Ferrite magnetic core and preparation method and application thereof

Abstract

The invention provides a ferrite magnetic core and a preparation method and application thereof. The ferrite magnetic core is provided with a groove body which is recessed inwards, the edge of the groove body is provided with an R angle, and the ferrite magnetic core is provided with at least one through hole. The preparation method comprises the following steps: (1) pre-sintering a main raw material of the soft magnetic ferrite to obtain a pre-sintered material; (2) carrying out first mixing on the pre-sintered material obtained in the step (1) and an additive to obtain a mixture; and (3) carrying out second mixing on the mixture obtained in the step (2) and a binder, and sintering to obtain the ferrite magnetic core. The high-stability ferrite magnetic core prepared by the method is accurate in assembly and pairing, not easy to crack and free of cracks after being sintered.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite ferrite, and relates to a ferrite magnetic core, a preparation method thereof, and an application thereof. Background Art

[0002] OBC (On Board Charger) is a core component for realizing energy conversion inside an electric vehicle, and has the ability to charge a power battery safely, quickly, and conveniently. According to the data provided by the battery management system BMS, the charging current and voltage parameters are dynamically adjusted, corresponding actions are executed, and the charging process is completed.

[0003] Soft ferrite materials are widely used in OBC because of their high resistivity, low high-frequency loss, low cost, and the fact that there is sufficient space in electric vehicles to make the magnetic core larger to compensate for the disadvantage of low saturation magnetic stripe density. There are dimensional changes during ferrite sintering. Due to the differences in its molding density and sintering density, there are often pairing errors when two products are paired for use. Generally, the dimensions can only be controlled at the level of the median value ± 0.9 × the median value. Therefore, large-sized magnetic cores need to be graded during actual use because there is no central reference to achieve paired use.

[0004] When it comes to large-sized products of soft ferrite, the first thing that comes to mind is to increase the pre-sintering temperature to reduce the shrinkage amount and reduce the glue content to reduce the risk of degumming and cracking. However, the above measures will bring new problems, such as: high core loss, large temperature rise, resulting in low charging efficiency, low glue content, low green strength, and cracking during the sintering drainage stage. R-angle cracks mean that the R-angle (R0.1 - R2) is used to transition at the junction of the side leg and the bottom thickness of the magnetic core. Because of less powder and low pressure during molding and poor precision in controlling the mold movement by a mechanical press, cracks will appear at the R-angle position after sintering.

[0005] CN111863367A discloses a manufacturing method of a manganese-zinc ferrite magnetic core. It includes steps such as batching, wet mixing and sanding by wet method, spray granulation, pre-sintering, secondary batching, secondary wet mixing and sanding, spray granulation, and sintering in sequence to manufacture a large-sized integrally formed magnetic core. However, the stability of the prepared magnetic core needs to be further improved.

[0006] CN113421751A discloses a magnetic core assembly and a power module. The magnetic core assembly includes a magnetic core assembly and a winding assembly. The magnetic core assembly includes a first magnetic column and a second magnetic column. When assembling the magnetic core, it needs to be graded to reduce the deviation of the dispensing surface. Otherwise, there will be a deviation between the magnetic cores after assembly, leading to problems such as local temperature rise of leakage inductance.

[0007] Therefore, how to prepare a high-stability magnetic core with precise assembly pairing, not easy to crack, and no cracks after sintering is an important research direction in this field. Summary of the Invention

[0008] The object of the present invention is to provide a high-stability ferrite magnetic core with precise assembly pairing, not easily cracked, and no cracks after sintering, and its preparation method and application.

[0009] To achieve the object of the present invention, the following technical solutions are adopted:

[0010] One object of the present invention is to provide a ferrite magnetic core, on which a recessed groove is provided, an R angle is provided at the edge of the groove, and at least one through hole is provided on the ferrite magnetic core.

[0011] The present invention prepares a high-stability ferrite magnetic core with precise assembly pairing, not easily cracked, and no cracks after sintering. The present invention provides through holes on the ferrite magnetic core as positioning holes, which can avoid the influence of assembly caused by the pairing error of inconsistent shrinkage of the magnetic core. An R angle is provided at the edge of the recessed groove to avoid cracks at the R angle position during sintering.

[0012] As a preferred technical solution of the present invention, the number of the grooves ≥ 1, and the number can be 1, 2, 3, 4, 5, 6, 7, 8, 9, etc., but is not limited to the listed values. Within this numerical range, other unlisted values are equally applicable.

[0013] Preferably, the radius of the R angle is 3 - 10 mm, and the radius can be 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0014] The present invention adopts a large R angle setting. If R < 3 mm, cracks will appear at the R angle; if R > 10 mm, density voids will appear, and the particles will not be damaged and will present a spherical shape.

[0015] Preferably, the shape of the through hole includes any one of a cylinder, a square column, or a polygon.

[0016] Another object of the present invention is to provide a preparation method of the ferrite magnetic core as described in object one, and the preparation method includes the following steps:

[0017] (1) Pre-sinter the main raw material of soft ferrite to obtain a pre-sintered material;

[0018] (2) Perform a first mixing of the pre-sintered material in step (1) and an additive to obtain a mixed material;

[0019] (3) Perform a second mixing of the mixed material in step (2) and a binder, and sinter to obtain the ferrite magnetic core.

[0020] In step (1) of the present invention, a pre-sintered material is obtained after pre-sintering; in step (2), an additive is added for the first mixing to obtain a powder with a suitable particle size, increase the specific surface area of the powder, improve the activity of the powder, and uniformly mix the additive and the pre-sintered material; in step (3), a binder is added, and after stirring evenly, granulation and molding of the ferrite magnetic core are achieved, and finally, it is sintered into a ferrite magnetic core with a specific structure.

[0021] As a preferred technical solution of the present invention, the main ferrite raw material in step (1) includes Fe 2 O 3 , Mn 3 O 4 and ZnO.

[0022] Preferably, the mass ratio of Fe 2 O 3 , Mn 3 O 4 and ZnO is (72 - 75):(22 - 25):(2 - 6). Among them, the mass ratio can be 72:25:3, 73:23:4, 74:22:4, 75:23:2, 72:22:6, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0023] As a preferred technical solution of the present invention, the main ferrite raw material in step (1) is subjected to wet sanding mixing and spray granulation in sequence, and then the pre-sintering is carried out.

[0024] Preferably, the solvent for the wet sanding mixing is water.

[0025] Preferably, the temperature of the pre-sintering in step (1) is 700 - 780 °C. Among them, the temperature can be 700 °C, 710 °C, 720 °C, 730 °C, 740 °C, 750 °C, 760 °C, 770 °C, 780 °C, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0026] If the temperature of the pre-sintering in the present invention is too high, it will affect the activity of the pre-sintered material, resulting in a decrease in the shrinkage ratio and deterioration of the performance of inductance and loss; if the temperature of the pre-sintering is too low, it will cause sintering cracking.

[0027] Preferably, the time of the pre-sintering in step (1) is 2.5 - 3.5 h. Among them, the time can be 2.5 h, 2.6 h, 2.7 h, 2.8 h, 2.9 h, 3.0 h, 3.1 h, 3.2 h, 3.3 h, 3.4 h, 3.5 h, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0028] If the pre-sintering time of the present invention is too short, it will lead to uneven pre-sintering. If the pre-sintering time is too long, it will affect the activity, resulting in a decrease in the shrinkage ratio and deterioration of the inductance and loss performance.

[0029] As a preferred technical solution of the present invention, the additive in step (2) includes CaCO 3 , ZnO, Nb 2 O 5 , CoO or V 2 O 5 Any one or a combination of at least two of them, and typical but non-limiting examples of the combination are: the combination of CaCO 3 and ZnO, the combination of ZnO and Nb 2 O 5 , the combination of Nb 2 O 5 and CoO, or the combination of CoO and V 2 O 5 etc.

[0030] Preferably, the addition amount of the CaCO 3 is 400 - 1000 ppm. The addition amount can be 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm or 1000 ppm, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0031] Preferably, the addition amount of the ZnO is 150 - 400 ppm. The addition amount can be 150 ppm, 200 ppm, 250 ppm, 300 ppm, 350 ppm or 400 ppm, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0032] Preferably, the addition amount of the Nb 2 O 5 is 80 - 250 ppm. The addition amount can be 80 ppm, 90 ppm, 100 ppm, 110 ppm, 120 ppm, 130 ppm, 140 ppm, 150 ppm, 160 ppm, 170 ppm, 180 ppm, 190 ppm, 200 ppm, 210 ppm, 220 ppm, 230 ppm, 240 ppm or 250 ppm, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0033] Preferably, the addition amount of CoO is 400 - 3500 ppm. The addition amount can be 400 ppm, 600 ppm, 800 ppm, 1000 ppm, 1200 ppm, 1400 ppm, 1600 ppm, 1800 ppm, 2000 ppm, 2200 ppm, 2400 ppm, 2600 ppm, 2800 ppm, 3000 ppm, 3200 ppm, 3400 ppm or 3500 ppm, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0034] Preferably, the 2 addition amount of V 5 O is 150 - 700 ppm. The addition amount can be 150 ppm, 200 ppm, 250 ppm, 300 ppm, 350 ppm, 400 ppm, 450 ppm, 500 ppm, 550 ppm, 600 ppm, 650 ppm or 700 ppm, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0035] Preferably, the first mixing in step (2) includes grinding.

[0036] Preferably, after the first mixing in step (2), the D 50 particle size of the mixed material is 0.9 - 1.2 μm. The D 50 particle size can be 0.9 μm, 0.95 μm, 1.0 μm, 1.05 μm, 1.1 μm, 1.15 μm or 1.2 μm, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0037] As a preferred technical solution of the present invention, the binder in step (3) is a polyvinyl alcohol solution.

[0038] Preferably, the mass fraction of the polyvinyl alcohol solution in the mixed material is 10 - 13.75%. The mass fraction can be 10%, 10.25%, 10.75%, 11.25%, 11.75%, 12.25%, 12.75%, 13.25% or 13.75%, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0039] The function of polyvinyl alcohol in the present invention is to improve the plasticity of the powder material. Adding too little will result in poor strength of the green body, prone to cracking and corner chipping problems; adding too much, since polyvinyl alcohol is an organic substance, it needs to be completely decomposed and discharged from the product before 600 °C during sintering. Excessive polyvinyl alcohol will cause debinding cracking, or a very slow heating rate and a long holding time are required to improve the debinding cracking problem.

[0040] As a preferred technical solution of the present invention, the second mixing described in step (3) includes stirring.

[0041] Preferably, after the second mixing, centrifugal granulation is carried out to obtain centrifuged material. A lubricant is added to the centrifuged material, and after mixing and molding in sequence, the sintering is carried out.

[0042] Preferably, the lubricant includes zinc stearate.

[0043] Preferably, the mass fraction of the lubricant in the centrifuged material is 0.03-0.07%, where the mass fraction can be 0.03%, 0.04%, 0.05%, 0.06% or 0.07%, etc., but is not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0044] Preferably, the pressure for molding is 1.2-1.8 T / cm 2 , where the pressure can be 1.2 T / cm 2 , 1.3 T / cm 2 , 1.4 T / cm 2 , 1.5 T / cm 2 , 1.6 T / cm 2 , 1.7 T / cm 2 or 1.8 T / cm 2 etc., but is not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0045] The present invention obtains a ferrite magnetic core with a specific structure through molding.

[0046] Preferably, a blank is obtained after molding, and the molding density of the blank is 2.94-3.06 g / cm 3 , where the density can be 2.94 g / cm 3 , 2.65 g / cm 3 , 2.96 g / cm 3 , 2.97 g / cm 3 , 2.98 g / cm 3 , 2.99 g / cm 3 , 3.00 g / cm 3 , 3.01 g / cm 3 , 3.02 g / cm 3 , 3.03 g / cm 3 , 3.04 g / cm 3 , 3.05 g / cm 3 or 3.06 g / cm 3etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0047] As a preferred technical solution of the present invention, the sintering in step (3) includes first sintering, second sintering, third sintering, fourth sintering, and fifth sintering.

[0048] Preferably, the temperature of the first sintering is 175 - 185°C, where the temperature can be 175°C, 176°C, 177°C, 178°C, 179°C, 180°C, 181°C, 182°C, 183°C, 184°C, or 185°C, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0049] Preferably, the temperature of the second sintering is 215 - 225°C, where the temperature can be 215°C, 216°C, 217°C, 218°C, 219°C, 220°C, 221°C, 222°C, 223°C, 224°C, or 225°C, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0050] Preferably, the temperature of the third sintering is 275 - 285°C, where the temperature can be 275°C, 276°C, 277°C, 278°C, 279°C, 280°C, 281°C, 282°C, 283°C, 284°C, or 285°C, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0051] Preferably, the temperature of the fourth sintering is 345 - 355°C, where the temperature can be 345°C, 346°C, 347°C, 348°C, 349°C, 350°C, 351°C, 352°C, 353°C, 354°C, or 355°C, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0052] Preferably, the holding times of the first sintering, second sintering, third sintering, and fourth sintering are each independently 20 - 60 min, where the time can be 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, or 60 min, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0053] In the present invention, if the holding time is too short, the sintered magnet will crack.

[0054] Preferably, the temperature of the fifth sintering is 1200 - 1400 °C. The temperature can be 1200 °C, 1220 °C, 1240 °C, 1260 °C, 1280 °C, 1300 °C, 1320 °C, 1340 °C, 1360 °C, 1380 °C or 1400 °C, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0055] Preferably, the time of the fifth sintering is 3.5 - 6 h. The time can be 3.5 h, 4 h, 5 h or 6 h, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0056] Preferably, the heating rate of the sintering is 1.2 - 1.3 °C / min. The heating rate can be 1.2 °C / min, 1.21 °C / min, 1.22 °C / min, 1.23 °C / min, 1.24 °C / min, 1.25 °C / min, 1.26 °C / min, 1.27 °C / min, 1.28 °C / min, 1.29 °C / min or 1.3 °C / min, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0057] If the heating rate of the sintering in the present invention is too high, it will cause the magnet prepared to crack.

[0058] Preferably, after sintering, it is cooled to 150 - 170 °C. The temperature can be 150 °C, 152 °C, 154 °C, 156 °C, 158 °C, 160 °C, 162 °C, 164 °C, 166 °C or 170 °C, etc., but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0059] During the sintering process of the present invention, nitrogen is used for protection. The relationship between the balanced oxygen partial pressure and the sintering temperature is: log(Po2) = -A / T + B (Po2 is the partial pressure of oxygen under atmospheric pressure conditions; A and B are constants, the value range of A is 13000 - 15000, the value range of B is 7 - 10, and T is the absolute temperature of the product sintering).

[0060] The third object of the present invention is to provide an application of the soft ferrite magnetic core as described in the first object, and the ferrite magnetic core is applied to the field of composite ferrite technology.

[0061] Compared with the prior art, the present invention has the following beneficial effects:

[0062] (1) The magnetic core prepared by the present invention has positioning holes (through holes), which can avoid the influence of the pairing error caused by inconsistent shrinkage of the magnetic core on the assembly. The magnetic core prepared by the present invention is provided with large R corners to avoid cracks at the R - corner position during sintering;

[0063] (2) The powder-making process and sintering process of the magnetic core of the present invention are combined to achieve the effect of no cracks after sintering of the magnetic core. Description of the Drawings

[0064] Figure 1 It is a structural diagram of the ferrite magnetic core of Embodiment 1 of the present invention.

[0065] In the figure: 1 - through hole 1; 2 - through hole 2; 3 - through hole 3; 4 - R corner 1; 5 - R corner 2; 6 - R corner 3. Detailed Embodiments

[0066] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0067] The present invention provides a ferrite magnetic core, on which there is a recessed groove, the edge of the groove is provided with an R corner, and there is at least one through hole on the ferrite magnetic core.

[0068] Further, the number of the grooves ≥ 1.

[0069] Further, the radius of the R corner is 3 - 10 mm.

[0070] Further, the shape of the through hole includes any one of a cylinder, a square column, or a polygon.

[0071] Embodiment 1

[0072] This embodiment provides a ferrite magnetic core as Figure 1 shown, on which there is a recessed groove, the edge of the groove is provided with an R corner, there are 3 through holes (through hole 1, through hole 2, through hole 3) on the ferrite magnetic core, the radius of R corner 1 is 10 mm, the radius of R corner 2 is 10 mm, and the radius of R corner 3 is 10 mm. The length, width, and thickness of the ferrite magnetic core of the present invention are 94 mm, 45 mm, and 30 mm, respectively.

[0073] This embodiment also provides a preparation method of the above ferrite magnetic core, and the preparation method includes the following steps:

[0074] (1) Ingredients of Fe 2 O 3 , Mn 3 O 4 and ZnO with a mass ratio of 72.35:23.22:4.42 are 400 kg, which are placed in a sand grinding tank for wet sand grinding and mixing, spray granulation, and pre-sintering at 750 °C for 3 h to obtain a pre-sintered material;

[0075] (2) The pre-sintered material described in step (1) and CaCO 3 , ZnO, Nb 2 O 5 , CoO and V 2 O 5 are subjected to sand grinding to obtain a mixed material, and the D 50 particle size of the mixed material is 1.05 μm;

[0076] (3) The mixed material described in step (2) and a polyvinyl alcohol solution (concentration: 10%) accounting for 10% of the mass of the mixed material are stirred, and centrifugal granulation is carried out to obtain a centrifuged material, and the loose filling ratio of the centrifuged material is 1.4%;

[0077] Zinc stearate accounting for 0.05% of the mass of the centrifuged material is added to the centrifuged material, and mixing is carried out in a mixer. The water content of the mixed powder is 0.78%. The mixed powder is subjected to double-sided pressing and forming by a conventional mechanical press of 1.6 T / cm 2 to obtain a green compact with a forming density of 3.01 g / cm 3 . After sintering, the front and back surfaces of the magnetic core are ground to obtain a ferrite magnetic core;

[0078] Among them, the specific process parameters of sintering are as follows: heating from room temperature to 180 °C and holding for 1 h, heating to 220 °C and holding for 1 h, heating to 280 °C and holding for 1 h, heating to 350 °C and holding for 1 h, the heating rate is 1.2 °C / min, finally heating to 1330 °C, holding for 5 h, setting the oxygen concentration by using the equilibrium oxygen partial pressure, and the final out-of-kiln temperature is 160 °C.

[0079] Examples 2-12 and Comparative Example 1 are based on the steps of Example 1 with parameter changes. The specific changed parameters are shown in Table 1. At the same time, the cracking conditions of Examples 1-12 and Comparative Example 1 are tested, and the test results are as recorded in Table 1.

[0080] Table 1

[0081]

[0082] It can be seen from the above table that in Examples 1-6, if the sintering holding time is too short or too long, the cracking condition after sintering will be aggravated; in Examples 7-8, if the R angle is too small, the proportion of R cracks after sintering will increase significantly. If the R angle is too large, the cracking proportion of the magnetic core after sintering will increase and particles will appear at the R angle; in Example 9, the pre-sintering temperature is too low, and the cracking condition of the magnetic core after sintering is aggravated; in Example 10, the addition amount of the polyvinyl alcohol solution is too low, and the cracking condition of the magnetic core after sintering is aggravated; in Example 11, the addition amount of the polyvinyl alcohol solution is too high, and the cracking condition of the magnetic core after sintering is aggravated; in Example 12, the holding time is too short, and the cracking condition of the magnetic core after sintering is aggravated; in Comparative Example 1, no positioning holes (through holes) are set, and there are errors in the assembly pairing.

[0083] The applicant declares that the above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by any person skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A ferrite core, characterized in that, a groove recessed inward is provided on the ferrite core, an R corner is provided at the edge of the groove, and at least one through hole is provided on the ferrite core.

2. The ferrite core according to claim 1, characterized in that, the number of the grooves ≥ 1; preferably, the radius of the R corner is 3 - 10 mm; preferably, the shape of the through hole includes any one of a cylinder, a square column or a polygon.

3. A preparation method of the ferrite core according to claim 1 or 2, characterized in that, the preparation method includes the following steps: (1) Pre-sinter the main raw material of soft ferrite to obtain a pre-sintered material; (2) Perform a first mixing on the pre-sintered material described in step (1) and an additive to obtain a mixed material; (3) Perform a second mixing on the mixed material described in step (2) and a binder, and sinter to obtain the ferrite core.

4. The preparation method according to claim 3, characterized in that, The ferrite main raw materials described in step (1) include Fe 2 O 3 , Mn 3 O 4 and ZnO; Preferably, the mass ratio of the Fe 2 O 3 , Mn 3 O 4 and ZnO is (72 to 75):(22 to 25):(2 to 6).

5. The preparation method according to claim 3 or 4, characterized in that, perform wet sanding mixing and spray granulation on the main ferrite raw material described in step (1) in sequence, and then perform the pre-sintering; preferably, the solvent for the wet sanding mixing is water; preferably, the temperature of the pre-sintering in step (1) is 700 - 780 °C; preferably, the time of the pre-sintering in step (1) is 2.5 - 3.5 h.

6. The preparation method according to any one of claims 3 - 5, characterized in that, The additive described in step (2) includes CaCO 3 , ZnO, Nb 2 O 5 , CoO or V 2 O 5 Any one or a combination of at least two of them; Preferably, the addition amount of CaCO 3 is 400 to 1000 ppm; preferably, the addition amount of ZnO is 150 - 400 ppm; Preferably, the addition amount of Nb 2 O 5 is 80 to 250 ppm; preferably, the addition amount of CoO is 400 - 3500 ppm; Preferably, the addition amount of V 2 O 5 is 150 to 700 ppm; preferably, the first mixing in step (2) includes grinding; Preferably, after the first mixing in step (2), the D of the mixture 50 particle size is 0.9 to 1.2 μm.

7. The preparation method according to any one of claims 3 - 6, characterized in that, the binder in step (3) is a polyvinyl alcohol solution; preferably, the mass fraction of the polyvinyl alcohol solution in the mixed material is 10 - 13.75%.

8. The preparation method according to any one of claims 3 - 7, characterized in that, the second mixing in step (3) includes stirring; preferably, perform centrifugal granulation after the second mixing to obtain a centrifuged material, add a lubricant to the centrifuged material, perform mixing and forming in sequence, and then perform the sintering; preferably, the lubricant includes zinc stearate; preferably, the mass fraction of the lubricant in the centrifuged material is 0.03 - 0.07%; preferably, the loose filling ratio of the centrifuged material is 1.38 - 1.45%; Preferably, the pressure for forming is 1.2 to 1.8 T / cm 2 ; Preferably, a blank is obtained after forming, and the forming density of the blank is 2.94 to 3.06 g / cm 3 .

9. The preparation method according to any one of claims 3 - 8, characterized in that, the sintering in step (3) includes a first sintering, a second sintering, a third sintering, a fourth sintering and a fifth sintering; preferably, the temperature of the first sintering is 175 - 185 °C; preferably, the temperature of the second sintering is 215 - 225 °C; preferably, the temperature of the third sintering is 275 - 285 °C; preferably, the temperature of the fourth sintering is 345 - 355 °C; preferably, the heat preservation times of the first sintering, the second sintering, the third sintering and the fourth sintering are each independently 20 - 60 min; Preferably, the temperature of the fifth sintering is 1200 - 1400 °C; Preferably, the time of the fifth sintering is 3.5 - 6 h; Preferably, the heating rate of the sintering is 1.2 - 1.3 °C / min; Preferably, after sintering, it is cooled down to 150 - 170 °C.

10. An application of the soft magnetic ferrite core as claimed in claim 1 or 2, characterized in that the ferrite core is applied to the field of composite ferrite technology.

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