A large magnetic field high power density soft magnetic ferrite material and a preparation method thereof

Abstract

The application belongs to the technical field of soft magnetic ferrite material, and discloses a preparation method of a high-power-density soft magnetic ferrite material, which comprises the following steps: (1) accurately weighing main materials Fe2O3, Mn3O4 and ZnO according to proportions to prepare a powder with uniform particle distribution; (2) pre-sintering the powder in air to obtain a manganese-zinc ferrite pre-sintered powder; (3) mixing the obtained pre-sintered powder, auxiliary additives and a dispersing agent according to proportions, and performing secondary ball milling to obtain a powder; (4) adding polyvinyl alcohol into the obtained powder to press a green body; and (5) sintering the green body to obtain a final soft magnetic ferrite material; the application provides a high-power-density soft magnetic ferrite material with the effects of high saturation magnetic induction intensity and low loss.

Description

Technical Field

[0001] This invention relates to the field of soft magnetic ferrite core technology, and particularly to a soft magnetic ferrite material with high magnetic field and high power density. Background Technology

[0002] Soft magnetic materials are magnetic materials that are not magnetic in themselves, but become magnetic when they are in a magnetic field and lose their magnetism when they are removed. They are characterized by high resistivity, low loss and high permeability.

[0003] In modern life, MnZn power ferrites, due to their excellent properties such as low loss, high permeability, high resistivity, and high saturation flux density, are used to manufacture transformers, sensors, magnetic deflection devices, DC / DC converters, and other devices. They are widely used in communications, remote monitoring, computers, automotive electronics, home appliances, green lighting, office automation, audio-visual equipment, and electronic information equipment. However, compared with soft magnetic metals, ferrites are subferromagnetic materials. Therefore, the main disadvantage of MnZn ferrites is their lower saturation flux density (Bs), typically only one-half to one-third that of metal magnetic powder cores, making their DC bias resistance worse than that of soft magnetic metals.

[0004] Therefore, it is necessary to study a soft magnetic ferrite material with high saturation magnetic induction intensity and low loss. Summary of the Invention

[0005] The purpose of this invention is to provide a soft magnetic ferrite material with a large magnetic field and high power density, which has the effects of high saturation magnetic induction intensity and low loss.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0007] A method for preparing a high-power-density soft magnetic ferrite material with a large magnetic field includes the following steps:

[0008] (1) The main materials Fe2O3, Mn3O4 and ZnO are weighed in proportion and then stirred and slurried, sand-milled and stirred and glued to obtain a slurry with uniform distribution and suitable particle size. The slurry is spray-dried to obtain powder with uniform particle distribution.

[0009] (2) The powder obtained in step (1) is pre-sintered in air using a natural gas rotary kiln to obtain manganese zinc ferrite pre-sintered powder. It passes through four temperature zones in succession, with temperatures and times of 500℃ for 30 min, 900℃ for 60 min, 900℃ for 60 min, and 850℃ for 30 min.

[0010] (3) Mix the ferrite pre-calcined powder, auxiliary additives and dispersant obtained in step (2) in proportion, and put the mixed material into a ball mill for secondary ball milling. After ball milling for 80 minutes, put the material into a vacuum drying oven and dry it at 150°C for 3 hours to obtain powder.

[0011] (4) Granulation and molding: Add 8% polyvinyl alcohol to the powder obtained in step (3) and stir for 15 minutes. After mixing, press the granules into green blanks using a hydraulic press.

[0012] (5) Sintering: After heat preservation and debinding of the green blank formed in step (4), sintering is carried out using a specific sintering curve to obtain the final soft magnetic ferrite material.

[0013] As a further provision of the present invention, in step (5), the following sintering curve is used for sintering: the initial temperature is 25°C, the temperature is increased at a rate of 2°C / min, and after the temperature reaches 720°C, the oxygen content is controlled between 3% and 4%, and the temperature is held for 2 hours. Then the temperature is increased at a rate of 5°C / min, and after the temperature reaches 1200°C, the oxygen content is reduced to between 1% and 2%, and the temperature is held for 6-7 hours. Finally, the temperature is cooled in a balanced atmosphere, and the temperature is reduced from 1200°C to 25°C at a cooling rate of 3°C / min.

[0014] As a further provision of the present invention, the main material in step (1) comprises the following components and proportions by weight: 69.10-71.90 parts Fe2O3, 22.20-23.15 parts Mn3O4, and 4.95-7.75 parts ZnO.

[0015] As a further provision of the present invention, the auxiliary additives in step (1) include the following components and proportions by weight fraction: 0.02-0.05 parts CaCO3, 0.03-0.05 parts SnO2, 0.02-0.04 parts In2O3, and 0.01-0.02 parts La2O3.

[0016] As a further provision of the present invention, the dispersant in step (1) is 5-7 parts of a 50% aqueous solution of polyacrylic acid, by weight.

[0017] As a further provision of the present invention, the auxiliary additive in step (1) further includes 0.01-0.03 parts of CuO by weight.

[0018] As a further provision of the present invention, the auxiliary additive in step (1) further includes 0.01-0.02 parts of Sb2O3 by weight.

[0019] As a further feature of the invention, it also includes a dispersant, which is 5-7 parts by weight of a 50% aqueous solution of polyacrylic acid.

[0020] As a further feature of the present invention, the auxiliary additives further include 0.01-0.03 parts of CuO by weight.

[0021] As a further feature of the present invention, the auxiliary additive further includes 0.01-0.02 parts of Sb2O3 by weight.

[0022] The beneficial effects of this invention are:

[0023] 1. The soft magnetic ferrite material of the present invention is MnZn ferrite. It is prepared by using special reaction main material and auxiliary additives, combined with a preparation method of soft magnetic ferrite material with high saturation magnetic flux density and low power loss after magnetic flux density saturation.

[0024] 2. In the soft magnetic ferrite material prepared by this invention, In2O3 and SnO2 are added during the sintering process. On the one hand, In... 3+ and Sn 4+ Ion doping can partially replace Fe 3+ Ions, In 3+ and Sn 4+ Ionic radius greater than Fe 3+ The difference in ion size leads to an increase in lattice defects in ferrites, enhancing the sintering activity of the material and thus promoting sintering. Furthermore, In... 3+ and Sn 4+ Ion doping may cause lattice distortion, reducing the cell volume and thus increasing the material density; meanwhile, In 3+ and Sn 4+ The ions are non-magnetic ions, when an appropriate amount of In... 3+ and Sn 4+ Doping and substituting part of Fe 3+ When In enters the octahedral a-site, it reduces the total ionic magnetic moment at the a-site, thereby increasing the total magnetic moment of the molecule and resulting in increased saturation magnetization; therefore, an appropriate amount of In... 3+ and Sn 4+ Ion doping can reduce the magnetocrystalline anisotropy constant of a material, while improving its microstructure, promoting grain growth, increasing its density, and reducing porosity, thereby reducing the ferromagnetic resonance linewidth. On the other hand, a small amount of In... 3+ and Sn 4+ Indium tin compound films with good conductivity can also be formed at grain boundaries (under high temperature conditions, indium compounds and tin compounds will react to form indium tin compounds), thereby reducing Zn volatilization during high-temperature sintering and further reducing dielectric loss.

[0025] 3. This invention incorporates Sb₂O₃. The low-melting-point Sb₂O₃ (650℃) forms a liquid phase during sintering. On one hand, the liquid Sb₂O₃ penetrates into the material, filling internal pores, reducing porosity, and effectively increasing density. Simultaneously, the liquid Sb₂O₃ increases the wettability of the main material, promoting ion diffusion and accelerating densification, thus speeding up grain growth and effectively increasing the saturation flux density of the soft magnet. On the other hand, In… 3+ and Sn 4+ The lattice expansion caused by ions makes Sb 3 + Ions readily enter the crystal lattice because Sb 3+ The 6p electrons of the ion have strong spin-orbit coupling, which, in the spinel crystal structure, is achieved through O 2- Ions make Fe 3+ The ions also possess strong spin-orbit coupling, which leads to the Fe under the influence of the crystal field. 3+ The 3d electron orbital angular momentum of the ion changes from a frozen state to a partially thawed state when Sb 3+ As ions gradually enter the crystal lattice, the increase in grain boundary resistivity and the reduction in vacancies inside the crystal also reduce dielectric loss.

[0026] 4. This invention incorporates CuO, which provides Cu during the sintering process. 2+ Cu can enter the ferrite lattice and undergo a substitution reaction to form CuFe₂O₄, which then dissolves in the ferrite and occupies the B site. 2+ At a lower temperature (720℃), four O-shaped structures are coplanar with their surroundings. 2- Forming covalent bonds, and with the two O atoms in the linear direction. 2- The formation of ionic bonds, due to the difference in valence, causes distortion of the entire crystal lattice, which to some extent increases the first process in sintering (densification and grain growth within individual agglomerates), resulting in larger agglomerates, promoting the effective elimination of porosity between agglomerates and further growth of ferrite grains.

[0027] 5. Polyacrylic acid with a 50% aqueous solution is added as a dispersant during the secondary ball milling process to make the mixing between the pre-sintered powder and the small amount of auxiliary additives more uniform. This can promote the ion exchange reaction between the auxiliary additives and the powder during the subsequent sintering process. Then, during the drying process at 150°C, the polyacrylic acid is removed to avoid the polyacrylic acid affecting the subsequent sintering process. Detailed Implementation

[0028] The technical solution of the present invention will now be clearly and completely described with reference to specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0029] I. Implementation Examples

[0030] Example 1

[0031] A high-magnetic-field, high-power-density soft magnetic ferrite material comprises, by weight fraction: 69.10 parts Fe2O3, 23.15 parts Mn3O4, 7.75 parts ZnO, 0.02 parts CaCO3, 0.03 parts SnO2, 0.02 parts La2O3, 5 parts polyacrylic acid in 50% aqueous solution, 0.03 parts CuO, and 0.01 parts Sb2O3.

[0032] A method for preparing a high-power-density soft magnetic ferrite material with a large magnetic field includes the following steps:

[0033] (1) The main materials Fe2O3, Mn3O4 and ZnO are weighed in proportion and then stirred and slurried, sand-milled and stirred and glued to obtain a slurry with uniform distribution and suitable particle size. The slurry is spray-dried to obtain powder with uniform particle distribution.

[0034] (2) The powder obtained in step (1) is pre-sintered in air using a natural gas rotary kiln to obtain manganese zinc ferrite pre-sintered powder. It passes through four temperature zones in succession, with temperatures and times of 500℃ for 30 min, 900℃ for 60 min, 900℃ for 60 min, and 850℃ for 30 min.

[0035] (3) Mix the ferrite powder, auxiliary additives and dispersant obtained in step (2) in proportion, and put the mixed material into a ball mill for secondary ball milling. After ball milling for 80 minutes, put the material into a vacuum drying oven and dry it at 150°C for 3 hours to obtain powder.

[0036] (4) Granulation and molding: Add 8% polyvinyl alcohol to the powder obtained in step (3) and stir for 15 minutes. After mixing, press the granules into green blanks using a hydraulic press.

[0037] (5) Sintering: After heat preservation and debinding of the green body formed in step (4), sintering is carried out. The initial temperature is 25℃, and the temperature is increased at a rate of 2℃ / min. After the temperature reaches 720℃, the oxygen content is controlled between 3% and 4%, and the temperature is held for 2 hours. Then the temperature is increased at a rate of 5℃ / min. After the temperature reaches 1200℃, the oxygen content is reduced to between 1% and 2%, and the temperature is held for 6-7 hours. Finally, the temperature is cooled in a balanced atmosphere. The temperature is reduced from 1200℃ to 25℃ at a cooling rate of 3℃ / min to obtain the final soft magnetic ferrite material.

[0038] A standard ring with an outer diameter of 25 mm, an inner diameter of 15 mm, and a height of 7.5 mm was finally obtained for testing. Magnetic properties and power loss were tested using a SY8232B-H analyzer; resistivity was tested using an RTS-9 dual-electric four-probe tester; and density was measured using the Archimedes displacement method. The results are shown in Table 1 below:

[0039] Table 1 Test results of the samples

[0040]

[0041] Example 2

[0042] A high-magnetic-field, high-power-density soft magnetic ferrite material comprises, by weight fraction: 69.80 parts Fe2O3, 22.90 parts Mn3O4, 7.30 parts ZnO, 0.04 parts CaCO3, 0.02 parts In2O3, 0.02 parts La2O3, 7 parts polyacrylic acid in 50% aqueous solution, 0.03 parts CuO, and 0.01 parts Sb2O3.

[0043] A method for preparing a high-power-density soft magnetic ferrite material with a large magnetic field includes the following steps:

[0044] (1) The main materials Fe2O3, Mn3O4 and ZnO are weighed in proportion and then stirred and slurried, sand-milled and stirred and glued to obtain a slurry with uniform distribution and suitable particle size. The slurry is spray-dried to obtain powder with uniform particle distribution.

[0045] (2) The powder obtained in step (1) is pre-sintered in air using a natural gas rotary kiln to obtain manganese zinc ferrite pre-sintered powder. It passes through four temperature zones in succession, with temperatures and times of 500℃ for 30 min, 900℃ for 60 min, 900℃ for 60 min, and 850℃ for 30 min.

[0046] (3) Mix the ferrite powder, auxiliary additives and dispersant obtained in step (2) in proportion, and put the mixed material into a ball mill for secondary ball milling. After ball milling for 80 minutes, put the material into a vacuum drying oven and dry it at 150°C for 3 hours to obtain powder.

[0047] (4) Granulation and molding: Add 8% polyvinyl alcohol to the powder obtained in step (3) and stir for 15 minutes. After mixing, press the granules into green blanks using a hydraulic press.

[0048] (5) Sintering: After heat preservation and debinding of the green body formed in step (4), sintering is carried out. The initial temperature is 25℃, and the temperature is increased at a rate of 2℃ / min. After the temperature reaches 720℃, the oxygen content is controlled between 3% and 4%, and the temperature is held for 2 hours. Then the temperature is increased at a rate of 5℃ / min. After the temperature reaches 1200℃, the oxygen content is reduced to between 1% and 2%, and the temperature is held for 6-7 hours. Finally, the temperature is cooled in a balanced atmosphere. The temperature is reduced from 1200℃ to 25℃ at a cooling rate of 3℃ / min to obtain the final soft magnetic ferrite material.

[0049] A standard ring with an outer diameter of 25 × an inner diameter of 15 × a height of 7.5 was finally obtained for testing. Magnetic properties and power loss were tested using a SY8232B-H analyzer, resistivity was tested using an RTS-9 dual-electric four-probe tester, and density was measured using the Archimedes' displacement method. The results are shown in Table 2 below:

[0050] Table 2 Test results of the samples

[0051]

[0052]

[0053] Example 3

[0054] A high-magnetic-field, high-power-density soft magnetic ferrite material comprises the following components by weight fraction: 70.50 parts Fe2O3, 23.00 parts Mn3O4, 6.50 parts ZnO, 0.05 parts CaCO3, 0.05 parts SnO2, 0.04 parts In2O3, 0.01 parts La2O3, 0.01 parts CuO, and 0.02 parts Sb2O3.

[0055] A method for preparing a high-power-density soft magnetic ferrite material with a large magnetic field includes the following steps:

[0056] (1) The main materials Fe2O3, Mn3O4 and ZnO are weighed in proportion and then stirred and slurried, sand-milled and stirred and glued to obtain a slurry with uniform distribution and suitable particle size. The slurry is spray-dried to obtain powder with uniform particle distribution.

[0057] (2) The powder obtained in step (1) is pre-sintered in air using a natural gas rotary kiln to obtain manganese zinc ferrite pre-sintered powder. It passes through four temperature zones in succession, with temperatures and times of 500℃ for 30 min, 900℃ for 60 min, 900℃ for 60 min, and 850℃ for 30 min.

[0058] (3) Mix the ferrite powder, auxiliary additives and dispersant obtained in step (2) in proportion, and put the mixed material into a ball mill for secondary ball milling. After ball milling for 80 minutes, put the material into a vacuum drying oven and dry it at 150°C for 3 hours to obtain powder.

[0059] (4) Granulation and molding: Add 8% polyvinyl alcohol to the powder obtained in step (3) and stir for 15 minutes. After mixing, press the granules into green blanks using a hydraulic press.

[0060] (5) Sintering: After heat preservation and debinding of the green body formed in step (4), sintering is carried out. The initial temperature is 25℃, and the temperature is increased at a rate of 2℃ / min. After the temperature reaches 720℃, the oxygen content is controlled between 3% and 4%, and the temperature is held for 2 hours. Then the temperature is increased at a rate of 5℃ / min. After the temperature reaches 1200℃, the oxygen content is reduced to between 1% and 2%, and the temperature is held for 6-7 hours. Finally, the temperature is cooled in a balanced atmosphere. The temperature is reduced from 1200℃ to 25℃ at a cooling rate of 3℃ / min to obtain the final soft magnetic ferrite material.

[0061] The final standard ring with an outer diameter of 25 × inner diameter of 15 × height of 7.5 was tested. Magnetic properties and power loss were measured using a SY8232B-H analyzer, resistivity was measured using an RTS-9 dual-electric four-probe tester, and density was measured using the Archimedes' displacement method. The results are shown in Table 3 below.

[0062] Table 3 Test results of the samples

[0063]

[0064]

[0065] Example 4

[0066] A high-magnetic-field, high-power-density soft magnetic ferrite material comprises, by weight fraction: 71.20 parts Fe2O3, 22.20 parts Mn3O4, 6.60 parts ZnO, 0.02 parts CaCO3, 0.03 parts SnO2, 0.02 parts In2O3, 0.01 parts La2O3, 7 parts polyacrylic acid in 50% aqueous solution, and 0.02 parts Sb2O3.

[0067] A method for preparing a high-power-density soft magnetic ferrite material with a large magnetic field includes the following steps:

[0068] (1) The main materials Fe2O3, Mn3O4 and ZnO are weighed in proportion and then stirred and slurried, sand-milled and stirred and glued to obtain a slurry with uniform distribution and suitable particle size. The slurry is spray-dried to obtain powder with uniform particle distribution.

[0069] (2) The powder obtained in step (1) is pre-sintered in air using a natural gas rotary kiln to obtain manganese zinc ferrite pre-sintered powder. It passes through four temperature zones in succession, with temperatures and times of 500℃ for 30 min, 900℃ for 60 min, 900℃ for 60 min, and 850℃ for 30 min.

[0070] (3) Mix the ferrite powder, auxiliary additives and dispersant obtained in step (2) in proportion, and put the mixed material into a ball mill for secondary ball milling. After ball milling for 80 minutes, put the material into a vacuum drying oven and dry it at 150°C for 3 hours to obtain powder.

[0071] (4) Granulation and molding: Add 8% polyvinyl alcohol to the powder obtained in step (3) and stir for 15 minutes. After mixing, press the granules into green blanks using a hydraulic press.

[0072] (5) Sintering: After heat preservation and debinding of the green body formed in step (4), sintering is carried out. The initial temperature is 25℃, and the temperature is increased at a rate of 2℃ / min. After the temperature reaches 720℃, the oxygen content is controlled between 3% and 4%, and the temperature is held for 2 hours. Then the temperature is increased at a rate of 5℃ / min. After the temperature reaches 1200℃, the oxygen content is reduced to between 1% and 2%, and the temperature is held for 6-7 hours. Finally, the temperature is cooled in a balanced atmosphere. The temperature is reduced from 1200℃ to 25℃ at a cooling rate of 3℃ / min to obtain the final soft magnetic ferrite material.

[0073] Finally, a standard ring with an outer diameter of 25 × an inner diameter of 15 × a height of 7.5 was obtained for testing. The magnetic properties and power loss were tested using a SY8232B-H analyzer, the resistivity of the sample was tested using an RTS-9 dual-electric four-probe tester, and the density of the sample was measured using the Archimedes' displacement method. The results are shown in Table 4 below:

[0074] Table 4 Test results of the samples

[0075]

[0076] Example 5

[0077] A high-magnetic-field, high-power-density soft magnetic ferrite material comprises, by weight fraction, the following components: 71.90 parts Fe2O3, 23.15 parts Mn3O4, 4.95 parts ZnO, 0.05 parts CaCO3, 0.05 parts SnO2, 0.04 parts In2O3, 0.02 parts La2O3, 5 parts polyacrylic acid in 50% aqueous solution, and 0.03 parts CuO.

[0078] A method for preparing a high-power-density soft magnetic ferrite material with a large magnetic field includes the following steps:

[0079] (1) The main materials Fe2O3, Mn3O4 and ZnO are weighed in proportion and then stirred and slurried, sand-milled and stirred and glued to obtain a slurry with uniform distribution and suitable particle size. The slurry is spray-dried to obtain powder with uniform particle distribution.

[0080] (2) The powder obtained in step (1) is pre-sintered in air using a natural gas rotary kiln to obtain manganese zinc ferrite pre-sintered powder. It passes through four temperature zones in succession, with temperatures and times of 500℃ for 30 min, 900℃ for 60 min, 900℃ for 60 min, and 850℃ for 30 min.

[0081] (3) Mix the ferrite powder, auxiliary additives and dispersant obtained in step (2) in proportion, and put the mixed material into a ball mill for secondary ball milling. After ball milling for 80 minutes, put the material into a vacuum drying oven and dry it at 150°C for 3 hours to obtain powder.

[0082] (4) Granulation and molding: Add 8% polyvinyl alcohol to the powder obtained in step (3) and stir for 15 minutes. After mixing, press the granules into green blanks using a hydraulic press.

[0083] (5) Sintering: After heat preservation and debinding of the green body formed in step (4), sintering is carried out. The initial temperature is 25℃, and the temperature is increased at a rate of 2℃ / min. After the temperature reaches 720℃, the oxygen content is controlled between 3% and 4%, and the temperature is held for 2 hours. Then the temperature is increased at a rate of 5℃ / min. After the temperature reaches 1200℃, the oxygen content is reduced to between 1% and 2%, and the temperature is held for 6-7 hours. Finally, the temperature is cooled in a balanced atmosphere. The temperature is reduced from 1200℃ to 25℃ at a cooling rate of 3℃ / min to obtain the final soft magnetic ferrite material.

[0084] Finally, a standard ring with an outer diameter of 25 × an inner diameter of 15 × a height of 7.5 was obtained for testing. The magnetic properties and power loss were tested using a SY8232B-H analyzer, the resistivity of the sample was tested using an RTS-9 dual-electric four-probe tester, and the density of the sample was measured using the Archimedes' displacement method. The results are shown in Table 5 below:

[0085] Table 5 Test results of the samples

[0086]

[0087] Example 6

[0088] A high-magnetic-field, high-power-density soft magnetic ferrite material comprises, by weight fraction, the following components: 71.00 parts Fe2O3, 23.00 parts Mn3O4, 6.00 parts ZnO, 0.05 parts CaCO3, 0.03 parts SnO2, 0.02 parts In2O3, 0.01 parts La2O3, 5 parts polyacrylic acid in 50% aqueous solution, 0.01 parts CuO, and 0.01 parts Sb2O3.

[0089] A method for preparing a high-power-density soft magnetic ferrite material with a large magnetic field includes the following steps:

[0090] (1) The main materials Fe2O3, Mn3O4 and ZnO are weighed in proportion and then stirred and slurried, sand-milled and stirred and glued to obtain a slurry with uniform distribution and suitable particle size. The slurry is spray-dried to obtain powder with uniform particle distribution.

[0091] (2) The powder obtained in step (1) is pre-sintered in air using a natural gas rotary kiln to obtain manganese zinc ferrite pre-sintered powder. It passes through four temperature zones in succession, with temperatures and times of 500℃ for 30 min, 900℃ for 60 min, 900℃ for 60 min, and 850℃ for 30 min.

[0092] (3) Mix the ferrite powder, auxiliary additives and dispersant obtained in step (2) in proportion, and put the mixed material into a ball mill for secondary ball milling. After ball milling for 80 minutes, put the material into a vacuum drying oven and dry it at 150°C for 3 hours to obtain powder.

[0093] (4) Granulation and molding: Add 8% polyvinyl alcohol to the powder obtained in step (3) and stir for 15 minutes. After mixing, press the granules into green blanks using a hydraulic press.

[0094] (5) Sintering: After heat preservation and debinding of the green body formed in step (4), sintering is carried out. The initial temperature is 25℃, and the temperature is increased at a rate of 2℃ / min. After the temperature reaches 720℃, the oxygen content is controlled between 3% and 4%, and the temperature is held for 2 hours. Then the temperature is increased at a rate of 5℃ / min. After the temperature reaches 1200℃, the oxygen content is reduced to between 1% and 2%, and the temperature is held for 6-7 hours. Finally, the temperature is cooled in a balanced atmosphere. The temperature is reduced from 1200℃ to 25℃ at a cooling rate of 3℃ / min to obtain the final soft magnetic ferrite material.

[0095] Finally, a standard ring with an outer diameter of 25 × an inner diameter of 15 × a height of 7.5 was obtained for testing. The magnetic properties and power loss were tested using a SY8232B-H analyzer, the resistivity of the sample was tested using an RTS-9 dual-electric four-probe tester, and the density of the sample was measured using the Archimedes' displacement method. The results are shown in Table 6 below:

[0096] Table 6 Test results of the samples

[0097]

[0098] It can be seen that the initial permeability μi of the final product reaches over 1000, and the power loss is 400kW / m under high temperature conditions of 100℃, 5MHz, and 30mT. 3 Below this, the Bs value at 100℃ is above 480mT.

[0099] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0100] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A method for preparing a high-power-density soft magnetic ferrite material with a large magnetic field, characterized in that, Includes the following steps: (1) The main materials Fe2O3, Mn3O4 and ZnO are weighed in proportion and then stirred and slurried, sand-milled and stirred and glued to obtain a slurry with uniform distribution and suitable particle size. The slurry is spray-dried to obtain powder with uniform particle distribution. (2) The powder obtained in step (1) is pre-sintered in air using a natural gas rotary kiln to obtain manganese zinc ferrite pre-sintered powder. It passes through four temperature zones in succession, with temperatures and times of 500℃ for 30 min, 900℃ for 60 min, 900℃ for 60 min, and 850℃ for 30 min. (3) Mix the ferrite pre-calcined powder, auxiliary additives and dispersant obtained in step (2) in proportion, and put the mixed material into a ball mill jar for secondary ball milling. After ball milling for 80 minutes, put the material into a vacuum drying oven and dry it at 150°C for 3 hours to obtain powder. (4) Granulation and molding: Add 8% polyvinyl alcohol to the powder obtained in step (3) and stir for 15 minutes. After mixing, press the granules into green blanks using a hydraulic press. (5) Sintering: After heat preservation and debinding of the green body formed in step (4), sintering is carried out using a specific sintering curve to obtain the final soft magnetic ferrite material. By weight fraction, the main material mentioned in step (1) includes the following components and proportions: 69.10-71.90 parts Fe2O3, 22.20-23.15 parts Mn3O4, and 4.95-7.75 parts ZnO; By weight fraction, the auxiliary additives mentioned in step (1) include the following components and proportions: 0.02-0.05 parts CaCO3, 0.03-0.05 parts SnO2, 0.02-0.04 parts In2O3, and 0.01-0.02 parts La2O3; The auxiliary additives in step (1) also include 0.01-0.03 parts CuO by weight. The auxiliary additives in step (1) also include 0.01-0.02 parts of Sb2O3 by weight.

2. The method for preparing a high-power-density soft magnetic ferrite material with a large magnetic field according to claim 1, characterized in that: In step (5), the following sintering curve is used for sintering: the initial temperature is 25℃, the temperature is increased at a rate of 2℃ / min, and after the temperature reaches 720℃, the oxygen content is controlled between 3% and 4%, and the temperature is held for 2 hours. Then the temperature is increased at a rate of 5℃ / min, and after the temperature reaches 1200℃, the oxygen content is reduced to between 1% and 2%, and the temperature is held for 6-7 hours. Finally, the temperature is cooled in a balanced atmosphere, and the temperature is reduced from 1200℃ to 25℃ at a cooling rate of 3℃ / min.

3. A high-power-density soft magnetic ferrite material with a large magnetic field obtained by the preparation method according to claim 1, characterized in that: The dispersant in step (1) is 5-7 parts by weight of a 50% aqueous solution of polyacrylic acid.

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