Forming die and method for large-size curved-surface rigid aerogel material

Abstract

The invention relates to a forming die and method for a large-size curved-surface rigid aerogel material. The forming die of the large-size curved-surface rigid aerogel material comprises a male die and a female die, and the assembly type female die is fixedly connected with the male die, and a forming cavity is formed between the assembly type female die and the male die. According to the method, the mode of multiple times of vacuumizing and pressurization auxiliary impregnation is adopted in the x dimension and the z dimension, it is guaranteed that a fiber preform is fully impregnated, surface wrinkles generated on a formed aerogel material are solved by adjusting the pressurization degree and the impregnation speed, bubbles generated in a mold are removed in an auxiliary mode through a heating vibrator, and the product quality is improved. The matching precision of the aerogel material and other components is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of aerogel materials, and in particular to a molding die and a molding method for a large-size curved rigid aerogel material. Background Art

[0002] With the advancement of science and technology and the development of industry, the requirements for material performance are getting higher and higher, especially in large-scale curved structures that need to withstand complex loads and harsh environments. The selection of materials is particularly important. Aerogel is a new type of thermal insulation material. Since the gas phase accounts for a very high proportion in aerogel, it greatly reduces solid-phase heat transfer compared to traditional thermal insulation materials. At the same time, nano-scale pores also have a significant inhibitory effect on gas heat transfer. Therefore, it has been widely used in high-end manufacturing fields such as aerospace, automobiles, ships, and wind power.

[0003] Aerogel material molding technology usually uses resin transfer molding (RTM for short). RTM is a process in which resin is injected into a closed mold, infiltrated into the reinforcing material, and then solidified. It can produce composite materials with accurate thickness and good appearance quality. Although RTM technology has shown many advantages in the manufacture of components, it still faces some technical challenges. Mold design and manufacturing is one of the key technologies that need to be broken through. The molding mold determines the shape, size and matching accuracy of the composite component with other components. It is a key factor in ensuring product quality, improving production efficiency and reducing costs. Due to its complex structure, the structural composition of the mold needs to be considered comprehensively. Defects are prone to occur during the molding process, such as bubbles, delamination, etc., and a series of problems such as demolding after molding. Summary of the invention

[0004] In view of this, the main purpose of the present invention is to provide a molding mold and method for large-sized curved rigid aerogel materials. The problem to be solved is to ensure that the fiber preform is fully impregnated by adopting multiple vacuuming and pressurization-assisted impregnation methods in the x and z dimensions, and to solve the surface wrinkles of the molded aerogel material by adjusting the pressurization size and the impregnation speed. The bubbles generated in the mold are removed with the assistance of a heating vibrator, which greatly improves the matching accuracy of the aerogel material and other components.

[0005] The purpose of the present invention and the technical problem to be solved are achieved by adopting the following technical solutions. The present invention proposes a molding die for a large-sized curved rigid aerogel material, the molding die comprising:

[0006] Male mold;

[0007] The assembled female mold is fixedly connected to the male mold, and a molding cavity is formed between the assembled female mold and the male mold.

[0008] The purpose of the present invention and the solution to its technical problems can be further achieved by adopting the following technical measures.

[0009] Preferably, in the aforementioned large-size curved rigid aerogel material forming mold, the protrusion of the male mold and the recess of the assembled female mold form a forming cavity for placing the fiber preform.

[0010] Preferably, the aforementioned large-size curved rigid aerogel material forming mold further includes a plurality of heating vibrators which are evenly distributed on the male mold and the assembled female mold.

[0011] Preferably, in the aforementioned molding mold for large-sized curved rigid aerogel material, 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 heating vibrators are respectively placed in the plurality of heating vibrator holes of the male mold and the assembled female mold.

[0012] Preferably, in the aforementioned forming mold for large-size curved rigid aerogel material, the edges of the male mold have a plurality of threaded holes, and the middle of the plurality of threaded holes has a plurality of mold opening holes; the plurality of threaded holes respectively have screws matching therewith, and the four mold opening holes respectively have screws matching therewith.

[0013] Preferably, in the aforementioned large-size curved rigid aerogel material forming mold, 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 a heating vibrator.

[0014] Preferably, in the aforementioned large-size curved rigid aerogel material forming mold, the bottom and side walls of the assembled female mold both have glue injection holes.

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

[0016] Preferably, in the aforementioned large-size curved rigid aerogel material forming mold, the surrounding side walls of the assembled female mold are also provided with a plurality of pneumatic telescopic push rods for easy demoulding, a plurality of lifting rings for easy loading and unloading, and a plurality of handles.

[0017] Preferably, in the aforementioned forming mold for large-size curved rigid aerogel materials, the assembled female mold includes a detachable core and a fixed core, a plurality of pneumatic telescopic push rods are arranged on the side wall of the fixed core, and the plurality of pneumatic telescopic rods are connected to the detachable core through a mortise and tenon structure.

[0018] Preferably, in the aforementioned molding mold for large-size curved rigid aerogel materials, the fixed core is in the shape of a concave curved surface, which is assembled with the detachable core as a whole to form a curved female mold; the male mold is in the shape of a convex curved surface, and the male mold is connected to the assembled female mold by screws to form a curved molding cavity.

[0019] Preferably, in the aforementioned large-size curved rigid aerogel material forming mold, the inner surfaces of the male mold and the assembled female mold are both coated with polytetrafluoroethylene, and the thickness thereof is 20 microns to 50 microns.

[0020] Preferably, in the aforementioned large-size curved rigid aerogel material forming mold, the detachable core comprises a plurality of rectangular female mold modules arranged in sequence, and each of the female mold modules has a corresponding pneumatic telescopic push rod.

[0021] Preferably, in the aforementioned large-size curved rigid aerogel material forming mold, the fixed core has grooves around it for placing the detachable core, and the thickness of the detachable core is smaller than the width of the groove.

[0022] Preferably, in the aforementioned large-size curved rigid aerogel material forming mold, each of the female mold modules has a plurality of assembly holes in its length direction, and most of the assembly holes have screws matching therewith.

[0023] Preferably, in the aforementioned large-size curved rigid aerogel material forming mold, the assembled female mold is provided with sealing grooves around it, and a sealing ring is provided in the sealing groove.

[0024] The purpose of the present invention and the solution to its technical problems can also be achieved by adopting the following technical solutions. A molding method of a large-sized curved rigid aerogel material proposed in the present invention comprises the following steps:

[0025] S1 sol preparation: The sol was prepared by the acid-base two-step method;

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

[0027] S3 glue injection: multiple vacuum and pressurization are used to assist glue dipping in the x and z dimensions;

[0028] S4 curing and aging: curing and aging by heating;

[0029] S5 demoulding and drying: Control the pneumatic telescopic push rod to the contracted state to separate the detachable core from the inner convex structure of the fixed core, so that the gel fiber prefabricated block can be demoulded smoothly, and then carbon dioxide supercritical drying is carried out.

[0030] The purpose of the present invention and the solution to its technical problems can be further achieved by adopting the following technical measures.

[0031] Preferably, in the aforementioned molding method of large-size curved rigid aerogel material, in step S1, the preparation of the sol specifically includes: fully mixing the silicon source and the solvent in a molar ratio and stirring them uniformly; adjusting the pH value of the sol to 3-4 with an acidic catalyst, reacting for 4h-8h, and then adding an alkaline catalyst to adjust the pH value of the sol to 6-7.

[0032] Preferably, in the aforementioned method for forming a large-size curved rigid aerogel material, in step S1, 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 an aqueous hydrochloric acid solution and an aqueous nitric acid solution; the alkaline catalyst is selected from at least one of an aqueous ammonia solution and an aqueous sodium hydroxide solution; and the molar ratio of the solvent to the silicon source is (1 to 10):1.

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

[0034] Preferably, in the aforementioned molding method of large-size curved rigid aerogel material, step S3 comprises: evacuating the mold to a vacuum degree of not less than -0.08 MPa, and the vacuuming time is not less than 1 min; then increasing the pressure by 0.1 MPa to 0.5 MPa per minute to less than or equal to 0.8 MPa, and filling the mold with glue, and repeating this process 2-3 times, maintaining positive pressure, until the liquid flows out of the glue outlet without bubbles, and the glue injection is completed.

[0035] Preferably, in the aforementioned method for forming a large-sized curved rigid aerogel material, in step S3, 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 40 Hz and 60 Hz.

[0036] Preferably, in the aforementioned method for forming a large-sized curved rigid aerogel material, in step S4, the heating temperature is 40°C to 60°C, the curing time is 30min to 60min, and the aging time is 60min to 120min.

[0037] Preferably, in the aforementioned method for forming a large-sized curved rigid aerogel material, in step S5, the drying temperature is 45° C. to 55° C., and the drying pressure is 10 MPa to 14 MPa.

[0038] By means of the above technical solution, the present invention provides a large-size curved rigid aerogel material forming mold and method, which has at least the following advantages:

[0039] 1. The present invention significantly improves the impregnation effect of the fiber preform by using multiple vacuuming and pressurization to assist the impregnation in the x and z dimensions. This method not only ensures that the fiber preform is fully and evenly impregnated, but also effectively solves the problem of surface wrinkles that are prone to occur in the traditional aerogel material molding process by adjusting the pressurization size and the impregnation speed. The reduction of such wrinkles 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 present invention also cleverly introduces a step of using a heating vibrator to assist in removing bubbles generated in the mold, which greatly reduces the internal defects of the aerogel material caused by the presence of bubbles during the preparation process, and greatly improves the matching accuracy of the aerogel material with other components.

[0040] 2. The mold provided by the present invention is designed with an assembled female mold module, a male and female film heating vibrator, and a pneumatic telescopic push rod. The mold has a simple structure and successfully solves the problems of bubble accumulation and demoulding difficulties generated during the molding process, improves the flexibility of the mold, and facilitates the maintenance and replacement of the mold. The present invention integrates multiple processes such as molding, heating curing and aging into the mold to achieve integrated operation. This makes the operation simpler, not only improves the continuity and stability of production, ensures the consistency of product quality, but also effectively reduces production costs and maintenance costs.

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

[0042] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the preferred embodiments of the present invention are described in detail as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a three-dimensional structural diagram of a molding die for a large-sized curved rigid aerogel according to an embodiment of the present invention;

[0044] Figure 2 It is a three-dimensional structural diagram of a large-sized curved rigid aerogel assembled female mold fixed core according to an embodiment of the present invention;

[0045] Figure 3 It is a three-dimensional structural diagram of a large-sized curved rigid aerogel assembled female mold with a detachable core according to an embodiment of the present invention;

[0046] Figure 4 This is a three-dimensional assembly diagram of a large-scale curved rigid aerogel according to an embodiment of the present invention;

[0047] Figure 5 This is a process flow chart of large-size curved rigid aerogel according to an embodiment of the present invention. DETAILED DESCRIPTION

[0048] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description of the specific implementation, structure, characteristics and effects of a large-size curved rigid aerogel material forming mold and method proposed by the present invention in combination with the preferred embodiment. In the following description, different "one embodiment" or "embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

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

[0050] like Figure 1-Figure 4 As shown, some embodiments of the present invention provide a molding die for a large-sized curved rigid aerogel material, comprising:

[0051] Male mold 8;

[0052] The assembled female mold 9 is fixedly connected to the male mold 8, and a molding 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 depression of the assembled female mold 9 form a molding cavity for placing the fiber preform 10 to prepare the rigid aerogel material. In the process of preparing the rigid aerogel material, the fiber preform is used to strengthen the aerogel material.

[0054] In some optional embodiments, the male mold 8 has twelve threaded holes 11 on its four edges, and four mold opening holes 12 in the middle of the twelve threaded holes 11, so as to facilitate the disassembly of the male mold 8; the twelve threaded holes 11 respectively have screws matching therewith, and the four mold opening holes 12 respectively have screws matching therewith; during the molding process, the male mold 8 and the assembled female mold 9 are assembled together by 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 optional embodiments, the side wall of the male mold 8 has six heating vibrator holes 13, the side wall of the assembled female mold 9 has six heating vibrator holes 13, and the twelve heating vibrator holes 13 are respectively provided with heating vibrators to achieve the purpose of rapid degassing and all-round heating in the process of preparing rigid aerogel materials.

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

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

[0058] In some optional 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 one glue outlet hole 16. These glue outlet holes 16 are used to assist in removing bubbles and avoid defects during the glue injection process.

[0059] In some optional embodiments, four pneumatic telescopic push rods 23 for easy demoulding, four lifting rings 17 for easy loading and unloading, and eight handles 18 are also provided on the surrounding side walls of the assembled female mold 9.

[0060] In some optional embodiments, the assembled female mold 9 includes a detachable core 21 and a fixed core 20, the detachable core 21 includes four rectangular female mold modules arranged in sequence, each of the female mold modules has a corresponding pneumatic telescopic push rod 23, the four pneumatic telescopic rods 23 are arranged on the side wall of the fixed core 20, and the four pneumatic telescopic rods 23 are connected to the detachable core 21 through a mortise and tenon structure to provide power for loading and unloading the female mold modules; in addition, the edges of the edge joints of each female mold module need to be precisely processed to form a circular chamfer with a radius of 0.5 cm, which is convenient for loading and unloading the female mold modules and removing bubbles.

[0061] In some optional embodiments, the fixed core 20 is provided with grooves around it for placing the removable core 21. The thickness of the removable core 21 is 5 cm, and the width of the groove is 7 cm, which provides a telescopic space for the pneumatic telescopic push rod 23, thereby avoiding damage to the gel fiber preform (the injection has been completed) during the demolding process.

[0062] In some optional embodiments, each of the female mold modules has two assembly holes 22 in the length direction thereof, which facilitates the loading and unloading of the female mold module 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. Figure 3 , the two assembly holes 22 both have screws that match them.

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

[0064] In some optional embodiments, the inner surfaces of the male mold 8 and the assembled female mold 9 are both coated with polytetrafluoroethylene, and the thickness is 20 microns to 50 microns. When the coating thickness is less than 20 microns, it is too thin, which will affect its anti-corrosion and corrosion resistance and cannot effectively protect the mold; if it is greater than 50 microns, the coating thickness is too thick, which will affect its wear resistance, corrosion resistance and other properties, thereby shortening the service life. Too thin or too thick may affect demolding; in the mold manufacturing process, polytetrafluoroethylene coating is plated on the inner surface of the mold to prevent the gel fiber preform from sticking and adhering to the mold surface, thereby reducing mold pollution, increasing the service life of the mold, and reducing the impact on the appearance and internal quality of the gel fiber preform.

[0065] In some optional embodiments, sealing grooves 19 are provided around the assembled female mold 9, and sealing rings are provided in the sealing grooves 19; after the male mold 8 and the assembled female mold 9 are closed, the sealing rings are placed in the sealing grooves 19 for sealing, which helps to prevent the fiber preform from leaking during the glue injection process and ensure the quality and integrity of the gel fiber preform.

[0066] In the above technical scheme, the present invention adopts the method of assembled female mold module to form the female mold molding cavity of the mold. The joint gap of the assembled female mold module can effectively solve the bubble accumulation generated during the molding process. A pneumatic telescopic push rod is designed in the fixed core of the assembled female mold. The pneumatic telescopic push rod can provide uniform pressure to ensure the uniform separation between the mold and the aerogel prefabricated block material. With the assembled female mold module, the problem of demoulding difficulty is successfully solved, the defects of the aerogel material in the molding process are avoided, and the yield rate of the aerogel material is greatly improved. The heating vibrator hole and the thermocouple hole are reserved in the female and male films of the mold to provide convenient operation for the curing and aging process of the aerogel material after the 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°, and the density is 0.22g / cm 3 ~0.26g / cm 3 The thermal conductivity at 1000°C is 0.040W / (m·K)~0.065W / (m·K), and the compressive strength at 10% compression is 0.5MPa~1MPa.

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

[0069] Step 1, sol preparation process: prepare the sol by the acid-base two-step method, and mix the silicon source and the solvent in a molar ratio and stir them evenly. Then, adjust the pH value of the sol to 3-4 with an acidic catalyst, react for 4h-8h, and then add an alkaline catalyst to adjust the pH value of the sol to 6-7. 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, isopropanol, 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 water, sodium hydroxide aqueous solution, etc.; wherein the molar ratio of the solvent to the silicon source is (1-10):1.

[0070] Step 2: Mold loading process: Start the pneumatic telescopic push rod 23 to the stretched state, and move the detachable core 21 and the inner convex structure of the fixed core 20 into the same position. Figure 4direction to form a mold forming cavity, cut the fiber preform to a size that fits the mold forming cavity; lay the cut fiber preform flat in the mold forming cavity, and the male and female molds can be positioned through the threaded holes 11 to ensure that the male and female molds can be accurately aligned when the molds are closed. Align the assembled female mold 9 and the male mold 8 according to the designed positioning structure, and ensure that all parts of the mold fit tightly to avoid gaps or misalignment. Fix the assembled female mold 9 and the male mold 8 with screws to complete the assembly of the fiber preform. The fiber preform is mainly used to enhance the strength and heat resistance of the aerogel to meet different insulation temperature requirements. The selected fiber preform can be one or more of alumina fiber, mullite fiber, basalt fiber, glass fiber, high silica fiber, etc., and its density can be 0.15g / cm 3 ~0.2g / cm 3 ;

[0071] Step 3, glue injection process: In the x and z dimensions, multiple vacuum and pressurization assisted dipping methods are used to ensure that the fiber preform is fully impregnated while increasing the exhaust points. First, the mold is vacuumed, and the vacuum degree is not less than -0.08MPa, and the vacuuming time is not less than 1min, which can effectively remove the air in the mold and the pores in the fiber preform, creating favorable conditions for the injection of sol; secondly, turn on the air pump and slowly increase the pressure at 0.1MPa~0.5MPa per minute, and the maximum does not exceed 0.8MPa, and the mold is filled with glue. Pressurization helps the sol to penetrate into every corner of the fiber preform faster to obtain a uniform gel fiber preform structure, but too high pressure (such as more than 0.8MPa) will cause the sol to be too fluid, resulting in wrinkles on the fiber preform when it moves in the mold, and deformation defects in the prepared gel fiber preform. This process is repeated 2-3 times to ensure that the sol can fully impregnate the fiber preform, and discharge the gas in the mold, maintain positive pressure, and complete the injection until the liquid flows out of the glue outlet without bubbles. During the process, the heating vibrator turns on the vibration mode, the vibration direction is consistent with the injection direction, and the vibration frequency is controlled at 40Hz~60Hz to obtain high-quality gel fiber preforms. When the vibration frequency is higher than 60Hz, it may cause the sol to produce too much foam, affecting the density and mechanical properties of the product; and when the vibration frequency is lower than 40Hz, it may not achieve the expected impregnation effect, which will also affect the quality of the product. The heating vibrator is placed in the heating vibrator hole 13 of the yin and yang membranes of the mold. The bubbles in the mold can be moved quickly by vibration and gathered at the position full of glue and the dead corner of the mold. Therefore, the glue outlet is designed at these positions, and the bubbles can be removed to avoid defects.

[0072] Step 4, curing and aging process: The mold is heated by a heating vibrator for rapid curing and aging. The curing temperature is controlled at 40℃~60℃, and this process takes 30min~60min; the temperature increase is conducive to the mutual collision and condensation of sol particles, which is basically inversely proportional to the gel time. If the temperature is greater than 60℃, the curing temperature is too high, which may cause the following problems: 1. Uneven and coarse structure: high temperature will cause the collision and condensation of sol particles to be too intense, resulting in uneven gel structure and even coarse particles, affecting the final performance of aerogel. 2. Gel cracking: Excessively high temperature may also produce greater internal stress, increasing the risk of gel cracking. If the temperature is less than 40℃ and the curing temperature is too low, it may lead to a slow gelation reaction: at low temperatures, the collision and condensation rate of sol particles will slow down, resulting in a prolonged gelation reaction time, and may even fail to completely form a gel. If the time is longer than 60 minutes, the excessively long curing time may cause the gel structure to become too tight, affecting its porosity and specific surface area, and thus resulting in decreased thermal insulation performance; and if the time is less than 30 minutes, the excessively short curing time may make the gel unable to be fully stabilized, resulting in poor performance and affecting subsequent use.

[0073] The aging temperature is controlled at 40℃~60℃, and the process is 60min~120min; aging helps to stabilize the gel structure and improve its performance. If the temperature is greater than 60℃, the aging temperature is too high, the evaporation of water inside the gel will be accelerated, causing the gel to shrink, which in turn affects its final performance and morphology; high temperature may also cause chemical reactions in certain components of the gel, resulting in changes in the properties of the gel and even destroying the gel structure. If the temperature is less than 40℃, the aging temperature is too low, the formation and stabilization process of the gel may become slow, extending the production cycle; at low temperatures, the molecular movement inside the gel slows down, which may be unfavorable for the tight arrangement of the gel structure and the improvement of performance. If the time is less than 60min, the aging time is insufficient, the gel may not be fully stable, and its internal network structure may not be strong enough, resulting in poor gel performance, such as low strength and insufficient porosity. If the time is greater than 120min, the aging time is too long, the gel structure may become too tight, the porosity is reduced, and the specific surface area is reduced, thereby affecting its thermal insulation performance. In addition, too long aging time may also increase production costs and energy consumption.

[0074] During the curing and aging process, in order to facilitate the heating of the mold, the heating vibrator is placed in the pre-designed heating vibrator hole 13. There are 12 heating vibrator holes 13 on the yin and yang membranes of the mold to achieve a full range of heating effects. In order to accurately control the heating process, the heating vibrator 13 is connected to the thermocouple placed in the thermocouple hole 14 of the mold. 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 a 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 achieving an efficient curing and aging process.

[0075] Step 5, demoulding and drying process: During demoulding, the pneumatic telescopic push rod 23 is controlled to a contracted state, and the inner convex structure of the detachable core and the fixed core can be quickly separated, so that the gel fiber prefabricated block can be demoulded smoothly (wet gel is obtained), and the internal structure collapse of the gel fiber prefabricated block edge caused by extrusion during demoulding is effectively avoided, and the stratification and damage caused are caused; then, carbon dioxide supercritical drying is carried out under the conditions of a drying temperature of 45°C to 55°C and a drying pressure of 10MPa to 14MPa to obtain the large-sized curved rigid aerogel material (curved surface). Selecting a drying temperature of 45°C to 55°C and a drying pressure of 10MPa to 14MPa can ensure that carbon dioxide reaches a 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 scheme, the present invention adopts multiple vacuum and pressurization assisted dipping methods in the x and z dimensions during the injection process to ensure that the fiber preform is fully impregnated and bubbles can be effectively removed. By adjusting the pressurization size and the dipping speed, the surface wrinkles of the molded aerogel material are solved. The bubbles generated in the mold are removed with the assistance of a heating vibrator, which greatly improves the matching accuracy of the aerogel material and other components.

[0077] The specific implementation methods of the present invention are further described in detail below in conjunction with the embodiments, but it should not be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by technicians in this field based on the above-mentioned contents of the present invention still fall within the scope of protection of the present invention.

[0078] Unless otherwise specified, the materials, reagents, etc. involved below are all commercially available products well known to those skilled in the art; unless otherwise specified, the methods described are all methods well known in the art. Unless otherwise defined, the technical terms or scientific terms used should have the common meanings understood by ordinary technicians in the field to which the present invention belongs.

[0079] The angle formula of the curved arc of the large-sized curved rigid aerogel material in the following Examples 1-3 is n=180l / (πr), where r is the radius; the arc length is l, which is measured by an electronic curved surface measuring instrument;

[0080] The density of the large-sized curved surface rigid aerogel material in the following Examples 1-3 is obtained by testing the mass and volume of the large-sized curved surface rigid aerogel material and by the ratio of the mass and volume;

[0081] The thermal conductivity of the large-sized curved rigid aerogel material in the following Examples 1-3 is measured by the water flow plate method according to YB / T4130;

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

[0083] Embodiment 1:

[0084] like Figure 5 As shown, this embodiment provides a method for forming a large-sized curved rigid aerogel material, comprising the following steps:

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

[0086] Step 2: The fiber preform is mullite fiber with a fiber density of 0.15 g / cm 3 , with a thickness of 15mm. Place the assembled female mold in the corresponding position. During the mold installation process, first assemble the fixed core 20 and the detachable core 21 together, open the pneumatic telescopic push rod 23 to the stretched state, and assemble the detachable core 21 and the inner convex structure of the fixed core 20 according to Figure 4 The fiber preform 10 is assembled in the direction of the mold to form a molding cavity, and the fiber preform is cut to fit the molding cavity of the mold; the cut fiber preform 10 is then laid flat in the molding cavity of the mold, and the male mold 8 of the mold is installed. The positioning bolt is used to ensure the position accuracy, and the assembled female mold 9 and the male mold 8 of the mold are fastened with screws to complete the assembly of the fiber preform and prepare for glue injection;

[0087] Step 3: During the glue injection process, the valves of all the glue injection ports 15 of the mold are closed, and the valves of all the glue outlets 16 of the mold are opened to check the air tightness of the mold. The vacuum degree is -0.09MPa. The vacuum degree is -0.08MPa within 3 minutes after the vacuum pumping is stopped. If the air tightness test is passed, glue injection can be carried out.

[0088] First, glue is injected in the z direction, all valves are closed, the valve of the glue outlet 16 in the z direction of the mold is opened, and the mold is evacuated to a vacuum degree of -0.08MPa for 1min; the valve of the glue outlet 16 in the z direction of the mold is closed, the valve of the glue injection port 15 in the z direction of the mold is opened, the air pump valve is opened, and the pressure is slowly increased at a rate of 0.2MPa per minute to 0.5MPa, and the heating vibrator is placed in the heating vibrator hole 13 reserved in the mold, the vibration mode of the heating vibrator is turned on, and it is adjusted to vibrate in the z direction. The vibration frequency is controlled at 50Hz, and the mold is filled with glue. This process is repeated 3 times, and the positive pressure is maintained. The valve of a glue outlet 16 in the z direction of the mold is opened until the liquid flows out of the glue outlet 16 in the z direction without bubbles, and the valve of a glue injection port 15 in the z direction and a valve of a glue outlet 16 in the z direction are closed to complete the glue injection in the z direction;

[0089] Secondly, glue is injected in the x direction. A valve of a glue injection port 15 in the x direction of the mold is opened, and 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 vibrate in the x direction, and the vibration frequency is controlled at 50 Hz. The mold is filled with glue. This process is repeated 3 times. The positive pressure is maintained. The valves of the four glue outlets 16 in the x direction of the mold are opened until there are no bubbles in the liquid flowing out of the four glue outlets 16 in the x direction. The valve of the glue injection port 15 in the x direction and the valves of the four glue outlets 16 in the x direction are closed to complete the glue injection in the x direction. After the glue injection is completed, the vibration mode of the heating vibrator is turned off.

[0090] Step 4: The curing and aging process is to turn on the heating mode of the heating vibrator, set the temperature at 40°C, and the time for 50 minutes to quickly cure the sol; set the temperature at 40°C and the time for 70 minutes to quickly age the sol;

[0091] Step 5, the demoulding process is to place the mold in the demoulding work area, loosen the screws, remove the mold male mold 8, control the pneumatic telescopic push rod 23 to the contracted state, and quickly separate the detachable core from the fixed core inner convex structure, so that the gel fiber prefabricated block is separated from the mold, and then the large-sized curved surface rigid aerogel material is obtained by supercritical drying with carbon dioxide (drying temperature is 55°C, drying pressure is 14MPa). After the shape of the large-sized curved surface rigid aerogel material is completed (curved), there is no stratification and insufficient glue filling, the fiber surface is wrinkle-free, the arc length is 324.5mm, the radius of the curve is 155mm, the angle of the curved arc is 120°, and the density is 0.24g / cm 3 The thermal conductivity at 1000°C is 0.046W / (m·K), and the compressive strength at 10% compression is 0.91MPa.

[0092] Example 2

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

[0094] Example 3

[0095] The steps of this embodiment are basically the same as those of embodiment 1, except that during the glue injection process, 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 the glue injection. After the appearance of the large-scale curved rigid aerogel obtained in this embodiment is completed (curved), there is no stratification or insufficient glue filling, and the fiber surface has no wrinkles. Its arc length is 319.2 mm, the radius is 150 mm, the angle of the curved arc is 122°, and the density is 0.24 g / cm 3 The thermal conductivity at 1000°C is 0.050W / (m·K), and the compressive strength at 10% compression is 0.89MPa.

[0096] Comparative Example 1

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

[0098] Comparative Example 2

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

[0100] Comparative Example 3

[0101] The steps of this comparative example are basically the same as those of Example 1, except that the injection is completed without using the vibration mode of the heating vibrator during the injection process. The gel fiber prefabricated block of the aerogel obtained in this comparative example sometimes has bulges, and the thermal insulation performance test temperature is slightly poor.

[0102] Compared with Example 1, the reduced number of glue outlets in Example 2 did not affect the quality of the gel fiber preform; the glue injection pressure in Example 3 was increased, the fiber preform did not slip, and no wrinkles appeared on the surface of the gel fiber preform. In Comparative Example 1, glue was injected in a single direction, and there was a small bulge on the upper surface of the edge of the gel fiber preform, which could not be used. In Comparative Example 2, the glue injection pressure was too high, the fiber preform slipped, and wrinkles appeared on the surface of the gel fiber preform, which could not be used. In Comparative Example 3, the gel fiber preform sometimes had bulges, and the thermal insulation performance test temperature was slightly poor, which may be due to the presence of a large number of bubbles in the gel fiber preform that were not removed in time.

[0103] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0104] The numerical range described in the present invention includes all the numerical values ​​within the range, and includes the range value formed by any two numerical values ​​within the range. Different numerical values ​​of the same indicator appearing in all embodiments of the present invention can be arbitrarily combined to form a range value.

[0105] The technical features in the claims and / or the specification of the present invention may be combined, and the combination is not limited to the combination obtained by reference 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 invention.

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

Claims

1. A molding die for a large-size curved rigid aerogel material, characterized in that: The molding die comprises: Male mold; The assembled female mold is fixedly connected to the male mold, and a molding cavity is formed between the assembled female mold and the male mold.

2. The molding die for large-size curved rigid aerogel material according to claim 1, characterized in that: The protrusion of the male mold and the depression of the assembled female mold form a molding cavity for placing the fiber preform; it also includes a plurality of heating vibrators, which are evenly distributed on the male mold and the assembled female mold; the side wall of the male mold has a plurality of heating vibrator holes, and the side wall of the assembled female mold has a plurality of heating vibrator holes, and the plurality of heating vibrator holes of the male mold and the assembled female mold are respectively provided with heating vibrators.

3. The molding die for large-size curved rigid aerogel material according to claim 2, characterized in that: The male mold has a plurality of threaded holes on the edges around it, and a plurality of mold opening holes are provided in the middle of the plurality of threaded holes; the plurality of threaded holes are provided with screws matching therewith, and the four mold opening holes are provided with screws matching therewith; 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.

4. The molding die for large-size curved rigid aerogel material according to claim 1, characterized in that: The bottom and side walls of the assembled female mold are provided with glue injection holes; the top of the male mold is provided with a plurality of glue outlet holes, and the side walls of the assembled female mold are provided with glue outlet holes; the surrounding side walls of the assembled female mold are also provided with a plurality of pneumatic telescopic push rods for convenient demoulding, a plurality of lifting rings for easy loading and unloading, and a plurality of handles.

5. The molding die for large-size curved rigid aerogel material according to claim 1, characterized in that: The assembled female mold includes a detachable core and a fixed core. A plurality of pneumatic telescopic push rods are arranged on the side wall of the fixed core, and the plurality of pneumatic telescopic push rods are connected to the detachable core through a mortise and tenon structure; the fixed core is in a concave curved shape, and is assembled with the detachable core to form a curved female mold; the male mold is in a convex curved shape, and is connected to the assembled female mold by screws to form a curved molding cavity; the inner surfaces of the male mold and the assembled female mold are both coated with polytetrafluoroethylene, and the thickness of which is 20 microns to 50 microns.

6. The molding die for large-size curved rigid aerogel material according to claim 5, characterized in that: The detachable core comprises a plurality of rectangular female mold modules arranged in sequence, each of the female mold modules having a corresponding pneumatic telescopic push rod; the fixed core is provided with grooves for placing the detachable core around it, and the thickness of the detachable core is smaller than the width of the groove; each of the female mold modules has a plurality of assembly holes in its length direction, and most of the assembly holes have screws matching therewith; the assembled female mold is provided with sealing grooves around it, and sealing rings are provided in the sealing grooves.

7. A method for forming a large-size curved rigid aerogel material, characterized in that: The following steps are involved: S1 sol preparation: The sol was prepared by the acid-base two-step method; S2 mold loading: start the pneumatic telescopic push rod to the stretched state, assemble the removable core and the inner convex structure of the fixed core to form a mold cavity; cut the fiber preform to a size that fits the mold cavity, and then lay the fiber preform flat in the mold cavity; then fix the assembled female mold and male mold with screws to complete the assembly of the fiber preform; S3 glue injection: multiple vacuum and pressurization are used to assist glue dipping in the x and z dimensions; S4 curing and aging: curing and aging by heating; S5 demoulding and drying: Control the pneumatic telescopic push rod to the contracted state to separate the detachable core from the inner convex structure of the fixed core, so that the gel fiber prefabricated block can be demoulded smoothly, and then carbon dioxide supercritical drying is carried out.

8. The method for forming a large-size curved rigid aerogel material according to claim 7, characterized in that: In step S1, the preparation of the sol specifically includes: mixing the silicon source and the solvent in a molar ratio and stirring them uniformly; adjusting the pH value of the sol to 3-4 with an acidic catalyst, reacting for 4h-8h, and then adding an alkaline catalyst to adjust the pH value of the sol to 6-7; 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 alkaline 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.

9. The method for forming a large-size curved rigid aerogel material according to claim 7, characterized in that: In step S2, the fiber preform is selected from at least one of alumina fiber, mullite fiber, basalt fiber, glass fiber and high silica fiber, and has a density of 0.15 g / cm 3 ~0.2g / cm 3 ; Step S3 includes: evacuating the mold to a vacuum degree of not less than -0.08MPa, and the vacuuming time is not less than 1min; then increasing the pressure by 0.1MPa~0.5MPa per minute to less than or equal to 0.8MPa, and filling the mold with glue. This process is repeated 2-3 times, maintaining positive pressure until liquid flows out of the glue outlet without bubbles, and the glue injection is completed.

10. The method for forming a large-sized curved rigid aerogel material according to claim 7, characterized in that: In step S3, 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; in step S4, the heating temperature is 40°C to 60°C, the curing time is 30min to 60min, and the aging time is 60min to 120min; in step S5, the drying temperature is 45°C to 55°C, and the drying pressure is 10MPa to 14MPa.

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