Perovskite ceramic material and preparation method and application thereof

Abstract

This application relates to the fields of infrared stealth technology and perovskite ceramic materials, and particularly to a perovskite ceramic material, its preparation method, and its application. The perovskite ceramic material has a cubic phase perovskite structure, and its molecular formula is La. 1‑x Ca x BaCoO 3‑δ Where 0 < x ≤ 0.15, and δ is the non-stoichiometric value of oxygen. The perovskite ceramic material provided in this application has both low infrared emissivity and low electromagnetic loss, achieving radar absorption compatibility.

Description

Technical Field

[0001] This application relates to the fields of infrared stealth technology and perovskite ceramic materials, and in particular to a perovskite ceramic material, its preparation method, and its application. Background Technology

[0002] The core of infrared stealth technology lies in the application of coatings with low infrared emissivity to reduce the detectability of targets in the infrared band. For a long time, coatings with low infrared emissivity have generally used metal-based fillers as functional fillers. These materials, with their extremely high conductivity and free electron gas, can strongly reflect infrared radiation and achieve extremely low emissivity (usually below 0.1).

[0003] However, the inherent technical defects of metal-based fillers further restrict their application in next-generation stealth coatings, such as: (1) poor compatibility and weather resistance: metal-based fillers are chemically active and easily react with coating base materials (especially halogen- and sulfur-containing resins), leading to coating discoloration and chalking. Their active surfaces are also easily oxidized or corroded, causing a sharp increase in emissivity and insufficient durability; (2) high density and easy sedimentation: the density of metal-based fillers is much higher than that of organic resins, and sedimentation is very likely to occur during coating storage and construction, resulting in uneven coating composition and performance. Unstable and increased weight load on equipment; (3) “Total reflection” does not match the spectrum: Metal-based fillers also have extremely strong reflective characteristics in the radar wave (microwave) band, which leads to an increase in the radar cross section (RCS) of the coating, which seriously conflicts with the requirements of radar stealth and makes it difficult to achieve wide spectrum (infrared / radar) compatible stealth; (4) Color uniformity and poor adaptability: Metal-based fillers are usually silver-white or gray-white, which is difficult to adjust into camouflage colors that match complex environments (such as jungles, deserts, cities), limiting their application in multispectral camouflage.

[0004] Based on this, this application aims to develop a novel filler material that combines low infrared emissivity, excellent environmental stability, lightweight, and the ability to achieve wide-spectrum (infrared / radar) compatible stealth. Summary of the Invention

[0005] The purpose of this application is to provide a perovskite-type ceramic material, its preparation method, and its application.

[0006] According to a first aspect of this application, embodiments of this application provide a perovskite-type ceramic material, wherein the perovskite-type ceramic material has a cubic phase perovskite structure, and the molecular formula of the perovskite-type ceramic material is La. 1-x Ca x BaCoO 3-δWhere 0 < x ≤ 0.15, and δ is the non-stoichiometric value of oxygen. Specifically, x in the molecular formula of the perovskite ceramic material can be 0.001, 0.005, 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.045, 0.05, 0.055, 0.06, 0.065, 0.07, 0.075, 0.08, 0.085, 0.09, 0.095, 0.1, 0.11, 0.115, 0.12, 0.125, 0.13, 0.135, 0.14, 0.145, 0.15, or a range of any two of the above values. It is not limited to the listed values; other unlisted values ​​within this range also apply.

[0007] Based on the problems existing in the relevant prior art mentioned in the background section, this application provides a novel perovskite ceramic material, wherein the molecular formula of the perovskite ceramic material is La. 1-x Ca x BaCoO 3-δ Where 0 < x ≤ 0.15. See also Figure 1 The SEM image of the perovskite ceramic material shown in this application indicates that the perovskite ceramic material provided in this application is composed of a large number of relatively uniform spherical microspheres (approximately 2-4 μm in diameter). These microspheres constitute the main framework of the material, with a relatively regular polyhedral cross-section. Each microsphere is not a dense solid but consists of countless smaller primary nanoparticles with sizes ranging from tens to hundreds of nanometers. These nanoparticles are well-fused but retain a large number of smaller gaps and pores. The regular blocky and granular structure shown in the SEM image gives the surface of the ceramic material a complex microstructure. When infrared radiation irradiates the surface of the material, it will undergo multiple scattering at these regular structures, preventing the infrared radiation from escaping smoothly from the material surface, thereby reducing the infrared emissivity of the ceramic material. Simultaneously, the image shows that the material has a large number of grain boundaries. The irregular atomic arrangement at the grain boundaries will absorb and scatter infrared radiation, further reducing the infrared energy that can be emitted in the form of thermal radiation, thus further reducing the infrared emissivity. Furthermore, the ceramic material La provided in this application... 1-x Ca x BaCoO 3-δ It has a cubic perovskite structure, with Ca and Ba doping forming Co. 3+ / Co 4+By mixing valence states and introducing an appropriate amount of oxygen vacancies, the conductivity of the material can be tuned to the semiconductor range, effectively suppressing conductivity loss and eddy current loss, resulting in low overall electromagnetic loss. Combined with the weak magnetic properties of the system, the material exhibits good impedance matching with radar waves, achieving excellent radar absorption performance. In other words, the perovskite ceramic material provided in this application has both low infrared emissivity and low electromagnetic loss, achieving radar absorption compatibility.

[0008] In some embodiments of this application, the molecular formula of the perovskite ceramic material is La. 1-x Ca x BaCoO 3-δ Where 0 < x < 0.075, and δ is the non-stoichiometric value of oxygen. Specifically, x in the molecular formula of the perovskite ceramic material can be 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.045, 0.05, 0.055, 0.06, 0.065, 0.07, 0.075, or a range of any two of the above values. It is not limited to the listed values; other unlisted values ​​within this range also apply.

[0009] In some embodiments of this application, the raw material source of La in the perovskite ceramic material is La(NO3)3·6H2O; the raw material source of Ca is Ca(NO3)2·4H2O; the raw material source of Ba is Ba(NO3); and the raw material source of Co is Co(NO3)2·6H2O.

[0010] According to a second aspect of this application, embodiments of this application also provide a method for preparing a perovskite-type ceramic material, the preparation method comprising: S1. Weigh the corresponding raw materials according to the molar ratio of each element in the molecular formula of the perovskite ceramic material, and fully dissolve each raw material. S2. Based on the dissolved raw materials, the perovskite-type ceramic material is prepared by the sol-gel method.

[0011] In a further embodiment of this application, a method for preparing perovskite ceramic materials is provided. The perovskite ceramic materials are prepared via a sol-gel method. Essentially, the sol-gel method involves constructing a highly homogeneous molecular-level mixed precursor through a chemical reaction in solution, followed by heat treatment to transform it into the target crystalline phase. By mixing all raw materials in solution at the ionic or molecular scale, component segregation caused by differences in particle size and density in solid-state methods can be further improved. This ensures accurate stoichiometry and the absence of impurities in the product, and is more conducive to the synthesis of complex perovskites containing four or more cations, such as LaCaBaCoO. The method provided in this application further improves the quality of the prepared perovskite ceramic materials, thereby further improving their related properties.

[0012] In some embodiments of this application, the preparation of the perovskite-type ceramic material using the sol-gel method based on the dissolved raw materials includes: S21. Add chelating agent and crosslinking agent sequentially to the dissolved raw material system, stir thoroughly to obtain a crosslinked mixture, and adjust the pH value of the mixture to 7.5-8.0; S22. After heating and stirring the pH-adjusted mixture in a water bath, stop stirring, let it stand for 8-15 hours, and then dry it to obtain a dry gel. S23. The dry gel is calcined to obtain a pre-calcined precursor; the pre-calcined precursor is ground and sieved to obtain precursor powder. S24. After mixing and pressing the precursor powder with the organic binder, the adhesive is removed. S25. After sintering the debinding precursor, the perovskite ceramic material is obtained. The molecular formula of the perovskite ceramic material is La. 1-x Ca x BaCoO 3-δ Where 0 < x ≤ 0.15, and δ is the non-stoichiometric value of oxygen.

[0013] Specifically, in step S21, the pH value of the mixture can be 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, or a range consisting of any two of the above values. It is not limited to the listed values; other unlisted values ​​within this range are also applicable. In step S22, the settling time can be 8h, 9h, 10h, 11h, 12, 13h, 14h, 15h, or a range consisting of any two of the above values. Specifically, x in the molecular formula of the perovskite ceramic material can be 0.001, 0.005, 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.045, 0.05, 0.055, 0.06, 0.065, 0.07, 0.075, 0.08, 0.085, 0.09, 0.095, 0.1, 0.11, 0.115, 0.12, 0.125, 0.13, 0.135, 0.14, 0.145, 0.15, or a range of any two of the above values. It is not limited to the listed values; other unlisted values ​​within this range also apply.

[0014] In some embodiments of this application, the molecular formula of the perovskite ceramic material is La. 1-x Ca x BaCoO 3-δ Where 0 < x < 0.075, and δ is the non-stoichiometric value of oxygen. Specifically, x in the molecular formula of the perovskite ceramic material can be 0.001, 0.005, 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.045, 0.05, 0.055, 0.06, 0.065, 0.07, 0.075, or a range of any two of the above values. It is not limited to the listed values; other unlisted values ​​within this range also apply.

[0015] In some embodiments of this application, the step of fully dissolving each preparation material includes: mixing the weighed preparation materials, adding deionized water, and stirring at a constant temperature until each preparation material is completely dissolved.

[0016] In some embodiments of this application, the raw materials for preparation include La(NO3)3·6H2O, Ba(NO3) and Co(NO3)2·6H2O; or, the raw materials for preparation include La(NO3)3·6H2O, Ba(NO3), Co(NO3)2·6H2O and Ca(NO3)2·4H2O.

[0017] In some embodiments of this application, the ratio of each preparation raw material to deionized water, expressed in g / mL, is 2-3:4. Specifically, the ratio of each preparation raw material to deionized water, expressed in g / mL, can be 2:4, 2.1:4, 2.2:4, 2.3:4, 2.4:4, 2.5:4, 2.6:4, 2.7:4, 2.8:4, 2.9:4, 3:4, or a range consisting of any two of the above values. The ratio is not limited to the listed values; other unlisted values ​​within this range also apply.

[0018] In some embodiments of this application, the temperature of the isothermal stirring is 50-70°C. Specifically, the temperature of the isothermal stirring can be 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C, 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, or a range of any two of the above values. The application is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0019] In some embodiments of this application, step S21, in which a chelating agent and a crosslinking agent are added sequentially to the dissolved raw material system and stirred thoroughly to obtain a crosslinked mixture, includes: adding a chelating agent sequentially to the dissolved raw material system, heating and stirring for 10-50 minutes, then further adding a crosslinking agent, stirring thoroughly for 10-50 minutes to obtain a crosslinked mixture.

[0020] Specifically, the heating and stirring time after adding the chelating agent can be 10 min, 11 min, 13 min, 15 min, 17 min, 19 min, 20 min, 21 min, 23 min, 25 min, 27 min, 29 min, 30 min, 31 min, 33 min, 35 min, 37 min, 39 min, 40 min, 41 min, 41 min, 43 min, 45 min, 47 min, 49 min, 50 min, or a range of any two of the above values. It is not limited to the listed values; other unlisted values ​​within this range are also applicable. Specifically, the stirring time after adding the crosslinking agent can be 10 min, 11 min, 13 min, 15 min, 17 min, 19 min, 20 min, 21 min, 23 min, 25 min, 27 min, 29 min, 30 min, 31 min, 33 min, 35 min, 37 min, 39 min, 40 min, 41 min, 41 min, 43 min, 45 min, 47 min, 49 min, 50 min, or a range of any two of the above values. It is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0021] In some embodiments of this application, the chelating agent includes at least one of citric acid, ethylenediaminetetraacetic acid, and tartaric acid.

[0022] In some embodiments of this application, the crosslinking agent includes at least one of ethylene glycol, polyethylene glycol, ethylene glycol methyl ether, and glycerol.

[0023] In some embodiments of this application, the weight ratio of the chelating agent to the sum of the raw materials is 1-2:2~3. Specifically, the weight ratio of the chelating agent to the sum of the raw materials can be 1:2, 1.1:2, 1.2:2, 1.3:2, 1.4:2, 1.5:2, 1.6:2, 1.7:2, 1.8:2, 1.9:2, 2:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9, 1:3, 1.5:3, etc. The range can be 1.5:2.1, 1.5:2.2, 1.5:2.3, 1.5:2.4, 1.5:2.5, 1.5:2.6, 1.5:2.7, 1.5:2.8, 1.5:2.9, 1.5:3, 2:2.1, 2:2.2, 2:2.3, 2:2.4, 2:2.5, 2:2.6, 2:2.7, 2:2.8, 2:2.9, 2:3, or any two of the above values. This range is not limited to the listed values; other unlisted values ​​within this range also apply.

[0024] In some embodiments of this application, the ratio of the sum of the preparation raw materials to the crosslinking agent, expressed in g / mL, is 1-2:2. Specifically, the ratio of the sum of the preparation raw materials to the crosslinking agent can be 1:2, 1.1:2, 1.2:2, 1.3:2, 1.4:2, 1.5:2, 1.6:2, 1.7:2, 1.8:2, 1.9:2, 2:2, or a range consisting of any two of the above values. The ratio is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0025] In some embodiments of this application, the reagent used to adjust the pH of the mixture is ammonia.

[0026] In some embodiments of this application, the conditions for water bath heating and stirring in step S22 include: the water bath heating and stirring temperature is 70~100℃, and the water bath heating and stirring time is 4-5h.

[0027] Specifically, the water bath heating and stirring temperature can be 70℃, 71℃, 72℃, 73℃, 74℃, 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, 90℃, 92℃, 94℃, 95℃, 96℃, 98℃, 100℃, or a range of any two of the above values. It is not limited to the listed values; other unlisted values ​​within this range are also applicable. Specifically, the water bath heating and stirring time can be 4h, 4.1h, 4.2h, 4.3h, 4.4h, 4.5h, 4.6h, 4.7h, 4.8h, 4.9h, 5h, or a range of any two of the above values. It is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0028] In some embodiments of this application, the drying conditions include: a drying temperature of 70-100℃ and a drying time of 5-20 hours. Specifically, the drying temperature can be 70℃, 71℃, 72℃, 73℃, 74℃, 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, 90℃, 92℃, 94℃, 95℃, 96℃, 98℃, 100℃, or a range consisting of any two of the above values. The drying is not limited to the listed values; other unlisted values ​​within this range are also applicable. The drying time can be 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, or a range consisting of any two of the above values. This applies not only to the listed values, but also to other unlisted values ​​within the range.

[0029] In some embodiments of this application, step S23, the heating procedure for calcining the dry gel, includes: raising the calcination temperature from room temperature to 500-700°C and holding it at that temperature for 5-15 hours; wherein the heating rate is 1-5°C / min. Specifically, in the heating procedure for calcining the dry gel, the temperature after heating can be 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C, 600°C, 610°C, 620°C, 630°C, 640°C, 650°C, 660°C, 670°C, 680°C, 690°C, 700°C, or a range consisting of any two of the above values. It is not limited to the listed values; other unlisted values ​​within this range are also applicable. The heat preservation time can be 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, or any range of two of the above values. It is not limited to the listed values; other unlisted values ​​within this range also apply.

[0030] In some embodiments of this application, in step S23, the sieve mesh size or mesh number is 400-800 mesh. Specifically, the sieve mesh size or mesh number can be 400 mesh, 450 mesh, 500 mesh, 550 mesh, 600 mesh, 650 mesh, 700 mesh, 750 mesh, 800 mesh, or a range of any two of the above values. It is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0031] In some embodiments of this application, in step S24, the mixing mass ratio of the precursor powder to the organic binder is 100:3 to 5; preferably, the organic binder includes at least one of polyvinyl alcohol and polyethylene oxide. Specifically, the mixing mass ratio of the precursor powder to the organic binder can be 100:3, 100:4, 100:5, or a range consisting of any two of the above values. It is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0032] In some embodiments of this application, the method for preparing the organic adhesive includes: adding the raw materials corresponding to the organic adhesive to deionized water and heating and stirring in a water bath to obtain the organic adhesive.

[0033] In some embodiments of this application, the water bath heating and stirring temperature is 80~100℃, and the water bath heating and stirring time is 80~150min; preferably, the mass fraction of the organic adhesive is 3%~8%. Specifically, the water bath heating and stirring temperature can be 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, 90℃, 92℃, 94℃, 95℃, 96℃, 98℃, 100℃, or a range of any two of the above values. It is not limited to the listed values; other unlisted values ​​within this range are also applicable. The water bath heating and stirring time can be 80min, 85min, 90min, 95min, 100min, 110min, 115min, 120min, 125min, 130min, 135min, 140min, 145min, 150min, or a range of any two of the above values. The numerical values ​​are not limited to those listed; other unlisted values ​​within this range also apply. Specifically, the mass fraction of the organic adhesive can be 3%, 4%, 5%, 6%, 7%, 8%, or a range consisting of any two of the above values. The numerical values ​​are not limited to those listed; other unlisted values ​​within this range also apply.

[0034] In some embodiments of this application, the pressing is performed using a powder tablet press; wherein the pressing pressure is 20-25 MPa, and the holding time is 1-5 min. Specifically, the pressing pressure can be 20 MPa, 21 MPa, 22 MPa, 23 MPa, 24 MPa, 25 MPa, or any range of two of the above values. It is not limited to the listed values; other unlisted values ​​within this range are also applicable. The holding time can be 1 min, 2 min, 3 min, 4 min, 5 min, or any range of two of the above values.

[0035] In some embodiments of this application, the glue removal includes: raising the temperature to 400-600℃ and holding it at that temperature for 2-10 hours; wherein the heating rate is 1-5℃ / min. Specifically, during the glue removal process, the temperature after heating can be 400℃, 410℃, 420℃, 430℃, 440℃, 450℃, 460℃, 470℃, 480℃, 490℃, 500℃, 510℃, 520℃, 530℃, 540℃, 550℃, 560℃, 570℃, 580℃, 590℃, 600℃, or a range consisting of any two of the above values. It is not limited to the listed values; other unlisted values ​​within this range are also applicable. Specifically, the holding time can be 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, or a range consisting of any two of the above values. The range of values ​​not listed here is also applicable, not limited to the values ​​listed. Specifically, the heating rate can be 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, or a range of any two of the above values. The range of values ​​not listed here is also applicable, not limited to the values ​​listed.

[0036] In some embodiments of this application, step S25 includes the sintering temperature rise process: One heating cycle: The heating rate is 3~8℃ / min. After heating from room temperature to 400℃-600℃, hold the temperature for 1~5 hours. Secondary heating: After the first heating is completed, continue heating to 1100℃-1200℃ at a heating rate of 3~8℃ / min, and hold for 5-15 hours.

[0037] Specifically, in a single heating cycle, the heating rate can be 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, or a range of any two of the above values. This is not limited to the listed values; other unlisted values ​​within this range also apply. The resulting temperature can be 400℃, 410℃, 420℃, 430℃, 440℃, 450℃, 460℃, 470℃, 480℃, 490℃, 500℃, 510℃, 520℃, 530℃, 540℃, 550℃, 560℃, 570℃, 580℃, 590℃, 600℃, or a range of any two of the above values. This is not limited to the listed values; other unlisted values ​​within this range also apply. The holding time can be 1h, 2h, 3h, 4h, 5h, or a range of any two of the above values. This applies not only to the listed values, but also to other unlisted values ​​within the range.

[0038] Specifically, in the secondary heating process, the heating rate can be 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, or any combination of two of the above values. It is not limited to the listed values; other unlisted values ​​within this range also apply. The temperature after heating can be 1100℃, 1110℃, 1120℃, 1130℃, 1140℃, 1150℃, 1160℃, 1170℃, 1180℃, 1190℃, 2000℃, or any combination of two of the above values. It is not limited to the listed values; other unlisted values ​​within this range also apply. The holding time can be 5h, 6h, 7h, 8h, 9h, 10h, 119h, 12h, 13h, 14h, 15h, or any combination of two of the above values. It is not limited to the listed values; other unlisted values ​​within this range also apply.

[0039] According to a third aspect of this application, embodiments of this application also provide the application of perovskite ceramic materials as described in any one of the first aspects of this application and / or perovskite ceramic materials prepared by the preparation method as described in any one of the second aspects of this application in the field of infrared stealth materials and / or infrared radiation materials.

[0040] The perovskite ceramic material provided in this application possesses both low infrared emissivity and low electromagnetic loss, enabling radar absorption compatibility. This perovskite ceramic material can be applied in the fields of infrared stealth materials and / or infrared radiation materials. For example, it can be used as a coating material or deposited onto the surface of a workpiece using vapor deposition or plasma spraying. It possesses the advantages of inorganic low-emissivity materials, such as easy assembly, strong anti-diffusion properties, and strong substrate adaptability, while also exhibiting low infrared emissivity and higher corrosion resistance. Therefore, it can be well applied in the fields of infrared stealth materials and / or infrared radiation materials. For instance, this perovskite ceramic material can be used to prepare infrared stealth materials and / or infrared radiation materials.

[0041] This application has at least the following advantages compared to the prior art: The perovskite ceramic material provided in this application has both low infrared emissivity and low electromagnetic loss, enabling radar absorption compatibility. Attached Figure Description

[0042] Figure 1 The X-ray diffraction pattern of the perovskite ceramic material prepared in the embodiments of this application; Figure 2 SEM images of the perovskite ceramic materials prepared in the comparative example of this application; Figure 3 SEM images of perovskite ceramic materials prepared in the embodiments of this application. Figure 4 The infrared emissivity data of the perovskite ceramic materials prepared in the embodiments and comparative examples of this application are shown in the 8~14μm band. Figure 5 This is a graph showing the measured radar transmittance data of the perovskite ceramic material prepared in the embodiments of this application; Figure 6 This is an optical image of the perovskite ceramic material prepared according to the embodiments of this application. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0044] Example 1 This embodiment provides a method for preparing a perovskite-type ceramic material, including the following steps: Step 1: According to the molar ratio of each element in the perovskite ceramic material La:Ba:Co:Ca=0.95:1:1:0.05, weigh out 10.74g of La(NO3)3·6H2O, 26.91g of Ba(NO3), 7.69g of Co(NO3)2·6H2O, and 0.312g of Ca(NO3)2·4H2O respectively, add 40mL of deionized water, and stir at a constant temperature of 60℃ until completely dissolved; Step 2: Slowly add 15g of anhydrous citric acid, heat and stir for a period of time; add 2ml of ethylene glycol, and continue stirring to form a homogeneous mixture; slowly adjust the pH of the solution to 7.5 with ammonia. Step 3: Place the pH-adjusted solution in a constant temperature water bath, heat it open to 90°C and stir for 5 hours. When the viscosity of the solution increases significantly and "coating" occurs, stop stirring. Continue to let it stand in the water bath for 10 hours to form a gel. Dry the formed gel in a vacuum drying oven at 90°C for 12 hours to form a black dry gel. Step 4: Pour the black dry gel obtained in Step 3 into an alumina crucible and place it in a muffle furnace for calcination. The calcination temperature program is as follows: heat up to 600℃ at a heating rate of 2℃ / min, hold for 10h, cool with the furnace, grind, and sieve to obtain a uniform precursor powder. Step 5: Add 2 mL of polyvinyl alcohol (PVA) organic binder to the precursor powder, and then press it into discs using a powder tablet press at a pressure of 20 MPa; wherein, the PVA organic binder is obtained by adding 5 g of polyvinyl alcohol to 95 g of pure water, heating it in a water bath to 90 °C and stirring for 100 min. Step Six: Place the disc on the alumina ceramic plate for adhesive removal; the adhesive removal process is as follows: raise the temperature to 500℃ at a heating rate of 2℃ / min and hold for 5 hours. Step 7: Place the debinding discs into a muffle furnace for sintering. After sintering, cool the discs to room temperature with the furnace to obtain the corresponding perovskite ceramic material. The sintering procedure is as follows: heat the discs from room temperature to 400°C at a heating rate of 5°C / min and hold for 2 hours. Then heat the discs to 1100°C at a heating rate of 5°C / min and hold for 8 hours.

[0045] Example 2 This embodiment provides a method for preparing a perovskite ceramic material based on Embodiment 1. The only difference between this embodiment and Embodiment 1 is that the molar ratio of each element in the perovskite ceramic material is different. In this embodiment, the molar ratio of each element in the perovskite ceramic material is 0.9:1:1:0.1, and the rest is the same as in Embodiment 1.

[0046] Example 3 This embodiment provides a method for preparing a perovskite ceramic material based on Embodiment 1. The only difference between this embodiment and Embodiment 1 is that the molar ratio of each element in the perovskite ceramic material is different. In this embodiment, the molar ratio of each element in the perovskite ceramic material is 0.85:1:1:0.15, and the rest is the same as in Embodiment 1.

[0047] Example 4 This embodiment provides a method for preparing a perovskite ceramic material based on Embodiment 1. The only difference between this embodiment and Embodiment 1 is that the molar ratio of each element in the perovskite ceramic material is different. In this embodiment, the molar ratio of each element in the perovskite ceramic material is La:Ba:Co:Ca=0.925:1:1:0.075, and the rest are the same as in Embodiment 1.

[0048] Example 5 This embodiment provides a method for preparing a perovskite ceramic material based on Embodiment 1. The only difference between this embodiment and Embodiment 3 is that the molar ratio of each element in the perovskite ceramic material is different. In this embodiment, the molar ratio of each element in the perovskite ceramic material is La:Ba:Co:Ca=0.93:1:1:0.06, and the rest are the same as in Embodiment 1.

[0049] Example 6 This embodiment provides a method for preparing a perovskite ceramic material based on Embodiment 1. The only difference between this embodiment and Embodiment 3 is that the molar ratio of each element in the perovskite ceramic material is different. In this embodiment, the molar ratio of each element in the perovskite ceramic material is La:Ba:Co:Ca=0.96:1:1:0.03, and the rest is the same as in Embodiment 1.

[0050] Example 7 This embodiment provides a method for preparing perovskite ceramic materials based on Embodiment 1. The only difference between this embodiment and Embodiment 1 is that the specific preparation process is different, while the rest is the same as Embodiment 1. The specific preparation process is as follows: Step 1: According to the molar ratio of each element in the perovskite ceramic material La:Ba:Co:Ca=0.95:1:1:0.05, weigh out 10.74g of La(NO3)3·6H2O, 26.91g of Ba(NO3), 7.69g of Co(NO3)2·6H2O, and 0.312g of Ca(NO3)2·4H2O respectively, add 40mL of deionized water, and stir at a constant temperature of 60℃ until completely dissolved; Step 2: Add an appropriate amount of EDTA and 5g of polyvinyl alcohol as a coagulant, heat at a constant temperature of 90℃ for 2 hours to form a gel, and then raise the gel from room temperature to 200℃ at a heating rate of 2℃ / min to obtain a black object. Step 3: Preheat the black object at 500℃ for 5 hours with a heating rate of 4℃ / min, and then dry it to obtain the dried black object. Step 4: Add 1 ml of polyvinyl alcohol colloid to the dried black object, grind it into powder, and then press it into discs using a hydraulic press at a pressure of 9 MPa; wherein, the polyvinyl alcohol colloid is prepared by adding 5 g of polyvinyl alcohol to 95 g of pure water, heating it to 90°C in a water bath and stirring continuously, and then cooling it to room temperature. Step 5: Place the discs on the alumina ceramic plate and then put them into a tube furnace for sintering. The sintering temperature program is as follows: heat from room temperature to 700℃ at a rate of 4℃ / min, and sinter at 700℃ for 24 hours. Then, cool the furnace to room temperature to obtain the corresponding perovskite ceramic material.

[0051] Example 8 This embodiment provides a method for preparing perovskite ceramic materials based on Embodiment 1. The only difference between this embodiment and Embodiment 1 is that the specific preparation process is different, while the rest is the same as Embodiment 1. The specific preparation process is as follows: Step 1: According to the molar ratio of each element in the perovskite ceramic material La:Ba:Co:Ca=0.95:1:1:0.05, weigh out 10.74g of La(NO3)3·6H2O, 26.91g of Ba(NO3), 7.69g of Co(NO3)2·6H2O, and 0.312g of Ca(NO3)2·4H2O respectively, add 40mL of deionized water, and stir at 60℃ until completely dissolved to obtain a nitric acid aqueous solution; Step 2: Add 0.24 mol of citric acid to the nitric acid aqueous solution and stir thoroughly; Step 3: Add 0.72 mol of ethylene glycol to the solution system from Step 2 and stir thoroughly; Step 4: After stirring thoroughly for 0.5 hours, continue to add NH3·H2O to the solution to adjust the pH value to 7.5; Step 5: Heat the pH-adjusted solution system in a water bath for 1.5 hours; Step 6: Dry the solution system after water bath heating at 100°C until a dry gel is obtained. Grind the dry gel to obtain a black powder. Step 7: Calcine the ground black powder in a muffle furnace until sintering is complete, and obtain precursor powder; the calcination procedure is as follows: heating rate is 2℃ / min, calcination temperature is 500℃, and holding time is 5h. Step 8: Place the mold containing the precursor powder into the spark plasma sintering furnace for sintering. After sintering, the corresponding perovskite ceramic material is obtained. The sintering procedure is as follows: heating rate of 100℃ / min, holding temperature of 1300℃, and holding time of 5min.

[0052] Example 9 This embodiment provides a method for preparing perovskite ceramic materials based on Embodiment 1. The only difference between this embodiment and Embodiment 1 is that the specific preparation process is different, while the rest is the same as Embodiment 1. The specific preparation process is as follows: Step 1: According to the molar ratio of each element in the perovskite ceramic material La:Ba:Co:Ca=0.95:1:1:0.05, weigh out 10.74g of La(NO3)3·6H2O, 26.91g of Ba(NO3), 7.69g of Co(NO3)2·6H2O, and 0.312g of Ca(NO3)2·4H2O respectively, add 40mL of deionized water, and stir at a constant temperature of 60℃ until completely dissolved; Step 2: Gradually add appropriate amounts of EDTA and 5g of polyvinyl alcohol as coagulants to the dissolved nitric acid aqueous solution system, heat at 90℃ for 2 hours to obtain a gel-like substance, and further heat the gel-like substance from room temperature to 200℃ at a heating rate of 2℃ / min to obtain a black substance. Step 3: Pre-calcine the obtained black substance at 500℃ for 5 hours, with a heating rate of 4℃ / min, and then dry to obtain a black dry gel. Step 4: Pour the black dry gel obtained in Step 3 into an alumina crucible, place it in a muffle furnace for calcination, cool it with the furnace, grind it, and sieve it to obtain a uniform precursor powder; wherein, the calcination heating program is: heat up to 600℃ at a heating rate of 2℃ / min, and hold for 10h. Step 5: Add 2 mL of polyvinyl alcohol (PVA) organic binder to the obtained precursor powder, and then press it into discs using a powder tablet press at a pressure of 20 MPa; wherein, the PVA organic binder is obtained by adding 5 g of polyvinyl alcohol to 95 g of pure water, heating it in a water bath to 90 °C and stirring for 100 min. Step Six: Place the disc on the alumina ceramic plate for adhesive removal; the adhesive removal process is as follows: raise the temperature to 500℃ at a heating rate of 2℃ / min and hold for 5 hours. Step 7: Place the debinding discs into a muffle furnace for sintering. After sintering, cool the discs to room temperature with the furnace to obtain the corresponding perovskite ceramic material. The sintering procedure is as follows: heat the discs from room temperature to 400°C at a heating rate of 5°C / min and hold for 2 hours. Then heat the discs to 1100°C at a heating rate of 5°C / min and hold for 8 hours.

[0053] Example 10 This embodiment provides a method for preparing perovskite-type ceramic materials based on Embodiment 1. The only difference between this embodiment and Embodiment 1 is that the specific preparation process is different, while the rest is the same as Embodiment 3.

[0054] The specific preparation process is as follows: Step 5: Add 2 mL of polyvinyl alcohol (PVA) organic binder to the precursor powder, and then press it into a disc using a powder press at a pressure of 20 MPa; wherein, the PVA organic binder is obtained by adding 5 g of polyvinyl alcohol to 95 g of pure water, heating it to 90°C in a water bath and stirring for 100 min; and Step 6: Place the disc on an alumina ceramic plate for debinding; wherein, the debinding process is: raising the temperature to 500°C at a heating rate of 2°C / min and holding it at that temperature for 5 h;” is omitted. That is, the steps of mixing and pressing the precursor powder with the PVA organic binder and debinding are not performed. Instead, the uniform precursor powder obtained in Step 4 is directly subjected to the sintering step in Step 7.

[0055] Comparative Example 1 This comparative example provides a method for preparing a perovskite ceramic material based on Example 1. The only difference between this comparative example and Example 1 is that the molar ratio of each element in the perovskite ceramic material is different. In this comparative example, the molar ratio of each element in the perovskite ceramic material is La:Ba:Co:Ca=1:1:1:0, and the rest are the same as in Example 1.

[0056] Comparative Example 2 This comparative example provides a method for preparing a perovskite ceramic material based on Example 1. The only difference between this comparative example and Example 1 is that the molar ratio of each element in the perovskite ceramic material is different. In this comparative example, the molar ratio of each element in the perovskite ceramic material is La:Ba:Co:Ca=1:1:2:0, and the rest are the same as in Example 1.

[0057] Comparative Example 3 This comparative example provides a method for preparing a perovskite ceramic material based on Example 1. The only difference between this comparative example and Example 3 is that the molar ratio of each element in the perovskite ceramic material is different. In this comparative example, the molar ratio of each element in the perovskite ceramic material is La:Ba:Co:Ca=0.95:1:2:0.05, and the rest are the same as in Example 1.

[0058] Example of effect (1) Analysis of X-ray diffraction pattern results Figure 1 The X-ray diffraction patterns of the infrared fillers obtained in Examples 1-5 are shown. Comparing the test patterns with standard perovskite cards reveals that all major diffraction peak positions correspond perfectly. This indicates that the synthesized material is a pure-phase perovskite structure, with no obvious impurity phases (such as Co3O4, La2O3, etc.) detected. In terms of crystal structure, referring to the standard PDF card, this perovskite belongs to the cubic crystal system. The multiple clear and sharp diffraction peaks appearing in the patterns, such as (1 1 0), (2 0 0), (21 1), (2 2 0), are typical characteristics of cubic perovskite structures. Regarding crystal quality, the sharp and narrow diffraction peaks indicate that the material has good crystallinity. The crystal grains are relatively large, and the lattice integrity is high.

[0059] (2) SEM scanning analysis Figure 2 , Figure 3 The images show SEM images of the perovskite ceramic materials prepared in Comparative Example 1 and Example 1. By comparing the two scanning electron microscope (SEM) images, significant differences in microstructure, particle dispersion, surface structure, and crystallization characteristics between the two samples can be clearly observed: according to Figure 2The results shown indicate that Comparative Example 1 exhibits severe particle agglomeration, with numerous nano / submicron-sized grains randomly clustering to form irregular blocky agglomerates several micrometers in size. The boundaries between grains are blurred, making it almost impossible to distinguish individual grain outlines. The agglomerates contain numerous irregular pores and voids, exhibiting an overall loose, porous, sponge-like structure with an uneven surface containing many sharp protrusions and depressions, resulting in a significantly increased specific surface area. These morphological characteristics suggest that the sample exhibits extremely poor particle dispersibility, indicating that effective grain growth control was not achieved during preparation. This led to grain adhesion, incomplete sintering neck development, and the formation of a microstructure with high defect density. Further based on Figure 3 The results show that the microstructure of Example 1 exhibits distinctly different characteristics: significantly improved particle dispersion, no obvious large-sized agglomerates, clearly distinguishable grain outlines, mostly polygonal or near-spherical shapes, and significantly improved uniformity of size distribution. The grain interfaces are clear, with intact boundaries and no obvious adhesion; the surface is relatively dense and smooth, without numerous irregular pores and depressions, resulting in a more regular overall structure. This indicates that the sample has more complete grain growth, higher crystallinity, and a more uniform sintering state between particles, forming a dense microstructure with low defect density.

[0060] From the perspective of the formation mechanism of infrared emissivity, the above-mentioned morphological differences directly lead to the significant difference in infrared emissivity between the two samples: First, the porous, rough, and high specific surface area structure of the Comparative Example 1 sample will form a "multiple reflection-absorption" trap effect on the incident infrared radiation. Infrared photons are repeatedly reflected and absorbed in the pores and depressions, which greatly reduces the reflectivity of the material to infrared radiation, thereby significantly increasing the emissivity; while the dense and smooth surface of the Example 1 sample can effectively reduce the multiple absorption process of infrared photons, enhance the surface reflectivity, and suppress the increase in emissivity.

[0061] (3) Analysis of infrared emissivity results The infrared emissivity of the ceramic materials prepared by Examples 1-10 and Comparative Examples 1-3 in the 8-14 μm wavelength band was tested, and the results are shown in Table 1: Table 1 Infrared emissivity results of materials for each group According to Table 1 and Figure 4The results show that when x=0 (undoped, Comparative Example 1), the emissivity of the corresponding material is 0.62; when x=0.05 (Example 1, Ca doping percentage 1.67%), the emissivity of the corresponding material drops to a minimum of 0.29; when x=0.10 (Example 2, Ca doping percentage 3.3%), the emissivity of the corresponding material rises back to 0.32; and when x=0.15 (Example 3, Ca doping percentage 5%), the emissivity of the corresponding material further increases to 0.46. Based on the above results, it can be seen that an appropriate amount of Ca... 2+ (x=0.05) replaces La 3+ Subsequently, to maintain charge balance, some Co 3+ Oxidized to Co 4+ Introducing more hole carriers further reduces the resistivity of the material, thereby significantly reducing its infrared emissivity; simultaneously, Ca... 2+ Doping-induced lattice distortion and hierarchical microsphere structures enhance multiple scattering and absorption of infrared radiation, further synergistically reducing emissivity. However, when Ca... 2+ When the doping concentration is too high (e.g., x ≥ 0.10), excessive heterovalent substitution further disrupts the lattice symmetry of the system and cannot effectively increase Co. 4+ Concentration, on the contrary, leads to an increase in resistivity, and emissivity subsequently rises. In summary, in the structure of the perovskite ceramic material provided in this application, different Ca doping amounts significantly affect the infrared emissivity of the material, and by controlling the Ca doping amount within the range of this application, the material can achieve better infrared low-emissivity performance (i.e., achieve a lower infrared emissivity).

[0062] (4) Analysis of radar transmittance results See further Figure 5 , Figure 5 This is a graph showing the radar transmittance test data of the perovskite ceramic material prepared in Example 1 of this application. According to... Figure 3 The results show that the transmittance curve of the perovskite ceramic material prepared in Example 1 exhibits slight fluctuations throughout the entire frequency band, but the overall performance is relatively stable without sharp drops or peaks. The optimal transmittance value occurs at the low-frequency end (close to -0.2 dB). As the frequency increases, the performance deteriorates slightly, but at the highest frequency of 18 GHz, the transmittance is still better than -1.0 dB. These results further demonstrate that the perovskite ceramic material provided in this application possesses both low infrared emissivity and low electromagnetic loss, achieving radar absorption compatibility.

[0063] See further Figure 6 , Figure 6 This is a physical optical image of the perovskite ceramic material prepared in Example 1 of this application, based on... Figure 6The results show that this ceramic material is a dark-colored powder.

[0064] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A perovskite-type ceramic material, characterized in that, The perovskite ceramic material has a cubic phase perovskite structure, and the molecular formula of the perovskite ceramic material is La. 1-x Ca x BaCoO 3-δ Where 0 < x ≤ 0.15, and δ is the non-stoichiometric value of oxygen.

2. The perovskite ceramic material according to claim 1, characterized in that, The molecular formula of the perovskite ceramic material is La. 1-x Ca x BaCoO 3-δ , where 0 < x < 0.075, and δ is the non-stoichiometric value of oxygen.

3. The perovskite ceramic material according to claim 1, characterized in that, In the perovskite ceramic material, the raw material source of La is La(NO3)3·6H2O; the raw material source of Ca is Ca(NO3)2·4H2O; the raw material source of Ba is Ba(NO3); and the raw material source of Co is Co(NO3)2·6H2O.

4. A method for preparing a perovskite-type ceramic material, characterized in that, The preparation method includes: S1. Weigh each raw material according to the molar ratio of each element in the molecular formula of the perovskite ceramic material, and fully dissolve each raw material. S2. Based on the dissolved raw materials, the perovskite-type ceramic material is prepared by the sol-gel method.

5. The preparation method according to claim 4, characterized in that, The preparation of the perovskite-type ceramic material based on the dissolved raw materials via the sol-gel method includes: S21. Add chelating agent and crosslinking agent sequentially to the dissolved raw material system, stir thoroughly to obtain a mixture, and adjust the pH value of the mixture to 7.5-8.0; S22. After heating and stirring the pH-adjusted mixture in a water bath, stop stirring, let it stand for 8-15 hours, and then dry it to obtain a dry gel. S23. The dry gel is calcined to obtain a pre-calcined precursor; the pre-calcined precursor is ground and sieved to obtain precursor powder. S24. After mixing and pressing the precursor powder with the organic binder, the adhesive is removed. S25. After sintering the debinding precursor, the perovskite ceramic material is obtained. The molecular formula of the perovskite ceramic material is La. 1-x Ca x BaCoO 3-δ Where 0 < x ≤ 0.15, and δ is the non-stoichiometric value of oxygen; Preferably, the molecular formula of the perovskite ceramic material is La. 1-x Ca x BaCoO 3-δ , where 0 < x < 0.075, and δ is the non-stoichiometric value of oxygen.

6. The preparation method according to claim 4, characterized in that, The step of fully dissolving each of the preparation materials includes: mixing the weighed preparation materials, adding deionized water, and stirring at a constant temperature until each of the preparation materials is completely dissolved; Preferably, the raw materials for preparation include La(NO3)3·6H2O, Ba(NO3) and Co(NO3)2·6H2O; or, the raw materials for preparation include La(NO3)3·6H2O, Ba(NO3), Co(NO3)2·6H2O and Ca(NO3)2·4H2O. Preferably, the ratio of each raw material to deionized water is 2-3:4, calculated in g / ml. Preferably, the temperature of the constant temperature stirring is 50-70℃.

7. The preparation method according to claim 5, characterized in that, In step S21, the step of sequentially adding a chelating agent and a crosslinking agent to the dissolved raw material system and stirring thoroughly to obtain a crosslinked mixture includes: After adding a chelating agent to the dissolved raw material system and heating and stirring for 10-50 minutes, a crosslinking agent is further added and stirred thoroughly for 10-50 minutes to obtain a crosslinked mixture. Preferably, the chelating agent includes at least one of citric acid, ethylenediaminetetraacetic acid, and tartaric acid; Preferably, the crosslinking agent includes at least one of ethylene glycol, polyethylene glycol, ethylene glycol methyl ether, and glycerol; Preferably, the weight ratio of the chelating agent to the sum of the raw materials used in the preparation is 1~2:2~3; Preferably, the weight ratio of the sum of all the raw materials to the crosslinking agent, calculated in g / ml, is 1~2:2; Preferably, the reagent used to adjust the pH of the mixture is ammonia.

8. The preparation method according to claim 5, characterized in that, In step S22, the conditions for water bath heating and stirring include: the water bath heating and stirring temperature is 70~100℃, and the water bath heating and stirring time is 4-5 h; Preferably, the drying conditions include: a drying temperature of 70~100℃ and a drying time of 5-20h; Preferably, in step S23, the heating procedure for calcining the dry gel includes: raising the calcination temperature from room temperature to 500-700°C and holding it at that temperature for 5-15 hours; preferably, the heating rate is 1-5°C / min. Preferably, in step S23, the sieve mesh size or number is 400-800 mesh.

9. The preparation method according to claim 5, characterized in that, In step S24, the mixing mass ratio of the precursor powder to the organic binder is 100:3~5; preferably, the organic binder includes at least one of polyvinyl alcohol, polyethylene glycol, ethylene glycol methyl ether, and glycerol. Preferably, the method for preparing the organic adhesive includes: adding the raw materials corresponding to the organic adhesive to deionized water and heating and stirring in a water bath to obtain the organic adhesive; Preferably, the water bath heating and stirring temperature is 80~100℃, and the water bath heating and stirring time is 80~150min; preferably, the mass fraction of the organic adhesive is 3%~8%; Preferably, the pressing is performed using a powder tablet press; wherein the pressing pressure is 20~25MPa and the holding time is 1~5min; Preferably, the glue removal includes: raising the temperature to 400~600℃ and holding it at that temperature for 2-10 hours; preferably, the heating rate is 1~5℃ / min; Preferably, in step S25, the sintering heating process includes: One heating cycle: The heating rate is 3~8℃ / min. After heating from room temperature to 400℃-600℃, hold the temperature for 1~5 hours. Secondary heating: After the first heating is completed, continue heating to 1100℃-1200℃ at a heating rate of 3~8℃ / min, and hold for 5-15 hours.

10. The application of a perovskite ceramic material as described in any one of claims 1-3 and / or a perovskite ceramic material prepared by the preparation method as described in any one of claims 4-9 in the field of infrared stealth materials and / or infrared radiation materials.

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