Iron-silicon-chromium alloy composite material with high magnetic conductivity and low loss and preparation method of iron-silicon-chromium alloy composite material

Abstract

The invention discloses an iron-silicon-chromium alloy composite material with high magnetic conductivity and low loss and a preparation method thereof, and the preparation method comprises the following steps: the main component comprises the following components in percentage by mass: 95-99.5% of iron-silicon-chromium alloy powder; and 0.5%-5% of inorganic nano aluminum oxide. The preparation method comprises the following steps: carrying out wet ball milling treatment on Fe-Si-Cr magnetic powder and nano aluminum oxide by adopting a mechanical alloying method, drying after treatment to obtain a mixed dry material, adding epoxy resin glue into the mixed dry material, and finally carrying out dry-wet granulation to obtain a target product, namely the Fe-Si-Cr alloy composite material. According to the invention, through the process combination of mechanical alloying and granulation, an insulating system compositely coated with inorganic nano aluminum oxide and epoxy resin is obtained, and firm coating of an insulating layer and good formability of composite powder are realized, so that the magnetic conductivity of the alloy is greatly improved, the loss of the alloy is reduced, the magnetic conductivity of the alloy is 43.2 at-100 kHz, and the loss of the alloy is 328.8. A soft magnetic composite material solution with excellent comprehensive performance is provided for related industries, and the requirements for integration and reliability in the fields of integrally-formed inductors, transformers and the like are met.

Description

Technical Field

[0001] This invention relates to the field of soft magnetic composite materials technology, specifically to a high-permeability, low-loss iron-silicon-chromium alloy composite material and its preparation method. Background Technology

[0002] Currently, ferroalloy materials in soft magnetic composites are widely used in fast-moving consumer goods (FMCG) smart terminal products, as well as inductors, high-frequency transformers, and energy storage components. These fields constantly demand updated and upgraded material properties. Increasing the magnetic permeability of materials can reduce the size of power inductor products and improve their current withstand characteristics. Therefore, researching and improving material properties to meet market demands is imperative.

[0003] Among numerous materials, iron-silicon-chromium alloys, as excellent soft magnetic materials, have gradually become the preferred material in many application fields due to their high permeability, low loss, and rust resistance. However, iron-silicon-chromium alloy materials still face many problems in practical applications. One issue is that under high-frequency alternating magnetic fields, eddy current loops form between conductive metal particles, resulting in significant interparticle eddy current losses, which severely limits their efficiency at high frequencies. To reduce losses caused by high frequencies, insulation methods are often used to modify the material by coating it. However, while using an insulating layer can improve insulation properties, it usually significantly reduces permeability, greatly diminishing the material's inherent advantages. Current technologies mainly employ insulating coatings on metal powder particles to improve the overall resistivity of the material. Coating metal powder with organic materials is relatively common. This method is simple and offers acceptable insulation performance. However, the inherent drawbacks of organic materials greatly limit their application, and their poor heat resistance leads to decomposition during subsequent heat treatment or high-temperature operation of devices, resulting in insulation failure and reduced magnetic properties. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an iron-silicon-chromium alloy composite material with high magnetic permeability and low loss characteristics, as well as its preparation method. This material can be widely used in fields such as integrally molded inductors, significantly reducing high-frequency eddy current losses while maintaining high magnetic permeability, and effectively improving the molding density and quality factor of the material.

[0005] This invention is achieved through the following technical solution: A high-permeability, low-loss iron-silicon-chromium alloy composite material includes iron-silicon-chromium alloy powder, nano-alumina powder dispersed and attached to the surface of the iron-silicon-chromium alloy powder, and an epoxy resin layer coated on the surface of the iron-silicon-chromium alloy powder. The composite material contains 0.5% to 5% nano-alumina powder and 95% to 99.5% iron-silicon-chromium alloy powder by mass fraction.

[0006] Preferably, the iron-silicon-chromium alloy powder contains 4.0% to 6.0% Si and 4.0% to 6.0% Cr by mass percentage, with the balance being Fe.

[0007] Preferably, the iron-silicon-chromium alloy composite material has a magnetic permeability μi ≥ 43.2 and a loss ≤ 328.8 kW / m at a frequency of 100 kHz. 3 .

[0008] A method for preparing a high-permeability, low-loss iron-silicon-chromium alloy composite material includes the following steps: Step S1: Disperse 0.5% to 5% of nano-alumina powder by mass percentage and attach it to the surface of 95% to 99.5% of iron-silicon-chromium alloy powder to obtain pre-dispersed composite powder. Step S2: Coat the surface of the pre-dispersed composite powder with epoxy resin to obtain the iron-silicon-chromium alloy composite material; The epoxy resin adhesive includes epoxy resin A and epoxy resin B, and the ratio of epoxy resin A to epoxy resin B is (6-8):1.

[0009] Preferably, the preparation method of the pre-dispersed composite powder is as follows: The nano-alumina powder and the iron-silicon-chromium alloy powder are ball-milled to obtain a pre-dispersed composite powder precursor. Then, the process control agent of the ball milling process is removed to obtain the pre-dispersed composite powder.

[0010] Preferably, the preparation method of the iron-silicon-chromium alloy composite material is as follows: An epoxy resin-acetone solution is added to the pre-dispersed composite powder. The powder is then wet-mixed to ensure that the resin solution uniformly impregnates and coats the powder. The powder is then dried to remove the solvent acetone. Finally, the powder is granulated twice and sieved to obtain the iron-silicon-chromium alloy composite material.

[0011] Preferably, the preparation method of the iron-silicon-chromium alloy composite material is as follows: Epoxy resin A and epoxy resin B are mixed at a mass ratio of (6-8):1, and then acetone equal in mass to the total mass of the epoxy resin is added. The mixture is stirred until homogeneous to obtain epoxy resin. Acetone solution; The epoxy resin An acetone solution is added to the pre-dispersed composite powder to make the epoxy resin... The pre-dispersed composite powder is coated with acetone solution to obtain a mixture; wherein the amount of epoxy resin A glue added is 4% to 6% of the total mass of the pre-dispersed composite powder; The mixture was heated at 70°C. Dry at 80℃ for 1 minute 2 hours, until the acetone has completely evaporated to obtain a dry mixture; The dried mixture is then dry-granulated, passing through a 60°C filter. The iron-silicon-chromium alloy composite material was obtained by sieving through a 200-mesh screen.

[0012] An inductor made of the aforementioned high-permeability, low-loss iron-silicon-chromium alloy composite material.

[0013] A method for fabricating an inductor includes the following steps: The inductor blank is pressed using the aforementioned high-permeability, low-loss iron-silicon-chromium alloy composite material. The inductor blank is subjected to gradient sintering to obtain the inductor; The gradient sintering includes: From room temperature at 2 Heating to 100°C at a rate of 3°C / min 150℃, heat preservation 1 2 h; Continue with 2 Heating to 200°C at a rate of 3°C / min 250℃, heat preservation 1 2 h; Then use 2 Heating to 550°C at a rate of 3°C / min 600℃, heat preservation 2 3 h; Finally, it is cooled in the furnace.

[0014] An apparatus comprising the inductor; The equipment includes smart terminal devices and power equipment.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: This application provides a high-permeability and low-loss iron-silicon-chromium alloy composite material. Using micron-sized iron-silicon-chromium alloy powder as the matrix, nano-alumina powder is forcibly dispersed and adhered to its surface through high-energy mechanical force, forming a continuous and stable inorganic pre-insulating layer. On this basis, an epoxy resin organic layer is further coated to fill any microscopic defects and pores that may exist in the inorganic layer, ultimately forming a dense, complete, and firmly bonded composite insulating system. This iron-silicon-chromium alloy composite material can effectively block direct contact between metal particles, significantly improving the overall resistivity and thus suppressing high-frequency eddy current losses. Simultaneously, due to the thin and uniform thickness of the insulating layer and the synergistic effect of the organic-inorganic phases enhancing the interfacial bonding and material toughness, the blocking effect of non-magnetic components on the magnetic circuit is minimized, thus maintaining high permeability while significantly reducing losses. The advantages of this composite material are as follows: First, the introduction of nano-alumina improves the heat resistance and stability of the insulating layer, overcoming the disadvantage of easy decomposition at high temperatures caused by single organic coatings; second, the epoxy resin coating not only fills the microscopic discontinuities in the inorganic layer, but also enhances the formability and mechanical strength of the powder, solving the problem of high brittleness and difficulty in compression molding of pure inorganic coatings; finally, the obtained composite material exhibits both high magnetic permeability (≥43.2) and low loss (≤328.8kW / m) at 100kHz. 3 With significantly improved overall soft magnetic properties, it is particularly suitable for high-frequency, high-power-density integral molded inductors and magnetic devices such as smart terminals. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart illustrating the preparation process of the iron-silicon-chromium composite material of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0020] In a first aspect, this application provides a high-permeability, low-loss iron-silicon-chromium alloy composite material, comprising iron-silicon-chromium alloy powder, nano-alumina powder dispersed and attached to the surface of the iron-silicon-chromium alloy powder, and an epoxy resin layer coated on the surface of the iron-silicon-chromium alloy powder.

[0021] By mass fraction, the content of nano-alumina powder is 0.5% to 5%, and the content of iron-silicon-chromium alloy powder is 95% to 99.5%. The iron-silicon-chromium alloy powder, by mass percentage, contains 4.0%–6.0% Si, 4.0%–6.0% Cr, and the balance is Fe.

[0022] The particle size of this iron-silicon-chromium alloy powder is 12–16 μm.

[0023] The iron-silicon-chromium alloy composite material exhibits a magnetic permeability μi ≥ 43.2 and a loss ≤ 328.8 kW / m at a frequency of 100 kHz. 3 .

[0024] This composite material employs an inorganic-organic composite insulation structure design. By sequentially constructing a nano-alumina adhesion layer and an epoxy resin coating layer on the surface of iron-silicon-chromium alloy powder, high-frequency soft magnetic properties are synergistically enhanced. The nano-alumina, as a heat-resistant inorganic insulating phase, effectively blocks the conductive pathways between metal particles, significantly suppressing eddy current losses. The epoxy resin, as an organic binder and filler phase, compensates for the microscopic defects of the inorganic layer, forming a continuous and dense composite insulation system, while also improving powder formability and mechanical strength. This composite structure ensures insulation reliability while minimizing the disruption of the magnetic circuit by non-magnetic components, thereby maintaining high permeability while reducing losses. The material achieves a permeability exceeding 43.2 and a loss below 328.8 kW / m at 100 kHz. 3 It combines good high-temperature stability and process adaptability, and is suitable for magnetic devices that require high power density and low loss, such as integrally molded inductors and high-frequency transformers.

[0025] Secondly, this application provides a method for preparing a high-permeability, low-loss iron-silicon-chromium alloy composite material, specifically including the following steps: Step 1: Disperse 0.5% to 5% of nano-alumina powder by mass percentage and attach it to the surface of 95% to 99.5% of iron-silicon-chromium alloy powder to obtain pre-dispersed composite powder. The iron-silicon-chromium alloy powder contains 4.0-6.0% Si, 4.0-6.0% Cr, and the remainder is Fe.

[0026] Step 2: Coat the surface of the pre-dispersed composite powder with epoxy resin to obtain an iron-silicon-chromium alloy composite material.

[0027] The epoxy resin adhesive includes epoxy resin A and epoxy resin B, with the ratio of epoxy resin A to epoxy resin B being (6~8):1.

[0028] This preparation method uses high-energy mechanical force to forcibly disperse and adhere nano-alumina powder to the surface of iron-silicon-chromium alloy particles, forming a uniform and stable inorganic pre-insulating layer, laying the microstructural foundation for suppressing high-frequency eddy currents. Then, utilizing the wettability and adhesiveness of epoxy resin, the pre-insulating powder is coated. The epoxy resin fills the microscopic pores and defects of the inorganic layer, forming a continuous, dense, and flexible inorganic-organic composite insulating layer. The coupling of inorganic and organic materials enhances the heat resistance and stability of the insulation system through alumina, while the epoxy resin strengthens the integrity, adhesion, and powder formability of the coating layer. The two-step process offers strong controllability, facilitating precise control of the insulation layer thickness and uniformity. This effectively suppresses eddy current losses while minimizing the negative impact of non-magnetic materials on magnetic permeability, ultimately resulting in a composite material with both high magnetic permeability and low loss characteristics, suitable for large-scale production.

[0029] In some embodiments, nano-alumina powder is dispersed and adhered to the surface of iron-silicon-chromium alloy powder to obtain a pre-dispersed composite powder, comprising: Mechanical force is used to highly disperse nano-alumina powder and attach it to or embed it into the surface of iron-silicon-chromium alloy powder particles, thus forming a pre-dispersed composite powder.

[0030] As a more specific example, the preparation method of pre-dispersed composite powder is as follows: Nano-alumina powder and iron-silicon-chromium alloy powder were fed into a planetary ball mill in a certain ratio, and an appropriate amount of alcohol was added as a process control agent. The mixture was wet-milled at a speed of 150-300 r / min for 6-8 hours. Through the mechanical force of high-energy ball milling, the nano-alumina particles were uniformly dispersed and firmly attached to the surface of the iron-silicon-chromium alloy powder, thus obtaining a pre-dispersed composite powder precursor. Then, the pre-dispersed composite powder precursor is dried at 70-80℃ for 6-8 hours to completely remove the alcohol solvent and obtain a dry, loose pre-dispersed composite powder.

[0031] This method utilizes the intense mechanical force of wet high-energy ball milling to forcibly disperse, collide, and embed or adhere nano-sized alumina particles to the surface of micron-sized iron-silicon-chromium alloy powder, thereby initially constructing a pre-insulating composite structure with nano-alumina as the framework at the physical level. The subsequent low-temperature drying process gently removes process additives (alcohol), achieving a phase transformation from a wet composite slurry to a dry, loose, and further processable functional powder.

[0032] Wet ball milling can effectively inhibit the agglomeration of nanoparticles, and the addition of alcohol has both grinding aid and anti-oxidation effects; the drying temperature is low and the time is long, which avoids powder oxidation or damage to the insulation layer; the pre-dispersed composite powder formed can form a close complement with the organic layer in the subsequent coating process, synergistically reducing eddy current loss and maintaining high magnetic permeability.

[0033] In some embodiments, an epoxy resin adhesive is coated onto the surface of a pre-dispersed composite powder to obtain an iron-silicon-chromium alloy composite material, comprising: An epoxy resin-acetone solution was added to the pre-dispersed composite powder, and the powder was uniformly impregnated and coated by wet mixing. The powder was then dried to remove the acetone solvent, followed by secondary dry powder granulation and sieving to obtain the iron-silicon-chromium alloy composite material.

[0034] As a more specific example, the preparation method of iron-silicon-chromium alloy composite material is as follows: S2.1. Mix epoxy resin A and epoxy resin B in a mass ratio of (6~8):1, then add acetone as a solvent in an equal mass ratio (i.e., 1:1 ratio) to the total mass of the epoxy resin adhesives, and stir until a homogeneous and transparent epoxy resin-acetone solution is formed. The stirring time is controlled at 15~20 minutes.

[0035] S2.2 Add the prepared epoxy resin-acetone solution to the pre-dispersed composite powder and stir thoroughly in a closed mixing device to ensure that the solution completely wets and evenly coats each composite powder particle to obtain a mixture. The amount of epoxy resin A glue added is controlled to be 4% to 6% of the total mass of the pre-dispersed composite powder.

[0036] S2.3 Transfer the mixture to an oven and dry it at 70~80℃ for 1~2 hours until the acetone is completely evaporated. At this time, the epoxy resin will be initially cross-linked and cured to obtain the dried mixture. S2.4. The dried mixture is mechanically dry granulated to redisperse it into a fine powder with good flowability, and then passed through a 60-200 mesh sieve to obtain iron-silicon-chromium alloy composite powder.

[0037] This method utilizes the fluidity and permeability of an epoxy resin-acetone solution to achieve uniform coating and micro-filling of pre-dispersed composite powders. Based on the pre-dispersed powder already possessing a nano-alumina pre-insulating layer, the liquid resin can effectively penetrate its micropores and interfaces, forming a continuous, dense, and tightly bonded organic-inorganic composite insulating system after curing. Acetone, as a volatile solvent, not only adjusts the resin viscosity to improve coating uniformity but is also completely removed through a gentle drying process, preventing residues from affecting insulation performance. Finally, pulverization treatment yields an iron-silicon-chromium alloy composite material.

[0038] Thirdly, this application provides a method for fabricating an inductor, comprising the following steps: Step 1: Press the inductor blank using the above-mentioned iron-silicon-chromium alloy composite material; Step 2: The inductor blank is sintered using a gradient heating process to obtain the inductor; The gradient heating process is as follows: First, slowly raise the temperature from room temperature to 100-150°C at a rate of 2-3°C / minute, and hold for 1-2 hours; Then, slowly raise the temperature to 200-250℃ at a rate of 2-3℃ / minute and hold for 1-2 hours; Secondly, slowly raise the temperature to 550-600℃ at a rate of 2-3℃ / minute and hold for 2-3 hours; Finally, the inductor is obtained by cooling it in the furnace.

[0039] Example 1 A high-permeability, low-loss iron-silicon-chromium alloy composite material and its preparation method, comprising the following steps: Step 1: Prepare pre-dispersed composite powder; By mass percentage, 99% iron-silicon-chromium magnetic powder and 1% nano-alumina powder were mixed and fed into a planetary ball mill. Alcohol, equivalent to 5% of the total powder mass, was added as a process control agent. The mixture was ball-milled for 8 hours at 300 r / min to obtain a pre-dispersed composite powder precursor. The pre-dispersed composite powder precursor was then placed in an oven and dried at 80℃ for 8 hours to completely remove the alcohol, yielding a dry pre-dispersed composite powder.

[0040] Step 2: Prepare iron-silicon-chromium alloy composite material; Preparation of epoxy resin-acetone coating solution: Mix epoxy resin A and epoxy resin B in a mass ratio of 8:1, then add acetone equal to the total mass of epoxy resin, stir for 20 minutes until homogeneous and transparent, and obtain epoxy resin-acetone solution.

[0041] The epoxy resin-acetone solution was added to the pre-dispersed composite powder, with epoxy resin A being added at 4% of the pre-dispersed composite powder mass. The mixture was thoroughly mixed in a closed system to ensure the epoxy resin-acetone solution uniformly impregnates and coats all powder particles. The wet material was then dried at 80°C for 2 hours until the acetone completely evaporated and the epoxy resin was initially cured. The dried material was then subjected to secondary dry granulation and passed through a 60-200 mesh sieve to obtain the iron-silicon-chromium alloy composite powder.

[0042] Furthermore, the inductor is prepared using the iron-silicon-chromium alloy composite powder from step 2, including the following process: Add 0.1% zinc stearate as a release agent and 0.1% binder by mass to the above composite powder, mix evenly, and then cold press it under 95 N pressure using a mold to obtain an inductor blank.

[0043] The inductor blank is subjected to gradient sintering, and the specific process is as follows: The temperature is increased from room temperature to 150°C at a rate of 2°C / min, and held at that temperature for 2 hours. Continue to increase the temperature to 250℃ at a rate of 2℃ / min, and hold for 2 hours; Then increase the temperature to 600℃ at a rate of 3℃ / min and hold for 3 hours; Finally, the furnace is cooled to obtain the final inductance.

[0044] The obtained iron-silicon-chromium alloy composite material has a permeability μi of 37.6 and a loss of 59.5 under a test condition of 100 kHz.

[0045] Example 2 A method for preparing a high-permeability, low-loss iron-silicon-chromium alloy composite material includes the following steps: Step 1: Prepare pre-dispersed composite powder; By mass percentage, 98% iron-silicon-chromium magnetic powder and 2% nano-alumina powder were mixed and fed into a planetary ball mill. Alcohol, equivalent to 5% of the total powder mass, was added as a process control agent. The mixture was ball-milled for 8 hours at 300 r / min to obtain a pre-dispersed composite powder precursor. The pre-dispersed composite powder precursor was then placed in an oven and dried at 80℃ for 8 hours to completely remove the alcohol, yielding a dry pre-dispersed composite powder.

[0046] Step 2: Prepare iron-silicon-chromium alloy composite material; Preparation of epoxy resin-acetone coating solution: Mix epoxy resin A and epoxy resin B in a mass ratio of 8:1, then add acetone equal to the total mass of epoxy resin, stir for 20 minutes until homogeneous and transparent, and obtain epoxy resin-acetone solution.

[0047] The epoxy resin-acetone solution was added to the pre-dispersed composite powder, with epoxy resin A being added at 4% of the pre-dispersed composite powder mass. The mixture was thoroughly mixed in a closed system to ensure the epoxy resin-acetone solution uniformly impregnates and coats all powder particles. The wet material was then dried at 80°C for 2 hours until the acetone completely evaporated and the epoxy resin was initially cured. The dried material was then subjected to secondary dry granulation and passed through a 60-200 mesh sieve to obtain the iron-silicon-chromium alloy composite powder.

[0048] Furthermore, the inductor is prepared using the iron-silicon-chromium alloy composite powder from step 2, including the following process: Add 0.1% zinc stearate as a release agent and 0.1% binder by mass to the above composite powder, mix evenly, and then cold press it under 95 N pressure using a mold to obtain an inductor blank.

[0049] The inductor blank is subjected to gradient sintering, and the specific process is as follows: The temperature is increased from room temperature to 150°C at a rate of 2°C / min, and held at that temperature for 2 hours. Continue to increase the temperature to 250℃ at a rate of 2℃ / min, and hold for 2 hours; Then increase the temperature to 600℃ at a rate of 3℃ / min and hold for 3 hours; Finally, the furnace is cooled to obtain the final inductance.

[0050] The obtained iron-silicon-chromium alloy composite material has a magnetic permeability μi of 43.2 and a loss of 328.8 under a test condition of 100 kHz.

[0051] Example 3 A method for preparing a high-permeability, low-loss iron-silicon-chromium alloy composite material includes the following steps: Step 1: Prepare pre-dispersed composite powder; By mass percentage, 97% of iron-silicon-chromium magnetic powder (containing 4.0–6.0% Si, 4.0–6.0% Cr, and the balance Fe) was mixed with 3% of nano-alumina powder. The mixture was fed into a planetary ball mill, and 5% (by mass) of alcohol was added as a process control agent. The mill was ball-milled for 8 hours at 300 r / min to obtain a pre-dispersed composite powder precursor. This precursor was then placed in an oven and dried at 80°C for 8 hours to completely remove the alcohol, yielding a dry pre-dispersed composite powder.

[0052] Step 2: Preparation of iron-silicon-chromium alloy composite material Preparation of epoxy resin-acetone coating solution: Mix epoxy resin A and epoxy resin B in a mass ratio of 8:1, then add acetone equal to the total mass of epoxy resin, and stir for 20 minutes to form a homogeneous and transparent epoxy resin-acetone solution.

[0053] The epoxy resin-acetone solution was added to the pre-dispersed composite powder, with epoxy resin A being added at 4% of the pre-dispersed composite powder mass. The mixture was thoroughly stirred in a closed system to ensure uniform wetting and coating of all powder particles. The wet material was then dried at 80°C for 2 hours until the acetone completely evaporated and the epoxy resin was initially cured. The dried material was then subjected to secondary dry granulation and passed through a 60-200 mesh sieve to obtain the iron-silicon-chromium alloy composite powder.

[0054] Furthermore, the inductor is prepared using the iron-silicon-chromium alloy composite powder from step 2, including the following process: Add 0.1% zinc stearate as a release agent and 0.1% binder by mass to the above-mentioned iron-silicon-chromium alloy composite powder, mix evenly, and then cold press it under 95 N pressure using a mold to obtain an inductor blank.

[0055] The inductor blank is subjected to gradient sintering, and the specific process is as follows: The temperature is increased from room temperature to 150°C at a rate of 2°C / min and held for 2 hours. Continue to increase the temperature to 250℃ at a rate of 2℃ / min, and hold for 2 hours; Then increase the temperature to 600℃ at a rate of 3℃ / min and hold for 3 hours; Finally, the inductor is cooled in the furnace to obtain the final inductor element.

[0056] The obtained iron-silicon-chromium alloy composite material has a magnetic permeability μi of 42.3 and a loss of 337.6 under a test condition of 100 kHz.

[0057] Example 4 A method for preparing a high-permeability, low-loss iron-silicon-chromium alloy composite material includes the following steps: Step 1: Prepare pre-dispersed composite powder; By mass percentage, 96% of iron-silicon-chromium magnetic powder (containing 4.0–6.0% Si, 4.0–6.0% Cr, and the remainder Fe) was mixed with 4% of nano-alumina powder. The mixture was fed into a planetary ball mill, and 5% (by mass) of alcohol was added as a process control agent. The mill was ball-milled for 8 hours at 300 r / min to obtain a pre-dispersed composite powder precursor. This precursor was then placed in an oven and dried at 80°C for 8 hours to completely remove the alcohol, yielding a dry pre-dispersed composite powder.

[0058] Step 2: Prepare an epoxy resin-acetone coating solution for the iron-silicon-chromium alloy composite material: Mix epoxy resin A and epoxy resin B at a mass ratio of 8:1, then add acetone equal to the total mass of the epoxy resin, and stir for 20 minutes until a homogeneous and transparent epoxy resin-acetone solution is formed.

[0059] The epoxy resin-acetone solution was added to the pre-dispersed composite powder, with epoxy resin A being added at 4% of the pre-dispersed composite powder mass. The mixture was thoroughly stirred in a closed system to ensure uniform wetting and coating of all powder particles. The wet material was then dried at 80°C for 2 hours until the acetone completely evaporated and the epoxy resin was initially cured. The dried material was then subjected to secondary dry granulation and passed through a 60-200 mesh sieve to obtain the iron-silicon-chromium alloy composite powder.

[0060] Furthermore, the inductor is prepared using the iron-silicon-chromium alloy composite powder from step 2, including the following process: Add 0.1% zinc stearate as a release agent and 0.1% binder to the above composite powder, mix evenly, and then cold press it under 95 N pressure using a mold to obtain an inductor blank.

[0061] The inductor blank is subjected to gradient sintering, and the specific process is as follows: The temperature is increased from room temperature to 150°C at a rate of 2°C / min and held for 2 hours. Continue to increase the temperature to 250℃ at a rate of 2℃ / min, and hold for 2 hours; Then increase the temperature to 600℃ at a rate of 3℃ / min and hold for 3 hours; Finally, the inductor is cooled in the furnace to obtain the final inductor element.

[0062] The obtained iron-silicon-chromium alloy composite material has a magnetic permeability μi of 39.4 and a loss of 362.7 under a test condition of 100 kHz.

[0063] Example 5 99.5% iron-silicon-chromium magnetic powder and 0.5% nano-alumina powder were weighed according to the mass ratio, and 3% alcohol was added. The mixture was ball-milled at 150 r / min for 6 hours and dried at 70℃ for 6 hours to obtain a pre-dispersed powder. An acetone solution of epoxy resin A:B glue = 6:1 was prepared, and A glue was added at 4% of the powder mass. After mixing, the mixture was dried at 70℃ for 1 hour, and then granulated and sieved to obtain a composite powder. 0.1% zinc stearate and 0.05% binder were added, and the mixture was pressed into shape at 85 N. A sample ring was obtained by gradient sintering (heating at 2℃ / min, holding at 100℃, 200℃, and 550℃ for 1, 1, and 2 hours respectively). The magnetic permeability μi was measured to be 36.8@100kHz, and the loss was 365.2 kW / m³.

[0064] Example 6 95.5% iron-silicon-chromium magnetic powder and 4.5% nano-alumina powder were weighed according to the mass ratio, 5% alcohol was added, and the mixture was ball-milled at 300 r / min for 8 hours. The powder was then dried at 80℃ for 8 hours to obtain a pre-dispersed powder. An acetone solution of epoxy resin A:B glue = 8:1 was prepared, and A glue was added at 6% of the powder mass. After mixing, the mixture was dried at 80℃ for 2 hours, granulated, and sieved to obtain a composite powder. 0.2% zinc stearate and 0.1% binder were added, and the mixture was pressed into shape at 95 N. A sample ring was obtained by gradient sintering (heating at 3℃ / min, holding at 150℃, 250℃, and 600℃ for 2, 2, and 3 hours respectively). The magnetic permeability μi = 38.1 @ 100kHz and the loss was 370.5 kW / m³.

[0065] Comparative Example 1 This comparative example provides a method for preparing an iron-silicon-chromium alloy composite material using only organic coating, to compare and verify the technical advantages of the iron-silicon-chromium alloy composite material proposed in this invention. Nano-alumina is not introduced in this comparative example; the specific steps are as follows: Step 1: Weigh 100% iron-silicon-chromium magnetic powder (with Si content of 4.0-6.0%, Cr content of 4.0-6.0%, and the remainder being Fe) by mass percentage, without adding any inorganic insulating materials.

[0066] Step 2: Prepare epoxy resin-acetone coating solution: Mix epoxy resin A and epoxy resin B in a mass ratio of 8:1, then add acetone equal to the total mass of the epoxy resin, and stir for 20 minutes until a homogeneous and transparent epoxy resin-acetone solution is formed.

[0067] The epoxy resin-acetone solution was directly added to the iron-silicon-chromium magnetic powder, with the amount of epoxy resin A being 4% of the magnetic powder mass. The mixture was thoroughly mixed in a closed system to ensure the solution uniformly coated all powder particles. The wet material was then dried at 80°C for 2 hours until the acetone completely evaporated and the epoxy resin was initially cured. The dried material underwent a second dry granulation process and passed through a 60-200 mesh sieve to obtain a single organic-coated iron-silicon-chromium alloy composite powder.

[0068] Step 3: Add 0.1% by weight of zinc stearate as a release agent and 0.1% by weight of binder to the above-mentioned single organic-coated iron-silicon-chromium alloy composite powder. After mixing evenly, use a mold to cold press and form it under 95 N pressure to obtain a sample ring blank.

[0069] The sample ring blank is subjected to gradient sintering, and the specific process is as follows: The temperature is increased from room temperature to 150°C at a rate of 2°C / min and held for 2 hours. Continue to increase the temperature to 250℃ at a rate of 2℃ / min, and hold for 2 hours; Then increase the temperature to 600℃ at a rate of 3℃ / min and hold for 3 hours; Finally, the sample ring was cooled in the furnace to obtain the final sample ring.

[0070] The Fe-Si-Cr powders prepared in Examples 1-6 and Comparative Example 1 were sintered and wound into rings. The inductance of the samples was measured using an E4980AL inductance meter, and the permeability was calculated using a formula. The test conditions were a frequency f = 100 kHz and a typical voltage of 1 V. Density was tested using the Archimedes displacement method. Loss performance was tested using a SY-8218B analyzer under the following conditions: 100 kHz, 50 mT, and 25 °C. The test results are shown in Table 1 below. Table 1

[0071] As can be seen from the performance data of the above embodiments and comparative examples, the performance of Examples 1-6 is generally higher than that of the comparative examples. Among the six embodiments, Example 2 exhibits the best performance, with a permeability of 43.2, a quality factor of 62.1, and a loss of 328.8. Compared to the comparative examples, the permeability of the Fe-Si-Cr magnetic powder doped with nano-alumina and coated with epoxy resin described in this invention is significantly higher. The permeability of Fe-Si-Cr materials increased by 50%, the molding density became larger and more stable, losses decreased by 18% under the same conditions, and the quality factor also improved significantly. This indicates that the invention can effectively improve the magnetic permeability of Fe-Si-Cr materials, reduce their losses, and enhance the overall performance of the material.

[0072] Example 7 An inductor made of the aforementioned iron-silicon-chromium alloy composite material.

[0073] Example 8 A device comprising the inductor of embodiment 7; The equipment includes smart terminal devices and power equipment; Smart terminal devices include, but are not limited to, smartphones, tablets, laptops, and wearable devices; Power equipment includes, but is not limited to, high-frequency transformers, energy storage components, power inductors, and switching power supply modules.

[0074] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A high-permeability, low-loss iron-silicon-chromium alloy composite material, characterized in that, It includes iron-silicon-chromium alloy powder, nano-alumina powder dispersed and attached to the surface of the iron-silicon-chromium alloy powder, and an epoxy resin layer coated on the surface of the iron-silicon-chromium alloy powder. The composite material contains 0.5% to 5% nano-alumina powder and 95% to 99.5% iron-silicon-chromium alloy powder by mass fraction.

2. The high permeability, low loss iron-silicon-chromium alloy composite material according to claim 1, characterized in that, The iron-silicon-chromium alloy powder contains, by mass percentage, 4.0%–6.0% Si, 4.0%–6.0% Cr, and the balance is Fe.

3. The high permeability, low loss iron-silicon-chromium alloy composite material according to claim 1, characterized in that, The iron-silicon-chromium alloy composite material has a magnetic permeability μi ≥ 43.2 and a loss ≤ 328.8 kW / m at a frequency of 100 kHz. 3 .

4. A method for preparing a high-permeability, low-loss iron-silicon-chromium alloy composite material according to any one of claims 1-3, characterized in that, Includes the following steps: Step S1: Disperse 0.5% to 5% of nano-alumina powder by mass percentage and attach it to the surface of 95% to 99.5% of iron-silicon-chromium alloy powder to obtain pre-dispersed composite powder. Step S2: Coat the surface of the pre-dispersed composite powder with epoxy resin to obtain the iron-silicon-chromium alloy composite material; The epoxy resin adhesive includes epoxy resin A and epoxy resin B, and the ratio of epoxy resin A to epoxy resin B is (6-8):

1.

5. The method for preparing the high-permeability, low-loss iron-silicon-chromium alloy composite material according to claim 4, characterized in that, The specific method for preparing the pre-dispersed composite powder is as follows: The nano-alumina powder and the iron-silicon-chromium alloy powder are ball-milled to obtain a pre-dispersed composite powder precursor. Then, the process control agent of the ball milling process is removed to obtain the pre-dispersed composite powder.

6. The method for preparing the high-permeability, low-loss iron-silicon-chromium alloy composite material according to claim 4, characterized in that, The preparation method of the iron-silicon-chromium alloy composite material is as follows: An epoxy resin-acetone solution is added to the pre-dispersed composite powder. The powder is then wet-mixed to ensure that the resin solution uniformly impregnates and coats the powder. The powder is then dried to remove the solvent acetone. Finally, the powder is granulated twice and sieved to obtain the iron-silicon-chromium alloy composite material.

7. The method for preparing the high-permeability, low-loss iron-silicon-chromium alloy composite material according to claim 6, characterized in that, The preparation method of the iron-silicon-chromium alloy composite material is as follows: Epoxy resin A and epoxy resin B are mixed at a mass ratio of (6-8):1, and then acetone equal in mass to the total mass of the epoxy resin is added. The mixture is stirred until homogeneous to obtain epoxy resin. Acetone solution; The epoxy resin An acetone solution is added to the pre-dispersed composite powder to make the epoxy resin... The pre-dispersed composite powder is coated with acetone solution to obtain a mixture; wherein the amount of epoxy resin A glue added is 4% to 6% of the total mass of the pre-dispersed composite powder; The mixture was heated at 70°C. Dry at 80℃ for 1 minute 2 hours, until the acetone has completely evaporated to obtain a dry mixture; The dried mixture is then dry-granulated, passing through a 60°C filter. The iron-silicon-chromium alloy composite material was obtained by sieving through a 200-mesh screen.

8. An inductor, characterized in that, It is made of a high-permeability, low-loss iron-silicon-chromium alloy composite material as described in any one of claims 1-3.

9. A method for preparing the inductor according to claim 8, characterized in that, Includes the following steps: Using as claimed in claim 1 Pressed inductor blanks of high permeability and low loss iron-silicon-chromium alloy composite materials as described in any one of the three claims; The inductor blank is subjected to gradient sintering to obtain the inductor; The gradient sintering includes: From room temperature at 2 Heating to 100°C at a rate of 3°C / min 150℃, heat preservation 1 2 h; Continue with 2 Heating to 200°C at a rate of 3°C / min 250℃, heat preservation 1 2 h; Then use 2 Heating to 550°C at a rate of 3°C / min 600℃, heat preservation 2 3 h; Finally, it is cooled in the furnace.

10. A device, characterized in that, Including the inductor as described in claim 8; The equipment includes smart terminal devices and power equipment.

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