A high-frequency low-loss soft magnetic material and its preparation method

Abstract

This application relates to the field of soft magnetic materials, and specifically discloses a high-frequency low-loss soft magnetic material and a preparation method thereof. A preparation method of a high-frequency low-loss soft magnetic material includes the following steps; (1) Mix and dissolve an iron salt, a zincate salt and a manganese salt to obtain a mixed salt solution, then add a rare earth salt solution, and then add a precipitating agent, stir and react, and then filter, wash, dry, calcine and refine the reacted solution to obtain rare earth-doped ferrite powder; (2) Sinter once, crush and screen to obtain a pre-sintered material; (3) Mix four powders of lrO 2 , MoO 2 , CNTs, and BNNT to obtain an intermediate powder; (4) Mix the pre-sintered material, the intermediate powder and a lubricant evenly and then press to form a green body, and then perform secondary sintering on the green body to obtain Mn-Zn soft magnetic ferrite. The ferrite prepared by the preparation method of this application has excellent magnetic properties and low loss at high frequencies.

Description

Technical Field

[0001] This application relates to the field of soft magnetic materials, and more specifically, it relates to a high-frequency low-loss soft magnetic material and a preparation method thereof. Background Art

[0002] The continuous progress of power electronics technology has put forward higher requirements for the performance of power transmission devices. With the continuous development of devices towards miniaturization, integration, lightweight, high-frequency, etc., the development of high-performance high-frequency power ferrite materials suitable for the MHz level has become the core task in the research field of soft magnetic materials.

[0003] As a soft magnetic material with a spinel structure, ferrite has become an indispensable part of the electronics industry due to its high magnetic permeability, high saturation magnetization intensity and low loss characteristics, and is widely used in various fields such as communication, sensing, television sets, switching power supplies and magnetic heads. Improving the magnetic properties of ferrite and reducing its loss at high frequencies have become problems that need to be urgently concerned and solved in this application field. Summary of the Invention

[0004] In order to improve the magnetic properties of ferrite and reduce its loss at high frequencies, this application provides a high-frequency low-loss soft magnetic material and a preparation method thereof.

[0005] The preparation method of a high-frequency low-loss soft magnetic material provided by this application adopts the following technical scheme:

[0006] A preparation method of a high-frequency low-loss soft magnetic material, characterized by comprising the following steps:

[0007] (1) Mix and dissolve iron salt, zincate and manganese salt to obtain a mixed salt solution, then add a rare earth salt solution, then add a precipitant, stir and react, then filter the reacted solution, and take the filter residue, wash, dry, calcine and refine it to obtain rare earth-doped ferrite powder;

[0008] (2) Sinter the rare earth-doped ferrite powder once, then crush and screen it to obtain a pre-sintered material;

[0009] (3) Mix lrO 2 , MoO 2 , CNTs, and BNNT four powders, add ethanol, stir magnetically and then perform ultrasonic dispersion, filter, take the filter residue, wash, dry and refine it to obtain intermediate powder;

[0010] (4) Mix the pre-sintered material, intermediate powder and lubricant evenly, then press to form a green body, and then perform secondary sintering on the green body to obtain Mn-Zn soft ferrite.

[0011] Optionally, in step (1), the molar ratio of the iron salt, zincate, and manganese salt is (2-5):(0.2-1):1;

[0012] In step (1), the solute in the rare earth salt solution is La(NO 3 ) 3 and Pr(NO 3 ) 3 with a molar ratio of 1:(0.5-2);

[0013] In step (1), the volume ratio of the rare earth salt solution to the mixed salt solution is 1:(1-3).

[0014] Optionally, in step (2), the sintering temperature for the first sintering is 700-1000 °C, and the sintering time is 1-3 h.

[0015] Optionally, in step (3), based on the pre-sintered material, the addition amounts of the four powders of lrO 2 , MoO 2 , CNTs, and BNNT do not exceed 0.5%-3% of the weight of the pre-sintered material.

[0016] Optionally, in step (3), the power of ultrasonic dispersion is 120 W, and the time is 30 min.

[0017] Optionally, in step (4), the sintering temperature for the second sintering is 1300-1500 °C, and the sintering time is 3-7 h.

[0018] Optionally, in step (4), the lubricant is barium stearate. Based on the pre-sintered material, the addition amount of the lubricant is 0.1-1.5 Wt%, and the pressing pressure is 10-20 T / cm 2 .

[0019] Optionally, in step (1), the refinement treatment is as follows: Using acetone and polyethylene glycol ethyl ether as grinding aids, ball-milling the calcined solid at a rotation speed of 300 r / min for 2 h, taking it out, washing, filtering by suction, and drying in vacuum to obtain rare earth-doped ferrite powder.

[0020] Optionally, in step (1), the precipitant is NH 3 ·H 2 O.

[0021] In the second aspect, the present application provides a high-frequency low-loss soft magnetic material prepared by the above preparation method.

[0022] In summary, the present application has the following beneficial effects:

[0023] 1. The rare earth salt solution (La(NO 3 ) 3 , Pr(NO 3 )3 ) not only enhances the density of the material, but also changes the crystal structure and magnetic domain structure of the material, thereby improving its magnetic permeability. It also helps the uniform growth of grains and increases the resistivity, thereby reducing the eddy current loss of the material.

[0024] 2. By doping lrO 2 、MoO 2 The key properties of soft magnetic materials such as uniformity, pores and particle size are fully demonstrated, which is conducive to the growth of grains and the improvement of resistivity, thereby significantly enhancing the electromagnetic properties of the product and giving the material excellent magnetic permeability and high saturation magnetic induction intensity.

[0025] 3. CNTs and BNNTs have good electrical conductivity and magnetic properties. Their addition helps to improve the magnetic permeability of soft magnetic materials and reduce the coercive force of soft magnetic materials. DETAILED DESCRIPTION

[0026] The present application is further described in detail below with reference to the embodiments.

[0027] Example

[0028] Example 1

[0029] A high-frequency, low-loss soft magnetic material, the preparation method of which is as follows:

[0030] (1) Ingredients: FeSO 4 、Na 2 Zn(OH) 4 、MnSO 4 The mixture was prepared in a molar ratio of 2:0.2:1 and then completely dissolved in deionized water to obtain a mixed salt solution. 3 ) 3 and Pr(NO 3 ) 3 The rare earth salt solution was prepared in a molar ratio of 1:0.5, and the rare earth salt solution and the mixed salt solution were mixed and stirred in a volume ratio of 1:1. At this time, NH 3 ·H 2 O, stirring for reaction, then filtering the solution after the reaction, taking the filter residue and washing it with deionized water for several times until the pH value of the washing solution reaches about 7, drying it in a vacuum drying oven, calcining the dried powder at 800°C for 300min, and then using acetone and polyglycol ether as grinding aids, ball milling the calcined solid at a speed of 300r / min for 2h, taking it out, washing, filtering and vacuum drying to obtain rare earth doped ferrite powder;

[0031] (2) Primary sintering: sintering the rare earth-doped ferrite powder at 700°C for 3 h, and then crushing and sieving the sintered material to obtain a pre-sintered material;

[0032] (3) Ultrasonic dispersion: Mix lrO 2 , MoO 2 , CNTs, and BNNT four kinds of powders. Based on the pre-sintered material, the addition amounts of lrO 2 , MoO 2 , CNTs, and BNNT four kinds of powders are 0.5%, 0.5%, 0.5%, and 0.5% of the weight of the pre-sintered material respectively; after mixing, add ethanol solution, turn on the magnetic stirrer, and conduct preliminary stirring on the solution to make the above solution and ethanol preliminarily mixed. Subsequently, perform ultrasonic dispersion: Use an ultrasonic disperser to perform ultrasonic treatment on the solution to make it better dispersed in the ethanol solution. Among them, the ultrasonic time is 30 min and the power is 120 W; after filtration, take the filter residue and wash it with deionized water multiple times until the pH value of the washing solution is about 7, and then perform drying to obtain the intermediate powder;

[0033] (4) Ball milling: Mix the intermediate powder and the pre-sintered material, and ball mill at a speed of 300 r / min for 5 h. After taking it out, wash, filter by suction, and vacuum dry to obtain a uniformly mixed powder;

[0034] (5) Compression molding: Mix the powder obtained in (4) with the lubricant barium stearate evenly. The addition amount of barium stearate is 0.1 Wt%, and press it into a ring-shaped sample under a pressure of 15 T / cm 2 ;

[0035] (6) Secondary sintering: Adopt a power bell-jar furnace for atmosphere sintering, with a sintering temperature of 1300 °C and a heat preservation time of 7 h to obtain Mn-Zn soft magnetic ferrite.

[0036] Example 2

[0037] A high-frequency low-loss soft magnetic material, and its preparation method is as follows:

[0038] (1) Batching: Configure FeSO 4 , Na 2 Zn(OH) 4 , MnSO 4 according to a molar ratio of 4:0.6:1, and then completely dissolve it with deionized water to obtain a mixed salt solution. Then, configure La(NO 3 ) 3 and Pr(NO 3 ) 3 according to a molar ratio of 1:1 to obtain a rare earth salt solution. Mix and stir the rare earth salt solution and the mixed salt solution at a volume ratio of 1:2. At this time, add 2 times the volume of the solution of NH 3 ·H 2O, stirring for reaction, then filtering the solution after the reaction, taking the filter residue and washing it with deionized water for several times until the pH value of the washing solution reaches about 7, drying it in a vacuum drying oven, calcining the dried powder at 900°C for 250min, and then using acetone and polyglycol ether as grinding aids, ball milling the calcined solid at a speed of 300r / min for 2h, taking it out, washing, filtering and vacuum drying to obtain rare earth doped ferrite powder;

[0039] (2) Primary sintering: sintering the rare earth-doped ferrite powder at 900°C for 2 h, and then crushing and sieving the sintered material to obtain a pre-sintered material;

[0040] (3) Ultrasonic dispersion: lrO 2 、MoO 2 , CNTs, BNNT four kinds of powders are mixed, based on the pre-sintered material, lrO 2 、MoO 2 The addition amounts of the four kinds of powders, CNTs and BNNT, are 1.5%, 1.5%, 1.5% and 1.5% of the weight of the pre-sintered material, respectively; after mixing, ethanol solution is added, and a magnetic stirrer is turned on to preliminarily stir the solution so that the above solution and ethanol are preliminarily mixed, followed by ultrasonic dispersion: an ultrasonic disperser is used to ultrasonically treat the solution so that it is better dispersed in the ethanol solution, wherein the ultrasonic time is 30 minutes and the power is 120W; after filtering, the filter residue is washed with deionized water for several times until the pH value of the washing solution reaches about 7, and then dried to obtain an intermediate powder;

[0041] (4) Ball milling: The intermediate powder is mixed with the pre-sintered material, and ball milled at a speed of 300 r / min for 5 h. After being taken out, it is washed, filtered and vacuum dried to obtain a uniformly mixed powder;

[0042] (5) Compression molding: The powder obtained in (4) was mixed evenly with the lubricant barium stearate, the addition amount of barium stearate was 1.0wt%, and the temperature was 15T / cm 2 Pressed into a ring-shaped sample under pressure;

[0043] (6) Secondary sintering: The sintering was carried out in a power bell furnace atmosphere at a sintering temperature of 1400°C and kept at this temperature for 5 hours to obtain Mn-Zn soft ferrite.

[0044] Example 3

[0045] A high-frequency, low-loss soft magnetic material, the preparation method of which is as follows:

[0046] (1) Ingredients: FeSO 4 、Na 2 Zn(OH) 4 、MnSO 4Prepare according to a molar ratio of 5:1:1, and then completely dissolve it with deionized water to obtain a mixed salt solution. Then, La(NO 3 ) 3 and Pr(NO 3 ) 3 Prepare a rare earth salt solution according to a molar ratio of 1:2. Mix and stir the rare earth salt solution and the mixed salt solution at a volume ratio of 1:3. At this time, add NH 3 ·H 2 O with a volume twice that of the solution, stir and react. Then, filter the reacted solution, take the filter residue, and wash it with deionized water multiple times until the pH value of the washing solution is about 7. Dry it in a vacuum drying oven. Calcinate the dried powder at 1000 °C for 800 min. Then, use acetone and polyethylene glycol ether as grinding aids, and ball-mill the calcined solid at a rotation speed of 300 r / min for 2 h. Take it out, wash, filter by suction, and vacuum-dry to obtain rare earth-doped ferrite powder;

[0047] (2) Primary sintering: Sinter the rare earth-doped ferrite powder at 1000 °C for 1 h, and then crush and screen the sintered product to obtain a pre-sintered material;

[0048] (3) Ultrasonic dispersion: Mix four kinds of powders of lrO 2 , MoO 2 , CNTs, and BNNT. Based on the pre-sintered material, the addition amounts of the four kinds of powders of lrO 2 , MoO 2 , CNTs, and BNNT are 3.0%, 3.0%, 3.0%, and 3.0% of the weight of the pre-sintered material, respectively. After mixing, add an ethanol solution, turn on the magnetic stirrer, and conduct preliminary stirring on the solution to make the above solution and ethanol preliminarily mixed. Then, conduct ultrasonic dispersion: Use an ultrasonic disperser to perform ultrasonic treatment on the solution to make it better dispersed in the ethanol solution, where the ultrasonic time is 30 min and the power is 120 W. After filtration, take the filter residue and wash it with deionized water multiple times until the pH value of the washing solution is about 7, and then dry it to obtain intermediate powder;

[0049] (4) Ball milling: Mix the intermediate powder and the pre-sintered material, and ball-mill at a rotation speed of 300 r / min for 5 h. Take it out, wash, filter by suction, and vacuum-dry to obtain uniformly mixed powder;

[0050] (5) Compression molding: Mix the powder obtained in (4) with the lubricant barium stearate evenly. The addition amount of barium stearate is 1.5 Wt%. Press it into an annular sample under a pressure of 15 T / cm 2 ;

[0051] (6) Secondary sintering: Adopt a power bell-jar furnace atmosphere sintering, with a sintering temperature of 1500 °C and a heat preservation time of 3 h to obtain Mn-Zn soft magnetic ferrite.

[0052] Example 4

[0053] A high-frequency, low-loss soft magnetic material, the preparation method of which is as follows:

[0054] (1) Ingredients: FeSO4, Na2Zn(OH)4, and MnSO4 are prepared in a molar ratio of 2:0.5:1, and then completely dissolved in deionized water to obtain a mixed salt solution. La(NO3)3 and Pr(NO3)3 are then prepared in a molar ratio of 1:1 to obtain a rare earth salt solution. The rare earth salt solution and the mixed salt solution are mixed and stirred at a volume ratio of 1:2. At this time, NH3·H2O with a volume twice that of the solution is added, and the reaction is stirred. The solution after the reaction is then filtered, and the residue is washed with deionized water for multiple times until the pH value of the washing solution reaches about 7, and then dried in a vacuum drying oven. The dried powder is calcined at 900°C for 250 minutes, and then acetone and polyglycol ether are used as grinding aids. The calcined solid is ball-milled at a speed of 300 r / min for 2 hours, and after being taken out, it is washed, filtered, and vacuum-dried to obtain a rare earth-doped ferrite powder;

[0055] (2) Primary sintering: sintering the rare earth-doped ferrite powder at 950°C for 2 h, and then crushing and sieving the sintered material to obtain a pre-sintered material;

[0056] (3) Ultrasonic dispersion: lrO 2 、MoO 2 , CNTs, BNNT four kinds of powders are mixed, based on the pre-sintered material, lrO 2 、MoO 2 The addition amounts of the four kinds of powders, CNTs and BNNT, are 3.0%, 3.0%, 3.0% and 3.0% of the weight of the pre-sintered material, respectively; after mixing, ethanol solution is added, and a magnetic stirrer is turned on to preliminarily stir the solution so that the above solution and ethanol are preliminarily mixed, followed by ultrasonic dispersion: an ultrasonic disperser is used to ultrasonically treat the solution so that it is better dispersed in the ethanol solution, wherein the ultrasonic time is 30 minutes and the power is 120W; after filtering, the filter residue is washed with deionized water for several times until the pH value of the washing solution reaches about 7, and then dried to obtain an intermediate powder;

[0057] (4) Ball milling: The intermediate powder is mixed with the pre-sintered material, and ball milled at a speed of 300 r / min for 5 h. After being taken out, it is washed, filtered and vacuum dried to obtain a uniformly mixed powder;

[0058] (5) Compression molding: The powder obtained in (4) was mixed evenly with the lubricant barium stearate, the addition amount of barium stearate was 1.5wt%, and the temperature was 15T / cm 2 Pressed into a ring-shaped sample under pressure;

[0059] (6) Secondary sintering: Using a power bell furnace for atmosphere sintering, the sintering temperature is 1340 °C, and the holding time is 5.5 h to obtain Mn-Zn soft magnetic ferrite.

[0060] Comparative example

[0061] Comparative example 1

[0062] A high-frequency low-loss soft magnetic material, the difference in its preparation method from that of Example 4 lies in: different raw material dosages, as shown in Table 1 specifically.

[0063] Comparative example 2

[0064] A high-frequency low-loss soft magnetic material, the difference in its preparation method from that of Example 4 lies in: different raw material dosages, as shown in Table 1 specifically.

[0065] Comparative example 3

[0066] A high-frequency low-loss soft magnetic material, the difference in its preparation method from that of Example 4 lies in: different raw material dosages, as shown in Table 1 specifically.

[0067] Comparative example 4

[0068] A high-frequency low-loss soft magnetic material, the difference in its preparation method from that of Example 4 lies in: different raw material dosages, as shown in Table 1 specifically.

[0069] Comparative example 5

[0070] A high-frequency low-loss soft magnetic material, the difference in its preparation method from that of Example 4 lies in: different raw material dosages, as shown in Table 1 specifically.

[0071] Comparative example 6

[0072] A high-frequency low-loss soft magnetic material, the difference in its preparation method from that of Example 4 lies in: different raw material dosages, as shown in Table 1 specifically.

[0073] Table 1 Dosage table of each raw material in the examples and comparative examples

[0074]

[0075] Performance detection test

[0076] The permeability, magnetic induction intensity, eddy current loss, and working frequency resistivity performance tests were respectively carried out on the above-mentioned examples and comparative examples. The test results are shown in Table 2:

[0077] Table 2 Magnetic property test of the examples and comparative examples

[0078]

[0079]

[0080] As can be seen from Table 2, adding lrO 2 , MoO 2 , CNTs, and BNNT is beneficial to increasing the magnetic induction intensity and resistivity, improving the eddy current loss of the material to a certain extent, and within a specified range, the more the added content, the more beneficial it is to improving the magnetic properties.

[0081] From the comparison between Example 4 and Comparative Examples 1-4, it can be seen that when adding lrO 2 , MoO 2 , CNTs, and BNNT these four additives simultaneously, the initial permeability, magnetic induction intensity, and resistivity of the material are all improved, while the eddy current loss decreases. This indicates that there is a significant synergistic effect among these four additives in improving the magnetic properties of Mn-Zn ferrite materials.

[0082] In Comparative Examples 1-4, when each additive is added alone or in combination, although the performance can also be improved to a certain extent, the effect is not as significant as when the four additives are added simultaneously. This further proves the importance of the synergistic effect of the four additives.

[0083] This specific embodiment is only an interpretation of the present application and does not limit the present application. Those skilled in the art can make modifications to this embodiment without creative contributions according to needs after reading this specification, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A method for preparing a high-frequency, low-loss soft magnetic material, characterized in that: The following steps are involved: (1) Mixing and dissolving an iron salt, a zincate and a manganese salt to obtain a mixed salt solution, then adding a rare earth salt solution, then adding a precipitant, stirring for reaction, then filtering the solution after the reaction, washing, drying, calcining and refining the filter residue to obtain a rare earth-doped ferrite powder; (2) sintering the rare earth-doped ferrite powder once, and then crushing and screening to obtain a pre-sintered material; (3) Mix the four powders of lrO2, MoO2, CNTs and BNNT, add ethanol, stir magnetically and then disperse ultrasonically, filter and wash, dry and refine the residue to obtain the intermediate powder; (4) The pre-sintered material, the intermediate powder and the lubricant are mixed evenly and then pressed to form a body, and then the body is subjected to secondary sintering to obtain a Mn-Zn soft ferrite; In step (1), the molar ratio of iron salt, zinc salt and manganese salt is (2-5): (0.2-1): 1; In step (1), the solute in the rare earth salt solution is La(NO3)3 and Pr(NO3)3 in a molar ratio of 1:(0.5-2); In step (1), the volume ratio of the rare earth salt solution to the mixed salt solution is 1:(1-3); In step (3), based on the pre-sintered material, the added amounts of the four powders of lrO2, MoO2, CNTs and BNNT are 0.5%-3% of the weight of the pre-sintered material respectively.

2. The method for preparing a high-frequency low-loss soft magnetic material according to claim 1, characterized in that: In step (2), the sintering temperature of the first sintering is 700-1000°C, and the sintering time is 1-3h.

3. The method for preparing a high-frequency low-loss soft magnetic material according to claim 1, characterized in that: In step (3), the power of ultrasonic dispersion is 120 W and the time is 30 min.

4. The method for preparing a high-frequency low-loss soft magnetic material according to claim 1, characterized in that: In step (4), the sintering temperature of the secondary sintering is 1300-1500°C, and the sintering time is 3-7h.

5. The method for preparing a high-frequency low-loss soft magnetic material according to claim 1, characterized in that: In step (4), the lubricant is barium stearate, and the amount of lubricant added is 0.1-1.5 wt% based on the pre-sintered material, and the pressing pressure is 10-20 T / cm 2 .

6. The method for preparing a high-frequency low-loss soft magnetic material according to claim 1, characterized in that: In step (1), the refinement treatment is as follows: using acetone and polyglycol ether as grinding aids, ball milling the calcined solid at a speed of 300 r / min for 2 hours, taking it out, washing, filtering and vacuum drying to obtain rare earth doped ferrite powder.

7. The method for preparing a high-frequency low-loss soft magnetic material according to claim 1, characterized in that: In step (1), the precipitant is NH3·H2O.

8. A high-frequency, low-loss soft magnetic material, characterized in that: The method is prepared by the preparation method according to any one of claims 1 to 7.

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