A composite cylinder with low thermal conductivity and high heat preservation at ultra-low temperature and a preparation method thereof

Abstract

The application discloses a composite cylinder with low heat conduction and high heat preservation at ultralow temperature and a preparation method, and belongs to the field of equipment materials. The cylinder preform is obtained through an integrated forming process, and the composite cylinder with low heat conduction and high heat preservation at ultralow temperature is obtained by impregnating the cylinder preform with a mixed solution obtained by mixing epoxy resin, aluminum oxide powder and a curing agent. The aluminum oxide powder is added to the epoxy resin, which improves the interface performance, reduces the leakage problem caused by the inconsistent thermal expansion coefficients of materials, and optimizes the performance. The aluminum oxide fiber reinforced resin matrix composite cylinder has low helium leakage rate at normal and low temperatures, high breaking strength at normal and low temperatures, and good liquid oxygen compatibility.

Description

Technical Field

[0001] This invention relates to a composite material cylinder with low thermal conductivity and high heat insulation at ultra-low temperatures and its preparation method, belonging to the field of equipment materials. Background Technology

[0002] With the rise of interstellar travel and deep space exploration, further improving the structural efficiency of launch vehicles has become a hot topic in the aerospace field. As the component with the largest weight and volume proportion in the propulsion system, the lightweighting level of the cryogenic fuel tank is a core factor in measuring the structural efficiency of a launch vehicle. Research shows that composite materials have higher specific strength and specific modulus than metallic materials, while also possessing excellent fatigue resistance. Composite material cryogenic fuel tanks can achieve a weight reduction target of 20%-40% compared to current aluminum alloy tanks, and the weight reduction effect becomes more significant as the tank size increases. To meet the cryogenic requirements of the tank, it is necessary to select composite materials that can maintain good performance at extremely low temperatures.

[0003] Currently, using lightweight, high-strength composite materials to replace traditional materials to reduce the weight of space launch vehicles and thus lower production costs is one of the key focuses of aerospace materials research. Among these, the materials and manufacturing processes of cryogenic composite tanks play a decisive role. Unlike traditional metal tanks, cryogenic composite tanks require special attention to leakage issues caused by crack propagation in the composite material at low temperatures, as well as consideration of suitable structural forms to achieve integrated structural and functional manufacturing of the tank.

[0004] There are two conventional methods for preparing cylindrical bodies: winding process and automatic fiber placement process. However, both of these processes can lead to problems such as mismatch in the thermal expansion coefficients of the polymer matrix and reinforcing fibers, as well as leakage of liquid helium and liquid nitrogen. This can cause large thermal stress inside the polymer matrix composite material in the ultra-low temperature environment, which can eventually lead to microcracks inside the composite material.

[0005] The development of materials for cryogenic storage tanks has progressed through stages involving metallic materials such as aluminum-magnesium alloys, aluminum-copper alloys, and aluminum-lithium alloys, and then to composite material shells with metal liners. Currently, the main research direction is the development of linerless composite material tanks. To meet the cryogenic requirements of storage tanks, composite materials that can maintain good performance at extremely low temperatures need to be selected. Common choices include glass fiber reinforced plastics (GFRP) and carbon fiber reinforced plastics (CFRP). However, these materials have poor resistance to ultra-low temperatures and poor mechanical properties at ultra-low temperatures.

[0006] Furthermore, most polymer materials undergo rapid chemical reactions when subjected to external forces such as impact, collision, and friction in a liquid oxygen environment, leading to ablation, combustion, or even explosion, demonstrating their incompatibility with liquid oxygen. The liquid oxygen compatibility of composite materials is closely related to the liquid oxygen compatibility of the resin matrix, and modifying the resin for liquid oxygen compatibility is fundamental to the preparation of composite materials for liquid oxygen storage tanks. Summary of the Invention

[0007] [Technical Issues]

[0008] Currently, cryogenic tanks made of composite materials have poor low-temperature impermeability; high manufacturing costs; and poor compatibility with liquid oxygen.

[0009] Microcracks initiation and propagation in low-temperature environments can lead to leakage of liquid helium and liquid hydrogen; the resistance to ultra-low temperatures and mechanical properties at ultra-low temperatures are poor.

[0010] [Technical Solution]

[0011] To address at least one of the aforementioned problems, this invention employs an integral molding process to weave a pre-formed cylindrical body; a mixed solution is prepared by mixing epoxy resin, alumina powder, and a curing agent; the pre-formed cylindrical body is then impregnated with this mixed solution to obtain a composite material cylindrical body exhibiting low thermal conductivity and high thermal insulation at ultra-low temperatures. This invention incorporates alumina powder into the epoxy resin, improving interfacial properties while reducing leakage issues caused by inconsistent thermal expansion coefficients of the materials, thus optimizing its performance. The alumina fiber-reinforced resin-based composite material cylindrical body of this invention exhibits low helium leakage rates and high fracture strength at both normal and low temperatures, and good liquid oxygen compatibility.

[0012] The first objective of this invention is to provide a method for preparing an alumina fiber-reinforced resin matrix composite cylinder with low thermal conductivity and high thermal insulation at ultra-low temperatures, comprising the following steps:

[0013] (1) Integrated woven cylinder prefabricated body:

[0014] First, alumina fiber is used as warp, weft, and knotting yarn to weave the top hemisphere of the cylinder in three dimensions using a four-step method. Then, the knotting yarn is cut, and the warp and weft yarns are woven through the straight section of the 2.5D cylinder. Finally, the outermost warp, weft, and knotting yarns are reconnected, and the bottom hemisphere of the cylinder is woven in three dimensions using a four-step method to obtain the final cylinder preform.

[0015] (2) Mix epoxy resin, alumina powder and curing agent to obtain a mixed solution;

[0016] (3) Immerse the precast cylinder in the mixed solution, remove it and cure it. Seal the top and bottom ports of the precast cylinder with flanges to obtain an alumina fiber reinforced resin matrix composite cylinder.

[0017] In one embodiment of the present invention, the diameter of the alumina fiber in step (1) is 4-30 μm.

[0018] In one embodiment of the present invention, the integrated weaving method described in step (1) is as follows:

[0019] The top hemisphere of the cylinder is woven in three dimensions using a four-step method, reducing the volume fraction of alumina fiber from 68-72% to 52-55%, and decreasing the weaving angle by 4-8° from the outside to the inside.

[0020] The straight section of the cylinder is woven using 2.5D weaving, with the volume fraction of alumina fiber fixed at 68%.

[0021] The bottom hemisphere of the cylinder is woven in three dimensions using a four-step method. The volume fraction of alumina fiber increases from 52-55% to 68-72%, and the weaving angle increases by 4-8° from the outside to the inside, ultimately resulting in the precast cylinder.

[0022] In one embodiment of the present invention, the flange in step (1) includes a flange plate, bolts, a sealing ring and a base; the flange plate is connected to the base by bolts; the cylindrical base is a ring structure with a groove, the upper part of which has a groove and a sealing ring in the groove, the sealing ring is made of polytetrafluoroethylene, and the upper protruding part of the sealing ring is directly connected to the flange plate to achieve sealing.

[0023] In one embodiment of the present invention, the alumina powder particle size in step (2) is 8-12 μm.

[0024] In one embodiment of the present invention, the mass ratio of epoxy resin, alumina powder and curing agent in step (2) is 10:2-4:5.

[0025] In one embodiment of the present invention, the curing agent in step (2) is diethanolamine.

[0026] In one embodiment of the present invention, the method for preparing the mixed solution in step (2) is as follows:

[0027] Add the curing agent to the container, slowly pour in the epoxy resin, and stir for 2-5 minutes at 25-35℃ and 100-500 r / min to ensure uniform mixing; slowly add the alumina powder to the mixture of curing agent and epoxy resin, and stir for 1-2 hours at 45-60℃ and 500-700 r / min to ensure that the alumina powder and epoxy resin are fully mixed, and finally obtain a mixed solution.

[0028] In one embodiment of the present invention, the curing in step (3) is performed at 140-160°C for 1.5-2.5 hours, at 260-300°C for 2.5-3.5 hours, and at 200-220°C for 2.5-3.5 hours.

[0029] In one embodiment of the present invention, the dimensions of the cylinder in step (1) are: overall length 970mm, cylinder diameter 700mm, straight section length 470mm, and cylinder thickness 10mm.

[0030] The second objective of this invention is to provide an alumina fiber reinforced resin matrix composite cylinder with low thermal conductivity and high heat insulation at ultra-low temperatures, which is prepared by the above method.

[0031] A third objective of this invention is to provide the application of the above-mentioned alumina fiber reinforced resin matrix composite cylinder with low thermal conductivity and high thermal insulation at ultra-low temperatures in cryogenic fuel tanks at temperatures of 77K-273K.

[0032] The fourth objective of this invention is to provide a cryogenic liquid helium, liquid hydrogen, and liquid nitrogen storage tank, which employs the aforementioned alumina fiber-reinforced resin matrix composite material cylinder that exhibits low thermal conductivity and high thermal insulation at ultra-low temperatures.

[0033] The fifth objective of this invention is to provide the application of the above-mentioned alumina fiber reinforced resin matrix composite cylinder with low thermal conductivity and high thermal insulation at ultra-low temperatures in the field of aerospace equipment.

[0034] [Beneficial Effects]

[0035] (1) Compared with traditional CFPR and GFPR cylinders, the alumina fiber reinforced resin matrix composite cylinder of the present invention has a lower thermal conductivity under the same temperature conditions and the thermal conductivity gradually increases and remains relatively stable as the temperature rises. It has a good low thermal conductivity and high heat preservation effect, which can effectively prevent the leakage of liquid nitrogen and liquid hydrogen, keep the temperature constant, and reduce energy consumption.

[0036] (2) The alumina fiber reinforced resin matrix composite cylinder prepared by the present invention has a liquid oxygen impact sensitivity of less than 15% and good liquid oxygen compatibility.

[0037] (3) The present invention adds alumina powder to epoxy resin, which improves the interfacial performance and reduces the leakage problem caused by the inconsistent thermal expansion coefficient of the materials, thus optimizing its performance.

[0038] (4) Compared with other traditional materials, the alumina fiber reinforced resin composite material prepared by the present invention has stronger resistance to ultra-low temperature and better mechanical properties in ultra-low temperature environment.

[0039] (5) The alumina fiber reinforced resin matrix composite cylinder of the present invention has excellent comprehensive mechanical properties. Through the three-dimensional preform forming process, it can realize the near-net-shape forming of large and complex component preforms, which can play an important role in improving the core indicators such as lightweight, reliability and mobility of the new generation of aerospace equipment. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the overall load of the alumina fiber reinforced resin matrix composite cylinder in Example 1; where 1 is the upper flange of the cylinder, 2 is the top hemisphere of the cylinder, 3 is the straight section of the cylinder, 4 is the lower flange of the cylinder, and 5 is the bottom hemisphere of the cylinder.

[0041] Figure 2 This is a schematic diagram of the structure of the flange portion 1 on the alumina fiber reinforced resin matrix composite cylinder of Example 1, where 101 is the flange, 102 is the bolt, 103 is the sealing ring, and 104 is the cylinder base.

[0042] Figure 3 This is a schematic diagram of the dimensions of the alumina fiber reinforced resin matrix composite cylinder in Example 1;

[0043] Figure 4 This is a diagram showing the position of the yarn carrier on the machine chassis after the four-step motion in Example 1;

[0044] Figure 5 This is a schematic diagram of the 2.5D weaving of the straight section of the bobbin in Example 1, where 6 is the warp yarn and 7 is the weft yarn. Detailed Implementation

[0045] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0046] Test method:

[0047] Permeability testing at normal and low temperatures:

[0048] Considering both safety and accuracy, the pressure difference method is used to test the material's leakage. The test is conducted on a permeability testing instrument according to ASTM D1434-82. The material to be tested is placed inside a fixture, which is divided into upper and lower parts. Helium is injected into the upper part using a high-pressure gas cylinder, while a vacuum pump is used to evacuate the lower part, creating a pressure difference across the material. This pressure difference, combined with the helium concentration difference, causes helium to pass through the material. A helium mass spectrometer leak detector is used to measure the leakage rate of the helium passing through the material. The helium leakage rate characterizes the material's permeability at room temperature. For cryogenic conditions, liquid nitrogen is used as the cooling medium (cooled to -196°C), and the pressure is increased by 3-5 atmospheres through nitrogen gas.

[0049] Liquid oxygen shock sensitivity test:

[0050] The liquid oxygen impact sensitivity test is a standard method for evaluating the liquid oxygen compatibility of materials. It is conducted on a liquid oxygen impact testing machine according to the American testing standard ASTM 2512-17. In the liquid oxygen impact sensitivity test, when the impact energy is set to 98J, if the tested material sample does not react in 20 impact tests, or if the aforementioned liquid oxygen incompatibility phenomenon occurs only once in 60 tests, the material is considered compatible with liquid oxygen. An appropriate weighting coefficient is assigned, comprehensively considering the reaction frequency and reaction intensity, to define the impact sensitivity index (IRS). The smaller the IRS value, the better the compatibility of the material with liquid oxygen.

[0051] Low temperature resistance test:

[0052] For testing low thermal conductivity, a section of the prepared alumina fiber reinforced resin matrix composite was cut off, and the transient thermal conductivity and specific heat capacity of the sample were measured using a TPS2200 thermal constant analyzer manufactured by HOT DISK GmbH of Sweden based on the transient plane method, in accordance with ISO22007-2.

[0053] Tensile test:

[0054] Tensile testing of the composite material was conducted according to the GB / T 1447-2005 test standard. The material was cut into dumbbell-shaped specimens along the warp direction. The tensile properties of the composite material were tested on an Instron 8801 electronic universal testing machine, where the stress and strain of the material were measured by an extensometer. The test temperatures were 25℃ and -200℃, with three specimens tested at each temperature, and the average value was taken.

[0055] Raw materials used in the examples:

[0056] Alumina fiber: long fiber, fineness 90tex, model F-72 alumina fiber, purchased from Shanghai Rongrong New Material Technology Co., Ltd.;

[0057] Epoxy resin: EP-301 waterborne epoxy resin, solid content 70%, viscosity 10000cps, density 1.6-2.3g / cm³ 3 ;

[0058] Alumina powder: particle size 8-12μm, aluminum content 99.5%, density 3.9-4.0g / cm³ 3 The source of the purchase was Shanghai Rongrong New Materials Technology Co., Ltd.

[0059] Alumina short fiber: 20μm in length, 225tex in fineness, model FR12-225 alumina fiber, purchased from Shanghai Rongrong New Material Technology Co., Ltd.;

[0060] Diethanolamine: Type 99-Diethanolamine;

[0061] Carbon fiber: T800 carbon fiber, with a diameter of 5-8μm and a density of 1.8-1.9g / cm³. 3 ;

[0062] Glass fiber: S-type glass fiber, diameter 8-20μm, length 12-25mm;

[0063] Silicon dioxide: CAS No.: 7631-86-9, density 2.684 g / cm³ 3 It has a purity of 98% and is a colorless and transparent crystal.

[0064] Example 1

[0065] A method for preparing an alumina fiber-reinforced resin matrix composite cylinder with low thermal conductivity and high thermal insulation at ultra-low temperatures includes the following steps:

[0066] (1) Alumina fiber is used for prefabricating the cylinder (e.g.) Figure 1 Integrated weaving:

[0067] Using alumina fiber as warp, weft, and splicing yarn, a four-step three-dimensional weaving process is employed to weave the top hemisphere 2 of the bobbin. During the weaving of the top hemisphere 2, the yarn carriers in adjacent rows alternately move one position along the X-direction, and the yarn carriers in adjacent columns alternately move one position along the Y-direction. Next, the movement directions of the yarn carriers are reversed from the previous two steps. After these four steps, the yarn carriers are restored to their original positions on the machine chassis (e.g., ...). Figure 3 As shown), one machine cycle is completed; during this process, the volume fraction of alumina fiber decreases from 70% to 54%, and the weaving angle decreases by 6° from the outside to the inside every other layer;

[0068] Afterwards, the spliced ​​yarn is cut, and the volume fraction of alumina fiber is fixed at 68%. The warp and weft yarns pass through the straight section 3 of the 2.5D braided bobbin; as shown... Figure 4 As shown;

[0069] Alumina fibers are arranged and woven in both circumferential and axial directions. When weaving to the bottom hemisphere 5 of the cylinder, the outermost warp and weft yarns are reconnected with the knotting yarns. A four-step three-dimensional weaving process is used to weave the bottom hemisphere 5 of the cylinder. During this process, the volume fraction of alumina fibers increases from 54% to 70%, and the weaving angle increases by 6° from the outside to the inside for every layer. Finally, the cylinder preform is obtained.

[0070] (2) Add 50g of diethanolamine to a clean container, slowly pour in 100g of epoxy resin, and stir at 30℃ and 300r / min for 5min to ensure that it is mixed evenly, so as to obtain a mixture of diethanolamine and epoxy resin; slowly add 20g of alumina powder to the mixture of diethanolamine and epoxy resin, and stir at 50℃ and 600r / min for 1.5hmin to ensure that the alumina powder and epoxy resin are fully mixed, and finally obtain a mixed solution;

[0071] (3) Using RTM process, the preformed cylinder is placed into the mold, and then placed in the oven to dry at 100℃ for 2 hours; use gauze dipped in alcohol to clean and wipe the upper and lower surfaces of the mold and the screw holes of the glue inlet and outlet to keep them clean and transparent;

[0072] (4) Inject the mixed solution into the mold until the mixed solution fills the entire mold and the dispensing tube, and completely impregnates the preformed cylinder. Stop injecting, maintain pressure, remove the connecting device, and put the mold into the oven to cure at 150°C for 2 hours, at 280°C for 3 hours, and at 210°C for 3 hours.

[0073] (5) After cooling at room temperature for 2.5 hours, the mold is removed. The upper and lower ports of the precast cylinder are sealed using the upper flange part 1 and the lower flange part 4 to obtain an alumina fiber reinforced resin matrix composite cylinder. The lower flange part 4 and the upper flange part 1 have the same structure. The upper flange part 1 is as follows: Figure 2 As shown, it includes a flange 101, bolts 102, a sealing ring 103, and a cylindrical base 104; the flange 101 is connected to the cylindrical base 104 by bolts 102; the cylindrical base is a ring structure with a groove, the ring height is 20mm, the upper part has a groove, and the groove contains a sealing gasket 103 made of polytetrafluoroethylene. The upper protruding part of the sealing ring 103 is directly connected to the flange 101 to achieve a seal.

[0074] Example 2

[0075] Adjust the mass of alumina powder in step (3) of Example 1 to 30g;

[0076] Other conditions and parameters remained the same as in Example 1, resulting in an alumina fiber reinforced resin matrix composite cylinder.

[0077] Compare with Example 1

[0078] Replace the Al2O3 fiber in step (1) with carbon fiber;

[0079] Other conditions and parameters remained the same as in Example 1, resulting in a carbon fiber reinforced resin matrix composite (CFRP) cylinder.

[0080] Compare with Example 2

[0081] Replace the Al2O3 fiber in step (1) with glass fiber;

[0082] Other conditions and parameters remained consistent with those in Example 1, resulting in a glass fiber reinforced resin matrix composite cylinder (GFRP).

[0083] Compare with Example 3

[0084] Remove the alumina powder from step (3) of Example 1;

[0085] Other conditions and parameters remained the same as in Example 1, resulting in an alumina fiber reinforced resin matrix composite cylinder.

[0086] Compare with Example 4

[0087] Adjust the mass of alumina powder in step (3) of Example 1 to 10g;

[0088] Other conditions and parameters remained the same as in Example 1, resulting in an alumina fiber reinforced resin matrix composite cylinder.

[0089] Compare with Example 5

[0090] Adjust the mass of alumina powder in step (3) of Example 1 to 50g;

[0091] Other conditions and parameters remained the same as in Example 1, resulting in an alumina fiber reinforced resin matrix composite cylinder.

[0092] Compare with Example 6

[0093] The particle size of the alumina powder in step (3) of Example 1 was adjusted to 15 μm;

[0094] Other conditions and parameters remained the same as in Example 1, resulting in an alumina fiber reinforced resin matrix composite cylinder.

[0095] Compare with Example 7

[0096] Replace the alumina powder in step (3) of Example 1 with silicon dioxide;

[0097] Other conditions and parameters remained the same as in Example 1, resulting in an alumina fiber reinforced resin matrix composite cylinder.

[0098] Compare with Example 8

[0099] Replace the alumina powder in step (3) of Example 1 with alumina short fibers;

[0100] Other conditions and parameters remained the same as in Example 1, resulting in an alumina fiber reinforced resin matrix composite cylinder.

[0101] Compare with Example 9

[0102] The preparation of the cylindrical body using fiber winding technology includes the following steps:

[0103] Alumina fibers are impregnated in epoxy resin at room temperature for 1.5 hours to allow the fibers to fully absorb the epoxy resin, thus obtaining resin-impregnated alumina fibers.

[0104] After the composite mandrel (upper hemisphere, lower hemisphere, and straight cylinder) is assembled, it is placed on a winding machine. The resin-impregnated alumina fibers are wound in a circumferential manner until the set number of layers (2 layers) is reached, and then the winding is stopped to form a winding layer.

[0105] Then, it is cured in a curing oven at 200℃ for 2 hours. After curing, the core mold is removed to obtain the alumina fiber reinforced resin matrix composite cylinder.

[0106] Compare with Example 10

[0107] The preparation of the cylindrical body using automated fiber placement technology includes the following steps:

[0108] (1) Mix epoxy resin and curing agent at a mass ratio of 10:3 at 30℃ and 300r / min for 5 minutes to ensure uniform mixing; apply the mixed epoxy resin onto alumina fibers at a coating density of 1.6g / cm³. 2 After coating, it is cured at 140℃ for 1.5 hours to obtain prepreg;

[0109] (2) The prepreg is fed into the filament laying head, 14 filaments are fed in at a time, and the filament bundles are individually pulled into the filament straightening device and then passed down through the filament pressing device; finally, the filament bundles are passed through the filament shearing device and enter the pressure roller; at the same time, inert gas nitrogen is used as a heat source to heat the filament bundles with hot air; the hot air temperature is 150℃ and the hot air rate is 3500r / min to make the filament bundles heated evenly; finally, an alumina fiber reinforced resin matrix composite cylinder is obtained.

[0110] The alumina fiber-reinforced resin matrix composite cylinders obtained in Examples 1-2 and Comparative Examples 1-10 were subjected to performance tests, and the test results are shown in Table 1:

[0111] Table 1

[0112]

[0113] As can be seen from Table 1, the alumina fiber reinforced resin matrix composite cylinders prepared in Examples 1-2 have low helium leakage rates and high fracture strength at normal and low temperatures, and good liquid oxygen compatibility.

[0114] The thermal conductivity of the alumina fiber-reinforced resin matrix composite cylinders obtained in Examples 1-2 and Comparative Examples 1-10 was tested at 77K, 170K, and 273K, respectively. The test results are shown in Table 2.

[0115] Table 2

[0116]

[0117]

[0118] As can be seen from Table 2, the thermal conductivity of the alumina fiber reinforced resin matrix composite cylinder prepared in Examples 1-2 is low and gradually increases with increasing temperature, remaining relatively stable.

[0119] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for preparing an alumina fiber-reinforced resin matrix composite cylinder with low thermal conductivity and high thermal insulation at ultra-low temperatures, characterized in that, Includes the following steps: (1) Integrated woven cylinder prefabricated body: First, alumina fiber is used as warp, weft, and knotting yarn to weave the top hemisphere of the cylinder in three dimensions using a four-step method. Then, the knotting yarn is cut, and the warp and weft yarns are woven through the straight section of the 2.5D cylinder. Finally, the outermost warp, weft, and knotting yarns are reconnected, and the bottom hemisphere of the cylinder is woven in three dimensions using a four-step method to obtain the final cylinder preform. The integrated weaving method is as follows: The top hemisphere of the cylinder is woven in three dimensions using a four-step method, reducing the volume fraction of alumina fiber from 68-72% to 52-55%, and decreasing the weaving angle by 4-8° from the outside to the inside. The straight section of the cylinder is woven using 2.5D weaving, with the volume fraction of alumina fiber fixed at 68%. The bottom hemisphere of the cylinder is woven in three dimensions using a four-step method. The volume fraction of alumina fiber increases from 52-55% to 68-72%, and the weaving angle increases by 4-8° from the outside to the inside, ultimately resulting in the precast cylinder. (2) Mix epoxy resin, alumina powder, and curing agent to obtain a mixed solution; (3) Immerse the precast cylinder in the mixed solution, remove it and cure it. Use flanges to seal the top and bottom ports of the precast cylinder to obtain an alumina fiber reinforced resin matrix composite cylinder.

2. The method according to claim 1, characterized in that, The diameter of the alumina fiber described in step (1) is 4-30 μm.

3. The method according to claim 1, characterized in that, In step (1), the flange includes a flange plate, bolts, a sealing ring, and a cylindrical base. The flange plate is connected to the cylindrical base by bolts. The cylindrical base is a circular ring structure with a groove. The upper part of the groove has a sealing ring, and the upper protruding part of the sealing ring is directly connected to the flange plate to achieve a seal.

4. The method according to claim 1, characterized in that, In step (2), the alumina powder has a particle size of 8-12 μm.

5. The method according to claim 1, characterized in that, In step (2), the mass ratio of epoxy resin, alumina powder and curing agent is 10:(2-4):

5.

6. A cylinder made of alumina fiber-reinforced resin matrix composite material with low thermal conductivity and high heat insulation at ultra-low temperatures, characterized in that, It is prepared by the method described in any one of claims 1-5.

7. The application of the alumina fiber reinforced resin matrix composite cylinder with low thermal conductivity and high thermal insulation at ultra-low temperatures as described in claim 6 in a cryogenic fuel tank at temperatures of 77K-273K.

8. A cryogenic liquid helium, liquid hydrogen, and liquid nitrogen storage tank, characterized in that, The cylinder with low thermal conductivity and high heat insulation at ultra-low temperatures, as described in claim 6, is made of alumina fiber reinforced resin matrix composite material.

9. The application of the alumina fiber reinforced resin matrix composite cylinder with low thermal conductivity and high thermal insulation at ultra-low temperatures as described in claim 6 in the field of aerospace equipment.

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