Flexible ceramic nanofiber paper as well as folding and shaping method and application thereof

Abstract

The invention belongs to the technical field of ceramic nanofiber paper manufacturing, and particularly relates to flexible ceramic nanofiber paper and a folding and shaping method and application thereof, and the method comprises the following steps: synthesizing a linear inorganic molecular chain with long-short side groups, preparing into a fiber spinning solution, and spinning into a precursor; performing infrared heating softening and folding shaping on the precursor; calcining to obtain ceramic nanofiber paper; the linear inorganic molecular chain with the long-short side group is prepared by the following steps: carrying out coordination modification on a metal alkoxide monomer by using a long / short inert ligand, and carrying out copolymerization and chain extension to obtain the linear inorganic molecular chain with the long-short side group; ultrasonic vibration is carried out in the folding and shaping process; and then cooling. Compared with the prior art, the problems that existing ceramic nanofiber paper of a three-dimensional structure is poor in performance, and the structure is difficult to maintain are solved. According to the scheme, through synergistic improvement of a precursor structure and a process, the ceramic nanofiber paper has excellent flexibility and structural stability, and the integrity and stability of a three-dimensional structure are improved.

Description

Technical Field

[0001] This invention belongs to the field of ceramic nanofiber paper manufacturing technology, specifically relating to a flexible ceramic nanofiber paper and its folding and shaping method and application. Background Technology

[0002] Ceramic fiber paper possesses the inherent properties of ceramic materials, such as high-temperature resistance, corrosion resistance, and good chemical stability. It also exhibits the flexibility and processability inherent in fiber structures, demonstrating significant application value in fields such as high-temperature insulation, catalyst carriers, and gas filtration. However, traditional ceramic fiber paper is mostly in the form of two-dimensional sheets, making it difficult to meet the spatial configuration requirements of complex service environments. Therefore, fabricating ceramic fiber paper from simple planar materials into three-dimensional structural products is of paramount importance for solving the application challenges of ceramic materials in complex scenarios.

[0003] Existing processes mostly involve folding pre-calcined ceramic fiber paper through methods such as mold pressing, mechanical folding, or bonding assembly, followed by drying, curing, or high-temperature sintering to obtain three-dimensional ceramic fiber products with corrugated, wavy, or honeycomb structures. For example, patent CN202510867554.X describes a process where solid amine is coated onto ceramic fiber paper, dried and cured, and then corrugated and shaped using a corrugated roll press to produce ceramic fiber corrugated paper containing solid amine. However, traditional ceramic fiber paper is mainly produced through wet forming processes, where the connection between short fibers relies primarily on adhesives or simple physical entanglement, resulting in a loose structure and poor mechanical strength. Furthermore, because the slip space between fibers is locked by high-temperature sintering, the ceramic fibers at the folds are prone to brittle fracture during folding deformation, leading to a significant decrease in product strength. Patent CN202510314915.8 describes a process for impregnating fiber paper with epoxy resin, drying, corrugating, and sintering. However, the forming process is often completed under static conditions with restricted fiber movement, which easily introduces residual internal stress. Simultaneously, the organic components relied upon by these methods undergo thermal decomposition during high-temperature calcination, easily leading to corrugated configuration distortion, structural collapse, or even overall instability, making it difficult to maintain its three-dimensional structure. Furthermore, the ceramic fiber paper prepared by these methods is mainly composed of micron-sized short fibers with large diameters and low aspect ratios. The resulting fiber network has large pore sizes, low specific surface areas, and poor uniformity, leading to poor mechanical properties and weak thermal insulation in the fiber paper and its products, making it difficult to meet high-performance requirements.

[0004] Therefore, developing ceramic fiber paper and its products based on continuous nanofibers is a key direction for breaking through existing performance bottlenecks and expanding their applications in advanced scenarios. To this end, there is an urgent need to develop a method for preparing flexible ceramic nanofiber paper that can achieve three-dimensional structural molding, in order to obtain flexible ceramic nanofiber paper products with complete structure and excellent performance, thereby meeting the pressing needs of applications such as high-temperature insulation, efficient catalysis, and gas filtration. Summary of the Invention

[0005] The purpose of this invention is to provide a flexible ceramic nanofiber paper and its folding and shaping method and application to solve at least one of the above-mentioned problems, thereby addressing the issues of poor performance and difficulty in maintaining the structure of existing three-dimensional ceramic nanofiber papers. This solution, through synergistic improvements in precursor structure and process, enables the ceramic nanofiber paper to possess excellent flexibility and structural stability, while enhancing the integrity and stability of the three-dimensional structure.

[0006] The objective of this invention is achieved through the following technical solution: The first aspect of this invention discloses a method for folding and shaping flexible ceramic nanofiber paper, comprising the following steps: First, linear inorganic molecular chains with long-short side groups are synthesized and prepared as a fiber spinning solution. The fiber spinning solution is then spun into a precursor. Subsequently, the precursor is subjected to infrared heating to soften and folding to shape it. Finally, ceramic nanofiber paper is obtained by calcination. in, The linear inorganic molecular chain with long-short side groups is synthesized by the following steps: the metal alkoxide monomer is coordinated and modified by long inert ligands and short inert ligands respectively, mixed and copolymerized, and the chain is extended to obtain the linear inorganic molecular chain with long-short side groups. During the folding and shaping process: ultrasonic vibration is applied to the molding precursor to relax and rearrange the fibers along the fold direction; then the temperature is lowered to below the glass transition temperature to fix the fiber bonding points.

[0007] Preferably, the metal alkoxide monomer is selected from one or more combinations of titanium source, zirconium source, aluminum source, indium source, tin source, hafnium source, gallium source, tantalum source and niobium source; wherein: The titanium source is selected from one or more combinations of titanium tetraethanol, titanium tetraethanol, titanium n-propoxide, titanium isopropoxide, titanium n-butoxide, and titanium isobutoxide. The zirconium source is selected from one or more combinations of zirconium tetraethanol, zirconium tetraethanol, zirconium n-propoxide, zirconium isopropoxide, zirconium n-butoxide, and zirconium isobutoxide; The aluminum source is selected from one or more combinations of aluminum trimethoxy, aluminum triethanolamine, aluminum tri-n-propoxy, aluminum isopropoxide, aluminum n-butoxide, and aluminum sec-butoxide. The indium source is selected from one or more combinations of indium isopropoxide, indium triethoxy, and indium tert-butoxide; The tin source is selected from one or more combinations of tin tetramethanol, tin tetraethanol, tin n-propoxide, tin isopropoxide, tin n-butoxide, tin isobutoxide, and tin tert-butoxide; The hafnium source is selected from one or more combinations of tetraethanol hafnium, tetraethanol hafnium, n-propanol hafnium, isopropanol hafnium, n-butanol hafnium, isobutanol hafnium and tert-butanol hafnium; The gallium source is selected from one or more combinations of gallium triethoxy, gallium isopropoxide, gallium n-butoxide, and gallium tert-butoxide; The tantalum source is selected from one or a combination of two of tantalum isopropoxide and tantalum n-butoxide; The niobium source is selected from one or a combination of two of niobium isopropoxide and niobium n-butoxide; The short inert ligand is one or more combinations of acetic acid, oxalic acid, ethylenediamine, and acetylacetone; The long inert ligand is one or more combinations of citric acid, aminotriacetic acid, ammonium citrate, stearic acid, oleic acid and hexanoic acid.

[0008] Preferably, a catalyst is added during the copolymerization process; The catalyst is selected from one or more combinations of boron trifluoride, aluminum trichloride, boron tribromide, boron triiodide, tin tetrachloride, silicon tetrachloride, and titanium tetrachloride.

[0009] Preferably, a chain extender is added during the chain extension process; The chain extender is selected from one or more combinations of bis(ethyl acetoacetate) titanate, bis(diethylcitrate) dipropoxide zirconium, diisopropoxydiacetylacetonate titanium, titanium dichlorodicyclopentadiene, zirconium dichlorodicyclopentadiene, and hafnium dichlorodicyclopentadiene.

[0010] Preferably, the infrared heating and softening process uses mid-infrared light as the irradiation source, with a wavelength range of 0.75~1000μm.

[0011] Preferably, the frequency of the ultrasonic vibration is 40~80kHz.

[0012] Preferably, the cooling temperature is -5~15℃.

[0013] Preferably, the calcination temperature is 400~1500℃ and the calcination time is 10~60min.

[0014] The second aspect of this invention discloses a flexible ceramic nanofiber paper, which is obtained by folding and shaping the ceramic nanofiber paper as described above. The cross-sectional shapes of the ceramic nanofiber paper include flat structure, corrugated structure and corrugated structure.

[0015] The third aspect of this invention discloses the application of the flexible ceramic nanofiber paper described above in fireproof and heat-insulating pads, solid electrolytes, flexible electrode or membrane support layers, flexible substrates or functional layers, catalytic and filter carriers, and flame-retardant, noise-reducing, and heat-insulating layers.

[0016] The flexible ceramic nanofiber paper prepared by this method uses inorganic ceramic materials with strong ionic and covalent bonds, a compact crystal structure, and excellent chemical stability, which enable it to maintain strength and shape stability at high temperatures and withstand temperatures above 1000℃. The oxide ceramics have highly stable chemical properties, are not easily corroded, and have an extremely high density lattice structure after sintering, which effectively blocks the penetration of corrosive media.

[0017] The working principle of this invention is as follows: This invention utilizes long and short inert ligands to coordinate modify metal alkoxide monomers, thereby obtaining bifunctional modified monomers. By activating the metal-oxygen bonds in the long inert ligand-modified monomers with a catalyst, they can undergo copolymerization reactions with the short inert ligand-modified monomers. This effectively suppresses the tendency for the short inert ligand-modified monomers to react with each other to form branched or cross-linked networks, thus promoting one-dimensional linear chain growth and ultimately yielding linear inorganic molecular chains with long and short side groups.

[0018] High-frequency micro-vibration is applied to the softened precursor during the folding and shaping process, which effectively weakens the physical entanglement and friction between nanofibers in the precursor. This allows the fibers to undergo microscopic slippage and rearrangement during folding and deformation, enabling them to be oriented and filled according to the shape of the mold structure. The continuous high-frequency micro-vibration introduces a dynamic stress relaxation mechanism during the pressing process, which can offset and disperse the local internal stress concentration caused by fiber bending and accumulation, fundamentally avoiding fiber damage and other problems that are easily caused during the pressing process.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) In this invention, metal alkoxides are modified with bifunctionality by long / short inert ligands, and chain extenders are introduced to induce their growth into linear inorganic molecular chains with high degree of polymerization. This molecular chain design endows the nanofibers in the precursor with thermoplasticity, which allows them to be transformed into a softened state under infrared heating conditions, so that they can be directly processed into three-dimensional structures by bending and deformation in the precursor stage.

[0020] (2) The ultrasonic roller generates high-frequency micro-vibration during the molding process to loosen the physical entanglement between fibers, induces the nanofibers in the precursor to undergo micro-rearrangement at the fold and dissipates stress, thereby avoiding the distortion, cracking or collapse of ceramic nanofiber paper caused by stress release during subsequent calcination, and significantly improving the integrity and stability of the three-dimensional structure.

[0021] (3) The ceramic nanofiber paper of this scheme adopts the processing path of direct precursor shaping, realizing continuous production from spinning, shaping to calcination. It avoids cumbersome secondary processing steps, reduces energy consumption, and avoids processing damage through controlled peeling technology (air blowing peeling), providing an efficient solution for large-scale preparation of high-performance three-dimensional ceramic paper products.

[0022] (4) The products obtained by this invention combine the inherent high-temperature resistance and corrosion resistance of ceramic materials with the excellent flexibility and structural stability of fiber structures. They can be further customized and assembled to obtain three-dimensional ceramic fiber paper products with cylindrical, sandwich, and honeycomb structures according to requirements. Based on this, through functional composites, one or more functions such as heat preservation, conductivity, electromagnetic stealth, catalysis, and gas adsorption can be obtained, which are suitable for fields such as high-temperature insulation, flame retardant noise reduction, flexible electrodes, electromagnetic protection, and gas filtration. Attached Figure Description

[0023] Figure 1 A schematic diagram of the pretreatment device for folding and shaping.

[0024] Figure 2 This is a schematic diagram of the structure of flexible ceramic nanofiber paper.

[0025] Figure 3 This is a schematic diagram of the structure of flexible ceramic nanofiber paper used in solid-state batteries.

[0026] In the diagram: 1-1 Infrared irradiation element, 1-2 Pressure roller, 1-3 Ultrasonic roller, 1-4 Cold pressing roller, 1-5 Air roller; 2-1 Cylindrical structure, 2-2 Sandwich structure, 2-3 Honeycomb structure. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0028] In the following embodiments and comparative examples, unless otherwise specified, the raw materials or processing techniques are all conventional commercially available raw materials or conventional processing techniques in the art. Unless otherwise specified, the functional components or structures are all conventional components or conventional structures used in the art to achieve the corresponding functions.

[0029] This invention synthesizes highly polymerized linear inorganic molecular chains with long-short side groups, prepares them as a spinning solution, and spins them to obtain thermoplastic precursor nanofiber paper. Subsequently, the precursor nanofiber paper is fed into a molding and shaping pretreatment device for folding and shaping: after infrared heating, the softened precursor nanofiber paper is folded and deformed under the assistance of high-frequency micro-vibration. After calcination, flexible ceramic nanofiber paper products with three-dimensional structures (such as flat, corrugated, or trapezoidal corrugated structures) can be directly obtained. Further assembly can yield flexible ceramic nanofiber paper products with complex three-dimensional structures such as honeycomb and cylindrical shapes, and functional composites can endow them with multiple functions such as heat insulation, conductivity, electromagnetic stealth, and catalysis. The flexible ceramic nanofiber paper products prepared by this invention have excellent flexibility and structural stability, showing broad application prospects in fields such as high-temperature insulation, flexible electronics, electromagnetic protection, and catalytic filtration.

[0030] More specifically, in this invention: Firstly, a method for preparing flexible ceramic nanofiber paper and its derivatives is provided, including the following steps: S1. First, a bifunctional modified monomer is prepared by coordinating a metal alkoxide monomer with long / short inert ligands. Then, a catalyst and deionized water are added to the system to cause the long-ligand modified monomer and the short-ligand modified monomer to undergo a copolymerization reaction, thereby obtaining a low-polymerization-degree linear inorganic molecular chain with long-short ligands. A chain extender is added to the system to allow chain extension growth, thereby obtaining a high-polymerization-degree linear inorganic molecular chain with long-short side groups. Then, the high-polymerization-degree linear inorganic molecular chain is prepared as a spinning solution and spun to obtain a thermoplastic precursor nanofiber paper. S2. The precursor nanofiber paper prepared in S1 is transported to the molding and shaping pretreatment device. It is softened by non-contact heating using infrared irradiation element 1-1. The softened precursor nanofiber paper is folded and deformed using pressure roller 1-2 and ultrasonic roller 1-3. Then it is shaped at low temperature by cold pressure roller 1-4. Finally, the folded precursor nanofiber paper is peeled off from the pressure roller surface by vertically spraying controlled airflow using air roller 1-5. S3. The folded precursor nanofiber paper in S2 is calcined to directly obtain flexible ceramic nanofiber paper products with flat, corrugated, or trapezoidal corrugated structures; through further assembly, flexible ceramic nanofiber paper products with three-dimensional structures such as honeycomb and tubular are obtained.

[0031] In step S2, the molding and shaping pretreatment device includes an infrared irradiation element 1-1, a pressure roller 1-2, an ultrasonic roller 1-3, a cold pressing roller 1-4, and an air roller 1-5. The infrared irradiation element 1-1 is positioned in front of the ultrasonic roller 1-3 to provide non-contact heating to the continuously conveyed precursor nanofiber paper. The ultrasonic roller 1-3 has a built-in ultrasonic generator that applies high-frequency micro-vibrations to the softened precursor nanofiber paper. The pressure roller 1-2 and the ultrasonic roller 1-3 mesh with each other to fold the precursor nanofiber paper (the three-dimensional structure after folding is determined by the shape of the module surrounding the roller, such as...). Figure 1 The diagram shows three sets of replaceable modules corresponding to flat, corrugated, and trapezoidal corrugated structures, respectively. The cold pressing roller 1-4 is located behind the ultrasonic roller 1-3 and engages synchronously with it to perform low-temperature shaping of the folded fiber paper and prevent the fiber bonding points from relaxing and rebounding due to residual heat. The air roller 1-5 is located behind and below the ultrasonic roller 1-3 and peels the fiber paper from the ultrasonic roller by vertically spraying controlled airflow onto the folded precursor nanofiber paper.

[0032] In some specific embodiments, in step S1, the metal alkoxide monomer is selected from one or more combinations of titanium source, zirconium source, aluminum source, indium source, tin source, hafnium source, gallium source, tantalum source, and niobium source; the titanium source is selected from one or more combinations of titanium tetramethylethanol, titanium tetraethanol, titanium n-propoxide, titanium isopropoxide, titanium n-butoxide, and titanium isobutoxide; the zirconium source is selected from one or more combinations of zirconium tetramethylethanol, zirconium tetraethanol, zirconium n-propoxide, zirconium isopropoxide, zirconium n-butoxide, and zirconium isobutoxide; the aluminum source is selected from aluminum trimethoxy, The source is selected from one or more combinations of aluminum triethanolamine, aluminum tri-n-propoxyamine, aluminum isopropoxide, aluminum n-butoxide, and aluminum sec-butoxide; the indium source is selected from one or more combinations of indium isopropoxide, indium triethoxyamine, and indium tert-butoxide; the tin source is selected from one or more combinations of tin tetraethanolamine, tin tetraethanolamine, tin n-propoxide, tin isopropoxide, tin n-butoxide, tin isobutoxide, and tin tert-butoxide; the hafnium source is selected from one or more combinations of hafnium tetraethanolamine, hafnium tetraethanolamine, hafnium n-propoxide, hafnium isopropoxide, hafnium n-butoxide, hafnium isobutoxide, and hafnium tert-butoxide. Combination; Gallium source selected from one or more combinations of gallium triethoxy, gallium isopropoxide, gallium n-butoxide, and gallium tert-butoxide; Tantalum source selected from one or two combinations of tantalum isopropoxide and tantalum n-butoxide; Niobium source selected from one or two combinations of niobium isopropoxide and niobium n-butoxide; Short inert ligand selected from one or more combinations of acetic acid, oxalic acid, ethylenediamine, and acetylacetone; Long inert ligand selected from one or more combinations of citric acid, aminotriacetic acid, ammonium citrate, stearic acid, oleic acid, and hexanoic acid; Catalyst selected from trifluorine One or more of boron trichloride, aluminum trichloride, boron tribromide, boron triiodide, tin tetrachloride, silicon tetrachloride, and titanium tetrachloride; one or more of the chain extender of bis(ethyl acetoacetate)titanate, bis(diethylcitrate)dipropoxide zirconium, diisopropoxydiacetylacetonate titanium, titanium dichlorodecene, zirconium dichlorodecene, and hafnium dichlorodecene; the degree of polymerization of the low-polymerization-degree linear inorganic molecular chain is 10~50; the degree of polymerization of the high-polymerization-degree linear inorganic molecular chain is 200~5000.

[0033] In some specific embodiments, in step S2, the infrared irradiation element 1-1 rapidly and uniformly softens the precursor nanofiber paper to a plastic state; the surfaces of the pressure roller 1-2, ultrasonic roller 1-3, and cold press roller 1-4 are all covered with replaceable low surface energy mold modules, which can produce two-dimensional flat precursor nanofiber paper, or directly press it into three-dimensional corrugated or trapezoidal corrugated precursor nanofiber paper; the infrared irradiation element 1-1 uses mid-infrared light as the irradiation source, with a wavelength range of 0.75~1000μm; the pressure applied to the precursor nanofiber paper by the pressure roller 1-2, ultrasonic roller 1-3, and cold press roller 1-4 is 0.1~5MPa.

[0034] An ultrasonic generator is installed inside ultrasonic rollers 1-3, which can generate high-frequency micro-vibrations in the range of 40~80kHz, causing the precursor ceramic fibers to undergo micro-slippage during the folding process, allowing the fibers to relax and rearrange along the fold direction, thus counteracting the localized internal stress concentration generated during the bending process of the fiber paper.

[0035] A condenser is introduced into the cold press rollers 1-4 to maintain their surface temperature between -5 and 15°C, so that the precursor nanofibers are rapidly cooled to below their glass transition temperature under pressure, effectively fixing the fiber bonding points; the condenser is one or a combination of ethylene glycol solution, propylene glycol solution, methyl silicone oil, fluorosilicone oil, alkylated aromatic hydrocarbons, diesters and polyol esters.

[0036] The air rollers 1-5 have slit nozzles, and the jetting airflow generates instantaneous pneumatic peeling force at the interface between the precursor nanofiber paper and the mold, so as to gently and non-destructively peel off the precursor nanofiber paper; the pressure of the jetting airflow is controlled within the range of 0.01~0.2MPa.

[0037] In some specific embodiments, in step S3, the calcination process is carried out at 400~1500℃ and the calcination time is 10~60min. After calcination, flexible ceramic nanofiber paper products with flat, corrugated, or trapezoidal corrugations are directly obtained.

[0038] Discounted ceramic nanofiber paper can be customized and assembled to form a three-dimensional structure, such as... Figure 2 As shown, it includes a cylindrical structure 2-1 formed by winding flat ceramic nanofiber paper, a sandwich structure 2-2 formed by sequentially stacking flat and corrugated fiber paper, and a honeycomb structure 2-3 formed by interlocking trapezoidal corrugated fiber paper.

[0039] Flexible ceramic nanofiber paper and its products can be used as fireproof and heat-insulating pads for power battery packs of new energy vehicles, solid electrolytes in solid lithium batteries, flexible electrode or separator support layers in sensors, flexible substrates or functional layers in semiconductor devices, catalytic and filter carriers in industrial waste gas and dust treatment systems, and flame-retardant, noise-reducing and heat-insulating layers for large aircraft, ships, submarines, subways and high-speed trains.

[0040] Example 1 This embodiment provides a molding and shaping pretreatment device for precursor nanofiber paper, the structure of which is described in the following figure. Figure 1 ,include: The system includes an infrared irradiation element 1-1, a pressure roller 1-2, an ultrasonic roller 1-3, a cold pressure roller 1-4, and an air roller 1-5. The infrared irradiation element 1-1 is located in front of the ultrasonic roller 1-3. The ultrasonic roller 1-3 has a built-in ultrasonic generator that applies high-frequency micro-vibrations to the precursor nanofiber paper in a softened state. The pressure roller 1-2 meshes with the ultrasonic roller 1-3. The cold pressure roller 1-4 is located behind the ultrasonic roller 1-3 and meshes with it synchronously. The air roller 1-5 is located on the lower rear side of the ultrasonic roller 1-3.

[0041] Example 2 This embodiment provides a flexible ceramic nanofiber paper product and its preparation method based on the apparatus of Embodiment 1. The specific steps are as follows: (1) Using zirconium n-propoxide as a metal alkoxide, acetylacetone as a short inert ligand and oleic acid as a long inert ligand for bifunctional modification, and adding boron trifluoride catalyst and zirconium dichlorocerocene chain extender, a high degree of polymerization linear precursor molecular chain with long-short side groups is obtained through copolymerization and chain extension growth. After preparing it into a spinning solution, the precursor nanofiber paper is obtained by spinning. (2) The precursor nanofiber paper is uniformly softened by emitting infrared light with a wavelength of 3.4 μm through an infrared irradiation element; then it enters a flat pressure roller module (module 3) and is pressed under a pressure of 5 MPa and a high frequency micro-vibration of 50 kHz; after being cooled by a -5℃ cold pressure roller, it is peeled off by a controlled airflow of 0.01 MPa sprayed by an air roller. (3) The flat precursor nanofiber paper was calcined at 850°C for 50 min to obtain a flat flexible ceramic nanofiber paper with excellent flexibility, smooth surface and continuous structure.

[0042] The flexibility of the flexible ceramic nanofiber paper prepared in this embodiment was tested, and its fracture toughness was ≥0.24 MJ / m. 3 The fracture toughness was determined by tensile testing in accordance with "GB-T 12914-2018 Determination of Tensile Strength of Paper and Paperboard". The fracture toughness value was calculated by integrating the area under the tensile stress-strain curve.

[0043] Example 3 This embodiment provides a flexible ceramic nanofiber paper product and its preparation method based on the apparatus of Embodiment 1. The specific steps are as follows: (1) Tetraethyl orthosilicate was used as the silicon source, acetylacetone was selected as the short inert ligand and stearic acid was selected as the long inert ligand for coordination modification, silicon tetrachloride was added as a catalyst, and dimethyl dichlorosilane was introduced as a chain extender. A high degree of polymerization linear siloxane molecular chain with long-short side groups was obtained through copolymerization and chain extension reaction, and thermoplastic precursor nanofiber paper was obtained by spinning. (2) The fiber is softened uniformly by emitting infrared light with a wavelength of 3.4 μm through an infrared irradiation element; then it enters the flattening pressure roller module (module 3) and is subjected to a pressure of 1.5 MPa, while simultaneously coordinating with 40 kHz high-frequency micro-vibration to induce fiber slippage; after being cooled by a 0℃ cold pressure roller, it is peeled off by air jetting 0.05 MPa airflow. (3) The flat precursor nanofiber paper was calcined at 1500℃ for 30 min to obtain a flat flexible ceramic nanofiber paper with excellent flexibility.

[0044] Tests showed that the fracture toughness of this flexible ceramic nanofiber paper was comparable to that of Example 2, and will not be elaborated further here.

[0045] Example 4 This embodiment provides a flexible ceramic nanofiber paper product and its preparation method based on the apparatus of Embodiment 1. The specific steps are as follows: (1) Using zirconium n-propoxide as a metal alkoxide, acetylacetone as a short inert ligand and oleic acid as a long inert ligand for bifunctional coordination modification; boron trifluoride catalyst was added to the system to activate the metal-oxygen bond, and a low degree of polymerization linear chain was obtained by hydrolysis and polycondensation. Then, zirconium dichlorocerocene chain extender was added to induce its growth into a high degree of polymerization linear inorganic molecular chain. It was prepared into a spinning solution and obtained thermoplastic precursor nanofiber paper by electrospinning. (2) The precursor nanofiber paper is heated and softened by emitting infrared light with a wavelength of 3.4 μm using an infrared irradiation element; the softened fiber paper is pressed by meshing with an ultrasonic roller (module 1) and a pressure of 0.1 MPa is applied. A high-frequency micro-vibration of 40 kHz is introduced to induce micro-rearrangement of fibers to relieve internal stress; after being cold-pressed and shaped by a 5℃ cold press roller, it is non-destructively peeled by a controlled airflow of 0.2 MPa sprayed by an air roller. (3) The obtained precursor nanofiber paper was calcined at 800℃ for 60 min to obtain trapezoidal corrugated flexible ceramic nanofiber paper.

[0046] Tests showed that the fracture toughness of this flexible ceramic nanofiber paper was comparable to that of Example 2, and will not be elaborated further here.

[0047] Example 5 This embodiment provides a flexible ceramic nanofiber paper product and its preparation method based on the apparatus of Embodiment 1. The specific steps are as follows: (1) Using aluminum isopropoxide as a metal alkoxide, oxalic acid as a short inert ligand and stearic acid as a long inert ligand are selected for modification, and silicon tetrachloride is added as a catalyst and titanium diisopropoxybisacetylacetonate as a chain extender to prepare a linear molecular chain with a high degree of polymerization with long-short side groups, and the precursor nanofiber paper is spun. (2) Adjust the infrared irradiation element to emit infrared light with a wavelength of 2.9μm to achieve rapid softening; feed the fiber paper into the pressure roller assembly with trapezoidal mold (module 1), apply a pressure of 1.8MPa and introduce 80kHz high frequency micro-vibration; after cold pressing and shaping at 15℃, demolding is achieved by air roller spraying air at 0.15MPa; (3) After calcining at 1100℃ for 45 minutes, corrugated flexible ceramic nanofiber paper was obtained.

[0048] Tests showed that the fracture toughness of this flexible ceramic nanofiber paper was comparable to that of Example 2, and will not be elaborated further here.

[0049] Example 6 This embodiment provides a flexible ceramic nanofiber paper product and its preparation method based on the apparatus of Embodiment 1. The specific steps are as follows: (1) Using titanium isopropoxide as a metal alkoxide, acetylacetone as a short inert ligand and oleic acid as a long inert ligand for coordination modification, titanium tetrachloride catalyst and titanium dichlorocerocene chain extender were added, the obtained linear molecular chain was formulated into a spinning solution and spun to obtain precursor nanofiber paper. (2) The fiber paper is softened by irradiation with mid-infrared light with a wavelength of 3.4 μm; the softened fiber paper is pressed by interlocking with a corrugated pressure roller module (module 2), a pressure of 1.5 MPa is applied, and a high-frequency micro-vibration of 70 kHz is introduced to induce micro-rearrangement of fibers to relieve internal stress; after being cold-pressed and shaped by a 0℃ cold pressure roller, it is peeled off non-destructively by a controlled airflow of 0.05 MPa sprayed by an air roller. (3) After calcining at 400℃ for 10 min, corrugated flexible ceramic nanofiber paper was obtained.

[0050] Tests showed that the fracture toughness of this flexible ceramic nanofiber paper was comparable to that of Example 2, and will not be elaborated further here.

[0051] Example 7 This embodiment provides a flexible ceramic nanofiber paper product and its preparation method, the specific steps of which are as follows: (1) Based on the apparatus of Example 1 and the method of Example 2, a flat precursor nanofiber paper with a smooth surface and uniform thickness was prepared; (2) After the obtained precursor nanofiber paper is softened by infrared heating, it is wound and pressed on a core mold, and cooled and shaped to obtain a cylindrical precursor nanofiber paper. (3) Calcination at 600℃ for 30 min transforms it into flexible ceramic nanofiber paper.

[0052] Tests showed that the fracture toughness of this flexible ceramic nanofiber paper was comparable to that of Example 2, and will not be elaborated further here.

[0053] Example 8 This embodiment provides a flexible ceramic nanofiber paper product and its preparation method, the specific steps of which are as follows: (1) Based on the apparatus of Example 1 and the method of Example 5, flat precursor nanofiber paper and corrugated precursor nanofiber paper were prepared respectively; (2) The obtained precursor nanofiber paper was calcined at 950℃ for 30 min to transform it into flexible ceramic nanofiber paper; (3) Then, flat ceramic nanofiber paper is used as the panel and corrugated ceramic nanofiber paper is used as the core layer. The layers are assembled by coating adhesive at the contact points, and finally a lightweight, high-porosity sandwich structure flexible ceramic nanofiber product is obtained.

[0054] Tests showed that the fracture toughness of this flexible ceramic nanofiber paper was comparable to that of Example 2, and will not be elaborated further here.

[0055] Example 9 This embodiment provides a flexible ceramic nanofiber paper product and its preparation method, the specific steps of which are as follows: (1) Based on the method of Example 4, precursor nanofiber paper with trapezoidal corrugations was prepared; (2) The obtained precursor nanofiber paper was calcined at 1000℃ for 40 min to transform it into flexible ceramic nanofiber paper; (3) Then the corrugated ceramic nanofiber paper is stacked in pairs and an adhesive is applied to the contact area to finally obtain a honeycomb flexible ceramic nanofiber product with high porosity and high strength.

[0056] Tests showed that the fracture toughness of this flexible ceramic nanofiber paper was comparable to that of Example 2, and will not be elaborated further here.

[0057] Comparative Example 1 This comparative example is basically the same as Example 2, except that in step (2), after the precursor nanofiber paper is heated to above the glass transition temperature by infrared irradiation, it is directly pressed and shaped without ultrasonic vibration, and then cooled, peeled and calcined; the other conditions are the same as in Example 2. Due to the lack of the fiber micro-slip and stress release process induced by ultrasonic vibration, the precursor is subjected to strong mechanical compression during the pressing process, resulting in severe stress concentration inside the fiber network. The overall flexibility of the ceramic paper prepared in Comparative Example 1 is greatly weakened, and the fracture toughness is only 0.17 MJ / m. 3 .

[0058] Comparative Example 2 This comparative example is basically the same as Example 4, except that in step (2), the precursor nanofiber paper was not cold-pressed and shaped by cold rollers. After infrared radiation treatment and pressing, it was naturally cooled, then peeled off and calcined. The other conditions are the same as in Example 4. Due to the lack of cold pressing and shaping process, the fibers have sufficient time for stress relaxation and elastic recovery of molecular chain segments during natural cooling, resulting in irreversible dimensional rebound of the three-dimensional structure before peeling. The ceramic paper prepared in Comparative Example 2 showed obvious collapse and blurred outline, with a fracture toughness of 0.20 MJ / m. 3 .

[0059] Application Example 1 like Figure 3 As shown, the flexible ceramic nanofiber product prepared in Example 2 or Example 3 is used as a solid electrolyte. The positive electrode and the negative electrode are respectively attached to both sides of the flexible ceramic nanofiber product. Then, the stacked positive electrode, flexible ceramic nanofiber paper and negative electrode are wound together to obtain a cylindrical battery cell structure.

[0060] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for folding and shaping flexible ceramic nanofiber paper, characterized in that, Includes the following steps: First, linear inorganic molecular chains with long-short side groups are synthesized and prepared as a fiber spinning solution. The fiber spinning solution is then spun into a precursor. Subsequently, the precursor is subjected to infrared heating to soften and folding to shape it. Finally, ceramic nanofiber paper is obtained by calcination. The linear inorganic molecular chain with long-short side groups is synthesized by the following steps: the metal alkoxide monomer is coordinated and modified by long inert ligands and short inert ligands respectively, mixed and copolymerized, and then extended to obtain the linear inorganic molecular chain with long-short side groups. During the folding and shaping process: ultrasonic vibration is applied to the molding precursor to relax and rearrange the fibers along the fold direction; then the temperature is lowered to below the glass transition temperature to fix the fiber bonding points.

2. The method for folding and shaping flexible ceramic nanofiber paper according to claim 1, characterized in that, The metal alkoxide monomer is selected from one or more combinations of titanium source, zirconium source, aluminum source, indium source, tin source, hafnium source, gallium source, tantalum source and niobium source; wherein: The titanium source is selected from one or more combinations of titanium tetraethanol, titanium tetraethanol, titanium n-propoxide, titanium isopropoxide, titanium n-butoxide, and titanium isobutoxide. The zirconium source is selected from one or more combinations of zirconium tetraethanol, zirconium tetraethanol, zirconium n-propoxide, zirconium isopropoxide, zirconium n-butoxide, and zirconium isobutoxide; The aluminum source is selected from one or more combinations of aluminum trimethoxy, aluminum triethanolamine, aluminum tri-n-propoxy, aluminum isopropoxide, aluminum n-butoxide, and aluminum sec-butoxide. The indium source is selected from one or more combinations of indium isopropoxide, indium triethoxy, and indium tert-butoxide; The tin source is selected from one or more combinations of tin tetramethanol, tin tetraethanol, tin n-propoxide, tin isopropoxide, tin n-butoxide, tin isobutoxide, and tin tert-butoxide; The hafnium source is selected from one or more combinations of tetraethanol hafnium, tetraethanol hafnium, n-propanol hafnium, isopropanol hafnium, n-butanol hafnium, isobutanol hafnium and tert-butanol hafnium; The gallium source is selected from one or more combinations of gallium triethoxy, gallium isopropoxide, gallium n-butoxide, and gallium tert-butoxide; The tantalum source is selected from one or a combination of two of tantalum isopropoxide and tantalum n-butoxide; The niobium source is selected from one or a combination of two of niobium isopropoxide and niobium n-butoxide; The short inert ligand is one or more combinations of acetic acid, oxalic acid, ethylenediamine, and acetylacetone; The long inert ligand is one or more combinations of citric acid, aminotriacetic acid, ammonium citrate, stearic acid, oleic acid and hexanoic acid.

3. The method for folding and shaping flexible ceramic nanofiber paper according to claim 1, characterized in that, A catalyst is added during the copolymerization process. The catalyst is selected from one or more combinations of boron trifluoride, aluminum trichloride, boron tribromide, boron triiodide, tin tetrachloride, silicon tetrachloride, and titanium tetrachloride.

4. The method for folding and shaping flexible ceramic nanofiber paper according to claim 1, characterized in that, A chain extender is added during the chain extension process; The chain extender is selected from one or more combinations of bis(ethyl acetoacetate) titanate, bis(diethylcitrate) dipropoxide zirconium, diisopropoxydiacetylacetonate titanium, titanium dichlorodicyclopentadiene, zirconium dichlorodicyclopentadiene, and hafnium dichlorodicyclopentadiene.

5. The method for folding and shaping flexible ceramic nanofiber paper according to claim 1, characterized in that, The infrared heating and softening process uses mid-infrared light as the irradiation source, with a wavelength range of 0.75~1000μm.

6. The method for folding and shaping flexible ceramic nanofiber paper according to claim 1, characterized in that, The frequency of the ultrasonic vibration is 40~80kHz.

7. The method for folding and shaping flexible ceramic nanofiber paper according to claim 1, characterized in that, The cooling temperature is -5~15℃.

8. The method for folding and shaping flexible ceramic nanofiber paper according to claim 1, characterized in that, The calcination temperature is 400~1500℃, and the calcination time is 10~60min.

9. A flexible ceramic nanofiber paper, characterized in that, It is obtained by folding and shaping ceramic nanofiber paper according to any one of claims 1 to 9; The cross-sectional shapes of the ceramic nanofiber paper include flat structure, corrugated structure and corrugated structure.

10. The application of the flexible ceramic nanofiber paper as described in claim 9 in fireproof and heat-insulating pads, solid electrolytes, flexible electrode or diaphragm support layers, flexible substrates or functional layers, catalytic and filter carriers, and flame-retardant, noise-reducing, and heat-insulating layers.

Images