Aerospace craft outer shell and preparation method thereof

Abstract

The invention discloses an aerospace craft outer shell and a preparation method thereof, the aerospace craft outer shell comprises a cylindrical metal shell, and the outer wall surface of the metal shell is sequentially covered with a ceramic matrix composite material protection layer, an aerogel layer and a thermal control paint coating; the inner wall face of the metal shell is sequentially covered with a flexible honeycomb heat insulation layer and a single-face aluminized polyester film coating layer. The aerospace craft outer shell provided by the invention has good heat resistance and heat insulation performance, can adapt to an extreme heat environment in the flight process of an aerospace craft, and effectively prevents heat from being transferred to the interior of the aircraft.

Description

Technical Field

[0001] The present disclosure relates to the field of aerospace technologies, and particularly to an outer shell of a space vehicle and a preparation method thereof. Background Art

[0002] During the mission execution of a space vehicle, its outer shell needs to withstand extremely harsh and complex environmental tests. When flying at high speed within the atmosphere, the outer shell of the vehicle rubs violently against the air, generating a high temperature of up to thousands of degrees Celsius, which poses extremely high requirements for the thermal protection performance of the vehicle's outer shell. At the same time, when passing through the atmosphere, it will also be subjected to high-speed impacts from substances such as raindrops and dust particles, which may cause damage to the surface of the outer shell. After entering space, the vehicle has to face extreme temperature variations (from extremely cold -270°C to over 120°C under direct sunlight), cosmic ray radiation, and impacts from micrometeoroids and other harsh environmental factors.

[0003] In the initial stage of the development of thermal protection technologies, resin-based composite materials (silicone resin, siloxane) were generally used to be bonded to the metal inner skin for leading-edge thermal protection. However, the temperature usage limit of silicone resin and siloxane composite materials is about 300°C. When the SR-71 flies at a high speed of Mach 3.2, the leading-edge temperature has reached 310°C, which is basically in the state of using the heat resistance limit of the material. This has forced the SR-71 to frequently replace the thermal protection materials, resulting in high maintenance costs. Moreover, due to the relatively backward thermal protection materials and heat insulation technologies at that time, the fuselage was almost a thermal structure, and only necessary thermal protection treatments were carried out at key parts. At the same time, due to poor anti-thermal expansion technology, corrugated skins were used on the aircraft surface to resist thermal expansion, and a high-emissivity thermal control coating was applied. The overall thermal protection structure had a relatively low operating temperature (not exceeding 500°C), and there were also significant problems with the reuse of materials.

[0004] With the evolution of technologies, the second-generation thermal protection structure emerged in the 1990s. At this time, the titanium alloy production technology was mature, and almost all titanium alloys were used as the outer skin, with flexible thermal protection materials used inside. However, since the structure is connected to the skin, although the flexible thermal protection materials can block radiant heat, their ability to block conductive heat is limited, and the overall heat insulation efficiency is not ideal. However, this structure has a simple design, is easy to maintain, and has a low cost. Its thermal protection effect mainly depends on the heat insulation performance of the flexible thermal protection materials.

[0005] At the beginning of this century, the third generation of thermal protection structures was formed, mainly using ceramic-based composite materials and metal honeycombs as the main materials. In this type of structure, ceramic-based composite materials are heat-resistant materials and play a partial role in heat insulation. They have the advantages of light structure and good heat insulation. However, ceramic-based composite materials have poor flexibility and are easily damaged. The gaps between ceramic tiles need to be filled with high-temperature sealants, which places extremely high demands on sealing materials. The metal thermal protection structure based on metal honeycombs fills the outer skin and the structure with flexible thermal protection materials, and uses high-temperature alloy fasteners to connect the metal honeycomb and the internal structure. The optimal thermal insulation effect is achieved by minimizing the contact points between the honeycomb and the structure. Its advantages are that the metal honeycomb has strong toughness, is not easy to break, and has a good thermal insulation effect. However, since the honeycomb core is welded to the panel, its thermal shock resistance and complex shape processing performance are poor.

[0006] At present, although the existing technology has made certain progress in the outer shell of aerospace vehicles, for example, the use environment of some materials has exceeded 1300℃, and some can even reach above 2600℃, which can meet the use of aircraft with a certain Mach number. However, there are still many shortcomings in the existing technology. On the one hand, it is difficult for existing heat-resistant materials and structures to ensure good thermal insulation performance while taking into account the flexibility, thermal shock resistance and processing performance of complex shapes of materials. On the other hand, for reusable spacecraft, the existing outer shell still has a lot of room for improvement in durability and maintenance convenience. The high maintenance cost and complex maintenance process limit the reuse efficiency of spacecraft. In addition, with the continuous development of aerospace technology, the requirements for lightweight, reliability and adaptation to more extreme thermal environments of spacecraft are getting higher and higher. The existing spacecraft outer shell technology has gradually been unable to meet these increasingly stringent requirements. Therefore, developing a new type of outer shell of aerospace vehicles to overcome the above-mentioned defects in the existing technology has become an important issue to be solved in the current aerospace field. Summary of the invention

[0007] The purpose of the present disclosure is to provide an outer shell of a spacecraft, which has good heat resistance and heat insulation properties, can adapt to the extreme thermal environment of the spacecraft during flight, and effectively prevent heat from being transferred to the interior of the aircraft.

[0008] In a first aspect, the present disclosure provides an outer shell of a spacecraft, comprising a cylindrical metal shell, the outer wall surface of which is sequentially covered with a ceramic-based composite material protective layer, an aerogel layer, and a thermal control paint coating; the inner wall surface of the metal shell is sequentially covered with a flexible honeycomb insulation layer and a single-sided aluminum-plated polyester coating layer.

[0009] Furthermore, both the ceramic matrix composite material protective layer and the flexible honeycomb heat insulation layer are attached to the surface of the metal shell through an inorganic binder; wherein, the inorganic binder is selected from one of phosphate binders, silicate binders, and oxide binders. The inorganic binder has the characteristics of high temperature resistance, strong adhesiveness, and stable properties, and can firmly bond the ceramic matrix composite material protective layer to the surface of the metal shell.

[0010] Furthermore, the single-sided aluminized polyester film layer is attached to the surface of the flexible honeycomb heat insulation layer through a high-temperature resistant organic binder; wherein, the high-temperature resistant organic binder is selected from one of polybenzothiazole binders, polybenzimidazole binders, and polysiloxane binders. Using a high-temperature resistant organic binder to bond the single-sided aluminized polyester film can avoid the problem of poor adhesion caused by the decrease in the viscosity of the binder at high temperatures.

[0011] Furthermore, the framework of the flexible honeycomb heat insulation layer is a carbon framework honeycomb, and the carbon framework honeycomb is filled with silica aerogel. The processing performance and thermal shock resistance of the carbon framework honeycomb are better than those of the metal honeycomb. The filled porous silica aerogel has an extremely low thermal conductivity, blocking the thermal radiation between the honeycomb pores at high temperatures, thus further improving the heat insulation performance of the honeycomb material.

[0012] Furthermore, the aerogel layer is one of alumina aerogel, silica aerogel, and zirconia aerogel. Such inorganic aerogels have good adhesiveness, and the surface of the ceramic matrix composite material has numerous micro-pores and defects with a relatively high roughness. Therefore, after the inorganic gel is coated, it can firmly adhere to the surface of the ceramic matrix composite material, so there is a strong bonding force between the formed aerogel layer and the ceramic matrix composite material without the need for other adhesives.

[0013] Furthermore, the aerogel layer contains 10 - 25 wt% of fiber materials, and the fiber materials include one of carbon fibers, polyimide fibers, silicon carbide fibers, silicon carbon oxide fibers, alumina fibers, and zirconia fibers.

[0014] The addition of fiber materials can enhance the aerogel framework, improve the flexibility of the aerogel, and enhance its structural stability, preventing the aerogel from collapsing or deforming under high temperature, low temperature, or other harsh environmental conditions. In addition, the added fibers can improve the internal heat conduction path of the aerogel without reducing its heat insulation performance, making the heat insulation effect of the aerogel more excellent.

[0015] Further, 1-4 wt% of colloidal silica is added to the thermal control paint. Colloidal silica has polar groups, which can form physical adsorption or chemical bonding with atoms or molecules on the surface of the object to be coated. At the same time, it can also interact with components such as resin in the paint spray, reduce the surface tension, improve the surface energy, enable the paint spray to better wet and spread on the surface of the object to be coated, and thus improve the adhesion.

[0016] The second aspect of the present disclosure provides a preparation method for the outer shell of a space vehicle, including the following steps:

[0017] S1. Coat an inorganic binder on the inner and outer surfaces of the metal shell, and then attach a ceramic matrix composite material to the outer surface of the metal shell to obtain a ceramic matrix composite material protective layer; attach a flexible honeycomb panel to the inner surface of the metal shell to obtain a flexible honeycomb heat insulation layer;

[0018] S2. Coat a high-temperature resistant organic binder on the surface of the flexible honeycomb heat insulation layer, and then attach a single-sided aluminized polyester film to the surface of the flexible honeycomb heat insulation layer to obtain a single-sided aluminized polyester film laminated layer;

[0019] S3. Fix the metal shell on a spraying device;

[0020] S4. Spray an inorganic gel on the surface of the ceramic matrix composite material protective layer, and obtain an aerogel layer after drying;

[0021] S5. Spray the thermal control paint on the surface of the gel layer, and obtain a thermal control paint coating after thermal curing.

[0022] Further, in step S1, the flexible honeycomb panel is obtained by impregnating a carbon skeleton honeycomb in a silica gel and drying.

[0023] In the present disclosure, by impregnating the carbon skeleton honeycomb in the silica gel, the silica gel fills the pores of the honeycomb, further improving the heat insulation performance of the honeycomb material.

[0024] Further, in step S3, the spraying device includes a frame, a rotating tailstock, a moving seat, a first rotating fixing seat, and a second rotating fixing seat;

[0025] The rotating tailstock is arranged at one end of the frame, and it includes a support seat, a rotating shaft horizontally arranged on the support seat, and a rotating table fixed on the rotating shaft. The rotating table has two mutually perpendicular table surfaces;

[0026] The first rotating fixing seat and the second rotating fixing seat are respectively arranged on the two table surfaces of the rotating table, and both of them include a chuck and a support rod; wherein the support rod is vertically installed on the table surface, the chuck is rotatably arranged on the table surface, and the chuck and the support rod are coaxially arranged;

[0027] The moving seat is arranged at the other end of the frame and is used to support the rod of the first rotary fixing seat.

[0028] The above spraying equipment can be vertical or horizontal. For the outer shell of a space vehicle with a shorter length, it can be fixed on the second rotary fixing seat in a vertical manner; while for the outer shell of a space vehicle with a longer length, it can be fixed on the first rotary fixing seat in a horizontal manner. Therefore, it is convenient for the spraying process of the outer shells of space vehicles with different lengths.

[0029] Further, the moving seat includes a lead screw slider module and a movable seat. The movable seat is installed on the slider of the lead screw slider module, and a pair of runners are arranged on the movable seat. Among them, the rod of the first rotary fixing seat is supported between the pair of runners.

[0030] In the present disclosure, by setting the lead screw slider module, the position of the movable seat on the frame can be adjusted very conveniently, so that when the metal shell is in a horizontal state, the movable seat can better support the rod.

[0031] Further, a plurality of universal wheels are arranged at the bottom of the frame, so that the spraying equipment can be moved conveniently through these universal wheels.

[0032] Further, in step S4, the inorganic gel is one of alumina gel, silica gel, and zirconia gel.

[0033] In the present disclosure, alumina gel, silica gel, and zirconia gel can all form aerogel materials with high porosity after drying, and have good heat insulation performance.

[0034] Further, 10-25 wt% of fiber materials are added to the inorganic gel, and the fiber materials include one of carbon fiber, polyimide fiber, silicon carbide fiber, silicon oxycarbide fiber, alumina fiber, and zirconia fiber.

[0035] In the present disclosure, adding fiber materials to the aerogel can play a role in strengthening the aerogel skeleton, improving the flexibility of the aerogel, enhancing its structural stability, and preventing the aerogel from collapsing or deforming under high temperature, low temperature or other harsh environmental conditions. In addition, the added fibers can improve the internal heat conduction path of the aerogel without reducing its heat insulation performance, making the heat insulation effect of the aerogel more excellent.

[0036] The present disclosure can at least achieve the following technical effects:

[0037] 1. In the outer shell of the aerospace vehicle of the present disclosure, an inorganic gel material is coated on the surface of the ceramic matrix composite protection layer. The inorganic gel material can penetrate into the gaps between the ceramic tiles and form an aerogel layer after drying. Since the inorganic gel has good adhesiveness, and the surface of the ceramic matrix composite has numerous micro-pores and defects and a relatively high roughness, the inorganic gel can firmly adhere to the surface of the ceramic matrix composite after coating. Therefore, the formed aerogel layer has a very strong bonding force with the ceramic matrix composite without the need for other adhesives. Moreover, the introduction of the aerogel layer significantly improves the heat insulation performance of the overall material.

[0038] 2. In the outer shell of the aerospace vehicle of the present disclosure, 1-4% of colloidal silica is added to the thermal control paint. The colloidal silica has polar groups, can form physical adsorption or chemical bonding with atoms or molecules on the surface of the object to be coated, and can also interact with components such as resins in the spray paint, reduce the surface tension, improve the surface energy, enable the spray paint to better wet and spread on the surface of the object to be coated, and thus improve the adhesion of the thermal control paint on the aerogel layer.

[0039] 3. The outer shell of the aerospace vehicle provided by the present disclosure has good heat resistance and heat insulation performance, can adapt to the extreme thermal environment during the flight of the aerospace vehicle, and effectively prevents heat from being transferred to the interior of the vehicle.

[0040] 4. The spraying equipment adopted in the present disclosure can be vertical or horizontal. For the outer shell of the aerospace vehicle with a shorter length, it can be fixed in a vertical manner; for the outer shell of the aerospace vehicle with a longer length, it can be fixed in a horizontal manner. Therefore, this spraying equipment is convenient for the spraying process of the outer shells of aerospace vehicles with different lengths. Description of the Drawings

[0041] Figure 1 is a schematic external view of the outer shell of the aerospace vehicle in the present disclosure;

[0042] Figure 2 is a schematic cross-sectional view of the outer shell of the aerospace vehicle in the present disclosure;

[0043] Figure 3 is a schematic structural view of the spraying equipment in the present disclosure;

[0044] Figure 4 is a schematic structural view of the rotating tailstock in the spraying equipment;

[0045] Figure 5 is a schematic structural view of the chuck in the spraying equipment;

[0046] Figure 6 is a schematic structural view of the moving seat in the spraying equipment;

[0047] Figure 7 Schematic diagram of installing the outer shell of a space vehicle onto a spraying device;

[0048] Description of reference numerals in the figure: 100, outer shell of the space vehicle; 110, metal outer shell; 120, ceramic matrix composite protection layer; 130, aerogel layer; 140, thermal control paint coating; 150, flexible honeycomb insulation layer; 160, single-sided aluminized polyester film coating layer;

[0049] 200, spraying device; 210, frame; 220, rotating tailstock; 221, support seat; 222, rotating shaft; 223, rotating table; 230, first rotating fixing seat; 231, chuck; 2311, disc body; 2312, jaws; 2313, handle; 232, support rod; 240, second rotating fixing seat; 250, moving seat; 251, screw slider module; 252, movable seat; 253, runner. Specific implementation manner

[0050] Next, the technical solutions of the present disclosure will be clearly and completely described in conjunction with the accompanying drawings and specific implementation manners. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present disclosure.

[0051] As shown in the attached Figure 1-2 figure, the present disclosure provides an outer shell of a space vehicle, including a metal outer shell 110 in a cylindrical shape. The outer wall surface of the metal outer shell 110 is sequentially covered with a ceramic matrix composite protection layer 120, an aerogel layer 130, and a thermal control paint coating 140; the inner wall surface of the metal outer shell 110 is sequentially covered with a flexible honeycomb insulation layer 150 and a single-sided aluminized polyester film coating layer 160.

[0052] In the present disclosure, the space vehicle can be various space flight devices, including but not limited to airplanes, satellites, rockets, missiles, etc. The metal outer shell 110 of the space vehicle is generally prepared from lightweight and high-strength metal materials, such as aluminum alloy, titanium alloy, etc.

[0053] When a spacecraft flies within the atmosphere, its outer shell rubs violently against the air, generating extremely high temperatures of up to several thousand degrees Celsius. Therefore, materials that can withstand extreme high temperatures, resist oxidation and corrosion are needed to protect the shell. Ceramic matrix composites are a type of composite material composed of a ceramic matrix and various fibers, with excellent properties such as high temperature resistance, high strength and stiffness, relatively light weight, oxidation resistance, and corrosion resistance, and can be used for a long time at high temperatures of 1200 - 1600 °C. Therefore, covering the outer wall surface of the metal shell 110 with ceramic matrix composites can still maintain its original state under extreme high temperatures, thus playing a very good protective role for the spacecraft shell 100.

[0054] In the present disclosure, the ceramic matrix composite protective layer 120 is attached to the surface of the metal shell 110 through an inorganic binder. The inorganic binder has the characteristics of high temperature resistance, strong adhesiveness, and stable properties, and can firmly bond the ceramic matrix composite protective layer 120 to the surface of the metal shell 110. Among them, the inorganic binder can be selected from one of phosphate binders, silicate binders, and oxide binders.

[0055] Although ceramic matrix composites have the characteristic of withstanding extreme high temperatures, they have poor flexibility and are prone to breakage. Therefore, the gaps between the ceramic tiles need to be filled with a high-temperature sealant, which has extremely high requirements for the sealing material. In the present disclosure, an inorganic gel material is coated on the surface of the ceramic matrix composite protective layer 120. The inorganic gel material can penetrate into the gaps between the ceramic tiles and form an aerogel layer 130 after drying. Since the inorganic gel has good adhesiveness, and the surface of the ceramic matrix composite has numerous micro-pores and defects and a high roughness, the inorganic gel can firmly adhere to the surface of the ceramic matrix composite after coating. Therefore, the formed aerogel layer 130 has a strong bonding force with the ceramic matrix composite without the need for other adhesives.

[0056] Aerogels have an extremely low thermal conductivity, much lower than that of most ceramic matrix composites. Adding an aerogel layer 130 on the surface of the ceramic matrix composite is equivalent to adding an efficient thermal resistance barrier, which can effectively block the heat transfer by conduction and greatly improve the heat insulation performance of the overall material. Moreover, the aerogel layer 130 can fill the micro-pores and defects on the surface of the ceramic matrix composite, eliminating the weak links of heat transfer, making it difficult for heat to penetrate into the interior of the ceramic matrix composite through these defects, thereby improving the overall heat insulation effect.

[0057] In the present disclosure, the inorganic gel can be alumina gel, silica gel, zirconia gel, etc., and preferably alumina gel.

[0058] In some embodiments of the present disclosure, the aerogel layer 130 further contains 10-25 wt% of fiber materials, and the fiber materials include, but are not limited to, one of carbon fiber, polyimide fiber, silicon carbide fiber, silicon oxycarbide fiber, alumina fiber, and zirconia fiber. The addition of the fiber materials can enhance the aerogel skeleton, improve the flexibility of the aerogel, increase its structural stability, and prevent the aerogel from collapsing or deforming under high temperature, low temperature, or other harsh environmental conditions. Additionally, the added fibers can improve the internal heat conduction path of the aerogel without reducing its heat insulation performance, making the heat insulation effect of the aerogel more excellent.

[0059] In the present disclosure, the fiber materials can be added to the reaction raw materials of the inorganic gel, and the fiber materials can be dispersed evenly by stirring or adding a dispersant, and then the reaction conditions are controlled to form the inorganic gel, so that the fiber materials can be more evenly distributed in the gel.

[0060] In the present disclosure, the length of the fiber materials is generally controlled between 1 and 100 μm, and the diameter is generally controlled between 1 and 100 nm.

[0061] The aerogel has a nano-porous structure, making its texture relatively fragile and easily damaged by mechanical external forces such as scratching and collision. Surface protection can form a protective film on the surface of the aerogel, enhance its ability to resist mechanical damage, and maintain the structural integrity and performance stability of the aerogel. In the present disclosure, forming a thermal control paint coating 140 on the surface of the aerogel layer 130 plays a good protective role for the aerogel layer 130, thereby being able to extend the service life of the aerogel layer 130 and avoid a reduction in heat insulation performance. Additionally, the thermal control paint can increase the radiation and reflection of heat, reduce the intake and conduction of heat, and thus further improve the heat insulation effect.

[0062] In the present disclosure, functional components can be added to the thermal control paint, so that the spacecraft has corresponding functions. For example, in some embodiments, components with the function of absorbing radar waves, such as ferrite, can be added to the thermal control paint. After coating the spacecraft with this thermal control paint, the spacecraft can have the function of radar stealth.

[0063] Due to the high porosity of the surface of the aerogel layer 130, when directly spraying the thermal control paint on the surface of the aerogel layer 130, the paint film is prone to crack and peel. To avoid this problem, the aerogel layer 130 can be polished or sprayed multiple times before painting. In the selection of the resin matrix of the thermal control paint, preferably, resin matrices such as epoxy resin and polyurethane are used, and these resins can form chemical bonds with the hydroxyl groups on the surface of the aerogel, and the bonding force is relatively strong.

[0064] In addition, in some embodiments, 1-4% of colloidal silica can be added to the thermal control paint. Colloidal silica has polar groups, which can form physical adsorption or chemical bonding with atoms or molecules on the surface of the object to be coated. At the same time, it can also interact with components such as resins in the spray paint, reduce the surface tension, improve the surface energy, enable the spray paint to better wet and spread on the surface of the object to be coated, and thus improve the adhesion.

[0065] In the present disclosure, a flexible honeycomb heat insulation layer 150 is further covered on the inner wall surface of the metal housing 110. The flexible honeycomb heat insulation layer 150 is attached to the surface of the metal housing 110 through an inorganic binder. The flexible honeycomb heat insulation layer 150 has good heat insulation performance, can further reduce the heat transfer between the inside and outside of the aircraft, and ensures the stability of the temperature inside the aircraft.

[0066] Honeycomb material is a sandwich structure composite material. The core layer is composed of cell grids in the shapes of hexagons, quadrilaterals, etc., similar to a honeycomb, and the upper and lower surfaces are bonded or brazed with thinner panels. Honeycomb materials have high stiffness, specific strength, and specific stiffness, are lightweight, and the cell grids are filled with air, making them have good heat insulation and sound insulation performance. At present, metal thermal protection structures mainly based on metal honeycombs (such as aluminum honeycombs) are widely used in aerospace. Its advantages are that the metal honeycomb has strong toughness, is not easily damaged, and has good heat insulation effect. However, due to the welding of the honeycomb core and the panel, its thermal shock resistance and complex shape processing performance are poor.

[0067] In the present disclosure, the honeycomb material adopts a flexible honeycomb material. Specifically, the flexible honeycomb material is a carbon skeleton honeycomb. The carbon skeleton honeycomb can be composed of carbon fiber or its fabric-reinforced carbon matrix, and its processing performance and thermal shock resistance are better than those of metal honeycombs. Moreover, the carbon skeleton honeycomb in the present disclosure is filled with silica aerogel. These porous aerogels have extremely low thermal conductivity, blocking the thermal radiation between the honeycomb pores at high temperatures, and thus further improving the adiabatic performance of the honeycomb material.

[0068] In the present disclosure, the carbon skeleton honeycomb can be impregnated in silica gel, so that the silica gel fills the pores of the honeycomb, and the carbon skeleton honeycomb material filled with silica aerogel can be obtained after drying.

[0069] Furthermore, a single-sided aluminized polyester film layer 160 is also attached to the surface of the flexible honeycomb heat insulation layer 150. The single-sided aluminized polyester film layer 160 can be a PET film or a polyimide film (PI), and the aluminized layer faces the inside of the aircraft. The polyester film itself is a poor conductor of heat and has a certain heat insulation ability. The aluminized layer further enhances its barrier effect on heat conduction, making it difficult for heat to be transferred from one side to the other through the single-sided aluminized polyester, and can effectively delay the heat transfer speed inside the aircraft and improve the heat insulation effect.

[0070] In the present disclosure, the single-sided aluminized polyester film is adhered to the surface of the flexible honeycomb thermal insulation layer 150 by means of a high-temperature resistant organic binder, and the high-temperature resistant organic binder is preferably selected from one of polybenzothiazole binder, polybenzimidazole binder, and polysiloxane binder.

[0071] The second aspect of the present disclosure provides a method for preparing an outer shell of a space vehicle, comprising the following steps:

[0072] S1. Coating an inorganic binder on the inner and outer surfaces of the metal shell 110, and then attaching a ceramic matrix composite material to the outer surface of the metal shell 110 to obtain a ceramic matrix composite material protective layer 120; attaching a flexible honeycomb panel to the inner surface of the metal shell 110 to obtain a flexible honeycomb thermal insulation layer 150;

[0073] S2. Coating a high-temperature resistant organic binder on the surface of the flexible honeycomb thermal insulation layer 150, and then attaching a single-sided aluminized polyester film to the surface of the flexible honeycomb thermal insulation layer 150 to obtain a single-sided aluminized polyester film coating layer 160;

[0074] S3. Fixing the metal shell 110 on the spraying device 200;

[0075] S4. Uniformly spraying an inorganic gel on the surface of the ceramic matrix composite material protective layer 120, and drying to obtain an aerogel layer 130;

[0076] S5. Spraying a thermal control paint on the surface of the gel layer, and obtaining a thermal control paint coating layer 140 after thermal curing.

[0077] For the spraying process of the outer shell of the space vehicle, the present disclosure designs a spraying device 200, which can fix the outer shell of the space vehicle in both vertical and horizontal states, so it can be applicable to outer shells of space vehicles with different lengths, facilitating the spraying process.

[0078] Please refer to Figure 3-4 , the spraying device 200 provided by the present disclosure includes a frame 210, a rotating tailstock 220, a first rotating fixing seat 230, a second rotating fixing seat 240, and a moving seat 250. Among them, the rotating tailstock 220 is arranged at one end of the frame 210, which includes a support seat 221, a horizontal rotating shaft 222 is provided on the support seat 221, and a rotating table 223 is fixed on the rotating shaft 222, and the rotating table 223 can rotate around the rotating shaft 222 in a vertical plane. The rotating table 223 has two mutually perpendicular table surfaces; in a preferred embodiment, the rotating table 223 is in a cubic shape.

[0079] Please refer to Figure 3, the first rotary fixing seat 230 and the second rotary fixing seat 240 are respectively arranged on two surfaces of the rotary table 223, and both of them include a chuck 231 and a support rod 232. Among them, the support rod 232 is vertically fixed on the said table surface, the chuck 231 is rotatably arranged on the corresponding table surface, and the support rod 232 and the chuck 231 are coaxially arranged.

[0080] Please refer to Figure 5 , the chuck 231 is used to install the metal shell 110 on the rotary table 223, and it includes a disk body 2311 and a plurality of claws 2312 installed on the disk body 2311. The plurality of claws 2312 are preferably evenly distributed along the circumferential direction of the disk body 2311. The claws 2312 can move along the radial direction of the disk body 2311 and abut against the inner wall surface of the metal shell 110, so as to realize the fixation of the metal shell 110. This chuck 231 can be applicable to the clamping of metal shells 110 of different sizes, and has better versatility.

[0081] In some embodiments of the present disclosure, a pair of handles 2313 are also installed on the back surface of the disk body 2311. By rotating the handles 2313, the chuck 231 can be driven to rotate, and then the metal shell 110 can be rotated around its axis. Therefore, the spraying device of the present disclosure can realize continuous spraying on the surface of the metal shell 110 by manually rotating the handles 2313, thus replacing the motor rotating components, which not only simplifies the structure of the device, but also can meet the usage restrictions of electrical components during the production and processing of aerospace vehicles.

[0082] The moving seat 250 is arranged at the other end of the frame 210 and is used to support the support rod 232 of the first rotary fixing seat 230. Please refer to Figure 6 , in some embodiments of the present disclosure, the moving seat 250 includes a lead screw slider module 251 and a movable seat 252, wherein the movable seat 252 is installed on the slider of the lead screw slider module 251. By rotating the lead screw slider module 251, the movable seat 252 can be driven to move on the frame 210, so the movable seat 252 can be applicable to aerospace vehicle outer shells of different lengths.

[0083] In some embodiments of the present disclosure, a pair of rotating wheels 253 are provided on the movable seat 252, and the rotating wheels 253 can be bearings. The support rod 232 of the first rotary fixing seat 230 is supported between the pair of rotating wheels 253. By using the pair of rotating wheels 253 to support the support rod 232, the friction between the support rod 232 and the movable seat 252 can be reduced, making the rotation of the aerospace vehicle outer shell smoother.

[0084] Please refer to Figure 3, in the present disclosure, the support rod 232 of the first rotary fixing seat 230 is in a horizontal state, and the support rod 232 of the second rotary fixing seat 240 is in a vertical state, which can respectively fix the outer shell of the spacecraft in a horizontal state and a vertical state on the frame. It should be noted that since the first rotary fixing seat 230 and the second rotary fixing seat 240 are relatively heavy, while the outer shell of the spacecraft to be sprayed is relatively light, therefore, by supporting the first rotary fixing seat 230 with the moving seat 250, the first rotary fixing seat 230 and the second rotary fixing seat 240 can maintain good stability and will not tip over due to rotation.

[0085] In some embodiments of the present disclosure, a plurality of universal wheels (not shown in the figure) are installed at the bottom of the frame, so that the spraying device can be conveniently moved through these universal wheels.

[0086] Please refer to Figure 7 , the spraying device 200 provided by the present disclosure can be upright or lying. For the outer shell of the spacecraft with a shorter length, it can be fixed in an upright manner; while for the outer shell of the spacecraft with a longer length, it can be fixed in a horizontal manner. Therefore, the spraying device is convenient for spraying and processing the outer shells of spacecraft with different lengths.

[0087] In summary, although the present disclosure has been disclosed above with preferred embodiments, the above preferred embodiments are not intended to limit the present disclosure. Those of ordinary skill in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the protection scope of the present disclosure is subject to the scope defined by the claims.

Claims

1. An outer shell of a spacecraft, characterized in that, It includes a cylindrical metal shell, and the outer wall surface of the metal shell is successively covered with a ceramic matrix composite material protective layer, an aerogel layer, and a thermal control paint coating; the inner wall surface of the metal shell is successively covered with a flexible honeycomb heat insulation layer and a single-sided aluminized polyester film coating layer.

2. The outer casing of a space vehicle as claimed in claim 1, characterized in that, The ceramic matrix composite material protective layer and the flexible honeycomb heat insulation layer are both attached to the surface of the metal shell through an inorganic binder; the single-sided aluminized polyester film coating layer is attached to the surface of the flexible honeycomb heat insulation layer through a high-temperature resistant organic binder; Wherein, the inorganic binder is selected from one of phosphate binders, silicate binders, and oxide binders; the high-temperature resistant organic binder is selected from one of polybenzothiazole binders, polybenzimidazole binders, and polysiloxane binders.

3. The outer casing of a spacecraft as claimed in claim 1, characterized in that, The framework of the flexible honeycomb heat insulation layer is a carbon framework honeycomb, and the carbon framework honeycomb is filled with silica aerogel.

4. The outer shell of a space vehicle as claimed in claim 1, wherein The aerogel layer is one of alumina aerogel, silica aerogel, and zirconia aerogel; and / or, The aerogel layer contains 10 - 25 wt% of fiber materials, and the fiber materials include at least one of carbon fiber, polyimide fiber, silicon carbide fiber, silicon oxycarbide fiber, alumina fiber, and zirconia fiber.

5. The outer shell of a space vehicle as claimed in claim 1, wherein, 1 - 4 wt% of colloidal silica is added to the thermal control paint.

6. A preparation method of the outer shell of a space vehicle as described in claim 1, characterized in that, It includes the following steps: S1. Apply an inorganic binder on the inner and outer surfaces of the metal shell, and then attach a ceramic matrix composite material to the outer surface of the metal shell to obtain a ceramic matrix composite material protective layer; attach a flexible honeycomb board to the inner surface of the metal shell to obtain a flexible honeycomb heat insulation layer; S2. Apply a high-temperature resistant organic binder on the surface of the flexible honeycomb heat insulation layer, and then attach a single-sided aluminized polyester film to the surface of the flexible honeycomb heat insulation layer to obtain a single-sided aluminized polyester film coating layer; S3. Fix the metal shell on a spraying device; S4. Spray an inorganic gel on the surface of the ceramic matrix composite material protective layer, and obtain an aerogel layer after drying; S5. Spray a thermal control paint on the surface of the aerogel layer, and obtain a thermal control paint coating after thermal curing.

7. The preparation method of the outer shell of the aerospace vehicle according to claim 6, characterized in that, In step S1, the flexible honeycomb board is obtained by impregnating a carbon framework honeycomb in silica gel and drying.

8. The preparation method of the outer shell of the aerospace vehicle according to claim 6, characterized in that, In step S3, the spraying device includes a frame, a rotating tailstock, a moving seat, a first rotating fixing seat, and a second rotating fixing seat; The rotating tailstock is arranged at one end of the frame, and it includes a support seat, a rotating shaft horizontally arranged on the support seat, and a rotating table fixed on the rotating shaft. The rotating table has two mutually perpendicular table surfaces; The first rotating fixing seat and the second rotating fixing seat are respectively arranged on the two table surfaces of the rotating table, and both of them include a chuck and a support rod; wherein the support rod is vertically installed on the table surface, the chuck is rotatably arranged on the table surface, and the chuck and the support rod are coaxially arranged; The moving seat is arranged at the other end of the frame and is used to support the support rod of the first rotating fixing seat.

9. The preparation method of the outer casing of the aerospace vehicle according to claim 8, characterized in that, The moving seat includes a screw rod slider module and a movable seat. The movable seat is installed on the slider of the screw rod slider module, and a pair of rotating wheels are arranged on the movable seat; Among them, the strut of the first rotary fixing seat is supported between the pair of runners.

10. The preparation method of the outer shell of the aerospace vehicle according to claim 6, characterized in that, In step S4, the inorganic gel is one of alumina gel, silica gel, and zirconia gel; and / or, 10-25 wt% of a fiber material is added to the inorganic gel, and the fiber material includes one of carbon fiber, polyimide fiber, silicon carbide fiber, silicon oxycarbide fiber, alumina fiber, and zirconia fiber.

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