Preparation method of manganese zinc ferrite material with broadband, low loss and high Bs power

Abstract

A preparation method of a broadband low-loss high-Bs power manganese zinc ferrite material relates to an electronic material technology, and comprises the following steps: step 1, taking Fe2O3, ZnO and MnO as raw materials, and batching; step 2, performing primary ball milling on the ingredients obtained in the step 1, and then drying and sieving to obtain a primary ball-milled material; step 3, pre-sintering; step 4, by taking the mass of the pre-sintered material obtained in the step 3 as a standard, adding 0.02 to 0.04 weight percent of V2O5, 0.02 to 0.04 weight percent of Nb2O5, 0.02 to 0.04 weight percent of ZrO2, 0.04 to 0.07 weight percent of TiO2 and 0.01 to 0.03 weight percent of YIG, so as to obtain doped mixed powder; step 5, secondary ball milling; step 6, granulating; step 7, pressing the granulated material into a green body part; and step 8, sintering the green body by stages. According to the invention, the initial permeability is improved while the resistivity of the power manganese-zinc ferrite is improved.

Description

Technical Field

[0001] The present invention relates to electronic material technology, and in particular to a method for preparing a broadband, low-loss, high-Bs power manganese-zinc ferrite material. Background Art

[0002] To address the issue of building an efficient power battery utilization system, PFM can be used to adjust the operating frequency to achieve a wide range of charging voltages, effectively extending battery life. Simultaneously, reducing the power loss of various electronic components can effectively improve power battery charging efficiency. These solutions place higher demands on the frequency and electromagnetic characteristics of power supply components and their materials. Manganese-zinc ferrite, a common core material for magnetic devices such as transformers and inductors, accounts for a significant portion of the volume and energy loss in onboard charger circuits, making it a key research topic.

[0003] Regarding broadband low-loss power manganese-zinc ferrite, Chinese patent document CN 101620908A discloses a wide-temperature, broadband, high-Curie-point, low-loss manganese-zinc ferrite material and its preparation method. Its main components include 52-57 mol% Fe2O3 and 3-7 mol% ZnO, with the remainder being MnO; its additives include 0.01-0.1 wt% CaO, 0.005-0.02 wt% SiO2, 0.04-0.075 wt% SnO2, 0.08-0.15 wt% TiO2, and 0.05-0.5 wt% Co2O3. This invention forms a perovskite high-resistance layer at the grain boundary by adding CaCO3 and TiO2, while TiO2 4+ The formation of electrostatic traps increases the resistivity and effectively reduces eddy current loss. At the same time, by adjusting the main material formula and appropriately increasing the Fe2O3 / ZnO content ratio, the cutoff frequency is increased and the residual loss is effectively reduced. Under the test conditions of 100℃, 200kHz, and 100mT, the volume power and volume loss of this material are 180-210kW / m 3 , under the test conditions of 100℃, 500kHz, 50mT, the volume power loss is 100~125kW / m 3 . However, the initial magnetic permeability of the material μ i and saturation magnetic induction intensity B sThe Chinese patent document CN 118471643A discloses a broadband ultra-low power loss manganese-zinc ferrite material, the main components of which include 71-72 mol% Fe2O3, 7-9 mol% ZnO and 20-21 mol% MnO, and the additives include 0.01-0.08 wt% CaCO3, 0.01-0.03 wt% SnO2, 0.005-0.008 wt% Co2O3, 0.005-0.01 wt% Bi2O3, 0.005-0.01 wt% nano-SiO2, 0.005-0.02 wt% MoO3 and 0.005-0.01 wt% ZrO2. This invention is achieved by doping Co 3+ The super exchange interaction between the A site and the B site is strengthened, which effectively improves the saturation magnetic induction intensity and the initial magnetic permeability, effectively reduces the hysteresis loss, and at the same time, the addition of low-melting-point YBCO forms a liquid phase during sintering to promote sintering, increase the sintering density, and increase the initial magnetic permeability of the material. The initial magnetic permeability of the material at 25°C is μ i and saturation magnetic induction intensity B s The volume loss is 271kW / m under the test conditions of 25℃, 100kHz and 200mT. 3 , the volume loss under the test conditions of 25℃, 300kHz, and 100mT is 251kW / m 3 Chinese patent document CN117843357A discloses an ultra-low loss high B s A wide-temperature, wide-bandwidth manganese-zinc ferrite material, wherein the main components include 52.0-55.5 mol% Fe2O3, 7.5-11.0 mol% ZnO, and the remainder Mn3O4. Its additives include 0.03-0.2 wt% CaO, 0.05-0.3 wt% SiO2, 0.01-0.2 wt% Nb2O5, 0.1-0.6 wt% Co2O3, 0.05-0.2 wt% TiO2, 0.05-0.3 wt% SnO2, 0.01-0.2 wt% ZrO2, 0.03-0.2 wt% V2O5, 0.05-0.2 wt% MoO3, and 0.03-0.5 wt% CuO. This invention adopts a multi-stage pre-sintering method to improve the activity of the powder while effectively avoiding the risk of material cracking. At the same time, it adopts a rapid heating and low-temperature sintering process of 1280-1330℃ to avoid abnormal grain growth. The initial magnetic permeability of this material at 25℃ is μ i and saturation magnetic induction intensity B s The volume loss is 334kW / m under the test conditions of 25℃, 100kHz and 200mT. 3 , the volume loss under the test conditions of 25℃, 500kHz, and 500mT is 121kW / m3 .

[0004] In summary, based on the existing broadband low loss high B s The research results show that the power manganese zinc ferrite material with low volume power loss and excellent electromagnetic performance has a narrow application frequency band of only 100 to 300kHz, while the electromagnetic performance and volume power loss performance of the power manganese zinc ferrite material with an application frequency of 100 to 500kHz are poor. Therefore, a new material with low loss in a wider frequency band (25kHz to 500kHz) and high initial magnetic permeability μi, resistivity and saturation magnetic induction intensity B has been developed. s The manganese-zinc ferrite material has great research significance and engineering application value. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing a power manganese-zinc ferrite material with low loss and excellent electromagnetic properties, especially in the frequency band of 25kHz to 500kHz.

[0006] The method for preparing a broadband, low-loss, high-Bs power manganese-zinc ferrite material provided by the present invention is characterized by comprising the following steps:

[0007] Step 1. Ingredients:

[0008] Fe2O3, ZnO and MnO are used as raw materials and are prepared in a ratio of "51.5-53.0 mol% of Fe2O3 and 10.0-12.0 mol% of ZnO, with the remainder being MnO";

[0009] Step 2: First ball milling

[0010] The ingredients obtained in step 1 are ball-milled once, and then dried and sieved to obtain a primary ball-milled material;

[0011] Step 3: Pre-burn

[0012] The sieved primary ball mill material is pre-fired in air at a temperature of 800°C to 900°C for 1 to 3 hours.

[0013] Step 4: Doping

[0014] Based on the mass of the pre-sintered material obtained in step 3, 0.02-0.04wt% V2O5, 0.02-0.04wt% Nb2O5, 0.02-0.04wt% ZrO2, 0.04-0.07wt% TiO2 and 0.01-0.03wt% YIG are added to obtain a doped mixed powder;

[0015] Step 5: Secondary ball milling

[0016] The mixed powder obtained by doping is subjected to secondary ball milling and dried to obtain secondary ball milled material;

[0017] Step 6: Granulation

[0018] Adding the secondary ball milling material to the binder, mixing them evenly and then granulating them to obtain granulated material;

[0019] Step 7: pressing the granulated material into a green part;

[0020] Step 8: Sinter the green part in stages:

[0021] The first stage: heating to 800-900°C in air atmosphere at a heating rate of 1-3°C / min;

[0022] The second stage: continue heating to 1200-1300℃ in air atmosphere. The heating rate is 1-2℃ / min;

[0023] The third stage: keep the sintering temperature at 1200-1300℃ for 6-8h, while adjusting the oxygen partial pressure to 1-3%;

[0024] The fourth stage: the temperature is lowered from 1200-1300°C to 800-900°C at a cooling rate of 1-3°C / min, and the oxygen partial pressure is reduced from 1-3% to 0%. Finally, the temperature is lowered from 800-900°C to room temperature at a cooling rate of 1-3°C / min in a pure nitrogen atmosphere.

[0025] Furthermore, in step 2, the ball milling speed is 230-260 r / min, and the ball milling time is 1-3 h.

[0026] In step 5, the ball milling speed is 230-250 r / min, and the ball milling time is 3-5 h.

[0027] Step 6 is: adding 8-14 wt% PVA adhesive to the secondary ball-milled material obtained in step 5, mixing evenly and then granulating to obtain granulated material.

[0028] In step 7, the granulated material is pressed into a green part at a pressure of 290 to 330 MPa.

[0029] The present invention uses YIG instead of the traditional CaCO3 additive to improve the resistivity of manganese-zinc ferrite while also improving the magnetic permeability. Traditional methods often use CaCO3 as an additive to improve the resistivity of manganese-zinc ferrite. CaCO3 has high melting point and high resistivity characteristics. During the sintering process, it will segregate at the grain boundaries to form a high-resistance layer, thereby achieving the purpose of improving the resistivity of manganese-zinc ferrite. The addition of a small amount of CaCO3 has an inhibitory effect on grain growth. Although a slower grain growth rate helps the densification process, a smaller grain size is not conducive to the initial magnetic permeability μ iIf excessive CaCO3 is added, the stability of the grain boundaries will be reduced, the grain growth will be coarsened and large pieces will stick together, resulting in the deterioration of the magnetic properties of the material. YIG also has the characteristics of high melting point and high resistivity. The addition of YIG can also achieve the purpose of improving the resistivity of power manganese-zinc ferrite, but compared with CaCO3, the addition of YIG does not cause drastic changes in grain size. At the same time, because YIG itself is magnetic, segregation at the grain boundaries is conducive to strengthening the magnetic coupling exchange effect between grains, which can effectively improve the saturation magnetic induction intensity B of the power manganese-zinc ferrite. s and the initial magnetic permeability μ i The present invention improves the resistivity of power manganese zinc ferrite while also improving the initial magnetic permeability μ i This is of great significance to reducing the power loss of power manganese zinc ferrite and expanding the application frequency band of power manganese zinc ferrite. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a SEM image of the natural cross section of Comparative Example 1 magnified 1000 times;

[0031] Figure 2 This is a SEM image of the natural cross section of Comparative Example 2 magnified 1000 times;

[0032] Figure 3 This is a SEM image of the natural cross section of Comparative Example 3 magnified 1000 times;

[0033] Figure 4 This is a SEM image of the natural cross section of Example 1 magnified 1000 times;

[0034] Figure 5 This is a SEM image of the natural cross section of Example 2 magnified 1000 times;

[0035] Figure 6 This is a SEM image of the natural cross section of Example 3 magnified 1000 times;

[0036] Figure 7 The loss temperature curves of Example 2 and Comparative Example 3 under the test conditions of 25kHz and 200mT;

[0037] Figure 8 The loss temperature curves of Example 2 and Comparative Example 3 under the test conditions of 100kHz and 200mT.

[0038] Figure 9 The loss temperature curves of Example 2 and Comparative Example 3 under the test conditions of 500kHz and 50mT. DETAILED DESCRIPTION

[0039] To further illustrate the technical solution of the present invention, the present invention is described in detail below with reference to the accompanying drawings and in conjunction with an embodiment. It should be noted that this example is only used to illustrate the present invention and does not limit the present invention. The "h" as a time unit in the present invention refers to "hour".

[0040] The present invention provides a method for preparing a broadband, low-loss, high-Bs power manganese-zinc ferrite material, comprising the following steps:

[0041] Step 1. Ingredients:

[0042] With Fe2O3, ZnO and MnO as raw materials, the calculation and ingredients are made according to the ratio of "51.5-53.0 mol% of Fe2O3 and 10.0%-12.0 mol% of ZnO, and the rest is MnO";

[0043] Step 2: First ball milling

[0044] The raw materials prepared in step 1 were added to deionized water and bearing steel balls and then placed in a planetary ball mill for primary milling. The milling speed was set at 230 r / min and the milling time was 2.5 hours. After the milling, the material was dried and sieved to obtain the primary milled material.

[0045] Step 3: Pre-burn

[0046] The sieved primary ball mill material in step 2 was pre-fired in air at a temperature of 800° C. for 3 h.

[0047] Step 4: Doping

[0048] Based on the mass of the pre-burned material obtained in step 3, additives are added in amounts shown in the table below to obtain a doped mixed powder;

[0049]

[0050] Step 5: Secondary ball milling

[0051] The mixed powder obtained after doping in step 4 was added to deionized water and bearing steel balls, and then placed in a planetary ball mill for secondary ball milling. The ball milling speed was 250 r / min and the ball milling time was 5 hours. After ball milling, it was dried to obtain the secondary ball milled material.

[0052] Step 6: Granulation

[0053] Add 14 wt% PVA binder to the secondary ball milled material in step 5, mix well and then granulate;

[0054] Step 7: Pressing

[0055] The granulated material in step 6 was placed into a mold and pressed into a green part at a pressure of 309 MPa.

[0056] Step 8: Sintering

[0057] The green body in step 7 is placed in a tube furnace in an atmosphere of balanced oxygen partial pressure for segmented sintering.

[0058] The first stage: heating to 900 °C in air atmosphere at a heating rate of 1.5 °C / min;

[0059] The second stage: continue heating to 1250℃ in air atmosphere at a heating rate of 2℃ / min;

[0060] The third stage: sintering at 1250 ° C for 8 hours while maintaining the oxygen partial pressure at 2.5%;

[0061] Stage 4: Cool down the temperature from 1250°C to 900°C at a cooling rate of 1.5°C / min, while reducing the oxygen partial pressure from 2.5% to 0%. Finally, cool down the temperature from 900°C to room temperature at a cooling rate of 3°C / min in a pure nitrogen atmosphere.

[0062] The performance characterization test of the manganese zinc ferrite prepared in Examples 1 to 3 and Comparative Examples 1 to 3 was carried out. The resistance of the samples at 25°C was measured using a TH2826LCR precision digital bridge and the resistivity of the samples was calculated. The initial magnetic permeability μ at 25°C was measured using an Iwasaki SY-8218B-H analyzer. i (Test conditions: 10kHz, 250mV) Saturation magnetic induction intensity B s (Test conditions: 50Hz, 1194A / m) and loss in the temperature range of 25~120℃ (Test conditions: 25kHz, 200mT, 100kHz, 200mmT, 500kHz, 50mT) were tested.

[0063] The following table shows the test results of Examples 1 to 3 and Comparative Examples 1 to 3:

[0064]

[0065]

[0066] Figures 1 to 3They are SEM images of the natural cross-sections of comparative examples 1 to 3 at 1000 times magnification. CaCO3 segregation at the grain boundaries can inhibit grain growth, promote the discharge of pores during the sintering process, increase density, and have a positive effect on improving the initial magnetic permeability. Inhibiting grain growth also reduces the grain size, increases the domain wall displacement resistance, and is not conducive to the improvement of the initial magnetic permeability. The change pattern of the initial magnetic permeability of MnZn ferrite with CaCO3 is the result of the combined effect of the above two mechanisms. From the test results, it can be seen that the positive contribution of densification to the improvement of the initial magnetic permeability is dominant, so the initial magnetic permeability of MnZn ferrite increases with the increase of CaCO3. In addition, the segregation of CaCO3 at the grain boundaries to form a high-resistance layer will be beneficial to the improvement of the resistivity of MnZn ferrite.

[0067] Figures 4-6 The following are SEM images of the natural cross-sections of Examples 1 to 3 at 1000 times magnification. The addition of YIG can slightly improve the sintering density of MnZn ferrite and has little effect on the average grain size. In addition, the magnetic YIG will segregate at the grain boundary to strengthen the magnetic coupling between the grains, thereby increasing the initial magnetic permeability of MnZn ferrite. The test results show that the degree of improvement of the initial magnetic permeability of MnZn ferrite by YIG is much greater than that of CaCO3 with the same content. On the other hand, due to the high resistivity of YIG, which is 10 12 Ω·m, and the sintering process will also segregate at the grain boundary to form a high-resistance layer, which increases the resistivity of MnZn ferrite.

[0068] Figure 1 、 Figure 2 、 Figure 3 The loss temperature curves of Example 2 and Comparative Example 3 under the test conditions of 25kHz, 200mT, 100kHz, 200mT, 500kHz, and 50mT are shown. In the temperature range of 25-120°C, the volume loss of Example 2 at each frequency point is lower than that of Comparative Example 3, verifying the superiority of the present invention.

[0069] The present invention uses YIG as a new additive to replace the traditional CaCO3 additive. On the one hand, although both YIG and CaCO3 have high resistivity (greater than 10 12 Ω·m), after sintering, it forms a high resistance layer at the grain boundary, which can reduce the eddy current loss. However, CaCO3 has a greater impact on the grain growth process and the grain size is difficult to control, while the addition of YIG has no obvious effect on the grain size. On the other hand, the magnetic YIG distributed at the grain boundary can enhance the magnetic coupling exchange between the grains, making the saturation magnetic induction intensity B of the power manganese-zinc ferrite s and the initial magnetic permeability μ i Therefore, the addition of YIG can make the manganese zinc ferrite have a higher initial magnetic permeability μ iAnd resistivity ρ, which can effectively reduce hysteresis loss and eddy current loss, and provide broadband, low loss and high B s The development of power manganese-zinc ferrite materials provides a solution.

Claims

1. Broadband, low loss, high B s The method for preparing a power manganese-zinc ferrite material is characterized in that: The steps include: Step 1. Ingredients: Fe2O3, ZnO and MnO are used as raw materials and are prepared in a ratio of "51.5-53.0 mol% of Fe2O3 and 10.0-12.0 mol% of ZnO, with the remainder being MnO"; Step 2: First ball milling The ingredients obtained in step 1 are ball-milled once, and then dried and sieved to obtain a primary ball-milled material; Step 3: Pre-burn The sieved primary ball mill material is pre-fired in air at a temperature of 800°C to 900°C for 1 to 3 hours. Step 4: Doping Based on the mass of the pre-sintered material obtained in step 3, 0.02-0.04wt% V2O5, 0.02-0.04wt% Nb2O5, 0.02-0.04wt% ZrO2, 0.04-0.07wt% TiO2 and 0.01-0.03wt% YIG are added to obtain a doped mixed powder; Step 5: Secondary ball milling The mixed powder obtained by doping is subjected to secondary ball milling and dried to obtain secondary ball milled material; Step 6: Granulation Adding the secondary ball milling material to the binder, mixing them evenly and then granulating them to obtain granulated material; Step 7: pressing the granulated material into a green part; Step 8: Sinter the green part in stages: The first stage: heating to 800-900°C in air atmosphere at a heating rate of 1-3°C / min; The second stage: continue heating to 1200-1300℃ in air atmosphere. The heating rate is 1-2℃ / min; The third stage: keep the sintering temperature at 1200-1300℃ for 6-8h, while adjusting the oxygen partial pressure to 1-3%; The fourth stage: the temperature is lowered from 1200-1300°C to 800-900°C at a cooling rate of 1-3°C / min, and the oxygen partial pressure is reduced from 1-3% to 0%. Finally, the temperature is lowered from 800-900°C to room temperature at a cooling rate of 1-3°C / min in a pure nitrogen atmosphere.

2. The broadband low-loss high B s The method for preparing a power manganese-zinc ferrite material is characterized in that: In step 2, the ball milling speed is 230-260 r / min, and the ball milling time is 1-3 h.

3. The broadband low-loss high B s The method for preparing a power manganese-zinc ferrite material is characterized in that: In step 5, the ball milling speed is 230-250 r / min, and the ball milling time is 3-5 h.

4. The broadband low-loss high B s The method for preparing a power manganese-zinc ferrite material is characterized in that: Step 6 is: adding 8-14 wt% PVA adhesive to the secondary ball-milled material obtained in step 5, mixing evenly and then granulating to obtain granulated material.

5. The broadband low-loss high B s The method for preparing a power manganese-zinc ferrite material is characterized in that: In step 7, the granulated material is pressed into a green part at a pressure of 290 to 330 MPa.

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