Method for preparing high-permeability iron-nickel / iron-silicon magnetic powder core through lamination

Abstract

The invention provides a method for preparing a high-permeability iron-nickel / iron-silicon magnetic powder core through lamination, and relates to the technical field of magnetic material preparation. The method for preparing the high-magnetic-conductivity iron-nickel / iron-silicon magnetic powder core through lamination mainly comprises the steps that iron-nickel and iron-silicon composite magnetic powder is prepared firstly, then lamination and pressure maintaining are sequentially conducted according to the proportion for shape fixing, and then annealing treatment is conducted to prepare the layered iron-nickel / iron-silicon magnetic powder core. According to the method, the defects in the prior art are overcome, the problems that stress is difficult to eliminate and the process is complex in the traditional pressing process are solved, and the cost in the mass production process is reduced while the performance of the magnetic core is improved.

Description

Technical Field

[0001] The invention relates to the technical field of magnetic material preparation, and in particular to a method for preparing a high-permeability iron-nickel / iron-silicon magnetic powder core by lamination. Background Art

[0002] In recent years, iron-based soft magnetic powder composites (SMCs) have attracted widespread attention due to their high saturation magnetic susceptibility, high magnetic permeability, and low magnetic loss. Consequently, SMCs are now widely used in miniature high-frequency electronic components, such as high-frequency sensors. The traditional process for preparing magnetic powder cores typically involves applying an insulating coating to the magnetic powder, followed by compression and molding of the coated powder, and finally annealing to produce the powder core sample. After the powder coating, compression molding is a key step in the industrial production of powder cores to meet the requirements of various electronic component shapes. During compression molding, the coated powder is placed into various film molds and compressed into a desired shape. The molds used in this process are designed based on the specific geometry of the desired device and are typically annular in shape. Lubricants such as zinc stearate and magnesium stearate are added during the compression stage to improve mold release. However, the internal stresses associated with compression molding cannot be completely eliminated through limited annealing, so further research is needed in this area.

[0003] In order to solve this thorny problem, some researchers have proposed warm pressing, which can reduce the molding pressure and the internal stress caused by it. The patent CN202310957011 mentions a method for preparing a low-loss, high-overlap composite magnetic powder core by using warm pressing to improve the lubrication between powder particles, reduce the internal stress of the magnetic powder core compact, reduce the breakage of the insulating coating, and increase the pressing density of the magnetic core. At the same time, with sendust as the main component and a small amount of iron silicon and iron nickel added, a composite magnetic powder core with excellent magnetic properties was obtained through improvements in component matching, particle size ratio, coating and pressing processes.

[0004] Some patents also propose laminated preparation methods, suggesting a new method for preparing magnetic materials. Patent publication CN202411888969 proposes a flexible composite electromagnetic shielding film with a layered composite structure, providing an electromagnetic shielding film product with broadband protection, high shielding effectiveness, and process flexibility.

[0005] However, new processes such as warm pressing introduce new procedures, which increase the cost of the preparation process. The simple mixing and pressing of several different magnetic powders is difficult to control the pressing process, and the performance of the material is difficult to regulate, which has a certain impact on the quality of the actual magnetic material. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the present invention provides a method for laminating and preparing high magnetic permeability iron-nickel / iron-silicon magnetic powder cores, which solves the problems of difficulty in eliminating stress and complex process in the traditional pressing process, improves the performance of the magnetic core and reduces the cost in the mass production process.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions: A method for laminating and preparing a high magnetic permeability iron-nickel / iron-silicon magnetic powder core, the method comprising the following steps: S1, mixing aerosolized spherical Fe-50wt.%Ni powder and aerosolized spherical Fe-5.5wt.%Si powder with a binder and anhydrous ethanol respectively, mixing and drying to obtain iron-nickel composite magnetic powder and iron-silicon composite magnetic powder; S2, respectively mixing iron-nickel composite magnetic powder and iron-silicon composite magnetic powder with a release agent to prepare iron-nickel composite powder and iron-silicon composite powder, roughly pressing the iron-silicon composite powder into a mold as a bottom layer, then adding iron-nickel composite powder and roughly pressing it as a middle layer, and finally adding iron-silicon composite powder as an upper layer and pressing and molding to obtain a sandwich structure iron-silicon / iron-nickel / iron-silicon magnetic ring rough embryo; S3. Place the rough blank into a tube furnace for annealing to obtain a layered iron-nickel / iron-silicon magnetic powder core.

[0008] Preferably, in step S1, when the aerosolized spherical Fe-50wt.%Ni powder and the aerosolized spherical Fe-5.5wt.%Si powder are mixed with the binder and anhydrous ethanol respectively, the content of anhydrous ethanol is 8 wt%~15 wt%, and the content of the binder is 0.5 wt%~2.0 wt%.

[0009] Preferably, in step S1, the D50 of the aerosolized spherical Fe-50wt.%Ni powder and the aerosolized spherical Fe-5.5wt.%Si powder is 30 μm, and the binder is a silicone resin.

[0010] Preferably, the method of drying after mixing in step S1 is to first place the mixture in an ultrasonic cleaning machine for 10 minutes to 30 minutes, and then place it in an oven at 50° C. to 70° C. for 30 minutes to 60 minutes.

[0011] Preferably, the release agent in step S2 is zinc stearate, and the amount of the release agent in the iron-nickel composite powder and the iron-silicon composite powder is 0.3 wt % to 0.5 wt %.

[0012] Preferably, in the iron-silicon / iron-nickel / iron-silicon magnetic ring rough blank of the sandwich structure in step S2, the iron-silicon composite powder accounts for 20 wt%~80 wt%, the iron-nickel composite powder accounts for 20 wt%~80 wt%, and the amount of iron-silicon composite powder in the bottom layer and the upper layer is the same.

[0013] Preferably, the compression molding pressure is 1100 MPa to 1200 MPa, and the holding time is 10 min to 20 min.

[0014] Preferably, the annealing in step S3 is performed under a nitrogen protection atmosphere.

[0015] Preferably, the annealing method is to first increase the temperature to 480°C to 500°C at a heating rate of 3°C / min, keep the temperature for 0.5h to 2.0h, and then cool in the furnace.

[0016] The present invention provides a method for laminating and preparing a high-permeability iron-nickel / iron-silicon magnetic powder core, which has the following advantages over the prior art: The present invention uses high-performance iron-nickel as the middle layer and adds iron-silicon powder on both sides to prepare a sandwich-structured laminated magnetic ring, which has improved density and higher magnetic permeability than samples prepared from a single powder. In addition, the present invention adds low-priced iron-silicon powder to the more expensive iron-nickel powder without introducing new processes, greatly reducing production costs. The morphology of the pressed sample magnetic ring can be clearly observed, making it easy to control the yield of the magnetic ring. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 This is a physical picture of the finished layered iron-nickel / iron-silicon magnetic powder core in Example 2 of the present invention; Figure 2 The X-ray diffraction patterns of the iron-nickel composite powder and the iron-silicon composite powder after annealing of the present invention; Figure 3 The following are scanning electron microscope images of the raw powders and the laminated powders of the present invention, wherein (a) is an electron microscope image of the raw iron-nickel powder, and (b) is an electron microscope image of the raw iron-silicon powder; (c) is an electron microscope image of the cross section of the sample pressed after simple mixing in Comparative Example 3, and (d) is an electron microscope image of the cross section of the sample prepared by lamination in Example 1; Figure 4 Schematic diagram of the curve of the change of magnetic permeability of the magnetic powder core samples prepared in Examples 1-4 of the present invention and Comparative Examples 1-3 as a function of frequency; Figure 5 Schematic diagram of the curve showing the change of magnetic loss with frequency for the magnetic powder core samples prepared in Examples 1-4 of the present invention and Comparative Examples 1-3. DETAILED DESCRIPTION

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0018] The silicone resin used in the following examples was Wacker silicone resin MSE100. The iron-nickel raw powder and the iron-silicon raw powder were aerosolized spherical Fe-50 wt.% Ni powder (D50 = 30 μm) and aerosolized spherical Fe-5.5 wt.% Si powder (D50 = 75 μm), respectively. The rings extruded from the mold used below had an outer diameter of 13.95 mm to 14.10 mm, an inner diameter of 7.85 mm to 7.95 mm, and a thickness of 5.30 mm to 5.60 mm.

[0019] Example 1: Preparation of FeNi / FeSi magnetic powder core: (1) 1.0 wt% silicone resin dissolved in 10 wt% anhydrous ethanol was added to 20 g of iron-nickel and iron-silicon raw powders, respectively. After stirring, the mixture was placed in an ultrasonic cleaner for 10 min and then dried in an oven at 60°C to obtain iron-nickel composite magnetic powder and iron-silicon composite magnetic powder, respectively. (2) adding 0.5 wt% zinc stearate as a release agent to the iron-nickel composite magnetic powder and the iron-silicon composite magnetic powder, respectively, to obtain iron-nickel composite powder and iron-silicon composite powder; (3) The total mass of each magnetic ring is set to 4 g. First, 40 wt% of iron-silicon composite powder is added to the mold, and a simple stamping is performed using the upper stamp of the mold. After it is slightly shaped, 20 wt% of iron-nickel composite powder is added, and a simple stamping is continued using the upper stamp of the mold. Finally, 40 wt% of iron-silicon composite magnetic powder is added and the mold is placed in a manual press. The mold is pressed at 1120 MPa for 10 minutes to obtain a sandwich magnetic ring rough blank. (4) The obtained magnetic ring blank is placed in a tubular furnace for annealing. The entire annealing process is carried out under a nitrogen protective atmosphere with a heating rate of 3°C / min, a holding temperature of 490°C, and a holding time of 1.0 h. Finally, the core is cooled to room temperature to obtain a layered iron-nickel / iron-silicon magnetic powder core.

[0020] Example 2: Preparation of FeNi / FeSi magnetic powder core: (1) 1.0 wt% silicone resin dissolved in 10 wt% anhydrous ethanol was added to 20 g of iron-nickel and iron-silicon raw powders, respectively. After stirring, the mixture was placed in an ultrasonic cleaner for 10 min and then dried in an oven at 60°C to obtain iron-nickel composite magnetic powder and iron-silicon composite magnetic powder, respectively. (2) adding 0.5 wt% zinc stearate as a release agent to the iron-nickel composite magnetic powder and the iron-silicon composite magnetic powder to obtain iron-nickel composite powder and iron-silicon composite powder; (3) The total mass of each magnetic ring is set to 4 g. First, 30 wt% of iron-silicon composite powder is added to the mold, and a simple punch is performed using the upper punch of the mold. After it is slightly shaped, 40 wt% of iron-nickel composite powder is added, and a simple punch is continued using the upper punch of the mold. Finally, 30 wt% of iron-silicon composite powder is added and the mold is placed in a manual press. The mold is pressed at 1120 MPa for 10 min to obtain a sandwich magnetic ring rough blank. (4) The rough magnetic ring blank is placed in a tubular furnace for annealing. The entire annealing process is carried out under a nitrogen protective atmosphere with a heating rate of 3°C / min, a holding temperature of 490°C, and a holding time of 1.0 h. Finally, the core is cooled to room temperature to obtain a layered iron-nickel / iron-silicon magnetic powder core.

[0021] Example 3: Preparation of FeNi / FeSi magnetic powder core: (1) 1.0 wt% silicone resin dissolved in 10 wt% anhydrous ethanol was added to 20 g of iron-nickel and iron-silicon raw powders, respectively. After stirring, the mixture was placed in an ultrasonic cleaner for 10 min and then dried in an oven at 60°C to obtain iron-nickel composite magnetic powder and iron-silicon composite magnetic powder, respectively. (2) adding 0.5 wt% zinc stearate as a release agent to the iron-nickel composite magnetic powder and the iron-silicon composite magnetic powder to obtain iron-nickel composite powder and iron-silicon composite powder; (3) The total mass of each magnetic ring is set to 4 g. First, 20 wt% of iron-silicon composite powder is added to the mold, and a simple stamping is performed using the upper punch of the mold. After it is slightly shaped, 60 wt% of iron-nickel composite powder is added, and a simple stamping is continued using the upper punch of the mold. Finally, 20 wt% of iron-silicon composite powder is added and the mold is placed in a manual press. The mold is pressed at 1120 MPa for 10 min to obtain a sandwich magnetic ring rough blank. (4) The rough magnetic ring blank is placed in a tubular furnace for annealing. The entire annealing process is carried out under a nitrogen protective atmosphere with a heating rate of 3°C / min, a holding temperature of 490°C, and a holding time of 1.0 h. Finally, the core is cooled to room temperature to obtain a layered iron-nickel / iron-silicon magnetic powder core.

[0022] Example 4: Preparation of FeNi / FeSi magnetic powder core: (1) 1.0 wt% silicone resin dissolved in 10 wt% anhydrous ethanol was added to 20 g of iron-nickel and iron-silicon raw powders, respectively. After stirring, the mixture was placed in an ultrasonic cleaner for 10 min and then dried in an oven at 60°C to obtain iron-nickel composite magnetic powder and iron-silicon composite magnetic powder, respectively. (2) adding 0.5 wt% zinc stearate as a release agent to the iron-nickel composite magnetic powder and the iron-silicon composite magnetic powder to obtain iron-nickel composite powder and iron-silicon composite powder; (3) The total mass of each magnetic ring is set to 4 g. First, 10 wt% of iron-silicon composite powder is added to the mold, and a simple punch is performed using the upper punch of the mold. After it is slightly shaped, 80 wt% of iron-nickel composite powder is added, and a simple punch is continued using the upper punch of the mold. Finally, 10 wt% of iron-silicon composite powder is added and the mold is placed in a manual press. The mold is pressed at 1120 MPa for 10 min to obtain a sandwich magnetic ring rough blank. (4) The rough magnetic ring blank is placed in a tubular furnace for annealing. The entire annealing process is carried out under a nitrogen protective atmosphere with a heating rate of 3°C / min, a holding temperature of 490°C, and a holding time of 1.0 h. Finally, the core is cooled to room temperature to obtain a layered iron-nickel / iron-silicon magnetic powder core.

[0023] Comparative Example 1: Preparation of magnetic powder core: (1) Add 1.0 wt% silicone resin dissolved in 10 wt% anhydrous ethanol to 20 g of iron-nickel raw powder, stir, place in an ultrasonic cleaner and shake for 10 min, and then place in an oven at 60 °C to dry to obtain iron-nickel composite magnetic powder; (2) adding 0.5 wt% zinc stearate as a release agent to the iron-nickel composite magnetic powder to obtain an iron-nickel composite powder; (3) The total mass of each magnetic ring is set to 4 g. After adding iron-nickel composite magnetic powder, it is placed in a manual press and pressed at 1120 MPa for 10 min to obtain a rough magnetic ring blank. (4) The obtained magnetic ring blank is placed in a tubular furnace for annealing. The entire annealing process is carried out under a nitrogen protective atmosphere with a heating rate of 3 °C / min, a holding temperature of 490 °C, and a holding time of 1.0 h. Finally, the iron-nickel magnetic powder core is obtained by cooling to room temperature with the furnace.

[0024] Comparative Example 2: Preparation of magnetic powder core: (1) Add 1.0 wt% of organic silicon resin dissolved in 10 wt% of anhydrous ethanol to 20 g of iron silicon raw powder, stir, place in an ultrasonic cleaner and shake for 10 min, and then place in an oven at 60°C to dry to obtain iron silicon composite magnetic powder; (2) adding 0.5 wt% zinc stearate as a release agent to the iron-silicon composite magnetic powder to obtain an iron-silicon composite powder; (3) The total mass of each magnetic ring is set to 4 g. After adding the iron-silicon composite powder, the ring is placed in a manual press and pressed at 1120 MPa for 10 min to obtain a rough magnetic ring blank. (4) The rough magnetic ring blank is placed in a tubular furnace for annealing. The entire annealing process is carried out under a nitrogen protective atmosphere with a heating rate of 3°C / min, a holding temperature of 490°C, and a holding time of 1.0 h. Finally, the iron silicon magnetic powder core is obtained by cooling to room temperature in the furnace.

[0025] Comparative Example 3: Preparation of magnetic powder core: (1) 1.0 wt% silicone resin dissolved in 10 wt% anhydrous ethanol was added to 20 g of iron-nickel and iron-silicon raw powders, respectively. After stirring, the mixture was placed in an ultrasonic cleaner for 10 min and then dried in an oven at 60°C to obtain iron-nickel composite magnetic powder and iron-silicon composite magnetic powder, respectively. (2) adding 0.5 wt% zinc stearate as a release agent to the iron-nickel composite magnetic powder and the iron-silicon composite magnetic powder to obtain iron-nickel composite powder and iron-silicon composite powder; (3) The total mass of each magnetic ring is set to 4 g. 20 wt% of iron-nickel composite powder and 80 wt% of iron-silicon composite powder are mixed and directly placed into a manual press. The mixture is pressed at 1120 MPa for 10 min to obtain a simple mixed magnetic ring rough blank. (4) The rough magnetic ring blank is placed in a tubular furnace for annealing. The entire annealing process is carried out under a nitrogen protective atmosphere with a heating rate of 3°C / min, a holding temperature of 490°C, and a holding time of 1.0 h. Finally, the magnetic ring is cooled to room temperature to obtain an iron-nickel / iron-silicon magnetic powder core.

[0026] Detection: 1. Testing the X-ray diffraction patterns of the iron-nickel composite powder and the iron-silicon composite powder prepared in Example 1: Figure 2 As shown; 2. Detect the cross-sectional microstructure of the iron-nickel raw powder, iron-silicon raw powder, the iron-nickel / iron-silicon magnetic powder core sample prepared in Comparative Example 3, and the iron-nickel / iron-silicon magnetic powder core sample prepared in Example 1. The specific results are as follows: Figure 3 As shown; 3. The magnetic powder cores prepared in Examples 1-4 and Comparative Examples 1-3 were tested using a BH soft magnetic measuring instrument at a test frequency of 1000 kHz and a magnetic flux density of 20 mT. The specific test results are shown in the following tables and Figure 4 、 Figure 5 As shown: The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing a high magnetic permeability iron-nickel / iron-silicon magnetic powder core by lamination, characterized in that: The method comprises the following steps: S1, mixing aerosolized spherical Fe-50wt.%Ni powder and aerosolized spherical Fe-5.5wt.%Si powder with a binder and anhydrous ethanol respectively, mixing and drying to obtain iron-nickel composite magnetic powder and iron-silicon composite magnetic powder; S2, respectively mixing iron-nickel composite magnetic powder and iron-silicon composite magnetic powder with a release agent to prepare iron-nickel composite powder and iron-silicon composite powder, roughly pressing the iron-silicon composite powder into a mold as a bottom layer, then adding iron-nickel composite powder and roughly pressing it as a middle layer, and finally adding iron-silicon composite powder as an upper layer and pressing and molding to obtain a sandwich structure iron-silicon / iron-nickel / iron-silicon magnetic ring rough embryo; S3. Place the rough blank into a tube furnace for annealing to obtain a layered iron-nickel / iron-silicon magnetic powder core.

2. The method for preparing a high magnetic permeability iron-nickel / iron-silicon magnetic powder core by lamination according to claim 1, characterized in that: In step S1, when the aerosolized spherical Fe-50wt.%Ni powder and the aerosolized spherical Fe-5.5wt.%Si powder are mixed with a binder and anhydrous ethanol respectively, the content of anhydrous ethanol is 8 wt%~15 wt%, and the content of the binder is 0.5 wt%~2.0 wt%.

3. The method for preparing a high magnetic permeability iron-nickel / iron-silicon magnetic powder core by lamination according to claim 1, characterized in that: In step S1 , the D50 of the aerosolized spherical Fe-50 wt. % Ni powder and the aerosolized spherical Fe-5.5 wt. % Si powder is 30 μm, and the binder is a silicone resin.

4. The method for preparing a high permeability iron-nickel / iron-silicon magnetic powder core by lamination according to claim 1, characterized in that: The method of drying after mixing in step S1 is to first place the mixture in an ultrasonic cleaning machine for oscillation treatment for 10 minutes to 30 minutes, and then place it in an oven at 50° C. to 70° C. for 30 minutes to 60 minutes.

5. The method for preparing a high magnetic permeability iron-nickel / iron-silicon magnetic powder core by lamination according to claim 1, characterized in that: In step S2, the release agent is zinc stearate, and the amount of the release agent in the iron-nickel composite powder and the iron-silicon composite powder is 0.3 wt % to 0.5 wt %.

6. The method for preparing a high magnetic permeability iron-nickel / iron-silicon magnetic powder core by lamination according to claim 1, characterized in that: In the sandwich structured iron-silicon / iron-nickel / iron-silicon magnetic ring rough blank in step S2, the iron-silicon composite powder accounts for 20 wt% to 80 wt%, the iron-nickel composite powder accounts for 20 wt% to 80 wt%, and the amount of iron-silicon composite powder in the bottom layer and the upper layer is the same.

7. The method for preparing a high magnetic permeability iron-nickel / iron-silicon magnetic powder core by lamination according to claim 1, characterized in that: The compression molding pressure is 1100 MPa to 1200 MPa, and the holding time is 10 min to 20 min.

8. The method for preparing a high magnetic permeability iron-nickel / iron-silicon magnetic powder core by lamination according to claim 1, characterized in that: The annealing in step S3 is performed under a nitrogen protection atmosphere.

9. The method for preparing a high magnetic permeability iron-nickel / iron-silicon magnetic powder core by lamination according to claim 1, characterized in that: The annealing method is to first increase the temperature to 480° C. to 500° C. at a heating rate of 3° C. / min, keep the temperature for 0.5 h to 2.0 h, and then cool in the furnace.

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