Wide-temperature high-direct-current superposition manganese zinc ferrite soft magnetic material and preparation method thereof

Abstract

The invention belongs to the field of soft magnetic ferrite materials, and discloses a wide-temperature high-direct-current superposition manganese zinc ferrite soft magnetic material and a preparation method thereof.The material comprises a main formula and a small formula, and the main formula comprises Fe2O3, MnO and the balance ZnO; and the small formula comprises TiO2, CaCO3, Nb2O5 and SiO2. The method comprises the following steps: (1) weighing the main formula, mixing and pre-sintering to obtain a pre-sintered material; (2) coarsely crushing the pre-sintered material, adding a small formula, sanding, adding a binder, and carrying out spray granulation to obtain a granular material; and (3) sintering the granules in a mixed atmosphere of nitrogen and oxygen to obtain the wide-temperature high-direct-current superimposed manganese zinc ferrite soft magnetic material. According to the invention, the problem of low inductance of the soft magnetic manganese zinc ferrite in high-temperature and low-temperature environments under large-current superposition is solved, and the charging efficiency of a charger is improved.

Description

Technical Field

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

[0002] High DC superposition manganese-zinc ferrite, due to its high saturation magnetic flux density and excellent DC superposition characteristics, is suitable for maintaining stable inductance even under high current operating environments. With the development of new energy vehicle technology, the market share of new energy vehicles has exceeded half. The on-board charger for new energy vehicles, a fixed charger on the electric vehicle, has the following main functions: 220V AC power is filtered to eliminate interference, rectified to 310V DC power by an AC-DC converter, then initially boosted by a power factor correction circuit, further boosted by a switching transformer, and finally rectified and filtered again by an LLC resonant converter to output high-voltage DC power suitable for the battery. High DC superposition manganese-zinc ferrite plays a crucial role in voltage transformation and energy storage in the EMI filtering, AC-DC converter, and LLC resonant converter of the new energy vehicle on-board charger.

[0003] As new energy vehicles develop towards longer range and faster charging, on-board chargers, as key components, will continue to undergo technological innovation. The ability of high DC-DC coupled manganese-zinc ferrite batteries to maintain stable inductance under DC bias over a wide temperature range will provide crucial support for performance improvement. Currently, DC-DC coupled manganese-zinc ferrite batteries suffer from significant inductance drops at low and high temperatures under high current conditions, leading to a 5%-15% reduction in charging efficiency at either low or high temperatures.

[0004] The relevant reference CN116444259A discloses a method for preparing high-frequency, high-DC superimposed, low-loss manganese-zinc ferrite materials. This method involves sequentially mixing and grinding the main materials, performing a first pre-firing, adding dopants, ball milling, and granulation, followed by a second pre-firing, second ball milling, and second granulation process. The material processed in the above steps is then formed into a green embryo and sintered to obtain a manganese-zinc ferrite soft magnetic material. The main materials include Fe2O3, MnO, ZnO, and NiO; the dopants include CaCO3 and / or Nb2O5, TiO2 and / or Co2O3, Bi2O3 and / or SnO2. This method increases the saturation magnetic flux density and reduces the residual magnetic flux density. However, the material exhibits poor temperature stability and low charging efficiency. Summary of the Invention

[0005] This invention aims to develop a wide-temperature, high-DC superimposed manganese-zinc ferrite soft magnetic material and its preparation method, which can solve the problem of low inductance of soft magnetic manganese-zinc ferrite under high current superposition in high and low temperature environments. It can be widely used in fields such as new energy vehicle charging to improve the charging efficiency of chargers.

[0006] To address the above technical problems, this invention provides a wide-temperature, high-DC superimposed manganese-zinc ferrite soft magnetic material, comprising a main formulation and a secondary formulation. The main formulation comprises 70.8-71.1 wt% Fe2O3, 19.7-20.1 wt% MnO, and the remainder ZnO; the secondary formulation comprises 2400-3000 ppm Co3O4, 2600-3000 ppm TiO2, 600-1200 ppm CaCO3, 100-400 ppm Nb2O5, and 20-60 ppm SiO2.

[0007] A method for preparing a wide-temperature, high-DC superimposed manganese-zinc ferrite soft magnetic material includes the following steps: (1) Weigh Fe2O3, MnO and ZnO raw materials according to the main formula ratio, mix the raw materials and pre-calcine them to obtain pre-calcined material; (2) The pre-burned material is coarsely crushed, then a small formula is added for sand milling, and then a binder is added for spray granulation to obtain granules; (3) The granular material is sintered in a mixed atmosphere of nitrogen and oxygen to obtain a wide-temperature high DC superimposed manganese zinc ferrite soft magnetic material sintering: a tube furnace is used for sintering, and the sintering temperature is 1330-1350℃.

[0008] Preferably, in step (1), the pre-firing temperature is 900℃ and the pre-firing time is 1h, which can effectively eliminate the abnormal expansion caused by the formation of ZnFe2O4 during subsequent sintering, avoid magnetic core cracks, and at the same time improve the compressibility and fluidity of the powder, and reduce product shrinkage and deformation.

[0009] Preferably, in step (2), the sand used for sand milling has a particle size of 1.3-1.5μm. By crushing the pre-burned material to the submicron level, the uniformity of the powder can be significantly improved, providing a more uniform solid-phase reaction basis for subsequent sintering, thereby optimizing the DC superposition performance of the final material.

[0010] Preferably, in step (3), the sintering temperature is 1350°C, so that the manganese zinc ferrite forms a dense spinel structure.

[0011] Preferably, in step (3), the sintering holding time is 3h, which ensures that the raw materials fully react in the solid phase and form a uniform microstructure, which is beneficial to the wide temperature and high DC superposition performance.

[0012] Preferably, in step (3), the oxygen content during sintering is 2.5%. Oxygen, as an oxidant, can oxidize Fe²⁺ to Fe³⁺, avoiding electron migration that leads to a decrease in resistivity, and obtaining better wide-temperature high DC superposition performance.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention optimizes the Fe2O3 and ZnO ratio, and avoids the incorporation of high-valence ions such as NiO and Bi2O3, which helps reduce costs, simplify the process, and improve production efficiency and product consistency. Furthermore, with a smaller formulation, the manganese-zinc ferrite material achieves a permeability of 2200-2300 at -40℃, 2600-2700 at 25℃, and 1700-1800 at 85℃ under a DC superimposed magnetic field H=51A / m, thus improving the charging efficiency of the charger.

[0014] 2. The preparation method of this invention is stable and easy to control. It involves pre-calcination at 900℃ for 1 hour, sintering in a tube furnace, and holding at 1350℃ for 3 hours. The sintering process is optimized, with clear steps, eliminating the need for complex temperature control procedures and improving production efficiency. The preparation process is relatively simplified, reducing energy consumption and labor input, while avoiding the additional costs associated with high-valence ions. Compared to traditional processes, it offers better market value.

[0015] 3. The pre-firing temperature of this invention is 900℃ and the pre-firing time is 1h, which can effectively eliminate the abnormal expansion caused by the formation of ZnFe2O4 during subsequent sintering, avoid magnetic core cracks, and at the same time improve the compressibility and flowability of the powder, and reduce product shrinkage and deformation. Detailed Implementation

[0016] Examples 1-4 provide a manganese-zinc ferrite material, the preparation method of which includes the following steps: (1) Weigh Fe2O3, MnO and ZnO raw materials according to the main formula ratio, mix the raw materials, and pre-calcine at 900℃ for 1 hour to obtain pre-calcined material; (2) The pre-burned material is coarsely crushed, then a small formula is added for sand milling, and then a conventional binder is added for spray granulation to obtain granules; (3) The granular material is sintered in a mixed atmosphere of nitrogen and oxygen to obtain a wide-temperature high DC superimposed manganese zinc ferrite soft magnetic material.

[0017] In step (1), the pre-firing temperature is 900℃ and the pre-firing time is 1h; In step (2), the abrasive particle size used in the sand mill is 1.5 μm; In step (3), the sintering temperature is 1350℃; In step (3), the sintering holding time is 3 hours; In step (3), the oxygen content during sintering is 2.5%; The formulations for samples 1-4 are shown in Table 1. Their properties are shown in Table 2. Examples marked with "*" are examples, and those without "*" are comparative examples.

[0018] Table 1

[0019] Table 2

[0020] As can be seen from Example 3* and the comparative example, increasing the zinc oxide content helps to improve the overall permeability. An appropriate amount of zinc oxide will increase the saturation magnetic induction intensity, thereby increasing the superimposed permeability of high and low temperature DC. When the iron oxide content is 70.97 wt.% and the zinc oxide content is above 9.5 wt.%, the increase in zinc oxide content will reduce the saturation magnetization intensity, thereby reducing the superimposed permeability.

[0021] Examples 5-7 provide a manganese-zinc ferrite material, the preparation method of which includes the following steps: (1) Weigh Fe2O3, MnO and ZnO raw materials according to the main formula ratio, mix the raw materials, and pre-calcine at 900℃ for 1 hour to obtain pre-calcined material; (2) The pre-burned material is coarsely crushed, then a small formula is added for sand milling, and then a conventional binder is added for spray granulation to obtain granules; (3) The granular material is sintered in a mixed atmosphere of nitrogen and oxygen to obtain a wide-temperature, high-DC superimposed manganese-zinc ferrite soft magnetic material.

[0022] In step (1), the pre-firing temperature is 900℃ and the pre-firing time is 1 h; In step (2), the abrasive particle size used in the sand mill is 1.5 μm; In step (3), the sintering temperature is 1350℃; In step (3), the sintering holding time is 3 hours; In step (3), the oxygen content during sintering is 2.5%; The formulations for samples 5-7 are shown in Table 3. Their properties are shown in Table 4. Examples marked with "*" are examples, and those without "*" are comparative examples.

[0023] Table 3

[0024] Table 4

[0025] As can be seen from Examples 6* and the Comparative Examples, increasing the cobalt oxide content results in more uniform grain growth, reduced porosity, and decreased resistance in domain rotation and domain wall displacement. Further addition of cobalt oxide increases saturation magnetization, leading to an increase in the superimposed permeability at both high and low temperatures. Simultaneously, the decrease in the magnetic anisotropy constant K1 causes the second peak of the permeability temperature curve to shift towards lower temperatures, resulting in an increase in initial permeability.

[0026] Examples 8-12 provide a manganese-zinc ferrite material, the preparation method of which includes the following steps: (1) Weigh Fe2O3, MnO and ZnO raw materials according to the main formula ratio, mix the raw materials, and pre-calcine at 900℃ for 1 hour to obtain pre-calcined material; (2) The pre-burned material is coarsely crushed, then a small formula is added for sand milling, and then a conventional binder is added for spray granulation to obtain granules; (3) The granular material is sintered in a mixed atmosphere of nitrogen and oxygen to obtain a wide-temperature, high-DC superimposed manganese-zinc ferrite soft magnetic material.

[0027] In step (1), the pre-firing temperature is 900℃ and the pre-firing time is 1 h; In step (2), the abrasive particle size used in the sand mill is 1.5 μm; In step (3), the sintering temperature is 1350℃; In step (3), the sintering holding time is 3 hours; In step (3), the oxygen content during sintering is 2.5%; The formulations for samples 8-12 are shown in Table 5. Their properties are shown in Table 6. Examples marked with "*" are examples, and those without "*" are comparative examples.

[0028] Table 5

[0029] Table 6

[0030] As can be seen from Examples 12* and Comparative Examples, an increase in the content of calcium oxycarbonate will affect the grain boundary migration rate, inhibit grain growth and refine grains, and increase the saturation magnetization, thereby increasing the superimposed permeability of high and low temperature DC.

[0031] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A wide-temperature, high-DC superimposed manganese-zinc ferrite soft magnetic material, comprising a main formulation and a minor formulation, characterized in that: The main formulation comprises 70.8-71.1 wt% Fe2O3, 19.7-20.1 wt% MnO, and the remainder ZnO; the sub-formulation comprises 2400-3000 ppm Co3O4, 2600-3000 ppm TiO2, 600-1200 ppm CaCO3, 100-400 ppm Nb2O5, and 20-60 ppm SiO2.

2. A method for preparing a wide-temperature, high-DC superimposed manganese-zinc ferrite soft magnetic material, characterized in that: Includes the following steps: (1) Weigh Fe2O3, MnO and ZnO raw materials according to the main formula ratio, mix the raw materials and pre-calcine them to obtain pre-calcined material; (2) The pre-burned material is coarsely crushed, then a small formula is added for sand milling, and then a binder is added for spray granulation to obtain granules; (3) The granular material is sintered in a mixed atmosphere of nitrogen and oxygen to obtain a wide-temperature high DC superimposed manganese zinc ferrite soft magnetic material sintering: tube furnace sintering is used and the sintering temperature is 1330-1350℃.

3. The preparation method of a wide-temperature, high-DC superimposed manganese-zinc ferrite soft magnetic material according to claim 2, characterized in that: In step (1), the pre-firing temperature is 900℃ and the pre-firing time is 1h.

4. The preparation method of a wide-temperature, high-DC superimposed manganese-zinc ferrite soft magnetic material according to claim 2, characterized in that: In step (2), the sand used for sand milling has a particle size of 1.3-1.5μm, and the pre-burned material is crushed to the submicron level.

5. The preparation method of a wide-temperature, high-DC superimposed manganese-zinc ferrite soft magnetic material according to claim 2, characterized in that: In step (3), the sintering temperature is 1350℃.

6. The preparation method of a wide-temperature, high-DC superimposed manganese-zinc ferrite soft magnetic material according to claim 2, characterized in that: In step (3), the sintering holding time is 3 hours.

7. The preparation method of a wide-temperature, high-DC superimposed manganese-zinc ferrite soft magnetic material according to claim 2, characterized in that: In step (3), the oxygen content of the sintering insulation is 2.5%.

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