In-situ forming / assembling integrated method of fiber-reinforced thermal protection structure

Abstract

The invention relates to an in-situ forming / assembling integrated method of a fiber-reinforced thermal protection structure, which solves the assembling problem of a thermal protection material at a bent special-shaped structure, simplifies the assembling process flow of the thermal protection structure, and can ensure the bonding consistency, integrity and quality stability of the thermal protection material. Comprising the following steps: coating a high-temperature-resistant adhesive on the surface of a cleaned structure supporting body; covering the adhesive with a fiber prefabricated body, connecting the fiber prefabricated body with the bearing structure main body, and standing until the curing of the adhesive is completed; designing an outer metal mold by taking the bearing structure as an inner mold; assembling the outer mold and the inner mold of the metal mold, and putting the bearing structure bonded with the fiber preform into the metal mold; the resin sol is injected into a mold through an RTM technology, and sol is injected; the mold is put into a drying oven for a sol-gel curing reaction; and after curing is completed, the mold is opened, and the cured fiber-reinforced heat prevention / insulation composite material is subjected to a solvent drying process at normal pressure in a gradient heating mode.

Description

Technical Field

[0001] The invention belongs to the field of preparation and assembly of thermal protection structures of aerospace products, and in particular relates to an integrated in-situ forming / assembly method of a fiber-reinforced thermal protection / insulation composite material. Background Art

[0002] The flight speed of aerospace products in the atmosphere is too high, and their surfaces will produce intense friction with the air, thus generating a large amount of aerodynamic heat, so a thermal protection structure is needed to protect the internal stability of the product. At present, large-area thermal protection areas on the outer surface of the product are mainly bonded to the product surface by "splicing" or "sleeving". The bonding process is relatively complicated, the process stability is poor, the bonding quality is difficult to guarantee, and it is difficult to operate in complex structures, which limits the structural design of the product. Summary of the invention

[0003] The present invention proposes an integrated in-situ forming / assembly method for a fiber-reinforced thermal protection structure, which realizes the integrated manufacturing and assembly of complex special-shaped load-bearing structures and thermal protection structures, solves the problem of assembling thermal protection materials at curved and special-shaped structures, simplifies the assembly process of the thermal protection structure, and ensures the bonding consistency, integrity and quality stability of the thermal protection materials, thereby achieving high-performance manufacturing goals.

[0004] The present invention is achieved by the following technical solutions:

[0005] An in-situ forming / assembly integrated method for a fiber-reinforced thermal protection structure comprises the following steps:

[0006] 1) Perform sandblasting or sandpaper polishing on the surface of the structural carrier to increase the surface roughness, and then use alcohols or ketones to clean the surface to enhance surface adhesion;

[0007] 2) coating a high temperature resistant adhesive on the surface of the cleaned structural carrier;

[0008] 3) Cover the fiber preform on the adhesive to form a connection with the main body of the load-bearing structure, and wait for 24-48 hours for the adhesive to cure;

[0009] 4) Take the load-bearing structure as the inner mold, and according to the structural shape of the manufactured product and the strength of the load-bearing structure itself, coordinate the inner membrane reinforcement structure as appropriate;

[0010] 5) Design the external metal mold, whose elements include: product conformal surface structure, mold sealing structure, RTM process glue injection and glue outlet and bolt fastening holes, assemble the metal mold with adapter bolts, use two ball valves to assemble at the glue injection and glue outlet respectively, and use raw tape to prevent leakage at the interface;

[0011] Assembling the outer metal mold with the inner mold, placing the bearing structure of the bonded fiber preform into the metal mold;

[0012] 6) Inject the resin sol into the mold by RTM process until no bubbles flow out of the outlet, and then inject the sol for 10-20 minutes while maintaining pressure to ensure that the sol fully impregnates the fiber preform;

[0013] 7) placing the mold in an oven at 80-120°C for 24-48 hours of sol-gel curing reaction;

[0014] 8) After the curing is completed, the mold is opened and the cured fiber-reinforced anti-corrosion / heat-insulating composite material is subjected to a solvent drying process in a gradient temperature rising manner under normal pressure, that is, firstly, a drying process is carried out in a ventilated place at normal temperature for 24-36 hours, then a drying process is carried out in an oven at 50-60°C for 24-48 hours, and finally a drying process is carried out in an oven at 90-120°C for 24-48 hours to ensure the integrity of the component surface and internal structure.

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

[0016] The bearing structure is titanium alloy, and a fiber preform is impregnated with a resin sol having a viscosity of 100 cps at 25° C. by an RTM process.

[0017] The bearing structure is a carbon fiber reinforced bismaleimide resin composite material, and a fiber preform is impregnated with a resin sol having a viscosity of 100 cps at 25° C. by an RTM process.

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

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

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

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

[0022] The bearing structure is a cylindrical carbon fiber reinforced polyimide composite material, a soluble reinforcement structure is used as the reinforcement core of the cylindrical inner mold, and its surface is waterproofed and placed inside the cylinder. The cylindrical structure is placed in a conformable metal mold, and a resin sol with a viscosity of 170 cps at 25°C is used to impregnate the fiber preform by RTM process, and then the mold is sealed and placed in an oven for curing process; then the mold is opened, the composite material is taken out and dried at normal pressure, and then the waterproof structure of the inner core of the reinforcement is destroyed, and a solvent is used to dissolve the inner core structure of the reinforcement.

[0023] The fiber preform is a quartz fiber mesh and fiber cloth, which is prepared by needle punching technology.

[0024] The method of the present invention breaks through the integrated manufacturing technology of complex special-shaped load-bearing structures and thermal protection structures, breaks the process limitations of traditional "step-by-step molding + bonding", and can be applied to the field of heat protection layer manufacturing in complex structural parts of products, solving problems such as the difficulty in assembly operation between the heat protection layer and the structural layer, effectively simplifying the assembly process of the thermal protection structure, improving the assembly reliability of the thermal protection structure, achieving high-performance manufacturing goals, realizing the manufacturing coupling of thermal protection + load-bearing structures, reducing the manufacturing cost of products, and improving the manufacturing quality of products. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0026] Figure 2 Schematic diagram of mold assembly installation;

[0027] Figure 3 Sol-gel 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 DESCRIPTION

[0030] The present invention develops an integrated in-situ forming / assembly method for fiber-reinforced heat-resistant / insulating composite materials through the coordinated design of the fiber preform forming process-heat-resistant structure forming process-bonding process, so that the heat-resistant structure can be assembled well after forming. This breaks the traditional step-by-step mode of manufacturing first and then bonding the heat-resistant structure, simplifies the manufacturing process of the product, improves the production efficiency and quality stability of the product, and achieves the goal of high-performance manufacturing.

[0031] Reference Figures 1 to 5 The technical invention is further described in detail with implementation cases.

[0032] Figure 1A flow chart for the process design of pre-connection of the carrier-fiber preform interface;

[0033] Figure 2 The figure shows a schematic diagram of the mold assembly installation in the present invention. During the process, it is necessary to ensure that the outer mold and the surface of the fiber preform are well fitted to avoid fiber wrinkles, fiber indentations, etc.

[0034] Figure 3 The figure shows the sol RTM process, in which the sol is injected into the mold in a gradient pressure-increasing manner, that is, the large gaps between the fiber and the mold are firstly exhausted by low pressure, and then the micro gaps in the fiber preform are exhausted by high pressure, so that the sol can fully impregnate the fiber preform. At the same time, this method can also avoid damage to the fiber preform due to excessive initial pressure;

[0035] Figure 4 The figure shows the sol-gel curing process of fiber-reinforced anti-heat / insulation composite materials. In this process, the mold must be well sealed to avoid the sealing failure of the reaction system caused by the increase in internal pressure due to the temperature increase and solvent vaporization effect;

[0036] Figure 5 The figure is a schematic diagram of the normal pressure drying process of the fiber-reinforced heat-resistant / heat-insulating composite material after curing. According to the shape and structure of the component, the drying tooling structure is designed as appropriate to avoid the capillary action of the solvent during drying, which may cause the component to exceed the outer dimension. After the drying is completed, the "load-bearing-heat-resistant structure in-situ forming / assembly integration" component is obtained, achieving the purpose of forming and assembling the thermal protection structure.

[0037] Example:

[0038] 1) Aluminum alloy is used as the bearing structure, the size is 220mm*220mm*8mm, high temperature resistant adhesive is coated on its surface, quartz fiber mesh and fiber cloth are bonded on its surface, and needle punching technology is used to prepare a density of 0.45g / cm 3 , a fiber preform with a thickness of 10mm. The above structure is placed in a metal mold, and the fiber preform is impregnated with a resin sol with a viscosity of 360cps at 25°C by RTM process, and then the mold is sealed and placed in a 110°C oven for a 48h curing process; then the mold is opened, and the composite material is taken out for normal pressure drying.

[0039] 2) Titanium alloy is used as the bearing structure, with a size of 220mm*220mm*2mm. High temperature resistant adhesive is coated on its surface, and carbon fiber mesh and fiber cloth are bonded on its surface. Needle punching technology is used to prepare a density of 0.20g / cm 3, a fiber preform with a thickness of 8mm. The above structure is placed in a metal mold, and the fiber preform is impregnated with a resin sol with a viscosity of 100cps at 25°C by RTM process, and then the mold is sealed and placed in a 90°C oven for a 48h curing process; then the mold is opened, and the composite material is taken out for normal pressure drying.

[0040] 3) Carbon fiber reinforced bismaleimide resin composite material is used as the load-bearing structure, the size is 220mm*220mm*4mm, high temperature resistant adhesive is coated on its surface, quartz fiber mesh and fiber cloth are bonded on its surface, and needle punching technology is used to prepare a density of 0.4g / cm 3 , a fiber preform with a thickness of 10mm. The above structure is placed in a metal mold, and the fiber preform is impregnated with a resin sol with a viscosity of 100cps at 25°C by RTM process, and then the mold is sealed and placed in a 90°C oven for a 48h curing process; then the mold is opened, and the composite material is taken out for normal pressure drying.

[0041] 4) A carbon fiber reinforced polyimide composite material is used as the bearing structure, with a size of 300mm*300mm*5mm. 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 0.35g / cm2 and the needle punching technology is used to prepare the composite material. 3 , a fiber preform with a thickness of 15mm. The above structure is placed in a metal mold, and the fiber preform is impregnated with a resin sol with a viscosity of 150cps at 25°C by RTM process, and then the mold is sealed and placed in a 100°C oven for a 48h curing process; then the mold is opened, and the composite material is taken out for normal pressure drying.

[0042] 5) A carbon fiber reinforced epoxy resin composite material is used as the load-bearing structure, with a size of 100mm*100mm*3mm. 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 0.18g / cm2 and the needle punching technology is used to prepare 3 , a fiber preform with a thickness of 8mm. The above structure is placed in a metal mold, and the fiber preform is impregnated with a resin sol with a viscosity of 80cps at 25°C by RTM process, and then the mold is sealed and placed in an 85°C oven for a 48h curing process; then the mold is opened, and the composite material is taken out for normal pressure drying.

[0043] 6) A carbon fiber reinforced epoxy resin composite material is used as the bearing structure, the size is 100mm*100mm*3mm, 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 0.18g / cm 3, a fiber preform with a thickness of 8mm. The above structure is placed in a metal mold, and the fiber preform is impregnated with a resin sol with a viscosity of 80cps at 25°C by RTM process, and then the mold is sealed and placed in an 85°C oven for a 48h curing process; then the mold is opened, and the composite material is taken out for normal pressure drying.

[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, a quartz fiber mesh and a fiber cloth are bonded to its surface, and a needle punching technique is used to prepare a density of 0.35 g / cm 3 , a fiber preform with a thickness of 10mm. The cylindrical structure is placed in a conformable metal mold, and the fiber preform is impregnated with a resin sol with a viscosity of 120cps at 25°C by RTM process, and then the mold is sealed and placed in a 90°C oven for a 48h curing process; then the mold is opened, and the composite material is taken out for normal pressure drying.

[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 a carrier, a high temperature resistant adhesive was coated on its outer surface, a quartz fiber mesh and a fiber cloth were bonded to its surface, and a needle punching technique was used to prepare a density of 0.45 g / cm 3 , a fiber preform with a thickness of 17mm. A soluble reinforcement structure is used as the reinforcement core of the inner mold of the cylinder, and its surface is waterproofed and placed inside the cylinder. The above cylindrical structure is placed in a conformable metal mold, and a resin sol with a viscosity of 170cps at 25°C is used to impregnate the fiber preform by RTM process, and then the mold is sealed and placed in a 90°C oven for a 48h curing process; then the mold is opened, the composite material is taken out for normal pressure drying, and then the waterproof structure of the reinforcement core is destroyed, and a suitable solvent is used to dissolve the reinforcement core structure.

Claims

1. An in-situ forming / assembly integrated method for a fiber-reinforced thermal protection structure, characterized by: The following steps are involved: 1) Perform sandblasting or sandpaper polishing on the surface of the structural carrier to increase the surface roughness, and then use alcohols or ketones to clean the surface to enhance surface adhesion; 2) coating a high temperature resistant adhesive on the surface of the cleaned structural carrier; 3) Cover the fiber preform on the adhesive to form a connection with the main body of the load-bearing structure, and wait for 24-48 hours for the adhesive to cure; 4) Take the load-bearing structure as the inner mold, and according to the structural shape of the manufactured product and the strength of the load-bearing structure itself, coordinate the inner membrane reinforcement structure as appropriate; 5) Design the external metal mold, whose elements include: product conformal surface structure, mold sealing structure, RTM process glue injection and glue outlet and bolt fastening holes, assemble the metal mold with adapter bolts, use two ball valves to assemble at the glue injection and glue outlet respectively, and use raw tape to prevent leakage at the interface; Assembling the outer metal mold with the inner mold, placing the bearing structure of the bonded fiber preform into the metal mold; 6) Inject the resin sol into the mold by RTM process until no bubbles flow out of the outlet, and then inject the sol for 10-20 minutes while maintaining pressure to ensure that the sol fully impregnates the fiber preform; 7) placing the mold in an oven at 80-120°C for 24-48 hours of sol-gel curing reaction; 8) After the curing is completed, the mold is opened and the cured fiber-reinforced anti-corrosion / heat-insulating composite material is subjected to a solvent drying process in a gradient temperature rising manner under normal pressure, that is, firstly, a drying process is carried out in a ventilated place at normal temperature for 24-36 hours, then a drying process is carried out in an oven at 50-60°C for 24-48 hours, and finally a drying process is carried out in an oven at 90-120°C for 24-48 hours to ensure the integrity of the component surface and internal structure.

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

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

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

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

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

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

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

9. The in-situ forming / assembly integrated method of a fiber reinforced thermal protection structure according to claim 1, characterized in that: The bearing structure is a cylindrical carbon fiber reinforced polyimide composite material, a soluble reinforcement structure is used as the reinforcement core of the cylindrical inner mold, and the surface is waterproofed and placed inside the cylinder. The cylindrical structure is placed in a conformable metal mold, and a resin sol with a viscosity of 170 cps at 25° C. is used to impregnate the fiber preform by RTM process, and then the mold is sealed and placed in an oven for curing process; The mold is then opened, the composite material is taken out and dried at normal pressure, the waterproof structure of the inner core of the reinforcement is then destroyed, and the inner core structure of the reinforcement is dissolved by a solvent.

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

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