A forming die and method for large size curved rigid aerogel material

Abstract

The present application relates to a kind of forming die and method of large size curved rigid aerogel material.The forming die of large size curved rigid aerogel material includes: male die;Assembled female die, which is fixedly connected with male die, and the assembled female die and male die form forming cavity between them.The present application adopts multiple vacuumizing and pressurizing auxiliary impregnation mode in x, z two dimensions, to ensure that fiber preform is fully impregnated, by adjusting the size of pressurization and impregnation speed, solve the surface wrinkle of the formed aerogel material, by heating vibrator auxiliary removal of the air bubble generated in mould, greatly improve the cooperation precision of aerogel material and other components.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aerogel materials, in particular to a forming mold and method of large-size curved rigid aerogel material. BACKGROUND

[0002] With the progress of science and technology and the development of industry, the requirements for material performance are becoming higher and higher, especially on large-size curved structures that need to bear complex loads and harsh environments, the selection of materials is particularly important. Aerogel is a new type of thermal insulation material. Due to the high proportion of gas phase in aerogel, the solid phase heat transfer is greatly reduced compared to traditional thermal insulation materials, and the nanoscale pores also have a significant inhibitory effect on gas heat transfer, so it has been widely used in high-end manufacturing fields such as aerospace, automobiles, ships, and wind power.

[0003] The forming technology of aerogel material usually adopts resin transfer molding (RTM for short). RTM is a process of injecting resin into a closed mold, infiltrating the reinforcing material, and then curing to form a composite material. It can produce composite materials with accurate thickness and good appearance quality. Although RTM technology has shown many advantages in the manufacturing of components, it still faces some technical challenges, and mold design and manufacturing are one of the key technologies that need to be broken through. The forming mold determines the shape, size and fitting precision of the composite material component with other components, and is a key factor to ensure product quality, improve production efficiency and reduce cost. Due to its complex structure, the structure of the mold needs to be considered comprehensively, and defects such as bubbles, delamination, etc. may occur during the forming process, and a series of problems such as demolding after forming may occur. SUMMARY

[0004] Therefore, the main purpose of the present application is to provide a forming mold and method of large-size curved rigid aerogel material. The problem to be solved is to ensure that the fiber preform is fully impregnated by using multiple vacuumizing and pressurizing auxiliary impregnation methods in the x and z dimensions, to solve the surface wrinkles of the formed aerogel material by adjusting the pressure and impregnation speed, and to greatly improve the fitting precision of the aerogel material with other components by using a heating vibrator to assist in removing the bubbles generated in the mold.

[0005] The purposes and technical problems of the present application are realized by adopting the following technical solutions. The present application provides a forming mold of large-size curved rigid aerogel material, which comprises:

[0006] a male mold;

[0007] an assembled female mold fixedly connected with the male mold, and a forming cavity formed between the assembled female mold and the male mold.

[0008] The purposes and technical problems of the present application can be further realized by adopting the following technical measures.

[0009] Preferably, the forming mold for large-sized curved rigid aerogel material, wherein the convex part of the male mold and the concave part of the assembled female mold form a forming cavity for placing the fiber preform.

[0010] Preferably, the forming mold for large-sized curved rigid aerogel material, wherein a plurality of heating vibrators are uniformly distributed on the male mold and the assembled female mold.

[0011] Preferably, the forming mold for large-sized curved rigid aerogel material, wherein the side wall of the male mold has a plurality of heating vibrator holes, the side wall of the assembled female mold has a plurality of heating vibrator holes, and a heating vibrator is placed in each of the plurality of heating vibrator holes of the male mold and the assembled female mold.

[0012] Preferably, the forming mold for large-sized curved rigid aerogel material, wherein the peripheral edge of the male mold has a plurality of threaded holes, each of the plurality of threaded holes has a plurality of mold opening holes in the middle, each of the plurality of threaded holes has a screw matched therewith, and each of the four mold opening holes has a screw matched therewith.

[0013] Preferably, the forming mold for large-sized curved rigid aerogel material, wherein the side wall of the assembled female mold has a thermocouple hole, a thermocouple is placed in the thermocouple hole, and the thermocouple is connected to the heating vibrator.

[0014] Preferably, the forming mold for large-sized curved rigid aerogel material, wherein the bottom and the side wall of the assembled female mold have glue injection holes.

[0015] Preferably, the forming mold for large-sized curved rigid aerogel material, wherein the top of the male mold has a plurality of glue outlet holes, and the side wall of the assembled female mold has a glue outlet hole.

[0016] Preferably, the forming mold for large-sized curved rigid aerogel material, wherein the peripheral side wall of the assembled female mold is further provided with a plurality of pneumatic telescopic push rods for facilitating demolding, a plurality of lifting rings for facilitating assembly and disassembly, and a plurality of handles.

[0017] Preferably, the forming mold for large-sized curved rigid aerogel material, wherein the assembled female mold comprises a detachable core and a fixed core, the side wall of the fixed core is provided with a plurality of pneumatic telescopic push rods, and the plurality of pneumatic telescopic push rods are connected to the detachable core through a mortise and tenon structure.

[0018] Preferably, the forming mold of large-size curved rigid aerogel material, wherein the fixed core is concave curved in shape, which is assembled with the detachable core to form a curved female mold; the male mold is convex curved in shape, and the male mold and the assembled female mold are connected by screws to form a curved forming cavity.

[0019] Preferably, the forming mold of large-size curved rigid aerogel material, wherein the inner surface of the male mold and the assembled female mold is coated with polytetrafluoroethylene, and the thickness is 20-50 microns.

[0020] Preferably, the forming mold of large-size curved rigid aerogel material, wherein the detachable core comprises a plurality of cuboid female mold modules arranged in sequence, and each female mold module is provided with a corresponding pneumatic telescopic push rod.

[0021] Preferably, the forming mold of large-size curved rigid aerogel material, wherein the fixed core is provided with a groove around the periphery for placing the detachable core, and the thickness of the detachable core is less than the width of the groove.

[0022] Preferably, the forming mold of large-size curved rigid aerogel material, wherein each female mold module is provided with a plurality of assembly holes in the length direction, and each assembly hole is provided with a screw.

[0023] Preferably, the forming mold of large-size curved rigid aerogel material, wherein the assembled female mold is provided with a sealing groove around the periphery, and the sealing groove is provided with a sealing ring.

[0024] The purposes and technical problems of the present application can also be achieved by the following technical solutions. The present application provides a forming method of large-size curved rigid aerogel material, comprising the following steps:

[0025] S1 Sol preparation: the sol is prepared by an acid-base two-step method;

[0026] S2 Molding: start the pneumatic telescopic push rod to the stretching state, assemble the detachable core with the inner convex structure of the fixed core to form a mold forming cavity; cut the fiber preform to the size of the mold forming cavity, and then lay the fiber preform flat in the mold forming cavity; then fix the assembled female mold and male mold with screws to complete the assembly of the fiber preform;

[0027] S3 Glue injection: in the x and z dimensions, multiple vacuumizing and pressurizing are adopted to assist the glue impregnation;

[0028] S4 Curing and aging: curing and aging are performed by heating;

[0029] S5 demoulding and drying: control the pneumatic telescopic push rod to the retracted state, separate the detachable core from the inner convex structure of the fixed core, and make the gel fiber preform block demould smoothly, and then perform supercritical drying of carbon dioxide.

[0030] The purposes and technical problems of the present application can also be further achieved by the following technical measures.

[0031] Preferably, in the forming method of the large-size curved rigid aerogel material, the preparation of the sol in step S1 specifically comprises: uniformly mixing and stirring the silicon source and the solvent according to the molar ratio; adjusting the pH value of the sol to 3-4 by using an acidic catalyst, then adding an alkaline catalyst to adjust the pH value of the sol to 6-7 after 4-8 hours of reaction.

[0032] Preferably, in the forming method of the large-size curved rigid aerogel material, the silicon source in step S1 is selected from at least one of methyl orthosilicate, ethyl orthosilicate and water glass; the solvent is selected from at least one of water, anhydrous ethanol, methanol, glycerol and isopropyl alcohol; the acidic catalyst is selected from at least one of hydrochloric acid aqueous solution and nitric acid aqueous solution; the alkaline catalyst is selected from at least one of ammonia water and sodium hydroxide aqueous solution; and the molar ratio of the solvent to the silicon source is (1-10):1.

[0033] Preferably, in the forming method of the large-size curved rigid aerogel material, the fiber preform in step S2 is selected from at least one of alumina fiber, mullite fiber, basalt fiber, glass fiber and high-silica fiber, and the density of the fiber preform is 0.15 g / cm 3 -0.2 g / cm 3 .

[0034] Preferably, in the forming method of the large-size curved rigid aerogel material, step S3 comprises: vacuumizing the mold to a vacuum degree of not less than -0.08 MPa for not less than 1 minute; then pressurizing at a rate of 0.1-0.5 MPa per minute to less than or equal to 0.8 MPa to fill the mold with the sol, and this process is repeated for 2-3 times; maintaining the positive pressure until no bubbles are generated in the liquid flowing out of the glue outlet, and the glue injection is completed.

[0035] Preferably, in the forming method of the large-size curved rigid aerogel material, the vibration mode is started during the glue injection in step S3, the vibration direction is consistent with the glue injection direction, and the vibration frequency is controlled to be between 40 Hz and 60 Hz.

[0036] Preferably, in the forming method of the large-size curved rigid aerogel material, the heating temperature in step S4 is 40-60℃, the curing time is 30-60 minutes, and the aging time is 60-120 minutes.

[0037] Preferably, the forming method of the large-size curved rigid aerogel material, wherein in step S5, the drying temperature is 45 DEG C ~ 55 DEG C, and the drying pressure is 10 MPa ~ 14 MPa.

[0038] By the above technical scheme, the forming mold and method of the large-size curved rigid aerogel material provided by the application have at least the following advantages:

[0039] 1. The application significantly improves the impregnation effect of the fiber preform by adopting the multiple vacuumizing and pressurizing auxiliary impregnation method in the x and z dimensions, which not only ensures that the fiber preform is fully and uniformly impregnated, but also effectively solves the surface wrinkle problem that is prone to occur in the traditional forming process of aerogel materials by adjusting the pressurizing size and impregnation speed. The reduction of the wrinkle not only improves the appearance quality of the aerogel material, but more importantly, it enhances the overall structural stability and mechanical properties of the material. In addition, the application also ingeniously introduces the step of heating vibrator auxiliary bubble removal in the mold, which greatly reduces the internal defects of the aerogel material caused by the existence of bubbles in the preparation process, and greatly improves the matching precision of the aerogel material and other components.

[0040] 2. The mold provided by the application designs the assembled female mold module, male and female film heating vibrator and pneumatic telescopic push rod, and the mold structure is simple, which successfully solves the problems of bubble accumulation and demolding difficulty in the forming process, improves the flexibility of the mold, and is convenient for maintenance and replacement of the mold. The application integrates multiple processes such as forming, heating curing and aging in the mold, realizes the integration of operation, makes the operation simpler, improves the continuity and stability of production, ensures the consistency of product quality, and effectively reduces the production cost and maintenance cost.

[0041] 3. The large-size curved rigid aerogel prepared by the application has an arc length of 310mm ~ 340mm, a radius of 150mm ~ 160mm, a curved arc angle of 120° ~ 123°, a density of 0.22g / cm 3 ~ 0.26g / cm 3 , a thermal conductivity of 0.040W / (m·K) ~ 0.065W / (m·K) at 1000 DEG C, and a compressive strength of 0.5MPa ~ 1MPa under 10% compression, which is convenient for processing and can be used as a good high-temperature resistant thermal insulation material.

[0042] The above description is only a summary of the technical scheme of the application, in order to more clearly understand the technical means of the application, and the content of the specification can be implemented as follows. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 A three-dimensional structural diagram of a forming mold for a large-size curved rigid aerogel according to an embodiment of the present application;

[0044] Figure 2 A three-dimensional structural diagram of a fixed core of an assembled female mold for a large-size curved rigid aerogel according to an embodiment of the present application;

[0045] Figure 3 A three-dimensional structural diagram of a detachable core of an assembled female mold for a large-size curved rigid aerogel according to an embodiment of the present application;

[0046] Figure 4 A three-dimensional assembly diagram of a large-size curved rigid aerogel according to an embodiment of the present application;

[0047] Figure 5 A process flow diagram of a large-size curved rigid aerogel according to an embodiment of the present application. DETAILED DESCRIPTION

[0048] To further clarify the technical means and effects taken by the present application to achieve the predetermined purposes, the specific implementation, structure, features and effects of a forming mold and method for a large-size curved rigid aerogel material according to the present application are described in detail as follows. In the following description, different "an embodiment" or "embodiments" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0049] The following materials or reagents, unless otherwise specified, are commercially available.

[0050] As shown in Figures 1-4 some embodiments of the present application provide a forming mold for a large-size curved rigid aerogel material, comprising:

[0051] a male mold 8;

[0052] an assembled female mold 9, which is fixedly connected with the male mold 8, and a forming cavity is formed between the assembled female mold 9 and the male mold 8.

[0053] In some optional embodiments, the protrusion of the male mold 8 and the recess of the assembled female mold 9 form a forming cavity for placing a fiber preform 10 for preparing a rigid aerogel material. In the process of preparing the rigid aerogel material, a fiber preform is used to enhance the aerogel material.

[0054] In some alternative embodiments, the four peripheral edges of the male mold 8 have twelve threaded holes 11, and the middle of the twelve threaded holes 11 has four mold opening holes 12, so as to facilitate disassembly of the mold male mold 8; the twelve threaded holes 11 respectively have screws matched therewith, and the four mold opening holes 12 respectively have screws matched therewith; during the mold assembly process, the male mold 8 and the assembled female mold 9 are assembled together through the screws, and the screws not only play a connecting role, but also ensure the stability and precision of the mold during the molding process.

[0055] In some alternative embodiments, the side wall of the male mold 8 has six heating vibrator holes 13, and the side wall of the assembled female mold 9 has six heating vibrator holes 13, and the twelve heating vibrator holes 13 respectively have heating vibrators placed therein, so as to achieve the purposes of rapid bubble removal and all-around heating during the preparation of rigid aerogel materials.

[0056] In some alternative embodiments, the side wall of the assembled female mold 9 has a thermocouple hole 14, and a thermocouple is placed in the thermocouple hole, so as to collect actual temperature data of the mold. In addition, the thermocouple is connected with the heating vibrator 13.

[0057] In some alternative embodiments, the bottom (x direction) and the side wall (z direction) of the assembled female mold 9 both have a glue injection hole 1.

[0058] In some alternative embodiments, the top of the male mold 8 has four glue outlet holes 16, and the side wall of the assembled female mold 9 has a glue outlet hole 16, and these glue outlet holes 16 are used to assist in removing bubbles and avoiding defects during the glue injection process.

[0059] In some alternative embodiments, the four peripheral side walls of the assembled female mold 9 are further provided with four pneumatic telescopic push rods 23 for facilitating demolding, four lifting rings 17 for facilitating assembly and disassembly, and eight handles 18.

[0060] In some alternative embodiments, the assembled female mold 9 includes a detachable core 21 and a fixed core 20, the detachable core 21 includes four cuboid female mold modules arranged in sequence, each of the female mold modules has a pneumatic telescopic push rod 23 matched therewith, the four pneumatic telescopic push rods 23 are arranged on the side wall of the fixed core 20, and the four pneumatic telescopic push rods 23 are connected with the detachable core 21 through a mortise and tenon structure, thereby providing power for assembly and disassembly of the female mold modules; in addition, the edges of the edge seams of each female mold module need to be accurately machined to form a circular chamfer with a radius of 0.5 cm, thereby facilitating assembly and disassembly of the female mold modules and bubble removal.

[0061] In some alternative embodiments, the fixed core 20 has a groove around its perimeter for placing the detachable core 21, the thickness of the detachable core 21 is 5 cm, and the width of the groove is 7 cm, providing a telescopic space for the telescopic air cylinder 23 and avoiding damage to the gel fiber preform (gel injection has been completed) during demolding.

[0062] In some alternative embodiments, each of the female mold modules has two assembly holes 22 in its length direction, which facilitates the assembly and disassembly of the female mold modules and facilitates the cleaning and maintenance of the mold. Specifically, the two assembly holes 22 can be respectively arranged at 1 / 4 and 3 / 4 of the length of the female mold module, as shown in Figure 3 Both of the assembly holes 22 have screws matched therewith.

[0063] In some alternative embodiments, the fixed core 20 is a concave curved surface shape, which is assembled with the detachable core 21 to form a curved female mold, and the male mold 8 is a convex curved surface shape; the male mold 8 and the assembled female mold 9 are connected by screws and form a curved surface forming cavity.

[0064] In some alternative embodiments, the inner surfaces of the male mold 8 and the assembled female mold 9 are both provided with a polytetrafluoroethylene coating with a thickness of 20-50 microns. If the thickness is less than 20 microns, the coating is too thin to affect its corrosion and corrosion resistance performance, and it cannot effectively protect the mold; if it is greater than 50 microns, the coating is too thick to affect its wear resistance, corrosion resistance, and other properties, thereby shortening the service life. Too thin or too thick may affect demolding; during mold manufacturing, the polytetrafluoroethylene coating is plated on the inner surface of the mold, which can prevent the gel fiber preform from sticking and sticking on the surface of the mold, thereby reducing mold contamination, improving mold service life, and reducing the impact on the appearance and internal quality of the gel fiber preform.

[0065] In some alternative embodiments, the assembled female mold 9 is provided with a sealing groove 19 around its perimeter, and a sealing ring is arranged in the sealing groove 19; after the male mold 8 and the assembled female mold 9 are closed, the sealing ring is placed in the sealing groove 19 for sealing, which helps to prevent the fiber preform from leaking during gel injection and ensures the quality and integrity of the gel fiber preform.

[0066] In the technical scheme, the assembly type female die module is used to form a female die forming cavity of the mold, the assembly type female die module joint gap can effectively solve the bubble accumulation in the forming process, the pneumatic telescopic push rod is designed in the assembly type female die fixed core, the pneumatic telescopic push rod can provide uniform pressure, and uniform separation between the mold and the aerogel prefabricated block material is ensured, the assembly type female die module is matched, the demolding difficulty problem is successfully solved, the defects of the aerogel material in the forming process are avoided, and the good product rate of the aerogel material is greatly improved. The heating vibrator hole and the thermocouple hole reserved in the mold female and male films provide convenient operation for the curing and aging process of the aerogel material after the glue injection is completed.

[0067] In addition, the arc length of the large-size curved rigid aerogel material mentioned above is 310mm-340mm, the radius is 150mm-160mm, the angle of the curved arc is 120°-123°, the density is 0.22g / cm 3 -0.26g / cm 3 , the thermal conductivity at 1000℃ is 0.040W / (m·K)-0.065W / (m·K), and the compressive strength under 10% compression is 0.5MPa-1MPa.

[0068] As Figure 5 shown, some embodiments of the present application also provide a forming method of a large-size curved rigid aerogel material, comprising the following steps:

[0069] Step 1, sol preparation process: the sol is prepared by an acid-base two-step method, and the silicon source and the solvent are fully mixed and stirred uniformly according to the molar ratio. Then, the pH value of the sol is adjusted to 3-4 by using an acidic catalyst, and after 4h-8h of reaction, the pH value of the sol is adjusted to 6-7 by adding an alkaline catalyst. Specifically, the silicon source can be one or more of methyl orthosilicate, ethyl orthosilicate, water glass, etc.; the solvent can be one or more of water, anhydrous ethanol, methanol, glycerol, isopropyl alcohol, etc.; the acidic catalyst can be one or more of hydrochloric acid aqueous solution, nitric acid aqueous solution, etc.; the alkaline catalyst can be one or more of ammonia, sodium hydroxide aqueous solution, etc.; and the molar ratio of the solvent to the silicon source is (1-10):1.

[0070] Step 2, mold loading process: the pneumatic telescopic push rod 23 is started to the stretched state, and the inner convex structure of the detachable core 21 and the fixed core 20 is matched according to the design of the mold cavity, and the detachable core 21 is matched with the fixed core 20. Figure 4assembly of the mold cavity, cutting the fiber preform to fit the mold cavity; placing the cut fiber preform flat in the mold cavity, positioning the male and female molds through the threaded holes 11 to ensure accurate alignment when the mold is closed. The assembled female mold 9 and male mold 8 are closed according to the designed positioning structure, ensuring that all parts of the mold are tightly fitted to avoid gaps or misalignment. The assembled female mold 9 and male mold 8 are secured with screws, completing the assembly of the fiber preform. The fiber preform is mainly used to enhance the strength and heat resistance of aerogels to meet different thermal insulation temperature requirements. The selected fiber preform can be one or more of alumina fiber, mullite fiber, basalt fiber, glass fiber, and high-silicon fiber, with a density of 0.15 g / cm 3 ~ 0.2 g / cm 3 ;

[0071] Step 3, glue injection process: in the x and z dimensions, use multiple vacuum and pressure assisted impregnation methods to ensure that the fiber preform is fully impregnated while increasing the number of exhaust points. First, vacuum the mold to a vacuum degree of not less than -0.08 MPa for not less than 1 min, which can effectively remove air in the mold and pores in the fiber preform, creating favorable conditions for sol injection. Second, open the air pump and slowly increase the pressure to 0.1 MPa to 0.5 MPa per minute, with a maximum of 0.8 MPa. Pressurizing helps sol penetrate into every corner of the fiber preform, resulting in a uniform gel fiber preform block structure. However, excessive pressure (such as more than 0.8 MPa) can cause the sol to flow too much, causing the fiber preform to move and wrinkle in the mold, resulting in deformation defects in the prepared gel fiber preform block. This process is repeated 2-3 times to ensure that the sol can fully impregnate the fiber preform and expel the gas in the mold, maintaining a positive pressure until no bubbles are observed in the liquid flowing out of the glue outlet. The glue injection process is complete. During the process, the heating vibrator is turned on in vibration mode, with the vibration direction consistent with the glue injection direction and the vibration frequency controlled at 40 Hz to 60 Hz to obtain a high-quality gel fiber preform block. A vibration frequency higher than 60 Hz can cause the sol to produce too much foam, affecting the density and mechanical properties of the product. A vibration frequency lower than 40 Hz may not achieve the desired impregnation effect, also affecting the quality of the product. The heating vibrator is placed in the heating vibrator hole 13 of the male and female molds, and vibration can make the bubbles in the mold move quickly and gather in the glue injection position and dead corner position of the mold. Therefore, glue outlets are designed at these positions to expel the bubbles and avoid defects.

[0072] Step 4, curing and aging process: The mold is heated and rapidly cured and aged by a heating vibrator, the curing temperature is controlled at 40-60°C, and the process lasts for 30-60 minutes. Higher temperature is beneficial for the mutual collision and condensation of sol particles, and is basically inversely proportional to the gelation time. If the temperature is greater than 60°C, the curing temperature is too high, which may cause the following problems: 1. uneven structure and coarse particles: high temperature may cause the collision and condensation of sol particles to be too violent, resulting in uneven gel structure, even coarse particles, affecting the final performance of aerogel. 2. gel cracking: too high temperature may also generate large internal stress, increasing the risk of gel cracking. If the temperature is less than 40°C, the curing temperature is too low, which may cause the gelation reaction to be slow: at low temperature, the collision and condensation speed of sol particles will slow down, resulting in prolonged gelation reaction time, and even may not be able to completely form a gel. If the time is greater than 60 minutes, the long curing time may cause the gel structure to become too tight, affecting its porosity and specific surface area, and thus leading to the decline of thermal insulation performance; while if the time is less than 30 minutes, the short curing time may make the gel not fully stable, resulting in poor performance and affecting subsequent use.

[0073] The aging temperature is controlled at 40-60°C, and the process lasts for 60-120 minutes; aging helps to stabilize the gel structure and improve performance. If the temperature is greater than 60°C, the aging temperature is too high, the evaporation of water in the gel will accelerate, leading to gel shrinkage, and thus affecting its final performance and morphology; high temperature may also cause chemical reactions of some components in the gel, leading to changes in gel properties, and even destroying the gel structure. If the temperature is less than 40°C, the aging temperature is too low, the gel formation and stabilization process may become slow, prolonging the production cycle; at low temperature, the molecular motion in the gel slows down, which may not be conducive to the close arrangement of gel structure and the improvement of performance. If the time is less than 60 minutes, the aging time is insufficient, the gel may not be fully stable, and its internal network structure may not be strong enough, leading to poor performance of the gel, such as low strength, insufficient porosity, etc. If the time is greater than 120 minutes, the long aging time may make the gel structure become too tight, reducing the porosity and specific surface area, and thus affecting its thermal insulation performance. In addition, the long aging time may also increase the production cost and energy consumption.

[0074] During the curing and aging process, in order to facilitate the heating of the mold, heating vibrators are placed in the pre-designed heating vibrator holes 13, which are 12 in total on the male and female films of the mold, to achieve a full range of heating effect. In order to accurately control the heating process, the heating vibrator 13 is connected with the thermocouple placed in the thermocouple hole 14 of the mold, and the thermocouple is used to collect the temperature data of the mold. By comparing these data with the set value of the heating vibrator, the power of the heating vibrator can be adjusted in time to ensure the accuracy and stability of the temperature. Such design can ensure the uniformity and accuracy of heating. Through the direct heating of the heating vibrator, the mold can quickly reach the required temperature, thereby realizing an efficient curing and aging process.

[0075] Step 5, demolding and drying process: when demolding, the pneumatic telescopic push rod 23 is controlled to the retracted state, which can quickly separate the detachable core from the inner convex structure of the fixed core, so that the gel fiber preform block is smoothly demolded (wet gel is obtained), and the collapse of the internal structure of the gel fiber preform block at the edge caused by extrusion during the demolding process is effectively avoided, and the phenomena of delamination and damage are generated; then, under the conditions of a drying temperature of 45-55°C and a drying pressure of 10-14 MPa, carbon dioxide supercritical drying is carried out, and the large-size curved rigid aerogel material (curved) is obtained. The selection of the drying temperature of 45-55°C and the drying pressure of 10-14 MPa can ensure that the carbon dioxide reaches the supercritical state, which can effectively avoid the problems of gel shrinkage and cracking caused by capillary force. By adjusting the temperature and pressure of carbon dioxide, the drying time can be effectively controlled and the drying efficiency can be improved.

[0076] In the above technical solution, during the glue injection process, the multiple vacuumizing and pressurizing auxiliary impregnation method is adopted in the x and z dimensions to ensure that the fiber preform is fully impregnated and the bubbles are effectively removed. By adjusting the pressure and impregnation speed, the surface wrinkles of the formed aerogel material are solved. The heating vibrator is used to assist in removing the bubbles generated in the mold, which greatly improves the cooperation precision of the aerogel material and other components.

[0077] The specific embodiments of the present application will be further described in detail below in conjunction with the examples, but it should not be understood as limiting the scope of protection of the present application. Some non-essential improvements and adjustments made by the person skilled in the art based on the content of the present application still belong to the protection scope of the present application.

[0078] Unless otherwise specified, the materials, reagents, etc. involved below are commercially available goods well known to those skilled in the art; unless otherwise specified, the methods described are well-known methods in the art. Unless otherwise defined, the technical terms or scientific terms used should be the usual meaning understood by those skilled in the art in the field to which the present application belongs.

[0079] In Examples 1-3 below, the angle formula for the curved arc of the large-size curved rigid aerogel material is n = 180l / (πr), where r is the radius and l is the arc length, which is measured by an electronic surface measuring instrument.

[0080] In Examples 1-3 below, the density of the large-size curved rigid aerogel material is obtained by testing the mass and volume of the large-size curved rigid aerogel material and then using the mass-to-volume ratio.

[0081] The thermal conductivity of the large-size curved rigid aerogel materials in Examples 1-3 below was measured by the water flow plate method according to YB / T4130;

[0082] The compressive strength of the large-size curved rigid aerogel materials in Examples 1-3 below was measured by an electronic universal testing machine.

[0083] Example 1:

[0084] like Figure 5 As shown, this embodiment provides a method for molding large-size curved rigid aerogel materials, including the following steps:

[0085] Step 1: The gel solution is a silica gel system. The gel solution contains tetraethyl orthosilicate as the silica source, anhydrous ethanol and water in a mass ratio of 1:1, and the molar amount of the solvent is 5 times that of the silica source. The acid catalyst is 1M hydrochloric acid aqueous solution. The pH value of the sol is adjusted to 3. After the reaction is complete, 1M ammonia water is added to adjust the pH value of the sol to 7.

[0086] Step 2: The fiber preform is made of mullite fiber with a fiber density of 0.15 g / cm³. 3 The thickness is 15mm. Place the assembled female mold in the corresponding position. During the mold assembly process, first assemble the fixed core 20 and the detachable core 21 together. Activate the pneumatic telescopic push rod 23 to the extended state, and align the inner convex structures of the detachable core 21 and the fixed core 20 according to… Figure 4 Assemble the fiber preforms in the following directions to form the molding cavity of the mold. Cut the fiber preforms to fit the size of the molding cavity of the mold. Then lay the cut fiber preforms 10 flat in the molding cavity of the mold. Install the male mold 8 of the mold and ensure the position is accurate by using positioning bolts. Use screws to fasten the assembled female mold 9 and male mold 8 of the mold to complete the fiber preform assembly and prepare for glue injection.

[0087] Step 3: The injection process is as follows: close all the valves of the injection ports 15 of the mold, open all the valves of the outlet ports 16 of the mold, check the airtightness of the mold, the vacuum degree is -0.09MPa, and the vacuum degree is -0.08MPa within 3 minutes after stopping the vacuuming. If the airtightness test is passed, the injection can proceed.

[0088] Firstly, glue injection is carried out in the z direction, all valves are closed, the valve of the glue outlet 16 in the z direction of the mold is opened, the mold is vacuumized, the vacuum degree is-0.08 MPa, the vacuum time is 1 min; the valve of the glue outlet 16 in the z direction of the mold is closed, the valve of the glue inlet 15 in the z direction of the mold is opened, the air pump valve is opened, the pressure is slowly increased at a speed of 0.2 MPa per minute to 0.5 MPa, the heating vibrator is placed in the heating vibrator hole 13 reserved in the mold, the vibration mode of the heating vibrator is opened, adjusted to z direction vibration, the vibration frequency is controlled at 50 Hz, the mold is filled with glue, the process is repeated 3 times, the positive pressure is maintained, the valve of one glue outlet 16 in the z direction of the mold is opened until there is no bubble in the liquid flowing out of the glue outlet 16 in the z direction, the valve of one glue inlet 15 in the z direction and the valve of one glue outlet 16 in the z direction are closed, and the glue injection in the z direction is completed;

[0089] Secondly, glue injection is carried out in the x direction, the valve of one glue inlet 15 in the x direction of the mold is opened, the air pump valve is opened, the pressure is slowly increased at a speed of 0.2 MPa per minute to 0.5 MPa, the heating vibrator is adjusted to x direction vibration, the vibration frequency is controlled at 50 Hz, the mold is filled with glue, the process is repeated 3 times, the positive pressure is maintained, the valves of four glue outlets 16 in the x direction of the mold are opened until there is no bubble in the liquid flowing out of the four glue outlets 16 in the x direction, the valve of one glue inlet 15 in the x direction and the valves of four glue outlets 16 in the x direction are closed, and the glue injection in the x direction is completed; after the glue injection is completed, the vibration mode of the heating vibrator is closed;

[0090] Step 4, the solidification and aging process is that the heating mode of the heating vibrator is opened, the temperature is set at 40℃, and the time is 50 min, the sol is rapidly solidified; the temperature is set at 40℃, and the time is 70 min, the sol is rapidly aged;

[0091] Step 5, the demolding process is that the mold is placed in the demolding working area, the screw is loosened, the male mold 8 is removed, the pneumatic telescopic push rod 23 is controlled to the retracted state, the detachable core and the fixed core inner convex structure can be quickly separated, the gel fiber preform block is separated from the mold, and then the carbon dioxide supercritical drying (drying temperature is 55℃, drying pressure is 14 MPa) is carried out to obtain the large-size curved rigid aerogel material. After the shape of the large-size curved rigid aerogel material is completed (curved surface), no delamination and incomplete filling phenomenon occurs, the fiber surface is wrinkle-free, the arc length is 324.5 mm, the curved surface radius is 155 mm, the angle of the curved surface bending arc is 120°, and the density is 0.24 g / cm 3 , the thermal conductivity at 1000℃ is 0.046 W / (m·K), and the compressive strength at 10% compression is 0.91 MPa.

[0092] Example 2

[0093] The steps of this example are basically the same as those of Example 1, except that only the valves of any two glue outlets 16 are opened when glue injection is performed in the z direction. The large-size curved rigid aerogel obtained in this example has no delamination and under-filled glue phenomenon after the shape is completed (curved), and the fiber surface has no wrinkles, with an arc length of 329.3 mm, a radius of 156 mm, an angle of the curved arc of the curved surface of 121°, and a density of 0.25 g / cm 3 The thermal conductivity at 1000°C is 0.053 W / (m·K), and the compressive strength at 10% compression is 0.72 MPa.

[0094] Example 3

[0095] The steps of this example are basically the same as those of Example 1, except that, during glue injection, the pressure is slowly increased at a rate of 0.2 MPa per minute, and the pressure is adjusted to 0.8 MPa to complete glue injection. The large-size curved rigid aerogel obtained in this example has no delamination and under-filled glue phenomenon after the shape is completed (curved), and the fiber surface has no wrinkles, with an arc length of 319.2 mm, a radius of 150 mm, an angle of the curved arc of the curved surface of 122°, and a density of 0.24 g / cm 3 The thermal conductivity at 1000°C is 0.050 W / (m·K), and the compressive strength at 10% compression is 0.89 MPa.

[0096] Comparative Example 1

[0097] The steps of this example are basically the same as those of Example 1, except that, during glue injection, glue injection is performed only in the z direction. The aerogel obtained in this example has small bulges on the edge of the upper surface, and cannot be used.

[0098] Comparative Example 2

[0099] The steps of this example are basically the same as those of Example 1, except that, during glue injection, the pressure is slowly increased at a rate of 0.2 MPa per minute, and the pressure is adjusted to 0.9 MPa to complete glue injection. The aerogel obtained in this example has wrinkles on the surface, and cannot be used.

[0100] Comparative Example 3

[0101] The steps of this example are basically the same as those of Example 1, except that, during glue injection, the vibration mode of the heating vibrator is not used, and glue injection is completed. The aerogel obtained in this example sometimes has bulges on the gel fiber preform, and the temperature of the thermal insulation performance test is slightly poor.

[0102] Compared with Example 1, the number of glue outlets of Example 2 is reduced, which does not affect the quality of the gel fiber preform block; the injection glue pressure of Example 3 is increased, the fiber preform does not slip, and the surface of the gel fiber preform block does not appear to be wrinkled. In Comparative Example 1, the gel fiber preform block cannot be used because of the small bulges on the edge of the upper surface of the gel fiber preform block due to the single direction injection of glue. In Comparative Example 2, the gel fiber preform block cannot be used because of the wrinkles on the surface of the gel fiber preform block due to the slippage of the fiber preform caused by the excessive injection glue pressure. In Comparative Example 3, the gel fiber preform block sometimes has bulges, the heat insulation performance test temperature is slightly poor, and a large number of air bubbles may exist in the gel fiber preform block and are not timely removed.

[0103] In the above examples, the description of each example is focused on, and the parts not described in detail in a certain example can be referred to the related description of other examples.

[0104] The numerical range described in the present application includes all the numerical values in the range, and includes the range value composed of any two numerical values in the range. The different numerical values of the same index appearing in all the examples of the present application can be combined to form a range value.

[0105] The technical features in the claims and / or the specification of the present application can be combined, and the combination manner is not limited to the combination obtained by reference relationship in the claims. The technical solution obtained by combining the technical features in the claims and / or the specification is also within the protection scope of the present application.

[0106] The above is only the preferred embodiment of the present application, and does not limit the present application in any form. Any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present application are still within the scope of the technical solution of the present application.

Claims

1. A forming method of a large-sized curved rigid aerogel material, characterized by, The method comprises the following steps: S1: Sol preparation: a two-step acid-base method is used to prepare the sol; S2: Molding: start the pneumatic telescopic push rod to the stretching state, assemble the detachable core and the inner convex structure of the fixed core to form the mold forming cavity; cut the fiber preform to the size of the mold forming cavity, then lay the fiber preform flat in the mold forming cavity; then fix the assembled female mold and male mold with screws to complete the assembly of the fiber preform; S3: Gel injection: in x and z dimensions, multiple vacuum and pressure assisted impregnation is used; the vibration mode is turned on during the injection, the vibration direction is consistent with the injection direction, and the vibration frequency is controlled between 40Hz and 60Hz; S4: Curing and aging: curing and aging are performed by heating; the heating temperature is 40℃-60℃, the curing time is 30min-60min, and the aging time is 60min-120min; S5: Demolding and drying: control the pneumatic telescopic push rod to the retracted state, separate the detachable core and the inner convex structure of the fixed core, make the gel fiber preform block demold smoothly, and then perform carbon dioxide supercritical drying; the drying temperature is 45℃-55℃, and the drying pressure is 10MPa-14MPa.

2. The forming method of large-sized curved rigid aerogel material according to claim 1, wherein In step S1, the preparation of the sol specifically includes: uniformly mixing and stirring the silicon source and the solvent according to the molar ratio; adjusting the pH value of the sol to 3-4 with an acidic catalyst, adding a basic catalyst to adjust the pH value of the sol to 6-7 after 4h-8h of reaction; the silicon source is selected from at least one of methyl orthosilicate, ethyl orthosilicate and water glass; the solvent is selected from at least one of water, anhydrous ethanol, methanol, glycerol and isopropanol; the acidic catalyst is selected from at least one of hydrochloric acid aqueous solution and nitric acid aqueous solution; the basic catalyst is selected from at least one of ammonia water and sodium hydroxide aqueous solution; the molar ratio of the solvent to the silicon source is (1-10):

1.

3. The forming method of large-sized curved rigid aerogel material according to claim 1, wherein In step S2, the fiber preform is selected from at least one of alumina fiber, mullite fiber, basalt fiber, glass fiber and high-silicon oxygen fiber, and has a density of 0.15g / cm3-0.2g / cm3; step S3 includes: vacuumizing the mold to a vacuum degree not less than -0.08MPa, and the vacuumizing time is not less than 1min; then pressurize at 0.1MPa-0.5MPa per minute to less than or equal to 0.8MPa, and the mold is filled with glue, this process is repeated 2-3 times, the positive pressure is maintained until there is no bubble in the liquid flowing out of the glue outlet, and the gel injection is completed.

4. A molding die for molding large-size curved rigid aerogel materials for implementing the method according to any one of claims 1-3, characterized in that, The forming mold comprises: a male mold; an assembled female mold fixedly connected with the male mold, and a forming cavity is formed between the assembled female mold and the male mold.

5. The forming mold for large size curved rigid aerogel material of claim 4, wherein, The convex part of the male mold and the concave part of the assembled female mold form a forming cavity for placing the fiber preform; a plurality of heating vibrators are uniformly distributed on the male mold and the assembled female mold; the side wall of the male mold has a plurality of heating vibrator holes, the side wall of the assembled female mold has a plurality of heating vibrator holes, and a heating vibrator is respectively placed in the plurality of heating vibrator holes of the male mold and the assembled female mold.

6. The forming mold for large size curved rigid aerogel material of claim 5, wherein, The four peripheral edges of the male mold have a plurality of threaded holes, and the middle of each threaded hole has a mold opening hole; each threaded hole has a screw matched therewith, and each mold opening hole has a screw matched therewith; the side wall of the assembled female mold has a thermocouple hole in which a thermocouple is placed, and the thermocouple is connected with a heating vibrator.

7. The forming mold for large scale curved rigid aerogel materials of claim 4, wherein, The bottom and the side wall of the assembled female mold have glue injection holes; the top of the male mold has a plurality of glue outlet holes, and the side wall of the assembled female mold has a glue outlet hole; the four peripheral side walls of the assembled female mold are further provided with a plurality of pneumatic telescopic push rods for facilitating demolding, a plurality of lifting rings for facilitating assembly and disassembly, and a plurality of handles.

8. The forming mold for large scale curved rigid aerogel material of claim 4, wherein, The assembled female mold comprises a detachable core and a fixed core, the side wall of the fixed core is provided with a plurality of pneumatic telescopic push rods, and the pneumatic telescopic push rods are connected with the detachable core through a mortise and tenon structure; the fixed core is in the shape of a concave curved surface, and is assembled with the detachable core to form a curved female mold; the male mold is in the shape of a convex curved surface, and is connected with the assembled female mold through screws to form a curved forming cavity; the inner surfaces of the male mold and the assembled female mold are both provided with a polytetrafluoroethylene coating with a thickness of 20 microns to 50 microns.

9. The forming mold for large scale curved rigid aerogel materials of claim 8, wherein, The detachable core comprises a plurality of cuboid female mold modules arranged in sequence, and each female mold module has a pneumatic telescopic push rod matched therewith; the fixed core has a groove around the periphery for placing the detachable core, and the thickness of the detachable core is smaller than the width of the groove; each female mold module has a plurality of assembly holes in the length direction, and each assembly hole has a screw matched therewith; the assembled female mold is provided with a sealing groove around the periphery, and the sealing groove is provided with a sealing ring.

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