A thermal control-wave absorbing integrated composite material, a preparation method thereof, and a spacecraft

Abstract

The present application provides a thermal control-wave absorbing integrated composite material, a preparation method thereof, and a spacecraft, which relates to the field of aerospace materials technology. The thermal control-wave absorbing integrated composite material comprises a composite ceramic core and a porous coating layer; the porous coating layer covers the composite ceramic core; the chemical formula of the composite ceramic core is La 1‑x Sr x MnO3 / Al2O3, 0.1≤x≤0.3; the porous coating layer includes Al2O3. By introducing Al2O3 into the composite ceramic core, the thermal radiation phase transition temperature can be controlled. The Al2O3 coating layer acts as a shell component to ensure the strength of the thermal control and wave absorbing integrated composite material. The porous structure of the porous coating layer allows radar waves to be absorbed through multiple reflections within the pores, effectively increasing the thermal control and wave absorbing integrated composite material's radar absorption.

Description

Technical Field

[0001] The present application relates to the field of aerospace material technology, and in particular to a thermal control-wave absorbing integrated composite material, a preparation method thereof, and a spacecraft. Background Art

[0002] With the rapid development of aerospace technology, spacecraft have put forward higher precision requirements on the thermal radiation performance of thermal control materials.

[0003] La 1-x Sr x Lanthanum strontium manganate (MnO3) compounds, as excellent thermal control materials, have a thermal radiation phase transition temperature near room temperature, limiting their application in the relatively low-temperature space environment. Furthermore, in an environment with increasingly severe electromagnetic pollution, spacecraft also need radar stealth. This requires coating their surfaces with absorbing materials to shield electromagnetic signals from detectors and ensure safe in-orbit flight.

[0004] Therefore, there is an urgent need to optimize existing thermal control materials so that they have both wave-absorbing properties, improve the survivability of spacecraft, and achieve multifunctional and lightweight spacecraft. Summary of the Invention

[0005] The purpose of this application is to provide a thermal control-wave absorbing integrated composite material, a preparation method thereof, and a spacecraft to solve the above-mentioned problems.

[0006] To achieve the above objectives, the present application provides, in a first aspect, a thermal control-wave absorbing integrated composite material, comprising a composite ceramic core and a porous cladding layer;

[0007] The porous coating layer covers the composite ceramic core;

[0008] The chemical formula of the composite ceramic core is La 1-x Sr x MnO3 / Al2O3, 0.1≤x≤0.3;

[0009] The porous coating layer includes Al2O3.

[0010] Optionally, the thermal control-wave absorbing integrated composite material meets at least one of the following conditions:

[0011] A. The particle size of the composite ceramic core is 20 μm-250 μm;

[0012] B. The thickness of the porous coating layer is 0.5 μm-2 μm;

[0013] C. La 1-x Sr xThe mass of MnO3 accounts for 60%-90% of the total mass of the composite ceramic core.

[0014] Optionally, the thermal control-wave absorbing integrated composite material meets at least one of the following conditions:

[0015] A. The specific surface area of ​​the thermal control-wave absorbing integrated composite material is 15m 2 / g-45m 2 / g;

[0016] B. The phase transition temperature of the thermal control-wave absorbing integrated composite material is 5°C-10°C.

[0017] A second aspect of the present application provides a method for preparing the thermal control-wave absorbing integrated composite material, comprising:

[0018] La 1-x Sr x MnO3, part of Al2O3, and a ball milling solvent are first mixed to obtain a mixed slurry;

[0019] granulating the mixed slurry to obtain a mixed powder;

[0020] The mixed powder, the remaining Al2O3 and the binder are mixed for the second time to obtain a powder to be processed;

[0021] The powder to be processed is subjected to plasma spheroidization treatment to obtain the thermal control-wave absorbing integrated composite material.

[0022] Optionally, the method for preparing the thermal control-wave absorbing integrated composite material satisfies at least one of the following conditions:

[0023] A. The ball milling solvent includes water and / or ethanol;

[0024] B. The binder includes one or more of polyvinyl alcohol, polyacrylic acid, and polyvinyl ketone.

[0025] Optionally, the method for preparing the thermal control-wave absorbing integrated composite material satisfies at least one of the following conditions:

[0026] A. The La 1-x Sr x The mass ratio of MnO3, the part of Al2O3, and the ball milling solvent is (3-4): (1-2): 15;

[0027] B. The mass ratio of the mixed powder, the remaining Al2O3, and the binder is (7.5-9): (1-2.5): 1.

[0028] Optionally, the method for preparing the thermal control-wave absorbing integrated composite material satisfies at least one of the following conditions:

[0029] A. the granulation comprises spray granulation;

[0030] B. The stirring rate of the second mixing is 800 rpm-1000 rpm, and the time is 3 h-4 h.

[0031] Optionally, the nozzle speed of the spray granulation is 20Hz-30Hz, and the peristaltic pump speed is 30rpm.

[0032] Optionally, the powder feeding rate of the plasma spheroidization treatment is 50 g / min-100 g / min, the carrier gas flow rate is 1 L / min-3 L / min, and the spheroidization power is 30 kW-50 kW.

[0033] A third aspect of the present application provides a spacecraft, comprising the thermal control-wave absorbing integrated composite material or the thermal control-wave absorbing integrated composite material prepared by the preparation method of the thermal control-wave absorbing integrated composite material.

[0034] Compared with the prior art, the advantages of this application include:

[0035] The thermal control-wave absorbing integrated composite material provided by the present application has a porous core-shell structure. 1-x Sr x The composite ceramic core of MnO3 can regulate the thermal radiation phase transition temperature of the composite ceramic core, so that the radiation phase transition temperature point occurs at a lower temperature rather than room temperature, and at the same time realize the low density and light weight of the thermal control-wave absorbing integrated composite material; In addition, Al2O3 as a coating layer has a lower melting point than La 1-x Sr x The high MnO3 content can serve as a shell component to ensure the strength of the thermal control-wave absorbing integrated composite material; the porous structure of the porous coating layer can enable radar waves to be absorbed after multiple reflections in the pores, effectively increasing the absorption of radar waves by the thermal control-wave absorbing integrated composite material; the porous core-shell structure can ensure the stability and dispersibility of the core binary composite material, so that it will not be partially enriched after plasma spheroidization, and the two-phase composite will be more uniform, thereby optimizing the thermal radiation phase change temperature range. At the same time, the core and shell layer materials both have radar absorbing properties, forming a gradient impedance, and improving the electromagnetic wave absorption effect of the material.

[0036] The thermal control-wave absorbing integrated composite material and its preparation method provided by the present application are prepared by 1-x Sr xMnO3, Al2O3, and a ball milling solvent are mixed and mechanically mixed by ball milling to form a slurry; the slurry is spray granulated to obtain a core powder; the powder is again ball milled with a binder and Al2O3 so that the Al2O3 layer is evenly coated on the outer shell of the core spherical powder to obtain a core-shell structure powder; finally, the core-shell structure powder is plasma spheroidized to obtain a thermal control-wave absorbing integrated composite material with a porous core-shell structure. The preparation method has readily available raw materials, a simple process, and is easy to operate, and is conducive to large-scale industrial production.

[0037] The spacecraft provided in this application has both thermal control and wave absorption capabilities, can serve stably in a lower temperature environment, and can shield the electromagnetic wave signals of the detector to ensure safe flight in orbit. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope of the present application.

[0039] Figure 1 SEM image of the thermal control-wave absorbing integrated composite material provided for implementation 1. DETAILED DESCRIPTION

[0040] As used herein:

[0041] "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variations thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0042] The conjunction "consisting of" excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed, excluding materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim, rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0043] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed alone. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including the range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0044] In these examples, parts and percentages are by mass unless otherwise indicated.

[0045] "Parts by mass" refers to the basic unit of measurement used to express the mass ratio of multiple components. One part can represent any unit of mass, such as 1g or 2.689g. If we say that the mass of component A is a parts and the mass of component B is b parts, this means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, we could say that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number representing a multiplication factor). It's important to note that, unlike parts by mass, the sum of the mass of all components is not limited to 100 parts.

[0046] "And / or" is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0047] In a first aspect, the present application provides a thermal control-wave absorbing integrated composite material, comprising a composite ceramic core and a porous cladding layer;

[0048] The porous coating layer covers the composite ceramic core;

[0049] The chemical formula of the composite ceramic core is La 1-x Sr x MnO3 / Al2O3, 0.1≤x≤0.3;

[0050] Optionally, x can be 0.1, 0.15, 0.2, 0.25, 0.3, or any value between 0.1 and 0.3.

[0051] It should be noted that La 1-x Sr x MnO3(LSMO) is a dielectric absorber with excellent electrical properties. 3+The strong electron-phonon interaction caused by the Jahn-Teller splitting and the related distortion in the MnO6 octahedron enhance the electronic conductivity and dielectric relaxation of the material, which is often used to adjust the dielectric loss of the composite material to achieve better electromagnetic matching. 1-x Sr x The phase transition temperature of MnO3 is close to room temperature, so its application at lower temperatures is limited. After the introduction of Al2O3, Al2O3 insulators can be 1-x Sr x The spin-polarized tunneling effect between MnO3 enhances magnetoresistance, causing the strong magnetoresistance effect to occur at a lower temperature rather than room temperature. According to the Rubenhagens equation, the emissivity of the material is positively correlated with its resistivity. When the strong magnetoresistance effect occurs, the resistivity of the material will change significantly, and the emissivity will also change significantly. The point with the largest emissivity change rate is the radiation phase transition temperature point, so the radiation phase transition temperature point of the composite ceramic core also moves to a lower temperature.

[0052] The porous coating layer includes Al2O3.

[0053] It should be noted that the porous coating layer is Al2O3, which is consistent with one of the raw materials of the core component. This is to achieve a smooth impedance transition between the coating layer and the core layer and improve the electromagnetic wave absorption effect of the absorbing material.

[0054] In some embodiments, the thermal control-wave absorbing integrated composite material satisfies at least one of the following conditions:

[0055] A. The particle size of the composite ceramic core is 20 μm-250 μm;

[0056] Optionally, the particle size of the composite ceramic core may be 20 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, or any value between 20 μm and 250 μm;

[0057] It should be noted that when the particle size of the composite ceramic core is 20 μm-250 μm, this particle size range is conducive to the subsequent preparation of the powder into a coating by spraying or brushing.

[0058] B. The thickness of the porous coating layer is 0.5 μm-2 μm;

[0059] Optionally, the thickness of the porous coating layer may be 0.5 μm, 1 μm, 1.5 μm, 2 μm, or any value between 0.5 μm and 2 μm;

[0060] It should be noted that when the thickness of the porous coating layer is 0.5μm-2μm, the thickness of the coating layer is conducive to ensuring the formation of a porous core-shell structure and enhancing the absorption effect of electromagnetic waves. If the thickness is too high, the overall thermal control performance of the material will be masked. If the thickness is too low, the material will be insufficient to form an impedance transition between the outer shell and the inner core, thereby weakening the absorption effect of radar waves.

[0061] C. La 1-x Sr x The mass of MnO3 accounts for 60%-90% of the total mass of the composite ceramic core.

[0062] Optional, La 1-x Sr x The mass of MnO 3 may account for 60%, 70%, 80%, 90% or any value between 60% and 90% of the total mass of the composite ceramic core.

[0063] In some embodiments, the thermal control-wave absorbing integrated composite material satisfies at least one of the following conditions:

[0064] A. The specific surface area of ​​the thermal control-wave absorbing integrated composite material is 15m 2 / g-45m 2 / g;

[0065] Optionally, the specific surface area of ​​the thermal control-wave absorbing integrated composite material can be 15m 2 / g, 20m 2 / g, 25m 2 / g、30m 2 / g、35m 2 / g, 40m 2 / g、45m 2 / g or 15m 2 / g-45m 2 Any value between / g;

[0066] It should be noted that when the specific surface area of ​​the thermal control-wave absorbing integrated composite material is 15m 2 / g-45m 2 / g, the aperture of the surface holes is just within the wavelength range of electromagnetic waves, which is beneficial to increase the absorption effect of electromagnetic waves.

[0067] B. The phase transition temperature of the thermal control-wave absorbing integrated composite material is 5°C-10°C.

[0068] Optionally, the phase transition temperature of the thermal control-wave absorbing integrated composite material may be 5°C, 6°C, 7°C, 8°C, 9°C, 10°C or any value between 5°C and 10°C.

[0069] It should be noted that when the phase transition temperature of the thermal control-wave absorbing integrated composite material is 5°C-10°C, the material can be used in a lower temperature range.

[0070] A second aspect of the present application provides a method for preparing the thermal control-wave absorbing integrated composite material, comprising:

[0071] La 1-x Sr x MnO3, part of Al2O3, and a ball milling solvent are first mixed to obtain a mixed slurry;

[0072] granulating the mixed slurry to obtain a mixed powder;

[0073] The mixed powder, the remaining Al2O3 and the binder are mixed for the second time to obtain a powder to be processed;

[0074] The powder to be processed is subjected to plasma spheroidization treatment to obtain the thermal control-wave absorbing integrated composite material.

[0075] In some embodiments, the method for preparing the thermal control-wave absorbing integrated composite material satisfies at least one of the following conditions:

[0076] A. The ball milling solvent includes water and / or ethanol;

[0077] B. The binder includes one or more of polyvinyl alcohol, polyacrylic acid, and polyvinyl ketone.

[0078] In some embodiments, the method for preparing the thermal control-wave absorbing integrated composite material satisfies at least one of the following conditions:

[0079] A. The La 1-x Sr x The mass ratio of MnO3, the part of Al2O3, and the ball milling solvent is (3-4): (1-2): 15;

[0080] Optional, La 1-x Sr x The mass ratio of MnO3, part of Al2O3, and ball milling solvent can be any value between 3:1:15, 3.5:1:15, 4:1:15, 3:1.5:15, 3:2:15, 4:2:15, or (3-4):(1-2):15;

[0081] B. The mass ratio of the mixed powder, the remaining Al2O3, and the binder is (7.5-9): (1-2.5): 1.

[0082] Optionally, the mass ratio of the mixed powder, the remaining Al2O3 and the binder can be 7.5:1:1, 8:1:1, 8.5:1:1, 9:1:1, 7.5:2:1, 7.5:2.5:1, 9:2:1, 9:2.5:1 or any value between (7.5-9):(1-2.5):1.

[0083] In some embodiments, the method for preparing the thermal control-wave absorbing integrated composite material satisfies at least one of the following conditions:

[0084] A. the granulation comprises spray granulation;

[0085] B. The stirring rate of the second mixing is 800 rpm-1000 rpm, and the time is 3 h-4 h.

[0086] Optionally, the stirring rate of the second mixing can be 800 rpm, 850 rpm, 900 rpm, 950 rpm, 1000 rpm or any value between 800 rpm and 1000 rpm, and the time can be 3 h, 3.5 h, 4 h or any value between 3 h and 4 h.

[0087] It is important to note that the setting range of stirring rate and time helps to evenly coat the shell material around the core, improving the integrity of the coating. If the coating stirring time is too long or the stirring rate is too slow or too fast, the powder coating efficiency will decrease, and most powders will be in a state of two-phase mechanical mixing, failing to form a core-shell structure.

[0088] In some embodiments, the nozzle speed of the spray granulation is 20 Hz-30 Hz, and the peristaltic pump speed is 30 rpm-40 rpm.

[0089] Optionally, the nozzle speed of the spray granulation can be 20 Hz, 25 Hz, 30 Hz or any value between 20 Hz and 30 Hz, and the peristaltic pump speed can be 30 rpm, 35 rpm, 40 rpm or any value between 30 rpm and 40 rpm.

[0090] It should be noted that the composite ceramic core is prepared by regulating the nozzle speed of the spray granulation and the peristaltic pump speed, and the particle size of the composite ceramic core can be controlled within the range of 20μm-250μm.

[0091] Optionally, the powder feeding rate of the plasma spheroidization treatment is 50 g / min-100 g / min, the carrier gas flow rate is 1 L / min-3 L / min, and the spheroidization power is 30 kW-50 kW.

[0092] Optionally, the powder feeding rate of the plasma spheroidization treatment can be 50g / min, 60g / min, 70g / min, 80g / min, 90g / min, 100g / min or any value between 50g / min-100g / min, the carrier gas flow rate can be 1L / min, 2L / min, 3L / min or any value between 1L / min-3L / min, and the spheroidization power can be 30kW, 40KW, 50kW or any value between 30kW-50kW.

[0093] It should be noted that the parameters of the plasma spheroidization treatment must be controlled so that the powder does not completely melt and densify. Instead, the powder is allowed to pass through the high-temperature plasma quickly, the binder evaporates quickly, and the shell material melts and condenses to form a uniform porous structure.

[0094] A third aspect of the present application provides a spacecraft, comprising the thermal control-wave absorbing integrated composite material or the thermal control-wave absorbing integrated composite material prepared by the preparation method of the thermal control-wave absorbing integrated composite material.

[0095] It should be noted that the spacecraft includes but is not limited to one or more of artificial earth satellites and space probes.

[0096] The embodiments of the present application will be described in detail below in conjunction with specific examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present application and should not be considered as limiting the scope of the present application. In the examples, if specific conditions are not specified, the conditions are carried out according to conventional conditions or manufacturer recommendations. The reagents or instruments used are not specified by the manufacturer and are conventional products that can be purchased commercially.

[0097] Example 1

[0098] This embodiment provides a first aspect of a thermal control-wave absorbing integrated composite material, comprising a composite ceramic core and a porous coating layer, wherein the porous coating layer covers the composite ceramic core, and the chemical formula of the composite ceramic core is La 1-x Sr x MnO3 / Al2O3, x is 0.2; the porous coating layer is Al2O3;

[0099] The particle size of the composite ceramic core is 45 μm, the thickness of the porous coating layer is 1 μm, and the La 1-x Sr x The mass of MnO3 accounts for 80% of the total mass of the composite ceramic core;

[0100] The specific surface area of ​​the thermal control-wave absorbing integrated composite material is 41m 2 / g, and the phase transition temperature is 5℃-10℃.

[0101] A second aspect of this embodiment provides a method for preparing a thermal control-wave absorbing integrated composite material, which specifically includes the following steps:

[0102] S1: La is added in a mass ratio of 4:1:15 1-x Sr x MnO3, Al2O3 and ball milling solvent are mechanically mixed by ball milling to prepare a mixed slurry;

[0103] S2: spray granulating the mixed slurry to obtain a mixed powder. The nozzle speed of the spray granulation is 25 Hz and the peristaltic pump speed is 35 rpm.

[0104] S3: The mixed powder, Al2O3, and binder were ball-milled again in a mass ratio of 9:1:1 at a stirring rate of 1000 rpm for 3 h to obtain a powder to be processed;

[0105] S4: The powder to be treated is subjected to plasma treatment at a powder feeding rate of 50 g / min, a carrier gas flow rate of 2 L / min, and a spheroidizing power of 30 kW to obtain a thermal control-wave absorbing integrated composite material;

[0106] The ball milling solvent is water; the binder is polyvinyl alcohol.

[0107] The SEM images of the thermal control-wave absorbing integrated composite material are as follows: Figure 1 shown.

[0108] Example 2

[0109] This embodiment provides a first aspect of a thermal control-wave absorbing integrated composite material, comprising a composite ceramic core and a porous coating layer, wherein the porous coating layer covers the composite ceramic core, and the chemical formula of the composite ceramic core is La 1-x Sr x MnO3 / Al2O3, x is 0.1; the porous coating layer is Al2O3;

[0110] The particle size of the composite ceramic core is 60 μm, the thickness of the porous coating layer is 1.2 μm, and the La 1-x Sr x The mass of MnO3 accounts for 85% of the total mass of the composite ceramic core;

[0111] The specific surface area of ​​the thermal control-wave absorbing integrated composite material is 36m 2 / g, and the phase transition temperature is 5℃-10℃.

[0112] A second aspect of this embodiment provides a method for preparing a thermal control-wave absorbing integrated composite material, which specifically includes the following steps:

[0113] S1: La is added in a mass ratio of 3:2:15 1-x Srx MnO3, Al2O3 and ball milling solvent are mechanically mixed by ball milling to prepare a mixed slurry;

[0114] S2: spray granulating the mixed slurry to obtain a mixed powder. The nozzle speed of the spray granulation is 25 Hz and the peristaltic pump speed is 35 rpm.

[0115] S3: The mixed powder, Al2O3, and binder were ball-milled again in a mass ratio of 8:2:1 at a stirring rate of 900 rpm for 3.5 h to obtain a powder to be processed;

[0116] S4: The powder to be treated is subjected to plasma treatment at a powder feeding rate of 80 g / min, a carrier gas flow rate of 2.5 L / min, and a spheroidizing power of 35 kW to obtain a thermal control-wave absorbing integrated composite material;

[0117] The ball milling solvent is water; the binder is polyvinyl alcohol.

[0118] Example 3

[0119] This embodiment provides a first aspect of a thermal control-wave absorbing integrated composite material, comprising a composite ceramic core and a porous coating layer, wherein the porous coating layer covers the composite ceramic core, and the chemical formula of the composite ceramic core is La 1-x Sr x MnO3 / Al2O3, x is 0.15; the porous coating layer is Al2O3;

[0120] The particle size of the composite ceramic core is 60 μm, the thickness of the porous coating layer is 1.5 μm, and the La 1-x Sr x The mass of MnO3 accounts for 88% of the total mass of the composite ceramic core.

[0121] The specific surface area of ​​the thermal control-wave absorbing integrated composite material is 30m 2 / g, and the phase transition temperature is 5℃-10℃.

[0122] A second aspect of this embodiment provides a method for preparing a thermal control-wave absorbing integrated composite material, which specifically includes the following steps:

[0123] S1: La is added in a mass ratio of 3.5:1.5:15 1-x Sr x MnO3, Al2O3 and ball milling solvent are mechanically mixed by ball milling to prepare a mixed slurry;

[0124] S2: The mixed slurry is spray granulated to obtain a mixed powder. The nozzle speed of the spray granulation is 28 Hz and the peristaltic pump speed is 35 rpm.

[0125] S3: The mixed powder, Al2O3, and binder were ball-milled again in a mass ratio of 8.5:1.5:1 at a stirring rate of 800 rpm for 4 h to obtain a powder to be processed;

[0126] S4: The powder to be treated is subjected to plasma treatment at a powder feeding rate of 60 g / min, a carrier gas flow rate of 3 L / min, and a spheroidizing power of 40 kW to obtain a thermal control-wave absorbing integrated composite material;

[0127] The ball milling solvent is ethanol and the binder is polyvinyl ketone.

[0128] Comparative Example 1

[0129] The difference from Example 1 is that no porous coating layer is provided, and only a composite ceramic core is provided.

[0130] Comparative Example 2

[0131] The difference from Example 1 is that the coating layer is not porous.

[0132] Comparative Example 3

[0133] The difference from Example 1 is that the core is only La 1-x Sr x MnO3, 0.1≤x≤0.3.

[0134] Comparative Example 4

[0135] The difference from Example 1 is that the thickness of the porous coating layer is 3 μm.

[0136] Comparative Example 5

[0137] The difference from Example 1 is that only La 1-x Sr x MnO3 material, no Al2O3 is set.

[0138] Comparative Example 6

[0139] The difference from Example 1 is that no plasma spheroidization treatment is performed, and high-temperature heat treatment is used to form pores.

[0140] The above examples and comparative examples were tested for specific surface area, thermal radiation phase transition temperature, and minimum reflectivity in radar wave absorption effect. The specific results are shown in Table 1.

[0141] The test method for specific surface area is: GB / T 13390-2008 Determination of specific surface area of ​​metal powders - Nitrogen adsorption method.

[0142] The test method for the phase change temperature of thermal radiation is: GJB 2502.3-2006 Test method for spacecraft thermal control coatings Part 3 Emissivity test.

[0143] The test method for the lowest reflectivity in radar wave absorption effect is: GJB 2038A-2011 Radar Absorbing Material Reflectivity Test Method.

[0144] Table 1 Test results

[0145]

[0146]

[0147] From the results in Table 1, it can be seen that when no porous structure or porous shell is provided in Comparative Examples 1 and 2, the specific surface area and the wave absorption effect of the material are significantly affected; when the core of Comparative Example 3 is only lanthanum strontium manganese material, the wave absorption performance is less affected, and the degree to which the phase transition temperature point moves toward low temperature is small; from Comparative Example 4, it can be seen that the shell thickness has a greater impact on the wave absorption performance; from Comparative Example 5, it can be seen that not providing alumina has a greater impact on the phase transition temperature; from Comparative Example 6, it can be seen that the long-term heating state of the high-temperature heat treatment causes the material to easily melt into a whole, making it difficult to form a uniform porous structure, which affects the material's absorption effect on electromagnetic waves.

[0148] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

[0149] Furthermore, those skilled in the art will appreciate that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and to form distinct embodiments. For example, in the claims above, any of the claimed embodiments may be used in any combination. The information disclosed in this background section is intended solely to enhance understanding of the overall background of this application and should not be construed as an admission or any implication that such information constitutes prior art known to those skilled in the art.

Claims

1. A method for preparing a thermal control-wave absorbing integrated composite material, characterized in that: The thermal control-wave absorbing integrated composite material comprises a composite ceramic core and a porous cladding layer; The porous coating layer covers the composite ceramic core; The chemical formula of the composite ceramic core is La 1-x Sr x MnO3 / Al2O3, 0.1≤x≤0.3; The porous coating layer comprises Al2O3; the thickness of the porous coating layer is 0.5 μm-2 μm; The phase transition temperature of the thermal control-wave absorbing integrated composite material is 5°C-10°C; The preparation method of the thermal control-wave absorbing integrated composite material comprises: 1-x Sr x MnO3, part of Al2O3, and a ball milling solvent are first mixed to obtain a mixed slurry; granulating the mixed slurry to obtain a mixed powder; The mixed powder, the remaining Al2O3 and the binder are mixed for the second time to obtain a powder to be processed; The powder to be processed is subjected to plasma spheroidization treatment to obtain the thermal control-wave absorbing integrated composite material; The binder includes one or more of polyacrylic acid and polyvinyl ketone; The mass ratio of the mixed powder, the remaining Al2O3, and the binder is (7.5-9): (1-2.5): 1; The powder feeding rate of the plasma spheroidization treatment is 50g / min-100g / min, the carrier gas flow rate is 1L / min-3L / min, and the spheroidization power is 30kW-50kW; The particle size of the composite ceramic core is 20 μm-250 μm; The La 1-x Sr x The mass of MnO3 accounts for 60%-90% of the total mass of the composite ceramic core; The specific surface area of ​​the thermal control-wave absorbing integrated composite material is 15m 2 / g-45m 2 / g; The La 1-x Sr x The mass ratio of MnO3, the part of Al2O3, and the ball milling solvent is (3-4): (1-2):

15.

2. The method for preparing the thermal control-wave absorbing integrated composite material according to claim 1, characterized in that: The ball milling solvent includes water and / or ethanol.

3. The method for preparing the thermal control-wave absorbing integrated composite material according to claim 1, characterized in that: At least one of the following conditions is met: A. the granulation comprises spray granulation; B. The stirring rate of the second mixing is 800 rpm-1000 rpm, and the time is 3 h-4 h.

4. The method for preparing the thermal control-wave absorbing integrated composite material according to claim 3, characterized in that: The nozzle speed of the spray granulation is 20Hz-30Hz, and the peristaltic pump speed is 30rpm-40rpm.

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