CN110668806A

CN110668806A - Preparation method of soft magnetic ferrite for high frequency

Info

Publication number: CN110668806A
Application number: CN201911041408.2A
Authority: CN
Inventors: 陈海艳
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-10-30
Filing date: 2019-10-30
Publication date: 2020-01-10

Abstract

The invention relates to a preparation method of a soft magnetic ferrite for high frequency, belonging to the technical field of electronic devices. The invention prepares the soft magnetic ferrite for high frequency by adding the zirconium oxide and the tin oxide, wherein the zirconium ion in the zirconium oxide has large radius, a high resistance layer can be formed at the crystal boundary of the ferrite, the crystal boundary resistivity of the material can be effectively improved, so that the high-frequency eddy current loss is reduced, the tin oxide belongs to a low-melting-point substance, the liquid phase sintering can be realized by adding the tin oxide, the sintering temperature is reduced, so that the grain size of the material is controlled, the tin ion in the tin oxide belongs to a non-magnetic ion, and the magnetic crystal anisotropy and the magnetostriction coefficient of the soft magnetic ferrite material can be adjusted by adding the tin oxide, so that the hysteresis loss of the material is controlled.

Description

Preparation method of soft magnetic ferrite for high frequency

Technical Field

The invention relates to a preparation method of a soft magnetic ferrite for high frequency, belonging to the technical field of electronic devices.

Background

The development of electronic devices requires, on the one hand, a continuous improvement of the circuit design level and, on the other hand, also does not leave open the improvement of the performance of the key materials and the progress of the manufacturing process. The progress of electronic devices is often closely related to the development of semiconductor materials, insulating materials, magnetic materials and other electrical and ceramic materials. In the field of magnetic materials, various soft magnetic ferrite materials are the most widely used component materials at present, and almost all electronic devices contain magnetic devices composed of soft magnetic ferrite, such as electronic computers, automotive electronics, mobile equipment, electric automobile charging devices, electromagnetic shielding of circuit boards, various switching power supplies, power adapters, near field communication devices, wireless charging facilities and the like. The composite material is mainly applied to electronic components such as various inductors, transformers, filters and the like, and devices formed by the composite material are widely applied to the fields of modern electric power, electronic information and the like. In the field of soft magnetic materials for power transmission, the materials mainly applied at present are silicon steel, permalloy, metallic amorphous and nanocrystalline materials, magnetic powder core and other metallic soft magnetic composite materials and ferrite materials. Ferrite is the only ceramic semiconductor material, the high resistivity of the ferrite is beneficial to restraining eddy current loss in a high-frequency alternating electromagnetic field, and the ferrite has simple manufacturing process, lower cost and high stability, thereby having excellent performance at high frequency. Therefore, the development of the soft magnetic ferrite core material with high frequency and low loss through different technologies has important practical significance.

According to the difference of the use occasions of materials, soft magnetic ferrite is generally divided into three different types, namely high-permeability ferrite, power ferrite and anti-electromagnetic interference ferrite, the high-permeability ferrite has high requirement on initial permeability, for manganese-zinc ferrite, the requirement is usually more than 5000, products which are already put into use in industry can reach 13000 ~ 15000 (models such as TDK-EPCOS: T66, T46 and H5C 3), when the initial permeability is too high, the Curie temperature and the temperature stability of the permeability are deteriorated, the ferrite with the too high permeability cannot enter practical industrial application, for nickel-zinc ferrite, the initial permeability is usually more than 2000, the power ferrite is the most widely applied ferrite with the largest yield, the ferrite is mainly used in the power transmission process, the ferrite is expected to have lower power consumption at higher frequency, the power transmission efficiency is improved, ideal loss can be reduced along with the temperature rise, and after components generate heat due to work, the power loss of the device can enable the manganese to work at a stable temperature, the power transmission efficiency is improved, and the ferrite is a plurality of ferrite products, wherein the ferrite is a plurality of common anti-electromagnetic interference ferrite, and the ferrite is an anti-electromagnetic interference ferrite.

In the industry standard of 'soft magnetic ferrite material classification' in China, the most important manganese-zinc power ferrite is a magnetic core for a switching power supply transformer. The rapid development of power electronics has led to switching power supplies replacing the original linear power supply on a large scale. Switching power sources originated in the last 50 s, and NASAF (national aviation and space navigation agency) developed small, lightweight, high conversion, low power consumption switching power sources for the purpose of reducing the weight of satellites, and nowadays, switching power sources have been widely used in the fields of computers, industrial processing, communications, electrical equipment, and home appliances. At present, most power supplies adopt a switching power supply, such as a power adapter of a notebook computer, a driving power supply of an LED lamp, a charger, a solar inverter, a module power supply, a communication power supply and the like, and are essentially the switching power supply.

With the increasing demand for miniaturization of switching power supplies, the higher the operating frequency, the smaller the core size of the transformer, and thus increasing the switching frequency can reduce the weight and size of the power supply. One of the key technologies for restricting the improvement of the working frequency lies in the preparation technology of the high-frequency wide-temperature low-loss high-performance power ferrite material used for the magnetic core. In the research and product development of the most common manganese-zinc ferrite at home and abroad, the working frequency is usually within 1MHz, and the magnetic conductivity and the power loss are obviously different along with the change of temperature at higher frequency. At present, soft magnetic ferrite materials using Fe2O3, Mn3O4, and ZnO as main components are available, but the power loss of the soft magnetic ferrite materials and magnetic cores using Fe2O3, Mn3O4, and ZnO as main components is still large, and the applicable frequency is low. Therefore, the research on the ferrite material with high frequency, wide temperature, low loss and high performance power is of great significance for the miniaturization of electronic products.

Disclosure of Invention

The technical problems to be solved by the invention are as follows: aiming at the problems of large power loss and low applicable frequency of the conventional soft magnetic ferrite material and magnetic core, the preparation method of the soft magnetic ferrite for high frequency is provided.

In order to solve the technical problems, the invention adopts the technical scheme that:

(1) adding ferric oxide, high-purity bismuth trioxide, yttrium-doped barium oxide, cobaltous oxide, zirconium oxide and tin oxide into absolute ethyl alcohol, placing the mixture into a ball mill, ball-milling the mixture for 2 ~ 4h at the normal temperature at the rotating speed of 300 ~ 400r/min, filtering the mixture, placing a filter cake into an oven at the temperature of 40 ~ 50 ℃ and drying the filter cake for 20 ~ 30min to obtain metal mixture powder;

(2) placing the metal mixture powder in a muffle furnace, presintering for 1 ~ 2h at the temperature of 700 ~ 800 ℃, and cooling to room temperature along with the furnace to obtain presintering powder;

(3) placing the pre-sintered powder in a grinding machine, grinding at the normal temperature at the rotating speed of 240 ~ 280r/min for 2 ~ 4h, then placing in a cold press for compression molding, and maintaining the pressure for 10 ~ 12s to obtain a pre-sintered biscuit;

(4) and (3) placing the pre-sintered element blank in a microwave sintering furnace, rapidly heating to 1200 ~ 1300 ℃ from the normal temperature, carrying out heat preservation sintering for 4 ~ 6h, and cooling to the room temperature along with the furnace to obtain the high-frequency soft magnetic ferrite.

The parts by weight of the ferric oxide, the high-purity bismuth trioxide, the yttrium-doped barium oxide, the cobaltous oxide, the zirconium oxide, the tin oxide and the absolute ethyl alcohol are 50 ~ parts of ferric oxide, 30 ~ parts of the high-purity bismuth trioxide, 10 ~ parts of the yttrium-doped barium oxide, 10 ~ parts of cobaltous oxide, 1 ~ parts of zirconium oxide, 1 ~ parts of tin oxide and 200 ~ parts of absolute ethyl alcohol.

The pressure of the compression molding in the step (3) is 120 ~ 140 MPa.

The heating rate in the step (4) is 25 ℃/min.

The specific preparation steps of the yttrium-doped barium oxide in the step (1) are as follows:

(1) adding barium chloride, yttrium chloride and absolute ethyl alcohol into deionized water, and stirring at the rotation speed of 200 ~ 240r/min for 10 ~ 12min at normal temperature to obtain a chloride mixed solution;

(2) adding ammonium bicarbonate into the mixed solution of chloride salt, stirring at the normal temperature at the rotation speed of 250 ~ 300r/min for 12 ~ 16min, placing in a hydrothermal reaction kettle, reacting at the temperature of 200 ~ 220 and 220 ℃ for 18 ~ 20h, and cooling at the normal temperature to obtain a mixed reactant;

(3) washing the mixed reactant with deionized water for 1 ~ 3 times, drying at normal temperature, placing in a muffle furnace, heating from normal temperature to 800 ~ 850 ℃, calcining for 1 ~ 2h at the constant temperature, and cooling to room temperature along with the furnace to obtain yttrium-doped barium oxide.

The barium chloride, the yttrium chloride, the ammonium bicarbonate, the absolute ethyl alcohol and the deionized water are 20 ~ 30 parts by weight of barium chloride, 4 ~ 6 parts by weight of yttrium chloride, 10 ~ 15 parts by weight of ammonium bicarbonate, 20 ~ 30 parts by weight of absolute ethyl alcohol and 60 ~ 90 parts by weight of deionized water.

The heating rate in the step (3) is 10 ℃/min.

The specific preparation steps of the high-purity bismuth trioxide described in the step (1) are as follows:

(1) adding bismuth nitrate and ethylene glycol into deionized water, and stirring at the rotation speed of 180 ~ 200r/min for 10 ~ 20min at normal temperature to obtain a bismuth nitrate mixed solution;

(2) adding ammonia water into the bismuth nitrate mixed solution, stirring at the rotation speed of 200 ~ 250r/min for 4 ~ 6min at normal temperature to obtain a bismuth ion reaction solution, placing the bismuth ion reaction solution into a hydrothermal reaction kettle, reacting for 20 ~ 24h at the temperature of 160 ~ 180 ℃, and cooling at normal temperature to obtain a bismuth metal reactant;

(3) washing the reactant with deionized water for 3 ~ 5 times, placing the reactant in an oven at 60 ~ 80 ℃ for drying for 40 ~ 60min to obtain a dried reactant, placing the dried reactant in a muffle furnace, heating the dried reactant from the normal temperature to 600 ~ 700 ℃ for heat preservation and calcination for 2 ~ 4h, and cooling the reactant to the room temperature along with the furnace to obtain the high-purity bismuth trioxide.

The weight parts of the bismuth nitrate, the ammonia water, the glycol and the deionized water are 20 ~ 30 parts of bismuth nitrate, 10 ~ 20 parts of ammonia water with the mass fraction of 10%, 40 ~ 60 parts of glycol and 40 ~ 60 parts of deionized water.

The heating rate in the step (3) is 5 ℃/min.

Compared with other methods, the method has the beneficial technical effects that:

(1) the invention takes ferric oxide, high-purity bismuth trioxide, yttrium-doped barium oxide and cobaltous oxide as raw materials to prepare a high-frequency soft magnetic ferrite, the ferrite prepared from multi-component metal oxide has large resistivity, higher dielectric property, small eddy current loss and large coercive force, thereby having ferromagnetism, ferroelectricity, ferromagnetism and piezoelectricity, and good magnetic conductivity under high frequency, and can effectively improve the working frequency of the soft magnetic ferrite, the ferric oxide can be combined with bismuth ions, barium ions and cobalt ions at high temperature to generate a hexagonal crystal structure compound, because barium ions with the radius close to that of oxygen ions exist in the crystal, the barium ions can participate in close packing together with the oxygen ions, thereby forming a hexagonal close packing structure, the hexagonal crystal structure is composed of four oxygen ion layers, the middle two layers respectively contain one barium ion, the structure enables barium-containing ferrite to have high coercive force, can effectively improve the working frequency of the ferrite, and because the barium oxide is doped with yttrium ions, the yttrium ions and iron ions can generate an yttrium iron garnet phase under a high-temperature condition, part of the yttrium ions enter a lattice structure of the hexaferrite in the sintering process, and the radius of the yttrium ions is closer to that of the iron ions, therefore, the yttrium ions have the tendency of occupying hexagonal octahedral sites, when part of the yttrium ions enter the lattice substitutive ions, lattice expansion can be caused, lattice instability and lattice distortion can be caused, the diffusion of solids is intensified, the progress of the sintering process is promoted, the compactness of the ferrite is improved, the demagnetizing field caused by air holes is reduced, the domain transfer is facilitated, the initial permeability is increased, after the yttrium ions are increased, on one hand, part of the ferric ions move to the tetrahedral sites to enable the ferrous ions and the ferric ions to be positioned in the octahedral sites The inter-electron transition is weakened, and on the other hand, the reduction of the average grain size contributes to the increase of the grain boundary resistance, resulting in the reduction of the real part of the dielectric constant. The reduction of the dielectric constant and the adjustability of the magnetic conductivity frequency characteristic are beneficial to the application of the ferrite material in the aspect of high-frequency inductance;

(2) the invention prepares the soft magnetic ferrite for high frequency by adding the zirconium oxide and the tin oxide, wherein the zirconium ion in the zirconium oxide has large radius, a high resistance layer can be formed at the crystal boundary of the ferrite, the crystal boundary resistivity of the material can be effectively improved, so that the high-frequency eddy current loss is reduced, the tin oxide belongs to a low-melting-point substance, the liquid phase sintering can be realized by adding the tin oxide, the sintering temperature is reduced, so that the grain size of the material is controlled, the tin ion in the tin oxide belongs to a non-magnetic ion, and the magnetic crystal anisotropy and the magnetostriction coefficient of the soft magnetic ferrite material can be adjusted by adding the tin oxide, so that the hysteresis loss of the material is controlled.

Detailed Description

Weighing 20 ~ 30 parts of bismuth nitrate, 10 ~ 20 parts of 10% ammonia water, 40 ~ 060 parts of ethylene glycol and 40 ~ 160 parts of deionized water according to parts by weight, adding bismuth nitrate and ethylene glycol into deionized water, stirring for 10 ~ min at a rotating speed of 180 ~ r/min at normal temperature to obtain a bismuth nitrate mixed solution, adding ammonia water into the bismuth nitrate mixed solution, stirring for 4 ~ min at a rotating speed of 200 ~ r/min at normal temperature to obtain a bismuth ion reaction solution, placing the bismuth ion reaction solution into a hydrothermal reaction kettle, reacting for 20 ~ h at a temperature of 160 ~ 6180 ℃, cooling at normal temperature to obtain a bismuth metal reactant, washing the reactant with deionized water for 3 ~ times, placing the reactant into an oven at 60 ~ ℃ for drying for 40min, obtaining a dry reactant, drying for 40 ~ min, placing the dry reactant into a muffle dry sintering furnace, heating from room temperature to 600 ℃ 0703672 ℃ at a temperature of ~, calcining for ~ h, calcining for a sintered bismuth oxide powder at a rotating speed of 5 ℃/min, placing the sintered bismuth oxide powder into a muffle 60min, placing into a dry bismuth oxide sintering furnace, placing a dry bismuth oxide powder at a sintered powder of ~, placing a sintered bismuth oxide powder of 3660 min at a sintered magnet under a rotating speed of 3660 min at a high-60 min, placing a high-temperature-60-600-36-.

Example 1

Respectively weighing 20 parts of bismuth nitrate, 10 parts of ammonia water with the mass fraction of 10%, 40 parts of ethylene glycol and 40 parts of deionized water according to the parts by weight, adding the bismuth nitrate and the ethylene glycol into the deionized water, stirring at the normal temperature at the rotating speed of 180r/min for 10min to obtain a bismuth nitrate mixed solution, adding ammonia water into the bismuth nitrate mixed solution, stirring at normal temperature at the rotating speed of 200r/min for 4min to obtain bismuth ion reaction solution, placing the bismuth ion reaction solution in a hydrothermal reaction kettle, reacting for 20 hours at 160 ℃, cooling at normal temperature to obtain a bismuth metal reactant, washing the reactant with deionized water for 3 times, placing the reactant in a 60 ℃ oven for drying for 40 minutes to obtain a dried reactant, placing the dried reactant in a muffle furnace, heating the temperature from the normal temperature to 600 ℃ at the heating rate of 5 ℃/min, carrying out heat preservation and calcination for 2 hours, and cooling to the room temperature along with the furnace to obtain high-purity bismuth trioxide; respectively weighing 20 parts of barium chloride, 4 parts of yttrium chloride, 10 parts of ammonium bicarbonate, 20 parts of absolute ethyl alcohol and 60 parts of deionized water according to parts by weight, adding the barium chloride, the yttrium chloride and the absolute ethyl alcohol into the deionized water, stirring at the normal temperature for 10min at the rotating speed of 200r/min to obtain a chloride mixed solution, adding the ammonium bicarbonate into the chloride mixed solution, stirring at the normal temperature for 12min at the rotating speed of 250r/min, placing the mixture into a hydrothermal reaction kettle, reacting for 18h at the temperature of 200 ℃, cooling at the normal temperature to obtain a mixed reactant, washing the mixed reactant with the deionized water for 1 time, drying at the normal temperature, then placing the washed reactant into a muffle furnace, heating from the normal temperature to 800 ℃ at the heating rate of 10 ℃/min, carrying out heat preservation and calcination for 1h, and cooling to the room temperature along with the furnace to obtain yttrium-doped barium; respectively weighing 50 parts of ferric oxide, 30 parts of high-purity bismuth oxide, 10 parts of yttrium-doped barium oxide, 10 parts of cobaltous oxide, 1 part of zirconium oxide, 1 part of tin oxide and 200 parts of absolute ethyl alcohol according to parts by weight, adding ferric oxide, high-purity bismuth oxide, yttrium-doped barium oxide, cobaltous oxide, zirconium oxide and tin oxide into absolute ethyl alcohol, placing the mixture into a ball mill, carrying out ball milling for 2 hours at the rotating speed of 300r/min at normal temperature, filtering, placing a filter cake into a drying oven at the temperature of 40 ℃ for drying for 20 minutes to obtain metal mixture powder, placing the metal mixture powder into a muffle furnace, presintering for 1 hour at the temperature of 700 ℃, cooling to room temperature along with the furnace to obtain presintering powder, placing the presintering powder into a grinding machine, grinding for 2 hours at the rotating speed of 240r/min at the normal temperature, placing into a cold press for pressing and molding at the pressure of 120MPa for 10 seconds, and (3) obtaining a pre-sintered element blank, placing the pre-sintered element blank in a microwave sintering furnace, heating from normal temperature to 1200 ℃ at the heating rate of 25 ℃/min, carrying out heat preservation sintering for 4h, and cooling to room temperature along with the furnace to obtain the high-frequency soft magnetic ferrite.

Example 2

Respectively weighing 25 parts of bismuth nitrate, 15 parts of ammonia water with the mass fraction of 10%, 50 parts of ethylene glycol and 50 parts of deionized water according to the parts by weight, adding the bismuth nitrate and the ethylene glycol into the deionized water, stirring at the normal temperature at the rotating speed of 190r/min for 15min to obtain a bismuth nitrate mixed solution, adding ammonia water into the bismuth nitrate mixed solution, stirring at normal temperature at 225r/min for 5min to obtain bismuth ion reaction solution, placing the bismuth ion reaction solution in a hydrothermal reaction kettle, reacting for 22 hours at 170 ℃, cooling at normal temperature to obtain a bismuth metal reactant, washing the reactant with deionized water for 4 times, placing the reactant in a 70 ℃ oven for drying for 50 minutes to obtain a dried reactant, placing the dried reactant in a muffle furnace, heating from the normal temperature to 650 ℃ at the heating rate of 5 ℃/min, carrying out heat preservation and calcination for 3 hours, and cooling to room temperature along with the furnace to obtain high-purity bismuth trioxide; respectively weighing 25 parts of barium chloride, 5 parts of yttrium chloride, 13 parts of ammonium bicarbonate, 25 parts of absolute ethyl alcohol and 75 parts of deionized water according to parts by weight, adding the barium chloride, the yttrium chloride and the absolute ethyl alcohol into the deionized water, stirring at the normal temperature at the rotating speed of 220r/min for 11min to obtain a chloride mixed solution, adding the ammonium bicarbonate into the chloride mixed solution, stirring at the normal temperature at the rotating speed of 275r/min for 14min, placing the mixture into a hydrothermal reaction kettle, reacting at the temperature of 210 ℃ for 19h, cooling at the normal temperature to obtain a mixed reactant, washing the mixed reactant with the deionized water for 2 times, drying at the normal temperature, then placing the washed reactant into a muffle furnace, heating from the normal temperature to 825 ℃ at the heating rate of 10 ℃/min, carrying out heat preservation and calcination for 1.5h, and cooling to the room temperature along with the furnace to obtain yttrium-doped; respectively weighing 55 parts by weight of ferric oxide, 33 parts by weight of high-purity bismuth oxide, 11 parts by weight of yttrium-doped barium oxide, 11 parts by weight of cobaltous oxide, 2 parts by weight of zirconium oxide, 2 parts by weight of tin oxide and 220 parts by weight of absolute ethyl alcohol, adding the ferric oxide, the high-purity bismuth oxide, the yttrium-doped barium oxide, the cobaltous oxide, the zirconium oxide and the tin oxide into the absolute ethyl alcohol, placing the mixture into a ball mill, ball-milling the mixture for 3 hours at the normal temperature at the rotating speed of 350r/min, filtering, placing a filter cake into a 45 ℃ oven, drying for 25 minutes to obtain metal mixture powder, placing the metal mixture powder into a muffle furnace, presintering the metal mixture powder for 1.5 hours at the temperature of 750 ℃, cooling the mixture to the room temperature to obtain presintering powder, placing the presintering powder into a grinding machine, grinding the presintering powder at the normal temperature at the rotating speed of 260r/min for 3 hours, placing the presintering powder into a cold press-forming machine at, and (3) obtaining a pre-sintered element blank, placing the pre-sintered element blank in a microwave sintering furnace, heating from normal temperature to 1250 ℃ at the heating rate of 25 ℃/min, carrying out heat preservation sintering for 5h, and cooling to room temperature along with the furnace to obtain the high-frequency soft magnetic ferrite.

Example 3

Respectively weighing 30 parts of bismuth nitrate, 20 parts of ammonia water with the mass fraction of 10%, 60 parts of ethylene glycol and 60 parts of deionized water according to the parts by weight, adding the bismuth nitrate and the ethylene glycol into the deionized water, stirring at the normal temperature at the rotating speed of 200r/min for 20min to obtain a bismuth nitrate mixed solution, adding ammonia water into the bismuth nitrate mixed solution, stirring at the normal temperature at the rotating speed of 250r/min for 6min to obtain a bismuth ion reaction solution, placing the bismuth ion reaction solution in a hydrothermal reaction kettle, reacting for 24 hours at 180 ℃, cooling at normal temperature to obtain a bismuth metal reactant, washing the reactant with deionized water for 5 times, placing the reactant in an oven at 80 ℃ for drying for 60 minutes to obtain a dried reactant, placing the dried reactant in a muffle furnace, heating the temperature from the normal temperature to 700 ℃ at the heating rate of 5 ℃/min, carrying out heat preservation and calcination for 4 hours, and cooling to the room temperature along with the furnace to obtain high-purity bismuth trioxide; respectively weighing 30 parts of barium chloride, 6 parts of yttrium chloride, 15 parts of ammonium bicarbonate, 30 parts of absolute ethyl alcohol and 90 parts of deionized water according to parts by weight, adding the barium chloride, the yttrium chloride and the absolute ethyl alcohol into the deionized water, stirring at 240r/min at normal temperature for 12min to obtain a chloride mixed solution, adding the ammonium bicarbonate into the chloride mixed solution, stirring at 300r/min at normal temperature for 16min, placing the mixture into a hydrothermal reaction kettle, reacting at 220 ℃ for 20h, cooling at normal temperature to obtain a mixed reactant, washing the mixed reactant with the deionized water for 3 times, drying at normal temperature, then placing the mixed reactant into a muffle furnace, heating from the normal temperature to 850 ℃ at a heating rate of 10 ℃/min, carrying out heat preservation and calcination for 2h, and cooling to the room temperature along with the furnace to obtain yttrium-doped barium oxide; then 60 parts of ferric oxide, 36 parts of high-purity bismuth trioxide, 12 parts of yttrium-doped barium oxide, 12 parts of cobaltous oxide, 3 parts of zirconium oxide, 3 parts of tin oxide and 240 parts of absolute ethyl alcohol are respectively weighed according to parts by weight, the ferric oxide, the high-purity bismuth trioxide, the yttrium-doped barium oxide, the cobaltous oxide, the zirconium oxide and the tin oxide are added into the absolute ethyl alcohol and are placed in a ball mill to be ball-milled for 4 hours at the rotating speed of 400r/min at normal temperature, the mixture is filtered, a filter cake is placed in a 50 ℃ oven to be dried for 30 minutes to obtain metal mixture powder, the metal mixture powder is placed in a muffle furnace to be presintered for 2 hours at the temperature of 800 ℃, the presintered powder is cooled to room temperature along with the furnace to obtain presintered powder, the presintered powder is placed in a grinding machine to be ground for 4 hours at the rotating speed of 280r/min at normal temperature and is placed in a cold press molding machine at the pressure of 140MPa for 12 seconds, and (3) obtaining a pre-sintered element blank, placing the pre-sintered element blank in a microwave sintering furnace, heating from normal temperature to 1300 ℃ at the heating rate of 25 ℃/min, carrying out heat preservation sintering for 6h, and cooling to room temperature along with the furnace to obtain the high-frequency soft magnetic ferrite.

The soft magnetic ferrite for high frequency prepared by the invention and the conventional soft magnetic ferrite on the market are detected, and the specific detection results are shown in the following table 1:

various prepared performances are measured by a U.S. 2330 power consumption meter, a CH100 tester and a Japanese research BHS-4 tester. (core loss was measured at 25 ℃ C. at 100Kc/200mT, and power loss was measured at 25 ℃ C. at 1MHz and 30 mT.)

Table 1 characterization of high frequency soft magnetic ferrite properties

As can be seen from Table 1, the soft magnetic ferrite for high frequency prepared by the invention has the advantages of small magnetic core loss, small power loss and wide application range.

Claims

1. A preparation method of a soft magnetic ferrite for high frequency is characterized by comprising the following specific preparation steps:

2. The method of claim 1, wherein the parts by weight of said iron trioxide, said high purity bismuth trioxide, said yttrium-doped barium oxide, said cobalt trioxide, said zirconium oxide, said tin oxide, and said absolute ethyl alcohol are 50 ~ 60 parts of iron trioxide, 30 ~ 36 parts of high purity bismuth trioxide, 10 ~ 12 parts of yttrium-doped barium oxide, 10 ~ 12 parts of cobalt trioxide, 1 ~ 3 parts of zirconium oxide, 1 ~ 3 parts of tin oxide, and 200 ~ 240 parts of absolute ethyl alcohol.

3. The method of preparing a soft magnetic ferrite for high frequency as set forth in claim 1, wherein the pressure of said press-molding in the step (3) is 120 ~ 140 MPa.

4. The method for preparing a soft magnetic ferrite for high frequency as claimed in claim 1, wherein the temperature rising rate in the step (4) is 25 ℃/min.

5. The method for preparing a soft magnetic ferrite for high frequency as claimed in claim 1, wherein the specific preparation steps of yttrium-doped barium oxide in step (1) are as follows:

6. The method of claim 5, wherein the weight parts of barium chloride, yttrium chloride, ammonium bicarbonate, absolute ethyl alcohol and deionized water are 20 ~ 30 parts of barium chloride, 4 ~ 6 parts of yttrium chloride, 10 ~ 15 parts of ammonium bicarbonate, 20 ~ 30 parts of absolute ethyl alcohol and 60 ~ 90 parts of deionized water.

7. The method for preparing a soft magnetic ferrite for high frequency as claimed in claim 5, wherein the temperature rising rate in the step (3) is 10 ℃/min.

8. The method for preparing a soft magnetic ferrite for high frequency as claimed in claim 1, wherein the specific preparation steps of the high purity bismuth trioxide of step (1) are as follows:

9. The method for preparing a soft magnetic ferrite for high frequency as claimed in claim 8, wherein the weight parts of bismuth nitrate, ammonia water, ethylene glycol and deionized water are 20 ~ 30 parts of bismuth nitrate, 10 ~ 20 parts of 10% ammonia water by mass fraction, 40 ~ 60 parts of ethylene glycol and 40 ~ 60 parts of deionized water.

10. The method for preparing a soft magnetic ferrite for high frequency as claimed in claim 8, wherein the temperature rising rate in the step (3) is 5 ℃/min.