Broadband low-loss manganese-zinc-magnesium ferrite material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of ferrite, in particular to a broadband low-loss manganese-zinc-magnesium ferrite material and a preparation method and application thereof.The broadband low-loss manganese-zinc-magnesium ferrite material comprises main components and auxiliary components, the main components comprise, by mole percent, 50.5-58.5 mol% of Fe2O3, 5.0-14.0 mol% of ZnO, 0.1-0.5 mol% of MgO and the balance MnO, and the auxiliary components comprise, by weight, 300-800 ppm of CaO, 50-300 ppm of SiO2, 100-400 ppm of Ta2O5 and 10-30 ppm of Na2O. The preparation method comprises the following steps: mixing and pre-sintering the main components, mixing and grinding the pre-sintered main components and the auxiliary components, adding a binder, carrying out spray granulation, carrying out compression molding, and sintering to obtain the ferrite material, which can be widely used for manufacturing magnetic cores with different specifications and different shapes. Through Mn-Zn-Mg ferrite components with specific content, an adaptive preparation method is selected, and the content of the sulfur element in the raw materials is limited, so that the problem of high loss of the existing material in the broadband range of 100kHz-500kHz is solved.

Description

A broadband, low-loss manganese-zinc-magnesium ferrite material, its preparation method, and its application. Technical Field

[0001] This invention relates to the field of ferrite technology, and in particular to a broadband, low-loss manganese-zinc-magnesium ferrite material, its preparation method, and its applications. Background Technology

[0002] Soft magnetic ferrite materials, due to their excellent properties such as high resistivity and low high-frequency power loss, have become one of the indispensable key materials in the field of high-frequency power electronics. Magnetic cores made of soft magnetic ferrites are widely used in electronic components such as transformers and inductors, and their performance directly affects the energy conversion efficiency and operating temperature of electronic devices. With the miniaturization and high-frequency development of electronic devices, higher requirements are being placed on the loss characteristics of ferrite materials under high-frequency conditions.

[0003] Currently, Mn-Zn ferrite, as a commonly used soft magnetic material, exhibits good magnetic properties in the low and mid-frequency range. However, in high-frequency applications (such as above several hundred kHz), its eddy current and hysteresis losses increase significantly, leading to an overall increase in losses and limiting its use in high-frequency power electronic devices. To meet the requirements of different operating frequency bands, different types of ferrite materials, such as Ni-Zn or Mg-Zn materials, are usually selected to meet the low-loss requirements at specific frequencies. However, this approach not only increases the complexity of material development and production but also raises manufacturing costs.

[0004] Although existing studies have attempted to improve the high-frequency characteristics of Mn-Zn ferrites through doping or process optimization, problems such as inaccurate control of material composition, impurity elements affecting grain boundary structure, and mismatch of sintering process parameters still exist, resulting in unstable loss performance of the material over a wide frequency range and making it difficult to achieve comprehensive optimization.

[0005] Therefore, there is an urgent need to develop a Mn-Zn-based ferrite material with low loss characteristics in a wide frequency range of 100kHz to 500kHz, and to develop a suitable preparation process to meet the stringent requirements of modern high-frequency electronic devices for material performance, while reducing production costs and enhancing product competitiveness. Summary of the Invention

[0006] The purpose of this invention is to provide a broadband, low-loss manganese-zinc-magnesium ferrite material, its preparation method, and its application. By selecting a suitable preparation method with a specific content of Mn-Zn-Mg ferrite composition and limiting the sulfur content in the raw materials, this invention aims to solve the problem of high loss in existing materials within a broadband range of 100kHz to 500kHz.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of the present invention provides a broadband low-loss manganese zinc magnesium ferrite material, comprising a main component and secondary components. The main component, by molar percentage, comprises 50.5~58.5 mol% Fe2O3, 5.0~14.0 mol% ZnO, 0.1~0.5 mol% MgO, with the balance being MnO. The secondary components, by weight of the main component, comprise 300~800 ppm CaO, 50~300 ppm SiO2, 100~400 ppm Ta2O5, and 10~30 ppm Na2O.

[0008] Furthermore, the secondary components, based on the total weight of the main components, also include ≤300 ppm of SO3.

[0009] The second aspect of this invention provides a method for preparing a broadband low-loss manganese-zinc-magnesium ferrite material, comprising the following steps: S1 Batching: preparing main component raw materials and secondary component raw materials by mass percentage; S2 Mixing and pre-firing: wet mixing the main component raw materials in step S1 followed by pre-firing to obtain a pre-firing mixture; S3 Sand milling and granulation: adding the secondary component raw materials prepared in step S1 to the pre-firing mixture obtained in step S2, and performing wet milling to obtain a ferrite slurry; adding a binder to the ferrite slurry, and then performing spray granulation to obtain granulated powder; S4 Molding: pressing the granulated powder obtained in step S3 into a molded body of a preset shape under a preset pressure; S5 Sintering: sintering the molded body obtained in step S4 in an oxygen atmosphere with an oxygen partial pressure concentration ≤0.3%; after sintering, cooling under a protective gas atmosphere to obtain the broadband low-loss manganese-zinc-magnesium ferrite material.

[0010] Furthermore, in step S2, the pre-firing temperature is 850~1050℃, and the pre-firing time is 1~6h.

[0011] Furthermore, in step S2, the mixing medium for wet mixing is water, and the wet mixing time is 1~3 hours.

[0012] Furthermore, in step S3, the grinding medium for wet grinding is water, and the wet grinding time is 1~3 hours.

[0013] Further, in step S3, the adhesive is a mixture selected from one or more of polyvinyl alcohol, carboxymethyl cellulose and polyvinyl acetate, and the amount of the adhesive is 0.5% to 1.5% on a dry powder basis.

[0014] Furthermore, in step S5, the sintering temperature is 1200~1300℃ and the sintering time is 3~10h.

[0015] Furthermore, in step S5, the protective gas is N2 or Ar.

[0016] A third aspect of this invention provides an application of a broadband, low-loss manganese-zinc-magnesium ferrite material, which is used to fabricate toroidal magnetic cores, exhibiting a loss ≤350kW / m at 100℃ and 100kHz / 200mT. 3 Loss at 500kHz / 50mT ≤200kW / m 3 .

[0017] Due to the application of the above technical solutions, the present invention has the following advantages compared with the prior art: The wideband low-loss manganese zinc magnesium ferrite material of the present invention, by adding a specific amount of MgO to the main component of manganese zinc ferrite, partially replaces Mn ferrite with Mg ferrite, thereby increasing the resistivity of the composite ferrite and reducing eddy current loss, overcoming the problem of high high frequency loss of traditional Mn-Zn ferrite, and realizing wideband low loss of the material.

[0018] This invention strictly controls the content of byproducts such as CaO, SiO2, Ta2O5, and Na2O, causing them to accumulate in the grain boundary region. This effectively increases the grain boundary resistivity, further suppresses eddy current losses, and reduces total losses. If the content of byproducts is below the lower limit set by this invention, the grain boundary resistivity cannot be sufficiently increased, making it difficult to achieve the loss reduction effect; if it exceeds the upper limit, it is easy to cause abnormal grain growth, which in turn leads to a deterioration in loss performance.

[0019] Furthermore, the present invention further limits the sulfur content in the raw materials to prevent it from reacting with calcium in the form of sulfate to form CaSO4 and segregating at the grain boundaries, thereby preventing uneven distribution of calcium at the grain boundaries, ensuring the integrity and uniformity of the grain boundary structure, and effectively suppressing the increase in eddy current loss caused by sulfur.

[0020] Furthermore, the preparation method provided by this invention has good process compatibility and can be seamlessly integrated with existing soft magnetic ferrite preparation processes. By precisely controlling the temperature and oxygen partial pressure during the sintering process, the material's loss performance is further optimized. Specifically, below 700°C, if the oxygen partial pressure is too low, it is not conducive to the full discharge of the binder and also increases costs due to the need to introduce protective gas in advance; while above 700°C, excessively high oxygen partial pressure will hinder the completion of the solid-phase reaction of the sintered body, resulting in insufficient densification, increased porosity, and ultimately a decrease in loss performance. Attached Figure Description

[0021] The following sections will describe some specific embodiments of the invention in a detailed manner by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or components. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings: Figure 1 is an X-ray diffraction (XRD) pattern of the broadband low-loss manganese-zinc-magnesium ferrite material of the present invention. Detailed Implementation

[0022] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] The broadband, low-loss manganese-zinc-magnesium ferrite material disclosed in this invention comprises a main component and secondary components. In molar percentage, the main component includes 50.5–58.5 mol% Fe₂O₃, 5.0–14.0 mol% ZnO, and 0.1–0.5 mol% MgO, with the balance being MnO. By adding a specific amount of MgO to the main component, the defect of decreased saturation magnetic flux density in ferrite materials due to excessive MgO is overcome, and the problem of high high-frequency loss in Mn ferrites is also overcome.

[0024] The secondary components, based on the total weight of the main components, include 300–800 ppm CaO, 50–300 ppm SiO2, 100–400 ppm Ta2O5, and 10–30 ppm Na2O. In this example, by precisely controlling the content of these secondary components, they can be enriched at the grain boundaries, effectively increasing grain boundary resistivity, suppressing eddy current effects, and reducing total losses. When the content of the secondary components is below the lower limit, it cannot sufficiently increase the grain boundary resistivity, resulting in limited loss reduction; while when its content exceeds the upper limit, it can easily cause abnormal grain growth, leading to a deterioration in loss performance.

[0025] In addition, the byproducts in this example include ≤300ppm of SO3. Sulfur in the raw materials usually exists in the form of sulfate ions, which readily combine with calcium to form CaSO4 and segregate at the grain boundaries, causing uneven calcium distribution in the grain boundary region, thereby increasing eddy current losses. By limiting the sulfur content, such adverse effects can be effectively avoided, ensuring that the material has stable and reliable loss characteristics.

[0026] The preparation method of the above-mentioned broadband low-loss manganese zinc magnesium ferrite material includes the following steps: S1 Batching: Prepare main component raw materials and secondary component raw materials by mass percentage; S2 Mixing and pre-firing: Wetly mix the main component raw materials in step S1 and then pre-firing to obtain a pre-firing mixture; S3 Sand milling and granulation: Add the secondary component raw materials prepared in step S1 to the pre-firing mixture obtained in step S2, and perform wet milling to obtain a ferrite slurry; add a binder to the ferrite slurry, and then perform spray granulation to obtain granulated powder; S4 Molding: Press the granulated powder obtained in step S3 into a molded body of a preset shape under a preset pressure; S5 Sintering: Place the molded body obtained in step S4 in an oxygen atmosphere with an oxygen partial pressure concentration ≤0.3% for sintering; after sintering, cool under a protective gas atmosphere to obtain the broadband low-loss manganese zinc magnesium ferrite material.

[0027] In step S2, the pre-firing temperature is 850~1050℃ and the pre-firing time is 1~6h.

[0028] In step S2, the mixing medium for wet mixing is water, and the wet mixing time is 1~3 hours.

[0029] In step S3, the grinding medium for wet grinding is water, and the wet grinding time is 1~3 hours.

[0030] In step S3, the adhesive is a mixture selected from one or more of polyvinyl alcohol, carboxymethyl cellulose and polyvinyl acetate, and the amount of adhesive used is 0.5% to 1.5% on a dry powder basis.

[0031] In step S5, the sintering temperature is 1200~1300℃ and the sintering time is 3~10h.

[0032] In step S5, the protective gas is N2 or Ar.

[0033] The aforementioned broadband, low-loss manganese-zinc-magnesium ferrite material can be used to fabricate toroidal magnetic cores, producing standard cores with a diameter of Φ25×15×8. At 100℃, the loss at 100kHz / 200mT is ≤350kW / m. 3 Loss at 500kHz / 50mT ≤200kW / m 3 The X-ray diffraction (XRD) spectrum of the broadband low-loss manganese zinc magnesium ferrite material of this invention is shown in Figure 1.

[0034] The present invention will be further described below with reference to specific embodiments. Embodiments

[0035] This embodiment provides a broadband low-loss manganese zinc magnesium ferrite material and its preparation method, including the following steps: (1) According to the chemical composition shown in Table 1, weigh the oxides Fe2O3, MnO (calculated as Mn3O4), ZnO and MgO as the main components and perform wet grinding in a sand mill for 1 hour (the grinding medium is water), and then pre-calcine at 900°C for 3 hours; based on the mass of the pre-calcined powder, add the secondary components shown in Table 1 to the pre-calcined material, wherein Na2O is converted to Na2CO3 and added, and perform secondary sand milling for 3 hours (wet grinding, the grinding medium is water); then add polyvinyl alcohol (1.0% based on dry powder) and perform spray granulation ( (1) Control the inlet temperature to 300℃ and the outlet temperature to 100℃ to obtain the molded body; (2) Sinter the molded body: During the sintering process, the first heating stage: the temperature is first raised from room temperature to 700℃ at a rate of 2.0℃ / min, and the heating is carried out in an atmospheric atmosphere; the second heating stage: the temperature is raised from 700℃ to 1250℃ at a rate of 1.0℃ / min, and the oxygen partial pressure is maintained at 0.3% during the heating stage; then it is kept at 1250℃ for 5 hours, and the oxygen partial pressure is maintained at 5.0%; finally, it is cooled to room temperature under the protection of N2 while maintaining the equilibrium oxygen partial pressure, and a broadband low-loss manganese zinc magnesium ferrite material is obtained.

[0036] The broadband low-loss manganese zinc magnesium ferrite material prepared above was used to make a standard magnetic core with a diameter of Ф25×15×8. Then, the power loss of the magnetic core at 100℃ was tested using a SY8219 BH analyzer. The results are shown in Table 1.

[0037] Table 1

[0038] As shown in Table 1, when both the principal and secondary components are within the scope of this invention, the magnetic core exhibits low losses at both 100kHz and 500kHz test frequencies, achieving wideband low-loss material performance. When the principal and secondary components deviate from the scope of this invention, the losses worsen, verifying the rationality and necessity of the component design in this invention.

[0039] The broadband low-loss manganese zinc magnesium ferrite material disclosed in this invention, by adding a specific amount of MgO to the main component, partially replaces Mn ferrite with Mg ferrite. After replacement, the resistivity of the composite ferrite is improved, the eddy current loss is reduced, and the problem of high high-frequency loss of Mn ferrite is overcome.

[0040] The broadband, low-loss manganese-zinc-magnesium ferrite material disclosed in this invention improves grain boundary resistivity and reduces eddy current loss by controlling the sulfur content in the raw materials to ensure uniform distribution of calcium at the grain boundaries. When the sulfur content in the raw materials is too high, it reacts with calcium to form CaSO4, resulting in grain boundary segregation, uneven distribution of calcium at the grain boundaries, and deterioration of losses.

[0041] The broadband, low-loss manganese-zinc-magnesium ferrite material of this invention was used to prepare a standard magnetic core with a diameter of Φ25×15×8. Its loss at 100℃ and 100kHz / 200mT is ≤350kW / m. 3 Loss at 500kHz / 50mT ≤200kW / m 3 .

[0042] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A broadband, low-loss manganese-zinc-magnesium ferrite material, comprising a main component and secondary components, characterized in that, The main components, by molar percentage, include 50.5-58.5 mol% Fe2O3, 5.0-14.0 mol% ZnO, 0.1-0.5 mol% MgO, with the balance being MnO. The secondary components, by weight of the main components, include 300-800 ppm CaO, 50-300 ppm SiO2, 100-400 ppm Ta2O5, and 10-30 ppm Na2O.

2. The broadband low-loss manganese-zinc-magnesium ferrite material according to claim 1, characterized in that, The secondary components, based on the total weight of the main components, also include ≤300ppm of SO3.

3. The method for preparing the broadband low-loss manganese-zinc-magnesium ferrite material according to any one of claims 1 to 2, characterized in that, The process includes the following steps: S1 Batching: Prepare the main component raw materials and secondary component raw materials by mass percentage; S2 Mixing and Pre-firing: Wetly mix the main component raw materials in step S1 and then pre-firing them to obtain a pre-firing mixture; S3 Sand Milling and Granulation: Add the secondary component raw materials prepared in step S1 to the pre-firing mixture obtained in step S2, and perform wet milling to obtain a ferrite slurry; Add a binder to the ferrite slurry, and then perform spray granulation to obtain granulated powder; S4 Molding: Under a preset pressure, the granulated powder obtained in step S3 is pressed into a molded body of a preset shape; S5 Sintering: The molded body obtained in step S4 is placed in an oxygen atmosphere with an oxygen partial pressure concentration ≤0.3% for sintering; After sintering, it is cooled under a protective gas atmosphere to obtain the broadband low-loss manganese zinc magnesium ferrite material.

4. The method for preparing the broadband low-loss manganese-zinc-magnesium ferrite material according to claim 3, characterized in that, In step S2, the pre-firing temperature is 850~1050℃ and the pre-firing time is 1~6h.

5. The method for preparing the broadband low-loss manganese-zinc-magnesium ferrite material according to claim 3, characterized in that, In step S2, the mixing medium for wet mixing is water, and the wet mixing time is 1 to 3 hours.

6. The method for preparing the broadband low-loss manganese-zinc-magnesium ferrite material according to claim 3, characterized in that, In step S3, the grinding medium for wet grinding is water, and the wet grinding time is 1 to 3 hours.

7. The method for preparing the broadband low-loss manganese-zinc-magnesium ferrite material according to claim 3, characterized in that, In step S3, the adhesive is a mixture selected from one or more of polyvinyl alcohol, carboxymethyl cellulose and polyvinyl acetate, and the amount of the adhesive is 0.5% to 1.5% on a dry powder basis.

8. The method for preparing the broadband low-loss manganese-zinc-magnesium ferrite material according to claim 3, characterized in that, In step S5, the sintering temperature is 1200~1300℃ and the sintering time is 3~10h.

9. The method for preparing the broadband low-loss manganese-zinc-magnesium ferrite material according to claim 3, characterized in that, In step S5, the protective gas is N2 or Ar.

10. The application of the broadband low-loss manganese-zinc-magnesium ferrite material according to any one of claims 1 to 2, characterized in that, The broadband, low-loss manganese-zinc-magnesium ferrite material is used to fabricate toroidal magnetic cores, with a loss ≤350kW / m at 100℃ and 100kHz / 200mT. 3 Loss at 500kHz / 50mT ≤200kW / m 3 .

Images