High-frequency Mn-Zn ferrite sintering process and product prepared thereby

Abstract

The application relates to the field of electronic information materials, in particular to a high-frequency manganese-zinc ferrite sintering process and a prepared product thereof. The process comprises the following steps: firstly, uniformly mixing main components and auxiliary component raw materials through ball milling, and then pre-sintering at high temperature to obtain pre-sintered powder; secondly, grinding and refining the pre-sintered powder, and then screening; thirdly, fully mixing, kneading and granulating the screened powder and an activator solution to obtain granular materials; fourthly, pressing the granular materials to form a blank product; and finally, sintering the blank product at a temperature below 1000 DEG C. The high-frequency manganese-zinc ferrite sintering process adopts a solvent surface activation method to improve the sintering activity of relatively coarse (2-5 mu m) ferrite pre-sintered powder and reduce the sintering temperature, can realize uniform, fine and dense microstructure at a sintering temperature below 1000 DEG C, and finally obtains high-frequency manganese-zinc ferrite with a working frequency above 5 MHz, high density, excellent magnetic performance and low power loss at high frequency.

Description

Technical Field

[0001] The present application relates to the field of electronic information materials, and in particular to a high-frequency manganese-zinc ferrite sintering process and its preparation products. Background Art

[0002] Manganese-zinc ferrite is primarily used in the manufacture of various inductors, transformers, filters, and chokes. It is an important component material widely used in electronic communications, national defense, and security. Manganese-zinc ferrite is made by high-temperature solid-phase sintering of iron oxide, zinc oxide, and manganese oxide. Its resistivity is several orders of magnitude higher than other soft magnetic materials, effectively suppressing high-frequency eddy currents and significantly increasing the operating frequency of ferrite compared to metal-based soft magnetic materials.

[0003] With the large-scale commercialization of 5G communication technology and third-generation semiconductors, the operating frequency of power devices has increased to MHz. The corresponding miniaturization and high-frequency development requirements of electronic devices are becoming increasingly stringent. This requires manganese-zinc ferrite to have higher operating frequencies and lower power losses. When the ferrite grain size is smaller than a certain size, the entire crystal becomes a single domain. This size is called the critical size of the single domain. By reducing the ferrite grain size to the single domain state (≤5μm), the high-frequency domain wall resonance of the manganese-zinc ferrite can be effectively eliminated, thereby increasing the operating frequency and reducing losses.

[0004] Traditional processes, such as solid oxide sintering, primarily reduce the grain size of manganese-zinc ferrite by doping it with grain growth inhibitors. However, adding too much growth inhibitor can reduce sintering density, leading to a decrease in both magnetic permeability and saturation magnetic induction. Furthermore, lowering the sintering temperature can also reduce the grain size of manganese-zinc ferrite. For example, Chinese patents CN107352991B and CN101266859A use coprecipitation and sol-gel methods, respectively, to prepare manganese-zinc ferrite, performing low-temperature sintering below 1000°C. However, the sol-gel method requires the use of organic solvents to dissolve the metal salts, resulting in a certain amount of residual organic solvent in the final sample, requiring additional steps to remove. Furthermore, the MnZn ferrite particles obtained by the coprecipitation method face difficulties in controlling the grain size and size distribution.

[0005] Currently, a common method for reducing the grain size of manganese-zinc ferrite is to use pre-calcined powder ≤ 0.5 μm to increase the powder surface area and enhance sintering activity. However, the sintering temperature is generally still above 1000°C. Excessively high sintering temperatures can lead to abnormal grain growth, uneven grain size, high porosity, and high energy consumption, which in turn deteriorate the material's high-frequency magnetic properties. Therefore, developing new methods for preparing manganese-zinc ferrite that can achieve densification and a fine-grained structure through sintering below 1000°C is of great practical significance. Summary of the Invention

[0006] Technical issues

[0007] Existing methods for sintering manganese-zinc ferrite generally still require temperatures exceeding 1000°C, which cannot guarantee the sintering quality of high-frequency, low-power manganese-zinc ferrite materials. The resulting manganese-zinc ferrite has low density and poor dimensional consistency. The power loss of manganese-zinc ferrite produced by existing methods is excessive at high frequencies. Furthermore, existing methods are cumbersome and complex to operate. The present invention aims to provide a process for sintering high-frequency manganese-zinc ferrite at low temperatures that is simple to operate and produces manganese-zinc ferrite with uniform composition, a dense structure, and excellent magnetic properties, while also reducing losses and conserving energy.

[0008] Technical Solution

[0009] The first aspect of the present application provides a high-frequency manganese-zinc ferrite sintering process, characterized in that the process includes the following specific steps:

[0010] a. Weigh the raw materials of high-frequency manganese-zinc ferrite, ball-mill the raw materials for 5 to 10 hours and mix them evenly to obtain a powder; wherein the raw materials are composed of a main component and a secondary component with a content of 0.19 to 0.75 wt%; wherein the main component is Fe2O 3、 ZnO and MnO2, the auxiliary component is SnO 2、 Co3O 4、 Composition of In2O3 and TiO2;

[0011] b. The powder is placed in an atmosphere sintering furnace for pre-firing, pre-firing under an inert atmosphere, the pre-firing temperature is 1100 to 1300 ° C, the temperature is raised to the pre-firing temperature and then kept warm, and the pre-firing is completed and the pre-firing powder is obtained by cooling the furnace;

[0012] c. Grind the calcined powder and sieve out a powder with a particle size of 2 to 5 μm;

[0013] d. The powder is thoroughly stirred with an activation solvent, kneaded and granulated to obtain a granular material; wherein the activation solvent is composed of water, polyvinyl alcohol and an activator; wherein the activator is one or more of ammonium nitrate, ammonium carbonate or ammonium bicarbonate;

[0014] e. Pressing the above granular material into a blank product;

[0015] f. The above-mentioned blank product is placed in an atmosphere sintering furnace for sintering. The sintering is carried out under an inert atmosphere at a sintering temperature of 850 to 1000°C. The temperature is raised to the sintering temperature and then kept warm. After sintering, the high-frequency manganese-zinc ferrite is obtained by cooling the furnace.

[0016] In some embodiments, based on 100% of the total mass of the main components, the Fe2O3 content is 68-72wt%, the ZnO content is 5.5-9wt%, and the MnO2 content is 19-25wt%; based on 100% of the total mass of the high-frequency manganese-zinc ferrite raw material, the SnO2 content is 0.05-0.25wt%, the Co3O4 content is 0.04-0.15wt%, the In2O3 content is 0.05-0.2wt%, and the TiO2 content is 0.05-0.15wt%.

[0017] In some embodiments, based on 100% of the total mass of the activation solvent, the content of the polyvinyl alcohol is 3-10 wt %, and the content of the activator is 1 wt %-5 wt %.

[0018] In some embodiments, the activator is ammonium nitrate or ammonium carbonate.

[0019] In some embodiments, the constant temperature increase rate in step b is 200-300° C. / h, and the insulation time is 2-3 h.

[0020] In some embodiments, the inert atmosphere in step b and step f maintains a balanced oxygen partial pressure and makes the oxygen partial pressure less than 2%; wherein the inert atmosphere is one of a nitrogen atmosphere, an argon atmosphere or a helium atmosphere.

[0021] In some embodiments, the grinding and refining in step c is performed by mechanical crushing and air flow milling, and the screening is performed by air flow classification.

[0022] In some embodiments, the density of the blank product in step e is 3.0 to 3.8 g cm -3 .

[0023] In some embodiments, the constant temperature increase rate in step f is 1-10° C. / min, and the insulation time is 4-10 h.

[0024] The second aspect of the present invention provides high-frequency manganese-zinc ferrite prepared by any of the high-frequency manganese-zinc ferrite sintering processes described above.

[0025] In some embodiments, the high-frequency manganese-zinc ferrite has a grain size of 2 to 5 μm, a density of ≥95%, a cutoff frequency of ≥5 MHz, and an initial magnetic permeability of higher than 600N.

[0026] Technical Effects

[0027] The ferrite prepared by the traditional method has the problems of abnormal grain growth and poor density. The present invention can improve the crystallinity and spinel phase purity of the pre-calcined powder by high-temperature pre-calcination. After the powder with a particle size of 2 to 5 μm is screened out and activated by the solvent surface, even if the specific surface area of ​​the powder is small, it has sufficient sintering activity and can be sintered and densified at a temperature below 1000°C. At the same time, the final product grain size is still maintained at 2 to 5 μm, avoiding abnormal growth of the grains and effectively maintaining the single domain structure, thereby ensuring its high cutoff frequency. More importantly, the present invention uses a solvent surface activation method to improve the sintering activity of the coarser (2 to 5 μm) ferrite pre-calcined powder and reduce its sintering temperature. A uniform fine-grained and densified microstructure can be achieved at a sintering temperature below 1000°C, and finally a high-frequency manganese-zinc ferrite with an operating frequency of more than 5 MHz, high density and excellent magnetic properties is obtained. In addition, the conventional manganese zinc ferrite has low loss in the high frequency range (500kHz~3M), and the high frequency manganese zinc ferrite of the present invention has a volume power consumption of no more than 2000kW / m at room temperature, cut-off frequency f=5MHz, B=30mT. 3 . BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Shown is a scanning electron microscope image of the high-frequency manganese-zinc ferrite prepared in Example 1;

[0029] Figure 2 Shown is a scanning electron microscope image of the high-frequency manganese-zinc ferrite prepared in Comparative Example 1. DETAILED DESCRIPTION

[0030] To facilitate the technical solution of the application, the following first provides a general explanation and definition of the terms and expressions involved in this application.

[0031] The terms "comprises," "comprising," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0032] The term "density" refers to density. For MnZn ferrite, while density is a physical property, it also has a certain impact on its magnetic properties. Increasing density can improve its saturation magnetic induction intensity to a certain extent. Furthermore, density can also reflect the porosity and uniformity of the MnZn ferrite's microstructure. Therefore, increasing density can improve material performance to a certain extent.

[0033] The term "initial permeability" refers to the extreme value of the core's amplitude permeability when the magnetic field intensity approaches zero. A high initial permeability means the material responds more quickly to external magnetic fields and is better able to absorb and conduct magnetic field energy. Therefore, MnZn ferrites with high initial permeability are widely used in electromagnetic interference (EMI) and electromagnetic compatibility (EMC) applications, such as inductors, transformers, and magnetic isolators.

[0034] The term "cutoff frequency" is used to describe a special frequency characteristic indicator. When the cutoff frequency of a material is reached during application, the material loss will increase sharply, and the loss will be converted into heat energy and heat, affecting the life of the device.

[0035] The "loss" of MnZn ferrite consists of three parts: hysteresis loss, eddy current loss and residual loss. In high-frequency applications, residual loss and eddy current loss play a major role.

[0036] The term "activating solvent" in the present invention refers to a mixed solution of activator, water and polyvinyl alcohol.

[0037] The term "solvent surface activation" in the present invention refers to using a certain activation solvent to react with the ferrite powder on the surface, thereby improving the sintering activity of the ferrite powder.

[0038] In each set of comparative experiments provided in this application, unless otherwise specified, other experimental conditions, materials, etc., except for the differences indicated in each group, are kept consistent to ensure comparability.

[0039] Unless otherwise specified, the reagents and instruments used in the embodiments of the present invention can be purchased from the market.

[0040] The following further describes a high-frequency manganese-zinc ferrite sintering process and its preparation products provided in this application.

[0041] Example 1: Preparation of high-frequency manganese-zinc ferrite

[0042] The main component raw materials, calculated as 100% by weight, are as follows: 70% by weight Fe₂O₃, 5.5% by weight ZnO, and 24.5% by weight MnO₂. The auxiliary component raw materials, calculated as 100% by weight of the high-frequency manganese-zinc ferrite raw materials, are as follows: 0.05% by weight SnO₂, 0.04% by weight Co₃O₄, 0.05% by weight In₂O₃, and 0.05% by weight TiO₂. The main and auxiliary components are weighed proportionally and placed in a ball mill for 5 hours to mix uniformly. The prepared powder is then heated to 1100°C at a rate of 200°C / hour under a nitrogen atmosphere, held at this temperature for 3 hours, and then cooled in the furnace. The high-temperature pre-sintered powder is mechanically crushed and jet milled, and then sieved using an air classifier to obtain a powder with a particle size of 2 to 5 μm. The sieved powder is thoroughly stirred and kneaded with an activation solvent, and granulated; the activation solvent is composed of water, polyvinyl alcohol, and an activator; the polyvinyl alcohol content is 5wt%, the activator content is 1wt%, and the activator is ammonium nitrate. The granulated material is pressed into a blank product with a density of 3.0g cm -3 The blank product was placed in an atmosphere sintering furnace at a sintering temperature of 850°C for 10 hours. During the sintering process, nitrogen was introduced to reduce the oxygen partial pressure to less than 2%. After cooling, the product was taken out of the furnace to obtain a low-temperature sintered high-frequency manganese-zinc ferrite (Ferrite-1). The electron microscope image of the high-frequency manganese-zinc ferrite is shown in FIG. Figure 1 shown.

[0043] Example 2: Preparation of high-frequency manganese-zinc ferrite

[0044] The main component raw materials, calculated as 100% by weight, are as follows: 68% by weight Fe2O3, 7% by weight ZnO, and 25% by weight MnO2. The auxiliary component raw materials, calculated as 100% by weight of the high-frequency manganese-zinc ferrite raw materials, are as follows: 0.01% by weight SnO2, 0.08% by weight Co3O4, 0.1% by weight In2O3, and 0.1% by weight TiO2. The main and auxiliary components are weighed proportionally and placed in a ball mill for 10 hours to mix uniformly. The prepared powder is then heated to 1200°C at a rate of 250°C / hour under a nitrogen atmosphere, held at this temperature for 3 hours, and then cooled in the furnace. The high-temperature pre-sintered powder is mechanically crushed and jet milled, and then sieved using an airflow classifier to obtain a powder with a particle size of 2 to 5 μm. The sieved powder was fully stirred and kneaded with an activation solvent, and granulated. The activation solvent consisted of water, polyvinyl alcohol, and an activator, wherein the concentration of polyvinyl alcohol was 6 wt%, the concentration of the activator was 2 wt%, and the activator was ammonium carbonate. The granulated material was pressed into a blank product with a density of 3.5 g cm -3 The blank product was placed in an atmosphere sintering furnace at a sintering temperature of 900°C for 8 hours. Nitrogen was introduced during the sintering process to reduce the oxygen partial pressure to less than 2%. The product was then cooled and taken out of the furnace to obtain low-temperature sintered high-frequency manganese-zinc ferrite (Ferrite-2).

[0045] Example 3: Preparation of high-frequency manganese-zinc ferrite

[0046] The main component raw materials, calculated as 100% by weight, are as follows: 71% by weight Fe₂O₃, 8% by weight ZnO, and 21% by weight MnO₂. The auxiliary component raw materials, calculated as 100% by weight of the high-frequency manganese-zinc ferrite raw materials, are as follows: 0.15% by weight SnO₂, 0.12% by weight Co₃O₄, 0.15% by weight In₂O₃, and 0.15% by weight TiO₂. The main and auxiliary components are weighed proportionally and placed in a ball mill for 8 hours to mix uniformly. The prepared powder is then heated to 1300°C at a rate of 250°C / hour under a nitrogen atmosphere, held at this temperature for 2 hours, and then cooled in the furnace. The high-temperature pre-sintered powder is mechanically crushed and jet milled, and then sieved using an air classifier to obtain a powder with a particle size of 2 to 5 μm. The sieved powder was fully stirred, kneaded and granulated with an activation solvent, wherein the activation solvent consisted of water, polyvinyl alcohol, and an activator, wherein the concentration of polyvinyl alcohol was 8wt%, the concentration of the activator was 3wt%, and the activator was ammonium bicarbonate. The granulated material was pressed into a blank product, and the density of the blank product was 3.8g cm -3 The blank product was placed in an atmosphere sintering furnace at a sintering temperature of 950°C for 6 hours. During the sintering process, nitrogen was introduced to reduce the oxygen partial pressure to less than 2%. The product was then cooled and taken out of the furnace to obtain low-temperature sintered high-frequency manganese-zinc ferrite (Ferrite-3).

[0047] Example 4: Preparation of high-frequency manganese-zinc ferrite

[0048] The main component raw materials, calculated as 100% by weight, are: 72% Fe2O3, 9% ZnO, and 19% MnO2. The auxiliary component raw materials, calculated as 100% by weight of the high-frequency manganese-zinc ferrite raw materials, are: 0.25% SnO2, 0.15% Co3O4, 0.2000% In2O3, and 0.1% TiO2. The main and auxiliary components are weighed proportionally and placed in a ball mill for 10 hours to mix uniformly. The prepared powder is then heated to 1250°C at a rate of 250°C / hour under a nitrogen atmosphere, held at this temperature for 3 hours, and then cooled in the furnace. The high-temperature pre-sintered powder is mechanically crushed and jet milled, and then sieved using an air classifier to obtain a powder with a particle size of 2 to 5 μm. The sieved powder was fully stirred and kneaded with an activation solvent, and granulated. The activation solvent consisted of water, polyvinyl alcohol, and an activator, wherein the concentration of polyvinyl alcohol was 10 wt%, the concentration of the activator was 5 wt%, and the activator was ammonium bicarbonate. The granulated material was pressed into a blank product with a density of 3.5 g cm -3The blank was placed in an atmosphere sintering furnace at a sintering temperature of 980°C for 8 hours. During the sintering process, nitrogen was introduced to reduce the oxygen partial pressure to less than 2%. The blank was then cooled and taken out of the furnace to obtain low-temperature sintered high-frequency manganese-zinc ferrite (Ferrite-4).

[0049] Example 5: Preparation of Comparative Example High-Frequency Manganese-Zinc Ferrite

[0050] Comparative Example 1:

[0051] The main component raw materials, calculated as 100% by weight, are: 70% Fe₂O₃, 5.5% ZnO, and 24.5% MnO₂. The auxiliary raw materials, calculated as 100% by weight of the high-frequency manganese-zinc ferrite raw materials, are: 0.05% SnO₂, 0.04% Co₃O₄, 0.05% In₂O₃, and 0.05% TiO₂. The main and auxiliary components are weighed proportionally and placed in a ball mill. Milling is performed for 5 hours to achieve uniform mixing. The resulting powder is then heated to 1100°C at a rate of 200°C / hour under a nitrogen atmosphere, held at this temperature for 3 hours, and then cooled in the furnace. The high-temperature pre-sintered powder is mechanically crushed and jet milled, and then sieved using an airflow classifier to obtain a powder with a particle size of 2 to 5 μm. The sieved powder is thoroughly mixed with water and polyvinyl alcohol (PVA) at a concentration of 5% by weight, kneaded, and granulated. The pellets obtained by granulation are pressed into blank products with a density of 3.0 g cm -3 The blank was placed in an atmosphere sintering furnace at a sintering temperature of 850°C for 10 hours. During the sintering process, nitrogen was introduced to reduce the oxygen partial pressure to less than 2%. After cooling, the blank was taken out of the furnace to obtain low-temperature sintered high-frequency manganese-zinc ferrite (Ferrite-5). The electron microscope image of the high-frequency manganese-zinc ferrite is shown in FIG. Figure 2 shown.

[0052] Comparative Example 2:

[0053] The main component raw materials, calculated as 100% by weight, are: 68% Fe₂O₃, 7% ZnO, and 25% MnO₂. The auxiliary raw materials, calculated as 100% by weight of the high-frequency manganese-zinc ferrite raw materials, are: 0.01% SnO₂, 0.08% Co₃O₄, 0.1% In₂O₃, and 0.1% TiO₂. The main and auxiliary components are weighed proportionally and placed in a ball mill. Milling is carried out for 10 hours to achieve uniform mixing. The resulting powder is then heated to 1200°C at a rate of 250°C / hour under a nitrogen atmosphere, held at this temperature for 3 hours, and then cooled in the furnace. The high-temperature pre-sintered powder is mechanically crushed and jet milled, and then sieved using an airflow classifier to obtain a powder with a particle size of 2-5 μm. The sieved powder is thoroughly mixed with water and polyvinyl alcohol (PVA) at a concentration of 6% by weight, kneaded, and granulated. The pellets obtained by granulation are pressed into blank products with a density of 3.5 g cm -3The blank was placed in an atmosphere sintering furnace at a sintering temperature of 900°C for 8 hours. Nitrogen was introduced during the sintering process to reduce the oxygen partial pressure to less than 2%. The blank was then cooled and taken out of the furnace to obtain low-temperature sintered high-frequency manganese-zinc ferrite (Ferrite-6).

[0054] Example 6: Characterization of high-frequency manganese-zinc ferrite

[0055] The high-frequency manganese-zinc ferrites prepared in Examples 1-4 and Comparative Examples 1-2 were characterized as follows:

[0056] (1) Grain size test: The grain size of high-frequency manganese-zinc ferrite was measured using a scanning electron microscope (model: ZEISS Sigma 300).

[0057] (2) Density test: Use the drainage method to determine the density of high-frequency manganese-zinc ferrite. The theoretical density of general ferrite is 5.5g / cm 3 , actual density / theoretical density = density.

[0058] (3) Cut-off frequency test: The cut-off frequency of high-frequency manganese-zinc ferrite was measured using an impedance analyzer (model: Keysight E4991B).

[0059] (4) Test of initial magnetic permeability: An impedance analyzer (model: Keysight E4991B) was used to measure the magnetic properties of high-frequency manganese-zinc ferrite.

[0060] (5) Loss test: Use BH analyzer (model: Yantong SY8218) to measure the loss of high-frequency manganese-zinc ferrite.

[0061] The characterization results are shown in Table 1.

[0062] Table 1 Characterization results of high frequency manganese zinc ferrite

[0063]

[0064] The results are shown in Table 1. When comparing the high-frequency manganese-zinc ferrite prepared in Example 1 with that prepared in Comparative Example 1, under the same main components, auxiliary components, sintering processes, etc., Example 1 introduces ammonium nitrate solvent for surface activation. Under the same grain size, the density of Example 1 is significantly improved (68% → 96%) compared with Comparative Example 1, resulting in a significant improvement in magnetic permeability (180 → 620) and a significant reduction in loss (6550kW / m 3 →1950kW / m 3 ).

[0065] Comparing the high-frequency manganese-zinc ferrite prepared in Example 2 and Comparative Example 2, under the same main components, auxiliary components, sintering processes, etc., Example 2 introduces ammonium carbonate for solvent surface activation. Under the condition of unchanged grain size, the density of Example 2 is significantly improved (76%→95%) compared with Comparative Example 2, resulting in a significant improvement in magnetic permeability (143→680) and a significant reduction in loss (5920kW / m 3 →1800kW / m 3 ).

[0066] The above specific implementation methods further illustrate the purpose, technical solutions and beneficial effects of this application in detail. It should be understood that the above are only specific implementation methods of this application and are not intended to limit the scope of protection of this application. Any modifications, equivalent replacements, improvements, etc. made on the basis of the technical solutions of this application should be included in the scope of protection of this application.

Claims

1. A high frequency manganese zinc ferrite sintering process, characterized in that: The process comprises the following specific steps: a. Weigh high-frequency manganese-zinc ferrite raw materials, ball-mill the raw materials to mix uniformly to obtain a powder; wherein the raw material consists of a main component and a content of 0.19~0.75 wt% of the secondary component; wherein the main component is Fe2O 3、 ZnO and MnO2, the auxiliary component is SnO 2、 Co3O 4、 Composition of In2O3 and TiO2; b. The powder is placed in an atmosphere sintering furnace and pre-fired under an inert atmosphere at a temperature of 1100 to 1300 ° C. The temperature is raised to the pre-fire temperature and then held constant. After the pre-fire is completed, the pre-fired powder is cooled and discharged. c. Grind the calcined powder and sieve out a powder with a particle size of 2 to 5 μm; d. The powder is thoroughly stirred with an activation solvent, kneaded and granulated to obtain granules; wherein the activation solvent is composed of water, polyvinyl alcohol and an activator; wherein the activator is one or more of ammonium nitrate, ammonium carbonate or ammonium bicarbonate; e The above-mentioned granular material is pressed into shape to obtain a rough product; f. Place the above-mentioned blank product into an atmosphere sintering furnace and sinter it under an inert atmosphere at a sintering temperature of 850~1000℃. Rise the temperature to the sintering temperature and then keep it warm. After sintering, cool it down and take it out of the furnace to obtain high-frequency manganese-zinc ferrite.

2. The high-frequency manganese-zinc ferrite sintering process according to claim 1, characterized in that: Based on 100% of the total mass of the main components, the Fe2O3 content is 68~72 wt%, the ZnO content is 5.5~9 wt%, and the MnO2 content is 19~25 wt%; based on 100% of the total mass of the high-frequency manganese-zinc ferrite raw material, the SnO2 content is 0.05~0.25 wt%, the Co3O4 content is 0.04~0.15 wt%, the In2O3 content is 0.05~0.2 wt%, and the TiO2 content is 0.05~0.15 wt%.

3. The high frequency manganese zinc ferrite sintering process according to claim 1, characterized in that: Based on 100% of the total mass of the activation solvent, the content of the polyvinyl alcohol is 5-10 wt%, and the content of the activator is 1-5 wt%.

4. The high-frequency manganese-zinc ferrite sintering process according to claim 3, characterized in that: The activator is ammonium nitrate or ammonium carbonate.

5. The high frequency manganese zinc ferrite sintering process according to claim 1, characterized in that: The constant temperature increase rate in step b is 200-300° C. / h, and the holding time is 2-3 h.

6. The high frequency manganese zinc ferrite sintering process according to claim 1, characterized in that: The inert atmosphere in step b and step f maintains a balanced oxygen partial pressure and makes the oxygen partial pressure less than 2%; wherein the inert atmosphere is one of a nitrogen atmosphere, an argon atmosphere or a helium atmosphere.

7. The high frequency manganese zinc ferrite sintering process according to claim 1, characterized in that: The grinding and refining in step c is carried out by mechanical crushing and air flow milling, and the screening is carried out by air flow classification.

8. The high frequency manganese zinc ferrite sintering process according to claim 1, characterized in that: The density of the blank product in step e is 3.0-3.8 g cm -3 .

9. The high frequency manganese zinc ferrite sintering process according to claim 1, characterized in that: The constant temperature increase rate in step f is 1-10°C / min, and the insulation time is 4-10 h.

10. The high-frequency manganese-zinc ferrite prepared by the high-frequency manganese-zinc ferrite sintering process according to any one of claims 1 to 9, characterized in that: The high-frequency manganese-zinc ferrite has a grain size of 2-5 μm, a density of ≥95%, a cutoff frequency of ≥5 MHz, and an initial magnetic permeability of higher than 600.

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