Ablation-resistant multi-element gradient heat prevention and insulation integrated composite material and preparation method thereof

Abstract

The invention relates to an ablation-resistant multi-element gradient heat prevention and insulation integrated composite material and a preparation method thereof, and belongs to the field of heat prevention and insulation composite materials. The composite material comprises a gradient density heat-proof layer and a light heat-insulating layer, wherein the gradient density heat-proof layer is arranged above the light heat-insulating layer; the raw materials of the gradient density heat-proof layer are fiber woven bodies and ceramic resin, and the raw material of the light heat insulation layer is fibrofelt; the gradient density heat protection layer and the light heat insulation layer are filled with aerogel. The ablation-resistant multi-element gradient heat prevention and insulation integrated composite material provided by the embodiment of the invention meets the conditions that the thickness is 20-80 mm, the density is smaller than or equal to 0.8 g / cm < 3 >, and the density and back temperature meeting the requirements can be obtained by adjusting the thickness of the composite material.

Description

Technical Field

[0001] The present application relates to the field of heat-insulating composite materials, and in particular to an ablation-resistant multi-element gradient heat-insulating integrated composite material and a preparation method thereof. Background Art

[0002] With the rapid development of the aerospace industry, thermal protection materials (TPMs) for aircraft surfaces require higher ablation resistance and relatively lower density. Aerogels, with their ultra-low thermal conductivity, are widely used as thermal insulation materials. However, in aircraft surface thermal protection, severe surface ablation and regression often occur due to the extremely high aerodynamic heating environment on the surface. Currently, the use of gradient structures with a dense surface and a porous interior is one of the best options for balancing thermal protection, insulation, and density in thermal protection materials.

[0003] Traditional fiber-braided reinforced resin-based composites offer excellent thermal insulation, dimensional stability, and lightweight properties, making them suitable for large thermal protection areas on aircraft surfaces. However, in the harsh thermodynamic coupling environment of high-speed, long-endurance aircraft, relying solely on fiber reinforcement is insufficient to address the problems of surface unevenness caused by ablation, reduced overall mechanical properties, and high mass loss, all of which impact the aircraft's accuracy and safety during flight. Summary of the Invention

[0004] The present application provides an ablation-resistant multi-element gradient heat-insulating integrated composite material and a preparation method thereof to solve the following technical problem: how to balance the lightness and ablation resistance of fiber-reinforced resin-based composite materials.

[0005] In a first aspect, an embodiment of the present application provides an ablation-resistant multi-element gradient heat-insulating integrated composite material, the composite material comprising a gradient density heat-insulating layer and a lightweight heat-insulating layer, the gradient density heat-insulating layer being disposed above the lightweight heat-insulating layer;

[0006] The raw materials of the gradient density heat protection layer are fiber braid and ceramic resin, and the raw materials of the lightweight heat insulation layer are fiber felt;

[0007] The gradient density heat protection layer and the lightweight heat insulation layer are both filled with aerogel.

[0008] Optionally, the gradient density heat protection layer includes a low-density heat protection layer, a medium-density heat protection layer and a high-density heat protection layer arranged in sequence from bottom to top; wherein,

[0009] The density of the high-density heat-proof layer is 1.2g / cm 3 ~1.4g / cm 3 The density of the medium-density heat-proof layer is 1.0g / cm 3 ~1.2g / cm 3The density of the low-density heat-proof layer is 0.8g / cm 3 ~1.0g / cm 3 .

[0010] Optionally, the aerogel includes at least one of the following: phenolic aerogel, silica aerogel, and alumina aerogel.

[0011] Optionally, the ceramic resin includes phenolic resin, ceramic filler and solvent, and the mass ratio of the phenolic resin, the ceramic filler and the solvent is (1-10):(1-10):(1-10).

[0012] Optionally, the ceramic filler includes at least one of the following: boride, carbide, oxide; and / or,

[0013] The particle size of the ceramic filler is 0.3 μm to 3 μm.

[0014] Optionally, the solvent includes an alcohol solvent.

[0015] Optionally, the thickness of a single layer of the gradient density heat protection layer is 0.5 mm to 10 mm; and / or,

[0016] The thickness of the composite material is 20 mm to 80 mm.

[0017] Optionally, the density of the lightweight insulation layer is 0.3 g / cm 3 ~0.6g / cm 3 and / or,

[0018] The density of the composite material is ≤0.8g / cm 3 .

[0019] In a second aspect, an embodiment of the present application provides a method for preparing the ablation-resistant multi-element gradient heat-insulating integrated composite material according to any one of the first aspects, the method comprising:

[0020] Mixing phenolic resin, solvent and ceramic filler, and adjusting the content of the solvent to obtain a gradient concentration ceramic resin solution;

[0021] impregnating a plurality of fiber braids with the gradient-concentration ceramic resin solution and drying the solution to obtain a gradient-density heat-resistant layer;

[0022] The gradient density heat-proof layer and the fiber felt are stacked and stitched together for curing to obtain a first heat-proof integrated composite material;

[0023] impregnating the first thermal insulation integrated composite material with an aerogel precursor to obtain a second thermal insulation integrated composite material filled with the aerogel precursor;

[0024] The second thermal insulation integrated composite material filled with aerogel precursor is subjected to sol-gel and drying in sequence to obtain an ablation-resistant multi-element gradient thermal insulation integrated composite material.

[0025] Optionally, the curing process parameters include: temperature of 120° C. to 180° C., and time of 1 hour to 10 hours.

[0026] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0027] The ablation-resistant multi-element gradient heat-insulating integrated composite material provided in the embodiment of the present application comprises a gradient-densified heat-proof layer and a lightweight heat-insulating layer, wherein the gradient-densified heat-proof layer is arranged above the lightweight heat-insulating layer; the raw materials of the gradient-densified heat-proof layer are fiber braid and ceramic resin, and the raw materials of the lightweight heat-insulating layer are fiber felt; the interiors of the gradient-densified heat-proof layer and the lightweight heat-insulating layer are both filled with aerogel. The composite material consists of a gradient-densified heat-proof layer and a lightweight heat-insulating layer, and the gradient-densified heat-proof layer is located above the lightweight heat-insulating layer, so that this upper and lower layered structural design constitutes the basic framework for realizing the heat-insulating function; the gradient-densified heat-proof layer uses fiber braid and ceramic resin as raw materials, the fiber braid provides certain structural strength and toughness, and the ceramic resin may give the heat-proof layer good high-temperature resistance and ablation resistance due to its ceramic component, and can function in a high heat flow environment; the lightweight heat-insulating layer uses fiber felt as raw material, which realizes the heat-insulating function while ensuring the lightweight characteristics of the material; both layers are filled with aerogel, Aerogel has extremely low thermal conductivity and density, which may further enhance the thermal protection performance in a gradient density thermal protection layer, and help reduce the overall mass and improve the thermal insulation performance in a lightweight thermal insulation layer; the high-density thermal protection layer with ceramics can significantly reduce ablation retreat in a high heat flux environment, which is crucial for materials used in high-temperature environments (such as spacecraft re-entry into the atmosphere) to ensure the integrity and service life of the material; the lightweight aerogel structure of the inner layer greatly reduces the overall mass of the material and reduces the weight burden, while achieving excellent thermal insulation performance, which can effectively block heat transfer and protect internal structures or equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0029] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0030] Figure 1 Schematic diagram of the structure of an ablation-resistant multi-element gradient heat-insulating integrated composite material provided in an embodiment of the present application; wherein 1 is a gradient density heat-insulating layer, 11 is a high-density heat-insulating layer, 12 is a medium-density heat-insulating layer, 13 is a low-density heat-insulating layer, and 2 is a lightweight heat-insulating layer;

[0031] Figure 2 A schematic flow chart of a method for preparing an ablation-resistant multi-element gradient heat-insulating integrated composite material provided in an embodiment of the present application;

[0032] Figure 3 A simplified practical flow chart of a method for preparing an ablation-resistant multi-element gradient heat-insulating integrated composite material provided in an embodiment of the present application. DETAILED DESCRIPTION

[0033] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0034] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a hard limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numbers within the range. For example, the description of a range from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0035] In this application, unless otherwise specified, the directional words used, such as "upper" and "lower", refer specifically to the directions of the drawings in the accompanying drawings. In addition, in the description of the present application specification, the terms "including", "comprising", etc. mean "including but not limited to". In this article, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. Wherein A and B can be singular or plural. In this article, "at least one" refers to one or more, and "plurality" refers to two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple. In the proportional relationships involved in this article, the parameters that need to be described by proportion should be understood as the first term of the proportional formula in the order of description, and the proportional numbers should be understood as the second term of the proportional formula. For example, if the mass ratio of substance A, substance B, and substance C is 1:2:3, then substance A, substance B, and substance C should correspond one-to-one to the proportional numbers in the proportional formula in the order of description, that is, the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0036] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0037] In the first aspect, the embodiments of the present application provide an ablation-resistant multi-element gradient heat-insulating integrated composite material. Figure 1 This is a schematic diagram of the structure of an ablation-resistant multi-element gradient heat-insulating integrated composite material provided in an embodiment of the present application; see Figure 1 , the composite material includes a gradient density heat protection layer and a lightweight heat insulation layer, the gradient density heat protection layer is arranged above the lightweight heat insulation layer;

[0038] The raw materials of the gradient density heat protection layer are fiber braid and ceramic resin, and the raw materials of the lightweight heat insulation layer are fiber felt;

[0039] The gradient density heat protection layer and the lightweight heat insulation layer are both filled with aerogel.

[0040] The composite material consists of a gradient density heat protection layer and a lightweight heat insulation layer. The gradient density heat protection layer is located above the lightweight heat insulation layer, so that this upper and lower layered structural design constitutes the basic framework for realizing the heat insulation function. The gradient density heat protection layer uses fiber braids and ceramic resins as raw materials. The fiber braids provide certain structural strength and toughness. The ceramic resin may give the heat protection layer good high temperature resistance and ablation resistance due to its ceramic components, and can play a role in high heat flow environments. The lightweight heat insulation layer uses fiber felt as raw material, which realizes the heat insulation function while ensuring the lightweight characteristics of the material. Both layers are filled with aerogel. Aerogel has extremely low thermal conductivity and density, which may further enhance the thermal protection performance in a gradient density thermal protection layer, and help reduce the overall mass and improve the thermal insulation performance in a lightweight thermal insulation layer; the high-density thermal protection layer with ceramics can significantly reduce ablation retreat in a high heat flux environment, which is crucial for materials used in high-temperature environments (such as spacecraft re-entry into the atmosphere) to ensure the integrity and service life of the material; the lightweight aerogel structure of the inner layer greatly reduces the overall mass of the material and reduces the weight burden, while achieving excellent thermal insulation performance, which can effectively block heat transfer and protect internal structures or equipment.

[0041] In some embodiments, the gradient density heat protection layer includes a low-density heat protection layer, a medium-density heat protection layer, and a high-density heat protection layer arranged in sequence from bottom to top; wherein,

[0042] The density of the high-density heat-proof layer is 1.2g / cm 3 ~1.4g / cm 3 The density of the medium-density heat-proof layer is 1.0g / cm 3 ~1.2g / cm 3 The density of the low-density heat-proof layer is 0.8g / cm 3 ~1.0g / cm 3 .

[0043] The gradient density heat protection layer adopts a layered design from low density to medium density and then to high density from bottom to top. This design conforms to the logic of heat transfer and material performance requirements. When heat is transmitted from the outside, the high-density heat protection layer is in the outermost layer, which can first withstand the impact of high heat flow, and use its higher density and corresponding material properties (such as ceramic resin and other ingredients) to effectively resist ablation. The medium-density heat protection layer acts as a transition buffer, further blocking heat transfer to a certain extent, sharing part of the heat load, and reducing the pressure on the high-density heat protection layer. The low-density heat protection layer is close to the lightweight insulation layer, which can continue to block heat, while ensuring a certain heat protection performance, minimizing its own weight, reducing the impact on the weight of the entire composite material, and achieving a balance between heat protection and lightness.

[0044] The density of the high-density heat-proof layer can be 1.2g / cm 3~1.4g / cm 3 This density range makes it have relatively high density and strength, can remain stable in high heat flow environment, effectively resist ablation and erosion, and protect the internal structure. The density of the medium density heat protection layer can be 1.0g / cm 3 ~1.2g / cm 3 , between high density and low density, can play a connecting role in heat protection performance without excessively increasing the weight of the material. Through reasonable density design, it achieves a balance between performance and weight. The density of the low-density heat protection layer can be 0.8g / cm 3 ~1.0g / cm 3 The lower density makes it lighter and provides a certain degree of heat protection, which works better with the lightweight insulation layer to reduce the overall weight of the composite material and further prevent heat from being transferred to the inside. For example, the density of the high-density heat protection layer can be 1.2g / cm 3 , 1.3g / cm 3 、14g / cm 3 etc.; the density of the medium-density heat-proof layer can be 1.0g / cm 3 , 1.1g / cm 3 , 1.2g / cm 3 etc.; the density of the low-density heat-proof layer can be 0.8g / cm 3 , 0.9g / cm 3 , 1.0g / cm 3 wait.

[0045] In some embodiments, the aerogel comprises at least one of the following: phenolic aerogel, silica aerogel, and alumina aerogel.

[0046] Aerogels include combinations of one or more of phenolic aerogel, silica aerogel, and alumina aerogel. Phenolic aerogel can have high heat resistance and good mechanical strength. Silica aerogel is an excellent thermal insulation material with extremely low thermal conductivity, even lower than that of still air. Alumina aerogel has high high-temperature resistance and can withstand very high temperatures without significant performance degradation. Whether phenolic aerogel, silica aerogel, or alumina aerogel, when filled into gradient-density thermal protection layers and lightweight insulation layers, they can significantly reduce the overall thermal conductivity of the composite material and improve its thermal insulation performance. The porous structure of aerogels can effectively block heat transfer paths, reducing heat conduction and convection. Their low density also helps reduce the weight of composite materials, meeting the demand for lightweight materials in practical applications. For example, in the aerospace field, reducing material weight can improve aircraft performance and efficiency. Different types of aerogels can be selected or combined according to specific application requirements.

[0047] In some embodiments, the ceramic resin includes a phenolic resin, a ceramic filler, and a solvent, and the mass ratio of the phenolic resin, the ceramic filler, and the solvent is (1-10):(1-10):(1-10).

[0048] Phenolic resins have high heat resistance, mechanical strength, and adhesion. Ceramic fillers are characterized by high temperature resistance, high hardness, and good chemical stability. Adding them to phenolic resins can enhance the resin's high-temperature resistance, wear resistance, and ablation resistance. Different types of ceramic fillers (such as aluminum oxide and silicon carbide) impart different performance characteristics to the ceramic resin, and the choice can be based on specific application requirements. The solvent's primary function is to dissolve the phenolic resin and adjust the ceramic resin's viscosity, making it easier to process and form. The mass ratio of phenolic resin, ceramic filler, and solvent can be (1-10):(1-10):(1-10). By adjusting the mass ratio of these three components, ceramic resins with different properties can be prepared to meet different application requirements. For example, in applications requiring high heat resistance and ablation resistance, the proportion of ceramic filler can be appropriately increased. For applications requiring high processing quality and better fluidity, the proportion of solvent can be adjusted. An appropriate mass ratio of phenolic resin, ceramic filler, and solvent allows the ceramic resin to form a stable structure at high temperatures, effectively blocking heat transfer and reducing the material's ablation recession rate. For example, the mass ratio of the phenolic resin, the ceramic filler, and the solvent may be 1:1:1, 2:3:2, 5:7:7, 8:5:8, 10:7:9, etc.

[0049] In some embodiments, the ceramic filler comprises at least one of: a boride, a carbide, an oxide; and / or,

[0050] The particle size of the ceramic filler is 0.3 μm to 3 μm.

[0051] Ceramic fillers can be a combination of one or more borides, carbides, and oxides. Boride ceramic fillers have the characteristics of high hardness, high melting point, and good chemical stability. For example, zirconium boride (ZrB2) has a melting point of up to 3246°C and can maintain good strength and oxidation resistance at high temperatures. Carbide ceramic fillers (such as silicon carbide SiC, boron carbide B4C, etc.) have extremely high hardness and strong wear resistance, and also have good high temperature resistance. Oxides (such as aluminum oxide Al2O3, zirconium oxide ZrO2, etc.) have good chemical stability, insulation and high temperature resistance. The particle size of the ceramic filler can be 0.3μm to 3μm. The appropriate type and particle size combination of ceramic fillers can achieve the best balance between the anti-ablation performance, mechanical strength and thermal insulation performance of the gradient density heat protection layer. For example, in a high-density heat shield, it may be necessary to add high-melting-point, high-hardness boride and carbide fillers, while controlling the particle size within an appropriate range, to improve their ablation resistance in high-heat-flux environments. In a low-density heat shield, the type and particle size of the ceramic filler can be appropriately adjusted to reduce the material density while maintaining a certain level of heat shielding performance. For example, the particle size of the ceramic filler can be 0.3 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, etc.

[0052] In some embodiments, the solvent comprises an alcohol solvent.

[0053] The solvent can be an alcohol. Alcohols generally have good compatibility with phenolic resins and ceramic fillers. They do not chemically react with the phenolic resin, thereby damaging the resin's structure and properties. Furthermore, they can also help disperse the ceramic filler in the resin to a certain extent. Examples of alcoholic solvents include ethanol and ethylene glycol.

[0054] In some embodiments, the thickness of a single layer of the gradient density heat protection layer is 0.5 mm to 10 mm; and / or,

[0055] The thickness of the composite material is 20 mm to 80 mm.

[0056] The thickness of a single layer of a gradient-density thermal barrier can range from 0.5mm to 10mm, ensuring a smoother transition in density and performance between layers while also providing sufficient strength and ablation resistance. The appropriate single-layer thickness allows for good synergy between the different density layers, effectively blocking heat transfer and improving ablation resistance. Composite materials can range in thickness from 20mm to 80mm, and their thickness is closely related to their thermal insulation and heat protection properties. Generally speaking, increased thickness lengthens the heat transfer path, thereby improving insulation. Thicker composite materials also provide more material to resist ablation, extending their service life. However, increased thickness also increases weight, necessitating a trade-off between insulation, heat protection, and weight. In practical applications, the thickness of the composite material should be appropriately selected based on specific usage conditions and performance requirements to achieve the optimal performance balance. For example, the thickness of a single layer of the gradient density heat protection layer can be 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, etc.; the thickness of the composite material can be 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, etc.

[0057] In some embodiments, the density of the lightweight insulation layer is 0.3 g / cm 3 ~0.6g / cm 3 and / or,

[0058] The density of the composite material is ≤0.8g / cm 3 .

[0059] In a second aspect, the embodiments of the present application provide a method for preparing the ablation-resistant multi-element gradient heat-insulating integrated composite material according to any one of the first aspects. Figure 2 This is a flow chart of a method for preparing an ablation-resistant multi-element gradient heat-insulating integrated composite material provided in an embodiment of the present application; see Figure 2 , the method comprising:

[0060] S1, mixing phenolic resin, solvent and ceramic filler, and adjusting the content of the solvent to obtain a gradient concentration ceramic resin solution;

[0061] Mixing phenolic resin, solvent, and ceramic filler is a basic step in preparing ceramic resin solution. Phenolic resin, as a matrix material, provides adhesion and a certain degree of heat resistance; ceramic filler enhances the material's high temperature resistance, ablation resistance, and other properties; the solvent is used to dissolve the phenolic resin and adjust the viscosity of the solution. By adjusting the solvent content, a gradient concentration ceramic resin solution is obtained, which lays the foundation for the subsequent formation of a gradient density heat protection layer. When ceramic resin solutions of different concentrations are impregnated into the fiber braid, different amounts of resin will be attached to the fibers, thereby achieving a gradient change in density.

[0062] S2, impregnating a plurality of fiber braids with the gradient-concentration ceramic resin solution and drying the solution to obtain a gradient-density heat-resistant layer;

[0063] Using a gradient concentration ceramic resin solution to impregnate multiple fiber braids is to evenly attach the ceramic resin to the fiber braid to form a gradient density heat protection layer. The drying process removes the solvent, allowing the phenolic resin to solidify and tightly bond to the fiber braid.

[0064] S3, stacking and stitching the gradient density heat-proof layer and the fiber felt to perform curing to obtain a first heat-proof integrated composite material;

[0065] The gradient-density thermal barrier layer and fiber mat are stacked and stitched together to create the composite's basic structure and securely connect the layers. This stitching strengthens the interlayer bond and prevents delamination during use. The curing process fully solidifies the phenolic resin, creating a composite material with the desired strength and performance.

[0066] In some embodiments, the curing process parameters include: a temperature of 120° C. to 180° C., and a time of 1 hour to 10 hours.

[0067] The curing process parameters include a temperature of 120°C to 180°C and a curing time of 1 to 10 hours to ensure complete curing of the resin and ensure the mechanical properties and heat resistance of the composite material. For example, the temperature can be 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, etc., and the curing time can be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, etc.

[0068] S4, impregnating the first thermal insulation integrated composite material with an aerogel precursor to obtain a second thermal insulation integrated composite material filled with the aerogel precursor;

[0069] The purpose of impregnating the first thermal insulation integrated composite material with an aerogel precursor is to allow the aerogel precursor to fill the internal pores of the composite material, preparing for the subsequent formation of the aerogel structure. The impregnation process must ensure that the aerogel precursor can fully penetrate all parts of the composite material, especially the internal pores of the fiber braid.

[0070] S5. Performing sol-gel and drying in sequence on the second thermal insulation integrated composite material filled with aerogel precursor to obtain an ablation-resistant multi-element gradient thermal insulation integrated composite material.

[0071] Sol-gel and drying principles: A composite material filled with an aerogel precursor undergoes a series of sol-gel and drying processes to transform the aerogel precursor into an aerogel. During the sol-gel process, the precursor undergoes a chemical reaction to form a gel network structure, while the drying process removes the solvent from the gel, forming an aerogel with a porous structure. Drying can also include a solvent replacement step to remove the solvent from the gel and introduce a solvent more suitable for the subsequent drying process.

[0072] The preparation method of the ablation-resistant multi-element gradient anti-thermal insulation integrated composite material is realized based on the above-mentioned ablation-resistant multi-element gradient anti-thermal insulation integrated composite material. The specific structure of the ablation-resistant multi-element gradient anti-thermal insulation integrated composite material can refer to the above-mentioned embodiment. Since the preparation method of the ablation-resistant multi-element gradient anti-thermal insulation integrated composite material adopts part or all of the technical solutions of the above-mentioned embodiment, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiment, which will not be repeated here one by one.

[0073] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are usually measured in accordance with national standards. If there are no corresponding national standards, then the methods are carried out in accordance with general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0074] Example 1

[0075] A multi-element gradient heat-insulating integrated composite material resistant to ablation, comprising a gradient-density heat-proof layer and a lightweight heat-insulating layer, wherein the gradient-density heat-proof layer is arranged above the lightweight heat-insulating layer; the raw materials of the gradient-density heat-proof layer are quartz fiber braid and ceramic resin, and the raw material of the lightweight heat-insulating layer is quartz fiber braid; the interiors of the gradient-density heat-proof layer and the lightweight heat-insulating layer are both filled with aerogel.

[0076] The gradient density heat protection layer includes a low-density heat protection layer, a medium-density heat protection layer and a high-density heat protection layer arranged in sequence from bottom to top; wherein the density of the high-density heat protection layer is 1.35g / cm 3The density of the medium-density heat-proof layer is 1.09g / cm 3 The density of the low-density heat-proof layer is 0.84g / cm 3 The thickness of the lightweight insulation layer is 27 mm, and the thicknesses of the low-density thermal protection layer, the medium-density thermal protection layer and the high-density thermal protection layer are 1 mm respectively; the aerogel is phenolic aerogel; the ceramic resin includes phenolic resin, ethanol, zirconium boride and silicon carbide; the mass ratios of phenolic resin, ethanol, zirconium boride and silicon carbide are 5:1:2.5:2.5 (1#), 5:5:2.5:2.5 (2#) and 5:7.5:2.5:2.5 (3#) for high, medium and low, respectively; the particle size of the ceramic filler is 1 μm.

[0077] A method for preparing an ablation-resistant multi-element gradient heat-insulating integrated composite material, Figure 3 This is a simplified practical process diagram of a method for preparing an ablation-resistant multi-element gradient heat-insulating integrated composite material provided in an embodiment of the present application; see Figure 3 , specifically including:

[0078] Preparation of gradient heat shield: Phenolic resin, ethanol, zirconium boride, and silicon carbide were mixed in a mass ratio of 5:1:2.5:2.5 (1#), 5:5:2.5:2.5 (2#), and 5:7.5:2.5:2.5 (3#) respectively, and stirred evenly to obtain a ceramic resin solution. A 1mm thick quartz fiber braid was completely impregnated with the ceramic resin solution using the RTM process and dried to obtain a heat shield. The heat shield obtained by impregnation with the 1# solution was a high-density heat shield with a density of 1.35g / cm 3 The medium-density heat-resistant layer obtained by impregnation with 2# solution has a density of 1.09g / cm 3 The low-density heat-resistant layer obtained by impregnation with 3# solution has a density of 0.84g / cm 3 The high, medium and low density heat-proof layers and 27 mm thick quartz fiber felt were stacked and sewn in sequence in the thickness direction and cured at 150 ° C for 5 h to obtain a 30 mm thick gradient heat-proof layer.

[0079] Preparation of lightweight thermal insulation layer: Prepare phenolic aerogel precursor solution, use RTM process to fully impregnate the gradient thermal insulation layer with phenolic aerogel precursor solution, then carry out sol-gel process, solvent replacement and drying in sequence to prepare ablation-resistant multi-element gradient thermal insulation integrated composite material. The density of the thermal insulation layer is 0.33g / cm 3 The density of the ablation-resistant multi-element gradient heat-insulating integrated composite material is 0.41g / cm 3 Under the test conditions of oxyacetylene heat flux of 1.5MW / m2-500s, the surface retreat is 0.92mm and the back temperature is 306℃.

[0080] Example 2

[0081] An ablation-resistant multi-element gradient heat-insulating integrated composite material, comprising a gradient-density heat-proof layer and a lightweight heat-insulating layer, wherein the gradient-density heat-proof layer is arranged above the lightweight heat-insulating layer; the raw materials of the gradient-density heat-proof layer are quartz fiber braid and ceramic resin, and the raw material of the lightweight heat-insulating layer is quartz fiber felt; the interiors of the gradient-density heat-proof layer and the lightweight heat-insulating layer are both filled with aerogel.

[0082] The gradient density heat protection layer includes a low-density heat protection layer, a medium-density heat protection layer and a high-density heat protection layer arranged in sequence from bottom to top; wherein the density of the high-density heat protection layer is 1.38g / cm 3 The density of the medium-density heat-proof layer is 1.17g / cm 3 The density of the low-density heat-proof layer is 0.91g / cm 3 The thickness of the lightweight thermal insulation layer is 24 mm, and the thicknesses of the low-density thermal insulation layer, the medium-density thermal insulation layer and the high-density thermal insulation layer are 2 mm respectively; the aerogel is phenolic aerogel; the ceramic resin includes phenolic resin, ethanol, zirconium oxide and silicon carbide; the mass ratios of phenolic resin, ethanol, zirconium oxide and silicon carbide are 5:1:5:5 (1#), 5:5:5:5 (2#) and 5:7.5:5:5 (3#) for high, medium and low, respectively; the particle size of the ceramic filler is 1 μm.

[0083] A method for preparing an ablation-resistant multi-element gradient heat-insulating integrated composite material, specifically comprising:

[0084] Preparation of gradient heat protection layer: Phenolic resin, ethanol, zirconium oxide and silicon carbide were mixed in a mass ratio of 5:1:5:5 (1#), 5:5:5:5 (2#), and 5:7.5:5:5 (3#) respectively and stirred evenly to obtain ceramic resin solution. Quartz fiber braids with thicknesses of 1mm, 2mm and 3mm were completely impregnated with 1#, 2# and 3# ceramic resin solutions respectively using RTM process and dried to obtain heat protection layer. The heat protection layer obtained by impregnation with 1# solution was a high-density heat protection layer with a density of 1.38g / cm 3 The medium-density heat-resistant layer obtained by impregnation with 2# solution has a density of 1.17g / cm 3 The low-density heat-resistant layer obtained by impregnation with 3# solution has a density of 0.91g / cm 3 The high, medium and low density heat-proof layers and 24 mm thick quartz fiber felt were sequentially sewn together and cured at 150°C for 5 h to obtain a 30 mm thick gradient heat-proof layer.

[0085] Preparation of lightweight thermal insulation layer: Prepare silica aerogel precursor solution, use RTM process to fully impregnate the gradient thermal insulation layer with silica aerogel precursor solution, then carry out sol-gel process, solvent replacement and drying in sequence to prepare ablation-resistant multi-element gradient thermal insulation integrated composite material. The density of the thermal insulation layer is 0.30g / cm 3 The density of the ablation-resistant multi-element gradient heat-insulating integrated composite material is 0.46g / cm 3 , at 1.5MW / m 2 Under the oxyacetylene heat flux test conditions of -500s, the surface retreat was 0.82mm and the back temperature was 342℃.

[0086] Example 3

[0087] An ablation-resistant multi-element gradient heat-insulating integrated composite material, comprising a gradient-density heat-proof layer and a lightweight heat-insulating layer, wherein the gradient-density heat-proof layer is arranged above the lightweight heat-insulating layer; the raw materials of the gradient-density heat-proof layer are quartz fiber braid and ceramic resin, and the raw material of the lightweight heat-insulating layer is quartz fiber felt; the interiors of the gradient-density heat-proof layer and the lightweight heat-insulating layer are both filled with aerogel.

[0088] The gradient density heat protection layer includes a low-density heat protection layer, a medium-density heat protection layer and a high-density heat protection layer arranged in sequence from bottom to top; wherein the density of the high-density heat protection layer is 1.35g / cm 3 The density of the medium-density heat-proof layer is 1.09g / cm 3 The density of the low-density heat-proof layer is 0.84g / cm 3 The thickness of the lightweight insulation layer is 65 mm, and the thicknesses of the low-density thermal protection layer, the medium-density thermal protection layer and the high-density thermal protection layer are 5 mm respectively; the aerogel is phenolic aerogel; the ceramic resin includes phenolic resin, ethanol, zirconium boride and silicon carbide; the mass ratios of phenolic resin, ethanol, zirconium boride and silicon carbide are 5:1:2.5:2.5 (1#), 5:5:2.5:2.5 (2#) and 5:7.5:2.5:2.5 (3#) for high, medium and low, respectively; the particle size of the ceramic filler is 1 μm.

[0089] A method for preparing an ablation-resistant multi-element gradient heat-insulating integrated composite material, specifically comprising:

[0090] Preparation of gradient heat shield: Phenolic resin, ethanol, zirconium boride, and silicon carbide were mixed in a mass ratio of 5:1:2.5:2.5 (1#), 5:5:2.5:2.5 (2#), and 5:7.5:2.5:2.5 (3#) respectively, and stirred evenly to obtain a ceramic resin solution. A 5mm thick quartz fiber braid was completely impregnated with the ceramic resin solution using the RTM process and dried to obtain a heat shield. The high-density heat shield obtained by impregnation with the 1# solution had a density of 1.35g / cm3 The medium-density heat-resistant layer obtained by impregnation with 2# solution has a density of 1.09g / cm 3 The low-density heat-resistant layer obtained by impregnation with 3# solution has a density of 0.84g / cm 3 The high, medium and low density heat-proof layers and 65 mm thick quartz fiber felt were stacked and sewn in sequence in the thickness direction and cured at 150 ° C for 5 h to obtain an 80 mm thick gradient heat-proof layer.

[0091] Preparation of lightweight thermal insulation layer: Prepare phenolic aerogel precursor solution, use RTM process to fully impregnate the gradient thermal insulation layer with phenolic aerogel precursor solution, then carry out sol-gel process, solvent replacement and drying in sequence to prepare ablation-resistant multi-element gradient thermal insulation integrated composite material. The density of the thermal insulation layer is 0.33g / cm 3 The density of the ablation-resistant multi-element gradient heat-insulating integrated composite material is 0.47g / cm 3 , at 1.5MW / m 2 Under the oxyacetylene heat flux test conditions of -500s, the surface retreat is 0.95mm and the back temperature is 45℃.

[0092] Comparative Example 1

[0093] A lightweight thermal insulation material. The composite material comprises only a lightweight thermal insulation layer. The raw material of the lightweight thermal insulation layer is quartz fiber felt. The interior of the lightweight thermal insulation layer is filled with aerogel.

[0094] A method for preparing a lightweight thermal insulation material, specifically comprising:

[0095] Preparation of lightweight thermal insulation layer: Prepare phenolic aerogel precursor solution, use RTM process to fully impregnate the gradient thermal insulation layer with phenolic aerogel precursor solution, then carry out sol-gel process, solvent replacement and drying in sequence to prepare lightweight thermal insulation composite material. The density of lightweight thermal insulation composite material is 0.33g / cm 3 , thickness is 30mm, at 1.5MW / m 2 Under the oxyacetylene heat flux test conditions of -500s, the surface retreat is 9.6mm and the back temperature is 408℃.

[0096] Comparative Example 2 (only for Example 3)

[0097] An ablation-resistant multi-element gradient heat-insulating integrated composite material, comprising a heat-proof layer and a lightweight heat-insulating layer, wherein the heat-proof layer is disposed above the lightweight heat-insulating layer; the heat-proof layer is made of a quartz fiber braid and ceramic resin, while the lightweight heat-insulating layer is made of a quartz fiber felt; and both the heat-proof layer and the lightweight heat-insulating layer are filled with aerogel.

[0098] The density of the heat protection layer is 1.35g / cm 3The thickness of the lightweight insulation layer is 65 mm, and the thickness of the heat protection layer is 15 mm; the aerogel is phenolic aerogel; the ceramic resin includes phenolic resin, ethanol, zirconium boride and silicon carbide; the mass ratio of phenolic resin, ethanol, zirconium boride and silicon carbide is 5:1:2.5:2.5, and the particle size of the ceramic filler is 1 μm.

[0099] A method for preparing an ablation-resistant multi-element gradient heat-insulating integrated composite material, specifically comprising:

[0100] Preparation of gradient heat protection layer: Phenolic resin, ethanol, zirconium boride and silicon carbide were mixed in a mass ratio of 5:1:2.5:2.5 to obtain a ceramic resin solution. A 15 mm thick quartz fiber braid was completely impregnated with the ceramic resin solution using the RTM process and dried to obtain a heat protection layer with a density of 1.35 g / cm 3 The heat-proof layer and the 65 mm thick quartz fiber felt were stacked and sewn in the thickness direction and cured at 150 ° C for 5 hours to obtain an 80 mm thick heat-proof layer;

[0101] Preparation of lightweight thermal insulation layer: Prepare phenolic aerogel precursor solution, use RTM process to fully impregnate the gradient thermal insulation layer with phenolic aerogel precursor solution, then carry out sol-gel process, solvent replacement and drying in sequence to prepare ablation-resistant multi-element gradient thermal insulation integrated composite material. The density of the thermal insulation layer is 0.33g / cm 3 The density of the ablation-resistant multi-element gradient heat-insulating integrated composite material is 0.52g / cm 3 , at 1.5MW / m 2 Under the oxyacetylene heat flux test conditions of -500s, the surface retreat was 0.92mm and the back temperature was 59℃.

[0102] In summary, the comparative example 1 only sets a light insulation layer, and the ablation resistance is poor (at 1.5MW / m 2 -500s oxyacetylene heat flow test conditions, the surface retreat is 9.6mm, the back temperature is 408 ° C); Comparative Example 2 is set on the basis of Example 3, and Comparative Example 2 does not set a gradient insulation layer of high-density heat-proof layer, medium-density heat-proof layer and low-density heat-proof layer, so the density of the composite material is high, and the corrosion resistance deviation (at 1.5MW / m 2 Under the oxyacetylene heat flow test conditions of -500s, the surface retreat was 0.92mm and the back temperature was 59°C. However, Examples 1 to 3 of the present application provide ablation-resistant multi-element gradient anti-thermal insulation integrated composite material, which achieves different densities and back temperatures by reasonably setting the thickness. (Thickness affects density and back temperature; when the thickness increases, the insulation layer increases, the thermal insulation performance improves, the back temperature decreases, and the overall density also decreases.)

[0103] One or more technical solutions in the embodiments of the present application may have at least the following technical effects or advantages:

[0104] (1) The ablation-resistant multi-element gradient heat-insulating integrated composite material has the characteristics of smooth surface after ablation, small surface retreat after long-term high-temperature ablation, and low density. It can be used in the surface thermal protection system of high-speed and long-endurance aircraft.

[0105] (2) The use of a gradient heat-resistant layer greatly simplifies the preparation process of the heat-resistant layer in the heat-insulating integrated composite material. At the same time, the gradient structure greatly reduces the overall density of the material while retaining the material's good anti-ablation performance.

[0106] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. An ablation-resistant multi-element gradient heat-insulating integrated composite material, comprising a gradient-density heat-insulating layer and a lightweight heat-insulating layer, wherein the gradient-density heat-insulating layer is disposed above the lightweight heat-insulating layer; The raw materials of the gradient density heat protection layer are fiber braid and ceramic resin, and the raw materials of the lightweight heat insulation layer are fiber felt; The gradient density heat protection layer and the lightweight heat insulation layer are both filled with aerogel.

2. The composite material according to claim 1, characterized in that The gradient density heat protection layer includes a low-density heat protection layer, a medium-density heat protection layer and a high-density heat protection layer arranged in sequence from bottom to top; wherein, The density of the high-density heat-proof layer is 1.2g / cm 3 ~1.4g / cm 3 The density of the medium-density heat-proof layer is 1.0g / cm 3 ~1.2g / cm 3 The density of the low-density heat-proof layer is 0.8g / cm 3 ~1.0g / cm 3 .

3. The composite material according to claim 1, characterized in that The aerogel includes at least one of the following: phenolic aerogel, silica aerogel, and alumina aerogel.

4. The composite material according to claim 1, characterized in that The ceramic resin includes phenolic resin, ceramic filler and solvent, and the mass ratio of the phenolic resin, the ceramic filler and the solvent is (1-10):(1-10):(1-10).

5. The composite material according to claim 4, characterized in that The ceramic filler comprises at least one of the following: boride, carbide, oxide; and / or, The particle size of the ceramic filler is 0.3 μm to 3 μm.

6. The composite material according to claim 4, characterized in that The solvent includes an alcohol solvent.

7. The composite material according to claim 1, characterized in that The thickness of a single layer of the gradient density heat protection layer is 0.5 mm to 10 mm; and / or, The thickness of the composite material is 20 mm to 80 mm.

8. The composite material according to claim 1, characterized in that The density of the lightweight thermal insulation layer is 0.3 g / cm 3 ~0.6g / cm 3 and / or, The density of the composite material is ≤0.8g / cm 3 .

9. A method for preparing the ablation-resistant multi-element gradient heat-insulating integrated composite material according to any one of claims 1 to 8, the method comprising: Mixing phenolic resin, solvent and ceramic filler, and adjusting the content of the solvent to obtain a gradient concentration ceramic resin solution; impregnating a plurality of fiber braids with the gradient-concentration ceramic resin solution and drying the solution to obtain a gradient-density heat-resistant layer; The gradient density heat-proof layer and the fiber felt are stacked and stitched together for curing to obtain a first heat-proof integrated composite material; impregnating the first thermal insulation integrated composite material with an aerogel precursor to obtain a second thermal insulation integrated composite material filled with the aerogel precursor; The second thermal insulation integrated composite material filled with aerogel precursor is subjected to sol-gel and drying in sequence to obtain an ablation-resistant multi-element gradient thermal insulation integrated composite material.

10. The method according to claim 9, characterized in that The curing process parameters include: temperature of 120° C. to 180° C., and time of 1 hour to 10 hours.

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