Modified soft magnetic composite alloy material and preparation method thereof, and composite soft magnetic powder core and preparation method thereof

Abstract

The invention provides a modified soft magnetic composite alloy material and a preparation method thereof, and a composite soft magnetic powder core and a preparation method thereof. The preparation method of the modified soft magnetic composite alloy material comprises the steps that S1, alloy powder and a coupling agent are mixed, ball-milled, screened, dried, annealed and compounded, and modified alloy powder is obtained; s2, uniformly mixing the low-melting-point powder and the high-resistivity nano powder, and sintering to obtain a coating agent with a porous structure; and S3, the modified alloy powder and a coating agent are mixed, and the modified soft magnetic composite alloy material is obtained. The powder surface coating agent with the porous structure is prepared through sintering, the surface resistance of the powder can be improved, and when the powder surface coating agent is applied to preparation of the magnetic powder core, the soft magnetic powder core with low loss, good magnetic performance and stability can be prepared. According to the method for preparing the composite alloy material by modifying the alloy powder, the process is simple, and meanwhile pollution to the environment in the preparation process is small.

Description

Technical Field

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

[0002] In recent years, with the continuous development of communication technology and semiconductor technology, electronic devices on the market are being improved in the directions of wearable, miniaturized, high-frequency, and low-cost. Materials used in electronic information also need to meet higher performance requirements. Magnetic powder cores have been widely used as the core of power conversion devices in fields such as automobiles, servers, photovoltaic, and communication equipment, which helps to improve the energy utilization efficiency of electronic devices, reduce energy losses, and contribute to future sustainable development.

[0003] Metal soft magnetic composite materials form an insulating layer by coating a material with high resistivity on the surface of magnetic powder to reduce high-frequency eddy current loss, and at the same time can increase its working frequency. However, there are often uneven coating situations, and the comprehensive performance improvement is not obvious. The doping of non-magnetic insulating media will reduce the volume ratio of magnetic media, resulting in the deterioration of its performance. The preparation process steps of magnetic cores include magnetic powder preparation, insulation coating, pressing into shape, and annealing treatment. Magnetic cores are prone to rust when exposed to the external environment and need to be protected by painting.

[0004] Chinese Patent Application with Publication No. CN 111081466 A discloses a preparation method of an amorphous nanocrystalline soft magnetic composite material. The method is to carry out insulation coating on amorphous nanocrystalline soft magnetic powder through the hydrolysis of metal organic alkoxide under the action of a surfactant, uniformly disperse a low melting point glass phase in an organic resin and uniformly mix it with the amorphous powder, and then carry out molding and annealing by die pressing. The magnetic powder core prepared by this method is relatively high in price, the preparation process takes a long time, and the cost increases.

[0005] Chinese Patent with Publication No. CN110136910 A provides a preparation method of a high magnetic permeability and low loss iron-based soft magnetic composite material. The method is to dissolve aluminum isopropoxide, tetraethyl orthosilicate, boric acid, and potassium hydroxide to obtain a transparent colloidal SiO2-Al2O3 coating layer material, carry out surface modification on carbonyl iron powder with oleic acid, add a binder and mix to obtain carbonyl iron powder core-shell particles with an insulating coating layer, and then add reduced iron powder and ball mill and mix, press into shape and anneal. The preparation process of this preparation method is complex, the preparation cost is high, and it is not conducive to mass production.

[0006] The Chinese patent with the publication number CN106205935 A provides a preparation method of an amorphous soft magnetic composite powder core. By preparing amorphous alloy ribbons into amorphous alloy powders, screening, compounding, passivating and coupling treatments are carried out, and then they are mixed and stirred with a ceramic precursor polymer solution to obtain composite amorphous powders. The powders are formed, heat-treated and coated with an insulating layer to obtain the amorphous soft magnetic composite powder core. This method selects amorphous alloy ribbons to prepare powders, and the pre-treatment process is relatively complex, resulting in an increase in the preparation cost. Summary of the Invention

[0007] The main object of the present invention is to provide a modified soft magnetic composite alloy material and its preparation method, a composite soft magnetic powder core and its preparation method, so as to solve the problems of high loss of metal soft magnetic materials or complex preparation processes in the prior art.

[0008] To achieve the above object, according to one aspect of the present invention, a preparation method of a modified soft magnetic composite alloy material is provided. The preparation method includes: Step S1, mixing alloy powder and a coupling agent, ball milling, screening, drying, annealing, and compounding to obtain modified alloy powder; Step S2, mixing low melting point powder and high resistivity nano powder evenly and sintering to obtain a coating agent with a porous structure; Step S3, mixing the modified alloy powder with the coating agent to obtain the modified soft magnetic composite alloy material.

[0009] Further, the alloy powder includes any one or more of FeSi, FeNi, FeSiAl, FeNiMo, FeSiAlNi, FeSiCr, and FeSiAlTi;

[0010] And / or, the coupling agent is any one or more of polyol surfactants, KH550, KH560, KH570, S510, S530, titanate coupling agents, and polyacrylamide;

[0011] Preferably, the mass ratio of the coupling agent to the alloy powder is (0.2 - 1.5):100.

[0012] Further, in Step S1, the ball milling is wet ball milling. Preferably, the solvent used for wet ball milling is any one or more of alcohol and acetone. Preferably, the ball milling time is 1 - 24 h, and the rotation speed frequency is 18 - 30 Hz;

[0013] And / or, in Step S1, the annealing is carried out in an inert gas. Preferably, the annealing temperature is 600°C - 850°C, and the time is 1 - 5 h. Preferably, when annealing, the heating rate is 1 - 5°C / min.

[0014] Further, the low melting point powder includes any one or more of boron oxide powder, boric acid powder, and bismuth oxide powder; preferably, the low melting point powder includes a mixture of any one or more of boron oxide powder and bismuth oxide powder and boric acid powder;

[0015] And / or, the high resistivity nano powder is any one or more of calcium oxide powder, alumina powder, and nano silicon dioxide powder;

[0016] Preferably, the molar ratio of the low melting point powder to the high resistivity nano powder is 1:(4 - 5).

[0017] Further, in step S2, the sintering temperature is 1000 - 1400 °C, preferably, the heat preservation time is 1 - 3 h; preferably, the heating rate during sintering is 1 - 5 °C / min.

[0018] Further, in step S3, the mass ratio of the coating agent to the modified alloy powder is 0.1 - 5:100.

[0019] According to another aspect of the present application, a modified soft magnetic composite alloy material is provided, and the modified soft magnetic composite alloy material is prepared by any one of the above preparation methods.

[0020] According to still another aspect of the present application, a preparation method of a composite soft magnetic powder core is provided, and the preparation method includes: mixing the above-mentioned modified soft magnetic composite alloy material with a binder and a release agent to form a mixed powder, compacting the mixed powder into a shape, and annealing.

[0021] Further, the binder includes any one or more of epoxy resin, silicone resin, phenolic resin, and silicone resin, preferably, the addition amount of the binder is 1 wt% - 5 wt% of the mixed powder;

[0022] And / or, the release agent includes any one or more of zinc stearate, barium stearate, aluminum stearate, and talcum powder, preferably, the addition amount of the release agent is 0.3 wt% - 3 wt% of the mixed powder.

[0023] Further, the pressure for compacting into a shape is 500 - 3000 MPa;

[0024] And / or, the annealing is carried out in an inert gas atmosphere, preferably, the heating rate of annealing is 1.5 - 5 °C / min, preferably, the treatment temperature of annealing is 550 - 850 °C, and the time is 1 - 3 h;

[0025] Preferably, the preparation method further includes: before performing press molding, passivating the modified soft magnetic composite alloy material. Preferably, the passivating agent for passivation treatment includes any one or more of phosphoric acid, hydrogen peroxide, and nitric acid. Preferably, the dosage of the passivating agent is 0.1-3 wt% of the modified soft magnetic composite alloy material;

[0026] Preferably, before performing the press molding treatment, screen the mixed powder.

[0027] According to another aspect of the present application, a composite soft magnetic powder core is provided, and the composite soft magnetic powder core is prepared by any one of the above preparation methods.

[0028] Applying the technical solution of the present invention, by sintering to prepare a powder surface coating agent with a porous structure, the surface resistance of the powder can be improved. Applying it to the preparation of a magnetic powder core can make a soft magnetic powder core with low loss, good magnetic properties and stability. The above method for modifying alloy powder to prepare a composite alloy material is not only simple in process, but also has less environmental pollution during the preparation process. Specific Embodiments

[0029] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0030] As analyzed in the background art of the present application, there are problems in the prior art such as high loss of metal soft magnetic materials or complex preparation processes. To solve this problem, the present application provides a modified soft magnetic composite alloy material and its preparation method, a composite soft magnetic powder core and its preparation method.

[0031] According to a typical embodiment of the present application, a preparation method of a modified soft magnetic composite alloy material is provided. The preparation method includes: Step S1, mixing alloy powder and a coupling agent, ball milling, screening, drying, annealing, and compounding to obtain modified alloy powder; Step S2, uniformly mixing low melting point powder and high resistivity nano powder, and performing sintering to obtain a coating agent with a porous structure; Step S3, mixing the modified alloy powder with the coating agent to obtain a modified soft magnetic composite alloy material.

[0032] The present application prepares a powder surface coating agent with a porous structure by sintering, which can improve the surface resistance of the powder. Applying it to the preparation of a magnetic powder core can make a soft magnetic powder core with low loss, good magnetic properties and stability. The above method for modifying alloy powder to prepare a composite alloy material is not only simple in process, but also has less environmental pollution during the preparation process.

[0033] The above alloy powders can be selected from the prior art. In some embodiments of the present application, the alloy powders include any one or more of FeSi, FeNi, FeSiAl, FeNiMo, FeSiAlNi, FeSiCr, and FeSiAlTi; through the coating modification method of the present application, the obtained materials have low losses, and the comprehensive effect after modification is particularly prominent.

[0034] In some embodiments of the present application, in order to further improve the performance of the modified soft magnetic composite alloy material, especially its stability, the coupling agent is any one or more of polyol surfactants, KH550, KH560, KH570, S510, S530, titanate coupling agents, and polyacrylamide.

[0035] In some preferred embodiments of the present application, the mass ratio of the coupling agent to the alloy powder is (0.2 - 1.5):100, and the improvement effect on the composite material is particularly significant.

[0036] In the above step S1, the specific implementation process of ball milling can refer to the prior art. In some embodiments of the present application, the ball milling is wet ball milling. Preferably, the solvent used in the wet ball milling is any one or more of alcohol and acetone, which has a good dissolution and dispersion effect on the coupling agent and is relatively cheap and easy to obtain. Preferably, the ball milling time is 1 - 24 h, and the rotation frequency is 18 - 30 Hz, with good effects, which helps the coupling agent to be evenly adsorbed on the surface of the alloy powder. In order to improve the performance of the magnetic material, the ball-milled material is screened, divided into different particle sizes, and then compounded according to needs in proportion. Among them, the order of screening, drying, annealing, and compounding can be adjusted according to actual needs, and the present application does not make any restrictions. For example, screening can be carried out first and then compounding, and then the compounded powder is dried and annealed, or screening can be carried out first, then drying and annealing, and then compounding after annealing.

[0037] In some preferred embodiments of the present application, the ball-milled material is screened with a 100-mesh sieve, a 200-mesh sieve, and a 350-mesh sieve, and then dried, annealed, and compounded; preferably, during compounding, the mass ratio of the 100-mesh powder, the 200-mesh powder, and the 350-mesh powder is (0.05 - 0.5):(0.1 - 1.5):(8 - 9.85).

[0038] In some embodiments of the present application, in step S1, the annealing is carried out in an inert gas to prevent oxidation of the alloy powder during the annealing process. Preferably, the annealing temperature is 600°C - 850°C, and the time is 1 - 5 h, which has a relatively obvious effect on improving the density, mechanical properties, and magnetic properties of the modified alloy powder. Preferably, during annealing, the heating rate is 1 - 5°C / min.

[0039] The above-mentioned low-melting-point powder can decompose or vaporize during the sintering process, release gas, and form a coating agent with a porous structure. In some embodiments of the present application, the low-melting-point powder includes any one or more of boron oxide powder, boric acid powder, and bismuth oxide powder. After sintering, the generated porous structure not only has a particularly significant effect on improving the bonding performance of the modified alloy powder and increasing the surface resistance of the powder; in some preferred embodiments of the present application, the low-melting-point powder includes a mixture of any one or more of boron oxide powder and bismuth oxide powder and boric acid powder. The boric acid powder and the boron oxide powder or bismuth oxide powder act together, and the formed porous structure coating layer has a more significant effect on improving the performance of the composite alloy material. Preferably, the content of boric acid powder in the low-melting-point powder is 20wt% - 80wt%, such as 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, 70wt%, or 80%, which can further improve the coating effect.

[0040] Preferably, the particle size of the low-melting-point powder is 0.5 - 10μm, which is beneficial to further improving its coating effect.

[0041] In some embodiments of the present application, the high-resistivity nano powder is any one or more of calcium oxide powder, alumina powder, and nano-silica powder, which can further increase the surface resistance of the powder and reduce the loss;

[0042] In some preferred embodiments of the present application, the molar ratio of the low-melting-point powder to the high-resistivity nano powder is 1:(4 - 5), which is beneficial to the formation of a porous structure and further improves the coating effect of the coating agent.

[0043] In some typical embodiments of the present application, in step S2, the sintering temperature is 1000 - 1400°C. Preferably, the heat preservation time is 1 - 3h; preferably, the heating rate during sintering is 1 - 5°C / min.

[0044] In the above step S3, the modified alloy powder and the coating agent are simply mixed and dispersed evenly. Due to the porous structure of the coating agent, it can be easily combined with the modified alloy powder modified by the coupling agent, such as by stirring for mixing. In some embodiments of the present application, the mass ratio of the coating agent to the modified alloy powder is 0.1 - 5:100, and the coating effect is better.

[0045] In some preferred embodiments of the present application, considering that after the modified alloy powder and the coating agent are mixed, the particles will agglomerate and the material particle size is relatively large, which is not conducive to improving the performance of the material. Step S3 includes: after mixing the modified alloy powder and the coating agent, performing dispersion granulation to obtain a modified soft magnetic composite alloy material; preferably, after granulation, the particle size of the modified soft magnetic composite alloy material is 100 mesh - 200 mesh.

[0046] According to another typical embodiment of the present application, a modified soft magnetic composite alloy material is provided, and this material is prepared by any one of the above preparation methods.

[0047] Due to the powder surface coating agent with a porous structure prepared by sintering contained in the above modified soft magnetic composite alloy material, the surface resistance of the powder is significantly improved. When it is applied to the preparation of magnetic powder cores, soft magnetic powder cores with low losses, good magnetic properties and stability can be made.

[0048] According to still another typical embodiment of the present application, a preparation method of a composite soft magnetic powder core is provided, and this preparation method includes: mixing the above modified soft magnetic composite alloy material with a binder and a release agent to form a mixed powder, compacting the mixed powder into a shape, and annealing.

[0049] The composite soft magnetic powder core prepared by this preparation method adopts the above modified soft magnetic composite alloy material with a relatively high surface resistance. While improving the performance of the magnetic powder core, it increases the magnetic permeability and green density of the magnetic powder core and reduces the loss of the magnetic powder core. Moreover, the preparation process of this method is simple and easy to industrialize.

[0050] The above binder can be selected from the prior art. In some embodiments of the present application, the binder includes any one or more of epoxy resin, silicone resin, phenolic resin and silicone resin, and can cooperate better with the modified soft magnetic composite alloy material of the present application. Preferably, the addition amount of the binder is 1wt% - 5wt% of the mixed powder, and the effect on improving the performance of the composite soft magnetic powder core is relatively significant.

[0051] The above release agent can also be selected from the prior art. Exemplarily, the release agent includes, but is not limited to, any one or more of zinc stearate, barium stearate, aluminum stearate and talcum powder. Preferably, the addition amount of the release agent is 0.3wt% - 3wt% of the mixed powder.

[0052] The specific process of compacting the mixed powder into a shape can refer to the prior art. Preferably, the pressure for compacting into a shape is 500 - 3000MPa, and the forming effect is better.

[0053] In some embodiments of the present application, annealing is carried out in an inert gas atmosphere. Preferably, the heating rate of annealing is 1.5 - 5°C / min, preferably, the treatment temperature of annealing is 550 - 850°C, and the time is 1 - 3h.

[0054] In some preferred embodiments of the present application, the above preparation method further includes: before the press molding, passivating the modified soft magnetic composite alloy material. Preferably, the passivating agent for the passivation treatment includes any one or more of phosphoric acid, hydrogen peroxide, and nitric acid. Preferably, the dosage of the passivating agent is 0.1-3 wt% of the modified soft magnetic composite alloy material; preferably, before the press molding treatment, the mixed powder is sieved to make the particles disperse evenly, which is beneficial to the further pressing effect.

[0055] According to another typical embodiment of the present application, a composite soft magnetic powder core is provided, and the composite soft magnetic powder core is prepared by any one of the above preparation methods. The composite soft magnetic powder core prepared by this preparation method uses the above modified soft magnetic composite alloy material with a relatively high surface resistance, which improves the magnetic core performance while increasing the magnetic permeability and green density of the magnetic powder core, reducing the loss of the magnetic powder core, and having a relatively low cost.

[0056] The following will further illustrate the beneficial effects that can be achieved by the present application in combination with examples and comparative examples.

[0057] Example 1

[0058] (1) Weigh 100 parts of alloy powder (96% FeSiAl + 3% FeNi + 1% FeNiMo) by weight, add 0.5 part of coupling agent KH560 and 200 parts of ethanol for ball milling. The ball milling frequency is set to 20 Hz and the time is 2 h. Sieve and separate with a 100-mesh sieve, a 200-mesh sieve, and a 350-mesh sieve, and dry at 100 °C, then perform annealing treatment. The heating rate of the annealing treatment is 3 °C / min, and it is heated to 600 °C in nitrogen or an atmosphere and held for 1 h. Mix the 350-mesh, 200-mesh, and 100-mesh powders according to a mass ratio of 7:2.5:0.5 to obtain the modified alloy powder.

[0059] (2) Weigh according to the molar ratio of low melting point powder (80% boric acid powder and 20% boron oxide powder) to high resistivity powder (calcium oxide) of 1:4, mix evenly, sinter at 1100 °C, and control the heating rate at 3 °C / min and hold for 2 h to obtain the coating agent;

[0060] (3) Mix the coating agent and the modified alloy powder according to a mass ratio of 1:99 to obtain the mixed powder;

[0061] (4) Mix and dry the mixed powder in (3): phosphoric acid: epoxy resin: zinc stearate according to a mass ratio of 100:0.8:2:0.5, press the magnetic core at a pressure of 2000 MPa, place the magnetic core in a tube furnace for annealing, and set the heat treatment process to hold at 700 °C in a nitrogen atmosphere for 2 h, and control the heating rate at 3 °C / min.

[0062] Example 2

[0063] (1) Weigh 100 parts of alloy powder (96% FeSiAl + 3% FeNi + 1% FeNiMo) by weight, add 1 part of coupling agent KH560 and 200 parts of ethanol for ball milling. Set the ball milling frequency to 23 Hz and the time to 2 h. Sieve it with 100-mesh sieve, 200-mesh sieve and 350-mesh sieve, and dry it at 100 °C, then carry out annealing treatment. The heating rate of the annealing treatment is 3 °C / min, heat it up to 600 °C in nitrogen or atmosphere, and keep it warm for 1.5 h. Mix the 350-mesh, 200-mesh and 100-mesh powders according to the mass ratio of 7:2.5:0.5 to obtain the modified alloy powder.

[0064] (2) Weigh according to the molar ratio of low melting point powder (50% boric acid powder and 50% bismuth oxide powder): high resistivity powder (calcium oxide) of 1:5, mix evenly, sinter at 1200 °C, control the heating rate at 3 °C / min, and keep it warm for 2 h to obtain the coating agent;

[0065] (3) Mix the coating agent and the modified alloy powder according to the mass ratio of 1.5:99 to obtain the mixed powder;

[0066] (4) Mix and dry the mixed powder in (3): phosphoric acid: epoxy resin: zinc stearate according to the mass ratio of 100:0.5:2:0.4, press the magnetic core at a pressure of 1000 MPa, place the magnetic core in a tube furnace for annealing, set the heat treatment process to keep it warm in nitrogen atmosphere at 750 °C for 2 h, and control the heating rate at 2.5 °C / min.

[0067] Example 3

[0068] (1) Weigh 100 parts of alloy powder (96% FeSiAl + 3% FeNi + 1% FeNiMo) by weight, add 0.8 part of coupling agent KH560 and 200 parts of ethanol for ball milling. Set the ball milling frequency to 23 Hz and the time to 3 h. Sieve it with 100-mesh sieve, 200-mesh sieve and 350-mesh sieve, and dry it at 100 °C, then carry out annealing treatment. The heating rate of the annealing treatment is 3 °C / min, heat it up to 650 °C in nitrogen or atmosphere, and keep it warm for 2 h. Mix the 350-mesh, 200-mesh and 100-mesh powders according to the mass ratio of 7:2.5:0.5 to obtain the modified alloy powder.

[0069] (2) Weigh according to the molar ratio of low melting point powder (80% boric acid powder and 20% bismuth oxide powder): high resistivity powder (calcium oxide) of 2:9, mix evenly, sinter at 1300 °C, control the heating rate at 3 °C / min, and keep it warm for 2 h to obtain the coating agent;

[0070] (3) Mix the coating agent and the modified alloy powder according to the mass ratio of 2:99 to obtain the mixed powder;

[0071] (4) Mix the mixed powder in (3): phosphoric acid: epoxy resin: zinc stearate in a mass ratio of 100:0.5:2:0.6, dry it, press the magnetic core under a pressure of 1800 MPa, place the magnetic core in a tube furnace for annealing, set the heat treatment process to hold at 750 °C in a nitrogen atmosphere for 2 h, and control the heating rate at 2.5 °C / min.

[0072] Example 4

[0073] (1) Weigh 100 parts of alloy powder (96% FeSiAl + 3% FeNi + 1% FeNiMo) by weight, add 0.6 parts of coupling agent KH550 and 200 parts of ethanol for ball milling. Set the ball milling frequency to 23 Hz and the time to 3 h. Sieve it with 100-mesh, 200-mesh, and 350-mesh sieves, dry it at 100 °C, and then perform annealing treatment. The heating rate of the annealing treatment is 3 °C / min. Heat it up to 700 °C in nitrogen or an atmosphere and hold for 2 h. Mix the 350-mesh, 200-mesh, and 100-mesh powders according to a mass ratio of 8:1.5:0.5 to obtain the modified alloy powder.

[0074] (2) Weigh according to the molar ratio of low-melting-point powder (80% boric acid powder and 20% bismuth oxide powder): high-resistivity powder (aluminum oxide) of 2:9, mix evenly, sinter at 1300 °C, control the heating rate at 3 °C / min, and hold for 2 h to obtain the coating agent;

[0075] (3) Mix the coating agent and the modified alloy powder according to a mass ratio of 3:100 to obtain the mixed powder;

[0076] (4) Mix the mixed powder in (3): phosphoric acid: epoxy resin: zinc stearate in a mass ratio of 100:0.4:3:0.6, dry it, press the magnetic core under a pressure of 2000 MPa, place the magnetic core in a tube furnace for annealing, set the heat treatment process to hold at 700 °C in a nitrogen atmosphere for 2 h, and control the heating rate at 2.5 °C / min.

[0077] Example 5

[0078] (1) Weigh 100 parts of alloy powder (96% FeSiAl + 3% FeNi + 1% FeNiMo) by weight, add 0.5 parts of coupling agent KH550 and 200 parts of ethanol for ball milling. Set the ball milling frequency to 23 Hz and the time to 3 h. Sieve it with 100-mesh, 200-mesh, and 350-mesh sieves, dry it at 100 °C, and then perform annealing treatment. The heating rate of the annealing treatment is 3 °C / min. Heat it up to 700 °C in nitrogen or an atmosphere and hold for 2 h. Mix the 350-mesh, 200-mesh, and 100-mesh powders according to a mass ratio of 8.5:1:0.5 to obtain the modified alloy powder.

[0079] (2) Weigh the low-melting-point powder (20% boric acid powder and 80% bismuth oxide powder) and the high-resistivity powder (aluminum oxide) according to a molar ratio of 1.5:7, mix them evenly, sinter at 1300 °C, control the heating rate at 3 °C / min, and hold for 2 h to obtain the coating agent;

[0080] (3) Mix the coating agent and the modified alloy powder according to a mass ratio of 4:100 to obtain a mixed powder;

[0081] (4) Mix and dry the mixed powder in (3): phosphoric acid: epoxy resin: zinc stearate according to a mass ratio of 100:0.4:3:0.6, press the magnetic core at a pressure of 2000 MPa, place the magnetic core in a tube furnace for annealing, set the heat treatment process to hold at 700 °C in a nitrogen atmosphere for 2 h, and control the heating rate at 2.5 °C / min.

[0082] Example 6

[0083] (1) Weigh 100 parts of alloy powder (96% FeSiAl + 3% FeNi + 1% FeNiMo) by weight, add 2 parts of coupling agent KH560 and 200 parts of ethanol for ball milling. Set the ball milling frequency to 23 Hz and the time to 3 h. Sieve and separate with 100-mesh sieve, 200-mesh sieve and 350-mesh sieve, dry at 100 °C, and then perform annealing treatment. The heating rate of the annealing treatment is 3 °C / min, heat up to 700 °C in nitrogen or an atmosphere, and hold for 2 h. Mix the 350-mesh, 200-mesh, and 100-mesh powders according to a mass ratio of 9:0.5:0.5 to obtain the modified alloy powder.

[0084] (2) Weigh the low-melting-point powder (60% boric acid powder and 40% bismuth oxide powder) and the high-resistivity powder (silicon dioxide) according to a molar ratio of 2:9.5, mix them evenly, sinter at 1400 °C, control the heating rate at 3 °C / min, and hold for 2 h to obtain the coating agent;

[0085] (3) Mix the step coating agent and the modified alloy powder according to a mass ratio of 3:100 to obtain a mixed powder;

[0086] (4) Mix and dry the mixed powder in (3): phosphoric acid: epoxy resin: zinc stearate according to a mass ratio of 100:0.6:2.5:0.5, press the magnetic core at a pressure of 1500 MPa, place the magnetic core in a tube furnace for annealing, set the heat treatment process to hold at 780 °C in a nitrogen atmosphere for 2 h, and control the heating rate at 2.5 °C / min.

[0087] Example 7

[0088] The difference from Example 1 is that in step (4), the molding pressure is adjusted to 1600 MPa.

[0089] Example 8

[0090] The difference from Example 1 is that in step (2), the ratio of the low-melting-point powder to the high-resistivity powder is adjusted to 2:9.

[0091] Example 9

[0092] The difference from Example 1 is that in step (2), the ratio of the low-melting-point powder to the high-resistivity powder is adjusted to 1:5.

[0093] Example 10

[0094] The difference from Example 1 is that in step (2), the ratio of the low-melting-point powder to the high-resistivity powder is adjusted to 1:3.

[0095] Example 11

[0096] The difference from Example 1 is that in step (2), the ratio of the low-melting-point powder to the high-resistivity powder is adjusted to 1:6.

[0097] Example 12

[0098] The difference from Example 1 is that in step (2), sintering is carried out at 1000 °C.

[0099] Example 13

[0100] The difference from Example 1 is that in step (2), sintering is carried out at 1400 °C.

[0101] Example 14

[0102] The difference from Example 1 is that in step (2), sintering is carried out at 1500 °C.

[0103] Example 15

[0104] The difference from Example 1 is that in step (2), sintering is carried out at 800 °C.

[0105] Example 16

[0106] The difference from Example 1 is that in step (2), all of the low-melting-point powder is boric acid powder.

[0107] Example 17

[0108] The difference from Example 1 is that in step (2), all of the low-melting-point powder is boron oxide powder.

[0109] Comparative Example 1

[0110] 100 parts of alloy powder (96% FeSiAl + 3% FeNi + 1% FeNiMo) were passivated with 1 part of phosphoric acid, 1 part of kaolin was added and mixed evenly, then 1 part of silicone resin was mixed. Using epoxy resin as the binder and zinc stearate as the release agent, it was molded under 1000 MPa and annealed in a nitrogen atmosphere at an annealing temperature of 700 °C to obtain a sample.

[0111] Comparative Example 2

[0112] 100 parts of alloy powder (96% FeSiAl + 3% FeNi + 1% FeNiMo) were passivated with 1 part of phosphoric acid, 1 part of kaolin was added and mixed evenly, then 1 part of silicone resin was mixed. Using epoxy resin as the binder and zinc stearate as the release agent, it was molded under 1000 MPa and annealed in a nitrogen atmosphere at an annealing temperature of 500 °C to obtain a sample.

[0113] Comparative Example 3

[0114] This comparative example provides a preparation method of a composite soft magnetic material. The preparation method is the same as that of Comparative Example 1 except that the annealing temperature is adjusted to 800 °C.

[0115] Comparative Example 4

[0116] This comparative example provides a preparation method of a composite soft magnetic material. The preparation method is the same as that of Comparative Example 1 except that the pressure is adjusted to 800 MPa.

[0117] The soft magnetic powder cores prepared by the preparation methods of the above examples and comparative examples were tested for magnetic permeability and loss, and the test results are listed in Table 1.

[0118] Among them, the test method for magnetic permeability is: According to the formula L = μ * N^2 * A / l, where L is the inductance, μ is the magnetic permeability, N is the number of turns of the winding, A is the cross-sectional area of the magnetic ring, and l is the magnetic path length. After testing the inductance of the magnetic core using an inductance meter, the magnetic permeability was obtained through conversion.

[0119] The test method for loss is: Wind 0.5 mm copper wires with 20 turns and 5 turns on the magnetic core, and use a SY8218 loss tester to test the loss under the conditions of 50 kHz and 100 mT.

[0120] Table 1

[0121]

[0122]

[0123] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects: By sintering to prepare a powder surface coating agent with a porous structure, the surface resistance of the powder can be improved. When it is applied to the preparation of magnetic powder cores, a soft magnetic powder core with low loss, good magnetic properties and stability can be made. The above method for modifying alloy powder to prepare a composite alloy material is not only simple in process, but also has less environmental pollution during the preparation process.

[0124] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a modified soft magnetic composite alloy material, characterized in that, comprising: Step S1, mixing alloy powder and coupling agent, ball milling, screening, drying, annealing, and compounding to obtain modified alloy powder; Step S2, uniformly mixing low melting point powder and high resistivity nano powder, and performing sintering to obtain a coating agent with a porous structure; Step S3, mixing the modified alloy powder with the coating agent to obtain a modified soft magnetic composite alloy material.

2. The preparation method according to claim 1, characterized in that, the alloy powder includes any one or more of FeSi, FeNi, FeSiAl, FeNiMo, FeSiAlNi, FeSiCr, and FeSiAlTi; and / or, the coupling agent is any one or more of polyol surfactant, KH550, KH560, KH570, S510, S530, titanate coupling agent, and polyacrylamide; Preferably, the mass ratio of the coupling agent to the alloy powder is (0.2 - 1.5):

100.

3. The preparation method according to claim 1, characterized in that, in the step S1, the ball milling is wet ball milling. Preferably, the solvent used for the wet ball milling is any one or more of alcohol and acetone. Preferably, the ball milling time is 1 - 24 h, and the rotation speed frequency is 18 - 30 Hz; and / or, in the step S1, the annealing is carried out in an inert gas. Preferably, the annealing temperature is 600°C - 850°C, and the time is 1 - 5 h. Preferably, when performing the annealing, the heating rate is 1 - 5°C / min.

4. The preparation method according to claim 1, characterized in that, the low melting point powder includes any one or more of boron oxide powder, boric acid powder, and bismuth oxide powder; preferably, the low melting point powder includes a mixture of any one or more of boron oxide powder and bismuth oxide powder and boric acid powder; and / or, the high resistivity nano powder is any one or more of calcium oxide powder, alumina powder, and nano - silica powder; Preferably, the molar ratio of the low melting point powder to the high resistivity nano powder is 1:(4 - 5).

5. The preparation method according to claim 1, characterized in that, in the step S2, the sintering temperature is 1000 - 1400°C. Preferably, the heat preservation time is 1 - 3 h; preferably, the heating rate during the sintering is 1 - 5°C / min.

6. The preparation method according to claim 1, characterized in that, in the step S3, the mass ratio of the coating agent to the modified alloy powder is 0.1 - 5:

100.

7. A modified soft magnetic composite alloy material, characterized in that, it is prepared by the preparation method according to any one of claims 1 to 6.

8. A preparation method of a composite soft magnetic powder core, characterized in that, comprising: Mixing the modified soft magnetic composite alloy material according to claim 7 with a binder and a release agent to form a mixed powder, compacting the mixed powder into a shape, and annealing.

9. The preparation method according to claim 8, characterized in that, The binder includes any one or more of epoxy resin, silicone resin, phenolic resin and silicone resin. Preferably, the addition amount of the binder is 1 wt% - 5 wt% of the mixed powder; And / or, the release agent includes any one or more of zinc stearate, barium stearate, aluminum stearate and talcum powder. Preferably, the addition amount of the release agent is 0.3 wt% - 3 wt% of the mixed powder.

10. According to the preparation method described in claim 8, It is characterized in that, The pressure for the compression molding is 500 - 3000 MPa; And / or, the annealing is carried out in an inert gas atmosphere. Preferably, the heating rate of the annealing is 1.5 - 5 °C / min. Preferably, the treatment temperature of the annealing is 550 - 850 °C, and the time is 1 - 3 h; Preferably, the preparation method further includes: before the compression molding, passivating the modified soft magnetic composite alloy material. Preferably, the passivating agent for the passivation treatment includes any one or more of phosphoric acid, hydrogen peroxide and nitric acid. Preferably, the dosage of the passivating agent is 0.1 - 3 wt% of the modified soft magnetic composite alloy material; Preferably, before the compression molding treatment, the mixed powder is subjected to sieving treatment.

11. A composite soft magnetic powder core, It is characterized in that, It is prepared by the preparation method described in any one of claims 8 to 10.

Images