CN115477824A - Preparation method of nano-pore resin-based composite material containing surface layer in-situ autogenous ablation-resistant layer - Google Patents
Preparation method of nano-pore resin-based composite material containing surface layer in-situ autogenous ablation-resistant layer Download PDFInfo
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- 238000011065 in-situ storage Methods 0.000 title claims abstract description 29
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- 238000002360 preparation method Methods 0.000 title claims abstract description 14
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- 238000005507 spraying Methods 0.000 claims description 22
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- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 9
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- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims description 9
- 238000010438 heat treatment Methods 0.000 claims description 9
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- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 claims description 3
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K7/00—Use of ingredients characterised by shape
- C08K7/02—Fibres or whiskers
- C08K7/04—Fibres or whiskers inorganic
- C08K7/10—Silicon-containing compounds
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Abstract
The invention relates to a preparation method of a nano-pore resin matrix composite material containing a surface layer in-situ autogenous ablation-resistant layer, which comprises the following steps: preparing a ceramic precursor solution; pretreating the surface layer of the fiber felt; oscillating and sintering, namely converting the ceramic precursor into an ablation-resistant ceramic layer in situ; preparing a resin solution; low-pressure impregnation; sol-gel reaction; drying under normal pressure to obtain the nano-pore resin matrix composite material containing the surface layer in-situ autogenous ablation-resistant layer. Compared with the composite material without the protective layer, the composite material with the protective layer has the advantages that the ablation rate is obviously reduced, the mechanical property is improved, and the anti-ablation layer can effectively improve the anti-ablation capacity of the nanoporous resin matrix composite material, improves the reliability of the material in extreme environments, and has wide application prospects in the field of thermal protection. Compared with the existing coating preparation method, the method has the advantages of simple process, low cost, high efficiency, safety, effectiveness and the like.
Description
Technical Field
The invention relates to the field of composite materials, in particular to a preparation method of a nano-pore resin-based composite material containing a surface layer in-situ autogenous ablation-resistant layer.
Background
The serious pneumatic heating is generated when the aerospace craft reenters/enters the atmosphere, the thermal protection system is one of key subsystems necessary for ensuring the normal work of the aerospace craft, and the heat protection material is a vital part in the thermal protection system. With the rapid development of a new generation of air-defense anti-pilot anti-critical hypersonic air-to-air missile, a missile body can bear harsher long-time strong oxidation and high dynamic pressure high overload impact, and a thermal protection material becomes a key technical bottleneck for model development. The traditional ablation heat-proof material cannot fully exert the advantage of material ablation heat absorption under the existing thermal environment condition, and the material has no heat-proof and heat-insulating integrated function due to large thermal conductivity and density, so that the structure of the aircraft is excessively heavy due to the heat-proof design of the materials. Therefore, the development of a material with low density, low cost, ultra-long time, low ablation and long-acting heat insulation is an important task in the current hypersonic velocity technical field.
The nano-pore resin-based composite material is a low-density, heat-proof and heat-insulating integrated composite material taking fibers as a prefabricated body and phenolic resin as a matrix, and has important application in the field of thermal protection. However, the low density characteristic of the material has the side effect that when the material is in a high-heat flow-low enthalpy-high shear environment, a carbon layer generated after pyrolysis of surface layer resin is in a porous loose structure, and is easy to be mechanically degraded, so that the protection cannot be provided for an inner layer matrix, and particularly in a terminal reentry process after long-time heating, airflow shear is increased sharply, and the degradation phenomenon of the surface layer of the material is more serious. The method for directly protecting the ablation surface of the material by adopting the coating method is the most direct and effective method, but for the ablation heat-proof material, the traditional coating method has complex process and higher cost, and the coating is easy to lose efficacy at high temperature because the thermal matching performance of the coating and the substrate is generally poor. And the ceramic precursor is wholly soaked in the fiber preform for ablation resistance modification, so that the density and the heat conductivity of the material are obviously improved, and the heat insulation performance of the material is influenced.
Disclosure of Invention
The present invention aims to overcome at least one of the defects of the prior art and provide a preparation method of a nanoporous resin-based composite material containing a surface layer in-situ self-generated ablation resistant layer, which can effectively improve the ablation resistance and the erosion resistance of the nanoporous resin-based composite material in a ballistic environment.
The purpose of the invention can be realized by the following technical scheme:
a preparation method of a nano-pore resin-based composite material containing a surface layer in-situ autogenous ablation-resistant layer comprises the following steps:
preparing a ceramic precursor solution: dissolving a ceramic precursor in a nonpolar solvent to obtain a ceramic precursor solution;
pretreatment of the surface layer of the fiber felt: uniformly spraying the ceramic precursor solution on the surface layer of the fiber felt, and then drying and curing;
oscillating and sintering: putting the pretreated fibrofelt into a carbonization furnace, sintering in an inert atmosphere, and converting a ceramic precursor into an ablation-resistant ceramic layer in situ;
preparing a resin solution: dissolving resin by a polar solvent and adding a curing agent to obtain a resin solution;
low-pressure impregnation: placing the fiber felt after oscillation sintering in a mould, and completely impregnating the fiber felt with the resin solution;
sol-gel reaction: sealing the mould, carrying out sol-gel reaction, and cooling to room temperature after the reaction is finished to obtain a composite material;
drying under normal pressure: and opening the mould, and then drying the composite material in a normal pressure environment to obtain the nano-pore resin matrix composite material containing the surface layer in-situ spontaneous ablation resistant layer.
Further, the ceramic precursor comprises one or more of polycarbosilane, polysilaborazine, polysilazane, polysiloxane and metal polysilazane, and the nonpolar solvent comprises one or more of n-hexane, n-heptane, cyclohexane or toluene.
Furthermore, the mass fraction of the ceramic precursor in the ceramic precursor solution is 25-100wt%, and the mass fraction of the nonpolar solvent is 0-75wt%.
Further, the fiber felt comprises fiber felt woven by one or more of carbon fiber, quartz fiber, mullite fiber, phenolic fiber or polyacrylonitrile fiber.
Further, the structural form of the fiber felt comprises a quasi three-dimensional needle punched structure, a fiber cloth laying layer structure, a needle punched fiber felt structure or a 2.5D woven structure, and the density of the fiber felt is 0.1-0.5g/cm 3 The thickness is 10-30mm.
Furthermore, the temperature for curing the ceramic precursor is 50-100 ℃ and the time is 6-48h.
Further, the spraying method is a multi-time quantitative spraying-drying-curing process; the volume of the ceramic precursor solution sprayed for one time is 30-50ml, and the total volume sprayed is 90-150ml.
Further, when spraying, the spray gun is vertical to the surface of the fiber felt, the spraying pressure is 0.1-0.3MPa, the spraying height is 100-200mm, and the moving speed of the spray nozzle is 10-12cm/s.
Further, the basic temperature-rise rate of the oscillation temperature-rise sintering is 10 ℃/min, the oscillation amplitude is +/-5 ℃/min, the oscillation frequency is 1/15-1/60Hz, the temperature-keeping time of each oscillation is 1-10min, and the end point temperature is 450-550 ℃.
Further, the polar solvent comprises one or more of n-butyl alcohol, isopropanol, ethanol or ethylene glycol; the temperature of the sol-gel reaction is 80-140 ℃, and the time is 24-48h; the drying temperature is 20-120 ℃, and the drying time is 24-48h.
Compared with the prior art, the invention has the following advantages:
(1) In the invention, the cold spraying method sprays the ceramic precursor on the surface layer of the fiber prefabricated part and generates the ablation-resistant layer in situ, the raw materials are easy to obtain, the preparation conditions are not limited, and the nano-pore structure of the material is not excessively depended;
(2) In the invention, the surface layer can be uniformly distributed by ceramic components and controllable in thickness through a plurality of times of quantitative spraying-drying-curing processes, and the phenomenon of large-scale cracking of the surface can also be avoided;
(3) In the invention, oscillation heating sintering is carried out, the heating rate is controlled to carry out up-and-down floating with certain amplitude and frequency on the basic heating rate, so that a ceramic precursor is fully pyrolyzed, an anti-ablation ceramic layer is self-generated in situ on the surface layer of a fiber prefabricated part, and the cracking and falling of the fiber prefabricated part caused by overlarge heating rate in a main weightless temperature interval are avoided;
(4) In the invention, the ceramic layer is closely adhered to the fibers on the surface layer of the fibrofelt, so that on one hand, the strong shearing erosion of heat flow is effectively resisted, the pyrolytic carbon layer is protected, and on the other hand, the situation that the ablation-resistant layer is warped and falls off in the heating process due to the poor thermal matching performance between the resin matrix and the ceramic precursor is avoided;
(5) Compared with the fiber preform subjected to integral impregnation pretreatment, the fiber preform in-situ preparation method has the advantages that the ceramic ablation layer is generated only on the surface layer of the fiber preform, so that the influence on the interface bonding strength of the fiber and the resin matrix and the mechanical property of the material are avoided;
(6) In the invention, the surface in-situ self-generated ablation-resistant ceramic layer is distributed in a sheet-shaped step shape among the surface fibers, is not a simple single-layer structure, has better ablation-resistant effect and does not influence the impregnation of resin.
Drawings
FIG. 1 is a surface view of an ablation-resistant layer of a surface layer of a fiber mat preform of example 1;
FIG. 2 is an SEM image of the surface layer of the fiber after pretreatment of the fiber mat in example 1;
FIG. 3 is a surface topography of the composite of example 1;
FIG. 4 is a SEM image of the surface layer of the composite material of example 1.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.
A preparation method of a nano-pore resin-based composite material containing a surface layer in-situ autogenous ablation-resistant layer comprises the following steps:
preparing a ceramic precursor solution: dissolving a ceramic precursor in a nonpolar solvent to obtain a ceramic precursor solution; the ceramic precursor comprises one or more of polycarbosilane, polysilaborazine, polysilazane, polysiloxane and metal polysilazane, and the nonpolar solvent comprises one or more of n-hexane, n-heptane, cyclohexane and toluene. The mass fraction of the ceramic precursor in the ceramic precursor solution is 25-100wt%, and the mass fraction of the nonpolar solvent is 0-75wt%.
Pretreatment of the surface layer of the fiber felt: injecting the ceramic precursor solution into a spray gun, uniformly spraying on the surface layer of the fibrofelt, drying and curing in a drying oven for a period of time, taking out, and repeating the operation for three times; the fiber felt comprises fiber felt woven by one or more of carbon fiber, quartz fiber, mullite fiber, phenolic fiber or polyacrylonitrile fiber, and the structural form of the fiber comprises: a quasi-three-dimensional needling structure, a fiber cloth laying layer structure, a needling fiber felt structure or a 2.5D weaving structure, wherein the density of the prefabricated body is 0.1-0.5g/cm 3 The thickness is 10-30mm. The curing temperature of the ceramic precursor is 50-100 ℃, and the curing time is 6-48h. The spraying method is a multi-time quantitative spraying-drying-curing process. The volume of the ceramic precursor solution sprayed once is 30-50ml, and the total volume of spraying is 90-150ml. The spray gun is vertical to the surface of the fiber preform, the spraying pressure is 0.1-0.3MPa, the spraying height is 100-200mm, and the moving speed of the spray nozzle is 10-12cm/s.
Oscillating and sintering: putting the pretreated fibrofelt into a carbonization furnace, sintering in a nitrogen atmosphere, and converting a ceramic precursor into an ablation-resistant ceramic layer in situ; the basic temperature-rise rate of the oscillation temperature-rise sintering is 10 ℃/min, the oscillation amplitude is +/-5 ℃/min, the oscillation frequency is 1/15-1/60Hz, the temperature-keeping time of each oscillation is 1-10min, and the end point temperature is 450-550 ℃.
Preparing a resin solution: dissolving resin by a polar solvent and adding a curing agent to obtain a resin solution; the polar solvent is one or more of n-butanol, isopropanol, ethanol or ethylene glycol;
low-pressure impregnation: placing the pretreated fiber felt in a proper mould, and completely impregnating the prefabricated body with a resin solution;
sol-gel reaction: sealing the mold, carrying out sol-gel reaction, and cooling to room temperature after the reaction is finished to obtain a composite material; the temperature of the sol-gel reaction is 80-140 ℃, and the time is 24-48h;
drying under normal pressure: and opening the mold, and then drying the composite material in a normal pressure environment to obtain the surface anti-ablation layer of the nanoporous resin matrix composite material. The drying temperature is 20-120 deg.C, and the drying time is 24-48h.
Example 1
A preparation method of a nano-pore resin-based composite material containing a surface layer in-situ autogenous ablation-resistant layer comprises the following steps:
1. preparing a ceramic precursor solution: diluting the ceramic precursor in n-hexane to obtain a ceramic precursor solution with the concentration of 25 wt%;
2. quantitative spraying-drying-curing for multiple times: taking the density of 0.26g/cm 3 A quartz fiber felt with the size of 220 multiplied by 10mm is put flat, then a ceramic precursor solution is vertically sprayed on the surface layer of the quartz fiber felt by a spray gun, and then the quartz fiber felt is dried and solidified in a 100 ℃ oven for 6 hours and then taken out, wherein the specific spraying parameters are as follows: the spraying rate was 90ml/s, the spraying distance was 200mm, the spraying pressure was 0.2MPa, and the nozzle moving speed was 12cm/s. The spraying-drying-curing operation was repeated three times, and the bulk density of the fiber after the three spraying operations was 0.29g/cm 3 。
3. Oscillating and sintering: and (3) placing the fiber preform pretreated in the step (2) into a carbonization furnace, and sintering in a nitrogen atmosphere, wherein the specific oscillation temperature-raising program is controlled as follows: keeping the temperature for 10min at a temperature of between 10 ℃/min and 100 ℃; keeping the temperature for 10min at 15 ℃/min to 250 ℃; keeping the temperature for 10min at a temperature of between 10 and 350 ℃; keeping the temperature for 10min at 5 ℃/min to 400 ℃; keeping the temperature for 30min at the temperature of 10 ℃/min to 500 ℃; then cooled to room temperature at 10 ℃/min to obtain a fiber preform having a surface ablation-resistant layer.
4. Preparing a resin solution: dissolving phenolic resin by using a polar solvent isopropanol, and adding a curing agent hexamethylenetetramine with the mass of 14% of the resin to obtain a resin solution with the concentration of 30 wt%;
5. low-pressure impregnation: putting the quartz fiber preform with the surface ablation-resistant layer into a mold, and completely impregnating the quartz fiber felt with the resin solution at the impregnation pressure of 0.05MPa;
6. sol-gel reaction: sealing the mould, carrying out sol-gel reaction at 80 ℃, and cooling to room temperature after 48h of reaction to obtain a composite material;
7. drying under normal pressure: and opening the mold, and then drying the composite material for 48 hours in a normal-temperature normal-pressure environment to obtain the surface anti-ablation layer of the nanoporous resin matrix composite material.
Example 2
The difference from example 1 is that the concentration of the ceramic precursor solution in step 1 was 50wt%.
Example 3
The difference from example 1 is that the concentration of the ceramic precursor solution in step 1 was 75wt%.
Example 4
The difference from example 1 is that the concentration of the ceramic precursor solution in step 1 is 100wt%.
Example 5
The difference from example 1 is that the drying curing temperature in step 1 is 75 ℃ and the curing time is 12 hours.
Example 6
The difference from example 1 is that the drying curing temperature in step 1 is 50 ℃ and the curing time is 24h.
Comparative example 1
The difference from example 1 is that there is no step1, the fiber preform in the step 3 is a quartz fiber felt which is not subjected to surface layer ceramic pretreatment and has the density of 0.26g/cm 3 And the size is 220 multiplied by 10mm.
Comparative example 2
The difference from example 1 is that the fiber preform was pretreated in step 1 by immersing the entire fiber preform in a 5wt% ceramic precursor solution for 1 hour.
Comparative example 3
The difference from example 1 is that the fiber preform was pretreated with a single spray-cure in step 1, and the total amount of the single spray was the same as the total amount of the three sprays in example 1.
The phenolic resins in all examples and comparative examples were commercially available thermoplastic phenolic resins, and specific sources were, for example, jinan Dahui chemical industry, dongguan city Futai rubber, nantong Xin chemical industry, and Wuxi Xin Yehao chemical industry.
The oxyacetylene test, the bending strength test, and the compression strength test were performed on all the examples and comparative examples, and the results are shown in table 1 below.
Oxyacetylene test: oxyacetylene ablation experiments were performed using GJB 323A-1996 (2000 deg.C and 4.2 MW/m) 2 )；
Tensile strength test: the tensile strength of the material is tested by an electronic universal tester Meitess CMT4204, and the standard GB/T1447-2005 of the tensile property test method of the fiber reinforced plastics is adopted;
and (3) testing the compression strength: the compression strength of the material in the Z-axis direction (thickness direction) is tested by an electronic universal tester Meits CMT4204, and the compression performance test method standard GB/T1448-2005 of the fiber reinforced plastics is adopted.
TABLE 1
| Example 1 | Example 2 | Example 3 | Example 4 | Example 5 | Example 6 | Comparative example 1 | Comparative example 2 | Comparative example 3 | |
| Density/g.cm -3 | 0.66 | 0.65 | 0.66 | 0.67 | 0.69 | 0.64 | 0.66 | 0.67 | 0.66 |
| Concentration of ceramic precursor solution/%) | 25 | 50 | 75 | 100 | 25 | 25 | 25 | 5 | 25 |
| Pretreatment curing temperature/. Degree.C | 50 | 50 | 50 | 50 | 75 | 100 | / | 50 | 50 |
| Pretreatment curing time/h | 48 | 48 | 48 | 48 | 24 | 6 | / | 48 | 48 |
| Linear ablation rate/mm · s -1 | 0.138 | 0.135 | 0.130 | 0.148 | 0.136 | 0.135 | 0.155 | 0.148 | 0.142 |
| Mass burningCorrosion rate/mg s -1 | 24.3 | 25.1 | 26.3 | 27.5 | 24.3 | 24.1 | 28.1 | 26.5 | 25.3 |
| Back side temperature rise/deg.C | 61 | 65 | 72 | 98 | 63 | 62 | 40 | 26 | 63 |
| Tensile strength/MPa | 62 | 68 | 67 | 70 | 63 | 61 | 63 | 57 | 61 |
| Compressive strength/MPa | 224 | 250 | 248 | 244 | 223 | 226 | 229 | 204 | 228 |
The surface pattern of the ablation-resistant layer of the fiber preform surface layer in example 1 is shown in fig. 1, and after pretreatment, the gaps between the fibers of the preform surface layer are filled with the ceramic precursor and are distributed uniformly, which shows that the process of pretreating the fiber preform by multiple spraying-drying-curing can well avoid local non-uniformity of ablation resistance caused by too large amount of single spraying (for example, comparative example 3). The surface morphology of the composite material in example 1 is shown in fig. 3, the surface of the material has a grid-like texture, but no large-scale cracks, because the surface fibers and the resin are separated by the ceramic sheet layer in the resin impregnation process, so that the outermost thin layer of resin has no fiber support, and the volume of the resin shrinks greatly when the material is dried, and thus the grid-like cracks shown in fig. 3 occur. The SEM image of the cross section of the surface ablation resistant layer in example 1 is shown in FIG. 4, and the microstructure is complete and has no cracks, which indicates that the surface ceramic layer and the resin matrix are mutually filled, and the resin impregnation is not affected.
Compared with comparative example 1, the linear ablation rate and the mass ablation rate of examples 1 to 4 both show a tendency of decreasing and then increasing, because the surface anti-ablation ceramic layer has a good supporting function, the surface hardness of the material is increased, the resin and the pyrolytic carbon are prevented from being mechanically ablated, the resin can better exert the ablation heat-proof function, and the ablation rate is reduced. However, the excessive concentration of the precursor can reduce the amount of resin on the surface layer of the composite material, damage the ablation heat-proof function, increase the temperature inside the material quickly, and oxidize the resin matrix on the inner layer quickly, so that the ablation rate is increased on the contrary. The tensile and compressive strengths of examples 1-4 were slightly increased compared to comparative example 1 because the ceramic layer bonded adjacent fibers together in a sheet-like manner, which effectively increased the stiffness of the fibers of the preform surface layer, and thus increased the mechanical strength of the material, as shown in fig. 2, SEM image of the fiber surface layer after pretreatment in example 1.
Examples 1-4 compared to comparative example 2 show that the overall impregnation of the pre-treated fiber preform reduces the mechanical strength of the composite material because the untreated fiber has a large number of active groups such as hydroxyl groups on its surface, which can form stable chemical bonds with the resin, and the interface strength between the fiber and the resin matrix is large. After the integral dipping pretreatment, the surface active groups are covered by the ceramic precursor, the interface bonding strength between the fiber preform and the resin matrix is reduced, and the mechanical property of the material is reduced, so that the method for spraying the ceramic precursor in-situ autogenous ceramic layer on the surface layer of the fiber preform is further shown to not influence the integral interface bonding strength of the material, improve the ablation resistance and ensure the mechanical stability of the material. However, examples 1-4 have higher back temperature than comparative example 2 because comparative example 2 uses a bulk impregnation pretreatment of the fiber reinforcement, and only a thin ceramic layer is attached to the fiber surface, and there is no dense ceramic layer on the material surface, thus not affecting the overall nanoporous structure of the material and thus not having much impact on the thermal insulation performance of the material.
Compared with the comparative example 1, in the examples 1 to 4, although the material density is almost the same, the back temperature increases with the increase of the ceramic precursor concentration, because the unique porous structure of the nanoporous resin-based composite material can effectively reduce the thermal conductivity of the material, the radiative heat exchange of the material is negligible at room temperature, the ceramic component content in the surface layer of the material increases with the increase of the ceramic precursor concentration, the resin matrix content is reduced, and meanwhile, the fibers in the thickness direction (Z direction) are bridged by the ceramic component, so that the solid-state heat conduction in the direction is improved, and the overall thermal conductivity of the material is improved.
In conclusion, compared with the composite material without the protective layer, the composite material with the protective layer has the advantages that the ablation rate is obviously reduced, the mechanical property is improved, and the anti-ablation layer can effectively improve the ablation resistance of the nanoporous resin matrix composite material, improves the reliability of the material in extreme environments, and has wide application prospects in the field of thermal protection. Compared with the existing coating preparation method, the method has the advantages of simple process, low cost, high efficiency, safety, effectiveness and the like.
The foregoing is directed to preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope of the technical solution of the present invention.
Claims (10)
1. A preparation method of a nano-pore resin-based composite material containing a surface layer in-situ autogenous ablation-resistant layer is characterized by comprising the following steps:
preparing a ceramic precursor solution: dissolving a ceramic precursor in a nonpolar solvent to obtain a ceramic precursor solution;
pretreatment of the surface layer of the fiber felt: uniformly spraying the ceramic precursor solution on the surface layer of the fiber felt, and then drying and curing;
oscillating and sintering: putting the pretreated fibrofelt into a carbonization furnace, sintering in an inert atmosphere, and converting a ceramic precursor into an ablation-resistant ceramic layer in situ;
preparing a resin solution: dissolving resin by a polar solvent and adding a curing agent to obtain a resin solution;
low-pressure impregnation: placing the fiber felt after oscillation sintering in a mould, and completely soaking the fiber felt by using a resin solution;
sol-gel reaction: sealing the mould, carrying out sol-gel reaction, and cooling to room temperature after the reaction is finished to obtain a composite material;
drying under normal pressure: and opening the mould, and then drying the composite material in a normal pressure environment to obtain the nano-pore resin matrix composite material containing the surface layer in-situ spontaneous ablation resistant layer.
2. The method of claim 1, wherein the ceramic precursor comprises one or more of polycarbosilane, polysilaborazine, polysilazane, polysiloxane, and metallopolysilazane, and the nonpolar solvent comprises one or more of n-hexane, n-heptane, cyclohexane, or toluene.
3. The method for preparing a nanoporous resin-based composite material containing a superficial in-situ autogenous ablation-resistant layer according to claim 1, wherein the mass fraction of the ceramic precursor in the ceramic precursor solution is 25-100wt%, and the mass fraction of the non-polar solvent is 0-75wt%.
4. The method for preparing the nanoporous resin-based composite material with the in-situ autogenous ablation-resistant surface layer as claimed in claim 1, wherein the fiber mat comprises a fiber mat woven from one or more of carbon fibers, quartz fibers, mullite fibers, phenolic fibers or polyacrylonitrile fibers.
5. The method for preparing the nano-pore resin-based composite material with the in-situ self-generated ablation-resistant surface layer as claimed in claim 1, wherein the structural form of the fiber felt comprises a quasi-three-dimensional needle-punched structure, a fiber cloth layer structure, a needle-punched fiber felt structure or a 2.5D weaving structure, and the density of the fiber felt is 0.1-0.5g/cm 3 The thickness is 10-30mm.
6. The method for preparing a nanoporous resin-based composite material comprising a superficial in-situ autogenous ablation-resistant layer according to claim 1, wherein the temperature for curing the ceramic precursor is 50-100 ℃ and the time is 6-48h.
7. The preparation method of the nanoporous resin-based composite material containing the in-situ autogenous ablation-resistant layer of the surface layer as claimed in claim 1, wherein the spraying method is a multi-time quantitative spraying-drying-curing process; the volume of the ceramic precursor solution sprayed for one time is 30-50ml, and the total volume sprayed is 90-150ml.
8. The method for preparing a nanoporous resin-based composite material comprising a superficial in-situ autogenous ablation-resistant layer according to claim 1, wherein the spray gun is perpendicular to the surface of the fibrofelt during spraying, the spraying pressure is 0.1-0.3MPa, the spraying height is 100-200mm, and the moving speed of the spray nozzle is 10-12cm/s.
9. The method for preparing the nanoporous resin-based composite material with the in-situ self-generated ablation-resistant surface layer according to claim 1, wherein the basic heating rate of the oscillating heating sintering is 10 ℃/min, the oscillation amplitude is +/-5 ℃/min, the oscillation frequency is 1/15-1/60Hz, the holding time of each oscillation is 1-10min, and the end point temperature is 450-550 ℃.
10. The method for preparing a nanoporous resin-based composite material comprising a superficial in-situ autogenous ablation-resistant layer according to claim 1, wherein the polar solvent comprises one or more of n-butanol, isopropanol, ethanol or ethylene glycol; the temperature of the sol-gel reaction is 80-140 ℃, and the time is 24-48h; the drying temperature is 20-120 ℃, and the drying time is 24-48h.
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