A manufacturing method for improving the magnetic properties of M-type permanent ferrite

Abstract

The application discloses a kind of manufacturing methods for improving the magnetic properties of M-type permanent ferrite, and belongs to the technical field of permanent magnetic material preparation.Technical field of the application is to select pre-sintered material A and pre-sintered material B, mix uniformly according to the mass ratio A:B=(9:1)~(2.5:7.5), and after adding additives, it is prepared by ball milling, pressing forming and sintering process to obtain M-type permanent ferrite.The application uses two different pre-sintered materials as the sintering raw material of the ferrite, and the composition of pre-sintered material A and pre-sintered material B is obviously different due to the difference in raw materials and preparation process.By reasonably matching the two pre-sintered materials and adding additives, combined with the optimized sintering process, not only the remanence and coercive force of the M-type permanent ferrite are improved, but also the overall stability of the material is enhanced.The mixing ratio of the two pre-sintered materials can be adjusted according to the specific product performance requirements, which is beneficial to mass production and flexible modification, and has wider practical value in the field of high-performance magnet application.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of permanent magnet material preparation, and particularly relates to a manufacturing method for improving the magnetic properties of M-type permanent magnet ferrite. BACKGROUND

[0002] Permanent magnet material, also known as hard magnetic material, refers to a magnetic material that can retain its magnetism for a long time after being magnetized under the action of an external magnetic field, and has a high residual magnetic induction strength and a high coercive force. Permanent magnet materials can be roughly divided into several categories such as metal permanent magnet materials, ferrite permanent magnet materials and rare earth permanent magnet materials.

[0003] Permanent magnet ferrite material is a compound with uniaxial anisotropy of hexagonal structure, which is manufactured by using iron red (or iron scale) and strontium carbonate (or barium carbonate) as main raw materials through a ceramic process. According to the crystal structure, it includes spinel type, garnet type, magnetoplumbite type (M type), W type and perovskite type, and different types of permanent magnet ferrite materials have different magnetic property characteristics.

[0004] M-type permanent magnet ferrite is a hard magnetic material with a hexagonal crystal structure, mainly formed by replacing A-site ions in the ferrite with barium (Ba) or strontium (Sr) to form a compound of AFe 12 O 19 (A=Ba,Sr). It has high coercive force and magnetic energy product, and is widely used in the fields of motors, loudspeakers, sensors and the like. However, compared with rare earth permanent magnets, its magnetic properties are significantly lower, which limits its application in high-end fields. Therefore, it is of great industrial value and market prospect to develop a new method for effectively improving the magnetic properties of M-type permanent magnet ferrite.

[0005] The existing method for improving the magnetic properties of M-type permanent magnet ferrite usually introduces rare earth elements and other ions to replace part of Fe or Sr ions, that is, the magnetic properties of M-type permanent magnet ferrite are improved by ion substitution technology (such as La-Co co-substitution). The method of introduction is to add materials containing rare earth elements and other ions in the preparation of the raw material formula of the pre-sintering material, which requires strict control of the proportion of each element, and from the comprehensive performance, the existing technology needs to introduce multiple rare earth elements to simultaneously improve the performance, which is complex in raw material management and is not conducive to large-scale production. SUMMARY

[0006] The purpose of the present application is to provide a manufacturing method for improving the magnetic properties of M-type permanent magnet ferrite, which can significantly improve the magnetic permeability, remanence and maximum magnetic energy product of the ferrite, simplify the production management and reduce the complexity.

[0007] The purpose of the present application can be achieved by the following technical solutions:

[0008] The application provides a manufacturing method for improving the magnetic property of M-type permanent ferrite, comprising the following steps:

[0009] Step one, selecting pre-sintering material A and pre-sintering material B, mixing uniformly according to the mass ratio A:B=(9:1)-(2.5:7.5), and obtaining mixed pre-sintering material;

[0010] Step two, adding additives to the mixed pre-sintering material, mixing and wet ball milling, and obtaining a mixture after drying;

[0011] Step three, pressing the mixture to obtain a green body, sintering the green body to obtain a sintered body, naturally cooling the sintered body to room temperature, and standing for 12-24 hours, and then grinding and cutting to obtain the M-type permanent ferrite;

[0012] The pre-sintering material A is a pre-sintering material of high-performance permanent ferrite, and the molecular formula of the high-performance permanent ferrite is Sr x Ca y La 1-x-y Fe n Co z Zn m O 19 , wherein 0.01<=x<=0.25, 0.05<=y<=0.35, 6.9<=n<=11.8, 0.01<=z<=0.25, and 0.01<=m<=0.12;

[0013] The pre-sintering material B is a pre-sintering material of high-remanence permanent ferrite, and the molecular formula of the high-remanence permanent ferrite is Ca x La 1-x Fe n Zn m O 19 , wherein 0.01<=x<=0.65, 5.8<=n<=11.9, and 0.01<=m<=0.2.

[0014] After mixing the two different pre-sintering materials, sintering is performed, on the one hand, based on the requirements of product application, the two pre-sintering materials can be mass-produced in actual production, and then the mixing ratio is adjusted according to the specific performance requirements to prepare permanent ferrite with different comprehensive performance, which is beneficial to mass production and flexible modification.

[0015] Further, the preparation of the pre-sintering material A is as follows:

[0016] S1, according to the molecular formula Sr x Ca y La 1-x-y Fe n Co z Zn m O 19The mass of SrCO3, CaCO3, La2O3, Fe2O3, Co3O4 and ZnO is calculated according to the molar ratio, and then weighed to obtain the ingredients;

[0017] S2, the ingredients are mixed to obtain a mixture, and the mixture is wet ground for 0.5-6h to obtain a ground material;

[0018] S3, the ground material is dried to a water content of less than 2%, crushed through an 80 mesh screen, pre-fired at 1220-1280℃ for 50-250min, and crushed to obtain a pre-fired material A.

[0019] Further, the pre-fired material B is prepared as follows:

[0020] (1) The mass of CaCO3, La2O3, Fe2O3 and ZnO is calculated according to the molar ratio of Ca x La 1-x Fe n Zn m O 19 The mass of CaCO3, La2O3, Fe2O3 and ZnO is calculated according to the molar ratio of Ca

[0021] (2) The ingredients are mixed to obtain a mixture, and the mixture is wet ground for 0.5-6h to obtain a ground material;

[0022] (3) The ground material is dried to a water content of less than 2%, crushed through an 80 mesh screen, pre-fired at 1220-1280℃ for 50-250min, and crushed to obtain a pre-fired material B.

[0023] Further, the amount of the additive is 0.3%-3.5% of the mass of the mixed pre-fired material. Adding appropriate additives in the mixed pre-fired material has a promoting effect, but the amount must be strictly controlled, and excessive addition may cause the material performance to decrease, and even have a harmful effect.

[0024] Further, the additive includes calcium carbonate, silicon dioxide and sorbitol. Calcium carbonate and silicon dioxide as additives can inhibit abnormal grain growth, thereby optimizing the microstructure of the material. Calcium oxide generated by the decomposition of calcium carbonate can play a fluxing role, reduce the reaction temperature, promote the progress of solid phase reaction, and can improve the density and magnetic properties of the product. The main role of adding sorbitol is as a dispersant, which can effectively improve the crystal structure and particle size distribution through steric hindrance stabilization.

[0025] Further, the additive further includes tricobalt tetroxide. Tricobalt tetroxide as an additive can significantly improve the magnetic properties of the permanent magnet ferrite.

[0026] Further, in step two, the grinding medium used in the ball mill is zirconia ball or bearing steel ball, the ball diameter is 3-8mm, the rotation speed of the ball mill is 60-300r / min, and the ball milling time is 5-20h.

[0027] Further, the average particle size of the mixture is 0.7-0.9μm.

[0028] Further, the magnetic field strength applied in the compression molding is 800-1500kA / m.

[0029] Further, the sintering comprises a preliminary sintering stage and a final sintering stage.

[0030] The temperature of the preliminary sintering stage is 800℃-1100℃, and the duration is 2-3h.

[0031] The temperature of the final sintering stage is 1200℃-1330℃, and the duration is 4-6h.

[0032] The sintering process is crucial in the preparation of ferrite, by setting the sintering process into two-stage sintering, the microstructure of the ferrite material can be better controlled, and the magnetic performance is improved, in the preliminary sintering stage, the moisture in the green body is uniformly reduced, which promotes the contact between the particles in the body at the beginning of sintering, and part of the solid phase reaction is carried out, in the final sintering stage, due to the high temperature, the solid phase reaction rate is fast, the core formed based on the part of the solid phase reaction in the preliminary sintering stage is further reacted, the reaction is more sufficient, the crystal grains in the sintered material are more uniform, and the magnetic performance is better.

[0033] Further, the sintering is carried out in air or oxygen atmosphere.

[0034] Further, the residual magnetism Br of the permanent ferrite is ≥4650Gs, the maximum magnetic energy product (BH)max is ≥5.05MGOe, the demagnetization ratio Hk / Hcj is ≥0.94, and the relative magnetic permeability is ≥1.05.

[0035] The beneficial effects of the present application are as follows:

[0036] The present application uses two different pre-sintered materials as the sintering raw material of ferrite, the pre-sintered material A and the pre-sintered material B have obvious differences in composition and performance due to different raw materials and preparation processes, the present application reasonably matches the two pre-sintered materials and adds additives, and combines with the optimized sintering process, which not only improves the residual magnetism and coercive force of the M-type permanent ferrite, but also enhances the overall stability and temperature resistance of the material. This method can not only effectively improve the product performance, but also is simple to operate, suitable for industrial production, and has strong market competitiveness. DETAILED DESCRIPTION

[0037] With reference to the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work are within the protection scope of the present application.

[0038] The preparation methods of pre-fired material A and pre-fired material B in the following examples and comparative examples are as follows:

[0039] Preparation of pre-fired material A:

[0040] S1, the mass of SrCO3, CaCO3, La2O3, Fe2O3, Co3O4 and ZnO is calculated according to the molar ratio of the molecular formula Sr 0.2 Ca 0.1 La 0.7 Fe 10.5 Co 0.21 Zn 0.12 O 19 , and then weighed to obtain the ingredients;

[0041] S2, the mixed material is obtained by mixing the ingredients, and the grinding material is obtained by wet grinding the mixed material for 5h;

[0042] S3, the grinding material is dried to a water content of less than 2%, crushed through an 80 mesh screen, pre-fired at 1260℃ for 5200min, and crushed to obtain pre-fired material A.

[0043] Preparation of pre-fired material B:

[0044] (1) the mass of CaCO3, La2O3, Fe2O3 and ZnO is calculated according to the molar ratio of the molecular formula Ca 0.45 La 0.55 Fe 10.5 Zn 0.2 O 19 , and then weighed to obtain the ingredients;

[0045] (2) the mixed material is obtained by mixing the ingredients, and the grinding material is obtained by wet grinding the mixed material for 5h;

[0046] (3) the grinding material is dried to a water content of less than 2%, crushed through an 80 mesh screen, pre-fired at 1260℃ for 200min, and crushed to obtain pre-fired material B.

[0047] Example 1

[0048] Step one, select pre-fired material A and pre-fired material B, mix uniformly according to the mass ratio A:B=9:1 to obtain mixed pre-fired material;

[0049] Step two, adding additives into the mixed pre-sintering material, the additives include calcium carbonate, silicon dioxide, sorbitol and tricobalt tetroxide, the adding amount of the additives is calculated by percentage of the mass of the mixed pre-sintering material, calcium carbonate: 0.20%, silicon dioxide: 0.33%, sorbitol: 0.30%, tricobalt tetroxide: 0.95%. The mixed pre-sintering material and the additives are mixed and wet ball milled, the grinding medium used in the ball milling is zirconium oxide ball, the diameter of the ball is 5mm, the rotating speed of the ball mill is 200r / min, the ball milling time is 10h, the mixture is obtained after drying, the average particle size of the mixture is 0.8μm;

[0050] Step three, the mixture is pressed into green body under the condition of the external magnetic field strength of 1000kA / m, the size of the green body is diameter of 40mm and height of 15mm, the green body is sintered in the high temperature furnace, two-stage sintering process is adopted, the green body is firstly sintered at 1100℃ for 2h, then cooled to below 100℃, and finally sintered at 1285℃ for 4h, the whole process is carried out in oxygen atmosphere, and the sintered body is obtained;

[0051] Step four, the sintered body is naturally cooled to room temperature and placed for 12h, and then the permanent magnet ferrite is obtained after grinding and cutting treatment.

[0052] Example 2

[0053] The difference from example 1 is only that the mass ratio of pre-sintering material A and pre-sintering material B is adjusted to A:B=8:2, and the adding amount of the additives is different, which is as follows:

[0054] Calcium carbonate: 0.53%, silicon dioxide: 0.32%, sorbitol: 0.30%, tricobalt tetroxide: 0.60%.

[0055] The other conditions and steps are the same as example 1.

[0056] Example 3

[0057] The difference from example 1 is only that the mass ratio of pre-sintering material A and pre-sintering material B is adjusted to A:B=7:3, and the adding amount of the additives is different, which is as follows:

[0058] Calcium carbonate: 0.29%, silicon dioxide: 0.37%, sorbitol: 0.30%, tricobalt tetroxide: 0.85%.

[0059] The other conditions and steps are the same as example 1.

[0060] Example 4

[0061] The difference from example 1 is only that the mass ratio of pre-sintering material A and pre-sintering material B is adjusted to A:B=6:4, and the adding amount of the additives is different, which is as follows:

[0062] Calcium carbonate: 0.35%, silicon dioxide: 0.36%, sorbitol 0.30%, tricobalt tetroxide: 0.80%.

[0063] Other conditions and steps are the same as Example 1.

[0064] Example 5

[0065] The difference from Example 1 is only that the mass ratio of pre-fired material A and pre-fired material B is adjusted to A:B=5:5, and the amount of additives added is different, as follows:

[0066] Calcium carbonate: 0.41%, silicon dioxide: 0.35%, sorbitol 0.30%, tricobalt tetroxide: 0.75%.

[0067] Other conditions and steps are the same as Example 1.

[0068] Example 6

[0069] The difference from Example 1 is only that the mass ratio of pre-fired material A and pre-fired material B is adjusted to A:B=4:6, and the amount of additives added is different, as follows:

[0070] Calcium carbonate: 0.47%, silicon dioxide: 0.34%, sorbitol 0.30%, tricobalt tetroxide: 0.70%.

[0071] Other conditions and steps are the same as Example 1.

[0072] Example 7

[0073] The difference from Example 1 is only that the mass ratio of pre-fired material A and pre-fired material B is adjusted to A:B=3:7, and the amount of additives added is different, as follows:

[0074] Calcium carbonate: 0.53%, silicon dioxide: 0.33%, sorbitol 0.30%, tricobalt tetroxide: 0.65%.

[0075] Other conditions and steps are the same as Example 1.

[0076] Example 8

[0077] The difference from Example 1 is only that the mass ratio of pre-fired material A and pre-fired material B is adjusted to A:B=2.5:7.5, and the amount of additives added is different, as follows:

[0078] Calcium carbonate: 0.56%, silicon dioxide: 0.33%, sorbitol 0.30%, tricobalt tetroxide: 0.63%.

[0079] Other conditions and steps are the same as Example 1.

[0080] Comparative Example 1

[0081] Comparative Example 2

[0082] Calcium carbonate: 0.12%, silicon dioxide: 0.40%, sorbitol 0.30%, tricobalt tetroxide: 1.00%.

[0083] Other conditions and steps are the same as Example 1.

[0084] Comparative Example 2

[0085] Comparative Example 2

[0086] Calcium carbonate: 0.70%, silicon dioxide: 0.30%, sorbitol 0.30%, tricobalt tetroxide: 0.50%.

[0087] Other conditions and steps are the same as Example 1.

[0088] Comparative Example 2

[0089] Comparative Example 2

[0090] Calcium carbonate: 0.15%, silicon dioxide: 0.35%, sorbitol 0.35%, tricobalt tetroxide: 0.20%.

[0091] Other conditions and steps are the same as Example 1.

[0092] Comparative Example 2

[0093] Comparative Example 2

[0094] Calcium carbonate: 0.18%, silicon dioxide: 0.39%, sorbitol 0.30%, tricobalt tetroxide: 0.90%.

[0095] Other conditions and steps are the same as Example 1.

[0096] The permanent ferrite magnets prepared in Example 1-Example 7 and Comparative Example 1-Comparative Example 3 were tested for performance, and the results are shown in Table 1:

[0097] Table 1

[0098]

[0099] It can be seen from Table 1 that the magnetic properties of the finished products are controlled by adjusting the ratio of pre-sintering material A and pre-sintering material B in Examples 1-8, and it can be seen from Comparative Examples 1-4 that the permanent magnet ferrite prepared according to the ratio in the examples has better comprehensive magnetic properties, wherein the maximum magnetic energy product and the demagnetization ratio are obviously improved, and it has more extensive practical value in the field of high-performance magnet applications.

[0100] It should be noted that the relational terms herein such as first and second and the like are used solely to distinguish one entity or action from another, without necessarily requiring or implying any such actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0101] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A production method for improving the magnetic properties of M-type permanent ferrite, characterized by, The method comprises the following steps: Step one, selecting pre-sintering material A and pre-sintering material B, mixing uniformly according to the mass ratio A:B=(9:1)~(2.5:7.5) to obtain mixed pre-sintering material; Step two, adding additives to the mixed pre-sintering material, mixing and wet ball milling, and drying to obtain a mixture; Step three, the mixture is pressed to form a green body, the green body is sintered to obtain a sintered body, the sintered body is naturally cooled to room temperature and then placed for 12-24 hours, and the sintered body is ground and cut to obtain an M-type permanent magnet ferrite; The pre-sintering material A is a pre-sintering material of high-performance permanent magnet ferrite, and the molecular formula of the high-performance permanent magnet ferrite is Sr x Ca y La 1-x-y Fe n Co z Zn m O 19 , wherein 0.01<=x<=0.25, 0.05<=y<=0.35, 6.9<=n<=11.8, 0.01<=z<=0.25, 0.01<=m<=0.12; The pre-sintering material B is a pre-sintering material of high remanence permanent magnet ferrite, and the molecular formula of the high remanence permanent magnet ferrite is Ca x La 1- x Fe n Zn m O 19 , wherein 0.01≤x≤0.65, 5.8≤n≤11.9, 0.01≤m≤0.

2.

2. The method of claim 1, wherein the M-type permanent ferrite is manufactured by adding a predetermined amount of a fluxing agent to a mixture of a predetermined amount of a raw material of the M-type permanent ferrite and a predetermined amount of a fluxing agent, and then sintering the mixture. The pre-sintering material A is prepared as follows: S1, Sr x Ca y La 1-x-y Fe n Co z Zn m O 19 The molar ratio of S1, S2, S3, S4, S5 and S6 is calculated to obtain the mass of SrCO3, CaCO3, La2O3, Fe2O3, Co3O4 and ZnO, and then weighed to obtain the ingredients. S2, mixing the ingredients to obtain a mixed material, wet grinding the mixed material for 0.5-6 hours to obtain a ground material; S3, drying the ground material to a water content of less than 2%, crushing it through an 80-mesh screen, and pre-sintering it at 1220-1280°C for 50-250 minutes, and crushing to obtain the pre-sintering material A.

3. The method for manufacturing an M-type permanent magnet ferrite with improved magnetic properties according to claim 1, characterized in that, The pre-sintering material B is prepared as follows: (1) CaCO3, La2O3, Fe2O3 and ZnO are weighed according to the molar ratio of the molecular formula Ca x La 1-x Fe n Zn m O 19 to obtain the ingredients; (2) mixing the ingredients to obtain a mixed material, wet grinding the mixed material for 0.5-6 hours to obtain a ground material; (3) drying the ground material to a water content of less than 2%, crushing it through an 80-mesh screen, and pre-sintering it at 1220-1280°C for 50-250 minutes, and crushing to obtain the pre-sintering material B.

4. The method of claim 1, wherein the M-type permanent ferrite is manufactured by adding a predetermined amount of a fluxing agent to a mixture of a predetermined amount of a raw material of the M-type permanent ferrite and a predetermined amount of a fluxing agent, and then sintering the mixture. The additive is added in an amount of 0.3%-3.5% of the mass of the mixed pre-sintering material.

5. The method for manufacturing an M-type permanent magnet ferrite according to claim 1, characterized in that, The additive comprises calcium carbonate, silicon dioxide, sorbitol, and tricobalt tetroxide. The additive comprises calcium carbonate, silicon dioxide, sorbitol, and tricobalt tetroxide. The additive comprises calcium carbonate, silicon dioxide, sorbitol, and tricobalt tetroxide.

6. The method for manufacturing an M-type permanent magnet ferrite according to claim 1, characterized in that, The average particle size of the mixture is 0.7-0.9 μm.

7. The method of claim 1, wherein the M-type permanent ferrite is manufactured by adding a predetermined amount of a fluxing agent to a mixture of a predetermined amount of a raw material of the M-type permanent ferrite and a predetermined amount of a fluxing agent, and then sintering the mixture. The magnetic field strength in the pressing forming is 800-1500 kA / m.

8. The method for manufacturing an M-type permanent magnet ferrite with improved magnetic properties according to claim 1, characterized in that, The sintering comprises a preliminary sintering stage and a final sintering stage. The temperature of the preliminary sintering stage is 800°C-1100°C, and the duration is 2-3 hours. The temperature of the final sintering stage is 1200°C-1330°C, and the duration is 4-6 hours.

9. The method for manufacturing an M-type permanent magnet ferrite with improved magnetic properties according to claim 1, characterized in that, The sintering is performed in an air or oxygen atmosphere.

10. A method for manufacturing an M-type permanent magnet ferrite with improved magnetic properties according to claim 1, characterized in that, The permanent magnet ferrite has a residual magnetization Br≥4650 Gs, a maximum magnetic energy product (BH)max≥5.05 MGOe, a demagnetization ratio Hk / Hcj≥0.94, and a relative permeability≥1.05.

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