B-site doped perovskite type composite wave-absorbing ceramic as well as preparation method and application thereof

Abstract

The invention belongs to the field of new materials, and discloses B-site doped perovskite type composite wave-absorbing ceramic as well as a preparation method and application thereof. The main phase of the composite wave-absorbing ceramic is LaMnxFe1 / 2 (1-x) Co1 / 2 (1-x) O3, and Cu-Zn oxide is compounded. The composite wave-absorbing ceramic not only has an excellent wave-absorbing effect, but also meets the requirement of thin thickness of a ceramic material. According to the preparation method of some examples of the invention, a method of simultaneously completing perovskite synthesis and compounding through one-step sintering is adopted to replace a conventional method of respectively synthesizing perovskite powder and Cu-Zn oxide and then compounding, energy is saved, and the preparation cost is greatly reduced. The preparation method is simple to operate, adopts a step-by-step reaction sintering method, ensures smooth synthesis of LaMnxFe1 / 2 (1-x) Co1 / 2 (1-x) O3, realizes densification of the composite ceramic, and can prepare the high-quality LaMnxFe1 / 2 (1-x) Co1 / 2 (1-x) O3 perovskite type Cu-Zn oxide composite ceramic.

Description

Technical Field

[0001] This invention belongs to the field of new materials, specifically relating to a B-site doped perovskite composite microwave absorbing ceramic, its preparation method, and its application. Background Technology

[0002] Microwave absorbing materials are in high demand in fields such as electromagnetic protection, stealth technology, and microwave communications. Perovskite oxides (ABO3) are considered a class of highly promising microwave absorbing materials due to their unique electronic structure, tunable composition, and good temperature stability. Among them, LaMnO3-based materials have been extensively studied due to their inherent Jahn-Teller distortion and complex magnetoelectric properties. Existing techniques typically employ single-ion doping to modulate their dielectric and magnetic properties in order to achieve impedance matching and enhanced loss mechanisms. However, such single-doping modifications often fail to achieve excellent impedance matching and strong attenuation capabilities, resulting in overall microwave absorption performance, especially in low-frequency bands (such as C and X bands), which is insufficient to meet the growing application demands.

[0003] Previous studies have shown that B-site doping has a certain impact on the microwave absorption performance of LaMnO3-based materials. Different elemental doping has different effects on the material's performance, and the specific mechanisms are not fully understood. Zinc oxide (ZnO) and copper oxide (CuO) are commonly used ceramic additives or second-phase materials, but current technologies mostly use them to improve the varistor, thermoelectric, or catalytic properties of materials, or simply as a single second phase in simple composites with perovskite. Currently, there is a lack of a systematic design that can combine the synergistic doping of multiple B-site ions with the precise introduction of a specific second phase (CuO / ZnO). Through multi-component, multi-scale synergistic effects, while controlling the intrinsic electromagnetic parameters of the perovskite matrix, rich heterogeneous interfaces and defect structures can be constructed at grain boundaries. This synergistic effect is expected to simultaneously optimize the impedance matching characteristics of the material and enhance various loss mechanisms such as dielectric relaxation, magnetic domain resonance, and interfacial polarization, thereby breaking through the performance limits of single-component or simple composite materials and obtaining composite microwave absorbing ceramics with strong absorption, thin thickness, and excellent thermal stability. Currently, there are no reports on the preparation of perovskite-type composite microwave absorbing ceramics and their microwave absorption performance using doped synergistic multi-component systems. Summary of the Invention

[0004] The purpose of this invention is to overcome at least one deficiency of the prior art and to provide a B-site doped perovskite composite microwave absorbing ceramic, its preparation method, and its application.

[0005] The technical solution adopted in this invention is: The first aspect of the present invention provides: A B-site doped perovskite composite microwave absorbing ceramic, with LaMn as the main ceramic phase. x Fe 1 / 2(1-x) Co1 / 2(1-x) O3, where 0.1≤x≤0.9, the main ceramic phase contains Cu-Zn oxide, and the mass percentage of Cu-Zn oxide is 5-50% of the main ceramic phase.

[0006] In some instances, the molar ratio of Cu to Zn is 1:1.

[0007] A second aspect of the present invention provides: The preparation method of the B-site doped perovskite composite absorbing ceramic according to the first aspect of the present invention includes the following steps: S1) Weigh the ceramic main phase raw materials according to the proportion, add water and ball mill to mix evenly to obtain a slurry; S2) Add CuO and ZnO to the slurry, ball mill and mix thoroughly until uniform, then dry to obtain a mixed powder; S3) The mixed powder is reacted and sintered in steps to obtain pre-calcined powder; S4) Pre-fired powder is ball-milled with water to obtain pre-fired powder slurry, and then dried to obtain raw powder; S5) The raw powder is shaped and sintered to obtain B-site doped perovskite composite microwave absorbing ceramic.

[0008] In some instances, the stepwise reaction sintering includes: 1) Increase the temperature to 900-1200℃ at a rate of 5-8℃ / min and hold for a period of time to form a perovskite phase; 2) Further increase the temperature to 1250-1400℃ at 3-5℃ / min and hold for heat to induce CuO-ZnO eutectic liquidation, thereby achieving densification of the composite ceramic; 3) Reduce the temperature to 900-1100℃ at a rate of 2-4℃ / min, hold the temperature to eliminate the internal stress of the composite ceramic, and then cool it with the furnace.

[0009] In some instances, the holding time for stepwise operation 1) in the stepwise reaction sintering is 2 to 12 hours.

[0010] In some instances, the holding time for stepwise operation 2) in the stepwise reaction sintering is 1 to 5 hours.

[0011] In some instances, the holding time for stepwise operation 3) in the stepwise reaction sintering is 2 to 6 hours.

[0012] In some instances, the sintering conditions for step S5) are: a heating rate of 2–5 °C / min and a sintering temperature of 1250–1500 °C.

[0013] In some instances, the sintering holding time in step S5) is 2 to 10 hours.

[0014] In some instances, the powder forming method is pressure forming, with a forming pressure of 5–30 MPa.

[0015] In some instances, the main ceramic phase raw materials are La2O3, Co3O4, Fe3O4, and Mn3O4.

[0016] These features can be combined arbitrarily as long as they do not conflict with each other.

[0017] A third aspect of the present invention provides: A microwave absorbing device, the surface of which is covered with B-site doped perovskite composite microwave absorbing ceramic as described in the first aspect of the present invention, or B-site doped perovskite composite microwave absorbing ceramic prepared according to the preparation method described in the second aspect of the present invention.

[0018] The beneficial effects of this invention are: The B-site doped perovskite composite absorbing ceramics of some examples of the present invention not only have excellent absorption effect, but also meet the requirement of thin ceramic material thickness. While ensuring that the minimum reflectivity value reaches -39dB, the material thickness is only 1.7mm.

[0019] The preparation methods of some examples of this invention are simple to operate and employ a stepwise reaction sintering method to ensure the quality of LaMn. x Fe 1 / 2(1-x) Co 1 / 2(1-x) While successfully synthesizing O3, the densification of the composite ceramic can be achieved, enabling the preparation of high-quality LaMn. x Fe 1 / 2(1-x) Co 1 / 2(1-x) O3 perovskite type Cu-Zn oxide composite ceramics.

[0020] The preparation methods of some examples of this invention utilize raw materials that are inexpensive and widely available. The microwave absorption properties of high-entropy ceramics can be controlled by adjusting the sintering process parameters.

[0021] The preparation methods of some examples of this invention adopt the method of "simultaneous synthesis and composite of perovskite in one-step sintering" instead of the conventional method of "separately synthesizing perovskite powder and Cu-Zn oxide and then composite", which saves energy and greatly reduces the preparation cost. Attached Figure Description

[0022] Figure 1 This is a scanning electron microscope image of the perovskite-type composite absorbing ceramic in Example 1 of the present invention.

[0023] Figures 2-9 This is the energy spectrum of the perovskite-type composite microwave absorbing ceramic in Example 1 of the present invention.

[0024] Figure 10 The reflectivity is the perovskite-type composite absorbing ceramic in Example 1 of this invention.

[0025] Figures 11-16 For Comparative Example 1, LaMn 0.3 Fe 0.35 Co 0.35 Energy spectrum of O3 ceramics.

[0026] Figure 17 For Comparative Example 1, LaMn 0.3 Fe 0.35 Co 0.35 Reflectivity of O3 ceramics. Detailed Implementation

[0027] The first aspect of the present invention provides: A B-site doped perovskite composite microwave absorbing ceramic, with LaMn as the main ceramic phase. x Fe 1 / 2(1-x) Co 1 / 2(1-x) O3, where 0.1≤x≤0.9, the main ceramic phase contains Cu-Zn oxide, and the mass percentage of Cu-Zn oxide is 5-50% of the main ceramic phase.

[0028] In some instances, the molar ratio of Cu to Zn is 1:1.

[0029] In some examples, the mass percentage of Cu-Zn oxide is 5% to 40% of the ceramic main phase. The specific content can be adjusted according to the absorption requirements.

[0030] A second aspect of the present invention provides: The preparation method of the B-site doped perovskite composite absorbing ceramic according to the first aspect of the present invention includes the following steps: S1) Weigh the ceramic main phase raw materials according to the proportion, add water and ball mill to mix evenly to obtain a slurry; S2) Add CuO and ZnO to the slurry, ball mill and mix thoroughly until uniform, then dry to obtain a mixed powder; S3) The mixed powder is reacted and sintered in steps to obtain pre-calcined powder; S4) Pre-fired powder is ball-milled with water to obtain pre-fired powder slurry, and then dried to obtain raw powder; S5) The raw powder is shaped and sintered to obtain B-site doped perovskite composite microwave absorbing ceramic.

[0031] In some instances, the stepwise reaction sintering includes: 1) Increase the temperature to 900-1200℃ at a rate of 5-8℃ / min and hold for a period of time to form a perovskite phase; 2) Further increase the temperature to 1250-1400℃ at 3-5℃ / min and hold for heat to induce CuO-ZnO eutectic liquidation, thereby achieving densification of the composite ceramic; 3) Reduce the temperature to 900-1100℃ at a rate of 2-4℃ / min, hold the temperature to eliminate the internal stress of the composite ceramic, and then cool it with the furnace.

[0032] In some instances, the holding time for stepwise operation 1) in the stepwise reaction sintering is 2 to 12 hours.

[0033] In some instances, the holding time for stepwise operation 2) in the stepwise reaction sintering is 1 to 5 hours.

[0034] In some instances, the holding time for stepwise operation 3) in the stepwise reaction sintering is 2 to 6 hours.

[0035] In some instances, the sintering conditions for step S5) are: a heating rate of 2–5 °C / min and a sintering temperature of 1250–1500 °C.

[0036] In some instances, the sintering holding time in step S5) is 2 to 10 hours.

[0037] In some instances, the powder forming method is pressure forming, with a forming pressure of 5–30 MPa.

[0038] In some examples, the main ceramic phase raw materials are La2O3, Co3O4, Fe3O4, and Mn3O4. These raw materials are widely available and inexpensive.

[0039] The technical solution of the present invention will be further illustrated below with examples, but the scope of protection of the present invention is not limited to the content described.

[0040] In the following examples, unless otherwise specified, the molar mixing ratio of CuO to ZnO is 1:1.

[0041] Reflectivity test The reflectivity testing equipment was a waveguide vector network analyzer, and the test band was the X-band (8.2-12.4 GHz).

[0042] Example 1 B-site doped perovskite composite absorbing ceramics (main ceramic phase: LaMn) 0.6 Fe 0.2 Co 0.2 The preparation method of O3 includes the following steps: S1) Weigh the materials La2O3: Mn3O4: Fe3O4: Co3O4 according to a molar ratio of 15:6:2:2; S2) Place the raw material in a polytetrafluoroethylene ball mill jar, use zirconium oxide as the grinding medium, add deionized water, the ball-to-material ratio is 5:1, the ball milling time is 10 hours, and the rotation speed is 600 r / min. S3) Add 40% CuO and ZnO by mass of the raw materials to the above slurry, and continue to ball mill in a planetary ball mill for 2 hours at a speed of 200 r / min. S4) Place the above mixture in a forced-air drying oven at 120°C for 12 hours to dry thoroughly and obtain the mixed powder; S5) The above powder is sintered in a muffle furnace in a stepwise reaction. Step 1: Heat to 1200℃ at 5℃ / min and hold for 10 hours. Step 2: Heat to 1300℃ at 3℃ / min and hold for 5 hours. Step 3: Cool to 1000℃ at 2℃ / min and hold for 2 hours, then cool to room temperature in the furnace. S6) The above pre-calcined powder was placed in a polytetrafluoroethylene ball milling jar for planetary ball milling. The ball milling time was 6 hours and the rotation speed was 300 r / min to obtain a ceramic mixed slurry. S7) Pour out the ceramic mixing slurry and put it into a forced-air drying oven to dry at 120℃ for 12 hours; S8) Ceramic green bodies are prepared by granulation and pressing, with a molding pressure within 10 MPa and a holding time of 5 min. S9) The above ceramic blank is placed in a muffle furnace for sintering at a temperature of 1400℃, a heating rate of 5℃ / min, and a holding time of 10h.

[0043] Figure 1 The image shown is a scanning electron microscope image of the perovskite-type composite absorbing ceramic in Example 1 of the present invention. It can be seen that the main ceramic phase and Cu-Zn oxide particles are uniformly dispersed.

[0044] Figures 2 to 9 The image shows the energy spectrum of the perovskite-type composite microwave absorbing ceramic in Example 1 of this invention. The elements La, Mn, O, Fe, Co, Cu, and Zn are uniformly dispersed in the perovskite-type composite microwave absorbing ceramic.

[0045] Figure 10 The image shows the reflectivity of the perovskite-type composite absorbing ceramic in Example 1 of this invention within the material thickness range of 1.2 to 2.2 mm. It can be seen that when the material thickness is only 1.7 mm, the perovskite-type composite absorbing ceramic has the lowest reflectivity and the best absorption effect.

[0046] The B-site doped perovskite composite absorbing ceramic obtained in Example 1 can achieve a minimum reflectivity of -39dB when the thickness is only 1.7mm.

[0047] Table 1 shows the LaMn content in the perovskite-type composite absorbing ceramic in Example 1 of the present invention. 0.6 Fe 0.2 Co 0.2 Elemental content analysis of the O3 phase (main ceramic phase). element quality% atomic molar mass % O 19.76 60.00 La 57.19 20.00 Mn 13.57 12.00 Fe 4.60 4.00 Co 4.85 4.00 Zn 0.00 0.00 Cu 0.00 0.00 total 100.00 100.00

[0048] Note: Elemental analysis was performed using normalization, meaning the total content of O, La, Mn, Fe, Co, Zn, and Cu is 1. The contents are relative to each other. Elemental analysis results indicate that stepwise ball milling effectively produced LaMn... 0.6 Fe 0.2 Co 0.2 O3 and Cu-Zn oxides achieve a simple composite effect, and the Cu-Zn oxides do not enter the main phase of the ceramic.

[0049] Example 2 B-site doped perovskite composite absorbing ceramics (main ceramic phase: LaMn) 0.4 Fe 0.3 Co 0.3 The preparation method of O3 includes the following steps: S1) Weigh the materials La2O3: Mn3O4: Fe3O4: Co3O4 according to a molar ratio of 15:4:3:3; S2) Place the raw material in a polytetrafluoroethylene ball mill jar, use zirconium oxide as the grinding medium, add deionized water, the ball-to-material ratio is 5:1, the ball milling time is 10 hours, and the rotation speed is 600 r / min. S3) Add 15% CuO and ZnO by mass of the raw materials to the above slurry, and continue to ball mill in a planetary ball mill for 2 hours at a speed of 200 r / min. S4) Place the above mixture in a forced-air drying oven at 120°C for 12 hours; S5) The above powder is sintered in a muffle furnace in a stepwise reaction. Step 1: Heat to 1000℃ at 5℃ / min and hold for 6 hours. Step 2: Heat to 1250℃ at 3℃ / min and hold for 5 hours. Step 3: Cool to 900℃ at 2℃ / min and hold for 3 hours, then cool to room temperature in the furnace. S6) The above pre-calcined powder was placed in a polytetrafluoroethylene ball milling jar for planetary ball milling treatment. The ball milling time was 6 hours and the rotation speed was 300 r / min. S7) Pour out the mixed slurry and put it into a forced-air drying oven to dry at 120℃ for 12 hours; S8) Ceramic green bodies are prepared by granulation and pressing, with a molding pressure within the range of 20 MPa and a holding time of 3 min. S9) The above ceramic blank is placed in a muffle furnace for sintering at a temperature of 1250℃, a heating rate of 3℃ / min, and a holding time of 5h.

[0050] The B-site doped perovskite composite absorbing ceramic obtained in Example 2 can achieve a minimum reflectivity of -18dB when the thickness is 2mm.

[0051] Example 3 B-site doped perovskite composite absorbing ceramics (main ceramic phase: LaMn) 0.6 Fe 0.2 Co 0.2 The preparation method of O3 includes the following steps: S1) Weigh the materials La2O3: Mn3O4: Fe3O4: Co3O4 according to a molar ratio of 15:6:2:2; S2) Place the raw material in a polytetrafluoroethylene ball mill jar, use zirconium oxide as the grinding medium, add deionized water, the ball-to-material ratio is 5:1, the ball milling time is 10 hours, and the rotation speed is 600 r / min. S3) Add 20% CuO and ZnO by mass of the raw materials to the above slurry, and continue to ball mill in a planetary ball mill for 2 hours at a speed of 200 r / min. S4) Place the above mixture in a forced-air drying oven at 120°C for 12 hours; S5) The above powder is sintered in a muffle furnace in a stepwise reaction. Step 1: Heat to 1100℃ at 8℃ / min and hold for 10 hours. Step 2: Heat to 1250℃ at 3℃ / min and hold for 4 hours. Step 3: Reduce temperature to 950℃ at 2℃ / min and hold for 2 hours, then cool to room temperature with the furnace. S6) The above pre-calcined powder was placed in a polytetrafluoroethylene ball milling jar for planetary ball milling treatment. The ball milling time was 6 hours and the rotation speed was 300 r / min. S7) Pour out the mixed slurry and put it into a forced-air drying oven to dry at 120℃ for 12 hours; S8) Ceramic green bodies are prepared by granulation and pressing, with a molding pressure within the range of 15MPa and a holding time of 4min. S9) The above ceramic blank is placed in a muffle furnace for sintering at a temperature of 1400℃, a heating rate of 4℃ / min, and a holding time of 5h.

[0052] The B-site doped perovskite composite absorbing ceramic obtained in Example 3 has a minimum reflectivity of -27dB when the thickness is 2.2mm.

[0053] Example 4 B-site doped perovskite composite absorbing ceramics (main ceramic phase: LaMn) 0.3 Fe 0.35 Co 0.35 The preparation method of O3 includes the following steps: S1) Weigh the La2O3: Mn3O4: Fe3O4: Co3O4 according to a molar ratio of 30:6:7:7; S2) Place the raw material in a polytetrafluoroethylene ball mill jar, use zirconium oxide as the grinding medium, add deionized water, the ball-to-material ratio is 5:1, the ball milling time is 10 hours, and the rotation speed is 600 r / min. S3) Add 5% by mass of CuO and ZnO to the above slurry, and continue to ball mill in a planetary ball mill for 2 hours at a speed of 200 r / min. S4) Place the above mixture in a forced-air drying oven at 120°C for 12 hours; S5) The above powder is sintered in a muffle furnace in a stepwise reaction. Step 1: Heat to 1050℃ at 8℃ / min and hold for 2 hours. Step 2: Heat to 1300℃ at 4℃ / min and hold for 1 hour. Step 3: Cool to 1000℃ at 3℃ / min and hold for 6 hours, then cool to room temperature in the furnace. S6) The above pre-calcined powder was placed in a polytetrafluoroethylene ball milling jar for planetary ball milling treatment. The ball milling time was 6 hours and the rotation speed was 300 r / min. S7) Pour out the mixed slurry and put it into a forced-air drying oven to dry at 120℃ for 12 hours; S8) Ceramic green bodies are prepared by granulation and pressing, with a molding pressure within 30 MPa and a holding time of 3 min. S9) The above ceramic body is placed in a muffle furnace for sintering at a temperature of 1350℃, a heating rate of 2℃ / min, and a holding time of 10h.

[0054] The B-site doped perovskite composite absorbing ceramic obtained in Example 4 has a minimum reflectivity of -21dB when the thickness is 2.5mm.

[0055] Example 5 B-site doped perovskite composite absorbing ceramics (main ceramic phase: LaMn) 0.3 Fe 0.35 Co 0.35 The preparation method of O3 includes the following steps: S1) Weigh the La2O3: Mn3O4: Fe3O4: Co3O4 according to a molar ratio of 30:6:7:7; S2) Place the raw material in a polytetrafluoroethylene ball mill jar, use zirconium oxide as the grinding medium, add deionized water, the ball-to-material ratio is 5:1, the ball milling time is 10 hours, and the rotation speed is 600 r / min. S3) Add 5% by mass of CuO and ZnO to the above slurry, and continue to ball mill in a planetary ball mill for 2 hours at a speed of 200 r / min. S4) Place the above mixture in a forced-air drying oven at 120°C for 12 hours; S5) The above powder is sintered in a muffle furnace in a stepwise reaction. Step 1: Heat to 1200℃ at 8℃ / min and hold for 2 hours. Step 2: Heat to 1400℃ at 4℃ / min and hold for 1 hour. Step 3: Cool to 1000℃ at 3℃ / min and hold for 6 hours, then cool to room temperature in the furnace. S6) The above pre-calcined powder was placed in a polytetrafluoroethylene ball milling jar for planetary ball milling treatment. The ball milling time was 6 hours and the rotation speed was 300 r / min. S7) Pour out the mixed slurry and put it into a forced-air drying oven to dry at 120℃ for 12 hours; S8) Ceramic green bodies are prepared by granulation and pressing, with a molding pressure within 30 MPa and a holding time of 3 min. S9) The above ceramic blank is placed in a muffle furnace for sintering at a temperature of 1450℃, a heating rate of 2℃ / min, and a holding time of 10h.

[0056] The B-site doped perovskite composite absorbing ceramic obtained in Example 5 can achieve a minimum reflectivity of -25dB when the thickness is 2mm.

[0057] Example 6 B-site doped perovskite composite absorbing ceramics (main ceramic phase: LaMn) 0.9 Fe 0.05 Co 0.05 The preparation method of O3 includes the following steps: S1) Weigh the materials La2O3: Mn3O4: Fe3O4: Co3O4 in a molar ratio of 30:18:1:1; S2) Place the raw material in a polytetrafluoroethylene ball mill jar, use zirconium oxide as the grinding medium, add deionized water, the ball-to-material ratio is 5:1, the ball milling time is 10 hours, and the rotation speed is 600 r / min. S3) Add 40% CuO and ZnO by mass of the raw materials to the above slurry, and continue to ball mill in a planetary ball mill for 2 hours at a speed of 200 r / min. S4) Place the above mixture in a forced-air drying oven at 120°C for 12 hours to dry thoroughly and obtain the mixed powder; S5) The above powder is sintered in a muffle furnace in a stepwise reaction. Step 1: Heat to 1200℃ at 5℃ / min and hold for 10 hours. Step 2: Heat to 1300℃ at 3℃ / min and hold for 5 hours. Step 3: Cool to 1000℃ at 2℃ / min and hold for 2 hours, then cool to room temperature in the furnace. S6) The above pre-calcined powder was placed in a polytetrafluoroethylene ball milling jar for planetary ball milling. The ball milling time was 6 hours and the rotation speed was 300 r / min to obtain a ceramic mixed slurry. S7) Pour out the ceramic mixing slurry and put it into a forced-air drying oven to dry at 120℃ for 12 hours; S8) Ceramic green bodies are prepared by granulation and pressing, with a molding pressure within 10 MPa and a holding time of 5 min. S9) The above ceramic blank is placed in a muffle furnace for sintering at a temperature of 1400℃, a heating rate of 5℃ / min, and a holding time of 10h.

[0058] The B-site doped perovskite composite absorbing ceramic obtained in Example 6 has a minimum reflectivity of -16dB when the thickness is 1.9mm.

[0059] Example 7 B-site doped perovskite composite absorbing ceramics (main ceramic phase: LaMn) 0.1 Fe 0.45 Co 0.45 The preparation method of O3 includes the following steps: S1) Weigh the materials La2O3: Mn3O4: Fe3O4: Co3O4 according to a molar ratio of 30:2:9:9; S2) Place the raw material in a polytetrafluoroethylene ball mill jar, use zirconium oxide as the grinding medium, add deionized water, the ball-to-material ratio is 5:1, the ball milling time is 10 hours, and the rotation speed is 600 r / min. S3) Add 40% CuO and ZnO by mass of the raw materials to the above slurry, and continue to ball mill in a planetary ball mill for 2 hours at a speed of 200 r / min. S4) Place the above mixture in a forced-air drying oven at 120°C for 12 hours to dry thoroughly and obtain the mixed powder; S5) The above powder is sintered in a muffle furnace in a stepwise reaction. Step 1: Heat to 1200℃ at 5℃ / min and hold for 10 hours. Step 2: Heat to 1300℃ at 3℃ / min and hold for 5 hours. Step 3: Cool to 1000℃ at 2℃ / min and hold for 2 hours, then cool to room temperature in the furnace. S6) The above pre-calcined powder was placed in a polytetrafluoroethylene ball milling jar for planetary ball milling. The ball milling time was 6 hours and the rotation speed was 300 r / min to obtain a ceramic mixed slurry. S7) Pour out the ceramic mixing slurry and put it into a forced-air drying oven to dry at 120℃ for 12 hours; S8) Ceramic green bodies are prepared by granulation and pressing, with a molding pressure within 10 MPa and a holding time of 5 min. S9) The above ceramic blank is placed in a muffle furnace for sintering at a temperature of 1400℃, a heating rate of 5℃ / min, and a holding time of 10h.

[0060] The B-site doped perovskite composite absorbing ceramic obtained in Example 5 has a minimum reflectivity of -18dB when the thickness is 2.3mm.

[0061] Comparative Example 1 LaMn 0.3 Fe 0.35 Co 0.35 The preparation method of O3 ceramics includes the following steps: S1) Weigh the La2O3: Mn3O4: Fe3O4: Co3O4 according to a molar ratio of 30:6:7:7; S2) Place the raw material in a polytetrafluoroethylene ball mill jar, use zirconium oxide as the grinding medium, add deionized water, the ball-to-material ratio is 5:1, the ball milling time is 10 hours, and the rotation speed is 600 r / min. S4) Place the above mixture in a forced-air drying oven at 120°C for 12 hours to dry thoroughly and obtain the mixed powder; S5) Heat the above powder to 1300°C in a muffle furnace at 3°C / min, hold for 5 hours, and then cool to room temperature with the furnace. S6) The above pre-calcined powder was placed in a polytetrafluoroethylene ball milling jar for planetary ball milling. The ball milling time was 6 hours and the rotation speed was 300 r / min to obtain a ceramic mixed slurry. S7) Pour out the ceramic mixing slurry and put it into a forced-air drying oven to dry at 120℃ for 12 hours; S8) Ceramic green bodies are prepared by granulation and pressing, with a molding pressure within 10 MPa and a holding time of 5 min. S9) The above ceramic blank is placed in a muffle furnace for sintering at a temperature of 1400℃, a heating rate of 5℃ / min, and a holding time of 10h.

[0062] Figures 11-16 For Comparative Example 1, LaMn 0.3 Fe 0.35 Co0.35 The energy spectrum of O3 ceramics shows that LaMn 0.3 Fe 0.35 Co 0.35 O3 ceramics are dense and have a uniform distribution of La, Mn, Fe, Co, and O elements.

[0063] Figure 17 For Comparative Example 1, LaMn 0.3 Fe 0.35 Co 0.35 The reflectivity of O3 ceramics in the material thickness range of 1.2-2.2 mm shows that at a thickness of 1.9 mm, LaMn... 0.3 Fe 0.35 Co 0.35 O3 ceramics have the lowest reflectivity, but it only reaches -14dB.

[0064] Overall, increasing the Cu-Zn composite content helps to reduce the reflectivity value and improve the wave absorption effect; increasing the sintering temperature also helps to reduce the reflectivity value; different ceramic components have a greater impact on reflectivity, and excessive or insufficient amounts of La, Mn, Fe, and Co are all detrimental to the final reflectivity result.

[0065] The above is a further detailed description of the present invention and should not be considered as a limitation on the specific implementation of the present invention. For those skilled in the art, simple deductions or substitutions without departing from the concept of the present invention are all within the protection scope of the present invention.

Claims

1. A B-site doped perovskite composite absorbing ceramic, characterized in that, The main phase of the ceramic is LaMn x Fe 1 / 2(1-x) Co 1 / 2(1-x) O3, where 0.1≤x≤0.9, the main ceramic phase contains Cu-Zn oxide, and the mass percentage of Cu-Zn oxide is 5-50% of the main ceramic phase.

2. The B-site doped perovskite composite absorbing ceramic according to claim 1, characterized in that, The molar ratio of Cu to Zn is 1:

1.

3. The method for preparing the B-site doped perovskite composite microwave absorbing ceramic according to claim 1, characterized in that, Includes the following steps: S1) Weigh the ceramic main phase raw materials according to the proportion, add water and ball mill to mix evenly to obtain a slurry; S2) Add CuO and ZnO to the slurry, ball mill and mix thoroughly until uniform, then dry to obtain a mixed powder; S3) The mixed powder is reacted and sintered in steps to obtain pre-calcined powder; S4) Pre-fired powder is ball-milled with water to obtain pre-fired powder slurry, and then dried to obtain raw powder; S5) The raw powder is shaped and sintered to obtain B-site doped perovskite composite microwave absorbing ceramic.

4. The preparation method according to claim 3, characterized in that, The stepwise reaction sintering includes: 1) Increase the temperature to 900-1200℃ at a rate of 5-8℃ / min and hold for a period of time to form a perovskite phase; 2) Further increase the temperature to 1250-1400℃ at a rate of 3-5℃ / min, and hold the temperature to allow CuO-ZnO to eutectic liquid phase, thereby achieving densification of the composite ceramic; 3) Reduce the temperature to 900-1100℃ at a rate of 2-4℃ / min, hold the temperature to eliminate the internal stress of the composite ceramic, and then cool it with the furnace.

5. The preparation method according to claim 4, characterized in that, In the stepwise reaction sintering, the holding time for stepwise operation 1) is 2–12 hours; and / or Step 2) involves a heat preservation time of 1–5 hours; and / or The heat preservation time for step 3) is 2 to 6 hours.

6. The preparation method according to claim 3, characterized in that, The sintering conditions for step S5) are: heating rate of 2-5℃ / min and sintering temperature of 1250-1500℃.

7. The preparation method according to claim 3 or 6, characterized in that, The sintering holding time in step S5) is 2 to 10 hours.

8. The preparation method according to claim 3, characterized in that, The method for forming the raw material powder is pressure forming, with a forming pressure of 5 to 30 MPa.

9. The preparation method according to claim 3, characterized in that, The main phase raw materials of the ceramic are La2O3, Co3O4, Fe3O4 and Mn3O4.

10. A wave-absorbing device, characterized in that, Its surface is covered with the B-site doped perovskite composite absorbing ceramic as described in claim 1 or 2, or the B-site doped perovskite composite absorbing ceramic prepared by the preparation method described in any one of claims 3 to 8.

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