High power density low loss manganese-zinc ferrite material, preparation method and application thereof

Abstract

The application belongs to the technical field of magnetic materials, and provides a high-power-density low-loss manganese-zinc ferrite material and a preparation method and application thereof.The manganese-zinc ferrite material comprises main components and auxiliary components, the main components are Fe2O3, ZnO and Mn3O4, and the auxiliary components are CaCO3, SiO2, Co2O3, V2O5, MoO3 and Nb2O5; the preparation method is to optimize the sand milling process, design different diameter steel ball ratios to reduce the difference between the powder particle size D90 and D50, and then reduce the difference in activation energy required for grain growth, so as to realize the uniform growth of grains; at the same time, by appropriately reducing the powder particle size to increase the specific surface area and activity, combined with the ultra-low temperature liquid phase sintering technology, fine and uniform grains are obtained, the material loss is effectively improved, and the manganese-zinc soft magnetic ferrite material with high temperature low loss characteristics at 1MHz, 130mT is successfully prepared, which can be applied to high-power-density power converters.

Description

Technical Field

[0001] This invention belongs to the field of magnetic materials technology, and relates to a high power density, low loss manganese-zinc ferrite material, its preparation method and application. Background Technology

[0002] With the rapid iteration of server power supplies, the accelerated penetration of third-generation semiconductors GaN / SiC, and the upgrading of power systems, higher demands are being placed on DC-DC conversion efficiency and power density. Achieving high power density generally involves two approaches: one is to maintain the core's operating frequency while increasing the operating magnetic flux density; the other is to maintain the core's operating magnetic flux density while increasing the operating frequency. From the loss formula: It is known that core loss increases exponentially with operating frequency and operating magnetic flux density, with the power exponent corresponding to operating magnetic flux density being higher, making it more difficult to achieve. However, as the application scenarios and performance requirements of components increase, some customers have requested improved efficiency and reduced losses of the core under operating conditions of 1MHz and 130mT, and require low losses in the temperature range of 80~100℃. Since resistivity is inversely proportional to temperature, resistivity decreases sharply at high temperatures, leading to increased eddy current losses. Therefore, the fabrication of high power density, low loss ferrite materials for such secondary server power supplies is a significant challenge.

[0003] Patent CN114195500A discloses a wide-frequency, wide-temperature, high-power-density, low-loss manganese-zinc soft magnetic ferrite material and its preparation method. It employs a quaternary main formulation technology combined with secondary sintering of powder to obtain a wide-temperature, low-loss material at 500kHz and 1MHz, 100mT. However, its operating magnetic flux density remains relatively low, and this patent does not involve optimization of the sand milling process or low-temperature sintering technology. Patent CN118724579A provides a method for preparing high-power-density, high-resistivity, low-power manganese-zinc ferrite. By adding impurities that easily accumulate at grain boundaries and combining this with a sintering process to fully form a glassy phase, the grain boundary resistivity is increased, resulting in a high-frequency, low-loss material at 1.5~2MHz, 100mT. However, its operating magnetic flux density is still lower than that of this invention, and the preparation process involved differs significantly from that of this invention.

[0004] Therefore, in order to meet the high power density requirements of devices and overcome the above difficulties, it is necessary to develop a high power density, low power consumption manganese-zinc ferrite material with low loss in the high temperature region at f=1MHz, B=130mT. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this invention provides a high power density, low loss manganese zinc ferrite material, its preparation method, and its application, so as to realize the characteristics of high power density and low power consumption of manganese zinc ferrite material, which can be applied to high power density power converter application scenarios.

[0006] The manganese-zinc ferrite material of the present invention: (1) By optimizing the sand milling process and selecting the ratio of steel balls with different diameters, the difference between D90 and D50 of the secondary sand milling slurry is reduced, and a slurry with a similar specific surface area is prepared to achieve uniformity of the core grain size and effectively reduce the hysteresis loss of the core; (2) By increasing the specific surface area of ​​the slurry, the activation energy required for grain growth is reduced. Combined with the addition of low-melting-point oxide auxiliary components and low-temperature sintering technology, low-temperature liquid phase sintering is achieved to achieve the effect of refining and densifying the grains and reducing the eddy current loss of the material. (3) The uniform particle size distribution and the high specific surface area of ​​the slurry provide a premise for the uniform densification of low-temperature sintering, while the low-temperature sintering process retains the advantage of particle size uniformity obtained in the sand milling stage. The synergistic effect between the two ultimately yields a low-loss core with uniform grain size and dense structure.

[0007] Through the above optimization of sand milling gradation, control of slurry specific surface area, and optimization and synergistic effect of sintering process, low-power manganese-zinc ferrite for high power density power converters has been successfully produced.

[0008] To achieve the above objectives, the technical solution adopted by this invention is as follows:

[0009] A method for preparing a high power density, low loss manganese-zinc ferrite material includes the following steps:

[0010] Step 1: Ingredient preparation. Weigh the main components according to the following proportions: Fe2O3: 52.0~57.0 mol%, ZnO: 5.0~10.0 mol%, with the remainder being Mn3O4. Then, perform sand milling and mixing to obtain a mixture.

[0011] Step 2: Pre-firing, the mixture obtained in Step 1 is pre-firing to obtain pre-fired material;

[0012] Step 3: Sand milling. The pre-burned material obtained in Step 2 is sieved, and then auxiliary components are added before sand milling to obtain abrasive material. The auxiliary components are CaCO3, SiO2, Co2O3, MoO3, V2O5, and Nb2O5.

[0013] Step 4: Granulation. Add glue to the abrasive obtained in Step 3 to granulate and obtain granules.

[0014] Step 5: Pressing. Press the granules obtained in Step 4 to obtain green bodies.

[0015] Step 6: Sintering. The green body obtained in Step 5 is sintered at a temperature of 1050~1160℃ for 3~8 hours, with an oxygen content of 1.0~2.6% during the holding period.

[0016] Preferably, the main components are Fe2O3: 53.0~56.0 mol%, ZnO: 6.0~9.0 mol%, and the remainder is Mn3O4.

[0017] Preferably, the main components are Fe2O3: 54.0~55.5 mol%, ZnO: 6.5~8.0 mol%, and the remainder is Mn3O4.

[0018] Preferably, the auxiliary components, based on the total weight of the main components, include: CaCO3: 600~1200ppm, SiO2: 60~90ppm, Co2O3: 1250~1750ppm, MoO3: 200~300ppm, V2O5: 200~400ppm, and Nb2O5: 100~200ppm.

[0019] Preferably, based on the total weight of the main components, the CaCO3 content can be 600ppm, 800ppm, 1000ppm, or 1200ppm; the SiO2 content can be 60ppm, 70ppm, 80ppm, or 90ppm; the Co2O3 content can be 1250ppm, 1500ppm, or 1750ppm; the Mo2O3 content can be 200ppm, 250ppm, or 300ppm; the V2O5 content can be 200ppm, 250ppm, 300ppm, 350ppm, or 400ppm; and the Nb2O5 content can be 100ppm, 150ppm, or 200ppm.

[0020] In step 1, wet sand milling is used for mixing, and the mixing time is 5~20 minutes.

[0021] In step 2, the mixture obtained in step 1 is pre-fired in air at a temperature of 800-900°C, a heating rate of 3-5°C / min, and a holding time of 2-3 hours. The pre-fired material is then sieved, preferably with a mesh size of 28-60 mesh, more preferably 40 mesh.

[0022] Preferably, in step 3, the steel balls have diameters of 1mm, 3mm, and 5.5mm, and their mass ratio is 1:(1.5~2.5):(3.0~5.0), which can be 1:1.5:3.0, 1:1.5:4, 1:1.5:5; 1:2.0:3.0, 1:2.0:4, 1:2.0:5.0; 1:2.5:3.0, 1:2.5:4.0, 1:2.5:5.0; the resulting abrasive has a D50 of 0.6~1.0μm, which can be 0.6, 0.7, 0.8, 0.9, or 1.0μm, and a D90 of 1.6~2.4μm, which can be 1.6, 1.8, 2.0, 2.2, or 2.4μm; the difference between D90 and D50 is 1.0~1.8μm.

[0023] Preferably, in step 3, the steel balls have diameters of 1mm, 3mm, and 5.5mm, and their mass ratio is 1:(1.8~2.4):(3.5~4.5), which can be 1:1.8:3.5, 1:1.8:4.0, 1:1.8:4.5; 1:2.1:3.5, 1:2.1:4.0, 1:2.1:4.5; 1:2.4:3.5, 1:2.4:4.0, 1:2.4:4.5; the resulting abrasive has a D50 of 0.6~0.9μm, which can be 0.6, 0.7, 0.8, or 0.9μm, and a D90 range of 1.6~2.2μm, which can be 1.6, 1.8, 2.0, or 2.2μm; the difference between D90 and D50 is 1.0~1.5μm.

[0024] Preferably, in step 3, the mass ratio of steel balls with diameters of 1mm, 3mm, and 5.5mm is 1:(1.8~2.1):(3.5~4.0), and can take values ​​of 1:1.8:3.5, 1:1.8:3.75, 1:1.8:4.0; 1:1.95:3.5, 1:1.95:3.75, 1:1.95:4.0; 1:2.1:3.5, 1:2.1:3.75, 1:2.1:4.0; the resulting abrasive D50 is 0.7~0.8μm, and can take values ​​of 0.7 or 0.8μm; the D90 range is 1.8~2.0μm, and can take values ​​of 1.8, 1.9, or 2.0μm; the difference between D90 and D50 is 1.0~1.2μm.

[0025] Preferably, in step 3, the grinding speed is 250~300 rpm, the grinding time is 50~70 min, and the ratio of the total mass of the pre-burned material and auxiliary components to the mass of the steel ball is 1:(3~7), more preferably 1:5.

[0026] In step 4, the adhesive includes polyvinyl alcohol. After adding polyvinyl alcohol, granulation is carried out. The amount of polyvinyl alcohol added is 6-15 wt% of the abrasive. After granulation, the sieve is sieved. The sieve mesh size is preferably 100-150 mesh, and more preferably 120 mesh.

[0027] Preferably, in step 5, the pressing pressure is 30~80MPa.

[0028] Preferably, in step 6, the sintering temperature is 1080~1120℃, and the oxygen content in the heat preservation section is 1.4~2.0%.

[0029] Secondly, the present invention provides a high power density, low loss manganese-zinc ferrite material, which is prepared by the preparation method of the high power density, low loss manganese-zinc ferrite material, and is composed of main components and auxiliary components. The main components are Fe2O3: 52.0~57.0 mol%, ZnO: 5.0~10.0 mol%, and the remainder is Mn3O4. The auxiliary components include CaCO3: 600~1200 ppm, SiO2: 60~90 ppm, Co2O3: 1250~1750 ppm, MoO3: 200~300 ppm, V2O5: 200~400 ppm, and Nb2O5: 100~200 ppm.

[0030] Preferably, the main components are Fe2O3: 53.0~56.0 mol%, ZnO: 6.0~9.0 mol%, and the remainder is Mn3O4.

[0031] Preferably, the main components are Fe2O3: 54.0~55.5 mol%, ZnO: 6.5~8.0 mol%, and the remainder is Mn3O4.

[0032] Preferably, based on the total weight of the main components, the CaCO3 content can be 600ppm, 800ppm, 1000ppm, or 1200ppm; the SiO2 content can be 60ppm, 70ppm, 80ppm, or 90ppm; the Co2O3 content can be 1250ppm, 1500ppm, or 1750ppm; the Mo2O3 content can be 200ppm, 250ppm, or 300ppm; the V2O5 content can be 200ppm, 250ppm, 300ppm, 350ppm, or 400ppm; and the Nb2O5 content can be 100ppm, 150ppm, or 200ppm.

[0033] The high power density, low loss manganese-zinc ferrite material exhibits low power consumption at 1MHz and 130mT, where Pcv ≤ 5000kW / m 3 (T=25℃, f=1MHz, B=130mT), Pcv≤3850kW / m 3 (T=100℃, f=1MHz, B=130mT), which can be applied to high power density power converters.

[0034] Thirdly, the application of the high power density, low loss manganese-zinc ferrite material as described in the second aspect in a high power density power converter is provided.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] (1) The high power density and low loss manganese zinc ferrite material can be applied to high operating frequency of 1MHz and high operating magnetic flux density of 130mT, while having low power consumption characteristics, which can meet the needs of higher frequency, integration and miniaturization of devices.

[0037] (2) The high power density and low loss manganese-zinc ferrite material has low power consumption characteristics under the conditions of 1MHz and 130mT, and its technical performance, indicators and parameters are as follows:

[0038] Pcv≤5000kW / m 3 (T=25℃, f=1MHz, B=130mT);

[0039] Pcv≤3850kW / m 3 (T=100°C, f=1MHz, B=130mT). Attached Figure Description

[0040] Figure 1 Here is a SEM image of the manganese-zinc ferrite obtained in Example 2;

[0041] Figure 2 SEM images of the manganese-zinc ferrite obtained in Comparative Example 2. Detailed Implementation

[0042] The following specific implementation examples further illustrate the high power density, low power consumption manganese-zinc ferrite materials and their preparation process according to the present invention. Three manganese-zinc ferrite materials (Examples 1-3) and three comparative examples (Examples 1-3) were prepared according to the following preparation methods.

[0043] Example 1:

[0044] A high-power-density, low-loss manganese-zinc ferrite comprises main components and auxiliary components. The main components are Fe₂O₃: 54.8 mol%, ZnO: 6.2 mol%, Mn₃O₄: 39 mol%; the auxiliary components are CaCO₃: 700 ppm, SiO₂: 70 ppm, Co₂O₃: 1900 ppm, Mo₂O₃: 200 ppm, V₂O₅: 300 ppm, and Nb₂O₅: 150 ppm. The preparation method includes the following steps:

[0045] Step 1: Ingredients: Weigh Fe2O3, ZnO, and Mn3O4 according to the proportion, and then perform wet sand milling for 12 minutes to obtain the mixture;

[0046] Step 2: Pre-firing: After drying the mixture obtained in Step 1, pre-firing is carried out in air at a temperature of 820℃, a heating rate of 3℃ / min, and a holding time of 2h.

[0047] Step 3: Sand milling: The pre-calcined material obtained in Step 2 is sieved through a 40-mesh sieve, and then auxiliary components are added in the following proportions: CaCO3, SiO2, Mo2O3, Co2O3, V2O5, and Nb2O5; the diameters of the steel balls are 1mm, 3mm, and 5.5mm, and the mass ratio of the three is 1:1.8:4.0. During sand milling, the ratio of the total mass of the pre-calcined material and auxiliary components to the total mass of the steel balls is 1:5. The sand milling speed is 300rpm, and the sand milling time is 60min. The resulting sand milling material has D50=0.9μm, D90=2.2, and D90-D50=1.3μm.

[0048] Step 4: Granulation: Dry the slurry after sand milling, add 10wt% polyvinyl alcohol to the sand milling material for granulation, and after granulation, sieve it through a 120-mesh sieve.

[0049] Step 5: Pressing and forming: Press a ring-shaped green body with dimensions of Φ12.7mm×Φ8mm×7mm and a pressing pressure of 50MPa;

[0050] Step 6: Sintering, sintering temperature is 1090℃, oxygen content in the holding section is 1.6%, holding time is 5h.

[0051] Example 2:

[0052] The difference from Example 1 is that the main components are Fe2O3: 55.6 mol%, ZnO: 6.6 mol%, and Mn3O4: 37.8 mol%.

[0053] Example 3:

[0054] The difference from Example 1 is that in step three, the diameters of the steel balls are 1mm, 3mm, and 5.5mm, respectively, and the mass ratio of the three is 1:1.95:3.5, D50=0.8μm, D90=1.8, and D90-D50=1.0μm.

[0055] Comparative Example 1:

[0056] The difference from Example 1 is that the main components are Fe2O3: 58.2 mol%, ZnO: 11.5 mol%, and Mn3O4: 30.3 mol%.

[0057] Comparative Example 2:

[0058] The difference from Example 2 is that the diameter of a single steel ball is 5.5 mm, D50 = 1.0 μm, D90 = 2.95, and D90 - D50 = 1.95 μm.

[0059] Comparative Example 3:

[0060] The difference from Example 1 is that the sintering temperature is 1180°C and the oxygen content in the holding section is 2.8%.

[0061] The manganese-zinc ferrite sample rings prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to power loss (Pcv) tests, and the results are shown in Table 1:

[0062] Table 1 Comparison of magnetic properties tested in the examples and comparative examples

[0063]

[0064] As shown in Table 1, Examples 1, 2, and 3, prepared according to the present invention, yielded the best magnetic properties. Comparing Comparative Example 1 with Example 1, it was found that when the contents of iron oxide and zinc oxide in the main formulation were outside the range of the main formulation, the loss at 60℃~100℃ deteriorated significantly. Comparing Comparative Example 2 with Example 2, it was found that when the steel balls were milled using a single diameter, the loss deteriorated to some extent. Comparing Comparative Example 3 with Example 3, it was found that when the sintering temperature was higher, the performance deteriorated significantly.

[0065] Figure 1 and Figure 2 SEM images of Example 2 and Comparative Example 2 are shown below. It can be seen that the ferrite grains obtained in Example 2 have better size uniformity than those in Comparative Example 2. Example 2 used a secondary grinding process with steel balls of different diameters, resulting in abrasive particles with D50 = 0.9 μm, D90 = 2.2 μm, and D90 - D50 = 1.3 μm. Comparative Example 2 used a single 5.5 mm diameter steel ball for secondary grinding, resulting in abrasive particles with D50 = 1.0 μm, D90 μm = 2.95, and D90 - D50 = 1.95 μm. The difference between D90 and D50 in Comparative Example 2 is significantly higher than that in Example 2, indicating poor grain size uniformity. This demonstrates that the grinding process described in this example can reduce grain size and effectively improve grain size uniformity, thereby improving the uniformity of subsequent grain growth and improving material loss characteristics.

[0066] The above description is only some embodiments of the present invention, but the scope of protection of the present invention is not limited thereto.

Claims

1. A method for preparing a high power density, low loss manganese-zinc ferrite material, characterized in that, Includes the following steps: Step 1, Ingredients: The main components are 52.0~57.0 mol% Fe2O3, 5.0~10.0 mol% ZnO, and the balance is Mn3O4. Weigh them according to the proportion and mix them to obtain a mixture. Step 2, Pre-calcination: The mixture obtained in Step 1 is pre-calcined to obtain pre-calcined material; Step 3, Sand Milling: The pre-calcined material obtained in Step 2 is sieved, and then auxiliary components are added. A second sand milling is performed using steel balls with diameters of 1mm, 3mm, and 5.5mm in a mass ratio of 1:(1.5~2.5):(3.0~5.0) to obtain abrasive sand. The auxiliary components include CaCO3, SiO2, Co2O3, MoO3, V2O5, and Nb2O5. The abrasive sand has a D50 of 0.6~1.0μm, a D90 of 1.6~2.4μm, and a difference between D90 and D50 of 1.0~1.8μm. Step 4, Granulation: Add glue to the abrasive obtained in Step 3 to granulate and obtain granules; Step 5, Pressing: Press the granules obtained in step 4 to obtain green bodies; Step 6, Sintering: Sinter the green body obtained in step 5 at a temperature of 1050~1160℃.

2. The method for preparing the high power density, low loss manganese-zinc ferrite material as described in claim 1, characterized in that, In step 1, the main components are 53.0~56.0 mol% Fe2O3, 6.0~9.0 mol% ZnO, and the balance is Mn3O4; the mixture is mixed by wet sand milling for 5~20 min.

3. The method for preparing the high power density, low loss manganese-zinc ferrite material as described in claim 1, characterized in that, In step 2, the pre-firing atmosphere is air, the pre-firing temperature is 800~900℃, the heating rate is 3~5℃ / min, and the holding time is 2~3h; the pre-firing material is sieved using a 28~60 mesh sieve.

4. The method for preparing the high power density, low loss manganese-zinc ferrite material as described in claim 1, characterized in that, In step 3, the content of auxiliary components is as follows: CaCO3: 600~1200ppm, SiO2: 60~90ppm, Co2O3: 1250~1750ppm, MoO3: 200~300ppm, V2O5: 200~400ppm, Nb2O5: 100~200ppm.

5. The method for preparing the high power density, low loss manganese-zinc ferrite material as described in claim 1, characterized in that, In step 3, the secondary sand milling speed is 250~300 rpm, the time is 50~70 min, and the ratio of the total mass of the pre-burned material and auxiliary components to the total mass of the steel balls is 1:(3~7).

6. The method for preparing the high power density, low loss manganese-zinc ferrite material as described in claim 1, characterized in that, In step 4, the adhesive includes polyvinyl alcohol, and the amount added is 6~15wt% of the abrasive; and the granules are sieved using a 100~150 mesh sieve.

7. The method for preparing the high power density, low loss manganese-zinc ferrite material as described in claim 1, characterized in that, In step 5, the pressing pressure is 30~80MPa.

8. The method for preparing the high power density, low loss manganese-zinc ferrite material as described in claim 1, characterized in that, In step 6, the heat preservation time is 3 to 8 hours, and the oxygen content in the heat preservation section is 1.0 to 2.6%.

9. A high power density, low loss manganese-zinc ferrite material, characterized in that, The high power density, low loss manganese-zinc ferrite material was prepared using the preparation method described in any one of claims 1-8.

10. The use of the high power density, low loss manganese-zinc ferrite material as described in claim 9, characterized in that, The high power density, low loss manganese-zinc ferrite is used in high power density power converters.

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