A surface-strengthened ceramic fiber flexible thermal insulation structure and its preparation method and application

Abstract

The present invention relates to the field of thermal protection materials, and in particular to a surface-toughened ceramic fiber flexible thermal insulation structure, its preparation method, and its application. The structure comprises a high-temperature alloy foil, a high-temperature alloy woven mesh, and a ceramic fiber layer stacked sequentially from the high-temperature side to the low-temperature side. The ceramic fiber layer comprises a high-temperature side ceramic fiber cloth, several layers of ceramic fiber filling layers, and a low-temperature side ceramic fiber cloth stacked sequentially, with a reflective screen provided between adjacent layers of ceramic fiber filling layers. The ceramic fiber layers are secured with ceramic fiber sewing thread, and the high-temperature alloy woven mesh and ceramic fiber layers are secured with high-temperature alloy sewing thread. The thermal insulation structure provided by the present invention is flexible, lightweight, and exhibits excellent properties such as high-temperature resistance, airflow erosion resistance, high toughness, and low thermal conductivity.

Description

Technical Field

[0001] The present invention relates to the field of thermal protection materials, and in particular to a surface-strengthened ceramic fiber flexible thermal insulation structure, a preparation method thereof, and applications thereof. Background Art

[0002] Due to the specific needs of aerospace and other industries for lightweight, highly heat-resistant flexible insulation materials, multi-layer insulation materials are widely used in thermal protection systems to maintain the temperature of the underlying structure within acceptable ranges. Ceramic fiber flexible insulation blankets, made of quartz needle-punched blanket and quartz cloth sewn with quartz sewing thread, are large-scale, reusable thermal protection components for the leeward side of the space shuttle. Their thermal protection performance has been fully verified in space shuttle engineering.

[0003] NASA's Ames Research Center developed the first generation of ceramic fiber flexible insulation blankets (Advanced Flexible Reusable Surface Insulation, AFRSI). This blanket was used as a large-area reusable thermal shield for the leeward side of the space shuttle and was fully validated in the US space shuttle program (Sawko, PM and HE Goldstein (1992). Performance of Uncoated AFRSI Blankets during Multiple Space Shuttle Flights. http: / / ntrs.nasa.gov). AFRSI is made of quartz needle-punched blanket and quartz cloth sewn with quartz sewing thread.

[0004] Furthermore, Calamito's research (Calamito, DP (1989). Tailorable advanced blanket insulation using aluminoborosilicate and alumina batting. NASA Contractor Report-177527) revealed a tailorable flexible thermal insulation material with a novel structural form, which has important applications in aerostats, spacecraft entry / return capsule parachute thermal protection systems, and more. Boeing's U.S. Patent 9,005,702B2 disclosed a reusable, high-temperature-resistant, flexible thermal insulation blanket for aerospace applications.

[0005] Hypersonic vehicles must withstand extremely high aerodynamic heating and pressure loads during the ascent and re-entry phases. The ceramic fabric on the top is easily torn and broken, causing physical damage and leading to water vapor infiltration. The method for improving the thermal insulation blanket is often to increase the density of the ceramic fabric to improve the high-temperature mechanical strength of the thermal insulation blanket. For example, China Publication No. CN114714686A discloses an antioxidant, low thermal conductivity, high-temperature resistant flexible thermal insulation material and its preparation method. However, the ability to resist airflow scouring and the thermal conductivity effect of this improvement method are still not ideal, which limits the application of ceramic fiber thermal insulation blankets in engineering. At present, there is an urgent need to explore a new type of surface-strengthened ultrafine ceramic fiber flexible insulation structure to ensure that the component has a high operating temperature while ensuring the aerodynamic smooth transition of the outer surface and improving the ability to resist airflow scouring. Summary of the Invention

[0006] In order to solve the above-mentioned technical problems existing in the prior art, the present invention provides a surface-reinforced ceramic fiber flexible thermal insulation structure and its preparation method and application. The thermal insulation structure (blanket) of the present invention is flexible and lightweight, and has excellent properties such as high temperature resistance, resistance to airflow erosion, strong toughness and low thermal conductivity.

[0007] In order to achieve the above objectives, the present invention adopts the following technical solutions.

[0008] In a first aspect, the present invention provides a surface-reinforced ultrafine ceramic fiber flexible thermal insulation structure comprising a high-temperature alloy foil, a high-temperature alloy woven mesh, and a ceramic fiber layer stacked sequentially from the high-temperature side to the low-temperature side. The ceramic fiber layer comprises a high-temperature side ceramic fiber cloth, several layers of ceramic fiber filling layers, and a low-temperature side ceramic fiber cloth stacked sequentially, with a reflective screen positioned between adjacent layers of the ceramic fiber filling layers. The ceramic fiber layers are secured by ceramic fiber sewing thread, and the high-temperature alloy woven mesh and ceramic fiber layers are secured by high-temperature alloy sewing thread. In the present invention, the heated surface of the surface-reinforced ultrafine ceramic fiber flexible thermal insulation blanket is the high-temperature side, and the side facing away from the heated surface is the low-temperature side. By utilizing this multi-layered structure design, which sequentially comprises the high-temperature alloy foil, the high-temperature alloy woven mesh, and the ceramic fiber layer, combined with a method of securing the ceramic fiber layer, the ceramic fiber sewing thread, and the high-temperature alloy sewing thread, the present invention achieves a flexible, lightweight, and excellent performance, including high-temperature resistance, airflow erosion resistance, high toughness, and low thermal conductivity. The ceramic fiber layer integrates ceramic fiber cloth, ceramic fiber filling layer, ceramic fiber cloth and reflective screen, and ceramic fiber sewing thread is used for sewing, which further improves the overall high temperature resistance and thermal insulation capabilities; the high temperature surface ceramic fiber cloth is wrapped with a layer of high temperature alloy woven mesh, and high temperature alloy sewing thread is used for sewing, which can prevent the high temperature surface of the ceramic fiber layer from becoming brittle and the fibers from falling off under the impact of high temperature hot air flow, thereby enhancing the tear strength of the high temperature surface of the ceramic fiber layer; the surface of the high temperature alloy woven mesh is covered with high temperature alloy foil, which can sustainably withstand multiple air heat flows and keep the top surface from bending. The high temperature surface is a high temperature alloy foil, which can also prevent moisture penetration and heat flow in special environments and ensure the aerodynamic smooth transition of the high temperature surface.

[0009] Preferably, a layer of the high-temperature alloy foil is welded to the surface of the high-temperature alloy woven mesh, and the welding is preferably brazing; the high-temperature surface ceramic fiber cloth is wrapped around the low-temperature surface ceramic fiber cloth; and the high-temperature alloy woven mesh seals the high-temperature surface ceramic fiber cloth. In the present invention, a layer of high-temperature alloy foil is brazed on the surface of the high-temperature alloy woven mesh, which can further improve the material's resistance to breakage and other properties, while maintaining the smoothness of the surface, making it more adaptable to special environments such as high temperature and heat flow. At the same time, the high-temperature surface ceramic fiber cloth is used to wrap the low-temperature surface ceramic fiber cloth. This design enhances the stability of the overall structure, prevents heat leakage from the edge, and further improves the thermal insulation effect. At the same time, the high-temperature alloy woven mesh seals the high-temperature surface ceramic fiber cloth, further enhancing the material's tear resistance and durability, preventing the ceramic fibers from becoming brittle and falling off under high temperature, and ensuring the structural integrity and service life under the impact of high-temperature hot air flow.

[0010] Preferably, the density of the surface toughened ceramic fiber flexible insulation structure is 150-300 kg / m 3 , preferably 160-200kg / m3 The surface-strengthened ceramic fiber flexible thermal insulation structure provided by the present invention reduces the weight burden in the application while maintaining the effects of flexibility, high temperature resistance, air flow erosion resistance, strong toughness and low thermal conductivity. The density of the surface-strengthened ceramic fiber flexible thermal insulation structure of the present invention can be less than 195kg / m³, for example 195kg / m³. 3 、194kg / m 3 、193kg / m 3 、189kg / m 3 、188kg / m 3 、187kg / m 3 、185kg / m 3 、175kg / m 3 、165kg / m 3 wait.

[0011] Preferably, in the ceramic fiber layer, the ceramic fiber filling layer is ceramic fiber cotton or ceramic fiber blanket.

[0012] Preferably, the reflective screen is aluminum foil or polyimide aluminum-coated film.

[0013] Further preferably, the number of ceramic fiber filling layers is 2-11, and the number of reflective screen layers is 1-10. Preferably, the number of reflective screen layers is one less than the number of ceramic fiber filling layers. The combination and parameters of the reflective screen and ceramic fiber filling layer employed in the present invention optimize the thermal insulation effect and structural strength, further enhancing the overall performance of the thermal insulation structure.

[0014] Preferably, the ceramic fiber filling layer is selected from one or more of quartz fiber wool, quartz fiber needle-punched blanket, alumina fiber wool and alumina fiber needle-punched blanket.

[0015] Preferably, the thickness of the quartz fiber needle-punched blanket is 5-20 mm, and the bulk density is 0.05-0.2 g / cm 3 The thickness of the alumina fiber needle-punched blanket is 5-25 mm, and the bulk density is 0.05-0.2 g / cm 3 .

[0016] Preferably, the ceramic fiber sewing thread is an alumina fiber yarn or a quartz fiber yarn; preferably, the ceramic fiber sewing thread is coated, and the coating treatment includes impregnating the surface of the twisted ceramic fiber sewing thread with polytetrafluoroethylene emulsion.

[0017] Preferably, the size of the ceramic fiber sewing thread is 90-300tex.

[0018] In the present invention, the ceramic fiber sewing thread adopts a (continuous) alumina fiber yarn or a (continuous) quartz fiber yarn that has been coated. The coating treatment includes impregnating the surface of the (continuous) ceramic fiber sewing thread that has been twisted with polytetrafluoroethylene emulsion. After this (continuous) treatment, the lubricity of the ceramic fiber sewing thread can be increased and wear and breakage can be reduced.

[0019] Preferably, the high-temperature surface ceramic fiber cloth is quartz fiber cloth or alumina fiber cloth; the low-temperature surface ceramic fiber cloth is quartz fiber cloth or alumina fiber cloth.

[0020] More preferably, the silica content of the quartz fiber cloth is 90%-99.9%; the alumina content of the alumina fiber cloth is 70%-99.9%, for example, the alumina content is 72%, 80%, 85%, 95% or 99%.

[0021] More preferably, the thickness of the high-temperature surface ceramic fiber cloth is 0.1-1.0 mm; the thickness of the low-temperature surface ceramic fiber cloth is 0.1-1.0 mm.

[0022] Further preferably, the high-temperature surface ceramic fiber cloth is plain, twill or satin; and the low-temperature surface ceramic fiber cloth is plain, twill or satin.

[0023] More preferably, the surface density of the high temperature surface ceramic fiber cloth is 100-275g / m 2 The surface density of the low-temperature ceramic fiber cloth is 100-275g / m 2 ; For example 105g / m 2 , 108g / m 2 , 245g / m 2 , 255g / m 2 , 265g / m 2 wait.

[0024] Preferably, the high-temperature alloy braided mesh is made of nickel-based high-temperature alloy.

[0025] Preferably, the high-temperature alloy braided mesh is woven from one or more wires selected from Inconel-600, Inconel-601, Inconel-617 and Inconel-625, and the mesh size of the high-temperature alloy braided mesh is 50-500 mesh.

[0026] Preferably, the high-temperature alloy sewing thread is a nickel-based high-temperature alloy wire or an iron-based high-temperature alloy wire.

[0027] Preferably, the material of the nickel-based high-temperature alloy wire is at least one of GH3030, GH3600, GH3602, GH3625, GH4049, GH4033 and GH4043; the iron-based high-temperature alloy wire is 316L stainless steel sewing wire.

[0028] Preferably, the diameter of the high-temperature alloy sewing thread is 0.25-1 mm.

[0029] Preferably, the high-temperature alloy foil is a nickel-based high-temperature alloy foil, a stainless steel foil or an aluminum foil.

[0030] Preferably, the material of the high-temperature alloy foil is Inconel-600, Inconel-601, Inconel-617 or Inconel-625, and the thickness of the high-temperature alloy foil is 0.2-2 mm.

[0031] In a second aspect, the present invention provides a method for preparing the surface-toughened ceramic fiber flexible thermal insulation structure, comprising the following steps.

[0032] 1) Laying a high-temperature surface ceramic fiber cloth, a ceramic fiber filling layer, a reflective screen, and a low-temperature surface ceramic fiber cloth to obtain a ceramic fiber layer; wrapping the low-temperature surface ceramic fiber cloth with the high-temperature surface ceramic fiber cloth and sewing and fixing it with ceramic fiber sewing thread.

[0033] 2) Covering the high-temperature surface ceramic fiber cloth with a layer of high-temperature alloy woven mesh; using the high-temperature alloy woven mesh to semi-enclose the side edges of the high-temperature surface ceramic fiber cloth and sewing and fixing them with high-temperature alloy sewing thread.

[0034] 3) A layer of high-temperature alloy foil is brazed on the surface of the high-temperature alloy woven mesh.

[0035] Preferably, in step 1), the single side reserved margin of the high temperature surface ceramic fiber cloth is 20-100 mm, and the single side reserved margin of the high temperature surface ceramic fiber cloth is used to wrap the low temperature surface ceramic fiber cloth.

[0036] Preferably, in step 2), the single side reserved margin of the high-temperature surface of the high-temperature alloy woven mesh is 10-40 mm, and the single side reserved margin of the high-temperature surface of the high-temperature alloy woven mesh is used to semi-enclose the side edge of the ceramic fiber cloth on the high-temperature surface.

[0037] In the present invention, a ceramic fiber layer is obtained by laminating a high-temperature surface ceramic fiber cloth, a ceramic fiber filling layer, a reflective screen, and a low-temperature surface ceramic fiber cloth, achieving the integration of the multi-layer structure and improving the high-temperature resistance and heat insulation performance of the material. The high-temperature surface ceramic fiber cloth is edge-wrapped and stitched and fixed with ceramic fiber sewing threads, enhancing the structural stability and durability. The high-temperature surface ceramic fiber cloth is covered with a high-temperature alloy woven mesh and its edge sealing treatment, further improving the tear resistance strength and durability of the material. A high-temperature alloy foil is brazed on the surface of the high-temperature alloy woven mesh, ensuring the surface smoothness and waterproof performance of the material in a high-temperature environment. By preferably reserving a side length margin for edge wrapping and semi-surrounding edge sealing treatment, the edge stability of the ceramic fiber cloth and the durability of the overall structure are improved, and at the same time, the edge fixing property and tear resistance strength of the high-temperature alloy woven mesh are improved.

[0038] Preferably, in step 2), the high-temperature alloy sewing thread and the ceramic fiber sewing thread in step 1) are alternately stitched to form a grid pattern.

[0039] In the present invention, the ceramic fiber sewing thread and the high-temperature alloy sewing thread are alternately stitched to jointly form a "grid" pattern, combining the raw material layers of different components into a whole; this not only improves the strength and fracture toughness between the composite materials, but also increases the dimensional stability of the sample, and the sewing process is simple and easy to implement.

[0040] Further preferably, in steps 1) and 2), the stitching is in the shape of a grid stitch.

[0041] Further preferably, in steps 1) and 2), the stitching row spacing of the ceramic fiber layer is 20 - 100 mm, the stitch pitch is 5 - 30 mm, the stitching row spacing of the high-temperature alloy woven mesh is 20 - 100 mm, the stitch pitch is 5 - 30 mm, the sewing threads of the ceramic fiber layer and the high-temperature alloy woven mesh are in an alternating stitching manner, the sewing threads of the ceramic fiber layer and the high-temperature alloy woven mesh do not overlap and have the same row spacing; the ceramic fiber sewing thread and the high-temperature alloy sewing thread form a grid pattern.

[0042] Further preferably, in step 2), the high-temperature alloy sewing thread is stitched on the center line of the stitching row spacing of the ceramic fiber layer, obtaining a grid pattern jointly composed of the ceramic fiber sewing threads and the high-temperature alloy sewing threads on the inner and outer surfaces.

[0043] The preparation process of the surface toughened ultra-fine ceramic fiber flexible heat insulation blanket provided by the present invention adopts a specific stitching method, increasing the dimensional stability of the sample, improving the strength and fracture toughness between the composite materials, and also improving the safety of material use. The maximum use temperature of the flexible heat insulation blanket reaches above 1300 °C, having excellent comprehensive performance.

[0044] Preferably, the mesh-shaped suture includes the following steps: sewing a single-pass suture in a continuous "M" shape, and sewing from both the upper and lower surfaces, the sutures on the two sides passing through the same point and in opposite directions; obtaining a continuous mesh-shaped line.

[0045] Preferably, the ceramic fiber sewing thread is used to sew the ceramic fiber layer, which can be as follows: the ceramic fiber sewing thread is passed through the ceramic fiber layer for sewing, and the ends are bent, stretched and tightened when sewing, and the ends are knotted at the edges, and the ceramic fiber sewing thread is hidden inside the ceramic fiber layer, and excess ceramic fiber sewing thread is removed. The process of sewing and fixing with high-temperature alloy sewing thread can be as follows: the high-temperature alloy sewing thread is passed through the high-temperature alloy braided mesh and the ceramic fiber layer for sewing, and the ends are bent, stretched and tightened when sewing, and the ends are knotted at the edges, and the high-temperature alloy sewing thread is hidden inside the high-temperature alloy braided mesh and the ceramic fiber layer, and excess high-temperature alloy sewing thread is removed.

[0046] Preferably, in step 3), the brazing comprises placing a brazing material in the middle of a high-temperature braided mesh, applying appropriate contact pressure, and heating to a temperature of 500-1260°C in a vacuum or inert atmosphere for brazing. In the present invention, the ceramic fiber layer, high-temperature alloy braided mesh, and high-temperature alloy sewing thread generally have a temperature resistance range of 600-1260°C. The brazing temperature is set at 500-1260°C to avoid damage to the ceramic fiber layer, high-temperature alloy braided mesh, and high-temperature alloy sewing thread.

[0047] In the present invention, the high-temperature alloy foil layer is fixed by brazing technology, which can ensure the integrity of the high-temperature alloy foil layer and is more conducive to the aerodynamically smooth transition of the high-temperature surface.

[0048] Preferably, the brazing is performed at alternating connection points of the high-temperature alloy sewing thread; and the brazing material is a paste or wire material.

[0049] Preferably, the brazing is performed at alternating connection points of the high temperature alloy sewing thread.

[0050] The third invention, the present invention also provides the application of the above-mentioned surface-reinforced ceramic fiber flexible thermal insulation structure or the surface-reinforced ceramic fiber flexible thermal insulation structure obtained by the above-mentioned preparation method in the thermal protection system of hypersonic aircraft.

[0051] The beneficial effects of the present invention are at least as follows: The surface toughened ceramic fiber flexible heat insulation structure provided by the present invention selects high-temperature resistant heat insulation materials. The service temperature of the flexible heat insulation blanket can reach above 1300 °C, and it has excellent properties such as flexibility, light weight, resistance to gas flow erosion, strong toughness, and low thermal conductivity while being high-temperature resistant. The present invention introduces a high-temperature alloy foil on the high-temperature side, which can play roles such as heat flow and moisture penetration resistance in special environments, and ensure the aerodynamic smooth transition of the high-temperature side, keeping the top surface from bending; the multi-layer heat insulation structure adopted by the ceramic fiber layer of the present invention has a reflective screen foil placed close to the cold boundary, with good heat insulation performance. The ceramic fiber layer is made of ceramic fiber materials, improving the overall high-temperature resistance and heat insulation effect of the material. It solves the problems that the currently used aluminum foil layer heat insulation film generally has poor high-temperature resistance, and the heat insulation film cannot withstand high-temperature baking for a long time and is prone to softening; a high-temperature alloy woven mesh is wrapped on the high-temperature side to prevent the ceramic fiber layer from becoming brittle and falling off at high temperatures, enhancing the tear resistance of the high-temperature side and improving the overall durability. The preparation process of the present invention and the sewing method adopted increase the dimensional stability and improve the strength and fracture toughness between composite materials. The ceramic fiber sewing thread and the high-temperature alloy sewing thread of the present invention are alternately sewn to jointly form a "field" pattern, combining the raw materials of each layer with different components into a whole, which can not only improve the strength and fracture toughness between composite materials, but also further increase the dimensional stability, and the sewing process of the present invention is simple and easy to implement. The present invention uses brazing technology to fix the high-temperature alloy foil, ensuring the integrity of the high-temperature alloy foil and being beneficial to the aerodynamic smooth transition of the high-temperature side. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art.

[0053] Figure 1 It is a top view structure provided by Embodiment 1 of the present invention.

[0054] Figure 2 It is an A-A sectional view structure provided by Embodiment 1 of the present invention.

[0055] Figure 3 It is the test results of the thermal conductivity at different temperatures provided by Embodiment 4 of the present invention and Comparative Example 3.

[0056] Figure 4 It is the physical side view, physical front view, front view of the outer high-temperature alloy woven mesh, and back view of the outer high-temperature alloy woven mesh provided by Embodiment 1 of the present invention.

[0057] Figure 5 It is a test sample of the heat insulation skirt of a certain model launch vehicle fairing with furnace performance provided by Comparative Example 4 of the present invention.

[0058] Figure 6 This is a furnace performance test sample of a thermal insulation cover of a high-temperature equipment in a space station provided in comparative example 5 of the present invention.

[0059] Among them, 1-high temperature alloy foil, 2-high temperature alloy woven mesh, 3-high temperature surface ceramic fiber cloth, 4-low temperature surface ceramic fiber cloth, 5-ceramic fiber filling layer, 6-ceramic fiber sewing thread, 7-high temperature alloy sewing thread, 8-reflective screen. DETAILED DESCRIPTION

[0060] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0061] In the following specific embodiments, the manufacturer of quartz fiber cloth (silicon dioxide content 99.9%), quartz fiber cotton (silicon dioxide content 99.9%), quartz fiber blanket, and quartz fiber sewing thread is Hubei Feilihua Quartz Glass Co., Ltd.; the manufacturer of alumina fiber cloth (alumina content 95%), alumina fiber cotton, alumina fiber blanket, and alumina fiber sewing thread is Shanghai Rongrong New Materials Technology Co., Ltd.; and the high-temperature alloy woven mesh, high-temperature alloy sewing thread, reflective screen, and high-temperature alloy foil are commercially available.

[0062] The following embodiments of the present invention provide a surface-reinforced ceramic fiber flexible insulation structure, in which the insulation blanket is composed of a high-temperature alloy foil, a high-temperature alloy woven mesh, and a ceramic fiber layer from the high-temperature side to the low-temperature side, wherein the ceramic fiber layer is a high-temperature side ceramic fiber cloth, several layers of ceramic fiber filling layers, and a low-temperature side ceramic fiber cloth stacked in sequence, a reflective screen is provided between two adjacent layers of ceramic fiber filling layers, the ceramic fiber layer is fixed by ceramic fiber sewing thread, and the high-temperature alloy woven mesh and the ceramic fiber layer are fixed by high-temperature alloy sewing thread.

[0063] The surface-strengthened ceramic fiber flexible thermal insulation structure provided in the following embodiments of the present invention is prepared by the following steps.

[0064] Step 1: Cut and weigh the required high-temperature insulation materials as required.

[0065] According to the requirements of bulk density and size, calculate the mass of each component, cut and weigh to obtain the raw materials. Among them, the cutting dimensions of the low-temperature surface ceramic fiber cloth, the ceramic fiber filling layer, and the reflective screen are determined according to the finished product size; for the high-temperature surface ceramic fiber cloth closest to the heating surface, a unilateral side length allowance is reserved for hemming and sewing with the low-temperature surface ceramic fiber cloth, and a unilateral side length allowance is reserved for the high-temperature alloy woven mesh and the high-temperature alloy foil for semi-surround edge sealing on the side.

[0066] Step 2: Structure from the low-temperature surface to the high-temperature surface of the ceramic fiber layer: The low-temperature surface ceramic fiber cloth, the ceramic fiber filling layer, the reflective screen, and the high-temperature surface ceramic fiber cloth are laid to obtain the ceramic fiber layer; or: The low-temperature surface ceramic fiber cloth, the alternating structure of multiple ceramic fiber filling layers and multiple reflective screens, and the high-temperature surface ceramic fiber cloth are laid to obtain the ceramic fiber layer.

[0067] Step 3: Sewing; Pass the ceramic fiber sewing thread through the ceramic fiber layer for sewing. When sewing at both ends, bend, stretch and tighten, finish with a knot at the edge, and remove the excess high-toughness ceramic fiber sewing thread to complete the sewing of the ceramic fiber layer.

[0068] Sewing method: The one-way sewing thread is sewn in a continuous "zigzag" shape, sewn from the upper and lower sides respectively. The penetration points of the sewing threads on both sides are the same, and the sewing thread directions are opposite; through this sewing method, a line that seems to form a continuous "grid" shape on the side when the two sides are combined is obtained.

[0069] Step 4: Cover a layer of high-temperature alloy woven mesh on the high-temperature surface ceramic fiber cloth, and use the same sewing method as in Step 3 to sew and fix it with high-temperature alloy sewing thread; when sewing with high-temperature alloy sewing thread, it is sewn on the center line of the row spacing of the ceramic fiber layer. After the high-temperature alloy woven mesh and the ceramic fiber layer are sewn, the sewing threads on the inner and outer surfaces together form a "field" pattern, and the ceramic fiber layer and the high-temperature alloy woven mesh form the high-temperature alloy layer.

[0070] Step 5: Weld a layer of high-temperature alloy foil on its surface at the alternating connection points of the high-temperature alloy sewing threads by using brazing technology to complete the preparation of the surface-strengthened ultra-fine ceramic fiber flexible heat insulation blanket. The brazing material is in the form of paste or filament. The brazing process is to place the brazing material in the middle of the high-temperature woven mesh and apply appropriate contact pressure to the high-temperature alloy foil, and then place the entire component in a vacuum or inert gas brazing furnace, and the brazing temperature is 500 - 1260 °C. Example 1

[0071] This example provides a surface-strengthened ultra-fine ceramic fiber flexible heat insulation blanket, the structure of which is as Figure 1 and Figure 2As shown, the insulation blanket is sequentially stacked from the high-temperature side to the low-temperature side, comprising a high-temperature alloy foil 1, a high-temperature alloy woven mesh 2, and a ceramic fiber layer. The ceramic fiber layer comprises a high-temperature side ceramic fiber cloth 3, several layers of ceramic fiber filling layers 5, and a low-temperature side ceramic fiber cloth 4. A reflective screen 8 is placed between two adjacent layers of ceramic fiber filling layers 5. The ceramic fiber layers are secured with ceramic fiber sewing thread 6, and the high-temperature alloy woven mesh 2 and the ceramic fiber layers are secured with high-temperature alloy sewing thread 7. A layer of high-temperature alloy foil 1 is brazed onto the surface of the high-temperature alloy woven mesh 2; the high-temperature side ceramic fiber cloth 3 wraps around the low-temperature side ceramic fiber cloth 4; and the high-temperature alloy woven mesh 2 semi-encloses and seals the sides of the high-temperature side ceramic fiber cloth 4.

[0072] The high temperature alloy foil is an Inconel 625 high temperature alloy foil with a size of 240 mm×240 mm×0.5 mm.

[0073] The high-temperature alloy woven mesh is a 240mm×240mm×0.3mm, 100-mesh Inconel 625 high-temperature alloy woven mesh.

[0074] The high temperature surface ceramic fiber cloth has a size of 260mm×260mm×0.1mm and a surface density of 108g / m 2 Plain quartz fiber cloth.

[0075] The low-temperature surface ceramic fiber cloth has a size of 220mm×220mm×0.1mm and a surface density of 108g / m 2 Plain quartz fiber cloth.

[0076] The ceramic fiber filling layer consists of two layers of 220mm×220mm×8mm in size and a bulk density of 0.1g / cm 3 A quartz fiber needle-punched blanket and a layer of 220 mm × 220 mm × 15 μm aluminum foil are alternately laminated to obtain it.

[0077] Ceramic fiber sewing thread is 195tex quartz fiber sewing thread (treated with polytetrafluoroethylene emulsion coating).

[0078] The high-temperature alloy sewing thread is 316L stainless steel sewing thread with a diameter of 0.4 mm.

[0079] The surface-strengthened ultrafine ceramic fiber flexible thermal insulation blanket provided in this embodiment is prepared by the following steps.

[0080] Step 1: Cut and weigh the required high-temperature insulation materials as required.

[0081] According to the requirements of bulk density and size, calculate the mass of each component, cut and weigh to obtain the raw materials. Among them, the cutting sizes of the low-temperature surface ceramic fiber cloth, the ceramic fiber filling layer, and the reflective screen are determined according to the finished product size; for the high-temperature surface ceramic fiber cloth closest to the heating surface, a single-sided side length allowance is reserved. The single-sided side length allowance is related to the sewing thickness of the heat insulation blanket. According to the thickness, reserve the single-sided side length and sew the edges with the low-temperature surface ceramic fiber cloth. For the high-temperature alloy woven mesh and the high-temperature alloy foil, a single-sided side length allowance is reserved. The single-sided side length allowance is related to the sewing thickness of the heat insulation blanket. According to the thickness, reserve the single-sided side length, and the single-sided side length allowance is half of the side thickness, forming a semi-packaged structure with the side.

[0082] Step 2: Structure from the low-temperature surface to the high-temperature surface of the ceramic fiber layer: The low-temperature surface ceramic fiber cloth, the ceramic fiber filling layer, the reflective screen, the ceramic fiber filling layer, and the high-temperature surface ceramic fiber cloth are laid and processed to obtain the ceramic fiber layer.

[0083] Step 3: Sewing; Pass the ceramic fiber sewing thread through the ceramic fiber layer for sewing. When sewing at both ends, bend, stretch and tighten, tie a knot at the edge to finish, and remove the excess high-toughness ceramic fiber sewing thread to complete the sewing of the ceramic fiber layer.

[0084] Sewing method: The one-way sewing thread is sewn in a continuous "zigzag" shape, sewn from the upper and lower surfaces respectively. The penetration points of the sewing threads on both surfaces are the same, and the sewing thread directions are opposite; through this sewing method, a line that seems to form a continuous "grid" shape on the side when the two surfaces are combined is obtained.

[0085] Step 4: Cover a layer of high-temperature alloy woven mesh on the high-temperature surface ceramic fiber cloth. Adopt the same sewing method as in Step 3. The sewing row spacing of the ceramic fiber layer is 50 mm, and the stitch spacing is 10 mm. The sewing row spacing of the high-temperature alloy woven mesh is 50 mm, and the stitch spacing is 10 mm. Use high-temperature alloy sewing thread to sew and fix; when sewing with the high-temperature alloy sewing thread, it is sewn on the center line of the row spacing of the ceramic fiber layer. After the high-temperature alloy woven mesh and the ceramic fiber layer are sewn, the sewing threads on the inner and outer surfaces together form a "field" pattern, and the ceramic fiber layer and the high-temperature alloy woven mesh form the high-temperature alloy layer.

[0086] Step 5: Weld a layer of high-temperature alloy foil on the surface at the alternating connection points of the high-temperature alloy sewing thread by using brazing technology to complete the preparation of the surface-strengthened ultra-fine ceramic fiber flexible heat insulation blanket. The brazing material is in the form of paste or filament. The brazing process is to place the brazing material in the middle of the high-temperature woven mesh and apply appropriate contact pressure to the high-temperature alloy foil, and then place the entire component in a vacuum or inert gas brazing furnace. The brazing temperature is 65?C. The prepared surface-strengthened ultra-fine ceramic fiber flexible heat insulation blanket is as Figure 4 shown. Example 2

[0087] This embodiment provides a surface-toughened ultrafine ceramic fiber flexible thermal insulation blanket having the same structure as that of embodiment 1. Specifically, the high-temperature alloy foil is an Inconel 625 high-temperature alloy foil having a size of 240 mm×240 mm×0.5 mm.

[0088] The high-temperature alloy woven mesh is a 240mm×240mm×0.3mm, 100-mesh Inconel 625 high-temperature alloy woven mesh.

[0089] The high temperature surface ceramic fiber cloth has a size of 260mm×260mm×0.1mm and a surface density of 108g / m 2 Plain quartz fiber cloth.

[0090] The low-temperature surface ceramic fiber cloth has a size of 220mm×220mm×0.1mm and a surface density of 108g / m 2 Plain quartz fiber cloth.

[0091] The ceramic fiber filling layer consists of three layers of 220mm×220mm×4mm in size and a bulk density of 0.1g / cm 3 The quartz fiber needle-punched blanket and two layers of 220×220mm×15μm aluminum foil are alternately laminated.

[0092] Ceramic fiber sewing thread is 195tex quartz fiber sewing thread (treated with polytetrafluoroethylene emulsion coating).

[0093] The high-temperature alloy sewing thread is 316L stainless steel sewing thread with a diameter of 0.4 mm.

[0094] The preparation steps are the same as in Example 1. Example 3

[0095] This embodiment provides a surface-toughened ultrafine ceramic fiber flexible thermal insulation blanket having the same structure as that of embodiment 1. Specifically, the high-temperature alloy foil is an Inconel 625 high-temperature alloy foil having a size of 240 mm×240 mm×0.5 mm.

[0096] The high-temperature alloy woven mesh is a 240mm×240mm×0.3mm, 100-mesh Inconel 625 high-temperature alloy woven mesh.

[0097] The high temperature surface ceramic fiber cloth has a size of 260mm×260mm×0.1mm, a thickness of 0.1mm, and a surface density of 108g / m 2 Plain quartz fiber cloth.

[0098] The low-temperature surface ceramic fiber cloth is a plain quartz fiber cloth with a size of 220mm×220mm×0.1mm and a surface density of 108g / m 2 Plain quartz fiber cloth.

[0099] The ceramic fiber filling layer is obtained by alternating and laminating five layers of quartz fiber needle-punched blankets with a size of 220 mm × 220 mm × 2 mm and four layers of aluminum foil with a size of 220 mm × 220 mm × 15 μm.

[0100] Ceramic fiber sewing thread is 195tex quartz fiber sewing thread (treated with polytetrafluoroethylene emulsion coating).

[0101] The high-temperature alloy sewing thread is 316L stainless steel sewing thread with a diameter of 0.4 mm.

[0102] The preparation steps are the same as in Example 1. Example 4

[0103] This embodiment provides a surface-toughened ultrafine ceramic fiber flexible thermal insulation blanket having the same structure as that of embodiment 1. Specifically, the high-temperature alloy foil is an Inconel 625 high-temperature alloy foil having a size of 240 mm×240 mm×0.5 mm.

[0104] The high-temperature alloy woven mesh is a 240mm×240mm×0.3mm, 100-mesh Inconel 625 high-temperature alloy woven mesh.

[0105] The high temperature surface ceramic fiber cloth has a size of 260mm×260mm×0.1mm and a surface density of 108g / m 2 Plain quartz fiber cloth.

[0106] The low-temperature surface ceramic fiber cloth has a size of 220mm×220mm×0.1mm and a surface density of 108g / m 2 Plain quartz fiber cloth.

[0107] The ceramic fiber filling layer consists of nine layers of 220×220mm×2mm in size and a bulk density of 0.1g / cm 3 The quartz fiber needle-punched blanket and eight layers of 220×220mm×15μm aluminum foil are alternately stacked.

[0108] Ceramic fiber sewing thread is 195tex quartz fiber sewing thread (treated with polytetrafluoroethylene emulsion coating).

[0109] The high-temperature alloy sewing thread is 316L stainless steel sewing thread with a diameter of 0.4 mm.

[0110] The preparation steps are the same as in Example 1. Example 5

[0111] This embodiment provides a surface-toughened ultrafine ceramic fiber flexible thermal insulation blanket having the same structure as that of embodiment 1. Specifically, the high-temperature alloy foil is an Inconel 625 high-temperature alloy foil having a size of 240 mm×240 mm×0.5 mm.

[0112] The high-temperature alloy woven mesh is a 240mm×240mm×0.3mm, 100-mesh Inconel 625 high-temperature alloy woven mesh.

[0113] The high temperature surface ceramic fiber cloth has a size of 260mm×260mm×0.18mm and a surface density of 245g / m 2 Twill alumina fiber cloth.

[0114] The low-temperature surface ceramic fiber cloth has a size of 220mm×220mm×0.18mm and a surface density of 245g / m 2 Twill alumina fiber cloth.

[0115] The ceramic fiber filling layer consists of two layers of 220mm×220mm×5mm in size and a bulk density of 0.1g / cm 3 The alumina fiber needle-punched blanket and a layer of 240mm×240mm×15μm aluminum foil are alternately stacked.

[0116] Ceramic fiber sewing thread is 195tex quartz fiber sewing thread (treated with polytetrafluoroethylene emulsion coating).

[0117] The high-temperature alloy sewing thread is 316L stainless steel sewing thread with a diameter of 0.4 mm.

[0118] The preparation steps are the same as in Example 1. Example 6

[0119] This embodiment provides a surface-toughened ultrafine ceramic fiber flexible thermal insulation blanket having the same structure as that of embodiment 1. Specifically, the high-temperature alloy foil is an Inconel 625 high-temperature alloy foil having a size of 240 mm×240 mm×0.5 mm.

[0120] The high-temperature alloy woven mesh is a 240mm×240mm×0.3mm, 100-mesh Inconel 625 high-temperature alloy woven mesh.

[0121] The high temperature surface ceramic fiber cloth has a size of 260mm×260mm×0.18mm and a surface density of 245g / m 2 Twill alumina fiber cloth.

[0122] The low-temperature surface ceramic fiber cloth has a size of 220mm×220mm×0.18mm and a surface density of 245g / m 2 Twill alumina fiber cloth.

[0123] The ceramic fiber filling layer consists of five layers of 220mm×220mm×3mm in size and a bulk density of 0.1g / cm 3The alumina fiber needle-punched blanket and four layers of 240mm×240mm×15μm aluminum foil are alternately stacked.

[0124] Ceramic fiber sewing thread is 195tex quartz fiber sewing thread (treated with polytetrafluoroethylene emulsion coating).

[0125] The high-temperature alloy sewing thread is 316L stainless steel sewing thread with a diameter of 0.4 mm.

[0126] The preparation steps are the same as in Example 1.

[0127] Comparative Example 1

[0128] A ceramic fiber flexible thermal insulation blanket, the structure of which differs from that of Example 1 in that it does not contain high-temperature alloy foil and high-temperature alloy woven mesh.

[0129] Comparative Example 2

[0130] A ceramic fiber flexible thermal insulation blanket, the structure of which differs from that of Example 1 in that it does not contain a high-temperature alloy woven mesh.

[0131] Comparative Example 3

[0132] An AFRSI flexible thermal insulation blanket is sprayed with a C9 coating on its surface. The AFRSI flexible thermal insulation blanket is made of a quartz fiber fabric and a quartz fiber blanket sewn with Teflon-coated quartz wire. The C9 coating is a high-temperature ceramic coating with good adhesion and cohesion. The thermal insulation pad of Comparative Example 3 has a maximum temperature resistance of 650°C in a wind tunnel test (wind speed of 3 Mach, maximum temperature of 1200°C). When the temperature exceeds 800°C, the C9 coating breaks and falls off, and the surface fiber cloth of the AFRSI flexible thermal insulation blanket becomes fuzzy. The ceramic fiber flexible thermal insulation blanket prepared in Example 4 uses Inconel high-temperature alloy woven mesh and Inconel high-temperature alloy foil, which can withstand a temperature of 1000°C for a long time and 1100°C for a short time, and keeps the top surface from bending. The thermal conductivity of the flexible thermal insulation blanket prepared in Example 4 and the AFRSI flexible thermal insulation blanket with a C9 coating sprayed on the surface of Comparative Example 3 is as follows: Figure 3 shown.

[0133] The bulk density and room temperature thermal conductivity of the above-mentioned embodiments and comparative examples were tested, and the mass loss rate was measured and calculated after single-side heating at 1300° C. for 60 seconds. The results are shown in the following table.

[0134]

[0135] The wind tunnel test (wind speed Mach 3, temperature 1000° C.) and thermal conductivity at different temperatures of Example 4 and Comparative Example 3 were tested, and the results are shown in the following table.

[0136]

[0137] As can be seen from the above table, the mass loss rate of the ceramic fiber flexible insulation blanket of the embodiment of the present invention is less than 3.95%, and the surface is flat and complete after high-temperature heating and wind tunnel testing, without burn-through, breakage and damage. The operating temperature of the material is above 1300°C; the material is light in weight and has a bulk density of <195kg / m 3 The invention has good heat insulation effect, low thermal conductivity at different temperatures, and thermal conductivity at room temperature is less than 0.0385W / (m·K). The preparation method of the invention is simple and easy.

[0138] Comparative Example 4

[0139] This comparative example is a certain type of launch vehicle fairing thermal insulation skirt ( Figure 5 ), made of aramid 1313 fiber cloth, aramid / polyester blended needle-punched blanket core material and aramid fiber sewing thread, with a density of 0.40g / cm 3 , the thermal conductivity at room temperature is 0.045W / (m·K).

[0140] Comparative Example 5

[0141] This comparative example is a thermal insulation cover for high temperature equipment in a space station in my country ( Figure 6 ), the internal insulation cotton core is made of quartz fiber cotton, the surface is made of PBO plain cloth, the sewing thread is made of PBO material, and the room temperature thermal conductivity coefficient is 0.038W / (m·K).

[0142] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A surface toughened ceramic fiber flexible thermal insulation structure, characterized in that: It includes a high-temperature alloy foil, a high-temperature alloy woven mesh and a ceramic fiber layer stacked in sequence from the high-temperature side to the low-temperature side; the ceramic fiber layer includes a high-temperature side ceramic fiber cloth, several layers of ceramic fiber filling layers and a low-temperature side ceramic fiber cloth stacked in sequence, and a reflective screen is provided between two adjacent layers of the ceramic fiber filling layers; the ceramic fiber layer is fixed by ceramic fiber sewing thread, and the high-temperature alloy woven mesh and the ceramic fiber layer are fixed by high-temperature alloy sewing thread; a layer of high-temperature alloy foil is welded on the surface of the high-temperature alloy woven mesh; the material of the high-temperature alloy woven mesh is nickel-based high-temperature alloy; the high-temperature alloy sewing thread is nickel-based high-temperature alloy wire or iron-based high-temperature alloy wire; the high-temperature alloy foil is nickel-based high-temperature alloy foil.

2. The surface-strengthened ceramic fiber flexible thermal insulation structure according to claim 1, characterized in that: The high-temperature surface ceramic fiber cloth wraps the low-temperature surface ceramic fiber cloth; The high-temperature alloy braided mesh seals the edge of the high-temperature surface ceramic fiber cloth.

3. The surface-toughened ceramic fiber flexible thermal insulation structure according to claim 1, characterized in that: The density of the surface toughened ceramic fiber flexible insulation structure is 150-300 kg / m 3 .

4. The surface-strengthened ceramic fiber flexible thermal insulation structure according to claim 1, characterized in that: In the ceramic fiber layer, the ceramic fiber filling layer is ceramic fiber cotton or ceramic fiber blanket; the reflective screen is aluminum foil or polyimide aluminum-plated film; The number of ceramic fiber filling layers is 2-11; The number of layers of the reflective screen is 1-10; The number of layers of the reflective screen is one layer less than the number of layers of the ceramic fiber filling layer.

5. The surface-strengthened ceramic fiber flexible thermal insulation structure according to claim 1, characterized in that: The ceramic fiber filling layer is selected from one or more of quartz fiber wool, quartz fiber needle-punched blanket, alumina fiber wool and alumina fiber needle-punched blanket.

6. The surface-toughened ceramic fiber flexible thermal insulation structure according to claim 5, characterized in that: The thickness of the quartz fiber needle-punched blanket is 5-20 mm, and the bulk density is 0.05-0.2 g / cm 3 The thickness of the alumina fiber needle-punched blanket is 5-25 mm, and the bulk density is 0.05-0.2 g / cm 3 .

7. The surface-toughened ceramic fiber flexible thermal insulation structure according to any one of claims 1 to 6, characterized in that: The ceramic fiber sewing thread is alumina fiber yarn or quartz fiber yarn.

8. The surface-strengthened ceramic fiber flexible thermal insulation structure according to claim 7, characterized in that: The ceramic fiber sewing thread is subjected to coating treatment, wherein the coating treatment comprises impregnating the surface of the twisted ceramic fiber sewing thread with polytetrafluoroethylene emulsion; The size of the ceramic fiber sewing thread is 90-300tex.

9. The surface-toughened ceramic fiber flexible thermal insulation structure according to any one of claims 1 to 6, characterized in that: The high-temperature surface ceramic fiber cloth is quartz fiber cloth or alumina fiber cloth, and the low-temperature surface ceramic fiber cloth is quartz fiber cloth or alumina fiber cloth; The silica content of the quartz fiber cloth is 90%-99.9%, and the alumina content of the alumina fiber cloth is 70%-99.9%; The thickness of the ceramic fiber cloth on the high temperature surface is 0.1-1.0 mm, and the thickness of the ceramic fiber cloth on the low temperature surface is 0.1-1.0 mm; The high-temperature surface ceramic fiber cloth is plain, twill or satin, and the low-temperature surface ceramic fiber cloth is plain, twill or satin; The surface density of the high temperature surface ceramic fiber cloth is 100-275g / m 2 The surface density of the low-temperature ceramic fiber cloth is 100-275g / m 2 .

10. The surface-toughened ceramic fiber flexible thermal insulation structure according to any one of claims 1 to 6, characterized in that: The high-temperature alloy braided mesh is woven from one or more wires selected from Inconel-600, Inconel-601, Inconel-617 and Inconel-625, and the mesh size of the high-temperature alloy braided mesh is 50-500 meshes.

11. The surface-toughened ceramic fiber flexible thermal insulation structure according to any one of claims 1 to 6, characterized in that: The material of the nickel-based high-temperature alloy wire is at least one of GH3030, GH3600, GH3602, GH3625, GH4049, GH4033 and GH4043; the iron-based high-temperature alloy wire is 316L stainless steel sewing wire; the diameter of the high-temperature alloy sewing wire is 0.25-1mm.

12. The surface-toughened ceramic fiber flexible thermal insulation structure according to any one of claims 1 to 6, characterized in that: The material of the high-temperature alloy foil is Inconel-600, Inconel-601, Inconel-617 or Inconel-625, and the thickness of the high-temperature alloy foil is 0.2-2 mm.

13. The method for preparing a surface-toughened ceramic fiber flexible thermal insulation structure according to any one of claims 1 to 12, characterized in that: The following steps are involved: 1) Laying a high-temperature surface ceramic fiber cloth, a ceramic fiber filling layer, a reflective screen, and a low-temperature surface ceramic fiber cloth to obtain a ceramic fiber layer; wrapping the low-temperature surface ceramic fiber cloth with the high-temperature surface ceramic fiber cloth and sewing and securing the low-temperature surface ceramic fiber cloth with ceramic fiber sewing thread; 2) Covering the high-temperature surface ceramic fiber cloth with a layer of high-temperature alloy woven mesh; using the high-temperature alloy woven mesh to semi-enclose the side edges of the high-temperature surface ceramic fiber cloth and sewing and fixing them with high-temperature alloy sewing thread; 3) A layer of high-temperature alloy foil is brazed on the surface of the high-temperature alloy woven mesh.

14. The method for preparing a surface-toughened ceramic fiber flexible thermal insulation structure according to claim 13, characterized in that: The single side of the high temperature surface ceramic fiber cloth The reserved side length margin is 20-100 mm, and the single-side reserved side length margin of the high-temperature surface ceramic fiber cloth is used to hem the low-temperature surface ceramic fiber cloth; the single-side reserved side length margin of the high-temperature alloy woven mesh is 10-40 mm, and the single-side reserved side length margin of the high-temperature alloy woven mesh is used to semi-enclose the side edge of the high-temperature surface ceramic fiber cloth; the high-temperature alloy sewing thread and the ceramic fiber sewing thread are alternately sewn to form a field pattern.

15. The method for preparing a surface-toughened ceramic fiber flexible thermal insulation structure according to claim 14, characterized in that: In step 1) and step 2), the suturing is done in a mesh-shaped manner.

16. The method for preparing a surface-toughened ceramic fiber flexible thermal insulation structure according to claim 15, characterized in that: The stitching line spacing of the ceramic fiber layer is 20-100mm, and the needle spacing is 5-30mm. The stitching line spacing of the high-temperature alloy woven mesh is 20-100mm, and the needle spacing is 5-30mm. The sewing thread of the ceramic fiber layer and the sewing thread of the high-temperature alloy woven mesh are stitched alternately; the ceramic fiber sewing thread and the high-temperature alloy sewing thread form a field pattern.

17. The method for preparing a surface-toughened ceramic fiber flexible thermal insulation structure according to claim 13, characterized in that: In step 3), the brazing comprises placing the brazing material in the middle of the high-temperature braided mesh and applying appropriate contact pressure, and heating to 500-1260° C. in a vacuum or inert atmosphere for brazing.

18. The method for preparing a surface-toughened ceramic fiber flexible thermal insulation structure according to claim 17, characterized in that: The brazing is performed at the alternating connection points of the high-temperature alloy sewing thread; and the brazing material is a paste or wire material.

19. Use of the surface-reinforced ceramic fiber flexible thermal insulation structure according to any one of claims 1 to 12 or the surface-reinforced ceramic fiber flexible thermal insulation structure obtained by the preparation method according to any one of claims 13 to 18 in a hypersonic aircraft thermal protection system.

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