide aerogel material, 50 g of hafnium acetylacetonate and 10 g of methyl orthosilicate were added dropwise to 50 g of ethanol and stirred and mixed. After stirring for 30 minutes, the molar ratio of C/Zr was 5, C 17.61 g of xylitol was added at a /Si molar ratio of 3, and 25.5 g of boric acid was added at a B/Zr molar ratio of 5. The rest of the operations were the same as described in Example 1, but the temperature of the carbothermic reduction reaction was selected as 1700°C. The porosity, pore size distribution and density of the prepared aerogel material were measured by mercury intrusion method, wherein the porosity was 75%, the pore size was 0.5-20 μm, and the density was 0.85 g/cm ³ .

Example 10

In order to prepare the hafnium boride/silicon carbide aerogel material, 50 g of hafnium acetylacetonate and 10 g of methyl orthosilicate were added dropwise to 50 g of ethanol and stirred and mixed. After stirring for 30 minutes, the molar ratio of C/Zr was 10, C 30.84 g of xylitol was added at a /Si molar ratio of 3, and 25.5 g of boric acid was added at a B/Zr molar ratio of 5. The rest of the operations were the same as described in Example 1, but the temperature of the carbothermic reduction reaction was selected as 1700°C. The porosity, pore size distribution and density of the prepared aerogel material were measured by mercury intrusion method, wherein the porosity was 81%, the pore size was 0.5-20 μm, and the density was 0.81 g/cm ³ .

Example 11

In order to prepare the hafnium boride/silicon carbide aerogel material, 50g of hafnium acetylacetonate and 10g of methyl orthosilicate were added dropwise to 50g of ethanol and stirred and mixed. After stirring for 30 minutes, the C/Zr molar ratio was 5, C 17.61 g of xylitol was added at a /Si molar ratio of 3, and 51.0 g of boric acid was added at a B/Zr molar ratio of 10. The rest of the operations were the same as described in Example 1, but the temperature of the carbothermic reduction reaction was selected as 1700°C. The porosity, pore size distribution and density of the prepared aerogel material were measured by mercury intrusion method, wherein the porosity was 71%, the pore size was 0.5-20 μm, and the density was 0.96 g/cm ³ .

Example 12

In order to prepare zirconium carbide/silicon carbide aerogel materials, 50 g of zirconium n-butoxide and 10 g of ethyl orthosilicate were added dropwise to 50 g of ethanol and stirred and mixed. After stirring for 30 minutes, according to the C/Zr molar ratio of 3, C The zirconium carbide/silicon carbide precursor was obtained by adding 16.42g glycerol in a molar ratio of 3 to Si and reacting in a water bath at 70°C for 2 hours; the precursor was poured into a beaker and placed in a 90°C oven for curing. After curing, the natural Cool to room temperature and demold to obtain zirconium carbide/silicon carbide precursor xerogel; place the xerogel in an electric furnace and heat it to 1500° C. for 2 hours under an argon atmosphere to perform a carbothermic reduction reaction; after the reaction is completed , naturally cooled to room temperature.

In the experiment, the physical photo of the zirconium carbide/silicon carbide aerogel obtained through the high-temperature carbothermic reduction reaction is shown in Figure b in Figure 1, and its XRD diffraction pattern is shown in Figure 2b. It can be seen from the figure that the zirconium carbide/silicon carbide composite aerogel bulk material with zirconium carbide as the main crystal phase can be obtained by the method provided by the present invention. The porosity, pore size distribution and density of the obtained aerogel were measured by mercury intrusion method, wherein the porosity was 80%, the pore size distribution was 0.8-2 μm, and the density was 0.45 g/cm ³ .

Example 13

In order to prepare zirconium carbide/silicon carbide aerogel materials, 50g of zirconium n-butoxide and 10g of ethyl orthosilicate were added dropwise to 50g of ethanol and stirred and mixed. After stirring for 30 minutes, the molar ratio of C/Zr was 5, C The zirconium carbide/silicon carbide precursor was obtained by adding 24.42 g of glycerol at a molar ratio of /Si to 3 and reacting in a water bath at 70° C. for 2 hours; other operations were the same as those described in Example 12. The porosity, pore size distribution and density of the prepared aerogel material were measured by mercury intrusion method, wherein the porosity was 85%, the pore size was 0.5-10 μm, and the density was 0.40 g/cm ³ .

Example 14

In order to prepare zirconium carbide/silicon carbide aerogel materials, 50 g of zirconium n-butoxide and 10 g of ethyl orthosilicate were added dropwise to 50 g of ethanol and stirred and mixed. After stirring for 30 minutes, according to the C/Zr molar ratio of 3, C The zirconium carbide/silicon carbide precursor was obtained by adding 16.27 g xylitol at a molar ratio of 3 to Si, and reacting in a water bath at 40° C. for 2 hours; the rest of the operations were the same as those described in Example 12. The porosity, pore size distribution and density of the prepared aerogel material were measured by mercury intrusion method, wherein the porosity was 77%, the pore size was 0.5-20 μm, and the density was 0.56 g/cm ³ .

Example 15

In order to prepare zirconium carbide/silicon carbide aerogel materials, 50 g of zirconium n-butoxide and 10 g of ethyl orthosilicate were added dropwise to 50 g of ethanol and stirred and mixed. After stirring for 30 minutes, according to the C/Zr molar ratio of 3, C The zirconium carbide/silicon carbide precursor was obtained by adding 10.53 g of furfuryl alcohol at a molar ratio of /Si to 3, and reacting in a water bath at 40° C. for 2 hours; other operations were the same as those described in Example 12. The porosity, pore size distribution and density of the prepared aerogel material were measured by mercury intrusion method, wherein the porosity was 70%, the pore size was 10-20 μm, and the density was 0.89 g/cm ³ .

Example 16

In order to prepare the hafnium carbide/silicon carbide aerogel material, 50g of hafnium acetylacetonate and 10g of methyl orthosilicate were added dropwise to 50g of ethanol and stirred and mixed. After stirring for 30 minutes, the molar ratio of C/Zr was 5, C/ Si molar ratio of 3 added 17.61 g of xylitol. The rest of the operations were the same as described in Example 12, but the temperature of the carbothermic reduction reaction was selected as 1700°C. The porosity, pore size distribution and density of the prepared aerogel material were measured by mercury intrusion method, wherein the porosity was 76%, the pore size was 1-20 μm, and the density was 0.82 g/cm ³ .

Example 17

In order to prepare the hafnium carbide/silicon carbide aerogel material, 50g of hafnium acetylacetonate and 10g of methyl orthosilicate were added dropwise to 50g of ethanol and stirred and mixed. After stirring for 30 minutes, the molar ratio of C/Zr was 5, C/ The Si molar ratio was 3 and 17.16 g of glycerol was added. The rest of the operations were the same as described in Example 12, but the temperature of the carbothermic reduction reaction was selected as 1700°C. The porosity, pore size distribution and density of the prepared aerogel material were measured by mercury intrusion method, wherein the porosity was 65%, the pore size was 1-20 μm, and the density was 0.98 g/cm ³ .

Example 18

In order to prepare the tantalum carbide/silicon carbide aerogel material, 50g of tantalum ethoxide and 10g of ethyl orthosilicate were added dropwise to 50g of ethanol and stirred and mixed. After stirring for 30 minutes, according to the C/Zr molar ratio of 5, C/Si A molar ratio of 3 was added with 23.30 g of glycerol. The rest of the operations were the same as described in Example 12, but the temperature of the carbothermic reduction reaction was selected as 1800°C. The porosity, pore size distribution and density of the prepared aerogel material were measured by mercury intrusion method, wherein the porosity was 65%, the pore size was 1-20 μm, and the density was 0.98 g/cm ³ .

Example 19

In order to prepare zirconium carbide/silicon carbide aerogel materials, 50g of zirconium n-butoxide and 10g of ethyl orthosilicate were added dropwise to 50g of ethanol and stirred and mixed. After stirring for 30 minutes, the molar ratio of C/Zr was 10, C The zirconium carbide/silicon carbide precursor was obtained by adding 49 g of glycerol at a molar ratio of 3 to Si at a 70° C. water bath for 2 hours; the rest of the operations were the same as described in Example 12. The porosity, pore size distribution and density of the prepared aerogel material were measured by mercury intrusion method, wherein the porosity was 85%, the pore size was 0.5-2 μm, and the density was 0.35 g/cm ³ .

Example 20 In order to prepare a zirconium carbide/zirconium boride/silicon carbide composite aerogel material, 50 g of zirconium n-butoxide and 10 g of ethyl orthosilicate were added dropwise to 50 g of ethanol, stirred and mixed, and after stirring for 30 minutes, according to C. The /Zr molar ratio is 10, the C/Si molar ratio is 3, 44.42 g of glycerol is added, and 56.95 g of triethyl borate is added according to the B/Zr molar ratio of 3. The rest of the operations were the same as described in Example 1, but the temperature of the heat treatment was selected as 1300°C. The prepared aerogel material is composed of three phases of zirconium carbide, zirconium boride and silicon carbide, and the XRD diffraction pattern is shown in Figure 5. Its porosity, pore size distribution and density are measured by mercury intrusion method, wherein the porosity is 75%, the pore size is 1-20 μm, and the density is 0.65 g/cm ³ .

Example 21

In order to prepare zirconium carbide/zirconium boride/silicon carbide composite aerogel material, 50g of zirconium n-butoxide and 10g of ethyl orthosilicate were added dropwise to 50g of ethanol and stirred and mixed, and after stirring for 30 minutes, according to C/Zr mole The ratio is 10, the C/Si molar ratio is 6, 64.42 g of glycerol is added, and 56.95 g of triethyl borate is added according to the B/Zr molar ratio of 3. The rest of the operations were the same as described in Example 1, but the temperature of the heat treatment was selected as 1200°C. The prepared aerogel material is composed of three phases of zirconium carbide, zirconium boride and silicon carbide, and its porosity, pore size distribution and density are measured by mercury intrusion method, wherein the porosity is 79%, the pore size is 1-20 μm, and the density is 1-20 μm. was 0.61 g/cm ³ .

Comparative Example 1

In order to prepare zirconium boride/silicon carbide aerogel, 50g of zirconium n-butoxide and 10g of ethyl orthosilicate were added dropwise to 50g of ethanol and stirred and mixed. After stirring for 30 minutes, the C/Zr molar ratio was 2, C 24.42 g of glycerol was added at a /Si molar ratio of 3, and 37.96 g of triethyl borate was added according to a B/Zr molar ratio of 2. The rest of the operations are the same as in Example 1, and the zirconium boride/silicon carbide aerogel material cannot be prepared by using this formula. Its microstructure is shown in Figure a in Figure 4, which is a dense structure, not a porous structure. The porosity measured by mercury porosimetry was 46%.

Comparative Example 2

In order to prepare zirconium carbide/silicon carbide aerogel materials, 50g of zirconium n-butoxide and 10g of ethyl orthosilicate were added dropwise to 50g of ethanol and stirred and mixed. After stirring for 30 minutes, the C/Zr molar ratio was 2, C The zirconium carbide/silicon carbide precursor was obtained by adding 14.42 g of glycerol at a molar ratio of /Si to 3 and reacting in a water bath at 80° C. for 2 hours; other operations were the same as those described in Example 12. The zirconium carbide/silicon carbide aerogel material cannot be prepared with this formula. Its microstructure is shown in Figure b in Figure 4, which is a dense structure, not a porous structure. The porosity measured by mercury porosimetry was 35%.

Claims (13)

1. a kind of preparation method of ultra-temperature ceramic-based aerogel material, which is characterized in that the ultra-temperature ceramic-based aeroge Material is aerogel composite, and composition includes transition metal boride and/or transition metal carbide and silicon carbide, The preparation method includes the following steps:

1) soluble transition metal presoma, organosilicon, soluble carbon source and boron source are dissolved in solvent and obtain mixed solution, 30~80 DEG C of reactions obtain precursor sol, wherein the transition metal member in the carbon and transition metal precursor in carbon source The molar ratio of element is 5~10:1, and the molar ratio of the transition metal element in boron element and transition metal precursor in boron source is 2 ~10:1, the molar ratio of the element silicon in carbon and silicon source in carbon source are 3:1~6:1；Or

Soluble transition metal presoma, organosilicon and soluble carbon source are dissolved in solvent and obtain mixed solution, 30~80 DEG C reaction obtains precursor sol, wherein the transition metal element in carbon and transition metal precursor in carbon source rubs , than being 3~10:1, the molar ratio of the element silicon in carbon and silicon source in carbon source is 3:1~6:1 for you；

2) gained composite precursor is solidified under normal pressure, solidification temperature is 40~120 DEG C, obtains aeroge precast body；

3) gained aeroge precast body is carried out under atmosphere protection, at 1000~1800 DEG C to ceramic conversion and obtains superhigh temperature pottery Porcelain base aerogel material, the microstructure of ultra-temperature ceramic-based aerogel material are aperture mesh-type structure, and aperture is 1~20 μm, porosity is 60~85%, and density is 0.2~1 g/cm³。

2. preparation method according to claim 1, which is characterized in that the transition metal is zirconium, hafnium, at least one in tantalum Kind.

3. preparation method according to claim 1 or 2, which is characterized in that the transition metal precursor is transition metal At least one of the organic coordination compound that oxychlorination things, transition metal hydroxide and transition metal and organic ligand are formed.

4. preparation method according to claim 3, which is characterized in that the organic ligand is alcohol or ketone.

5. preparation method according to claim 1, which is characterized in that the organosilicon is silicate monomer, terminal hydroxy group is poly- At least one of dimethyl siloxane.

6. preparation method according to claim 5, which is characterized in that the silicate monomer is preferably ethyl orthosilicate And/or methyl orthosilicate.

7. preparation method according to claim 1, which is characterized in that the solvent be ethyl alcohol, methanol, in acetone at least It is a kind of.

8. preparation method according to claim 1, which is characterized in that the solubility carbon source is polyalcohol；The boron source For boric acid and/or borate.

9. preparation method according to claim 8, which is characterized in that it is described solubility carbon source be glycerine, pentaerythrite, At least one of xylitol, furfuryl alcohol.

10. preparation method according to claim 8, it is characterised in that the borate is tri-n-butyl borate and/or boron Triethylenetetraminehexaacetic acid ester.

11. preparation method according to claim 1, which is characterized in that the transition metal boride be zirconium boride and/or Hafnium boride, the transition metal carbide are at least one of zirconium carbide, hafnium carbide, tantalum carbide.

12. preparation method according to claim 1, which is characterized in that small in 30~80 DEG C of reactions 0.5~4 in step 1) When obtain precursor sol.

13. a kind of ultra-temperature ceramic-based aerogel material of the preparation of the preparation method as described in any one of claims 1 to 12.

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