Ferrite material as well as preparation method and application thereof

Abstract

The invention relates to a ferrite material as well as a preparation method and application thereof, and belongs to the technical field of laminated soft magnetic ferrite inductors / magnetic beads. The ferrite material comprises a main component and an additive accounting for 1.0 wt%-2.5 wt% of the mass of the main component, the main component is prepared from the following components in percentage by mass: 64.56 percent to 66.48 percent of Fe2O3, 14.85 percent to 17.50 percent of NiO, 10.93 percent to 11.93 percent of ZnO and 5.09 percent to 8.10 percent of CuO; the chemical formula of the additive is M1-xFe2O4, and x < lt > is greater than or equal to 0; m is at least one of Li, Mg, Ti, Sr, Mo, Bi and Fe. The additive is a spinel phase, and the high-purity spinel phase ferrite material is obtained by mixing and co-firing the additive of the spinel phase and the main component of the spinel phase.

Description

Technical Field

[0001] The present invention belongs to the technical field of laminated soft ferrite inductors / ferrite beads, and particularly relates to a ferrite material, a preparation method thereof and an application thereof. Background Art

[0002] The automotive industry is developing towards electrification, networking, intelligence and sharing, and the complexity and functional iterative upgrade requirements of automotive electronic systems are increasing day by day. In a power supply system mainly composed of a DC / DC converter, an inductor that plays a role in energy storage and filtering is one of the key components, which affects the reliability and stability of the power supply system. It is crucial to select a high-quality and highly reliable inductor / ferrite bead for vehicle use.

[0003] Preparing high-performance ferrite materials is the key to preparing laminated inductors / ferrite beads. The following common problems need to be solved urgently: material component design, crystal structure design, powder property control, the dosage and action mechanism of additive components, and the correlation regulation of indexes such as magnetic permeability, quality factor and temperature coefficient. At present, in order to reduce the sintering temperature and / or improve the magnetoelectric properties of ferrite materials, domestic and foreign technologies mostly adopt adding crystalline (or amorphous) doping compounds or fluxes. The adding method is mostly added at the initial stage of the main component mixing and ball milling or added before the material is sintered after the main component is calcined. The former method is likely to cause segregation of the chemical composition / phase composition of trace or small amounts of additives, and the latter method is likely to cause additive elements to be difficult to enter the spinel lattice and aggregate in the form of glass phase at grain boundaries, pores or defects, etc. Both will cause more or less deterioration of the material properties.

[0004] Therefore, it is of great significance to provide a ferrite material with high reliability and consistency. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the above non-spinel raw material direct incorporation and non-uniform phase formation technology, and provide a ferrite material, a preparation method thereof and an application thereof.

[0006] The present invention is realized through the following technical solutions:

[0007] In the first aspect, the present invention provides a ferrite material, which includes a main component and an additive accounting for 1.0 wt% - 2.5 wt% of the mass of the main component; the main component includes the following components in mass percentage: 64.56% - 66.48% of Fe2O3, 14.85% - 17.50% of NiO, 10.93% - 11.93% of ZnO, 5.09% - 8.10% of CuO; the chemical formula of the additive is M 1-x Fe2O4, where 0 ≤ x < 1, and M is at least one of Li, Mg, Ti, Sr, Mo, Bi and Fe.

[0008] The additive of the present invention is a spinel phase. By co-firing the additive of the spinel phase with the main components of the spinel phase, a high-purity spinel ferrite material is obtained. This method is conducive to adjusting the concentrations of A-site and B-site of the spinel, the molecular magnetic moment, and the ratio of normal / inverse spinel, thereby regulating the super-exchange interaction between A and B sites; it is conducive to the tailored design and standardized production according to the material properties. The ferrite material manufactured thereby meets the requirements of high-performance magnetic components for high-frequency decoupling / choking, low-frequency filtering, and eliminating electromagnetic interference / compatibility (EMI / EMC) noise.

[0009] Preferably, the additive is at least one of (Li 0.2 Fe 0.9 )Fe2O4, MgFe2O4, (Fe)[TiFe]O4, SrFe2O4, (Fe)[MoFe]O4, (Fe)[BiFe]O4, (Li 0.6 Fe)[Ti 0.6 Fe]O4, and (Fe)[Ti 0.5 Mg 0.5 Fe]O4.

[0010] In the chemical formulas of the above additives, the round brackets and square brackets represent the tetrahedral and octahedral positions of the spinel phase respectively.

[0011] Preferably, the additive is obtained by calcining a mixture of an oxide of element M and an iron oxide.

[0012] Specifically, the oxide of element M is Li2O, MgO, TiO2, SrO, MoO3, Bi2O3, Fe2O3; the iron oxide is Fe2O3.

[0013] The present invention can obtain a spinel phase additive by calcining a mixture of an oxide of element M and an iron oxide, and can obtain a high-purity ferrite material after co-firing with the main components.

[0014] In a second aspect, the present invention provides a method for preparing the ferrite material, comprising the following steps:

[0015] (1) Mix the components in the main components, ball mill, dry, and calcine to obtain magnetic powder; mix the oxide of element M and the iron oxide, ball mill, dry, and calcine to obtain an additive;

[0016] (2) Mix the magnetic powder and the additive obtained in step (1), ball mill, and sand mill to obtain a mixed magnetic powder;

[0017] (3) Mix the mixed magnetic powder obtained in step (2) with a binder and water, granulate, mold, and sinter to obtain the ferrite material.

[0018] The preparation method of the present invention obtains a high-purity ferrite material by separately synthesizing the spinel-phase preforms of the main component and the additive and then mixing and co-firing them.

[0019] Preferably, in the step (1), when ball milling, water is added for ball milling, and the mass ratio of the material (the material refers to the total raw materials) to water is 1:(0.8 - 2); more preferably, the mass ratio of the material to water is 1:1.5.

[0020] Preferably, in the step (1), the rotation speed of the ball milling is 100 rpm - 200 rpm, and the time is 10 h - 40 h; more preferably, the rotation speed of the ball milling is 150 rpm, and the time is 30 h.

[0021] Preferably, in the step (1), the drying temperature is 110°C - 200°C, and the time is 20 h - 30 h.

[0022] Preferably, in the step (1), the calcination temperature is 750°C - 810°C, and the time is 2 h - 4 h; more preferably, the calcination temperature is 770°C - 790°C, and the time is 2 h - 3 h.

[0023] Preferably, in the step (2), the rotation speed of the ball milling is 100 rpm - 200 rpm, and the time is 1 h - 10 h; more preferably, the rotation speed of the ball milling is 150 rpm, and the time is 4 h.

[0024] Preferably, in the step (2), the rotation speed of the sand milling is 500 rpm - 1000 rpm, and the time is 8 h - 24 h; more preferably, the rotation speed of the sand milling is 600 rpm, and the time is 12 h.

[0025] Preferably, in the step (3), the binder is a conventional resin binder in the electronic ceramics industry.

[0026] The present invention does not limit the type and addition amount of the resin binder, and any binder commonly used in the field can be used in the present invention. Preferably, the addition amount of the binder is 7% - 10% based on the mass percentage of the mixed magnetic powder.

[0027] Preferably, in the step (3), granulation is carried out using a granulator or a spray dryer, both of which are common equipment in the electronic ceramics industry. Preferably, the water addition amount during spray granulation is 35% - 40% based on the mass percentage of the suspension, that is, the solid content is 60% - 65% based on the mass percentage.

[0028] Preferably, in the step (3), the molding pressure is 260 MPa - 320 MPa, and the pressure holding time is 30 s - 60 s; more preferably, the molding pressure is 280 MPa - 300 MPa, and the pressure holding time is 30 s - 45 s.

[0029] Preferably, in the step (3), the sintering temperature is 885°C - 920°C, and the time is 1h - 3h; more preferably, the sintering temperature is 890°C - 915°C, and the time is 2h - 2.5h.

[0030] Preferably, in the step (3), the heating rate of the sintering is 1°C / min - 5°C / min, and the cooling rate is 1°C / min - 5°C / min; more preferably, the heating rate of the sintering is 2°C / min, and the cooling rate is 2°C / min.

[0031] In a third aspect, the present invention provides the application of the ferrite material in magnetic components.

[0032] The ferrite material of the present invention has a pure-phase spinel structure and meets the requirements of high-performance magnetic components for high-frequency decoupling / choking, low-frequency filtering, and eliminating electromagnetic interference / compatibility (EMI / EMC) noise. Preferably, the magnetic components include at least one of chip multilayer inductor devices, filters, pulse voltage transformers, magnetic saturation amplifiers, intermediate frequency transformers, and chokes.

[0033] The present invention has the following beneficial effects: aiming at a pure-phase formula and a pure-phase polycrystalline structure, the present invention regards non-spinel phases, glass phases (amorphous phases), and glass-ceramic phases as impurity phases. By separately synthesizing spinel-phase preforms of the main components and additives and co-firing them, a high-purity spinel-phase ferrite material is obtained. At the same time, in the preparation process, hierarchical ball milling, precise control of calcination and sintering are used to effectively control the grain size and distribution, and the microstructure such as inside the grains and at the grain boundaries. A structurally stable continuous solid solution, that is, a pure-phase mixed (normal / inverse) spinel polycrystal (ceramic), is prepared to eliminate all possible impurity phases, and give full play to the crystallographic advantages of normal and inverse spinels respectively, so as to achieve the purpose of regulating the magnetoelectric properties and improving the reliability and consistency. Detailed embodiments

[0034] To better illustrate the purpose, technical solutions, and advantages of the present invention, the present invention will be further described below with reference to specific embodiments. Those skilled in the art should understand that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0035] Unless otherwise specified, the test methods used in the examples are all conventional methods; the materials, reagents, etc. used, unless otherwise specified, can all be obtained from commercial channels.

[0036] Examples 1 - 21

[0037] The composition of the ferrite material described in the embodiments of the present invention is shown in Table 1.

[0038] Comparative Examples 1-8

[0039] The differences between Comparative Examples 1-8 and the Examples lie only in the types and dosages of the additive components, as shown in Table 1.

[0040] The preparation methods of the ferrite materials in the Examples and Comparative Examples include the following steps:

[0041] (1) Mix the components in the main components according to the formula shown in Table 1, ball mill, dry, and calcine to obtain magnetic powder; in the Examples, mix the oxide of the corresponding M element with Fe2O3 according to the chemical formula of the additive shown in Table 1, ball mill, dry, and calcine to obtain the additive; the phase composition of the additive is as shown in Table 1; the additive in the Comparative Examples is the oxide of the chemical formula shown in Table 1;

[0042] (2) Mix the magnetic powder and the additive obtained in step (1), ball mill and sand mill to obtain mixed magnetic powder; the mass percentage of the additive in the main components is as shown in Table 1;

[0043] (3) Mix the mixed magnetic powder obtained in step (2) with a binder and water, granulate, mold, and sinter to obtain the ferrite material;

[0044] In step (1), the mass ratio of the material to water during ball milling is 1:1.5, the rotation speed of the ball milling is 150 rpm, and the time is 30 h; the drying temperature is 150 °C and the time is 25 h; the calcination temperature is 780 °C and the time is 2.5 h;

[0045] In step (2), the rotation speed of the ball milling is 150 rpm and the time is 4 h; the rotation speed of the sand milling is 600 rpm and the time is 12 h;

[0046] In step (3), the binder is a resin binder, and the addition amount is 8% based on the mass percentage of the mixed magnetic powder; the molding pressure is 290 MPa and the pressure holding time is 40 s; the sintering temperature is as shown in Table 1 and the time is 2 h; the heating rate of the sintering is 2 °C / min and the cooling rate is 2 °C / min.

[0047] In the components of each Example and Comparative Example in Table 1,

[0048] The formula I of the main components includes the following components by mass percentage: 65.85% of Fe2O3, 14.85% of NiO, 11.50% of ZnO, 7.80% of CuO;

[0049] The formula II of the main components includes the following components by mass percentage: 64.56% of Fe2O3, 15.41% of NiO, 11.93% of ZnO, 8.10% of CuO;

[0050] The formula III of the main component includes the following components by mass percentage: 66.48% of Fe2O3, 17.50% of NiO, 10.93% of ZnO, and 5.09% of CuO.

[0051] Among them, formula II is obtained by reducing the Fe content of formula I, and formula III is obtained by increasing the Fe content of formula I.

[0052] In addition, the main component formulas I-III without adding additives are used as the blank group for comparison.

[0053] Table 1 Composition of ferrite materials in examples and comparative examples

[0054]

[0055]

[0056] The ferrite materials prepared in each example and comparative example are subjected to performance tests. The test results are shown in Table 2, where the relative permeability μ, quality factor Q, impedance |Z| (Ω), and Curie temperature T c (°C) are measured according to GB / Z 28870-2012 "Measurement Methods for Soft Magnetic Ferrite Materials for Electromagnetic Interference Suppression".

[0057] Table 2 Performance test results of ferrite materials in examples and comparative examples

[0058]

[0059] It can be seen from Table 2 that the introduction of the additive of the present invention can effectively regulate the performance of the ferrite material.

[0060] In Examples 1-7, the permeability μ of the prepared ferrite material is 92.79-154.81 (4 MHz), the quality factor Q is 100-145 (1 MHz), the impedance |Z| is 32.69-57.80 Ω (1 MHz) / 112.3-200.4 Ω (4 MHz), and the Curie temperature T c has little difference and fluctuates during the same series of tests, and is 280-330 °C. Compared with the blank group 1, the permeability, quality factor, and impedance of the samples with the additive introduced (Examples 1-7) are regulated according to the type and dosage of the additive.

[0061] In Examples 8-14, the permeability μ of the prepared ferrite material is 91.98-143.50 (4 MHz), the quality factor Q is 111-160 (1 MHz), the impedance |Z| is 33.88-56.10 Ω (1 MHz) / 109.6-197.0 Ω (4 MHz), and the Curie temperature T cIt is 300 to 350 °C. Compared with the blank group 2, for the samples with additives introduced (Examples 8 - 14), their magnetic permeability, quality factor, and impedance are regulated according to the type and dosage of the additives.

[0062] In Examples 15 - 21, the magnetic permeability μ of the prepared ferrite materials is 77.59 to 161.91 (4 MHz), the quality factor Q is 108 to 180 (1 MHz), the impedance |Z| is 33.46 to 92.44 Ω (1 MHz) / 111.6 to 190.1 Ω (4 MHz), and the Curie temperature T c is 270 to 320 °C. Compared with the blank group 3, for the samples with additives introduced (Examples 15 - 21), their magnetic permeability, quality factor, and impedance are regulated according to the type and dosage of the additives.

[0063] In Comparative Examples 1, 4, and 5, the additives Li2O, SrO, and MoO3 with non - spinel structures are difficult to dissolve in the components of the main component formula II, and their inductance characteristics are very poor, making it impossible to conduct performance tests.

[0064] In Comparative Examples 2, 3, 6 - 8, the magnetic permeability μ of the prepared ferrite materials is 25.70 to 73.48 (4 MHz), the quality factor Q is 75 to 180 (1 MHz), and the impedance |Z| is 10.16 to 30.90 Ω (1 MHz) / 34.05 to 102.1 Ω (4 MHz). Compared with Examples 1 - 21, both the magnetic permeability μ and the impedance |Z| in the comparative examples are too low.

[0065] Finally, it should be noted that the above - mentioned examples are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A ferrite material, characterized in that, It includes a main component and an additive accounting for 1.0 wt% to 2.5 wt% of the mass of the main component; the main component includes the following components by mass percentage: 64.56% - 66.48% of Fe2O3, 14.85% - 17.50% of NiO, 10.93% - 11.93% of ZnO, 5.09% - 8.10% of CuO; the chemical formula of the additive is M 1-x Fe2O4, where 0 ≤ x < 1, and M is at least one of Li, Mg, Ti, Sr, Mo, Bi, and Fe.

2. The ferrite material according to claim 1, wherein The additive is (Li 0.2 Fe 0.9 )Fe2O4, MgFe2O4, (Fe)[TiFe]O4, SrFe2O4, (Fe)[MoFe]O4, (Fe)[BiFe]O4, (Li 0.6 Fe)[Ti 0.6 Fe]O4, and (Fe)[Ti 0.5 Mg 0.5 Fe]O4, or at least one of them.

3. The ferrite material according to claim 1, characterized in that, The additive is obtained by mixing and calcining the oxide of M element and iron oxide.

4. The preparation method of the ferrite material according to any one of claims 1-3, characterized in that, It includes the following steps: (1) Mix the components in the main component, ball mill, dry, and calcine to obtain magnetic powder; mix the oxide of M element and iron oxide, ball mill, dry, and calcine to obtain an additive; (2) Mix the magnetic powder and the additive obtained in step (1), ball mill, and sand mill to obtain a mixed magnetic powder; (3) Mix the mixed magnetic powder obtained in step (2) with a binder and water, granulate, mold, and sinter to obtain the ferrite material.

5. The preparation method of the ferrite material according to claim 4, characterized in that, In step (1), the calcination temperature is 750°C - 810°C, and the time is 2h - 4h.

6. The preparation method of the ferrite material according to claim 4, characterized in that, In step (1), the rotation speed of the ball milling is 100rpm - 200rpm, and the time is 10h - 40h; and / or, the drying temperature is 110°C - 200°C, and the time is 20h - 30h.

7. The preparation method of the ferrite material according to claim 4, characterized in that, In step (2), the rotation speed of the ball milling is 100rpm - 200rpm, and the time is 1h - 10h; and / or, in step (2), the rotation speed of the sand milling is 500rpm - 1000rpm, and the time is 8h - 24h.

8. The preparation method of the ferrite material according to claim 4, characterized in that, In step (3), the sintering temperature is 885°C - 920°C, and the time is 1h - 3h.

9. The preparation method of the ferrite material according to claim 4, characterized in that, In step (3), the binder is a resin binder; and / or, the addition amount of the binder is 7% - 10% based on the mass percentage of the mixed magnetic powder; and / or, the molding pressure is 260MPa - 320MPa, and the pressure holding time is 30s - 60s; and / or, the heating rate of the sintering is 1°C / min - 5°C / min, and the cooling rate is 1°C / min - 5°C / min.

10. Application of the ferrite material according to any one of claims 1 - 3 and the ferrite material prepared by the preparation method of the ferrite material according to any one of claims 4 - 9 in magnetic components.

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