An in-situ forming / fitting integrated method of a fiber reinforced thermal protection structure

Abstract

This invention relates to an in-situ molding / assembly integrated method for fiber-reinforced thermal protection structures, solving the assembly problem of thermal protection materials at curved and irregularly shaped structures, simplifying the assembly process of thermal protection structures, and ensuring the consistency, integrity, and quality stability of thermal protection material bonding. The method includes the following steps: coating the cleaned surface of the structural support with a high-temperature resistant adhesive; covering the fiber preform with the adhesive, forming a connection with the main support structure, and allowing it to stand for the adhesive to cure; designing an outer metal mold with the support structure as the inner mold; assembling the outer and inner metal molds, and placing the support structure with the bonded fiber preform into the metal mold; injecting resin sol into the mold using an RTM process; placing the mold in an oven for a sol-gel curing reaction; after curing, opening the mold and allowing the cured fiber-reinforced thermal insulation composite material to undergo a solvent drying process under normal pressure using a gradient heating method.

Description

Technical Field

[0001] This invention belongs to the field of thermal protection structure preparation and assembly for aerospace products, specifically relating to an in-situ molding / assembly integrated method for fiber-reinforced thermal insulation composite materials. Background Technology

[0002] Aerospace products travel at extremely high speeds within the atmosphere, generating significant aerodynamic heat through intense friction with the air. Therefore, thermal protection structures are necessary to ensure the stability of the internal components. Currently, large thermal protection areas on the outer surface of these products are typically bonded to the surface using splicing or interlocking methods. This bonding process is complex, lacks stability, and struggles to guarantee bonding quality. Furthermore, it is difficult to implement in complex structures, thus limiting the structural design of these products. Summary of the Invention

[0003] This invention proposes an in-situ molding / assembly integrated method for fiber-reinforced thermal protection structures, which realizes the integrated manufacturing and assembly of complex irregular load-bearing structures and thermal protection structures. It solves the assembly problem of thermal protection materials at curved irregular structures, simplifies the assembly process of thermal protection structures, and ensures the consistency, integrity and quality stability of thermal protection material bonding, thereby achieving the goal of high-performance manufacturing.

[0004] This invention is achieved through the following technical solutions:

[0005] An in-situ molding / assembly integrated method for fiber-reinforced thermal protection structures includes the following steps:

[0006] 1) The surface of the structural support is sanded or polished to increase the surface roughness, and then the surface is cleaned with alcohols or ketones to enhance the surface adhesion.

[0007] 2) Apply a high-temperature resistant adhesive to the cleaned surface of the structural support;

[0008] 3) Cover the fiber preform with the adhesive to form a connection with the main load-bearing structure, and let it stand for 24-48 hours to allow the adhesive to cure completely;

[0009] 4) Using the load-bearing structure as the inner mold, and depending on the structural shape of the manufactured product and the strength of the load-bearing structure itself, an inner membrane reinforcement structure may be added as appropriate.

[0010] 5) Design the external metal mold, the elements of which include: the product conformal surface structure, the mold sealing structure, the RTM process injection and dispensing port and bolt fastening holes. Assemble the metal mold with matching bolts, and use two ball valves respectively to assemble the injection port and dispensing port. Use PTFE tape to prevent leakage at the interface.

[0011] Assemble the outer metal mold and the inner mold, and place the load-bearing structure of the bonded fiber preform into the metal mold;

[0012] 6) Inject the resin sol into the mold using the RTM process. After no more air bubbles flow out of the outlet, continue to inject the sol under pressure for 10-20 minutes to ensure that the sol fully impregnates the fiber preform.

[0013] 7) Place the mold in an oven at 80-120℃ for 24-48 hours for a sol-gel curing reaction.

[0014] 8) After curing, open the mold and perform solvent drying on the cured fiber-reinforced heat-insulating composite material under normal pressure with a gradient temperature increase. That is, first perform the drying process in a ventilated place at room temperature for 24-36 hours, then perform the drying process in an oven at 50-60℃ for 24-48 hours, and finally perform the drying process in an oven at 90-120℃ for 24-48 hours to ensure the integrity of the surface and internal structure of the component.

[0015] The load-bearing structure is made of aluminum alloy and the fiber preform is impregnated with a resin sol with a viscosity of 360 cps at 25°C using the RTM process.

[0016] The load-bearing structure is made of titanium alloy, and the fiber preform is impregnated with resin sol with a viscosity of 100 cps at 25°C using the RTM process.

[0017] The load-bearing structure is a carbon fiber reinforced bismaleimide resin composite material, in which a resin sol with a viscosity of 100 cps at 25°C is used to impregnate the fiber preform using an RTM process.

[0018] The load-bearing structure is a carbon fiber reinforced polyimide composite material, and the fiber preform is impregnated with a resin sol with a viscosity of 150 cps at 25°C using an RTM process.

[0019] The load-bearing structure is a carbon fiber reinforced epoxy resin composite material, and the fiber preform is impregnated with a resin sol with a viscosity of 80 cps at 25°C using an RTM process.

[0020] The load-bearing structure is a carbon fiber reinforced epoxy resin composite material, and the fiber preform is impregnated with a resin sol with a viscosity of 80 cps at 25°C using an RTM process.

[0021] The supporting structure is a cylindrical metal, and the fiber preform is impregnated with a resin sol with a viscosity of 120 cps at 25°C using the RTM process.

[0022] The supporting structure is a cylindrical carbon fiber reinforced polyimide composite material. A soluble reinforcing structure is used as the reinforcing core of the inner cylinder mold, and its surface is waterproofed. It is placed inside the cylinder, and the cylindrical structure is placed in a conformal metal mold. The fiber preform is impregnated with a resin sol with a viscosity of 170 cps at 25°C using the RTM process. The mold is then sealed and placed in an oven for curing. The mold is then opened, the composite material is removed and dried under normal pressure, and the waterproof structure of the inner core of the reinforcing structure is destroyed. The inner core structure of the reinforcing structure is then dissolved using a solvent.

[0023] The fiber preform consists of a quartz fiber mesh and fiber cloth, and is prepared using needle punching technology.

[0024] This invention breaks through the integrated manufacturing technology of complex irregular load-bearing structures and thermal protection structures, overcoming the limitations of traditional "step-by-step molding + bonding" processes. It can be applied to the manufacturing of thermal protection layers in complex structural parts of products, solving problems such as difficult assembly operations between thermal protection layers and structural layers, effectively simplifying the assembly process of thermal protection structures, improving the assembly reliability of thermal protection structures, achieving high-performance manufacturing goals, realizing the manufacturing coupling of thermal protection and load-bearing structures, reducing product manufacturing costs, and improving product manufacturing quality. Attached Figure Description

[0025] Figure 1 Schematic diagram of the interface connection between the load-bearing structure and the fiber precast body;

[0026] Figure 2 Mold assembly diagram;

[0027] Figure 3 Sol-RTM process;

[0028] Figure 4 Sol-gel curing process of composite materials;

[0029] Figure 5 Schematic diagram of the atmospheric pressure drying process of composite materials. Detailed Implementation

[0030] This invention develops an integrated in-situ molding / assembly method for fiber-reinforced heat-insulating / protective composite materials by coordinating the fiber preform molding process, the heat-protective structure molding process, and the bonding process. This allows the heat-protective structure to be fully assembled immediately after molding. It breaks away from the traditional step-by-step model of manufacturing heat-protective structures first and then bonding, simplifying the manufacturing process, improving production efficiency and quality stability, and achieving high-performance manufacturing goals.

[0031] Reference Appendix Figures 1-5 The invention will be further described in detail with reference to the implementation examples.

[0032] Figure 1Flowchart of process design for pre-connection of the load-bearing fiber preform interface;

[0033] Figure 2 The diagram shown is a schematic of the mold assembly installation in this invention. During the process, it is necessary to ensure that the outer mold fits well with the surface of the fiber preform to avoid fiber wrinkles, fiber indentations and other phenomena.

[0034] Figure 3 The diagram illustrates the sol-RTM process, which involves injecting the sol into the mold using a gradient pressurization method. First, a low-pressure approach is used to eliminate large voids between the fibers and the mold, followed by a high-pressure approach to eliminate micro-voids within the fiber preform, ensuring thorough impregnation of the fiber preform by the sol. This method also avoids damage to the morphology of the fiber preform caused by excessively high initial pressure.

[0035] Figure 4 The image shows the sol-gel curing process of fiber-reinforced heat-insulating / insulating composite material. This process requires ensuring good mold sealing to prevent the internal pressure from rising due to temperature increase and solvent vaporization, which could cause the reaction system to fail to seal.

[0036] Figure 5 This is a schematic diagram of the atmospheric pressure drying process of the cured fiber-reinforced heat-insulating composite material. The drying fixture structure is designed according to the shape and structure of the component to avoid the capillary effect during solvent drying, which may cause the component's dimensional deviation to exceed the tolerance. After drying, the "load-bearing and heat-insulating structure in-situ forming / assembly integrated" component is obtained, achieving the purpose of forming and assembling the heat protection structure.

[0037] Example:

[0038] 1) An aluminum alloy load-bearing structure, measuring 220mm*220mm*8mm, is used. A high-temperature resistant adhesive is coated on its surface, and a quartz fiber mesh and fiber cloth are bonded to it. The structure is prepared using needle-punching technology to achieve a density of 0.45g / cm³. 3 A 10mm thick fiber preform was placed in a metal mold. The fiber preform was then impregnated with a resin sol with a viscosity of 360cps at 25°C using an RTM process. The mold was then sealed and placed in a 110°C oven for a 48-hour curing process. The mold was then opened, and the composite material was removed and dried under normal pressure.

[0039] 2) A titanium alloy load-bearing structure, measuring 220mm*220mm*2mm, is used. A high-temperature resistant adhesive is coated on its surface, and carbon fiber mesh and fiber cloth are bonded to it. A density of 0.20g / cm³ is achieved using needle-punching technology. 3A fiber preform with a thickness of 8 mm was placed in a metal mold. The fiber preform was impregnated with a resin sol with a viscosity of 100 cps at 25°C using an RTM process. The mold was then sealed and placed in a 90°C oven for a 48-hour curing process. The mold was then opened, and the composite material was removed and dried under normal pressure.

[0040] 3) A carbon fiber reinforced bismaleimide resin composite material with dimensions of 220mm*220mm*4mm is used as the load-bearing structure. A high-temperature resistant adhesive is coated on its surface, and a quartz fiber mesh and fiber cloth are bonded to it. The structure is prepared using needle punching technology to achieve a density of 0.4g / cm³. 3 A 10mm thick fiber preform was placed in a metal mold. The fiber preform was then impregnated with a resin sol with a viscosity of 100cps at 25°C using an RTM process. The mold was then sealed and placed in a 90°C oven for a 48-hour curing process. The mold was then opened, and the composite material was removed and dried under normal pressure.

[0041] 4) A carbon fiber reinforced polyimide composite material with dimensions of 300mm*300mm*5mm is used as the load-bearing structure. A high-temperature resistant adhesive is coated on its surface, and a quartz fiber mesh and fiber cloth are bonded to its surface. The density is prepared using needle punching technology to achieve a density of 0.35g / cm³. 3 A 15mm thick fiber preform was placed in a metal mold. The fiber preform was then impregnated with a resin sol with a viscosity of 150cps at 25°C using an RTM process. The mold was then sealed and placed in a 100°C oven for a 48-hour curing process. The mold was then opened, and the composite material was removed and dried under normal pressure.

[0042] 5) A carbon fiber reinforced epoxy resin composite material with dimensions of 100mm*100mm*3mm is used as the load-bearing structure. A high-temperature resistant adhesive is coated on its surface, and a quartz fiber mesh and fiber cloth are bonded to it. The structure is prepared using needle punching technology to achieve a density of 0.18g / cm³. 3 A fiber preform with a thickness of 8 mm was formed. The above structure was placed in a metal mold, and the fiber preform was impregnated with a resin sol with a viscosity of 80 cps at 25°C using an RTM process. The mold was then sealed and placed in an 85°C oven for a 48-hour curing process. Afterward, the mold was opened, the composite material was removed, and dried under normal pressure.

[0043] 6) A carbon fiber reinforced epoxy resin composite material, measuring 100mm*100mm*3mm, is used as the load-bearing structure. A high-temperature resistant adhesive is coated on its surface, and a quartz fiber mesh and fiber cloth are bonded to it. The structure is prepared using needle-punching technology to achieve a density of 0.18g / cm³. 3A fiber preform with a thickness of 8 mm was formed. The above structure was placed in a metal mold, and the fiber preform was impregnated with a resin sol with a viscosity of 80 cps at 25°C using an RTM process. The mold was then sealed and placed in an 85°C oven for a 48-hour curing process. Afterward, the mold was opened, the composite material was removed, and dried under normal pressure.

[0044] 7) A cylindrical metal with a diameter of 300 mm and a length of 800 mm is used as the carrier. A high-temperature resistant adhesive is coated on its surface, and a quartz fiber mesh and fiber cloth are bonded to its surface. A density of 0.35 g / cm³ is prepared using needle punching technology. 3 A 10mm thick fiber preform was formed. The cylindrical structure was placed in a conformal metal mold, and the fiber preform was impregnated with a resin sol with a viscosity of 120cps at 25°C using an RTM process. The mold was then sealed and placed in a 90°C oven for a 48-hour curing process. The mold was then opened, and the composite material was removed and dried under normal pressure.

[0045] 8) A cylindrical carbon fiber reinforced polyimide composite material structure with an outer diameter of 380 mm, an inner diameter of 368 mm, and a length of 800 mm was used as the carrier. A high-temperature resistant adhesive was coated on its outer surface, and a quartz fiber mesh and fiber cloth were bonded to its surface. A density of 0.45 g / cm³ was prepared using needle punching technology. 3 A 17mm thick fiber preform was constructed. A soluble reinforcing structure was used as the core reinforcement of the cylindrical inner mold, and its surface was waterproofed before being placed inside the cylinder. The cylindrical structure was then placed in a conformal metal mold, and the fiber preform was impregnated with a resin sol with a viscosity of 170cps at 25°C using an RTM process. The mold was then sealed and placed in a 90°C oven for a 48-hour curing process. Subsequently, the mold was opened, the composite material was removed, and dried under normal pressure. The waterproof structure of the core reinforcement was then destroyed, and the core reinforcement structure was dissolved using a suitable solvent.

Claims

1. An in-situ molding / assembly integrated method for a fiber-reinforced thermal protection structure, characterized in that: Includes the following steps: 1) The surface of the structural support is sanded or polished to increase the surface roughness, and then the surface is cleaned with alcohols or ketones to enhance the surface adhesion. 2) Apply a high-temperature resistant adhesive to the cleaned surface of the structural support; 3) Cover the fiber preform with the adhesive to form a connection with the structural support, and let it stand for 24-48 hours to allow the adhesive to cure completely; 4) Using the structural support as the inner mold, and depending on the structural shape of the manufactured product and the strength of the structural support itself, an inner membrane reinforcement structure may be added as appropriate. 5) Design the external metal mold, the elements of which include: the product conformal surface structure, the mold sealing structure, the RTM process injection and dispensing port and bolt fastening holes. Assemble the metal mold with matching bolts, and use two ball valves respectively to assemble the injection port and dispensing port. Use PTFE tape to prevent leakage at the interface. Assemble the outer metal mold and the inner mold, and place the structural support of the bonded fiber preform into the metal mold; 6) Inject the resin sol into the mold using the RTM process. After no more air bubbles flow out of the outlet, continue to inject the sol under pressure for 10-20 minutes to ensure that the sol fully impregnates the fiber preform. 7) Place the mold in an oven at 80-120℃ for 24-48 hours for a sol-gel curing reaction. 8) After curing, open the mold and perform solvent drying on the cured fiber-reinforced heat-insulating composite material under normal pressure with a gradient temperature increase. That is, first perform the drying process in a ventilated place at room temperature for 24-36 hours, then perform the drying process in an oven at 50-60℃ for 24-48 hours, and finally perform the drying process in an oven at 90-120℃ for 24-48 hours to ensure the integrity of the surface and internal structure of the component.

2. The in-situ forming / assembly integrated method for a fiber-reinforced thermal protection structure according to claim 1, characterized in that: The structural support is made of aluminum alloy, and the fiber preform is impregnated with a resin sol with a viscosity of 360 cps at 25°C using the RTM process.

3. The in-situ forming / assembly integrated method for a fiber-reinforced thermal protection structure according to claim 1, characterized in that: The structural support is made of titanium alloy, and the fiber preform is impregnated with resin sol with a viscosity of 100 cps at 25°C using the RTM process.

4. The in-situ forming / assembly integrated method for a fiber-reinforced thermal protection structure according to claim 1, characterized in that: The structural support is a carbon fiber reinforced bismaleimide resin composite material, and the fiber preform is impregnated with a resin sol with a viscosity of 100 cps at 25°C using an RTM process.

5. The in-situ forming / assembly integrated method for a fiber-reinforced thermal protection structure according to claim 1, characterized in that: The structural support is a carbon fiber reinforced polyimide composite material, and the fiber preform is impregnated with a resin sol with a viscosity of 150 cps at 25°C using an RTM process.

6. The in-situ forming / assembly integrated method for a fiber-reinforced thermal protection structure according to claim 1, characterized in that: The structural support is a carbon fiber reinforced epoxy resin composite material, and the fiber preform is impregnated with a resin sol with a viscosity of 80 cps at 25°C using an RTM process.

7. The in-situ forming / assembly integrated method for a fiber-reinforced thermal protection structure according to claim 1, characterized in that: The structural support is a carbon fiber reinforced epoxy resin composite material, and the fiber preform is impregnated with a resin sol with a viscosity of 80 cps at 25°C using an RTM process.

8. The in-situ forming / assembly integrated method for a fiber-reinforced thermal protection structure according to claim 1, characterized in that: The structural support is a cylindrical metal, and the fiber preform is impregnated with a resin sol with a viscosity of 120 cps at 25°C using the RTM process.

9. The in-situ molding / assembly integrated method for a fiber-reinforced thermal protection structure according to claim 1, characterized in that: The structural support is a cylindrical carbon fiber reinforced polyimide composite material. A soluble reinforcing structure is used as the reinforcing core of the inner cylinder mold, and its surface is waterproofed. It is placed inside the cylinder of the cylindrical structural support. The cylindrical structural support is placed in a conformal metal mold. The fiber preform is impregnated with a resin sol with a viscosity of 170 cps at 25°C using the RTM process. Then the mold is sealed and placed in an oven for curing. The mold was then opened, the composite material was removed and dried at normal pressure, the waterproof structure of the reinforcing core was then destroyed, and the reinforcing core structure was dissolved using a solvent.

10. The in-situ molding / assembly integrated method for a fiber-reinforced thermal protection structure according to any one of claims 1-9, characterized in that: The fiber preform consists of a quartz fiber mesh and fiber cloth, and is prepared using needle punching technology.

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