Magnetic powder core and preparation method thereof

Abstract

The invention discloses a magnetic powder core and a preparation method thereof. The preparation method of the magnetic powder core comprises the four steps of preparation of gas atomization iron-silicon soft magnetic powder, insulation coating, compression molding and annealing heat treatment. The iron-silicon soft magnetic powder is prepared through a gas atomization process, so that the iron-silicon soft magnetic powder has very good soft magnetic performance and has the advantages of low price, high magnetic conductivity, high resistivity, low coercive force, low loss, stable direct current bias characteristic and good temperature stability. Then, the iron-silicon soft magnetic powder is subjected to insulation coating; due to the fact that the aerosolized iron-silicon magnetic powder base body is subjected to preheating activation, ball milling through the insulation modifier and the heat treatment process, the magnetic conductivity and the insulation performance of the obtained iron-silicon powder product are improved in a coordinated mode; and after compression molding and annealing heat treatment, a high-temperature-resistant and corrosion-resistant magnetic powder core product is finally obtained.

Description

Technical Field

[0001] The present invention relates to the field of preparation of alloy soft magnetic materials, in particular to a magnetic powder core and a preparation method thereof. Background Art

[0002] Metallic soft magnetic materials are important basic functional materials in the electronics industry. Compared to traditional ferrite soft magnetic materials, metallic soft magnetic powder cores, due to their internal pore structure, are less susceptible to magnetic flux leakage at high frequencies and less prone to saturation under strong DC current conditions. They are suitable for the manufacture of electronic components such as power factor correctors, switching regulators, in-line noise filters, and pulse flyback transformers. They are widely used in a wide range of fields, including new energy vehicles, photovoltaics, information communications, and consumer electronics. Among the iron-based soft magnetic materials, iron silicon powder and its powder cores offer the highest cost-performance ratio and are among the largest-volume materials in the metallic soft magnetic material market.

[0003] In order to improve the magnetic permeability performance of the product, the existing iron silicon magnetic powder is likely to affect the insulation of the product. At the same time, the product has poor high temperature resistance and corrosion resistance, which limits the product's use efficiency. Summary of the Invention

[0004] The purpose of the present invention is to provide a magnetic powder core and a preparation method thereof, so as to solve the problem of poor high temperature resistance and corrosion resistance of the above-mentioned magnetic powder core.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for preparing a magnetic powder core, comprising the following steps:

[0007] S1: preparing aerosolized iron-silicon soft magnetic powder, wherein the aerosolized iron-silicon soft magnetic powder comprises the following elements by weight percentage: Si: 4.5-6.5%, Ni: <0.05%, Cr: <0.05%, Cu: <0.05%, C: <0.03%, Mn: <0.05%, P: <0.04%, S: <0.03%, and the balance is Fe;

[0008] S2: Insulation coating: Insulation coating of aerosolized iron silicon soft magnetic powder, including the following steps:

[0009] S21: preheating and activating the aerosolized iron-silicon soft magnetic powder obtained in S1 to obtain a preheated and activated iron-silicon magnetic powder matrix;

[0010] S22: The preheated activated iron silicon magnetic powder matrix and the insulating modifier are subjected to ball milling coating treatment in a weight ratio of 5:3, with a ball milling speed of 1000-1500 r / min for 1 hour to obtain an insulating coated soft magnetic powder;

[0011] The insulating modifier includes a dopamine modified liquid and a forsterite-nano titanium dioxide sintered body, wherein the mass ratio of the dopamine modified liquid to the forsterite-nano titanium dioxide sintered body is (5-8):3;

[0012] S3: Pressing and molding: Screening the insulating coated soft magnetic powder before pressing, then mixing the screened insulating coated soft magnetic powder with a release agent and pressing it into a magnetic powder core matrix;

[0013] S4: Annealing heat treatment: Perform high-temperature annealing heat treatment on the magnetic powder core matrix to obtain a magnetic powder core.

[0014] In the preparation method of the magnetic powder core, the preparation method of the dopamine modification liquid is:

[0015] S201: first add 5 to 8 parts of dopamine hydrochloride to 25 to 30 parts of water, then add 2 to 4 parts of sodium silicate solution and 1 to 3 parts of silane coupling agent, and stir evenly to obtain a dopamine-based medium liquid;

[0016] S202: heating and stirring the nano-calcium carbonate, dimethylhydroxy silicone oil, and silane coupling agent in a weight ratio of 3:7:1 until the stirring is completed to obtain a nano-calcium carbonate solution;

[0017] The specific operation steps of the heating and stirring treatment are:

[0018] First, stir at a temperature of 50-55°C and a speed of 350-400 r / min for 1 h, maintain a constant speed, then heat to 70°C at a rate of 1-3°C / min and continue stirring for 2 h;

[0019] S203: adding 5 to 8 parts of halloysite and 2 to 5 parts of silicon carbide to 5 to 8 parts of a 5% by mass lanthanum chloride solution, stirring thoroughly, then filtering, drying, sintering at 150 to 170° C. for 1 hour, and finally air cooling to room temperature to obtain a halloysite / silicon carbide composite;

[0020] S204: 3-5 parts of halloysite / silicon carbide composite, 1-2 parts of sodium metaborate, and 2-4 parts of cerium oxide are added to 5-8 parts of nano-calcium carbonate solution and ball-milled at a speed of 1500 rpm for 1 hour. After the ball milling is completed, the mixture is filtered and dried to obtain a modified nano-filler.

[0021] S205: ultrasonically treating the modified nanofiller and the dopamine-based medium at a weight ratio of 2:5, and completing the ultrasonic treatment to obtain a dopamine-modified liquid;

[0022] The silane coupling agent is silane coupling agent KH550; the mass of the sodium silicate solution is 2-5%; the ultrasonic power of the ultrasonic treatment is 350-400W, and the ultrasonic time is 1 hour.

[0023] In the preparation method of the magnetic powder core, the average particle size of the halloysite is 3.5 to 5 μm, and the average aspect ratio is 7 to 12.

[0024] In the preparation method of the magnetic powder core, the preparation method of the forsterite-nano-titanium dioxide sintered body is:

[0025] S206: dispersing 2 to 4 parts of nano-silica sol into 5 to 8 parts of chitosan solution, then adding 1 to 2 parts of sodium carboxymethyl cellulose, and stirring to obtain a modified solution; the mass fraction of the chitosan solution is 3 to 4%;

[0026] S207: 5 to 8 parts of nano-titanium dioxide and 1 to 3 parts of barium sulfate are immersed in 6 to 10 parts of the modified solution and stirred thoroughly, and then filtered and dried to obtain a modified nano-titanium dioxide;

[0027] S208: ball milling 4 to 7 parts of the modified nano-titanium dioxide, 2 to 5 parts of forsterite, and 3 to 5 parts of a 5% by mass yttrium nitrate solution at a rotation speed of 750 to 1050 r / min for 2 hours; after the ball milling, filtering and drying, and then calcining to obtain a forsterite-nano-titanium dioxide sintered body;

[0028] The specific steps of the thermal calcination treatment are: first heating to 175°C at a rate of 1-3°C / min, sintering for 1 hour, then heating to 300°C at a rate of 2-4°C / min, keeping warm for 45 minutes, and finally air cooling to room temperature.

[0029] In the preparation method of the magnetic powder core, the preheating activation temperature is 350-370° C., and the activation time is 20 minutes.

[0030] In the method for preparing the magnetic powder core, in step S3, the mesh size of the sieve before pressing is 80-200 meshes, and the amount of the release agent added accounts for 0.3-0.6% of the total weight of the insulating coated soft magnetic powder and the release agent.

[0031] In the method for preparing the magnetic powder core, in step S4, the annealing temperature of the high-temperature annealing heat treatment is 650-850° C., and the annealing time is 30-120 minutes.

[0032] In the method for preparing the magnetic powder core, in step S1, the following steps are included:

[0033] S11: Proportioning: Weigh the gas atomized iron-silicon soft magnetic powder raw material, the slag remover and the deoxidizer according to the proportion;

[0034] S12: Alloy smelting: heating and smelting the gas atomized iron-silicon soft magnetic powder raw material, adding a slag remover and a deoxidizer, and stirring; after stirring, standing and removing the slag to obtain an alloy melt;

[0035] S13: Gas atomization powder making: The alloy melt is poured into a tundish, and the alloy melt flows into the gas atomization chamber from the guide pipe at the bottom of the tundish. The alloy melt is atomized by high-pressure nitrogen gas, and the alloy melt is broken into droplets. After cooling and solidification, the droplets are settled to obtain semi-finished powder;

[0036] S14: Screening: After the semi-finished product powder is cooled to room temperature, it is screened once; then it is annealed in high-temperature nitrogen and screened twice to obtain aerosolized iron-silicon soft magnetic powder.

[0037] In the method for preparing the magnetic powder core, in step S11, the amount of the slag remover added is 0.15-0.35% of the total mass of the aerosolized iron silicon soft magnetic powder raw material, and the amount of the deoxidizer added is 0.20-0.40% of the aerosolized iron silicon soft magnetic powder raw material;

[0038] In step S12, the alloy is smelted at a temperature of 1600-1650° C. and the standing time is 0.5-2.5 min;

[0039] In step S13, the alloy melt pouring temperature is 1630-1660° C.; the pressure of the high-pressure nitrogen is 3.5-5.0 MPa; and the temperature inside the tundish is 1000-1250° C.;

[0040] The material of the flow guide tube is boron nitride or zirconium oxide, and the diameter of the flow guide tube is 4.0 to 7.0 mm;

[0041] In the step S14, the mesh size of the first screening is 60-100 meshes, and the mesh size of the second screening is 100-325 meshes; and in the high-temperature nitrogen annealing treatment, the annealing temperature is 700-1050° C., and the annealing time is 25-60 minutes.

[0042] The present invention also provides a magnetic powder core, which is prepared by the above-mentioned method for preparing the magnetic powder core.

[0043] A technical solution in the present invention can have the following beneficial effects:

[0044] The method for preparing the magnetic powder core includes four steps: preparing aerosolized iron silicon soft magnetic powder, insulating coating, pressing and forming, and annealing heat treatment. The iron silicon soft magnetic powder is prepared by an aerosolization process, so that the iron silicon soft magnetic powder has excellent soft magnetic properties and has the advantages of low price, high magnetic permeability, high resistivity, low coercivity, low loss, stable DC bias characteristics, and good temperature stability. Subsequently, the iron silicon soft magnetic powder is insulatingly coated; because the aerosolized iron silicon magnetic powder matrix is preheated and activated, then ball-milled with an insulating modifier, and then prepared in conjunction with a heat treatment process, the magnetic permeability and insulation properties of the obtained iron silicon powder product are coordinated and improved; after pressing and annealing heat treatment, a high temperature resistant and corrosion-resistant magnetic powder core product is finally obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a microscopic morphology of the gas-atomized iron-silicon soft magnetic powder obtained in Example 1 of the present invention;

[0046] Figure 2 This is a microscopic morphology of the gas-atomized iron-silicon soft magnetic powder obtained in Example 2 of the present invention;

[0047] Figure 3 This is a microscopic morphology of the gas-atomized iron-silicon soft magnetic powder obtained in Example 3 of the present invention;

[0048] Figure 4 This is a microscopic morphology of the gas-atomized iron-silicon soft magnetic powder obtained in Example 4 of the present invention. DETAILED DESCRIPTION

[0049] The technical solution of the present invention will be further illustrated below by way of specific embodiments. To facilitate understanding of the present invention, the present invention will be described in more detail below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of the present invention.

[0050] If no specific techniques or conditions are specified in the examples, the experiments were carried out according to the techniques or conditions described in the literature in the field or according to the product instructions. All reagents or instruments used without specifying the manufacturer are commercially available conventional products.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0052] The present invention provides a method for preparing a magnetic powder core, comprising the following steps:

[0053] S1: preparing aerosolized iron-silicon soft magnetic powder, wherein the aerosolized iron-silicon soft magnetic powder comprises the following elements by weight percentage: Si: 4.5-6.5%, Ni: <0.05%, Cr: <0.05%, Cu: <0.05%, C: <0.03%, Mn: <0.05%, P: <0.04%, S: <0.03%, and the balance is Fe;

[0054] S2: Insulation coating: Insulation coating of aerosolized iron silicon soft magnetic powder, including the following steps:

[0055] S21: preheating and activating the aerosolized iron-silicon soft magnetic powder obtained in S1 to obtain a preheated and activated iron-silicon magnetic powder matrix;

[0056] S22: The preheated activated iron silicon magnetic powder matrix and the insulating modifier are subjected to ball milling coating treatment in a weight ratio of 5:3, with a ball milling speed of 1000-1500 r / min for 1 hour to obtain an insulating coated soft magnetic powder;

[0057] The insulating modifier includes a dopamine modified liquid and a forsterite-nano titanium dioxide sintered body, wherein the mass ratio of the dopamine modified liquid to the forsterite-nano titanium dioxide sintered body is (5-8):3;

[0058] S3: Pressing and molding: Screening the insulating coated soft magnetic powder before pressing, then mixing the screened insulating coated soft magnetic powder with a release agent and pressing it into a magnetic powder core matrix;

[0059] S4: Annealing heat treatment: Perform high-temperature annealing heat treatment on the magnetic powder core matrix to obtain a magnetic powder core.

[0060] The magnetic powder core preparation method includes four steps: preparing aerosolized iron-silicon soft magnetic powder, insulating and coating, pressing and forming, and annealing. The iron-silicon soft magnetic powder prepared through the aerosol process exhibits excellent soft magnetic properties, low cost, high magnetic permeability, high resistivity, low coercivity, low loss, stable DC bias characteristics, and good temperature stability.

[0061] Subsequently, the iron silicon soft magnetic powder is insulated and coated; since the aerosolized iron silicon magnetic powder matrix is preheated and activated, then ball-milled with an insulating modifier, and then processed with a heat treatment process, the magnetic permeability and insulation properties of the obtained iron silicon powder product are coordinated and improved; after pressing and annealing heat treatment, a high-temperature and corrosion-resistant magnetic powder core product is finally obtained.

[0062] The insulating modifier is prepared by blending and co-formulating a dopamine-modified liquid with a forsterite-nano-titania sintered body. The dopamine-modified liquid is prepared by blending dopamine hydrochloride, water, sodium silicate solution and a silane coupling agent. The raw materials are coordinated and used as a matrix agent, and the modified nano-filler is dispersed in a dopamine-based medium liquid to facilitate better blending and co-formulating with the forsterite-nano-titania sintered body, thereby improving the aerosolized iron silicon magnetic powder matrix and further improving the product performance.

[0063] In a specific embodiment, the pressing pressure of the pressing molding is 10 to 30 T / cm 2 .

[0064] Specifically, the preparation method of the dopamine modified liquid is:

[0065] S201: first add 5 to 8 parts of dopamine hydrochloride to 25 to 30 parts of water, then add 2 to 4 parts of sodium silicate solution and 1 to 3 parts of silane coupling agent, and stir evenly to obtain a dopamine-based medium liquid;

[0066] S202: heating and stirring the nano-calcium carbonate, dimethylhydroxy silicone oil, and silane coupling agent in a weight ratio of 3:7:1 until the stirring is completed to obtain a nano-calcium carbonate solution;

[0067] The specific operation steps of the heating and stirring treatment are:

[0068] First, stir at a temperature of 50-55°C and a speed of 350-400 r / min for 1 h, maintain a constant speed, then heat to 70°C at a rate of 1-3°C / min and continue stirring for 2 h;

[0069] S203: adding 5 to 8 parts of halloysite and 2 to 5 parts of silicon carbide to 5 to 8 parts of a 5% by mass lanthanum chloride solution, stirring thoroughly, then filtering, drying, sintering at 150 to 170° C. for 1 hour, and finally air cooling to room temperature to obtain a halloysite / silicon carbide composite;

[0070] S204: 3-5 parts of halloysite / silicon carbide composite, 1-2 parts of sodium metaborate, and 2-4 parts of cerium oxide are added to 5-8 parts of nano-calcium carbonate solution and ball-milled at a speed of 1500 rpm for 1 hour. After the ball milling is completed, the mixture is filtered and dried to obtain a modified nano-filler.

[0071] S205: ultrasonically treating the modified nanofiller and the dopamine-based medium at a weight ratio of 2:5, and completing the ultrasonic treatment to obtain a dopamine-modified liquid;

[0072] The silane coupling agent is silane coupling agent KH550; the mass of the sodium silicate solution is 2-5%; the ultrasonic power of the ultrasonic treatment is 350-400W, and the ultrasonic time is 1 hour.

[0073] The modified nanofiller is treated by heating and stirring nano-calcium carbonate, dimethylhydroxy silicone oil, and silane coupling agent KH560, which can optimize the interfacial insulation of nano-calcium carbonate and better blend the halloysite / silicon carbide composite, sodium metaborate, and cerium oxide. The halloysite / silicon carbide composite is prepared by thoroughly stirring halloysite, silicon carbide, and a 5% by mass lanthanum chloride solution, then filtering, drying, and sintering at 150-170°C for 1 hour. The resulting halloysite / silicon carbide composite enhances the performance stability of the system. By co-blending the modified nanofiller raw materials, the product's performance is further improved.

[0074] Specifically, the average particle size of the halloysite is 3.5-5 μm, and the average aspect ratio is 7-12.

[0075] The halloysite with the above-mentioned particle size and aspect ratio can be better composited with silicon carbide, thereby improving the stability of the halloysite / silicon carbide composite.

[0076] Specifically, the preparation method of the forsterite-nano titanium dioxide sintered body is:

[0077] S206: dispersing 2 to 4 parts of nano-silica sol into 5 to 8 parts of chitosan solution, then adding 1 to 2 parts of sodium carboxymethyl cellulose, and stirring to obtain a modified solution; the mass fraction of the chitosan solution is 3 to 4%;

[0078] S207: 5 to 8 parts of nano-titanium dioxide and 1 to 3 parts of barium sulfate are immersed in 6 to 10 parts of the modified solution and stirred thoroughly, and then filtered and dried to obtain a modified nano-titanium dioxide;

[0079] S208: ball milling 4 to 7 parts of the modified nano-titanium dioxide, 2 to 5 parts of forsterite, and 3 to 5 parts of a 5% by mass yttrium nitrate solution at a rotation speed of 750 to 1050 r / min for 2 hours; after the ball milling, filtering and drying, and then calcining to obtain a forsterite-nano-titanium dioxide sintered body;

[0080] The specific steps of the thermal calcination treatment are: first heating to 175°C at a rate of 1-3°C / min, sintering for 1 hour, then heating to 300°C at a rate of 2-4°C / min, keeping warm for 45 minutes, and finally air cooling to room temperature.

[0081] The forsterite-nano titanium dioxide sintered body is treated by immersing nano titanium dioxide and barium sulfate in a modified solution, and the modified solution is prepared by blending nano silica sol, chitosan solution and sodium carboxymethyl cellulose; at the same time, the forsterite and yttrium nitrate solution with a mass fraction of 5% are ball-milled, and the raw materials are combined and coordinated, with nano titanium dioxide and forsterite as the matrix, and then subjected to heat calcination treatment, heated to 175°C at a rate of 1-3°C / min, sintered for 1 hour, and then heated to 300°C at a rate of 2-4°C / min, and kept warm for 45 minutes.

[0082] A step-by-step thermal calcination improvement process is adopted to enhance the matrix activity of nano-titanium dioxide and forsterite, so that they can better cooperate with the dopamine modification liquid, thereby improving the coating of the aerosolized iron silicon soft magnetic powder and further improving the performance of the product.

[0083] Specifically, the preheating activation temperature is 350-370° C., and the activation time is 20 minutes.

[0084] The above temperature can remove surface adsorbents and volatiles, eliminate the oxide layer or passivation film, and activate the surface of the magnetic powder particles to improve their diffusion ability, provide kinetic conditions for grain growth and densification in subsequent high-temperature annealing or sintering processes, promote sintering activity, and optimize the soft magnetic properties of the magnetic core.

[0085] Specifically, in the step S3, the mesh size of the sieve before pressing is 80-200 meshes, and the added amount of the release agent accounts for 0.3-0.6% of the total weight of the insulating coated soft magnetic powder and the release agent.

[0086] By screening the powder before pressing, large particles are prevented from scratching the mold surface during pressing, thus extending the mold life. At the same time, the large particles of insulating coated soft magnetic powder are prevented from causing local oxidation or grain boundary defects during the annealing process, which leads to increased core loss or decreased mechanical strength.

[0087] The release agent lubricates the contact interface between the mold surface and the magnetic powder particles, reducing the friction between the two, thereby reducing the demolding resistance and reducing the occurrence of mold sticking after pressing; moreover, it can also be coated on the surface of the insulating coated soft magnetic powder, reducing the adhesion between particles, enhancing the fluidity of the powder, making the powder more evenly distributed in the mold, reducing the density gradient of the green body after pressing, and improving the consistency of the magnetic properties of the magnetic powder core.

[0088] Specifically, in step S4, the annealing temperature of the high temperature annealing heat treatment is 650-850° C., and the annealing time is 30-120 minutes.

[0089] Annealing temperature and time directly affect the microstructure of the magnetic powder core. Using annealing temperature and time within the above range can maximize the magnetic properties while avoiding the risk of crystallization or oxidation.

[0090] Furthermore, in step S1, the following steps are included:

[0091] S11: Proportioning: Weigh the gas atomized iron-silicon soft magnetic powder raw material, the slag remover and the deoxidizer according to the proportion;

[0092] S12: Alloy smelting: heating and smelting the gas atomized iron-silicon soft magnetic powder raw material, adding a slag remover and a deoxidizer, and stirring; after stirring, standing and removing the slag to obtain an alloy melt;

[0093] S13: Gas atomization powder making: The alloy melt is poured into a tundish, and the alloy melt flows into the gas atomization chamber from the guide pipe at the bottom of the tundish. The alloy melt is atomized by high-pressure nitrogen gas, and the alloy melt is broken into droplets. After cooling and solidification, the droplets are settled to obtain semi-finished powder;

[0094] S14: Screening: After the semi-finished product powder is cooled to room temperature, it is screened once; then it is annealed in high-temperature nitrogen and screened twice to obtain aerosolized iron-silicon soft magnetic powder.

[0095] By adopting the above steps, the purpose of low-temperature melting and low-temperature atomization can be achieved, and then high-pressure nitrogen atomization is used to prepare iron-silicon soft magnetic powder, which can overcome the problem of oxidation slag caused by the different melting points of iron and silicon in a non-vacuum state, thereby avoiding the problem of oxidation slag clogging the leak nozzle and causing the atomization process to be unable to continue. The atomization process is realized in a non-vacuum state, which can avoid the use of expensive vacuum equipment and complicated vacuum pumping operations. The production process is simple and the production efficiency is high, which can greatly reduce production costs.

[0096] Furthermore, in the step S11, the amount of the slag remover added is 0.15-0.35% of the total mass of the atomized iron silicon soft magnetic powder raw material, and the amount of the deoxidizer added is 0.20-0.40% of the total mass of the atomized iron silicon soft magnetic powder raw material;

[0097] In step S12, the alloy is smelted at a temperature of 1600-1650° C. and the standing time is 0.5-2.5 min;

[0098] In step S13, the alloy melt pouring temperature is 1630-1660° C.; the pressure of the high-pressure nitrogen is 3.5-5.0 MPa; and the temperature inside the tundish is 1000-1250° C.;

[0099] The material of the flow guide tube is boron nitride or zirconium oxide, and the diameter of the flow guide tube is 4.0 to 7.0 mm;

[0100] In the step S14, the mesh size of the first screening is 60-100 meshes, and the mesh size of the second screening is 100-325 meshes; and in the high-temperature nitrogen annealing treatment, the annealing temperature is 700-1050° C., and the annealing time is 25-60 minutes.

[0101] The commercially available deslagging agent is F2, and the deoxidizer is calcium silicon particles. The deoxidizer reacts with oxygen in the alloy melt to form easily removable compounds. The deslagging agent is used to remove molten metal slag during the smelting process, preventing it from clogging the pipes and halting atomization.

[0102] The aerosolized iron silicon soft magnetic powder prepared by the above method has the advantages of good sphericity, low oxygen content, stable composition and high production efficiency. The prepared magnetic powder core has magnetic properties of high DC bias and low loss.

[0103] The present invention also provides a magnetic powder core, which is prepared by the above-mentioned method for preparing the magnetic powder core.

[0104] Example 1

[0105] A method for preparing a magnetic powder core comprises the following steps:

[0106] Preparation of aerosolized iron silicon soft magnetic powder comprises the following steps:

[0107] Mixing ratio: according to the mixing ratio, weigh the aerosolized iron silicon soft magnetic powder raw material, 0.20% slag remover and 0.30% deoxidizer; wherein the Si content in the aerosolized iron silicon soft magnetic powder is 5.5%;

[0108] Alloy smelting: The gas atomized iron-silicon soft magnetic powder raw material is heated and smelted, a slag remover and a deoxidizer are added, and the mixture is stirred; after stirring, the mixture is allowed to stand and the slag is removed to obtain an alloy melt; wherein, the alloy smelting temperature is 1630-1640°C, and the standing time is 1.5 minutes;

[0109] Gas atomization powder making: The alloy melt is poured into a tundish, and the alloy melt flows into the gas atomization chamber through the guide tube at the bottom of the tundish. High-pressure nitrogen is used to atomize the alloy melt, breaking it into droplets. After cooling and solidification, the droplets are settled to obtain semi-finished powder. The alloy melt pouring temperature is 1650-1660°C, the pressure of the high-pressure nitrogen is 4.7-4.8 MPa, and the temperature inside the tundish is 1200°C. The guide tube is made of boron nitride and has a diameter of 4.5 mm.

[0110] Sieving: After the temperature drops to room temperature, the semi-finished powder is sieved once; then subjected to high-temperature nitrogen annealing at 850°C for 60 minutes, and sieved twice to obtain aerosolized iron-silicon soft magnetic powder; wherein the mesh number of the first sieve is 100 mesh, and the mesh number of the second sieve is 325 mesh;

[0111] Insulation coating, including the following steps:

[0112] The preheated activated iron silicon magnetic powder matrix and the insulating modifier were subjected to ball milling coating treatment in a weight ratio of 5:3, with a ball milling speed of 1000 r / min and a ball milling time of 1 h to obtain an insulating coated soft magnetic powder;

[0113] The insulating modifier includes a dopamine modified liquid and a forsterite-nano titanium dioxide sintered body, wherein the mass ratio of the dopamine modified liquid to the forsterite-nano titanium dioxide sintered body is 5:3;

[0114] The preheating activation temperature in this embodiment is 350°C and the activation time is 20 minutes;

[0115] The preparation method of the dopamine modified liquid of this embodiment is:

[0116] First, 5 parts of dopamine hydrochloride were added to 25 parts of water, followed by 2 parts of sodium silicate solution and 1 part of silane coupling agent, and stirred evenly to obtain a dopamine-based medium liquid;

[0117] Preparation of modified nanofiller:

[0118] Nano-calcium carbonate, dimethylhydroxy silicone oil, and silane coupling agent were heated and stirred in a weight ratio of 3:7:1, and the stirring was completed to obtain a nano-calcium carbonate solution; the specific operation steps of the heating and stirring treatment were as follows: first, stirring at a temperature of 50° C. and a speed of 350 r / min for 1 hour, maintaining a constant speed, then heating to 70° C. at a rate of 1° C. / min, and continuing stirring for 2 hours;

[0119] 5 parts of halloysite and 2 parts of silicon carbide were added to 5 parts of 5% by mass lanthanum chloride solution and stirred thoroughly, then filtered and dried, and then sintered at 150°C for 1 hour, and finally air-cooled to room temperature to obtain a halloysite / silicon carbide composite;

[0120] 3 parts of halloysite / silicon carbide composite, 1 part of sodium metaborate and 2 parts of cerium oxide were added to 5 parts of nano calcium carbonate solution and ball milled at a speed of 1500 r / min for 1 hour. After the ball milling was completed, the mixture was filtered and dried to obtain a modified nano filler.

[0121] Ultrasonic treatment is performed on the modified nanofiller and the dopamine-based medium in a weight ratio of 2:5, and the ultrasonic treatment is terminated to obtain a dopamine-modified liquid;

[0122] The silane coupling agent in this embodiment is silane coupling agent KH550; the mass of the sodium silicate solution is 2%; the ultrasonic power of the ultrasonic treatment is 350W, and the ultrasonic time is 1 hour;

[0123] The average particle size of the halloysite in this example is 3.5 μm, and the average aspect ratio is 7;

[0124] The preparation method of the forsterite-nano titanium dioxide sintered body of this embodiment is as follows:

[0125] Disperse 2 parts of nano-silica sol into 5 parts of chitosan solution, then add 1 part of sodium carboxymethyl cellulose and stir evenly to obtain a modified solution; the mass fraction of the chitosan solution is 3%;

[0126] Immerse 5 parts of nano-titanium dioxide and 1 part of barium sulfate in 6 parts of the modified solution and stir thoroughly, then filter and dry to obtain a nano-titanium dioxide modified body;

[0127] 4 parts of nano-titanium dioxide modified body, 2 parts of forsterite and 3 parts of 5% by mass yttrium nitrate solution were ball-milled at a speed of 750 r / min for 2 hours; after the ball-milling, the mixture was filtered and dried, and then calcined to obtain a forsterite-nano-titanium dioxide sintered body;

[0128] The specific steps of the thermal calcination treatment are as follows: first, heating to 175°C at a rate of 1°C / min, sintering for 1 hour, then heating to 300°C at a rate of 2°C / min, keeping at that temperature for 45 minutes, and finally air cooling to room temperature;

[0129] Compression molding: The insulating coated soft magnetic powder is sieved before pressing, and then the sieved insulating coated soft magnetic powder is mixed with a release agent and pressed into a magnetic powder core matrix; wherein the mesh size of the sieve before pressing is 200 mesh, and the amount of the release agent added is 0.3% of the total weight of the insulating coated soft magnetic powder and the release agent;

[0130] Annealing heat treatment: The magnetic powder core substrate is subjected to high temperature annealing heat treatment at 745°C for 75 minutes to obtain a magnetic powder core.

[0131] Example 2

[0132] The steps of Example 2 are the same as those of Example 1, except that: in the step of preparing the aerosolized iron silicon soft magnetic powder, 0.35% of a slag remover and 0.40% of a deoxidizer are used; the Si content in the aerosolized iron silicon soft magnetic powder is 5.8%;

[0133] The annealing temperature of the high-temperature nitrogen annealing treatment is 850°C, and the annealing time is 60 minutes; the mesh number of the first screening is 60 mesh, and the mesh number of the second screening is 100 mesh;

[0134] The insulation coating step includes the following steps:

[0135] The preheated activated iron silicon magnetic powder matrix and the insulating modifier were ball milled in a weight ratio of 5:3 at a ball milling speed of 1500 r / min for 1 h.

[0136] The insulating modifier includes a dopamine modified liquid and a forsterite-nano titanium dioxide sintered body, wherein the mass ratio of the dopamine modified liquid to the forsterite-nano titanium dioxide sintered body is 8:3;

[0137] The preheating activation temperature in this embodiment is 370°C and the activation time is 20 minutes.

[0138] The preparation method of the dopamine modified liquid of this embodiment is:

[0139] First, 8 parts of dopamine hydrochloride were added to 30 parts of water, followed by 4 parts of sodium silicate solution and 3 parts of silane coupling agent, and stirred evenly to obtain a dopamine-based medium liquid;

[0140] Preparation of modified nanofiller:

[0141] Nano-calcium carbonate, dimethylhydroxy silicone oil, and silane coupling agent were heated and stirred in a weight ratio of 3:7:1, and the stirring was completed to obtain a nano-calcium carbonate solution. The specific operation steps of the heating and stirring treatment were as follows: first, stirring at a temperature of 55° C. and a speed of 400 r / min for 1 hour, maintaining a constant speed, then heating to 70° C. at a rate of 3° C. / min, and continuing stirring for 2 hours;

[0142] 8 parts of halloysite and 5 parts of silicon carbide were added to 8 parts of 5% by mass lanthanum chloride solution and stirred thoroughly, then filtered and dried, and then sintered at 170°C for 1 hour, and finally air-cooled to room temperature to obtain a halloysite / silicon carbide composite;

[0143] 5 parts of halloysite / silicon carbide composite, 2 parts of sodium metaborate and 4 parts of cerium oxide were added to 8 parts of nano calcium carbonate solution and ball milled at a speed of 1500 r / min for 1 hour. After the ball milling was completed, the mixture was filtered and dried to obtain a modified nano filler.

[0144] Ultrasonic treatment is performed on the modified nanofiller and the dopamine-based medium in a weight ratio of 2:5, and the ultrasonic treatment is terminated to obtain a dopamine-modified liquid;

[0145] The silane coupling agent in this embodiment is silane coupling agent KH550; the mass of the sodium silicate solution is 5%; the ultrasonic power of the ultrasonic treatment is 400W, and the ultrasonic time is 1h;

[0146] The average particle size of the halloysite in this example is 5 μm, and the average aspect ratio is 12;

[0147] The preparation method of the forsterite-nano titanium dioxide sintered body of this embodiment is as follows:

[0148] Disperse 4 parts of nano-silica sol into 8 parts of chitosan solution, then add 2 parts of sodium carboxymethyl cellulose and stir evenly to obtain a modified solution; the mass fraction of the chitosan solution is 4%;

[0149] 8 parts of nano-titanium dioxide and 3 parts of barium sulfate were immersed in 10 parts of the modified solution and stirred thoroughly, and then filtered and dried to obtain a nano-titanium dioxide modified body;

[0150] 7 parts of nano-titanium dioxide modified body, 5 parts of forsterite and 5 parts of 5% by mass yttrium nitrate solution were ball-milled at a speed of 1050 r / min for 2 hours; after the ball-milling, the mixture was filtered and dried, and then calcined to obtain a forsterite-nano-titanium dioxide sintered body;

[0151] The specific steps of the thermal calcination treatment are as follows: first, heating to 175°C at a rate of 3°C / min, sintering for 1 hour, then heating to 300°C at a rate of 4°C / min, keeping at that temperature for 45 minutes, and finally air cooling to room temperature;

[0152] In the pressing step, the mesh number of the sieve before pressing is 80 meshes, and the added amount of the release agent accounts for 0.6% of the total weight of the insulating coated soft magnetic powder and the release agent.

[0153] In the annealing heat treatment step, the magnetic powder core substrate is subjected to a high-temperature annealing heat treatment at 745° C. for 80 minutes to obtain a magnetic powder core.

[0154] Example 3

[0155] The steps of Example 3 are the same as those of Example 1, except that: in the step of preparing the aerosolized iron silicon soft magnetic powder, 0.15% of a slag remover and 0.20% of a deoxidizer are used; the Si content in the aerosolized iron silicon soft magnetic powder is 6.0%;

[0156] The annealing temperature of the high-temperature nitrogen annealing treatment is 850°C, and the annealing time is 60 minutes; the mesh number of the first screening is 80 mesh, and the mesh number of the second screening is 200 mesh;

[0157] The insulation coating step includes the following steps:

[0158] The preheated activated iron silicon magnetic powder matrix and the insulating modifier were ball milled in a weight ratio of 5:3 at a ball milling speed of 1250 r / min for 1 h.

[0159] The insulating modifier includes a dopamine modified liquid and a forsterite-nano titanium dioxide sintered body, wherein the mass ratio of the dopamine modified liquid to the forsterite-nano titanium dioxide sintered body is 6.5:3;

[0160] The preheating activation temperature in this embodiment is 360°C and the activation time is 20 minutes;

[0161] The preparation method of the dopamine modified liquid of this embodiment is:

[0162] First, 6.5 parts of dopamine hydrochloride were added to 27.5 parts of water, followed by 4 parts of sodium silicate solution and 3 parts of silane coupling agent, and stirred evenly to obtain a dopamine-based medium liquid;

[0163] Preparation of modified nanofiller:

[0164] Nano-calcium carbonate, dimethylhydroxy silicone oil, and silane coupling agent were heated and stirred in a weight ratio of 3:7:1, and the stirring was completed to obtain a nano-calcium carbonate solution. The specific operation steps of the heating and stirring treatment were as follows: first, stirring at a temperature of 52.5° C. and a speed of 375 r / min for 1 hour, maintaining a constant speed, then heating to 70° C. at a rate of 2° C. / min, and continuing stirring for 2 hours;

[0165] 6.5 parts of halloysite and 3.5 parts of silicon carbide were added to 6.5 parts of 5% by mass lanthanum chloride solution and stirred thoroughly, then filtered and dried, and then sintered at 160°C for 1 hour, and finally air-cooled to room temperature to obtain a halloysite / silicon carbide composite;

[0166] 4 parts of halloysite / silicon carbide composite, 1.5 parts of sodium metaborate and 3 parts of cerium oxide were added to 6.5 parts of nano calcium carbonate solution and ball milled at a speed of 1500 r / min for 1 hour. After the ball milling was completed, the mixture was filtered and dried to obtain a modified nano filler.

[0167] Ultrasonic treatment is performed on the modified nanofiller and the dopamine-based medium in a weight ratio of 2:5, and the ultrasonic treatment is terminated to obtain a dopamine-modified liquid;

[0168] The silane coupling agent in this embodiment is silane coupling agent KH550; the mass of the sodium silicate solution is 3.5%; the ultrasonic power of the ultrasonic treatment is 375W, and the ultrasonic time is 1 hour;

[0169] The average particle size of the halloysite in this example is 4.5 μm, and the average aspect ratio is 9.5;

[0170] The preparation method of the forsterite-nano titanium dioxide sintered body of this embodiment is as follows:

[0171] Disperse 3 parts of nano-silica sol into 6.5 parts of chitosan solution, then add 1.5 parts of sodium carboxymethyl cellulose and stir evenly to obtain a modified solution; the mass fraction of the chitosan solution is 3.5%;

[0172] Immerse 6.5 parts of nano-titanium dioxide and 2 parts of barium sulfate in 8 parts of the modified solution and stir thoroughly, then filter and dry to obtain a modified nano-titanium dioxide;

[0173] 5.5 parts of nano-titanium dioxide modified body, 3.5 parts of forsterite and 4 parts of 5% by mass yttrium nitrate solution were ball-milled at a speed of 900 r / min for 2 hours; after the ball-milling, the mixture was filtered and dried, and then calcined to obtain a forsterite-nano-titanium dioxide sintered body;

[0174] The specific steps of the thermal calcination treatment are as follows: first, heating to 175°C at a rate of 2°C / min, sintering for 1 hour, then heating to 300°C at a rate of 3°C / min, keeping at that temperature for 45 minutes, and finally air cooling to room temperature;

[0175] In the pressing step, the mesh number of the sieve before pressing is 100 meshes, and the added amount of the release agent accounts for 0.4% of the total weight of the insulating coated soft magnetic powder and the release agent.

[0176] In the annealing heat treatment step, the magnetic powder core substrate is subjected to a high temperature annealing heat treatment at 800° C. for 75 minutes to obtain a magnetic powder core.

[0177] Example 4

[0178] The steps of Example 4 are the same as those of Example 1, except that: in the step of preparing the aerosolized iron silicon soft magnetic powder, 0.20% of a slag remover and 0.30% of a deoxidizer are used; the Si content in the aerosolized iron silicon soft magnetic powder is 6.2%; the annealing temperature of the high-temperature nitrogen annealing treatment is 850° C., and the annealing time is 60 min;

[0179] In the annealing heat treatment step, the magnetic powder core substrate is subjected to a high-temperature annealing heat treatment at 850° C. for 60 minutes to obtain a magnetic powder core.

[0180] The powder properties of the atomized iron-silicon soft magnetic powders obtained in Examples 1 to 4 were tested. The powder properties test items included Si content, tap density (TD), oxygen content (O) and micromorphology. The test results are shown in Table 1. The magnetic core performance of the magnetic powder cores obtained in Examples 1 to 4 was tested for inductance, superposition and power consumption. The test results are shown in Table 2. The micromorphology was observed by scanning electron microscopy. The micromorphology of the atomized iron-silicon soft magnetic powders obtained in Examples 1 to 4 can be found in Table 2. Figures 1 to 4 .

[0181] Table 1 - Powder performance test results

[0182]

[0183] Table 2 - Core performance test results

[0184]

[0185] As shown in Tables 1 and 2, the aerosolized iron-silicon soft magnetic powder prepared by this method has good sphericity, low oxygen content and stable composition, and the magnetic powder core prepared by the above method has magnetic properties with high DC bias and low loss.

[0186] Comparative Example 1

[0187] The difference from Example 1 is that the forsterite-nano-titanium dioxide sintered body is not added to the insulation modifier.

[0188] Comparative Example 2

[0189] The difference from Example 1 is that no nano-titanium dioxide modifier is added in the preparation of the forsterite-nano-titanium dioxide sintered body.

[0190] Comparative Example 3

[0191] The difference from Example 1 is that the preparation method of the modified nano-titanium dioxide is different:

[0192] 6.5 parts of nano-titanium dioxide were immersed in 6.5 parts of chitosan solution, and then 1.5 parts of sodium carboxymethyl cellulose were added, stirred thoroughly, and then filtered and dried to obtain a modified nano-titanium dioxide.

[0193] Comparative Example 4

[0194] The difference from Example 1 is that the forsterite-nano-titanium dioxide sintered body is prepared without ball milling treatment with forsterite and yttrium nitrate solution.

[0195] Comparative Example 5

[0196] The difference from Example 1 is that the dopamine modified liquid is prepared by adding 6.5 parts of dopamine hydrochloride to 27.5 parts of water instead.

[0197] Comparative Example 6

[0198] The difference from Example 1 is that no modified nanofiller is added to the dopamine modified liquid.

[0199] Comparative Example 7

[0200] The difference from Example 1 is that no halloysite / silicon carbide composite is added to the modified nanofiller.

[0201] Comparative Example 8

[0202] The difference from Example 1 is that the preparation method of the halloysite / silicon carbide composite is different:

[0203] 6.5 parts of halloysite were added to 6.5 parts of 5% by mass lanthanum chloride solution, stirred thoroughly, and then filtered and dried.

[0204] Comparative Example 9

[0205] The difference from Example 1 is that sodium metaborate and cerium oxide are not added in the preparation of the modified nanofiller.

[0206] Comparative Example 10

[0207] The difference from Example 1 is that the nano calcium carbonate liquid is directly replaced by dimethylhydroxy silicone oil.

[0208] The breakdown voltage and effective magnetic permeability μ at 100KHz of the products of Example 1 and Comparative Examples 1 to 10 were measured. e The test results are shown in Table 3.

[0209] Table 3 - Breakdown voltage and effective permeability μ at 100 kHz e Results

[0210]

[0211] Based on the above tests, the product was placed at 75°C for 48 hours to test its high temperature resistance, and placed in 2% hydrochloric acid mist for 12 hours, and then placed in 5% sodium chloride salt mist for 12 hours to test its corrosion resistance. The test results are shown in Table 4.

[0212] Table 4 - Test results under high temperature and corrosion resistance conditions

[0213]

[0214] From comparative examples 1 to 10 and embodiment 1, as well as the tests under high temperature and corrosion resistance conditions, it can be seen that;

[0215] The product of Example 1 has excellent breakdown voltage and effective magnetic permeability, and the performance of the two can be improved in a coordinated manner. The product has significant performance stability under high temperature conditions and still has significant performance stability under corrosion resistance conditions. The performance stability of the product has been significantly improved.

[0216] The insulation modifier of the present invention does not contain forsterite-nano-titanium dioxide sintered body, and the dopamine modification liquid is prepared by adding 6.5 parts of dopamine hydrochloride to 27.5 parts of water instead. The performance stability of the product shows a significant deterioration trend;

[0217] The performance of the products obtained by not adding the nano-titania modifier to the forsterite-nano-titania sintered body, using different preparation methods for the nano-titania modifier, or not using the ball milling treatment of forsterite and yttrium nitrate solution in the preparation of the forsterite-nano-titania sintered body all showed a trend of deterioration to varying degrees. The forsterite-nano-titania sintered body obtained by the specific method of the present invention had the most significant product performance effect.

[0218] The performance of the products showed a trend of deterioration when no modified nanofiller was added to the dopamine modified liquid, no halloysite / silicon carbide composite was added to the modified nanofiller, the preparation method of the halloysite / silicon carbide composite was different, sodium metaborate and cerium oxide were not added in the preparation of the modified nanofiller, and the nano calcium carbonate liquid was directly replaced with dimethylhydroxy silicone oil. The performance of the products showed a trend of deterioration when no modified nanofiller was added and no halloysite / silicon carbide composite was added. The performance influencing factors of the products showed a significant change in trend when no modified nanofiller and halloysite / silicon carbide composite were added. At the same time, the dopamine modified liquid obtained by a specific process such as a modified nanofiller prepared by a specific method of the present invention and combined with a nano calcium carbonate liquid had the most significant product performance effect. The effects of other replacement methods were not as significant as those of the present invention.

[0219] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are intended solely to illustrate the principles of the present invention and are not to be construed in any way as limiting the scope of protection of the present invention. Based on the explanations herein, those skilled in the art will be able to devise other specific embodiments of the present invention without inventive effort, and such equivalent variations or substitutions are intended to be encompassed within the scope of the claims of this application.

Claims

1. A method for preparing a magnetic powder core, characterized in that: The following steps are involved: S1: preparing aerosolized iron-silicon soft magnetic powder, wherein the aerosolized iron-silicon soft magnetic powder comprises the following elements by weight percentage: Si: 4.5-6.5%, Ni: <0.05%, Cr: <0.05%, Cu: <0.05%, C: <0.03%, Mn: <0.05%, P: <0.04%, S: <0.03%, and the balance is Fe; S2: Insulation coating: Insulation coating of aerosolized iron silicon soft magnetic powder, including the following steps: S21: preheating and activating the aerosolized iron-silicon soft magnetic powder obtained in S1 to obtain a preheated and activated iron-silicon magnetic powder matrix; S22: The preheated activated iron silicon magnetic powder matrix and the insulating modifier are subjected to ball milling coating treatment in a weight ratio of 5:3, with a ball milling speed of 1000-1500 r / min for 1 hour to obtain an insulating coated soft magnetic powder; The insulating modifier includes a dopamine modified liquid and a forsterite-nano titanium dioxide sintered body, wherein the mass ratio of the dopamine modified liquid to the forsterite-nano titanium dioxide sintered body is (5-8):3; S3: Pressing and molding: Screening the insulating coated soft magnetic powder before pressing, then mixing the screened insulating coated soft magnetic powder with a release agent and pressing it into a magnetic powder core matrix; S4: Annealing heat treatment: Perform high-temperature annealing heat treatment on the magnetic powder core matrix to obtain a magnetic powder core.

2. The method for preparing a magnetic powder core according to claim 1, wherein: The preparation method of the dopamine modified liquid is: S201: first add 5 to 8 parts of dopamine hydrochloride to 25 to 30 parts of water, then add 2 to 4 parts of sodium silicate solution and 1 to 3 parts of silane coupling agent, and stir evenly to obtain a dopamine-based medium liquid; S202: heating and stirring the nano-calcium carbonate, dimethylhydroxy silicone oil, and silane coupling agent in a weight ratio of 3:7:1 until the stirring is completed to obtain a nano-calcium carbonate solution; The specific operation steps of the heating and stirring treatment are: First, stir at a temperature of 50-55°C and a speed of 350-400 r / min for 1 h, maintain a constant speed, then heat to 70°C at a rate of 1-3°C / min and continue stirring for 2 h; S203: adding 5 to 8 parts of halloysite and 2 to 5 parts of silicon carbide to 5 to 8 parts of a 5% by mass lanthanum chloride solution, stirring thoroughly, then filtering, drying, sintering at 150 to 170° C. for 1 hour, and finally air cooling to room temperature to obtain a halloysite / silicon carbide composite; S204: 3-5 parts of halloysite / silicon carbide composite, 1-2 parts of sodium metaborate, and 2-4 parts of cerium oxide are added to 5-8 parts of nano-calcium carbonate solution and ball-milled at a speed of 1500 rpm for 1 hour. After the ball milling is completed, the mixture is filtered and dried to obtain a modified nano-filler. S205: ultrasonically treating the modified nanofiller and the dopamine-based medium at a weight ratio of 2:5, and completing the ultrasonic treatment to obtain a dopamine-modified liquid; The silane coupling agent is silane coupling agent KH550; the mass of the sodium silicate solution is 2-5%; the ultrasonic power of the ultrasonic treatment is 350-400W, and the ultrasonic time is 1 hour.

3. The method for preparing a magnetic powder core according to claim 2, wherein: The average particle size of the halloysite is 3.5 to 5 μm, and the average aspect ratio is 7 to 12.

4. The method for preparing a magnetic powder core according to claim 1, wherein: The preparation method of the forsterite-nano titanium dioxide sintered body is: S206: dispersing 2 to 4 parts of nano-silica sol into 5 to 8 parts of chitosan solution, then adding 1 to 2 parts of sodium carboxymethyl cellulose, and stirring to obtain a modified solution; The mass fraction of the chitosan solution is 3-4%; S207: 5 to 8 parts of nano-titanium dioxide and 1 to 3 parts of barium sulfate are immersed in 6 to 10 parts of the modified solution and stirred thoroughly, and then filtered and dried to obtain a modified nano-titanium dioxide; S208: ball milling 4 to 7 parts of the modified nano-titanium dioxide, 2 to 5 parts of forsterite, and 3 to 5 parts of a 5% by mass yttrium nitrate solution at a rotation speed of 750 to 1050 r / min for 2 hours; after the ball milling, filtering and drying, and then calcining to obtain a forsterite-nano-titanium dioxide sintered body; The specific steps of the thermal calcination treatment are: first heating to 175°C at a rate of 1-3°C / min, sintering for 1 hour, then heating to 300°C at a rate of 2-4°C / min, keeping warm for 45 minutes, and finally air cooling to room temperature.

5. The method for preparing a magnetic powder core according to claim 1, wherein: The preheating activation temperature is 350-370° C., and the activation time is 20 minutes.

6. The method for preparing a magnetic powder core according to claim 1, wherein: In the step S3, the mesh number of the sieve before pressing is 80-200 meshes, and the added amount of the release agent accounts for 0.3-0.6% of the total weight of the insulating coated soft magnetic powder and the release agent.

7. The method for preparing a magnetic powder core according to claim 1, characterized in that: In the step S4, the annealing temperature of the high temperature annealing heat treatment is 650-850° C., and the annealing time is 30-120 minutes.

8. The method for preparing a magnetic powder core according to claim 1, wherein: In step S1, the following steps are included: S11: Proportioning: Weigh the gas atomized iron-silicon soft magnetic powder raw material, the slag remover and the deoxidizer according to the proportion; S12: Alloy smelting: heating and smelting the gas atomized iron-silicon soft magnetic powder raw material, adding a slag remover and a deoxidizer, and stirring; after stirring, standing and removing the slag to obtain an alloy melt; S13: Gas atomization powder making: The alloy melt is poured into a tundish, and the alloy melt flows into the gas atomization chamber from the guide pipe at the bottom of the tundish. The alloy melt is atomized by high-pressure nitrogen gas, and the alloy melt is broken into droplets. After cooling and solidification, the droplets are settled to obtain semi-finished powder; S14: Screening: After the semi-finished product powder is cooled to room temperature, it is screened once; then it is annealed in high-temperature nitrogen and screened twice to obtain aerosolized iron-silicon soft magnetic powder.

9. The method for preparing a magnetic powder core according to claim 8, characterized in that: In the step S11, the amount of the slag remover added is 0.15-0.35% of the total mass of the atomized iron silicon soft magnetic powder raw material, and the amount of the deoxidizer added is 0.20-0.40% of the total mass of the atomized iron silicon soft magnetic powder raw material; In step S12, the alloy is smelted at a temperature of 1600-1650° C. and the standing time is 0.5-2.5 min; In step S13, the alloy melt pouring temperature is 1630-1660° C.; the pressure of the high-pressure nitrogen is 3.5-5.0 MPa; and the temperature inside the tundish is 1000-1250° C.; The material of the flow guide tube is boron nitride or zirconium oxide, and the diameter of the flow guide tube is 4.0 to 7.0 mm; In the step S14, in the high temperature nitrogen annealing treatment, the annealing temperature is 700-1050° C., the annealing time is 25-60 min; and the mesh number of the first screening is 60-100 mesh, and the mesh number of the second screening is 100-325 mesh.

10. A magnetic powder core, characterized in that: The magnetic powder core is prepared by the method for preparing a magnetic powder core according to any one of claims 1 to 9.

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