Method for improving mechanical strength of iron-based alloy magnetic powder core

Abstract

The application discloses a method for improving the mechanical strength of an iron-based alloy magnetic powder core, which comprises the following steps: soaking the insulated iron-based alloy powder into a treatment liquid, forming a film on the surface of the magnetic powder particles after insulation, playing a role of bonding and strengthening the film layer, preventing the deterioration of loss, improving the magnetic powder formability, and enhancing the mechanical strength of the magnetic powder core; then, pressing the magnetic powder into a blank, and soaking the formed green blank into the treatment liquid for secondary soaking, which can make up for the uneven insulation coating of the magnetic powder particles, effectively repair the insulation coating layer on the surface of the green blank of the magnetic powder core which may be damaged due to pressing, play a role of bonding, strengthening the film layer and preventing rust, and solve the problems of the existing green blank of the magnetic powder core, such as difficult pressing forming, easy breaking during transportation, and large environmental pollution of the existing paint spraying process, and effectively prevent the green blank of the magnetic powder core from being broken and the surface from being rusted due to the factors of difficult pressing forming, easy breaking during transportation and environmental influence.

Description

Technical Field

[0001] This invention belongs to the field of magnetic materials technology, specifically relating to a method for improving the mechanical strength of iron-based alloy magnetic powder cores. Background Technology

[0002] There are many types of iron-based alloy magnetic powder cores. Currently, the most commonly used iron-based alloy magnetic powder cores include iron-nickel magnetic powder cores, iron-silicon-aluminum magnetic powder cores, iron-silicon magnetic powder cores, and iron-nickel-molybdenum magnetic powder cores. These are widely used in electronic equipment such as photovoltaic inverters, transformers, new energy vehicle charging piles, and electronic communication devices. The preparation of magnetic powder cores mainly involves four processes: powder selection, insulation coating, pressing and molding, and annealing heat treatment. Among these, insulation coating is crucial in the preparation process and directly affects the excellent performance of the magnetic powder core.

[0003] After the insulating-coated iron-based alloy powder is evenly mixed with a certain amount of release agent, it is placed into a hydraulic forming machine for pressing. During the pressing process, the insulating coating layer on the surface of the alloy powder may be damaged, resulting in low mechanical strength of the pressed green blank. Furthermore, the low mechanical strength of the green magnetic powder core makes it prone to cracking or crushing due to collisions during production and handling, severely impacting practical applications. To prevent the crushing of the iron-based alloy magnetic powder core, a binder is often used in actual production to evenly mix the alloy powder with the binder, thereby improving the mechanical strength of the magnetic powder core. However, the binder's effect on improving mechanical strength is not very good, and the outer skin of the green magnetic powder core is prone to peeling off after prolonged use, affecting its practical application in power electronic equipment. In addition, iron-based alloy magnetic powder cores are mainly composed of iron, making them prone to rusting in humid environments and exhibiting poor corrosion resistance. To prevent rusting, a painting process is often used in actual production, but painting is harmful to the environment. Therefore, developing a process that does not affect the magnetic properties of the magnetic powder core while improving its mechanical strength and providing comprehensive rust prevention is of great significance for enhancing the overall performance of iron-based alloy magnetic powder cores. Summary of the Invention

[0004] To address the problems of low mechanical strength and significant environmental pollution caused by existing magnetic powder cores and spray painting for rust prevention, this invention provides a method for improving the mechanical strength of iron-based alloy magnetic powder cores without affecting their magnetic properties, while simultaneously enhancing their corrosion resistance.

[0005] The present invention provides a method for improving the mechanical strength of iron-based alloy magnetic powder cores, comprising the following steps:

[0006] Step 1: Immerse the insulated iron-based alloy magnetic powder in the treatment solution for 50 minutes; remove the powder, dry it at 90°C for 60 minutes to obtain iron-based alloy powder coated with the treatment solution.

[0007] Step 2: Add a release agent to the iron-based alloy powder coated with the treatment liquid obtained in Step 1, mix evenly, and press into a magnetic powder core green blank;

[0008] Step 3: Immerse the magnetic powder core blank obtained in Step 2 in the treatment solution for a second time for 25 minutes; dry the magnetic powder core blank at 70°C for 10 minutes; after drying, bake the blank under the following conditions: 120-350°C for 20-120 minutes; to obtain the blank soaked in the treatment solution.

[0009] Step 4: The green blank soaked in the treatment solution of Step 3 is annealed in nitrogen at a temperature of 650-850℃ for 60-120 minutes and then cooled in the furnace to obtain the iron-based alloy magnetic powder core.

[0010] In step 1, the iron-based alloy powder is one of the following: gas-atomized iron-silicon-aluminum alloy powder, gas-atomized iron-silicon alloy powder, and crushed iron-silicon-aluminum alloy powder.

[0011] In step 1, the treatment solution is a mixed solution of anhydrous ethanol, kaolin and nano-yttrium oxide, with a mass ratio of 30:1.5:0.6 to 5.4.

[0012] In step 2, the amount of release agent added is 0.3% to 1.0% of the mass of the iron-based alloy powder coated by the treatment liquid; the molding pressure is 1600 MPa to 2000 MPa.

[0013] The treatment solution used in step 3 is the same as that used in step 1. The ratio of the soaking time in step 1 to the soaking time in step 3 is 2:1.

[0014] The effective permeability of the iron-based alloy magnetic powder core obtained in step 4 is 57.2–63, and the loss is 236.7–572.3 mW / cm under the test conditions of 50 kHz / 100 mT. 3 The tensile stress is 1.39–1.96 MPa.

[0015] The design basis of the method of this invention is:

[0016] For iron-based alloy magnetic powder cores, the commonly used methods to improve their mechanical strength mainly involve adding binders during the pressing process and spraying a coating onto the surface of the green powder core, but the final effect is limited. Therefore, this invention provides a method for improving the mechanical strength of iron-based alloy magnetic powder cores, namely, a combined "immersion-baking" process.

[0017] The immersion process involves soaking the insulated alloy powder required for strengthening the iron-based alloy magnetic powder core in a treatment solution. The aim is to ensure that the treatment solution adheres to the surface of each magnetic powder particle. The kaolin in the treatment solution has good adhesion and binding properties, allowing the corrosion-resistant nano-yttrium oxide to adhere to the surface of the insulated iron-based alloy powder. Yttrium enriches and combines with silicon and oxygen in the treatment solution film, increasing the corrosion potential and decreasing the corrosion current density. Simultaneously, it inhibits cathodic reduction reactions, thereby controlling the entire corrosion process. It also acts as a physical barrier, preventing the corrosive medium from penetrating the treatment solution film and thus preventing the iron-based alloy magnetic powder from rusting. The treatment solution also compensates for the unevenness of the magnetic powder during the insulation coating process, blocking the eddy current paths between magnetic powder particles to prevent further increases in loss. Another function is that the good viscosity of the treatment solution improves the formability of the magnetic powder, enhancing the bonding force between the green magnetic powder core blanks during subsequent pressing and molding, thereby increasing the mechanical strength of the magnetic powder core. After the iron-based alloy powder is soaked, the pressed and shaped magnetic powder core blank is immersed in the treatment solution for a second soaking. After soaking, it is baked. In this way, the surface of the magnetic powder core blank can be well repaired for the damage to the insulating film layer caused by pressing and the film layer of the treatment solution layer after the first soaking. It can also make the surface of the blank have high bonding force. This can play a role from both inside and outside, giving the magnetic powder core good mechanical strength. On the other hand, it can also make the surface of the magnetic powder core blank adhere to a layer of treatment solution film, preventing the surface of the magnetic powder core blank from rusting. After being soaked twice, the film is baked at a temperature of 120–350℃ for 20–120 minutes, forming a specific mesh-like porous structure. The nano-yttrium oxide and kaolin in the film can form a limited substitution solid solution, which precipitates in the form of YAl2 strengthening phase and is evenly distributed in the film. The YAl2 strengthening phase has a good coherent or semi-coherent relationship with the iron-based alloy matrix. It can not only act as a nucleation point to refine the grains, but also play a very high pinning effect on dislocations, grain boundaries and subgrain boundaries, which can effectively hinder the migration of dislocations and the growth of grains. Meanwhile, these tiny reinforcing particles have high thermal stability, preventing the alloy grains from growing during baking and subsequent annealing heat treatment. This stabilizes the alloy substructure and inhibits recrystallization, thus improving the alloy's strength. As a result, a layer of processing liquid film can be firmly attached to the surface of the magnetic powder core green blank. The resulting processing liquid film has hydrophobic, adhesive, and reinforcing properties, tightly wrapping the magnetic powder core green blank with a film layer, enhancing the bonding force of the magnetic powder core green blank, and thereby improving the mechanical strength of the magnetic powder core.

[0018] The "immersion-baking" processing sequence in this invention cannot be changed; otherwise, the magnetic powder core will not achieve the desired strengthening effect. If a "baking-immersion" processing sequence is used, the bonding force between the film layer on the surface of the magnetic powder core and the green magnetic powder core blank is weakened, and the processing liquid film layer cannot firmly adhere to the surface of the green magnetic powder core blank. This not only fails to improve the strength of the alloy but also reduces it. The comparative examples in the later embodiments also demonstrate that the "immersion-baking" processing sequence cannot be changed. Ultimately, the "immersion-baking" processing method of this invention can not only further improve the mechanical strength of the magnetic powder core but also enhance its corrosion resistance.

[0019] In the "immersion-baking" process of this invention, the baking temperature and time must be neither too long nor too short. If the baking temperature and time are too short, a striped film structure is easily formed. This structure is loose and has poor adhesion, and cannot adhere well to the surface of the magnetic powder core. Although the nano-yttrium oxide and kaolin in the film can form a limited substitution solid solution, the amount of precipitated YAl2 reinforcement is relatively small, which has a very weak pinning effect on dislocations, grain boundaries, and subgrain boundaries, and cannot effectively hinder dislocation migration and grain growth. Therefore, it has no significant effect on improving the mechanical strength of the magnetic powder core. If the baking temperature and time are too long, a fish-scale film structure is easily formed. Although this film structure is tightly distributed, and the nano-yttrium oxide and kaolin in the film can form a limited substitution solid solution, the precipitated YAl2 reinforcement phase becomes enriched and unevenly distributed due to the excessive baking temperature and time. This promotes grain growth and dislocation migration, thus seriously reducing the mechanical strength of the magnetic powder. Ultimately, the baking conditions in the "immersion-baking" process of this invention are suitable, namely, the baking conditions are: temperature of 120-350℃ and time of 20-120min, which can achieve the purpose of improving the mechanical strength of the magnetic powder core.

[0020] Compared with the prior art, the beneficial effects of the present invention are reflected in:

[0021] 1. In this invention, the iron-based alloy powder after insulation is immersed in a treatment solution. The treatment solution can form a thin film on the surface of the magnetic powder after insulation. The formed treatment solution film can compensate for the non-uniformity of the magnetic powder during the insulation coating process. On the other hand, the formed treatment solution film has the functions of hydrophobicity, adhesion and strengthening of the film layer. Therefore, it can prevent the magnetic powder from rusting and block the eddy current path between magnetic powder particles, thereby preventing further increase in loss.

[0022] 2. This invention employs a combined "immersion-baking" process. After baking at a temperature of 120–350°C for 20–120 minutes, a porous, mesh-like treatment liquid film layer is firmly attached to the surface of the magnetic powder core green body. The YAl2 reinforcing phase in the treatment liquid film layer is evenly dispersed. The YAl2 reinforcing phase not only refines the grains but also effectively hinders dislocation migration and grain growth, enhancing the bonding force of the magnetic powder core green body and thus improving the mechanical strength of the magnetic powder core. At the same time, this process can also repair the insulating film layer and treatment liquid film layer damaged by pressing on the surface of the magnetic powder core green body, improving the corrosion resistance of the magnetic powder core and preventing increased losses.

[0023] 3. The preparation method of this invention is low in cost, simple to operate, and environmentally friendly, making it suitable for large-scale production by enterprises.

[0024] 4. This invention uses a gas-atomized iron-silicon-aluminum magnetic powder core with a permeability level of 60 (±5%) as an example. Sample 1 is the sample without treatment solution, and sample 2 is the sample treated using the process of this invention. The magnetoelectric properties and tensile strength test results of both are shown in Table 1. As can be seen from the table, compared with the sample without treatment solution, the permeability and loss of the sample treated using the process of this invention are not significantly different, but the tensile stress is significantly improved, with an improvement of 30% to 50%. Figure 1 These are two samples that have undergone a double 85 test for 720 hours, by Figure 1 It can be seen that the sample treated by the process of the present invention has a smooth surface, without crushing or peeling, and no rust appears on the surface, indicating good corrosion resistance.

[0025] Table 1

[0026] Attached Figure Description

[0027] Figure 1 (a) Untreated sample and (b) Appearance of the atomized iron-silicon-aluminum magnetic powder core sample after double 85 test following treatment with the process of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1:

[0030] 1. Soak 200g of insulated broken iron-silicon-aluminum alloy powder in 1kg of treatment solution for 50min; remove the powder, dry it at 90℃ for 60min to obtain the treatment solution coated broken iron-silicon-aluminum alloy powder; the treatment solution is prepared by uniformly mixing anhydrous ethanol, kaolin and nano-yttrium oxide in a mass ratio of 30:1.5:3.

[0031] 2. Add 0.6g of release agent to 200g of crushed iron-silicon-aluminum alloy powder coated with treatment liquid, mix evenly, and press into a standard magnetic powder core blank with an outer diameter of 26.92mm, an inner diameter of 14.73mm, and a height of 11.18mm, with a molding pressure of 1600MPa.

[0032] 3. Immerse the pressed magnetic powder core blank in the treatment solution for a second time for 25 minutes; dry the magnetic powder core blank at 70°C for 10 minutes; bake the blank after drying under the following conditions: temperature 230°C and time 80 minutes; to obtain the blank soaked in the treatment solution; the treatment solution is the same as the treatment solution in step 1.

[0033] 4. The green blank soaked in the treatment solution is annealed in nitrogen at a temperature of 650℃ for 60 minutes and then cooled in the furnace to obtain a broken iron-silicon-aluminum magnetic powder core.

[0034] The crushed iron-silicon-aluminum magnetic powder core obtained in this embodiment has an effective permeability of 63 and a loss of 332.6 mW / cm under the test conditions of 50 kHz / 100 mT, as determined by magnetoelectric performance testing. 3 The tensile stress is 1.39 MPa.

[0035] Example 2:

[0036] 1. Immerse 200g of insulated atomized iron-silicon-aluminum alloy powder in 1kg of treatment solution for 50min; remove the powder, dry it at 90℃ for 60min to obtain treatment solution-coated atomized iron-silicon-aluminum alloy powder; the treatment solution is prepared by uniformly mixing anhydrous ethanol, kaolin and nano-yttrium oxide in a mass ratio of 30:1.5:3.

[0037] 2. Add 1.4g of release agent to 200g of atomized iron-silicon-aluminum alloy powder coated with treatment liquid and mix evenly. Press into a standard magnetic powder core blank with an outer diameter of 26.92mm, an inner diameter of 14.73mm, and a height of 11.18mm. The molding pressure is 1800MPa.

[0038] 3. The pressed magnetic powder core blank is immersed in the treatment solution for a second time for 25 minutes; the magnetic powder core blank is dried at 70°C for 10 minutes; after drying, the blank is baked under the following conditions: temperature 230°C and time 80 minutes; a blank soaked in the treatment solution is obtained; the treatment solution is the same as the treatment solution in step (1);

[0039] 4. The green blank soaked in the treatment solution is annealed in nitrogen at a temperature of 750℃ for 90 minutes and then cooled in the furnace to obtain the gas-atomized iron-silicon-aluminum magnetic powder core.

[0040] The gas-atomized iron-silicon-aluminum magnetic powder core obtained in this embodiment has an effective permeability of 57.2 and a loss of 403.7 mW / cm under the test conditions of 50 kHz / 100 mT. 3 The tensile stress is 1.96 MPa.

[0041] Depend on Figure 1 It can be seen that, Figure 1 Figure (a) shows the appearance of an untreated gas-atomized iron-silicon-aluminum magnetic powder core sample after a double 85 test. It is evident that the surface of this magnetic powder core has poor forming effect and exhibits corrosion. Figure (b) shows the appearance of a gas-atomized iron-silicon-aluminum magnetic powder core sample treated with the process of this invention after a double 85 test. It is evident that the surface of this magnetic powder core is smooth, has good forming effect, and shows no signs of corrosion.

[0042] Example 3:

[0043] 1. Immerse 200g of insulated atomized iron-silicon alloy powder in 1kg of treatment solution for 50min; remove the powder, dry it at 90℃ for 60min to obtain treatment solution-coated atomized iron-silicon alloy powder; the treatment solution is prepared by uniformly mixing anhydrous ethanol, kaolin and nano-yttrium oxide in a mass ratio of 30:1.5:3.

[0044] 2. Add 2g of release agent to 200g of atomized iron-silicon alloy powder coated with treatment liquid and mix evenly. Press it into a standard magnetic powder core blank with an outer diameter of 26.92mm, an inner diameter of 14.73mm, and a height of 11.18mm. The molding pressure is 2000MPa.

[0045] 3. The pressed magnetic powder core blank is immersed in the treatment solution for a second time for 25 minutes; the magnetic powder core blank is dried at 70°C for 10 minutes; after drying, the blank is baked under the following conditions: temperature 230°C and time 80 minutes; a blank soaked in the treatment solution is obtained; the treatment solution is the same as the treatment solution in step (1);

[0046] 4. The green blank soaked in the treatment solution is annealed in nitrogen at a temperature of 850℃ for 120 minutes and then cooled in the furnace to obtain the gas-atomized iron-silicon-aluminum magnetic powder core.

[0047] The gas-atomized iron-silicon magnetic powder core obtained in this embodiment was tested for its magnetoelectric properties. The core exhibited an effective permeability of 59.6 and a loss of 403.7 mW / cm² under test conditions of 50 kHz / 100 mT. 3 The tensile stress is 1.64 MPa.

[0048] Example 4:

[0049] 1. Immerse 200g of insulated atomized iron-silicon-aluminum alloy powder in 1kg of treatment solution for 50min; remove the powder, dry it at 90℃ for 60min to obtain treatment solution-coated atomized iron-silicon-aluminum alloy powder; the treatment solution is prepared by uniformly mixing anhydrous ethanol, kaolin and nano-yttrium oxide in a mass ratio of 30:1.5:3.

[0050] 2. Add 1.4g of release agent to 200g of atomized iron-silicon-aluminum alloy powder coated with treatment liquid and mix evenly. Press into a standard magnetic powder core blank with an outer diameter of 26.92mm, an inner diameter of 14.73mm, and a height of 11.18mm. The molding pressure is 1800MPa.

[0051] 3. The pressed magnetic powder core blank is baked under the following conditions: temperature 230℃ and time 80min; then it is immersed in the treatment solution for a second time for 25min; the magnetic powder core blank is dried at 70℃ for 10min; the blank soaked in the treatment solution is obtained; the treatment solution is the same as the treatment solution in step (1);

[0052] 4. The green blank soaked in the treatment solution is annealed in nitrogen at a temperature of 750℃ for 90 minutes and then cooled in the furnace to obtain the gas-atomized iron-silicon-aluminum magnetic powder core.

[0053] The gas-atomized iron-silicon-aluminum magnetic powder core obtained in this embodiment was tested for magnetoelectric properties, and its effective permeability was 59.3, with a loss of 456.2 mW / cm under the test conditions of 50 kHz / 100 mT. 3 The tensile stress is 1.09 MPa.

[0054] Compared with Example 2, it can be seen that the preparation method of improving the mechanical strength of iron-based alloy magnetic powder core in this invention is closely related to the order of "immersion-baking" treatment. That is, immersion must be carried out first, followed by baking, in order to improve the mechanical strength of the magnetic powder core and greatly enhance its corrosion resistance, thereby improving the overall performance of the iron-based alloy magnetic powder core and expanding its application range.

[0055] Example 5:

[0056] 1. Immerse 200g of insulated atomized iron-silicon-aluminum alloy powder in 1kg of treatment solution for 50min; remove the powder, dry it at 90℃ for 60min to obtain treatment solution-coated atomized iron-silicon-aluminum alloy powder; the treatment solution is prepared by uniformly mixing anhydrous ethanol, kaolin and nano-yttrium oxide in a mass ratio of 30:1.5:3.

[0057] 2. Add 1.4g of release agent to 200g of atomized iron-silicon-aluminum alloy powder coated with treatment liquid and mix evenly. Press into a standard magnetic powder core blank with an outer diameter of 26.92mm, an inner diameter of 14.73mm, and a height of 11.18mm. The molding pressure is 1800MPa.

[0058] 3. The pressed magnetic powder core blank is immersed in the treatment solution for a second time for 25 minutes; the magnetic powder core blank is dried at 70°C for 10 minutes; after drying, the blank is baked under the following conditions: temperature 400°C and time 160 minutes; a blank soaked in the treatment solution is obtained; the treatment solution is the same as the treatment solution in step (1);

[0059] 4. The green blank soaked in the treatment solution is annealed in nitrogen at a temperature of 750℃ for 90 minutes and then cooled in the furnace to obtain the gas-atomized iron-silicon-aluminum magnetic powder core.

[0060] The gas-atomized iron-silicon-aluminum magnetic powder core obtained in this embodiment was tested for its magnetoelectric properties. The core exhibited an effective permeability of 58.5 and a loss of 427.3 mW / cm² under test conditions of 50 kHz / 100 mT. 3 The tensile stress is 1.12 MPa.

[0061] Example 6:

[0062] 1. Immerse 200g of insulated atomized iron-silicon-aluminum alloy powder in 1kg of treatment solution for 50min; remove the powder, dry it at 90℃ for 60min to obtain treatment solution-coated atomized iron-silicon-aluminum alloy powder; the treatment solution is prepared by uniformly mixing anhydrous ethanol, kaolin and nano-yttrium oxide in a mass ratio of 30:1.5:3.

[0063] 2. Add 1.4g of release agent to 200g of atomized iron-silicon-aluminum alloy powder coated with treatment liquid and mix evenly. Press into a standard magnetic powder core blank with an outer diameter of 26.92mm, an inner diameter of 14.73mm, and a height of 11.18mm. The molding pressure is 1800MPa.

[0064] 3. The pressed magnetic powder core blank is immersed in the treatment solution for a second time for 25 minutes; the magnetic powder core blank is dried at 70°C for 10 minutes; after drying, the blank is baked under the following conditions: temperature 70°C and time 10 minutes; a blank soaked in the treatment solution is obtained; the treatment solution is the same as the treatment solution in step (1);

[0065] 4. The green blank soaked in the treatment solution is annealed in nitrogen at a temperature of 750℃ for 90 minutes and then cooled in the furnace to obtain the gas-atomized iron-silicon-aluminum magnetic powder core.

[0066] The gas-atomized iron-silicon-aluminum magnetic powder core obtained in this embodiment was tested for magnetoelectric properties, and its effective permeability was 59.5, with a loss of 453.6 mW / cm under the test conditions of 50 kHz / 100 mT. 3 The tensile stress is 1.22 MPa.

[0067] Compared with Example 2, the baking temperature and time in Example 5 were too long and the baking temperature and time in Example 6 were too short. As a result, the mechanical strength of the magnetic powder core in Example 5 was reduced by 42.89% compared with Example 2, and the mechanical strength of the magnetic powder core in Example 6 was reduced by 37.77% compared with Example 2. This shows that the range of baking temperature and time in the "immersion-baking" process of the present invention is appropriate. That is, the baking conditions are: temperature of 120-350℃ and time of 20-120min, which can achieve the purpose of improving the mechanical strength of the magnetic powder core.

[0068] Example 7:

[0069] 1. Immerse 200g of insulated atomized iron-silicon-aluminum alloy powder in 1kg of treatment solution for 50min; remove the powder, dry it at 90℃ for 60min to obtain treatment solution-coated atomized iron-silicon-aluminum alloy powder; the treatment solution is prepared by uniformly mixing anhydrous ethanol, kaolin and nano-yttrium oxide in a mass ratio of 30:1.5:0.6.

[0070] 2. Add 1.4g of release agent to 200g of atomized iron-silicon-aluminum alloy powder coated with treatment liquid and mix evenly. Press into a standard magnetic powder core blank with an outer diameter of 26.92mm, an inner diameter of 14.73mm, and a height of 11.18mm. The molding pressure is 1800MPa.

[0071] 3. The pressed magnetic powder core blank is immersed in the treatment solution for a second time for 25 minutes; the magnetic powder core blank is dried at 70°C for 10 minutes; after drying, the blank is baked under the following conditions: temperature 230°C and time 80 minutes; a blank soaked in the treatment solution is obtained; the treatment solution is the same as the treatment solution in step (1);

[0072] 4. The green blank soaked in the treatment solution is annealed in nitrogen at a temperature of 750℃ for 90 minutes and then cooled in the furnace to obtain the gas-atomized iron-silicon-aluminum magnetic powder core.

[0073] The gas-atomized iron-silicon-aluminum magnetic powder core obtained in this embodiment was tested for its magnetoelectric properties. The core exhibited an effective permeability of 58.5 and a loss of 416.4 mW / cm² under test conditions of 50 kHz / 100 mT. 3 The tensile stress is 1.85 MPa.

[0074] Example 8:

[0075] 1. Immerse 200g of insulated atomized iron-silicon-aluminum alloy powder in 1kg of treatment solution for 50min; remove the powder, dry it at 90℃ for 60min to obtain treatment solution-coated atomized iron-silicon-aluminum alloy powder; the treatment solution is prepared by uniformly mixing anhydrous ethanol, kaolin and nano-yttrium oxide in a mass ratio of 30:1.5:5.4.

[0076] 2. Add 1.4g of release agent to 200g of atomized iron-silicon-aluminum alloy powder coated with treatment liquid and mix evenly. Press into a standard magnetic powder core blank with an outer diameter of 26.92mm, an inner diameter of 14.73mm, and a height of 11.18mm. The molding pressure is 1800MPa.

[0077] 3. The pressed magnetic powder core blank is immersed in the treatment solution for a second time for 25 minutes; the magnetic powder core blank is dried at 70°C for 10 minutes; after drying, the blank is baked under the following conditions: temperature 230°C and time 80 minutes; a blank soaked in the treatment solution is obtained; the treatment solution is the same as the treatment solution in step (1);

[0078] 4. The green blank soaked in the treatment solution is annealed in nitrogen at a temperature of 750℃ for 90 minutes and then cooled in the furnace to obtain the gas-atomized iron-silicon-aluminum magnetic powder core.

[0079] The gas-atomized iron-silicon-aluminum magnetic powder core obtained in this embodiment was tested for its magnetoelectric properties. The core exhibited an effective permeability of 60.8 and a loss of 435.6 mW / cm² under test conditions of 50 kHz / 100 mT. 3 The tensile stress is 1.79 MPa.

[0080] Finally, it should be noted that the above-described embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; all process solutions that are not substantially different from the concept of the present invention are within the protection scope of the present invention.

Claims

1. A method for improving the mechanical strength of iron-based alloy magnetic powder cores, characterized in that... Includes the following steps: Step 1: Immerse the insulated iron-based alloy magnetic powder in the treatment solution, remove the powder, and dry it to obtain iron-based alloy powder coated with the treatment solution. Step 2: Add a release agent to the iron-based alloy powder coated with the treatment liquid obtained in Step 1, mix evenly, and press into a magnetic powder core green blank; Step 3: Immerse the magnetic powder core blank obtained in Step 2 in the treatment solution for a second time, and dry the magnetic powder core blank at 70°C; after drying, bake the blank under the following conditions: 120~350°C for 20~120 min; to obtain the blank soaked in the treatment solution. Step 4: The green blank soaked in the treatment solution of Step 3 is annealed in nitrogen at a temperature of 650~850℃ and a holding time of 60~120min. It is then cooled in the furnace to obtain the iron-based alloy magnetic powder core. In steps 1 and 3, the treatment solution is a mixed solution of anhydrous ethanol, kaolin and nano-yttrium oxide, with a mass ratio of 30:1.5:0.6~5.

4.

2. The method according to claim 1, characterized in that: In step 1, the iron-based alloy powder is one of the following: gas-atomized iron-silicon-aluminum alloy powder, gas-atomized iron-silicon alloy powder, and crushed iron-silicon-aluminum alloy powder.

3. The method according to claim 1, characterized in that: In step 1, the drying temperature is 90 ℃ and the drying time is 60 min.

4. The method according to claim 1, characterized in that: In step 2, the amount of release agent added is 0.3% to 1.0% of the mass of the iron-based alloy powder coated by the treatment liquid.

5. The method according to claim 1, characterized in that: In step 2, the molding pressure is 1600 MPa~2000 MPa.

6. The method according to claim 1, characterized in that: The ratio of the soaking time in step 1 to the soaking time in step 3 is 2:

1.

7. The method according to claim 6, characterized in that: The soaking time in step 1 is 50 min, and the soaking time in step 3 is 25 min.

8. The method according to claim 1, characterized in that: The effective permeability of the iron-based alloy magnetic powder core obtained in step 4 is 57.2~63, and the loss is 236.7~572.3 mW / cm under the test conditions of 50 kHz / 100 mT. 3 The tensile stress is 1.39~1.96MPa.

Images