A lightweight and efficient heat-insulating protective structure

Abstract

The present invention provides a lightweight and efficient heat-insulating protective structure, which relates to the field of functional composite materials, and comprises a hot surface protective layer (10), a heat-insulating layer and a cold surface protective layer (30). The heat-insulating layer is formed by alternately stacking a thermal resistance layer (21) and a reflective layer (22), the number of the thermal resistance layers (21) is n, the number of the reflective layers (22) is n+1, and n is not less than 1; the reflective layer (22) is a sandwich structure formed by an A-side polyimide film (221), an aluminum-plated layer (222), and a B-side polyimide film (223), and the B-side polyimide film (223) is close to the hot surface protective layer (10), and the A-side polyimide film (221) is close to the cold surface protective layer (30). The heat-insulating protective structure can solve the problems of poor high-temperature heat-insulating effect, poor moisture and heat resistance, salt spray resistance, and vibration resistance of the existing protective structure, large thickness, large surface density, large weight, and easy cracking and deformation.

Description

Technical Field

[0001] The invention relates to the technical field of functional composite materials, and in particular to a lightweight and efficient heat-insulating protective structure. Background Art

[0002] The parachute compartment is the compartment on the aircraft used to load the recovery parachute or the drag parachute. Under the influence of the engine radiation heat and aerodynamic heating, if the temperature of the parachute compartment is too high, not only will the fabric of the recovery parachute or the drag parachute itself be difficult to bear, but the carbonization of the pressure oil will also cause the recovery parachute or the drag parachute to be unable to be released normally, thus causing serious safety accidents. Therefore, during the design and manufacturing process, it is necessary to effectively insulate the parachute compartment and control the temperature of the inner wall of the parachute compartment within the range allowed by the material properties to improve the reliability and safety of the recovery parachute or the drag parachute.

[0003] The existing thermal insulation protection structure usually uses aluminum foil directly as the reflective layer, which has the following problems: First, the emissivity of the aluminum foil will increase with the increase of temperature, which will lead to a decrease in reflective ability; second, the existing thermal insulation protection structure is a non-completely sealed structure. During use, there is a possibility that the atmosphere, liquid, etc. enter the interior of the thermal insulation protection structure and corrode the reflective layer, which can easily lead to a decrease in the thermal insulation effect. At the same time, the existing thermal insulation protection structure usually uses a metal layer as a protective layer of the composite structure, but directly uses a smooth metal structure as a protective layer. When the area of ​​the thermal insulation product is large, the overall strength of the thermal insulation protection structure is low and it is easy to deform. In addition, the metal structure has a large thickness, large surface density, and heavy weight. During use, it is easy to crack, wrinkle, and other problems, which directly affects its protective performance and thermal insulation performance; in addition, when the metal structure is combined with the thermal insulation material, in order to ensure the stability of the overall structure, the metal structure is usually tightly fitted with the thermal insulation material, which can easily form heat conduction and heat accumulation on the metal structure, directly affecting the thermal insulation effect of the thermal insulation material. Summary of the invention

[0004] In view of the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a lightweight and efficient thermal insulation protective structure, which can effectively solve the problems of the existing protective structure, such as poor high-temperature thermal insulation effect, poor resistance to moisture and heat, salt spray and vibration, large thickness, high surface density, high weight, easy cracking and deformation, etc., and has the characteristics of lightweight, efficient thermal insulation, long-term and stable protection.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A lightweight and efficient heat-insulating protective structure comprises a hot surface protection layer, a heat-insulating layer and a cold surface protection layer, wherein the heat-insulating layer is formed by alternatingly stacking thermal resistance layers and reflective layers, the number of thermal resistance layers is n, the number of reflective layers is n+1, and n is not less than 1 (i.e., the layers close to the hot surface protection layer and the cold surface protection layer are reflective layers); the reflective layer is a sandwich structure formed by an A-side polyimide film, an aluminum-plated layer, and a B-side polyimide film, wherein the B-side polyimide film is close to the hot surface protection layer, and the A-side polyimide film is close to the cold surface protection layer.

[0007] Due to the difference in expansion coefficient between the reflective layer and the thermal resistance layer, stress concentration is easily generated between the reflective layer and the thermal resistance layer, which leads to interlayer cracking and gradually expands outward, causing the thermal insulation protection structure to fail, increase the thermal conductivity, and reduce its thermal protection ability; the present application effectively improves the interlayer shear performance through the lamination of a specific thermal resistance layer and a reflective layer, and can inhibit the expansion of delamination damage during the thermal shock process, thereby eliminating interlayer cracking and ensuring the plasticity of the thermal insulation protection structure. At the same time, through the sandwich design formed by the A-side polyimide film, the aluminum-plated layer, and the B-side polyimide film, the aluminum layer is protected by a polyimide film with low surface density, excellent thermal stability, flame retardancy and mechanical properties, so as to avoid the increase in the emissivity of the aluminum foil with the increase in temperature and the influence of external erosion on the aluminum layer, thereby improving the reflective layer's environmental adaptability such as resistance to moisture and heat, and resistance to salt spray. In addition, the use of an aluminum layer with high reflectivity and low roughness as the middle layer of the sandwich structure can, firstly, achieve the bonding of two layers of polyimide film using the aluminum layer without the need for adhesives, thereby improving the integrity of the reflective layer; secondly, form an insulating gradient, that is, the inner layer is an aluminum layer with high thermal reflectivity and high thermal conductivity, and the outer layer is a polyimide film with low thermal conductivity. Through interlayer reflection and barrier, effective attenuation of thermal radiation and heat transfer is achieved, thereby improving the thermal insulation performance of the entire reflective layer.

[0008] Based on further optimization of the above scheme, the hot surface protection layer and the cold surface protection layer both adopt a metal embossed titanium foil structure, that is, protrusions distributed in an array are arranged on the surface of the flat titanium foil structure, the protrusions of the hot surface protection layer protrude toward the side away from the thermal insulation layer, and the protrusions of the cold surface protection layer protrude toward the side close to the thermal insulation layer.

[0009] Based on further optimization of the above solution, the convex shapes of the hot surface protection layer and the cold surface protection layer are any one of rice grain shape, pearl shape and water drop shape.

[0010] Based on the further optimization of the above scheme, the thickness of the hot surface protection layer and the cold surface protection layer are both 0.03-0.1 mm; the diameter of the protrusion is 1-2.5 mm, and the height is 0.4-1.0 mm; the distance between two adjacent protrusions is 4-8 mm; the number of protrusions per unit area in the protection layer (i.e., the hot surface protection layer or the cold surface protection layer) is 1.5x10 4 ~6x104 indivual.

[0011] Through the setting of the protrusions, firstly, the strain hardening effect formed during the pressing process of the protrusions is utilized to improve the stiffness of the hot surface protection layer and the cold surface protection layer, thereby improving the overall stiffness of the protective structure and realizing the protection of the internal thermal insulation layer; secondly, by evenly distributing the uneven protrusions and reducing the wrinkles formed during the molding process of the protective layer, the weak points of failure are reduced, the damage of the protective layer is avoided, and the overall resistance of the protective structure to liquid penetration is improved; thirdly, through the outward protrusions of the hot surface protective layer, the reflective surface of the surface of the protective structure is converted from mirror reflection to dot matrix diffuse reflection, thereby expanding the heat reflection area and improving the reflection efficiency; fourthly, by utilizing the cavity matrix formed between the protrusions of the hot surface protective layer and the thermal insulation layer, the interlayer flow field is changed, micro air gaps are formed, heat conduction is effectively blocked, and the thermal insulation effect is improved; fifthly, through the protrusions of the cold surface protective layer, the contact between the cold surface protective layer and the thermal insulation layer is converted from surface contact to point contact, thereby reducing the heat conduction area, avoiding the formation of temperature concentration points, and realizing uniform and rapid dissipation of the remaining heat after blocking. In addition, through the cavity matrix formed between the cold surface protection layer and the substrate, the dissipation rate of the residual heat is further increased through the micro air gaps in the interlayer flow field, thereby improving the thermal insulation effect.

[0012] Based on further optimization of the above scheme, the thickness of the thermal resistance layer is 0.5-5 mm; the thermal resistance layer adopts basalt fiber reinforced silica aerogel felt, wherein the diameter of the basalt fiber is not greater than 6 μm, the mass ratio of basalt fiber to silica aerogel is 1:0.78-1, and the thermal conductivity of the basalt fiber reinforced silica aerogel felt at room temperature is 0.017-0.020 W / (m•K).

[0013] Using small-diameter basalt fibers as reinforcing fibers for nanoporous silica aerogel can effectively limit the solid heat conduction of the fibers themselves, making the basalt fiber felt itself have a lower thermal conductivity. At the same time, using short-diameter basalt fibers to form a low-density preform can further reduce the density of the fiber-reinforced aerogel composite while ensuring its mechanical properties. The diameter of the fiber preform is close to the wavelength of near-infrared radiation, which can produce a strong diffraction and scattering effect on the near-infrared radiation, thereby further enhancing the high-temperature infrared radiation heat conduction barrier effect. In addition, the addition of basalt fibers can effectively solve the problems of pure aerogel being brittle and easy to break.

[0014] Based on the further optimization of the above scheme, the volume density of the basalt fiber reinforced silica aerogel felt is 150-170 kg / m 3 The bulk density of the preform formed by basalt fiber is 80~90kg / m 3 The density of silica aerogel is 70~80kg / m 3.

[0015] Based on further optimization of the above solution, the thickness of the polyimide film on the A side is 20-30 μm, the thickness of the aluminum plating layer is 100-200 nm, and the thickness of the polyimide film on the B side is 4-6 μm.

[0016] The following are the effects of the technical solution of the present invention:

[0017] The present application uses a hot surface protection layer, a cold surface protection layer, and a structure design of a stacked and staggered reflective layer-…-thermal resistance layer-…-reflective layer, and uses the hot surface protection layer and the cold surface protection layer to protect the thermal insulation layer formed by the reflective layer-…-thermal resistance layer-…-reflective layer, effectively preventing the infiltration of the external atmosphere, liquid, etc., thereby affecting the thermal insulation performance of the thermal resistance layer with nanoporous silica aerogel, ensuring the long-term stability and effectiveness of the thermal insulation performance of the protective structure; and through the combination of the hot surface protection layer and the cold surface protection layer, the protective shell structure is integrated, thereby improving the integrity, connection reliability, and overall infiltration and corrosion resistance of the thermal insulation protection structure. At the same time, the sandwich structure formed by the polyimide film and the aluminum layer is used to achieve double protection, avoiding the problem of reduced reflectivity caused by the thin reflective aluminum layer being affected by leaking liquids, gases, etc. In addition, the structure of the hot surface protection layer and the cold surface protection layer cooperates with the thermal insulation layer to further improve the overall thermal insulation performance of the protective structure, effectively avoid the formation of temperature accumulation points, and ensure the stability and long-term effectiveness of the thermal insulation. The overall principle of the protective structure of the present application is clear, simple, reliable, and highly lightweight. It can be used for thermal insulation protection of special equipment in various fields under high temperature environments of 120 to 350°C, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the overall structure of the heat insulation protection structure in an embodiment of the present invention.

[0019] Figure 2 for Figure 1 A partial enlarged view of middle A.

[0020] Figure 3 Schematic diagram of the structure of the hot surface protection layer of the heat insulation protection structure in an embodiment of the present invention.

[0021] Among them, 10, hot surface protection layer; 21, thermal resistance layer; 22, reflective layer; 221, A-side polyimide film; 222, aluminum plating layer; 223, B-side polyimide film; 30, cold surface protection layer. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly described below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0023] Embodiment 1:

[0024] A lightweight and highly efficient thermal insulation protection structure, see Figure 1 As shown, the hot surface protection layer 10, the heat insulation layer and the cold surface protection layer 30 are both made of a metal embossed titanium foil structure, that is, protrusions (such as Figure 3 As shown, the protrusion of the hot surface protection layer 10 faces the side away from the heat insulation layer (i.e. Figure 1 The cold surface protective layer 30 protrudes toward the side close to the heat insulation layer (i.e. Figure 1 The hot surface protection layer 10 and the cold surface protection layer 30 are shaped like rice grains; the thickness of the hot surface protection layer 10 and the cold surface protection layer 30 is 0.03 mm (the thickness of the titanium foil when the hot surface protection layer 10 and the cold surface protection layer 30 are flat); the diameter of the protrusion is 1 mm and the height is 0.4 mm; the distance between two adjacent protrusions is 4 mm; the number of protrusions per unit area in the protective layer (i.e., the hot surface protection layer 10 or the cold surface protection layer 30) is 6x10 4 indivual.

[0025] The thermal insulation layer is formed by alternating thermal resistance layers 21 and reflective layers 22, the number of thermal resistance layers 21 is n, the number of reflective layers 22 is n+1, and n is not less than 1 (that is, the reflective layers 22 are all close to the hot surface protection layer 10 and the cold surface protection layer 30; the specific number of thermal resistance layers 21 and reflective layers 22 is determined according to the actual insulation effect required, for example, in this embodiment, a structure of five thermal resistance layers 21 + six reflective layers 22 is adopted); the thickness of the thermal resistance layer 21 is 2 mm, and the thermal resistance layer 21 adopts basalt fiber reinforced silica aerogel felt, wherein the diameter of the basalt fiber is not more than 6 μm, the mass ratio of basalt fiber to silica aerogel is 1:0.78, and the thermal conductivity of the basalt fiber reinforced silica aerogel felt at room temperature is 0.020 W / (m•K); the volume density of the basalt fiber reinforced silica aerogel felt is 159.74 kg / m 3 The bulk density of the preform formed by basalt fiber is 89.74kg / m 3 The density of silica aerogel is 70kg / m 3 .

[0026] Reference Figure 2As shown: the reflective layer 22 is a sandwich structure formed by an A-side polyimide film 221, an aluminum-plated layer 222, and a B-side polyimide film 223, and the B-side polyimide film 223 is close to the hot surface protection layer 10, and the A-side polyimide film 221 is close to the cold surface protection layer 30 (that is, with respect to the B-side polyimide film 223 and the A-side polyimide film 221 of the single-layer reflective layer 22, the B-side polyimide film 223 is closer to the hot surface protection layer 10, and the A-side polyimide film 221 is closer to the cold surface protection layer 30); the thickness of the A-side polyimide film 221 is 20μm, the thickness of the aluminum-plated layer 222 is 100nm, and the thickness of the B-side polyimide film 223 is 4μm.

[0027] Embodiment 2:

[0028] A lightweight and highly efficient thermal insulation protection structure, see Figure 1 As shown, the hot surface protection layer 10, the heat insulation layer and the cold surface protection layer 30 are both made of a metal embossed titanium foil structure, that is, protrusions (such as Figure 3 As shown, the protrusion of the hot surface protection layer 10 faces the side away from the heat insulation layer (i.e. Figure 1 The cold surface protective layer 30 protrudes toward the side close to the heat insulation layer (i.e. Figure 1 The hot surface protection layer 10 and the cold surface protection layer 30 are convex in shape of pearls; the thickness of the hot surface protection layer 10 and the cold surface protection layer 30 is 0.06 mm (the thickness of the titanium foil when the hot surface protection layer 10 and the cold surface protection layer 30 are flat); the diameter of the convex is 1.5 mm and the height is 0.7 mm; the distance between two adjacent convexities is 6 mm; the number of convexities per unit area in the protective layer (i.e., the hot surface protection layer 10 or the cold surface protection layer 30) is 3.8 x 10 4 indivual.

[0029] The thermal insulation layer is formed by alternatingly stacking thermal resistance layers 21 and reflective layers 22, the number of thermal resistance layers 21 is n, the number of reflective layers 22 is n+1, and n is not less than 1 (that is, the layers close to the hot surface protection layer 10 and the cold surface protection layer 30 are all reflective layers; the specific number of thermal resistance layers 21 and reflective layers 22 is determined according to the actual insulation effect required, for example, in this embodiment, a structure of five thermal resistance layers 21 + six reflective layers 22 is adopted); the thickness of the thermal resistance layer 21 is 2 mm, and the thermal resistance layer 21 adopts basalt fiber reinforced silica aerogel felt, wherein the diameter of the basalt fiber is not more than 6 μm, the mass ratio of basalt fiber to silica aerogel is 1:0.85, and the thermal conductivity of the basalt fiber reinforced silica aerogel felt at room temperature is 0.018 W / (m•K); the volume density of the basalt fiber reinforced silica aerogel felt is 163.24 kg / m 3The bulk density of the preform formed by basalt fiber is 88.24kg / m 3 The density of silica aerogel is 75kg / m 3 .

[0030] Reference Figure 2 As shown: the reflective layer 22 is a sandwich structure formed by an A-side polyimide film 221, an aluminum-plated layer 222, and a B-side polyimide film 223, and the B-side polyimide film 223 is close to the hot surface protection layer 10, and the A-side polyimide film 221 is close to the cold surface protection layer 30 (that is, with respect to the B-side polyimide film 223 and the A-side polyimide film 221 of the single-layer reflective layer 22, the B-side polyimide film 223 is closer to the hot surface protection layer 10, and the A-side polyimide film 221 is closer to the cold surface protection layer 30); the thickness of the A-side polyimide film 221 is 25μm, the thickness of the aluminum-plated layer 222 is 150nm, and the thickness of the B-side polyimide film 223 is 5μm.

[0031] Embodiment 3:

[0032] A lightweight and highly efficient thermal insulation protection structure, see Figure 1 As shown, the hot surface protection layer 10, the heat insulation layer and the cold surface protection layer 30 are both made of a metal embossed titanium foil structure, that is, protrusions (such as Figure 3 As shown, the protrusion of the hot surface protection layer 10 faces the side away from the heat insulation layer (i.e. Figure 1 The cold surface protective layer 30 protrudes toward the side close to the heat insulation layer (i.e. Figure 1 The hot surface protection layer 10 and the cold surface protection layer 30 are convex in the shape of a water drop; the thickness of the hot surface protection layer 10 and the cold surface protection layer 30 is 0.1 mm (the thickness of the titanium foil when the hot surface protection layer 10 and the cold surface protection layer 30 are flat); the diameter of the convex is 2.5 mm and the height is 1.0 mm; the distance between two adjacent convexities is 8 mm; the number of convexities per unit area in the protective layer (i.e., the hot surface protection layer 10 or the cold surface protection layer 30) is 1.5x10 4 indivual.

[0033] The thermal insulation layer is formed by alternatingly stacking thermal resistance layers 21 and reflective layers 22, the number of thermal resistance layers 21 is n, the number of reflective layers 22 is n+1, and n is not less than 1 (that is, the layers close to the hot surface protection layer 10 and the cold surface protection layer 30 are all reflective layers; the specific number of thermal resistance layers 21 and reflective layers 22 is determined according to the actual insulation effect required, for example, in this embodiment, a structure of five layers of thermal resistance layers 21 + six layers of reflective layers 22 is adopted); the thickness of the thermal resistance layer 21 is 2 mm, and the thermal resistance layer 21 adopts basalt fiber reinforced silica aerogel felt, wherein the diameter of the basalt fiber is not more than 6 μm, the mass ratio of basalt fiber to silica aerogel is 1:1, and the thermal conductivity of the basalt fiber reinforced silica aerogel felt at room temperature is 0.017 W / (m•K); the volume density of the basalt fiber reinforced silica aerogel felt is 160 kg / m 3 The bulk density of the preform formed by basalt fiber is 80kg / m 3 , the density of silica aerogel is 80kg / m 3 .

[0034] Reference Figure 2 As shown: the reflective layer 22 is a sandwich structure formed by an A-side polyimide film 221, an aluminum-plated layer 222, and a B-side polyimide film 223, and the B-side polyimide film 223 is close to the hot surface protection layer 10, and the A-side polyimide film 221 is close to the cold surface protection layer 30 (that is, with respect to the B-side polyimide film 223 and the A-side polyimide film 221 of the single-layer reflective layer 22, the B-side polyimide film 223 is closer to the hot surface protection layer 10, and the A-side polyimide film 221 is closer to the cold surface protection layer 30); the thickness of the A-side polyimide film 221 is 30μm, the thickness of the aluminum-plated layer 222 is 200nm, and the thickness of the B-side polyimide film 223 is 6μm.

[0035] Comparative Example 1:

[0036] A heat insulation protection structure includes a hot surface protection layer, a heat insulation layer and a cold surface protection layer. The thickness, structure, material, etc. of the hot surface protection layer are consistent with those in Example 2, that is, a metal embossed titanium foil structure; the cold surface protection layer is 0.06 mm thick, and the cold surface protection layer adopts a flat and smooth titanium foil structure. The heat insulation layer is consistent with that in Example 2 (including the thickness, material, number of layers, etc. of the thermal resistance layer and the reflective layer).

[0037] Comparative Example 2:

[0038] A heat insulation protection structure includes a hot surface protection layer, a heat insulation layer and a cold surface protection layer. The thickness, structure, material, etc. of the cold surface protection layer are consistent with those in Example 2, that is, a metal embossed titanium foil structure; the thickness of the hot surface protection layer is 0.06 mm, and the hot surface protection layer adopts a flat and smooth titanium foil structure. The heat insulation layer is consistent with that in Example 2 (including the thickness, material, number of layers, etc. of the thermal resistance layer and the reflective layer).

[0039] Comparative Example 3:

[0040] A heat-insulating protective structure comprises a hot surface protection layer, a heat-insulating layer and a cold surface protection layer, wherein the thickness, structure, material, etc. of the hot surface protection layer and the cold surface protection layer are consistent with those in Example 2, that is, a metal embossed titanium foil structure; the heat-insulating layer is formed by alternatingly stacking a thermal resistance layer and a reflective layer, the number of reflective layers is n, the number of thermal resistance layers is n+1, and n is not less than 1 (that is, the layers close to the hot surface protection layer and the cold surface protection layer are all thermal resistance layers; the total number of layers of the thermal resistance layer and the reflective layer is consistent with that in Example 2), and the thickness, material, etc. of the thermal resistance layer and the reflective layer are consistent with those in Example 2.

[0041] Comparative Example 4:

[0042] A heat-insulating protective structure comprises a hot surface protection layer, a heat-insulating layer and a cold surface protection layer. The thickness, structure, material, etc. of the hot surface protection layer and the cold surface protection layer are consistent with those in Example 2, that is, a metal embossed titanium foil structure; the heat-insulating layer is formed by alternatingly stacking a thermal resistance layer and a reflective layer, and the number of the thermal resistance layers and the number of the reflective layers are consistent with those in Example 2; at the same time, the thickness and material of the thermal resistance layer 21 are consistent with those in Example 2, the reflective layer adopts a smooth and flat aluminum foil structure, and the thickness of the reflective layer is consistent with that in Example 2.

[0043] Performance test: The heat insulation protection structure samples obtained in Examples 1 to 3 and Comparative Examples 1 to 4 (the sample sizes are all 400 mm long and 300 mm wide) are fixed on the bracket of the closed inner cavity of the heating equipment. At the same time, three temperature measuring points (i.e., thermocouples) are evenly arranged on the cold surface of the sample, and the cold surface temperature of the sample is continuously collected by the thermocouple; when the hot surface temperature is 300°C, the ambient temperature is 23°C, and the insulation time is 1 hour (the other test conditions of Examples 1 to 3 and Comparative Examples 1 to 4 are consistent), the test results are as follows:

[0044]

[0045] It can be clearly seen from the above table that the laminated structure combination of the cold surface protection layer + the outer layer of the hot surface protection layer of the specific structure of the present application, and the reflective layer + the thermal resistance layer of the specific material can effectively improve the thermal insulation performance of the protective structure. Under the long-term (i.e., 1 hour) action of the hot surface temperature of 300°C, the average temperature of the cold surface of the thermal insulation protection structure prepared by the present application is not more than 63°C, which is significantly lower than the thermal insulation protection structure and the average temperature of the cold surface prepared in Comparative Examples 1 to 4 (the cold surface temperature in Comparative Examples 1 to 4 is 70°C and above); at the same time, the temperature difference of each temperature measuring point of the thermal insulation protection structure prepared by the present application is small, which proves that the structure of the present application can dissipate heat evenly and there is no temperature concentration point, which also indirectly proves that the interlayer heat insulation effect of the present application is good.

Claims

1. A lightweight and efficient heat-insulating protective structure, characterized in that: It comprises a hot surface protection layer, a heat insulation layer and a cold surface protection layer, wherein the heat insulation layer is formed by alternately stacking a thermal resistance layer and a reflective layer, the number of the thermal resistance layers is n, the number of the reflective layers is n+1, and n is not less than 1; the reflective layer is a sandwich structure formed by an A-side polyimide film, an aluminum-plated layer, and a B-side polyimide film, and the B-side polyimide film is close to the hot surface protection layer, and the A-side polyimide film is close to the cold surface protection layer; the thickness of the A-side polyimide film is 20 to 30 μm, and the thickness of the B-side polyimide film is 4 to 6 μm; The hot surface protective layer and the cold surface protective layer both adopt a metal embossed titanium foil structure, that is, protrusions distributed in an array are arranged on the surface of the flat titanium foil structure, the protrusions of the hot surface protective layer protrude toward the side away from the thermal insulation layer, and the protrusions of the cold surface protective layer protrude toward the side close to the thermal insulation layer; the protrusions of the hot surface protective layer and the cold surface protective layer are in the shape of rice grains, pearls, or water drops; the thickness of the hot surface protective layer and the cold surface protective layer is 0.03-0.1 mm; the diameter of the protrusions is 1-2.5 mm, and the height is 0.4-1.0 mm; the distance between two adjacent protrusions is 4-8 mm; the number of protrusions per unit area in the hot surface protective layer or the cold surface protective layer is 1.5x10 4 ~6x10 4 indivual; The thickness of the thermal resistance layer is 0.5-5 mm; the thermal resistance layer adopts basalt fiber reinforced silica aerogel felt, wherein the diameter of the basalt fiber is not more than 6 μm, the mass ratio of basalt fiber to silica aerogel is 1:0.78-1, and the thermal conductivity of the basalt fiber reinforced silica aerogel felt at room temperature is 0.017-0.020 W / (m•K).

2. A lightweight and efficient heat-insulating protective structure according to claim 1, characterized in that: The thickness of the aluminum plating layer is 100-200 nm.

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