A method for preparing a honeycomb titanium nitride ceramic aerogel

Abstract

The application relates to a preparation method of a honeycomb-shaped titanium nitride (TiN) ceramic aerogel. The method combines a sol-gel method and a carbothermal reduction-nitriding process, and comprises the following steps: firstly, preparing titanium dioxide (TiO2) nanorods through a hydrothermal method; then mixing the TiO2 nanorods with an organic sol system; and finally preparing a new honeycomb-shaped ultralight TiN ceramic aerogel through a sol-gel, supercritical drying and carbothermal reduction-nitriding process. The prepared TiN ceramic aerogel has a large BET specific surface area and a very low thermal conductivity, and exhibits excellent mechanical properties, heat insulation properties and oxidation resistance, so that the mechanical strength and high-temperature resistance of the TiN ceramic aerogel in an oxygen-containing environment are improved, and the TiN ceramic aerogel has great application value in the fields of aerospace, energy storage and building thermal insulation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aerogel material preparation, and relates to a preparation method of honeycomb-shaped titanium nitride (TiN) ceramic aerogel. BACKGROUND

[0002] Aerogel material is a three-dimensional lightweight porous material composed of nanoparticles or polymer molecular chains. It has attracted widespread attention in high-temperature insulation applications due to its high-temperature resistance, low thermal conductivity and other characteristics. However, traditional oxide aerogels have many weaknesses, such as insufficient thermal stability, easy phase transition and particle sintering. In contrast, nitride materials have high melting point, high hardness, high thermal stability and wear resistance, making them suitable for extreme application conditions such as high temperature, high pressure and corrosive environment. Among them, TiN porous ceramic material has attracted widespread attention due to its excellent high-temperature resistance, high strength and high thermal insulation properties. However, current TiN porous ceramics face challenges such as high sintering temperature, high production cost, poor purity and low porosity. Han L, Dong L, Zhang H, et al. (Journal of the European Ceramic Society, 2021, 41(10): 5127-5137.) used TiO2 and chitosan powder as starting materials to prepare TiN aerogel by freeze casting and carbon thermal reduction nitriding method. However, the specific surface area of the TiN aerogel prepared by this method is too small, only 80-167 m 2 / g, and the thermal conductivity at room temperature is relatively high, about 0.1 W / (m K), and the preparation method is complex, the energy consumption is high, and it is not easy to scale up production. Rao Huashang et al. (Cheng, Qi, Zhouhong Yin, Zhenxiao Pan, et al. ACS Applied Energy Materials, 2021, 4(8): 7599-7610.) used tetrabutyl titanate and graphene oxide as raw materials to prepare graphene oxide / TiN aerogel by freeze drying and carbon thermal reduction nitriding method. However, this method is high in cost and complex in preparation process, and is not easy to industrialize. Huangshuangneng et al. (CN202410574363.X) directly added metal catalyst and carbon source in TiO2 aerogel, and prepared carbon nitride titanium aerogel by carbon nitriding treatment. However, the specific surface area of the carbon nitride titanium aerogel obtained by this method is only 358.7 m 2 / g, and the operation is complex and not suitable for large-scale production. SUMMARY

[0003] The application aims to improve the deficiencies of the prior art and provides a preparation method of honeycomb TiN ceramic aerogel, which comprises the following steps: first, TiO2 nanorods are prepared by a hydrothermal method; then, the TiO2 nanorods are mixed with an organic sol to prepare a honeycomb TiN ceramic aerogel by a sol-gel method, supercritical drying and carbon thermal reduction.

[0004] The application provides a preparation method of honeycomb TiN ceramic aerogel, which comprises the following steps:

[0005] (1) a titanium source, water and acid are uniformly mixed at a certain molar ratio at 20-30 DEG C, TiO2 nanorods are obtained through hydrothermal reaction and oven drying;

[0006] (2) phenol, formaldehyde, sodium carbonate and water are uniformly mixed and stirred at a certain molar ratio at 20-30 DEG C to obtain an organic sol;

[0007] (3) the TiO2 nanorods obtained in step (1) and the organic sol obtained in step (2) are uniformly mixed and stirred at a certain mass ratio at 20-30 DEG C, and the mixture is placed at 50-100 DEG C for 12-72 h for gel aging, and then solvent replacement is performed;

[0008] (4) the wet gel obtained in step (3) is subjected to carbon dioxide supercritical drying to obtain a precursor aerogel;

[0009] (5) the precursor aerogel obtained in step (4) is subjected to heat treatment under the protection of a nitrogen atmosphere to obtain honeycomb TiN ceramic aerogel.

[0010] Preferably, the acid in step (1) is one or a mixture of several of hydrochloric acid, sulfuric acid, phosphoric acid, boric acid and oxalic acid; the mass concentration of the acid is 5-50%; the titanium source is one or a mixture of several of tetrabutyl titanate, n-propyl titanate, n-butyl titanate and ethyl titanate; the titanium source, water and acid are mixed at a molar ratio of 1:(10-20):(30-40); the hydrothermal reaction temperature is 150-300 DEG C, and the hydrothermal reaction time is 1-5 h; the oven drying temperature is 40-60 DEG C, and the drying time is 12-72 h.

[0011] Preferably, the phenol in step (2) is one or a mixture of several of catechol, resorcinol, hydroquinone, cresol or pyrogallol; the aldehyde is one or a mixture of several of formaldehyde, acetaldehyde, butyraldehyde, cinnamyl aldehyde or anisaldehyde; and the phenol, aldehyde, sodium carbonate and water are mixed in a molar ratio of 1:(2-6):(0.1-0.8):(1-5).

[0012] Preferably, the TiO2 nanorods and the organic sol are mixed uniformly in a mass ratio of 1:(0.1-0.8) in step (3); the displacement solvent is one or a mixture of several of ethanol, methanol, acetone, n-pentanol or isopropyl alcohol; and the displacement is performed 5-15 times at intervals of 6-12 h.

[0013] Preferably, the carbon dioxide supercritical drying in step (4) uses carbon dioxide as the drying medium, and the drying temperature is 40-70℃, the drying pressure is 8-15 MPa, the gas release rate is 4-16 L / min, and the drying time is 5-14 h.

[0014] Preferably, the heat treatment in step (5) is performed at a temperature of 1000-1500℃, a heating rate of 2-8℃ / min, and a holding time of 2-5 h.

[0015] Advantages:

[0016] The method and the method for preparing a honeycomb TiN ceramic aerogel prepared by the method have the following characteristics:

[0017] (1) The preparation process of the application is simple, raw materials are easy to obtain, energy consumption is low, it is efficient, low cost, and can be produced on a large scale.

[0018] (2) The application provides a method for preparing a honeycomb TiN ceramic aerogel, which has low thermal conductivity, high porosity, high specific surface area, strong oxidation resistance and other characteristics. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a sample diagram of the honeycomb TiN ceramic aerogel obtained in Example 1 before and after the 1300℃ butane lance experiment.

[0020] Figure 2 is an X-ray diffraction diagram of the honeycomb TiN ceramic aerogel obtained in Example 2.

[0021] Figure 3 is a scanning electron microscope diagram of the honeycomb TiN ceramic aerogel obtained in Example 3. DETAILED DESCRIPTION

[0022] The application will be further described below in conjunction with examples, but the scope of protection is not limited thereto.

[0023] Example 1

[0024] Tetrabutyl titanate, water, hydrochloric acid (5wt%) were mixed at a molar ratio of 1:10:30 at 20°C and stirred uniformly, and then hydrothermal treatment was performed at 150°C for 5h, and then it was placed in an oven at 40°C and dried for 72h to obtain TiO2nanorods. Then, catechol, formaldehyde, sodium carbonate, water were mixed at a molar ratio of 1:2:0.1:1 at 20°C and stirred uniformly to obtain an organic sol. The TiO2nanorods and the organic sol were mixed at a mass ratio of 1:0.1 at 20°C and stirred uniformly, and then it was placed at 50°C for 72h until it gelled, and then it was subjected to ethanol solvent replacement, wherein the replacement was performed 5 times at an interval of 12h. The wet gel was subjected to carbon dioxide supercritical drying to obtain a precursor aerogel, wherein the drying temperature was 40°C, the drying pressure was 8MPa, the air release rate was 4L / min, and the drying time was 14h. Finally, the obtained precursor aerogel was subjected to heat treatment in a nitrogen atmosphere, wherein the heat treatment temperature was 1000°C, the heating rate was 2°C / min, and the holding time was 5h. Figure 1 Figure 1 is a sample diagram of the honeycomb-shaped TiN ceramic aerogel prepared before and after the 1300°C butane torch experiment. As can be seen from the figure, the shape of the aerogel remains unchanged after the 1300°C butane torch test, without any shrinkage or cracks. After characterization and testing, the aerogel is a pure-phase TiN ceramic aerogel material, and its specific surface area is as high as 515.5m2 / g, and its thermal conductivity at room temperature is only 0.048W / (m·K). The material was characterized by scanning electron microscopy, and it was found that the sample was obviously honeycomb-shaped and had a uniform pore structure, which was beneficial to improving the thermal insulation performance of the material.

[0025] Example 2

[0026] The n-propyl titanate, water, sulfuric acid (10wt%) were mixed in a molar ratio of 1:20:40 at 25°C and stirred uniformly, and then hydrothermally treated at 300°C for 1h, and then placed in an oven at 45°C for drying for 48h to obtain TiO2nanorods. Then the resorcinol, acetaldehyde, sodium carbonate, water were mixed in a molar ratio of 1:6:0.8:5 at 25°C and stirred uniformly to obtain an organic sol. The TiO2nanorods and the organic sol were mixed in a mass ratio of 1:0.8 at 25°C and stirred uniformly, and then placed at 100°C for 12h for gelation, and then subjected to methanol solvent replacement, wherein the replacement times were 12 times, and the interval was 6h each time. The wet gel was subjected to carbon dioxide supercritical drying to obtain a precursor aerogel, wherein the drying temperature was 70°C, the drying pressure was 15MPa, the air release rate was 16L / min, and the drying time was 5h. Finally, the obtained precursor aerogel was subjected to heat treatment in a nitrogen atmosphere, wherein the heat treatment temperature was 1500°C, the heating rate was 8°C / min, and the holding time was 2h. The prepared honeycomb-like TiN ceramic aerogel was subjected to a 1300°C butane spray gun test, and the shape was unchanged without any shrinkage or cracks. Figure 2 The X-ray diffraction pattern of the prepared honeycomb-like TiN ceramic aerogel was obtained, and it can be seen from the figure that the diffraction peak is consistent with the standard spectrum of TiN, proving that the sample is a pure-phase TiN ceramic aerogel material. After characterization and testing, the specific surface area of the material is as high as 513.8m 2 / g, and the thermal conductivity at room temperature is only 0.051W / (m·K). The material was characterized by using a scanning electron microscope, and it was found that the sample was obviously honeycomb-like and had a uniform pore structure, which was beneficial to improve the heat insulation performance of the material.

[0027] Example 3

[0028] Ti(OBu)4, water, phosphoric acid (50wt%) were mixed in a molar ratio of 1:12:38 at 30°C and stirred uniformly, and then hydrothermally treated at 200°C for 4h, and then placed in a 50°C oven for drying for 36h to obtain TiO2nanorods. Then, hydroquinone, butyl aldehyde, sodium carbonate, water were mixed in a molar ratio of 1:3:0.2:3 at 30°C and stirred uniformly to obtain an organic sol. The TiO2nanorods and the organic sol were mixed in a mass ratio of 1:0.3 at 30°C and stirred uniformly, and then placed at 60°C for 48h until it gelled, and then subjected to acetone solvent replacement, wherein the replacement times were 8 times, and the interval was 9h each time. The wet gel was subjected to carbon dioxide supercritical drying to obtain a precursor aerogel, wherein the drying temperature was 50°C, the drying pressure was 10MPa, the air release rate was 8L / min, and the drying time was 12h. Finally, the obtained precursor aerogel was subjected to heat treatment in a nitrogen atmosphere, wherein the heat treatment temperature was 1200°C, the heating rate was 4°C / min, and the holding time was 4h. The prepared honeycomb-like TiN ceramic aerogel was subjected to a 1300°C butane torch test, and the shape was unchanged without any shrinkage or cracks. After characterization and testing, the aerogel was a pure-phase TiN ceramic aerogel material, and the specific surface area was as high as 515.6m2 / g, and the thermal conductivity at room temperature was only 0.046W / (m·K), Figure 3 The scanning electron microscope image of the honeycomb-like TiN ceramic aerogel is shown in the figure, and it can be seen from the figure that the sample is obviously honeycomb-like, and has a uniform pore structure, which is beneficial to improve the heat insulation performance of the material.

[0029] Example 4

[0030] Ti(OEt)4, H2O, H3BO3 (20wt%) were mixed in a molar ratio of 1:15:32 at 35 °C and stirred uniformly, and then hydrothermally treated at 250 °C for 2 h, and then placed in a 55 °C oven for drying for 24 h to obtain TiO2nanorods. Then, cresol, cinnamaldehyde, Na2CO3, H2O were mixed in a molar ratio of 1:4:0.6:2 at 35 °C and stirred uniformly to obtain an organic sol. The TiO2nanorods and the organic sol were mixed in a mass ratio of 1:0.6 at 35 °C and stirred uniformly, and then placed at 80 °C for 36 h until it gelled, and then subjected to n-pentanol solvent replacement, wherein the replacement was performed 9 times at an interval of 8 h. The wet gel was subjected to carbon dioxide supercritical drying to obtain a precursor aerogel, wherein the drying temperature was 60 °C, the drying pressure was 12 MPa, the air release rate was 10 L / min, and the drying time was 7 h. Finally, the obtained precursor aerogel was subjected to heat treatment in a nitrogen atmosphere, wherein the heat treatment temperature was 1300 °C, the heating rate was 5 °C / min, and the holding time was 3.5 h. The prepared honeycomb-like TiN ceramic aerogel was subjected to a 1300 °C butane torch test, and the shape was unchanged without any shrinkage or cracks. After characterization and testing, the aerogel was a pure-phase TiN ceramic aerogel material, and the specific surface area was as high as 514.7 m2 / g, and the thermal conductivity at room temperature was only 0.050 W / (m·K). The material was characterized by scanning electron microscopy, and it was found that the sample was obviously honeycomb-like and had a uniform pore structure, which was conducive to improving the thermal insulation performance of the material.

[0031] Example 5

[0032] Tetrabutyl titanate, water, oxalic acid (30wt%) were mixed in a molar ratio of 1:18:35 at 40℃ and stirred uniformly, and then hydrothermally treated at 280℃ for 3h, and then placed in a 60℃ oven for drying for 12h to obtain TiO2nanorods. Then, phloroglucinol, anisaldehyde, sodium carbonate, water were mixed in a molar ratio of 1:5:0.5:4 at 40℃ and stirred uniformly to obtain an organic sol. The TiO2nanorods and the organic sol were mixed in a mass ratio of 1:0.5 at 40℃ and stirred uniformly, and then placed at 90℃ for 24h until it gelled, and then subjected to isopropanol solvent replacement, wherein the replacement times were 10 times, and the interval was 7h each time. The wet gel was subjected to carbon dioxide supercritical drying to obtain a precursor aerogel, wherein the drying temperature was 55℃, the drying pressure was 13MPa, the air release rate was 14L / min, and the drying time was 9h. Finally, the obtained precursor aerogel was subjected to heat treatment in a nitrogen atmosphere, wherein the heat treatment temperature was 1400℃, the heating rate was 6℃ / min, and the holding time was 3h. The prepared honeycomb-like TiN ceramic aerogel was subjected to a 1300℃ butane spray test, and the shape was unchanged without any shrinkage or cracks. After characterization and testing, the aerogel was a pure-phase TiN ceramic aerogel material, and the specific surface area was as high as 514.7m2 / g, and the thermal conductivity at room temperature was only 0.047W / (m·K). The material was characterized by scanning electron microscopy, and it was found that the sample was obviously honeycomb-like, and had a uniform pore structure, which was beneficial to improve the heat insulation performance of the material.

Claims

1. A method for preparing a honeycomb-shaped titanium nitride ceramic aerogel, comprising the following steps: (1) mixing a titanium source, water and acid in a certain molar ratio at 20-30 ℃ to obtain TiO2 nanorods through a hydrothermal reaction and oven drying; (2) mixing phenol, aldehyde, sodium carbonate and water in a certain molar ratio at 20-30 ℃ to obtain an organic sol; (3) mixing the TiO2 nanorods obtained in step (1) and the organic sol obtained in step (2) in a mass ratio of 1:(0.1-0.8) at 20-30 ℃, stirring uniformly, placing at 50-100 ℃ for 12-72 h for gel aging, and then performing solvent replacement; (4) performing carbon dioxide supercritical drying on the wet gel obtained in step (3) to obtain a precursor aerogel; and (5) performing heat treatment on the precursor aerogel obtained in step (4) under nitrogen atmosphere protection to obtain a honeycomb-shaped titanium nitride TiN ceramic aerogel. In step (1), the acid is one or a mixture of several of hydrochloric acid, sulfuric acid, phosphoric acid, boric acid or oxalic acid; the mass concentration of the acid is 5-50%; the titanium source is one or a mixture of several of tetrabutyl titanate, n-propyl titanate, n-butyl titanate or ethyl titanate; the titanium source, water and acid are mixed in a molar ratio of 1:(10-20):(30-40); the hydrothermal reaction temperature is 150-300 ℃, and the hydrothermal reaction time is 1-5 h; the oven drying temperature is 40-60 ℃, and the drying time is 12-72 h. In step (2), the phenol is one or a mixture of several of o-dihydroxybenzene, m-dihydroxybenzene, p-dihydroxybenzene, cresol or pyrogallol; the aldehyde is one or a mixture of several of formaldehyde, acetaldehyde, butyl aldehyde, cinnamyl aldehyde or anisaldehyde; and the phenol, aldehyde, sodium carbonate and water are mixed in a molar ratio of 1:(2-6):(0.1-0.8):(1-5). In step (3), the replacement solvent is one or a mixture of several of ethanol, methanol, acetone, n-pentanol or isopropyl alcohol; the replacement is performed 5-15 times, and each time interval is 6-12 h. In step (4), the carbon dioxide supercritical drying uses carbon dioxide as the drying medium, the drying temperature is 40-70 ℃, the drying pressure is 8-15 MPa, the air release rate is 4-16 L / min, and the drying time is 5-14 h. In step (5), the heat treatment temperature is 1000-1500 ℃, the heating rate is 2-8 ℃ / min, and the holding time is 2-5 h. ​ ​ ​ ​ ​ 2. The method of claim 1, wherein ​ 3. The method of claim 1, wherein ​ 4. The method of claim 1, wherein ​ 5. The method of claim 1, wherein ​ 6. The method of claim 1, wherein ​

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