Wide-temperature low-loss manganese-zinc ferrite material, preparation method and application thereof

Abstract

The application relates to the technical field of manganese-zinc ferrite material, and provides a wide-temperature low-loss manganese-zinc ferrite material and a preparation method and application thereof.The main components of the manganese-zinc ferrite material are Fe2O3, ZnO and MnO, and the auxiliary components include Fe3O4@SiO2 magnetic nanoparticles, CaO, Co2O3, ZrO2, TiO2 and V2O5.The preparation method adopts a horizontal sand mill for sand grinding mixing, Fe3O4@SiO2 magnetic nanoparticles are prepared through hydrolysis of tetraethyl orthosilicate, and a heat preservation treatment process is reasonably set according to the Curie temperature of the material in the sintering cooling stage, so that the uniform growth of the crystal grains is effectively promoted, the grain boundary resistivity is improved, and the internal stress of the material is reduced, thereby realizing the reduction of the loss, and the prepared wide-temperature low-loss manganese-zinc ferrite material can be applied to a scene with a working frequency of 200-500 kHz.

Description

Technical Field

[0001] This invention belongs to the technical field of manganese-zinc ferrite materials, and particularly relates to a wide-temperature, low-loss manganese-zinc ferrite material, its preparation method, and its application. Background Technology

[0002] Currently, magnetic components are gradually developing towards miniaturization, low loss, and high power, mainly used in 5G communications, new energy vehicles, server power supplies, data centers, and other fields. With the development of third-generation semiconductors (SiC and GaN), the operating frequency is increasing, which can effectively reduce the size of magnetic components and increase power density. However, the operating frequency of currently used manganese-zinc ferrite materials is less than 300kHz. Increasing the operating frequency will lead to a significant increase in magnetic component losses, causing thermal design failure of the device. This necessitates the development of a wide-temperature, low-loss manganese-zinc ferrite material under mid-frequency (200-500kHz) conditions to adapt to the increased operating frequency of magnetic components.

[0003] One common method to reduce eddy current loss in manganese-zinc ferrite is to appropriately incorporate the high-resistivity compound SiO2. Controlling the SiO2 grain size and ensuring its uniform distribution is crucial. If the SiO2 grain size is too large, it can hinder grain boundary migration, which is also detrimental to ferrite grain uniformity. Patent CN118471643A provides a broadband ultra-low power loss manganese-zinc ferrite material for 5G base stations. This material exhibits good high-temperature losses at 200kHz, 125mT and 300kHz, 100mT, but the use of nano-SiO2 makes it prone to local agglomeration, leading to the formation of abnormally large grains and resulting in higher losses at room temperature. Patent CN120072452A discloses a manganese-zinc ferrite, its preparation method, and its uses. It employs tetraethyl orthosilicate hydrolysis to coat the surface of manganese-zinc ferrite with SiO2, obtaining a low-loss, high-frequency manganese-zinc ferrite material. However, SiO2 is at least coated on the main component, so a large amount of coating reagents are required, making it difficult and costly to achieve precise control.

[0004] Patent CN115650718A discloses a manganese-zinc ferrite material and its preparation method that combines ultra-wide temperature range, low power consumption, and stable magnetic permeability at temperature. Within an ultra-wide temperature range of 0℃-150℃, at 100kHz and 200mT and 200kHz and 100mT, the power consumption changes very little with temperature. However, the secondary milling time is 16-24 hours, which is too long and results in excessive power loss at room temperature. Patent CN112573912A provides a medium-wide frequency MnZn ferrite material with wide temperature range and low power loss, and its preparation method. The pre-sintered material undergoes secondary milling and sedimentation separation in a liquid medium to prepare the medium-wide frequency MnZn ferrite material with wide temperature range and low power loss. Its microstructure is dense and the grains are uniform. It exhibits low power loss within a wide temperature range of 0-140℃ and at operating frequencies of 100-500kHz. However, the process is complex and involves secondary milling followed by sedimentation separation. Summary of the Invention

[0005] In order to overcome the problems of high loss and complicated preparation process of manganese zinc ferrite materials under medium frequency (200-500kHz) conditions in the prior art, the present invention aims to provide a wide-temperature low-loss manganese zinc ferrite material, its preparation method and application.

[0006] This invention employs tetraethyl orthosilicate hydrolysis to coat Fe3O4 nanoparticles with a layer of SiO2, forming Fe3O4@SiO2 magnetic nanoparticles as an auxiliary component. The nano-Fe3O4, during sintering, lowers the sintering temperature, promotes densification, and refines the grain size. Furthermore, the coated SiO2 forms a uniform high-resistivity layer at the grain boundaries, preventing abnormal grain growth and reducing eddy current losses while also preventing an increase in hysteresis losses. This invention utilizes a horizontal sand mill with small-diameter steel balls for sand milling, eliminating the sedimentation and sorting step to obtain powder with a concentrated particle size distribution. In the sintering process, based on the Curie temperature characteristics of manganese-zinc ferrite materials, a heat preservation step is introduced during the cooling stage to reduce internal stress and Fe3O4 nanoparticle size distribution. 3+ / Fe 2+ By optimizing the proportions, manganese-zinc ferrite materials with lower losses can be obtained.

[0007] In a first aspect, the present invention provides a method for preparing a wide-temperature, low-loss manganese-zinc ferrite material, comprising the following steps:

[0008] S1. Ingredients and Mixing: Weigh the main components Fe2O3, ZnO and MnO according to the proportion, wherein the content of Fe2O3 is 52.0-54.5 mol%, the content of ZnO is 8.0-12.0 mol%, and the remainder is MnO. Wet mixing is carried out in a horizontal sand mill, and the sand mill slurry is dried in an oven to obtain mixed powder.

[0009] S2, Pre-calcination: The mixed powder obtained in S1 is pre-calcined and cooled in the furnace to obtain pre-calcined material;

[0010] S3. Doping: Weigh out the auxiliary components according to the proportion, based on 100wt% of the pre-calcined material obtained in S2, including 300-900ppm CaO, 2000-5000ppm Co2O3, 50-300ppm ZrO2, 500-3000ppm TiO2, 100-400ppm V2O5, and 50-500ppm Fe3O4@SiO2 magnetic nanoparticles. Mix them with the pre-calcined material obtained in S2 and then mix them in a horizontal sand mill to obtain the doped powder.

[0011] S4. Granulation and molding: Add glue to the doped powder obtained in S3, granulate and sieve to obtain manganese zinc ferrite powder, and then press to obtain green body.

[0012] S5. Sintering: The green blanks obtained in S4 are sintered in a bell-shaped furnace, including the following steps:

[0013] S51. Heating stage: The temperature is raised to 1000℃ in the air atmosphere at a first rate, and then raised to 1200~1300℃ at a lower second rate, while controlling the oxygen content to be below 0.1%; wherein the first rate is 1.0-3.0℃ / min, the second rate is 0.4-1.0℃ / min, and the second rate is less than the first rate;

[0014] S52, Insulation Stage: Insulate at 1200~1300℃ for 3-10 hours, controlling the oxygen content to 2.0-5.0%;

[0015] S53: Cooling stage: Cool to 900℃ at the third rate, controlling the oxygen content at 1.0-2.0%; then cool to room temperature at a higher fourth rate, maintaining oxygen partial pressure balance. When cooling to 150-250℃, hold for 0.5-3 hours, controlling the oxygen content at 1.0-21.0%. The third rate is 1.0-2.0℃ / min, and the fourth rate is 2.0-4.0℃ / min, with the fourth rate being greater than the third rate.

[0016] In step S1, preferably, the diameter of the steel balls used in the horizontal sand mill is 1-5mm, the ratio of powder:deionized water:steel balls during sand milling is 1:1:2, the rotation speed is 300-1500r / min, and the sand milling time is 0.2-1h.

[0017] In step S2, preferably, the pre-firing temperature is 750-1000℃, the holding time is 2-4h, and the pre-firing atmosphere is air;

[0018] In step S3, preferably, the Fe3O4@SiO2 magnetic nanoparticles are prepared through the following steps:

[0019] S31. Mix Fe3O4 nanoparticles, anhydrous ethanol, deionized water and ammonia water in a ratio of 0.5g:(50-100mL):(10-30mL):(2-5mL) and ultrasonically disperse for 10-30min.

[0020] S32. Slowly add 1-2 mL of tetraethyl orthosilicate and stir at room temperature for 3-12 h to obtain the reaction product;

[0021] S33. The reaction product obtained in S32 is washed by centrifugation 3-5 times with deionized water or anhydrous ethanol, and then dried in a vacuum drying oven.

[0022] In step S3, preferably, the diameter of the steel balls used in the horizontal sand mill is 1-5mm, the ratio of doped powder:deionized water:steel balls during sand milling is 1:1:2, the rotation speed is 300-1500r / min, the sand milling time is 0.5-2h, and the particle size D50 of the resulting doped powder is controlled to be 0.8-1.2μm.

[0023] In step S4, preferably, based on 100wt% of doped powder, the adhesive includes PVA solution, with an addition amount of 5-15wt%; the pressing pressure is 50-200kN; and the green shape is not limited, and can be T25, T12.7, or T12.5.

[0024] In S53, the holding temperature of 150-250℃ during the cooling stage is determined by the Curie temperature Tc of the manganese-zinc ferrite material obtained by sintering. This holding temperature is lower than the Curie temperature Tc. If the temperature is too high, a second phase will precipitate, which will destroy the uniformity of the crystal structure and lead to a deterioration in loss performance.

[0025] Secondly, the present invention provides a wide-temperature, low-loss manganese-zinc ferrite material, prepared by the preparation method of the wide-temperature, low-loss manganese-zinc ferrite material described in the first aspect, wherein the loss performance of the wide-temperature, low-loss manganese-zinc ferrite material is as follows:

[0026] Pcv≤202kW / m 3 (200kHz, 125mT, 100℃);

[0027] Pcv≤188kW / m 3 (300kHz, 100mT, 100℃);

[0028] Pcv≤619kW / m 3 (500kHz, 100mT, 100℃);

[0029] The wide-temperature, low-loss manganese-zinc ferrite material exhibits low loss at 200-500kHz and can be applied to magnetic components operating at frequencies of 200-500kHz.

[0030] Thirdly, the present invention provides an application of the wide-temperature, low-loss manganese-zinc ferrite material as described in the second aspect in magnetic components, with an operating frequency of 200-500kHz.

[0031] The technical solution of this invention utilizes a horizontal sand mill with small-diameter steel balls, resulting in a more concentrated particle size distribution after sand milling. This reduces gaps between large particles, promotes uniform grain growth, reduces the formation of abnormally large grains, and increases the number of grain boundaries. Grain boundaries, acting as high-resistivity layers, can block eddy current diameters; therefore, this method can increase resistivity and thus reduce eddy current losses.

[0032] On the other hand, introducing SiO2 at grain boundaries can form a high-resistivity calcium silicate layer with CaO, reducing eddy current loss. However, directly adding SiO2 powder results in uneven distribution, leading to localized high SiO2 content and abnormal grain growth in some areas. The widening of magnetic domains and the increased domain wall mobility barrier within these large grains increase hysteresis loss, particularly affecting low-temperature losses. This invention uses tetraethyl orthosilicate hydrolysis to coat Fe3O4 nanoparticles with a layer of SiO2, forming Fe3O4@SiO2 magnetic nanoparticles. During sintering, this forms a uniform high-resistivity layer while preventing abnormal grain growth and reducing abnormally large grains caused by nano-SiO2 aggregation. This improves eddy current loss at 200-500kHz conditions while minimizing the negative impact on room-temperature hysteresis loss.

[0033] Thirdly, during sintering, inconsistent internal and external temperatures lead to uneven shrinkage and a mismatch between the thermal expansion coefficients of impurities at grain boundaries and the matrix, resulting in localized stress within the manganese-zinc ferrite material. This stress hinders domain wall movement and increases hysteresis loss. This invention incorporates a heat preservation treatment during the cooling stage of sintering, setting the temperature below the Curie temperature Tc of the manganese-zinc ferrite material and precisely controlling the oxygen content during the heat preservation treatment. Excessively high temperatures can cause the precipitation of a second phase, disrupting the uniformity of the crystal structure and ultimately deteriorating loss performance; heat preservation at an appropriate temperature (150-250℃) can significantly reduce the accumulation of internal stress, decrease the energy required for domain wall movement, and thus reduce hysteresis loss. Furthermore, appropriate control of the oxygen content can reduce Fe... 2+ Small amount oxidized to Fe 3+ This can increase resistivity and reduce eddy current losses in materials.

[0034] This invention achieves a reduction in eddy current loss and hysteresis loss of manganese-zinc ferrite through the synergistic effect of the above three aspects: optimizing grain size through sand milling process, improving grain boundary resistance through main and auxiliary component regulation, and reducing stress influence through sintering process adjustment. The resulting wide-temperature low-loss manganese-zinc ferrite material has good loss characteristics in the range of 200-500kHz.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] 1. A layer of SiO2 is coated on the surface of Fe3O4 nanoparticles by hydrolysis of tetraethyl orthosilicate to form Fe3O4@SiO2 magnetic nanoparticles as an auxiliary component. During the sintering process, abnormally large grains formed by the aggregation of nano SiO2 are reduced, and eddy current loss and low-temperature hysteresis loss are improved under 200-500kHz conditions.

[0037] 2. A method for uniformly distributing the particle size of manganese-zinc ferrite powder by sand milling is provided. A horizontal sand mill is used in conjunction with small-diameter steel balls, which can effectively improve the uniformity of the powder particle size, reduce the formation of abnormally large grains, increase the number of grain boundaries, and reduce eddy current loss.

[0038] 3. During the cooling stage of the sintering process, an additional heat preservation treatment is added. The heat preservation temperature is set below the Curie temperature Tc, which can reduce the negative impact caused by local stress accumulation. At the same time, combined with oxygen content control, the resistivity of the material is improved, thereby reducing the loss of manganese-zinc ferrite material. Detailed Implementation

[0039] The technical solution of the present invention will be further illustrated below through specific implementation methods. The implementation examples are only some of the implementation examples of the present invention.

[0040] Example 1

[0041] This embodiment prepares a wide-temperature, low-loss manganese-zinc ferrite material for use in the 200-500kHz range using the following method:

[0042] S1. Ingredients and Mixing: The main formula Fe2O3:MnO:ZnO is weighed according to the molar ratio of 53.5:37.5:9.0, mixed evenly, and added to a horizontal sand mill for wet sand milling. The steel ball diameter is 1mm, the speed is 900r / min, and the sand milling time is 0.5h. After drying, the mixed powder is obtained. The ratio of mixed powder:deionized water:steel ball during sand milling is 1:1:2.

[0043] S2, Pre-firing: The mixed powder obtained in S1 is pre-firing in air at a temperature of 900℃ for 3 hours, and then cooled to room temperature in the furnace to obtain the pre-fired material;

[0044] S3. Doping: Weigh the auxiliary components as follows: CaO 400ppm, Co2O3 3500ppm, ZrO2 100ppm, TiO2 2000ppm, V2O5 200ppm, Fe3O4@SiO2 200ppm. Mix the pre-calcined material and the above auxiliary components in a horizontal sand mill for secondary sand milling at a speed of 900r / min for 0.5h. Then dry the slurry to obtain doped powder, wherein the ratio of doped powder:deionized water:steel balls is 1:1:2, and the diameter of the steel balls is 1mm.

[0045] The preparation of Fe3O4@SiO2 magnetic nanoparticles is as follows:

[0046] S31. Weigh 0.5g of Fe3O4 nanoparticles and add them to a three-necked flask. Add 60mL of anhydrous ethanol, 15mL of deionized water and 2mL of ammonia water, and sonicate for 15min.

[0047] S32. Slowly add 1 mL of tetraethyl orthosilicate and stir at room temperature for 4 hours.

[0048] S33. After the reaction is complete, the mixture is centrifuged and washed 5 times with deionized water, and then dried in a vacuum drying oven.

[0049] S4. Granulation and molding: Add 10wt% PVA solution to the doped powder obtained in S3, granulate and sieve to obtain manganese zinc ferrite powder, and press the manganese zinc ferrite powder into T25*15*7.5 rings with a pressing pressure of 80kN.

[0050] S5. Sintering: The green body obtained in S4 is pressed and sintered in a bell-shaped furnace, which mainly consists of three stages:

[0051] S51. Heating stage: Heat from room temperature to 400℃ at 1.0℃ / min, then heat to 1000℃ at 2.0℃ / min for sintering in air; then heat to 1200℃ at 0.5℃ / min for densification, controlling the oxygen content to be below 0.1%.

[0052] S52, Insulation Stage: Insulate at 1200℃ for 8 hours, with the oxygen content controlled at 2.0% during the insulation stage;

[0053] S53. Cooling stage: Cool from 1200℃ to 900℃ at a rate of 1.0℃ / min, controlling the oxygen content at 1.5%; then cool down to room temperature at a rate of 2.0℃ / min. During the cooling stage, the oxygen partial pressure is balanced. The cooling is further set as follows: when the temperature drops to 180℃, a heat preservation platform is set up, the heat preservation time is 2 hours, and the oxygen content is 1.0%.

[0054] Example 2

[0055] This embodiment prepares a wide-temperature, low-loss manganese-zinc ferrite material for use at 200-500kHz using the following method:

[0056] S1. Ingredients and Mixing: Main Formula Fe2O 3: MnO and ZnO were weighed according to a molar ratio of 52.5:37.5:10, mixed evenly, and added to a horizontal sand mill for wet sand milling. The steel ball diameter was 1 mm, the speed was 900 r / min, and the sand milling time was 0.5 h. After sand milling, the mixture was dried to obtain a mixed powder. The ratio of mixed powder:deionized water:steel ball during sand milling was 1:1:2.

[0057] S2, Pre-firing: The mixed powder obtained in S1 is pre-firing in air at a temperature of 900℃ for 3 hours, and then cooled to room temperature in the furnace to obtain the pre-fired material;

[0058] S3. Doping: Weigh the auxiliary components as follows: CaO 600ppm, Co2O3 4000ppm, ZrO2 150ppm, TiO2 1000ppm, V2O5 250ppm, Fe3O4@SiO2 150ppm. Add the auxiliary components to the pre-calcined material obtained in S2 and perform secondary sand milling in a horizontal sand mill. The steel ball diameter is 1mm, the rotation speed is 900r / min, and the sand milling time is 0.5h. Then dry the slurry to add the doping powder. During ball milling, the ratio of doping powder:deionized water:steel ball is 1:1:2.

[0059] The preparation of Fe3O4@SiO2 magnetic nanoparticles is as follows:

[0060] S31. Weigh 0.5g of Fe3O4 nanoparticles and add them to a three-necked flask. Add 80mL of anhydrous ethanol, 15mL of deionized water and 3mL of ammonia water, and sonicate for 20min.

[0061] S32. Slowly add 1.5 mL of tetraethyl orthosilicate and stir at room temperature for 6 hours;

[0062] S33. After the reaction is complete, the mixture is washed five times by centrifugation with anhydrous ethanol, and then dried in a vacuum drying oven.

[0063] S4. Granulation and molding: Add 10wt% PVA solution to the doped powder obtained in S3, granulate and sieve to obtain manganese zinc ferrite powder, and press the manganese zinc ferrite powder into T25*15*7.5 rings with a pressing pressure of 120kN.

[0064] S5. Sintering: The pressed green body is placed in a bell-shaped furnace for sintering, which mainly consists of three stages:

[0065] S51. Heating stage: Heat from room temperature to 400℃ at 1.0℃ / min, then heat to 1000℃ at 2.0℃ / min for sintering in air; then heat to 1240℃ at 0.5℃ / min for densification, controlling the oxygen content to be below 0.1%.

[0066] S52, Insulation Stage: Insulate at 1240℃ for 6 hours, with the oxygen content controlled at 3.0% during the insulation stage;

[0067] S53. Cooling stage: Cool from 1240℃ to 900℃ at a rate of 1.0℃ / min, controlling the oxygen content at 1.5%; then cool down to room temperature at a rate of 2.0℃ / min. During the cooling stage, the oxygen partial pressure is balanced. The cooling is further set as follows: when the temperature drops to 200℃, a heat preservation platform is set up, the heat preservation time is 1.0h, and the oxygen content is 8.0%.

[0068] Example 3

[0069] This embodiment prepares a wide-temperature, low-loss manganese-zinc ferrite material for use in the 200-500kHz range using the following method:

[0070] S1. Ingredients and Mixing: Main Formula Fe2O 3: MnO and ZnO were weighed according to a molar ratio of 54.0:35.0:11.0, mixed evenly, and added to a horizontal sand mill for wet sand milling. The steel ball diameter was 1 mm, the speed was 900 r / min, and the sand milling time was 0.5 h. After sand milling, the mixture was dried to obtain a mixed powder. The ratio of mixed powder:deionized water:steel ball during sand milling was 1:1:2.

[0071] S2, Pre-firing: The mixed powder obtained in S1 is pre-firing in air at a temperature of 900℃ for 3 hours, and then cooled to room temperature in the furnace to obtain the pre-fired material;

[0072] S3. Doping: The auxiliary components are weighed as follows: CaO 800ppm, Co2O3 4500ppm, ZrO2 150ppm, TiO2 500ppm, V2O5 200ppm, and Fe3O4@SiO2 100ppm. The pre-calcined material obtained in S2 is added with the auxiliary components and then subjected to secondary sand milling in a horizontal sand mill. The steel ball diameter is 1mm, the rotation speed is 900r / min, and the milling time is 0.5h. The slurry is then dried to obtain the doped powder. During sand milling, the ratio of doped powder:deionized water:steel balls is 1:1:2.

[0073] The preparation of Fe3O4@SiO2 magnetic nanoparticles is as follows:

[0074] S31. Weigh 0.5g of Fe3O4 nanoparticles and add them to a three-necked flask. Add 100mL of anhydrous ethanol, 20mL of deionized water, and 4mL of ammonia water. Disperse the mixture by sonication for 20min.

[0075] S32. Slowly add 2 mL of tetraethyl orthosilicate and stir at room temperature for 10 h.

[0076] S33. After the reaction is complete, the mixture is centrifuged and washed 5 times with deionized water, and then dried in a vacuum drying oven.

[0077] S4. Granulation and molding: Add 10wt% PVA solution to the doped powder obtained in S3, granulate and sieve to obtain manganese zinc ferrite powder, and press the manganese zinc ferrite powder into T25*15*7.5 rings with a pressing pressure of 80kN.

[0078] S5. Sintering: The pressed green body is placed in a bell-shaped furnace for sintering, which mainly consists of three stages:

[0079] S51. Heating stage: Heat from room temperature to 400℃ at 1.0℃ / min, then heat to 1000℃ at 2.0℃ / min for sintering in air; then heat to 1280℃ at 0.5℃ / min for densification, controlling the oxygen content to be below 0.1%.

[0080] S52, Insulation Stage: Insulate at 1280℃ for 5 hours, with the oxygen content controlled at 4.0% during the insulation stage;

[0081] S53. Cooling stage: Cool from 1280℃ to 900℃ at a rate of 1.0℃ / min, controlling the oxygen content at 1.5%; then cool down to room temperature at a rate of 2.0℃ / min. During the cooling stage, the oxygen partial pressure is balanced. The cooling is further set as follows: when the temperature drops to 220℃, a heat preservation platform is set up, the heat preservation time is 0.5h, and the oxygen content is 3.0%.

[0082] Example 4

[0083] This embodiment provides a wide-temperature, low-loss manganese-zinc ferrite material applicable under 200-500kHz conditions. The difference from Embodiment 1 is that the amount of Fe3O4@SiO2 magnetic nanoparticles added in S3 is 400ppm.

[0084] Example 5

[0085] This embodiment provides a wide-temperature, low-loss manganese-zinc ferrite material applicable under 200-500kHz conditions. The difference from Embodiment 1 is that the diameter of the steel balls in the horizontal sand mill in S1 and S3 is 5mm.

[0086] Example 6

[0087] This embodiment provides a wide-temperature, low-loss manganese-zinc ferrite material applicable under 200-500kHz conditions. The difference from Embodiment 1 is that the oxygen content during the heat preservation stage of S53 cooling is 21%.

[0088] Comparative Example 1

[0089] This embodiment provides a manganese-zinc ferrite material applicable under conditions of 200-500kHz. The difference from Embodiment 1 is that Fe3O4@SiO2 magnetic nanoparticles are not added as an auxiliary component in S3.

[0090] Comparative Example 2

[0091] This embodiment provides a manganese-zinc ferrite material applicable under conditions of 200-500kHz. The difference from Embodiment 1 is that Fe3O4@SiO2 magnetic nanoparticles are not added in S3, but Fe3O4 nanoparticles are added. The amount of Fe3O4 nanoparticles added is 130ppm based on the total mass of the pre-burned material.

[0092] Comparative Example 3

[0093] This embodiment provides a manganese-zinc ferrite material applicable under conditions of 200-500kHz. The difference from Embodiment 1 is that Fe3O4@SiO2 magnetic nanoparticles are not added in S3, but SiO2 particles (D50 is 6μm) are added, with an addition amount of 70ppm based on the total mass of the pre-sintered material.

[0094] Comparative Example 4

[0095] This embodiment provides a manganese-zinc ferrite material applicable under conditions of 200-500kHz. The difference from Embodiment 1 is that Fe3O4@SiO2 magnetic nanoparticles are not added in S3, but SiO2 nanoparticles (particle size of 20nm) are added, with an addition amount of 70ppm based on the total mass of the pre-burned material.

[0096] Comparative Example 5

[0097] This embodiment provides a manganese-zinc ferrite material applicable under conditions of 200-500kHz. The difference from Embodiment 1 is that the sand milling of S1 and S3 is carried out using a planetary ball mill with a rotation speed of 300r / min.

[0098] Comparative Example 6

[0099] This embodiment provides a manganese-zinc ferrite material applicable at 200-500kHz. The difference from Embodiment 1 is that no heat preservation treatment is introduced in the cooling stage of S53.

[0100] Comparative Example 7

[0101] This embodiment provides a manganese-zinc ferrite material applicable under conditions of 200-500kHz. The difference from Embodiment 1 is that the heat preservation time of the heat preservation treatment in the S53 cooling stage is extended to 5h.

[0102] The particle size of the doped powders obtained after milling in Examples 1-6 and Comparative Examples 1-7 was tested, and the power loss of the T25*15*7.5 rings obtained after sintering was tested. The results are shown in Table 1.

[0103] Table 1. Particle size of doped powder and power loss data of sintered magnetic cores obtained from sand milling in each test case.

[0104]

[0105] The test data in the table above shows that:

[0106] Examples 1-3 demonstrate that preparing Fe3O4@SiO2 magnetic nanoparticles by hydrolysis of tetraethyl orthosilicate, and introducing heat preservation treatment during the sintering cooling stage, significantly improves power loss at intermediate frequencies of 200-500kHz. Example 2 exhibits the best performance, with Pcv reduced to 160kW / m² under test conditions of 300kHz, 100mT, and 100℃. 3 .

[0107] A comparison of Examples 1 and 4 shows that adding a smaller amount of Fe3O4@SiO2 magnetic nanoparticles is more beneficial for reducing losses.

[0108] By comparing Examples 1 and 5 and Comparative Example 5, it can be seen that the horizontal sand mill using small steel balls with a diameter of 1 mm has a more uniform particle size distribution and the best wear performance.

[0109] By comparing Examples 1 and 6, and Comparative Examples 6 and 7, it can be seen that introducing insulation treatment during the cooling stage has a relatively small impact on loss optimization due to air atmosphere, and the effect is better with low oxygen concentration. Introducing insulation treatment can effectively reduce medium-frequency losses, especially at room temperature, but excessively long insulation times will lead to deterioration.

[0110] A comparison of Example 1 and Comparative Examples 1-4 shows that the smaller the particle size of SiO2 particles, the less loss occurs. Fe3O4 nanoparticles can also reduce loss, and the effect of adding Fe3O4@SiO2 magnetic nanoparticles is more obvious.

[0111] In summary, the Fe3O4@SiO2 magnetic nanoparticles prepared by adding tetraethyl orthosilicate hydrolysis avoid the formation of abnormally large grains during sintering, reducing high-temperature losses while also preventing excessively high losses at room temperature. Furthermore, using a horizontal sand mill with small-diameter steel balls improves the uniformity of the sand particle size, and setting up a heat-insulating platform during the cooling stage eliminates internal stress, both of which effectively reduce mid-frequency losses. Therefore, the wide-temperature, low-loss manganese-zinc ferrite material prepared by this method can be applied under mid-frequency (200-500kHz) conditions to adapt to the increased operating frequencies of magnetic components.

[0112] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a wide-temperature, low-loss manganese-zinc ferrite material, characterized in that, Includes the following steps: S1. Ingredients and Mixing: The main components are 52.0-54.5 mol% Fe2O3, 8.0-12.0 mol% ZnO, and the remainder is MnO. After weighing according to the proportion, they are mixed in a horizontal sand mill to obtain a mixed powder. S2, Pre-calcination: The mixed powder obtained in S1 is pre-calcined and cooled in the furnace to obtain pre-calcined material; S3, Doping: Add auxiliary components to the pre-calcined material obtained in S2. Based on the mass of the pre-calcined material, the auxiliary components include 50-500 ppm of Fe3O4@SiO2 magnetic nanoparticles. After weighing in proportion, they are mixed in a horizontal sand mill to obtain doped powder with D50 of 0.8-1.2 μm. The Fe3O4@SiO2 magnetic nanoparticles are prepared by hydrolysis of tetraethyl orthosilicate. S4. Granulation and molding: Add glue to the doped powder obtained in S3, granulate and sieve to obtain manganese zinc ferrite powder, and then press to obtain green body. S5. Sintering: The green body obtained in S4 is sintered, specifically by heating from room temperature to 1000℃ in an air atmosphere, then heating to 1200-1300℃ while controlling the oxygen content to be less than 0.1%; then adjusting the oxygen content to 2.0-5.0% and holding at that temperature; subsequently cooling to room temperature, where the temperature is held at 150-250℃ for 0.5-3 hours while controlling the oxygen content to be 1.0-21.0%.

2. The preparation method of the wide-temperature, low-loss manganese-zinc ferrite material as described in claim 1, characterized in that, In S1, the diameter of the steel balls used in the horizontal sand mill is 1-5mm, the ratio of mixed powder:deionized water:steel balls is 1:1:2, the rotation speed is 300-1500r / min, and the sand milling time is 0.2-1h.

3. The method for preparing the wide-temperature, low-loss manganese-zinc ferrite material as described in claim 1, characterized in that, In S2, the pre-firing temperature is 750-1000℃, the holding time is 2-4h, and the pre-firing atmosphere is air.

4. The method for preparing the wide-temperature, low-loss manganese-zinc ferrite material as described in claim 1, characterized in that, In S3, Fe3O4@SiO2 magnetic nanoparticles were prepared through the following steps: S31. Mix Fe3O4 nanoparticles, anhydrous ethanol, deionized water and ammonia water in a ratio of 0.5g:(50-100mL):(10-30mL):(2-5mL) and ultrasonically disperse for 10-30min. S32. Slowly add 1-2 mL of tetraethyl orthosilicate and stir at room temperature for 3-12 h to obtain the reaction product; S33. The reaction product obtained in S32 is washed by centrifugation 3-5 times with deionized water or anhydrous ethanol, and then dried in a vacuum drying oven.

5. The method for preparing the wide-temperature, low-loss manganese-zinc ferrite material as described in claim 1, characterized in that, In S3, based on the quality of the pre-burned material, the auxiliary components also include: 300-900ppm CaO, 2000-5000ppm Co2O3, 50-300ppm ZrO2, 500-3000ppm TiO2, and 100-400ppm V2O5.

6. The method for preparing the wide-temperature, low-loss manganese-zinc ferrite material as described in claim 1, characterized in that, In S3, the diameter of the steel balls used in the horizontal sand mill is 1-5mm, the ratio of mixed powder:deionized water:steel balls is 1:1:2, the rotation speed is 300-1500r / min, and the sand milling time is 0.5-2h.

7. The method for preparing the wide-temperature, low-loss manganese-zinc ferrite material as described in claim 1, characterized in that, In S4, the adhesive includes a PVA solution, with an amount of 5-15 wt% of the doped powder; the pressing pressure is 50-200 kN.

8. The method for preparing the wide-temperature, low-loss manganese-zinc ferrite material as described in claim 1, characterized in that, In S5, during heating, the temperature is first increased to 1000℃ at a first rate of 1.0-3.0℃ / min, then increased to 1200-1300℃ at a lower second rate of 0.4-1.0℃ / min, and then held for 3-10 hours. During cooling, the temperature is first decreased to 900℃ at a third rate of 1.0-2.0℃ / min while controlling the oxygen content at 1.0-2.0%, then the oxygen partial pressure is balanced and the temperature is decreased to room temperature at a higher fourth rate of 2.0-4.0℃ / min.

9. A wide-temperature, low-loss manganese-zinc ferrite material, characterized in that, It was prepared using the preparation method of wide-temperature, low-loss manganese-zinc ferrite material as described in any one of claims 1-8.

10. The application of the wide-temperature, low-loss manganese-zinc ferrite material as described in claim 9 in magnetic components, characterized in that... The operating frequency is 200-500kHz.

Images