Soft magnetic granulation powder and preparation method thereof

Abstract

The invention relates to soft magnetic granulation powder and a preparation method thereof, belongs to the field of soft magnetic materials, and provides soft magnetic granulation powder with high magnetic conductivity and low loss. According to grading of Fe-based metal raw powder FeNi, FeSiAl and FeSi, one or more kinds of metal raw powder are mixed and then subjected to multi-step coating, and then the soft magnetic granulation powder with high magnetic conductivity and low loss is obtained; the phenomenon of low bonding force among particles caused by different materials, different particle sizes and different hardness can be effectively relieved; the magnetic conductivity of the prepared soft magnetic granulation powder reaches 100 kHz and the loss is as low as 160 mW * cm <-3 > (50 kHz, 100 mT) by controlling the proportion of the auxiliary material I, the auxiliary material II and the auxiliary material III and coating the auxiliary material I, the auxiliary material II and the auxiliary material III; and the coupling agent is used for treatment, so that the bonding property of a three-time coating layer interface of the soft magnetic granulation powder is enhanced, and the reliability of a granulation powder pressed product is improved.

Description

Technical Field

[0001] The invention belongs to the field of soft magnetic materials and relates to soft magnetic granulated powder and a preparation method thereof. Background Art

[0002] Soft magnetic materials are made by compressing magnetic powder coated with an insulating medium. They combine the characteristics of high saturation magnetic induction intensity and high magnetic permeability of metallic soft magnetic materials and high resistivity of soft ferrites, and can simultaneously meet the needs of high frequency (kHz-MHz) and miniaturization.

[0003] The first generation of magnetic powder cores: powder metallurgy sintered soft magnets, such as pure iron, iron phosphorus Fe-P, ferrosilicon Fe-Si, nickel iron Fe-Ni, iron cobalt Fe-Co, and stainless steel, have good magnetic properties in DC applications, but have high losses under high-frequency AC.

[0004] Second-generation magnetic powder cores include iron cores and carbonyl iron cores. Low-cost iron cores have low resistivity and relatively low losses only at low frequencies. Their magnetic permeability is μ = 10-100, and they are generally only used below 50kHz. Carbonyl iron cores, made from ultrafine iron powder, can operate in the medium- and high-frequency range of 100kHz to 100MHz. They have good DC bias characteristics, but their magnetic permeability is low, around μ = 10. Second-generation iron cores have a high magnetostriction coefficient and are not suitable for high-temperature conditions.

[0005] Third-generation powder cores: alloy powder cores, including: FeSiAl powder cores (Sendust Core), high-flux FeNi powder cores (High Flux Core), molybdenum permalloy FeNiMo powder cores (Mpp Core), and FeSi powder cores (X-fluxcore). High-flux FeNi powder cores, composed of 50% Fe and 50% Ni, offer a high saturation flux density (μM) of up to 1.5T, thus reducing the working volume. Their magnetic permeability (μM) ranges from 10 to 160, exhibits minimal temperature variation, low losses, and excellent DC bias characteristics, making them suitable for applications with more stringent requirements.

[0006] Metal powder coating methods include organic, inorganic, and organic-inorganic composite coating. Inorganic coating can increase the heat treatment temperature, which is beneficial for eliminating internal compression stress. It also has good chemical stability and high resistivity. However, the brittleness of single inorganic materials limits their maximum compression strength, making it difficult to obtain compacted magnetic powder cores with high density. Inorganic coating agents for magnetic powders mainly include phosphates, metal oxides, non-metallic oxides, and ferrites. Inorganic coating methods are generally divided into wet chemical and dry chemical methods. Among them, metal oxide coatings such as Fe2O3, SiO2, MgO, Al2O3, and TiO2 have high resistivity and good thermal stability, making them ideal insulating coating agents. The coating layer needs to have good insulation strength, high temperature resistance, and adhesion. Single inorganic coating has problems with adhesion and coating uniformity, while organic-inorganic composite coating can improve the adhesion between particles, as well as the insulation strength and high temperature resistance.

[0007] Organic coating can be categorized as using thermosetting or thermoplastic organic materials. Commonly used organic coating agents are primarily thermosetting polymers such as epoxy resins, polyester powders, polyurethane powders, and mixtures thereof. These can further enhance the integrity and insulation of the coating layer, thereby increasing Q and reducing losses. Excessive organic coating can reduce magnetic permeability due to magnetic dilution. Therefore, organic-inorganic composite coating requires a reasonable ratio and process to achieve high permeability and low loss. Summary of the Invention

[0008] The purpose of the present invention is to provide a method for preparing a soft magnetic granulated powder with high magnetic permeability and low loss for high-frequency miniaturized products.

[0009] To achieve the above object, the technical solution adopted by the present invention is as follows: Step 1: Mix FeNi and one or more FeSiAl and FeSi metal powders to obtain a mixed powder with a particle size of 5-50 μm and a FeNi content of ≥50%; stir and coat the metal powder with an acid solution, wherein the amount of the acid solution added accounts for 0.1 wt.%-0.3 wt.% of the metal powder, the stirring speed is 10-40 r / min, the stirring time is 10-30 minutes, and after stirring, the mixture is dried in a blast oven at 80-120° C. for 1-1.5 hours to obtain a coated powder.

[0010] Alternatively, FeNi metal raw powder is first added to an acid solution and stirred to perform a coating, and then the coated FeNi powder is mixed with FeSiAl and / or FeSi metal raw powder to obtain a mixed powder; The acid solution is made of one of phosphoric acid and oxalic acid, and the solvent is preferably ethanol; then the auxiliary material-solvent is added to the mixed original powder and stirred. Step 2: Prepare auxiliary material 2: Add one or more of Fe2O3, SiO2, MgO, Al2O3, and TiO2 precursors to a solvent, preferably a mixed solvent of water and ethanol (such as a mass ratio of 1:1), add the solvent for preparing auxiliary material 2 to the powder in step 1 and stir, the addition amount accounts for 0.5-1 wt.% of the metal original powder, the stirring speed is 10-40r / min, stirring for 10-30min, and after stirring, dry in a blast oven at 120-180℃ for 1-1.5 hours to obtain a secondary coated powder.

[0011] Step 3: Mix and stir the secondary coated powder with a coupling agent, wherein the coupling agent is preferably at least one of an aminosilane coupling agent, a fluorocarbon silane coupling agent, and an epoxy silane coupling agent. After stirring, dry the mixture in a blast oven at 60° C. for 1 hour to obtain a coupling agent-treated powder.

[0012] Step 4: Prepare auxiliary material three: prepare an organic solution of silicone resin, the solvent is preferably acetone, add the prepared auxiliary material three to the coupling agent treated powder and stir, the addition amount is preferably 0.3 wt.%-0.8 wt.% of the metal original powder, the stirring speed is 10-40r / min, and the stirring time is 10-30min to obtain a tertiary coated powder.

[0013] Step 5: The stirred three-times coated powder is granulated into 100-120 meshes using a double-roll granulator, crushed into 20-40 meshes after granulation, and dried in a blast oven at 60° C. for 1 hour to obtain a semi-finished soft magnetic granulated powder.

[0014] Step 6: Adding a release agent to the semi-finished soft magnetic granulated powder in an amount of 0.1 wt.% to 0.3 wt.% to obtain the final soft magnetic granulated powder. The release agent is one or more of lithium stearate, magnesium stearate, zinc stearate, aluminum stearate, and calcium stearate.

[0015] The beneficial effects of the present invention relative to the prior art are: (1) The present invention controls the ratio of auxiliary material 1, auxiliary material 2, and auxiliary material 3 and the coating steps to prepare a magnetic permeability of 100 (100kHz) and a loss as low as 160 mW*cm -3 (50kHz, 100mT) soft magnetic granulated powder.

[0016] (2) The present invention uses a coupling agent treatment to enhance the bonding properties of the interfaces of the three coating layers of the soft magnetic granulated powder and improve the reliability of the granulated powder pressed product.

[0017] (3) The present invention explores the grading of Fe-based metal raw powders FeNi, FeSiAl, and FeSi. One or more metal raw powders are first mixed and then coated in multiple steps, which can effectively reduce the phenomenon of low binding force between particles caused by different materials, particle sizes, and hardness. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The process flow of soft magnetic metal granulation powder of Example 1 Figure 1 ; Figure 2 The process flow of soft magnetic metal granulation powder of Example 2 Figure 2 . DETAILED DESCRIPTION

[0019] Example 1 The soft magnetic metal granulated powder of the present invention is specifically implemented according to the following steps: Step 1: Mix FeNi and FeSiAl raw powders, wherein the FeNi content is ≥50%.

[0020] Step 2: Prepare auxiliary material 1: phosphoric acid solution, the solvent is preferably ethanol, add the prepared auxiliary material 1 to the mixed original powder and stir, the addition amount is 0.1-0.2 wt.%, the stirring speed is 10-40r / min, stirring for 10-30min, and after stirring, dry in a blast oven at 80-120℃ for 1-1.5 hours to obtain a primary coated powder.

[0021] Step 3: Prepare auxiliary material 2: SiO2 precursor solution tetraethoxysilane, the solvent is preferably a mixed solvent of water and ethanol, add the prepared auxiliary material 2 to the primary coating powder and stir, the addition amount is preferably 0.5 wt.%-1 wt.%, the stirring speed is 10-40r / min, stirring for 10-30min, and after stirring, dry in a blast oven at 120-180℃ for 1-1.5 hours to obtain the secondary coating powder.

[0022] Step 4: Prepare auxiliary material three: an organic solution of silicone resin, preferably acetone as the solvent, add the prepared auxiliary material three to the secondary coating powder and stir, the addition amount is preferably 0.3 wt.%-0.8 wt.%, the stirring speed is 10-40r / min, and the stirring time is 10-30min to obtain the tertiary coating powder.

[0023] Step 5: The stirred three-times coated powder is granulated into 100-120 meshes using a double-roll granulator, crushed into 20-40 meshes after granulation, and dried in a blast oven at 60° C. for 1 hour to obtain a semi-finished soft magnetic granulated powder.

[0024] Step 8: Add a stearate release agent to the semi-finished soft magnetic granulation powder: one or more of lithium stearate, magnesium stearate, zinc stearate, aluminum stearate, and calcium stearate, and add 0.1 wt.%-0.3 wt.% to obtain the final soft magnetic granulation powder.

[0025] The magnetic permeability of the soft magnetic granulated powder prepared in Example 1 can reach 100-115 at 100KHz and 1V.

[0026] Example 2 The soft magnetic metal granulated powder of the present invention is specifically implemented according to the following steps: Step 1: Prepare auxiliary material 1: Prepare acid solution, the solvent is preferably ethanol.

[0027] Step 2: Add FeNi raw powder to auxiliary material 1 and stir, the addition amount is 0.1-0.2 wt.%, the stirring speed is 10-40r / min, and the stirring time is 10-30min. After stirring, dry in a blast oven at 80-120℃ for 1-1.5 hours to obtain a coated FeNi powder.

[0028] Step 3: Mix the primary coated FeNi powder with FeSiAl, wherein the content of the primary coated FeNi powder is ≥50%, to obtain a mixed powder.

[0029] Step 4: Mix the mixed powder with a coupling agent, preferably at least one of an aminosilane coupling agent, a fluorocarbon silane coupling agent, and an epoxy silane coupling agent, and then dry the mixed powder in a blast oven at 60° C. for 1 hour to obtain a coupling agent-treated powder.

[0030] Step 5: Prepare auxiliary material 2: an organic solution of silicone resin, preferably acetone as the solvent, add the prepared auxiliary material 2 to the coupling agent treated powder and stir, the addition amount is preferably 0.3 wt.%-0.8 wt.%, the stirring speed is 10-40r / min, and the stirring time is 10-30min to obtain a tertiary coated powder.

[0031] Step 6: The stirred three-times coated powder is granulated into 100-120 meshes using a double-roll granulator, crushed into 20-40 meshes after granulation, and dried in a blast oven at 60° C. for 1 hour to obtain a semi-finished soft magnetic granulated powder.

[0032] Step 7: Add a stearate release agent to the semi-finished soft magnetic granulation powder: one or more of lithium stearate, magnesium stearate, zinc stearate, aluminum stearate, and calcium stearate, and add 0.1 wt.%-0.3 wt.% to obtain the final soft magnetic granulation powder.

[0033] The magnetic permeability of the soft magnetic granulated powder prepared in Example 2 can reach 110 at 100 KHz and 1 V.

Claims

1. A method for preparing soft magnetic granulated powder, characterized in that: The preparation method comprises the following steps: Step 1: FeNi and one or two of FeSiAl and FeSi metal powders are mixed to obtain a mixed powder, wherein the FeNi content is ≥50%, and then the metal powder and acid solution are stirred and coated, the amount of acid solution added is 0.1wt.%-0.3wt.% of the metal powder, the stirring speed is 10-40r / min, and after stirring, it is dried in a blast oven at 80-120℃ for 1-1.5 hours to obtain a primary coated powder; Alternatively, FeNi metal raw powder is first added to an acid solution and stirred for coating, and then the coated FeNi powder is mixed with FeSiAl and / or FeSi metal raw powder, wherein the FeNi content is ≥50%, to obtain a mixed powder; Step 2: preparing auxiliary material 2: adding one or more of Fe2O3, SiO2, MgO, Al2O3, and TiO2 precursors into a solvent, wherein the solvent is a mixed solvent of water and ethanol, to obtain a solvent for preparing auxiliary material 2; Add the solvent of the second auxiliary material to the powder of step 1 and stir, the amount of the solvent added is 0.5-1wt% of the original metal powder, and then dry at 120-180℃ for 1-1.5 hours to obtain the secondary coated powder; Step 3: Mix the secondary coated powder and the coupling agent, stir, and then dry in a blast oven at 60°C for 1 hour to obtain a coupling agent-treated powder; Step 4: Prepare auxiliary material 3: Prepare an organic solution of silicone resin to obtain auxiliary material 3 solution; add auxiliary material 3 solution to the coupling agent treated powder and stir, the addition amount accounts for 0.3-0.8wt% of the original metal powder to obtain a tertiary coated powder; Step 5: The stirred three-coated powder is granulated into 100-120 meshes using a double-roll granulator, crushed into 20-40 meshes after granulation, and dried in a blast oven at 60°C for 1 hour to obtain a semi-finished soft magnetic granulated powder; Step 6: Add a release agent to the semi-finished soft magnetic granulated powder in an amount of 0.1-0.3wt% to obtain the final soft magnetic granulated powder.

2. The method for preparing the soft magnetic granulated powder according to claim 1, wherein The acid solution described in step 1 is made from one of phosphoric acid and oxalic acid.

3. The method for preparing the soft magnetic granulated powder according to claim 1, wherein The coupling agent in step 3 is preferably one or more of an aminosilane coupling agent, a fluorocarbon silane coupling agent, and an epoxy silane coupling agent.

4. The method for preparing the soft magnetic granulated powder according to claim 1, wherein In step six, the release agent is one or more of lithium stearate, magnesium stearate, zinc stearate, aluminum stearate, and calcium stearate.

5. A soft magnetic granulated powder, characterized in that: The soft magnetic granulated powder is manufactured by the preparation method according to any one of claims 1 to 4.

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