High-mechanical-property low-loss high-frequency manganese-zinc power ferrite and preparation method thereof

Abstract

The invention discloses a high-mechanical-property low-loss high-frequency manganese-zinc power ferrite and a preparation method, and relates to the technical field of soft magnetic ferrite materials. The high-mechanical-property low-loss high-frequency manganese-zinc power ferrite is composed of main components and auxiliary components; the main components comprise, in terms of oxide, 53.5 to 56.5 mol% of Fe2O3, 3.5 to 5.5 mol% of ZnO, and 38.0 to 43.0 mol% of MnCO3; the auxiliary components comprise 0.01-0.03 wt% of nano yttrium iron garnet, 0.01-0.03 wt% of nano yttrium iron garnet, 0.01-0.03 wt% of nano yttrium iron garnet, 0.01-0.03 wt% of nano yttrium iron garnet and 0.01-0.03 wt% of nano yttrium iron garnet, caSiO3: 0.01 wt% to 0.05 wt%; the content of Nb2O5 is 0.01 to 0.04 weight percent; ho2O3: 0.1 wt% to 0.8 wt%; and Co2O3: 0.1 to 0.3 wt%. On the basis of improving the bending strength, the eddy-current loss is reduced, and the high-frequency low-loss high-bending-strength cable has high bending strength and high-frequency low-loss performance.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of soft magnetic ferrite materials, in particular to a manganese-zinc (MnZn) power ferrite suitable for megahertz (MHz) frequency and having high mechanical strength and low power loss and a preparation method thereof. BACKGROUND

[0002] With the application of the third generation semiconductor (such as SiC and GaN) technology in switching power supplies, the working frequency of the power supply has been extended to the MHz range, which puts forward higher requirements for magnetic materials. In order to meet the development trend of high frequency miniaturization, high power and high reliability of the power supply, the MnZn power ferrite must have excellent mechanical properties (such as high bending strength) in addition to high current resistance, low high-frequency loss and high saturation magnetic flux density (Bs) in order to withstand assembly stress and thermal stress, facilitate precision processing (such as cutting, grinding and punching) and improve reliability.

[0003] At present, the main technical routes for improving the performance of MnZn ferrite include main formula optimization, sintering process control and micro additive doping. Common additives such as CaO, SiO2, V2O5, MoO3 and Bi2O3 mainly play a role through mechanisms such as forming a high-resistance grain boundary layer, promoting liquid phase sintering or refining grains. However, these traditional additives have obvious performance bottlenecks: excessive SiO2 will form a continuous grain boundary phase, leading to abnormal grain growth and deterioration of magnetic properties; MoO3 is easy to volatilize at high temperatures, introducing pores and defects; although V2O5 can promote sintering, excessive addition will significantly reduce the saturation magnetization. More importantly, these additives can only optimize a certain specific performance, and it is difficult to achieve the dual goals of high frequency low loss and high mechanical strength, and there is a technical dilemma of "trade-off".

[0004] In the high frequency application scenario of MHz level, MnZn ferrite faces two key technical challenges: one is that the eddy current loss increases exponentially with the increase of frequency, and the other is that the mechanical strength is insufficient due to the small size of the magnetic core required by high frequency use, which easily leads to low processing yield and short service life. The eddy current loss is directly related to the grain boundary resistivity of the material, and the mechanical strength depends on the microstructure characteristics of the material, such as grain size, porosity and grain boundary bonding force. The existing technology attempts to balance these performances by using multiple additives in combination (such as CaCO3-SiO2-MoO3 synergistic doping), but the effect is limited. The main reason is that different additives may have mutual restriction or even opposing effects. For example, CaCO3-SiO2 added to reduce loss will reduce the sintering activity, resulting in a decrease in density; and Bi2O3 added to increase density may form too much liquid phase, causing abnormal grain growth. This "trade-off" situation has become the main bottleneck for the development of high frequency MnZn power ferrite technology.

[0005] Yttrium iron garnet (Y3Fe5O 12 12) is a ferrite material with a cubic garnet structure, known for its excellent magnetic properties. YIG has extremely low magnetic loss, high resistivity, and thermal stability in the microwave frequency range. These characteristics make YIG widely used in microwave devices, magneto-optical devices, and spintronics. When the size of YIG is reduced to the nanoscale (20-100 nm), it exhibits unique surface effects and small-size effects, such as higher surface energy and enhanced interface interactions. Studies have shown that nano-YIG powder can be prepared by sol-gel method, chemical co-precipitation method, etc., and its magnetic properties (such as saturation magnetization) are closely related to the particle size. The introduction of nano-YIG as an additive into MnZn power ferrite to simultaneously control its microstructure and improve mechanical properties and high-frequency magnetic properties has not been reported. The present invention proposes the use of nano-YIG as a key additive, combined with calcium silicate (CaSiO3) and holmium oxide (Ho2O3), to solve the technical problem of balancing high-frequency MnZn ferrite loss and mechanical strength. The innovation of this technical approach lies in the following aspects: Multi-performance synergistic improvement: Traditional additives can only optimize a specific performance, while nano-YIG achieves a synergistic improvement of mechanical properties and magnetic properties through its unique physical and magnetic properties. Experimental results show that the addition of appropriate amounts of nano-YIG (0.02-0.03wt%) can increase the bending strength to 5.86MPa, while reducing the power loss under the condition of 2MHz / 50mT to 943-1429kW / m 3 (25-120℃), solving the contradiction between high mechanical strength and low high-frequency loss in traditional technology.

[0006] Cross-border integration of technical approach: The present invention creatively applies YIG material, originally used in microwave devices and spintronics, to power ferrite, achieving cross-border integration of different technical fields. This cross-border application not only brings performance breakthroughs but also provides new ideas for the design of soft magnetic materials.

[0007] Fine regulation of interface engineering: The use of calcium silicate (CaSiO3) to combine calcium oxide (CaO) and silicon dioxide (SiO2) high resistivity and refine the grain size, combined with high melting point holmium oxide (Ho2O3) enriched in the grain boundary, forms uniform and small grain size / high resistance grain boundaries, reducing high-frequency eddy current loss in the MHz frequency range and improving mechanical properties. At the same time, the use of nanometer YIG with ferrimagnetic properties forms a unique interface structure at the MnZn ferrite grain boundary, providing good electrical insulation and maintaining excellent magnetic coupling. This interface engineering achieves a synergistic regulation of the electrical transport and spin wave transport properties of the material, significantly reducing the eddy current loss and magnon scattering at high frequencies. SUMMARY

[0008] The technical problem solved by the present application is to provide a high-mechanical-property low-loss MnZn power ferrite applied to MHz frequency bands and a preparation method, which optimizes the formula by doping nano YIG, calcium silicate (CaSiO3) and holmium trioxide (Ho2O3), reduces eddy current loss on the basis of improving bending strength, and has high bending strength and high-frequency low-loss performance.

[0009] The technical solution adopted by the present application to solve the technical problem is that the high-mechanical-property low-loss high-frequency MnZn power ferrite is composed of main components and auxiliary components; characterized in that, in terms of oxides, the molar percentage composition of the main components is: Fe2O3: 53.5-56.5 mol%, ZnO: 3.5-5.5 mol%, MnCO3: 38.0-43.0 mol%; in terms of the total mass of the pre-sintered material obtained after pre-sintering of the main components, the auxiliary components include: nano yttrium iron garnet: 0.01-0.03 wt%; CaSiO3: 0.01-0.05 wt%; Nb2O5: 0.01-0.04 wt%; Ho2O3: 0.1-0.8 wt%; Co2O3: 0.1-0.3 wt%.

[0010] Further, the molar percentage composition of the main components is: Fe2O3: 54.5 mol%, ZnO: 4.5 mol%, MnCO3: 41.0 mol%.

[0011] The content of the auxiliary components is: nano yttrium iron garnet: 0.03 wt%, CaSiO3: 0.03 wt%, Nb2O5: 0.03 wt%, Ho2O3: 0.5 wt%, Co2O3: 0.25 wt%.

[0012] The nano yttrium iron garnet has a particle size range of 20-100 nm, a ferromagnetic resonance line width ΔH lower than 80 Oe, and a 4πMs not lower than 1500 Gauss.

[0013] The present application also provides a preparation method of the high-mechanical-property low-loss high-frequency MnZn power ferrite, characterized by comprising the following steps: Step 1, batching: Fe2O3, ZnO and MnCO3 are used as raw materials, and the proportions are: 53.5-56.5 mol% of Fe2O3, 3.5-5.5 mol% of ZnO, and 38.0-43.0 mol% of MnCO3; Step 2, primary ball milling: The raw materials weighed in step 1 are subjected to primary ball milling, and then dried and sieved to obtain a primary-milled powder; Step 3, pre-sintering: The primary-milled powder obtained in step 2 is subjected to pre-sintering in an air atmosphere, the pre-sintering temperature is 800-1000℃, the pre-sintering time is 2-4 hours, and after the pre-sintering is completed, the pre-sintered material is sieved to obtain a pre-sintered material; Step 4, doping: The pre-sintered material is added with auxiliary components to obtain a mixed powder, and the mass of the pre-sintered material obtained in step 3 is taken as a reference, and the auxiliary components include: nano yttrium iron garnet: 0.01-0.03wt%, CaSiO3: 0.01-0.05wt%, Nb2O5: 0.01-0.04wt%, Ho2O3: 0.1-0.8wt%, Co2O3: 0.1-0.3wt%; Step 5, secondary ball milling: The mixed powder obtained in step 4 is subjected to secondary ball milling, and then dried to obtain a secondary-milled powder; Step 6, granulation: The secondary-milled powder obtained in step 5 is subjected to granulation and dried to obtain a granulated material; Step 7, hydraulic forming: The granulated material obtained in step 6 is extruded and formed in a hydraulic machine to obtain a green body; Step 8, sintering: The green body obtained in step 7 is subjected to segmented sintering to obtain the MnZn power ferrite; wherein the process of segmented sintering is as follows: First stage: after the green body is put in, the temperature is raised to 500-600℃ in an air atmosphere; Second stage: continue to raise the temperature to 1100-1200℃; Third stage: keep the temperature at 1100-1200℃ for 6 hours, and adjust the oxygen partial pressure to 1-3%; Fourth stage: reduce the temperature from 1100-1200℃ to 500℃, and reduce the oxygen partial pressure from 1-3% to 0%; then, in a pure nitrogen atmosphere, the temperature is naturally cooled from 500℃ to room temperature.

[0014] In the step 2, the ball milling time is 2-3 hours; in step 5, the ball milling time of secondary ball milling is 3-5 hours.

[0015] The maximum bending strength of the MnZn power ferrite of the application reaches 5.86MPa; the saturation magnetic induction strength B s>501mT (25℃), 426mT (100℃), loss 208~463kw / m at 1MHz, 50mT 3 (25~120℃); loss 943~1429kw / m at 2MHz, 50mT 3 (25~120℃).

[0016] The preparation method of the application optimizes the formula of doping nano YIG (i.e. nano yttrium iron garnet, Y3Fe5O 12 12), calcium silicate (CaSiO3) and diholmium trioxide (Ho2O3), reduces the eddy current loss on the basis of improving the bending strength, and prepares the MnZn power ferrite with high bending strength and high-frequency low-loss performance.

[0017] The significant advantages and outstanding creativity of the application are: (1) the introduction of nano YIG and the new concept of "phonon-magnon synergistic effect" The application creatively introduces the nano-scale YIG (particle size 20-100nm) with ferrimagnetism as functional additives into the MnZn ferrite system. YIG itself is a ferromagnetic insulator, has extremely high resistivity (about 1×10 10~12 Ω·cm) and narrow ferromagnetic resonance line width, and is an ideal material in the field of high-frequency microwave and spin electronics. When its size is reduced to nanoscale and uniformly dispersed in the MnZn ferrite matrix, not only as inert second-phase particles, but also actively interacts with the matrix, producing a new "phonon-magnon synergistic effect".

[0018] 1.1 Phonon localization and mechanical enhancement (phonon level): Nano YIG particles have high melting point (about 1555℃) and high hardness (Mohs hardness 6.5-7.0). In the sintering process, these high-stability, high-strength nanoparticles can effectively pin the grain boundaries, inhibit the abnormal growth of MnZn ferrite grains, and promote the formation of fine and uniform microstructure (see Figure 2 and Figure 1 Comparison). According to the Griffith-Irwin theory, the fracture of a material depends not only on its own strength (such as yield strength), but also on the size and shape of its internal defects (cracks), and the ability of the material to resist crack propagation (fracture toughness). Grain refinement is a key factor to improve the bending strength of ceramic materials. The use of calcium silicate (CaSiO3) and diholmium trioxide (Ho2O3) refines the grains, and the introduction of nano YIG helps to further reduce the porosity of the sintered body and improve the density (data in Table 3 confirms), thereby jointly promoting the significant improvement of the bending strength of the material (up to 5.86MPa in Example 2).

[0019] 1.2 Suppression of Magneton Scattering and Reduction of High-Frequency Loss (Magneton Level): Calcium silicate (CaSiO3) and holmium trioxide (Ho2O3) are effective measures to improve resistivity, but both are non-magnetic, which easily leads to a decrease in magnetic properties. However, YIG, which is subferromagnetic like MnZn ferrite, is an excellent magneton (spin wave) conduction material. Nano-YIG particles are enriched at the grain boundaries of MnZn ferrite, and their inherent high resistivity characteristics (1×10⁻⁶) contribute to this. 10~12 The nanometer-sized YIG (Ω·cm) structure significantly improves grain boundary resistance, effectively suppressing eddy current losses in the MHz band. More importantly, the specific interface formed between the nano-YIG and the matrix positively influences magneton transport, helping to suppress magneton scattering at high frequencies and further reducing magnetic losses. This strategy of simultaneously optimizing charge transport and spin wave transport by introducing specific nanostructures is the core innovation of this invention.

[0020] (2) Compensation for magnetocrystalline anisotropy and optimization of temperature stability The magnetocrystalline anisotropy constant (K1) and magnetostriction coefficient (λs) of MnZn ferrite vary with temperature, and the temperature point corresponding to its zero point (K1=0) determines the temperature region with the lowest loss. YIG is the ferrite with the lowest magnetocrystalline anisotropy. The addition of nano-YIG, along with the synergistic effect of Co2O3 in the auxiliary components, can finely compensate for the effective magnetocrystalline anisotropy of the material. This compensation effect helps to broaden the low-loss temperature plateau, enabling the material to maintain low high-frequency power loss (e.g., ...) over a wide temperature range from 25℃ to 120℃. Figures 5 to 7 As shown in the figure, it meets the stringent requirements of modern switching power supplies for temperature stability.

[0021] (3) The essential difference between the present invention and conventional additives in the prior art: Traditional performance-enhancing additives, such as SiO2, CaO, and V2O5, typically function by forming high-resistivity grain boundaries, promoting liquid-phase sintering, or refining grains. However, these additives often have limited functionality, and excessive addition can lead to side effects (such as abnormal grain growth due to excessive SiO2), negatively impacting mechanical and magnetic properties. This invention uses calcium silicate (CaSiO3) and holmium trioxide (Ho2O3) to refine grains and form a high-resistivity layer. More importantly, nano-YIG is a functional additive with intrinsically strong magnetic properties. It is not merely a physical barrier or flux, but actively participates in and optimizes the microstructure evolution and high-frequency magnetization dynamics of the material during sintering through its unique magnetic properties and nanoscale effect, achieving a synergistic improvement in both mechanical and magnetic properties—something no single additive could previously achieve.

[0022] (4) Significant improvement in performance indicators The material has a loss of 943-1429 kW / m under the condition of 2 MHz and 50 mT 3 The bending strength is up to 5.86 MPa, the saturation magnetic induction Bs@25 DEG C is greater than 500 mT, and the comprehensive performance is better than that of the prior art.

[0023] (5) Precise control of the preparation process and compatibility The preparation method provided by the application is based on mature traditional ceramic process, and the addition amount (0.01-0.03 wt%) of nano YIG and the optimized four-stage sintering process (especially the oxygen partial pressure control in the third stage) are precisely controlled, so that the nano YIG can fully play its positive role without introducing negative effects. The method does not require special or expensive equipment, and the process is stable and easy to realize industrialization, which has significant economic benefits and application prospect.

[0024] The core innovation points of the application compared with the prior art are as follows: BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The SEM photo of the fracture of the ferrite obtained for Comparative Example 2 (without adding nano YIG).

[0026] Figure 2 The SEM photo of the fracture of the ferrite obtained for Example 2 (adding 0.02 wt% nano YIG).

[0027] Figure 3 The SEM photo of the fracture of the ferrite obtained for Example 5 (adding 0.07 wt% nano YIG).

[0028] Figure 4 The bending strength comparison chart of the ferrite materials of the examples and the comparative example.

[0029] Figure 5 The power loss temperature characteristic curve chart of the ferrite materials of Example 1 and Comparative Example 2 under the condition of 1 MHz and 50 mT.

[0030] Figure 6 The power loss temperature characteristic curve chart of the ferrite materials of Example 2 and Comparative Example 2 under the condition of 2 MHz and 50 mT.

[0031] Figure 7 The power loss temperature characteristic curve chart of the ferrite materials of Example 1 and Comparative Example 2 under the condition of 3 MHz and 30 mT. DETAILED DESCRIPTION

[0032] The technical solutions of the application will be described in detail below with reference to the drawings and examples.

[0033] The application provides a preparation method of a megahertz manganese-zinc power ferrite with high mechanical property and low loss, and the samples of examples 1-5 and comparative examples 1-2 are prepared through the following steps. Step 1, batching: Fe2O3, ZnO and MnCO3 are used as raw materials, and the raw materials are weighed according to the main component calculation of "54.5mol% of Fe2O3, 4.5mol% of ZnO and 41.0mol% of MnCO3"; Step 2, primary ball milling: The raw materials weighed in step 1 are placed in a planetary ball mill, and primary ball milling is performed for 2.5 hours, the ball milling medium is Ф5mm bearing steel, after the ball milling is completed, drying, and passing through a 40-mesh sieve, the primary-milled powder is obtained; Step 3, pre-sintering: The primary-milled powder obtained in step 2 is placed in a bell jar furnace, and pre-sintering is performed in an air atmosphere, the pre-sintering temperature is 920℃, the pre-sintering time is 4 hours, after the pre-sintering is completed, passing through a 40-mesh sieve, the pre-sintered powder is obtained; Step 4, doping: The mass of the pre-sintered material obtained in step 3 is used as a reference, and the auxiliary components shown in Table 1 are added to the pre-sintered material to obtain a mixed powder; Table 1 Component proportion (wt%)

[0034] In this step, taking nano YIG as an example, if the mass of the pre-sintered material obtained in step 3 is 100 grams, then the nano YIG added in example 1 is 0.01 grams, and the other components are the same.

[0035] Step 5, secondary ball milling: The mixed powder obtained in step 4 is placed in a planetary ball mill, and deionized water is added, ball milling for 5 hours, the ball milling medium is Ф5mm bearing steel, after the ball milling is completed, drying, and passing through a 40-mesh sieve, the secondary-milled powder is obtained; Step 6, granulation: PVA is added to the secondary-milled powder at a weight ratio of 11wt% for granulation, and drying is performed to obtain a granulated material with good fluidity; Step 7, hydraulic forming: The granulated material obtained in step 6 is placed in a mold, and extrusion forming is performed in a hydraulic machine to obtain a green part, the mold is a Ф14*8mm circular ring mold, and the extrusion pressure is 102MPa; Step 8, sintering: The green part obtained in step 7 is subjected to segmented sintering to obtain the manganese-zinc power ferrite; wherein, the process of segmented sintering is as follows: First stage: After placing the green blank in the air, the temperature is raised to 600℃ at a heating rate of 1.5℃ / min. Second stage: The temperature is increased to 1150℃ in air at a heating rate of 2.5℃ / min; The third stage: hold at a sintering temperature of 1150℃ for 6 hours, adjusting the oxygen partial pressure to 1.6% during the holding stage; The fourth stage: the cooling stage. The cooling process adopts the equilibrium oxygen partial pressure method to reduce the temperature from 1150℃ to 500℃, while the oxygen partial pressure is reduced from 1.6% to 0%. Then, under a pure nitrogen atmosphere, the temperature is naturally cooled from 500℃ to room temperature.

[0036] The mechanical properties of the samples, such as bending strength, were tested using a bending strength tester. The test results for Examples 1-5 and Comparative Examples 1-2 are shown in Table 2. Table 2 Test results of Examples 1-5 and Comparative Examples 1-2 Sample No. YIG content (wt%) Bending strength (MPa) Comparative Example 1 0.00% 3.42 Comparative Example 2 0.00% 3.68 Example 1 0.01% 4.47 Example 2 0.02% 5.86 Example 3 0.03% 4.87 Example 4 0.05% 3.14 Example 5 0.07% 2.61 The initial permeability μ of the sample was measured using a Tonghui TH2826LCR digital bridge. i The resistivity ρ was measured; the saturation magnetic induction intensity B of the sample was measured using an Iwasaki SY-8218BH analyzer. s Volumetric power loss P cv Tests were conducted; the sintering density d of the samples was measured using the weighing method. The test results of Examples 1-5 and Comparative Examples 1-2 are shown in Table 3: Table 3 Test results of Examples 1-5 and Comparative Examples 1-2

[0037] Results analysis: Microstructure: Comparison Figure 1 and Figure 2 As can be seen, the addition of 0.02 wt% nano-YIG (Example 2) resulted in... Figure 2 The sample grain size was significantly refined, the distribution was uniform, and the porosity was significantly reduced. However, excessive addition (Example 5) resulted in a significantly finer grain size, more uniform distribution, and a significantly reduced porosity. Figure 3 This leads to uneven tissue distribution. Figure 1 Here is a SEM image of the natural cross-section of MnZn ferrite in Comparative Example 2; from Figure 1 It can be seen that the sample obtained without the addition of nano-YIG in Comparative Example 2 has a grain size between 2.5 and 12 μm (average size 6 μm), with many pores and unevenness. Figure 2 Here is a SEM image of the natural cross-section of MnZn ferrite from Example 2; Figure 2 It can be seen that the sample obtained by adding 0.02wt% nano YIG in Example 2 has a grain size between 2 and 10 μm (average size 4.6 μm), fewer pores, and finer and more uniform grains. Figure 3SEM image of natural fracture of MnZn ferrite of Example 5; from Figure 3 It can be seen that the sample of Example 5 with 0.07wt% nano-YIG has increased pores and uneven grain size between 2.5-13μm (average size 6μm). Figures 1 to 3 It is shown that appropriate nano-YIG doping can improve the microstructure of MnZn power ferrite, refine the grain, reduce the pores, and improve the grain uniformity.

[0038] Mechanical properties: Compared with Comparative Example 2 using calcium silicate (CaSiO3) and holmium trioxide (Ho2O3) and Comparative Example 1 using conventional CaO and SiO2, the bending strength has been improved. On this basis, if Figure 4 and Table 2, with the addition of nano-YIG increasing to 0.02wt% (Example 2), the bending strength reaches a peak of 5.86MPa, confirming the significant effect of nano-YIG on strengthening materials. Figure 4 Mechanical property characteristic curve of MnZn ferrite material prepared in Examples 1-5 and Comparative Example 2; from Figure 4 It can be seen that the sample of Example 1 with 0.01wt% nano-YIG can effectively improve the mechanical properties of MnZn ferrite material, and the sample of Example 2 with 0.02wt% nano-YIG obtains the maximum mechanical properties, and the mechanical properties decrease with further addition.

[0039] Magnetic properties: Two phenomena must be noted: first, compared with Comparative Example 1 using conventional CaO and SiO2, Comparative Example 2 using calcium silicate (CaSiO3) and holmium trioxide (Ho2O3) has improved permeability and reduced high-frequency loss; second, the permeability is further increased after using nano-YIG. Examples 1, 2 and 3 all exhibit much lower power loss (Table 3, Figures 5 to 7 ) than Comparative Example 2 in a wide temperature range (25-120℃) and a wide frequency band (1-3MHz), while maintaining a high saturation magnetic induction (Example 3 B s >500mT@25℃). Figure 5 、 7 Temperature characteristic curve of total loss Pcv (kw / m 3 ,1MHz50mT) and Pcv (kw / m 3 ,3MHz30mT) of MnZn ferrite material prepared in Example 1 and Comparative Example 2; Figure 6 Temperature characteristic curve of total loss Pcv (kw / m 3The temperature characteristic curve of the MnZn ferrite material (50mT, 2MHz) is shown in Table 3; it can be seen from Table 3 that the addition of 0.02-0.03wt% nano YIG can effectively reduce the loss of the MnZn ferrite material at high frequency; when 0.02wt% nano YIG is added in Example 2, the sintering density and resistivity of the MnZn ferrite material reach the maximum values.

[0040] The present application successfully prepares the MnZn power ferrite with high bending strength and low high-frequency loss by introducing nano YIG with a specific content, synergizing calcium silicate (CaSiO3) and other additives such as holmium trioxide (Ho2O3), which can meet the harsh requirements of MHz-level high-frequency high-power switching power supply on magnetic materials. The introduction of nano YIG not only solves the technical problem that the traditional additive system is difficult to balance the mechanical properties and magnetic properties, but also realizes the synergistic optimization of material properties through the "magnon-phonon synergistic effect", which has important technical innovation value and industrialization prospect.

Claims

1. A high-performance, low-loss, high-frequency manganese-zinc power ferrite, composed of a main component and auxiliary components; characterized in that, The main component, calculated as oxides, has the following molar percentage composition: Fe2O3: 53.5~56.5 mol%, ZnO: 3.5~5.5 mol%, MnCO3: 38.0~43.0 mol%; Based on the total mass of the pre-fired material obtained after pre-firing the main component as 100%, the auxiliary components include: Nano-yttrium iron garnet: 0.01~0.03wt%; CaSiO3: 0.01~0.05wt% Nb₂O₅: 0.01~0.04wt% Ho2O3: 0.1~0.8wt% Co2O3: 0.1~0.3wt%.

2. The high-performance, low-loss, high-frequency manganese-zinc power ferrite according to claim 1, characterized in that, The molar percentage composition of the main components is: Fe2O3: 54.5 mol%, ZnO: 4.5 mol%, MnCO3: 41.0 mol%.

3. The high-performance, low-loss, high-frequency manganese-zinc power ferrite according to claim 1 or 2, characterized in that, The content of the auxiliary components is as follows: nano-yttrium iron garnet: 0.03wt%, CaSiO3: 0.03wt%, Nb2O5: 0.03wt%, Ho2O3: 0.5wt%, Co2O3: 0.25wt%.

4. The high-mechanical-performance, low-loss, high-frequency manganese-zinc power ferrite according to claims 1-4, characterized in that, The nano-yttrium iron garnet has a particle size range of 20~100nm, a ferromagnetic resonance linewidth ΔH of less than 80 Oersted (Oe), and a 4πMs of not less than 1500 Gauss.

5. A method for preparing high-mechanical-performance, low-loss, high-frequency manganese-zinc power ferrite, characterized in that, Includes the following steps: Step 1, Ingredients: Using Fe2O3, ZnO and MnCO3 as raw materials, the proportions are: 53.5~56.5 mol% Fe2O3, 3.5~5.5 mol% ZnO, and 38.0~43.0 mol% MnCO3; Step 2, First ball milling: The raw materials weighed in step 1 are ball-milled once, then dried and sieved to obtain a first-mill powder. Step 3, Preheating: The powder obtained in step 2 is pre-calcined in air at a temperature of 800-1000℃ for 2-4 hours. After pre-calcination, it is sieved to obtain the pre-calcined material. Step 4, Doping: Adding auxiliary components to the pre-fired material yields a mixed powder. Using the mass of the pre-fired material obtained in step 3 as a benchmark, the auxiliary components include: Nano-yttrium iron garnet: 0.01~0.03wt%, CaSiO3: 0.01~0.05wt%, Nb2O5: 0.01~0.04wt%, Ho2O3: 0.1~0.8wt%, Co2O3: 0.1~0.3wt% Step 5, Secondary ball milling: The mixed powder obtained in step 4 is subjected to secondary ball milling, and then dried to obtain secondary ball milled material; Step 6, Granulation: The secondary ball milling material obtained in step 5 is granulated and dried to obtain granulated material. Step 7, hydroforming: The granulated material obtained in step 6 is extruded and molded in a hydraulic press to obtain a green part; Step 8, Sintering: The green blank obtained in step 7 is sintered in segments to obtain the manganese-zinc power ferrite; wherein, the segmented sintering process is as follows: First stage: After placing the green blank in the air, raise the temperature to 500~600℃; Second stage: Continue to raise the temperature to 1100~1200℃; Third stage: Keep warm at 1100~1200℃ for 6 hours, and adjust the oxygen partial pressure to 1~3%; Fourth stage: The temperature is reduced from 1100~1200℃ to 500℃, and the oxygen partial pressure is reduced from 1~3% to 0%; then, under a pure nitrogen atmosphere, the temperature is naturally cooled from 500℃ to room temperature.

6. The method for preparing high-mechanical-performance, low-loss, high-frequency manganese-zinc power ferrite as described in claim 5, characterized in that, In step 2, the ball milling time is 2-3 hours; in step 5, the ball milling time for the second ball milling is 3-5 hours.

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