DC-resistant superimposed MnZn ferrite materials, their preparation methods and applications

Abstract

This application discloses a DC-resistant MnZn ferrite material, its preparation method, and its application. The DC-resistant MnZn ferrite material comprises: a main material of MnZn ferrite; a first additive, calculated as oxides by weight percentage of the main material, including 0.3 wt% Co₂O₃, 0.05 wt% ZrO₂, 0.03 wt% V₂O₅, and 0.15 wt% CaO; and a second additive, calculated as oxides by weight percentage of the main material, including 0.1–0.5 wt% YIG ferrite particles. The preparation method is an oxide ceramic method, where the green body is sintered in stages by controlling the temperature and oxygen partial pressure. The MnZn ferrite material of this application, through cobalt doping, YIG ferrite composite, and adjustment of the sintering process, exhibits excellent morphology and combines high magnetic permeability with superior DC-resistant properties.

Description

Technical Field

[0001] This invention relates to the field of electronic materials technology, and in particular to DC-resistant superimposed MnZn ferrite materials, their preparation methods, and applications. Background Technology

[0002] MnZn power soft magnetic materials, as the heart of switching power supplies, inverters, and transformers, are a supporting backbone material for electronic information materials, widely used in automotive electronics, communications, home appliances, green lighting, new energy, electromagnetic interference suppression, and military power supplies. In recent years, with the development of electronic information technology, the high integration of electronic devices requires power supplies to maintain excellent performance in complex electromagnetic environments. Especially for military power supplies, good stability must be maintained under electromagnetic interference conditions to provide a continuous and reliable power supply to military equipment. This requires the MnZn ferrite core in power supply devices to have good resistance to DC superposition, enabling it to maintain stable performance even under DC superposition conditions.

[0003] When a DC bias current exists in a circuit, or when a device is in a complex electromagnetic environment, the MnZn ferrite core in an inductor or transformer will be in a near-saturation state. At this point, the permeability of the core material decreases, leading to a reduction in inductance and consequently affecting circuit stability and efficiency. Therefore, the impact of DC bias must be considered in the design of power supply devices to avoid drastic changes in the core's permeability. In engineering applications, to prevent a rapid drop in core permeability under DC bias, an air gap is typically added to the core. This prevents the core from quickly entering a saturation magnetization state under DC bias and mitigates the effect of the DC magnetic field on permeability. This method can improve the core's resistance to DC superposition to some extent, but the air gap reduces the core's inductance. To achieve a specific inductance value, the number of winding turns must be increased, leading to increased copper losses. Furthermore, leakage inductance is generated at the air gap, causing unnecessary electromagnetic interference. If the core material itself has strong resistance to DC superposition and can withstand large DC superposition while maintaining high permeability, then the design of the power supply device can be further optimized and its performance can be further improved.

[0004] Therefore, it is necessary to develop a magnetic ferrite material with resistance to DC superposition.

[0005] Furthermore, energy conservation and environmental protection are important themes in global development today. Existing technologies for preparing MnZn power ferrites involve high sintering temperatures, typically 1200–1400℃, resulting in significant energy consumption, which is detrimental to energy conservation and environmental protection. Therefore, it is necessary to improve the preparation methods of magnetic composite ferrite materials. Summary of the Invention

[0006] The purpose of this invention is to provide DC-resistant superimposed MnZn ferrite materials, their preparation methods, and applications, in order to solve the problems of unnecessary electromagnetic interference caused by leakage inductance in existing technologies, as well as the high sintering temperature and high energy consumption of existing technologies.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for preparing DC-resistant superimposed MnZn ferrite materials includes:

[0009] Based on molar percentage and calculated as oxides, 52.1–55.1 mol% Fe2O3, 34.9–39.9 mol% MnO, and 8.0–10.0 mol% ZnO were weighed and mixed to obtain the MnZn ferrite main material;

[0010] Based on weight percentages and calculated as oxides, 0.10–0.50 wt% Co2O3, 0.05 wt% ZrO2, 0.03 wt% V2O5, and 0.15 wt% CaO were weighed and mixed to obtain the first additive; 0.1–0.5 wt% YIG ferrite nanoparticles were weighed and used as the second additive.

[0011] After placing the MnZn ferrite main material into the ball mill, the grinding material is pre-fired, and the ball milling material obtained after one ball milling is dried.

[0012] After adding the first additive and the second additive, the material is ball-milled twice. An organic binder is added to the powder after the second ball milling and mixed evenly. The powder is then granulated and pressed into a green embryo. The green embryo is then sintered in segments to obtain a composite ferrite material.

[0013] Furthermore, the second additive is YIG ferrite nanoparticles; the YIG ferrite nanoparticles are Y 3-y Bi y Fe 5- x Al x O 12 , where 0≤x≤0.5, 0≤y≤0.2; the particle size of YIG ferrite particles is less than 100nm.

[0014] Furthermore, YIG ferrite nanoparticles can be prepared by a sol-gel method, comprising the following steps: dissolving Fe(NO3)3 and Y(NO3)3 in distilled water and stirring to obtain a mixed solution; adjusting the pH of the mixed solution with ammonia to maintain it at 6-7; adding ethylene glycol dropwise to the mixed solution and heating and stirring until the water evaporates to obtain a gel; continuously raising the temperature to allow the gel to spontaneously combust into powder; sintering the powder at 870-920℃ to obtain powder with a particle size of less than 100 nm.

[0015] Furthermore, the segmented sintering is carried out in a sintering furnace, including a first stage, a second stage, and a third stage. The first stage is the heating stage, which includes a first temperature zone, a second temperature zone, a third temperature zone, and a fourth temperature zone arranged sequentially. The first temperature zone is room temperature to 300°C, with a heating rate of 2°C / min and an air atmosphere. The second temperature zone is 300°C to 700°C, with a heating rate of 1°C / min and an air atmosphere. The third temperature zone is 700°C to 1150°C, with a heating rate of 1.5°C / min and an air atmosphere. The fourth temperature zone is 1150°C to 1250°C, with a heating rate of 2.5°C / min and an oxygen partial pressure of 0.005%.

[0016] Furthermore, the second stage is the heat preservation stage, which includes the fifth temperature zone, with a temperature of 1250℃~1250℃, maintained for 5h-8h, and an oxygen partial pressure of 1.9~2.7%.

[0017] Furthermore, the third stage is the cooling stage, which includes the sixth, seventh, and eighth temperature zones. The sixth temperature zone is 1250℃~1150℃, with a cooling rate of 2℃ / min and an oxygen partial pressure of 1.6%; the seventh temperature zone is 1150℃~700℃, with a cooling rate of 1.5℃ / min and an oxygen partial pressure of 0.8%; and the eighth temperature zone is below 700℃, with a cooling rate of 2℃ / min and an oxygen partial pressure of 0.005%.

[0018] Furthermore, during the first ball milling, deionized water at a weight of 1 to 1.5 times that of the MnZn ferrite main material is added, and the ball milling is carried out for more than 1.5 hours; the pre-firing conditions include pre-firing in an air atmosphere at 890℃ to 920℃, and holding the pre-firing at that temperature for 0.5 to 2 hours; the second ball milling includes adding the first additive, the second additive, 100 wt% deionized water, and 50 wt% ethanol, and then ball milling for 3.5 to 4 hours.

[0019] Furthermore, the molding process includes drying the slurry after secondary ball milling in a fume hood, adding PVA adhesive to granulate and sieve, selecting powder with a particle size of 100-200 mesh, and pressing it into shape at 60 MPa.

[0020] Secondly, the present invention provides a DC-resistant superimposed MnZn ferrite material, which is prepared by the aforementioned method for preparing DC-resistant superimposed MnZn ferrite material.

[0021] Thirdly, the present invention provides an application of DC-resistant superimposed MnZn ferrite material, which is used in electronic components.

[0022] Compared with the prior art, the present invention has the following technical effects:

[0023] This invention can adjust the Fe content in MnZn ferrite by controlling the oxygen partial pressure.2+ The content of ions, the mechanism is Fe 2+ It will be oxidized to Fe in an oxygen environment. 3+ The higher the oxygen content, the more Fe is oxidized. 2+ The more. And Fe 2+ It exhibits positive magnetocrystalline anisotropy, which can be achieved by adjusting Fe. 2+ The content of [specific component] can alter the overall magnetocrystalline anisotropy of the material, thereby achieving the purpose of regulating DC superposition characteristics. Furthermore, by controlling the sintering temperature and time in each temperature zone, the prepared DC superposition-resistant MnZn ferrite material exhibits good structural stability, with no cracking or breakage of the material particles. This prevents local structural collapse during operation in complex electromagnetic environments, meeting the development requirements for DC superposition resistance.

[0024] This invention provides a method for preparing DC-resistant superimposed MnZn ferrite. Based on a suitable main formulation, the method utilizes composite doping with various additives such as CaO, ZrO2, Co2O3, V2O5, and nano-YIG ferrite to control the microstructure and electromagnetic properties of the material. Specifically, the incorporation of high-resistivity oxides such as CaO and ZrO2 is beneficial for improving the resistivity of the material; the incorporation of V2O5 is beneficial for forming liquid-phase sintering, effectively promoting the solid-phase reaction during sintering and improving grain uniformity; the incorporation of Co... 2 + , using Co 2+ The positive magnetocrystalline anisotropy of MnZn ferrite was controlled to regulate the overall magnetocrystalline anisotropy of the MnZn ferrite. The addition of YIG ferrite nanoparticles enhanced long-range magnetic interactions between grains, effectively preventing a decrease in permeability. Finally, the MnZn power ferrite prepared through the composite addition of various additives and by controlling the sintering process with controlled temperature and oxygen partial pressure exhibited uniform grain size distribution, high permeability, and excellent resistance to DC superposition. By improving the material's inherent electromagnetic properties and its resistance to DC superposition, the permeability of the core remained constant under a given DC magnetic field.

[0025] The present invention provides a DC-resistant MnZn ferrite where Co ions can modulate the magnetocrystalline anisotropy of the MnZn ferrite, thereby adjusting the trend of its permeability change with a DC magnetic field. To control the degradation of other electromagnetic properties of MnZn ferrite caused by excessive Co doping, such as decreased permeability, reduced resistivity, and increased magnetic loss, a YIG ferrite phase is introduced. Since YIG particles are a magnetic phase, their distribution between the grains of MnZn ferrite promotes long-range magnetic interactions, effectively preventing a decrease in permeability. This allows the material to maintain high permeability under DC superposition conditions, exhibiting excellent DC superposition resistance.

[0026] This invention relates to the application of DC superposition resistant MnZn ferrite in the fabrication of electronic materials. Based on this application, the DC superposition resistant MnZn ferrite utilizes Co doping to adjust its DC superposition characteristics by introducing a YIG garnet phase. Since YIG nanoparticles are a magnetic phase, they possess high DC superposition resistance while maintaining magnetic permeability. Therefore, applying this DC superposition resistant MnZn ferrite to electronic materials enhances the DC superposition resistance of the MnZn ferrite material itself. When the magnetic core itself has strong DC superposition resistance, the magnetic core does not require an air gap. In this case, the magnetic core has a complete circuit, avoiding the influence of leakage inductance caused by the air gap, thus showing great application prospects in the fabrication of electronic devices.

[0027] The sixth temperature zone of this invention is the initial cooling stage, where a slightly faster cooling rate can reduce sintering time. The seventh temperature zone slows down the cooling rate to prevent sample cracking and deformation during cooling. By the eighth temperature zone, the temperature has dropped to 700℃, at which point temperature changes have virtually no impact on the sample's shape. Further increasing the cooling rate can further shorten the sintering time. Throughout the cooling process, the oxygen partial pressure gradually decreases, preventing the sample from being oxidized. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a graph showing the change in permeability of MnZn under DC superposition magnetic field in Embodiment 1 of this application.

[0030] Figure 2 This is a graph showing the change in permeability of MnZn under DC superposition magnetic field in Embodiment 2 of this application.

[0031] Figure 3 This is a graph showing the change in permeability of MnZn under DC superposition magnetic field in Embodiment 3 of this application.

[0032] Figure 4 This is a graph showing the change of magnetic permeability with DC magnetic field provided in Comparative Example 1 of this application;

[0033] Figure 5 This is a graph showing the change of magnetic permeability with a DC magnetic field, provided in Comparative Example 2 of this application. Detailed Implementation

[0034] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0035] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0036] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items.

[0037] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0038] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0039] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass described in the embodiments of this application can be a mass unit known in the chemical industry, such as μg, mg, g, or kg.

[0040] The terms "first" and "second" are used for descriptive purposes only to distinguish the target substances from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. For example, without departing from the scope of the embodiments of this application, "first XX" may also be referred to as "second XX," and similarly, "second XX" may also be referred to as "first XX." Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0041] Soft magnetic ferrites, as the name suggests, are magnetic materials characterized by their magnetic conductivity. Just as metals conduct electricity, some materials are magnetic; these are called magnetic materials. Magnetic materials are divided into hard magnetic and soft magnetic materials. Hard magnetic materials are permanent magnets, meaning they possess magnetism without the need for an external current-carrying solenoid, and their magnetism does not disappear. Soft magnetic materials, on the other hand, are not inherently magnetic; they only generate a magnetic field when an external current-carrying solenoid is applied, and this magnetic field disappears when the applied current is removed.

[0042] Ferrites are "functional ceramic materials" made by sintering a mixture of iron oxides and other metal oxides. They possess good magnetic permeability and, compared to ordinary metals, have advantages such as weaker coercivity and lower remanence after the removal of external current. Generally, based on their formulations, they are classified into four types: manganese-zinc ferrites, nickel-zinc ferrites, lithium-zinc ferrites, and magnesium-zinc ferrites.

[0043] This application provides a DC-resistant stacked MnZn ferrite material to better adjust the magnetocrystalline anisotropy of MnZn ferrite materials and thus improve their DC resistance. The DC-resistant stacked MnZn ferrite material of this application improves the magnetocrystalline anisotropy of the material through cobalt doping. Simultaneously, to overcome the decrease in permeability and deterioration of electromagnetic performance caused by large-scale cobalt doping, the DC resistance is improved by compositing MnZn ferrite with YIG ferrite particles, thus ensuring permeability. This application also controls the sintering temperature, oxygen partial pressure, and time in each temperature zone during the sintering process, resulting in a DC-resistant stacked MnZn ferrite material with good structural stability, no cracking or breakage of the material particles, and the ability to prevent local structural collapse under complex electromagnetic environments, thus meeting the development requirements for DC resistance stacking.

[0044] According to a certain aspect of this application, a method for preparing a DC-resistant superimposed MnZn ferrite material is provided, such as... Figure 1 As shown, the preparation method includes the following steps:

[0045] S01: Prepare the MnZn ferrite main material, calculated by molar percentage as oxides, including 52.1–55.1 mol% Fe2O3, 34.9–39.9 mol% MnO, and 8–10 mol% ZnO, and weigh the calculated content; prepare the first additive, calculated by weight percentage as oxides, including 0.10–0.50 wt% Co2O3, 0.05 wt% ZrO2, 0.03 wt% V2O5, and 0.15 wt% CaO; perform a first ball milling, placing the MnZn ferrite main material into the ball mill as grinding media;

[0046] S02: Provide the second additive YIG ferrite particles, comprising 0.1-0.5 wt% nano-YIG particles by weight percentage, wherein the main component of the YIG ferrite particles is Y 3-y Bi y Fe 5-x Al x O 12 Where 0 ≤ x ≤ 0.5, and / or 0 ≤ y ≤ 0.2, optionally, the value of x is 0.16 to 0.20. Additionally, the preparation method of the second additive includes: dissolving Fe(NO3)3 and Y(NO3)3 in distilled water and stirring to obtain a mixed solution; adjusting the pH of the mixed solution using ammonia to maintain it at 6-7; adding ethylene glycol dropwise to the mixed solution and heating and stirring until the water evaporates to obtain a gel; continuously raising the temperature to allow the gel to spontaneously combust into powder; sintering the powder at 870-920℃ to obtain powder with a particle size less than 100 nm.

[0047] S03: Dry the ball milling material obtained after the first ball milling; add the first additive and the second additive and then ball mill a second time;

[0048] S04: PVA organic binder is added to the powder after secondary ball milling and mixed evenly. After granulation, it is pressed into a green embryo. The green embryo is sintered in stages under controlled temperature and oxygen partial pressure conditions. The staged sintering is carried out in a sintering furnace and includes a first stage, a second stage and a third stage, wherein the first stage is a heating stage, the second stage is a heat preservation stage, and the third stage is a cooling stage.

[0049] S05: The DC-resistant superimposed MnZn ferrite magnetic ring prepared in this application was tested using a PLR36-20 DC power supply and an IWATSU SY-8232B-H analyzer. Three sets of coils, each with 5 turns, were wound around the magnetic ring. One set of coils was connected to the DC power supply to provide a DC magnetic field along the magnetic circuit of the magnetic ring. The magnetic field strength was calculated using H = NI / le, where N is the number of turns, I is the current, and le is the effective length of the magnetic ring. The remaining two sets of coils were connected to a BH analyzer to test the permeability. The permeability test conditions were 1 kHz, 1 A / m, and 25 °C.

[0050] The second aspect of this application provides a DC-resistant superimposed MnZn ferrite material, comprising:

[0051] The main material is MnZn ferrite, which, by molar percentage and calculated as oxides, comprises 52.1–55.1 mol% Fe₂O₃, 34.9–39.9 mol% MnO, and 8–10 mol% ZnO; the first additive, by weight percentage and calculated as oxides, comprises 0.10–0.50 wt% Co₂O₃, 0.05 wt% ZrO₂, 0.03 wt% V₂O₅, and 0.15 wt% CaO; the second additive is YIG ferrite particles, comprising 0.1–0.5 wt% YIG ferrite particles by weight percentage.

[0052] The following description is based on specific embodiments. It should be noted that because this application involves a large number of experiments, to better illustrate the main points of this application, the embodiments use fixed proportions of the main material and the first and second additives. However, the proportions of the main material and the first and second additives mentioned in the claims of this application all achieve the desired effect and are within the scope of protection of this application. Specific embodiments and comparative examples are as follows.

[0053] Example

[0054]

[0055] Comparative Example

[0056]

[0057] Example 1

[0058] The preparation steps for MnZn ferrite are as follows:

[0059] (1) Prepare the main MnZn ferrite material, and weigh it according to the molar percentage, calculated as oxides, including 54.1 mol% Fe2O3, 35.9 mol% MnO, and 10 mol% ZnO;

[0060] (2) The first additive is prepared, which, by weight percentage and calculated as oxides, includes 0.10 wt% Co2O3, 0.05 wt% ZrO2, 0.03 wt% V2O5, and 0.15 wt% CaO;

[0061] (3) A second additive is prepared, which is YIG ferrite particles. The preparation method is as follows: 15.00g Fe(NO3)3 and 10.23g Y(NO3)3 are dissolved in distilled water and stirred to obtain a mixed solution; the pH value of the mixed solution C is adjusted with ammonia water to maintain it at 6-7; ethylene glycol is added dropwise to the mixed solution and heated and stirred until the water evaporates to obtain a gel; the temperature is continuously increased to allow the gel to spontaneously combust into powder; the powder is sintered at 870-920℃ to obtain powder with a particle size of less than 100nm. 0.1wt% nano-YIG particles are provided by weight percentage.

[0062] (4) Place the MnZn ferrite main material into a ball mill, add an equal mass of deionized water, and grind the material once. After drying the ball milling material obtained after the first ball milling, add the first additive and the second additive and then ball mill a second time. Add organic binder PVA glue to the powder after the second ball milling and mix evenly. After granulation, press it into a green embryo.

[0063] (5) The green embryo is sintered under controlled temperature and oxygen partial pressure conditions. Specifically, the segmented sintering is carried out in a sintering furnace, including a first stage, a second stage, and a third stage. The first stage is a heating stage, which includes a first temperature zone, a second temperature zone, a third temperature zone, and a fourth temperature zone arranged sequentially. The first temperature zone is room temperature to 300°C, with a heating rate of 2°C / min and an air atmosphere. The second temperature zone is 300°C to 700°C, with a heating rate of 1°C / min and an air atmosphere. The third temperature zone is 700°C to 1150°C, with a heating rate of 1.5°C / min and an air atmosphere. The fourth temperature zone is 1150°C to 1250°C, with a heating rate of 2.5°C / min. The first stage is a cooling stage, which includes a fifth temperature zone (1250℃~1250℃) held for 6 hours with an oxygen partial pressure of 1.9%. The second stage is a cooling stage, which includes a sixth, seventh, and eighth temperature zone. The sixth temperature zone is 1250℃~1150℃ with a cooling rate of 2℃ / min and an oxygen partial pressure of 1.6%. The seventh temperature zone is 1150℃~700℃ with a cooling rate of 1.5℃ / min and an oxygen partial pressure of 0.8%. The eighth temperature zone is below 700℃ with a cooling rate of 2℃ / min and an oxygen partial pressure of 0.005%.

[0064] After the segmented sintering is completed, a DC-resistant superimposed MnZn ferrite material is obtained.

[0065] The above-mentioned DC-resistant superimposed MnZn ferrite material was tested:

[0066] The DC-resistant superimposed MnZn ferrite magnetic ring obtained in the above steps was tested using a PLR36-20 DC power supply and an IWATSU SY-8232B-H analyzer. Three sets of coils, each with 5 turns, were wound around the magnetic ring. One set of coils was connected to the DC power supply to provide a DC magnetic field along the magnetic circuit of the magnetic ring. The magnetic field strength can be determined using H = NI / l. e Where N is the number of coil turns, I is the current, and l e This represents the effective length of the magnetic ring. Repeat the test multiple times. Figure 1 The diagram shows the change in magnetic permeability of the DC-resistant MnZn ferrite material obtained in Example 1 as a function of a DC magnetic field. The horizontal axis represents H. dc (A / m), with the vertical axis representing permeability. Where H... μmax H represents the DC magnetic field corresponding to the point where the permeability reaches its maximum value. μ100 H represents the DC magnetic field corresponding to the point where the permeability decreases to 100% of the initial permeability. μ70 This represents the DC magnetic field corresponding to the point where the permeability decreases to 70% of the initial permeability.

[0067] Figure 1 The figure shows the variation of the magnetic permeability of the magnetic ring in Example 1 with a DC magnetic field. The initial magnetic permeability of this magnetic ring is 1530 H. μmax 145 A / m, H μ100 223 A / m, H μ70 It is 277 A / m.

[0068] Example 2

[0069] The preparation steps of MnZn ferrite are basically the same as those in Example 1, except that in step (5), during the sintering of the green embryo under controlled temperature and oxygen partial pressure conditions, the oxygen partial pressure is controlled to be 2.3% during the heat preservation stage.

[0070] Figure 2 The figure shows the variation of the permeability of the magnetic ring made of DC-resistant superimposed MnZn ferrite material obtained in Example 2 with a DC magnetic field. The initial permeability of this magnetic ring is 1586 H. μmax 132A / m, H μ100 231A / m, H μ70 It is 270A / m.

[0071] Example 3

[0072] The preparation steps of MnZn ferrite are basically the same as those in Example 1, except that the oxygen partial pressure is 2.7% during the heat preservation stage in step (5) when the temperature and oxygen partial pressure are controlled to sinter the green embryo.

[0073] Figure 3The figure shows the variation of the permeability of the magnetic ring made of DC-resistant superimposed MnZn ferrite material obtained in Example 2 with a DC magnetic field. The initial permeability of this magnetic ring is 1691 H. μmax 126 A / m, H μ100 208A / m, H μ70 It is 262A / m.

[0074] Comparative Example 1

[0075] A MnZn ferrite is prepared in a manner that is basically the same as in Example 1, except that in step (1), when the main material of the MnZn ferrite is prepared, the composition of the main material is 53.7 mol% Fe2O3, 35.3 mol% MnO, and 11 mol% ZnO. In step (5), during the sintering of the green embryo under controlled temperature and oxygen partial pressure conditions, the oxygen partial pressure is 1.6% during the heat preservation stage.

[0076] Figure 4 The figure shows the variation of the permeability of the magnetic ring made of DC-resistant superimposed MnZn ferrite material obtained in Example 2 with a DC magnetic field. The initial permeability of this magnetic ring is 1413 H. μmax 148A / m, H μ100 216 A / m, H μ70 It is 262A / m.

[0077] Comparative Example 2

[0078] A MnZn ferrite was prepared in a manner that was basically the same as in Example 1. The difference was that when the main material of the MnZn ferrite was prepared in step (1), the composition of the main material was 53.5 mol% Fe2O3, 35.5 mol% MnO, and 11 mol% ZnO. In step (5), during the sintering of the green embryo under controlled temperature and oxygen partial pressure conditions, the oxygen partial pressure was 3.1% during the heat preservation stage.

[0079] Figure 5 The figure shows the variation of the permeability of the magnetic ring made of DC-resistant superimposed MnZn ferrite material obtained in Example 2 with a DC magnetic field. The initial permeability of this magnetic ring is 1720 H. μmax 101A / m, H μ100 179A / m, H μ70 It is 247 A / m.

[0080] As can be seen from the above data, during the preparation of MnZn ferrite based on the embodiments of this application, controlling the oxygen partial pressure during the heat preservation stage to be between 1.9 and 2.7% has the best effect on improving the magnetic ring's resistance to DC superposition.

[0081] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing DC-resistant superimposed MnZn ferrite materials, characterized in that, include: Based on molar percentage and calculated as oxides, 52.1~55.1 mol% Fe2O3, 34.9~39.9 mol% MnO, and 8.0~10.0 mol% ZnO were weighed and mixed to obtain the MnZn ferrite main material; Based on weight percentages and calculated as oxides, 0.10~0.50wt% Co2O3, 0.05wt% ZrO2, 0.03wt% V2O5, and 0.15wt% CaO were weighed and mixed to obtain the first additive; 0.1~0.5wt% YIG ferrite nanoparticles were weighed and used as the second additive. After placing the MnZn ferrite main material into the ball mill, the grinding material is pre-fired, and the ball milling material obtained after one ball milling is dried. After adding the first additive and the second additive, the mixture is ball-milled twice. An organic binder is added to the powder after the second ball milling and mixed evenly. The mixture is then granulated and pressed into a green embryo. The green embryo is then sintered in segments to obtain a composite ferrite material. The second additive is YIG ferrite nanoparticles; the YIG ferrite nanoparticles are Y 3-y Bi y Fe 5-x Al x O 12 , where 0≤ x ≤0.5, 0≤ y ≤0.2; the particle size of YIG ferrite particles is less than 100 nm; Segmented sintering is carried out in a sintering furnace, including a first stage, a second stage, and a third stage. The first stage is the heating stage, which includes a first temperature zone, a second temperature zone, a third temperature zone, and a fourth temperature zone set sequentially. The first temperature zone is room temperature to 300℃, with a heating rate of 2℃ / min and an air atmosphere. The second temperature zone is 300℃ to 700℃, with a heating rate of 1℃ / min and an air atmosphere. The third temperature zone is 700℃ to 1150℃, with a heating rate of 1.5℃ / min and an air atmosphere. The fourth temperature zone is 1150℃ to 1250℃, with a heating rate of 2.5℃ / min and an oxygen partial pressure of 0.005%. The second stage is the heat preservation stage, which includes the fifth temperature zone, with a temperature of 1250℃~1250℃, maintained for 5 h - 8 h, and an oxygen partial pressure of 1.9~2.7%. The third stage is the cooling stage, which includes the sixth, seventh, and eighth temperature zones. The sixth temperature zone is 1250℃~1150℃, with a cooling rate of 2℃ / min and an oxygen partial pressure of 1.6%; the seventh temperature zone is 1150℃~700℃, with a cooling rate of 1.5℃ / min and an oxygen partial pressure of 0.8%; and the eighth temperature zone is below 700℃, with a cooling rate of 2℃ / min and an oxygen partial pressure of 0.005%.

2. The method for preparing DC-resistant superimposed MnZn ferrite material according to claim 1, characterized in that, YIG ferrite nanoparticles were prepared by a sol-gel method, comprising the following steps: dissolving Fe(NO3)3 and Y(NO3)3 in distilled water and stirring to obtain a mixed solution; adjusting the pH of the mixed solution with ammonia to maintain it at 6-7; adding ethylene glycol dropwise to the mixed solution and heating and stirring until the water evaporates to obtain a gel; continuously increasing the temperature to allow the gel to spontaneously combust into powder; sintering the powder at 870-920℃ to obtain powder with a particle size of less than 100 nm.

3. The method for preparing DC-resistant superimposed MnZn ferrite material according to claim 1, characterized in that, In the first ball milling, deionized water with a weight of 1 to 1.5 times that of the MnZn ferrite main material is added, and the ball milling is carried out for more than 1.5 hours. The pre-calcination conditions include pre-calcination in an air atmosphere at 890℃ to 920℃ for 0.5 to 2 hours. The second ball milling includes adding the first additive, the second additive, 100 wt% deionized water, and 50 wt% ethanol, and then ball milling for 3.5 to 4 hours.

4. The method for preparing DC-resistant superimposed MnZn ferrite material according to claim 3, characterized in that, The molding process involves drying the slurry after secondary ball milling in a fume hood, adding PVA adhesive to granulate and sieve it, selecting powder with a particle size of 100-200 mesh, and pressing it into shape at 60 MPa.

5. A DC-resistant superimposed MnZn ferrite material, characterized in that, The material was prepared by the method for preparing DC-resistant superimposed MnZn ferrite material as described in any one of claims 1 to 4.

6. An application of the DC-resistant superimposed MnZn ferrite material as described in claim 5, characterized in that, DC-resistant MnZn ferrite materials are used in electronic components.

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