Method for producing a soft magnetic manganese-zinc ferrite with ultra-high frequency, high magnetic permeability and low loss

Abstract

A process for producing a soft magnetic manganese-zinc ferrite with ultra-high frequency, high magnetic permeability, and low loss, characterized in that the soft magnetic manganese-zinc ferrite material with ultra-high frequency, high magnetic permeability, and low loss comprises main components and auxiliary components, wherein the main components comprise Fe₂O₃: 73.5 to 76.5 wt.%, ZnO: 1.4 to 3.0 wt.%, MoO₃: 0.01 to 0.04 wt.%, the remainder being Mn₃O₄, wherein, based on the total weight of the main components, the auxiliary components comprise CaCO₃: 400 to 600 ppm, ZrO₂: 100 to 300 ppm, TiO₂: 500 to 800 ppm, Co₂O₃: 1500 to 4000 ppm, CuO: 50 to 200 ppm, wherein the process for producing soft magnetic Manganese-zinc ferrite with ultra-high frequency, high magnetic permeability and low loss exhibits the following steps: Step 1, Preparation: Fe2O3, ZnO, MoO3 and Mn3O4 are weighed according to their proportions and then mixed by wet grinding, with a mixing time of 10 to 20 minutes; Step 2, Pre-burning: the mixture obtained from step 1 is dried and then pre-burned, with the pre-burning taking place in air, the pre-burning temperature being 800 to 1000 °C and the temperature rise rate being 3 to 5 °C / minute; Step 3, Grinding: the pre-burned material obtained from step 2 is shaken and then the auxiliary components are added according to the proportions: CaCO3, ZrO2, TiO2, Co2O3, CuO and ground, with the grinding time being 30 to 90 minutes; Step 4, Granulation: the ground slurry is dried and granulated; Step 5, Pressing and Forming: it is pressed into a ring-shaped green body with the dimensions ϕ12.5mm*ϕ7.5mm*7mm; Step 6, sintering, where the sintering temperature is 1000 to 1200 °C, the holding time is 4 to 8 hours and the equilibrium oxygen content is 1.5 to 3.0 %; Step 7, annealing, in which the fired product is annealed under vacuum conditions, the temperature is increased to 600 to 900 °C under vacuum conditions, and the product is kept warm for 2 to 4 hours.

Description

Technical field

[0001] The invention relates to the production of a soft magnetic manganese-zinc ferrite with ultra-high frequency, high magnetic permeability and low loss, and belongs to the technical field of magnetic materials. State of the art

[0002] With the development of microelectronics technology, the performance of conventional silicon and gallium nitride (GaN) semiconductor devices has approached the theoretical limit determined by the materials themselves. Third-generation semiconductor materials, consisting of silicon carbide (SiC) and gallium nitride (GaN)—wide-bandgap semiconductors—have, however, become an ideal alternative for the fabrication of high-performance, high-frequency, and radiation-resistant electronic devices due to their outstanding advantages such as a large bandgap, high saturation drift rate, and high critical breakdown field. The current operating frequency of high-frequency transformers already exceeds 1 MHz, and with advances in science and technology, the future trend is toward frequencies above 5 MHz.Currently, NiZn ferrite is the standard material for operating frequencies above 5 MHz, but its cost is much higher than that of MnZn ferrite. Therefore, to meet the high-frequency requirements of magnetic devices and to further reduce costs, the development of a new generation of high-performance soft magnetic materials with ultra-high frequency, low loss, high magnetic permeability, and high DC bias capability in the 6 MHz to 8 MHz frequency band is necessary.

[0003] Chinese patent number CN106830913B discloses a method for producing high-frequency, high-saturation magnetic flux density, and low-loss MnZn ferrite, the formula and process of which differ significantly from those of the present invention. It does not address magnetic permeability, and the applicable frequency does not exceed 6 MHz. Chinese patent number CN112759379A discloses an annealing process for reducing the loss of high-frequency MnZn ferrite sintered magnet cores. This process treats the magnetic core at a temperature of Tc ±150 °C in a nitrogen atmosphere. Although the loss is improved, this does not explain the changes in other magnetic properties. It differs significantly from the annealing process of the present invention.The present invention can not only improve loss but also increase magnetic permeability, so that the magnetic permeability of the magnetic core does not deteriorate at ultra-high frequency. Content of the invention

[0004] To solve the aforementioned problems, the present invention provides a method for producing a soft magnetic manganese-zinc ferrite with ultra-high frequency and high magnetic permeability. The present invention utilizes suitable main components and dopants, employing a main formula with a low Zn content to increase the material's cutoff frequency, resulting in lower losses in the 6 to 8 MHz frequency range. The main formula is doped with the low-melting-point substance MoO3 to enhance dissolution, lower the sintering temperature, accelerate the reaction rate, and reduce grain size and high-frequency losses. Due to the low Zn content formula and the co-solvent doping, the magnetic permeability of the material is reduced.To further reduce loss and improve magnetic permeability, it is annealed at 600 to 900 °C. Annealing not only eliminates stress in the magnetic core and improves magnetic permeability, but also makes the liquid phase distribution more uniform, increases the resistivity, and reduces loss. The result is a soft magnetic manganese-zinc ferrite with ultra-high frequency and high magnetic permeability.

[0005] To achieve the above objective, the present invention uses the following specific technical solutions: Step 1, Preparation: according to the proportions, Fe2O3: 73.5 to 76.5 wt.%, ZnO: 1.4 to 3.0 wt.%, MoO3: 0.01 to 0.04 wt.% are weighed out, the remainder is Mn3O4, and then mixed by wet grinding, with a mixing time of 10 to 20 minutes; Step 2, Pre-burning: the mixture obtained from step 1 is dried and then pre-burned, with the pre-burning taking place in air, the pre-burning temperature being 800 to 1000 °C and the temperature rise rate being 3 to 5 °C / minute; Step 3, Grinding: the pre-burned material obtained from step 2 is shaken and then the auxiliary components are added according to the proportions: CaCO3: 400 to 600 ppm, ZrO2: 100 to 300 ppm, TiO2: 500 to 800 ppm, Co2O3: 1500 to 4000 ppm, CuO: 50 to 200 ppm, and ground, with the grinding time being 30 to 90 minutes; Step 4, Granulation: depending on the total weight of the powder obtained after grinding, 15 wt% polyvinyl alcohol is added, ground and sieved into particles of a specific size, and the ground slurry is dried and granulated; Step 5, Pressing and Forming: it is pressed into a ring-shaped green body with the dimensions ϕ12.5mm*ϕ7.5mm*7mm; Step 6, sintering, where the sintering temperature is 1000 to 1200 °C, the holding time is 4 to 8 hours and the equilibrium oxygen content is 1.5 to 3.0 %; Step 7, annealing, in which the fired product is annealed under vacuum conditions. During the heating process, the temperature is first increased at 3 to 5 °C / minute to 250 to 400 °C and held for 30 to 60 minutes, then the temperature is increased at 1 to 3 °C / minute to 600 to 900 °C and held for 2 to 4 hours, and then the temperature is gradually reduced, with the cooling rate starting at 1 to 3 °C / min and decreasing to 300 to 500 °C, and then the temperature is reduced to room temperature of 5 to 8 °C.

[0006] Furthermore, the main components of a manganese-zinc ferrite with ultra-high frequency, high magnetic permeability and low loss preferably contain Fe2O3: 74.0 to 75.5 wt.%, ZnO: 1.4 to 3.0 wt.%, MoO3: 0.03 to 0.04 wt.%, the remainder is Mn3O4, the auxiliary components contain CaCO3: 400 to 600 ppm, ZrO2: 100 to 300 ppm, TiO2: 500 to 800 ppm, Co2O3: 1500 to 2000 ppm, CuO: 50 to 200 ppm.

[0007] Preferably, the sintering temperature in step 6 is 1050 to 1150 °C and the grain size after sintering is 2 to 4 µm.

[0008] Compared with the prior art, the present invention has the following advantageous effects: The soft magnetic manganese-zinc ferrite produced by the inventive method exhibits lower loss and high magnetic permeability in the frequency range of 6 to 8 MHz and achieves the following technical performance, indicators and parameters: (1) Initial magnetic permeability µi≥850 (T=25°C, B<0.25mT); (2) Magnetic loss Pcv≤1150kW / m 3 (T=25°C, f=6MHz, B=30mT); PCV≤1250kW / m 3 (T=40°C, f=6MHz, B=30mT); PCV≤600kW / m 3 (T=25°C, f=8MHz, B=10mT); PCV≤730kW / m 3 (T=40°C, f=8MHz, B=10mT); (3) Intensity of magnetic saturation induction Bs≥530mT (25°C, H=1194A / m); Bs≥440mT (100°C, H=1194A / m); The soft magnetic manganese-zinc ferrite with ultra-high frequency, high magnetic permeability and low loss of the present invention can not only replace some of the NiZn ferrite, meet the requirements for the ultra-high frequency use of magnetic devices, and significantly reduce material costs, but also contribute to reducing the device volume and the number of winding turns, and can reduce conduction losses and temperature increases, which can be widely used in miniaturized devices and provides material reserves for future, more miniaturized devices. Detailed description

[0009] The manufacturing process and the ultra-high-frequency, high-magnetic, low-loss soft magnetic manganese-zinc ferrite produced according to the present invention are described in more detail below with reference to specific implementation examples. Two soft magnetic MnZn ferrite materials in embodiments 1 and 2, and four soft magnetic MnZn ferrite materials in comparative examples 1, 2, 3, and 4, were produced according to the following manufacturing processes. Embodiment 1: An ultra-high-frequency, high-magnetic, low-loss soft magnetic manganese-zinc ferrite consisting of main components and auxiliary components, wherein the manufacturing process is as follows: Step 1, Preparation: Fe2O3: 74.3 wt.%, ZnO: 1.8 wt.%, MoO3: 0.04 wt.% and the remaining Mn3O4 ingredients, which are then mixed by wet ball mills for a mixing time of 15 minutes; Step 2, Pre-burning: the mixture obtained from step 1 is dried and then pre-burned, with a pre-burning temperature of 900 °C and a temperature rise rate of 5 °C / min; Step 3, Grinding: the obtained pre-burned material is shaken and then the auxiliary components are added: CaCO3: 600 ppm, ZrO2: 200 ppm, TiO2: 800 ppm, Co2O3: 1800 ppm, CuO: 50 to 200 ppm, grinding for 70 minutes; Step 4, Granulation: depending on the total weight of the powder obtained after grinding, 15 wt% polyvinyl alcohol is added, ground and sieved into particles of a specific size; Step 5, Pressing and Forming: it is pressed into a ring-shaped green body with dimensions ϕ12.5mm*ϕ7.5mm*7mm; Step 6, Sintering: the sintering temperature is 1120°C, the holding time is 6 hours and the equilibrium oxygen content is 1.6%; Step 7, annealing: the temperature is increased to 700 °C under vacuum conditions at a specific temperature rise rate and held for 2 hours, then slowly reduced to room temperature at a specific rate.

[0010] Exemplary embodiment 2: A soft magnetic manganese-zinc ferrite material with ultra-high frequency, high magnetic permeability and low loss, consisting of main components and auxiliary components, wherein the manufacturing process is as follows: Step 1, Preparation: Fe2O3: 74.8 wt.%, ZnO: 2.4 wt.%, MoO3: 0.04 wt.% and the remaining Mn3O4 ingredients, which are then mixed by wet ball mills, with a mixing time of 15 minutes; Step 2, Pre-burning: the mixture obtained from step 1 is dried and then pre-burned, with a pre-burning temperature of 900 °C and a temperature rise rate of 5 °C / min; Step 3, Grinding: the obtained pre-burned material is shaken and then the auxiliary components are added: CaCO3: 600 ppm, ZrO2: 200 ppm, TiO2: 800 ppm, Co2O3: 1800 ppm, CuO: 80 ppm, grinding for 70 minutes; Step 4, Granulation: depending on the total weight of the powder obtained after grinding, 15 wt% polyvinyl alcohol is added, ground and sieved into particles of a specific size; Step 5, Pressing and Forming: it is pressed into a ring-shaped green body with the dimensions ϕ12.5mm*ϕ7.5mm*7mm; Step 6: Sintering, the sintering temperature is 1120°C, the holding time is 6 hours and the equilibrium oxygen content is 1.6%; Step 7, annealing: the temperature is increased to 700 °C under vacuum conditions at a specific temperature rise rate and held for 2 hours, then slowly reduced to room temperature at a specific rate.

[0011] Exemplary embodiment 3: A soft magnetic manganese-zinc ferrite material with ultra-high frequency, high magnetic permeability and low loss, consisting of main components and auxiliary components, wherein the manufacturing process is as follows: Step 1, Preparation: Fe2O3: 75.2 wt.%, ZnO: 2.8 wt.%, MoO3: 0.03 wt.% and the remaining Mn3O4 ingredients, which are then mixed by wet grinding, with a mixing time of 15 minutes; Step 2, Pre-burning: the mixture obtained from step 1 is dried and then pre-burned, with a pre-burning temperature of 900 °C and a temperature rise rate of 5 °C / min; Step 3, Grinding: the obtained pre-burned material is shaken and then the auxiliary components are added: CaCO3: 600 ppm, ZrO2: 200 ppm, TiO2: 800 ppm, Co2O3: 1800 ppm, CuO: 80 ppm, grinding for 70 minutes. Step 4, Granulation: depending on the total weight of the powder obtained after grinding, 15 wt% polyvinyl alcohol is added, ground and sieved into particles of a specific size; Step 5, Pressing and Forming: it is pressed into a ring-shaped green body with the dimensions ϕ12.5mm*ϕ7.5mm*7mm; Step 6, Sintering: the sintering temperature is 1120°C, the holding time is 6 hours and the equilibrium oxygen content is 1.6%; Step 7, annealing: the temperature is increased to 800°C under vacuum conditions at a specific temperature rise rate and held for 2 hours, then slowly reduced to room temperature at a specific rate.

[0012] Comparative example 1: A soft magnetic manganese-zinc ferrite material consisting of main components and auxiliary components, wherein the manufacturing process is as follows: Step 1, Preparation: Fe2O3: 74.3 wt.%, ZnO: 2.2 wt.%, MoO3: 0.04 wt.% and the remaining Mn3O4 ingredients, which are subsequently mixed by wet ball mills, the mixing time being 15 minutes; Step 2, Pre-burning: the mixture obtained from step 1 is dried and then pre-burned, with a pre-burning temperature of 900 °C and a temperature rise rate of 5 °C / min; Step 3, Grinding: the obtained pre-burned material is shaken and then the auxiliary components are added: CaCO3: 600 ppm, ZrO2: 200 ppm, TiO2: 800 ppm, Co2O3: 1800 ppm, CuO: 50 to 200 ppm, grinding for 70 minutes; Step 4, Granulation: depending on the total weight of the powder obtained after grinding, 15 wt% polyvinyl alcohol is added, ground and sieved into particles of a specific size; Step 5, Pressing and Forming: it is pressed into a ring-shaped green body with the dimensions ϕ12.5mm*ϕ7.5mm*7mm; Step 6, Sintering: the sintering temperature is 1120°C, the holding time is 6 hours and the equilibrium oxygen content is 1.6%.

[0013] Comparative example 2: a soft magnetic manganese-zinc ferrite material consisting of main components and auxiliary components, the manufacturing process being as follows: Step 1, Preparation: Fe2O3: 74.6 wt.%, ZnO: 3.4 wt.%, MoO3: 0.04 wt.% and the remaining Mn3O4 ingredients, which are then mixed by wet ball mills for a mixing time of 15 minutes; Step 2, Pre-burning: the mixture obtained from step 1 is dried and then pre-burned, with a pre-burning temperature of 900 °C and a temperature rise rate of 5 °C / min; Step 3, Grinding: the obtained pre-burned material is shaken and then the auxiliary components are added: CaCO3: 600 ppm, ZrO2: 200 ppm, TiO2: 800 ppm, Co2O3: 1800 ppm, CuO: 50 to 200 ppm, grinding for 70 minutes; Step 4, Granulation: depending on the total weight of the powder obtained after grinding, 15 wt% polyvinyl alcohol is added, ground and sieved into particles of a specific size; Step 5, Pressing and Forming: it is pressed into a ring-shaped green body with the dimensions ϕ12.5mm*ϕ7.5mm*7mm; Step 6, Sintering: the sintering temperature is 1120°C, the holding time is 6 hours and the equilibrium oxygen content is 1.6%; Step 7, annealing: the temperature is increased to 700 °C under vacuum conditions at a specific temperature rise rate and held for 2 hours, then slowly reduced to room temperature at a specific rate.

[0014] Comparative example 3: A soft magnetic manganese-zinc ferrite material consisting of main components and auxiliary components, wherein the manufacturing process is as follows: Step 1, Preparation: Fe2O3: 74.3 wt.%, ZnO: 1.8 wt.%, and the remaining Mn3O4 ingredients, which are subsequently mixed by wet ball mills, the mixing time being 15 minutes; Step 2, Pre-burning: the mixture obtained from step 1 is dried and then pre-burned, with a pre-burning temperature of 900 °C and a temperature rise rate of 5 °C / min; Step 3, Grinding: the obtained pre-burned material is shaken and then the auxiliary components are added: CaCO3: 600 ppm, ZrO2: 200 ppm, TiO2: 800 ppm, Co2O3: 1800 ppm, CuO: 50 to 200 ppm, grinding for 70 minutes; Step 4, Granulation: depending on the total weight of the powder obtained after grinding, 15 wt% polyvinyl alcohol is added, ground and sieved into particles of a specific size; Step 5, Pressing and Forming: it is pressed into a ring-shaped green body with the dimensions ϕ12.5mm*ϕ7.5mm*7mm; Step 6, Sintering: the sintering temperature is 1120°C, the holding time is 6 hours and the equilibrium oxygen content is 1.6%; Step 7, annealing: the temperature is increased to 700 °C under vacuum conditions at a specific temperature rise rate and held for 2 hours, then slowly reduced to room temperature at a specific rate.

[0015] Comparative example 4: A soft magnetic manganese-zinc ferrite material consisting of main components and auxiliary components, wherein the manufacturing process is as follows: Step 1, Preparation: Fe2O3: 74.6 wt.%, ZnO: 3.4 wt.%, MoO3: 0.04 wt.% and the remaining Mn3O4 ingredients, which are subsequently mixed by wet grinding, the mixing time being 15 minutes; Step 2, Pre-burning: the mixture obtained from step 1 is dried and then pre-burned, with a pre-burning temperature of 900 °C and a temperature rise rate of 5 °C / min; Step 3, Grinding: the obtained pre-burned material is shaken and then the auxiliary components are added: CaCO3: 600 ppm, ZrO2: 200 ppm, TiO2: 800 ppm, Co2O3: 1800 ppm, CuO: 50 to 200 ppm, grinding for 70 minutes; Step 4, Granulation: depending on the total weight of the powder obtained after grinding, 15 wt% polyvinyl alcohol is added, ground and sieved into particles of a specific size; Step 5, Pressing and Forming: it is pressed into a ring-shaped green body with dimensions ϕ12.5mm*ϕ7.5mm*7mm, with a density of 3.2 g / cm³ 3 Step 6: Sintering: the sintering temperature is 1120°C, the holding time is 6 hours and the equilibrium oxygen content is 1.6%.

[0016] The magnetic properties tested in the embodiments and comparison examples are listed in the following table: Exam dates µ(25 °C B<5mT) Bs (mT , H=1194A / m) Pcv (kW / m 3 ) 25 °C 100 °C 6 MHz 30 mT 25°C 6 MHz 30 mT 40°C 8 MHz 10 mT 25°C 8 MHz 10mT40°C Example 1 830 536 445 1180 1220 610 715 Example 2 860 530 441 1120 1275 580 730 Example 3 905 534 443 1135 1310 605 740 Comparative example 1 670 532 443 1320 1390 760 880 Comparative example 2 1020 524 434 1610 1750 1045 1110 Comparative example 3 720 526 435 1465 1550 950 1060 Comparative example 4 1200 522 430 1850 1920 1130 1370

[0017] The table shows that embodiments 1, 2, and 3 achieve the best magnetic properties according to the manufacturing process of the present invention. Comparing embodiment 1 with the other embodiments, or comparing embodiment 2 with embodiment 4, reveals that the magnetic permeability is significantly increased and the loss is reduced after annealing. Comparing embodiment 2 with the other embodiments shows that a lower Zn content in the main formula significantly reduces the high-frequency loss. Comparing embodiment 3 with the other embodiments shows that adding MoO3 to the main formula increases the magnetic permeability and decreases the high-frequency loss.

Claims

[1] Method for producing a soft magnetic manganese-zinc ferrite with ultra-high frequency, high magnetic permeability and low loss, characterized by , that the soft magnetic manganese-zinc ferrite material with ultra-high frequency, high magnetic permeability and low loss comprises main components and auxiliary components, wherein the main components are Fe2O3: 73.5 to 76.5 wt.%, ZnO: 1.4 to 3.0 wt.%, MoO3: 0.01 to 0.04 wt.%, the remainder is Mn3O4, wherein, based on the total weight of the main components, the auxiliary components are CaCO3: 400 to 600 ppm, ZrO2: 100 to 300 ppm, TiO2: 500 to 800 ppm, Co2O3: 1500 to 4000 ppm, CuO: 50 to 200 ppm, wherein the process for producing soft magnetic manganese-zinc ferrite with ultra-high frequency, high magnetic permeability and low loss comprises the following steps: Step 1, Preparation: Fe2O3, ZnO, MoO3 and Mn3O4 are weighed according to their proportions and then mixed by wet grinding, with a mixing time of 10 to 20 minutes; Step 2, Pre-burning: the mixture obtained from step 1 is dried and then pre-burned, with the pre-burning taking place in air, the pre-burning temperature being 800 to 1000 °C and the temperature rise rate being 3 to 5 °C / minute; Step 3, Grinding: the pre-burned material obtained from step 2 is shaken and then the auxiliary components are added according to the proportions: CaCO3, ZrO2, TiO2, Co2O3, CuO and ground, with the grinding time being 30 to 90 minutes; Step 4, Granulation: the ground slurry is dried and granulated; Step 5, Pressing and Forming: it is pressed into a ring-shaped green body with the dimensions ϕ12.5mm*ϕ7.5mm*7mm; Step 6, sintering, where the sintering temperature is 1000 to 1200 °C, the holding time is 4 to 8 hours and the equilibrium oxygen content is 1.5 to 3.0 %; Step 7, annealing, in which the fired product is annealed under vacuum conditions, the temperature is increased to 600 to 900 °C under vacuum conditions, and the product is kept warm for 2 to 4 hours. [2] Method for producing a soft magnetic manganese-zinc ferrite with ultra-high frequency, high magnetic permeability and low loss according to claim 1, characterized by , that the main components are Fe2O3: 74.0 to 75.5 wt.%, ZnO: 1.4 to 3.0 wt.%, MoO3: 0.03 to 0.04 wt.%, the remainder is Mn3O4, the auxiliary components are CaCO3: 400 to 600 ppm, ZrO2: 100 to 300 ppm, TiO2: 500 to 800 ppm, Co2O3: 1500 to 2000 ppm, CuO: 50 to 200 ppm. [3] Method for producing a soft magnetic manganese-zinc ferrite with ultra-high frequency, high magnetic permeability and low loss according to claim 1 or 2, characterized by , that the sintering temperature in step 6 is 1050 to 1150 °C and the grain size after sintering is 2 to 4 µm. [4] Method for producing a soft magnetic manganese-zinc ferrite with ultra-high frequency, high magnetic permeability and low loss according to claim 1 or 2, characterized by , that in step 7 during the annealing process the temperature is first increased at 3 to 5 °C / minute to 250 to 400 °C and held for 30 to 60 minutes, then the temperature is increased at 1 to 3 °C / minute to 600 to 900 °C and held for 2 to 4 hours, then the temperature is reduced at 1 to 3 °C / minute to 300 to 500 °C and finally reduced to room temperature at 5 to 8 °C / minute.