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 H1;
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 material2And H3Within 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 sequence1、H2And H3Completing 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 alternative embodiment, the low CTE high temperature described in step (1)The difference of thermal expansion coefficient between the ceramic powder and the high-temperature ceramic powder with the medium thermal expansion coefficient is 1.0 multiplied by 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 D90Less 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/cm3~0.80g/cm3The 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 range1-H2Filling 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 H2-H3The 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 H3Within the depth range, the pore filling rate is within the range of 60-100%; and said H1-H2Filling degree in depth range, H2-H3Filling degree and H in depth range3The 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 H2In the range of 1mm to 6mm, said H3In the range of 0.2mm to 3mm, and said H1>H2>H3。
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.
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 H1;
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 material2And H3Within 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 sequence1、H2And H3Completing 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 described in step (1)The body is characterized in that the thermal expansion coefficient is less than or equal to 5 multiplied by 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) is901/2 less than average pore of oxidation-proof carbon fiber reinforced skeleton and more than 100nm, preferably optimized ceramic powder particle size D90Less 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/cm3~0.80g/cm3The 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 solvent1Within 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 framework2Within 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 framework3Within 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, H1-H2The 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%; h2-H3The 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%; h3The 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 H1-H2Depth range, H2-H3Within depth and H3The 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 H1In the range of 3mm to 10mm, said H2In the range of 1mm to 6mm, said H3In the range of 0.2mm to 3mm, and said H1>H2>H3。
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 H1;
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 material2And H3Within 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 sequence1、H2And H3Completing 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:
example 1:
(1) in the particle size D90Boron carbide powder of 5 μm as a high temperature ceramic having a low thermal expansion coefficient (thermal expansion coefficient of 4.5X 10)-6K) in particle size D905 μm zirconium carbide powder as a high-temperature ceramic having a medium thermal expansion coefficient (thermal expansion coefficient of 6.73X 10)-6K) with D90The molybdenum silicide of 5 μm is a high-temperature ceramic with high thermal expansion coefficient (thermal expansion coefficient is 7.8 × 10)-6and/K), taking liquid-phase polycarbosilane (the silicon/carbon ratio is 1:1, the solid-phase residual rate after pyrolysis is 66% (mass)) as a liquid-phase carrier, taking toluene as a solvent, respectively preparing D slurry, Z slurry and G slurry according to the volume ratio of the high-temperature ceramic powder to the liquid-phase carrier being 1:0.8, and regulating the viscosity to be within the range of 30-60 s by using the solvent.
(2) At a density of 0.33g/cm3And the oxidation protection carbon fiber reinforced skeleton with the average pore diameter of 30 mu m and the interior of the oxidation protection carbon fiber reinforced skeleton is a silicon carbide oxidation protection layer and is used as an ultrahigh-temperature light thermal protection material. Firstly, toluene is adopted to coat the surface of an oxidation protection carbon fiber reinforced framework, and a continuous liquid film is formed on the surface layer. And then continuously coating the D slurry, and permeating the D slurry into the surface layer of the oxidation protection carbon fiber reinforced framework within the range of 5mm under the induction action of a capillary adsorption liquid phase. And after drying, heating and curing at 200 ℃ in an inert protection environment. The coating and curing process is repeated for 1 time, and the filling of the porosity degree of about 20 percent is realized. Then, by adopting the similar process, the Z slurry and the G slurry are coated and penetrated into the range of 3mm and 1.5mm of the depth of the surface layer of the material in sequence and are solidified, the filling degree is about 50% in the range of 1.5mm to 3mm, and the filling degree is about 80% in the range of 1.5 mm.
(3) And sintering the obtained ceramic filling material in a vacuum sintering furnace at 1500 ℃ and under the pressure of less than 10kPa for 2h to form a ceramic integrated large-gradient transition layer.
The transition layer prepared by the method has obvious characteristic of gradient change of components and structures, and the macroscopic thermal expansion coefficient of the surface layer of the transition layer is about 6 multiplied by 10 from that of the outer surface layer-6the/K gradient transitions to about 3.5X 10 of the inner skin-6and/K. Preparing ZrB on the surface of the transition layer2the/SiC ultrahigh-temperature protective layer has no shedding of the protective layer and no cracking of the material after being subjected to oxyacetylene flame examination at 2000 ℃. After the ultrahigh-temperature protective layer is prepared on the surface of the transition layer prepared by the traditional method, the sample is cracked and damaged under the same examination condition. Therefore, the technical method effectively realizes the preparation of the large-gradient transition layer and solves the problem that the ultrahigh-temperature light thermal protection material is easy to be damaged by thermal stress at high temperature after the high-density protection coating is formed on the surface of the ultrahigh-temperature light thermal protection material.
Example 2:
(1) in the particle size D90Silicon carbide powder of 2 μm as a high temperature ceramic having a low thermal expansion coefficient (thermal expansion coefficient of 3.8X 10)-6K) in particle size D90Hafnium boride powder of 5 μm as a high-temperature ceramic having a thermal expansion coefficient of 5.7X 10-6K) with D90Titanium carbide of 5 μm is a high-temperature ceramic with a high thermal expansion coefficient (thermal expansion coefficient of 7.74X 10)-6and/K), taking phenolic resin (copper mountain chemical plant) with the carbon residue rate of about 50% as a liquid phase carrier, taking ethanol as a solvent, respectively preparing D slurry, Z slurry and G slurry according to the volume ratio of the high-temperature ceramic powder to the liquid phase carrier of 1:0.5, and regulating the viscosity to be within the range of 20 s-50 s by using the solvent.
(2) At a density of 0.30g/cm3And the oxidation protection carbon fiber reinforced framework with the average pore diameter of 40 mu m and the silicon carbide/zirconium boride oxidation protection layer inside is used as the ultrahigh-temperature light thermal protection material. Firstly, ethanol is adopted to coat the surface of an oxidation protection carbon fiber reinforced framework, and a continuous liquid film is formed on the surface layer. And then continuously coating the D slurry, and permeating the D slurry into the surface layer of the oxidation protection carbon fiber reinforced framework within 6mm under the induction action of a capillary adsorption liquid phase. And after drying, heating and curing at 200 ℃ in an inert protection environment. The coating and curing process is repeated for 2 times to achieve the pore filling degreeFilling about 30%. Then, by adopting the similar process, the Z slurry and the G slurry are sequentially coated and penetrated into the range of the depth of 4mm and the range of 2mm of the surface layer of the material and are solidified, the filling degree is about 55% in the range of the depth of 2 mm-4 mm, and the filling degree is about 85% in the range of the depth of 2 mm.
(3) And sintering the obtained ceramic filling material in a vacuum sintering furnace at 1600 ℃ and under the pressure lower than 10kPa for 2h to form the ceramic integrated large-gradient transition layer.
The transition layer prepared by the method has obvious characteristic of gradient change of components and structures, and the macroscopic thermal expansion coefficient of the surface layer of the transition layer is about 5.6 multiplied by 10 from that of the outer surface layer-6the/K gradient transitions to about 3X 10 of the inner skin-6and/K. Preparing MoSi on the surface of the transition layer2/ZrB2And after the ultra-high temperature protective layer is subjected to oxyacetylene flame examination at 2200 ℃, the protective layer does not fall off, and the material does not crack. After the ultrahigh-temperature protective layer is prepared on the surface of the transition layer prepared by the traditional method, the sample is cracked and damaged under the same examination condition. Therefore, the technical method effectively realizes the preparation of the large-gradient transition layer and solves the problem that the ultrahigh-temperature light thermal protection material is easy to be damaged by thermal stress at high temperature after the high-density protection coating is formed on the surface of the ultrahigh-temperature light thermal protection material.
Example 3:
(1) in the particle size D905 μm silicon carbide powder as a low thermal expansion coefficient high temperature ceramic (thermal expansion coefficient of 3.8X 10)-6K) in particle size D90Hafnium carbide powder of 5 μm as a medium thermal expansion coefficient high temperature ceramic (thermal expansion coefficient of 6.7X 10)-6K) with D90Molybdenum silicide of 10 μm is a high-temperature ceramic with a high coefficient of thermal expansion (coefficient of thermal expansion of 7.8X 10)-6The preparation method comprises the following steps of (K) respectively preparing D slurry by taking phenolic resin (copper mountain chemical plant) with the carbon residue rate of about 50% as a liquid phase carrier and ethanol as a solvent according to the volume ratio of 1:0.5 of high-temperature ceramic powder to the liquid phase carrier, and regulating the viscosity to be within the range of 20-50 s by using the ethanol; toluene is used as a solvent, Z slurry and G slurry are respectively prepared according to the volume ratio of the high-temperature ceramic powder to the liquid-phase carrier of 1:0.8, and the viscosity is regulated and controlled within the range of 30 s-60 s by using the solvent.
(2) By densityIs 0.30g/cm3And the oxidation protection carbon fiber reinforced skeleton with the average pore diameter of 40 mu m and the silicon carbide protective layer inside is used as the ultrahigh-temperature light thermal protection material. Firstly, ethanol is adopted to coat the surface of an oxidation protection carbon fiber reinforced framework, and a continuous liquid film is formed on the surface layer. And then continuously coating the D slurry, and permeating the D slurry into the surface layer of the oxidation protection carbon fiber reinforced framework within 6mm under the induction action of a capillary adsorption liquid phase. And after drying, heating and curing at 200 ℃ in an inert protection environment. The coating and curing process is repeated for 2 times, and the filling of the porosity of about 30 percent is realized. Then, by adopting the similar process, toluene is used as a solvent, and the Z slurry and the G slurry are sequentially coated and penetrated into the range of 3mm and 1mm of the depth of the surface layer of the material and are solidified, wherein the filling degree is about 50% in the range of 1mm to 3mm of the depth, and the filling degree is about 80% in the range of 1mm of the depth.
(3) And sintering the obtained ceramic filling material in a vacuum sintering furnace at 1650 ℃ and under the pressure of less than 10kPa for 2h to form the ceramic integrated large-gradient transition layer.
The transition layer prepared by the method has obvious characteristic of gradient change of components and structures, and the macroscopic thermal expansion coefficient of the surface layer of the transition layer is about 6.1 multiplied by 10 from that of the outer surface layer-6the/K gradient transitions to about 3.2X 10 of the inner skin-6and/K. Preparing MoSi on the surface of the transition layer2/ZrB2And after the ultrahigh-temperature protective layer is subjected to 2000 ℃ oxyacetylene flame examination, the protective layer does not fall off, and the material does not crack. After the ultrahigh-temperature protective layer is prepared on the surface of the transition layer prepared by the traditional method, the sample is cracked and damaged under the same examination condition. Therefore, the technical method effectively realizes the preparation of the large-gradient transition layer and solves the problem that the ultrahigh-temperature light thermal protection material is easy to be damaged by thermal stress at high temperature after the high-density protection coating is formed on the surface of the ultrahigh-temperature light thermal protection material.
The above description is only for the best mode of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.
Those skilled in the art will appreciate that the invention may be practiced without these specific details.