CN109434092B - Environment-friendly dispersion solution and method for preparing neodymium iron boron magnet material by using same - Google Patents
Environment-friendly dispersion solution and method for preparing neodymium iron boron magnet material by using same Download PDFInfo
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Abstract
The invention belongs to the technical field of neodymium iron boron material sintering, and particularly relates to a preparation method of a neodymium iron boron magnet material. In the preparation method of the neodymium iron boron magnet material, the dispersion liquid is added for mixing the powder before the auxiliary alloy powder is added into the main alloy powder, and the main alloy powder is added after the powder mixing is finished.
Description
Technical Field
The invention belongs to the technical field of neodymium iron boron material sintering, and particularly relates to a preparation method of a neodymium iron boron magnet material, in particular to a method for improving the dispersibility and the flowability of alloy powder in a powder mixing process by reducing the friction force and the agglomeration force between main and auxiliary alloy powder in a double-alloy process in the powder mixing stage in the sintering process of the neodymium iron boron magnet material, and obtaining uniformly dispersed non-agglomerated magnetic powder by adjusting the proportion of each component of a dispersion solution and the ultrasonic oscillation time.
Background
With the wide application of the neodymium iron boron permanent magnet material in the fields of new energy automobiles, wind power generation and the like, the demand of the sintered neodymium iron boron magnet material with high coercivity and high thermal stability is increased rapidly. In the prior art, heavy rare earth Dy/Tb is usually added to greatly improve the magnetic performance of the magnet, but on one hand, heavy rare earth occupies less rare earth resources and is expensive, so that a single alloy process is adopted to prepare a high-performance magnet, the product of remanence and magnetic energy is greatly reduced by adding multiple rare earths, and the production cost is greatly improved.
In the 90 s of the 20 th century, people put forward a method for preparing a neodymium-iron-boron magnet material from double alloys, which is characterized in that two alloys are smelted, wherein one alloy is a main alloy without heavy rare earth elements, the other alloy is a low-melting-point auxiliary alloy rich in heavy rare earth, and the two alloys are prepared by grinding the two alloys into powder through airflow milling, mixing the powder, pressing and sintering. The double-alloy method realizes the great reduction of the cost by adding the alloy powder with low melting point, but the main problem of the double-alloy method in the process industrialization is that the main alloy powder and the auxiliary alloy powder are not mixed uniformly, so that the magnet segregation is serious. In the prior art, the powder mixing process adopted in the preparation of the neodymium iron boron magnet by the double-alloy method is the same as the traditional powder mixing process, and the powder mixing process is realized by adding a small amount of dispersing agent during the powder mixing, but the method has obvious effect when the same alloy powder is mixed, when the double-alloy method is adopted for preparation, because the main alloy powder and the auxiliary alloy powder are two kinds of alloy powder with different properties, the auxiliary alloy powder is rich in rare earth elements, the size of the powder particles is 20-30 percent smaller than that of the main powder, and because the particle size difference is larger and the consumption of the auxiliary alloy material is less, a large amount of small crystal grains are usually agglomerated on one powder particle after the jet milling, and the agglomerated powder is difficult to disperse in the traditional powder mixing process, so that the friction force is increased, the flowability is poor, the particle distribution is uneven, the utilization rate of rare earth is low, and the production cost is high, and the magnet performance is unstable and the uniformity is poor.
Therefore, in order to solve the problem that the auxiliary alloy material is easy to agglomerate in the actual production process, the auxiliary alloy powder is usually dispersed by adding a dispersing agent into the auxiliary alloy powder and dispersing the auxiliary alloy powder by ultrasonic oscillation before mixing the powder. The added dispersant is mostly attached to the surface of the powder, which can not only prevent the oxidation of the powder, but also increase the fluidity of the powder and reduce the magnetostatic effect among magnetic powder. The used dispersing agent has a very obvious effect of improving the magnetic performance of the magnet material in the process of preparing the sintered neodymium-iron-boron magnet material by adopting a double-alloy method, and the microstructure of the magnet cannot cause agglomeration of neodymium-rich phase chunks due to uneven powder mixing, direct contact of crystal grains and growth of the crystal grains. Therefore, the method for adding the dispersing agent well solves the problems of agglomeration and large friction force among different powder particles, and the improvement of the method is not only beneficial to industrialization of a double-alloy method, but also beneficial to improving the magnetic property of a magnet material, improving the stability of the magnet neodymium iron boron, reducing the production cost, and especially reducing the production cost of a high-performance magnet. However, the dispersant materials used in the traditional process mostly have the problems of low dispersion efficiency, unstable dispersion performance or environmental pollution and the like, so that the development of a novel green environment-friendly dispersant has positive significance for the sintering preparation of neodymium iron boron magnet materials.
Disclosure of Invention
Therefore, the invention aims to provide an environment-friendly dispersion solution and further discloses a method for preparing a neodymium iron boron magnet material by using the dispersion solution.
In order to solve the technical problems, the environment-friendly dispersion solution comprises the following components in percentage by mass based on the total amount of the dispersion solution:
1-10 wt% of zinc stearate;
5-15 wt% of polyethylene glycol octane;
2-15 wt% of glycerol;
5-15 wt% of antistatic agent;
40-80 wt% of solvent.
Preferably, the antistatic agent comprises a T1502 antistatic agent.
Preferably, the solvent component comprises ethanol and/or methanol.
The invention also discloses the application of the environment-friendly dispersion liquid in preparing neodymium iron boron magnet materials.
The invention also discloses a preparation method of the neodymium iron boron magnet material, which comprises the following steps:
(1) preparing materials according to the selected alloy components of the neodymium iron boron magnet material, and smelting and quickly solidifying to obtain an alloy thin strip; carrying out hydrogen explosion coarse crushing on the obtained alloy thin strip, and then carrying out airflow fine grinding and crushing on the alloy thin strip to obtain main alloy powder;
(2) mixing the selected auxiliary alloy powder with the dispersion liquid of any one of claims 1 to 3, and performing dispersion treatment under ultrasonic oscillation;
(3) mixing the dispersed auxiliary alloy powder with the main alloy powder, carrying out orientation compression on the mixed alloy powder under a magnetic field, and further densifying by static pressure to obtain a green body;
(4) and carrying out vacuum sintering heat treatment on the obtained green body to obtain the required neodymium iron boron magnet material.
In the preparation method of the neodymium iron boron magnet material, preferably, the dispersion liquid is added for mixing the powder before the auxiliary alloy powder is added into the main alloy powder, and the main alloy powder is added after the powder mixing is finished.
The dispersion liquid is prepared by selected organic solution and dispersant components, and has the functions of accelerating the deagglomeration and fast dispersion of aggregates, effectively shortening the dispersion time, delaying the re-agglomeration time of particles and enabling the particles to be in a dispersed state for a long time; and the addition mode of the dispersion liquid is that after the auxiliary alloy powder is milled by airflow, the auxiliary alloy powder and the dispersion liquid are mixed and dispersed under ultrasonic oscillation, and the mixture is preferably added and then oscillated for 5-30 min.
In the step (1), the neodymium iron boron magnet material has a structure shown by the following general formula: a (PrNd)aFe100-a-b-cBbMc(wt.％)；B:RExN100-x(ii) a Wherein, M element is selected from at least one of Co, Ti, Mo, Ga, Al, Cu, Zr, Ta and Nb element, RE element is selected from at least one of Dy, Tb, Nd, Pr and Ho element, and N element is selected from at least one of Cu, Ga, Al, Fe, Zn, Ni and Sn element;
the a, b, c and x satisfy the following relations: a is more than or equal to 28 and less than or equal to 33, b is more than or equal to 0.92 and less than or equal to 1.05, c is more than or equal to 0 and less than or equal to 3, d is more than or equal to 0 and less than or equal to 1.5, and x is more than or equal to 50 and less than or equal to 100.
Further, the particle size of the main alloy powder is controlled to be 2-10um, and preferably 2.5-6 um; the particle size of the secondary alloy powder is controlled to be 1-5um, and preferably 1.5-3 um.
In the step (2), the mass ratio of the auxiliary alloy powder to the dispersion liquid is 1: 4-7.
In the step (2), the dispersion treatment step is performed in a micro-oxygen atmosphere containing nitrogen gas, and the oxygen content is controlled to be 200-500 ppm.
In the step (3), the magnetic field intensity of the compression step is controlled to be 2-3T, and the pressure of the static pressure step is controlled to be 200-300 MPa;
in the step (4), the vacuum sintering heat treatment specifically includes: placing the green body in a vacuum furnace and vacuumizing to less than 10 DEG C-2Heating the mixture pa, raising the temperature to 1040-.
The environment-friendly dispersion liquid is prepared by taking zinc stearate, polyethylene glycol octane, glycerol and a T1502 antistatic agent as effective components and adding ethanol and/or methanol solvents, and has the functions of accelerating the depolymerization and the rapid dispersion of aggregates, effectively shortening the dispersion time, delaying the re-agglomeration time of particles and enabling the particles to be in a dispersed state for a long time. The environment-friendly dispersion liquid is particularly suitable for preparing neodymium iron boron magnets by a double-alloy method, and specifically, the dispersion liquid and rare earth-rich low-melting-point alloy powder are mixed and subjected to ultrasonic oscillation to wet and disperse agglomerated powder and wrap the surface of the agglomerated powder, so that the magnetostatic force and the friction force among the powder are reduced; and through regulating and controlling the components of the dispersion liquid and the ultrasonic oscillation time, the rare earth-rich low-melting-point alloy powder and the neodymium-iron-boron main powder are uniformly mixed, so that the powder mixing time is favorably shortened, the working efficiency is improved, and the performance of the magnet is improved. The environment-friendly dispersion liquid disclosed by the invention is simple and convenient to prepare, free of pollution, low in cost, easy in obtaining of raw material components, free of pollution to alloy powder, and very suitable for industrial production, and the magnetic property and the processing property of the prepared magnet are greatly improved.
In the preparation method of the neodymium iron boron magnet material, the dispersion liquid is added for mixing the powder before the auxiliary alloy powder is added into the main alloy powder, and the main alloy powder is added after the powder mixing is finished.
Drawings
In order that the present disclosure may be more readily and clearly understood, the following detailed description of the present disclosure is provided in connection with specific embodiments thereof and the accompanying drawings, in which,
FIG. 1 is a fracture morphology of a magnet material prepared by the process of example 1 of the present invention;
fig. 2 shows the fracture morphology of the magnet material prepared by the conventional process in example 1 of the present invention.
Detailed Description
Example 1
The preparation method of the neodymium iron boron magnet material comprises the following steps:
(1) preparing materials according to a chemical general formula, and obtaining main alloy sheets and auxiliary alloy sheets by using praseodymium-neodymium metal, dysprosium-iron metal, aluminum metal, copper metal, cobalt metal, pure iron and a small amount of ferroboron with the purity of 99.5% as raw materials through a rapid solidification process;
the main alloy comprises the following components (PrNd)31FebalCo0.8Al0.4Zr0.1B0.96(wt.%) and thickness in
0.2-0.45 mm; the auxiliary alloy component is Dy75Fe15Cu10(wt.%), thickness 0.2-0.45 mm;
vacuumizing the main alloy casting sheet and the auxiliary alloy casting sheet, filling hydrogen, performing hydrogen explosion treatment after the hydrogen absorption of the casting sheet to generate crystal fracture, performing dehydrogenation at the temperature of 600 ℃ of 530 ℃ after reaction for 2-4h to obtain hydrogen explosion powder, and then performing jet milling to obtain the average grain diameter of the main alloy powder of 3-4 mu m and the average grain diameter of the auxiliary alloy powder of 2-3 mu m;
(2) in an argon-protected glove box, completely soaking the prepared auxiliary alloy powder in dispersion liquid, opening an ultrasonic oscillation instrument (the rotating speed is 3500 plus 4200r/min), dispersing the agglomerated powder under the conditions of dispersion liquid and ultrasonic oscillation, completely wrapping the powder by using a dispersing agent, taking out after 15min, and filtering for 1-2 times by using a filter sieve to separate the auxiliary alloy powder from the rest solution to obtain the dispersed auxiliary alloy powder;
the dispersion comprises the following components in percentage by total weight: 5 wt% of zinc stearate, 7 wt% of polyethylene glycol octane (C)8H18) 10 wt% of glycerol, 5 wt% of T1502 antistatic agent, 73 wt% of ethanol; controlling the weight ratio of the auxiliary alloy powder to the dispersion liquid to be 1: 5;
(3) uniformly mixing the dispersed auxiliary alloy powder and the main alloy powder in a three-dimensional mixer, performing orientation pressing on the mixed alloy powder in a 2T magnetic field to obtain a green body, and further improving the density of the green body by isostatic pressing under 200 Mpa;
(4) placing the prepared green body in a vacuum sintering furnace, controlling the sintering temperature to 1065 ℃, preserving the heat for 4 hours,
regulating the primary tempering temperature to 900 ℃ and keeping the temperature for 2h, and regulating the secondary tempering temperature to 490 ℃ and keeping the temperature for 4h to obtain the required magnet material.
Example 2
The preparation method of the neodymium iron boron magnet material comprises the following steps:
(1) preparing materials according to a chemical general formula, and obtaining main alloy sheets and auxiliary alloy sheets by using praseodymium-neodymium metal, dysprosium-iron metal, aluminum metal, copper metal, cobalt metal, zirconium metal, pure iron and a small amount of ferroboron with the purity of 99.5% as raw materials through a rapid hardening process;
the main alloy comprises the following components (PrNd)31FebalCo0.8Al0.4Zr0.1B0.96(wt.%) and thickness in
0.2-0.45 mm; the auxiliary alloy component is Dy75Fe15Cu10(wt.%), thickness 0.2-0.45 mm;
vacuumizing the main alloy casting sheet and the auxiliary alloy casting sheet, filling hydrogen, performing hydrogen explosion treatment after the hydrogen absorption of the casting sheet to generate crystal fracture, performing dehydrogenation at 580 ℃ after reaction for 2-4h to obtain hydrogen explosion powder, and then performing jet milling to obtain the main alloy powder with the average grain diameter of 3-4 microns and the auxiliary alloy powder with the average grain diameter of 2-3 microns;
(2) in an argon-protected glove box, completely soaking the auxiliary alloy powder in a dispersing agent, starting an ultrasonic oscillator, dispersing the agglomerated powder under the conditions of the dispersing agent and ultrasonic oscillation, wrapping the powder by the dispersing agent, taking out after 10min, and filtering for 1-2 times by a filter sieve to separate the auxiliary alloy powder from the rest solution to obtain the dispersed auxiliary alloy powder;
the dispersion comprises the following components in percentage by total weight: 4 wt% of zinc stearate, 8 wt% of polyethylene glycol octane (C8H18), 8 wt% of glycerol, 5 wt% of T1502 antistatic agent, and 75 wt% of methanol; controlling the weight ratio of the auxiliary alloy powder to the dispersion liquid to be 1: 4;
(3) uniformly mixing the dispersed auxiliary alloy powder and the main alloy powder in a three-dimensional mixer, performing orientation pressing on the mixed alloy powder in a 2T magnetic field to form a blank, and further improving the density of the blank in isostatic pressing under 200 Mpa;
(4) and placing the prepared green body in a vacuum sintering furnace, controlling the sintering temperature to 1070 ℃, preserving the heat for 4h, adjusting the primary tempering temperature to 900 ℃, preserving the heat for 3h, and preserving the secondary tempering temperature to 510 ℃ for 4h to prepare the required magnet material.
Example 3
The preparation method of the neodymium iron boron magnet material comprises the following steps:
(1) preparing materials according to a chemical general formula, and obtaining main alloy sheets and auxiliary alloy sheets by using praseodymium-neodymium metal, dysprosium metal, aluminum metal, copper metal, cobalt metal, pure iron and a small amount of ferroboron with the purity of 99.5% as raw materials through a rapid solidification process;
the main alloy comprises the following components (PrNd)31FebalCo0.8Al0.4Zr0.1B0.96(wt.%) thickness of 0.2-0.45 mm; the auxiliary alloy component is Dy75Fe15Cu10(wt.%), thickness 0.2-0.45 mm;
vacuumizing the main alloy casting sheet and the auxiliary alloy casting sheet, filling hydrogen, performing hydrogen explosion treatment after the hydrogen absorption of the casting sheet to generate crystal fracture, performing dehydrogenation at 580 ℃ after reaction for 2-4h to obtain hydrogen explosion powder, and then performing jet milling to obtain the main alloy powder with the average grain diameter of 3-4 microns and the auxiliary alloy powder with the average grain diameter of 2-3 microns;
(2) in an argon-protected glove box, completely soaking the auxiliary alloy powder in the dispersion liquid, opening an electromagnetic stirrer, dispersing the agglomerated powder under the vibration of a dispersing agent and ultrasonic waves, wrapping the powder by the dispersing agent, taking out after 10min, and filtering for 2-3 times by a filter sieve to separate the auxiliary alloy powder from the rest of the solution to obtain the dispersed auxiliary alloy powder;
the dispersion comprises the following components in percentage by total weight: 3 wt% of zinc stearate, 8 wt% of polyethylene glycol octane (C8H18), 10 wt% of glycerol, 6 wt% of T1502 antistatic agent and 73 wt% of ethanol; controlling the weight ratio of the auxiliary alloy powder to the dispersion liquid to be 1: 7;
(3) uniformly mixing the dispersed auxiliary alloy powder and the main alloy powder in a three-dimensional mixer, performing orientation pressing on the mixed alloy powder in a 2T magnetic field to form a blank, and further improving the density of the blank under the isostatic pressure of 200 Mpa;
(4) and (3) placing the prepared blank in a vacuum sintering furnace, controlling the sintering temperature to 1075 ℃, preserving heat for 4h, adjusting the primary tempering temperature to 910 ℃, preserving heat for 3h, and preserving heat for 4h at the secondary tempering temperature to 510 ℃ to prepare the required magnet material.
Comparative example 1
The preparation method of the neodymium iron boron magnet material is carried out according to the traditional process, and specifically comprises the following steps:
(1) the materials are mixed according to the same chemical formula as the example 1, the mixed materials are put into a 3kg rapid hardening furnace, and the vacuum degree is pumped to 10-2Introducing argon with the purity of 99.99 percent below Pa, opening the medium-frequency induction heating to melt the raw materials, and then casting at the rotating speed of 40-47r/min of a copper roller to obtain a cast sheet with the thickness of 2-5 mm; placing the prepared neodymium iron boron cast sheet in a hydrogen explosion furnace, vacuumizing, filling hydrogen, carrying out crystal fracture after the cast sheet absorbs hydrogen, reacting for 2-4h, and dehydrogenating at the temperature of 600 ℃ of 530-;
(2) adding a small amount of dispersant (the existing traditional dispersant is mainly a multi-element organic compound and is provided with a lipophilic group, namely C) into the prepared hydrogen explosion powder according to the traditional method of the prior art17H35Mainly containing a small amount of polar groups, and dispersing some of the polar groups by using alcohol and using kerosene), while the traditional adding mode is to add the mixture at the stages of jet mill grinding and powder mixing, wherein the adding amount accounts for 0.03 percent of the magnetic powder, the adding amount is small, particularly when two different magnetic powders are mixed, the mixture is not uniform, the dispersibility is poor, and the auxiliary alloy powder cannot be uniformly dispersed with the main powder, so that the performance of the magnet is unstable, therefore, in order to better separate the dispersing agent and the magnetic powder, a method of dispersing agent plus ultrasonic oscillation is adopted, the mixture is placed in a jet mill charging tank, and the rotating speed is 3500-;
(3) uniformly mixing the dispersed auxiliary alloy powder and the main alloy powder in a three-dimensional mixer, pressing the mixed alloy powder downwards in a 2T magnetic field direction, and carrying out isostatic pressing at 200-300 MPa;
(4) and (3) placing the prepared blank in a vacuum sintering furnace, controlling the sintering temperature to 1075 ℃, preserving heat for 4h, adjusting the primary tempering temperature to 910 ℃, preserving heat for 3h, and preserving heat for 4h at the secondary tempering temperature to 510 ℃ to prepare the required magnet material.
Comparative example 2
The preparation method of the neodymium iron boron magnet material is carried out according to the traditional process, and specifically comprises the following steps:
(1) the materials are mixed according to the same chemical formula as the example 2, the mixed materials are put into a 3kg rapid hardening furnace, and the vacuum degree is pumped to 10-2Introducing argon with the purity of 99.99 percent below Pa, opening the medium-frequency induction heating to melt the raw materials, and then casting at the rotating speed of 40-47r/min of a copper roller to obtain a cast sheet with the thickness of 2-5 mm; placing the prepared neodymium iron boron cast sheet in a hydrogen explosion furnace, vacuumizing, filling hydrogen, carrying out crystal fracture after the cast sheet absorbs hydrogen, reacting for 2-4h, and dehydrogenating at the temperature of 600 ℃ of 530-;
(2) adding a small amount of dispersant (the dispersant is selected and added in the same way as the comparative example 1) into the prepared hydrogen explosion powder according to the traditional method of the prior art, placing the hydrogen explosion powder into an airflow grinding material tank, and adjusting the rotating speed to 3500-;
(3) uniformly mixing the dispersed auxiliary alloy powder and the main alloy powder in a three-dimensional mixer, pressing the mixed alloy powder downwards in a 2T magnetic field direction, and carrying out isostatic pressing at 200-300 MPa;
(4) and (3) placing the prepared blank in a vacuum sintering furnace, controlling the sintering temperature to 1075 ℃, preserving heat for 4h, adjusting the primary tempering temperature to 910 ℃, preserving heat for 3h, and preserving heat for 4h at the secondary tempering temperature to 510 ℃ to prepare the required magnet material.
Comparative example 3
The preparation method of the neodymium iron boron magnet material is carried out according to the traditional process, and specifically comprises the following steps:
(1) the materials are mixed according to the same chemical formula as the example 3, the mixed materials are put into a 3kg rapid hardening furnace, and the vacuum degree is pumped to 10-2Introducing argon with purity of 99.99% below Pa, opening medium frequency induction heating to melt the raw materials, casting, and rotating at copper roller speed of 40-47r/min to obtainObtaining a casting sheet with the thickness of 2-5 mm; placing the prepared neodymium iron boron cast sheet in a hydrogen explosion furnace, vacuumizing, filling hydrogen, carrying out crystal fracture after the cast sheet absorbs hydrogen, reacting for 2-4h, and dehydrogenating at the temperature of 600 ℃ of 530-;
(2) adding a small amount of dispersant (the dispersant is selected and added in the same way as the comparative example 1) into the prepared hydrogen explosion powder according to the traditional method of the prior art, placing the hydrogen explosion powder into an airflow grinding material tank, and adjusting the rotating speed to 3500-;
(3) uniformly mixing the dispersed auxiliary alloy powder and the main alloy powder in a three-dimensional mixer, pressing the mixed alloy powder downwards in a 2T magnetic field direction, and carrying out isostatic pressing at 200-300 MPa;
(4) and (3) placing the prepared blank in a vacuum sintering furnace, controlling the sintering temperature to 1075 ℃, preserving heat for 4h, adjusting the primary tempering temperature to 910 ℃, preserving heat for 3h, and preserving heat for 4h at the secondary tempering temperature to 510 ℃ to prepare the required magnet material.
The sintered magnets of examples 1 to 3 and comparative examples 1 to 3 were cut into 10mm diameter and 10mm height cylinders, and the magnetic properties of the magnets were measured by a high temperature permanent magnet measuring instrument NIM-500C and recorded in table 1 below, and the fracture morphology diagrams of the magnet materials obtained in examples 1 and comparative examples 1 are shown in fig. 1 and 2, respectively.
TABLE 1 magnetic Performance results of sintered magnets
| Process for the preparation of a coating | Br(kGs) | Hcj(kOe) | (BH)max(MGOe) | Hk/Hcj |
| Example 1 | 12.98-13.21 | 16.85-17.25 | 40.65-42.10 | 0.95-0.98 |
| Example 2 | 12.85-12.91 | 18.55-19.35 | 39.15-41.05 | 0.92-0.95 |
| Example 3 | 12.74-12.83 | 20.55-21.55 | 37.15-38.25 | 0.88-0.92 |
| Comparative example 1 | 12.82-12.95 | 15.17-15.43 | 38.80-41.05 | 0.92-0.95 |
| Comparative example 2 | 12.71-12.82 | 16.47-17.23 | 37.80-39.05 | 0.91-0.93 |
| Comparative example 3 | 12.57-12.72 | 17.47-18.43 | 35.80-37.35 | 0.86-0.90 |
As can be seen from the fracture morphology graphs of the magnet material shown in the attached drawings 1 and 2, the magnet material prepared by the method has uniform and fine fracture crystal grains and does not have larger crystal grains; the fracture of the magnet material prepared by the traditional method in the prior art has large grains, and the grains are distributed more intensively.
Therefore, the preparation method of the neodymium iron boron magnet material can effectively improve the distribution uniformity of the alloy powder, is beneficial to refining crystal grains and optimizing the microstructure of the magnet, greatly reduces large crystal grains and irregular crystal grains, makes the crystal grains more compact and finer, and greatly improves the performance of the magnet.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.
Claims (5)
1. The preparation method of the neodymium iron boron magnet material is characterized by comprising the following steps:
(1) preparing materials according to the selected alloy components of the neodymium iron boron magnet material, and smelting and quickly solidifying to obtain an alloy thin strip; carrying out hydrogen explosion coarse crushing on the obtained alloy thin strip, then carrying out airflow fine grinding and crushing to obtain main alloy powder, and controlling the particle size of the main alloy powder to be 2-10 um;
(2) mixing selected auxiliary alloy powder with the particle size of 1-5um with dispersion liquid, and performing dispersion treatment in a nitrogen-containing micro-oxygen atmosphere under ultrasonic oscillation, wherein the oxygen content is controlled to be 200-500 ppm;
the dispersion comprises the following components in percentage by mass based on the total weight of the dispersion:
1-10 wt% of zinc stearate;
5-15 wt% of polyethylene glycol octane;
2-15 wt% of glycerol;
5-15 wt% of antistatic agent;
40-80 wt% of a solvent, wherein the solvent component comprises ethanol and/or methanol;
(3) mixing the dispersed auxiliary alloy powder with the main alloy powder, carrying out orientation compression on the mixed alloy powder under a magnetic field, and further densifying the mixed alloy powder through isostatic pressing to obtain a green body;
(4) and carrying out vacuum sintering heat treatment on the obtained green body to obtain the required neodymium iron boron magnet material.
2. The method for preparing the neodymium-iron-boron magnet material according to claim 1, wherein in the step (1), the neodymium-iron-boron magnet material has a structure shown in the following general formula: a (PrNd)aFe100-a-b-cBbMc；B:RExN100-x(ii) a Wherein, M element is selected from at least one of Co, Ti, Mo, Ga, Al, Cu, Zr, Ta and Nb element, RE element is selected from at least one of Dy, Tb, Nd, Pr and Ho element, and N element is selected from at least one of Cu, Ga, Al, Fe, Zn, Ni and Sn element;
the a, b, c and x satisfy the following relations: a is more than or equal to 28 and less than or equal to 33, b is more than or equal to 0.92 and less than or equal to 1.05, c is more than or equal to 0 and less than or equal to 3, and x is more than or equal to 50 and less than or equal to 100.
3. The method for preparing a neodymium-iron-boron magnet material according to claim 2, wherein in the step (2), the mass ratio of the auxiliary alloy powder to the dispersion liquid is 1: 4-7.
4. A method of manufacturing a neodymium iron boron magnet material according to any one of claims 1-3, characterized in that:
in the step (3), the magnetic field intensity of the orientation compression step is controlled to be 2-3T, and the pressure of the isostatic pressing step is controlled to be 200-300 MPa;
in the step (4), the vacuum sintering heat treatment specifically includes: placing the green body in a vacuum furnace and vacuumizing to less than 10 DEG C-2Heating the mixture pa, raising the temperature to 1040-.
5. The method of manufacturing a neodymium-iron-boron magnet material according to claim 1, wherein the antistatic agent comprises a T1502 antistatic agent.
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