Preparation method of core-shell structure wave-absorbing agent taking hollow ceramic microbeads as core
By using hollow ceramic microspheres as the core and employing surface treatment and coating with nickel-zinc ferrite and polyaniline, a lightweight and efficient core-shell structure microwave absorber was prepared. This solved the problems of high density and insufficient absorption performance of traditional microwave absorbers, and achieved good electromagnetic wave absorption effect at low density.
Patent Information
- Application Number
- CN202311455490.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-03
- Publication Date
- 2026-08-25
- Estimated Expiration
- 2043-11-03
AI Technical Summary
Traditional microwave absorbing agents have high density, making it difficult to meet the requirements of "thin, light, wide, and strong" microwave absorbing coatings. Furthermore, existing microwave absorbing materials have shortcomings in electromagnetic wave absorption performance.
A core-shell structure microwave absorbing agent with hollow ceramic microspheres as the core is prepared by surface treatment and coating with nickel-zinc ferrite and polyaniline. The preparation method includes steps such as ultrasonic dispersion, surface amination, and oxidative polymerization to form a lightweight and efficient microwave absorbing material.
The prepared core-shell structured microwave absorber has low density and low cost, and possesses excellent electromagnetic wave absorption performance, meeting the requirements of lightweight and high-efficiency absorption.
Smart Images
Figure CN117729761B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of microwave absorbing materials technology, specifically to a method for preparing a core-shell structure microwave absorbing agent with hollow ceramic microspheres as the core. Background Technology
[0002] Electromagnetic waves of various frequencies are ubiquitous in the electronics and information industry and in daily life. These electromagnetic waves not only affect the safety of electronic information and equipment, causing damage and information leakage, but also pose significant health risks. Absorbing materials can absorb these electromagnetic waves and convert them into other forms of energy, thereby protecting electronic equipment and human health and safety. Commonly used absorbing materials consist of an absorbing agent with electromagnetic loss capabilities and a matrix with wave transmission properties. The quality of the absorbing agent is a crucial factor affecting the absorption performance of the material. With the development of modern society, new demands have been placed on absorbing agents. Traditional absorbing agents are bulky and dense, limiting their applications. To meet the requirements of "thin, light, wide, and strong" absorbing coatings, research on absorbers is also developing towards high efficiency, lightweight, composite materials, good environmental adaptability, easy maintenance, and high-temperature resistance.
[0003] Hollow ceramic microspheres possess low density due to their hollow structure, and exhibit good corrosion resistance, high-temperature resistance, and chemical stability. Composite microwave absorbing agents with hollow ceramic microspheres as the core have low density, and the hollow structure significantly increases the number of interfaces. These composite microwave absorbing agents effectively overcome the high density problem of traditional microwave absorbing agents, thus enabling the preparation of lightweight microwave absorbing agents. Among many conductive polymers, such as polypyrrole and polyaniline, polyaniline has attracted much attention due to its simple synthesis, high conductivity, good chemical stability, and readily available and inexpensive raw materials. Ferrites, metallic nickel, or their compounds possess good magnetic permeability and are traditional magnetic microwave absorbing agents; however, electromagnetic waves can still penetrate them at high frequencies, resulting in losses. Therefore, microwave absorbing agents need to possess good electrical and magnetic properties to exhibit good microwave absorption performance.
[0004] In view of this, this application proposes a method for preparing a core-shell structure microwave absorber with hollow ceramic microspheres as the core. Summary of the Invention
[0005] The purpose of this invention is to at least solve one of the technical problems existing in the prior art, and to provide a method for preparing a core-shell structure microwave absorber with hollow ceramic microspheres as the core.
[0006] To achieve the above objectives, the technical solution adopted by this invention is as follows: a method for preparing a core-shell structure microwave absorber with hollow ceramic microspheres as the core.
[0007] Including the following methods:
[0008] S1. Take an appropriate amount of hollow ceramic microspheres, ultrasonically disperse them in an acidic solution and stir continuously, perform surface treatment, filter them, wash them with deionized water and ethanol, and dry them in a vacuum drying oven.
[0009] S2. Take the hollow ceramic microspheres that have been acid-washed in step S1 and carry out a surface amination reaction in a silane coupling agent solution to make it easier for other compounds to grow on the surface of the hollow microspheres. After filtration, wash with deionized water and dry.
[0010] S3. Disperse the hollow ceramic microspheres treated in step S2 in the shell solution and stir ultrasonically; then transfer the above system to a reaction vessel for reaction, filter after reaction, wash with deionized water and dry.
[0011] S4. Take the hollow ceramic microspheres treated in step S3 and disperse them in the oxidative polymerization solution for oxidative polymerization. After the reaction, filter them, wash them with deionized water, and dry them in an oven.
[0012] Furthermore, the acidic solution in step S1 includes at least one of dilute nitric acid and hydrofluoric acid.
[0013] Furthermore, in step S1, the mass of hollow ceramic microspheres is 10-20g, the concentration of the acidic solution is 2-10%, and the reaction time is 30-60min.
[0014] Furthermore, in step S2, the silane coupling agent solution is composed of 3-aminopropyltriethoxysilane, ethanol, and water, and the mass-to-volume (g / mL) ratio of the hollow ceramic microspheres to 3-aminopropyltriethoxysilane is 5-10:2-4; the reaction temperature is 60-80℃, and the stirring time is 1.5-2h.
[0015] Furthermore, the shell solution is composed of the following raw materials by weight: 0.1071-0.4961 g of NiCl2·6H2O, 0.0268-0.1241 g of ZnCl2·6H2O, 0.1338-0.6202 g of FeCl3·6H2O, 30 mL of deionized water, and 5 mol / L of sodium hydroxide.
[0016] Furthermore, the shell solution is composed of the following raw materials: 50 mL palladium chloride solution, 50 mL stannous chloride solution, and nickel plating solution. The palladium chloride solution is composed of 0.0015 M PdCl2 and 0.25 M HCl; the stannous chloride solution is composed of 0.1 M SnCl2 and 0.1 M HCl; and the nickel plating solution is composed of 25 g / L NiSO4·6H2O, 25 g / L NaH2PO2·H2O, 25 g / L C6H5Na3O7·2H2O, 15 g / L CH3COONa·3H2O, and 10 g / L lactic acid.
[0017] Furthermore, the reaction temperature in step S3 is 50-180℃, and the reaction time is 1-12h.
[0018] Furthermore, the polymerization oxidation solution is composed of 1 mol / L sulfuric acid solution, aniline, and oxidant. The mass-volume (g / mL) ratio of the hollow microspheres to aniline is 0.2-1.0:0.2-1.0, the molar ratio of the oxidant to aniline is 1:1, and the oxidant is ammonium persulfate.
[0019] Furthermore, the polymerization oxidation solution is composed of pyrrole, ethanol solution, and ferric chloride solution, and the mass ratio of hollow microspheres, pyrrole, and ferric chloride is 0.5:2:4.0-5.0.
[0020] Furthermore, in step S4, the reaction temperature for polymerization oxidation is 0°C or below, and the reaction time is 10-16 h; the drying temperature is 60-80°C, and the drying time is 12-24 h.
[0021] As can be seen from the above description of the present invention, compared with the prior art, the present invention has the following beneficial effects:
[0022] 1. The hollow ceramic microspheres prepared by this invention are core-shell structure microwave absorbers that are first coated with nickel-zinc ferrite and then coated with polyaniline. They have the advantages of low density, simple preparation and low cost.
[0023] 2. The hollow ceramic microspheres prepared by this invention are core-shell structure microwave absorbers that are first coated with nickel-zinc ferrite and then coated with polyaniline, satisfying the characteristics of being lightweight and having high absorption.
[0024] 3. The core-shell structure microwave absorber prepared by this invention, which uses hollow microspheres as the core and is coated with conductive polymer after nickel plating, has lightweight and corrosion-resistant properties.
[0025] 4. The core-shell structure microwave absorber prepared by this invention, which uses hollow microspheres as the core and is coated with conductive polymer after nickel plating, has the advantage of having a high electromagnetic wave absorption effect at low density. Attached Figure Description
[0026] Figure 1 Density diagrams of the core-shell structure microwave absorbers with hollow ceramic microspheres as the core prepared in Examples 1-4 of this invention;
[0027] Figure 2 SEM image of the core-shell structure microwave absorber with hollow ceramic microspheres as the core prepared in Example 1;
[0028] Figure 3 This is a SEM image of the core-shell structure microwave absorber with hollow ceramic microspheres as the core prepared in Example 2.
[0029] Figure 4Image a is a SEM image of the core-shell structure microwave absorber with hollow ceramic microspheres as the core prepared in Example 3; image b is a cross-sectional view of the core-shell structure microwave absorber with hollow ceramic microspheres as the core prepared in Example 3.
[0030] Figure 5 This is a SEM image of the core-shell structure microwave absorber with hollow ceramic microspheres as the core prepared in Example 4.
[0031] Figure 6 The reflection loss diagrams are for the core-shell structure absorbing agents with hollow ceramic microspheres as the core prepared in Examples 1-4 of this invention, wherein (a) HNP30; (b) HNP40; (c) HNP50; (d) HNP60;
[0032] Figure 7 The graphs show the effect of different coating thicknesses on the reflection loss of glass microspheres in Examples 5 and 6.
[0033] Figure 8 The graph shows the effect of polypyrrole coating amount on the reflection loss of nickel-plated glass microspheres in Examples 5 and 6. Detailed Implementation
[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.
[0035] Example 1
[0036] Preparation method of core-shell composite microwave absorber (HNP30) with 30% polyaniline content:
[0037] 1. Take 10g of hollow ceramic microspheres and ultrasonically disperse them in a 10% dilute nitric acid solution with a volume of 325mL. Stir continuously for 30min. Perform surface treatment, filter, wash with deionized water and ethanol, and dry in a vacuum drying oven.
[0038] 2. Take 2 mL of 3-aminopropyltriethoxysilane (KH550) and add it to 100 mL of a mixed solution of ethanol and water in a volume ratio of 95 / 5. Add 5 g of acid-washed hollow ceramic microspheres to the above mixed solution and react at a temperature of 75 °C for 90 min. Amination-treated hollow ceramic microspheres are obtained, filtered, washed with deionized water and ethanol, and dried in a vacuum drying oven.
[0039] 3. Add 0.1071g NiCl2·6H2O, 0.0268g ZnCl2·6H2O, and 0.1338g FeCl3·6H2O to 30mL of deionized water to prepare a mixed solution. Add 5mol / L sodium hydroxide solution to adjust the pH of the solution to 11. Disperse 1.516g of surface-aminated hollow ceramic microspheres into the above mixed solution and then sonicate for 30min. Transfer the above system to a 50mL reactor and react at 180℃ for 10h. After the reaction, centrifuge, wash with deionized water, and dry.
[0040] 4. Add 0.236 mL of aniline monomer to 25 mL of 1 mol / L sulfuric acid aqueous solution. Take 0.5 g of nickel-zinc ferrite-coated hollow ceramic microspheres and disperse them in the aniline solution. Add ammonium persulfate solution (0.3847 g (NH4)2S2O8 + 12.5 mL H2SO4) at 0 °C to carry out an oxidative polymerization reaction. The reaction temperature is 0 °C and the reaction time is 16 h. After the reaction, filter the solution, wash it with deionized water and ethanol, and dry it in an oven at 60 °C for 24 h.
[0041] The core-shell structure microwave absorber with hollow ceramic microspheres as its core appears as a dark green powder, and its density is calculated to be 0.63 g / cm³. 3 ,like Figure 1 As shown; SEM analysis revealed that its morphology exhibited a spherical structure with a surface coating, with a particle size of approximately 25-45 μm. Figure 2 As shown.
[0042] The microwave absorption performance of a core-shell structured absorber with hollow ceramic microspheres as the core was tested using a vector network analyzer (VNA). The results show that the minimum reflection loss is -20.38 dB (f = 4.96 GHz) with a matching thickness of 5.0 mm, and the effective absorption bandwidth (RL < -10 dB) is 1.68 GHz. Figure 6 As shown.
[0043] Example 2
[0044] Preparation method of core-shell composite microwave absorber (HNP40) with 40% polyaniline content:
[0045] 1. Take 10g of hollow ceramic microspheres and ultrasonically disperse them in a 10% dilute nitric acid solution with a volume of 325mL. Stir continuously for 30min. Perform surface treatment, filter, wash with deionized water and ethanol, and dry in a vacuum drying oven.
[0046] 2. Take 2 mL of 3-aminopropyltriethoxysilane (KH550) and add it to 100 mL of a mixed solution of ethanol and water in a volume ratio of 95 / 5. Add 5 g of acid-washed hollow ceramic microspheres to the above mixed solution and react at a temperature of 75 °C for 90 min. Amination-treated hollow ceramic microspheres are obtained, filtered, washed with deionized water and ethanol, and dried in a vacuum drying oven.
[0047] 3. Add 0.2021g NiCl2·6H2O, 0.0505g ZnCl2·6H2O, and 0.2527g FeCl3·6H2O to 30mL of deionized water to prepare a mixed solution. Add 5mol / L sodium hydroxide solution to adjust the pH of the solution to 11. Disperse 1.516g of surface-aminated hollow ceramic microspheres into the above mixed solution and then sonicate for 30min. Transfer the above system to a 50mL reactor and react at 180℃ for 10h. After the reaction, centrifuge, wash with deionized water, and dry.
[0048] 4. Add 0.367 mL of aniline monomer to 25 mL of 1 mol / L sulfuric acid aqueous solution. Take 0.5 g of nickel-zinc ferrite-coated hollow ceramic microspheres and disperse them in the aniline solution. Add ammonium persulfate solution (0.5987 g (NH4)2S2O8 + 12.5 mL H2SO4) at 0 °C to carry out an oxidative polymerization reaction. The reaction temperature is 0 °C and the reaction time is 16 h. After the reaction, filter the solution, wash it with deionized water and ethanol, and dry it in an oven at 60 °C for 24 h.
[0049] The core-shell structure microwave absorber with hollow ceramic microspheres as its core appears as a dark green powder, and its density is calculated to be 0.59 g / cm³. 3 ,like Figure 1 As shown; SEM analysis revealed that its morphology exhibited a spherical structure with a surface coating, with a particle size of approximately 25-45 μm. Figure 3 As shown.
[0050] The microwave absorption performance of a core-shell structured microwave absorber with hollow ceramic microspheres as the core was tested using a vector network analyzer (VNA). The results show that the minimum reflection loss is -36.37 dB (f = 6.96 GHz) at a matching thickness of 3.5 mm, and the effective absorption bandwidth (RL < -10 dB) is 2.24 GHz. Figure 6 As shown.
[0051] Example 3
[0052] Preparation method of core-shell composite microwave absorber (HNP50) with 50% polyaniline content:
[0053] 1. Take 10g of hollow ceramic microspheres and ultrasonically disperse them in a 10% dilute nitric acid solution with a volume of 325mL. Stir continuously for 30min. Perform surface treatment, filter, wash with deionized water and ethanol, and dry in a vacuum drying oven.
[0054] 2. Take 2 mL of 3-aminopropyltriethoxysilane (KH550) and add it to 100 mL of a mixed solution of ethanol and water in a volume ratio of 95 / 5. Add 5 g of acid-washed hollow ceramic microspheres to the above mixed solution and react at a temperature of 75 °C for 90 min. Amination-treated hollow ceramic microspheres are obtained, filtered, washed with deionized water and ethanol, and dried in a vacuum drying oven.
[0055] 3. Add 0.3265g NiCl2·6H2O, 0.0816g ZnCl2·6H2O, and 0.4082g FeCl3·6H2O to 30mL of deionized water to prepare a mixed solution. Add 5mol / L sodium hydroxide solution to adjust the pH of the solution to 11. Disperse 1.516g of surface-aminated hollow ceramic microspheres into the above mixed solution and then sonicate for 30min. Transfer the above system to a 50mL reactor and react at 180℃ for 10h. After the reaction, centrifuge, wash with deionized water, and dry.
[0056] 4. Add 0.550 mL of aniline monomer to 25 mL of 1 mol / L sulfuric acid aqueous solution. Take 0.5 g of nickel-zinc ferrite-coated hollow ceramic microspheres and disperse them in the aniline solution. Add ammonium persulfate solution (0.9012 g (NH4)2S2O8 + 12.5 mL H2SO4) at 0 °C to carry out an oxidative polymerization reaction. The reaction temperature is 0 °C and the reaction time is 16 h. After the reaction, filter the solution, wash it with deionized water and ethanol, and dry it in an oven at 60 °C for 24 h.
[0057] The core-shell structure microwave absorber with hollow ceramic microspheres as its core appears as a dark green powder, and its density is calculated to be 0.52 g / cm³. 3 ,like Figure 1 As shown; SEM analysis revealed that its morphology exhibited a spherical structure with a surface coating, with a particle size of approximately 25-45 μm. Figure 4 As shown in a and b.
[0058] The microwave absorption performance of a core-shell structured microwave absorber with hollow ceramic microspheres as the core was tested using a vector network analyzer (VNA). The results show that the minimum reflection loss is -58.63 dB (f = 16.64 GHz) and the effective absorption bandwidth (RL < -10 dB) is 3.88 GHz when the matching thickness is 1.5 mm. Figure 6 As shown.
[0059] Example 4
[0060] Preparation method of core-shell composite microwave absorber (HNP60) with 60% polyaniline content:
[0061] 1. Take 10g of hollow ceramic microspheres and ultrasonically disperse them in a 10% dilute nitric acid solution with a volume of 325mL. Stir continuously for 30min. Perform surface treatment, filter, wash with deionized water and ethanol, and dry in a vacuum drying oven.
[0062] 2. Take 2 mL of 3-aminopropyltriethoxysilane (KH550) and add it to 100 mL of a mixed solution of ethanol and water in a volume ratio of 95 / 5. Add 5 g of acid-washed hollow ceramic microspheres to the above mixed solution and react at a temperature of 75 °C for 90 min. Amination-treated hollow ceramic microspheres are obtained, filtered, washed with deionized water and ethanol, and dried in a vacuum drying oven.
[0063] 3. Add 0.4961g NiCl2·6H2O, 0.1241g ZnCl2·6H2O, and 0.6202g FeCl3·6H2O to 30mL of deionized water to prepare a mixed solution. Add 5mol / L sodium hydroxide solution to adjust the pH of the solution to 11. Disperse 1.516g of surface-aminated hollow ceramic microspheres into the above mixed solution and then sonicate for 30min. Transfer the above system to a 50mL reactor and react at 180℃ for 10h. After the reaction, centrifuge, wash with deionized water, and dry.
[0064] 4. Add 0.825 mL of aniline monomer to 25 mL of 1 mol / L sulfuric acid aqueous solution. Take 0.5 g of nickel-zinc ferrite-coated hollow ceramic microspheres and disperse them in the aniline solution. Add ammonium persulfate solution (1.3488 g (NH4)2S2O8 + 12.5 mL H2SO4) at 0 °C to carry out an oxidative polymerization reaction. The reaction temperature is 0 °C and the reaction time is 16 h. After the reaction, filter the solution, wash it with deionized water and ethanol, and dry it in an oven at 60 °C for 24 h.
[0065] The core-shell structured microwave absorber with hollow ceramic microspheres as its core appears as a dark green powder, and its density is calculated to be 0.47 g / cm³. 3 ,like Figure 1 As shown; SEM analysis revealed that its morphology exhibited a spherical structure with a surface coating, with a particle size of approximately 25-45 μm. Figure 5 As shown;
[0066] The microwave absorption performance of a core-shell structured microwave absorber with hollow ceramic microspheres as the core was tested using a vector network analyzer (VNA). The results show that the minimum reflection loss is -28.05 dB (f = 7.20 GHz) with a matching thickness of 3.5 mm, and the effective absorption bandwidth (RL < -10 dB) is 2.24 GHz. Figure 6 As shown.
[0067] Example 5
[0068] A method for preparing a hollow core-shell structured lightweight microwave absorber by plating nickel onto hollow microspheres and then coating them with a conductive polymer, the preparation steps of which are as follows:
[0069] Step 1: Take any type of hollow microspheres, disperse them in hydrofluoric acid solution, stir, perform surface treatment, filter, and wash with deionized water.
[0070] The hollow microspheres weigh 20g, the hydrofluoric acid has a concentration of 2% and a volume of 200ml, and the reaction time is 30min.
[0071] Step 2: Take the surface-treated hollow microspheres and immerse them in a silane coupling agent solution to react and aminate the surface of the hollow microspheres. After filtration, wash with deionized water.
[0072] Take 2g of the hollow microspheres from step one, 100ml of ethanol solution with a silane coupling agent content of 30g / L, react at 50℃, and stir for 2h.
[0073] Step 3: Disperse the hollow microspheres treated in Step 2 in a palladium chloride solution, stir under heating conditions, and filter after reaction.
[0074] The palladium chloride solution was prepared as 50 ml of PdCl2 (0.0015 M) + HCl (0.25 M); the reaction temperature was 60 °C and the reaction time was 1 h.
[0075] Step 4: Disperse the hollow microspheres treated in Step 3 in a stannous chloride solution, stir under heating conditions, and filter after reaction.
[0076] The stannous chloride solution was prepared as 50 ml of SnCl2 (0.1 M) + HCl (0.1 M); the reaction temperature was 50 °C, and the stirring time was 2 h.
[0077] Step 5: Disperse the hollow microspheres treated in Step 4 in a nickel plating solution and react under heating conditions to plate the surface of the hollow microspheres with nickel. After the reaction, filter and wash with deionized water.
[0078] The plating solution consisted of NiSO4·6H2O (25 g / L), NaH2PO2·H2O (25 g / L), C6H5Na3O7·2H2O (25 g / L), CH3COONa·3H2O (15 g / L), and lactic acid (10 g / L); the reaction temperature was 75℃ and the reaction time was 1 hour.
[0079] Step six: Take the hollow microspheres treated in step five, disperse them in a pyrrole solution, add ferric chloride solution at 0°C, and carry out an oxidative polymerization reaction for 10 hours; after the reaction, filter, wash with deionized water, and dry in an oven.
[0080] The ingredients included 0.5g of hollow microspheres, 2g of pyrrole, a mixture of 50ml water and 10ml ethanol as solvent, and 4.83g of ferric chloride solution (FeCl3 + 50ml H2O). The drying temperature was 60℃ and the drying time was 12h.
[0081] Example 6
[0082] A method for preparing a hollow core-shell structured lightweight microwave absorber by plating nickel onto hollow microspheres and then coating them with a conductive polymer, the preparation steps of which are as follows:
[0083] Step 1: Take any type of hollow microspheres, disperse them in a solution of sodium fluoride and hydrochloric acid, stir, perform surface treatment, filter, and wash with deionized water.
[0084] The hollow microspheres were 20g, the hydrofluoric acid concentration was 4%, the volume was 400ml, and the reaction time was 30min.
[0085] Step 2: Take the surface-treated hollow microspheres and immerse them in a silane coupling agent solution to react and aminate the surface of the hollow microspheres. After filtration, wash with deionized water.
[0086] Take 2g of the hollow microspheres from step one and 100ml of ethanol solution with a silane coupling agent content of 30g / L.
[0087] Step 3: Disperse the hollow microspheres treated in Step 2 in a palladium chloride solution, stir under heating conditions, and filter after reaction.
[0088] The palladium chloride solution was prepared as 50 ml of PdCl2 (0.002 M) + HCl (0.25 M); the reaction temperature was 60 °C and the reaction time was 1 h.
[0089] Step 4: Disperse the hollow microspheres treated in Step 3 in a stannous chloride solution, stir under heating conditions, and filter after reaction.
[0090] The stannous chloride solution was prepared as 50 ml of SnCl2 (0.1 M) + HCl (0.1 M); the reaction temperature was 50 °C, and the stirring time was 2 h.
[0091] Step 5: Disperse the hollow microspheres treated in Step 4 in a nickel plating solution and react them under heating conditions to plate the surface of the hollow microspheres with nickel; after the reaction, filter the solution and wash with deionized water.
[0092] The plating solution consisted of NiSO4·6H2O (25 g / L), NaH2PO2·H2O (25 g / L), C6H5Na3O7·2H2O (25 g / L), CH3COONa·3H2O (15 g / L), and lactic acid (10 g / L); the reaction temperature was 60℃ and the reaction time was 1 h.
[0093] Step six: Take the hollow microspheres treated in step five, disperse them in a pyrrole solution, add ammonium persulfate solution at 0°C, and carry out an oxidative polymerization reaction for 10 hours; after the reaction, filter, wash with deionized water, and dry in an oven.
[0094] The ingredients included 0.5g of hollow microspheres, 2g of pyrrole, a mixture of 50ml water and 10ml ethanol as solvent, and 6.8g of ammonium persulfate solution (NH4)2S2O8 + 50ml H2O. The drying temperature was 60℃ and the drying time was 12h.
[0095] The microwave absorption performance of a lightweight microwave absorber with a hollow core-shell structure, prepared by coating conductive polymers with nickel-plated hollow microspheres, was tested using a vector network analyzer (VNA).
[0096] like Figure 7 As shown in the diagram, the reflection loss of hollow microspheres with different nickel plating amounts (sample preparation test: the following 5 types of hollow microspheres are all filled with 40wt% in paraffin) shows that: the minimum reflection loss of hollow microspheres is -1.71dB; the minimum reflection loss of hollow microspheres with a nickel plating amount of 2.5wt% is -4.91dB; the minimum reflection loss of hollow microspheres with a nickel plating amount of 10wt% is -15.67dB; the minimum reflection loss of hollow microspheres with a nickel plating amount of 17.5wt% is -25.67dB; and the minimum reflection loss of hollow microspheres with a nickel plating amount of 25wt% is -10.51dB.
[0097] like Figure 8As shown in the diagram, the reflection loss of nickel-plated hollow microspheres (sample preparation test: the filling amount of the following 5 hollow microspheres in paraffin is 20 wt%) is affected by different polypyrrole coating amounts. It can be seen that the minimum reflection loss is -4.85 dB when the polypyrrole coating amount on the surface of the nickel-plated hollow microspheres is 17.5 wt%; the minimum reflection loss is -4.97 dB when the nickel plating thickness on the surface of the hollow microspheres is 20 wt%; the minimum reflection loss is -9.21 dB when the matching polypyrrole coating amount is 40 wt%; the minimum reflection loss is -32.02 dB when the matching polypyrrole coating amount is 60 wt%; and the minimum reflection loss is -18.87 dB when the matching polypyrrole coating amount is 80 wt%.
[0098] Without causing conflict, those skilled in the art can freely combine and use the above-mentioned additional technical features.
[0099] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.
Claims
1. A method for preparing a core-shell structure microwave absorber with hollow ceramic microspheres as the core, characterized in that, Including the following methods: S1. Take an appropriate amount of hollow ceramic microspheres, ultrasonically disperse them in an acidic solution and stir continuously, perform surface treatment, filter them, wash them with deionized water and ethanol, and dry them in a vacuum drying oven. S2. Take the hollow ceramic microspheres that have been acid-washed in step S1 and carry out a surface amination reaction in a silane coupling agent solution to make it easier for other compounds to grow on the surface of the hollow microspheres. After filtration, wash with deionized water and dry. S3. Take the hollow ceramic microspheres treated in step S2, disperse them in the shell solution, and stir ultrasonically; then transfer the above solution to a reaction vessel for reaction, filter after reaction, wash with deionized water and dry. S4. Disperse the hollow ceramic microspheres treated in step S3 in an oxidative polymerization solution and carry out oxidative polymerization. After the reaction, filter the solution, wash with deionized water, and dry in an oven. The shell solution is composed of the following raw materials by weight: 0.1071-0.4961 g of NiCl2·6H2O, 0.0268-0.1241 g of ZnCl2·6H2O, 0.1338-0.6202 g of FeCl3·6H2O, 30 mL of deionized water, and 5 mol / L of sodium hydroxide; The oxidative polymerization solution is composed of 1 mol / L sulfuric acid solution, aniline, and oxidant. The mass-volume ratio of the hollow microspheres to aniline is 0.2-1.0:0.2-1.0, the molar ratio of the oxidant to aniline is 1:1, and the oxidant is ammonium persulfate.
2. The method for preparing the core-shell structure microwave absorber with hollow ceramic microspheres as the core according to claim 1, characterized in that: The acidic solution in step S1 includes at least one of dilute nitric acid and hydrofluoric acid.
3. The method for preparing the core-shell structure microwave absorber with hollow ceramic microspheres as the core according to claim 1, characterized in that: In step S1, the mass of hollow ceramic microspheres is 10-20g, the concentration of the acidic solution is 2-10%, and the reaction time is 30-60 min.
4. The method for preparing the core-shell structure microwave absorber with hollow ceramic microspheres as the core according to claim 1, characterized in that: In step S2, the silane coupling agent solution is composed of 3-aminopropyltriethoxysilane, ethanol, and water. The mass-to-volume ratio of the hollow ceramic microspheres to 3-aminopropyltriethoxysilane is 5-10:2-4. The reaction temperature is 60-80℃, and the stirring time is 1.5-2h.
5. The method for preparing the core-shell structure microwave absorber with hollow ceramic microspheres as the core according to claim 1, characterized in that: The reaction temperature in step S3 is 50-180℃, and the reaction time is 1-12 h.
6. The method for preparing the core-shell structure microwave absorber with hollow ceramic microspheres as the core according to claim 1, characterized in that: In step S4, the polymerization oxidation reaction temperature is 0°C or below, and the reaction time is 10-16 h; the drying temperature is 60-80°C, and the time is 12-24 h.