An organic-inorganic composite internal insulation material for solid rocket motors and its preparation method

Abstract

The present invention relates to an organic-inorganic composite internal insulation material for a solid rocket motor and a preparation method thereof. An organo-inorganic hybrid phenolic resin is injected into an inorganic fiber preform having a carbon fiber-quartz fiber gradient structure, a pore-forming solvent is added, and after curing, a surface sealing treatment is carried out to prepare the organic-inorganic composite internal insulation material. Compared with the prior art, the internal insulation material prepared by the present invention can achieve multiple functions such as low density, low thermal conductivity, and ablation resistance under a single structure, and can be applied to the internal insulation structure of a solid rocket motor having high specific impulse and long-time working characteristics.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal insulation materials, and particularly relates to an organic-inorganic composite internal thermal insulation material for a solid rocket motor and a preparation method thereof. Background Art

[0002] The internal thermal insulation structures of solid rocket motors, such as gas pipelines, nozzle converging sections, nozzle diverging sections, etc., need to withstand harsh conditions such as high-temperature and high-pressure gas ablation and long-term heating during service. The currently used internal thermal insulation materials mainly include superalloys, carbon fiber / phenolic molded composites, alloy liner-composite nested structures, etc. With the increase of the gas temperature and pressure of solid rocket motors, the following deficiencies of the existing internal thermal insulation materials are exposed during use: (1) Superalloys have a large density and a high thermal conductivity; (2) Carbon fiber / phenolic molded composites have insufficient ablation resistance and a relatively high thermal conductivity; (3) The nested structure has poor thermal matching, the combined interface is prone to failure, and the thermal conductivity is relatively high. Therefore, the development of an integrated internal thermal insulation material with low density-low thermal conductivity-ablative resistance is an urgent need in this field at present. Summary of the Invention

[0003] The purpose of the present invention is to provide an organic-inorganic composite internal thermal insulation material for a solid rocket motor and a preparation method thereof.

[0004] The purpose of the present invention can be achieved by the following technical solutions: A preparation method of an organic-inorganic composite internal thermal insulation material for a solid rocket motor, injecting an organic-inorganic hybrid phenolic resin into an inorganic fiber preform with a carbon fiber-quartz fiber gradient structure, adding a pore-forming solvent, and obtaining a porous composite material after curing, and performing surface sealing treatment on the porous composite material to prepare the organic-inorganic composite internal thermal insulation material.

[0005] The carbon fiber preform has excellent ablation resistance, but a relatively high thermal conductivity. While quartz fiber has a low thermal conductivity, but poor ablation resistance. Therefore, designing a carbon fiber-quartz fiber gradient structure can make the surface of the internal thermal insulation material have excellent ablation resistance, and at the same time show a relatively low thermal conductivity as a whole.

[0006] The organic-inorganic hybrid phenolic resin has excellent high-temperature resistance and a relatively high char residue rate compared with traditional phenolic resins, which is beneficial to improving the ablation resistance of the internal thermal insulation material. The added pore-forming solvent can volatilize during the resin curing process, making the resin form a porous structure, which is beneficial to reducing the thermal conductivity and density of the internal thermal insulation structure.

[0007] Preferably, the preparation method includes the following steps:

[0008] S1: Design the inorganic fiber preform into a carbon fiber-quartz fiber gradient structure;

[0009] S2: Select an organic-inorganic hybrid phenolic resin as the matrix raw material and add a pore-forming solvent;

[0010] S3: Inject the resin into the fiber preform through an alternating pressure-assisted RTM process, and cure the injected resin through an alternating temperature curing process to obtain a porous composite material;

[0011] S4: Perform a pore sealing treatment on the surface of the porous composite material through an alternating vacuum impregnation and alternating temperature curing process, thereby preparing an organic-inorganic composite internal thermal insulation material.

[0012] Preferably, the weaving forms of the carbon fiber-quartz fiber gradient structure include orthogonal three-directional, fine weaving and piercing, 2.5D weaving, and fabric / net tire laminated needle punching.

[0013] Preferably, from the side close to the engine gas to the side far from the engine gas, the volume percentage of the carbon fiber layer decreases, while the volume percentage of the quartz fiber layer increases.

[0014] Preferably, the carbon fiber-quartz fiber gradient structure is composed of a carbon fiber layer, an intermediate transition layer (containing both carbon fibers and quartz fibers), and a quartz fiber layer;

[0015] The volume percentage of the carbon fiber layer decreases in an equal-proportion gradient from 100% to 0% according to the thickness direction dimension. At the same time, the volume percentage of the quartz fiber layer increases in an equal-proportion gradient from 0% to 100% according to the thickness direction dimension, and the gradient of the decrease in the volume fraction of the carbon fiber layer is the same as the gradient of the increase in the volume fraction of the quartz fiber layer.

[0016] Preferably, the organic-inorganic hybrid phenolic resin includes an organosilicon hybrid phenolic resin, a polycarbosilane hybrid phenolic resin, and a boron hybrid phenolic resin.

[0017] Preferably, a pore-forming solvent is added to the organic-inorganic hybrid phenolic resin.

[0018] More preferably, the pore-forming solvent accounts for 10% - 30% of the total solution volume of the organic-inorganic hybrid phenolic resin and the pore-forming solvent.

[0019] Preferably, the types of the pore-forming solvent include ethanol, isopropanol, cyclohexane, and ethylene glycol.

[0020] Preferably, inject the organic-inorganic hybrid phenolic resin into the inorganic fiber preform through an alternating pressure-assisted RTM process, and cure the injected organic-inorganic hybrid phenolic resin through an alternating temperature curing process.

[0021] By using a glue injection pressure that alternates within a certain range and frequency, the resin can be more evenly filled in the pores of the fiber preform, which is beneficial to improving the ablation resistance of the internal thermal insulation material. By using a curing temperature that alternates within a certain range and frequency, the resin can be cured more thoroughly, which is more beneficial to improving the ablation resistance of the internal thermal insulation material.

[0022] Further preferably, in the alternating pressure-assisted RTM process, the pressure inside the resin container is not a constant value but an alternating pressure. The container pressure is set to 0.3 - 1.2 MPa, the pressure alternating amplitude is 5% - 10% of the set container pressure value, and the alternating frequency is 0.1 - 0.5 Hz.

[0023] Further preferably, in the alternating temperature curing process, the temperature is not a constant value but an alternating temperature. The curing temperature is set to 85 - 130 °C, the alternating temperature amplitude is 2% - 5% of the set curing temperature value, the alternating frequency is 0.01 - 0.1 Hz, and the curing time is 24 - 36 h.

[0024] Preferably, the surface sealing treatment is carried out on the surface in contact with the gas by alternating vacuum impregnation and alternating temperature curing to obtain an organic-inorganic composite internal thermal insulation material.

[0025] Only carrying out the sealing treatment on the surface in contact with the gas flow can improve its ablation resistance without affecting the thermal conductivity and density of the overall material. Alternating pressure impregnation is more conducive to the sealing agent entering the surface of the porous composite material, thereby improving the ablation resistance of the internal thermal insulation material; adopting the alternating temperature curing process can make the sealing agent cure more thoroughly, which is conducive to improving the ablation resistance of the internal thermal insulation material.

[0026] Preferably, the surface sealing treatment steps include:

[0027] S1: Using a vacuum bag to seal the surface of the porous composite material that does not need to be sealed, only exposing the surface in contact with the gas, placing it in a closed container, and using the alternating vacuum impregnation process to immerse the sealing agent into the surface of the porous composite material;

[0028] S2: Using the alternating temperature curing process to cure the immersed sealing agent to obtain the organic-inorganic composite internal thermal insulation material.

[0029] Further preferably, the sealing agent is a solvent-free organic-inorganic hybrid phenolic resin (such as organosilicon hybrid phenolic resin, polycarbosilane hybrid phenolic resin, boron hybrid phenolic resin, etc.).

[0030] Further preferably, in the alternating vacuum impregnation process, the vacuum degree is not lower than -0.08 MPa, the vacuum alternating amplitude is 5 - 15% of the set vacuum value, the alternating frequency is 0.1 - 0.8 Hz, and the impregnation time is 6 - 12 h.

[0031] Further preferably, in the alternating temperature curing process, the curing temperature is set to 90 - 140 °C, the amplitude of the alternating temperature is 2% - 5% of the set curing temperature value, the alternating frequency is 0.01 - 0.1 Hz, and the curing time is 36 - 48 h.

[0032] An organic-inorganic composite internal insulation material for a solid rocket motor is prepared by the above preparation method.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The present invention provides an organic-inorganic composite internal insulation material and its preparation method, which can solve the problem that traditional internal insulation materials cannot have both low density, low thermal conductivity, and resistance to gas ablation.

[0035] 2. Through the design of the carbon fiber - quartz fiber gradient structure, the present invention can endow the surface of the internal insulation material with excellent ablation resistance, while the overall material shows a relatively low thermal conductivity.

[0036] 3. By using the injection pressure that alternates within a certain amplitude and frequency, the resin can be more evenly filled in the pores of the fiber preform, which is beneficial to improving the ablation resistance of the internal insulation material. By using the curing temperature that alternates within a certain amplitude and frequency, the resin can be cured more fully, which is more conducive to improving the ablation resistance of the internal insulation material.

[0037] 4. The present invention only performs hole sealing treatment on the surface in contact with the gas flow, which can improve its ablation resistance without affecting the thermal conductivity and density of the overall material.

[0038] 5. Through alternating pressure impregnation, the present invention is more conducive to the entry of the hole sealing agent into the surface of the porous composite material, thereby improving the ablation resistance of the internal insulation material. By using the alternating temperature curing process, the hole sealing agent can be cured more fully, which is beneficial to improving the ablation resistance of the internal insulation material.

[0039] 6. The internal insulation material prepared by the method of the present invention can achieve multiple functions such as low density, low thermal conductivity, and ablation resistance under a single structure, and can be applied to the internal insulation structure of a solid rocket motor with high specific impulse and long-time working characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic structural diagram of the organic-inorganic composite internal insulation material of the present invention;

[0041] In the figure: 1 - surface hole sealing, 2 - porous organic-inorganic hybrid phenolic resin, 3 - carbon fiber, 4 - quartz fiber. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and gives the detailed implementation manner and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0043] Example 1

[0044] Step 1. Design the inorganic fiber preform into a carbon fiber - quartz fiber orthogonal three - dimensional gradient structure. The volume percentage of the carbon fiber layer decreases in equal - proportion gradient from 100% to 0% according to the thickness - direction dimension. At the same time, the volume percentage of the quartz fiber layer increases in equal - proportion gradient from 0% to 100% according to the thickness - direction dimension. And the gradient of the decrease in the volume fraction of the carbon fiber layer is the same as the gradient of the increase in the volume fraction of the quartz fiber layer.

[0045] Step 2. Select silicone - hybrid phenolic resin as the matrix raw material, and the silicone - hybrid phenolic resin is prepared according to Patent ZL201911266938.7. And add isopropanol with a volume fraction of 10% as the pore - forming agent.

[0046] Step 3. Inject the resin into the fiber preform through the alternating - pressure - assisted RTM process. The molding pressure is 0.3 MPa, the pressure alternating amplitude is 5% of the set molding pressure value, and the alternating frequency is 0.1 Hz.

[0047] Step 4. Cure the injected resin through the alternating - temperature process. The curing temperature is 85 °C, the alternating - temperature amplitude is 2% of the set curing - temperature value, and the alternating frequency is 0.01 Hz. The curing time is 24 h. A porous composite material is obtained.

[0048] Step 5. Seal the surfaces of the porous composite material that do not need to be sealed with a vacuum bag, only expose the surface that needs to contact the gas, place it in a closed container, and use silicone - hybrid phenolic resin as the hole - sealing agent.

[0049] Step 6. Immerse the hole - sealing agent into the surface of the porous material through the alternating - vacuum - impregnation process. The vacuum degree of the alternating - vacuum impregnation is - 0.08 MPa, the vacuum - alternating amplitude is 5% of the set vacuum value, the alternating frequency is 0.1 Hz, and the impregnation time is 6 h.

[0050] Step 7. Cure the hole - sealing agent through the alternating - temperature - curing process. The curing temperature is 90 °C, the alternating - temperature amplitude is 2% of the set curing - temperature value, and the alternating frequency is 0.01 Hz. The curing time is 36 h. After curing, an organic - inorganic composite internal thermal insulation material with low - density - low - thermal - conductivity - gas - ablation - resistant multi - functional integration can be obtained.

[0051] As Figure 1As shown in the figure, the organic-inorganic composite internal thermal insulation material includes a surface hole-sealing layer 1, a porous organic-inorganic hybrid phenolic resin 2, carbon fibers 3, and quartz fibers 4. The porous organic-inorganic hybrid phenolic resin 2 is provided with a surface hole-sealing layer 1 on the surface in contact with the fuel gas. The carbon fibers 3 and quartz fibers 4 are disposed within the porous organic-inorganic hybrid phenolic resin 2. From the side close to the engine fuel gas to the side far from the engine fuel gas, the volume percentage of the carbon fibers 3 decreases, while the volume percentage of the quartz fibers 4 increases.

[0052] Example 2

[0053] Step 1. Design the inorganic fiber preform into a carbon fiber - quartz fiber 2.5D woven gradient structure. The volume percentage of the carbon fiber layer decreases in equal proportion along the thickness direction from 100% to 0%. At the same time, the volume percentage of the quartz fiber layer increases in equal proportion along the thickness direction from 0% to 100%. And the gradient of the decrease in the volume fraction of the carbon fiber layer is the same as the gradient of the increase in the volume fraction of the quartz fiber layer.

[0054] Step 2. Select polycarbosilane hybrid phenolic resin as the matrix raw material, and the polycarbosilane hybrid phenolic resin is prepared according to Patent ZL202111389268.5. And add isopropanol with a volume fraction of 15% as the pore-forming agent.

[0055] Step 3. Inject the resin into the fiber preform through the alternating pressure-assisted RTM process. The molding pressure is 0.9 MPa, the pressure alternating amplitude is 6% of the set molding pressure value, and the alternating frequency is 0.2 Hz.

[0056] Step 4. Cure the injected resin through the alternating temperature process. The curing temperature is 100 °C, the alternating temperature amplitude is 3% of the set curing temperature value, and the alternating frequency is 0.05 Hz. The curing time is 30 h. Obtain the porous composite material.

[0057] Step 5. Seal the surface of the porous composite material that does not need to be hole-sealed with a vacuum bag, only expose the surface that needs to be in contact with the fuel gas, place it in a closed container, and use polycarbosilane hybrid phenolic resin as the hole-sealing agent.

[0058] Step 6. Immerse the hole-sealing agent into the surface of the porous material through the alternating vacuum impregnation process. The vacuum degree of the alternating vacuum impregnation is -0.085 MPa, the vacuum alternating amplitude is 10% of the set vacuum value, the alternating frequency is 0.4 Hz, and the impregnation time is 10 h.

[0059] Step 7. Cure the hole-sealing agent through the alternating temperature curing process. The curing temperature is 100 °C, the alternating temperature amplitude is 3% of the set curing temperature value, and the alternating frequency is 0.05 Hz. The curing time is 40 h. After curing, an organic-inorganic composite internal thermal insulation material with low density - low thermal conductivity - fuel gas ablation resistance multifunctional integration can be obtained.

[0060] Example 3

[0061] Step 1. Design the inorganic fiber preform into a carbon fiber - quartz fiber cloth / net tire laminated needle - punched gradient structure. The volume percentage of the carbon fiber layer decreases in equal - proportion gradient from 100% to 0% according to the thickness - direction dimension. At the same time, the volume percentage of the quartz fiber layer increases in equal - proportion gradient from 0% to 100% according to the thickness - direction dimension. And the gradient of the decrease in the volume fraction of the carbon fiber layer is the same as the gradient of the increase in the volume fraction of the quartz fiber layer.

[0062] Step 2. Select boron - hybridized phenolic resin as the matrix raw material, and the boron - hybridized phenolic resin is prepared according to Patent ZL201710138648.9. And add isopropanol with a volume fraction of 30% as the pore - forming agent.

[0063] Step 3. Inject the resin into the fiber preform through the alternating - pressure - assisted RTM process. The forming pressure is 1.2 MPa, the pressure alternating amplitude is 10% of the set forming pressure value, and the alternating frequency is 0.5 Hz.

[0064] Step 4. Cure the injected resin through the alternating - temperature process. The curing temperature is 130 °C, the alternating - temperature amplitude is 5% of the set curing temperature value, the alternating frequency is 0.1 Hz. The curing time is 36 h. A porous composite material is obtained.

[0065] Step 5. Seal the surfaces of the porous composite material that do not need to be sealed with a vacuum bag, only expose the surface that needs to contact the gas, place it in a closed container, and use boron - hybridized phenolic resin as the hole - sealing agent.

[0066] Step 6. Immerse the hole - sealing agent into the surface of the porous material through the alternating - vacuum impregnation process. The vacuum degree of the alternating - vacuum impregnation is - 0.09 MPa, the vacuum alternating amplitude is 15% of the set vacuum value, the alternating frequency is 0.8 Hz, and the impregnation time is 12 h.

[0067] Step 7. Cure the hole - sealing agent through the alternating - temperature curing process. The curing temperature is 140 °C, the alternating - temperature amplitude is 5% of the set curing temperature value, the alternating frequency is 0.1 Hz. The curing time is 48 h. After curing, an organic - inorganic composite internal thermal insulation material with low - density - low - thermal - conductivity - gas - ablation - resistant multi - function integration can be obtained.

[0068] Comparative Example 1

[0069] Step 1. Design the inorganic fiber preform into an orthogonal three - dimensional carbon fiber structure.

[0070] Step 2. Select silicone hybrid phenolic resin as the matrix raw material, and the silicone hybrid phenolic resin is prepared according to Patent ZL201911266938.7. And add isopropanol with a volume fraction of 10% as the pore-forming agent.

[0071] Step 3. Inject the resin into the fiber preform by the alternating pressure-assisted RTM process. The molding pressure is 0.3 MPa, the pressure alternating amplitude is 5% of the set molding pressure value, and the alternating frequency is 0.1 Hz.

[0072] Step 4. Cure the injected resin by the alternating temperature process. The curing temperature is 85 °C, the alternating temperature amplitude is 2% of the set curing temperature value, and the alternating frequency is 0.01 Hz. The curing time is 24 h. A porous composite material is obtained.

[0073] Step 5. Seal the surfaces of the porous composite material that do not need to be sealed with a vacuum bag, only expose the surface that needs to contact the gas, place it in a closed container, and use silicone hybrid phenolic resin as the sealing agent.

[0074] Step 6. Immerse the sealing agent into the surface of the porous material by the alternating vacuum impregnation process. The vacuum degree of the alternating vacuum impregnation is -0.08 MPa, the vacuum alternating amplitude is 5% of the set vacuum value, the alternating frequency is 0.1 Hz, and the impregnation time is 6 h.

[0075] Step 7. Cure the sealing agent by the alternating temperature curing process. The curing temperature is 90 °C, the alternating temperature amplitude is 2% of the set curing temperature value, and the alternating frequency is 0.01 Hz. The curing time is 36 h. After curing, an organic-inorganic composite internal thermal insulation material can be obtained.

[0076] Comparative Example 2

[0077] Step 1. Design the inorganic fiber preform into a 2.5D woven gradient structure of carbon fiber - quartz fiber. The volume percentage of the carbon fiber layer decreases in equal proportion along the thickness direction dimension from 100% to 0%. At the same time, the volume percentage of the quartz fiber layer increases in equal proportion along the thickness direction dimension from 0% to 100%. And the gradient of the decrease in the volume fraction of the carbon fiber layer is the same as the gradient of the increase in the volume fraction of the quartz fiber layer.

[0078] Step 2. Select polycarbosilane hybrid phenolic resin as the matrix raw material, and the polycarbosilane hybrid phenolic resin is prepared according to Patent ZL202111389268.5. And add isopropanol with a volume fraction of 15% as the pore-forming agent.

[0079] Step 3. Inject the resin into the fiber preform by the alternating pressure-assisted RTM process. The molding pressure is 0.9 MPa, the pressure alternating amplitude is 6% of the set molding pressure value, and the alternating frequency is 0.2 Hz.

[0080] Step 4. Cure the injected resin through an alternating temperature process. The curing temperature is 100°C, the amplitude of the alternating temperature is 3% of the set curing temperature value, the alternating frequency is 0.05 Hz, and the curing time is 30 h. A porous composite material is obtained.

[0081] Comparative Example 3

[0082] Step 1. Design the inorganic fiber preform into a laminated needle-punched gradient structure of carbon fiber-quartz fiber cloth / wire mesh. The volume percentage of the carbon fiber layer decreases in equal proportion gradient in the thickness direction from 100% to 0%. At the same time, the volume percentage of the quartz fiber layer increases in equal proportion gradient in the thickness direction from 0% to 100%. And the gradient of the decrease in the volume fraction of the carbon fiber layer is the same as the gradient of the increase in the volume fraction of the quartz fiber layer.

[0083] Step 2. Select boron-hybridized phenolic resin as the matrix raw material, and the boron-hybridized phenolic resin is prepared according to Patent ZL201710138648.9. And add isopropanol with a volume fraction of 30% as the pore-forming agent.

[0084] Step 3. Inject the resin into the fiber preform through the RTM process, where the molding pressure is 1.2 MPa.

[0085] Step 4. Cure the injected resin through an alternating temperature process. The curing temperature is 130°C, the amplitude of the alternating temperature is 5% of the set curing temperature value, the alternating frequency is 0.1 Hz, and the curing time is 36 h. A porous composite material is obtained.

[0086] Step 5. Seal the surface of the porous composite material that does not need to be sealed with a vacuum bag, only expose the surface that needs to contact the gas, place it in a closed container, and use boron-hybridized phenolic resin as the hole-sealing agent.

[0087] Step 6. Immerse the hole-sealing agent into the surface of the porous material through a vacuum impregnation process, and the vacuum degree of the vacuum impregnation is -0.09 MPa.

[0088] Step 7. Cure the hole-sealing agent through an alternating temperature curing process. The curing temperature is 140°C, the amplitude of the alternating temperature is 5% of the set curing temperature value, the alternating frequency is 0.1 Hz, and the curing time is 48 h. After curing, an organic-inorganic composite internal thermal insulation material can be obtained.

[0089] Comparative Example 4

[0090] Step 1. Design the inorganic fiber preform as a carbon fiber - quartz fiber cloth / net tire laminated needle - punched gradient structure. The volume percentage of the carbon fiber layer decreases in equal - proportion gradient from 100% to 0% according to the thickness - direction dimension. At the same time, the volume percentage of the quartz fiber layer increases in equal - proportion gradient from 0% to 100% according to the thickness - direction dimension. And the gradient of the decrease in the volume fraction of the carbon fiber layer is the same as the gradient of the increase in the volume fraction of the quartz fiber layer.

[0091] Step 2. Select boron - hybridized phenolic resin as the matrix raw material, and the boron - hybridized phenolic resin is prepared according to Patent ZL201710138648.9. Add isopropanol with a volume fraction of 30% as the pore - forming agent.

[0092] Step 3. Inject the resin into the fiber preform by the alternating - pressure - assisted RTM process. The forming pressure is 1.2 MPa, the pressure alternating amplitude is 10% of the set forming pressure value, and the alternating frequency is 0.5 Hz.

[0093] Step 4. Cure the injected resin. The curing temperature is 130 °C and the curing time is 36 h. A porous composite material is obtained.

[0094] Step 5. Seal the surfaces of the porous composite material that do not need to be sealed with a vacuum bag, only expose the surface that needs to contact the gas, place it in a closed container, and use boron - hybridized phenolic resin as the hole - sealing agent.

[0095] Step 6. Immerse the hole - sealing agent into the surface of the porous material by the alternating - vacuum impregnation process. The vacuum degree of the alternating - vacuum impregnation is - 0.09 MPa, the vacuum alternating amplitude is 15% of the set vacuum value, the alternating frequency is 0.8 Hz, and the impregnation time is 12 h.

[0096] Step 7. Cure the hole - sealing agent. The curing temperature is 140 °C and the curing time is 48 h.

[0097] Explanation of the attached table

[0098] Table 1 summarizes the properties of the organic - inorganic composite internal thermal insulation materials obtained in Examples 1 - 3 and the internal thermal insulation materials obtained in Comparative Examples 1 - 4. Among them, the density is tested by the method of GB 1463 - 2005, the thermal conductivity is tested by the method of GBT 10295 - 2008, and the linear ablation rate is tested by the method of GJB 323B - 2018.

[0099] Table 1

[0100]

[0101] By comparing Example 1 and Comparative Example 1, it can be found that designing the fiber preform as a carbon fiber - quartz fiber gradient structure can significantly reduce the thermal conductivity of the material without affecting the ablation - resistance performance compared with the pure carbon fiber structure.

[0102] By comparing Example 2 and Comparative Example 2, it can be found that by performing hole sealing treatment on the surface where the material contacts the gas flow, the ablation resistance performance of the material can be significantly improved without affecting the overall thermal conductivity and density of the material.

[0103] By comparing Example 3 and Comparative Examples 3-4, it can be found that using alternating pressure impregnation and alternating temperature curing is more beneficial to the ablation resistance performance of the material compared to fixed pressure impregnation and fixed temperature curing.

[0104] The material obtained by the present invention has both low density, low thermal conductivity and low linear ablation rate, and has broad application prospects in the adiabatic structure of solid rocket engines.

[0105] The above description of the embodiments is to enable those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and all improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A preparation method of an organic-inorganic composite internal insulation material for a solid rocket motor, characterized in that, inject an organo-inorganic hybrid phenolic resin into an inorganic fiber preform with a carbon fiber - quartz fiber gradient structure, add a pore-forming solvent, and perform surface sealing treatment after curing to prepare the organic-inorganic composite internal insulation material; the carbon fiber - quartz fiber gradient structure is composed of a carbon fiber layer, an intermediate transition layer, and a quartz fiber layer; the volume percentage of the carbon fiber layer decreases in equal proportion along the thickness direction from 100% to 0%, and at the same time, the volume percentage of the quartz fiber layer increases in equal proportion along the thickness direction from 0% to 100%, and the gradient of the decrease in the volume fraction of the carbon fiber layer is the same as the gradient of the increase in the volume fraction of the quartz fiber layer; inject the organo-inorganic hybrid phenolic resin into the inorganic fiber preform through an alternating pressure-assisted RTM process, and cure the injected organo-inorganic hybrid phenolic resin through an alternating temperature curing process; the surface sealing treatment step includes: S1: Seal the surface of the porous composite material that does not need to be sealed with a vacuum bag, only expose the surface in contact with the gas, place it in a closed container, and immerse the sealing agent into the surface of the porous composite material by an alternating vacuum impregnation process; S2: Cure the immersed sealing agent by an alternating temperature curing process to obtain the organic-inorganic composite internal insulation material; the sealing agent is an organo-inorganic hybrid phenolic resin without solvent.

2. The preparation method of the organic-inorganic composite internal insulation material for a solid rocket motor according to claim 1, characterized in that, the weaving form of the carbon fiber - quartz fiber gradient structure is orthogonal three-directional, fine weaving piercing, 2.5D weaving, or cloth / net tire laminated needle punching.

3. The preparation method of the organic-inorganic composite internal insulation material for a solid rocket motor according to claim 1, characterized in that, the organo-inorganic hybrid phenolic resin is an organosilicon hybrid phenolic resin, a polycarbosilane hybrid phenolic resin, or a boron hybrid phenolic resin.

4. The preparation method of the organic-inorganic composite internal insulation material for a solid rocket motor according to claim 1, characterized in that, the types of the pore-forming solvent are ethanol, isopropanol, cyclohexane, or ethylene glycol.

5. The preparation method of the organic-inorganic composite internal insulation material for a solid rocket motor according to claim 1, characterized in that, in the alternating pressure-assisted RTM process, set the container pressure to 0.3 - 1.2 MPa, the pressure alternating amplitude to 5% - 10% of the set container pressure value, and the alternating frequency to 0.1 - 0.5 Hz; in the alternating temperature curing process, set the curing temperature to 85 - 130 °C, the alternating temperature amplitude to 2% - 5% of the set curing temperature value, the alternating frequency to 0.01 - 0.1 Hz, and the curing time to 24 - 36 h.

6. The preparation method of the organic-inorganic composite internal insulation material for a solid rocket motor according to claim 1, characterized in that, In the alternative vacuum impregnation process described in step S1, the vacuum degree is not less than -0.08 MPa, the vacuum alternation amplitude is 5-15% of the set vacuum value, the alternation frequency is 0.1-0.8 Hz, and the impregnation time is 6-12 h; In the alternative temperature curing process described in step S2, the set curing temperature is 90-140 °C, the alternation temperature amplitude is 2%-5% of the set curing temperature value, the alternation frequency is 0.01-0.1 Hz, and the curing time is 36-48 h.

7. An organic-inorganic composite internal insulation material for a solid rocket motor, characterized in that, it is prepared by using the preparation method described in any one of claims 1-6.

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