A high-permeability, temperature-stable manganese-zinc ferrite material and its preparation method

Abstract

This invention belongs to the technical field of manganese-zinc soft magnetic ferrite materials, specifically disclosing a high-permeability temperature-stable manganese-zinc ferrite material and its preparation method. This material maintains a relatively small fluctuation in initial permeability over a wide temperature range of -40℃ to 70℃. It comprises a basic component and secondary components. The basic component consists of 53.5–54.5 mol% ferric oxide, 18.5–19.5 mol% zinc oxide, and the remainder being manganese oxide. The secondary components, calculated as 100 wt% of the main component, consist of 0.02–0.10 wt% calcium carbonate, 0.002–0.01 wt% nano-silica, 0.01–0.05 wt% niobium pentoxide, 0.10–0.30 wt% titanium dioxide, and 0.05–0.15 wt% cobalt tetroxide. The material is prepared by steps including weighing, mixing, pre-firing, ball milling, sand milling, granulation, molding, and sintering. By controlling the proportion of basic components and secondary components, the temperature stability of the initial magnetic permeability of the material can be improved.

Description

Technical Field

[0001] This invention belongs to the technical field of manganese-zinc soft magnetic ferrite materials, specifically relating to a high-permeability, temperature-stable manganese-zinc ferrite material and its preparation method. Background Technology

[0002] With the continuous development of technology, the market has put forward wide-temperature requirements for the performance of many manganese-zinc ferrite materials. Outdoor facilities of modern communication equipment, such as repeaters, amplifiers, and various high-precision instruments and equipment, not only require high temperatures, but also require the equipment to work reliably and stably at low temperatures. Therefore, high requirements are placed on the stability of the initial magnetic permeability of materials in the temperature range of -40℃ to 70℃.

[0003] Since both saturation polarization and energy parameters are affected by temperature, the initial permeability also strongly depends on temperature. Conventional manganese-zinc ferrites exhibit an initial permeability starting from a small value at low temperatures, increasing with temperature or increasing to a second peak temperature before decreasing, then increasing again with further temperature until reaching a maximum value at the Curie temperature, followed by a sharp drop. This is due to the changes in magnetocrystalline anisotropy and saturation magnetization with temperature. Therefore, requiring the manganese-zinc ferrite material to possess high stability of initial permeability within a temperature range of -40℃ to 70℃ is a challenging problem that urgently needs to be solved by researchers in this field. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the main objective of this invention is to provide a high-permeability, temperature-stable manganese-zinc ferrite material.

[0005] Another object of the present invention is to provide a method for preparing the high permeability temperature-stability manganese-zinc ferrite material.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention provides a high-permeability, temperature-stable manganese-zinc ferrite material, comprising a basic component and auxiliary components, wherein:

[0008] The basic components, based on a total amount of 100 mol%, consist of 53.5–54.5 mol% ferric oxide, 18.5–19.5 mol% zinc oxide, and the remainder being manganese oxide.

[0009] The secondary components, based on 100 wt% of the basic components, consist of 0.02–0.10 wt% calcium carbonate, 0.002–0.01 wt% nano-silica, 0.01–0.05 wt% niobium pentoxide, 0.10–0.30 wt% titanium dioxide, and 0.05–0.15 wt% cobalt tetroxide.

[0010] Preferably, the total amount of the basic components, calculated as 100 mol%, consists of 53.8–54.3 mol% ferric oxide, 18.7–19.2 mol% zinc oxide, and the balance manganese oxide.

[0011] Preferably, the by-products, based on 100 wt% of the basic components, are 0.03–0.08 wt% calcium carbonate, 0.002–0.005 wt% nano-silica, 0.015–0.03 wt% niobium pentoxide, 0.08–0.12 wt% cobalt tetroxide, and 0.10–0.20 wt% titanium dioxide.

[0012] Preferably, the difference between the maximum and minimum initial magnetic permeability of the high-permeability temperature-stability manganese-zinc ferrite material within the temperature range of -40℃ to 70℃ is less than 20% of the average initial magnetic permeability within the same temperature range. Using the above-mentioned preferred dosage range of basic and secondary components results in a material with even better temperature stability of magnetic permeability.

[0013] The magnetocrystalline anisotropy constant K1 is one of the factors controlling the stability of the initial permeability over a wide temperature range. Maintaining a stable K1 value within the desired temperature range ensures minimal fluctuations in the initial permeability. The K1 value is primarily determined by the various components that make up the ferrite; in this invention, Fe has a positive K1 value. 2+ and Co 2+ Fe has a negative K1 value. 3+ Ti 4 + Mn 2+ Co 2+ This can reduce the temperature dependence of K1, thus reducing the rate of temperature change of K1. Therefore, if Co is added... 2+ Then compared to not adding Co 2+ It exhibits stability over a wider temperature range. Furthermore, due to Ti... 4+ The gradient distribution of K1 within the crystal inevitably leads to non-uniformity of K1 values ​​within the crystal. Therefore, within a certain temperature range, due to the... 4+ The entry of the material and its gradient distribution will cause the two maxima of the K1-T curve in each region to be located differently within the crystal, and the superposition of these maxima leads to an increase in the initial permeability temperature stability. This invention mainly controls the proportion range of each component of the material to keep the magnetocrystalline anisotropy constant K1 stable within the required temperature range.

[0014] As the grain size of the material increases, Ti will... 4+ When the gradient is not obvious and the grain boundaries are relatively thinner, reducing this non-uniform distribution will enhance μ. iThe sharpness of the two peaks in the ~T curve deteriorates the temperature characteristics of the material. Therefore, the addition of Nb₂O₅, mainly located at the grain boundaries, can inhibit grain growth, thus ensuring a uniform microstructure that is beneficial to Ti. 4+ The impact on the K1 value.

[0015] The addition of the remaining byproducts CaCO3 and nano-SiO2 in this invention mainly improves the resistivity of manganese-zinc ferrite, optimizes the initial magnetic permeability frequency performance of the material, and reduces the specific loss factor of the material.

[0016] This invention also provides a method for preparing the above-mentioned high permeability temperature-stable manganese-zinc ferrite material, comprising the following steps:

[0017] (1) Weighing: Select ferric oxide, zinc oxide and manganese oxide as the main components of raw materials and weigh them for batching;

[0018] (2) Mixing: The main components from step (1) are mixed in a vibratory ball mill;

[0019] (3) Pre-firing: The mixed powder from step (2) is placed in a muffle furnace for pre-firing. After holding it at the temperature for 1 hour, it is immediately taken out and cooled under air conditions.

[0020] (4) Ball milling: The pre-calcined material is ball milled until the powder D50 particle size is less than 3μm;

[0021] (5) Sand milling: Add auxiliary components to the powder after ball milling and add pure water for secondary grinding. The D50 particle size of the slurry after grinding is less than 2.0μm.

[0022] (6) Granulation: After the slurry after sand milling is dried, PVA is added for granulation;

[0023] (7) Molding: The granulated powder is pressed into a ring-shaped green body;

[0024] (8) Sintering: The formed green blank is sintered under nitrogen protection to obtain a high magnetic permeability temperature stable manganese zinc ferrite material.

[0025] Preferably, in step (3), the pre-burning and heat preservation temperature is 840℃~920℃.

[0026] Preferably, in step (8), the sintering temperature is 1300-1340℃ and the holding time is 2-8h.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention effectively controls the temperature characteristics of the magnetocrystalline anisotropy constant K1 of the material by determining the ratio of ferric oxide to zinc oxide in the basic components and the added by-components for reaction, and finally obtains a high-permeability temperature-stable manganese-zinc ferrite material. The initial permeability of the material is 2500±25% in the temperature range of -40℃ to 70℃, the Curie temperature of the material is ≥170℃, and the difference between the maximum and minimum initial permeability in the temperature range of -40℃ to 70℃ is less than 20% of the average value of the initial permeability in the temperature range. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0029] Example 1

[0030] Weigh the Fe2O3, ZnO, and MnO according to the proportions shown in Table 1, mix, pre-calcine (850℃), and ball-mill (until the powder D50 particle size is less than 3μm); place the ball-milled powder into a grinder, and simultaneously add the remaining additives (CaCO3 0.04wt%, nano SiO2 0.002wt%, Nb2O5 0.025wt%, Co3O4 0.1wt%, TiO2 0.3wt%), and add pure water for wet grinding for 30 minutes until the slurry D50 particle size is less than 2μm; after wet grinding, remove the slurry, dry it, add PVA for granulation, and shape it into... The sample ring was placed in a sintering furnace with atmosphere control, the sintering temperature was set to 1330℃, and the holding time was 4h; the electrical properties of the sintered sample ring were tested.

[0031] Table 1

[0032]

[0033]

[0034] Note: All numbers marked with an asterisk (*) are comparative examples.

[0035] In Table 1, samples 2-3 and 8-9 are embodiments of the present invention, and their main components are all within the limits defined by the present invention, and their material properties fully meet the specifications. Sample 1 represents the performance of samples with Fe2O3 content less than the specified range; as the Fe2O3 content decreases, Fe... 2+The decrease in ions causes the second peak of the initial permeability temperature curve to shift to higher temperatures, resulting in a distinct second peak in the temperature range of -40℃ to 70℃, thus disrupting the temperature stability of permeability. Samples 4-6 exhibit performance characteristics where the Fe2O3 content exceeds the specified range. The increased Fe2O3 content leads to the presence of Fe... 2+ The increase in ions causes the second peak of the initial permeability temperature curve to shift to lower temperatures, affecting Fe. 2+ The more ions present, the greater the shift of the second peak towards lower temperatures, resulting in a more sloping initial permeability curve from -40℃ to 70℃, and a decrease in permeability stability. Similarly, samples 7, 10, and 11 had ZnO content exceeding the limits specified in this invention, and their performance did not fully meet the requirements.

[0036] Example 2

[0037] Weigh out raw materials containing 53.8 mol% Fe2O3, 18.8 mol% ZnO, and the balance MnO. Mix, pre-calcine (850℃), and ball mill (until the powder D50 particle size is less than 3 μm). Place the ball-milled powder into a grinder, and add the remaining additives (CaCO3 0.04 wt%, Nb2O5 0.025 wt%, SiO2 0.002 wt%, TiO2 0.3 wt%, and cobalt tetroxide 0.5 wt%). Add pure water and wet-mill for 30 min until the slurry D50 particle size is less than 2 μm. After wet milling, remove the slurry, dry it, add PVA for granulation, and shape it into a powder. The sample ring was placed in a sintering furnace with atmosphere control, the sintering temperature was set to 1330℃, and the holding time was 4h; the electrical properties of the sintered sample ring were tested.

[0038] Table 2

[0039]

[0040] Note: All numbers marked with an asterisk (*) are comparative examples.

[0041] In Table 2, samples without * are examples of the present invention, and the amount of Co3O4 added is within the range defined by the present invention, and the material properties meet the requirements. Samples marked with * are outside the range defined by the present invention, and their properties do not fully meet the requirements. The addition of Co3O4 has the effect of regulating temperature characteristics. When an appropriate amount of Co3O4 is added, the stability of the initial magnetic permeability in the temperature range of -40℃ to 70℃ is improved. However, if the amount added is insufficient or excessive, the stability will deteriorate because the influence on the magnetocrystalline anisotropy constant K1 exceeds the requirements.

[0042] Example 3

[0043] Weigh out raw materials containing 54.0 mol% Fe2O3, 18.9 mol% ZnO, and the balance MnO. Mix, pre-calcine (850℃), and ball mill (until the powder D50 particle size is less than 3 μm). Place the ball-milled powder into a grinder, and add the remaining additives (CaCO3 0.04 wt%, Nb2O5 0.025 wt%, SiO2 0.002 wt%, Co3O4 0.1 wt%, TiO2 addition amount is shown in Table 3). Add pure water and wet-mill for 30 min until the slurry D50 particle size is less than 2 μm. After wet milling, remove the slurry, dry it, add PVA for granulation and molding. The sample ring was placed in a sintering furnace with atmosphere control, the sintering temperature was set to 1330℃, and the holding time was 4h; the electrical properties of the sintered sample ring were tested.

[0044] Table 3

[0045]

[0046] Note: All numbers marked with an asterisk (*) are comparative examples.

[0047] In Table 3, samples without * are examples of the present invention, and the TiO2 addition amount is within the range defined by the present invention, and the material properties meet the requirements. Samples with * deviate from the range defined by the present invention, and their properties do not fully meet the requirements.

[0048] Example 4

[0049] Weigh out raw materials containing 54.4 mol% Fe2O3, 18.8 mol% ZnO, and the balance MnO. Mix, pre-calcine (850℃), and ball mill (until the powder D50 particle size is less than 3 μm). Place the ball-milled powder into a grinder, and simultaneously add the remaining additives (CaCO3 0.04 wt%, SiO2 0.003 wt%, Co3O4 0.1 wt%, TiO2 0.1 wt%, Nb2O5 as shown in Table 4), and add pure water for wet grinding for 30 min until the slurry D50 particle size is less than 2 μm. After wet grinding, remove the slurry, dry it, add PVA for granulation, and shape it into... The sample ring was placed in a sintering furnace with atmosphere control, the sintering temperature was set to 1330℃, and the holding time was 5h; the electrical properties of the sintered sample ring were tested.

[0050] Table 4

[0051]

[0052]

[0053] Note: All numbers marked with an asterisk (*) are comparative examples.

[0054] In Table 4, samples without * are examples of the present invention, and the Nb2O5 addition amount is within the range defined by the present invention, and the material properties meet the requirements. Samples with * are outside the range defined by the present invention, and their properties do not fully meet the requirements.

[0055] Example 5

[0056] Weigh out raw materials containing 54.1 mol% Fe2O3, 18.90 mol% ZnO, and the balance MnO. Mix, pre-calcine (holding temperature settings are shown in Table 5), and ball mill (until the powder D50 particle size is less than 3 μm). Place the ball-milled powder into a grinder, and add the remaining additives (CaCO3 0.08 wt%, Nb2O5 0.030 wt%, SiO2 0.003 wt%, Co3O4 0.15 wt%, TiO2 0.2 wt%). Add pure water and wet-mill for 30 minutes until the slurry D50 particle size is less than 2 μm. After wet milling, remove the slurry, dry it, add PVA for granulation, and shape it into... The sample ring was placed in a sintering furnace with atmosphere control, the sintering temperature was set to 1340℃, and the holding time was 5h; the electrical properties of the sintered sample ring were tested.

[0057] Table 5

[0058]

[0059] Note: All numbers marked with an asterisk (*) are comparative examples.

[0060] In Table 5, samples without * are embodiments of the present invention, and their pre-firing and holding temperatures are all within the range defined by the present invention, and their material properties meet the specifications. Samples marked with * deviate from the range defined by the present invention, and their properties do not fully meet the requirements of the specifications. The pre-firing temperature has a significant impact on the microstructure of the material. Too low a pre-firing temperature leads to increased activity of the powder, resulting in abnormally large grains after sintering, which affects the stability of the initial permeability. Conversely, too high a pre-firing temperature will cause discontinuous grain growth during sintering, also affecting stability.

[0061] Example 6

[0062] Weigh out raw materials containing 54.1 mol% Fe2O3, 19.3 mol% ZnO, and the balance MnO. Mix, pre-calcine (850℃), and ball mill (until the powder D50 particle size is less than 3 μm). Place the ball-milled powder into a grinder, and add the remaining additives (CaCO3 0.06 wt%, Nb2O5 0.025 wt%, SiO2 0.002 wt%, Co3O4 0.10 wt%, TiO2 0.1 wt%). Add pure water and wet-mill for 30 min until the slurry D50 particle size is less than 2 μm. After wet milling, remove the slurry, dry it, add PVA for granulation, and shape it into... The sample ring was placed in a sintering furnace with atmosphere control, and the sintering temperature was set as shown in Table 6. The holding time was 4 hours. The electrical properties of the sintered sample ring were tested.

[0063] Table 6

[0064]

[0065] Note: All numbers marked with an asterisk (*) are comparative examples.

[0066] In Table 6, samples without * are examples of the present invention, and their sintering temperatures are all within the range defined by the present invention, and their material properties meet the specifications. Samples with * deviate from the range defined by the present invention, and their properties do not fully meet the requirements of the specifications.

[0067] The above performance test results show that the high-stability manganese-zinc ferrite material prepared by the present invention has an initial magnetic permeability of 2500±25% in the temperature range of -40℃ to 70℃, a Curie temperature ≥170℃, and the difference between the maximum and minimum initial magnetic permeability in the temperature range of -40℃ to 70℃ is less than 20% of the average initial magnetic permeability in the temperature range.

[0068] The above description of the embodiments is intended to enable those skilled in the art to understand and use the present invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the principles of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A high-permeability, temperature-stable manganese-zinc ferrite material, characterized in that, Includes basic components and secondary components, among which: The basic components, based on a total amount of 100 mol%, consist of 53.5–54.5 mol% ferric oxide, 18.5–19.5 mol% zinc oxide, and manganese oxide. The by-products, calculated as 100 wt% of the basic components, consist of 0.02-0.10 wt% calcium carbonate, 0.002-0.01 wt% nano-silica, 0.015-0.03 wt% niobium pentoxide, 0.10-0.30 wt% titanium dioxide, and 0.05-0.15 wt% cobalt tetroxide; The preparation method of the high-permeability, temperature-stable manganese-zinc ferrite material includes the following steps: (1) Weighing: Select ferric oxide, zinc oxide and manganese oxide as the basic components of raw materials and weigh them for batching; (2) Mixing: The basic components from step (1) are mixed in a vibratory ball mill; (3) Pre-firing: The powder mixed in step (2) is placed in a muffle furnace for pre-firing. After holding at the temperature for 1 hour, it is immediately taken out and cooled under air conditions. The pre-firing temperature is 840℃~920℃. (4) Ball milling: The pre-calcined material is ball milled until the powder D50 particle size is less than 3μm; (5) Sand milling: Add auxiliary components to the powder after ball milling and add pure water for secondary grinding. The D50 particle size of the ground slurry is less than 2.0 μm. (6) Granulation: After the slurry after sand milling is dried, PVA is added for granulation; (7) Molding: The granulated powder is pressed into a ring-shaped green body; (8) Sintering: The formed green body is sintered under nitrogen protection at a temperature of 1300~1340℃ and held for 2~8h to obtain a high permeability temperature-stable manganese zinc ferrite material.

2. The high permeability temperature-stability manganese-zinc ferrite material according to claim 1, characterized in that, The total amount of the basic components, calculated at 100 mol%, consists of 53.8–54.3 mol% ferric oxide, 18.7–19.2 mol% zinc oxide, and manganese oxide.

3. The high permeability temperature-stability manganese-zinc ferrite material according to claim 1, characterized in that, The secondary components, calculated as 100 wt% of the basic components, consist of 0.03-0.08 wt% calcium carbonate, 0.002-0.005 wt% nano-silica, 0.015-0.03 wt% niobium pentoxide, 0.08-0.12 wt% cobalt tetroxide, and 0.10-0.20 wt% titanium dioxide.

4. The high permeability temperature-stability manganese-zinc ferrite material according to claim 1, characterized in that, The initial magnetic permeability of the material is 2500±25% in the temperature range of -40℃ to 70℃, and the Curie temperature of the material is ≥170℃.

5. The high permeability temperature-stability manganese-zinc ferrite material according to claim 1, characterized in that, The ratio of the difference between the maximum and minimum initial permeability within the temperature range of -40℃ to 70℃ to the average initial permeability within the same temperature range is less than 20%.

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