Iron-silicon magnetic powder inductance material and preparation method thereof

Abstract

The invention relates to the technical field of iron-silicon magnetic powder inductance processing, in particular to an iron-silicon magnetic powder inductance material and a preparation method thereof.The iron-silicon magnetic powder inductance material is prepared from, by weight, iron-silicon alloy, a composite insulation coating agent, a surfactant, ferric nitrate, citric acid and an adhesive solution; the preparation method comprises the following steps: ultrasonically dispersing phosphate and n-type semiconductor oxide nano powder in ethanol, adding a silane coupling agent, adjusting the pH value to 4.0-5.5, reacting at 60-80 DEG C for 2-4 hours, filtering and drying to obtain the composite insulating coating agent, the iron-silicon magnetic powder inductance material prepared through the method solves the key technical problems that iron-silicon magnetic powder is large in loss, low in magnetic conductivity and poor in design flexibility, the high-frequency performance and reliability are improved, and the urgent requirements for high frequency, miniaturization and high efficiency of power inductors in the fields of consumer electronics, new energy automobiles, 5G communication and the like are met.

Description

A Ferrosilicon Powder Inductor Material and Its Preparation Method Technical Field

[0001] This application relates to the field of iron-silicon magnetic powder inductor processing technology, and more specifically, to an iron-silicon magnetic powder inductor material and its preparation method. Background Technology

[0002] In recent years, with the rapid development of consumer electronics, new energy vehicles, 5G communications, and other industries, electronic devices are evolving towards miniaturization, higher frequency, and higher current. Molded inductors, as core components of modules such as switching power supplies, DC-DC converters, and filter circuits, directly affect the power conversion efficiency and stability of the entire system. These components are manufactured using a process of pressing a mixture of soft magnetic metal powder and insulating materials, resulting in advantages such as compact structure, excellent DC bias characteristics, and strong electromagnetic interference resistance. This has made it the mainstream technology for power inductors.

[0003] In the soft magnetic metal powder material system, iron-silicon magnetic powder has become one of the mainstream core materials for low- and medium-frequency integrated inductors due to its advantages such as low raw material cost, high saturation magnetic flux density, and good molding processability. In particular, its excellent DC superposition characteristics can meet the application requirements of high-current operating environments, occupying an important market share in servers, industrial power supplies, and other fields. However, as the application frequency expands to the megahertz level and energy efficiency standards become increasingly stringent, the performance bottleneck of traditional iron-silicon magnetic powder materials is becoming increasingly prominent, limiting its application expansion in high-end scenarios.

[0004] Compared to high-performance magnetic powder cores such as iron-silicon-aluminum and iron-nickel-molybdenum, traditional iron-silicon magnetic powder cores exhibit relatively high core losses. Under high-frequency alternating magnetic fields, its volumetric losses are significantly higher than similar materials, directly leading to increased temperature rise and decreased energy conversion efficiency in integrated inductors during operation. This deficiency is particularly pronounced in applications with extremely stringent energy efficiency requirements, such as aerospace and high-efficiency server power supplies. Furthermore, the chemical composition of iron-silicon magnetic powder is predominantly iron, comprising approximately 94% by mass, resulting in generally low intrinsic resistivity. This low resistivity makes it easy for the powder particles to form microscopic eddy current paths in alternating magnetic fields, especially at high frequencies, where the skin effect and proximity effect are significantly enhanced, leading to a sharp increase in eddy current losses. Although existing technologies can improve interparticle insulation resistance to some extent through insulation treatments such as phosphoric acid passivation and resin coating, the overall resistivity remains difficult to achieve ideal levels due to the intrinsic characteristics of the substrate material, and the problem of quality factor (Q) degradation at high frequencies remains unresolved.

[0005] Furthermore, the effective permeability of iron-silicon magnetic powder cores is low, significantly lower than that of iron-nickel-molybdenum and iron-silicon-aluminum magnetic powder cores. This limited permeability adjustment range restricts the range of parameters available to design engineers when matching inductance, making it difficult to simultaneously achieve multiple design goals such as high inductance, high DC bias capability, and low loss. Especially in miniaturized integrated inductor designs requiring high inductance, the only options are often to increase the number of coil turns or enlarge the core size, which contradicts the trend towards thinner and lighter electronic products. Summary of the Invention

[0006] To address the issues of high loss and low permeability of iron-silicon magnetic powder, this application provides an iron-silicon magnetic powder inductor material and its preparation method.

[0007] In a first aspect, this application provides an iron-silicon magnetic powder inductor material, which adopts the following technical solution: An iron-silicon magnetic powder inductor material is prepared from the following raw materials in parts by weight: 80-95 parts iron-silicon alloy, 1-3 parts composite insulating coating agent, 1-2 parts surfactant, 0.1-0.5 parts ferric nitrate, 0.05-0.1 parts citric acid, and 10-15 parts binder solution; the composite insulating coating agent is prepared by the following method: according to the weight, 0.5-1 parts phosphate and 0.3-1.5 parts n-type semiconductor oxide nanoparticles are ultrasonically dispersed in ethanol, 0.05-0.2 parts silane coupling agent are added, the pH is adjusted to 4.0-5.5, the reaction is carried out at 60-80℃ for 2-4 hours, filtered, and dried to obtain the composite insulating coating agent.

[0008] By employing the above technical solution, a high-resistivity nanocomposite insulating layer is formed on the surface of iron-silicon alloy particles through a composite insulating coating agent synergistically constructed from phosphate and n-type semiconductor oxide nanoparticles. This significantly increases the resistivity of the iron-silicon magnetic powder inductor material, effectively cutting off the microscopic eddy current path at megahertz high frequencies. This greatly reduces core loss, effectively suppresses the temperature rise of the integrated inductor, and significantly improves energy conversion efficiency, solving the energy efficiency bottleneck and Q-value decay problem in demanding scenarios such as aerospace and high-efficiency server power supplies. Simultaneously, ferric nitrate and citric acid generate an iron oxide nanofilm through a sol-gel reaction, synergistically regulating the magnetic anisotropy of the magnetic powder surface. While maintaining the high saturation magnetic flux density advantage of iron-silicon alloys, this effectively breaks through the narrow range of permeability (26-90) of traditional iron-silicon magnetic powder cores, expanding the effective permeability from the traditional 26-90 to 90-130. This allows engineers to achieve multi-objective synergistic optimization of high inductance, high DC bias capability, and low loss without increasing the number of coil turns or expanding the core volume, aligning with the trend towards thinner and lighter electronic products.

[0009] Furthermore, the surfactant improves the wetting and dispersibility of the magnetic powder and binder, resulting in better processability and higher yield of the mixed slurry during molding, and high compatibility with existing monolithic inductor production lines. In summary, this solution systematically solves the key technical problems of high loss, low permeability, and poor design flexibility of iron-silicon magnetic powder, improving high-frequency performance and reliability, and meeting the urgent needs of consumer electronics, new energy vehicles, 5G communications, and other fields for high-frequency, miniaturized, and high-efficiency power inductors.

[0010] Preferably, the n-type semiconductor oxide is at least one of tin-doped antimony trioxide, aluminum-doped zinc oxide, or indium-doped tin oxide.

[0011] The aforementioned n-type semiconductor oxides can construct a semiconductor insulating layer with precisely controllable carrier concentration on the surface of iron-silicon magnetic powder. Compared to intrinsic oxides, the free electrons introduced by doping can effectively shield high-frequency eddy current penetration, further reducing losses above 100kHz by 10-15%, while maintaining resistivity >500μΩ·cm. Its high carrier mobility enhances the space charge polarization effect, resulting in a stable increase in permeability, and its cost is far lower than that of the iron-silicon-aluminum / iron-nickel-molybdenum system.

[0012] Preferably, the particle size of the n-type semiconductor oxide nanoparticles is 10-50 nm.

[0013] By adopting the above technical solution and optimizing the particle size of n-type semiconductor oxide nanoparticles, they can be tightly attached to the surface of iron-silicon magnetic powder to form a continuous and dense nano-insulating layer. This can effectively sever the microscopic eddy current path, increase the contact resistance between particles, and further improve the overall resistivity. At the same time, the nanoscale effect strengthens the interfacial polarization, which increases the effective permeability and ultimately reduces the core loss by more than 40%.

[0014] Preferably, the iron-silicon alloy is a spherical powder obtained by mixing iron, silicon, aluminum and doping elements in a weight ratio of (93-95):(3-5):(0.5-0.8):0.8 and then atomizing it.

[0015] By adopting the above technical solution and optimizing the composition of the iron-silicon alloy, the resistivity of the matrix is ​​increased by more than 50%, and eddy current losses are reduced. The spherical morphology ensures uniform adhesion of the composite insulating coating agent, forming a tight match with the nano-semiconductor oxide, thus improving the overall resistivity. The synergistic effect of the matrix and the coating layer reduces the core loss by 40-50%, and the effective permeability stably reaches 100-120. At the same time, the flowability of the spherical powder greatly improves the pressing and molding processability and batch consistency, combining high performance with industrial feasibility.

[0016] Preferably, the average particle size of the iron-silicon alloy is 100-300 mesh.

[0017] By adopting the above technical solution, the average particle size of the iron-silicon alloy is optimized. Preferably, the adhesive solution is prepared from the following raw materials by weight: 20-30 parts of epoxy-terminated silicone oil modified epoxy resin, 3-5 parts of hydroxyl-terminated polydimethylsiloxane, 2-4 parts of nano-silica sol, 0.1-0.3 parts of crosslinking catalyst, 0.5-1 parts of crosslinking agent, and 20-40 parts of organic solvent.

[0018] By adopting the above technical solution, using epoxy resin modified with terminal epoxy groups as the main body, and through the epoxy-hydroxyl crosslinking reaction with hydroxyl-terminated polydimethylsiloxane, a rigid network structure with embedded flexible silicone segments is formed. This increases the bending strength of the cured magnetic core by 20-30%, while effectively alleviating thermal stress during high-frequency operation and preventing cracking of the pressed body. Nano-silica sol, as an inorganic reinforcing phase, can be uniformly dispersed to form a micro-nano composite structure, improving the thermal conductivity of the adhesive, accelerating the dissipation of heat lost from the magnetic core, and synergistically increasing the overall resistivity and reducing eddy current losses with the composite insulating coating agent. The viscosity of the organic solvent is adjusted to 2000-5000 cps to ensure uniform mixing of the magnetic powder, coating agent, and adhesive, resulting in a density uniformity deviation of <±2% for the pressed parts and excellent batch consistency.

[0019] Preferably, the structural formula of the epoxy resin modified with terminal epoxy groups is as follows: .

[0020] By adopting the above technical solution, the structure of the epoxy resin modified with epoxy-terminated silicone oil is optimized. It can undergo hydrosilylation with hydrogen-containing silicone oil and participate in epoxy-amine or epoxy-hydroxyl crosslinking reactions to form an organosilicon-epoxy interpenetrating network. Its flexible silicone segments effectively alleviate internal thermal stress and mechanical shock of the magnetic core and inhibit the generation of microcracks. The epoxy-terminated groups ensure good compatibility and co-curing with the silane coupling agent and polyether-modified bisphenol F epoxy resin on the iron-nickel powder surface, improving the interfacial bonding force, thereby enhancing the toughness, damp heat resistance and dimensional stability of the adhesive, and ensuring the long-term reliability and performance consistency of the magnetic core under high-frequency and high-temperature conditions.

[0021] Preferably, the hydroxyl-terminated polydimethylsiloxane has a molecular weight of 3000-6000, a hydroxyl value of 45-75 mgKOH / g, and a viscosity of 200-500 mPa.s at 25°C.

[0022] By adopting the above technical solution and optimizing the parameters of hydroxyl-terminated polydimethylsiloxane, the viscosity of the adhesive solution is stabilized at 2000-4000 mPa·s, improving the magnetic powder filling rate while maintaining good fluidity and ensuring uniform density of the pressed preform. Precise control of the hydroxyl value results in a high degree of reaction with the epoxy groups, forming an interpenetrating network structure, which enhances the interfacial bonding strength and effectively prevents core delamination and cracking. The appropriate molecular weight and viscosity reduce the dielectric loss of the material, with a Q value attenuation of <10% at 1MHz, meeting the stringent requirements of low dielectric loss for high-frequency applications.

[0023] Preferably, the crosslinking catalyst is a composite catalyst composed of dibutyltin dilaurate and titanate coupling agent in a mass ratio of 1:0.5-1.

[0024] By adopting the above technical solution, the curing of the adhesive is promoted, the curing time is shortened, and the efficiency of crosslinking reaction and the quality of interfacial bonding are improved.

[0025] Secondly, this application provides a method for preparing iron-silicon magnetic powder inductor material, which adopts the following technical solution: A method for preparing iron-silicon magnetic powder inductor material includes the following preparation steps: S1, stirring iron-silicon alloy, composite insulating coating agent, surfactant, ferric nitrate, citric acid and binder solution evenly to obtain a mixture; S2, placing the magnetic core blank formed by pressing the mixture into a furnace, applying a pulsed magnetic field with an intensity of 0.5-2T, a frequency of 5-20Hz, and a duration of 10-30min, heating to 180-220℃ and holding for 1-2h in a hydrogen / nitrogen mixed atmosphere, then continuing to heat to 450-550℃ and holding for 2-4h, and cooling to obtain iron-silicon magnetic powder inductor material.

[0026] By employing the above technical solution, applying a 0.5-2 T pulsed magnetic field during heat treatment induces the iron-silicon magnetic powder particles to align orderly along the magnetic field direction in the early stages of curing, effectively optimizing magnetic domain orientation, reducing hysteresis loss, and improving effective permeability. Combined with a two-stage heating process under a hydrogen-nitrogen mixed atmosphere, this achieves both thorough cross-linking and curing of the binder and removal of organic matter, while preventing magnetic powder oxidation. Simultaneously, it promotes the synergistic stabilization of the iron oxide nanofilm generated in situ in the ferric nitrate-citric acid system and the composite insulating coating layer. This process improves the high-frequency performance, permeability stability, and mechanical strength of the iron-silicon magnetic powder inductor material, resulting in inductor materials with low loss, high Q value, and excellent batch consistency, while also being compatible with existing monolithic molding production lines.

[0027] In summary, this application has the following beneficial effects: 1. By constructing a composite insulating coating layer composed of phosphate and n-type semiconductor oxide nanoparticles on the surface of iron-silicon alloy particles, this application significantly improves the volume resistivity of iron-silicon magnetic powder inductor materials, effectively suppresses eddy current losses in the megahertz frequency band, greatly reduces core temperature rise, and improves energy conversion efficiency. Simultaneously, by utilizing the sol-gel reaction of ferric nitrate and citric acid to generate an in-situ iron oxide nanofilm, the magnetic anisotropy of the particle surface is controlled, increasing the effective permeability while maintaining high saturation magnetic flux density, thus overcoming the bottleneck of poor design flexibility in iron-silicon materials. Furthermore, the surfactant optimizes the dispersibility of the magnetic powder and binder, and, in conjunction with a dedicated binder system, ensures stable pressing and molding processes, high yield, and compatibility with existing production lines. The overall solution systematically solves the problems of high high-frequency loss, low permeability, and difficulty in miniaturization of iron-silicon magnetic powder inductors, fully meeting the urgent needs of consumer electronics, new energy vehicles, and 5G communications for high-performance power inductors. Detailed Implementation Examples

[0028] The nano-silica sol was purchased from Lianyungang Huayuan Chemical Co., Ltd.

[0029] Example 1

[0030] A type of iron-silicon magnetic powder inductor material is prepared by the following method: S1. 800g of iron-silicon alloy, 10g of composite insulating coating agent, 10g of surfactant (glycerol), 1g of ferric nitrate, 0.5g of citric acid, and 100g of binder solution are stirred evenly to obtain a mixture; the iron-silicon alloy is a spherical powder obtained by mixing iron, silicon, aluminum, and doping elements in a weight ratio of 93:3:0.5:0.8 and then atomizing; the average particle size of the iron-silicon alloy is 100 mesh; the composite insulating coating agent is prepared by the following method: 10g of phosphate (aluminum dihydrogen phosphate) and 6g of n-type semiconductor oxide nanoparticles (tin-doped antimony trioxide) are ultrasonically dispersed in ethanol, and 1g of silane coupling agent (γ-glycidyl etheroxypropyltrimethoxysilane) is added. The pH was adjusted to 4.0, and the reaction was carried out at 60℃ for 2 hours. After filtration and drying, the composite insulating coating agent was obtained. The adhesive solution was prepared by the following method: 200g of epoxy-terminated silicone oil modified epoxy resin, 30g of hydroxyl-terminated polydimethylsiloxane, 20g of nano-silica sol, 1g of crosslinking catalyst, 5g of crosslinking agent (polyetheramine), and organic solvent (ethyl acetate) were mixed evenly to obtain the adhesive solution. The hydroxyl-terminated polydimethylsiloxane had a molecular weight of 3000, a hydroxyl value of 45mgKOH / g, and a viscosity of 200mPa.s at 25℃. The crosslinking catalyst was a composite catalyst composed of dibutyltin dilaurate and titanate coupling agent at a mass ratio of 1:0.5. The structural formula of the epoxy-terminated silicone oil modified epoxy resin is as follows:

[0031] Where x=10, y=25; S2, the magnetic core blank formed by pressing the mixture is placed in an atmosphere furnace, a pulsed magnetic field with an intensity of 0.5T, a frequency of 5Hz, and a duration of 10min is applied, and the temperature is raised to 180℃ and held for 1h in a hydrogen / nitrogen mixed atmosphere, and then raised to 450℃ and held for 2h. After cooling, the iron-silicon magnetic powder inductor material is obtained.

[0032] The difference between Examples 2-3 and Example 1 lies in the types, amounts, and parameters of raw materials used to prepare the iron-silicon magnetic powder inductor material. Specific differences are shown in Table 1: Table 1: Types, amounts, and parameters of raw materials used to prepare the iron-silicon magnetic powder inductor material.

[0033] In Example 2, 16g of phosphate (zinc dihydrogen phosphate) and 20g of n-type semiconductor oxide nanoparticles (aluminum-doped zinc oxide) were ultrasonically dispersed in ethanol. 2g of silane coupling agent (γ-aminopropyltriethoxysilane) was added, the pH was adjusted to 5, and the reaction was carried out at 60℃ for 3 hours. After filtration and drying, the composite insulating coating agent was obtained. The adhesive solution was prepared by the following method: 250g of epoxy-terminated silicone oil modified epoxy resin, 40g of hydroxyl-terminated polydimethylsiloxane, 30g of nano-silica sol, 2g of crosslinking catalyst, 8g of crosslinking agent, and 300g of organic solvent (ethyl acetate) were mixed evenly to obtain the adhesive solution. The hydroxyl-terminated polydimethylsiloxane had a molecular weight of 4500, a hydroxyl value of 60mgKOH / g, and a viscosity of 300mPa.s at 25℃. The crosslinking catalyst was a composite catalyst composed of dibutyltin dilaurate and titanate coupling agent at a mass ratio of 1:0.8. The structural formula of the epoxy-terminated silicone oil modified epoxy resin is as follows:

[0034] Where x=15, y=20.

[0035] In Example 3, 20g of phosphate (magnesium dihydrogen phosphate) and 30g of n-type semiconductor oxide nanoparticles (indium-doped tin oxide) were ultrasonically dispersed in ethanol. 4g of silane coupling agent (γ-(methacryloyloxy)propyltrimethoxysilane) was added, the pH was adjusted to 5.5, and the mixture was reacted at 80°C for 4 hours. The mixture was then filtered and dried to obtain the composite insulating coating agent. The adhesive solution was prepared by the following method: 300g of epoxy resin modified with terminal epoxy group silicone oil, 50g of hydroxyl-terminated polydimethylsiloxane, ... A binder solution was obtained by uniformly mixing 40g of nano-silica sol, 3g of crosslinking catalyst, 10g of crosslinking agent (methylhexahydrophthalic anhydride), and 400g of organic solvent (ethyl acetate); the molecular weight of hydroxyl-terminated polydimethylsiloxane was 36000, the hydroxyl value was 75mgKOH / g, and the viscosity at 25℃ was 500mPa.s; the crosslinking catalyst was a composite catalyst composed of dibutyltin dilaurate and titanate coupling agent in a mass ratio of 1:1; the structural formula of the epoxy resin modified with terminal epoxy group silicone oil is as follows:

[0036] Where x=20, y=15.

[0037] Example 4

[0038] A type of iron-silicon magnetic powder inductor material, the difference between this embodiment and embodiment 1 is that the epoxy resin modified with terminal epoxy group silicone oil is replaced with bisphenol A type epoxy resin.

[0039] The bisphenol A type epoxy resin is EP01441-310 type bisphenol A type epoxy resin.

[0040] Example 5

[0041] A type of iron-silicon magnetic powder inductor material, the difference between this embodiment and embodiment 1 is that the nano-silica sol is replaced with an equal mass of nano-silica.

[0042] Example 6

[0043] A type of iron-silicon magnetic powder inductor material, the difference between this embodiment and Example 1 is that the particle size of the n-type semiconductor oxide nanoparticles is 60 nm. Example 7

[0044] A type of iron-silicon magnetic powder inductor material, the difference between this embodiment and Embodiment 1 is that the iron-silicon alloy is a spherical powder obtained by mixing iron, silicon and aluminum in a weight ratio of 93:3:0.5 and then atomizing it. Comparative Example

[0045] Comparative Example 1: A type of iron-silicon magnetic powder inductor material. The difference between this comparative example and Example 1 is that aluminum dihydrogen phosphate is used instead of an equal mass of composite insulating coating agent.

[0046] Comparative Example 2 is an iron-silicon magnetic powder inductor material. The difference between this comparative example and Example 1 is that tin-doped antimony trioxide is replaced with antimony trioxide.

[0047] Comparative Example 3 is an iron-silicon magnetic powder inductor material. The difference between this comparative example and Example 1 is that iron nitrate is not added.

[0048] Comparative Example 4: An iron-silicon magnetic powder inductor material. This comparative example differs from Example 1 in that citric acid is replaced with 5% hydrochloric acid by mass. Detection Method / Test Method

[0049] Volume resistivity test: Performed according to ASTM D257. Cylindrical blanks with a diameter of 10 mm and a thickness of 2 mm were prepared from Examples 1-7 and Comparative Examples 1-5, respectively. Silver electrodes were sprayed onto the surface to form parallel electrodes. A DC voltage of 10 V was applied using a high-resistivity meter (Keithley 6517B) to measure the leakage current and test the volume resistivity, ρ = R * (A / L), where R is the measured resistance, A is the electrode area, and L is the sample thickness. Core loss test: Referencing IEC 60404-6:2018 "Magnetic materials – Part 6: Methods of measurement for soft magnetic metal powder materials in toroidal specimens", the samples were pressed into standard toroidal cores with a diameter of Φ25 mm × Φ15 mm × 8 mm, N1 = N2 = 20 turns, frequency range 100 kHz, 500 kHz, 1 MHz, magnetic flux density: 0.1 T, temperature 25 °C. Effective permeability: Referencing GB / T 3658-2008 "Measuring Method of AC Magnetic Properties of Soft Magnetic Materials for Ring-Shaped Specimens", Test conditions: frequency 100kHz, 1MHz, magnetic field strength H=10A / m; Quality factor (Q value) test: refer to SJ / T 10281-1991 "Detailed Specifications for Electronic Components - Ferrite Cores", Sample preparation: the magnetic core is wound with a 10-turn coil, LCR digital bridge test, test conditions: frequency 1MHz, temperature 25℃; Experimental data are shown in Table 2: Table 2 Experimental data of Examples 1-7 and Comparative Examples 1-4

[0050] As shown in the above data, this application improves the overall performance of iron-silicon magnetic powder inductor materials by introducing a composite insulating coating agent composed of phosphate and n-type semiconductor oxide nanoparticles, combined with ferric nitrate-citric acid sol-gel surface modification and a highly thermally conductive flexible organosilicon-modified epoxy bonding system. The volume resistivity can be increased to over 620 μΩ·cm, effectively suppressing high-frequency eddy current losses and significantly reducing core losses at 1MHz. Simultaneously, the effective permeability is broadened to 112–125, maintaining excellent stability at 1MHz, and the quality factor is improved. This demonstrates that while maintaining the advantages of low cost and high saturation magnetic flux density of the iron-silicon system, this material fully meets the stringent requirements of high-frequency, miniaturized, and high-efficiency power inductors in consumer electronics, new energy vehicles, and 5G communications.

[0051] By comparing Example 1 with Comparative Examples 1–4, it can be seen that using only phosphate or undoped oxides cannot effectively improve resistivity and suppress high-frequency eddy current losses; Comparative Example 3 shows that the lack of ferric nitrate will cause the magnetic permeability to fail to break through the traditional upper limit; Comparative Example 4 shows that the key complexing role of citric acid in forming a uniform iron oxide functional film cannot be replaced by ordinary acid. Only when all components work together can high resistivity, low core loss, high magnetic permeability and high Q value be achieved simultaneously.

[0052] Comparing Examples 1 with Examples 4-7, Example 4 uses ordinary bisphenol A type epoxy resin instead of epoxy-terminated silicone oil modified epoxy resin, resulting in insufficient flexibility, high interfacial stress, increased core loss, and decreased Q value; Example 5 uses nano-silica powder instead of sol, which weakens thermal conductivity and insulation due to poor dispersibility and weak interfacial bonding; In Example 6, the n-type semiconductor oxide particle size is too large, making it difficult to form a dense and uniform coating layer, resulting in deterioration of high-frequency performance; Example 7 omits doping elements, which reduces the matrix resistivity and magnetic properties. This shows that only by using modified resin with a specific structure, nano-sol morphology, optimized nano-powder particle size, and iron-silicon alloy containing aluminum and doping elements can the advantages of high frequency, low loss, high permeability, and high reliability of iron-silicon magnetic powder inductors be fully utilized.

[0053] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A type of iron-silicon magnetic powder inductor material, characterized in that, It is prepared from the following raw materials in parts by weight: 80-95 parts iron-silicon alloy, 1-3 parts composite insulating coating agent, 1-2 parts surfactant, 0.1-0.5 parts ferric nitrate, 0.05-0.1 parts citric acid, and 10-15 parts adhesive solution; The composite insulating coating agent is prepared by the following method: 0.5-1 parts by weight of phosphate and 0.3-1.5 parts by weight of n-type semiconductor oxide nanoparticles are ultrasonically dispersed in ethanol, 0.05-0.2 parts by weight of silane coupling agent are added, the pH is adjusted to 4.0-5.5, the mixture is reacted at 60-80℃ for 2-4 hours, filtered, and dried to obtain the composite insulating coating agent.

2. The iron-silicon magnetic powder inductor material according to claim 1, characterized in that: The n-type semiconductor oxide is at least one of tin-doped antimony trioxide, aluminum-doped zinc oxide, or indium-doped tin oxide.

3. The iron-silicon magnetic powder inductor material according to claim 1, characterized in that: The particle size of the n-type semiconductor oxide nanoparticles is 10-50 nm.

4. The iron-silicon magnetic powder inductor material according to claim 1, characterized in that: The adhesive solution is prepared from the following raw materials in parts by weight: 20-30 parts of epoxy-terminated silicone oil modified epoxy resin, 3-5 parts of hydroxyl-terminated polydimethylsiloxane, 2-4 parts of nano silica sol, 0.1-0.3 parts of crosslinking catalyst, 0.5-1 parts of crosslinking agent, and 20-40 parts of organic solvent.

5. The iron-silicon magnetic powder inductor material according to claim 4, characterized in that, The structural formula of the epoxy resin modified with terminal epoxy groups is as follows: 。 6. The iron-silicon magnetic powder inductor material according to claim 4, characterized in that: The hydroxyl-terminated polydimethylsiloxane has a molecular weight of 3000-6000, a hydroxyl value of 45-75 mgKOH / g, and a viscosity of 200-500 mPa.s at 25°C.

7. The iron-silicon magnetic powder inductor material according to claim 4, characterized in that: The crosslinking catalyst is a composite catalyst composed of dibutyltin dilaurate and titanate coupling agent in a mass ratio of 1:0.5-1.

8. The iron-silicon magnetic powder inductor material according to claim 1, characterized in that: The iron-silicon alloy is a spherical powder obtained by mixing iron, silicon, aluminum and doping elements in a weight ratio of (93-95):(3-5):(0.5-0.8):0.8 and then atomizing it.

9. The iron-silicon magnetic powder inductor material according to claim 8, characterized in that: The average particle size of the iron-silicon alloy is 100-300 mesh.

10. A method for preparing the iron-silicon magnetic powder inductor material as described in any one of claims 1-9, characterized in that, The preparation process includes the following steps: S1, stirring the iron-silicon alloy, composite insulating coating agent, surfactant, ferric nitrate, citric acid and binder solution evenly to obtain a mixture; S2, placing the magnetic core blank formed by pressing the mixture into a furnace, applying a pulsed magnetic field with an intensity of 0.5-2T, a frequency of 5-20Hz, and a duration of 10-30min, heating to 180-220℃ and holding for 1-2h in a hydrogen / nitrogen mixed atmosphere, then continuing to heat to 450-550℃ and holding for 2-4h, and cooling to obtain the iron-silicon magnetic powder inductor material.

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