Strong-ablation-erosion-resistant ceramizable flexible thermal protection material and preparation method thereof

Abstract

The invention belongs to the field of novel composite materials, and particularly relates to a strong-ablation-erosion-resistant ceramizable flexible thermal protection material and a preparation method thereof.According to the material, ethylene propylene diene monomer serves as a matrix, polysilazane resin of a special structure serves as a ceramization modifier, and aerogel powder serves as heat insulation reinforcing filler. The thermal protection material provided by the invention can form a compact high-strength ceramic protection layer on the surface in a high-temperature environment, improves the structural strength of an ablation carbonization layer, effectively reduces the ablation degree of the material, has the characteristics of light weight, ablation resistance, scouring resistance, efficient heat insulation and the like, and can meet the protection requirements of high-performance engines of novel weaponry in the future.

Description

Technical Field

[0001] The invention belongs to the technical field of composite materials, and in particular relates to a ceramic flexible thermal protection material resistant to strong ablation and erosion and a preparation method thereof. Background Art

[0002] The inner insulation layer of a rocket engine is a thermal protection material installed on the inner surface of the engine casing. It has the properties of high temperature resistance, ablation resistance, and resistance to high-speed heat flow erosion. When the engine is working, the insulation layer absorbs and takes away most of the heat through continuous decomposition and ablation to alleviate the transfer of heat generated by the combustion of the propellant to the casing, prevent high-temperature and high-pressure combustion gas from reducing the strength and structural stability of the casing, and play a role in heat insulation and thermal protection of the engine casing. It is a key component to ensure the normal operation of the engine. Due to its low density and good processability, ablative rubber is a commonly used material for the development of the inner insulation layer of solid rocket engines. It mainly includes nitrile rubber, silicone rubber, EPDM rubber, etc. Among them, EPDM rubber is a copolymer with ethylene, propylene and a small amount of non-conjugated dienes as monomers. It has the advantages of good heat resistance, excellent ablation performance, and high carbonization rate. It is currently the most widely used inner insulation layer material.

[0003] With the development of equipment technology, the temperature and pressure inside the engine have greatly increased, especially the internal insulation layer located at the front head of the engine, which is directly subjected to the strong ablation and erosion of high-temperature, high-speed and high-pressure gas flow. The ablation performance of traditional EPDM rubber materials has gradually failed to meet the use requirements of high-performance engines.

[0004] The ceramic reaction occurs under high temperature and a ceramic layer is formed on the surface, which is one of the effective ways for the ablative material to block the gas and hot oxygen environment, resist airflow erosion, reduce the peeling of the ablation carbonization layer, and improve the ablation performance. At present, there are two main ways to prepare ceramic EPDM rubber. One is to add inorganic ceramic powders such as mica powder, glass powder, and ceramic powder to the rubber matrix, and realize ceramicization by melting the ceramic powder at high temperature to form a liquid protective layer on the surface of the material, such as invention patents CN202110582426.2, CN202110078605.2, CN202410522477.X, etc.; the other is to add silicon-containing organic substances such as alkoxysilane, polysiloxane and multifunctional silsesquioxane (POSS) to the rubber matrix, and realize ceramicization by decomposing silicone at high temperature to generate SiO2, SiC and other substances, such as invention patents CN201811001907.4, CN201410825886.3, etc.

[0005] However, inorganic ceramic powders have a large density, which will significantly increase the density and thermal conductivity of the flexible insulation layer; silicon-containing organic matter has a low ceramicization efficiency and has limited effect on improving the ablation performance of the insulation material. In addition, these ceramic modifiers (including inorganic ceramic powders and silicon-containing organic matter) are basically doped into the EPDM system through physical blending. Due to the relative inertness of the EPDM molecular chain, too much ceramic modifier is prone to agglomeration and greatly reduces the mechanical, ablation and other properties of the flexible insulation material. However, when the amount of ceramic modifier added is small, it is difficult to effectively play the role of ceramic protection. The existing ceramicizable EPDM system is difficult to meet the needs of the inner insulation layer under strong ablation scouring of high-performance engines. Summary of the invention

[0006] In order to solve the problems existing in the above-mentioned prior art, the present invention provides a highly ablation-resistant and erosion-resistant ceramic flexible thermal protection material and a preparation method thereof. The material is based on EPDM rubber, uses a special structural polysilazane resin as a ceramic modifier, and uses aerogel powder as a thermal insulation reinforcing filler. The provided thermal protection material will form a dense and high-strength ceramic protection layer on the surface under high temperature conditions, and improve the structural strength of the ablation carbonization layer, effectively reducing the degree of material ablation. At the same time, it has the characteristics of light weight, ablation resistance, erosion resistance, and high-efficiency thermal insulation, which can meet the protection needs of high-performance engines of new weapons and equipment in the future.

[0007] The specific concept of the present invention is as follows: using ceramic precursor polysilazane resin as a ceramic modifier for EPDM rubber. Polysilazane resin is the most commonly used ceramic precursor for manufacturing silicon nitride ceramics. It has a high degree of ceramicization and good structural strength under high temperature environment; the polysilazane resin used is a special structural polymer, and its molecular structure contains functional groups such as hydrogen and vinyl, which can react chemically with the EPDM rubber network, which can not only improve the compatibility between the two, but also greatly improve the strength of the EPDM ablation carbon layer, and can effectively resist the erosion of high-pressure and high-speed gas flow. At the same time, the inventor uses aerogel powder to replace the traditional reinforcing material white carbon black, while ensuring the mechanical properties of the rubber, further reducing the thermal conductivity of the rubber and reducing the heat transfer to the shell. By adding polysilazane resin and aerogel powder, the problems of low ceramicization efficiency, poor component compatibility and poor rubber ablation resistance of ceramic EPDM rubber are solved, and a ceramic flexible inner insulation layer material that is resistant to strong ablation erosion is provided for new high-performance engines.

[0008] Based on the above inventive concept, the present invention provides a strong ablation and erosion resistant ceramic flexible thermal protection material, the raw material composition of which is calculated by weight:

[0009] EPDM rubber: 100 parts;

[0010] Polysilazane: 10-50 parts;

[0011] Reinforcement fiber: 5-20 parts;

[0012] Reinforcing agent: 10-40 parts;

[0013] Accelerator: 1-5 parts;

[0014] Rubber adhesive: 2-10 parts;

[0015] Stearic acid: 0-2 parts;

[0016] Vulcanizing agent: 1 to 5 parts.

[0017] The polysilazane is one or a mixture of two of vinyl polysilazane, hydrogen-containing polysilazane and methyl vinyl polysilazane; further, the molecular weight Mw of the polysilazane is 500 to 8000.

[0018] The reinforcing fiber is one of aramid fiber, poly(p-phenylene benzobisoxazole) fiber and polyimide fiber in the form of 5-10 mm long fiber or pulp.

[0019] The reinforcing agent is one of SiO2 aerogel powder, phenolic aerogel powder, Al2O3 aerogel powder, and ZrO2 aerogel powder; further, the powder particle size of the reinforcing agent is 10 to 500 μm.

[0020] The accelerator is one of zinc oxide, magnesium oxide and lead oxide or a mixture of two of them.

[0021] The rubber adhesive is one of adhesive AB-30, adhesive RC, and adhesive RE, or a mixture of two of them in any ratio.

[0022] The stearic acid plays an activating and promoting role in the vulcanization process, and can react with zinc oxide and the like at high temperature to generate zinc stearate and other substances to promote the vulcanization of rubber.

[0023] The vulcanizing agent is one of sulfur, benzoyl peroxide and dicumyl peroxide or a mixture of two of them.

[0024] Furthermore, the raw material composition is calculated by weight:

[0025] EPDM rubber: 100 parts;

[0026] Polysilazane: 12-40 parts;

[0027] Reinforcement fiber: 7-15 parts;

[0028] Reinforcing agent: 10-28 parts;

[0029] Accelerator: 1.5-4 parts;

[0030] Rubber adhesive: 2.5-8 parts;

[0031] Stearic acid: 0.5-1.7 parts;

[0032] Vulcanizing agent: 1.5 to 4 parts.

[0033] Furthermore, the inventors also provide a method for preparing a strong ablation-resistant and erosion-resistant ceramic flexible thermal protection material, the specific steps of which are as follows:

[0034] (1) Preparation of EPDM rubber compound

[0035] Add EPDM rubber and reinforcing fiber to the internal mixer according to the proportion, and mix them at room temperature for 15 to 30 minutes. Then add the reinforcing agent to the internal mixer three times, and mix them at room temperature for a total of 10 to 30 minutes. Put the mixed rubber into the open mixer, and add polysilazane, accelerator, rubber adhesive, stearic acid and vulcanizer in order according to the proportion, and mix them until they are evenly mixed. Adjust the roller distance of the open mixer to ≤1mm, pass it through 5 to 10 times, adjust the roller distance according to the thickness requirements and produce the sheet, and place it at room temperature for 12 hours to obtain the EPDM mixed rubber.

[0036] (2) Vulcanization molding of flexible thermal protection materials

[0037] Place the mold in a vulcanizer and heat it to 150-175°C, and evenly spray the release agent; according to the product size requirements, weigh a certain amount of the EPDM compound obtained in the previous step and put it into the mold, hot-press and vulcanize it at 150-175°C and 0.5-3MPa for 10-60min, and a strong ablation-resistant and erosion-resistant ceramic EPDM insulation layer can be obtained after demolding.

[0038] Compared with the prior art, the above technical solution of the present invention has the following advantages:

[0039] (1) The highly ablation-resistant and erosion-resistant ceramic EPDM rubber prepared by the present invention adopts a special structure polysilazane resin containing functional groups such as hydrogen and vinyl as a ceramic modifier, which can chemically react with the EPDM rubber network during the thermal vulcanization process of the rubber. Compared with traditional inorganic ceramic powders such as mica powder and glass powder, it has excellent component compatibility and avoids the occurrence of agglomeration.

[0040] (2) Polysilazane resin has a high degree of ceramicization and good structural strength under high temperature environment. In addition, since it is evenly dispersed in the rubber matrix, it can greatly improve the strength of the EPDM ablation carbon layer during high-temperature ablation and can effectively resist the erosion of high-pressure and high-speed gas flow.

[0041] (3) The ceramic EPDM rubber resistant to strong ablation and erosion prepared by the present invention adopts aerogel powder instead of the traditional reinforcing material white carbon black. On the one hand, aerogel has an extremely low thermal conductivity coefficient. Adding it to the rubber system can effectively improve the thermal insulation effect of the material without losing the mechanical properties (the traditional method of adding glass microbeads will reduce the mechanical properties of the material). On the other hand, the polar groups on the surface of the aerogel powder can form intermolecular forces with the H bonds and hydroxyl groups on the polysilazane, promoting the uniform dispersion of the aerogel powder in the rubber matrix, so that it can effectively replace white carbon black to play the role of reinforcing filler, disperse stress loads, and improve the mechanical strength of the rubber.

[0042] (4) Through chemical reactions and intermolecular forces, polysilazane forms a strong overall structure among the rubber matrix, aerogel powder and polysilazane. The synergistic effect of polysilazane and aerogel powder restricts the movement of the EPDM macromolecular chain segments, further improving the mechanical properties and heat resistance of the material.

[0043] In summary, the density of the strong ablation-resistant and erosion-resistant ceramic EPDM rubber obtained by the above raw material composition and preparation method is 0.9 g / cm 3 ~1.2g / cm 3 , tensile strength ≥ 8MPa, thermal conductivity ≤ 0.23W / m·K, linear ablation rate ≤ 0.055mm / s, mass ablation rate ≤ 0.060g / s. Compared with the EPDM rubber material prepared with white carbon black as reinforcement and without adding polysilazane resin, the material of the present invention has the characteristics of anti-scouring, ablation resistance, good ceramic effect and excellent thermal insulation performance, and provides a ceramic flexible inner insulation layer material that is resistant to strong ablation and scouring for new high-performance engines. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a photograph of the outer surface of the strong ablation-resistant and erosion-resistant ceramic EPDM rubber sample prepared in Example 1 before ablation;

[0045] Figure 2 This is a side profile photo of the strong ablation-resistant and erosion-resistant ceramic EPDM rubber sample prepared in Example 1 after ablation;

[0046] Figure 3 This is a side profile photograph of the EPDM rubber sample prepared in Comparative Example 1 after ablation.

[0047] As can be seen from the figure, Figure 2 The ablation depth of the sample is significantly less than Figure 3 For the samples, after adding polysilazane, the polysilazane will undergo a ceramic reaction when the rubber is ablated at high temperature. The formed ceramic product is tightly combined with the carbonized layer on the rubber surface, effectively hindering the further ablation and cracking of the rubber matrix and improving the rubber's anti-ablation performance. DETAILED DESCRIPTION

[0048] The present invention will be further described below in conjunction with specific embodiments, so that those skilled in the art can understand the present invention more comprehensively, but the present invention is not limited in any way. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0049] Example 1

[0050] A ceramicized flexible thermal protection material resistant to strong ablation and erosion, the raw material composition of which is calculated by weight:

[0051] EPDM rubber, 100 parts; vinyl polysilazane with a molecular weight Mw of 500-800, 40 parts; aramid pulp, 7 parts; SiO2 aerogel powder, particle size 50-150 μm, 15 parts; zinc oxide accelerator, 3.2 parts; rubber adhesive AB-30, 2.5 parts; stearic acid, 0.5 parts; sulfur, 4 parts.

[0052] The specific preparation method of the above materials is as follows:

[0053] Weigh each component material according to the above ratio, add EPDM rubber and aramid pulp into the internal mixer, and mix for 20 minutes. Then add SiO2 aerogel powder into the internal mixer three times, and mix for a total of 30 minutes. Put the mixed rubber into the open mixer, add vinyl polysilazane, zinc oxide accelerator, rubber adhesive AB-30, stearic acid and sulfur in turn, and mix until mixed evenly. Adjust the roller distance of the open mixer to ≤1mm, pass it 7 times, adjust the roller distance to 3mm and produce the sheet, and place it at room temperature for 12 hours to obtain EPDM mixed rubber.

[0054] A mold with a cavity size of 100 mm × 100 mm × 10 mm was placed in a vulcanizer and heated to 155°C, and a release agent was evenly sprayed on it. 120 g of EPDM rubber was weighed and placed in the mold according to the product size requirements. The mold was hot-pressed and vulcanized at 155°C and 2.5 MPa for 40 minutes, and the mold was removed to obtain a ceramic EPDM insulation layer that was resistant to strong ablation and erosion. Its properties are shown in Table 1.

[0055] Example 2

[0056] A ceramicized flexible thermal protection material resistant to strong ablation and erosion, the raw material composition of which is calculated by weight:

[0057] EPDM rubber, 100 parts; methyl vinyl polysilazane with a molecular weight Mw of 7000-8000, 20 parts; poly(p-phenylene benzobisoxazole) pulp, 15 parts; phenolic aerogel powder with a particle size of 100-200 μm, 27 parts; magnesium oxide accelerator, 3.9 parts; rubber adhesive RC, 7.5 parts; stearic acid, 1.2 parts; sulfur, 1 part; diisopropylbenzene peroxide, 2 parts.

[0058] The specific preparation method of the above materials is as follows:

[0059] Weigh each component material according to the above ratio, add EPDM rubber and poly(p-phenylene benzobisoxazole) pulp into the internal mixer, and mix for 15 minutes. Then add phenolic aerogel powder into the internal mixer three times, and mix for a total of 25 minutes. Put the mixed rubber into the open mixer, add methyl vinyl polysilazane, magnesium oxide accelerator, rubber adhesive RC, stearic acid, sulfur and diisopropylbenzene peroxide in turn, and mix until mixed evenly. Adjust the roller distance of the open mixer to ≤1mm, pass it 5 times, adjust the roller distance to 2mm and produce the sheet, and place it at room temperature for 12 hours to obtain EPDM mixed rubber.

[0060] A mold with a cavity size of 180mm×180mm×5mm was placed in a vulcanizer and heated to 160°C, and a release agent was evenly sprayed. 175g of EPDM rubber was weighed and placed in the mold according to the product size requirements, and hot-pressed and vulcanized at 160°C and 3MPa for 20 minutes. After demolding, a strong ablation-resistant and erosion-resistant ceramic EPDM insulation layer was obtained, and its properties are shown in Table 1.

[0061] Example 3

[0062] A ceramicized flexible thermal protection material resistant to strong ablation and erosion, the raw material composition of which is calculated by weight:

[0063] EPDM rubber, 100 parts; hydrogen-containing polysilazane with a molecular weight Mw of 1000-2000, 32 parts; 6mm polyimide fiber, 13 parts; SiO2 aerogel powder with a particle size of 350-450μm, 20 parts; lead oxide accelerator, 2.1 parts; rubber adhesive RE, 7.2 parts; stearic acid, 1.0 parts; diisopropylbenzene peroxide, 2.5 parts.

[0064] The specific preparation method of the above materials is as follows:

[0065] Weigh each component material according to the above ratio, add EPDM rubber and polyimide fiber into the internal mixer, and mix for 30 minutes. Then add SiO2 aerogel powder into the internal mixer three times, and mix for a total of 15 minutes. Put the mixed rubber into the open mixer, add hydrogen-containing polysilazane, lead oxide accelerator, rubber adhesive RE, stearic acid and diisopropylbenzene peroxide in turn, and mix until mixed evenly. Adjust the roller distance of the open mixer to ≤1mm, pass it 10 times, adjust the roller distance to 2.5mm and produce the sheet, and place it at room temperature for 12 hours to obtain EPDM mixed rubber.

[0066] A mold with a cavity size of 300mm×200mm×5mm was placed in a vulcanizer and heated to 175°C, and a release agent was evenly sprayed. 320g of EPDM rubber was weighed and placed in the mold according to the product size requirements, and hot-pressed and vulcanized at 175°C and 0.5MPa for 30 minutes. After demolding, a strong ablation-resistant and erosion-resistant ceramic EPDM insulation layer was obtained, and its properties are shown in Table 1.

[0067] Example 4

[0068] A ceramicized flexible thermal protection material resistant to strong ablation and erosion, the raw material composition of which is calculated by weight:

[0069] EPDM rubber, 100 parts; hydrogen-containing polysilazane with a molecular weight Mw of 3000-4000, 13 parts; 10mm polyimide fiber, 10 parts; Al2O3 aerogel powder with a particle size of 200-300μm, 25 parts; zinc oxide accelerator, 1.5 parts; rubber adhesive AB-30, 4.8 parts; stearic acid, 0.7 parts; benzoyl peroxide, 3 parts.

[0070] The specific preparation method of the above materials is as follows:

[0071] Weigh each component material according to the above ratio, add EPDM rubber and polyimide fiber into the internal mixer, and mix for 25 minutes. Then add Al2O3 aerogel powder into the internal mixer three times, and mix for a total of 10 minutes. Put the mixed rubber into the open mixer, add hydrogen-containing polysilazane, zinc oxide accelerator, rubber adhesive AB-30, stearic acid and benzoyl peroxide in turn, and mix until mixed evenly. Adjust the roller distance of the open mixer to ≤1mm, pass it 8 times, adjust the roller distance to 1.5mm and produce the sheet, and place it at room temperature for 12 hours to obtain EPDM mixed rubber.

[0072] A mold with a cavity size of 160mm×160mm×3mm was placed in a vulcanizer and heated to 170°C, and a release agent was evenly sprayed. 85g of EPDM rubber was weighed and placed in the mold according to the product size requirements, and hot-pressed and vulcanized at 170°C and 2MPa for 15 minutes. After demolding, a strong ablation-resistant and erosion-resistant ceramic EPDM insulation layer was obtained, and its properties are shown in Table 1.

[0073] Example 5

[0074] A ceramicized flexible thermal protection material resistant to strong ablation and erosion, the raw material composition of which is calculated by weight:

[0075] EPDM rubber, 100 parts; vinyl polysilazane with a molecular weight Mw of 5000-6500, 25 parts; aramid pulp, 15 parts; ZrO2 aerogel powder with a particle size of 150-250 μm, 13 parts; magnesium oxide accelerator, 2.7 parts; rubber adhesive AB-30, 1.5 parts; rubber adhesive RC, 2 parts; stearic acid, 1.5 parts; sulfur, 1.5 parts.

[0076] The specific preparation method of the above materials is as follows:

[0077] Weigh each component material according to the above ratio, add EPDM rubber and aramid pulp into the internal mixer, and mix for 17 minutes. Then add ZrO2 aerogel powder into the internal mixer three times, and mix for a total of 20 minutes. Put the mixed rubber into the open mixer, add vinyl polysilazane, magnesium oxide accelerator, rubber adhesive AB-30, rubber adhesive RC, stearic acid and sulfur in turn, and mix until mixed evenly. Adjust the roller distance of the open mixer to ≤1mm, pass it 9 times, adjust the roller distance to 2.5mm and produce the sheet, and place it at room temperature for 12 hours to obtain EPDM mixed rubber.

[0078] A mold with a cavity size of 200mm×180mm×1.5mm was placed in a vulcanizer and heated to 165°C, and a release agent was evenly sprayed. 60g of EPDM rubber was weighed and placed in the mold according to the product size requirements, and hot-pressed and vulcanized at 165°C and 1.5MPa for 10 minutes. After demolding, a strong ablation-resistant and erosion-resistant ceramic EPDM insulation layer was obtained, and its properties are shown in Table 1.

[0079] Comparative Example 1

[0080] A heat protection material, the raw material composition of which is calculated by weight:

[0081] EPDM rubber, 100 parts; aramid pulp, 7 parts; fumed silica, 15 parts; zinc oxide accelerator, 3.2 parts; rubber adhesive AB-30, 2.5 parts; stearic acid, 0.5 parts; sulfur, 4 parts.

[0082] The specific preparation method of the above materials is as follows:

[0083] Weigh each component material according to the above ratio, add EPDM rubber and aramid pulp into the internal mixer, and mix for 20 minutes. Then add fumed silica into the internal mixer three times, and mix for a total of 30 minutes. Put the mixed rubber into the open mixer, add zinc oxide accelerator, rubber adhesive AB-30, stearic acid and sulfur in turn, and mix until mixed evenly. Adjust the roller distance of the open mixer to ≤1mm, pass it 7 times, adjust the roller distance to 3mm and produce the sheet, and place it at room temperature for 12 hours to obtain EPDM mixed rubber.

[0084] A mold with a cavity size of 100 mm × 100 mm × 10 mm was placed in a vulcanizer and heated to 155°C, and a release agent was evenly sprayed on it. 128 g of EPDM rubber was weighed and placed in the mold according to the product size requirements. The mold was hot-pressed and vulcanized at 155°C and 2.5 MPa for 40 minutes, and the mold was removed to obtain a ceramic EPDM insulation layer that was resistant to strong ablation and erosion. Its properties are shown in Table 1.

[0085] Experimental example

[0086] The density, mechanical properties, thermal conductivity and ablation performance (according to GJB323A-1996) of the highly ablation-resistant and erosion-resistant ceramic flexible thermal protection materials prepared in the above-mentioned embodiments and comparative examples were tested. The specific performance test results are shown in Table 1.

[0087] Table 1

[0088] Test items Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 <![CDATA[Density / (g / cm 3 )]]> 0.947 1.158 1.096 1.035 1.142 0.924 Tensile strength / MPa 8.52 12.13 10.64 9.45 11.47 6.83 Thermal conductivity / (W / m·K) 0.225 0.213 0.221 0.215 0.227 0.253 Linear ablation rate / (mm / s) 0.0376 0.0428 0.0398 0.0514 0.0473 0.159 Mass ablation rate / (g / s) 0.0436 0.0519 0.0467 0.0582 0.0554 0.0738

[0089] As can be seen from Table 1, adding polysilazane to the EPDM rubber system not only improves the mechanical properties of the material, but also greatly improves the ablation performance of the material. At the same time, the use of aerogel powder instead of white carbon black reduces the thermal conductivity of the material to a certain extent and improves the thermal insulation performance of the material. The various properties of the material finally obtained have been greatly improved compared with the material of the comparative example, and can be used as the inner insulation layer material of the new high-performance engine.

[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any equivalent substitutions, modifications, etc. made by technicians in this field without any creative work within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A ceramicized flexible thermal protection material resistant to strong ablation and erosion, characterized in that: The raw material composition is calculated by weight: EPDM rubber: 100 parts; Polysilazane: 10-50 parts; Reinforcement fiber: 5-20 parts; Reinforcing agent: 10-40 parts; Accelerator: 1-5 parts; Rubber adhesive: 2-10 parts; Stearic acid: 0-2 parts; Vulcanizing agent: 1 to 5 parts.

2. The strong ablation resistant and erosion resistant ceramic flexible thermal protection material according to claim 1 is characterized in that: The polysilazane is one of vinyl polysilazane, hydrogen-containing polysilazane, methyl vinyl polysilazane or a mixture of two thereof; the reinforcing agent is one of SiO2 aerogel powder, phenolic aerogel powder, Al2O3 aerogel powder and ZrO2 aerogel powder.

3. The strong ablation resistant and erosion resistant ceramic flexible thermal protection material according to claim 2 is characterized in that: The molecular weight Mw of the polysilazane is 500-8000.

4. The strong ablation resistant and erosion resistant ceramic flexible thermal protection material according to claim 2 is characterized in that: The powder particle size of the reinforcing agent is 10 to 500 μm.

5. The strong ablation resistant and erosion resistant ceramic flexible thermal protection material according to claim 1 is characterized in that: The reinforcing fiber is one of aramid fiber, poly(p-phenylene benzobisoxazole) fiber and polyimide fiber in the form of 5-10 mm long fiber or pulp.

6. The strong ablation resistant and erosion resistant ceramic flexible thermal protection material according to claim 1 is characterized in that: The accelerator is one of zinc oxide, magnesium oxide, and lead oxide, or a mixture of two of them; the vulcanizing agent is one of sulfur, benzoyl peroxide, and dicumyl peroxide, or a mixture of two of them; and the rubber adhesive is one of adhesive AB-30, adhesive RC, and adhesive RE, or a mixture of two of them in any ratio.

7. The strong ablation resistant and erosion resistant ceramic flexible thermal protection material according to claim 1 is characterized in that: The raw material composition is calculated by weight: EPDM rubber: 100 parts; Polysilazane: 12-40 parts; Reinforcement fiber: 7-15 parts; Reinforcing agent: 10-28 parts; Accelerator: 1.5-4 parts; Rubber adhesive: 2.5-8 parts; Stearic acid: 0.5-1.7 parts; Vulcanizing agent: 1.5 to 4 parts.

8. The strong ablation resistant and erosion resistant ceramic flexible thermal protection material according to any one of claims 1 to 7, characterized in that: The final material density is 0.9 g / cm 3 ~1.2g / cm 3 , tensile strength ≥8MPa, thermal conductivity ≤0.23W / m·K, linear ablation rate ≤0.055mm / s, mass ablation rate ≤0.060g / s.

9. The method for preparing the strong ablation and erosion resistant ceramic flexible thermal protection material according to any one of claims 1 to 7, characterized in that: The specific steps are as follows: (1) Preparation of EPDM rubber compound Add EPDM rubber and reinforcing fiber to an internal mixer according to the proportion, and mix them at room temperature for 15 to 30 minutes; then add the reinforcing agent to the internal mixer three times, and mix them at room temperature for a total of 10 to 30 minutes; put the mixed rubber into an open mixer, and add polysilazane, accelerator, rubber adhesive, stearic acid and vulcanizing agent in sequence according to the proportion, and mix them until they are uniformly mixed, adjust the roller distance of the open mixer to ≤1mm, pass the mixer 5 to 10 times, adjust the roller distance according to the thickness requirement, and produce the sheet, and place it at room temperature for 12 hours to obtain EPDM mixed rubber; (2) Vulcanization molding of flexible thermal protection materials Place the mold in a vulcanizer and heat it to 150-175°C, and evenly spray a release agent; according to the product size requirements, weigh the EPDM rubber mixture obtained in the previous step and put it into the mold, hot-press and vulcanize it at 150-175°C and 0.5-3MPa for 10-60min, and a strong ablation-resistant and erosion-resistant ceramic flexible thermal protection material can be obtained after demolding.

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