Ultra-wide temperature and wide magnetic permeability low-loss Mn-Zn ferrite and its preparation method and application

Abstract

The present invention discloses an ultra-wide temperature range and wide magnetic permeability low-loss manganese zinc ferrite and its preparation method and application, belonging to the technical field of magnetic materials. By adopting a formula with more Fe2O3 and less ZnO, the magnetocrystalline anisotropy constant K1 and the saturation magnetostriction coefficient λ are reduced s , the saturation magnetization intensity Ms is increased, the internal and external stresses of the material are reduced, and a precise and uniform microstructure is formed, so that a magnetic material with high initial magnetic permeability, high saturation magnetic flux density and ultra-low power consumption can be obtained; by introducing CaCO3, TiO2, Nb2O5, Co3O4 and SnO2 as auxiliary components, the auxiliary components can enter the interior and grain boundaries of the grains, promote the solid-phase reaction, reduce the sintering temperature, control the grain growth, and contribute to improving the ultra-wide temperature range magnetic permeability of the manganese zinc ferrite. The obtained ultra-wide temperature range and wide magnetic permeability low-loss manganese zinc ferrite has ultra-low power consumption at wide temperatures, and the application temperature range is from -40°C to 160°C.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetic materials, and particularly relates to an ultra-wide temperature range and wide magnetic permeability low-loss MnZn ferrite, a preparation method thereof, and an application thereof. Background Art

[0002] Due to factors such as region and power, automotive electronics and photovoltaic inverters have relatively strict temperature requirements for passive devices. In particular, for transformers and inductors, which are the main devices, high temperature characteristics are required, and the material is required to have the characteristics of an ultra-wide temperature range, specifically, the material is required to have excellent and stable characteristics from -40°C to 160°C.

[0003] In recent years, technicians in the industry have done a lot of research work to obtain wide-temperature and ultra-low-power magnetic materials. For example, patent CN202111420511.5 discloses a wide-temperature low-loss high-strength MnZn power ferrite, a preparation method thereof, and an application thereof. Under the conditions of 100 kHz and 200 mT, the power consumption at 25°C ≤ 350 mW / cm 3 , and the power consumption at 120°C ≤ 350 mW / cm 3 ; under the conditions of 1194 A / m and 50 Hz, the saturation magnetic flux density at 25°C ≥ 535 mT. This material has excellent loss and saturation magnetic flux density characteristics from 25°C to 120°C. Another example is patent CN202310829822.X, which discloses a wide-temperature low-loss soft magnetic MnZn ferrite material applicable to 25 - 140°C, a preparation method thereof, and an application thereof. This material has excellent loss and saturation magnetic flux density characteristics from 25°C to 140°C and can also better meet the requirements of in-vehicle OBC and DC-DC. However, the temperature range that the above two materials can meet is only limited to the range of normal temperature from 25°C to 140°C, and for the wide-temperature low-loss soft magnetic MnZn ferrite material disclosed in patent CN202310829822.X, after the temperature exceeds 140°C, the loss increases rapidly and deteriorates.

[0004] Therefore, there is an urgent need for a magnetic material that has excellent loss and saturation magnetic flux density characteristics from -40°C to 160°C to solve the above problems. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides an ultra-wide temperature range and wide magnetic permeability low-loss MnZn ferrite, a preparation method thereof, and an application thereof. The ultra-wide temperature range and wide magnetic permeability low-loss MnZn ferrite provided by the present invention have ultra-wide temperature and ultra-low power consumption, and the application temperature range is from -40°C to 160°C. At the same time, it also has a very high saturation magnetic flux density and magnetic permeability.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a manganese-zinc ferrite with ultra-wide temperature range, wide magnetic permeability and low loss, which comprises a main component and auxiliary materials;

[0008] In terms of mole percentage, the main component comprises Fe 2 O 3 53.48 - 53.78 mol%, ZnO 10.25 - 10.50 mol% and the balance of MnO;

[0009] The auxiliary materials comprise CaCO 3 , TiO 2 , Nb 2 O 5 , Co 3 O 4 and SnO 2 .

[0010] Preferably, in terms of the total weight of the main component, the auxiliary materials comprise CaCO 3 0.02 - 0.04%, TiO 2 0.1 - 0.4%, Nb 2 O 5 0.02 - 0.03%, Co 3 O 4 0.3 - 0.5% and SnO 2 0.1 - 0.3%.

[0011] The present invention provides a preparation method of the manganese-zinc ferrite with ultra-wide temperature range, wide magnetic permeability and low loss as described in the above technical solution, comprising the following steps:

[0012] (1) Weigh Fe 2 O 3 , ZnO and MnO according to mole percentage, then carry out ball milling and mixing and pre-sintering to obtain a pre-sintered material;

[0013] (2) Weigh each auxiliary material according to the total weight of the main component, then carry out ball milling and mixing, pressing and sintering on the auxiliary materials and the pre-sintered material obtained in step (1) to obtain the manganese-zinc ferrite with ultra-wide temperature range, wide magnetic permeability and low loss.

[0014] Preferably, in step (1), the material-water ratio of the ball milling and mixing is 1:(1.1 - 1.2), the material-ball ratio is 1:(3 - 4), the grinding balls are steel balls with ф = 3 mm, and the time is 60 - 80 min.

[0015] Preferably, in step (1), the pre-sintering temperature is 930 - 960 °C, the feeding rate is 2 - 4 kg / h; the spinel synthesis degree of the pre-sintered material is 30 - 40%.

[0016] Preferably, in step (2), the material-water ratio for ball milling and mixing is 1:(1 - 1.2), the material-ball ratio is 1:(5 - 6), the grinding balls are steel balls with ф = 3 mm, and the time is 70 - 90 min.

[0017] Preferably, in step (2), zinc stearate is added during the pressing and forming process; the addition amount of zinc stearate is 2 - 3‰.

[0018] Preferably, in step (2), the sintering includes a heating stage, a heat preservation stage, and a cooling stage.

[0019] Preferably, the heating stage is as follows: under an air atmosphere, heating from room temperature to 1260 - 1300 °C, and the heating time is 6 - 8 h; the heat preservation stage is as follows: heat preservation for 5 - 6 h under the conditions of 1260 - 1300 °C and an oxygen content of 2 - 3%; the cooling stage is as follows: under a slightly reducing atmosphere, cooling from 1260 - 1300 °C to room temperature at a rate of 3 - 4 °C / min.

[0020] The present invention also provides an application of the ultra-wide temperature range and wide magnetic permeability and low-loss manganese-zinc ferrite described in the above technical solution in a transformer or an inductor.

[0021] Compared with the prior art, the present invention has the following advantages and technical effects:

[0022] The present invention adopts a formula with more Fe 2 O 3 , less ZnO, reduces the magnetocrystalline anisotropy constant K 1 and the saturation magnetostriction coefficient λ s , increases the saturation magnetization intensity Ms, reduces the internal and external stresses of the material, forms a precise and uniform microstructure, and can obtain a magnetic material with high initial magnetic permeability, high saturation magnetic flux density, and ultra-low power consumption; by introducing CaCO 3 , TiO 2 , Nb 2 O 5 , Co 3 O 4 and SnO 2 as auxiliary components, the auxiliary components can enter the interior and grain boundaries of the grains, promote the solid-phase reaction, reduce the sintering temperature, control the grain growth, and contribute to improving the wide temperature range and wide magnetic permeability of the manganese-zinc ferrite.

[0023] The ultra-wide temperature range and wide magnetic permeability and low-loss manganese-zinc ferrite provided by the present invention, under the conditions of 100 kHz and 200 mT, the power consumption at -40 °C ≤ 400 mW / cm 3 , and the power consumption at 160 °C ≤ 400 mW / cm 3; Under the conditions of 1194 A / m and 50 Hz, the saturation magnetic flux density at 25 °C is ≥550 mT, the saturation magnetic flux density at 140 °C is ≥410 mT, the initial permeability is 3000. Compared with existing magnetic materials, it has lower power consumption over a wider temperature range, a wider application temperature range from -40 °C to 160 °C, a higher saturation magnetic flux density and permeability, and is very suitable for applications in automotive electronics and photovoltaics. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings forming a part of this application are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation of this application. In the drawings:

[0025] Figure 1 It is a graph showing the variation of power consumption with temperature for the manganese-zinc ferrite in Example 2 and Comparative Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0027] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0028] An embodiment of the present invention provides a manganese-zinc ferrite with ultra-wide temperature range, wide permeability, and low loss, including a main component and auxiliary materials;

[0029] In terms of mole percentage, the main component includes Fe 2 O 3 53.48 - 53.78 mol%, ZnO 10.25 - 10.50 mol%, and the balance of MnO;

[0030] The auxiliary materials include CaCO 3 , TiO 2 , Nb 2 O 5 , Co 3 O 4 and SnO 2 .

[0031] In a preferred embodiment, in terms of mole percentage, the main component includes Fe 2 O 353.48 - 53.58 mol%, ZnO 10.25 - 10.30 mol% and the balance of MnO. By adopting a formulation with more Fe 2 O 3 and less ZnO, the magnetocrystalline anisotropy constant K 1 and the saturation magnetostriction coefficient λ s are reduced, the saturation magnetization Ms is increased, the internal and external stresses of the material are reduced, and a precise and uniform microstructure is formed, thus obtaining a magnetic material with high initial permeability, high saturation magnetic flux density and ultra - low power consumption.

[0032] In a preferred embodiment, based on the total weight of the main components, the auxiliary materials include CaCO 3 0.02 - 0.04%, TiO 2 0.1 - 0.4%, Nb 2 O 5 0.02 - 0.03%, Co 3 O 4 0.3 - 0.5% and SnO 2 0.1 - 0.3%. By introducing CaCO 3 , TiO 2 , Nb 2 O 5 , Co 3 O 4 and SnO 2 as auxiliary components, the auxiliary components can enter the interior and grain boundaries of the grains, promote the solid - phase reaction, reduce the sintering temperature, control the grain growth, and contribute to improving the wide - temperature and wide - permeability of the manganese - zinc ferrite; the introduction of the auxiliary components can control the internal grain size to be above 12 μm and the external grain size to be below 12 μm. The TiO 2 and Co 3 O 4 combination in the present invention makes the magnetocrystalline anisotropy constant K 1 zero, which helps to reduce the high - temperature power consumption of the manganese - zinc ferrite. The addition of SnO 2 plays a role in converting Fe 3+ to Fe 2+ , which helps to reduce the low - temperature power consumption of the manganese - zinc ferrite.

[0033] The present invention provides a method for preparing the ultra - wide - temperature and wide - permeability and low - loss manganese - zinc ferrite described in the above technical solution, comprising the following steps:

[0034] (1) Weigh Fe 2 O 3 , ZnO and MnO according to the molar percentage, and then carry out ball - milling mixing and pre - sintering to obtain a pre - sintered material;

[0035] (2) Weigh each auxiliary material according to the total weight of the main components, and then ball-mill and mix the auxiliary materials and the pre-sintered material obtained in step (1), press them into shape, and sinter them to obtain the ultra-wide temperature and wide magnetic permeability low-loss manganese-zinc ferrite.

[0036] In a preferred embodiment, in step (1), the material-water ratio of the ball-milling and mixing is 1:(1.1 - 1.2), the material-ball ratio is 1:(3 - 4), the grinding balls are steel balls with ф = 3 mm, and the time is 60 - 80 min; the average particle size of the slurry obtained by the ball-milling and mixing is 1.10 - 1.20 μm.

[0037] In a preferred embodiment, in step (1), the pre-sintering temperature is 930 - 960 °C, and the feeding rate is 2 - 4 kg / h. In the present invention, controlling the pre-sintering temperature and feeding rate within the above ranges is beneficial to ensuring and stabilizing the spinel synthesis degree. Changing the pre-sintering temperature will change the magnetization degree of the powder, thereby changing the density of the manganese-zinc ferrite, and ultimately changing the power consumption.

[0038] In a preferred embodiment, in step (1), the pre-sintering is carried out under air conditions; the pre-sintering equipment is a natural gas 500-type rotary kiln; the rotation speed of the natural gas 500-type rotary kiln is 2 N / min.

[0039] In a preferred embodiment, in step (1), the spinel synthesis degree of the pre-sintered material is 30 - 40%.

[0040] In a preferred embodiment, in step (2), the material-water ratio of the ball-milling and mixing is 1:(1 - 1.2), the material-ball ratio is 1:(5 - 6), the grinding balls are steel balls with ф = 3 mm, and the time is 70 - 90 min; the average particle size of the slurry obtained by the ball-milling and mixing is 1.00 - 1.10 μm.

[0041] In a preferred embodiment, in step (2), after the ball-milling and mixing, it further includes mixing the slurry obtained by the ball-milling and mixing with a PVA solution; the concentration of the PVA solution is 8%, and the dosage is 10% of the mass of the slurry; the mixing method is stirring, the stirring time is 120 min, and the rotation speed is 175 rpm.

[0042] In a preferred embodiment, in step (2), zinc stearate is added during the pressing process; the addition amount of zinc stearate is 2 - 3‰; the density of the standard green compact obtained by the pressing is controlled at 3 g / cm 3 .

[0043] In a preferred embodiment, in step (2), the sintering includes a heating stage, a holding stage, and a cooling stage.

[0044] In a preferred embodiment, the heating stage is as follows: in an air atmosphere, heating from room temperature to 1260 - 1300 °C, with a heating time of 6 - 8 h; the heat preservation stage is as follows: heat preservation for 5 - 6 h under the conditions of 1260 - 1300 °C and an oxygen content of 2 - 3%; the cooling stage is as follows: in a slightly reducing atmosphere, cooling from 1260 - 1300 °C to room temperature at a rate of 3 - 4 °C / min. In the cooling stage of the present invention, the operation is carried out in a slightly reducing atmosphere, so that the wide - temperature and low - loss performance of the material is greatly improved.

[0045] In a preferred embodiment, the slightly reducing atmosphere follows the Morinaga formula logO 2 % = a - b / T (where a and b are empirical constants. In manganese - zinc ferrite, a is usually about 7, b is usually about 14540, and T is the sintering temperature / K). In the present invention, a is preferably 6.2 - 6.5. In the cooling stage, when the set value of the oxygen content is lower than the calculated value of the formula, it is a reducing atmosphere, and the manganese - zinc ferrite undergoes a reduction reaction, and Fe 3+ is converted to Fe 2+ ; when the set value of the oxygen content is higher than the calculated value of the formula, it is an oxidizing atmosphere, and an oxidation reaction occurs; when the set value of the oxygen content is the same as the calculated value of the formula, it is a balanced atmosphere, and no chemical reaction occurs.

[0046] The present invention also provides an application of the ultra - wide - temperature and wide - magnetic - permeability and low - loss manganese - zinc ferrite described in the above technical solution in a transformer or an inductor.

[0047] In the embodiments of the present invention, room temperature refers to "25 ± 2 °C".

[0048] Unless otherwise specified, the raw materials in the embodiments of the present invention are all obtained through commercial channels.

[0049] Examples 1 - 2 and Comparative Example 1

[0050] A preparation method of an ultra - wide - temperature and wide - magnetic - permeability and low - loss manganese - zinc ferrite:

[0051] (1) Weigh Fe 2 O 3 , ZnO and MnO according to the molar percentage, and then carry out ball - milling and mixing. The ratio of material to water for ball - milling is 1:1.1, the ratio of material to balls is 1:3, the grinding balls are steel balls with a diameter of ф = 3 mm, and the ball - milling time is 60 min to obtain a slurry with an average particle size of 1.1 μm.

[0052] (2) Use a natural gas 500 - type rotary kiln to pre - sinter the slurry obtained in step (1) under air conditions to obtain a pre - sintered material with a spinel synthesis degree of 32%; among them, the rotation speed of the natural gas 500 - type rotary kiln is 2 N / min, the pre - sintering temperature is 945 °C, and the feeding amount is 4 kg / h.

[0053] (3) Weigh each auxiliary material according to the total weight of the main components, and then ball-mill and mix the auxiliary materials and the pre-sintered material obtained in step (1). The ratio of material to water for ball-milling is 1:1, the ratio of material to balls is 1:5, the grinding balls are steel balls with ф = 3 mm, the ball-milling time is 70 min, and a slurry with an average particle size of 1.10 μm is obtained. Then, add a PVA solution (concentration 8%) accounting for 10% of the slurry mass and stir at a speed of 175 rpm for 120 min. Subsequently, add zinc stearate according to an addition amount of 2‰, and then carry out pressing and forming to obtain a green body with a density of 3 g / cm 3 of the green body.

[0054] (4) Sinter the green body obtained in step (3). Heating stage: Under an air atmosphere, heat from room temperature to 1260 °C at a uniform speed over 6 h. Insulation stage: Insulate at 1260 °C under the condition of an oxygen content of 2% for 5 h. Cooling stage: Under a slightly reducing atmosphere, cool from 1260 °C to room temperature at a rate of 3 °C / min to obtain a manganese-zinc ferrite with an ultra-wide temperature range, low magnetic permeability, and low loss; among them, the slightly reducing atmosphere follows the Morin-Rieu formula logO 2 % = a - b / T, where a is 6.2 - 6.5.

[0055] The component compositions and properties of Examples 1-2 and Comparative Example 1 are shown in Table 1.

[0056] Table 1 Component Compositions and Properties of Examples 1-2 and Comparative Example 1

[0057]

[0058] As can be seen from Table 1, the manganese-zinc ferrites with ultra-wide temperature range, low magnetic permeability, and low loss in Examples 1 and 2 have lower power consumption over a wider temperature range. In the range of -40 °C to 160 °C, the power consumption is low and the change is small. Comparative Example 1 omits Co 3 O 4 , and the power consumption at -40 °C and 160 °C increases significantly.

[0059] Figure 1 is a graph showing the variation of power consumption with temperature for the manganese-zinc ferrites in Example 2 and Comparative Example 1. As Figure 1 can be seen, the manganese-zinc ferrite in Example 2 has low power consumption and small change in the range of -40 °C to 160 °C, while for the manganese-zinc ferrite in Comparative Example 1 in the range of -40 °C to 160 °C, when the temperature is lower than 20 °C and higher than 120 °C, the loss increases rapidly and deteriorates.

[0060] Comparative Example 2

[0061] The difference from Example 1 is that TiO 2 is omitted, and the remaining steps are the same as in Example 1.

[0062] Comparative Example 3

[0063] It is different from Example 1 in that SnO is omitted 2 , and the remaining steps are the same as those in Example 1.

[0064] Comparative Example 4

[0065] It is different from Example 1 in that in step (4), in the cooling stage: in a mixed atmosphere of oxygen and nitrogen, the partial pressure of oxygen in the mixed atmosphere is 0.5%, and it is cooled from 1260 °C to room temperature at a rate of 3 °C / min, and the remaining steps are the same as those in Example 1.

[0066] Comparative Example 5

[0067] It is different from Example 1 in that TiO 2 is replaced by SiO 2 , and the remaining steps are the same as those in Example 1.

[0068] Comparative Example 6

[0069] It is different from Example 1 in that SnO 2 is replaced by Ta 2 O 5 , and the remaining steps are the same as those in Example 1.

[0070] Comparative Example 7

[0071] It is different from Example 1 in that Co 3 O 4 is replaced by Co 2 O 3 , and the remaining steps are the same as those in Example 1.

[0072] The properties of the manganese-zinc ferrite prepared in Comparative Examples 2-7 are shown in Table 2.

[0073] Table 2 Properties of the manganese-zinc ferrite prepared in Comparative Examples 2-7

[0074]

[0075] As can be seen from Table 2, omitting TiO 2 or SnO 2 will increase the high-temperature power consumption of the manganese-zinc ferrite, and changing the atmosphere in the cooling stage will cause a significant increase in both the low-temperature and high-temperature power consumptions of the manganese-zinc ferrite. Replacing TiO 2 with SiO 2 or replacing SnO 2 with Ta 2 O 5 will increase both the high-temperature and low-temperature power consumptions of the manganese-zinc ferrite. Replacing Co 3 O 4 with Co 2 O3 , the high-temperature and low-temperature power consumptions of the manganese-zinc ferrite will both increase because Co 2+ has a non-zero ground-state orbital momentum moment, so there is a strong spin-orbit coupling effect, resulting in a very large positive magnetocrystalline anisotropy constant in the spinel ferrite. The magnetocrystalline anisotropy constant K 2+ contributed by Co 1 decreases sharply with the increase of temperature. Therefore, there may be a cancellation point where K = 0 within the range below the Curie point, generating the second peak of the μ-T curve. Adding Co 2+ to the iron-rich MnZn ferrite can significantly change the μ-T curve. Co 3 O 4 contains cobalt elements in the +2 valence state, while the valence state of cobalt elements in Co 2 O 3 is +3 valence and does not have this effect.

[0076] The above is only the preferred specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in this application should be covered by the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

1. An ultra-wide temperature range and low-loss manganese-zinc ferrite with magnetic permeability, characterized in that: Including main ingredients and auxiliary materials; In terms of molar percentage, the main components are Fe2O3 53.48-53.78 mol%, ZnO 10.25-10.50 mol% and the balance MnO; Based on the total weight of the main components, the auxiliary materials are CaCO3 0.02-0.04%, TiO2 0.1-0.4%, Nb2O5 0.02-0.03%, Co3O4 0.3-0.5% and SnO2 0.1-0.3%; The method for preparing the ultra-wide temperature range and low-loss manganese-zinc ferrite comprises the following steps: (1) Fe2O3, ZnO and MnO are weighed according to mole percentage, and then ball-milled and pre-calcined to obtain a pre-calcined material; (2) Weighing each auxiliary material according to the total weight of the main components, then ball-milling the auxiliary material and the pre-sintered material obtained in step (1), pressing and sintering to obtain the ultra-wide temperature range and low-loss manganese-zinc ferrite; the sintering includes a heating stage, a heat preservation stage and a cooling stage; the heating stage is: heating from room temperature to 1260-1300°C in an air atmosphere, and the heating time is 6-8h; the heat preservation stage is: keeping warm at 1260-1300°C and an oxygen content of 2-3% for 5-6h; the cooling stage is: cooling from 1260-1300°C to room temperature at a rate of 3-4°C / min in a partially reducing atmosphere.

2. The method for preparing the ultra-wide temperature and permeability low-loss manganese-zinc ferrite according to claim 1, characterized in that: The following steps are involved: (1) Fe2O3, ZnO and MnO are weighed according to mole percentage, and then ball-milled and pre-calcined to obtain a pre-calcined material; (2) Weighing each auxiliary material according to the total weight of the main components, then ball-milling the auxiliary material and the pre-sintered material obtained in step (1), pressing and sintering to obtain the ultra-wide temperature range and low-loss manganese-zinc ferrite; the sintering includes a heating stage, a heat preservation stage and a cooling stage; the heating stage is: heating from room temperature to 1260-1300°C in an air atmosphere, and the heating time is 6-8h; the heat preservation stage is: keeping warm at 1260-1300°C and an oxygen content of 2-3% for 5-6h; the cooling stage is: cooling from 1260-1300°C to room temperature at a rate of 3-4°C / min in a partially reducing atmosphere.

3. The preparation method according to claim 2, characterized in that: In step (1), the material-water ratio of the ball milling mixture is 1:(1.1-1.2), the material-ball ratio is 1:(3-4), the grinding balls are steel balls with a diameter of ф=3 mm, and the grinding time is 60-80 min.

4. The preparation method according to claim 2, characterized in that: In step (1), the pre-calcination temperature is 930-960°C, and the feed rate is 2-4 kg / h.

5. The preparation method according to claim 2, characterized in that: In step (2), the material-water ratio of the ball milling mixture is 1:(1-1.2), the material-ball ratio is 1:(5-6), the grinding balls are steel balls with a diameter of ф=3 mm, and the time is 70-90 min.

6. The preparation method according to claim 2, characterized in that: In step (2), zinc stearate is added during the compression molding process; the amount of zinc stearate added is 2-3‰.

7. Application of the ultra-wide temperature range, low-loss manganese-zinc ferrite with magnetic permeability as described in claim 1 in transformers or inductors.

Images