CN1655295A - Magnet powder, manufacturing method of sintered magnet and product thereof - Google Patents

Abstract

The present invention relates to the field of magnetic materials, and more particularly to improvements in magnet powder of hexagonally shaped magnetoplumbite ferrite, sintered magnet manufacturing method and formulation thereof, the magnet or magnetic powder having a curie temperature comprising a major phase of hexagonally shaped ferrite comprising A, R, B and Fe and having the following characteristic molecular formula: a. the_1－XR_x [(Fe³⁺ _aFe²⁺ _b) _12－yB_y] _zO₁₉By adding trivalent Co and optimizing the formula, the magnetocrystalline anisotropy constant K1 is improved, the intrinsic coercivity (Hcj) is greatly improved, the optimal magnetic performance is achieved, and the process in the prior art is greatly simplified.

Description

Magnet powder, method for producing sintered magnet, and product thereof

Technical Field

The invention relates to the field of magnetic materials, in particular to improvement of a manufacturing method and a formula of magnet powder and a sintered magnet of hexagonal magnetoplumbite ferrite.

Background

The sintered permanent magnetic ferrite has stable magnetic performance and strong demagnetization resistance; the rust is not easy to occur, and a protective layer is not required to be coated; the product is hard and crisp, and can be used for processing and cutting special tools; the price is low, the use cost is low and the like; therefore, the method is widely applied to industries such as automobiles, household appliances, industrial automation and the like. The sintered permanent magnetic ferrite is made of hexagonal system sintered ferrite magnet, and especially the hexagonal magnetoplumbite ferrite is widely applied. The oxide permanent magnetic ferrite material mainly adopts strontium ferrite (SrO.6Fe) with magnetoplumbite (M type) hexagonal structure₂O₃) And barium ferrite (BaO.6Fe)₂O₃) The magnet is sintered as a raw material. Two main parameters that affect the magnetic properties of sintered magnets are remanence (Br) and intrinsic coercivity (Hcj). Br is positively correlated with factors such as magnet density, degree of magnet orientation, and saturation magnetization Ms of crystal structure. Due to the structural and performance limitations of the magnetoplumbite, the Br value of the conventional permanent magnetic ferrite is limited to about 446mT, and cannot be larger than 450mT basically.

In order to solve the problems, as early as 80 years, the M-type barium ferrite is studied in great detail by professors and the like at Nanjing university in China, and then the conclusion is drawn that La and Zn are added into the barium ferrite to replace Ba²⁺And Fe³⁺Can increase the saturation magnetization Ms of barium ferrite by about 20mT to obtain 450mT orA higher Br value, but at this time, it is difficult to simultaneously obtain a Br value of 450mT or more and an Hcj value of 318kA/m or more due to a decrease in the magnetocrystalline anisotropy field.

Hcj is proportional to the product (HA × fc) of the magnetocrystalline anisotropy field (HA ═ 2K1/Ms) and the monodomain grain ratio (fc), where K1 represents the magnetocrystalline anisotropy constant, determined by the crystal structure as Ms. The M-type strontium ferrite has a size of 3.5 × 10⁶erg/cm³K1, M type barium ferrite having a thickness of 3.3X 10⁶K1 of erg/cm3, since it is very difficult to raise K1 again in the conventional method, must make a breakthrough in the monodomain state of ferrite particles. The ferrite particles have the largest intrinsic coercive force Hcj in the single domain state. In order to make ferrite grains into monodomain grains, the size of ferrite particles must be smaller than 1 μm of the critical diameter thereof, and in the case of sintered magnets, the grain size must be controlled to 1 μm or less, and considering that the grain growth in the sintering process is about 2 times, the powder size in the molding process is 0.5 μm or less, which is liable to cause a reduction in productivity.

Japanese patent document discloses a process for producing an iron oxide sintered magnet (publication No. JP2002-353021A) in which at least two compounds of iron, element A, element R and element M are used as raw materials, mixed and sintered at 1000-1350 ℃ in air, the temperature is maintained for 1 second to 3 hours, 0.1 to 2% of silica or 0.2 to 4% of calcium carbonate may be added as a sintering aid, and the composition of the sintered magnet obtained is Sr in the examples_0.8La_0.2Fe_11.8Co_0.2O₁₉Wherein the dispersant used in the preparation process is calcium gluconate, and the concentration of the slurry is 75%. It is apparent from the above patent documents that Fe in the ferrite sintered magnet prepared therefrom is completely trivalent, the conditions of the required process are complicated, and the structure of the crystal is relatively simple, and when other substances are added, the structure of the crystal is easily changed and the stability is poor. Other documents relating to sintered magnets have been reported at home and abroad, but the use of compounds containing Co element is generally a divalent oxide (CoO) so as to satisfy the chargeThe above method requires strict control of raw materials and production processes in order to obtain a sintered magnet having excellent magnetic properties under balanced conditions. In addition, when ferrite is subjected to the pre-firing and sintering, the temperature thereof is also high, which causes an increase in energy consumption during production, and thus the production cost is high. Since the added raw materials are not reasonable, the shrinkage coefficients of the ferrites are different between the a-axis direction and the c-axis direction during sintering, which may cause significant deformation and directly affect the performance of the product. During sintering, only a common sintering process is adopted, so that partial materials are not fully sintered due to oxygen deficiency in the sintering process, and black blocks are generated.

Disclosure of Invention

The invention mainly solves the problems that in the prior art, because the formula of raw materials is unreasonable, the iron in the ferrite sintered magnet is completely trivalent, the crystal structure is single, when other substances are added in the sintering process, the crystal structure is easy to change, and the magnetic performance is seriously influenced.

The invention also solves the technical problems that the ferrite can not have high residual magnetic induction intensity, high coercivity, high intrinsic coercivity, high magnetic energy product, low intrinsic coercivity temperature coefficient and the like at the same time in the prior art; a formulation capable of comprehensively and effectively optimizing various parameters of ferrite and a method for manufacturing the ferrite powder and the sintered ferrite are provided.

The invention also solves the technical problems that the processes of proportioning, sintering and the like in the prior art must meet the charge balance condition in non-stoichiometric conditions, and the performance of the proportioning and the product is adversely affected; provides the magnet powder and the sintered magnet which are easy to configure, excellent in performance of the obtained product and reasonable in compatibility.

The invention also solves the technical problems of complex sintering process, difficult control, low operability, easy generation of black blocks due to oxygen deficiency, easy deformation of crystals, poor product quality and the like in the prior art; provides a simple, convenient and easy-to-implement method for producing magnet powder and sintered magnet with high product quality.

The invention also solves the technical problems of environmental pollution, low orientation degree, unreasonable temperature for presintering and sintering, high production cost and the like caused by adopting an organic medium dispersant in the prior art; provides a formula of magnet powder and sintered magnet which adopt an environment-friendly nontoxic organic surfactant as a dispersing agent and have high orientation degree and low cost, and a manufacturing method thereof.

The technical problem of the invention is mainly solved by the following technical scheme: a method for producing a sintered magnet or magnetic powder having a curie temperature, comprising a hexagonal ferrite main phase containing A, R, B and Fe, and having a molecular formula characterized by: a. the_1-XR_x[Fe³⁺ _aFe²⁺ _b)_12-yB_y]_zO₁₉Wherein

a represents one or two elements of Sr and Ba;

r represents at least one element selected from rare earth elements and Bi, and essentially contains La;

b represents at least one element of Co, Mn, Zn, Ge and As, wherein Co is necessarily contained, and the valence of the Co element is positive trivalent;

wherein a + b equals 1;

a is preferably 0.95-0.996, b is preferably 0.004-0.05;

z is preferably 0.8 to 1.2.

The preparation method is characterized by comprising the following steps:

a. primary burdening: mixing a plurality of compounds containing required elements and additives according to the molar ratio of the elements, wherein a compound of a positive trivalent Co element is adopted, the obtained mixture is crushed by a wet mixing process, and the average particle size of the mixed particles is not more than 2.0 mu m;

b. primary calcination: after wet mixing, presintering in air at the presintering temperature of 1100-1300 ℃ for 0.2-5 hours;

c. secondary burdening: weighing the pre-sintered material, adding the compound of the required elements and the additive again in a mass ratio mode, and grinding the obtained mixture in a wet method mode until the average grain size of crystal grains is not more than 0.80 mu m at most;

d. molding and sintering: adjusting the water content of the slurry obtained in the step to 65-80 wt%, then forming in a magnetic field, and sintering the formed body in an oxygen-rich atmosphere.

Conventionally, it is considered that the valence of Fe ion in hexagonal ferrite must be positive trivalent, if Fe exists in the crystal²⁺The inventors have also often gone into such a wrong region, but as a result of many diligent tests, the inventors concluded that it is appropriate to make the hexagonal ferrite contain a small amount of Fe by the process of the present invention²⁺The magnetic properties of the sintered ferrite are rather helped.

The inventors also proposed the use of La ions which simultaneously increase Br and Hcj³⁺、Co³⁺、Bi³⁺Plasma pair of Fe of M-type permanent magnetic ferrite³⁺And Sr²⁺The non-stoichiometric proportion can obviously improve the crystal structure of the M-type strontium ferrite and improve the performance of the permanent magnetic ferrite, so that the Ms of the permanent magnetic ferrite magnet after substitution is more traditional (SrO.6Fe)₂O₃) Ferrite is improved by about 2.0 percent and K₁The improvement can be improved by about 10 percent, and the product is favorable for developing towards miniaturization and light weight; meanwhile, the intrinsic coercive force Hcj temperature coefficient of the permanent magnetic ferrite magnet is obviously improved, the low-temperature demagnetization phenomenon of the product is prevented, and the use stability of the product in cold regions and high-altitude regions is improvedAnd (4) sex.

The present inventors have first proposed that, in the case where elements such as La, Bi, Co, Zn, and Mn are added in a molar ratio to determine the components of the ferrite before the pre-firing, one or more metal oxides such as La, Bi, Co, Zn, and Mn are added again in a mass percentage manner at the time of secondary grinding, thereby obtaining more excellent magnetic properties.

When in secondary burdening, adding La in the form of mass percent₂O₃May also be substituted for a part of Sr²⁺So as to obtain more stable magnetoplumbite type hexaferrite structure and larger magnetocrystalline anisotropy field, the other part stays on the surface of the crystal boundary to form crystal boundary components, which play the role of fluxing agent, prevent the crystal grains from further growing up, can obviously increase coercive force, and does not influence remanence too much, thereby improving (BH) max value, in addition, can widen the range of secondary sintering temperature, and is beneficial to improving the consistency of product performance and the yield

When in secondary burdening, Co is added in a mass percentage manner₂O₃、ZnO、Bi₂O₃、MnO₂Etc. metal oxides, may further be substituted for the moiety 4f₁And 4f₂Fe of crystal position³⁺Larger Bohr magneton number, especially Bi, can be obtained₂O₃The secondary sintering temperature can be obviously reduced, the density is increased, the Br is improved, and meanwhile, the secondary powder is easy to sand, and the sand grinding time is shortened.

The continuous ball milling is carried out by adopting an improved ball mill, and the average particle size of the ball-milled particles is controlled to be about 0.65 +/-0.05 mu m and is approximately in normal distribution. Thereby ensuring that the crystal grain can have higher Br value even though the crystal grain grows after the presintering and sintering.

Preferably, the molar ratios of the elements relative to the total amount of the metal elements in one batching are respectively as follows: a: 3.5 to 8.0 at%; r: 0.38 to 6.5 at%; b: 0.38 to 4.2 at%; fe: 85.0 to 92.0 at%, wherein the content of the trivalent cobalt is 0.3 to 3.0 at%. The molar ratio is favorable for controlling the addition of each component, so that the formula can reach the ideal ratio.

Preferably, one or more of the following compounds and additives are added during secondary batching, and the mass ratio of each element compound to the total weight of the weighed mixture is respectively as follows: la₂O₃：0.05～2.0wt％；Co₂O₃：0.05～1.2wt％；ZnO：0.2～0.6wt％；Bi₂O₃：0.05～0.6wt％；MnO₂：0.1～0.4wt％；B₂O₃：0.2～0.8wt％；CaCO₃：0.4～2.0wt％；Al₂O₃：0.3～2.0wt％；SrSO₄：0.2～1.0wt％；Cr₂O₃：0.3～1.5wt％；SrCO₃：0.1～1.0wt％；BaCO₃：0.1～1.0wt％；As₂O₃：0.4～2.0wt％；SiO₂: 0.3-1.0 wt%; kaolin: 0.6 to 2.0 wt%.

Preferably, the compound added during the secondary compounding must contain 0.05-0.6 wt% of Bi₂O₃The secondary sintering temperature can be obviously reduced, the energy of sintering loss is saved, the density is increased, Br is improved, and meanwhile, the secondary ball material is easy to sand, and the sand grinding time is shortened.

Preferably, the compound added during the secondary compounding process contains kaolin: 0.6 to 2.0 wt%. In the case of the second addition, SiO may not be added₂And Al₂O₃And the kaolin with lower price is used instead, thereby effectively reducing the production cost.

Preferably, the compound added during the secondary mixing contains a dispersant, wherein the dispersant is composed of an organic surfactant and is added in an amount of 0.2-2.0 wt%; and adding a solution containing an alkaline compound simultaneously with the addition of the dispersant. The time for adding the dispersant is not limited as long as the dispersant is contained in the finally obtained slurry for molding. However, the amount of the dispersion agent adsorbed on the surface of the crystal grains when the additive is added as a secondary ingredient becomes large, thereby facilitating the rotation of the crystal grains to obtain a higher degree of orientation. The addition of the dispersing agent can improve the particle size distribution of the coarsely ground granular powder; and organic surface active agents (namely dispersing agents) such as polyvinyl alcohol, calcium gluconate, ascorbic acid, sorbose and oleic acid are added into the forming slurry solution, sodium hydroxide solution and other reagents are added into the forming slurry solution, and the anisotropic sintered permanent magnetic ferrite magnet prepared by the production method of using the ball milling medium as water can achieve high orientation degree achieved by organic media (xylene and oleic acid), wherein the orientation degree is more than 96.0%. In addition, the organic medium (xylene and oleic acid) is a toxic substance, easily causes environmental pollution, and has great influence on the body of an operator.

Preferably, in the sintering step, the molded body is sintered in an oxygen-rich atmosphere at 1100-1260 ℃, the oxygen partial pressure is not less than 20%, and the temperature is kept for 0.2-3 hours, so that the oxygen-rich atmosphere sintering can ensure sufficient oxidation, and black blocks caused by insufficient oxygen content are prevented.

A sintered magnet produced by the above process, having a curie temperature, comprising a hexagonal ferrite main phase containing A, R, B and Fe, and having a molecular formula characterized by:

A_1-xR_x[(Fe³⁺ _aFe²⁺ _b)_12-yB_y]_zO₁₉wherein

a represents one or two elements of Sr and Ba;

r represents at least one element selected from rare earth elements and Bi, and essentially contains La;

b represents at least one element of Co, Mn, Zn, Ge and As, wherein Co is necessarily contained, and the valence of the Co element is positive trivalent;

wherein a + b equals 1;

a is preferably 0.95-0.996, b is preferably 0.004-0.05;

the preferable ranges of x and y are as follows: x is more than or equal to 0.05 and less than or equal to 0.5, and y is more than or equal to 0.05 and less than or equal to 0.45

z is preferably 0.8 to 1.2.

Preferably, where 1.0. ltoreq. x/y. ltoreq.1.5 and Z is 1, too large or too small a value of x/y will affect the properties of the magnet powder.

Preferably, the additive for producing the magnet powder is La₂O₃：0.05～2.0wt％、Co₂O₃：0.05～1.2wt％、ZnO：0.2～0.6wt％、Bi₂O₃：0.05～0.6wt％、MnO₂：0.1～0.4wt％、B₂O₃：0.2～0.8wt％、CaCO₃：0.4～2.0wt％、Al₂O₃：0.3～2.0wt％、SrSO₄：0.2～1.0wt％、Cr₂O₃：0.3～1.5wt％、SrCO₃：0.1～1.0wt％、BaCO₃：0.1～1.0wt％、As₂O₃：0.4～2.0wt％、SiO₂: 0.3-2.0 wt%, kaolin: 0.6-2.0 wt% of one or more of the following components.

Preferably, the optimized hexagonal ferrite main phase contains A, R¹B and Fe, having the following characteristic molecular formulae: a. the_1-XR¹ _x[(Fe³⁺ _aFe²⁺ _b)_12-yB_y]_zO₁₉Wherein,

a represents one or more elements of Sr and Ba;

R¹represents one or more elements selected from rare earth elements and Bi, and essentially contains La and Bi;

b represents at least one element of Co, Mn, Zn, Ge and As, wherein Co is necessarily contained, and the valence of the Co element is positive trivalent;

wherein a + b equals 1;

a is preferably 0.95-0.996, b is preferably 0.004-0.05;

the magnet powder prepared by the process is characterized by comprisingHas a Curie temperature, comprises a hexagonal ferrite main phase containing A, R, B and Fe, and has the following characteristic formula: a. the_1-XR_x[(Fe³⁺ _aFe²⁺ _b)_12-yB_y]_zO₁₉Wherein

a represents one or two elements of Sr and Ba;

r represents at least one element selected from rare earth elements and Bi, and essentially contains La;

b represents at least one element of Co, Mn, Zn, Ge and As, wherein Co is necessarily contained, and the valence of the Co element is positive trivalent;

wherein a + b equals 1;

a is preferably 0.95-0.996, b is preferably 0.004-0.05;

preferably, where 1.0. ltoreq. x/y. ltoreq.1.5 and Z is 1, too large or too small a value of x/y will affect the properties of the magnet powder.

Preferably, the additive for producing the magnet powder is La₂O₃：0.05～2.0wt％、Co₂O₃：0.05～1.2wt％、ZnO：0.2～0.6wt％、Bi₂O₃：0.05～0.6wt％、MnO₂：0.1～0.4wt％、B₂O₃：0.2～0.8wt％、CaCO₃：0.4～2.0wt％、Al₂O₃：0.3～2.0wt％、SrSO₄：0.2～1.0wt％、Cr₂O₃：0.3～1.5wt％、SrCO₃：0.1～1.0wt％、BaCO₃：0.1～1.0wt％、As₂O₃：0.4～2.0wt％、SiO₂: 0.3-2.0 wt%, kaolin: 0.6-2.0 wt% of one or more of the following components.

Preferably, the optimized hexagonal ferrite main phase contains A, R¹B and Fe, having the following characteristic molecular formulae: a. the_1-XR¹ _x[(Fe³⁺ _aFe²⁺ _b)_12-yB_y]_zO₁₉Wherein,

a represents one or more elements of Sr and Ba;

R¹represents one or more elements selected from rare earth elements and Bi, and essentially contains La and Bi;

b represents at least one element of Co, Mn, Zn, Ge and As, wherein Co must be contained, and the valence of Co is positive three;

a is preferably 0.95-0.996, b is preferably 0.004-0.05;

a + b equals 1;

therefore, the invention has the following advantages:

1. by adding the positive trivalent Co and optimizing the formula, the magnetocrystalline anisotropy constant K1 is improved, the intrinsic coercivity (Hcj) is greatly improved, the optimal magnetic performance is achieved, and the process in the prior art is greatly simplified.

2. Meanwhile, the ferrite has high residual magnetic induction intensity, high coercivity, high intrinsic coercivity, high magnetic energy product and low intrinsic coercivity temperature coefficient;

3. the method is simple, convenient to operate and easy to implement;

4. the nontoxic organic medium dispersant is adopted, so that the environment-friendly function is realized, and the grinding of crystal grains and the obtaining of higher orientation degree are facilitated;

5. the temperature of pre-sintering and sintering is effectively reduced, the production cost is favorably reduced, and the crystal grains are uniform in size;

6. the compatibility of various components is reasonable, the adding sequence is scientific, and the control of the grain size is facilitated;

7. and the secondary addition is adopted, so that the performance of the product is further improved, and the control of crystal grains is facilitated.

Drawings

Figure 1 shows the comparison of the orientation degree of a magnet obtained by three ball milling modes of using oleic acid as a dispersing agent, xylene as a ball milling medium, adding water into the dispersing agent as the ball milling medium and using water as the ball milling medium

Detailed Description

The technical scheme of the invention is further specifically described by the following embodiments and the accompanying drawings.

Example 1:

the following raw materials are adopted as raw materials:

Fe₃O₄powder and Fe₂O₃Powder (wherein Fe₂O₃The purity of the powder is more than or equal to 99.2 wt%, and the original average particle size of the particles is as follows: 1.0um)85.6 wt%

SrCO₃12.1 wt% of powder (purity is more than or equal to 98.0 wt%, original average particle size of particles is 2.1um)

La₂O₃1.5 wt% of powder (purity is more than or equal to 99.0 wt%, original average particle size of particles is 0.8um)

Co₂O₃0.8 wt% of powder (purity is more than or equal to 99.0 wt%, original average particle size of particles is 0.8um)

The method comprises the following steps of carrying out physical and chemical analysis on various raw materials, taking the raw materials in a molar ratio mode, adding the raw materials and additives (specific substances) into a wet ball mill, mixing, drying, presintering in air at 1210 ℃, and carrying out heat preservation for 2 hours to obtain a granular presintering material, wherein the granular presintering material has a ferrite main phase as follows:

Sr_1-XLa_x[(Fe³⁺ _aFe²⁺ _b)_12-yCo_y]O₁₉。

0.4 wt% of a dispersant was added to the obtained calcined material, followed by coarsely pulverizing the calcined material and dry-coarsely pulverizing the added additive in a continuous dry vibration ball mill for 10 minutes, and the average particle size of the pulverized powder was 4.2 μm.

Next, 450 g of the coarsely pulverized material produced in the above manner was weighed, and 0.4 wt% SiO was added₂0.7 wt.% of CaCO₃And then 680 ml of deionized water was added as a ball milling medium to prepare a slurry for pulverization.

Wet pulverization was carried out in a modified high-efficiency ball mill for 24 hours, and the average particle size of the slurry particles after pulverization was 0.7 μm.

After the wet grinding, the molding slurry was subjected to centrifugal dehydration to adjust the slurry concentration to 76%, and then molded, and a molding magnetic field of 12000Oe was applied in the pressing direction at the same time as the pressing. The resulting molded article was a cylinder having a diameter of 43.2mm and a height of 13mm, and the molding pressure was 10 MPa.

And (3) carrying out heat treatment on the formed body at the temperature of 100-600 ℃ to completely remove the organic dispersing agent, then sintering in air at the temperature rise speed of 150 ℃/h and keeping the temperature at 1220 ℃ for 1.5 h to obtain a sintered body. The upper and lower surfaces of the sintered body were polished, and the residual magnetic induction strength (Br), coercive force (Hcb), intrinsic coercive force (Hcj), and maximum magnetic energy product (BH) max were measured.

Comparative example 1

The following raw materials are adopted as raw materials:

Fe₂O₃powder (purity is more than or equal to 99.8 wt%, original average particle size of particles is 1.0um)85.6 wt%

SrCO₃12.1 wt% of powder (purity is more than or equal to 98.0 wt%, original average particle size of particles is 2.1um)

La₂O₃1.5 wt% of powder (purity is more than or equal to 99.0 wt%, original average particle size of particles is 0.8um)

CoO powder (purity not less than 96.0 wt%, original average particle size of particles: 0.8um) 0.8 wt%

Carrying out physical and chemical analysis on various raw materials, taking the raw materials in a molar ratio mode, adding the raw materials and additives into a wet ball mill, mixing, drying, presintering in air at 1210 ℃, and preserving heat for 2 hours to obtain a granular presintering material, wherein the granular presintering material has a ferrite main phase as follows: sr_1-xLa_xFe³⁺ _12-yCo_yO₁₉。

0.4 wt% of a dispersant was added to the obtained calcined material, followed by coarsely pulverizing the calcined material and dry-coarsely pulverizing the added additive in a continuous dry vibration ball mill for 10 minutes, and the average particle size of the pulverized powder was 4.2 μm.

Next, 450 g of the coarsely pulverized material produced in the above manner was weighed, and 0.4 wt% SiO was added₂0.7 wt.% of CaCO₃And then 680 ml of deionized water was added as a ball milling medium to prepare a slurry for pulverization.

Wet pulverization was carried out in a modified high-efficiency ball mill for 24 hours, and the average particle size of the slurry particles after pulverization was 0.7 μm.

After the wet grinding, the molding slurry was subjected to centrifugal dehydration to adjust the slurry concentration to 76%, and then molded, and a molding magnetic field of 12000Oe was applied in the pressing direction at the same time as the pressing. The resulting molded article was a cylinder having a diameter of 43.2mm and a height of 13mm, and the molding pressure was 10 MPa.

And (3) carrying out heat treatment on the formed body at the temperature of 100-600 ℃ to completely remove the organic dispersing agent, then sintering in air at the temperature rise speed of 150 ℃/h and keeping the temperature at 1220 ℃ for 1.5 h to obtain a sintered body. The upper and lower surfaces of the sintered body were polished, and the residual magnetic induction strength (Br), coercive force (Hcb), intrinsic coercive force (Hcj), and maximum magnetic energy product (BH) max were measured.

Table 1: comparison between the magnetic Properties of example 1 and comparative example 1

Example 2:

the following raw materials are adopted as raw materials:

Fe₃O₄powder and Fe₂O₃Powder (wherein Fe₂O₃The purity of the powder is more than or equal to 99.2 wt%, and the original average particle size of the particles is as follows: 1.0um)84.5 wt%

SrCO₃Powder (purity more than or equal to 98.0 wt%, original average particle size of particles: 2.1um) 10.8 wt%

La₂O₃3.2 wt% of powder (purity is more than or equal to 99.0 wt%, original average particle size of particles is 0.8um)

Co₂O₃1.5 wt% of powder (purity is more than or equal to 99.0 wt%, original average particle size of particles is 0.8um)

Adding raw materials and additives into a wet ball mill, mixing, drying, presintering at 1200 ℃ in air, and preserving heat for 1.5 hours to obtain a granular presintering material, wherein the granular presintering material has the following main phases of ferrite:

Sr_1-XLa_x[(Fe³⁺ _aFe²⁺ _b)_12-yCo_y]O₁₉。

the obtained calcined material was roughly pulverized in a dry manner in a continuous dry vibration ball mill for 10 minutes, and the average particle size of the pulverized powder was 4.2 μm.

Next, 450 g of the coarsely pulverized material produced in the above manner was weighed, and 0.3 wt% SiO was added₂0.7 wt.% of CaCO₃1.5 wt% of oleic acid and 0.1 wt% of NaOH mixed solution, 1.0 wt% of La₂O₃0.9 wt% of Co₂O₃1.0 wt% of Al₂O₃And then 680 ml of deionized water is added as a ball milling mediumAnd preparing a slurry for pulverization.

Wet pulverization was carried out in a modified high-efficiency ball mill for 35 hours, and the average particle size of the slurry particles after pulverization was 0.60 μm.

After the wet grinding, the molding slurry was subjected to centrifugal dehydration to adjust the slurry concentration to 76%, and then molded, and a molding magnetic field of 12000Oe was applied in the pressing direction at the same time as the pressing. The resulting molded article was a cylinder having a diameter of 43.2mm and a height of 13mm, and the molding pressure was 10 MPa.

The molded body is subjected to heat treatment at a temperature of 100-600 ℃ to completely remove oleic acid, and then is sintered in an oxygen-rich atmosphere at a temperature rise rate of 150 ℃/h and at 1220 ℃ for 0.5 h with an oxygen partial pressure of 25% to obtain a sintered body. The upper and lower surfaces of the sintered body were polished, and the residual magnetic induction strength (Br), coercive force (Hcb), intrinsic coercive force (Hcj), and maximum magnetic energy product (BH) max were measured.

Comparative example 2

The following raw materials are adopted as raw materials:

Fe₂O₃powder (wherein Fe₂O₃The purity of the powder is more than or equal to 99.2 wt%, and the original average particle size of the particles is as follows: 1.0um)84.5 wt%

SrCO₃Powder (purity more than or equal to 98.0 wt%, original average particle size of particles: 2.1um) 10.8 wt%

La₂O₃3.2 wt% of powder (purity is more than or equal to 99.0 wt%, original average particle size of particles is 0.8um)

Co₃O₄And CoO powder (purity not less than 99.0 wt%, original average particle size of particles: 0.8um) 1.5 wt%

Adding raw materials and additives into a wet ball mill, mixing, drying, presintering at 1200 ℃ in air, and preserving heat for 1.5 hours to obtain a granular presintering material, wherein the granular presintering material has the following main phases of ferrite:

Sr_1-xLa_xFe³⁺ _12-yCo_yO₁₉。

the obtained calcined material was roughly pulverized in a dry manner in a continuous dry vibration ball mill for 10 minutes, and the average particle size of the pulverized powder was 4.2 μm.

Next, 450 g of the coarsely pulverized material produced in the above manner was weighed, and 0.3 wt% SiO was added₂0.7 wt.% of CaCO₃1.5 wt% of oleic acid and 0.1 wt% of NaOH mixed solution, 1.0 wt% of La₂O₃0.9 wt% of CoO, 1.0 wt% of Al₂O₃And then 680 ml of deionized water was added as a ball milling medium to prepare a slurry for pulverization.

Wet pulverization was carried out in a modified high-efficiency ball mill for 35 hours, and the average particle size of the slurry particles after pulverization was 0.60 μm.

After the wet grinding, the molding slurry was subjected to centrifugal dehydration to adjust the slurry concentration to 76%, and then molded, and a molding magnetic field of 12000Oe was applied in the pressing direction at the same time as the pressing. The resulting molded article was a cylinder having a diameter of 43.2mm and a height of 13mm, and the molding pressure was 10 MPa. The molded body is subjected to heat treatment at a temperature of 100-600 ℃ to completely remove oleic acid, and then is sintered in an oxygen-rich atmosphere at a temperature rise rate of 150 ℃/h and at 1220 ℃ for 0.5 h with an oxygen partial pressure of 25% to obtain a sintered body. The upper and lower surfaces of the sintered body were polished, and the residual magnetic induction strength (Br), coercive force (Hcb), intrinsic coercive force (Hcj), and maximum magnetic energy product (BH) max were measured.

Table 2: comparison between the magnetic properties of example 2 and comparative example 2

Example 3:

the following raw materials are adopted as raw materials:

Fe₃O₄powder and Fe₂O₃Powder (wherein Fe₂O₃The purity of the powder is more than or equal to 99.2 wt%, and the original average particle size of the particles is as follows: 1.0um)82.5 wt%

SrCO₃Powder (purity more than or equal to 98.0 wt%, original average particle size of particles: 2.1um) 7.6 wt%

La₂O₃Powder (purity is more than or equal to 99.0 wt%, original average particle size of particles is 0.8um) 6.3 wt%

Co₂O₃3.6 wt% of powder (purity is more than or equal to 99.0 wt%, original average particle size of particles is 0.8um)

The following materials were used as additives

SiO₂: 0.2 wt% of powder (purity is more than or equal to 99.0 wt%, original average particle size of particles is 0.5um)

CaCO₃: 0.2 wt% of powder (purity is more than or equal to 99.0 wt%, original average particle size of particles is 1.5um)

Adding raw materials and additives into a wet ball mill, mixing, drying, presintering at 1250 ℃ in air, and preserving heat for 2.5 hours to obtain a granular presintering material, wherein the granular presintering material has the following main phases of ferrite:

Sr_1-XLa_x[(Fe³⁺ _aFe²⁺ _b)_12-yCo_y]O₁₉。

the obtained calcined material was added and then dry-coarsely pulverized in a continuous dry vibration ball mill for 10 minutes, and the average particle size of the pulverized powder was 4.2 μm.

Next, 450 g of the coarsely pulverized material produced in the above manner was weighed, and 1.0 wt% La was added₂O₃，SiO₂0.3wt％、0.8wt％CaCO₃1.5 wt% of dispersant, and 680 ml of deionized water as ball milling mediumAnd (5) preparing the grinding slurry.

Wet pulverization was carried out in a modified high-efficiency ball mill for 35 hours, and the average particle size of the slurry particles after pulverization was 0.62 μm.

After the wet pulverization, the slurry for molding was subjected to centrifugal dehydration to adjust the slurry concentration to 73%, and then molded, and a magnetic field of 13000Oe was applied in the direction of the pressing while the molding was performed, whereby a molded article having a cylindrical shape with a diameter of 43.2mm and a height of 13mm was obtained and a molding pressure of 10 MPa.

And (3) carrying out heat treatment on the formed body at the temperature of 100-600 ℃ to completely remove the organic dispersing agent, then sintering in air at the temperature rise speed of 150 ℃/h and keeping the temperature at 1220 ℃ for 1.5 h to obtain a sintered body. The upper and lower surfaces of the sintered body were polished, and the residual magnetic induction strength (Br), coercive force (Hcb), intrinsic coercive force (Hcj), and maximum magnetic energy product (BH) max were measured.

Comparative example 3

The following raw materials are adopted as raw materials:

Fe₂O₃powder (wherein Fe₂O₃The purity of the powder is more than or equal to 99.2 wt%, and the original average particle size of the particles is as follows: 1.0um)82.5 wt%

SrCO₃Powder (purity more than or equal to 98.0 wt%, original average particle size of particles: 2.1um) 7.6 wt%

La₂O₃Powder (purity is more than or equal to 99.0 wt%, original average particle size of particles is 0.8um) 6.3 wt%

CoO powder (purity is more than or equal to 99.0 wt%, original average particle size of particles is 0.8um) 3.6 wt%

The following materials were used as additives

SiO₂: 0.2 wt% of powder (purity is more than or equal to 99.0 wt%, original average particle size of particles is 0.5um)

CaCO₃: powder (purity is more than or equal to 99.0 wt%, original average particle size of the particles: 1.5um)0.2 wt%

Adding raw materials and additives into a wet ball mill, mixing, drying, presintering at 1250 ℃ in air, and preserving heat for 2.5 hours to obtain a granular presintering material, wherein the granular presintering material has the following main phases of ferrite:

Sr_1-xLa_xFe³⁺ _12-xCo²⁺ _xO₁₉。

the obtained calcined material was added and then dry-coarsely pulverized in a continuous dry vibration ball mill for 10 minutes, and the average particle size of the pulverized powder was 4.2 μm.

Next, 450 g of the coarsely pulverized material produced in the above manner was weighed, and 1.0 wt% La was added₂O₃，SiO₂0.3wt％、0.8wt％CaCO₃And 1.5 wt% of dispersant, and then 680 ml of deionized water is added as a ball milling medium to prepare slurry for pulverization.

Wet pulverization was carried out in a modified high-efficiency ball mill for 35 hours, and the average particle size of the slurry particles after pulverization was 0.62 μm.

After the wet pulverization, the slurry for molding was subjected to centrifugal dehydration to adjust the slurry concentration to 73%, and then molded, and a magnetic field of 13000Oe was applied in the direction of the pressing while the molding was performed, whereby a molded article having a cylindrical shape with a diameter of 43.2mm and a height of 13mm was obtained and a molding pressure of 10 MPa.

And (3) carrying out heat treatment on the formed body at the temperature of 100-600 ℃ to completely remove the organic dispersing agent, then sintering in air at the temperature rise speed of 150 ℃/h and keeping the temperature at 1220 ℃ for 1.5 h to obtain a sintered body. The upper and lower surfaces of the sintered body were polished, and the residual magnetic induction strength (Br), coercive force (Hcb), intrinsic coercive force (Hcj), and maximum magnetic energy product (BH) max were measured.

Table 3: comparison between the magnetic properties of example 3 and comparative example 3

Example 4:

the following raw materials are adopted as raw materials:

Fe₂O₃powder (Fe)₂O₃The purity of the powder is more than or equal to 99.2 wt%, and the original average particle size of the particles is as follows: 1.0um)85.6 wt%

SrCO₃12.1 wt% of powder (purity is more than or equal to 98.0 wt%, original average particle size of particles is 2.1um)

La₂O₃1.5 wt% of powder (purity is more than or equal to 99.0 wt%, original average particle size of particles is 0.8um)

Co₂O₃0.8 wt% of powder (purity is more than or equal to 99.0 wt%, original average particle size of particles is 0.8um)

Adding raw materials and additives into a wet ball mill, mixing, drying, presintering in air at 1260 ℃, and preserving heat for 2.5 hours to obtain a granular presintering material, wherein the granular presintering material has the following main phases of ferrite: sr_1-XLa_x[(Fe³⁺ _aFe²⁺ _b)_12-yCo_y]O₁₉。

0.4 wt% of a dispersant was added to the calcined powder, and the calcined powder was dry-coarsely pulverized in a continuous dry vibration ball mill for 10 minutes, whereby the average particle size of the pulverized powder was 4.2 μm.

Next, 450 g of the coarsely pulverized material produced in the above manner was weighed, and 1.0 wt% of kaolin, 1.3 wt% of a dispersant, and 1.0 wt% of La were added₂O₃And then 680 ml of deionized water was added as a ball milling medium to prepare a slurry for pulverization.

Wet pulverization was carried out in a modified high-efficiency ball mill for 35 hours, and the average particle size of the slurry particles after pulverization was 0.61. mu.m.

After the wet grinding, the molding slurry was subjected to centrifugal dehydration to adjust the slurry concentration to 78%, and then molded, and a molding magnetic field of 13000Oe was applied in the pressing direction at the same time as the pressing. The resulting molded article was a cylinder having a diameter of 43.2mm and a height of 13mm, and the molding pressure was 10 MPa.

And (3) carrying out heat treatment on the formed body at the temperature of 100-600 ℃ to completely remove the organic dispersing agent, and then sintering in air at the temperature rise speed of 150 ℃/h, keeping the temperature at 1220 ℃ for 1.5 h, and controlling the oxygen partial pressure at 50% to obtain a sintered body. The upper and lower surfaces of the sintered body were polished, and the residual magnetic induction strength (Br), coercive force (Hcb), intrinsic coercive force (Hcj), and maximum magnetic energy product (BH) max were measured.

Table 4: example 4 magnetic Properties

Example 5:

the following raw materials are adopted as raw materials:

Fe₂O₃powder (Fe)₂O₃The purity of the powder is more than or equal to 99.2 wt%, and the original average particle size of the particles is as follows: 1.0um)83.0 wt%

SrCO₃Powder (purity more than or equal to 98.0 wt%, original average particle size of particles: 2.1um) 9.5 wt%

La₂O₃2.9 wt% of powder (purity is more than or equal to 99.0 wt%, original average particle size of particles is 0.8um)

Co₂O₃1.5 wt% of powder (purity is more than or equal to 99.0 wt%, original average particle size of particles is 0.8um)

Bi₂O₃2.2 wt% of powder (purity is more than or equal to 99.0 wt%, original average particle size of particles is 0.5um)

ZnO powder (purity is more than or equal to 99.0 wt%, original average particle size of particles is 1.0um) 0.9 wt%

Adding raw materials and additives into a wet ball mill, mixing, drying, presintering at 1200 ℃ in air, and preserving heat for 3 hours to obtain a granular presintering material, wherein the granular presintering material has the following main phases of ferrite: sr_1-XLa_x[(Fe³⁺ _aFe²⁺ _b)_12-yCo_gBi_h]O₁₉。

0.4 wt% of a dispersant was added to the calcined powder, and the calcined powder was subjected to coarse dry grinding in a continuous dry vibration ball mill for 10 minutes, whereby the average particle size of the ground powder was 4.2. mu.m.

Next, 450 g of the coarsely pulverized material produced in the above manner was weighed, and 0.4 wt% SiO was added₂0.75 wt% of CaCO₃1.5 wt% of dispersant, 0.4 wt% of Bi₂O₃And then 680 ml of deionized water was added as a ball milling medium to prepare a slurry for pulverization.

Wet pulverization was carried out in a modified high-efficiency ball mill for 35 hours, and the average particle size of the slurry particles after pulverization was 0.61. mu.m.

After the wet grinding, the molding slurry was subjected to centrifugal dehydration to adjust the slurry concentration to 80%, and then molded, and a molding magnetic field of 13000Oe was applied in the pressing direction at the same time as the pressing. The resulting molded article was a cylinder having a diameter of 43.2mm and a height of 13mm, and the molding pressure was 10 MPa.

And (3) carrying out heat treatment on the formed body at the temperature of 100-600 ℃, completely removing the organic dispersing agent, then sintering in air at the temperature rise speed of 150 ℃/h, and keeping the temperature at 1200 ℃ for 45 minutes to obtain a sintered body. The upper and lower surfaces of the sintered body were polished, and the residual magnetic induction strength (Br), coercive force (Hcb), intrinsic coercive force (Hcj), and maximum magnetic energy product (BH) max were measured.

Table 5: example 5 magnetic Properties

Example 6:

the following raw materials are adopted as raw materials:

Fe₂O₃powder (Fe)₂O₃The purity of the powder is more than or equal to 99.2 wt%, and the original average particle size of the particles is as follows: 1.0um)84.9 wt%

SrCO₃Powder (purity more than or equal to 98.0 wt%, original average particle size of particles: 2.1um) 10.5 wt%

La₂O₃3.5 wt% of powder (purity is more than or equal to 99.0 wt%, original average particle size of particles is 0.8um)

Co₂O₃1.1 wt% of powder (purity is more than or equal to 99.0 wt%, original average particle size of particles is 0.8um)

Adding raw materials and additives into a wet ball mill, mixing, drying, presintering at 1240 ℃ in air, and preserving heat for 2 hours to obtain a granular presintering material, so that the granular presintering material has the following main phases of ferrite: sr_0.76La_0.24Fe³⁺ _11.8Fe²⁺ _0.04Co³⁺ _0.16O₁₉。。

0.4 wt% of a dispersant was added to the calcined powder, and the calcined powder was dry-coarsely pulverized in a continuous dry vibration ball mill for 10 minutes, whereby the average particle size of the pulverized powder was 4.2 μm.

Next, 450 g of the coarsely pulverized material produced in the above manner was weighed, and 1.0 wt% of kaolin and 1.0 wt% of La were added₂O₃Then, 800 milli-xylene was added as a ball milling medium, and 1.0 wt% of oleic acid was used as a dispersant to prepare a slurry for pulverization.

Wet pulverization was carried out in a modified high-efficiency ball mill for 35 hours, and the average particle size of the slurry particles after pulverization was 0.61. mu.m.

After the wet grinding, the molding slurry was subjected to centrifugal dehydration to adjust the slurry concentration to 78%, and then molded, and a molding magnetic field of 13000Oe was applied in the pressing direction at the same time as the pressing. The resulting molded article was a cylinder having a diameter of 43.2mm and a height of 13mm, and the molding pressure was 10 MPa.

And (3) carrying out heat treatment on the formed body at the temperature of 100-600 ℃, completely removing the organic dispersing agent, then sintering in air at the temperature rise speed of 150 ℃/h, and keeping the temperature at 1200 ℃ for 1 h to obtain a sintered body. The upper and lower surfaces of the sintered body were polished, and the residual magnetic induction strength (Br), coercive force (Hcb), intrinsic coercive force (Hcj), and maximum magnetic energy product (BH) max were measured.

Comparative example 6:

the following raw materials are adopted as raw materials:

Fe₂O₃powder (Fe)₂O₃The purity of the powder is more than or equal to 99.2 wt%, and the original average particle size of the particles is as follows: 1.0um)

84.9wt％

SrCO₃Powder (purity more than or equal to 98.0 wt%, original average particle size of particles: 2.1um) 10.5 wt%

La₂O₃3.1 wt% of powder (purity is more than or equal to 99.0 wt%, original average particle size of particles is 0.8um)

Co₂O₃1.1 wt% of powder (purity is more than or equal to 99.0 wt%, original average particle size of particles is 0.8um)

Adding raw materials and additives into a wet ball mill, mixing, drying, presintering at 1240 ℃ in air, and preserving heat for 2 hours to obtain a granular presintering material, so that the granular presintering material has the following main phases of ferrite: sr_0.76La_0.24Fe³⁺ _11.8Fe²⁺ _0.04Co³⁺ _0.16O₁₉。。

The obtained calcined material was roughly pulverized in a dry vibration ball mill for 10 minutes in a dry manner, and the average particle size of the pulverized powder was 4.2 μm.

Subsequently, 450 g of the coarsely pulverized material produced in the above manner was weighed, and 1.0 wt% of kaolin and 1.Owt wt% of La were added₂O₃650ml of deionized water was added as a ball milling medium to prepare a slurry for pulverization.

Wet pulverization was carried out in a modified high-efficiency ball mill for 35 hours, and the average particle size of the slurry particles after pulverization was 0.61. mu.m.

After the wet grinding, the molding slurry was subjected to centrifugal dehydration to adjust the slurry concentration to 78%, and then molded, and a molding magnetic field of 13000Oe was applied in the pressing direction at the same time as the pressing. The resulting molded article was a cylinder having a diameter of 43.2mm and a height of 13mm, and the molding pressure was 1 OMPa.

The molded body is heat-treated at a temperature of 100 to 600 ℃ and then sintered in air at a temperature rise rate of 150 ℃/hour and held at 1200 ℃ for 1 hour to obtain a sintered body. The upper and lower surfaces of the sintered body were polished, and the residual magnetic induction strength (Br), coercive force (Hcb), intrinsic coercive force (Hcj), and maximum magnetic energy product (BH) max were measured.

Table 6: comparison between the magnetic Properties of example 6 and comparative example 6

The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.

Although the terms primary batch, secondary batch, primary calcination, molding and sintering are used more often herein, the possibility of using other terms is not excluded. These terms are used merely to more conveniently describe and explain the nature of the present invention; they are to be construed as being without limitation to any additional limitations that may be imposed by the spirit of the present invention.

Claims (16)

1. A method for manufacturing a sintered magnet or magnetic powder, said magnet or magnetic powder has a Curie temperature, comprises a hexagonal ferrite main phase containing A, R, B and Fe, and has a molecular formula of the following characteristics: A _1-X R _x [(Fe ³⁺ _a Fe ²⁺ _b ) _12-y B _y ] _z O ₁₉ , where, A represents one or two elements in Sr and Ba; R represents at least one element selected from rare earth elements and Bi, and must contain La; B represents at least one element of Co, Mn, Zn, Ge, As, which must contain Co, and the valence of Co element is positive trivalent; Among them, a+b is equal to 1; a is preferably 0.95-0.996, and b is preferably 0.004-0.05; z is preferably 0.8 to 1.2. It is characterized in that the preparation method comprises the following steps: a. Primary ingredients: according to the molar ratio of the elements, several compounds containing the required elements are mixed with the additives. Among them, the oxides of positive trivalent Co elements are used, and the resulting mixture is pulverized by a wet mixing process. After mixing The average particle size of the granular material is not greater than 2.0μm; b. Primary calcination: after wet mixing, pre-calcine in the air, the pre-calcination temperature is 1100 ℃ ~ 1300 ℃, heat preservation 0.2 ~ 5 hours; c. Secondary batching: Weigh the calcined material, and add several required element compounds and additives again in a mass proportioning manner, and continuously grind the resulting mixture in a wet method until the average particle size of the particles is less than 0.7 μm ; d. Forming and sintering: adjust the water content of the slurry obtained in the above steps to adjust its concentration to 65-80 wt%, and then form it in a magnetic field, and sinter the formed body in an oxygen-enriched atmosphere. 2. The manufacturing method of sintered magnet according to claim 1, characterized in that the molar ratios of the elements relative to the total amount of the metal elements in the first batching are: A: 3.5-8.0 at%; R: 0.38 ～6.5at%; B: 0.30～4.2at%; Fe: 85.0～92.0at%, wherein the content of the trivalent cobalt is 0.3-3at%. 3. The manufacturing method of sintered magnet or magnetic powder according to claim 1, characterized in that one or several of the following compounds are added during the secondary batching, and the mass of each element compound and additive accounts for the The mass percentages of the total amount of the mixture weighed are: La ₂ O ₃ : 0.05-2.0 wt%, Co ₂ O ₃ : 0.05-1.2 wt%, ZnO: 0.2-0.6 wt%, Bi ₂ O ₃ : 0.05-0.6 wt%, MnO ₂ : 0.1~0.4wt%, B ₂ O ₃ : 0.2~0.8wt%, CaCO ₃ : 0.4~2.0wt%, Al ₂ O ₃ : 0.3~2.0wt%, SrSO ₄ : 0.2~1.0wt% %, Cr ₂ O ₃ : 0.3~1.5wt%, SrCO ₃ : 0.1~1.0wt%, BaCO ₃ : 0.1~1.0wt%, As ₂ O ₃ : 0.4~2.0wt%, SiO ₂ : 0.3~2.0wt% , Kaolin: 0.6 to 2.0 wt%. 4. The manufacturing method of sintered magnet or magnetic powder according to claim 3, characterized in that the compound added during the secondary batching must contain 0.05-0.6wt% _{Bi2O3 .} 5. The manufacturing method of sintered magnet or magnetic powder according to claim 3, characterized in that the compound added during the secondary batching must contain 0.4-1.2wt% of kaolin. 6. The manufacturing method of sintered magnet or magnetic powder according to claim 1 or 2, characterized in that a dispersant is used in the wet grinding process of the mixture in the described secondary batching, and the dispersant is an organic surfactant , the addition amount is 0.2-2.0wt%; a solution containing an alkaline compound is added to the dispersant at the same time. 7. the manufacture method of sintered magnet or magnetic powder according to claim 3 is characterized in that a dispersant is used in the mixture wet grinding process in the described secondary batching, and the dispersant is an organic surfactant, which The addition amount is 0.2-2.0 wt %; a solution containing an alkaline compound is added to the dispersant at the same time. 8. The manufacturing method of sintered magnet or magnetic powder according to claim 1 or 2, characterized in that in the sintering step, the molded body is sintered in an oxygen-enriched atmosphere at 1100°C to 1260°C, and the oxygen partial pressure does not Less than 20%, keep warm for 0.2 to 3 hours. 9. A sintered magnet as claimed in claim 1, characterized in that it has a Curie temperature, comprises a hexagonal ferrite main phase containing A, R, B and Fe, and has a molecular formula of the following characteristics: A _1-X R _x [(Fe ³⁺ _a Fe ²⁺ _b ) _12-y B _y ] _z O ₁₉ , where, A represents one or two elements in Sr and Ba; R represents at least one element selected from rare earth elements and Bi, and must contain La; B represents at least one element of Co, Mn, Zn, Ge, As, which must contain Co, and the valence of Co element is positive trivalent; Among them, a+b is equal to 1; a is preferably 0.95-0.996, and b is preferably 0.004-0.05; The preferred ranges of x and y are: 0.05≤x≤0.5, 0.05≤y≤0.45 z is preferably 0.8 to 1.2. 10. The sintered magnet according to claim 9, characterized in that, the optimal values of x, y, z are: 1.0≤x/y≤1.5, Z is 1. 11. The sintered magnet according to claim 9, characterized in that the additives for making the sintered magnet are La ₂ O ₃ : 0.05-2.0wt%, Co ₂ O ₃ : 0.05-1.2wt%, ZnO: 0.2-0.6wt% %, Bi ₂ O ₃ : 0.05~0.6wt%, MnO ₂ : 0.1~0.4wt%, B ₂ O ₃ : 0.2~0.8wt%, CaCO ₃ : 0.4~2.0wt%, Al ₂ O ₃ : 0.3~2.0 wt%, SrSO ₄ : 0.2~1.0wt%, Cr ₂ O ₃ : 0.3~1.5wt%, SrCO ₃ : 0.1~1.0wt%, BaCO ₃ : 0.1~1.0wt%, As ₂ O ₃ : 0.4~2.0wt% %, SiO ₂ : 0.3-2.0wt%, kaolin: 0.6-2.0wt%, or one or more of them. 12. The sintered magnet according to claim 9 or 10 or 11, characterized in that the optimized hexagonal ferrite main phase contains A, R ¹ , B and Fe, and has the following molecular formula: A _1-X R ¹ _x [(Fe ³⁺ _a Fe ²⁺ _b ) _12-y B _y ] _z O ₁₉ where, A represents one or more elements of Sr and Ba; R ¹ represents more than one element selected from rare earth elements and Bi, and must contain La and Bi; B represents at least one element of Co, Mn, Zn, Ge, As, which must contain positive trivalent Co, and the valence of Co element is positive trivalent; Among them, a+b is equal to 1; a is preferably 0.95-0.996, and b is preferably 0.004-0.05; 13. A magnet powder made as claimed in claim 1, characterized in that it has a Curie temperature, comprises a hexagonal ferrite main phase containing A, R, B and Fe, and has a molecular formula of the following characteristics: A _1-X R _x [(Fe ³⁺ _a Fe ²⁺ _b ) _12-y B _y ] _z O ₁₉ , where, A represents one or two elements in Sr and Ba; R represents at least one element selected from rare earth elements and Bi, and must contain La; B represents at least one element of Co, Mn, Zn, Ge, As, which must contain Co, and the valence of Co element is positive trivalent; Among them, a+b is equal to 1; a is preferably 0.95-0.996, and b is preferably 0.004-0.05; The preferred ranges of x and y are: 0.05≤x≤0.5, 0.05≤y≤0.45 z is preferably 0.8 to 1.2. 14 . The sintered magnet according to claim 13 , wherein the optimum values of x, y and z are 1.0≤x/y≤1.5, and Z is 1. 15. The magnet powder according to claim 1113 _, characterized in that the additives _for making the magnet powder are _La2O3 : 0.05-2.0wt%, _Co2O3 : 0.05-1.2wt%, ZnO: 0.2-0.6wt% %, Bi ₂ O ₃ : 0.05~0.6wt%, MnO ₂ : 0.1~0.4wt%, B ₂ O ₃ : 0.2~0.8wt%, CaCO ₃ : 0.4~2.0wt%, Al ₂ O ₃ : 0.3~2.0 wt%, SrSO ₄ : 0.2~1.0wt%, Cr ₂ O ₃ : 0.3~1.5wt%, SrCO ₃ : 0.1~1.0wt%, BaCO ₃ : 0.1~1.0wt%, As ₂ O ₃ : 0.4~2.0wt% %, SiO ₂ : 0.3-2.0wt%, kaolin: 0.6-2.0wt%, or one or more of them. 16. The magnet powder according to claim 13, 14 or 15, characterized in that the optimized hexagonal ferrite main phase contains A, R ¹ , B and Fe, and has the following molecular formula: A _1-X R ¹ _x [(Fe ³⁺ _a Fe ²⁺ _b ) _12-y B _y ] _z O ₁₉ , where, A represents one or more elements of Sr and Ba; R ¹ represents more than one element selected from rare earth elements and Bi, and must contain La and Bi; B represents at least one element of Co, Mn, Zn, Ge, As, which must contain positive trivalent Co.