Layered structure ceramic nanofiber aerogel with sheet-shaped bonding points and preparation method of layered structure ceramic nanofiber aerogel
By introducing sheet-like bonding points into the layered structure design of ceramic nanofiber aerogel, the fragility and dust release problems of traditional ceramic aerogels are solved, enabling the preparation of ceramic nanofiber aerogels with high mechanical strength and deformability under normal pressure, which are suitable for complex environments.
Patent Information
- Application Number
- CN202510920907.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-04
- Publication Date
- 2025-11-21
AI Technical Summary
Traditional ceramic aerogels are fragile in terms of mechanical properties and have reduced temperature resistance. Dust release issues limit their applications, and the controllability of ceramic nanofiber structures under normal pressure is poor, making it difficult to meet the requirements of harsh service environments.
By employing a layered structure design, ceramic nanofiber aerogels are prepared under normal pressure by introducing sheet-like bonding points in the dense layers and combining freeze-drying and high-temperature calcination processes. This results in fully dense stacked, fully fluffy stacked, or dense-to-fluffy gradient stacked structures, which enhance mechanical strength, toughness, and deformability.
The ceramic nanofiber aerogel prepared under normal pressure has high mechanical strength, good deformability and excellent thermal insulation properties, making it suitable for complex environmental conditions and expanding its application range.
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Figure CN120987630A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of advanced ceramic preparation technology, specifically to a layered ceramic nanofiber aerogel with sheet-like bonding points and its preparation method. Background Technology
[0002] Maintaining the structural stability of ceramic aerogels under tensile, compressive, and flexural forces is crucial for preserving their functionality, extending their service life, and expanding their application range. However, traditional ceramic aerogels often exhibit brittleness due to the fragile interparticle connections in their "pearl necklace"-like three-dimensional network structure. While polymer crosslinking or fiber reinforcement can improve the strength of ceramic aerogels, these methods lead to decreased temperature resistance and persistent dust release issues, limiting their practical applications.
[0003] In recent years, innovations in the research of flexible ceramic nanofibers have driven a revolution in the mechanical design paradigm of ceramic aerogels. Based on the fiber network reconstruction technology using freeze-drying, ceramic nanofiber aerogels composed of flexible ceramic nanofibers and bonding structures as basic building blocks can be prepared, fundamentally overcoming the shortcomings of traditional ceramic aerogels such as brittleness and dust release. However, the size limitations of the freeze chamber and the low economic efficiency of the freeze-drying process restrict the large-scale application of ceramic nanofiber aerogels. Using three-dimensional reactive electrospinning, solution blown spinning, and biaxial electrospinning techniques, ceramic nanofiber aerogels composed of interlaced and coiled nanofibers can be prepared under atmospheric pressure. However, the random aggregation of ceramic nanofibers leads to poor structural controllability and a limited range of adjustable bulk density. Furthermore, under extreme environments such as mechanical impact and high-frequency vibration, insufficient bonding structures can easily cause failure. Therefore, how to achieve ceramic nanofiber aerogels with mechanical strength, sufficient deformability, and excellent thermal insulation properties under atmospheric pressure through structural design to meet the requirements of harsh service environments remains a significant challenge. Summary of the Invention
[0004] The purpose of this invention is to provide a layered ceramic nanofiber aerogel with sheet-like bonding points and its preparation method. The preparation method can prepare a ceramic nanofiber aerogel with mechanical strength, high deformability and excellent thermal insulation properties under normal pressure.
[0005] To achieve the above objectives, according to the first aspect of the present invention, the following technical solution is adopted:
[0006] A layered ceramic nanofiber aerogel with sheet-like bonding points is prepared under normal pressure. The layered structure of the ceramic nanofiber aerogel is one of the following: fully dense stacking, fully fluffy stacking, alternating stacking of dense and fluffy layers, or a gradual transition from dense to fluffy stacking. The density of the sheet-like bonding points in the dense layer is 5–50 per cm³.3 It forms an arch shape in the dense layer;
[0007] The layered ceramic nanofiber aerogel with sheet-like bonding points has a bulk density of 10–70 mg / cm³. 3 It can withstand a maximum tensile breaking strength of 638 kPa, a maximum compressive strain of 80%, a maximum bending strain of 80%, and a maximum bursting strength of 392 N.
[0008] According to a second objective of the present invention, the present invention adopts the following technical solution:
[0009] (1) Cut the ceramic nanofiber sponge into multiple pieces, each corresponding to a different layer, and soak them thoroughly in cellulose nanofiber dispersion and inorganic sol respectively.
[0010] (2) The ceramic nanofiber sponge block obtained in step (1) is squeezed into different thicknesses according to the required degree of compression and stacked layer by layer, and then frozen to obtain a frozen block;
[0011] (3) The frozen block from step (2) was placed in an organic solvent containing glutaraldehyde for solvent replacement and crosslinking under normal pressure. After the frozen block was completely thawed, it was placed in an oven to dry to obtain a hybrid aerogel.
[0012] (4) The hybrid aerogel is ceramicized by high-temperature calcination process to obtain a layered ceramic nanofiber aerogel with sheet-like bonding points.
[0013] The preparation method provided by this invention can also employ the following further technical solutions, or a combination of these further technical solutions:
[0014] The ceramic nanofiber sponge in step (1) is prepared by one of the following techniques: conjugate electrospinning, 3D electrospinning, or airflow-assisted electrospinning, combined with a high-temperature calcination process. The bulk density of the ceramic nanofiber sponge is 3–10 mg / cm³. 3 The pore size is 1000–5000 nm and the thickness is 2–10 mm.
[0015] In step (1), the concentration of the cellulose nanofiber dispersion is 0.01-2%, the diameter of the cellulose nanofiber is 2-30 nm, and the aspect ratio is 50-4000.
[0016] The inorganic sol in step (1) is prepared by hydrolysis and condensation in water with one or more of aminosilane, zirconium salt, aluminum salt, titanium salt, and silane coupling agent at a molar ratio of 1:9 to 9:1. The solid content of the inorganic sol is 0.01 to 2%.
[0017] In step (1), the soaking time is 2 to 12 hours.
[0018] In step (2), the extrusion is carried out in two forms: dense extrusion and fluffy extrusion. Dense extrusion means that the thickness after extrusion is 10% or less of the original thickness of the sponge block, while fluffy extrusion means that the thickness after extrusion is greater than 10% of the original thickness of the sponge block. The number of stacked layers is 2 to 10. The freezing method used after stacking is one of liquid nitrogen freezing, refrigerator freezing, or programmable temperature-controlled freezing.
[0019] In step (3), glutaraldehyde accounts for 0.1-10% of the organic solvent, which is one or a mixture of methanol, ethanol, isopropanol, and tert-butanol. The solvent replacement and atmospheric pressure crosslinking time is 1-12 hours. The atmospheric pressure crosslinking is the Schiff base reaction between the carboxyl groups on the surface of cellulose nanofibers and glutaraldehyde, as well as the hydrogen bonding between hydroxyl, amino and carboxyl groups. The drying temperature is 40-100℃ and the drying time is 2-8 hours.
[0020] Step (4) has a maximum calcination temperature of 600-1200℃, a heating rate of 1-10℃ / min, and a holding time of 1-5 hours at the maximum calcination temperature.
[0021] In step (3), glutaraldehyde accounts for 0.1-10% of the organic solvent, which is one or a mixture of methanol, ethanol, isopropanol, and tert-butanol. The solvent replacement and atmospheric pressure crosslinking time is 1-12 hours. The atmospheric pressure crosslinking is the Schiff base reaction between the carboxyl groups on the surface of cellulose nanofibers and glutaraldehyde, as well as the hydrogen bonding between hydroxyl, amino and carboxyl groups. The drying temperature is 40-100℃ and the drying time is 2-8 hours.
[0022] Step (4) has a maximum calcination temperature of 600-1200℃, a heating rate of 1-10℃ / min, and a holding time of 1-5 hours at the maximum calcination temperature.
[0023] This invention uses ceramic nanofiber sponge as raw material, which is successively soaked in cellulose nanofiber dispersion and inorganic sol, then extruded into layers of different thicknesses and stacked and frozen. The frozen blocks are then placed in a solution containing a crosslinking agent for thawing, solvent replacement, and crosslinking. Finally, they are dried and calcined at high temperature under normal pressure to obtain a layered ceramic nanofiber aerogel with sheet-like bonding points. The ceramic nanofiber aerogel prepared by this invention has advantages such as compression resistance, tensile strength, bending resistance, and burst resistance, thus overcoming the shortcomings of poor mechanical performance of ceramic aerogels under complex environmental conditions and showing broad application prospects. Attached Figure Description
[0024] Figure 1 The images show the morphology of the dense and fluffy alternating stacked layered ceramic nanofiber aerogel. Figure a shows the macroscopic morphology, figure b shows the microscopic cross-sectional structure, figure c shows a magnified view of a local dense layer, and figure d shows a magnified view of a local fluffy layer.
[0025] Figure 2 The mechanical properties of dense, fluffy, alternatingly stacked layered ceramic nanofiber aerogels are shown in Figure a, where Figure a is the compressive stress-strain curve, Figure b is the flexural stress-strain curve, Figure c is the tensile stress-strain curve, and Figure d is the bursting strength-strain curve. Detailed Implementation
[0026] To enable those skilled in the art to better understand the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the described embodiments are merely some embodiments of the present invention, and not all embodiments. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various modifications or alterations to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.
[0027] Example 1
[0028] This embodiment provides a dense, fluffy, alternatingly stacked layered ceramic nanofiber aerogel, the steps of which are as follows:
[0029] (1) With a bulk density of 6 mg / cm³ 3 Using 8mm thick ceramic nanofiber sponge as raw material, cut into 5cm*5cm length*width dimensions, soaked in 0.5% cellulose nanofiber dispersion for 4 hours, and then transferred to an inorganic sol with a 1% solid content and a molar ratio of 3-aminopropyltriethoxysilane to basic zirconium carbonate of 1:1 for 4 hours.
[0030] (2) The ceramic nanofiber sponge soaked in step (1) is subjected to dense extrusion and fluff extrusion respectively. The thickness after dense extrusion accounts for 2.5% of the original thickness of the sponge, and the thickness after fluff extrusion accounts for 37.5% of the original thickness of the sponge. Then, 6 layers of dense layer and 5 layers of fluff layer are stacked in the form of alternating dense and fluff layers. Then, the sponge is frozen with liquid nitrogen.
[0031] (3) The frozen block obtained in step (2) was placed in a methanol solution containing 0.5% glutaraldehyde for 4 hours to thaw, replace the solvent and crosslink. Then it was dried in an oven at 60°C for 4 hours to obtain a hybrid aerogel.
[0032] (4) The hybrid aerogel was placed in a muffle furnace and heated to 1000℃ at a rate of 5℃ / min, and held at that temperature for 1 hour to obtain a bulk density of 5 mg / cm³. 3 Ceramic nanofiber aerogel.
[0033] See Figure 1The image shows the morphology of the layered ceramic nanofiber aerogel prepared in Example 1. It can be seen that the ceramic aerogel is composed of alternating dense and fluffy layers, both of which have sheet-like bonding points, with the bonding points in the dense layer exhibiting an arched shape.
[0034] See Figure 2 The mechanical properties of the layered ceramic nanofiber aerogel prepared in Example 1 are characterized. It can be seen that the ceramic aerogel can recover from bending under 80% compressive strain and 80% flexural strain, with a tensile fracture strength of up to 565 kPa and a bursting strength of up to 220 N.
[0035] Example 2
[0036] This embodiment provides a fluffy, stacked, layered ceramic nanofiber aerogel, the steps of which are as follows:
[0037] (1) With a bulk density of 3 mg / cm³ 3 Using 5mm thick ceramic nanofiber sponge as raw material, cut into dimensions of 3cm x 3cm, soak in 0.2% cellulose nanofiber dispersion for 2 hours, and then transfer to an inorganic sol with a molar ratio of 1:1 of 3-aminopropyltriethoxysilane and basic zirconium carbonate and a solid content of 0.5% for 2 hours.
[0038] (2) The ceramic nanofiber sponge soaked in step (1) is fluffed and squeezed. The thickness after squeezing is 70% of the original thickness of the sponge block. After stacking 7 layers, it is frozen in a refrigerator.
[0039] (3) The frozen block obtained in step (2) was placed in a methanol solution containing 0.3% glutaraldehyde for 3 hours to thaw, replace the solvent and crosslink. Then it was dried in an oven at 60°C for 3 hours to obtain a hybrid aerogel.
[0040] (4) The hybrid aerogel was placed in a muffle furnace and heated to 1000℃ at a rate of 5℃ / min, and held at that temperature for 2 hours to obtain a bulk density of 5 mg / cm³. 3 The ceramic nanofiber aerogel has a tensile breaking strength of up to 340 kPa and a bursting strength of up to 100 N.
[0041] Example 3
[0042] This embodiment provides a densely stacked layered ceramic nanofiber aerogel, the steps of which are as follows:
[0043] (1) With a bulk density of 10 mg / cm³ 3Using 10mm thick ceramic nanofiber sponge as raw material, cut into dimensions of 8cm x 8cm, soak in 0.1% cellulose nanofiber dispersion for 8 hours, and then transfer to an inorganic sol with a molar ratio of 1:1 of 3-aminopropyltriethoxysilane and basic zirconium carbonate and a solid content of 0.2% for 8 hours.
[0044] (2) The ceramic nanofiber sponge soaked in step (1) is compacted and compressed. The thickness after compression is 3% of the original thickness of the sponge block. After stacking 10 layers, it is frozen with liquid nitrogen.
[0045] (3) The frozen block obtained in step (2) was placed in a methanol solution containing 0.8% glutaraldehyde for 5 hours to thaw, replace the solvent and crosslink. Then it was dried in an oven at 80°C for 12 hours to obtain a hybrid aerogel.
[0046] (4) The hybrid aerogel was placed in a muffle furnace and heated to 1000℃ at a rate of 5℃ / min, and held at that temperature for 3 hours to obtain a bulk density of 70 mg / cm³. 3 The ceramic nanofiber aerogel has a tensile breaking strength of up to 340 kPa and a bursting strength of up to 392 N.
[0047] Example 4
[0048] This embodiment provides a dense to fluffy gradient stacked layered ceramic nanofiber aerogel, the steps of which are as follows:
[0049] (1) With a bulk density of 8 mg / cm³ 3 Using 10mm thick ceramic nanofiber sponge as raw material, cut into 6cm*6cm length*width dimensions, soaked in 0.3% cellulose nanofiber dispersion for 6 hours, and then transferred to an inorganic sol with a 1:1 molar ratio of 3-aminopropyltriethoxysilane to basic zirconium carbonate and a solid content of 0.2% for 6 hours.
[0050] (2) The ceramic nanofiber sponge soaked in step (1) is squeezed and the thickness after squeezing is 2%, 4%, 6%, 8%, 10%, 12%, 14% and 16% of the original thickness of the sponge block, respectively. After stacking according to the thickness from low to high, it is frozen with liquid nitrogen.
[0051] (3) The frozen block obtained in step (2) was placed in a methanol solution containing 1.2% glutaraldehyde for 8 hours to thaw, replace the solvent and crosslink. Then it was dried in an oven at 70°C for 8 hours to obtain a hybrid aerogel.
[0052] (4) The hybrid aerogel was placed in a muffle furnace and heated to 1000℃ at a rate of 2℃ / min, and held at that temperature for 3 hours to obtain a bulk density of 50 mg / cm³.3 The ceramic nanofiber aerogel has a tensile breaking strength of up to 310 kPa and a bursting strength of up to 280 N.
Claims
1. A layered ceramic nanofiber aerogel with sheet-like bonding points, characterized in that, The ceramic nanofiber aerogel was prepared under normal pressure. The layered structure of the ceramic nanofiber aerogel is one of the following: fully dense stacked, fully loose stacked, alternating stacked dense and loose layers, or gradually changing stacked from dense to loose layers. The density of the sheet-like bonding points in the dense layer is 5-50 per cm³. 3 It forms an arch shape in the dense layer; The layered ceramic nanofiber aerogel with sheet-like bonding points has a bulk density of 10–70 mg / cm³. 3 It can withstand a maximum tensile breaking strength of 638 kPa, a maximum compressive strain of 80%, a maximum bending strain of 80%, and a maximum bursting strength of 392 N.
2. A method for preparing a layered ceramic nanofiber aerogel with sheet-like bonding points, characterized in that, The preparation of the ceramic nanofiber aerogel under normal pressure includes the following steps: (1) Cut the ceramic nanofiber sponge into multiple pieces, each corresponding to a different layer, and soak them thoroughly in cellulose nanofiber dispersion and inorganic sol respectively. (2) The ceramic nanofiber sponge block obtained in step (1) is squeezed into different thicknesses according to the required degree of compression and stacked layer by layer, and then frozen to obtain a frozen block; (3) The frozen block from step (2) was placed in an organic solvent containing glutaraldehyde for solvent replacement and crosslinking under normal pressure. After the frozen block was completely thawed, it was placed in an oven to dry to obtain a hybrid aerogel. (4) The hybrid aerogel is ceramicized by high-temperature calcination process to obtain a layered ceramic nanofiber aerogel with sheet-like bonding points.
3. The preparation method according to claim 2, characterized in that: The ceramic nanofiber sponge in step (1) is prepared by one of the following techniques: conjugate electrospinning, 3D electrospinning, or airflow-assisted electrospinning, combined with a high-temperature calcination process. The bulk density of the ceramic nanofiber sponge is 3–10 mg / cm³. 3 The pore size is 1000–5000 nm and the thickness is 2–10 mm.
4. The preparation method according to claim 2, characterized in that: In step (1), the concentration of the cellulose nanofiber dispersion is 0.01-2%, the diameter of the cellulose nanofiber is 2-30 nm, and the aspect ratio is 50-4000.
5. The preparation method according to claim 2, characterized in that: The inorganic sol in step (1) is prepared by hydrolysis and condensation in water with one or more of aminosilane, zirconium salt, aluminum salt, titanium salt, and silane coupling agent at a molar ratio of 1:9 to 9:
1. The solid content of the inorganic sol is 0.01 to 2%.
6. The preparation method according to claim 2, characterized in that: In step (1), the soaking time is 2 to 12 hours.
7. The preparation method according to claim 2, characterized in that: In step (2), the extrusion is carried out in two forms: dense extrusion and fluffy extrusion. Dense extrusion means that the thickness after extrusion is 10% or less of the original thickness of the sponge block, while fluffy extrusion means that the thickness after extrusion is greater than 10% of the original thickness of the sponge block. The number of stacked layers is 2 to 10. The freezing method used after stacking is one of liquid nitrogen freezing, refrigerator freezing, or programmable temperature-controlled freezing.
8. The preparation method according to claim 2, characterized in that: In step (3), glutaraldehyde accounts for 0.1-10% of the organic solvent, which is one or a mixture of methanol, ethanol, isopropanol, and tert-butanol. The solvent replacement and atmospheric pressure crosslinking time is 1-12 hours. The atmospheric pressure crosslinking is the Schiff base reaction between the carboxyl groups on the surface of cellulose nanofibers and glutaraldehyde, as well as the hydrogen bonding between hydroxyl, amino and carboxyl groups. The drying temperature is 40-100℃ and the drying time is 2-8 hours.
9. The preparation method according to claim 2, characterized in that: Step (4) has a maximum calcination temperature of 600-1200℃, a heating rate of 1-10℃ / min, and a holding time of 1-5 hours at the maximum calcination temperature.