A low-loss MnZn ferrite material for 500kHz and its preparation method

Abstract

The present invention relates to a low-loss MnZn ferrite material for 500kHz and a preparation method thereof. The method comprises the following steps: (1) adding MnZn ferrite particles and CaTiO3 powder to ethanol, stirring for 1.5 to 2.5 hours in a water bath at 45 to 55°C, and drying to obtain a mixed powder; (2) pressing the mixed powder into a magnetic ring, keeping the temperature at 1100 to 1200°C in a nitrogen-oxygen mixture for 45 to 75 minutes, and then cooling to 180 to 220°C to obtain a low-loss MnZn ferrite material for 500kHz. In the preparation method provided by the present invention, CaTiO3 is used as an auxiliary component to modify the MnZn ferrite, thereby increasing the magnetic permeability and improving the temperature coefficient of magnetic permeability, reducing eddy current loss and hysteresis loss, and achieving a minimum loss of 128mW·cm at 500kHz and room temperature. ‑3 Compared with the conventional MnZn ferrite material without adding CaTiO3, the loss is reduced by 42.1%, which greatly reduces the use loss of MnZn ferrite material and improves the performance of MnZn ferrite material.

Description

Technical Field

[0001] The invention relates to a low-loss MnZn ferrite material for 500 kHz and a preparation method thereof, belonging to the technical field of magnetic material preparation. Background Art

[0002] With the development of new energy vehicles, solar panels, and 5G communication technology, coupled with the call for green energy conservation, low carbon emissions, and environmental protection, electronic components such as transformers and inductors are moving towards high frequency, high efficiency, miniaturization, and ultra-thinness. This places a premium on the soft ferrite materials used, demanding low loss at higher frequencies. At the same time, most domestic MnZn ferrite manufacturers have excess production capacity, but their magnetic powder products have low added value, with the remaining cores primarily used in low-frequency bands. To improve the competitiveness of domestic manufacturers and increase the added value of their products, a simple, feasible, and effective preparation process is urgently needed to address this situation.

[0003] In order to reduce the total loss of MnZn power ferrite at 500kHz, it is necessary to separate the total loss of the material, analyze its loss composition and proportion, and then take corresponding measures to reduce the specific loss, thereby more effectively reducing the total loss of MnZn ferrite material. Chinese patent document CN117466638A discloses a wide temperature and low loss MnZn ferrite material, which includes a main component and an auxiliary component, wherein the main component is 53.1-53.8 mol% Fe2O3, 9-10 mol% ZnO, and the balance is MnO, and the auxiliary component is composed of: 0.34-0.45 wt% Co2O3, 0.03-0.04 wt% CaCO3, 0.020-0.025 wt% Nb2O5, 0.01-0.02 wt% ZrO2, 0.003-0.006 wt% SiO2, 0.05-0.5 wt% NiO, and 0.1-0.2 wt% SnO2. However, the MnZn ferrite material provided by this patent does not involve losses in the higher frequency band (500kHz), and the dopant needs to be added during the secondary ball milling. Once the doping effect is lower than expected, re-mixing will result in a waste of material time. In addition, the sintering process of this method requires a 3-hour insulation time, which consumes a lot of energy.

[0004] Therefore, the development of a MnZn ferrite material that can be used in the 500kHz high frequency band and maintain low loss, as well as a preparation method with a simpler and more effective doping method, a shorter sintering process time and lower energy consumption, is of great significance to the entire production and application of MnZn ferrite materials. Summary of the Invention

[0005] In view of the deficiencies of the prior art, the present invention provides a low-loss MnZn ferrite material for 500 kHz and a preparation method thereof.

[0006] The technical solutions of the present invention are as follows:

[0007] A method for preparing a low-loss MnZn ferrite material for 500 kHz comprises the following steps:

[0008] (1) adding MnZn ferrite particles and CaTiO3 powder to ethanol, stirring for 1.5 to 2.5 hours in a water bath at 45 to 55°C, and drying to obtain a mixed powder;

[0009] (2) The mixed powder is pressed into a magnetic ring at 300-500 MPa, and then the magnetic ring is placed in a sintering device, kept at 1100-1200°C in a nitrogen-oxygen mixed gas for 45-75 minutes, and then cooled to 180-220°C to obtain a low-loss MnZn ferrite material for 500 kHz.

[0010] According to the preferred embodiment of the present invention, in step (1), the mass ratio of the MnZn ferrite particles to the CaTiO3 powder is 1000:(0.4-1.2). The MnZn ferrite particles are existing materials and can be prepared according to a published method or obtained commercially.

[0011] Further preferably, the mass ratio of the MnZn ferrite particles to the CaTiO3 powder is 1000:1.

[0012] Preferably, according to the present invention, in step (1), the mass volume ratio of the MnZn ferrite particles to ethanol is 65:(80-120), unit: g / mL.

[0013] Preferably, according to the present invention, in step (1), the temperature of the water bath is 50° C., the stirring time is 2 h, and the stirring rate is 300 r / min.

[0014] According to the preferred embodiment of the present invention, in step (1), the drying step is performed by placing the product in an oven at 80° C. for 45 to 75 minutes.

[0015] Preferably, according to the present invention, in step (2), the sintering temperature is 1150° C. and the holding time is 60 minutes.

[0016] Preferably, according to the present invention, in step (2), the oxygen content in the nitrogen-oxygen mixture is 3.5%, a nitrogen-oxygen mixer is used to maintain the oxygen content during the insulation process, and flowing nitrogen is filled into the sintering equipment during the cooling process until cooling is completed.

[0017] The present invention also provides a low-loss MnZn ferrite material for 500 kHz prepared by the above method.

[0018] Anything not described in detail in the present invention can be carried out according to the existing technology.

[0019] Technical features and beneficial effects of the present invention:

[0020] 1. In the preparation method provided by the present invention, CaTiO3 is used as an auxiliary component to modify MnZn ferrite, wherein Ca 2+ The ions form a high resistance layer at the grain boundary, which increases the grain boundary resistivity, makes the grain boundary distinct, refines the grains, and reduces eddy current loss; Ti 4+ Some of them exist at the grain boundary, and some of them enter the interior of the lattice. The Ti inside the lattice 4+ This will cause 2Fe to appear at the B site of MnZn ferrite 3+ →Fe 2+ +Ti 4+ The conversion of Fe 2+ (K1>0), and also because Ti 4+ The ionic radius is larger than that of Fe 3+ The large radius of CaTiO3 changes the magnetic field characteristics of the crystal, making its magnetocrystalline anisotropy have a significant K1>0 effect, increasing the magnetic permeability and improving the temperature coefficient of magnetic permeability, while reducing eddy current loss and hysteresis loss. Therefore, adding CaTiO3 can effectively improve the magnetic properties and microstructure of MnZn ferrite, resulting in MnZn power ferrite that can be used at 500kHz.

[0021] 2. The low-loss MnZn ferrite material provided by the present invention has a minimum loss of 128mW·cm at 500kHz and room temperature. -3 Compared with the conventional MnZn ferrite material without adding CaTiO3, the loss is reduced by 42.1%, which greatly reduces the use loss of MnZn ferrite material and improves the performance of MnZn ferrite material.

[0022] 3. This invention provides a novel method for preparing low-loss MnZn ferrite materials. This method allows for direct composition adjustment based on MnZn ferrite particles, offering a novel approach for industrial production. Furthermore, this doping method can reuse excess powder from industrial production, increasing product value and reducing production losses and costs. Furthermore, the sintering process only requires a 45-75 minute hold at 1150°C, eliminating the need for multiple temperature adjustments, significantly contributing to energy conservation and carbon reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 These are XRD patterns of the low-loss MnZn ferrite materials prepared in Examples 1 to 4 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0024] The present invention is further described below by way of specific examples and accompanying drawings, but the scope of the invention is not limited thereto. The raw materials used in the examples are all conventional raw materials, and the equipment used are all conventional equipment, which can be purchased from commercial sources.

[0025] Among them, MnZn ferrite particles are existing materials, which can be prepared according to the "Soft Ferrite Production Process and Control Technology" or obtained from the market.

[0026] Example 1

[0027] A method for preparing a low-loss MnZn ferrite material for 500 kHz comprises the following steps:

[0028] (1) Add 65 g of MnZn ferrite particles and 0.026 g of CaTiO3 powder to 100 mL of ethanol, place the container containing the powder and ethanol in a water bath crucible, and stir with an electronic stirring rod for 2 h in a 50 ° C water bath at a speed of 300 r / min until the ethanol is basically evaporated. Place the stirred powder in an 80 ° C oven and dry it for 60 min until the ethanol is completely evaporated and the powder has good fluidity. Then take it out and cool it to room temperature to obtain a mixed powder;

[0029] (2) A hydraulic press is used to press the mixed powder into a magnetic ring at 400 MPa, and then the magnetic ring is placed in a bell-type atmosphere sintering furnace and kept warm for 60 minutes at a sintering temperature of 1150°C in a nitrogen-oxygen mixed gas environment. During the insulation process, a nitrogen-oxygen mixer is used to maintain the oxygen content at 3.5%. The magnetic ring is then cooled to 200°C. During the cooling process, flowing nitrogen is filled into the furnace, and the product is finally taken out to obtain a low-loss MnZn ferrite material for 500 kHz.

[0030] The low-loss MnZn ferrite material for 500 kHz prepared in this embodiment is numbered 2 and is denoted as CTO-4.

[0031] Example 2

[0032] A method for preparing a low-loss MnZn ferrite material for 500 kHz comprises the following steps:

[0033] (1) Add 65 g of MnZn ferrite particles and 0.052 g of CaTiO3 powder to 100 mL of ethanol, place the container containing the powder and ethanol in a water bath crucible, and stir with an electronic stirring rod for 2 h in a 50 ° C water bath at a speed of 300 r / min until the ethanol is almost completely evaporated. Place the stirred powder in an 80 ° C oven and dry it for 60 min until the ethanol is completely evaporated and the powder has good fluidity. Then take it out and cool it to room temperature to obtain a mixed powder;

[0034] (2) A hydraulic press is used to press the mixed powder into a magnetic ring at 400 MPa, and then the magnetic ring is placed in a bell-type atmosphere sintering furnace and kept warm for 60 minutes at a sintering temperature of 1150°C in a nitrogen-oxygen mixed gas environment. During the insulation process, a nitrogen-oxygen mixer is used to maintain the oxygen content at 3.5%. The magnetic ring is then cooled to 200°C. During the cooling process, flowing nitrogen is filled into the furnace, and the product is finally taken out to obtain a low-loss MnZn ferrite material for 500 kHz.

[0035] The low-loss MnZn ferrite material for 500 kHz prepared in this embodiment is numbered 3 and is denoted as CTO-8.

[0036] Example 3

[0037] A method for preparing a low-loss MnZn ferrite material for 500 kHz comprises the following steps:

[0038] (1) Add 65 g of MnZn ferrite particles and 0.065 g of CaTiO3 powder to 100 mL of ethanol, place the container containing the powder and ethanol in a water bath crucible, and stir with an electronic stirring rod for 2 h in a 50 ° C water bath at a speed of 300 r / min until the ethanol is almost completely evaporated. Place the stirred powder in an 80 ° C oven and dry it for 60 min until the ethanol is completely evaporated and the powder has good fluidity. Then take it out and cool it to room temperature to obtain a mixed powder;

[0039] (2) A hydraulic press is used to press the mixed powder into a magnetic ring at 400 MPa, and then the magnetic ring is placed in a bell-type atmosphere sintering furnace and kept warm for 60 minutes at a sintering temperature of 1150°C in a nitrogen-oxygen mixed gas environment. During the insulation process, a nitrogen-oxygen mixer is used to maintain the oxygen content at 3.5%. The magnetic ring is then cooled to 200°C. During the cooling process, flowing nitrogen is filled into the furnace, and the product is finally taken out to obtain a low-loss MnZn ferrite material for 500 kHz.

[0040] The low-loss MnZn ferrite material for 500 kHz prepared in this embodiment is numbered 4, denoted as CTO-10.

[0041] Example 4

[0042] A method for preparing a low-loss MnZn ferrite material for 500 kHz comprises the following steps:

[0043] (1) Add 65 g of MnZn ferrite particles and 0.078 g of CaTiO3 powder to 100 mL of ethanol, place the container containing the powder and ethanol in a water bath crucible, and stir with an electronic stirring rod for 2 h in a 50 ° C water bath at a speed of 300 r / min until the ethanol is basically evaporated. Place the stirred powder in an 80 ° C oven and dry it for 60 min until the ethanol is completely evaporated and the powder has good fluidity. Then take it out and cool it to room temperature to obtain a mixed powder;

[0044] (2) A hydraulic press is used to press the mixed powder into a magnetic ring at 400 MPa, and then the magnetic ring is placed in a bell-type atmosphere sintering furnace and kept warm for 60 minutes at a sintering temperature of 1150°C in a nitrogen-oxygen mixed gas environment. During the insulation process, a nitrogen-oxygen mixer is used to maintain the oxygen content at 3.5%. The magnetic ring is then cooled to 200°C. During the cooling process, flowing nitrogen is filled into the furnace, and the product is finally taken out to obtain a low-loss MnZn ferrite material for 500 kHz.

[0045] The low-loss MnZn ferrite material for 500 kHz prepared in this embodiment is numbered 5 and is denoted as CTO-12.

[0046] Comparative Example 1

[0047] A method for preparing a MnZn ferrite material, comprising the steps as described in Example 1, except that no CaTiO3 powder is added in step (1).

[0048] The MnZn ferrite material prepared in this comparative example is numbered 1 and is recorded as CTO-0.

[0049] Test example

[0050] The products prepared in Examples 1 to 4 and Comparative Example 1 were subjected to XRD characterization and performance testing. The test indicators included initial magnetic permeability (μ i ) and loss (P cv ), the result is as follows Figure 1 and as shown in Table 1.

[0051] The specific test method is: use LCR meter to test its inductance value and calculate its initial magnetic permeability μ i , use the power consumption meter to test its loss P at 500kHz and 50mT cv .

[0052] Table 1. Product properties of Examples 1 to 4 and Comparative Example 1

[0053]

[0054] Depend on Figure 1It can be seen that after sintering, Examples 1 to 4 and Comparative Example 1 have only one physical phase, MnZn ferrite, which indicates that the present invention successfully prepares MnZn ferrite material and the doped CaTiO3 does not affect the composition of the physical phase.

[0055] As shown in Table 1, compared with Comparative Example 1, the losses of the MnZn ferrite materials prepared in Examples 1 to 4 at 500kHz and 50mT are significantly reduced. In particular, the loss of the MnZn ferrite material No. 4 (CTO-10) is the lowest, only 128mW·cm -3 Compared with the conventional MnZn ferrite material without CaTiO3 added (Comparative Example 1), the loss is reduced by 42.1%, which is comparable to the performance of the PC500 product of Japan TDK Company under the same test conditions. This shows that the preparation method provided by the present invention uses CaTiO3 as an auxiliary component to modify the MnZn ferrite, wherein Ca 2+ The ions form a high resistance layer at the grain boundary, which increases the grain boundary resistivity, makes the grain boundary distinct, refines the grains, and reduces eddy current loss; Ti 4+ Some of them exist at the grain boundary, and some of them enter the interior of the lattice. The Ti inside the lattice 4+ This will cause 2Fe to appear at the B site of MnZn ferrite 3+ →Fe 2+ +Ti 4+ The conversion of Fe 2+ (K1>0), and also because Ti 4+ The ionic radius is larger than that of Fe 3+ The radius is large, which changes the magnetic field characteristics of the crystal and makes its magnetocrystalline anisotropy have an obvious K1>0 effect, thereby increasing the magnetic permeability and improving the temperature coefficient of magnetic permeability, reducing eddy current loss and hysteresis loss. Adding CaTiO3 can effectively improve the magnetic properties and microstructure of MnZn ferrite materials, thereby obtaining MnZn power ferrite that can be used for 500kHz.

[0056] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify or replace the technical solutions of the present invention with equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a low-loss MnZn ferrite material for 500kHz, characterized in that: The steps are as follows: (1) adding MnZn ferrite particles and CaTiO3 powder to ethanol, stirring for 1.5 to 2.5 hours in a water bath at 45 to 55°C, and drying to obtain a mixed powder; (2) The mixed powder is pressed into a magnetic ring at 300-500 MPa, and then the magnetic ring is placed in a sintering device, kept at 1100-1200°C in a nitrogen-oxygen mixed gas for 45-75 minutes, and then cooled to 180-220°C to obtain a low-loss MnZn ferrite material for 500 kHz.

2. The preparation method according to claim 1, wherein In step (1), the mass ratio of the MnZn ferrite particles to the CaTiO3 powder is 1000:(0.4-1.2).

3. The preparation method according to claim 2, wherein The mass ratio of the MnZn ferrite particles to the CaTiO3 powder is 1000:

1.

4. The preparation method according to claim 1, wherein In step (1), the mass volume ratio of the MnZn ferrite particles to ethanol is 65:(80-120), unit: g / mL.

5. The preparation method according to claim 1, wherein In step (1), the temperature of the water bath is 50° C., the stirring time is 2 h, and the stirring rate is 300 r / min.

6. The preparation method according to claim 1, wherein In step (1), the drying step is performed by placing the product in an oven at 80° C. for 45 to 75 minutes.

7. The preparation method according to claim 1, wherein In step (2), the sintering temperature is 1150° C. and the holding time is 60 minutes.

8. The preparation method according to claim 1, wherein In step (2), the oxygen content in the nitrogen-oxygen mixture is 3.5%. A nitrogen-oxygen mixer is used to maintain the oxygen content during the heat preservation process. Simultaneously, flowing nitrogen is introduced into the sintering equipment during the cooling process until the cooling is completed.

9. A low-loss MnZn ferrite material for 500kHz, characterized in that: It is prepared according to the preparation method according to any one of claims 1 to 8.

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