阅读说明：本技术 一种超高温轻质热防护材料大梯度过渡层的制备方法 (Preparation method of large-gradient transition layer of ultrahigh-temperature light thermal protection material ) 是由 李同起 刘宇峰 *** 张大海 于 2019-10-17 设计创作，主要内容包括：本发明涉及一种超高温轻质热防护材料大梯度过渡层的实现方法,属无机超高温防护材料领域。所述方法以氧化防护碳纤维增强骨架为超高温轻质热防护材料,采用液相诱导涂覆浸渍-固化方法将不同膨胀系数的超高温陶瓷粉体引入到材料表层的不同深度范围,通过不同次数引入实现不同深度范围内孔隙填充度的控制,实现材料表层热膨胀系数和孔隙填充度的梯度变化,通过高温烧结进行陶瓷化,形成大梯度过渡层制备,实现了过渡层与超高温轻质热防护材料的一体化,对超高温轻质热防护材料表层力学性能有良好的增强效果。(The invention relates to a method for realizing a large-gradient transition layer of an ultrahigh-temperature light thermal protection material, belonging to the field of inorganic ultrahigh-temperature protection materials. The method takes an oxidation protection carbon fiber reinforced framework as an ultrahigh-temperature light thermal protection material, adopts a liquid-phase induced coating, dipping and curing method to introduce ultrahigh-temperature ceramic powder with different expansion coefficients into different depth ranges of a material surface layer, realizes control of pore filling degrees in different depth ranges through introduction of different times, realizes gradient change of a material surface layer thermal expansion coefficient and the pore filling degrees, carries out ceramic formation through high-temperature sintering, forms a large-gradient transition layer, realizes integration of the transition layer and the ultrahigh-temperature light thermal protection material, and has a good enhancement effect on the mechanical properties of the ultrahigh-temperature light thermal protection material surface layer.)

1. A preparation method of a large-gradient transition layer of an ultrahigh-temperature light thermal protection material is characterized by comprising the following steps of:

(1) taking a high-temperature ceramic precursor, high-carbon residue resin or a solvent as liquid phase carriers, respectively taking high-temperature ceramic powder with a low thermal expansion coefficient, high-temperature ceramic powder with a medium thermal expansion coefficient and high-temperature ceramic powder with a high thermal expansion coefficient as fillers, and respectively mixing the three fillers with the liquid phase carriers to prepare three liquid phase coating impregnating slurries, wherein the impregnating slurry formed by the low thermal expansion coefficient ceramic is taken as D slurry, the impregnating slurry formed by the medium thermal expansion coefficient ceramic is taken as Z slurry, and the impregnating slurry formed by the high thermal expansion coefficient ceramic is taken as G slurry;

(2) respectively filling three liquid-phase coating dipping slurry D slurry, Z slurry and G slurry prepared in the step (1) into the surface layer of an oxidation protection carbon fiber reinforced framework which takes a carbon fiber reinforced framework as a main body and has a high-temperature oxidation protection coating on the inner hole wall, controlling different filling depth ranges and different pore filling rates, and then curing, wherein the process is as follows:

firstly, coating a solvent on the surface of an oxidation protection carbon fiber reinforced framework, forming a continuous liquid film on the surface layer, continuously coating D slurry on the surface of the liquid film, drying the liquid film, heating and curing, repeating the coating and curing process for 1-2 times until the depth of the D slurry on the oxidation protection surface layer of the carbon fiber reinforced framework is H ₁；

And then according to the method for coating and curing the D sizing agent, sequentially coating and penetrating the Z sizing agent and the G sizing agent to the depth H of the surface layer of the carbon fiber reinforced framework material ₂And H ₃Within the range, after being dried and heated and cured, the three ceramic materials with different thermal expansion coefficients are prepared and respectively arranged at different depths H in sequence ₁、H ₂And H ₃Completing pore coating and filling of the ultrahigh-temperature light thermal protection material within the range;

(3) and (3) carrying out high-temperature sintering treatment on the ultrahigh-temperature light thermal protection material which is prepared in the step (2) and is coated and filled in the pores, so as to obtain the ultrahigh-temperature light thermal protection material with the integrated large-gradient transition layer.

2. The method for preparing the ultrahigh-temperature light thermal protection material large-gradient transition layer according to claim 1, wherein the high-temperature ceramic powder with the low thermal expansion coefficient in the step (1) has a thermal expansion coefficient of not more than 5 x 10 ^-6The high-temperature ceramic powder with the medium thermal expansion coefficient means that the thermal expansion coefficient is 5 multiplied by 10 ^-6/K～7×10 ^-6In the range of/K, the high-temperature ceramic powder with high thermal expansion coefficient means that the thermal expansion coefficient is more than or equal to 7 multiplied by 10 ^-6/K。

3. The method for preparing the ultrahigh-temperature light thermal protection material large-gradient transition layer according to claim 1, wherein the high-temperature ceramic powder with the low thermal expansion coefficient in the step (1) and the high-temperature ceramic powder with the medium thermal expansion coefficient in the step (1) are prepared by the method of preparing the ultrahigh-temperature light thermal protection material large-gradient transition layerThe difference in thermal expansion coefficient between the ceramic powders is 1.0X 10 ^-6/K～2.3×10 ^-6In the range of/K, the difference of the thermal expansion coefficients between the high-temperature ceramic powder with the medium thermal expansion coefficient and the high-temperature ceramic powder with the high thermal expansion coefficient is 1.0 multiplied by 10 ^-6/K～2.3×10 ^-6In the range of/K.

4. The method for preparing the large gradient transition layer of the ultra-high temperature lightweight thermal protective material according to claim 1, wherein the high temperature ceramic powder in step (1) is selected from carbides of B, Hf, Zr, Ti, Nb, Mo, Ta and Si, or from borides of B, Hf, Zr, Ti, Nb, Mo, Ta and Si, or from silicides of B, Hf, Zr, Ti, Nb, Mo, Ta and Si, or from nitrides of B, Hf, Zr, Ti, Nb, Mo, Ta and Si.

5. The method for preparing the ultrahigh-temperature light thermal protection material large-gradient transition layer according to claim 1, wherein the particle size D of the high-temperature ceramic powder in the step (1) ₉₀Less than 1/2 and greater than 100nm of the average porosity of the oxidation protected carbon fiber reinforced skeleton.

6. The method for preparing the ultrahigh-temperature light thermal protection material large-gradient transition layer according to claim 5, wherein the ceramic powder has the optimized particle size D ₉₀Less than 1/3 of average porosity of the oxidation protected carbon fiber reinforced skeleton.

7. The method for preparing the ultrahigh-temperature light thermal protection material large-gradient transition layer according to claim 1, wherein the high-temperature ceramic precursor in the step (1) comprises polycarbosilane, silicon carbon nitrogen resin and silicon boron carbon nitrogen resin.

8. The method for preparing the ultrahigh-temperature light thermal protection material large-gradient transition layer according to claim 1, wherein the high-carbon-residue resin in the step (1) is high-carbon-residue phenolic resin or furfuryl ketone resin.

9. The preparation method of the ultrahigh-temperature light thermal protection material large-gradient transition layer according to claim 1, wherein the solvent in the step (1) is a benzene solvent, an alcohol solvent, a ketone solvent or an alkane solvent, and the solvent is selected from toluene, xylene, ethanol, n-hexane and acetone.

10. The preparation method of the ultrahigh-temperature light thermal protection material large-gradient transition layer according to claim 1, wherein the volume ratio of the ceramic powder filler to the liquid-phase carrier in the step (1) is 1 (0.5-5), the fluidity of the mixed slurry is realized by adding a proper amount of organic solvent, and the viscosity range of the mixed slurry is controlled within 10 s-100 s.

11. The method for preparing the large-gradient transition layer of the ultra-high temperature lightweight thermal protection material according to claim 1, wherein the oxidation protection capability of the high-temperature oxidation protection coating of the ultra-high temperature lightweight thermal protection material in the step (2) exceeds 1800 ℃, and the density of the oxidation protection carbon fiber reinforced skeleton is 0.20g/cm ³～0.80g/cm ³The average pore diameter is 10-100 μm, and the coating material is one or the combination of two or more of silicon carbide, hafnium carbide, zirconium carbide, titanium carbide, molybdenum silicide, zirconium boride and hafnium boride.

12. The method for preparing the ultrahigh-temperature lightweight thermal protective material large-gradient transition layer according to claim 1, wherein the liquid carriers used in the D slurry, the Z slurry and the G slurry in the step (2) are the same or different.

13. The method for preparing the ultrahigh-temperature light thermal protection material large-gradient transition layer according to claim 1, wherein the D slurry, the Z slurry and the G slurry in the step (2) are respectively coated and filled in different depth ranges by adopting different pore filling rates, and the D slurry is coated and filled in the H range ₁-H ₂Filling in depth range, and the porosity filling rate is 10-50%Internal; d slurry and Z slurry are mixed and filled in the H ₂-H ₃The depth range, the pore filling rate is within the range of 30-80%; d slurry, Z slurry and G slurry are mixed and filled in the H ₃Within the depth range, the pore filling rate is within the range of 60-100%; and said H ₁-H ₂Filling degree in depth range, H ₂-H ₃Filling degree and H in depth range ₃The degree of filling in the depth range increases in turn.

14. The method for preparing the ultrahigh-temperature lightweight thermal protective material large-gradient transition layer according to claim 1, wherein the H in the step (2) ₁In the range of 3mm to 10mm, said H ₂In the range of 1mm to 6mm, said H ₃In the range of 0.2mm to 3mm, and said H ₁>H ₂>H ₃。

15. The preparation method of the ultrahigh-temperature light thermal protection material large-gradient transition layer according to claim 1, wherein the heating and curing process in the step (2) is performed under vacuum or inert gas protection, and the curing temperature is 80-300 ℃.

16. The preparation method of the ultrahigh-temperature light thermal protection material large-gradient transition layer according to claim 1, wherein the high-temperature sintering treatment in the step (3) is performed under the protection of inert gas or under vacuum, the temperature is 1200 ℃ to 2000 ℃, the treatment time is 1 to 3 hours, and further preferably, the sintering temperature is 1500 ℃ to 1800 ℃.

17. An ultrahigh-temperature light thermal protection material is characterized by comprising an oxidation protection carbon fiber reinforced skeleton which takes a carbon fiber reinforced skeleton as a main body and is provided with a high-temperature oxidation protection coating on the inner hole wall, a thermal stress slow-release transition layer prepared on the surface layer of the material, and an ultrahigh-temperature protection layer prepared on the surface of the thermal stress slow-release transition layer, wherein the thermal stress slow-release transition layer is prepared according to the method of claim 1.

18. The ultra-high temperature lightweight thermal protection material according to claim 17, wherein the material of the ultra-high temperature protective layer is one or a combination of two or more of silicon carbide, hafnium carbide, zirconium carbide, titanium carbide, molybdenum silicide, zirconium boride and hafnium boride.

Technical Field

The invention relates to a preparation method of a large-gradient transition layer of an ultrahigh-temperature light thermal protection material, belonging to the technical field of inorganic ultrahigh-temperature protection materials.

Background

The high-speed and light-weight development of aircrafts puts a clear demand on ultrahigh-temperature light thermal protection materials with the temperature of over 1800 ℃, and the traditional ceramic fiber light thermal protection materials (ceramic heat insulation tiles) cannot be applied in the industry because of low temperature resistance (generally lower than 1500 ℃), so that the ultrahigh-temperature light thermal protection materials consisting of carbon fiber reinforced frameworks for oxidation protection and surface ultrahigh-temperature protection layers become one of important directions for the development of the technical field of ultrahigh-temperature thermal protection materials.

In the ultrahigh-temperature light thermal protection material, the oxidation-protected carbon fiber reinforced skeleton is mainly used for supporting the ultrahigh-temperature heat insulation and protection layer, and the surface ultrahigh-temperature protection layer is mainly used for resisting the scouring of high-temperature pneumatic heat flow and preventing the internal skeleton from being burnt. The ultra-high temperature protective layer is a compact system generally composed of ultra-high temperature ceramics, and has a large thermal expansion coefficient and high bearing capacity. The carbon fiber reinforced skeleton is a light material system with low density, and has small thermal expansion coefficient and weak mechanical bearing capacity. Due to the great difference of physical properties between the ultrahigh-temperature protective layer and the carbon fiber reinforced framework, great thermal stress exists between the two layers of the integrated ultrahigh-temperature light thermal protection material in high-temperature service, and the integrated material is easily damaged. Therefore, the construction of the thermal stress slow-release transition layer between the two layers is an important way for effectively solving the thermal stress damage.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, and provides a preparation method of a large-gradient transition layer of an ultrahigh-temperature light thermal protection material, which solves the requirement of the ultrahigh-temperature light thermal protection material on a gradient transition stress slow-release transition layer and realizes the preparation of the thermal stress slow-release transition layer for the ultrahigh-temperature light thermal protection material.

In order to achieve the above purpose, the invention provides the following technical scheme:

a preparation method of a large-gradient transition layer of an ultrahigh-temperature light thermal protection material comprises the following steps:

(1) taking a high-temperature ceramic precursor, high-carbon residue resin or a solvent as liquid phase carriers, respectively taking high-temperature ceramic powder with a low thermal expansion coefficient, high-temperature ceramic powder with a medium thermal expansion coefficient and high-temperature ceramic powder with a high thermal expansion coefficient as fillers, and respectively mixing the three fillers with the liquid phase carriers to prepare three liquid phase coating impregnating slurries, wherein the impregnating slurry formed by the low thermal expansion coefficient ceramic is taken as D slurry, the impregnating slurry formed by the medium thermal expansion coefficient ceramic is taken as Z slurry, and the impregnating slurry formed by the high thermal expansion coefficient ceramic is taken as G slurry;

(2) respectively filling three liquid-phase coating dipping slurry D slurry, Z slurry and G slurry prepared in the step (1) into the surface layer of an oxidation protection carbon fiber reinforced framework which takes a carbon fiber reinforced framework as a main body and has a high-temperature oxidation protection coating on the inner hole wall, controlling different filling depth ranges and different pore filling rates, and then curing, wherein the process is as follows:

firstly, coating a solvent on the surface of an oxidation protection carbon fiber reinforced framework, forming a continuous liquid film on the surface layer, continuously coating D slurry on the surface of the liquid film, drying the liquid film, heating and curing, repeating the coating and curing process for 1-2 times until the depth of the D slurry on the oxidation protection surface layer of the carbon fiber reinforced framework is H ₁；

And then according to the method for coating and curing the D sizing agent, sequentially coating and penetrating the Z sizing agent and the G sizing agent to the depth H of the surface layer of the carbon fiber reinforced framework material ₂And H ₃Within the range, after being dried and heated and cured, the three ceramic materials with different thermal expansion coefficients are prepared and respectively arranged at different depths H in sequence ₁、H ₂And H ₃Completing pore coating and filling of the ultrahigh-temperature light thermal protection material within the range;

(3) and (3) carrying out high-temperature sintering treatment on the ultrahigh-temperature light thermal protection material which is prepared in the step (2) and is coated and filled in the pores, so as to obtain the ultrahigh-temperature light thermal protection material with the integrated large-gradient transition layer.

In an optional embodiment, the high-temperature ceramic powder with low thermal expansion coefficient in the step (1) refers to that the thermal expansion coefficient is less than or equal to 5 × 10 ^-6The high-temperature ceramic powder with the medium thermal expansion coefficient means that the thermal expansion coefficient is 5 multiplied by 10 ^-6/K～7×10 ^-6In the range of/K, the high-temperature ceramic powder with high thermal expansion coefficient means that the thermal expansion coefficient is more than or equal to 7 multiplied by 10 ^-6/K。

In an optional embodiment, the difference between the thermal expansion coefficients of the high-temperature ceramic powder with the low thermal expansion coefficient and the high-temperature ceramic powder with the medium thermal expansion coefficient in step (1) is 1.0 × 10 ^-6/K～2.3×10 ^-6In the range of/K, the difference of the thermal expansion coefficients between the high-temperature ceramic powder with the medium thermal expansion coefficient and the high-temperature ceramic powder with the high thermal expansion coefficient is 1.0 multiplied by 10 ^-6/K～2.3×10 ^-6In the range of/K.

In an optional embodiment, the high-temperature ceramic powder in step (1) is a carbide of B, Hf, Zr, Ti, Nb, Mo, Ta, Si, or the like, or a boride selected from B, Hf, Zr, Ti, Nb, Mo, Ta, Si, or a silicide selected from B, Hf, Zr, Ti, Nb, Mo, Ta, Si, or a nitride selected from B, Hf, Zr, Ti, Nb, Mo, Ta, Si.

In an optional embodiment, the particle size D of the high-temperature ceramic powder in step (1) ₉₀1/2 less than average pore of oxidation-proof carbon fiber reinforced skeleton and more than 100nm, preferably optimized ceramic powder particle size D ₉₀Less than 1/3 of average porosity of the oxidation protected carbon fiber reinforced skeleton.

In an optional embodiment, the high-temperature ceramic precursor in step (1) refers to a liquid-phase precursor that contains high-temperature ceramic powder constituent elements and can form high-temperature ceramic after high-temperature pyrolysis, and the preferred high-temperature ceramic precursor includes polycarbosilane, silicon carbon nitrogen resin, and silicon boron carbon nitrogen resin.

In an alternative embodiment, the high carbon residue resin in step (1) refers to a high carbon residue phenolic resin or a furfuryl ketone resin.

In an alternative embodiment, the solvent in step (1) refers to a volatile solvent having good wettability with the thermal protective material and capable of rapidly dissolving the high-temperature ceramic precursor or the high-carbon residue resin, such as a benzene series solvent, an alcohol solvent, a ketone solvent, an alkane solvent, and the like, and preferably, the solvent is selected from toluene, xylene, ethanol, n-hexane, and acetone.

In an optional embodiment, the volume ratio of the ceramic powder filler to the liquid-phase carrier in the step (1) is 1 (0.5-5), the fluidity of the mixed slurry can be realized by adding a proper amount of organic solvent, and the viscosity range of the mixed slurry is controlled within 10 s-100 s.

In an optional embodiment, the oxidation prevention capacity of the high-temperature oxidation prevention coating of the ultra-high temperature light thermal protection material in the step (2) exceeds 1800 ℃, and the density of the oxidation prevention carbon fiber reinforced skeleton is 0.20g/cm ³～0.80g/cm ³The average pore diameter is 10-100 μm, and the coating material is one or the combination of two or more of silicon carbide, hafnium carbide, zirconium carbide, titanium carbide, molybdenum silicide, zirconium boride and hafnium boride.

In an alternative embodiment, the liquid carriers used for the D slurry, the Z slurry and the G slurry in step (2) may be the same or different.

In an alternative embodiment, the D paste, the Z paste and the G paste in the step (2) are respectively coated and filled in different depth ranges by adopting different pore filling rates, and the D paste is coated and filled in the H range ₁-H ₂Filling in a depth range, wherein the porosity filling rate is within a range of 10-50%; d slurry and Z slurry are mixed and filled in the H ₂-H ₃The pore filling rate is within the range of 30-80 percent within the depth rangeInternal; d slurry, Z slurry and G slurry are mixed and filled in the H ₃Within the depth range, the pore filling rate is within the range of 60-100%; and said H ₁-H ₂Filling degree in depth range, H ₂-H ₃Filling degree and H in depth range ₃The degree of filling in the depth range increases in turn.

In an alternative embodiment, H is as described in step (2) ₁In the range of 3mm to 10mm, said H ₂In the range of 1mm to 6mm, said H ₃In the range of 0.2mm to 3mm, and said H ₁>H ₂>H ₃。

In an optional embodiment, the oxidation of the high-temperature ceramic powder and the liquid-phase carrier is prevented, and the heating and curing process in the step (2) is performed under the protection of vacuum or inert gas, and the curing temperature is 80-300 ℃.

In an optional embodiment, the high-temperature sintering treatment in the step (3) is performed under the protection of inert gas or under vacuum, the temperature is 1200 ℃ to 2000 ℃, the treatment time is 1 to 3 hours, and further preferably, the sintering temperature is 1500 ℃ to 1800 ℃.

The invention also provides the following technical scheme:

the ultrahigh-temperature light thermal protection material comprises an oxidation protection carbon fiber reinforced framework which takes a carbon fiber reinforced framework as a main body and is provided with a high-temperature oxidation protection coating on the inner hole wall, a thermal stress slow-release transition layer prepared on the surface layer of the material, and an ultrahigh-temperature protection layer prepared on the surface of the thermal stress slow-release transition layer, wherein the thermal stress slow-release transition layer is prepared according to the preparation method of the ultrahigh-temperature light thermal protection material large-gradient transition layer.

In an optional embodiment, the material of the ultra-high temperature protective layer is selected from one or a combination of two or more of silicon carbide, hafnium carbide, zirconium carbide, titanium carbide, molybdenum silicide, zirconium boride and hafnium boride.

Compared with the prior art, the invention has the following beneficial effects:

(1) according to the preparation method of the large-gradient transition layer of the ultrahigh-temperature light thermal protection material, provided by the embodiment of the invention, the gradient change of components and structures of the surface layer is realized by filling the high-temperature ceramics with different thermal expansion coefficients and different filling degrees in different depth ranges of the surface layer of the oxidation protection carbon fiber reinforced framework, so that an effective thermal stress gradient slow-release transition layer is provided for the ultrahigh-temperature light thermal protection material;

(2) according to the preparation method of the large-gradient transition layer of the ultrahigh-temperature light thermal protection material, provided by the embodiment of the invention, the liquid-phase induced coating, dipping and curing method is adopted, so that the effective filling of high-temperature ceramic components with different thermal expansion coefficients in different depth ranges of the surface layer of the oxidation protection carbon fiber reinforced framework can be realized, the effective control of the filling degree can be realized by controlling the filling times, and a means is provided for the formation of the gradient transition layer;

(3) according to the preparation method of the large-gradient transition layer of the ultrahigh-temperature light thermal protection material, the prepared transition layer is embedded into the surface layer of the oxidation protection carbon fiber reinforced framework, so that the integration of the transition layer and the ultrahigh-temperature light thermal protection material is realized, the compatibility of the filling phase and the oxidation protection carbon fiber reinforced framework is good, and the problems of material damage or obvious performance reduction caused by poor compatibility can be avoided;

(4) according to the preparation method of the large-gradient transition layer of the ultra-high temperature light thermal protection material, the prepared transition layer has good high-temperature oxidation resistance, and the survival capability of the ultra-high temperature light thermal protection material in a high-temperature aerobic environment can be greatly improved;

(5) according to the preparation method of the large-gradient transition layer of the ultra-high temperature light thermal protection material, provided by the embodiment of the invention, the prepared transition layer has a good effect of enhancing the surface mechanical property of the ultra-high temperature light thermal protection material, and the service performance of the ultra-high temperature light thermal protection material can be greatly improved.

Drawings

Fig. 1 is a schematic structural diagram in the thickness direction of an integrated large-gradient transition layer prepared on a surface layer of an oxidation-protected carbon fiber reinforced skeleton according to an embodiment of the present invention;

① is a high coefficient of thermal expansion ceramicA filling layer ② is a medium thermal expansion coefficient ceramic filling layer ③ is a low thermal expansion coefficient ceramic filling layer ④ is an oxidation protection carbon fiber reinforced skeleton H ₁A low coefficient of thermal expansion ceramic fill depth; h ₂The depth of the ceramic filling layer with the medium thermal expansion coefficient; h ₃The depth of the ceramic filling layer with high thermal expansion coefficient.

Detailed Description

The following description will further explain embodiments of the present invention by referring to specific examples and drawings, but the present invention is not limited to the following examples.

The embodiment of the invention provides a preparation method of a large-gradient transition layer of an ultrahigh-temperature light thermal protection material, which comprises the following steps:

(1) taking a high-temperature ceramic precursor, high-carbon residue resin or a solvent as liquid phase carriers, respectively taking high-temperature ceramic powder with a low thermal expansion coefficient, high-temperature ceramic powder with a medium thermal expansion coefficient and high-temperature ceramic powder with a high thermal expansion coefficient as fillers, and respectively mixing the three fillers with the liquid phase carriers to prepare three liquid phase coating impregnating slurries, wherein the impregnating slurry formed by the low thermal expansion coefficient ceramic is taken as D slurry, the impregnating slurry formed by the medium thermal expansion coefficient ceramic is taken as Z slurry, and the impregnating slurry formed by the high thermal expansion coefficient ceramic is taken as G slurry;

(2) respectively filling three liquid-phase coating dipping slurry D slurry, Z slurry and G slurry prepared in the step (1) into an oxidation protection carbon fiber reinforced framework surface layer which takes a carbon fiber reinforced framework as a main body and has a high-temperature oxidation protection coating on the inner hole wall, controlling different filling depth ranges and different pore filling rates, and then curing, wherein the process is as follows:

firstly, coating a solvent on the surface of an oxidation protection carbon fiber reinforced framework, forming a continuous liquid film on the surface layer, continuously coating D slurry on the surface of the liquid film, drying the liquid film, heating and curing, repeating the coating and curing process for 1-2 times until the depth of the D slurry on the oxidation protection surface layer of the carbon fiber reinforced framework is H ₁；

Followed by coatingAnd D slurry coating and curing method, namely respectively coating the Z slurry and the G slurry in sequence and penetrating the Z slurry and the G slurry to the depth H of the surface layer of the carbon fiber reinforced framework material ₂And H ₃Within the range, after being dried and heated and cured, the three ceramic materials with different thermal expansion coefficients are prepared and respectively arranged at different depths H in sequence ₁、H ₂And H ₃Completing pore coating and filling of the ultrahigh-temperature light thermal protection material within the range;

(3) and (3) carrying out high-temperature sintering treatment on the ultrahigh-temperature light thermal protection material which is prepared in the step (2) and is coated and filled in the pores, so as to obtain the ultrahigh-temperature light thermal protection material with the integrated large-gradient transition layer.

The preparation method provided by the embodiment of the invention is to sinter the ceramic powder and the solidified liquid phase carrier so as to form the integrated large-gradient transition layer consisting of different filling degrees and different filling phases in different depth ranges.

Specifically, in the embodiment of the present invention, the high-temperature ceramic powder with a low thermal expansion coefficient in step (1) refers to a ceramic powder with a thermal expansion coefficient of not more than 5 × 10 ^-6The high-temperature ceramic powder with the medium thermal expansion coefficient means that the thermal expansion coefficient is 5 multiplied by 10 ^-6/K～7×10 ^-6In the range of/K, the high-temperature ceramic powder with high thermal expansion coefficient means that the thermal expansion coefficient is more than or equal to 7 multiplied by 10 ^-6/K。

Specifically, in the embodiment of the present invention, the difference between the thermal expansion coefficients of the high-temperature ceramic powder with a low thermal expansion coefficient and the high-temperature ceramic powder with a medium thermal expansion coefficient in step (1) is 1.0 × 10 ^-6/K～2.3×10 ^-6In the range of/K, the difference of the thermal expansion coefficients between the high-temperature ceramic powder with the medium thermal expansion coefficient and the high-temperature ceramic powder with the high thermal expansion coefficient is 1.0 multiplied by 10 ^-6/K～2.3×10 ^-6In the range of/K.

Specifically, in the embodiment of the present invention, the high-temperature ceramic powder in step (1) is a carbide of boron (B), hafnium (Hf), zirconium (Zr), titanium (Ti), niobium (Nb), molybdenum (Mo), tantalum (Ta), silicon (Si), or the like, or a boride selected from B, Hf, Zr, Ti, Nb, Mo, Ta, and Si, or a silicide selected from B, Hf, Zr, Ti, Nb, Mo, Ta, and Si, or a nitride selected from B, Hf, Zr, Ti, Nb, Mo, Ta, and Si.

Specifically, in the embodiment of the present invention, the particle size D of the high-temperature ceramic powder in step (1) is ₉₀1/2 less than average pore of oxidation-proof carbon fiber reinforced skeleton and more than 100nm, preferably optimized ceramic powder particle size D ₉₀Less than 1/3 of average porosity of the oxidation protected carbon fiber reinforced skeleton.

Specifically, in the embodiment of the present invention, the high-temperature ceramic precursor in step (1) refers to a liquid-phase precursor that contains high-temperature ceramic powder constituent elements and can form high-temperature ceramic after high-temperature pyrolysis. Preferred high temperature ceramic precursors include polycarbosilanes, silicon carbon nitrogen resins, silicon boron carbon nitrogen resins.

Specifically, in the embodiment of the present invention, the high carbon residue resin in step (1) refers to a high carbon residue phenolic resin or a high carbon residue furfuryl ketone resin.

Specifically, in the embodiment of the present invention, the solvent in step (1) refers to a volatilizable solvent that has good wettability with the thermal protection material and can rapidly dissolve the high-temperature ceramic precursor or the high-carbon residue resin, such as a benzene series solvent, an alcohol solvent, a ketone solvent, an alkane solvent, and the like, and is preferably toluene, xylene, ethanol, n-hexane, acetone, and the like.

Specifically, in the embodiment of the invention, the volume ratio of the ceramic powder filler to the liquid-phase carrier in the step (1) is 1 (0.5-5), the fluidity of the mixed slurry can be realized by adding a proper amount of organic solvent, and the viscosity range of the mixed slurry is preferably controlled within the range of 10 s-100 s.

Specifically, in the embodiment of the invention, the oxidation prevention capacity of the high-temperature oxidation prevention coating of the ultrahigh-temperature light-weight thermal protection material in the step (2) is more than 1800 ℃, and the density of the oxidation prevention carbon fiber reinforced skeleton is 0.20g/cm ³～0.80g/cm ³The average pore diameter is 10-100 μm, and the coating material is one or the combination of two or more of silicon carbide, hafnium carbide, zirconium carbide, titanium carbide, molybdenum silicide, zirconium boride and hafnium boride.

Specifically, in the embodiment of the present invention, the liquid carriers used for the D slurry, the Z slurry, and the G slurry in step (2) may be the same or different.

Specifically, in the embodiment of the invention, in the step (2), the D slurry, the Z slurry and the G slurry are sequentially filled into different depth ranges of the surface layer of the ultra-high temperature lightweight thermal protection material by a liquid-phase induction coating and dipping method, and are cured.

More specifically, the ceramic powder containing low thermal expansion coefficient is solidified to a certain depth H of the surface layer of the high-temperature oxidation protection carbon fiber reinforced framework through the capillary adsorption liquid phase induction of the solvent ₁Within the range, the ceramic powder containing the coefficient of thermal expansion is solidified to a certain depth H of the surface layer of the high-temperature oxidation protection carbon fiber reinforced framework ₂Within the range, the ceramic powder containing high thermal expansion coefficient is solidified to a certain depth H of the surface layer of the high-temperature oxidation protection carbon fiber reinforced framework ₃Within the range. And finally realizing the pore filling of the ceramic materials with different thermal expansion coefficients in different depth ranges after drying and curing.

More specifically, in the formed large gradient transition layer, H ₁-H ₂The filling phase in the depth range is a ceramic filling phase with a low thermal expansion coefficient, and the porosity filling rate is within the range of 10-50%; h ₂-H ₃The filling phase in the depth range is a low-thermal expansion coefficient ceramic and medium-thermal expansion coefficient ceramic mixed filling phase, and the porosity filling rate is in the range of 30-80%; h ₃The filling phase in the depth range is a mixed filling phase of low thermal expansion coefficient ceramic, medium thermal expansion coefficient ceramic and high thermal expansion coefficient ceramic, and the porosity filling rate is in the range of 60-100%. And H ₁-H ₂Depth range, H ₂-H ₃Within depth and H ₃The filling degree in the depth range is sequentially improved. Generally, after the filling of the high-temperature ceramic with the low thermal expansion coefficient is completed, the high-temperature ceramic with the medium thermal expansion coefficient is filled, and finally the high-temperature ceramic with the high thermal expansion coefficient is filled.

In particular, the H ₁In the range of 3mm to 10mm, said H ₂In the range of 1mm to 6mm, said H ₃Is in the range of 0.2mm to 3mm, andsaid H ₁>H ₂>H ₃。

Specifically, in the embodiment of the invention, the oxidation of the high-temperature ceramic powder and the liquid-phase carrier is prevented, the heating and curing process in the step (2) is carried out under the protection of vacuum or inert gas, and the curing temperature is 80-300 ℃.

Specifically, in the embodiment of the present invention, the high-temperature sintering treatment in step (3) is performed under the protection of an inert gas or under vacuum, the temperature is 1200 ℃ to 2000 ℃, the treatment time is 1 to 3 hours, and more preferably, the sintering temperature is 1500 ℃ to 1800 ℃.

The embodiment of the invention also provides an ultrahigh-temperature light thermal protection material, which comprises an oxidation protection carbon fiber reinforced framework taking a carbon fiber reinforced framework as a main body and provided with a high-temperature oxidation protection coating on the inner hole wall, a thermal stress slow-release transition layer prepared on the surface layer of the material, and an ultrahigh-temperature protection layer prepared on the surface of the thermal stress slow-release transition layer, wherein the thermal stress slow-release transition layer is prepared according to the preparation method of the large-gradient transition layer of the ultrahigh-temperature light thermal protection material, and specifically comprises the following steps:

(1) taking a high-temperature ceramic precursor, high-carbon residue resin or a solvent as liquid phase carriers, respectively taking high-temperature ceramic powder with a low thermal expansion coefficient, high-temperature ceramic powder with a medium thermal expansion coefficient and high-temperature ceramic powder with a high thermal expansion coefficient as fillers, and respectively mixing the three fillers with the liquid phase carriers to prepare three liquid phase coating impregnating slurries, wherein the impregnating slurry formed by the low thermal expansion coefficient ceramic is taken as D slurry, the impregnating slurry formed by the medium thermal expansion coefficient ceramic is taken as Z slurry, and the impregnating slurry formed by the high thermal expansion coefficient ceramic is taken as G slurry;

(2) respectively filling three liquid-phase coating dipping slurry D slurry, Z slurry and G slurry prepared in the step (1) into the surface layer of an oxidation protection carbon fiber reinforced framework which takes a carbon fiber reinforced framework as a main body and has a high-temperature oxidation protection coating on the inner hole wall, controlling different filling depth ranges and different pore filling rates, and then curing, wherein the process is as follows:

firstly, coating a solvent on the surface of an oxidation protection carbon fiber reinforced framework, forming a continuous liquid film on the surface layer, continuously coating D slurry on the surface of the liquid film, drying the liquid film, heating and curing, repeating the coating and curing process for 1-2 times until the depth of the D slurry on the oxidation protection surface layer of the carbon fiber reinforced framework is H ₁；

And then according to the method for coating and curing the D sizing agent, sequentially coating and penetrating the Z sizing agent and the G sizing agent to the depth H of the surface layer of the carbon fiber reinforced framework material ₂And H ₃Within the range, after being dried and heated and cured, the three ceramic materials with different thermal expansion coefficients are prepared and respectively arranged at different depths H in sequence ₁、H ₂And H ₃Completing pore coating and filling of the ultrahigh-temperature light thermal protection material within the range;

(3) and (3) carrying out high-temperature sintering treatment on the ultrahigh-temperature light thermal protection material which is prepared in the step (2) and is coated and filled in the pores, so as to obtain the ultrahigh-temperature light thermal protection material with the integrated large-gradient transition layer.

Specifically, in the embodiment of the present invention, the material of the ultra-high temperature protective layer is one or a combination of two or more of silicon carbide, hafnium carbide, zirconium carbide, titanium carbide, molybdenum silicide, zirconium boride and hafnium boride.

The following are several specific embodiments of the invention: