A high-frequency, high-Bs, high-DC superposition, low-loss manganese-zinc ferrite and preparation method thereof

Abstract

The present invention belongs to the technical field of magnetic materials, and specifically relates to a high-frequency, high-Bs, high-DC superposition, low-loss manganese-zinc ferrite and a preparation method. The manganese-zinc ferrite material of the present invention: 1. By doping the NiO quaternary main formula, the Curie temperature of the material is increased, the Bs of the material is increased, and the DC superposition characteristics of the material are improved; 2. Two batches of powders with different sanding particle sizes are evenly mixed in proportion to improve the particle size distribution of the powder, improve the microscopic properties of the material, increase the Bs of the material and reduce the material loss; 3. Set a suitable densification interval and time to make the reaction proceed to the direction of generating spinel to the greatest extent, ensure that the material can fully undergo solid-phase reaction, generate spinel structure, increase material density, improve material DC superposition characteristics, and successfully achieve the high-frequency, high-Bs, high-DC superposition, low-loss performance of the material under the conditions of 1MHz to 3MHz and working magnetic density of 30mT to 50mT.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetic materials, and specifically relates to a high-frequency, high-Bs, high-DC superposition, low-loss manganese-zinc ferrite and a preparation method thereof. Background Art

[0002] In recent years, manganese-zinc soft ferrite materials have been widely used as power materials (i.e. transformer cores) in the field of high-frequency switching power supplies. On the one hand, with the market demand for smaller, lighter and thinner electronic devices, in order to reduce the volume or weight of the magnetic circuit, it is urgent to use manganese-zinc ferrite materials with higher magnetic permeability and lower power loss at higher frequencies; on the other hand, in some circuits, the core works in an environment with a large DC superposition component, and it is necessary to establish a suitable working point for the magnetic device through the bias current of the core winding to put it in a specific working state. The electrical and magnetic properties of the core will change significantly with the superimposed DC field. It can be seen that when using soft magnetic power ferrites at high frequencies, in addition to low power consumption, the material must also have high DC superposition performance. Therefore, the research on the low power consumption and DC superposition characteristics of manganese-zinc soft ferrites has important guiding significance for the application of materials.

[0003] The Chinese patent with publication number CN116444259A discloses a high-frequency, high-DC superimposed low-loss manganese-zinc ferrite material and its preparation method. The invention mainly uses two pre-sintering processes, and then the second pre-sintering is followed by a second ball milling process to make the particle size distribution uniform, promote the homogenization of the sintered structure, obtain a better microstructure, and improve the magnetic properties. However, under the conditions of 1MHz and 50mT, the loss of the material at 25℃ and 100℃ both reaches 150kw / m 3 Above, the loss is high.

[0004] A Chinese patent with publication number CN109851346A discloses a high-frequency, high Bs and low-loss manganese-zinc soft ferrite material, which uses a quaternary system formula and a one-time pre-sintering process to produce a high-frequency manganese-zinc soft ferrite material with improved Bs and power consumption in a high-frequency environment. However, under the conditions of 1MHz and 50mT, the power loss of the invention at 25°C exceeds 300KW / m 3 , the power loss at 100℃ exceeds 180KW / m 3 ; Under the condition of 1194A / m, the Bs of this material at 25°C does not exceed 520mT, and the Bs at 100°C does not exceed 440mT. The loss and Bs characteristics of this invention are poor.

[0005] A Chinese patent with announcement number CN101419858B discloses a broadband, high permeability, low loss manganese-zinc soft ferrite material, which adopts multi-stage series sand grinding, each stage adopts the optimal combination of steel balls of different sizes, and the slurry is produced from the front stage to the back stage. The manufacturing process of this invention is complicated, and the equipment is prone to malfunction during large-scale production, affecting the production efficiency of the material; and the invention does not involve a parallel sand grinding process, that is, two batches of powders with different sand grinding particle sizes are evenly mixed in a certain proportion. Summary of the invention

[0006] The purpose of the present invention is to provide a high-frequency, high-Bs, high-DC superposition, low-loss manganese-zinc ferrite and a preparation method. The manganese-zinc ferrite material of the present invention: 1. By doping the NiO quaternary main formula, the Curie temperature of the material is increased, the Bs of the material is increased, and the DC superposition characteristics of the material are improved; 2. Two batches of powders with different sanding particle sizes are evenly mixed in a certain proportion to improve the particle size distribution of the powder, so that the powder particle size has a better normal distribution, improve the microscopic properties of the material, increase the Bs of the material and reduce the material loss; 3. Set a suitable densification interval and time to make the reaction proceed to the direction of generating spinel to the greatest extent, ensure that the material can fully undergo solid-phase reaction, generate spinel structure, increase material density, and improve the DC superposition characteristics of the material. Through the above-mentioned formula system, and in conjunction with optimizing the powder particle size distribution, a reasonable sintering process is formulated to successfully achieve the high-frequency, high-Bs, high-DC superposition, low-loss performance of the material under the conditions of 1MHz to 3MHz and working magnetic density of 30mT to 50mT.

[0007] A method for preparing high-frequency, high-Bs, high-DC superposition, low-loss manganese-zinc ferrite comprises the following steps:

[0008] Step 1: Ingredients, the main components include Fe2O3: 52.5-56.5mol%, ZnO: 3.0-5.5mol%, NiO: 1.8-4.5mol%, and the rest is Mn3O4, and wet sand milling is performed;

[0009] Step 2: pre-burning, drying the mixture obtained in step 1 and then pre-burning;

[0010] Step 3: sand grinding, vibrating the pre-sintered material obtained in step 2, and then adding auxiliary components CaCO3, Nb2O5, CuO, Co2O3 and Ta2O5, mixing and dividing into batch A and batch B and sand grinding them separately, and controlling the powder particle size D50 after sand grinding to be 0.8-1.2 μm and 0.6-0.9 μm respectively;

[0011] Step 4: Granulation, sieving and granulating the sand-milled batch A and batch B powders respectively;

[0012] Step 5: Mixing: mixing the powders of batch A and batch B in step 4 in a weight ratio of 3-5:5-7;

[0013] Step 6: Pressing and forming;

[0014] Step 7: Sintering. Before reaching the sintering temperature, densification is performed in the range of 700-850°C to 1050-1150°C, and the densification time is 2-5 hours.

[0015] Preferably, the main components include Fe2O3: 53.5-55.5mol%, ZnO: 3.5-5mol%, NiO: 2-4mol%, and the rest is Mn3O4;

[0016] Preferably, the main components include Fe2O3: 54-55mol%, ZnO: 4-4.5mol%, NiO: 2.5-3.5mol%, and the rest is Mn3O4.

[0017] Preferably, based on the total weight of the main components, the auxiliary components are CaCO3: 0.01-0.04wt%, Co2O3: 0.25-0.50wt%, Nb2O5: 0.01-0.03wt%, Ta2O5: 0.06-0.15wt%, CuO: 0.05-0.20wt%;

[0018] Preferably, based on the total weight of the main components, the auxiliary components are CaCO3: 0.02~0.03wt%, Co2O3: 0.35~0.4wt%, Nb2O5: 0.02~0.025wt%, Ta2O5: 0.08~0.12wt%, and CuO: 0.09~0.15wt%.

[0019] Preferably, in step 1, the main components are mixed by wet sand grinding, and the mixing time is 10 to 20 minutes.

[0020] Preferably, in step 2, pre-firing is carried out in air, the pre-firing temperature is 800-1000° C., and the heating rate is 3-5° C. / min.

[0021] Preferably, in step 3, the particle size D50 of the powder after sand grinding is controlled to be 0.9-1.1 μm and 0.7-0.8 μm respectively;

[0022] Preferably, in step 3, the sand grinding time of batch A and batch B powders is 40 to 60 minutes and 80 to 120 minutes respectively;

[0023] Preferably, in step 3, the sand grinding time of batch A and batch B powders is 45-55 min and 90-110 min, respectively.

[0024] Preferably, in step 4, the sand-milled powders of batch A and batch B are sieved and granulated respectively, and the PVA content added in the granulation is 5-20%.

[0025] Preferably, in step 5, the weight ratio of the powders of batch A to batch B is 3.5-4.5:5.5-6.5;

[0026] Preferably, in step 5, the weight ratio of batch A powder to batch B powder is 4:6.

[0027] Preferably, in step 6, the compacting density of the green body is 3.0 to 3.2 g / cm 3 .

[0028] Preferably, in step 7, before reaching the sintering temperature, densification is performed in the range of 750-800° C. to 1080-1120° C., and the densification time is 3-4 hours.

[0029] Preferably, in step 7, during the densification stage, the sintering atmosphere is a pure nitrogen atmosphere, or the oxygen content is 100 to 500 ppm;

[0030] Preferably, in step 7, during the densification stage, the oxygen content is 200 ppm, 300 ppm or 400 ppm.

[0031] Preferably, in step 7, the sintering temperature is 1100-1300° C.;

[0032] Preferably, in step 7, the sintering temperature is 1150-1250°C.

[0033] A high-frequency, high-Bs, high-DC superposition, low-loss manganese-zinc ferrite is mainly prepared by the above method. Compared with the prior art, the beneficial effects of the present invention are:

[0034] (1) The material of the present invention is suitable for scenarios of 1MHz to 3MHz and can be used in smaller, lighter and thinner electronic devices to meet the application requirements of low power loss at high frequencies;

[0035] (2) The material of the present invention has high Bs and high DC superposition characteristics and can be used in large DC superposition field circuits;

[0036] (3) The material of the present invention has the characteristics of high working magnetic flux density and low loss under the condition of 1MHz to 3MHz, and achieves the following technical performance, indicators and parameters:

[0037] Initial magnetic permeability μ i ≥800(T=25℃, B<0.25mT);

[0038] Magnetic loss Pcv≤50kW / m 3 (T=25℃, f=1MHz, B=50mT);

[0039] Pcv≤50kW / m 3(T=100℃, f=1MHz, B=50mT);

[0040] Pcv≤150kW / m 3 (T=25℃, f=3MHz, B=30mT);

[0041] Pcv≤150kW / m 3 (T=100℃, f=3MHz, B=30mT);

[0042] Saturation magnetic induction intensity Bs ≥ 550mT (25°C, H = 1194A / m); Bs ≥ 460mT (100°C, H = 1194A / m);

[0043] The high-frequency, high-Bs, high-DC superposition, low-loss manganese-zinc ferrite of the present invention has excellent magnetic characteristics such as high frequency, high DC superposition and low loss, meets the needs of magnetic electronic devices and products developing in the direction of miniaturization, lightness and energy saving, reduces the heat generated by equipment due to loss, and improves work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is the DC superposition diagram of the material in Example 1. DETAILED DESCRIPTION

[0045] The high-frequency, high-Bs, high-DC superposition, low-loss manganese-zinc ferrite and preparation method of the present invention are further described in detail below through specific implementation cases.

[0046] Embodiment 1: A method for preparing a high-frequency, high-Bs, high-DC superposition, low-loss manganese-zinc ferrite, comprising the following steps:

[0047] Step 1: Ingredients: Fe2O3: 55.4 mol%, ZnO: 4.5 mol%, NiO: 2.2 mol%, and the rest is Mn3O4, and then wet sand milled and mixed for 15 min;

[0048] Step 2: Pre-burning: drying the mixture obtained in step 1 and pre-burning it in air at a temperature of 900°C and a heating rate of 3.5°C / min;

[0049] Step 3: Sand grinding: The pre-sintered material obtained in step 2 was vibrated and then auxiliary components were added in proportion: CaCO3: 0.02 wt%, Nb2O5: 0.02 wt%, CuO: 0.06 wt%, Co2O3: 0.23 wt%, Ta2O5: 0.08 wt%, and the mixture was divided into batch A and batch B and sand ground separately. The sand grinding time was 40 min and 80 min respectively, and the sand grinding particle sizes were 1.18 μm and 0.84 μm respectively.

[0050] Step 4: Granulation: The sand-milled batch A and batch B powders were sieved and granulated, with a PVA content of 15%;

[0051] Step 5: Mixing: Mix the powders of batch A and batch B in step 4 in a ratio of 1:1 by a mixer;

[0052] Step 6: Pressing: Pressing into a ring-shaped green body with a size of Φ12.5mm×Φ7.5mm×7mm, the pressing density of the green body is 3.15g / cm 3 ;

[0053] Step 7: Sintering: Heat to 800°C and enter densification, the heating rate is 0.8°C / min, densification is carried out in the range of 800-1050°C, the densification time is 3h, the oxygen content in the densification stage is 100ppm, and the sintering temperature after densification is 1140°C.

[0054] Example 2: A method for preparing high-frequency, high-Bs, high-DC superposition, low-loss manganese-zinc ferrite. Compared with Example 1, the difference is that the main components in the ingredients of step 1 are Fe2O3: 55.4 mol%, ZnO: 4.5 mol%, NiO: 2.6 mol%, and the rest are Mn3O4.

[0055] Example 3: A method for preparing high-frequency, high-Bs, high-DC superposition, low-loss manganese-zinc ferrite. Compared with Example 1, the difference is that the mixing in step 5 is to mix the batch A and batch B powders in step 4 in a weight ratio of 3:2 through a mixer.

[0056] Comparative Example 1: A method for preparing high-frequency, high-Bs, high-DC superposition, low-loss manganese-zinc ferrite. Compared with Example 1, the difference is that the main components in the ingredients of step 1 are Fe2O3: 55.4 mol%, ZnO: 4.5 mol%, NiO: 1.6 mol%, and the rest are Mn3O4.

[0057] Comparative Example 2: A method for preparing high-frequency, high-Bs, high-DC superposition, low-loss manganese-zinc ferrite. Compared with Example 1, the difference is that the sand grinding time in step 3 is 30 min and 70 min respectively, and the sand grinding particle size is 1.31 μm and 0.97 μm respectively.

[0058] Comparative Example 3: A method for preparing high-frequency, high-Bs, high-DC superposition, low-loss manganese-zinc ferrite. The difference from Example 1 is that the powders in step 3 are directly sand-milled at one time after mixing, without being divided into two batches. The sand-milling time is 80 minutes, and the sand-milling particle size is 0.88 μm; the mixing of two batches of powders in step 5 is not involved.

[0059] The samples obtained from the embodiments and comparative examples were subjected to power consumption and Bs tests. The test conditions were: power consumption was tested at 1 MHz, 50 mT and 3 MHz, 30 mT, and Bs was tested at 1 kHz, 1194 A / m. The performance is recorded in Table 1 below.

[0060] Table 1 Magnetic properties of materials in Examples and Comparative Examples

[0061]

[0062] Through a reasonable formula system, optimized powder particle size distribution and a reasonable sintering process, we have successfully achieved high-frequency, high-Bs, high-DC superposition and low-loss manganese-zinc ferrite materials under the conditions of 1MHz~3MHz and working magnetic flux density of 30mT~50mT.

[0063] The above descriptions are only some embodiments of the present invention, but the protection scope of the present invention is not limited thereto.

Claims

1. A method for preparing high-frequency, high-Bs, high-DC superposition, low-loss manganese-zinc ferrite, characterized in that: The following steps are involved: Step 1: Ingredients, the main components include Fe2O3: 52.5-56.5mol%, ZnO: 3.0-5.5mol%, NiO: 1.8-4.5mol%, and the rest is Mn3O4, and wet sand milling is performed; Step 2: pre-burning, drying the mixture obtained in step 1 and then pre-burning; Step 3: sand grinding, vibrating the pre-sintered material obtained in step 2, and then adding auxiliary components CaCO3, Nb2O5, CuO, Co2O3 and Ta2O5, mixing and dividing into batch A and batch B, and sand grinding them separately, and controlling the powder particle size D50 after sand grinding to be 0.9-1.2 μm and 0.6-0.84 μm respectively; Step 4: Granulation, sieving and granulating the sand-milled batch A and batch B powders respectively; Step 5: Mixing: mixing the powders of batch A and batch B in step 4 in a weight ratio of 3-5:5-7; Step 6: Pressing and forming; Step 7: Sintering. Before reaching the sintering temperature, densification is performed in the range of 700-850°C to 1050-1150°C, and the densification time is 2-5 hours.

2. The method for preparing a high-frequency, high-Bs, high-DC superposition, low-loss manganese-zinc ferrite according to claim 1, characterized in that: The main components include Fe2O3: 53.5-55.5 mol%, ZnO: 3.5-5 mol%, NiO: 2-4 mol%, and the rest is Mn3O4.

3. The method for preparing a high-frequency, high-Bs, high-DC superposition, low-loss manganese-zinc ferrite according to claim 1, characterized in that: The auxiliary components are CaCO3: 0.01-0.04wt%, Co2O3: 0.25-0.50wt%, Nb2O5: 0.01-0.03wt%, Ta2O5: 0.06-0.15wt%, and CuO: 0.05-0.20wt%.

4. The method for preparing a high-frequency, high-Bs, high-DC superposition, low-loss manganese-zinc ferrite according to claim 1, characterized in that: In the step 1, the main components are mixed by wet sand grinding for 10 to 20 minutes. In the step 2, they are pre-fired in air at a temperature of 800 to 1000° C. and a heating rate of 3 to 5° C. / min.

5. The method for preparing a high-frequency, high-Bs, high-DC superposition, low-loss manganese-zinc ferrite according to claim 1, characterized in that: In step 3, the particle size D50 of the powder after sand grinding is controlled to be 0.9-1.1 μm and 0.7-0.84 μm respectively; the sand grinding time of the powders of batch A and batch B is 40-60 min and 80-120 min respectively.

6. The method for preparing a high-frequency, high-Bs, high-DC superposition, low-loss manganese-zinc ferrite according to claim 1, characterized in that: In step 5, the weight ratio of the powders of batch A to batch B is 3.5-4.5:5.5-6.

5.

7. The method for preparing a high-frequency, high-Bs, high-DC superposition, low-loss manganese-zinc ferrite according to claim 1, characterized in that: In the step 7, before reaching the sintering temperature, densification is performed in the range of 750-800° C. to 1080-1120° C., and the densification time is 3-4 hours.

8. The method for preparing a high-frequency, high-Bs, high-DC superposition, low-loss manganese-zinc ferrite according to claim 1, characterized in that: In the step 7, during the densification stage, the sintering atmosphere is a pure nitrogen atmosphere, or the oxygen content is 100 to 500 ppm.

9. The method for preparing a high-frequency, high-Bs, high-DC superposition, low-loss manganese-zinc ferrite according to claim 1, characterized in that: In the step 7, the sintering temperature is 1100-1300°C.

10. A high frequency, high Bs, high DC superposition, low loss manganese zinc ferrite, characterized in that: The high-frequency, high-Bs, high-DC, and low-loss manganese-zinc ferrite material is prepared by the preparation method of the high-frequency, high-Bs, high-DC, and low-loss manganese-zinc ferrite according to any one of claims 1 to 9.

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