Mn-Zn ferrite granulated powder, Mn-Zn ferrite and preparation method and application thereof

Abstract

The application discloses a kind of manganese-zinc ferrite granulation powder, manganese-zinc ferrite and preparation method, application thereof, belong to magnetic material field.Granulation powder includes main material and auxiliary material, the composition of main material is iron compound, zinc compound and manganese compound, iron compound is 52~55mol% with Fe2O3 conversion amount, zinc compound is 19~22mol% with ZnO conversion amount, manganese compound is the balance with MnO conversion amount, the particle size of auxiliary material is within 100nm, and its composition includes CaCO3, Co3O4, Nb2O5, V2O5 four kinds, wherein:CaCO3 accounts for 200ppm~1000ppm of the total weight of main material, Co3O4 accounts for 500ppm~2000ppm of the total weight of main material, Nb2O5 accounts for 100ppm~300ppm of the total weight of main material, V2O5 accounts for 100ppm~500ppm of the total weight of main material.Manganese-zinc ferrite is obtained by molding and sintering using the above granulation powder, and the D10, D50 and D90 of the internal grains of the magnetic core satisfy (D90-D10) / D50≤1.1.The initial permeability of the manganese-zinc ferrite of the application is maintained at more than 5000, while the permeability at 1MHz frequency point is maintained at more than 3000, and it also has high impedance characteristics.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of magnetic materials, and more particularly relates to a manganese-zinc ferrite granulating powder, a manganese-zinc ferrite and a preparation method and application thereof. BACKGROUND

[0002] High permeability MnZn ferrite material is an important branch of MnZn ferrite, and its main characteristic is that the initial permeability (μ i ) is high. Generally, MnZn ferrite material with an initial permeability (μ i ) of 5000 or more is referred to as high permeability MnZn ferrite. High permeability MnZn ferrite devices are usually applied in a low magnetic flux density environment, at which time the initial permeability of the material plays a major role. On the one hand, when the initial permeability of the device is high, a smaller number of winding turns can obtain an equal inductance, and the use of high permeability material can significantly reduce the size of the device. It is generally believed that the volume of a transformer is inversely proportional to the μ i 3 / 2 of the material. When the permeability is doubled, the volume of the transformer is only 35% of the original. In addition, a smaller number of winding turns can effectively reduce the line loss, which is conducive to the miniaturization, light weight and energy saving of the device.

[0003] However, with the rapid development of electronic information technology, electronic devices are increasingly integrated, high-frequency and miniaturized, and various electromagnetic interference problems are becoming increasingly serious. Simply pursuing high permeability cannot meet the requirements of electronic development, and the research on high permeability MnZn ferrite material has changed to comprehensive performance. The performance requirements for high permeability MnZn ferrite material are becoming more and more demanding. In addition to high permeability, the current high permeability MnZn ferrite is also required to have a flat μ i -f curve in a wide frequency range, so that the material can be used in a wide frequency range. At the same time, it also has a high impedance characteristic to improve the anti-electromagnetic interference capability of the material.

[0004] Although the initial permeability of the existing high permeability 5K material on the market is close to consistent, the permeability decreases rapidly with the increase of frequency. Due to the influence of inductance, the high-frequency impedance is low. With the rapid development of electronic information technology, there is an urgent need for a product with wide frequency and high permeability.

[0005] According to the search, the patent application file with the Chinese patent application number 201110230602.2 and the publication date of February 22, 2012 discloses a manufacturing method of a broadband high-manganese-zinc ferrite core. The ingredient formula in the ferrite core batching process is: Fe2O3 53.88 mol%, MnO 36.44 mol%, and ZnO 9.68 mol%. Before the granulation process, 58 ppm of TiO2, MoO3, V2O5, Bi2O3, CaCO3, SiO2, Nb2O5, SnO2, Co2O3, and CuO are added to the pre-sintered powder as additives to improve the frequency characteristics and loss characteristics of the material.

[0006] The patent application file with the Chinese patent application number 202010993430.3 and the publication date of December 29, 2020 discloses a broadband high-permeability high-impedance manganese-zinc ferrite and a preparation method thereof. The manganese-zinc ferrite includes a functional component and an auxiliary component. The functional component and the amount are: Fe2O3: 46.5-49.5 mol%, ZnO: 16.5-18.5 mol%, and the balance is MnO. The sum of the molar ratios of the three functional components is 100%. The auxiliary component is Co2O3, SiO2, CaCO3, Nb2O5, V2O5, TiO2, and SnO2.

[0007] In the above-mentioned manganese-zinc ferrite material, a large number of auxiliary additives are added to achieve high permeability, and the initial permeability can reach four to five thousand. However, the broadband permeability is not explicitly stated. The existing additives are various and can effectively improve the initial permeability, but as the frequency rises, the mechanism of multiple types of additives is complex, which often leads to a decrease in permeability.

[0008] Therefore, in order to have high permeability in a wide frequency range, it is urgent to develop a manganese-zinc ferrite granulation powder, a manganese-zinc ferrite and a preparation method and application thereof. SUMMARY

[0009] 1. Problem to be solved

[0010] One of the purposes of the present application is to provide a manganese-zinc ferrite granulation powder, which aims to optimize the formula and obtain raw materials for preparing a broadband high-magnetic permeability manganese-zinc ferrite. Another purpose of the present application is to provide a manganese-zinc ferrite, which aims to solve the problem of rapid decrease in magnetic permeability at high frequency of existing high-magnetic permeability materials. Further, a preparation method of the manganese-zinc ferrite is provided.

[0011] 2. Technical solution

[0012] In order to solve the above-mentioned problems, the technical solution adopted by the present application is as follows:

[0013] According to the purpose of the present application, the first aspect of the present application provides a Mn-Zn ferrite granulated powder, which comprises a main material and an auxiliary material, the main material is composed of an iron compound, a zinc compound and a manganese compound, the iron compound is 52-55 mol% in terms of the amount of Fe2O3, the zinc compound is 19-22 mol% in terms of the amount of ZnO, and the manganese compound is the balance in terms of the amount of MnO, and the particle size of the auxiliary material is within 100 nm, and the auxiliary material is composed of CaCO3, Co3O4, Nb2O5 and V2O5, wherein: CaCO3 accounts for 200-1000 ppm of the total weight of the main material, Co3O4 accounts for 500-2000 ppm of the total weight of the main material, Nb2O5 accounts for 100-300 ppm of the total weight of the main material, and V2O5 accounts for 100-500 ppm of the total weight of the main material.

[0014] In the above technical solution, the applicant first found the best composition of the main material in the Mn-Zn ferrite, that is, to increase the proportion of ZnO and keep the molar ratio of the iron compound and the zinc compound within the range of (52-55):(19-22), and then to add four kinds of auxiliary materials, and the particle size of the auxiliary materials is within 100 nm. On the one hand, the present application has only four kinds of auxiliary materials, and in the prior art, in order to enhance the magnetic permeability of the ferrite, more than five kinds of auxiliary materials are often added to the main material, but too many kinds of auxiliary materials will complicate the mechanism at high frequency and affect the magnetic permeability. Moreover, the addition of auxiliary materials will have a substantial effect only within a certain range, and too many kinds of auxiliary materials will either not have a significant effect due to insufficient addition of individual components, or the total addition of auxiliary materials will be excessive due to sufficient addition of individual components, which will deteriorate the performance of the ferrite. Even if the initial magnetic permeability is high, the magnetic permeability may also decrease rapidly at high frequency. On the other hand, the particle size of the auxiliary materials added in the present application is within 100 nm, because the specific surface area of the auxiliary materials is large when the particle size is within 100 nm, and the surface energy is correspondingly high. At the same time, the surface atoms of the nanoparticles have a large number of unsaturated bonds and high chemical activity, and are extremely easy to combine with other atoms to achieve a stable state. Therefore, the addition of nanometer auxiliary materials is helpful for the uniform growth of the crystal grains of the Mn-Zn ferrite material to achieve an ideal size. In addition, due to the small particle radius of the nanometer auxiliary materials, the same weight of the same impurity has a larger volume, and is more easily and uniformly dispersed in the ferrite material, which is also helpful for the uniform growth of the crystal grains. Therefore, the addition of nanometer auxiliary materials can obtain high-quality Mn-Zn ferrite materials with uniform crystal grains.

[0015] As a possible implementation scheme, the weight ratio of CaCO3, Co3O4, Nb2O5 and V2O5 in the auxiliary material is 8:16:4:3.

[0016] As a possible implementation scheme, in the main material, the molar ratio of Fe2O3 and ZnO is 21:8.

[0017] The second aspect of the application provides a preparation method of a manganese-zinc ferrite granulating powder, comprising the following steps:

[0018] S1, a batching process: after the main material and the auxiliary material are weighed according to the above-mentioned proportion, deionized water is added to the main material for primary sanding, and then spray drying is performed to obtain a spray material;

[0019] S2, a pre-burning process: the spray material is pre-burned to obtain a pre-burned material;

[0020] S3, a secondary sanding process: after the auxiliary material is added to the pre-burned material, deionized water is added for secondary sanding to obtain a secondary sanding material;

[0021] S4, a spray granulation process: the secondary sanding material is spray granulated to obtain a manganese-zinc ferrite granulating powder.

[0022] As a possible implementation scheme, in step S2, the pre-burning temperature of the pre-burning process is 800-950 DEG C, and the pre-burning time is 2-5 hours.

[0023] As a possible implementation scheme, in step S3, the time of the secondary sanding process is controlled to be 50-90 min, and the particle size distribution is controlled to be D50: 1.0-1.6 mu m.

[0024] The third aspect of the application provides a manganese-zinc ferrite, which is a formed body obtained by sintering a manganese-zinc ferrite granulating powder, wherein the manganese-zinc ferrite granulating powder comprises a main material and an auxiliary material, the main material comprises an iron compound, a zinc compound and a manganese compound, the iron compound is 52-55 mol% in terms of the amount of Fe2O3, the zinc compound is 19-22 mol% in terms of the amount of ZnO, and the manganese compound is the balance in terms of the amount of MnO, the particle size of the auxiliary material is within 100 nm, and the auxiliary material comprises CaCO3, Co3O4, Nb2O5 and V2O5, wherein: CaCO3 accounts for 200-1000 ppm of the total weight of the main material, Co3O4 accounts for 500-2000 ppm of the total weight of the main material, Nb2O5 accounts for 100-300 ppm of the total weight of the main material, and V2O5 accounts for 100-500 ppm of the total weight of the main material.

[0025] In the case of adopting the above technical scheme, the four auxiliary materials and the main material have a synergistic effect:

[0026] The melting point of Nb2O5 is 1520℃. During the sintering process in ferrite, it mainly exists in the grain boundaries. A small amount of addition can prevent the formation of large grains. The formed grains have good uniformity. Therefore, a small amount of Nb2O5 can make μ i However, when Nb2O5 is added in excess, it accumulates in the grain boundaries, which significantly reduces the grain size. With the increase of Nb2O5 addition, the grain growth is hindered and the grain size is reduced, so the magnetic domain width can be reduced, the domain wall resonance frequency can be increased, and its frequency characteristics can be improved.

[0027] CaCO3 mainly exists on the grain boundaries, thereby increasing the grain boundary resistivity. Co3O4 adjusts the magnetocrystalline anisotropy constant K1, making the material have good temperature stability and high magnetic permeability. 2+ Can inhibit Fe 2+ The combination of the two makes the material have a higher resistivity at high frequency, thereby improving the impedance at high frequency, and because the conductive electron migration of MnZn ferrite is mainly through Fe 2+ with Fe 3+ The electronic transition of Fe 2+ The resistivity of ferrite increases and the frequency characteristics will be improved to a certain extent.

[0028] As a low melting point metal oxide, V2O5 exists in liquid phase during high temperature sintering of ferrite particles. Therefore, adding an appropriate amount is beneficial to increase the contact area of ​​solid phase reaction during sintering, accelerate the reaction speed, promote grain growth, and obtain higher initial magnetic permeability. The above doping cooperates with each other and finally controls Fe by higher sintering temperature and higher oxygen content. 2+ The production of makes the material achieve broadband and high permeability performance.

[0029] Nb2O5 exists on the grain boundaries, giving the grains good uniformity, but a low-melting-point substance such as V2O5 must be added simultaneously to accelerate the reaction rate and promote grain growth. Otherwise, although the grains are uniform, they are small in size, resulting in a low initial magnetic permeability. Both CaCO3 and Co3O4 have the effect of increasing resistivity, but one increases the resistivity at the grain boundaries and the other increases the resistivity within the grains. The combination of the two makes the overall resistivity even greater, thereby maximizing the improvement in impedance at high frequencies.

[0030] As a possible implementation scheme, the lattice grain size in the manganese zinc ferrite under the measured microstate is close to uniform, that is, the average grain size distribution of the internal grains of the magnetic core is narrow, and D10, D50 and D90 of the internal grains of the magnetic core satisfy the following conditions: (D90-D10) / D50≤1.1. In the case of adopting the above technical scheme, the particle size of the added adjuvant is within 100 nm, because the specific surface area of the adjuvant is large and the surface energy is high when the particle size is within 100 nm; meanwhile, the surface atoms of the nano particles have a large number of unsaturated bonds and have high chemical activity, and are extremely easy to combine with other atoms to reach a stable state, so that the addition of the nano adjuvant helps the uniform growth of the manganese zinc ferrite material to reach an ideal size.

[0031] The fourth aspect of the present application provides a preparation method of manganese zinc ferrite, comprising the following steps:

[0032] S1, a batching process: after the main materials and adjuvants are weighed according to the above proportions, deionized water is added to the main materials for primary sanding, and the sprayed materials are obtained after spray drying;

[0033] S2, a pre-burning process: the sprayed materials are pre-burned to obtain pre-burned materials;

[0034] S3, a secondary sanding process: after the adjuvants are added to the pre-burned materials, deionized water is added for secondary sanding to obtain secondary sanding materials;

[0035] S4, a spray granulation process: the secondary sanding materials are spray granulated to obtain manganese zinc ferrite granulation powder;

[0036] S5, a forming process: the manganese zinc ferrite granulation powder is formed into a ring blank;

[0037] S6, a sintering process: the ring blank is sintered at 1300-1380℃, and the oxygen content in the atmosphere is controlled at 3-8%, thereby obtaining a wide-band high-permeability manganese zinc ferrite material.

[0038] As a possible implementation scheme, in step S2, the pre-burning temperature of the pre-burning process is 800-950℃, and the pre-burning time is 2-5 hours.

[0039] As a possible implementation scheme, in step S3, the time of the secondary sanding process is controlled at 50-90 min, and the particle size distribution is controlled at D50: 1.0-1.6 μm.

[0040] As a possible implementation scheme, in step S6, the sintering process is a segmented variable-speed temperature rising sintering, and the sintering temperature variation curve is as follows:

[0041] The temperature is raised from room temperature to 400-600℃ at a temperature rising speed of 2-4℃ / min, and the temperature is kept for 2-4h;

[0042] continuing to heat at a temperature increasing rate of 2-5℃ / min to 900-1100℃;

[0043] continuing to heat at a temperature increasing rate of 1-3℃ / min to 1300-1380℃, and keeping the temperature at 1300-1380℃ for 4-8h;

[0044] after the temperature keeping, cooling to room temperature at a rate of 2-5℃ / min.

[0045] In the case of the above technical solution, the granulated powder of the application is combined with a special sintering process, which solves the problem of too fast decrease of the magnetic permeability of the high magnetic permeability material at high frequency, realizes the wide frequency characteristics, and due to the improvement of the magnetic permeability at high frequency, the impedance characteristics are also improved, so that the material has stronger anti-electromagnetic interference ability. That is, the initial magnetic permeability of the manganese zinc ferrite obtained by the application is >5000, the 1MHz magnetic permeability is >3000, and the impedance Z of the T25 / 15 / 12 sample ring at 1MHz is >42Ω.

[0046] The fifth aspect of the application provides an application of the manganese zinc ferrite, which is used for preparing a power common mode electromagnetic interference (EMI) filter, a broadband transformer and an inductive magnetic core of a digital communication system, and plays a good signal conversion and transmission role.

[0047] 3. Beneficial effects

[0048] Compared with the prior art, the beneficial effects of the application are:

[0049] The manganese zinc ferrite of the application keeps the initial magnetic permeability above 5000, the magnetic permeability at 1MHz frequency point above 3000, and also has high impedance characteristics (the impedance Z of the T25 / 15 / 12 sample ring at 1MHz is >42Ω), so that it has good anti-electromagnetic interference ability in a wider frequency range. DETAILED DESCRIPTION

[0050] The application will be further described below in combination with specific embodiments.

[0051] Example 1

[0052] The manganese zinc ferrite of the embodiment comprises main materials and auxiliary materials, the composition of the main materials is iron compound, zinc compound and manganese compound, the iron compound is 52.5 mol% in terms of the amount of Fe2O3, the zinc compound is 20 mol% in terms of the amount of ZnO, and the manganese compound is the balance in terms of the amount of MnO, the particle size of the auxiliary materials is within 100 nm, and the composition of the auxiliary materials comprises CaCO3, Co3O4, Nb2O5 and V2O5, wherein: CaCO3 accounts for 400 ppm of the total weight of the main materials, Co3O4 accounts for 800 ppm of the total weight of the main materials, Nb2O5 accounts for 200 ppm of the total weight of the main materials, and V2O5 accounts for 150 ppm of the total weight of the main materials.

[0053] The preparation method of the manganese zinc ferrite granulating powder of the embodiment comprises the following steps:

[0054] S1, a batching process: after the main materials and auxiliary materials are weighed according to the above proportions, deionized water is added to the main materials for primary sanding, and the sprayed materials are obtained after spray drying;

[0055] S2, a pre-burning process: the sprayed materials are pre-burned, the pre-burning temperature is 800-950℃, the pre-burning time is 2-5 hours, and the pre-burned materials are obtained;

[0056] S3, a secondary sanding process: after the auxiliary materials are added to the pre-burned materials, deionized water is added for secondary sanding, the time is controlled to be 50-90 min, the particle size distribution is controlled to be D50: 1.0-1.6 μm, and the secondary sanded materials are obtained;

[0057] S4, a spray granulation process: the secondary sanded materials are spray granulated to obtain the manganese zinc ferrite granulating powder;

[0058] S5, a forming process: the manganese zinc ferrite granulating powder is formed into a ring blank;

[0059] S6, a sintering process: the ring blank is sintered at 1380℃, the oxygen content of the atmosphere is controlled to be 4.5%, and the manganese zinc ferrite material with wide frequency and high magnetic permeability of the embodiment is obtained.

[0060] In the sintering process of step S6 of the embodiment, the sintering is performed by segmented variable-speed temperature rising, and the sintering temperature change curve is as follows:

[0061] The temperature is raised from room temperature to 500℃ at a temperature rising speed of 3℃ / min, and the temperature is kept for 3h;

[0062] The temperature is continuously raised to 1000℃ at a temperature rising speed of 4℃ / min;

[0063] The temperature is continuously raised to 1380℃ at a temperature rising speed of 2℃ / min, and the temperature is kept for 6h at 1380℃;

[0064] After the heat preservation is finished, cool to room temperature at a rate of 3℃ / min.

[0065] Example 2

[0066] The manganese zinc ferrite of the embodiment comprises a main material and an auxiliary material, the main material is composed of an iron compound, a zinc compound and a manganese compound, the iron compound is 54 mol% in terms of the amount of Fe2O3, the zinc compound is 20 mol% in terms of the amount of ZnO, and the manganese compound is the balance in terms of the amount of MnO, the particle size of the auxiliary material is within 100 nm, and the composition comprises CaCO3, Co3O4, Nb2O5 and V2O5, wherein: CaCO3 accounts for 400 ppm of the total weight of the main material, Co3O4 accounts for 800 ppm of the total weight of the main material, Nb2O5 accounts for 200 ppm of the total weight of the main material, and V2O5 accounts for 150 ppm of the total weight of the main material.

[0067] The preparation method of the manganese zinc ferrite granulating powder of the embodiment comprises the following steps:

[0068] S1, a batching process: after the main material and the auxiliary material are weighed according to the above proportions, deionized water is added to the main material for primary sanding, and the sprayed material is obtained after spray drying;

[0069] S2, a pre-burning process: the sprayed material is pre-burned, the pre-burning temperature is 800-950℃, the pre-burning time is 2-5 hours, and the pre-burned material is obtained;

[0070] S3, a secondary sanding process: after the auxiliary material is added to the pre-burned material, deionized water is added for secondary sanding, the time is controlled to be 50-90 min, the particle size distribution is controlled to be D50: 1.0-1.6 μm, and the secondary sanding material is obtained;

[0071] S4, a spray granulation process: the secondary sanding material is spray granulated to obtain the manganese zinc ferrite granulating powder;

[0072] S5, a forming process: the manganese zinc ferrite granulating powder is formed into a ring blank;

[0073] S6, a sintering process: the ring blank is sintered at 1370℃, the oxygen content of the atmosphere is controlled to be 4.5%, and the manganese zinc ferrite material with wide frequency and high magnetic permeability of the embodiment is obtained.

[0074] In the sintering process of step S6 of the embodiment, the sintering is performed by segmented variable-speed heating, and the sintering temperature change curve is as follows:

[0075] The temperature is raised from room temperature to 500℃ at a rate of 3℃ / min, and the temperature is kept for 3h;

[0076] The temperature is continuously raised to 1000℃ at a rate of 4℃ / min;

[0077] Continuing to increase the temperature to 1370℃ at a temperature increasing rate of 2℃ / min, and keeping the temperature at 1370℃ for 6h;

[0078] After the keeping temperature, cooling to room temperature at a rate of 3℃ / min.

[0079] Embodiment 3

[0080] The manganese zinc ferrite of the embodiment comprises a main material and an auxiliary material, the main material is composed of an iron compound, a zinc compound and a manganese compound, the iron compound is 52mol% in terms of the amount of Fe2O3, the zinc compound is 22mol% in terms of the amount of ZnO, and the manganese compound is the balance in terms of the amount of MnO, the particle size of the auxiliary material is within 100nm, and the composition comprises CaCO3, Co3O4, Nb2O5 and V2O5, wherein: CaCO3 accounts for 400ppm of the total weight of the main material, Co3O4 accounts for 800ppm of the total weight of the main material, Nb2O5 accounts for 200ppm of the total weight of the main material, and V2O5 accounts for 150ppm of the total weight of the main material.

[0081] The preparation method of the manganese zinc ferrite granulating powder of the embodiment comprises the following steps:

[0082] S1, a batching process: after the main material and the auxiliary material are weighed according to the above proportions, deionized water is added to the main material for primary sanding, and the sprayed material is obtained after spray drying;

[0083] S2, a pre-burning process: the sprayed material is pre-burned, the pre-burning temperature is 800-950℃, the pre-burning time is 2-5 hours, and the pre-burned material is obtained;

[0084] S3, a secondary sanding process: after the auxiliary material is added to the pre-burned material, deionized water is added for secondary sanding, the time is controlled to be 50-90min, the particle size distribution is controlled to be D50: 1.0-1.6μm, and the secondary sanding material is obtained;

[0085] S4, a spray granulation process: the secondary sanding material is spray granulated to obtain the manganese zinc ferrite granulating powder;

[0086] S5, a forming process: the manganese zinc ferrite granulating powder is formed into a ring blank;

[0087] S6, a sintering process: the ring blank is sintered at 1370℃, the oxygen content of the atmosphere is controlled to be 4.5%, and the manganese zinc ferrite material with wide frequency and high magnetic permeability of the embodiment is obtained.

[0088] In the sintering process of step S6 of the embodiment, the sintering is a segmented variable-speed sintering, and the sintering temperature change curve is as follows:

[0089] Increasing the temperature from room temperature to 500℃ at a temperature increasing rate of 3℃ / min, and keeping the temperature for 3h;

[0090] Continue to increase the temperature to 1000℃ at a temperature increasing rate of 4℃ / min;

[0091] Continue to increase the temperature to 1370℃ at a temperature increasing rate of 2℃ / min, and keep the temperature at 1370℃ for 6h;

[0092] After the end of the temperature keeping, cool to room temperature at a rate of 3℃ / min.

[0093] Example 4

[0094] The manganese zinc ferrite of the present example comprises a main material and an auxiliary material, the main material is composed of an iron compound, a zinc compound and a manganese compound, the iron compound is 52.5mol% in terms of the amount of Fe2O3, the zinc compound is 20mol% in terms of the amount of ZnO, and the manganese compound is the balance in terms of the amount of MnO, the particle size of the auxiliary material is within 100nm, and the composition comprises CaCO3, Co3O4, Nb2O5 and V2O5, wherein: CaCO3 accounts for 400ppm of the total weight of the main material, Co3O4 accounts for 800ppm of the total weight of the main material, Nb2O5 accounts for 200ppm of the total weight of the main material, and V2O5 accounts for 150ppm of the total weight of the main material.

[0095] The preparation method of the manganese zinc ferrite granulating powder of the present example comprises the following steps:

[0096] S1, a batching process: after the main material and the auxiliary material are weighed according to the above proportions, deionized water is added to the main material for primary sanding, and the sprayed material is obtained after spray drying;

[0097] S2, a pre-burning process: the sprayed material is pre-burned, the pre-burning temperature is 800-950℃, and the pre-burning time is 2-5 hours, and the pre-burned material is obtained;

[0098] S3, a secondary sanding process: after the auxiliary material is added to the pre-burned material, deionized water is added for secondary sanding, the time is controlled to be 50-90min, the particle size distribution is controlled to be D50: 1.0-1.6μm, and the secondary sanding material is obtained;

[0099] S4, a spray granulation process: the secondary sanding material is spray granulated to obtain the manganese zinc ferrite granulating powder;

[0100] S5, a forming process: the manganese zinc ferrite granulating powder is formed into a ring blank;

[0101] S6, a sintering process: the ring blank is sintered at 1370℃, and the oxygen content of the atmosphere is controlled to be 3.1%, and the manganese zinc ferrite material with wide frequency and high magnetic permeability of the present example is obtained.

[0102] In the sintering process of step S6 of the present example, the sintering is a segmented variable speed increasing sintering, and the sintering temperature change curve is as follows:

[0103] Ramp up from room temperature to 500°C at a rate of 3°C / min, hold for 3h;

[0104] Continue to ramp up to 1000°C at a rate of 4°C / min;

[0105] Continue to ramp up to 1370°C at a rate of 2°C / min, hold for 6h at 1370°C;

[0106] After the holding, cool down to room temperature at a rate of 3°C / min.

[0107] Example 5

[0108] This example is basically the same as Example 1, except that in step S6, the sintering process is constant speed sintering, i.e. ramp up from room temperature to 1380°C at a rate of 2°C / min, hold for 6h at 1380°C, which is not conducive to glue removal and densification.

[0109] Comparative Example 1

[0110] This comparative example is basically the same as Example 1, except that Nb2O5 accounts for 400ppm of the total weight of the main material.

[0111] Comparative Example 2

[0112] This comparative example is basically the same as Example 1, except that it does not contain CaCO3.

[0113] Comparative Example 3

[0114] This comparative example is basically the same as Example 1, except that it does not contain Co3O4.

[0115] Comparative Example 4

[0116] This comparative example is basically the same as Example 1, except that it does not contain V2O5.

[0117] Comparative Example 5

[0118] This comparative example is basically the same as Example 1, except that in S6, the sintering process is as follows: the ring blank is sintered at 1390°C, and in the segmented variable speed sintering, the sintering temperature curve is as follows:

[0119] Ramp up from room temperature to 500°C at a rate of 3°C / min, hold for 3h;

[0120] Continue to ramp up to 1000°C at a rate of 4°C / min;

[0121] Continue to ramp up to 1390°C at a rate of 2°C / min, hold for 6h at 1390°C;

[0122] After the heat preservation, cool down to room temperature at a rate of 3℃ / min.

[0123] In the present comparative example, the sintering temperature is increased, but the frequency characteristics are insufficient.

[0124] Comparative Example 6

[0125] The present comparative example is basically the same as Example 1, except that S6, the sintering process is performed in a nitrogen atmosphere at 1370℃.

[0126] The magnetic permeability and impedance of the manganese-zinc ferrite material obtained in each example and comparative example at a wide frequency are shown in Table 1:

[0127] Table 1: Performance test of manganese-zinc ferrite obtained in each example and comparative example

[0128]

[0129] As can be seen from Table 1, the initial magnetic permeability of Examples 1-5 is greater than 5000, and as the frequency increases, the magnetic permeability at 1MHz can still reach more than 3000, and the impedance Z of the sample ring T25 / 15 / 12 at 1MHz is greater than 42Ω; in Comparative Example 1, the content of Nb2O5 is higher than 200ppm of the total weight of the main material, and in Comparative Examples 2 / 3 / 4, CaCO3, Co3O4 and V2O5 are respectively absent, although the initial magnetic permeability is higher than 5000, the magnetic permeability at 1MHz is lower than 3000, and in Comparative Example 5, the holding temperature in the sintering process is increased by 10℃ compared with Example 1, although the initial magnetic permeability is high, the magnetic permeability at 1MHz is lower than 3000; in Comparative Example 6, no oxygen atmosphere is contained, the magnetic permeability and impedance are relatively low, and the distribution of the ferrite internal lattice size in the comparative example is relatively wide, which affects the magnetic permeability and impedance performance.

[0130] The raw materials and equipment used in the present application are conventional raw materials and equipment in the art unless otherwise specified; the methods used in the present application are conventional methods in the art unless otherwise specified. The above is only a preferred embodiment of the present application, and does not limit the present application in any way, any simple modification, change and equivalent transformation of the above embodiment according to the technical essence of the present application are still within the protection scope of the technical solution of the present application.

Claims

1. A method for preparing manganese-zinc ferrite, characterized in that: A manganese-zinc ferrite material is obtained by subjecting manganese-zinc ferrite granulated powder to a molding process and a sintering process. The manganese-zinc ferrite granulated powder includes a main material and an auxiliary material. The main material is composed of an iron compound, a zinc compound and a manganese compound, wherein the iron compound is 52-55 mol% in terms of Fe2O3 conversion, the zinc compound is 19-22 mol% in terms of ZnO conversion, and the manganese compound is the balance in terms of MnO conversion. The particle size of the auxiliary material is within 100 nm, and the auxiliary material comprises four kinds of materials: CaCO3, Co3O4, Nb2O5 and V2O5, wherein: CaCO3 accounts for 400 ppm of the total weight of the main material, Co3O4 accounts for 800 ppm of the total weight of the main material, Nb2O5 accounts for 200 ppm of the total weight of the main material, and V2O5 accounts for 150 ppm of the total weight of the main material; wherein: The sintering process is as follows: the formed granulated powder is sintered at 1300℃~1380℃, wherein the oxygen content of the atmosphere is controlled at 3%~8%; the sintering process is sintering in a staged variable speed heating process, and the sintering temperature change curve is as follows: Heat the sample from room temperature to 400-600°C at a rate of 2-4°C / min and keep the temperature for 2-4 hours. Continue heating at a rate of 2 to 5°C / min to 900 to 1100°C; Continue heating at a rate of 1-3°C / min to 1300-1380°C, and keep at 1300-1380°C for 4-8 hours; After the insulation is completed, cool to room temperature at a rate of 2~5℃ / min.

2. The method for preparing manganese-zinc ferrite according to claim 1, wherein: In the main material, the molar ratio of Fe2O3 and ZnO is 21:

8.

3. The method for preparing manganese-zinc ferrite according to claim 1 or 2, wherein: The preparation method of the manganese zinc ferrite granulated powder comprises the following steps: S1, batching process: add deionized water to the main material and perform sand grinding, and then spray dry to obtain the spray material; S2, pre-burning process: pre-burning the sprayed material to obtain pre-burned material; S3, secondary sand grinding process: after adding auxiliary materials to the pre-burned material, add deionized water for secondary sand grinding to obtain secondary sand abrasive; S4, spray granulation process: spray granulate the secondary sand abrasive to obtain manganese zinc ferrite granulated powder.

4. The method for preparing manganese-zinc ferrite according to claim 3, wherein: In step S2, the pre-firing temperature of the pre-firing process is 800-950° C., and the pre-firing time is 2-5 hours.

5. The method for preparing manganese-zinc ferrite according to claim 3, wherein: In step S3, the time of the secondary sand grinding process is controlled within 50 min to 90 min, and the particle size distribution is controlled within D50: 1.0 μm to 1.6 μm.

6. A manganese-zinc ferrite, characterized in that: Manganese zinc ferrite obtained by the preparation method according to any one of claims 1 to 5.

7. The manganese-zinc ferrite according to claim 6, characterized in that: The D10, D50 and D90 of the internal grains of manganese-zinc ferrite meet the following conditions: (D90-D10) / D50≤1.

1.

8. Use of the manganese-zinc ferrite according to claim 6 or 7 in preparing filters, broadband transformers, and inductor cores.

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