Inorganic flexible fiber paper with spot welding type fixed three-dimensional network structure and preparation method of inorganic flexible fiber paper

Abstract

The invention discloses inorganic flexible fiber paper with a spot welding type fixed three-dimensional network structure and a preparation method of the inorganic flexible fiber paper, and relates to the technical field of inorganic fiber materials.The inorganic flexible fiber paper comprises a three-dimensional porous fiber skeleton formed by interweaving inorganic fibers, the discontinuous bonding units are dispersed at overlapping points of the fiber skeleton and are formed by inorganic glue; the bonding units are chemically bonded to fiber lap joints in an isolated dot form, and the fiber skeleton and the bonding units are mutually combined and uniformly distributed in x, y and z directions to jointly form a composite network structure with the porosity of 70%-90%; through the spot welding type three-dimensional network structure design, the fiber skeleton provides flexible support, and the bonding units are bonded only at lap joints, so that the material has no fracture when the bending radius is greater than or equal to 50mm, the hardening embrittlement defect caused by excessive traditional inorganic glue is overcome, and the special-shaped scene requirements of battery wrapping corner wrapping, pipeline elbow heat insulation and the like are met.

Description

Technical Field

[0001] This invention relates to the field of inorganic fiber materials technology, specifically to an inorganic flexible fiber paper with a spot-welded fixed three-dimensional network structure and its preparation method. Background Technology

[0002] In the existing technology, fiber paper made from inorganic fibers mainly includes aluminosilicate fiber paper and alumina fiber paper, but they all have obvious technical defects and cannot meet the requirements of being heat-resistant to 1000℃ and completely inorganic.

[0003] In terms of forming process, aluminum silicate fibers, due to their smooth surface and weak inter-fiber hydrogen bonding, must rely on binders to assist in paper formation. Currently, the industry commonly uses organic binders such as acrylic emulsions and ethyl acetate resins, typically adding 8%-15%. These binders begin to soften and decompose above 300℃ and completely burn at 400℃, releasing toxic gases such as formaldehyde and carbon monoxide, which not only pollutes the environment but also causes a sharp drop in the strength of the fiber paper. Some manufacturers have tried to use inorganic binders such as silica sol and water glass, which solves the high-temperature decomposition problem, but require an addition of more than 15% to form an effective bond. Excessive inorganic binders will cause the fiber paper to harden into a plate shape, increasing its bending radius from 10mm for flexible materials to over 60mm, or even making it inflexible, unable to wrap the corners of battery packs, pipe bends, and other similar components; moreover, the hardened fiber paper loses its elasticity and cannot buffer stress under equipment vibration conditions, making it prone to cracking due to rigid impacts. More seriously, the continuous glass phase film formed by inorganic adhesives will develop microcracks due to thermal expansion and contraction during 1000℃ thermal cycling. The continuous shedding of slag can lead to short circuits in the internal circuits of precision instruments or contaminate high-end products such as semiconductor wafers.

[0004] While alumina fiber paper outperforms aluminum silicate in temperature resistance, its production process still faces the bottleneck of balancing fiber dispersion and bonding. The fibers are mostly 5-10 micrometers in diameter, requiring approximately 20% inorganic binder during the papermaking process. It also suffers from hardening and embrittlement issues, and its high cost makes it difficult to promote in the civilian sector.

[0005] In summary, the shortcomings of existing inorganic fiber paper in terms of fiber cleanliness, high-temperature stability, and mechanical adaptability highlight the urgent need to develop fully inorganic flexible fiber paper with different temperature resistance ranges. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides an inorganic flexible fiber paper with a spot-welded fixed three-dimensional network structure and its preparation method, thus solving the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: an inorganic flexible fiber paper with a spot-welded fixed three-dimensional network structure, comprising: A three-dimensional porous fiber skeleton composed of interwoven inorganic fibers, and discontinuous adhesive units formed by inorganic adhesive dispersed at the overlap points of the fiber skeleton. The bonding units are chemically bonded to the fiber overlap points in an isolated point-like form. The fiber skeleton and the bonding units are combined with each other and evenly distributed in the x, y, and z directions, together forming a composite network structure with a porosity of 70%-90%. The inorganic flexible fiber paper is composed entirely of inorganic components, with an overall thickness of 0.3-1.5mm, a tensile strength of 100-300kPa, no breakage when the bending radius is ≥50mm, a temperature resistance range of -20-1000℃, and a mass loss of ≤0.3wt% when kept at 900℃ for 2 hours.

[0008] According to the above technical solution, the bonding unit can also be called a local inorganic joint, which is configured to solidify the entire three-dimensional network structure by providing bonding strength at the fiber overlap point.

[0009] According to the above technical solution, the inorganic fiber has a diameter of 7-11 μm, a length of not less than 6 mm, a concentrated fiber length distribution, and a slag ball content of less than 1 wt%.

[0010] According to the above technical solution, the inorganic fiber is one or more of alumina fiber, aluminum silicate fiber, basalt fiber, glass fiber or ceramic fiber, and its surface is activated to contain abundant hydroxyl active groups. The hydroxyl active groups form coordination bonds with metal ions in the inorganic adhesive, thereby improving the bonding strength between the fiber skeleton and the bonding unit.

[0011] According to the above technical solution, the equivalent diameter of the bonding unit is 6-100μm, and its melting point is 500-2100℃.

[0012] A method for preparing inorganic flexible fiber paper with a spot-welded fixed three-dimensional network structure includes the following steps: S1. Fiber pretreatment: Take the inorganic fiber described in claim 1, place it in a dilute hydrochloric acid solution with a mass concentration of 1%-3%, and stir at 50-60℃ for 30-40 minutes to remove impurities on the fiber surface and introduce hydroxyl active sites. S2. Preparation of inorganic fiber suspension: Add the inorganic fibers pretreated in step S1 to water, and add 0.1%-0.3% polyethylene oxide dispersant. Stir at 300-500 r / min for 60-90 min. After mixing evenly, a uniformly dispersed inorganic fiber suspension is obtained. S3. Gradient low-pressure vacuum filtration: The inorganic fiber suspension obtained in step S2 is transferred to a gradient pore size forming mesh (pore sizes from top to bottom are 80μm, 50μm, and 30μm), and low-pressure vacuum filtration at 0.05-0.1MPa is applied for 10-15 minutes to initially fix the fiber distribution morphology. S4. Gradient high-pressure vacuum filtration: The forming wire after step S3 is further filtered under high pressure of 0.15-0.2MPa for 20-25 minutes to reduce the moisture content of the fiber paper wet blank to 30%-40% and obtain a fiber paper wet blank with uniform fiber distribution and stable structure. S5. Preparation and application of modified organic adhesive: Select one or more of acrylic acid, acrylate, ethylene, and ethyl acetate and add them to water. At the same time, add 0.5%-1% of nano-silica particles (particle size 10-20nm). Disperse the mixture ultrasonically at an ultrasonic power of 300-500W for 20-30 minutes to obtain the modified organic adhesive. Then, apply the modified organic adhesive to the wet fiber paper blank obtained in step S4 by spraying (spraying pressure 0.2-0.3MPa, spraying distance 15-20cm). Dry the blank at 120℃ for 60 minutes to obtain the fiber paper base paper. S6. Preparation and application of stable inorganic binder: Select one or more of aluminum sol, silica sol, yttrium sol, zirconium sol, alumina, silicon oxide, calcium oxide, boron oxide, sodium oxide, or potassium oxide and add them to water. Add 1%-2% citric acid (as a chelating agent), stir at 40-50℃ for 40-50 min, and adjust the pH to 5.5-6.5 to obtain an inorganic binder with improved stability (solid content of 5%-10%, solid melting point of 500-2100℃). Apply it to the fiber paper base paper obtained in step S5 by roller coating (roller coating pressure 0.1-0.15MPa, roller speed 5-8m / min), and dry it at 120℃ for 60 min to obtain fiber paper green paper. S7. High-temperature adhesive removal first stage: Apply a pressure of 0-300Pa above the fiber paper blank obtained in step S6, raise the temperature to 300-400℃ at a rate of 5℃ / min, and keep it at that temperature for 30-40min to initially remove the low-boiling-point components in the organic adhesive. S8. High-temperature degumming and bonding second stage: The fiber paper preform treated in step S7 is heated to 500-1500℃ at a rate of 3℃ / min and held for 60min to complete high-temperature degumming and chemical bonding of fiber-adhesive units. Finally, it is naturally cooled to room temperature in the furnace to obtain the inorganic flexible fiber paper.

[0013] According to the above technical solution, in step S1, the mass concentration of the dilute hydrochloric acid solution is 2%, the stirring temperature is 55℃, and the time is 35min; in step S2, the amount of polyethylene oxide dispersant added is 0.2%, the stirring speed is 400r / min, and the time is 75min.

[0014] According to the above technical solution, in step S3, the low-pressure vacuum filtration pressure is 0.08 MPa and the time is 12 min; in step S4, the high-pressure vacuum filtration pressure is 0.18 MPa and the time is 22 min, and the moisture content of the obtained fiber paper wet blank is 35%.

[0015] According to the above technical solution, in step S5, the amount of nano-silica particles added is 0.8%, the ultrasonic power is 400W, and the time is 25min; the spraying pressure is 0.25MPa, and the spraying distance is 18cm; in step S6, the amount of citric acid added is 1.5%, the stirring temperature is 45℃, the time is 45min, and the pH is adjusted to 6.0; the roller coating pressure is 0.12MPa, and the roller speed is 6m / min.

[0016] According to the above technical solution, in step S7, the temperature is raised to 350℃ and held for 35 minutes; in step S8, the temperature is raised to 950-1450℃ and held for 60 minutes.

[0017] This invention provides an inorganic flexible fiber paper with a spot-welded fixed three-dimensional network structure and its preparation method. It has the following beneficial effects: (1) This invention, through the “spot welding” three-dimensional network structure design, provides flexible support for the fiber skeleton and the bonding unit is bonded only at the overlap point, so that the material does not break when the bending radius is ≥50mm, which overcomes the hardening and embrittlement defects caused by excessive inorganic glue in the traditional method, and meets the needs of irregular scenarios such as battery pack corner wrapping and pipe bend heat insulation.

[0018] (2) This invention avoids the health risks of inhalable particulate matter formed by ultrafine fibers in traditional aluminum silicate fibers, as well as the problems of large-sized slag balls piercing battery separators and abrading precision instruments; there are no harmful impurities left during the preparation process, and no toxic gases such as formaldehyde and carbon monoxide are released after high-temperature degumming, which can be adapted to scenarios with extremely high cleanliness requirements such as semiconductor wafer protection and precision instrument heat insulation.

[0019] (3) This invention solves the problems of weak interfacial bonding and easy cracking and flaking of traditional inorganic fiber paper by activating the fiber surface to form hydroxyl active sites and forming coordination bonds with inorganic glue metal ions, combined with a "spot welding" three-dimensional network structure; at the same time, the 70%-90% interconnected porosity ensures thermal insulation performance and avoids loss of flexibility caused by structural compaction, and can be used stably for a long time under vibration and thermal cycling conditions.

[0020] (4) The invention uses gradient vacuum filtration in the preparation process to ensure uniform fiber distribution, segmented high-temperature degumming to avoid internal stress cracking, low amount of organic adhesive and can be completely removed by high temperature, and inorganic adhesive solid content is only 5%-10%, which reduces adhesive consumption and production costs compared with traditional processes; at the same time, there is no large amount of organic waste liquid discharge, and high-temperature degumming leaves no harmful residues, which meets the requirements of environmental protection production. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the spot-welded fixed three-dimensional network structure of the present invention; Figure 2 This is an optical microscope image of the inorganic flexible fiber paper of the present invention after an organic adhesive has been applied. Figure 3 This is an optical microscope image of the inorganic flexible fiber paper of the present invention after being kept at 950°C for 60 min. Figure 4 This is a schematic diagram of the inorganic flexible fiber paper preparation process of the present invention.

[0022] In the diagram: 1. Fiber skeleton; 2. Adhesive unit. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] Please see Figures 1-4 One embodiment of the present invention is: an inorganic flexible fiber paper having a spot-welded fixed three-dimensional network structure, comprising: A three-dimensional porous fiber skeleton 1 composed of interwoven inorganic fibers, and discontinuous adhesive units 2 formed by inorganic adhesive dispersed at the overlap points of the fiber skeleton 1. The bonding unit 2 is chemically bonded to the fiber overlap point in an isolated point form. The fiber skeleton 1 and the bonding unit 2 are combined with each other and evenly distributed in the x, y and z directions, together forming a composite network structure with a porosity of 70%-90%. Inorganic flexible fiber paper is composed entirely of inorganic components, with an overall thickness of 0.3-1.5mm, a tensile strength of 100-300kPa, no breakage when the bending radius is ≥50mm, a temperature resistance range of -20-1000℃, and a mass loss of ≤0.3wt% when kept at 900℃ for 2 hours.

[0025] The three-dimensional porous structure of the fiber skeleton 1 is formed by the random interweaving of inorganic fibers, and the pores are interconnected; the bonding unit 2 exists only at the fiber overlap point and does not cover the main area of ​​the fiber surface, ensuring that the flexibility of the fiber skeleton is not overly constrained, making the product more flexible and resistant to high temperature stability.

[0026] The bonding unit 2, also known as the local inorganic bonding part, is configured to solidify the entire three-dimensional network structure by providing bonding strength at the fiber overlap point. This ensures that the product can maintain the stability of the three-dimensional network structure under high temperature conditions, solves the problem of sudden strength drop caused by bonding failure in traditional inorganic fiber paper at high temperatures, and improves the long-term reliability of the product.

[0027] The inorganic fibers have a diameter of 7-11μm and a length of not less than 6mm, with a concentrated fiber length distribution and a slag ball content of less than 1wt%, which reduces fiber agglomeration during the forming process and ensures the uniformity of the fiber paper structure. The low slag ball content can prevent puncture of the separator in battery pack insulation scenarios and wear in precision instruments, meet the requirements for high cleanliness, and reduce the health threat to the respiratory tract of operators.

[0028] The inorganic fiber is one or more of alumina fiber, aluminosilicate fiber, basalt fiber, glass fiber, or ceramic fiber. Its surface is activated and contains abundant hydroxyl active groups. The hydroxyl active groups form coordination bonds with metal ions in the inorganic adhesive, which improves the bonding strength between the fiber skeleton 1 and the bonding unit 2, enhances the interfacial bonding force between the fiber and the inorganic adhesive, and avoids the interlayer delamination problem caused by weak interfacial bonding in traditional inorganic fiber paper. The stability of the coordination bonds can improve the product's crack resistance during thermal cycling, reduce flaking, and extend the product's service life.

[0029] The equivalent diameter of the bonding unit 2 is 6-100μm, and its melting point is 500-2100℃. This ensures the consistency of the size and high-temperature resistance of the bonding unit in different batches of products, avoids the fiber flexibility being affected by the bonding unit being too large, or the softening failure at high temperature caused by the melting point being too low, and improves the stability of product quality.

[0030] A method for preparing inorganic flexible fiber paper with a spot-welded fixed three-dimensional network structure includes the following steps: S1. Fiber pretreatment: Take the inorganic fiber of claim 1, place it in a dilute hydrochloric acid solution with a mass concentration of 1%-3%, and stir at 50-60℃ for 30-40 min to remove impurities on the fiber surface and introduce hydroxyl active sites. S2. Preparation of inorganic fiber suspension: Add the inorganic fibers pretreated in step S1 to water, and add 0.1%-0.3% polyethylene oxide dispersant. Stir at 300-500 r / min for 60-90 min. After mixing evenly, a uniformly dispersed inorganic fiber suspension is obtained. S3. Gradient low-pressure vacuum filtration: The inorganic fiber suspension obtained in step S2 is transferred to a gradient pore size forming mesh (pore sizes from top to bottom are 80μm, 50μm, and 30μm), and low-pressure vacuum filtration at 0.05-0.1MPa is applied for 10-15 minutes to initially fix the fiber distribution morphology. S4. Gradient high-pressure vacuum filtration: The forming wire after step S3 is further filtered under high pressure of 0.15-0.2MPa for 20-25 minutes to reduce the moisture content of the fiber paper wet blank to 30%-40% and obtain a fiber paper wet blank with uniform fiber distribution and stable structure. S5. Preparation and application of modified organic adhesive: Select one or more of acrylic acid, acrylate, ethylene, and ethyl acetate and add them to water. At the same time, add 0.5%-1% of nano-silica particles (particle size 10-20nm). Disperse the mixture ultrasonically at an ultrasonic power of 300-500W for 20-30 minutes to obtain the modified organic adhesive. Then, apply the modified organic adhesive to the wet fiber paper blank obtained in step S4 by spraying (spraying pressure 0.2-0.3MPa, spraying distance 15-20cm). Dry the blank at 120℃ for 60 minutes to obtain the fiber paper base paper. S6. Preparation and application of stable inorganic binder: Select one or more of aluminum sol, silica sol, yttrium sol, zirconium sol, alumina, silicon oxide, calcium oxide, boron oxide, sodium oxide, or potassium oxide and add them to water. Add 1%-2% citric acid (as a chelating agent), stir at 40-50℃ for 40-50 min, and adjust the pH to 5.5-6.5 to obtain an inorganic binder with improved stability (solid content of 5%-10%, solid melting point of 500-2100℃). Apply it to the fiber paper base paper obtained in step S5 by roller coating (roller coating pressure 0.1-0.15MPa, roller speed 5-8m / min), and dry it at 120℃ for 60 min to obtain fiber paper green paper. S7. High-temperature adhesive removal first stage: Apply a pressure of 0-300Pa above the fiber paper blank obtained in step S6, raise the temperature to 300-400℃ at a rate of 5℃ / min, and keep it at that temperature for 30-40min to initially remove the low-boiling-point components in the organic adhesive. S8. High-temperature degumming and bonding second stage: The fiber paper preform treated in step S7 is heated to 500-1500℃ at a rate of 3℃ / min and held for 60min to complete high-temperature degumming and chemical bonding of fiber-adhesive units. Finally, it is naturally cooled to room temperature in the furnace to obtain inorganic flexible fiber paper.

[0031] In step S1, the mass concentration of the dilute hydrochloric acid solution is 2%, the stirring temperature is 55℃, and the time is 35 min; in step S2, the amount of polyethylene oxide dispersant added is 0.2%, the stirring speed is 400 r / min, and the time is 75 min.

[0032] In step S3, the low-pressure vacuum filtration pressure is 0.08 MPa and the time is 12 min; in step S4, the high-pressure vacuum filtration pressure is 0.18 MPa and the time is 22 min, and the moisture content of the resulting fiber paper wet blank is 35%.

[0033] In step S5, the amount of nano-silica particles added is 0.8%, the ultrasonic power is 400W, and the time is 25min; the spraying pressure is 0.25MPa, and the spraying distance is 18cm; in step S6, the amount of citric acid added is 1.5%, the stirring temperature is 45℃, the time is 45min, and the pH is adjusted to 6.0; the roller coating pressure is 0.12MPa, and the roller speed is 6m / min.

[0034] In step S7, the temperature is raised to 350℃ and held for 35 minutes; in step S8, the temperature is raised to 950-1450℃ and held for 60 minutes.

[0035] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An inorganic flexible fiber paper with a spot-welded fixed three-dimensional network structure, characterized in that, include: A three-dimensional porous fiber skeleton (1) composed of interwoven inorganic fibers, and discontinuous adhesive units (2) formed by inorganic adhesive dispersed at the overlap points of the fiber skeleton (1). The adhesive unit (2) is chemically bonded to the fiber overlap point in an isolated point form. The fiber skeleton (1) and the adhesive unit (2) are combined with each other and evenly distributed in the x, y and z directions, forming a composite network structure with a porosity of 70%-90%. The inorganic flexible fiber paper is composed entirely of inorganic components, with an overall thickness of 0.3-1.5mm, a tensile strength of 100-300kPa, no breakage when the bending radius is ≥50mm, a temperature resistance range of -20-1000℃, and a mass loss of ≤0.3wt% when kept at 900℃ for 2 hours.

2. The inorganic flexible fiber paper with a spot-welded fixed three-dimensional network structure according to claim 1, characterized in that: The adhesive unit (2) can also be referred to as a local inorganic bond, which is configured to consolidate the entire three-dimensional network structure by providing bonding strength at the fiber overlap point.

3. The inorganic flexible fiber paper with a spot-welded fixed three-dimensional network structure according to claim 2, characterized in that: The inorganic fibers have a diameter of 7-11 μm, a length of not less than 6 mm, and a concentrated fiber length distribution, with a slag ball content of less than 1 wt%.

4. The inorganic flexible fiber paper with a spot-welded fixed three-dimensional network structure according to claim 3, characterized in that: The inorganic fiber is one or more of alumina fiber, aluminum silicate fiber, basalt fiber, glass fiber or ceramic fiber. Its surface is activated and contains abundant hydroxyl active groups. The hydroxyl active groups form coordination bonds with metal ions in the inorganic adhesive, thereby improving the bonding strength between the fiber skeleton (1) and the bonding unit (2).

5. An inorganic flexible fiber paper with a spot-welded fixed three-dimensional network structure according to claim 4, characterized in that: The equivalent diameter of the bonding unit (2) is 6-100μm, and its melting point is 500-2100℃.

6. A method for preparing inorganic flexible fiber paper with a spot-welded fixed three-dimensional network structure, characterized in that, Includes the following steps: S1. Fiber pretreatment: Take the inorganic fiber described in claim 1, place it in a dilute hydrochloric acid solution with a mass concentration of 1%-3%, and stir at 50-60℃ for 30-40 minutes to remove impurities on the fiber surface and introduce hydroxyl active sites. S2. Preparation of inorganic fiber suspension: Add the inorganic fibers pretreated in step S1 to water, and add 0.1%-0.3% polyethylene oxide dispersant. Stir at 300-500 r / min for 60-90 min. After mixing evenly, a uniformly dispersed inorganic fiber suspension is obtained. S3. Gradient low-pressure vacuum filtration: The inorganic fiber suspension obtained in step S2 is transferred to a gradient pore size forming mesh (pore sizes from top to bottom are 80μm, 50μm, and 30μm), and low-pressure vacuum filtration at 0.05-0.1MPa is applied for 10-15 minutes to initially fix the fiber distribution morphology. S4. Gradient high-pressure vacuum filtration: The forming wire after step S3 is further filtered under high pressure of 0.15-0.2MPa for 20-25 minutes to reduce the moisture content of the fiber paper wet blank to 30%-40% and obtain a fiber paper wet blank with uniform fiber distribution and stable structure. S5. Preparation and application of modified organic adhesive: Select one or more of acrylic acid, acrylate, ethylene, and ethyl acetate and add them to water. At the same time, add 0.5%-1% of nano-silica particles (particle size 10-20nm). Disperse the mixture ultrasonically at an ultrasonic power of 300-500W for 20-30 minutes to obtain the modified organic adhesive. Then, apply the modified organic adhesive to the wet fiber paper blank obtained in step S4 by spraying (spraying pressure 0.2-0.3MPa, spraying distance 15-20cm). Dry the blank at 120℃ for 60 minutes to obtain the fiber paper base paper. S6. Preparation and application of stable inorganic binder: Select one or more of aluminum sol, silica sol, yttrium sol, zirconium sol, alumina, silicon oxide, calcium oxide, boron oxide, sodium oxide, or potassium oxide and add them to water. Add 1%-2% citric acid (as a chelating agent), stir at 40-50℃ for 40-50 min, and adjust the pH to 5.5-6.5 to obtain an inorganic binder with improved stability (solid content of 5%-10%, solid melting point of 500-2100℃). Apply it to the fiber paper base paper obtained in step S5 by roller coating (roller coating pressure 0.1-0.15MPa, roller speed 5-8m / min), and dry it at 120℃ for 60 min to obtain fiber paper green paper. S7. High-temperature adhesive removal first stage: Apply a pressure of 0-300Pa above the fiber paper blank obtained in step S6, raise the temperature to 300-400℃ at a rate of 5℃ / min, and keep it at that temperature for 30-40min to initially remove the low-boiling-point components in the organic adhesive. S8. High-temperature degumming and bonding second stage: The fiber paper preform treated in step S7 is heated to 500-1500℃ at a rate of 3℃ / min and held for 60min to complete high-temperature degumming and chemical bonding of fiber-adhesive units. Finally, it is naturally cooled to room temperature in the furnace to obtain the inorganic flexible fiber paper.

7. The method for preparing an inorganic flexible fiber paper with a spot-welded fixed three-dimensional network structure according to claim 6, characterized in that: In step S1, the mass concentration of the dilute hydrochloric acid solution is 2%, the stirring temperature is 55℃, and the time is 35 min; in step S2, the amount of polyethylene oxide dispersant added is 0.2%, the stirring speed is 400 r / min, and the time is 75 min.

8. The method for preparing an inorganic flexible fiber paper with a spot-welded fixed three-dimensional network structure according to claim 7, characterized in that: In step S3, the low-pressure vacuum filtration pressure is 0.08 MPa and the time is 12 min; in step S4, the high-pressure vacuum filtration pressure is 0.18 MPa and the time is 22 min, and the moisture content of the resulting fiber paper wet blank is 35%.

9. The inorganic flexible fiber paper with a spot-welded fixed three-dimensional network structure and its preparation method according to claim 8, characterized in that: In step S5, the amount of nano-silica particles added is 0.8%, the ultrasonic power is 400W, and the time is 25min; the spraying pressure is 0.25MPa, and the spraying distance is 18cm; in step S6, the amount of citric acid added is 1.5%, the stirring temperature is 45℃, the time is 45min, and the pH is adjusted to 6.0; the roller coating pressure is 0.12MPa, and the roller speed is 6m / min.

10. The inorganic flexible fiber paper with a spot-welded fixed three-dimensional network structure and its preparation method according to claim 9, characterized in that: In step S7, the temperature is raised to 350℃ and held for 35 minutes; in step S8, the temperature is raised to 950-1450℃ and held for 60 minutes.

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