Direct current superimposed and wide temperature low loss mnzn ferrite and preparation method and application thereof

Abstract

The application discloses a DC superimposition-resistant and wide-temperature low-loss MnZn ferrite and a preparation method and application thereof. The MnZn ferrite main material is prepared according to the required raw material weight of 52.3-53.3 mol% of Fe2O3, 35.2-36.2 mol% of MnO, 0.12-0.18 mol% of TiO2 and the balance of ZnO; the additive is prepared by mixing 0.12-0.16 wt% of CaCO3, 0.02-0.04 wt% of SiO2, 0.03-0.04 wt% of V2O5, 0.12-0.18 wt% of Co2O3 and 0.1-0.3 wt% of SrTiO3 nano powder; the main material is put into a ball mill for primary ball milling mixing, and then is dried and pre-sintered; the pre-sintered powder and the additive are simultaneously put into the ball mill for secondary ball milling, and then are dried and granulated, and are formed into annular green bodies, and the ferrite is obtained by sintering the annular green bodies. The MnZn ferrite material with high DC superimposition resistance and low loss can be prepared, the initial permeability is 2933, the DC superimposition magnetic field value corresponding to a 70% reduction of the permeability is 200 A / m, the loss is lower than 330 kW / m μ70 at 100 kHz and 200 mT in the range of 25-100 DEG C. 3 ​

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic materials, in particular to a DC superimposed resistant MnZn ferrite, a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of power electronics technology, magnetic components such as filters, transformers and power inductors are widely used. MnZn ferrite has high resistivity, high initial permeability and low loss, and the ferrite core made of MnZn ferrite is the core component of these magnetic components. The performance of MnZn ferrite is closely related to the overall performance of the device, especially the loss of the core, which has a decisive influence on the efficiency and stability of the device. The performance of MnZn ferrite is closely related to the external environment. On the one hand, the MnZn ferrite core is often subjected to external magnetic field impact, such as the electromagnetic field radiated by other electromagnetic components during operation, which can reduce the magnetic permeability of the material and further reduce the inductance of the device; on the other hand, the loss of the core will change with the change of the external environment temperature. Under normal circumstances, with the increase of temperature, the loss-temperature characteristic curve of MnZn ferrite presents a "concave" curve, and the temperature corresponding to the minimum value of the loss curve is the most suitable working temperature of the material, at which the material loss is the lowest and the efficiency of the magnetic component is the highest. When the ambient temperature deviates from this temperature, the material loss will increase, and the efficiency of the magnetic component will decrease, thereby reducing the energy conversion efficiency of the switching power supply. This loss characteristic of MnZn ferrite seriously restricts its versatility in different temperature ranges. When designing the device, the corresponding MnZn ferrite material with loss-temperature characteristics can only be selected for different working temperatures of the device. This not only makes the MnZn ferrite material category diverse, increases the production cost, but also once the working temperature of the ferrite core deviates from its most suitable working temperature range, the core loss increases, the device efficiency decreases, and even a vicious cycle of "increasing loss-temperature increase-further increasing loss" occurs. With the development of integrated electronic devices, the working environment of MnZn ferrite core is becoming more and more severe. How to keep the core in good performance under complex electromagnetic and temperature environment and broaden the application range of MnZn ferrite is a difficult problem to be solved in the electronic information industry.

[0003] In the patent "Preparation method of medium-wide frequency wide temperature low-loss MnZn ferrite material" (CN 112573912A), CaCO3, SiO2, Nb2O5, ZrO2 and Co2O3 are used as additives, and the molar percentage of the main components is: Fe2O3 is 52.5-53.5mol%, ZnO is 8.8-9.8mol%, and MnO is the balance; according to the total weight of the main components, the content of each component of the additive auxiliary components is: CaCO3 is 0.04-0.06%, Nb2O5 is 0.02-0.03%, Co2O3 is 0.35-0.45%, ZrO2 is 0.01-0.03%, and SiO2 is 30-120ppm. The sintered ferrite grain size is controlled to realize grain refinement, and the loss caused by the dispersion of ferrite grain size is reduced, but this scheme is for a wide frequency range (100-500kHz), and the loss at medium frequency is still high. At 500kHz 100mT, the loss at 25-100℃ is more than 560kW / m 3 , and this patent does not control the direct current superposition characteristics. Therefore, the present application will further reduce the loss at medium frequency while improving the direct current superposition resistance of the material.

[0004] The patent "Low-loss MnZn power ferrite and its preparation method" (CN 113956031 A) discloses a MnZn ferrite material composed of main components and auxiliary materials. The main components include 52.38-52.49mol% Fe2O3 and 8.69-8.78mol% ZnO, and the rest is MnO. The auxiliary materials include 0.07-0.08wt% CaCO3, 0.0035-0.04wt% Nb2O5, 0.46-0.47wt% Co2O3 and 0.15-0.2wt% SnO2, which reduces the loss in the frequency range of 100-300kHz, but does not explore the direct current superposition characteristics of the material.

[0005] Patent "A high-frequency wide-temperature low-loss MnZn ferrite material and its preparation method" (CN 110517840A) discloses a MnZn ferrite material composed of main components and auxiliary components. The main components include 71-77.4 mol% Fe2O3 and 2-13.8 mol% ZnO, 0.001-1 mol% Ni2O3, and the rest is Mn3O4. The auxiliary components include CaCO3: 200-2000 ppm, Nb2O5: 0-500 ppm, V2O5: 0-500 ppm, SnO2: 0-1000 ppm, TiO2: 0-2000 ppm, ZrO2: 0-200 ppm, Ta2O5: 0-200 ppm, GeO2: 0-1000 ppm, Co3O4: 0-3000 ppm, Bi2O3: 0-1000 ppm, SiO2: 0-200 ppm. The prepared material has the characteristics of maintaining low loss in medium-high frequency (500 kHz-5 MHz) and wide temperature (-30-140℃) range, and expands the temperature use interval.

[0006] In summary, the above-mentioned patent discloses a material that only targets the loss in the medium frequency range and also considers the DC superposition characteristics of the material. To solve this problem, the present invention will reduce the high-temperature loss of the material while considering the DC superposition characteristics of the material.

[0007] Patent "A wide-temperature super-large-current MnZn ferrite material and its preparation method" (CN 113292331A) discloses a MnZn ferrite material. The main components are: Fe2O3: 51.80-54.00 mol%, ZnO: 15.00-18.00 mol%, MnO: 29.50-32.00 mol%; auxiliary components are: Nb2O5: 100-500 ppm, ZrO2: 200-600 ppm, TiO2: 100-500 ppm, CaCO3: 300-800 ppm, SiO2: 10-80 ppm, Co2O3: 2000-5000 ppm, V2O5: 100-500 ppm. By adjusting the content of Fe2O3 and the content of additives Co2O3 and V2O5, the -40℃ and 85℃ superposition characteristics, the magnetic permeability and the incremental magnetic permeability of the material are comprehensively controlled. The prepared material has good DC superposition characteristics at -40℃-85℃, but does not consider the temperature characteristics of the loss. The 100 kHz 200 mT loss at -40℃-85℃ exceeds 400 kW / m 3 .

[0008] Patent "high DC superimposed characteristics of MnZn ferrite material and preparation method" (CN 105174932 A) discloses a kind of high DC superimposed characteristics of MnZn ferrite material, its characteristics are that material composition includes main material and dopant, the main material includes 53.0~55.0mol% Fe2O3 And 38.0~40.0mol% MnO, 0~1.5mol% NiO, the rest is ZnO, with the weight of main material as the calculation basis, calculated by oxide, dopant includes: 0.02~0.20wt% nano CaCO3, 0.001~0.10wt% V2O5, 0.001~0.06wt% Bi2O3, 0.01~0.40wt% Co2O3, 0.01~0.09wt% ZrO2, 0.01~0.20wt% Ge2O3, obtain the MnZn ferrite with high temperature low loss and high DC superimposed characteristics.The invention regulates the DC superimposed characteristics of magnetic permeability to some extent, but the magnetic permeability has dropped to 85% of the initial value under 250mA DC magnetic field, and the invention is for the loss under low frequency 100kHz, and the loss under medium frequency 500kHz is not explored.Similarly, the patents with publication number 10033613.6A and publication number 10518405.6 all disclose similar materials with high temperature low loss and excellent DC superimposed characteristics, but all are for high temperature loss under low frequency, and the loss temperature characteristics under medium frequency are not explored.

[0009] The materials disclosed in the above patents take into account the DC superimposed characteristics and loss of the material to some extent, but are all for loss under low frequency, and the loss under medium frequency is not explored.In order to reduce the size of power supply, the working frequency of magnetic core material will be continuously increased from low frequency (100kHz) to medium frequency (500kHz).Based on this, the present application will suppress the loss under medium frequency while taking into account the DC superimposed characteristics of the material, to prepare MnZn ferrite material with DC superimposed characteristics and low loss under medium frequency. SUMMARY

[0010] The purpose of the present application is to provide a DC superimposed and wide temperature low loss MnZn ferrite and preparation method and application, to solve the problem of loss under low frequency.

[0011] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0012] In a first aspect, the present application provides a preparation method of DC superimposed and wide temperature low loss MnZn ferrite, comprising:

[0013] The main material of MnZn ferrite is obtained by mixing the raw materials according to 52.3-53.3 mol% of Fe2O3, 35.2-36.2 mol% of MnO, 0.12-0.18 mol% of TiO2, and the balance of ZnO;

[0014] The additive is obtained by mixing 0.12-0.16 wt% of CaCO3, 0.02-0.04 wt% of SiO2, 0.03-0.04 wt% of V2O5, 0.12-0.18 wt% of Co2O3, and 0.1-0.3 wt% of SrTiO3 nano powder;

[0015] The main material is put into a ball mill for primary ball milling, and then dried and pre-sintered;

[0016] The pre-sintered powder and the additive are put into the ball mill for secondary ball milling, and then dried and granulated, and the granulated powder is formed into a ring-shaped green body, and the ring-shaped green body is sintered to obtain the ferrite.

[0017] Optionally, in the primary ball milling, the main material is put into the ball mill for ball milling for 2-4 h, the ball milling medium is Φ3 mm zirconium ball, the ball milling speed is 241 rpm, the mixed slurry is placed in an oven for drying for 24 h, and the dried slurry is sieved through a 40-mesh sieve; in the secondary ball milling, the ball milling time is 4.5-5.5 h, and the ball milling speed is 241 rpm; the SrTiO3 contained in the additive is nano powder, and the particle size is 30-100 nm.

[0018] Optionally, after the primary ball milling, the main material is dried and put into a muffle furnace for pre-sintering, the temperature is 900-910℃, the holding time is 2.0-2.5 h, and the atmosphere is air.

[0019] Optionally, in the granulation, the powder after the secondary ball milling is dried, 12.5-16.5 wt% of PVA glue is added, and the powder and the glue are mixed

[0020] Optionally, in the forming, the granulated powder is filled into a mold, and a hydraulic machine is used to press the powder into a ring-shaped green body, the pressure is 6-7 MPa, and the pressure holding time is 10-15 s.

[0021] Optionally, in the sintering, the green body is put into an atmosphere tube furnace, sintered at 1310℃-1330℃, the holding time is 5 h, the oxygen partial pressure in the holding stage is 2.4%-2.7%, and then gradually reduced to room temperature; the cooling stage is divided into three stages: the first stage is from the holding temperature to 1150℃, and the oxygen partial pressure is reduced to 0.8%; the second stage is from 1150℃ to 950℃, and the oxygen partial pressure is reduced to 0.08%; and the third stage is from 950℃ to 50℃, and the oxygen partial pressure is reduced to 0.01%.

[0022] Optionally, the granulation process in Step 4 is a hand kneading method, the powder is mixed with PVA glue, and then kneaded by hand for 20-30 minutes until the powder changes from loose state to quicksand state; in the forming process, 2-3wt% of zinc stearate is added to the powder before pressing, and a stirrer is used to mix for 5 minutes to facilitate the green body demolding; in the forming process, the pressure is applied in the order of first rising to 3-4MPa and maintaining for 5s to make the gas in the powder fully discharged, and then slowly rising to 6-7MPa and maintaining for 10-15s.

[0023] Optionally, in the first ball milling and the second ball milling process, the ball milling medium is deionized water and stainless steel balls, and the weight ratio of the powder, deionized water and steel balls is 1:1.6:3; the steel ball material is 304 stainless steel, and is composed of four different specifications of stainless steel balls mixed in a specific weight ratio, and the weight ratio is Φ1.5mm: Φ3.0mm: Φ5.0mm: Φ8.5mm = 1:3:3:4;

[0024] In the second aspect, the application provides a DC superimposition resistant and wide temperature low loss MnZn ferrite prepared by a preparation method of the DC superimposition resistant and wide temperature low loss MnZn ferrite.

[0025] In the third aspect, the application provides an application of the DC superimposition resistant and wide temperature low loss MnZn ferrite, and the DC superimposition resistant and wide temperature low loss MnZn ferrite is applied to electronic components.

[0026] Compared with the prior art, the application has the following technical effects:

[0027] The application provides a DC superimposition resistant and low loss MnZn ferrite material and a preparation method. 4+ Compared with the traditional method of adding TiO2 in the second ball milling process, Ti4+ can enter the crystal lattice of the MnZn ferrite well, form an ion pair with Fe 2+ , improve the grain resistivity and inhibit the eddy current loss, and also adjust the magnetic crystal anisotropy constant and improve the DC superimposition resistance of the MnZn ferrite. Secondly, the high-resistivity nano SrTiO3 particles are introduced into the additive, which can construct a high-resistivity grain boundary to further reduce the eddy current loss. Finally, in the preparation method, specific proportion steel balls are used in the ball milling process to speed up the ball milling efficiency and reduce the introduced impurities; and a two-step pressing method is used in the forming process to effectively discharge the gas in the powder, which is beneficial to the densification of the green body.

[0028] The application provides a DC superimposition resistant and low loss MnZn power ferrite material. The main material is Fe2O3, MnO, TiO2 and ZnO, wherein Ti4+ The introduction of Fe can increase the positive magnetocrystalline anisotropy of Fe. 2+ The content effectively improves the material's resistance to DC superposition, while Ti 4+ Capable of binding Fe 2+ To avoid it from reacting with Fe 3+ The electronic transition process between them increases the resistivity of the grains.

[0029] This invention uses steel balls in a specific ratio as the milling medium during ball milling, which can quickly and uniformly mix the powder and grind the pre-calcined powder into particles smaller than 1 micrometer, facilitating uniform grain growth. During the forming process, a step-by-step pressure application method is used to fully release air from the powder, resulting in a dense green body and reducing porosity generated during sintering. The additive, nano-SrTiO3 particles, can accumulate at the grain boundaries of MnZn ferrite, constructing a high-resistivity grain boundary layer and further improving the resistivity of MnZn ferrite.

[0030] The above method enables the fabrication of MnZn ferrite materials that possess both high DC superposition resistance and low loss, with a magnetic permeability of 2933 and H₂O. μ70 That is, the DC superimposed magnetic field value corresponding to a 70% reduction in magnetic permeability is 200 A / m, and the loss in the range of 25–100℃ at 100 kHz and 200 mT is less than 330 kW / m. 3 . Attached Figure Description

[0031] Figure 1 The variation of magnetic permeability of MnZn ferrite with DC superimposed magnetic field. Detailed Implementation

[0032] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0033] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0034] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items.

[0035] It should be understood that the magnitude of the serial number of the above processes does not mean the order of execution in various embodiments of the present application, and part or all of the steps can be executed in parallel or in sequence, and the execution order of the processes should be determined according to its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0036] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0037] The weight of the related components mentioned in the specification of the embodiments of the present application can not only refer to the specific content of each component, but also represent the weight ratio relationship between each component, therefore, as long as the content of the related components in the specification of the embodiments of the present application is enlarged or reduced in proportion, it is within the scope disclosed in the specification of the embodiments of the present application. Specifically, the mass mentioned in the specification of the embodiments of the present application can be μg, mg, g, kg and other mass units commonly known in the chemical field.

[0038] The terms "first", "second" are only for the purpose of description, used to distinguish the subject matter from each other, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. For example, without departing from the scope of the embodiments of the present application, the first XX can also be referred to as the second XX, and similarly, the second XX can also be referred to as the first XX. Therefore, the features limited by "first", "second" can explicitly or implicitly include one or more of the features.

[0039] At 100 kHz 200 mT, the loss of MnZn is composed of hysteresis loss and eddy current loss, and the eddy current loss is closely related to the resistivity of the material. Previous studies have shown that Ti 4+ ions can form ion pairs with Fe 2+ ions in MnZn ferrite, which can bind Fe 2+ ions and thus reduce the electronic transition process between Fe 2+ ions and Fe 2+ ions, thereby increasing the resistivity of the material. At the same time, Fe 2+ ions have a positive magnetocrystalline anisotropy, which can affect the magnetocrystalline anisotropy constant of MnZn ferrite, and thus adjust the DC superposition characteristics of permeability. Generally, Ti 4+ is introduced by adding TiO2 additive during secondary ball milling, but this method introduces Ti 4+It is difficult to completely enter the crystal lattice, and the remaining part will be enriched in the grain boundary to form a heterogeneous phase, which deteriorates the electromagnetic performance of the MnZn ferrite. Based on this, the application provides a DC superimposed and low loss MnZn ferrite material and a preparation method 4+ , which directly introduces Ti into the main formula of the MnZn ferrite to promote it to enter the crystal lattice of the MnZn ferrite, adjusts the magnetic anisotropy constant while improving the grain resistivity, and improves the DC superimposed resistance of the MnZn ferrite; on the other hand, high-resistivity nano-SrTiO3 particles are introduced into the additive to build a high-resistivity grain boundary to reduce the eddy current loss. Based on the above idea, the magnetic anisotropy and grain / grain boundary conductivity of the MnZn ferrite are simultaneously regulated, and the MnZn ferrite with DC superimposed resistance and low loss can be prepared

[0040] To achieve the above application purposes, the technical scheme adopted by the application is as follows:

[0041] In a first aspect, the application provides a DC superimposed and low loss MnZn power ferrite material, which comprises a main material and an additive.

[0042] In the above scheme, the main material is 52.3-53.3mol% Fe2O3, 35.2-36.2mol% MnO, 0.12-0.18mol% TiO2, and the balance is ZnO; the additive is 0.12-0.16wt% CaCO3 based on the weight of the main material, 0.02-0.04wt% SiO2 based on the weight of the main material, 0.03-0.04wt% V2O5 based on the weight of the main material, 0.12-0.18wt% Co2O3 based on the weight of the main material, and 0.1-0.3wt% SrTiO3 based on the weight of the main material.

[0043] In a second aspect, the application provides a preparation method of a DC superimposed and low loss MnZn power ferrite material, and the preparation process is as follows:

[0044] Step 1: Configure the main material of the MnZn ferrite. Calculate the required raw material weight according to 52.3-53.3mol% Fe2O3, 35.2-36.2mol% MnO, 0.12-0.18mol% TiO2, and the balance is ZnO, and accurately weigh using an analytical balance.

[0045] Step 2: Primary ball milling: put the main material into the ball mill for ball milling mixing, the ball milling time is 2-4h, the ball milling medium is Φ3mm zirconium ball, the ball milling speed is 241r / min, the mixed slurry is placed in an oven for drying for 24h, and then sieved through a 40 mesh sieve after drying;

[0046] Step 3 pre-burning. After drying, the main material after the first ball milling is put into the muffle furnace for pre-burning, the temperature is 900-910℃, the holding time is 2.0-2.5h, and the atmosphere is air;

[0047] Step 4 preparation of additives. Add additives to the pre-burned powder, calculate and weigh the required additives according to the weight of the pre-burned powder, including 0.12-0.16wt% CaCO3, 0.02-0.04wt% SiO2, 0.03-0.04wt% V2O5, 0.12-0.18wt% Co2O3, 0.1-0.3wt% SrTiO3 nano powder;

[0048] Step 5 secondary ball milling. Put the pre-burned powder and additives into the ball mill at the same time for ball milling, the ball milling time is 4.5-5.5h, and the rotating speed is 241r / min;

[0049] Step 6 granulation. After drying the powder after secondary ball milling, add 12.5-16.5wt% PVA glue, mix the powder and glue;

[0050] Step 7 forming. Fill the granulated powder into the mold, and press it into a ring-shaped green body with a hydraulic press, the pressure is 6-7MPa, and the holding time is 10-15s;

[0051] Step 8 sintering. Put the green body into the atmosphere tube furnace, sinter at 1310-1330℃, the holding time is 5h, the oxygen partial pressure in the holding stage is 2.4%-2.7%, and then gradually reduce to room temperature.

[0052] Use LCR digital bridge (TH2828) and direct current power supply (PLR36-20) to test the magnetic permeability of the ring-shaped sample, the number of turns is 10 turns, the test condition is 1kHz 1A / m 25℃; Use BH analyzer (IWATSU SY-8218) to test the loss P of the ring-shaped sample in the range of 25-100℃, the number of turns is 5 turns, and the test condition is 100kHz 200mT. cv

[0053] Specifically:

[0054] ​The application provides a DC superimposed resistant and low-loss MnZn power ferrite material, which is composed of components and additives, wherein the main components comprise 52.30-53.30 mol% of Fe2O3, 35.20-36.20 mol% of MnO, 0.20-0.40 mol% of TiO2 and the balance of ZnO; the additives comprise 0.12-0.16 wt% of CaCO3, 0.02-0.04 wt% of SiO2, 0.03-0.04 wt% of V2O5, 0.12-0.18 wt% of Co2O3 and 0.1-0.3 wt% of SrTiO3, based on the weight of the main material.

[0055] In addition to Fe2O3, MnO and ZnO, TiO2 is added to the main material to form a MnZnFeTi quaternary system;

[0056] The SrTiO3 contained in the additives is a nano-powder with a particle size of 30-100 nm;

[0057] The method comprises the following steps:

[0058] Step 1: configuring the MnZn ferrite main material; the required raw material weight is calculated according to 52.3-53.3 mol% of Fe2O3, 35.2-36.2 mol% of MnO, 0.12-0.18 mol% of TiO2 and the balance of ZnO, and the accurate weight is measured by using an analytical balance.

[0059] Step 2: primary ball milling; the main material is placed into a ball mill for ball milling mixing, the ball milling time is 2-4 h, the ball milling medium is Φ3 mm zirconium ball, the ball milling rotation speed is 241 r / min, and the mixed slurry is placed in an oven for drying for 24 h, and then the dried slurry is passed through a 40-mesh sieve;

[0060] Step 3: pre-sintering; the main material after primary ball milling is dried and then placed into a muffle furnace for pre-sintering, the temperature is 900-910 DEG C, the holding time is 2.0-2.5 h, and the atmosphere is air;

[0061] Step 4: preparing the additives; the additives are added into the pre-sintered powder, the required additives are weighed according to the weight of the pre-sintered powder, and the additives comprise 0.12-0.16 wt% of CaCO3, 0.02-0.04 wt% of SiO2, 0.03-0.04 wt% of V2O5, 0.12-0.18 wt% of Co2O3 and 0.1-0.3 wt% of SrTiO3 nano-powder;

[0062] Step 5 Secondary ball milling. Put the pre-sintered powder and additives into the ball mill at the same time, ball milling time is 4.5-5.5h, rotation speed is 241r / min;

[0063] Step 6 Granulation. After drying the powder after secondary ball milling, add 12.5-16.5wt% PVA glue, mix the powder and glue;

[0064] Step 7 Forming. Fill the granulated powder into the mold, press into ring-shaped green body by hydraulic machine, pressure is 6-7MPa, pressure holding time is 10-15s;

[0065] Step 8 Sintering. Put the green body into the atmosphere tube furnace, sinter at 1310-1330℃, holding time is 5h, oxygen partial pressure in holding stage is 2.4%-2.7%, then gradually reduce to room temperature;

[0066] Step 1 Primary ball milling and Step 3 Secondary ball milling, the ball milling medium used is deionized water and stainless steel balls, the weight ratio of powder:deionized water:steel ball is 1:1.6:3;

[0067] Step 1 Primary ball milling and Step 3 Secondary ball milling, the steel ball used is 304 stainless steel, and is composed of four different specifications of stainless steel balls mixed according to a specific weight ratio, the weight ratio is Φ1.5mm:Φ3.0mm:Φ5.0mm:Φ8.5mm=1:3:3:4;

[0068] Step 4 Granulation process uses hand rubbing method, after mixing the powder and PVA glue, rub for 20-30min with hands until the powder changes from loose state to sand state;

[0069] Step 5 Forming process, 2-3wt% zinc stearate is added to the powder before pressing, and mixed for 5min by stirrer to facilitate green body demolding;

[0070] Step 5 Forming process, the pressure application sequence is first increased to 3-4MPa and maintained for 5s to fully discharge the gas in the powder, then slowly increased to 6-7MPa and maintained for 10-15s;

[0071] Step 6 Sintering process, the cooling stage is divided into three stages: the first stage is holding temperature-1150℃, oxygen partial pressure is reduced to 0.8%; the second stage is 1150-950℃, oxygen partial pressure is reduced to 0.08%; the third stage is 950-50℃, oxygen partial pressure is reduced to 0.01%.

[0072] Example

[0073] Table 1 Main materials, additive ingredients and holding temperature of Examples 1-6

[0074]

[0075]

[0076] Example 1

[0077] A preparation method of a DC superposition resistant and low loss MnZn power ferrite material, the preparation steps are as follows:

[0078] Step 1: Configure the MnZn ferrite main material. Calculate the required raw material weight according to 52.3mol% Fe2O3, 36.2mol% MnO, 0.12mol% TiO2, and 11.38mol% ZnO, and accurately weigh using an analytical balance.

[0079] Step 2: First ball milling: Put the main material into the ball mill for ball milling mixing, the ball milling time is 3h, the ball milling medium is Φ3mm zirconium ball, the ball milling speed is 241r / min, the mixed slurry is placed in the oven for drying for 24h, and then sieved through a 40 mesh sieve after drying;

[0080] Step 3: Pre-sintering. After drying the main material after first ball milling, put it into a muffle furnace for pre-sintering, the temperature is 900℃, the holding time is 2h, and the atmosphere is air;

[0081] Step 4: Preparation of additives. Add additives to the pre-sintered powder, calculate and weigh the required additives according to the weight of the pre-sintered powder, including 0.12wt% CaCO3, 0.03wt% SiO2, 0.03wt% V2O5, 0.15wt% C o 2O3, 0.1wt% SrTiO3 nano powder;

[0082] Step 5: Second ball milling. Put the pre-sintered powder and additives into the ball mill at the same time for ball milling, the ball milling time is 5h, and the speed is 241r / min;

[0083] Step 6: Granulation. After drying the powder after second ball milling, add 14.5wt% PVA glue, mix the powder and glue;

[0084] Step 7: Forming. Fill the granulated powder into the mold, and press it into a ring-shaped green body with a hydraulic press, the pressure is 6MPa, and the holding time is 10s;

[0085] Step 8: Sintering. Put the green body into a tube furnace with an atmosphere, sinter at 1310℃, holding time is 5h, oxygen partial pressure during holding stage is 2.5%, and then gradually reduce to room temperature;

[0086] Example 2

[0087] A preparation method of a DC superimposed resistant and low loss MnZn power ferrite material, the preparation steps are as follows:

[0088] Step 1: Configure the MnZn ferrite main material. Calculate the required raw material weight according to 52.4mol% Fe2O3, 36.1mol% MnO, 0.13mol% TiO2, and 11.37mol% ZnO, and accurately weigh.

[0089] Step 2: First ball milling: Put the main material into the ball mill for ball milling mixing, the ball milling time is 3h, the ball milling medium is Φ3mm zirconium ball, the ball milling speed is 241r / min, the mixed slurry is placed in the oven for drying for 24h, and then sieved through a 40 mesh sieve after drying;

[0090] Step 3: Pre-sintering. After the main material is dried after the first ball milling, it is put into a muffle furnace for pre-sintering, the temperature is 900℃, the holding time is 2h, and the atmosphere is air;

[0091] Step 4: Preparation of additives. Add additives to the pre-sintered powder, calculate and weigh the required additives according to the weight of the pre-sintered powder, including 0.12wt% CaCO3, 0.03wt% SiO2, 0.03wt% V2O5, 0.15wt% Co2O3, and 0.1wt% SrTiO3 nano powder;

[0092] Step 5: Second ball milling. Put the pre-sintered powder and additives into the ball mill at the same time for ball milling, the ball milling time is 5h, and the speed is 241r / min;

[0093] Step 6: Granulation. After the second ball milling, the powder is dried, 14.5wt% PVA glue is added, and the powder and glue are mixed;

[0094] Step 7: Forming. The granulated powder is filled into the mold, and a hydraulic machine is used to press into a ring-shaped green body, the pressure is 6MPa, and the holding time is 10s;

[0095] Step 8: Sintering. Put the green body into the atmosphere tube furnace, sinter at 1310℃, holding time is 5h, oxygen partial pressure during holding stage is 2.5%, and then gradually reduce to room temperature;

[0096] Example 3

[0097] A preparation method of a DC superimposed resistant and low loss MnZn power ferrite material, the preparation steps are as follows:

[0098] Step 1 Preparation of MnZn ferrite main material. Calculate the required raw material weight according to 52.6mol% Fe2O3, 35.9mol% MnO, 0.14mol% TiO2, 11.36mol% ZnO, and accurately weigh.

[0099] Step 2 First ball milling: put the main material into the ball mill for ball milling mixing, the ball milling time is 3h, the ball milling medium is Φ3mm zirconium ball, the ball milling speed is 241r / min, the mixed slurry is placed in the oven for drying for 24h, and then sieved through 40 mesh sieve after drying;

[0100] Step 3 Pre-sintering. After drying the main material after first ball milling, put it into the muffle furnace for pre-sintering, the temperature is 900℃, the holding time is 2h, and the atmosphere is air;

[0101] Step 4 Preparation of additives. Add additives to the pre-sintered powder, calculate and weigh the required additives according to the weight of the pre-sintered powder, including 0.12wt% CaCO3, 0.03wt% SiO2, 0.03wt% V2O5, 0.15wt% C o 2O3, 0.2wt% SrTiO3 nano powder;

[0102] Step 5 Second ball milling. Put the pre-sintered powder and additives into the ball mill for ball milling at the same time, the ball milling time is 5h, and the speed is 241r / min;

[0103] Step 6 Granulation. After drying the powder after second ball milling, add 14.5wt% PVA glue, mix the powder with the glue;

[0104] Step 7 Forming. Fill the granulated powder into the mold, and press it into a ring-shaped green body with a hydraulic press, the pressure is 6MPa, and the holding time is 10s;

[0105] Step 8 Sintering. Put the green body into the atmosphere tube furnace, sinter at 1320℃, holding time is 5h, oxygen partial pressure during holding stage is 2.5%, then gradually reduce to room temperature;

[0106] Example 4

[0107] A preparation method of a DC superimposed and low loss MnZn power ferrite material, the preparation steps are as follows:

[0108] Step 1 Preparation of MnZn ferrite main material. Calculate the required raw material weight according to 52.6mol% Fe2O3, 35.9mol% MnO, 0.14mol% TiO2, 11.36mol% ZnO, and accurately weigh.

[0109] Step 2 primary ball milling: the main material is put into the ball mill for ball milling mixing, the ball milling time is 3h, the ball milling medium is Φ3mm zirconium ball, the ball milling speed is 241r / min, the mixed slurry is placed in the oven for drying for 24h, and then it is sieved through a 40 mesh sieve after drying;

[0110] Step 3 pre-sintering. After drying, the main material after primary ball milling is put into a muffle furnace for pre-sintering, the temperature is 900℃, the holding time is 2h, and the atmosphere is air;

[0111] Step 4 preparation of additives. Additives are added to the pre-sintered powder, the required additives are weighed according to the weight of the pre-sintered powder, which contains 0.12wt% CaCO3, 0.03wt% SiO2, 0.03wt% V2O5, 0.15wt% C o 2O3, 0.2wt% SrTiO3 nano powder;

[0112] Step 5 secondary ball milling. The pre-sintered powder and additives are put into the ball mill for ball milling at the same time, the ball milling time is 5h, and the speed is 241r / min;

[0113] Step 6 granulation. After drying, 14.5wt% PVA glue is added to the powder after secondary ball milling, and the powder and glue are mixed;

[0114] Step 7 shaping. The granulated powder is filled into the mold, and the ring-shaped green body is pressed by hydraulic machine, the pressure is 6MPa, and the holding time is 10s;

[0115] Step 8 sintering. The green body is put into a tube furnace, sintered at 1320℃, the holding time is 5h, the oxygen partial pressure during holding is 2.5%, and then it is gradually reduced to room temperature;

[0116] Example 5

[0117] A preparation method of a DC superimposed and low loss MnZn power ferrite material, the preparation steps are as follows:

[0118] Step 1 preparation of MnZn ferrite main material. The required raw material weight is calculated according to 53.0mol% Fe2O3, 35.5mol% MnO, 0.16mol% TiO2, and 11.34mol% ZnO, and accurately weighed.

[0119] Step 2 primary ball milling: the main material is put into the ball mill for ball milling mixing, the ball milling time is 3h, the ball milling medium is Φ3mm zirconium ball, the ball milling speed is 241r / min, the mixed slurry is placed in the oven for drying for 24h, and then it is sieved through a 40 mesh sieve after drying;

[0120] Step 3 pre-burning. After drying, the primary material after the first ball milling is put into the muffle furnace for pre-burning, the temperature is 900℃, the holding time is 2h, and the atmosphere is air;

[0121] Step 4 preparation of additives. Additives are added to the pre-burned powder, the required additives are weighed according to the weight of the pre-burned powder, including 0.12wt% CaCO3, 0.03wt% SiO2, 0.03wt% V2O5, 0.15wt% Co2O3, and 0.2wt% SrTiO3 nano powder;

[0122] Step 5 secondary ball milling. The pre-burned powder and additives are put into the ball mill at the same time for ball milling, the ball milling time is 5h, and the rotating speed is 241r / min;

[0123] Step 6 granulation. After drying, the powder after the second ball milling is added with 14.5wt% PVA glue, and the powder and glue are mixed;

[0124] Step 7 shaping. The granulated powder is filled into the mold, and a ring-shaped green body is pressed by a hydraulic machine, the pressure is 6MPa, and the holding time is 10s;

[0125] Step 8 sintering. The green body is put into the atmosphere tube furnace for sintering at 1320℃, the holding time is 5h, the oxygen partial pressure during the holding stage is 2.5%, and then gradually reduced to room temperature;

[0126] Example 6

[0127] A preparation method of a DC superimposed and low loss MnZn power ferrite material, the preparation steps are as follows:

[0128] Step 1 configuration of MnZn ferrite primary material. The required raw material weight is calculated according to 53.3mol% Fe2O3, 35.2mol% MnO, 0.18mol% TiO2, and 11.32mol% ZnO, and accurately weighed.

[0129] Step 2 first ball milling: the primary material is put into the ball mill for ball milling and mixing, the ball milling time is 3h, the ball milling medium is Φ3mm zirconium ball, the ball milling rotating speed is 241r / min, the mixed slurry is placed in the oven for drying for 24h, and then passed through a 40 mesh sieve after drying;

[0130] Step 3 pre-burning. After drying, the primary material after the first ball milling is put into the muffle furnace for pre-burning, the temperature is 900℃, the holding time is 2h, and the atmosphere is air;

[0131] Step 4 Preparation of additives. Additives are added to the pre-sintered powder. The required additives are weighed according to the weight of the pre-sintered powder, including 0.12wt% CaCO3, 0.03wt% SiO2, 0.03wt% V2O5, 0.15wt% Co2O3, and 0.3wt% SrTiO3 nano powder;

[0132] Step 5 Secondary ball milling. The pre-sintered powder and additives are placed in a ball mill at the same time for ball milling. The ball milling time is 5h, and the rotation speed is 241r / min;

[0133] Step 6 Granulation. After drying the secondary ball-milled powder, 14.5wt% PVA glue is added, and the powder is mixed with the glue;

[0134] Step 7 Molding. The granulated powder is filled into a mold, and a hydraulic machine is used to press it into a ring-shaped green body. The pressure is 6MPa, and the holding time is 10s;

[0135] Step 8 Sintering. The green body is placed in a tube furnace and sintered at 1330℃ for 5h. The oxygen partial pressure during the holding stage is 2.5%, and then it is gradually reduced to room temperature;

[0136] Comparative Example

[0137] Table 2 Composition of main materials and additives of Comparative Examples 1 and 2 and holding temperature

[0138]

[0139] Comparative Example 1

[0140] A method for preparing a MnZn power ferrite material, the preparation steps are as follows:

[0141] Step 1 Preparation of MnZn ferrite main material. The required raw material weight is calculated according to 52.3mol% Fe2O3, 36.2mol% MnO, 0.05mol% TiO2, and 11.45mol% ZnO, and accurately weighed.

[0142] Step 2 Primary ball milling: The main material is placed in a ball mill for ball milling and mixing. The ball milling time is 3h, the ball milling medium is Φ3mm zirconium ball, and the ball milling rotation speed is 241r / min. The mixed slurry is dried in an oven for 24h, and then sieved through a 40 mesh sieve;

[0143] Step 3 Pre-sintering. The pre-sintered powder is placed in a muffle furnace for pre-sintering at a temperature of 900℃ for 2h in an air atmosphere;

[0144] Step 4 Preparation of additives. Additives are added to the pre-sintered powder. The required additives are weighed according to the weight of the pre-sintered powder, including 0.12wt% CaCO3, 0.03wt% SiO2, 0.03wt% V2O5, 0.15wt% C o 2O3, 0.0wt% SrTiO3 nanopowder;

[0145] Step 5 Secondary ball milling. The pre-sintered powder and additives are placed in a ball mill for ball milling at the same time. The ball milling time is 5h, and the rotation speed is 241r / min;

[0146] Step 6 Granulation. After drying the secondary ball-milled powder, 14.5wt% PVA glue is added, and the powder and glue are mixed;

[0147] Step 7 Molding. The granulated powder is filled into a mold, and a hydraulic machine is used to press it into a ring-shaped green body. The pressure is 6MPa, and the pressure holding time is 10s;

[0148] Step 8 Sintering. The green body is placed in a tube furnace, and sintering is carried out at 1310℃. The holding time is 5h, and the oxygen partial pressure during the holding stage is 2.5%. Then it is gradually reduced to room temperature;

[0149] Comparative Example 2

[0150] A method for preparing a MnZn power ferrite material, the preparation steps are as follows:

[0151] Step 1 Preparation of MnZn ferrite main material. The required raw material weight is calculated according to 53.3mol% Fe2O3, 35.2mol% MnO, 0.25mol% TiO2, and 11.25mol% ZnO, and accurately weighed.

[0152] Step 2 Primary ball milling: The main material is placed in a ball mill for ball milling and mixing. The ball milling time is 3h, the ball milling medium is Φ3mm zirconium ball, and the ball milling rotation speed is 241r / min. The mixed slurry is dried in an oven for 24h, and then sieved through a 40 mesh sieve after drying;

[0153] Step 3 Pre-sintering. The primary ball-milled main material is dried and then placed in a muffle furnace for pre-sintering at a temperature of 900℃ for 2.0h in an air atmosphere;

[0154] Step 4 Preparation of additives. Additives are added to the pre-sintered powder. The required additives are weighed according to the weight of the pre-sintered powder, including 0.12wt% CaCO3, 0.03wt% SiO2, 0.03wt% V2O5, 0.15wt% C o 2O3, 0.5wt% SrTiO3 nanopowder;

[0155] Step 5: Secondary ball milling. The pre-calcined powder and additives are simultaneously placed into a ball mill for ball milling. The milling time is 5 hours, and the rotation speed is 241 rpm.

[0156] Step 6: Granulation. After drying the powder from the secondary ball milling, add 14.5 wt% PVA adhesive and mix the powder with the adhesive;

[0157] Step 7: Molding. The granulated powder is filled into a mold and pressed into a ring-shaped green preform using a hydraulic press at a pressure of 6 MPa for 10 seconds.

[0158] Step 8 Sintering. The green embryo is placed in an atmosphere tube furnace and sintered at 1330℃ for 5 hours. The oxygen partial pressure during the holding period is 2.5%, and then the temperature is gradually reduced to room temperature.

[0159] Table 3

[0160]

[0161] From Table 3 and Figure 1 As can be seen from the performance parameters of Examples 1 to 6, the present invention prepares MnZn ferrite with high initial magnetic permeability and saturation magnetic induction intensity by adjusting the amount of Ti substitution in the main formula and the amount of nano-SrTiO3 doping in the additives, combined with the adjustment of the sintering temperature. It also has excellent resistance to DC superposition and low core loss.

[0162] Comparing Examples 1 and 2, under the same SrTiO3 doping amount, increasing the Ti substitution amount results in a decrease in Fe... 2+ The increase in content leads to a slight decrease in initial permeability, H μ70 The saturation magnetic induction intensity also increases slightly due to the increase in Fe content, and the loss remains below 360 kW / m in the temperature range of 25–100℃. 3 .

[0163] Compared to Examples 1 and 2, Examples 3, 4, and 5 simultaneously increased the SrTiO3 doping amount and the Ti substitution amount, on the one hand by increasing the Ti ion doping of Fe... 2+ The binding effect of ions increases grain resistivity; on the other hand, the high-resistivity grain boundaries formed by SrTiO3 further increase the resistivity of MnZn ferrite, thereby reducing losses in the 25–100 °C range. Simultaneously, the increase in Ti ions also implies the presence of positively magnetized anisotropic Fe... 2+ An increase in ions leads to H μ70The DC superimposed resistance is further improved. Since the high melting point of SrTiO3 can inhibit the growth of MnZn ferrite grains, the sintering temperature is also increased to 1320°C to ensure the full growth of MnZn ferrite grains.

[0164] Compared with examples 3, 4 and 5, the SrTiO3 doping amount and Ti substitution amount of example 6 are further increased. Although the H μ70 increases, the initial permeability also decreases to 3014, and the loss in the range of 25-100°C is not significantly reduced.

[0165] Compared with examples 1-6, the Ti substitution amount in comparative example 1 is small, and SrTiO3 is not doped. Although the initial permeability and saturation magnetic induction are the largest, the H μ70 is only 67 A / m, indicating poor DC superimposed resistance and large loss in the range of 25-100°C.

[0166] Compared with examples 1-6, the Ti substitution amount in comparative example 2 is greatly increased, and although the H μ70 increases to 142 A / m, the DC superimposed resistance is improved, but since the binding effect of Ti ions is limited, too much Fe 2+ makes the grain resistivity decrease, and the loss increases sharply. Even if the SrTiO3 doping amount is increased synchronously, it still cannot curb the decrease of the resistivity of MnZn ferrite, and instead, due to the introduction of too much non-magnetic phase, the initial permeability and saturation magnetic induction decrease.

[0167] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing MnZn ferrite resistant to DC superposition and with wide temperature range and low loss, characterized in that, include: The required raw material weight was calculated based on 52.3–53.3 mol% Fe2O3, 35.2–36.2 mol% MnO, 0.12–0.18 mol% TiO2, with the balance being ZnO, to obtain the MnZn ferrite main material; The additive was prepared by mixing 0.12–0.16 wt% CaCO3, 0.02–0.04 wt% SiO2, 0.03–0.04 wt% V2O5, 0.12–0.18 wt% Co2O3, and 0.1–0.3 wt% SrTiO3 nanopowder. The main material is put into a ball mill for one ball milling and mixing, then dried and pre-calcined; The pre-fired powder and additives are simultaneously put into a ball mill for secondary ball milling, then dried and granulated to form an annular green body. The annular green body is then sintered to obtain ferrite.

2. The method for preparing DC-resistant, wide-temperature, low-loss MnZn ferrite according to claim 1, characterized in that, In the first ball milling, the main material is placed in a ball mill for ball milling and mixing for 2-4 hours. The ball milling media are Φ3mm zirconium balls, and the ball milling speed is 241 rpm. The mixed slurry is placed in an oven to dry for 24 hours and then passed through a 40-mesh sieve. In the second ball milling, the ball milling time is 4.5-5.5 hours, and the speed is 241 rpm. The SrTiO3 contained in the additive is a nano powder with a particle size of 30-100nm.

3. The method for preparing DC-resistant, wide-temperature, low-loss MnZn ferrite according to claim 1, characterized in that, After the main material is dried after one ball milling, it is placed in a muffle furnace for pre-firing at a temperature of 900-910℃ for 2.0-2.5 hours in an air atmosphere.

4. The method for preparing DC-resistant, wide-temperature, low-loss MnZn ferrite according to claim 1, characterized in that, During granulation, the powder after secondary ball milling is dried, and 12.5-16.5 wt% of PVA adhesive is added to mix the powder and adhesive.

5. The method for preparing DC-resistant, wide-temperature, low-loss MnZn ferrite according to claim 1, characterized in that, During molding, the granulated powder is filled into the mold and pressed into a ring-shaped green preform using a hydraulic press. The pressure is 6-7 MPa and the holding time is 10-15 seconds.

6. The method for preparing DC-resistant, wide-temperature, low-loss MnZn ferrite according to claim 1, characterized in that, During sintering, the green embryo is placed in an atmosphere tube furnace and sintered at 1310℃~1330℃ for 5 hours, with an oxygen partial pressure of 2.4%~2.7% during the holding period. Then, it is gradually cooled to room temperature. The cooling period is divided into three stages: the first stage is from the holding temperature to 1150℃, with the oxygen partial pressure dropping to 0.8%; the second stage is from 1150℃ to 950℃, with the oxygen partial pressure dropping to 0.08%; and the third stage is from 950℃ to 50℃, with the oxygen partial pressure dropping to 0.01%.

7. The method for preparing DC-resistant, wide-temperature, low-loss MnZn ferrite according to claim 1, characterized in that, The granulation process uses a hand-kneading method. After the powder and PVA adhesive are mixed, they are kneaded by hand for 20-30 minutes until the powder changes from a loose state to a flowing sand state. During the molding process, 2-3 wt% zinc stearate is added to the powder before pressing, and it is mixed with a stirrer for 5 minutes to facilitate the demolding of the green body. During the molding process, the pressure is applied in the following order: first, it is increased to 3-4 MPa and held for 5 seconds to allow the gas in the powder to be fully discharged, and then it is slowly increased to 6-7 MPa and held for 10-15 seconds.

8. The method for preparing DC-resistant, wide-temperature, low-loss MnZn ferrite according to claim 1, characterized in that, In both the primary and secondary ball milling processes, the milling media used are deionized water and stainless steel balls, with a powder:deionized water:steel ball weight ratio of 1:1.6:

3. The steel balls used are made of 304 stainless steel and are composed of four different specifications of stainless steel balls mixed in a specific weight ratio of Φ1.5mm:Φ3.0mm:Φ5.0mm:Φ8.5mm = 1:3:3:

4.

9. A MnZn ferrite resistant to DC superposition and exhibiting wide temperature range and low loss, characterized in that, It is prepared by the method for preparing DC-resistant, wide-temperature, low-loss MnZn ferrite according to any one of claims 1 to 8.

10. An application of the DC-resistant, wide-temperature, low-loss MnZn ferrite as described in claim 9, characterized in that, MnZn ferrite, which is resistant to DC superposition and has a wide temperature range and low loss, is used in electronic components.

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