An organic-inorganic interpenetrating heat-insulating and heat-proof integrated material and its in-situ preparation method

Abstract

The present invention discloses an organic-inorganic interpenetrating anti-heat-insulating integrated material and an in-situ preparation method thereof, belonging to the field of preparation of ablative-resistant materials. The material comprises a porous skeleton formed by in-situ pressure curing of phosphate slurry I and boron-modified phenolic resin with interpenetrating distribution, and an atmospheric pressure curing coating of phosphate slurry II brushed on the surface of the porous skeleton; both the phosphate slurry I and the phosphate slurry II are formed by stirring raw materials including aluminum dihydrogen phosphate and nano-zirconia; and the mass fraction of nano-zirconia in the phosphate slurry II is greater than that in the phosphate slurry I. Through the synergistic effect of composition and structure, the material has the characteristics of high matrix interface bonding force and excellent ablative-resistant performance.

Description

Technical Field

[0001] The present invention relates to an organic-inorganic interpenetrating anti-heat-insulating integrated material and an in-situ preparation method thereof, belonging to the field of ablative material preparation. Background Art

[0002] In recent years, with the development of space technology and the in-depth exploration of deep space, the significant increase in the flight speed of spacecraft has led to increasingly harsh re-entry environments. When the return capsule penetrates the dense atmosphere at a high speed of several kilometers per second, intense aerodynamic heating can cause the surface temperature to soar above 2000 °C. Without efficient thermal protection measures, the structure of the return capsule will face the risk of ablation and disintegration. To ensure the safety of astronauts and the reliability of equipment, improving the ablation resistance and heat insulation performance of the thermal protection system (TPS) has become a core technical bottleneck that urgently needs to be broken through in the space field.

[0003] However, traditional metal-based and ceramic-based heat-insulating materials are gradually difficult to meet the design requirements of lightweight and integration due to defects such as high density, brittleness, and poor processing adaptability. Although polymer-based composite materials dominate in key TPS components such as the combustion chamber of a propellant ramjet engine (PRE) and the throat of a rocket nozzle due to their low density, excellent mechanical properties, and heat resistance advantages, they still have obvious limitations. For example, the interfacial bonding strength between the resin matrix and inorganic fillers is insufficient, and interfacial delamination is prone to occur at high temperatures; in an extreme thermo-mechanical coupling environment, traditional laminated composite structures are prone to thermal stress concentration, resulting in the failure of the anti-heat-insulating integrated function. In addition, the existing material systems are difficult to simultaneously improve the ablation protection and heat insulation performance, restricting the technological development of a new generation of hypersonic vehicles. Summary of the Invention

[0004] Aiming at the problems of low ablation resistance and heat insulation performance of the materials of the thermal protection system in the prior art and poor interfacial bonding ability of the matrix, the first object of the present invention is to provide an organic-inorganic interpenetrating anti-heat-insulating integrated material. In this material, the resin-based organic component and the phosphate inorganic component are interpenetratingly distributed and tightly combined with each other, which not only solves the problem of low interfacial bonding force of the matrix, but also in-situ forms a topological network carbonized layer structure through a carbonization reaction in a low-oxygen and high-temperature environment. Collaborating with the zirconia particles and the boron element introduced into the boron phenolic resin, it effectively solves the shortcoming of high-temperature failure of traditional structure integrated anti-heat-insulating materials.

[0005] The second object of the present invention is to provide a preparation method of an organic-inorganic interpenetrating anti-heat-insulating integrated material. This method in-situ prepares an organic-inorganic interpenetrating and internally porous structure from organic components, inorganic components, and pore-forming agents, significantly enhancing the interfacial bonding force of the components. This preparation process is simple, the reagent raw materials are cheap and easily available, the preparation period is short, the preparation equipment and conditions are simple, which is conducive to large-scale industrial production.

[0006] To achieve the above technical objectives, the present invention provides an organic-inorganic interpenetrating anti-heat-insulating integrated material, which comprises a porous framework formed by in-situ pressure curing of phosphate slurry I and boron-modified phenolic resin with interpenetrating distribution, and an atmospheric pressure curing coating of phosphate slurry II brushed on the surface of the porous framework; both the phosphate slurry I and the phosphate slurry II are formed by stirring raw materials including aluminum dihydrogen phosphate and nano-zirconia; and the mass fraction of nano-zirconia in the phosphate slurry II is greater than that in the phosphate slurry I, and the porosity of the organic-inorganic interpenetrating anti-heat-insulating integrated material is 35-40%.

[0007] The key to the excellent interfacial bonding force, anti-heat-insulating and anti-ablative properties of the material of the present invention lies in the coexistence and interpenetration of organic and inorganic components and the synergistic effect of the porous structure.

[0008] The principle of ablation resistance of the material of the present invention is derived from a multi-stage synergistic mechanism. Specifically, at the initial stage of ablation, the surface of the material rapidly absorbs heat and the temperature rises sharply. First, the aluminum phosphate monohydrate phase (formed by the reaction of aluminum dihydrogen phosphate and nano zirconium oxide) present in the phosphate slurry II is dehydrated and melted at high temperature, and the aluminum dihydrogen phosphate phase is also decomposed due to high temperature. The two take away part of the heat, and a small amount of heat is transferred to the upper layer inside the material. Then the sub-surface of the boron phenolic resin preferentially undergoes step-by-step pyrolysis, releasing gases such as H2O, CO, and CO2. At this time, the decomposition of the surface phosphate and the decomposition of the sub-surface boron phenolic acid resin take away a large amount of initial heat, reducing the continuous penetration of heat and the degree of ablation damage on the surface of the material. As the temperature further increases, the aluminum phosphate formed after dehydration melts and sinks, and the molten aluminum phosphate and other substances sink to fill the surface and internal pore structure of the material, preventing the penetration of oxygen, and at the same time providing heat for further carbonization and other reactions of organic matter in the sub-surface of the material. Organic matter with an interpenetrating network structure undergoes a carbonization reaction in a low-oxygen and high-temperature environment, forming a topological network carbonization layer structure in situ. On the one hand, the carbon content of the carbonized layer is relatively high, and the presence of carbon ensures that the material maintains a certain structural stability at high temperatures; on the other hand, the carbonized layer is a porous structure, and the pores can hinder heat conduction, just like a thermal insulation barrier, reducing the transfer of heat to the inside of the material and protecting the matrix. The stable topological network carbonized layer structure can not only effectively fix the molten aluminum phosphate to prevent its diffusion, but also prevent the material from ablating and retreating. As the ablation continues, the boron element in the boron phenolic resin reacts with other substances at high temperatures to produce compounds such as B2O3. These compounds further react with carbon to produce B4C, etc., and finally form a ceramic layer composed of B4C, B2O3 and glassy carbon in the topological network carbonized layer structure, further improving the high temperature resistance and thermal insulation properties of the carbonized layer. At the same time, the zirconium oxide particles on the surface sinter and grow at high temperatures, acting as pinning to fix the dissipation of the molten aluminum phosphate. In the later stage of ablation, a zirconium oxide particle layer, molten aluminum oxide and other substances, a topological network carbonized layer structure, and the lower original material and porous structure layer are formed from top to bottom. The specific structure is as follows: Figure 7 As shown. Due to the high temperature resistance of the surface zirconia, the material exhibits excellent high temperature ablation resistance; similarly, the pore structure left by the pore former inside the material can effectively reduce the heat transfer efficiency, thereby exhibiting excellent high temperature thermal insulation performance.

[0009] Meanwhile, in the present invention, the mass fraction of nano-zirconia in the phosphate slurry II is greater than that in the phosphate slurry I. The reason for such a setting is as follows: Zirconia has a relatively high melting point and is the main substance for the ablation resistance of the material system. With a larger addition amount of zirconia in the phosphate II on the brushed surface, a zirconia layer can be formed on the surface during subsequent ablation experiments to protect the substances inside the material, enabling a stronger carbon layer structure to be formed inside, further improving the ablation stability and reliability. The reason for the relatively small amount of zirconia in the phosphate slurry I used for in-situ preparation of the interpenetrating organic-inorganic material inside is that a large amount of high-melting-phase substances are not required inside. The unablated zirconia particles inside can play a toughening role, and excessive addition thereof will affect the heat insulation performance of the material. Moreover, the outer surface of the material of the present invention has no pores, but the internal skeleton structure has a relatively high porosity, which is conducive to hindering heat conduction in the middle and late stages of ablation, like a heat insulation barrier, reducing the heat transfer to the inside of the material and protecting the matrix.

[0010] As a preferred embodiment, the mass ratio of the phosphate slurry I, boron-modified phenolic resin, and phosphate slurry II is (40 - 80):(2 - 8):(10 - 15). If the addition amount of the phosphate slurry I is too much, the organic-inorganic interpenetrating structure will be reduced, and it is difficult to form a topological network carbonized layer structure, resulting in uneven distribution of the carbon layer inside the system and affecting the ablation resistance support and heat insulation performance. If the addition amount of the phosphate slurry is less, the proportion of organic matter in the matrix is high. During high-temperature ablation, a large amount of carbonization and volatilization will occur in the organic matter near the ablation layer. First, it will lead to a serious decrease in the mass ablation rate. Second, it will seriously damage the dense zirconia layer of the ablation layer, forming more external exhaust holes, and the infiltration of oxygen molecules will cause the oxidation failure of the carbon layer. The influence of boron-modified phenolic resin is similar to that of the phosphate slurry I. If too much of the phosphate slurry II is brushed, the coating thickness will increase and the organic-inorganic hybrid layer of the matrix will be reduced. Since the brushed phosphate slurry II belongs to a dense and pore-free structure with a thermal conductivity greater than that of the matrix material, it will seriously affect the temperature on the back side of ablation at the same ablation temperature. If the brushing amount of the phosphate slurry II is reduced, the surface coating will be thin. During subsequent ablation, the phosphate decomposes and volatilizes, forming fine holes, and the ablation flame directly damages the matrix, affecting the overall ablation performance of the material.

[0011] As a preferred embodiment, the viscosity of the phosphate slurry I is 10 - 15 Pas, and the viscosity of the phosphate slurry II is 15 - 20 Pas.

[0012] As a preferred embodiment, the mass ratio of aluminum dihydrogen phosphate and nano-zirconia in the phosphate slurry I is (1 - 3):(2 - 5); more preferably, the mass ratio of aluminum dihydrogen phosphate and nano-zirconia is (1 - 2):(2 - 3).

[0013] As a preferred solution, the mass ratio of aluminum dihydrogen phosphate to nano zirconia in the phosphate slurry II is (1~3):(2~6).

[0014] Under the range of the mass ratio of aluminum dihydrogen phosphate to nano zirconia in the phosphate slurry I and phosphate slurry II preferably used in the present invention, it is beneficial to maintain the stability of the material structure and the gradient heat insulation and ablation protection performance between the outer surface layer and the internal material during the ablation process.

[0015] The present invention also provides a preparation method of an organic-inorganic interpenetrating heat insulation and ablation protection integrated material. The method is to mix raw materials including phosphate slurry I, boron-modified phenolic resin and pore-forming agent, and then pour them into a mold for pressurized heating and curing to form a porous skeleton; brush the phosphate slurry II on the outer surface of the porous skeleton and then cure it under normal pressure to obtain the product.

[0016] In the preparation method of the present invention, during the in-situ curing of phosphate slurry I, boron-modified phenolic resin and pore-forming agent, due to the high adhesiveness and compatibility of phosphate and resin matrix, they are well in-situ cured to form a whole, while the pore-forming agent pyrolyzes during the high-temperature curing process to form a pore structure. Therefore, a porous skeleton with organic-inorganic interpenetration is formed in-situ, significantly improving the interfacial bonding force. By brushing the phosphate slurry II, the surface pore structure can be filled to avoid direct contact with the organic matter during subsequent ablation and protect the internal structure. At the same time, the boron-modified phenolic resin used in the present invention introduces boron elements into the molecular structure of phenolic resin to replace the hydrogen in the phenolic hydroxyl group. Since the bond energy of the boron-oxygen bond is higher than that of the carbon-carbon bond, a three-dimensional network structure containing boron is formed during application, further improving the ablation resistance of the material.

[0017] The pore-forming agent used in the present invention is a commonly used inorganic pore-forming agent on the market, such as ammonium bicarbonate, ammonium carbonate, etc.

[0018] As a preferred solution, the mass ratio of the phosphate slurry I, boron-modified phenolic resin and pore-forming agent is (40~80):(2~8):(1~4). If the addition amount of the pore-forming agent is relatively large, there will be more pore structures in the matrix material, which will affect the overall mechanical properties of the material and thus affect the ablation reliability; if the addition amount of the pore-forming agent is relatively small, fewer pore structures will be formed inside the matrix, which will affect the subsequent ablation heat insulation performance and cause the back temperature of the material to rise. Further preferably, the mass ratio of the phosphate slurry I, boron-modified phenolic resin and pore-forming agent is (40~60):(2~6):(1~2).

[0019] As a preferred solution, the conditions for pressure-heating curing and forming are as follows: the temperature is 120-150 °C, and the pressure is 2-15 Mpa. In this temperature range, there is partial melting of the boron phenolic resin, which can combine well with the phosphate material. Through appropriate pressurization, the phosphate slurry I and the boron-modified phenolic resin can be combined more tightly for in-situ composite curing and forming. Further preferably, the temperature is 120-130 °C, and the pressure is 5-10 Mpa.

[0020] As a preferred solution, the molding time for pressure-heating curing and forming is 1-5 h. Further preferably, the molding time is 2-4 h.

[0021] As a preferred solution, the equipment for pressure-heating selected in the present invention can be a flat vulcanizer.

[0022] As a preferred solution, the brushing is carried out in a small amount and multiple times until the pores on the surface of the porous skeleton are filled, so as to avoid direct contact with the organic matter during subsequent ablation and protect the internal structure.

[0023] As a preferred solution, after brushing the phosphate slurry II, it is oscillated and then put into an oven for curing and forming. Further, the oscillation frequency is 100-150 / min, and more preferably, the oscillation frequency is 100-120 / min, and the oscillation time is 2-6 min.

[0024] As a preferred solution, the temperature for atmospheric-pressure curing and forming is 80-100 °C. The atmospheric-pressure curing and forming of the present invention is mainly to cure the brushed phosphate slurry II.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The organic-inorganic interpenetrating anti-heat-insulating integrated material provided by the present invention has the resin-based organic component and the phosphate inorganic component interpenetrating and distributed and tightly combined with each other. It not only solves the problem of low interfacial bonding force of the matrix, but also in-situ forms a topological network carbonized layer structure through a carbonization reaction in a low-oxygen and high-temperature environment. Collaborating with the zirconia particles and the boron element introduced in the boron phenolic resin, it effectively solves the shortcoming of high-temperature failure of traditional structural integrated anti-heat-insulating materials.

[0027] (2) The present invention in-situ prepares and cures the organic component, the inorganic component and the pore-forming agent in one step to form an organic-inorganic interpenetrating and internally porous structure, which significantly enhances the interfacial bonding force of the components. The preparation process is simple, the reagent raw materials are cheap and easy to obtain, the preparation period is short, the preparation equipment and conditions are simple, which is conducive to large-scale industrial production.

[0028] (3) The zirconia particles in the material of the present invention will sinter and grow at high temperatures to act as pinning to fix the dissipation of molten aluminum phosphate, improving the stable structure of the material.

[0029] (4) During the ablation process of the material of the present invention, the boron element introduced in the boron phenolic resin forms a ceramic layer composed of B4C, B2O3 and glassy carbon in the topological network carbonized layer structure, further improving the high-temperature resistance and heat insulation performance of the carbonized layer. Brief Description of the Drawings

[0030] Figure 1 It is a surface microscopic morphology diagram of the material after curing by a flat vulcanizer in Example 1 (before brushing phosphate slurry II).

[0031] Figure 2 It is a compressive strength data diagram of the organic-inorganic interpenetrating heat-insulating and heat-protecting integrated material prepared in Example 1.

[0032] Figure 3 It is a surface microscopic morphology diagram of the material after curing by a flat vulcanizer in Example 2 (before brushing phosphate slurry II).

[0033] Figure 4 It is the XRD data of the material after curing by a flat vulcanizer in Example 2 (before brushing phosphate slurry II).

[0034] Figure 5 It is a surface microscopic morphology diagram of the organic-inorganic interpenetrating heat-insulating and heat-protecting integrated material prepared in Example 2.

[0035] Figure 6 It is a compressive strength data diagram of the organic-inorganic interpenetrating heat-insulating and heat-protecting integrated material prepared in Example 2.

[0036] Figure 7 It is a surface microscopic morphology diagram of the organic-inorganic interpenetrating heat-insulating and heat-protecting integrated material prepared in Example 2 after ablation at 2500°C.

[0037] Figure 8 It is a cross-sectional microscopic morphology diagram of the organic-inorganic interpenetrating heat-insulating and heat-protecting integrated material prepared in Example 2 after ablation at 2500°C.

[0038] Figure 9 It is a structural schematic diagram of the material formed after the organic-inorganic interpenetrating heat-insulating and heat-protecting integrated material prepared by the present invention is ablated at 2500°C.

[0039] Figure 10 It is a compressive strength data diagram of the organic-inorganic interpenetrating heat-insulating and heat-protecting integrated material prepared in Comparative Example 2. Specific Embodiments

[0040] To further illustrate the present invention, the following describes the content of the present invention in detail in conjunction with embodiments. However, it should be understood that these embodiments are implemented on the premise of the technical solution of the present invention, and the detailed implementation methods and specific operation processes are given. It is only to further illustrate the features and advantages of the present invention, rather than a limitation on the claims of the present invention. The protection scope of the present invention is not limited to the following embodiments either.

[0041] The boron-modified phenolic resin used in the examples and comparative examples of the present invention was purchased from Chenghui New Materials, and the product model was PF-241.

[0042] Example 1

[0043] (1) Mix 20 g of aluminum dihydrogen phosphate solution and 40 g of nano-zirconia particles, and stir for 0.4 h to obtain phosphate slurry I;

[0044] (2) Weigh 40 g of the phosphate slurry I obtained in step (1), mix it with 4 g of boron-modified phenolic resin and 1 g of pore-forming agent (ammonium bicarbonate), stir for 0.3 h, pour it into a mold, and place it in a flat vulcanizer at 120 °C, mold press at 8 Mpa, and keep the pressure for 3 h to cure and form a porous skeleton;

[0045] (3) Mix 20 g of aluminum dihydrogen phosphate solution and 55 g of nano-zirconia particles, and stir for 0.2 h to obtain phosphate slurry II;

[0046] (4) Brush the phosphate slurry II obtained in step (3) onto the surface of the porous skeleton obtained in step (2), with a brushing amount of 10 g. After oscillating at 110 times / min for 5 min, place it in an oven at 80 °C to cure and form the organic-inorganic interpenetrating thermal insulation and ablation-resistant integrated material. The porosity of the material is 37%.

[0047] In the subsequent ablation experiment of this material, the mass ablation rate and linear ablation rate are 0.0093 g / s and 0.013 mm / s respectively. The ablation surface temperature is 2480 °C, and the back temperature is 152 °C. Its compressive strength reaches 5.13 MPa, indicating that the material has good bonding properties and is not easily damaged.

[0048] Example 2

[0049] (1) Mix 20 g of aluminum dihydrogen phosphate solution and 50 g of nano-zirconia particles, and stir for 0.3 h to obtain phosphate slurry I;

[0050] (2) Weigh 40 g of the phosphate slurry I obtained in step (1), mix it with 6 g of boron-modified phenolic resin and 1 g of pore-forming agent (ammonium bicarbonate), stir for 0.3 h, pour it into a mold, and place it in a flat vulcanizer at 120 °C, mold press at 8 Mpa, and keep the pressure for 3 h to cure and form a porous skeleton;

[0051] (3) Mix 20 g of aluminum dihydrogen phosphate solution and 60 g of nano-zirconia particles, and stir for 0.2 h to obtain phosphate slurry II;

[0052] (4) Brush the phosphate slurry II obtained in step 3 onto the surface of the porous skeleton in step 2, with a brushing amount of 12 g. After oscillating at 120 times / min for 5 min, place it in an oven at 80 °C for curing and forming to obtain an organic-inorganic interpenetrating anti-heat-insulating integrated material, and the porosity of the material is 37%.

[0053] In the subsequent ablation experiment of this material, the mass ablation rate and linear ablation rate are 0.0085 g / s and 0.016 mm / s respectively. The ablation surface temperature is 2480 °C, and the back temperature is 135 °C. Its compressive strength reaches 6.15 MPa, indicating that the material has good bonding and is not easily damaged.

[0054] Example 3

[0055] (1) Mix 25 g of aluminum dihydrogen phosphate solution and 70 g of nano-zirconia particles, and stir for 0.3 h to obtain phosphate slurry I;

[0056] (2) Weigh 50 g of the phosphate slurry I obtained in step 1, mix it with 5 g of boron-modified phenolic resin and 2 g of pore-forming agent (ammonium bicarbonate), stir for 0.3 h, pour it into a mold, and place it on a flat vulcanizer at 130 °C for molding under a pressure of 9 Mpa and keep the pressure for 2 h to obtain a porous skeleton;

[0057] (3) Mix 10 g of aluminum dihydrogen phosphate solution and 40 g of nano-zirconia particles to obtain phosphate slurry II;

[0058] (4) Brush the phosphate slurry II obtained in step 3 onto the surface of the porous skeleton in step 3, with a brushing amount of 13 g. After oscillating at 120 times / min for 6 min, place it in an oven at 80 °C for curing and forming to obtain an organic-inorganic interpenetrating anti-heat-insulating integrated material, and the porosity is 38%.

[0059] In the subsequent ablation experiment of this material, the mass ablation rate and linear ablation rate are 0.0081 g / s and 0.017 mm / s respectively. The ablation surface temperature is 2450 °C, and the back temperature is 149 °C.

[0060] Example 4

[0061] (1) Mix 25 g of aluminum dihydrogen phosphate solution and 70 g of nano-zirconia particles, and stir for 0.3 h to obtain phosphate slurry I;

[0062] (2) Weigh 50 g of the phosphate slurry I obtained in step 1, mix it with 5 g of boron-modified phenolic resin and 2 g of pore-forming agent (ammonium carbonate), stir for 0.3 h, pour it into a mold, and place it on a flat vulcanizer at 150 °C for molding under a pressure of 3 Mpa and keep the pressure for 2 h to obtain a porous skeleton;

[0063] (3) Mix 10 g of aluminum dihydrogen phosphate solution and 40 g of nano zirconia particles to obtain phosphate slurry II;

[0064] (4) Brush the phosphate slurry II obtained in step 3 onto the surface of the porous skeleton in step 3, with a brushing dosage of 15 g. After oscillating at 120 times / min for 6 min, place it in an oven at 90 °C for curing and molding to obtain an organic-inorganic interpenetrating thermal insulation and ablation-resistant integrated material, with a porosity of 39%.

[0065] In the subsequent ablation experiment of this material, the mass ablation rate and linear ablation rate are 0.0083 g / s and 0.011 mm / s respectively. The ablation surface temperature is 2527 °C, and the back temperature is 168 °C.

[0066] Comparative Example 1

[0067] The difference between this comparative example and Example 2 is only that no pore-forming agent is added, and the remaining steps and conditions are the same, obtaining an organic-inorganic interpenetrating integrated material.

[0068] During the ablation process of this composite material, the heat insulation performance decreases relatively. Since this composite material is prepared by compression molding with a flat vulcanizing machine and no pore-forming agent is added, the density of the sample increases and the porosity is low. The dense sample provides certain convenient conditions for ablation heat conduction, resulting in a decrease in the heat insulation performance of the sample.

[0069] In the subsequent ablation experiment research of this material, the heat insulation performance is poor, the surface temperature is 2470 °C, and the back temperature is 311 °C. Its heat insulation performance drops significantly.

[0070] Comparative Example 2

[0071] The difference between this comparative example and Example 2 is only that instead of compression molding with a flat vulcanizing machine, oven curing is used, and the curing temperature is the same as that in Example 2. The remaining steps and conditions are the same, obtaining an organic-inorganic interpenetrating thermal insulation and ablation-resistant integrated material.

[0072] This composite material belongs to atmospheric pressure curing, and the bonding degree between the organic and inorganic substances is low, affecting the mechanical properties of the material. And in the subsequent ablation performance research, ablation peeling is likely to occur in the material. The compressive strength of this material is shown in Figure 10 , and its compressive strength is only 1.47 MPa, affecting the reliability of the subsequent experimental environment.

[0073] Comparative Example 3

[0074] The difference between this comparative example and Example 2 is only that the organic matter is replaced with a phenolic resin not modified with boron, and the remaining steps and conditions are the same, obtaining an organic-inorganic interpenetrating integrated material.

[0075] Since the organic matter added to the composite material is unmodified phenolic resin, its decomposition temperature is relatively reduced, and the carbonization rate is also relatively reduced. After the organic matter decomposes and before carbonization, no substances such as B2O3 are generated inside, which will affect the formation of the subsequent topological network carbonization layer and cause ablation recession during ablation. After ablation at 2485 °C, the mass ablation rate and linear ablation rate of this material are 0.0081 g / s and 0.055 mm / s respectively, and its linear ablation rate is relatively large.

[0076] Comparative Example 4

[0077] The difference between this comparative example and Example 2 is only that the preparation of phosphate slurry II is to mix 20 g of aluminum dihydrogen phosphate solution and 30 g of nano-zirconia particles, and the rest of the steps and conditions are the same, obtaining an organic-inorganic interpenetrating integrated material.

[0078] The content of zirconia in the brush-coated phosphate slurry II of this composite material is reduced. Due to the reduction of zirconia in the coating (ablation-resistant layer), during the subsequent ablation experiment, the denseness and thickness of the zirconia layer on the ablation surface decrease, and the ablation temperature is more likely to reach the interior of the material, resulting in an ablation surface temperature of 2450 °C, a back temperature of 277 °C, and the mass ablation rate and linear ablation rate are 0.0121 g / s and 0.046 mm / s respectively, both of which are relatively large.

Claims

1. An organic-inorganic interpenetrating heat-insulating integrated material, characterized in that: It comprises a porous framework interpenetrating with each other formed by in-situ pressurized curing of phosphate slurry I and boron-modified phenolic resin, and a phosphate slurry II normal pressure curing coating brushed on the surface of the porous framework; The phosphate slurry I and the phosphate slurry II are both formed by stirring raw materials including aluminum dihydrogen phosphate and nano zirconium oxide; And the mass fraction of nano zirconium oxide in phosphate slurry II is greater than the mass fraction of nano zirconium oxide in phosphate slurry I; The porosity of the organic-inorganic interpenetrating heat-insulating integrated material is 35-40%; The mass ratio of aluminum dihydrogen phosphate and nano zirconium oxide in the phosphate slurry I is (1-3): (2-5); The mass ratio of aluminum dihydrogen phosphate and nano zirconium oxide in the phosphate slurry II is (1-3): (2-6); The preparation process of the organic-inorganic interpenetrating anti-insulation integrated material is as follows: raw materials including phosphate slurry I, boron-modified phenolic resin and pore-forming agent are mixed and poured into a mold for pressurized heating and curing to obtain a porous skeleton; phosphate slurry II is brushed on the outer surface of the porous skeleton and then cured at normal pressure to obtain the obtained material.

2. The organic-inorganic interpenetrating heat-insulating integrated material according to claim 1, characterized in that: The mass ratio of the phosphate slurry I, the boron-modified phenolic resin and the phosphate slurry II is (40-80): (2-8): (10-15).

3. The method for preparing an organic-inorganic interpenetrating heat-insulating integrated material according to claim 1 or 2, characterized in that: The raw materials including phosphate slurry I, boron-modified phenolic resin and pore-forming agent are mixed and poured into a mold for pressurized heating and curing to obtain a porous skeleton; the phosphate slurry II is brushed on the outer surface of the porous skeleton and then cured at normal pressure to obtain the porous skeleton.

4. The method for preparing an organic-inorganic interpenetrating heat-insulating integrated material according to claim 3, characterized in that: The mass ratio of the phosphate slurry I, the boron-modified phenolic resin and the pore-forming agent is (40-80): (2-8): (1-2).

5. The method for preparing an organic-inorganic interpenetrating heat-insulating integrated material according to claim 3, characterized in that: The conditions for the pressurized heating curing molding are: a temperature of 120-150° C. and a pressure of 2-15 Mpa.

6. The method for preparing an organic-inorganic interpenetrating heat-insulating integrated material according to claim 4 or 5, characterized in that: The molding time of the pressurized heating and curing molding is 1 to 5 hours.

7. The method for preparing an organic-inorganic interpenetrating heat-insulating integrated material according to claim 6, characterized in that: The brush coating is performed in small amounts and multiple times until the pores on the surface of the porous skeleton are filled.

8. The method for preparing an organic-inorganic interpenetrating heat-insulating integrated material according to claim 3, characterized in that: The temperature of the normal pressure curing molding is 80-100°C.

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