Preparation method of petal-shaped ferromagnetic metal particles

Abstract

The invention discloses a preparation method of petal-shaped ferromagnetic metal particles, which is characterized in that growing magnetic metal particles generate anisotropy based on an external magnetic field, and anisotropic petal-shaped ferromagnetic metal particles are prepared by a hydrothermal synthesis method. Weighing cobalt chloride hexahydrate and sodium tartrate, and adding deionized water for dissolving; adding a hydrazine hydrate solution with the concentration of more than 80wt%, and uniformly stirring; dropwise adding a sodium hydroxide solution in a stirring state; putting the prepared solution into a reaction kettle, and adding magnetons; then, raising the temperature of the reaction kettle to 100-200 DEG C, reacting for 4-16 hours, and cooling to room temperature; centrifugally separating and drying to obtain a product. The magnetocrystalline anisotropy of the magnetic metal particles is utilized to break through the Snoek constant, high-frequency microwave absorption is achieved, and the performance requirements of high-frequency application materials can be met.

Description

Technical Field

[0001] This invention belongs to the technical field of magnetic material preparation, specifically relating to a method for preparing petal-shaped ferromagnetic metal particles. Background Technology

[0002] Magnetic materials can be used as shielding materials and radar absorbing materials, and can be integrated into various high-frequency microwave devices. Furthermore, depending on the application context, various requirements have been placed on the electromagnetic properties of microwave magnetic materials, further promoting research into related fundamental theories. Research on the microwave characteristics of magnetic materials focuses on analyzing the relationship between material microstructure and electromagnetic properties, providing guidance for the analysis and preparation of microwave magnetic materials. In the study of magnetic metal particles, most are iron-based spherical and sheet-like absorbers, suitable for low-frequency microwave applications. However, existing iron-based spherical and sheet-like absorbers, due to their adherence to the Snoek limit, are insufficient to meet the performance requirements of increasingly sophisticated high-frequency applications. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing petal-shaped ferromagnetic metal particles, aiming to achieve electromagnetic loss of magnetic metal particles in the high-frequency band. This invention utilizes the magnetocrystalline anisotropy of magnetic metal particles to overcome the Snoek constant, obtaining a highly efficient high-frequency microwave absorber, achieving excellent performance in the high-frequency microwave band.

[0004] This invention is mainly achieved through the following technical solutions: A method for preparing petal-shaped ferromagnetic metal particles, which involves using an external magnetic field to induce anisotropy in growing magnetic metal particles, and then using a hydrothermal synthesis method to prepare anisotropic petal-shaped magnetic metal particles; the method includes the following steps: Step S1: Weigh out cobalt chloride hexahydrate and sodium tartrate, and dissolve them in deionized water; Step S2: Add a hydrated hydrazine solution with a concentration greater than 80 wt%, and stir until homogeneous; Step S3: Add sodium hydroxide solution dropwise while stirring; Step S4: Place the solution prepared in step S3 into the reaction vessel and add a magnetic wave; then, heat the reaction vessel to 100°C~200°C and react for 4h~16h, then cool to room temperature; Step S5: Centrifuge and dry to obtain the product.

[0005] To better realize the present invention, in step S1, 1.1424g~6.8544g of cobalt chloride hexahydrate and 1.104g~8.832g of sodium tartrate are weighed and dissolved in 8ml~160ml of deionized water.

[0006] To better realize the present invention, in step S2, 4 ml to 96 ml of hydrated hydrazine solution is added.

[0007] To better realize the present invention, in step S3, 0.6g to 7.2g of solid sodium hydroxide is weighed and 4ml to 36ml of deionized water is added to prepare a sodium hydroxide solution.

[0008] To better realize the present invention, in step S4, the magnetic particle includes type A, type B, type C, octagonal and cross-shaped, and the magnetic force is 0.5-5N.

[0009] To better realize the present invention, in step S5, a vacuum drying oven is used to dry at 80°C for 12 hours.

[0010] To better realize the present invention, further, in step S1, 2.2848g of cobalt chloride hexahydrate and 2.208g of sodium tartrate are weighed and dissolved in 32ml of deionized water; in step S2, 16ml of hydrazine hydrate solution is added; in step S3, 1.2g of solid sodium hydroxide is weighed and added to 12ml of deionized water to prepare a sodium hydroxide solution.

[0011] To better realize the present invention, in step S4, a type B magnetic particle with a magnetic force of 1N is added, and the reactor is heated to 120°C and reacted for 8 hours.

[0012] The beneficial effects of this invention are as follows: This invention controls the morphology, size, and phase of magnetic metal particles by adjusting different substance concentrations, hydrothermal temperatures, hydrothermal times, alkali concentrations, and the magnitude of the applied magnetic field. This increases the magnetocrystalline anisotropy of the magnetic metal particles, thereby effectively controlling their electromagnetic properties and electromagnetic wave absorption performance. This invention utilizes the magnetocrystalline anisotropy of magnetic metal particles to overcome the Snoek constant, achieving high-frequency microwave absorption, which can meet the performance requirements of high-frequency application materials. Attached Figure Description

[0013] Figure 1 The XRD pattern of the petal-shaped ferromagnetic metal particles prepared in Example 2; Figure 2 SEM image of the petal-shaped ferromagnetic metal particles prepared in Example 2; Figure 3 The complex permittivity and loss tangent of the petal-shaped ferromagnetic metal particles prepared in Example 2 are shown. Figure 4 The image shows the complex permeability and loss tangent of the petal-shaped ferromagnetic metal particles prepared in Example 2. Figure 5 The image shows the hysteresis loop of the petal-shaped ferromagnetic metal particles prepared in Example 2. Detailed Implementation

[0014] Example 1: A method for preparing petal-shaped ferromagnetic metal particles is based on the action of an external magnetic field on the growing magnetic metal particles, causing them to become anisotropic. Anisotropic petal-shaped magnetic metal particles are then prepared using a magneton-assisted hydrothermal synthesis method, thereby achieving high-frequency wave absorption performance. The specific steps include: Step 1: Using an electronic balance, weigh out 1.1424 g ~ 6.8544 g of cobalt chloride hexahydrate (CoCl2·6H2O) and place it in a beaker; Step 2: Weigh 1.104g~8.832g of sodium tartrate (C4H4O6Na2·2H2O) using an electronic balance, place it in the beaker from Step 1, and then add 8ml~160ml of deionized water to dissolve it. Step 3: Using a graduated cylinder, measure 4 ml to 96 ml of hydrated hydrazine (N2H4·H2O, wt ≥ 80.0%) and add it to the solution obtained in Step 2 above; Step 4: Using an electronic balance, weigh 0.6g to 7.2g of solid sodium hydroxide (NaOH) and place it in a beaker containing 4ml to 36ml of deionized water.

[0015] Step 5: Under vigorous stirring at 200 r / min, add the sodium hydroxide solution obtained in step 4 to the solution obtained in step 3.

[0016] Step 6: Place the solution obtained in step 5 into a polytetrafluoroethylene-lined reactor, add a magnetic spool, tighten it, place it in an oven, and heat it to 100°C~200°C for 4h~16h.

[0017] Step 7: Allow the sample obtained in Step 6 to cool naturally to room temperature. At this time, blackish-gray particles are deposited on the polytetrafluoroethylene inner substrate. Wash the product several times with deionized water and anhydrous ethanol, centrifuge, and dry in a vacuum drying oven at 80°C for 12 hours to obtain a blackish-gray powder product. Pack it into a sample strip and label it.

[0018] This invention controls the morphology, size, and phase of magnetic metal particles by adjusting different substance concentrations, hydrothermal temperatures, hydrothermal times, alkali concentrations, and the magnitude of the applied magnetic field. This increases the magnetocrystalline anisotropy of the magnetic metal particles, thereby effectively controlling their electromagnetic properties and electromagnetic wave absorption performance. This invention utilizes the magnetocrystalline anisotropy of magnetic metal particles to overcome the Snoek constant, achieving high-frequency microwave absorption, which can meet the performance requirements of high-frequency application materials.

[0019] Example 2: A method for preparing petal-shaped ferromagnetic metal particles, requiring raw materials including cobalt chloride hexahydrate, sodium tartrate, water, hydrazine, deionized water, and sodium hydroxide, all of analytical grade. The magnetic particles include type A, type B, type C, octagonal, and cross-shaped types, with a magnetic force of 0.5-5 N. The method specifically includes the following steps: Step 1: Using an electronic balance, weigh 2.2848g of cobalt chloride hexahydrate (CoCl2·6H2O) and place it in a beaker; Step 2: Weigh 2.208g of sodium tartrate (C4H4O6Na2·2H2O) using an electronic balance, place it in the beaker from Step 1, and then add 32ml of deionized water to dissolve it. Step 3: Using a graduated cylinder, measure 16 ml of hydrated hydrazine (N2H4·H2O, wt≥80.0%) and add it to the solution obtained in Step 2 above; Step 4: Using an electronic balance, weigh 1.2g of solid sodium hydroxide (NaOH) and place it in a beaker containing 12ml of deionized water.

[0020] Step 5: Add the sodium hydroxide solution obtained in step 4 to the solution obtained in step 3 while stirring vigorously.

[0021] Step 6: Place the solution obtained in step 5 into a polytetrafluoroethylene-lined reactor, add a type B magnetic spool with a magnetic force of 1N, tighten it, place it in an oven, and heat it to 120°C for 8 hours.

[0022] Step 7: Allow the sample obtained in Step 6 to cool naturally to room temperature. At this time, blackish-gray particles are deposited on the polytetrafluoroethylene inner substrate. Wash the product several times with deionized water and anhydrous ethanol, centrifuge, and dry in a vacuum drying oven at 80°C for 12 hours to obtain a blackish-gray powder product. Pack it into a sample strip and label it.

[0023] like Figure 1 and Figure 2 As shown, the prepared samples were analyzed by XRD and SEM. Figure 2 As shown, (a) is a SEM image of the ferromagnetic metal particles prepared without the addition of magnetic particles, and (b) is a SEM image of the petal-shaped ferromagnetic metal particles prepared in this embodiment. The comparison reveals that this invention prepares petal-shaped ferromagnetic metal particles using a combination of magnetic particles and hydrothermal method, and that this invention offers high controllability and can be mass-produced.

[0024] like Figure 3As shown, (a) is a graph showing the variation of the real part of the dielectric constant of the ferromagnetic metal particles prepared with and without magnets; (b) is a graph showing the variation of the imaginary part of the dielectric constant of the ferromagnetic metal particles prepared with and without magnets; and (c) is a graph showing the variation of the dielectric loss tangent of the ferromagnetic metal particles prepared with and without magnets. From the dielectric loss tangent, it can be seen that at 15 GHz, the petal-shaped ferromagnetic metal particles prepared with magnets exhibit a dielectric loss absorption peak. Since the specific surface area of ​​the petal-shaped particles is higher than that of the spherical particles, the hysteresis loss is stronger when electromagnetic waves interact with the petal-shaped particles. Therefore, the petal-shaped ferromagnetic metal particles prepared in this embodiment have better dielectric properties.

[0025] like Figure 4 As shown, (a) is a graph showing the variation of the real part of the permeability of the ferromagnetic metal particles prepared with and without magnetons; (b) is a graph showing the variation of the imaginary part of the permeability of the ferromagnetic metal particles prepared with and without magnetons; and (c) is a graph showing the variation of the permeability loss tangent of the ferromagnetic metal particles prepared with and without magnetons. From the permeability loss tangent, it can be seen that at 13 GHz, the petal-shaped ferromagnetic metal particles prepared with magnetons have a stronger magnetic loss absorption peak. Since the specific surface area of ​​the petal-shaped particles is higher than that of the spherical particles, the interaction between the petal-shaped particles and the electromagnetic waves is enhanced when irradiated by electromagnetic waves, thereby increasing the magnetic loss. Therefore, the petal-shaped ferromagnetic metal particles prepared in this embodiment have better magnetic loss performance.

[0026] like Figure 5 As shown, the hysteresis loop of the petal-shaped ferromagnetic metal particles prepared in this embodiment characterizes the magnetization properties of the magnetic material, and its coercivity, saturation magnetization, remanence and other parameters can be obtained.

[0027] In summary, this invention can ensure the uniformity of the prepared powder and the process is stable. It provides a stable and simple preparation method for magnetic metal particles with magnetocrystalline anisotropy, which can be applied in fields such as electromagnetic shielding and electromagnetic wave absorption, and has good practicality.

[0028] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing petal-shaped ferromagnetic metal particles, characterized in that, Anisotropic magnetic metal particles are induced to grow using an external magnetic field, and anisotropic petal-shaped magnetic metal particles are prepared using a hydrothermal synthesis method; the process includes the following steps: Step S1: Weigh out cobalt chloride hexahydrate and sodium tartrate, and dissolve them in deionized water; Step S2: Add a hydrated hydrazine solution with a concentration greater than 80 wt%, and stir until homogeneous; Step S3: Add sodium hydroxide solution dropwise while stirring; Step S4: Place the solution prepared in step S3 into a reaction vessel and add a magnetic wave; then, heat the reaction vessel to 100°C~200°C and react for 4h~16h, then cool to room temperature; Step S5: Centrifuge and dry to obtain the product.

2. The method for preparing petal-shaped ferromagnetic metal particles according to claim 1, characterized in that, In step S1, weigh 1.1424g~6.8544g of cobalt chloride hexahydrate and 1.104g~8.832g of sodium tartrate, and dissolve them in 8ml~160ml of deionized water.

3. The method for preparing petal-shaped ferromagnetic metal particles according to claim 2, characterized in that, In step S2, 4 ml to 96 ml of hydrated hydrazine solution is added.

4. The method for preparing petal-shaped ferromagnetic metal particles according to claim 3, characterized in that, In step S3, 0.6g to 7.2g of solid sodium hydroxide is weighed and 4ml to 36ml of deionized water is added to prepare a sodium hydroxide solution.

5. The method for preparing petal-shaped ferromagnetic metal particles according to claim 1, characterized in that, In step S4, the magnetic particle includes type A, type B, type C, octagonal and cross-shaped, and the magnetic force is 0.5-5N.

6. The method for preparing petal-shaped ferromagnetic metal particles according to claim 1, characterized in that, In step S5, a vacuum drying oven is used to dry the product at 80°C for 12 hours.

7. The method for preparing petal-shaped ferromagnetic metal particles according to claim 1, characterized in that, In step S1, 2.2848g of cobalt chloride hexahydrate and 2.208g of sodium tartrate are weighed and dissolved in 32ml of deionized water; in step S2, 16ml of hydrazine hydrate solution is added; in step S3, 1.2g of solid sodium hydroxide is weighed and dissolved in 12ml of deionized water to prepare a sodium hydroxide solution.

8. The method for preparing petal-shaped ferromagnetic metal particles according to claim 7, characterized in that, In step S4, a type B magnetic particle with a magnetic force of 1N is added, and the reactor is heated to 120°C and reacted for 8 hours.

Images