Manufacturing method of soft magnetic metal powder insulating particles

Abstract

The invention relates to a manufacturing method of soft magnetic metal powder insulating particles. The manufacturing method comprises the following steps that S1, one or more of carbonyl iron powder, reduced iron powder, Fe-Si amorphous powder and Fe-Si-Cr amorphous powder are selected as metal soft magnetic materials; s2, mixing magnesium dichromate, phosphoric acid, urea, glycerol, sodium dodecyl benzene sulfonate and deionized water to prepare an insulating agent; and S3, taking the insulating agent, diluting the insulating agent with acetone, adding the metal soft magnetic powder into the diluted insulating agent, and stirring to a dry state. And S4, the mixture obtained in the S3 is over-dispersed and then dried in the shade to be baked, and primary processing powder is obtained. And S5, taking epoxy resin, diluting the epoxy resin with acetone, adding the diluted epoxy resin into the primary processing powder, stirring, drying in the shade, baking for primary curing, heating, and taking the baked powder as secondary processing powder. S6, zinc stearate is added into the secondary processing powder to serve as a lubricating agent; and uniformly mixing to obtain the soft magnetic metal powder insulating particles.

Description

Technical Field

[0001] The present invention relates to the technical field of soft magnetic alloy powders, and particularly to a method for manufacturing insulating particles of soft magnetic metal powders. Background Art

[0002] At present, as electronic devices continue to develop towards miniaturization and high performance, the performance requirements for magnetic components such as inductors are becoming increasingly stringent. Metal soft magnetic powder cores, as the key materials for manufacturing inductors, especially high-frequency, high-current, and high-power inductors, their performance directly determines the quality of the inductors. There are many factors affecting the performance of metal soft magnetic powder cores, among which the selection and treatment methods of insulating agents and binders play a crucial role.

[0003] Currently, common metal soft magnetic powder cores include iron powder cores, iron-nickel alloy powder cores, iron-nickel-molybdenum alloy powder cores, iron-silicon-aluminum alloy powder cores, etc. In actual production, usually, soft magnetic alloy powders are mixed evenly with insulating agents and binders and then pressed into shape, and finally obtained the final product through heat treatment. However, there are many drawbacks in the use of insulating agents and binders in the prior art. For example, although some insulating binders can increase the resistivity of the powder core, enhance the internal air gap of the powder core, improve the high-frequency characteristics and reduce the power loss, with the increase of their addition amount, the air gap rate inside the powder core rises, the magnetic permeability decreases, and then the power density of the magnetic core decreases. The "manufacturing method of iron-silicon-aluminum magnetic powder cores" disclosed in Japanese Patent Laid-Open No. 9-74011 and No. 9-125108, although its insulating binder has a relatively wide range of applicable magnetic powders and relatively stable performance, and can improve the quality factor of the magnetic core to a certain extent, the uniformity of the formed silicon dioxide surface film layer is difficult to guarantee, resulting in poor performance stability of the magnetic core and unable to meet the requirements of high-end electronic devices for the performance consistency and reliability of magnetic components; Chinese Patent CN1164709C discloses a "preparation of insulating binder for metal magnetic powder cores", which is characterized in that the insulating binder is composed of chromic anhydride, mica, tetraethyl orthosilicate, and silicone resin diluted and mixed with organic solvents. This insulating binder has a wide range of applicable magnetic powders, stable performance, and can significantly improve the quality factor of the magnetic core, but the uniformity of the formed silicon dioxide surface film layer is difficult to guarantee, so the performance stability of its magnetic core is poor.

[0004] In summary, it is of great practical significance and market demand to develop a manufacturing method of insulating particles of soft magnetic metal powders that can effectively improve the performance of metal soft magnetic powder cores, especially significantly improve in terms of insulation performance, magnetic permeability retention, and overall performance stability. Summary of the Invention

[0005] Based on this, it is necessary to provide a method for manufacturing insulating particles of soft magnetic metal powders in view of the above problems, including the following steps:

[0006] S1: Select one or more of carbonyl iron powder, reduced iron powder, Fe-Si, and Fe-Si-Cr amorphous powder as the soft magnetic metal material;

[0007] S2: Mix magnesium dichromate, phosphoric acid, urea, glycerol, sodium dodecylbenzenesulfonate with deionized water to prepare the insulating agent;

[0008] S3: Take the above insulating agent, with the addition amount being 5%-10% of the weight of the soft magnetic metal powder, dilute it with acetone, and the addition amount of acetone is 5%-8% of the weight of the soft magnetic metal powder. Add the soft magnetic metal powder to the diluted insulating agent and stir until it is in a dry state.

[0009] S4: Pass the mixture in S3 through an 80-mesh sieve to disperse the powder, then dry it in a shaded place for 45 minutes in an environment with a humidity of 40%-50% and a temperature of 25°C, and finally bake it at 100°C for 120 minutes to obtain the primary processed powder.

[0010] S5: Take epoxy resin, with the addition amount being 2%-8% of the weight of the soft magnetic metal powder; dilute the epoxy resin with acetone, and the addition amount of acetone is 5%-8% of the weight of the soft magnetic metal powder; add the diluted epoxy resin to the primary processed powder, stir at room temperature and pass through a 50-mesh sieve for granulation. After drying in a shaded place for 45 minutes, first bake it at 80°C for 30 minutes for preliminary curing, then raise the temperature to 100°C and bake for 60 minutes. Take the powder after baking with a mesh size of 50-200 as the secondary processed powder.

[0011] S6: Add zinc stearate as a lubricant to the secondary processed powder, and the dosage of zinc stearate is 0.1%-0.2% of the weight of the soft magnetic metal powder; add zinc stearate by spray method and mix evenly to obtain the insulated particles of the soft magnetic metal powder.

[0012] In one of the embodiments, in S2, each component of the insulating agent is calculated by weight percentage, including 4.00% magnesium dichromate, 5.00% phosphoric acid, 2.50% urea, 3.80% glycerol, 0.50% sodium dodecylbenzenesulfonate, and 50% deionized water.

[0013] In one of the embodiments, in S5, the selected resin is the two-component thermosetting epoxy resin 106A and 106B, and the ratio of the addition of 106A and 106B is 3:1.

[0014] In one of the embodiments, in S5, after adding the diluted epoxy resin to the primary processed powder, the stirring speed is 200-300 revolutions per minute, and the stirring time is 30-40 minutes.

[0015] In one embodiment, during the powder making process, if Fe-Si-Cr powder is used, it needs to go through a specific pretreatment process, including ball milling under the protection of inert gas, with a ball-to-material ratio of (3-5):1 and a ball milling time of 2-4 hours.

[0016] In one embodiment, in S3, the stirring speed is controlled at 300-500 revolutions per minute.

[0017] In one embodiment, after the granulation step, the secondary processed powder is subjected to magnetic field orientation treatment, with a magnetic field intensity of 500-800 oersteds and a treatment time of 10-20 minutes.

[0018] In one embodiment, in S6, zinc stearate is added by the spray method and stirred for 15-20 minutes at a stirring speed of 100-180 revolutions per minute.

[0019] In one embodiment, the prepared soft magnetic metal powder insulating particles are applied to the production of accessories for metal soft magnetic series products such as integrated molded inductors, metal powder cores, R rods, E / I-Cores, etc.

[0020] Beneficial effects:

[0021] 1: The power inductors produced by the manufacturing method of the present invention exhibit excellent performance, with remarkable characteristics of high saturation, large current, and low eddy current loss. Compared with traditional inductors, the present invention has been comprehensively improved from material selection to process optimization, greatly enhancing the stability of product characteristics, ensuring the consistency of product performance under different working conditions, and improving the market competitiveness of the product.

[0022] 2: The present invention cleverly utilizes the strong oxidizing property of Cr 6+ ions to successfully construct a uniform passivation film on the surface of metal powder particles. This innovative insulation method effectively achieves the insulation effect between metal particles. Compared with traditional insulation methods, the insulation film of the present invention is more uniform and stable, can effectively reduce the loss of magnetic permeability, and improve the overall performance of the powder core.

[0023] 3: The prepared magnetic core has good high-temperature resistance characteristics and can withstand a maximum temperature of 200 °C during the subsequent processing of the product. This characteristic enables the magnetic core to adapt to various production processes of conventional inductor products, such as high-temperature welding, heat treatment, etc. At the same time, the good high-temperature resistance performance is beneficial for the magnetic core to fully release internal stress during annealing, reduce hysteresis loss, further optimize product performance, and improve the reliability and stability of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the overall process flow chart of the present invention;

[0025] Figure 2 Schematic diagram of powder particles after coating;

[0026] Figure 3 Comparison chart of saturation magnetic induction intensity among Examples 1-4;

[0027] Figure 4 Comparison chart of magnetic permeability among Examples 1-4;

[0028] Figure 5 Comparison chart of power loss among Examples 1-4;

[0029] Figure 6 Comparison chart of insulation resistance among Examples 1-4;

[0030] Figure 7 Comparison chart of compressive strength among Examples 1-4;

[0031] Figure 8 Comparison chart of magnetic permeability change rate after aging among Examples 1-4.

[0032] 1. Iron powder particles; 2. Insulating film; 3. Adhesive layer. Detailed implementation manners

[0033] To make the above objects, features and advantages of the present invention more apparent and understandable, the following provides a detailed description of the specific implementation manners of the present invention. Many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0034] As used herein, the term "prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing" or any other variation thereof used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article or device containing the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article or device.

[0035] When an equivalent, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values and lower preferred values, this should be understood to specifically disclose all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, whether or not such ranges are separately disclosed. For example, when the range "1 to 5" is disclosed, the described range should be interpreted to include ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise specified, the range is intended to include its end values and all integers and fractions within the range.

[0036] Furthermore, the indefinite articles "a" and "an" before elements or components of the present invention do not limit the quantity requirements (i.e., the number of occurrences) of the elements or components. Therefore, "a" or "an" should be interpreted to include one or at least one, and elements or components in the singular form also include the plural form, unless the quantity clearly refers to the singular form.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this invention belongs. The terms used in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0038] S1: Select one or more of carbonyl iron powder, reduced iron powder, Fe-Si, and Fe-Si-Cr amorphous powder as the metal soft magnetic material; in S1, when high magnetic permeability is required, carbonyl iron powder is preferably selected; if the high-frequency performance needs to be improved, Fe-Si-Cr amorphous powder is preferably selected; it can also be mixed according to requirements. For example, when manufacturing a high-frequency inductor, 70% of Fe-Si-Cr amorphous powder and 30% of reduced iron powder are mixed.

[0039] S2: Mix magnesium dichromate, phosphoric acid, urea, glycerol, sodium dodecylbenzenesulfonate, and deionized water to prepare an insulating agent; in S2, for metal soft magnetic powder with a large specific surface area, the addition amount of the insulating agent can be close to 10%, and the addition amount of acetone is 8%; when manufacturing a high-power inductor, the addition amount of epoxy resin can be increased to 8%.

[0040] S3: Take the above insulating agent, with an addition amount of 5%-10% of the weight of the metal soft magnetic powder, dilute it with acetone, and the addition amount of acetone is 5%-8% of the weight of the metal soft magnetic powder. Add the metal soft magnetic powder to the diluted insulating agent and stir until it is in a dry state.

[0041] S4: Pass the mixture from S3 through an 80-mesh sieve to disperse the powder, then air-dry it for 45 min in an environment with a humidity of 40 - 50% and a temperature of 25°C, and finally bake it at 100°C for 120 min to obtain the primary processed powder.

[0042] S5: Take epoxy resin, with an addition amount of 2% - 8% of the weight of the metal soft magnetic powder; dilute the epoxy resin with acetone, with the addition amount of acetone being 5% - 8% of the weight of the metal soft magnetic powder; add the diluted epoxy resin to the primary processed powder, stir at room temperature and pass through a 50-mesh sieve for granulation, air-dry for 45 min, first bake at 80°C for 30 minutes for preliminary curing, then raise the temperature to 100°C and bake for 60 min, and take the powder after baking with a mesh size of 50 - 200 as the secondary processed powder.

[0043] S6: Add zinc stearate as a lubricant to the secondary processed powder, with the dosage of zinc stearate being 0.1% - 0.2% of the weight of the metal soft magnetic powder; add zinc stearate by the spray method and mix evenly to obtain the insulated particles of the soft magnetic metal powder.

[0044] In one of the embodiments, in S2, by weight percentage, the components of the insulating agent include 4.00% magnesium dichromate, 5.00% phosphoric acid, 2.50% urea, 3.80% glycerol, 0.50% sodium dodecylbenzenesulfonate, and 50% deionized water.

[0045] In one of the embodiments, in S5, the selected resin is the two-component thermosetting epoxy resin 106A and 106B; and the addition ratio of 106A and 106B is 3:1, and the addition amount of this epoxy resin is adjusted between 2% - 8% according to the requirements of the product for strength and insulation performance.

[0046] In one of the embodiments, in S5, after adding the diluted epoxy resin to the primary processed powder, the stirring speed is 200 - 300 revolutions per minute, and the stirring time is 30 - 40 minutes.

[0047] Furthermore, during the powder making process, if Fe-Si-Cr powder is used, it needs to go through a specific pretreatment process, including ball milling under inert gas protection, with a ball-to-material ratio of (3 - 5):1 and a ball milling time of 2 - 4 hours; optimize the powder particle size distribution and crystal structure through ball milling to improve the magnetic properties of the product.

[0048] In addition, the ball milling treatment is as follows:

[0049] Preparation: Select a suitable ball mill, such as a planetary ball mill, a drum ball mill, etc. According to the requirements of the ball milling process, prepare grinding balls of corresponding materials and specifications. Common materials include zirconia, stainless steel, etc. Put the Fe-Si-Cr powder into a clean and dry ball mill tank. According to the requirement of the ball-to-material ratio (3 - 5):1, accurately weigh an appropriate amount of grinding balls and put them into the ball mill tank. For example, if 100 g of Fe-Si-Cr powder is put in, according to the ball-to-material ratio of 4:1, 400 g of grinding balls need to be added. At the same time, prepare inert gases such as argon (Ar), nitrogen (N2), etc., as well as a gas delivery device, a gas purity detection device, and a sealing device for the ball mill.

[0050] Sealing of the ball mill tank and gas replacement: Firmly install the ball mill tank on the ball mill to ensure good sealing and prevent external air from entering. Connect the inert gas delivery pipeline to the ball mill tank, open the gas valve, and introduce the inert gas at a large flow rate to replace the air in the ball mill tank. During the replacement process, use the gas purity detection device to monitor the gas purity in the ball mill tank in real time. When the oxygen content is lower than 0.1%, it can be considered that the replacement is completed, and then close the gas valve.

[0051] Ball milling treatment: Set the operating parameters of the ball mill. According to the characteristics of the Fe-Si-Cr powder and the process requirements, control the ball milling time within 2 - 4 hours. Start the ball mill, and the ball mill begins to run. The grinding balls continuously impact and grind the Fe-Si-Cr powder in the tank, making its particle size finer and the distribution more uniform, and at the same time optimizing the crystal structure. During the ball milling process, closely monitor the operating state of the ball mill, such as temperature, noise, etc., to ensure the stable progress of the ball milling process. If the operating temperature of the ball mill is too high, the rotation speed can be appropriately reduced or the ball milling can be paused, and then continue after the temperature drops.

[0052] Subsequent treatment: After the ball milling is completed, first turn off the ball mill and continue to introduce the inert gas to keep the positive pressure in the ball mill tank to prevent air from entering. After the ball mill tank cools down to room temperature, transfer the milled powder to a sealed container for storage under the protection of the inert gas.

[0053] Further, in S3, the stirring speed is controlled at 300 - 500 revolutions per minute. Ensure that all components are fully mixed to form a uniform and stable insulating agent system, and improve the coating effect of the insulating film on the surface of the metal powder.

[0054] Further, after the granulation step, perform a magnetic orientation treatment on the secondary processed powder. The magnetic field strength is 500 - 800 oersteds, and the treatment time is 10 - 20 minutes. Through the magnetic orientation treatment, the magnetic domains inside the powder are arranged more orderly, enhancing the magnetic permeability and magnetic anisotropy of the product to meet the requirements of specific electromagnetic application scenarios.

[0055] During processing, the powder is evenly spread out in a special container, which is placed in a uniform magnetic field generated by an electromagnet or a superconducting magnet, allowing the powder magnetic domains to be arranged orderly under the action of the magnetic field. After processing, the magnetic permeability and magnetic anisotropy of the product can be enhanced, improving the product performance and meeting the requirements of specific electromagnetic application scenarios.

[0056] Further, in S6, zinc stearate is added by the spray method and stirred for 15 - 20 minutes at a stirring speed of 100 - 180 revolutions per minute; the method of adding zinc stearate by the spray method ensures that zinc stearate uniformly covers the surface of the secondary processed powder, avoiding particle agglomeration and breakage, and improving the product forming quality;

[0057] The spray method can make zinc stearate uniformly cover the surface of the secondary processed powder particles in the form of tiny droplets. Compared with other addition methods, it avoids the problem of local agglomeration of zinc stearate, making the lubricant more evenly distributed in the powder. In actual production, if the traditional addition method is used, there may be a situation where the concentration of zinc stearate is too high in some areas and insufficient in some areas, affecting the fluidity and forming performance of the powder. The spray method can ensure that each powder particle is evenly attached with zinc stearate. For example, when making metal powder cores, it can make the powder fill more evenly in the mold, improving the consistency of product quality.

[0058] In one of the embodiments, the prepared soft magnetic metal powder insulating particles are applied to the production of accessories for metal soft magnetic series products such as integrated molded inductors, metal powder cores, R rods, E / I-Cores, etc.

[0059] Example 1

[0060] S1: Select Fe-Si-Cr amorphous powder as the metal soft magnetic material, which has low hysteresis loss and high magnetic permeability at high frequencies and is suitable for the production of high-frequency inductors.

[0061] S2: Prepare the insulating agent strictly according to the above formula. Each component is calculated by weight percentage, including 4.00% magnesium dichromate, 5.00% phosphoric acid, 2.50% urea, 3.80% glycerol, 0.50% sodium dodecylbenzenesulfonate, and 50% deionized water.

[0062] S3: Take the insulating agent, and the addition amount is 6% of the weight of the metal soft magnetic powder. The addition amount of acetone is 6% of the weight of the metal soft magnetic powder. The stirring speed is controlled at 400 revolutions per minute and stirred until it is in a dry state.

[0063] S4: Pass the mixture through an 80-mesh sieve to disperse the powder, dry it in a shaded place for 45 minutes in an environment with a humidity of 45% and a temperature of 25°C, and then bake it at 100°C for 120 minutes to obtain the primary processed powder.

[0064] S5: Select the two-component thermosetting epoxy resin 106A and 106B, with an addition amount of 5% of the weight of the metal soft magnetic powder, and the ratio of the addition amounts of 106A and 106B being 3:1. The addition amount of acetone is 6% of the weight of the metal soft magnetic powder. The stirring speed is 250 revolutions per minute, and the stirring time is 35 minutes. Granulate through a 50-mesh sieve, air-dry for 45 min, first bake at 80 °C for 30 minutes, then raise the temperature to 100 °C and bake for 60 min. Take the baked powder with a particle size of 50 - 200 meshes as the secondary processing powder.

[0065] S6: Add zinc stearate, with a dosage of 0.15% of the weight of the metal soft magnetic powder. Add zinc stearate by the spray method, and stir at a stirring speed of 150 revolutions per minute for 18 minutes to obtain insulated particles of soft magnetic metal powder. Press them into standard T-90 magnetic rings, and wind 20 Ts with φ0.6 mm enameled wire.

[0066] Example 2

[0067] S1: The same as in Example 1, select Fe-Si-Cr amorphous powder.

[0068] S2: Use the traditional insulating agent formula, with the main component being common organic insulating materials. The addition amount and acetone dilution ratio are the same as in Example 1.

[0069] S3: During the processing, due to the limitations of the traditional insulating agent components, a uniform passivation film cannot be formed on the surface of the metal powder. The stirring speed is the same as in Example 1, and stir until it is in a dry state.

[0070] S4: After the same dispersion, air-drying, and baking steps, obtain the primary processed powder.

[0071] S5: Perform granulation operations using the same epoxy resin, addition amount, and acetone dilution amount as in Example 1. However, due to the difference in the insulation performance of the primary processed powder, during the stirring process, the bonding effect between the epoxy resin and the powder is not as good as that in Example 1. The stirring speed and time are the same as in Example 1. After granulation, air-drying, and baking, take the powder with the same mesh number as the secondary processing powder.

[0072] S6: Add the same proportion of zinc stearate, use the traditional addition method and stir to obtain the insulated particles of soft magnetic metal powder for comparison, and make magnetic rings of the same specification.

[0073] Example 3

[0074] S1: Select carbonyl iron powder as the metal soft magnetic material, which is suitable for low-frequency inductors with high requirements for magnetic permeability.

[0075] Insulating agent preparation S2: Prepare the insulating agent according to the invention formula.

[0076] Insulating agent treatment S3: Adjust the addition amount of the insulating agent to 4% of the weight of the metal soft magnetic powder, and the addition amount of acetone is 5% of the weight of the metal soft magnetic powder. Control the stirring speed at 350 revolutions per minute and stir until dry.

[0077] S4: Obtain the primary processed powder according to the conventional steps.

[0078] S5: Select the two-component thermosetting epoxy resin 106A and 106B, with the addition amount adjusted to 3% of the weight of the metal soft magnetic powder, and the addition amount of acetone is 5% of the weight of the metal soft magnetic powder. The stirring speed is 220 revolutions per minute and the stirring time is 32 minutes. After steps such as granulation, air drying and baking, take the powder after baking with a mesh size of 50 - 200 as the secondary processed powder.

[0079] S6: Add zinc stearate, with the dosage being 0.1% of the weight of the metal soft magnetic powder. Add zinc stearate by the spray method and stir for 16 minutes at a stirring speed of 120 revolutions per minute to mix evenly to obtain the insulated particles of the soft magnetic metal powder, and make standard magnetic rings.

[0080] Example 4

[0081] S1: Select reduced iron powder as the metal soft magnetic material, which has the characteristics of lower cost and better magnetism.

[0082] S2: Prepare the insulating agent according to the invention formula.

[0083] S3: The addition amount of the insulating agent is 8% of the weight of the metal soft magnetic powder, and the addition amount of acetone is 7% of the weight of the metal soft magnetic powder. Control the stirring speed at 450 revolutions per minute and stir until dry.

[0084] S4: Obtain the primary processed powder according to the conventional steps.

[0085] S5: Select the two-component thermosetting epoxy resin 106A and 106B, with the addition amount adjusted to 7% of the weight of the metal soft magnetic powder, and the addition amount of acetone is 7% of the weight of the metal soft magnetic powder. The stirring speed is 280 revolutions per minute and the stirring time is 38 minutes. During the granulation process, appropriately adjust the stirring speed and time to ensure that the epoxy resin evenly coats the powder. After air drying and baking, take the powder after baking with a mesh size of 50 - 200 as the secondary processed powder.

[0086] S6: Add zinc stearate, with the dosage being 0.2% of the weight of the metal soft magnetic powder. Add zinc stearate by the spray method and stir for 18 minutes at a stirring speed of 160 revolutions per minute to mix evenly to obtain the insulated particles of the soft magnetic metal powder, and make standard magnetic rings.

[0087]

[0088]

[0089] It can be clearly seen from the data comparison that:

[0090] Saturation magnetic induction intensity: Example 1 shows the best performance, reaching 1.25 T. Example 2 is relatively lower, only 1.10 T. The saturation magnetic induction intensities of Example 3 and Example 4 are also better than that of Example 2, being 1.20 T and 1.22 T respectively. This indicates that the manufacturing method of the present invention can effectively improve the saturation magnetic induction intensity of the magnetic core, enabling it to have better performance in a high magnetic field environment. In Example 2, due to the use of a traditional insulating agent, the magnetic potential of the metal powder cannot be fully exerted, resulting in a relatively low saturation magnetic induction intensity.

[0091] Magnetic permeability: The magnetic permeability of Example 1 is 80, significantly higher than 65 of Example 2. The magnetic permeabilities of Example 3 and Example 4 are 70 and 75 respectively, also reflecting the advantage of the manufacturing method of the present invention in maintaining the magnetic permeability. During the insulation treatment process of the traditional process, a large loss of magnetic permeability occurred, while the present invention reduces the negative impact on the magnetic permeability by optimizing the insulating agent formula and process.

[0092] Power loss: Power loss is directly related to the energy utilization efficiency of the inductor. The power loss of Example 1 is 120 kW / m at 100 kHz 3 , significantly lower than 150 kW / m of Example 2 3 . The power losses of Example 3 and Example 4 are also relatively low, being 130 kW / m 3 and 125 kW / m 3 respectively. This shows that the magnetic core manufactured by the present invention can effectively reduce the power loss at high frequencies, improve the energy utilization efficiency, and reduce energy waste.

[0093] Insulation resistance: Insulation resistance reflects the insulation performance of the magnetic core. The insulation resistance of Example 1 reaches 500 MΩ, much higher than 300 MΩ of Example 2. The insulation resistances of Example 3 and Example 4 are 400 MΩ and 450 MΩ respectively, also better than that of Example 2. The present invention uses the passivation film formed by Cr 6+ ions and subsequent insulation treatment process to effectively improve the insulation performance of the magnetic core, ensuring the safety and stability of the inductor during operation.

[0094] Compressive strength: Compressive strength reflects the mechanical properties of the magnetic core. The compressive strength of Example 1 is 80 MPa, significantly higher than 65 MPa of Example 2. The compressive strengths of Example 3 and Example 4 are 70 MPa and 75 MPa respectively, also better than that of Example 2. This indicates that the magnetic core manufactured by the present invention is more reliable in terms of mechanical properties, can withstand greater pressure, and is not prone to deformation or damage.

[0095] Magnetic permeability change rate after aging: The magnetic permeability change rate after aging is an important indicator to measure the stability of the magnetic core. In Example 1, the magnetic permeability change rate after aging at 180°C for 500 h is only 5%, while in Example 2 it is as high as 15%. The magnetic permeability change rates after aging in Example 3 and Example 4 are 8% and 6% respectively, both lower than that in Example 2. This fully demonstrates that the magnetic core manufactured by the present invention has better stability, can maintain relatively stable magnetic properties in a high-temperature aging environment, and extends the service life of the product.

[0096] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0097] The above-described embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. A method for manufacturing insulated particles of soft magnetic metal powder, characterized in that, It includes the following steps: S1: Select one or more of carbonyl iron powder, reduced iron powder, Fe-Si, and Fe-Si-Cr amorphous powder as the soft magnetic metal material; S2: Mix magnesium dichromate, phosphoric acid, urea, glycerol, sodium dodecylbenzenesulfonate and deionized water to prepare an insulating agent; S3: Take the above insulating agent, with an addition amount of 5%-10% of the weight of the soft magnetic metal powder, dilute it with acetone, and the addition amount of acetone is 5%-8% of the weight of the soft magnetic metal powder. Add the soft magnetic metal powder to the diluted insulating agent and stir until it is in a dry state. S4: Pass the mixture of S3 through an 80-mesh sieve to disperse the powder, then dry it in a shaded place for 45 min in an environment with a humidity of 40%-50% and a temperature of 25 °C, and finally bake it at 100 °C for 120 min to obtain the primary processed powder. S5: Take epoxy resin, with an addition amount of 2%-8% of the weight of the soft magnetic metal powder; dilute the epoxy resin with acetone, and the addition amount of acetone is 5%-8% of the weight of the soft magnetic metal powder; add the diluted epoxy resin to the primary processed powder, stir at room temperature and pass through a 50-mesh sieve for granulation. After drying in a shaded place for 45 min, first bake it at 80 °C for 30 minutes for preliminary curing, then raise the temperature to 100 °C and bake for 60 min. Take the powder after baking with a mesh size of 50-200 as the secondary processed powder. S6: Add zinc stearate as a lubricant to the secondary processed powder, and the amount of zinc stearate used is 0.1%-0.2% of the weight of the soft magnetic metal powder; add zinc stearate by spray method and mix evenly to obtain the insulated particles of soft magnetic metal powder.

2. The manufacturing method of the insulated particles of soft magnetic metal powder according to claim 1, characterized in that, In S2, each component of the insulating agent is calculated by weight percentage, including 4.00% magnesium dichromate, 5.00% phosphoric acid, 2.50% urea, 3.80% glycerol, 0.50% sodium dodecylbenzenesulfonate and 50% deionized water.

3. The manufacturing method of the insulated particles of soft magnetic metal powder according to claim 1, wherein The resin selected in S5 is the two-component thermosetting epoxy resin of 106A and 106B.

4. The manufacturing method of the insulated particles of soft magnetic metal powder according to claim 1, characterized in that, In S5, after adding the diluted epoxy resin to the primary processed powder, the stirring speed is 200-300 revolutions per minute, and the stirring time is 30-40 minutes.

5. The manufacturing method of the insulated particles of soft magnetic metal powder according to claim 1, characterized in that, During the powder making process, if Fe-Si-Cr powder is used, it needs to go through a specific pretreatment process, including ball milling under the protection of inert gas, with a ball-to-material ratio of (3-5):1 and a ball milling time of 2-4 hours.

6. The manufacturing method of the insulated particles of soft magnetic metal powder according to claim 1, characterized in that, In S3, the stirring speed is controlled at 300-500 revolutions per minute.

7. The manufacturing method of the insulated particles of soft magnetic metal powder according to claim 1, characterized in that, After the granulation step, perform magnetic field orientation treatment on the secondary processed powder, with a magnetic field strength of 500-800 oersteds and a treatment time of 10-20 minutes.

8. The manufacturing method of the insulated particles of soft magnetic metal powder according to claim 1, characterized in that, In S6, add zinc stearate by spray method and stir at a stirring speed of 100-180 revolutions per minute for 15-20 minutes.

9. The manufacturing method of the insulated particles of soft magnetic metal powder according to claim 1, characterized in that, The prepared insulated particles of soft magnetic metal powder are applied to the production of accessories for metal soft magnetic series products such as integrated molded inductors, metal powder cores, R rods, and E / I-Cores.

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