High resistivity wide temperature low loss mnzn ferrite and preparation method and application thereof

Abstract

The application relates to a preparation method and application of a high-resistivity wide-temperature low-loss MnZn ferrite. The MnZn ferrite material is composed of main material and auxiliary material, wherein the main material comprises 52.8-53.8 mol% of Fe2O3 and 37.2-38.2 mol% of MnO, and the balance is ZnO; the first auxiliary material comprises 0.2-0.4 wt% of CaCO3 based on the weight of the main material, 0.03-0.06 wt% of ZrO2 based on the weight of the main material, 0.05-0.07 wt% of HfO2 based on the weight of the main material and 0.1-0.3 wt% of TiO2 based on the weight of the main material; the second auxiliary material comprises 0.04-0.07 wt% of Bi2O3 based on the weight of the main material. The preparation method is an oxide ceramic method, a segmented multi-step heat preservation method is adopted in the sintering stage, and the prepared MnZn ferrite has the characteristics of uniform crystal grains, few pores, high resistivity and low loss in a wide temperature range (25-120 DEG C).

Description

Technical Field

[0001] This invention relates to the field of electronic materials technology, and in particular to high resistivity, wide temperature range, and low loss MnZn ferrite, its preparation method, and its application. Background Technology

[0002] High-efficiency power supply devices, such as AC-DC and DC-DC converters and switching power supplies, are fundamental electronic components in the modern electronics and information industry. Particularly in new energy vehicles, DC-DC converters convert high battery voltage to low voltage to power the vehicle's electronic equipment, and also convert high battery voltage to phase voltage to drive the motor and propel the vehicle. In power supply devices, transformer cores made of MnZn power ferrite material are crucial for power transmission and conversion, but also significantly contribute to the device's size, weight, and losses. In particular, core losses reduce the efficiency of the power supply device, and in severe cases, can cause electronic components to overheat or even burn out.

[0003] As power supply devices become increasingly integrated, electronic devices inevitably generate energy losses and dissipate heat during operation. This causes the operating temperature of the magnetic core to typically exceed room temperature. The increased temperature also leads to a sharp decrease in the resistivity of the magnetic core, resulting in a dramatic increase in eddy current losses. Under low-frequency conditions, such as 100kHz at 200mT, the losses in MnZn ferrite consist of hysteresis losses and eddy current losses. Hysteresis losses are related to the irreversible magnetization process, while eddy current losses are related to the eddy currents generated within the material under an alternating magnetic field. Generally, with increasing temperature, hysteresis losses initially decrease and then increase, depending on the change in the magnetocrystalline anisotropy constant with temperature; eddy current losses, on the other hand, show a monotonically increasing trend, determined by the semiconductor properties of MnZn ferrite. At high temperatures, the sharp decrease in material resistivity causes a dramatic increase in eddy current losses, which in turn leads to a sharp increase in core losses, severely impacting the efficiency and stability of the power supply device. Therefore, there is an urgent need to develop a MnZn ferrite material with high resistivity and low loss over a wide temperature range to meet the requirements of power devices to continue to operate normally in increasingly harsh temperature environments. Summary of the Invention

[0004] The purpose of this invention is to provide high resistivity, wide temperature range, and low loss MnZn ferrite, as well as its preparation method and application, to solve the problem that at high temperatures, the material resistivity decreases sharply, causing a sharp increase in eddy current loss, which in turn leads to a sharp increase in core loss, seriously affecting the efficiency and stability of power supply devices.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a method for preparing high resistivity, wide temperature range, and low loss MnZn ferrite, comprising:

[0007] The main material is obtained by mixing 52.8–53.8 mol% Fe₂O₃ and 37.2–38.2 mol% MnO, with the balance being ZnO; the first auxiliary material is obtained by mixing 0.2–0.4 wt% CaCO₃, 0.03–0.06 wt% ZrO₂, 0.05–0.07 wt% HfO₂, and 0.1–0.3 wt% TiO₂; the second auxiliary material is obtained by mixing 0.04–0.07 wt% Bi₂O₃.

[0008] The main material is put into a ball mill for one ball milling and mixing, and then pre-calcined to obtain pre-calcined powder.

[0009] The pre-calcined powder is crushed, and the first and second auxiliary materials are added to the sieved powder and then ball-milled a second time.

[0010] The powder after secondary ball milling is mixed with adhesive and granulated. The granulated particles are placed in a mold and pressed into a ring-shaped green body. The ring-shaped green body is sintered to obtain ferrite.

[0011] Furthermore, during the first ball milling, the milling time is 2-4 hours, the milling media is Φ3mm zirconium balls, the milling speed is 241 rpm, and the mixed slurry is placed in an oven to dry for 24 hours. After drying, it is passed through a 40-mesh sieve.

[0012] Furthermore, before pre-firing, the powder is compacted with a pressure of 10 kg.

[0013] Furthermore, the pre-calcination process is as follows: the sieved powder is placed in a bell-shaped furnace and heated to 2... o C / min~3 o The heating rate increased from room temperature to 900 °C / min. o C, at 900 o Keep warm at 1.5-3 hours under temperature, then at 2 o C / min~3 o The cooling rate is reduced from 900 °C / min. o C drops to room temperature.

[0014] Furthermore, during the secondary ball milling, the milling time is 3-5 hours, the milling medium is Φ2.5mm bearing steel, and the milling speed is 289 rpm. The slurry after the secondary ball milling is placed in an oven to dry for 24 hours.

[0015] Furthermore, during granulation, 10.5–14.5 wt% PVA adhesive is added to the sieved powder, and the powder and adhesive are mixed and granulated. After granulation, the mixture is passed through 40-mesh and 160-mesh sieves, and particles with a size between 40-mesh and 160-mesh are collected. The PVA adhesive is prepared by mixing 117 adhesive and 217 adhesive at a mass ratio of 1:2, and slowly pouring the mixture into 100... o It is prepared by boiling in boiling water for 2 hours.

[0016] Furthermore, during forming, the ring-shaped green body is pressed into a ring shape under a pressure of 5.5 MPa to 8.5 MPa; during sintering, the ring-shaped green body is placed in an atmosphere-type tube furnace and sintered at 1280 °C according to the sintering curve. o C~1320 o C is used for sintering, with an oxygen partial pressure of 2.0%~3.2%.

[0017] Furthermore, the sintering process employs a segmented, multi-step heat preservation method. The specific sintering curve is as follows: Stage 1: Temperature from 50°C... o C rises to 200 o C, heating rate is 2.5 o C / min, air is introduced; temperature from 200 o C rises to 500 o C, heating rate is 1.5 o C / min, air is introduced; temperature from 500 o C rose to 900 o C, heating rate is 2.0 o C / min, air is introduced; temperature from 900 o C rose to 1100 o C, heating rate is 1.5 o C / min, air is introduced, and at 1100 o Keep warm at 1100°C for 2 hours; temperature rise from 1100°C. o C rose to 1200 o C, heating rate is 1.5 o C / min, air is introduced, and at 1200 o Keep warm at 1200°C for 2 hours; temperature from 1200°C o C rose to 1280 o C~1320 o C, heating rate is 1.5 o C / min, air is introduced; temperature reaches 1280℃ o C~1320 o After temperature C, a mixture of nitrogen and oxygen with an oxygen partial pressure of 2.0%~3.2% is introduced and kept at this temperature for 2 hours; the temperature is then increased from 1280°C. o C~1320 o C drops to 1100 o C, cooling rate is 1.5o C / min, oxygen partial pressure drops to 1.8%; temperature drops from 1100 o C drops to 900 o C, cooling rate is 1.5 o At C / min, the oxygen partial pressure gradually decreased to 0.02%; the temperature increased from 900°C. o C drops to 500 o C, cooling rate is 2 o C / min, oxygen partial pressure drops to 0%; temperature from 500 o The temperature drops to room temperature at a rate of 3. o C / min, oxygen partial pressure drop to 0%.

[0018] Secondly, the present invention provides a high resistivity, wide temperature range, and low loss MnZn ferrite, which is prepared by a method for preparing high resistivity, wide temperature range, and low loss MnZn ferrite.

[0019] Thirdly, the present invention relates to the application of a high resistivity, wide temperature range, and low loss MnZn ferrite, which is used in electronic components.

[0020] Compared with the prior art, the present invention has the following technical effects:

[0021] This invention provides a high-resistivity, wide-temperature-range, low-loss MnZn ferrite. The main materials are Fe2O3, MnO, and ZnO, which, combined with a suitable preparation process, can form a spinel-phase MnZn ferrite. The first auxiliary material is a high-resistivity additive containing CaCO3, ZrO2, HfO2, and TiO2. These additives can accumulate at the grain boundaries of the MnZn ferrite, increasing the overall resistivity of the material. The second auxiliary material is low-melting-point Bi2O3, which can form a liquid phase during sintering, thereby promoting the grain growth of MnZn ferrite. Based on the above composition, a MnZn ferrite material with sufficient grain growth and high grain boundary resistivity can be prepared, effectively suppressing hysteresis loss and eddy current loss.

[0022] This invention provides a method for preparing high-resistivity, wide-temperature-range, low-loss MnZn ferrite. The second auxiliary material, Bi₂O₃, forms a liquid phase during sintering, but it is difficult to control the promoting effect of the liquid phase on grain growth. Typically, the addition of Bi₂O₃ leads to abnormal grain growth and porosity. This invention employs the traditional oxide ceramic method, with the core technology being a segmented, multi-step heat-holding method during sintering. This allows for sufficient grain growth without abnormal growth and enables timely gas removal, effectively preventing porosity formation and producing low-loss MnZn ferrite over a wide temperature range. Simultaneously, the segmented, multi-step heat-holding sintering method reduces energy consumption and production costs. Attached Figure Description

[0023] Figure 1 SEM comparison images of the samples. Detailed Implementation

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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 well-known unit of mass in the chemical industry, such as µg, mg, g, or kg.

[0030] The terms “first” and “second” are used only to describe the purpose and to distinguish the target substances from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features.

[0031] To address the growing demand for highly integrated power devices, this invention provides a high-resistivity, wide-temperature-range, low-loss MnZn ferrite and its preparation method. The core idea of ​​this invention is: based on a suitable main formulation, a first auxiliary material, namely high-resistivity CaCO3, ZrO2, HfO2, and TiO2, is added during the secondary ball milling process to construct thin and high-resistivity MnZn ferrite grain boundaries, thereby increasing the overall resistivity of the material and effectively suppressing eddy current losses; and a second auxiliary material, namely low-melting-point Bi2O3, is added to promote the grain growth of MnZn ferrite, ensuring sufficient grain growth. Simultaneously, a segmented, multi-step heat preservation method is employed during the sintering process, with temperatures at 1100°C and 1100°C respectively. o C, 1200 o C and 1280-1310 o By holding the solution at C for 2 hours, abnormal grain growth caused by Bi₂O₃ and the phenomenon of pores being trapped inside the grains were avoided. The prepared MnZn ferrite microstructure was excellent, with uniform grain size distribution, very few pores, thin and high-resistivity grain boundaries. o C~120 o It exhibits extremely low loss values ​​at C. The preparation process includes the following steps:

[0032] Ingredients

[0033] Based on the main components of 52.8~53.8 mol% Fe2O3, 37.2~38.2 mol% MnO, and the balance being ZnO, calculate the mass of Fe2O3, Mn3O4, and ZnO raw materials required to prepare 450g of powder, accurate to four decimal places, and weigh each raw material using an analytical balance with a strength of 0.01%.

[0034] One ball mill

[0035] The main material is put into a planetary ball mill for ball milling and mixing. The ball milling time is 2-4 hours, the ball milling media is Φ3mm zirconium balls, the ball milling speed is 241 rpm, the mixed slurry is placed in an oven to dry for 24 hours, and then passed through a 40-mesh sieve.

[0036] Pre-fired

[0037] The sieved powder was compacted under 10 kg pressure and then placed in a bell-shaped furnace at 2... o C / min~3 o The heating rate increased from room temperature to 900 °C / min. o C, at 900 o Keep warm at 1.5-3 hours under temperature, then at 2 o C / min~3 o The cooling rate is reduced from 900 °C / min. o C drops to room temperature;

[0038] Secondary ball mill

[0039] The pre-calcined powder is mechanically crushed and passed through a 40-mesh sieve. The first auxiliary material, namely 0.2-0.4 wt% CaCO3, 0.03-0.06 wt% ZrO2, 0.05-0.07 wt% HfO2, and 0.1-0.3 wt% TiO2, and the second auxiliary material, 0.04-0.07 wt% Bi2O3, are added to the sieved powder. The main material and the first and second auxiliary materials are then placed in a ball mill for ball milling for 3-5 hours. The ball milling media is Φ2.5 mm bearing steel, and the ball milling speed is 289 rpm. The slurry after the second ball milling is placed in an oven and dried for 24 hours.

[0040] Granulation

[0041] After secondary ball milling, the powder is mechanically crushed and passed through a 40-mesh sieve. 10.5-14.5 wt% of PVA adhesive is added to the sieved powder. The powder and adhesive are mixed and granulated. After granulation, the powder is passed through 40-mesh and 160-mesh sieves, and particles with a size between 40-mesh and 160-mesh are taken.

[0042] forming

[0043] The granules are placed in a mold and pressed into ring-shaped and disc-shaped green bodies under a pressure of 5.5MPa to 8.5MPa.

[0044] sintering

[0045] The annular green body was placed in an atmosphere-type tube furnace and sintered at 1280°C according to a specific sintering curve. o C~1320 o C is used for sintering, with an oxygen partial pressure of 2.0%~3.2%.

[0046] test

[0047] The initial permeability of the toroidal sample obtained in step S7 was tested using a BH analyzer of model SY-8218 under the following conditions: 1 kHz, 1 A / m.

[0048] The loss of the toroidal sample obtained in step S7 was tested using a BH analyzer (model SY-8218). The test conditions were 100 kHz, 200 mT, and 25~120 °C. o C;

[0049] The resistance of the disc-shaped sample obtained in step S7 was tested using an impedance analyzer of model Keysight E4991B. R The test conditions were 100kHz and 1V, according to the formula. ρ=RS / d The resistivity of the disc-shaped sample was calculated, where d The thickness of the disc, S Let be the area of ​​the circular piece.

[0050] The invention will now be described in detail through specific embodiments.

[0051] Example

[0052] Table 1

[0053]

[0054] Comparative Example

[0055] Table 2

[0056]

[0057] Example 1

[0058] A high resistivity, wide temperature range, and low loss ferrite is prepared by the following steps:

[0059] (1) Prepare MnZn ferrite main material, first auxiliary material and second auxiliary material, wherein the main material contains 52.8 mol% Fe2O3, 37.4 mol% MnO4 and 9.8 mol% ZnO; the first auxiliary material contains 0.2 wt% CaCO3, 0.03 wt% ZrO2, 0.05 wt% HfO2 and 0.2 wt% TiO2 based on the weight of the main material; the second auxiliary material contains 0.04 wt% Bi2O3 based on the weight of the main material.

[0060] (2) The MnZn ferrite main material was put into a ball mill for ball milling. The ball milling time was 4 hours. The ball milling media was Φ3mm zirconium balls. The ball milling speed was 241 rpm. The mixed slurry was placed in an oven to dry for 24 hours. After drying, it was passed through a 40-mesh sieve.

[0061] (3) Place the sieved powder in a bell-shaped furnace and heat it at 2... o The heating rate increased from room temperature to 900 °C / min. o C, at 900 o Keep warm at C for 2 hours, then at 2 o The cooling rate is reduced from 900 °C / min. o C drops to room temperature;

[0062] (4) The pre-calcined powder is mechanically crushed and passed through a 40-mesh sieve. The sieved powder, the first auxiliary material, and the second auxiliary material are put into a ball mill for ball milling. The ball milling time is 5 hours, the ball milling medium is Φ2.5mm bearing steel, the ball milling speed is 289 rpm, and the slurry after the second ball milling is placed in an oven to dry for 24 hours.

[0063] (5) The dried powder is mechanically crushed and passed through a 40-mesh sieve. 12.5wt% of PVA adhesive is added to the sieved powder. The powder and adhesive are mixed and granulated. After granulation, the powder is passed through a 40-mesh and a 160-mesh sieve. Particles with a size between 40-mesh and 160-mesh are taken.

[0064] (6) Place the granules in a mold and press them into ring-shaped green blanks and disc green blanks under a pressure of 6.5 MPa;

[0065] (7) Place the green billet in an atmosphere-type tube furnace and sinter it in segments and steps according to a specific sintering curve at 1100°C. o Keep warm at 1200°C for 2 hours. o Keep warm at 1310°C for 2 hours, then finally at 1310°C. o Incubation at C for 2 hours resulted in an oxygen partial pressure of 2.9%.

[0066] Example 2

[0067] A high resistivity, wide temperature range, and low loss ferrite is prepared by the following steps:

[0068] (1) Prepare MnZn ferrite main material, first auxiliary material and second auxiliary material, wherein the main material and first auxiliary material are the same as in Example 1, and the second auxiliary material is 0.05wt% Bi2O3.

[0069] (2) The preparation steps are exactly the same as in Example 1.

[0070] Example 3

[0071] A high resistivity, wide temperature range, and low loss ferrite is prepared by the following steps:

[0072] (1) Prepare MnZn ferrite main material, first auxiliary material and second auxiliary material, wherein the main material contains 53.0 mol% Fe2O3, 37.2 mol% MnO and 9.8 mol% ZnO; the first auxiliary material is the same as in Example 1; the second auxiliary material is 0.05 wt% Bi2O3.

[0073] (2) The preparation steps are almost the same as in Example 1, except that the maximum heat preservation temperature is 1300°C. o C.

[0074] Example 4

[0075] A high resistivity, wide temperature range, and low loss ferrite is prepared by the following steps:

[0076] (1) Prepare the main material of MnZn ferrite, the first auxiliary material and the second auxiliary material, wherein the main material contains 53.4 mol% Fe2O3, 37.2 mol% MnO and 9.4 mol% ZnO; the first auxiliary material is the same as in Example 1; the second auxiliary material is 0.06 wt% Bi2O3.

[0077] (2) The preparation steps are almost the same as in Example 1, except that the maximum heat preservation temperature is 1290°C. o C.

[0078] Example 5

[0079] A high resistivity, wide temperature range, and low loss ferrite is prepared by the following steps:

[0080] (1) Prepare the main material of MnZn ferrite, the first auxiliary material and the second auxiliary material, wherein the main material contains 53.4 mol% Fe2O3, 37.2 mol% MnO and 9.4 mol% ZnO; the first auxiliary material is the same as in Example 1; the second auxiliary material is 0.07 wt% Bi2O3.

[0081] (2) The preparation steps are almost the same as in Example 1, except that the maximum heat preservation temperature is 1290°C. o C.

[0082] Example 6

[0083] A high resistivity, wide temperature range, and low loss ferrite is prepared by the following steps:

[0084] (1) Prepare the main material of MnZn ferrite, the first auxiliary material and the second auxiliary material, wherein the main material contains 53.8 mol% Fe2O3, 37.0 mol% MnO and 9.2 mol% ZnO; the first auxiliary material is the same as in Example 1; the second auxiliary material is 0.07 wt% Bi2O3.

[0085] (2) The preparation steps are almost the same as in Example 1, except that the maximum heat preservation temperature is 1280°C. o C.

[0086] Comparative Example 1

[0087] A MnZn ferrite material is prepared by the following steps:

[0088] (1) Prepare the main material of MnZn ferrite, the first auxiliary material and the second auxiliary material, wherein the main material contains 52.8 mol% Fe2O3, 37.4 mol% MnO and 9.8 mol% ZnO; the first auxiliary material is the same as in Example 1; the second auxiliary material is 0.02 wt% Bi2O3.

[0089] (2) The preparation steps are almost the same as in Example 1, except that the maximum heat preservation temperature is 1330°C. o C.

[0090] Comparative Example 2

[0091] A MnZn ferrite material is prepared by the following steps:

[0092] (1) Prepare the main material of MnZn ferrite, the first auxiliary material and the second auxiliary material, wherein the main material contains 53.8 mol% Fe2O3, 37.0 mol% MnO and 9.2 mol% ZnO; the first auxiliary material is the same as in Example 1; the second auxiliary material is 0.08 wt% Bi2O3.

[0093] (2) The preparation steps are almost the same as in Example 1, except that the maximum heat preservation temperature is 1260°C. o C.

[0094] SEM images of the high resistivity, wide temperature range, and low loss MnZn ferrites in the above embodiments and comparative examples are shown below. Figure 1 As shown in Table 2, the relevant performance parameters are as follows.

[0095] Depend on Figure 1 As can be seen from the SEM images and the performance parameters of Examples 1-6 in Table 2, the MnZn ferrite prepared by this invention has uniform grains, few pores, and exhibits high resistivity and low loss over a wide temperature range. Among them, the samples of Examples 3 and 4 show the best performance, with the highest initial permeability, the fewest pores, and the highest density (25-120). o C has the lowest loss.

[0096] Comparing Examples 1 and 2 with Examples 3 and 4, it can be seen that reducing the content of the second auxiliary material Bi2O3 and increasing the maximum holding temperature, based on Examples 3 and 4, results in a slight increase in porosity and a slight decrease in density, initial permeability, and resistivity due to the reduction of the liquid phase and the increase in sintering temperature during the sintering process. (25~120) o C loss increased slightly.

[0097] Comparing Examples 5 and 6 with Examples 3 and 4, it can be seen that increasing the content of the second auxiliary material Bi2O3 and lowering the maximum holding temperature, based on Examples 3 and 4, leads to a decrease in grain uniformity, a slight increase in porosity, and a slight decrease in density, initial permeability, and resistivity due to the increase in liquid phase and the decrease in sintering temperature during the sintering process. (25~120) o C loss increased slightly.

[0098] Comparing Comparative Example 1 with Examples 3 and 4, it can be seen that significantly reducing the content of the second auxiliary material Bi2O3 and increasing the maximum holding temperature, based on Examples 3 and 4, leads to poorer grain uniformity, increased porosity, and decreased density, initial permeability, and resistivity due to the reduction of the liquid phase and the increase in sintering temperature during the sintering process. (25~120) o C loss increases.

[0099] Comparing Comparative Example 2 with Examples 3 and 4, it can be seen that increasing the content of the second auxiliary material Bi2O3 and significantly reducing the maximum holding temperature, based on Examples 3 and 4, leads to a sharp increase in porosity and a sharp decrease in density, initial permeability, and resistivity due to the increase in liquid phase and the decrease in sintering temperature during the sintering process. (25~120) o C loss increases dramatically.

[0100] As can be seen from the above data, in the preparation process of the high resistivity wide-temperature low-loss MnZn ferrite of the present invention, the first auxiliary material is used to improve the overall resistivity of the material, and the second auxiliary material of 0.04~0.07wt% Bi2O3 is added to promote sufficient grain growth. At the same time, the segmented multi-step heat preservation sintering method is combined to make the grain growth of MnZn ferrite sufficient and uniform, and the grain boundaries thin and high resistivity, which has the best effect on improving resistivity and reducing loss over a wide temperature range.

[0101] Table 3

[0102]

[0103] 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 high resistivity, wide temperature range, and low loss MnZn ferrite, characterized in that, include: The main material is obtained by mixing 52.8–53.8 mol% Fe₂O₃ and 37.2–38.2 mol% MnO, with the balance being ZnO; the first auxiliary material is obtained by mixing 0.2–0.4 wt% CaCO₃, 0.03–0.06 wt% ZrO₂, 0.05–0.07 wt% HfO₂, and 0.1–0.3 wt% TiO₂; the second auxiliary material is obtained by mixing 0.04–0.07 wt% Bi₂O₃. The main material is put into a ball mill for one ball milling and mixing, and then pre-calcined to obtain pre-calcined powder. The pre-calcined powder is crushed, and the first and second auxiliary materials are added to the sieved powder and then ball-milled a second time. The powder after secondary ball milling is mixed with adhesive and granulated. The granulated particles are placed in a mold and pressed into a ring-shaped green body. The ring-shaped green body is sintered to obtain ferrite. The pre-firing process is as follows: the sieved powder is placed in a bell-shaped furnace and fired at 2... o C / min~3 o The heating rate increased from room temperature to 900 °C / min. o C, at 900 o Keep warm at 1.5-3 hours under temperature, then at 2 o C / min~3 o The cooling rate is reduced from 900 °C / min. o C drops to room temperature; During granulation, 10.5–14.5 wt% PVA adhesive is added to the sieved powder. The powder and adhesive are mixed and granulated. After granulation, the mixture is passed through 40-mesh and 160-mesh sieves, and particles with a size between 40-mesh and 160-mesh are collected. The PVA adhesive is prepared by mixing 117 adhesive and 217 adhesive at a mass ratio of 1:2 and slowly pouring the mixture into 100... o C is obtained by boiling in boiling water for 2 hours; During forming, the ring-shaped green body is pressed into a ring shape under a pressure of 5.5 MPa to 8.5 MPa; during sintering, the ring-shaped green body is placed in an atmosphere-type tube furnace and sintered at 1280 °C according to the sintering curve. o C~1320 o C is used for sintering, with an oxygen partial pressure of 2.0%~3.2%; The sintering process employs a segmented, multi-step heat preservation method. The specific sintering curve is as follows: Stage 1: Temperature from 50... o C rises to 200 o C, heating rate is 2.5 o C / min, air is introduced; temperature from 200 o C rises to 500 o C, heating rate is 1.5 o C / min, air is introduced; temperature from 500 o C rose to 900 o C, heating rate is 2.0 o C / min, air is introduced; temperature from 900 o C rose to 1100 o C, heating rate is 1.5 o C / min, air is introduced, and at 1100 o Keep warm at 1100°C for 2 hours; temperature rise from 1100°C. o C rose to 1200 o C, heating rate is 1.5 o C / min, air is introduced, and at 1200 o Keep warm at 1200°C for 2 hours; temperature from 1200°C o C rose to 1280 o C~1320 o C, heating rate is 1.5 o C / min, air is introduced; temperature reaches 1280°C. o C~1320 o After temperature C, a mixture of nitrogen and oxygen with an oxygen partial pressure of 2.0%~3.2% is introduced and kept at this temperature for 2 hours; the temperature is then increased from 1280°C. o C~1320 o C drops to 1100 o C, cooling rate is 1.5 o C / min, oxygen partial pressure drops to 1.8%; temperature drops from 1100 o C drops to 900 o C, cooling rate is 1.5 o At C / min, the oxygen partial pressure gradually decreased to 0.02%; the temperature decreased from 900... o C drops to 500 o C, cooling rate is 2 o C / min, oxygen partial pressure drops to 0%; temperature from 500 o The temperature drops to room temperature at a rate of 3. o C / min, oxygen partial pressure drop to 0%.

2. The method for preparing high resistivity, wide temperature range, and low loss MnZn ferrite according to claim 1, characterized in that, During a single ball milling process, the milling time is 2-4 hours, the milling media is Φ3mm zirconium balls, the milling speed is 241 rpm, and the mixed slurry is placed in an oven to dry for 24 hours. After drying, it is passed through a 40-mesh sieve.

3. The method for preparing high resistivity, wide temperature range, and low loss MnZn ferrite according to claim 1, characterized in that, Before pre-firing, the powder is compacted with a pressure of 10 kg.

4. The method for preparing high resistivity, wide temperature range, and low loss MnZn ferrite according to claim 1, characterized in that, During the second ball milling, the milling time is 3-5 hours, the milling medium is Φ2.5mm bearing steel, and the milling speed is 289 rpm. The slurry after the second ball milling is placed in an oven to dry for 24 hours.

5. A high resistivity, wide temperature range, and low loss MnZn ferrite, characterized in that, It is prepared by the method for preparing high resistivity, wide temperature range and low loss MnZn ferrite according to any one of claims 1 to 4.

6. An application of the high resistivity, wide temperature range, and low loss MnZn ferrite as described in claim 5, characterized in that, High resistivity, wide temperature range, and low loss MnZn ferrites are used in electronic components.

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