A composite soft magnetic material and its preparation method

Abstract

The present invention belongs to the field of semiconductor material technology. More specifically, it relates to a composite soft magnetic material and a preparation method thereof. The product prepared by the present invention includes coated FeNi particles and carbonyl iron powder; wherein, the mass ratio of the coated FeNi particles to the carbonyl iron powder is 1:(2.5-2.8); the D50 of the coated FeNi particles is 0.1-0.2 times the D50 of the carbonyl iron powder, and the D50 of the carbonyl iron powder is 1-10 μm; the coated FeNi particles include a FeNi particle core and a coating layer, the coating layer includes a titanium dioxide coating layer, and the average thickness of the titanium dioxide coating layer is 8-10% of the D50 of the FeNi particle core. The coating layer includes a titanium dioxide coating layer, and aluminum oxide deposited on the surface of the titanium dioxide coating layer, and pores are at least partially formed on the surface of the titanium dioxide coating layer, and at least part of the aluminum oxide is embedded in the pores.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor materials and more specifically relates to a composite soft magnetic material and a preparation method thereof. Background Art

[0002] Soft magnetic composite materials, also known as magnetic powder cores, are composite materials made by insulating soft magnetic powder and then pressing it under high pressure. Due to their properties such as easy mechanical forming, high magnetic permeability, and low loss, they have become a key material in power inductor components. From the perspective of power electronics applications, the development of third-generation wide-bandgap semiconductors is driving the increase in the power of power electronic devices, which places higher demands on inductor components. As power inductors develop towards high frequency, high current, and miniaturization, soft magnetic composite materials are also required to have low loss at high operating frequencies and good DC bias characteristics. Soft magnetic composite materials can be customized to meet the different needs of different application scenarios, making them suitable for large-scale manufacturing and having greater industrial prospects. As a result, soft magnetic composite materials are beginning to be widely used in industry.

[0003] For soft magnetic composite materials, it's important not only to consider whether their magnetic permeability meets the design requirements for the inductor's inductance, but also to consider the composite's impact on the inductor's saturation current, losses, cutoff frequency, and other aspects. Currently, the most common method for adjusting the electromagnetic properties of one-piece inductors is to compound soft magnetic powders with different electromagnetic properties, combining the advantages of several powders to create a soft magnetic composite with better overall performance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the problem of large eddy current loss of existing composite soft magnetic materials during use, and provide a composite soft magnetic material and a preparation method thereof.

[0005] The purpose of the present invention is to provide a composite soft magnetic material.

[0006] Another object of the present invention is to provide a method for preparing the composite soft magnetic material.

[0007] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0008] A composite soft magnetic material comprising coated FeNi particles and carbonyl iron powder;

[0009] Wherein, the mass ratio of the coated FeNi particles to the carbonyl iron powder is 1:(2.5-2.8);

[0010] The D50 of the coated FeNi particles is 0.1-0.2 times the D50 of the carbonyl iron powder, and the D50 of the carbonyl iron powder is 1-10 μm;

[0011] The coated FeNi particles include a FeNi particle core and a coating layer. The coating layer includes a titanium dioxide coating layer. The average thickness of the titanium dioxide coating layer is 8-10% of the D50 of the FeNi particle core.

[0012] The above technical solution coats the surface of FeNi particles with a titanium dioxide coating layer. First, titanium dioxide, as a wide bandgap semiconductor, has a high resistivity, which can hinder the flow of current, especially through coating, isolating the conductive coupling between particles and reducing eddy current loss; secondly, the presence of the titanium dioxide coating layer can reduce the eddy current flow area, that is, the eddy current needs to bypass the titanium dioxide coating layer to flow, significantly increasing the path length of the eddy current, thereby significantly reducing the eddy current intensity; and in the composite material system of FeNi particles and carbonyl iron powder, by adjusting the reasonable sizes of the two to obtain a relatively good gradation, thereby obtaining a higher packing density, which is helpful for improving the comprehensive performance of the product. However, the inventors found that in this case, it is necessary to It is necessary to control the thickness of the titanium dioxide coating layer to ensure that the comprehensive performance is effectively exerted. This is because, on the one hand, the FeNi particles with a particle size significantly smaller than that of the carbonyl iron powder have a higher surface energy and are prone to agglomeration. After agglomeration, it is difficult to achieve uniform filling of the pores between the carbonyl iron powder particles, and the secondary particles formed by agglomeration will lead to an increase in local eddy current losses. By coating with titanium dioxide, its surface energy can be effectively reduced and its agglomeration can be reduced; on the other hand, if the average thickness of the coating layer is too low, when wrapping on particles of corresponding particle size, it is difficult for large particles to form a continuous and complete coating layer, and small particles are prone to excessive coating. Then, the probability of direct contact between FeNi particles increases, which will still affect the effect of reducing eddy current losses.

[0013] Furthermore, the coating layer includes a titanium dioxide coating layer and aluminum oxide deposited on the surface of the titanium dioxide coating layer, and pores are at least partially formed on the surface of the titanium dioxide coating layer, and at least part of the aluminum oxide is embedded in the pores.

[0014] The above technical solution further deposits alumina in the pores of the titanium dioxide coating layer to compensate for the performance defects caused by its pore defects, and can make the surface of the coated FeNi particles smooth, which is conducive to better filling and performance.

[0015] Furthermore, the mass of the aluminum oxide is 2-4% of the total mass of the FeNi particle core and the titanium dioxide coating layer.

[0016] Furthermore, the aluminum oxide is distributed in an island shape on the surface of the titanium dioxide coating layer.

[0017] By regulating the amount of alumina coating, we can avoid too little coating, which would make it difficult to effectively fill the pores, and also prevent too much coating, which would affect the performance of the product. By regulating its island distribution, it is actually achieved by adapting to the pores on the surface of the titanium dioxide coating layer. In other words, deposition is only formed at the pores. In this way, the degradation of product performance caused by excessive use of alumina can be avoided as much as possible.

[0018] Furthermore, the carbonyl iron powder further includes a silicon dioxide coating layer on the surface, and the average thickness of the silicon dioxide coating layer is 8-10% of the D50 of the carbonyl iron powder.

[0019] Furthermore, the sphericity of the core of the FeNi particles is 8.5-9.0.

[0020] A method for preparing a composite soft magnetic material, the specific preparation steps comprising:

[0021] Preparation of coated FeNi particles: The FeNi particle core is dispersed in an ethanol solution, and sodium dodecylbenzenesulfonate is added at a concentration of 0.3-0.5% of the mass of the FeNi particle core. After adjusting the pH to 7.5-7.7, tetrabutyl titanate is slowly added dropwise to form a precursor coating layer on the surface of the FeNi particle. After the addition is completed, the solution is aged for 12-24 hours, filtered, washed and dried to obtain a dry filter cake, which is then calcined under inert gas protection to form a titanium dioxide coating layer on the surface of the FeNi particle core.

[0022] Furthermore, the slow dripping is: dripping at a rate of 8-12 mL / min.

[0023] Furthermore, the preparation of the coated FeNi particles further comprises:

[0024] Aluminum oxide is deposited on the surface of the titanium dioxide coating layer: after the titanium dioxide coating layer is formed on the surface of the FeNi particle core, its moisture content is adjusted to 2.5-2.8%, and then a mixed gas containing trimethylaluminum is introduced to complete the deposition of aluminum hydroxide. After the deposition is completed, calcination is performed to convert the aluminum hydroxide into aluminum oxide, thereby completing the deposition of aluminum oxide.

[0025] Furthermore, the mixed gas is formed by mixing trimethylaluminum gas and nitrogen in a volume ratio of 1:20-1:25.

[0026] In the above preparation process, tetrabutyl titanate is first used as a titanium source, and the pH and the drop rate of tetrabutyl titanate are controlled to ensure its high crystallinity and reduce the defects of the coating layer. In addition, with the auxiliary effect of sodium dodecylbenzene sulfonate, it is not only beneficial for the FeNi particle core to be uniformly and stably dispersed during the preparation process, so that its surface is fully and uniformly deposited, but also beneficial for the uniform adsorption of the hydrolysis product of tetrabutyl titanate on its surface. However, due to the presence of residual sodium dodecylbenzene sulfonate, it will cause pores or surface defects to be generated during the calcination process. By further hydrolyzing and depositing with a gaseous aluminum source, aluminum hydroxide can be effectively deposited in the pores or surface defects. Finally, after calcination, a stable aluminum oxide is generated, which effectively fills the pores and surface defects and ensures the integrity of the particle surface. DETAILED DESCRIPTION

[0027] The present invention is further described below with reference to specific examples, which, however, are not intended to limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0028] Unless otherwise specified, the reagents and materials used in the following examples were commercially available.

[0029] Example 1

[0030] Preparation of coated FeNi particles:

[0031] With FeNi particles as the core, FeNi particles and a 65% ethanol solution by mass were mixed in a mass ratio of 1:10 and poured into a reactor, and sodium dodecylbenzene sulfonate (0.3% by mass of the FeNi particles) was added. After ultrasonic dispersion for 30 minutes at an ultrasonic frequency of 100 kHz, the pH of the material in the reactor was adjusted to 7.5. Subsequently, tetrabutyl titanate was continuously added dropwise to the reactor at a rate of 8 mL / min under stirring, wherein the stirring speed was controlled at 500 r / min, and the amount of tetrabutyl titanate was 0.55 times the mass of the FeNi particles. After the addition of tetrabutyl titanate was completed, stirring was stopped and the mixture was heated to room temperature. The mixture was aged at 65°C for 12 hours; filtered, the filter cake was collected, and the filter cake was washed with deionized water until the washing liquid was neutral, and then the washed filter cake was transferred to an oven and dried at 100°C to constant weight to obtain a dry filter cake; the obtained dry filter cake was transferred to a carbonization furnace, heated to 380°C in an argon atmosphere, kept warm and calcined for 120 minutes, and then cooled to room temperature with the furnace and discharged to form a titanium dioxide coating layer on the surface of the FeNi particles. By adjusting the amount of tetrabutyl titanate and the preparation process, the average thickness of the titanium dioxide coating layer was adjusted to 8% of the D50 of the FeNi particles, thereby obtaining pretreated FeNi particles;

[0032] The obtained pretreated FeNi particles were sprayed with water to adjust their moisture content to 2.5%, and then transferred to a tube furnace, and a mixed gas containing trimethylaluminum was continuously introduced into the tube furnace at a rate of 30 L / min. Specifically, the introduction time was adjusted according to the mass of the pretreated FeNi particles, and it was controlled that for every 1 kg of pretreated FeNi particles, continuous ventilation was required for 0.3 min to convert, so that alumina was deposited in the pores on the surface of the titanium dioxide coating layer and formed an island distribution, and the mass of the alumina product corresponded to 2% of the mass of the pretreated FeNi particles, wherein the mass of the pretreated FeNi particles was the mass before the moisture content was adjusted; after the deposition was completed, the temperature was raised to 360° C., kept warm and calcined for 20 min, and then cooled to room temperature with the furnace to obtain coated FeNi particles;

[0033] The mixed gas is a mixture of trimethylaluminum gas and nitrogen gas in a volume ratio of 1:20.

[0034] The sphericity of the FeNi particles is 8.5;

[0035] Raw materials preparation:

[0036] The coated FeNi particles and carbonyl iron powder were weighed in a mass ratio of 1:2.5, and 1.5% of the mass of the coated FeNi particles was added with a silane coupling agent KH-560, and the mixture was stirred at 300 r / min for 1 h to obtain a mixed powder;

[0037] The carbonyl iron powder is a carbonyl iron powder coated with a silicon dioxide coating layer, wherein the D50 of the carbonyl iron powder is 1 μm; the average thickness of the silicon dioxide coating layer is 8% of the D50 of the carbonyl iron powder; specifically, the carbonyl iron powder is a material produced by BASF (China) Co., Ltd.

[0038] Before weighing, the coated FeNi particles were sieved to obtain particles with a D50 of 0.1 times the D50 of the carbonyl iron powder;

[0039] According to weight, 100 parts of mixed powder, 150 parts of acetone, 1 part of epoxy resin E-44, and 0.06 parts of epoxy resin curing agent are taken in sequence. The epoxy resin E-44 and acetone are first mixed and dissolved, and then the mixed powder is added. After stirring and mixing at a speed of 600 r / min for 1 hour, the epoxy resin curing agent is added, and the stirring and mixing is continued for 10 minutes. The mixture is dried to remove the acetone, and then the mixture is pressed into shape in a hydraulic press at 580 MPa, and then heat-treated at 180°C for 45 minutes. The mixture is cooled and discharged to obtain a composite soft magnetic material.

[0040] Example 2

[0041] Preparation of coated FeNi particles:

[0042] With FeNi particles as the core, FeNi particles and 65% ethanol solution were mixed in a mass ratio of 1:10 and poured into a reactor, and sodium dodecylbenzene sulfonate (0.4% by mass of FeNi particles) was added. After ultrasonic dispersion for 30 minutes at an ultrasonic frequency of 110 kHz, the pH of the material in the reactor was adjusted to 7.6. Then, tetrabutyl titanate was continuously added dropwise to the reactor at a rate of 10 mL / min under stirring, wherein the stirring speed was controlled at 500 r / min, and the amount of tetrabutyl titanate was 0.59 times the mass of the FeNi particles. After the addition of tetrabutyl titanate was completed, stirring was stopped and the temperature was set at 400 °C. The mixture was statically aged at 65° C. for 18 hours; filtered, the filter cake was collected, and the filter cake was washed with deionized water until the washing liquid was neutral, and then the washed filter cake was transferred to an oven and dried at 100° C. to constant weight to obtain a dry filter cake; the obtained dry filter cake was then transferred to a carbonization furnace, heated to 390° C. in an argon atmosphere, kept warm and calcined for 160 minutes, and then cooled to room temperature with the furnace and discharged to form a titanium dioxide coating layer on the surface of the FeNi particles. By adjusting the amount of tetrabutyl titanate and the preparation process, the average thickness of the titanium dioxide coating layer was adjusted to 9.2% of the D50 of the FeNi particles, thereby obtaining pretreated FeNi particles;

[0043] The obtained pretreated FeNi particles were sprayed with water to adjust their moisture content to 2.7%, and then transferred to a tube furnace, and a mixed gas containing trimethylaluminum was continuously introduced into the tube furnace at a rate of 36 L / min. Specifically, the introduction time was adjusted according to the mass of the pretreated FeNi particles, and it was controlled that for every 1 kg of pretreated FeNi particles, continuous ventilation was required for 0.35 min to convert, so that alumina was deposited in the pores on the surface of the titanium dioxide coating layer and formed an island distribution, and the mass of the alumina product corresponded to 2.8% of the mass of the pretreated FeNi particles, wherein the mass of the pretreated FeNi particles was the mass before the moisture content was adjusted; after the deposition was completed, the temperature was raised to 360° C., kept warm and calcined for 20 min, and then cooled to room temperature with the furnace to obtain coated FeNi particles;

[0044] The mixed gas is a mixture of trimethylaluminum gas and nitrogen gas in a volume ratio of 1:23.

[0045] The sphericity of the FeNi particles is 8.8;

[0046] Raw materials preparation:

[0047] The coated FeNi particles and carbonyl iron powder were weighed in a mass ratio of 1:2.6, and 1.5% of the mass of the coated FeNi particles was added with a silane coupling agent KH-560, and the mixture was stirred at 300 r / min for 1 h to obtain a mixed powder;

[0048] The carbonyl iron powder is a carbonyl iron powder coated with a silicon dioxide coating layer, wherein the D50 of the carbonyl iron powder is 6 μm; the average thickness of the silicon dioxide coating layer is 9.5% of the D50 of the carbonyl iron powder; specifically, the carbonyl iron powder is a material produced by BASF (China) Co., Ltd.

[0049] Before weighing, the coated FeNi particles were sieved to obtain particles with a D50 of 0.15 times the D50 of the carbonyl iron powder;

[0050] According to weight, 110 parts of mixed powder, 160 parts of acetone, 1.15 parts of epoxy resin E-44, and 0.065 parts of epoxy resin curing agent are taken in sequence. The epoxy resin E-44 and acetone are first mixed and dissolved, and then the mixed powder is added. After stirring and mixing at a speed of 600 r / min for 1 hour, the epoxy resin curing agent is added, and stirring and mixing is continued for 10 minutes. The mixture is dried to remove the acetone, and then pressed into shape in a hydraulic press at 580 MPa, and then heat-treated at 180°C for 45 minutes. The mixture is cooled and discharged to obtain a composite soft magnetic material.

[0051] Example 3

[0052] Preparation of coated FeNi particles:

[0053] With FeNi particles as the core, FeNi particles and a 65% mass fraction of ethanol solution were mixed in a mass ratio of 1:10 and poured into a reactor, and sodium dodecylbenzene sulfonate (0.5% by mass of FeNi particles) was added. After ultrasonic dispersion for 30 minutes at an ultrasonic frequency of 120 kHz, the pH of the material in the reactor was adjusted to 7.7. Subsequently, tetrabutyl titanate was continuously added dropwise to the reactor at a rate of 12 mL / min under stirring, wherein the stirring speed was controlled at 500 r / min, and the amount of tetrabutyl titanate was 0.62 times the mass of the FeNi particles. After the addition of tetrabutyl titanate was completed, stirring was stopped and the mixture was heated to room temperature. The mixture was statically aged at 65°C for 24 hours; filtering, collecting the filter cake, and washing the filter cake with deionized water until the washing liquid was neutral, then transferring the washed filter cake into an oven and drying it at 100°C to constant weight to obtain a dry filter cake; then transferring the obtained dry filter cake into a carbonization furnace, heating it to 400°C in an argon atmosphere, calcining it at that temperature for 180 minutes, cooling it to room temperature with the furnace, and discharging it to form a titanium dioxide coating layer on the surface of the FeNi particles, and adjusting the amount of tetrabutyl titanate and the preparation process to adjust the average thickness of the titanium dioxide coating layer to 10% of the D50 of the FeNi particles, thereby obtaining pretreated FeNi particles;

[0054] The obtained pretreated FeNi particles were sprayed with water to adjust the moisture content to 2.8%, and then transferred to a tube furnace, and a mixed gas containing trimethylaluminum was continuously introduced into the tube furnace at a rate of 40 L / min. Specifically, the introduction time was adjusted according to the mass of the pretreated FeNi particles, and it was controlled that for every 1 kg of pretreated FeNi particles, continuous ventilation was required for 0.4 min to convert, so that alumina was deposited in the pores on the surface of the titanium dioxide coating layer and formed an island distribution, and the mass of the alumina product corresponded to 4% of the mass of the pretreated FeNi particles, wherein the mass of the pretreated FeNi particles was the mass before the moisture content was adjusted; after the deposition was completed, the temperature was raised to 360° C., kept warm and calcined for 20 min, and then cooled to room temperature with the furnace to obtain coated FeNi particles;

[0055] The mixed gas is a mixture of trimethylaluminum gas and nitrogen gas in a volume ratio of 1:25.

[0056] The sphericity of the FeNi particles is 9.0;

[0057] Raw materials preparation:

[0058] The coated FeNi particles and carbonyl iron powder were weighed in a mass ratio of 1:2.8, and 1.5% of the mass of the coated FeNi particles was added with a silane coupling agent KH-560, and the mixture was stirred at 300 r / min for 1 h to obtain a mixed powder;

[0059] The carbonyl iron powder is a carbonyl iron powder coated with a silicon dioxide coating layer, wherein the D50 of the carbonyl iron powder is 10 μm; the average thickness of the silicon dioxide coating layer is 10% of the D50 of the carbonyl iron powder; specifically, the carbonyl iron powder is a material produced by BASF (China) Co., Ltd.

[0060] Before weighing, the coated FeNi particles were sieved to obtain particles with a D50 of 0.2 times the D50 of the carbonyl iron powder;

[0061] According to weight, 120 parts of mixed powder, 180 parts of acetone, 1.2 parts of epoxy resin E-44, and 0.08 parts of epoxy resin curing agent are taken in sequence. The epoxy resin E-44 and acetone are first mixed and dissolved, and then the mixed powder is added. After stirring and mixing at a speed of 600 r / min for 1 hour, the epoxy resin curing agent is added, and the stirring and mixing is continued for 10 minutes. The mixture is dried to remove the acetone, and then the mixture is pressed into shape in a hydraulic press at 580 MPa, and then heat-treated at 180°C for 45 minutes. The mixture is cooled and discharged to obtain a composite soft magnetic material.

[0062] Example 4

[0063] The difference between this embodiment and embodiment 1 is that pure nitrogen is used instead of the mixed gas, and the other conditions remain unchanged.

[0064] Example 5

[0065] Compared with Example 1, this embodiment has the following differences:

[0066] Preparation of coated FeNi particles:

[0067] With FeNi particles as the core, FeNi particles and a 65% ethanol solution by mass were mixed in a mass ratio of 1:10 and poured into a reactor, and sodium dodecylbenzene sulfonate (0.3% by mass of the FeNi particles) was added. After ultrasonic dispersion for 30 minutes at an ultrasonic frequency of 100 kHz, the pH of the material in the reactor was adjusted to 7.5. Subsequently, tetrabutyl titanate was continuously added dropwise to the reactor at a rate of 8 mL / min under stirring, wherein the stirring speed was controlled at 500 r / min, and the amount of tetrabutyl titanate was 0.55 times the mass of the FeNi particles. After the addition of tetrabutyl titanate was completed, stirring was stopped and the mixture was heated to room temperature. The mixture was aged at 65°C for 12 hours; filtered, the filter cake was collected, and the filter cake was washed with deionized water until the washing liquid was neutral, and then the washed filter cake was transferred to an oven and dried at 100°C to constant weight to obtain a dry filter cake; the obtained dry filter cake was transferred to a carbonization furnace, heated to 380°C in an argon atmosphere, kept warm and calcined for 120 minutes, and then cooled to room temperature with the furnace and discharged to form a titanium dioxide coating layer on the surface of the FeNi particles. By adjusting the amount of tetrabutyl titanate and the preparation process, the average thickness of the titanium dioxide coating layer was adjusted to 8% of the D50 of the FeNi particles, thereby obtaining pretreated FeNi particles;

[0068] The obtained pretreated FeNi particles were dispersed in a 10% by mass aluminum chloride solution, and ammonia water was used as a precipitant. After adjusting the pH to 7.8, the mixture was stirred at 300 r / min with a stirrer for 30 minutes. The filter cake was then filtered and collected. The filter cake was washed with deionized water until the washing liquid was neutral. The washed filter cake was then transferred to an oven and dried to constant weight at 100°C. The dried filter cake was then transferred to a muffle furnace, heated to 360°C, kept warm and calcined for 20 minutes, and then cooled to room temperature with the furnace to obtain coated FeNi particles.

[0069] The sphericity of the FeNi particles is 8.5;

[0070] The rest of the conditions remain unchanged.

[0071] Comparative Example 1

[0072] Compared with Example 1, this comparative example has the following differences:

[0073] Preparation of coated FeNi particles:

[0074] The FeNi particles are sprayed with water to adjust their moisture content to 2.5%, and then transferred to a tube furnace. A mixed gas containing trimethylaluminum is continuously introduced into the tube furnace at a rate of 30 L / min. Specifically, the introduction time is adjusted according to the mass of the FeNi particles, and it is controlled that for every 1 kg of FeNi particles, continuous ventilation is required for 0.3 min to convert so that aluminum oxide is deposited on the surface of the FeNi particles, and the mass of the aluminum oxide product corresponds to 2% of the mass of the FeNi particles, wherein the mass of the FeNi particles is the mass before the moisture content is adjusted; after the deposition is completed, the temperature is raised to 360° C., kept warm and calcined for 20 minutes, and then cooled to room temperature with the furnace to obtain coated FeNi particles;

[0075] The mixed gas is a mixture of trimethylaluminum gas and nitrogen gas in a volume ratio of 1:20.

[0076] The sphericity of the FeNi particles is 8.5;

[0077] The rest of the conditions remain unchanged.

[0078] Blank example

[0079] Raw materials preparation:

[0080] Prepare carbonyl iron powder, add 1.5% of the mass of carbonyl iron powder to the silane coupling agent KH-560, and stir and mix with a stirrer at 300 r / min for 1 hour to obtain a mixed powder;

[0081] The carbonyl iron powder is a carbonyl iron powder coated with a silicon dioxide coating layer, wherein the D50 of the carbonyl iron powder is 1 μm; the average thickness of the silicon dioxide coating layer is 8% of the D50 of the carbonyl iron powder; specifically, the carbonyl iron powder is a material produced by BASF (China) Co., Ltd.

[0082] According to weight, 100 parts of mixed powder, 150 parts of acetone, 1 part of epoxy resin E-44, and 0.06 parts of epoxy resin curing agent are taken in sequence. The epoxy resin E-44 and acetone are first mixed and dissolved, and then the mixed powder is added. After stirring and mixing at a speed of 600 r / min for 1 hour, the epoxy resin curing agent is added, and the stirring and mixing is continued for 10 minutes. The mixture is dried to remove the acetone, and then the mixture is pressed into shape in a hydraulic press at 580 MPa, and then heat-treated at 180°C for 45 minutes. The mixture is cooled and discharged to obtain a composite soft magnetic material.

[0083] The performance tests of the products obtained in the examples and comparative examples were carried out, and the specific test methods and test results are as follows:

[0084] An inductor having a specification of 2.0 mm × 1.5 mm × 1.0 mm was prepared in accordance with the embodiment or the comparative example to form an integrally formed inductor, and its nominal inductance was 2.2 μH.

[0085] The quality factor of the one-piece molded inductor was tested at different frequencies. The quality factor refers to the ratio of the inductive reactance to the DC resistance of the inductor when operating under an alternating current at a certain frequency. The higher the quality factor, the lower the energy loss and the higher the efficiency.

[0086] Taking the product prepared in the blank example as a benchmark, calculate the quality factor improvement rate of the products obtained in other examples or comparative examples relative to the blank example;

[0087] In addition, the frequency corresponding to the point where the quality factor is zero is the self-resonant frequency of the inductor; the product prepared in the blank example is used as a benchmark, and the improvement rate of the self-resonant frequency of the products obtained in the other embodiments or comparative examples relative to the blank example is calculated;

[0088] The detailed test results are shown in Table 1:

[0089] Table 1: Product performance test results

[0090]

[0091] It can be seen from the test results in Table 1 that the product obtained by the present invention can improve the performance of the soft magnetic composite material, especially reduce its eddy current loss, compared with single carbonyl iron powder.

[0092] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A composite soft magnetic material, characterized in that: Including coated FeNi particles and carbonyl iron powder; Among them, the mass ratio of coated FeNi particles and carbonyl iron powder is 1: (2.5-2.8); The D50 of the coated FeNi particles is 0.1-0.2 times that of the carbonyl iron powder, and the D50 of the carbonyl iron powder is 1-10 μm; The coated FeNi particles include a FeNi particle core and a coating layer, wherein the coating layer includes a titanium dioxide coating layer, and the average thickness of the titanium dioxide coating layer is 8-10% of the D50 of the FeNi particle core; The coating layer includes a titanium dioxide coating layer and aluminum oxide deposited on the surface of the titanium dioxide coating layer, and pores are at least partially formed on the surface of the titanium dioxide coating layer, and at least a portion of the aluminum oxide is embedded in the pores; The mass of alumina is 2-4% of the total mass of the FeNi particle core and the titanium dioxide coating; Alumina is distributed in island shape on the surface of the titanium dioxide coating layer.

2. The composite soft magnetic material according to claim 1, characterized in that The carbonyl iron powder further includes a silicon dioxide coating layer on the surface, and the average thickness of the silicon dioxide coating layer is 8-10% of the carbonyl iron powder D50.

3. The composite soft magnetic material according to claim 1, characterized in that The sphericity of the FeNi particle core is 8.5-9.

0.

4. A method for preparing a composite soft magnetic material according to any one of claims 1 to 3, characterized in that: The specific preparation steps include: Preparation of coated FeNi particles: The FeNi particle cores are dispersed in an ethanol solution, and sodium dodecylbenzene sulfonate is added at a rate of 0.3-0.5% by weight of the FeNi particle cores. After adjusting the pH to 7.5-7.7, tetrabutyl titanate is slowly added dropwise to form a precursor coating layer on the surface of the FeNi particles. After the addition is completed, the solution is aged for 12-24 hours, filtered, washed, and dried to obtain a dry filter cake. The dry filter cake is then calcined under inert gas protection to form a titanium dioxide coating layer on the surface of the FeNi particle cores. The slow addition is performed at a rate of 8-12 mL / min. The preparation of the coated FeNi particles further comprises: Deposition of aluminum oxide on the surface of the titanium dioxide coating: After a titanium dioxide coating is formed on the surface of the FeNi particle core, its moisture content is adjusted to 2.5-2.8%, and then a mixed gas containing trimethylaluminum is introduced to complete the deposition of aluminum hydroxide. After the deposition is completed, calcination is performed to convert the aluminum hydroxide into aluminum oxide, thus completing the deposition of aluminum oxide.

5. The method for preparing a composite soft magnetic material according to claim 4, wherein: The mixed gas is formed by mixing trimethylaluminum gas and nitrogen in a volume ratio of 1:20-1:25.

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