CN115458317B - Anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity, preparation method and application thereof - Google Patents
Anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity, preparation method and application thereofInfo
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- CN115458317B CN115458317B CN202211213687.8A CN202211213687A CN115458317B CN 115458317 B CN115458317 B CN 115458317B CN 202211213687 A CN202211213687 A CN 202211213687A CN 115458317 B CN115458317 B CN 115458317B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
- H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
- H01F41/0266—Moulding; Pressing
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
- H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
- H01F1/047—Alloys characterised by their composition
- H01F1/053—Alloys characterised by their composition containing rare earth metals
- H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
- H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
- H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
- H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
- H01F1/0577—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together sintered
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Abstract
The invention relates to the technical field of rare earth permanent magnet materials, and provides an anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity, and a preparation method and application thereof. The permanent magnet material is prepared from 98-99.99% of alloy powder and 0.01-2% of diamond powder by mass percent. The diamond powder has the particle size of 5-1000 nm, has the characteristics of high melting point, high hardness, excellent heat conductivity, non-electric conduction and the like, is not easy to melt during hot pressing and thermal deformation, can be uniformly distributed at a magnetic powder interface, can effectively reduce the heat preservation time before deformation treatment, inhibit the growth of interface crystal grains and improve the magnetic resistivity, and is excellent in magnetic performance, and the permanent magnet material prepared by the method has the characteristics of high remanence, high coercivity and high resistivity, and can not seriously damage the remanence of a magnet while greatly improving the coercivity of the magnet by adding the nano diamond powder with specific content.
Description
Technical Field
The invention relates to the technical field of rare earth permanent magnet materials, in particular to an anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity, and a preparation method and application thereof.
Background
The RE-Fe-B permanent magnet material has wide application in the field of permanent magnet motors and the like due to excellent comprehensive hard magnetic performance. However, due to the fact that the conductivity is high, the Curie temperature is low, the absolute value of the coercivity temperature coefficient is high, eddy current loss can be generated in the service process of the permanent magnet motor, the temperature of the magnet is increased, a thermal demagnetizing effect is caused, and the service stability of the magnet is poor. The nanocrystalline rare earth permanent magnet material is superior to the traditional nanocrystalline rare earth permanent magnet material in temperature stability and fracture toughness, and is one of research hot spots of the current rare earth permanent magnet alloy material. The hot pressing/hot deformation process is one of the mainstream methods for preparing full density anisotropic nanocrystalline RE-Fe-B magnets. Because the Re 2Fe14 B crystal grain has Young modulus anisotropy, namely the Young modulus along the a and B axis directions is far greater than the Young modulus along the c axis direction, under the action of uniaxial pressure, the RE-Fe-B crystal realizes preferential growth orientation through crystal face sliding, crystal grain rotation and a 'dissolving-separating' mechanism, and forms a c axis orientation texture in a parallel pressure direction. The thermal deformation rare earth permanent magnetic material mainly comprises a Re 2Fe14 B main phase and an RE-rich phase, the magnetic performance of the thermal deformation magnet, especially the remanence and the magnetic energy product, is closely related to the orientation degree of main phase grains, the nonferromagnetic RE-rich phase not only provides an atomic diffusion channel and wets grain boundaries in the thermal deformation process, but also can reduce the exchange coupling among the main phase grains and improve the coercive force of the magnet. However, because the surface of the quick quenching magnetic powder is rough, the sheet magnetic powder is not fully contacted with each other, so that stress concentration exists at a contact interface, heat is easily accumulated at the magnetic powder interface at high temperature, coarse grains at the interface are abnormally grown, quasi-periodic coarse grains appear in the magnet, and the actual coercive force of the thermally deformed magnet is far lower than an expected value of a theoretical value.
In order to solve the problems of coarse local crystal grains, uneven microstructure and low coercivity in the magnet, the invention patent (CN 201610847457.5) discloses a method for inhibiting the coarse local crystal grains in the magnet and improving the microstructure uniformity of the thermally deformed magnet so as to improve the coercivity of the thermally deformed magnet by adding graphene, but the graphene has larger specific surface area and high surface energy, strong van der Waals force exists between sheets, so that the graphene is difficult to uniformly disperse, obvious agglomeration phenomenon occurs, the agglomerated graphene seriously worsens the magnetic performance of the magnet, and in addition, the graphene has high conductivity, the resistivity of the thermally deformed magnet is reduced after the graphene is added, the eddy current loss of the magnet is increased, and the service stability of the neodymium-iron-boron magnet is reduced. The invention patent (CN202010169811. X) discloses a method for improving the resistivity of a thermally deformed magnet by coating a nano inorganic insulating material, but the magnetic property of the magnet is remarkably reduced due to the introduction of a large amount of non-magnetic property phase. The invention patent (CN 110098026A) discloses a method for improving the strength and surface hardness of bonded rare earth permanent magnets by adding diamond, however, the bonded magnets have low magnetic performance due to serious magnetic dilution caused by adding excessive binder, and the application range of the bonded magnets is limited. In conclusion, the method has important significance in improving the microstructure of the nanocrystalline thermal deformation magnet and improving the magnetoelectric performance of the nanocrystalline thermal deformation magnet.
Disclosure of Invention
The invention aims to overcome the problems in the prior art and provides an anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity, and a preparation method and application thereof.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides an anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity, which is prepared from the following raw materials in percentage by mass:
98-99.99% of alloy powder and 0.01-2% of diamond powder.
Preferably, the alloy powder is Re xFe100-x-y-zTMyBz, re is one or more of La, ce, pr, nd, Y, dy and Tb, and TM is one or more of Co, zr, cr, V, nb, si, ti, mo, mn, W, ga, cu, al, zn;
wherein, the x is more than or equal to 26.0 and less than or equal to 36.0,0.14 and y is more than or equal to and z is more than or equal to 8.0,0.8 and less than or equal to 1.36.
Preferably, the particle size of the diamond powder is 5-1000 nm.
The invention also provides a preparation method of the anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity, which comprises the following steps:
(1) Mixing alloy powder and diamond powder, and then carrying out densification treatment to obtain an isotropic magnet;
(2) And carrying out thermal deformation orientation treatment on the isotropic magnet to obtain the anisotropic nanocrystalline rare earth permanent magnet material.
Preferably, the densification environment in the step (1) is a vacuum environment or an argon atmosphere, the vacuum degree of the vacuum environment is 1x 10 -2 Pa or more, the densification temperature is 400-750 ℃ or 20-30 ℃, the densification pressure is 100-700 MPa, and the densification time is 3-10 min.
Preferably, the environment of the thermal deformation orientation treatment in the step (2) is a vacuum environment or an argon atmosphere, the vacuum degree of the vacuum environment is more than or equal to 10Pa, the temperature of the thermal deformation orientation treatment is 650-850 ℃, the pressure of the thermal deformation orientation treatment is 20-250 MPa, and the speed of the thermal deformation orientation treatment is 0.01-0.5 mm/s.
Preferably, the thermal deformation orientation treatment in the step (2) is thermal deformation cake treatment or back extrusion ring treatment, and the deformation amount of the thermal deformation cake treatment is 30-80%.
Preferably, the pressure of the heat-deformed cake treatment in the step (2) is 20-250 MPa.
The invention also provides application of the anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity in the field of permanent magnet motors.
The beneficial effects of the invention are as follows:
1. The anisotropic nanocrystalline rare earth permanent magnet material prepared by the method has the advantages that the magnetic property is improved to a certain extent relative to alloy powder, and the coercivity of a magnet can be greatly improved and the residual magnetism of the magnet can not be seriously damaged by adding the nano diamond powder with specific mass fraction.
2. The nano diamond powder added by the invention has the characteristics of high melting point, high hardness, excellent thermal conductivity, non-electric conduction and the like. The high-melting-point high-hardness characteristic ensures that the nano diamond powder is not easy to melt in the hot pressing and thermal deformation processes, can be uniformly distributed on the contact interface of the quick quenching magnetic powder particles, can inhibit the formation of a coarse grain region and the growth of RE 2Fe14 B crystal grains, has excellent heat conduction property, ensures that the diamond powder is uniformly distributed on the magnetic powder interface, avoids local overheating caused by insufficient magnetic powder contact at high temperature, shortens the time required for the whole magnet to reach the set temperature, reduces the heat preservation time before deformation treatment, thereby achieving the purposes of inhibiting the whole crystal grain growth of the magnet and improving the comprehensive magnetic performance of the magnet, has the insulation characteristic that the diamond powder is uniformly distributed on the contact interface of the quick quenching magnetic powder particles, improves the resistivity of the magnet, and in addition, the grain refinement of the coarse grain region leads to the increase of the number of crystal boundaries, free electrons encounter the crystal defects to scatter in different directions, thereby reducing the electron conduction efficiency, and finally the magnetic performance and the resistivity of the magnet are simultaneously improved.
Drawings
FIG. 1 is a graph of the microscopic morphology of the nanodiamond powder of example 1;
FIG. 2 (a) is a microstructure of the anisotropic nanocrystalline rare earth permanent magnet material with a diamond addition of 0.1% prepared in example 1;
FIG. 2 (b) is a graph showing the distribution morphology of nanodiamond powder in the anisotropic nanocrystalline rare earth permanent magnet material with diamond addition of 0.1% prepared in example 1;
FIG. 3 (a) is a graph showing the fracture morphology of the anisotropic nanocrystalline rare earth permanent magnet material with diamond addition of 0 prepared in example 2;
Fig. 3 (b) is a fracture morphology diagram of the anisotropic nanocrystalline rare earth permanent magnet material with a diamond addition of 0.1% prepared in example 2.
Detailed Description
The invention provides an anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity, which is prepared from the following raw materials in percentage by mass:
98-99.99% of alloy powder and 0.01-2% of diamond powder.
In the invention, the mass fraction of the alloy powder is 98-99.99%, preferably 98.5-99.5%, and more preferably 98.8-99.2%.
In the present invention, the mass fraction of the diamond powder is 0.01 to 2%, preferably 0.5 to 1.5%, and more preferably 0.8 to 1.2%.
In the invention, the alloy powder is Re xFe100-x-y-zTMyBz, re is preferably one or more of La, ce, pr, nd, Y, dy and Tb, and TM is preferably one or more of Co, zr, cr, V, nb, si, ti, mo, mn, W, ga, cu, al, zn;
wherein, the x is more than or equal to 26.0 and less than or equal to 36.0,0.14 and y is more than or equal to and z is more than or equal to 8.0,0.8 and less than or equal to 1.36.
In the present invention, x is preferably 26.0≤x≤36.0, more preferably 28.0≤x≤34.0, still more preferably 30.0≤x≤32.0.
In the present invention, y is preferably 0.14≤y≤8.0, more preferably 2.0≤y≤6.0, and still more preferably 3.0≤y≤5.0.
In the present invention, z is preferably 0.8≤z≤1.36, more preferably 0.9≤z≤1.26, and still more preferably 1.0≤z≤1.16.
In the invention, the Re xFe100-x-y-zTMyBz alloy powder can be obtained through purchase or preparation.
The invention provides a preparation method of Re xFe100-x-y-zTMyBz alloy powder, which comprises the following steps:
(a) Smelting and pouring the raw materials in sequence to obtain an RE-Fe-B-TM alloy cast ingot;
(b) Removing surface oxide skin from RE-Fe-B-TM alloy cast ingot, and sequentially carrying out mechanical crushing and rapid quenching to obtain RE-Fe-B-TM rapid quenching belt;
(c) And mechanically crushing the RE-Fe-B-TM rapid quenching belt to obtain the Re xFe100-x-y-zTMyBz alloy powder.
In the invention, the smelting mode of the step (a) is preferably arc smelting or induction smelting, the smelting atmosphere is argon, and the smelting temperature is preferably 1200-1500 ℃, more preferably 1230-1400 ℃, and even more preferably 1250-1350 ℃.
In the invention, the fast quenching mode in the step (b) is preferably melt fast quenching or induction fast quenching, and the fast quenching speed is preferably 15-40 m/s, more preferably 20-35 m/s, and even more preferably 25-30 m/s.
In the present invention, the particle diameter of the diamond powder is preferably 5 to 1000nm, more preferably 50 to 800nm, and even more preferably 200 to 600nm.
In the invention, the rare earth permanent magnet material consists of a main phase Re 2Fe14 B, a rare earth-rich phase and nano diamond, wherein the main phase is a flaky grain, and the diamond is uniformly distributed at the magnetic powder interface.
The invention also provides a preparation method of the anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity, which comprises the following steps:
(1) Mixing alloy powder and diamond powder, and then carrying out densification treatment to obtain an isotropic magnet;
(2) And carrying out thermal deformation orientation treatment on the isotropic magnet to obtain the anisotropic nanocrystalline rare earth permanent magnet material.
In the invention, the mixing atmosphere in the step (1) is preferably argon, the mixing mode is preferably three-dimensional mixing or ball milling mixing, and the mixing time is preferably 1-3 h, more preferably 1.5-2.5 h, and even more preferably 1.8-2.2 h.
In the invention, the densification treatment environment in the step (1) is preferably a vacuum environment or an argon atmosphere, the vacuum degree of the vacuum environment is preferably 1×10 -2 Pa or more, more preferably 1.2×10× 10 -2 Pa or more, more preferably 1.5×10 -2 Pa or more, the densification treatment is cold press or hot press densification treatment, the temperature of the hot press densification treatment is preferably 400-750 ℃, more preferably 450-700 ℃, more preferably 500-650 ℃, and the temperature of the cold press densification treatment is preferably 20-30 ℃, more preferably 22-28 ℃, more preferably 24-26 ℃.
In the invention, the pressure of the densification is preferably 100-700 MPa, more preferably 200-600 MPa, more preferably 300-500 MPa, and the time of the densification is preferably 3-10 min, more preferably 4-9 min, more preferably 5-8 min.
In the present invention, the heat distortion orientation treatment environment in the step (2) is preferably a vacuum environment or an argon atmosphere, the vacuum degree of the vacuum environment is 10Pa or more, more preferably 12Pa or more, more preferably 15Pa or more, the temperature of the heat distortion orientation treatment is preferably 650-850 ℃, more preferably 700-800 ℃, more preferably 730-770 ℃, and the rate of the heat distortion orientation treatment is preferably 0.01-0.5 mm/s, more preferably 0.05-0.4 mm/s, more preferably 0.1-0.3 mm/s.
In the present invention, the heat distortion orientation treatment in the step (2) is a heat distortion cake treatment or a back extrusion ring treatment, and the deformation amount of the heat distortion cake treatment is preferably 30 to 80%, more preferably 50 to 75%, and even more preferably 60 to 70%.
In the present invention, the pressure of the heat-deformed cake treatment in the step (2) is preferably 20 to 250mpa, more preferably 50 to 200mpa, and even more preferably 100 to 150mpa.
In the present invention, the back extrusion ring process is to place the isotropic magnet in a mold of a specific size and to extrude under dynamic pressure.
In the present invention, the end pressure of the back extrusion ring treatment is preferably 50 to 300mpa, more preferably 70 to 250mpa, and even more preferably 100 to 200mpa.
In the present invention, the densification treatment in step (1) and the heat distortion orientation treatment in step (2) are performed in a discharge plasma sintering method or an induction heating sintering method.
The invention also provides application of the anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity in the field of permanent magnet motors.
The technical solutions provided by the present invention are described in detail below with reference to examples, but they should not be construed as limiting the scope of the present invention.
Example 1
Mixing Nd 29.89Fe62.62Co5.93Ga0.64B0.92 alloy powder and nano diamond powder with the particle size of 500nm, putting the mixture into a three-dimensional mixer, mixing the mixture for 2 hours under argon atmosphere to obtain uniform mixed magnetic powder, taking out the uniform mixed magnetic powder in a glove box protected by argon, putting the uniform mixed magnetic powder (wherein the nano diamond powder accounts for 0.1% of the mass fraction of the uniform mixed magnetic powder), putting the uniform mixed magnetic powder into a hot-pressing die prepared in advance, carrying out hot-pressing densification treatment for 5 minutes under 500 ℃ and 500MPa in the argon atmosphere to obtain an isotropic magnet, carrying out hot-deformation cake treatment on the magnet under 750 ℃ and 150MPa in the argon atmosphere, setting the temperature of the magnet to be 0.1mm/s, and obtaining the anisotropic nanocrystalline rare earth permanent magnet material with the diamond addition of 0.1% (the heating mode of densification treatment and hot-deformation cake treatment is a discharge plasma sintering mode).
And (3) keeping other conditions unchanged, and respectively setting the nano diamond powder to be 0, 0.2%, 0.3%, 0.4% and 2% of the uniformly mixed magnetic powder by mass percent to obtain the anisotropic nano-crystalline rare earth permanent magnet material with different diamond addition amounts (0, 0.2%, 0.3%, 0.4% and 2%).
The microstructure of the anisotropic nanocrystalline rare earth permanent magnet material with the diamond addition of 0.1% prepared in the embodiment is characterized to obtain a microstructure diagram of the anisotropic nanocrystalline rare earth permanent magnet material, as shown in fig. 2 (a), and a distribution morphology diagram of the nano diamond powder in the anisotropic nanocrystalline rare earth permanent magnet material, as shown in fig. 2 (b). It can be seen from fig. 2 (a) that the permanent magnet material is formed by stacking strip-shaped magnetic powder, part of rare earth-rich phases are distributed at the magnetic powder interface, and from fig. 2 (b), nano diamond particles are distributed at the strip interface, so that grain growth at the interface is inhibited.
The magnetic properties of the anisotropic nanocrystalline rare earth permanent magnet materials with diamond additions of 0, 0.1%, 0.2%, 0.3%, 0.4% and 2% in this example were respectively tested, and the obtained performance comparison results are shown in table 1.
Table 1 magnetic properties comparison results of permanent magnet materials with different diamond additions
It can be obtained from table 1 that the magnetic property and the resistivity of the anisotropic nanocrystalline rare earth permanent magnet material can be improved by adding a proper amount of nano diamond, and the resistivity of the permanent magnet material is obviously increased after more nano diamond is added.
Example 2
Mixing MM 29.6Fe62.6Co6.0Ga0.6Al0.2B1.0 alloy powder and nano diamond powder with the grain diameter of 600nm, putting the mixture into a three-dimensional mixer, mixing the mixture for 2.2 hours under argon atmosphere to obtain uniformly mixed magnetic powder, taking out the uniformly mixed magnetic powder in an argon-protected glove box (wherein the nano diamond powder accounts for 0.1% of the mass fraction of the uniformly mixed magnetic powder), putting the uniformly mixed magnetic powder into a hot-pressing die prepared in advance, carrying out hot-pressing densification treatment for 10 minutes under the temperature of 600 ℃ and 200MPa in the argon atmosphere to obtain an isotropic magnet, carrying out hot-deformation cake treatment on the magnet under the temperature of 700 ℃ and 120MPa in the argon atmosphere at the setting speed of 0.2MM/s, wherein the temperature rise mode of densification treatment and hot-deformation cake treatment is a discharge plasma sintering mode, and obtaining the anisotropic nanocrystalline rare earth permanent magnet material with the diamond addition of 0.1%.
Wherein, in the MM 29.6Fe62.6Co6.0Ga0.6Al0.2B1.0 quick quenching magnetic powder, MM is mixed rare earth and consists of 49.8wt% of Ce, 25wt% of Nd, 25wt% of Pr and 0.2wt% of Dy.
And keeping other conditions unchanged, and setting the mass fraction of nano diamond powder in the uniformly mixed magnetic powder to be 0 to obtain the anisotropic nanocrystalline rare earth permanent magnet material with the diamond addition of 0.
The fracture morphology of the anisotropic nanocrystalline rare earth permanent magnet material with the diamond addition of 0 and 0.1% obtained in this example was respectively characterized, and a fracture morphology diagram of the anisotropic nanocrystalline rare earth permanent magnet material with the diamond addition of 0 was obtained, as shown in fig. 3 (a), and a fracture morphology diagram of the anisotropic nanocrystalline rare earth permanent magnet material with the diamond addition of 0.1% was obtained, as shown in fig. 3 (b). The figure shows that the magnet without nano diamond has coarse grains and poor orientation, and the magnetic powder obtained after nano diamond is added has obviously reduced grain size at the contact interface, finer grains and more regular orientation, so that the magnet performance is obviously improved.
The anisotropic nanocrystalline rare earth permanent magnet materials of the present example, in which the diamond addition amounts were 0 and 0.1%, were respectively tested for magnetic properties, and the obtained performance comparison results are shown in table 2.
TABLE 2 magnetic properties comparison results of permanent magnet materials with diamond additions of 0 and 0.1%
Example 3
Mixing Ce 33Fe65.15Ga0.5B1.35 alloy powder with nano diamond powder with the grain size of 700nm, putting the mixture into a three-dimensional mixer, mixing the mixture for 1.9 hours under the argon atmosphere to obtain uniform mixed magnetic powder, taking out the uniform mixed magnetic powder in a glove box protected by argon, wherein the nano diamond powder accounts for 0.1 percent of the mass of the uniform mixed magnetic powder, putting the uniform mixed magnetic powder into a hot-pressing die which is prepared in advance, carrying out hot-pressing densification treatment for 5 minutes under the condition of the vacuum degree of 1.2 x 10 -2 Pa and the vacuum degree of 550 ℃ and 200MPa to obtain an isotropic magnet, carrying out hot-deformation cake treatment on the magnet under the condition of the vacuum degree of 12Pa and the conditions of 700 ℃ and 200MPa, setting the setting speed to be 0.3mm/s, and the deformation amount to be 65% (the heating mode of densification treatment and hot-deformation cake treatment is an induction heating sintering mode), thereby obtaining the anisotropic nano-crystal rare earth permanent magnet material with the diamond addition amount of 0.1 percent.
And keeping other conditions unchanged, and respectively setting the nano diamond powder to be 0, 0.4 percent and 0.8 percent of the mass fraction of the uniformly mixed magnetic powder to obtain the anisotropic nanocrystalline rare earth permanent magnet material with different diamond addition amounts (0, 0.4 percent and 0.8 percent).
The anisotropic nanocrystalline rare earth permanent magnet materials of the present example, in which the diamond addition amounts were 0, 0.1%, 0.4% and 0.8%, were respectively tested for magnetic properties, and the results of the performance comparisons obtained are shown in table 3.
Table 3 magnetic properties comparison results of permanent magnet materials with different diamond additions
Example 4
Mixing Nd 29.8Fe68.6Ga0.4Ti0.15Si0.1B0.95 alloy powder and nano diamond powder with the particle size of 650nm, putting the mixture into a three-dimensional mixer, mixing the mixture for 2 hours under the argon atmosphere to obtain uniform mixed magnetic powder, taking out the uniform mixed magnetic powder in a glove box protected by argon (wherein the nano diamond powder accounts for 0.5% of the mass fraction of the uniform mixed magnetic powder), putting the uniform mixed magnetic powder into a hot-pressing die prepared in advance, carrying out hot-pressing densification treatment for 4min under the conditions of 660 ℃ and 200MPa in the vacuum degree of 1.4 x 10 -2 Pa to obtain an isotropic magnet, putting the magnet into a back extrusion die in the vacuum degree of 14Pa to carry out back extrusion circular ring treatment at the setting speed of 0.2mm/s and the temperature of 850 ℃ and the ending pressure of 150MPa, wherein the heating mode of the densification treatment and the back extrusion circular ring treatment is an induction heating sintering mode, and the back extrusion magnetic ring with C-axis texture, wherein the diamond addition amount is 30mm, the inner diameter of 26mm and the wall thickness of 2mm is obtained.
And (3) keeping other conditions unchanged, setting the mass fraction of nano diamond powder in the uniformly mixed magnetic powder to be 0, and obtaining the back extrusion magnetic ring with the c-axis texture, wherein the outer diameter is 30mm, the inner diameter is 26mm, and the wall thickness is 2mm, and the diamond addition amount is 0.
The magnetic properties of the back-extrusion magnet rings with diamond additions of 0 and 0.5% in this example were respectively tested, and the obtained performance comparison results are shown in table 4.
TABLE 4 magnetic properties comparison results of back-extruded magnetic rings with diamond additions of 0 and 0.5%
Example 5
Mixing Nd 29.89Fe62.62Co5.93Ga0.64B0.92 alloy powder and nano diamond powder with the particle size of 450nm, putting the mixture into a three-dimensional mixer, mixing the mixture for 1.8 hours under argon atmosphere to obtain uniformly mixed magnetic powder, taking out the uniformly mixed magnetic powder in an argon-protected glove box (wherein the nano diamond powder accounts for 0.1% of the mass fraction of the uniformly mixed magnetic powder), putting the uniformly mixed magnetic powder into a cold pressing mold prepared in advance, carrying out cold pressing densification treatment for 10 minutes under the temperature of 25 ℃ and 350MPa in the argon atmosphere to obtain an isotropic magnet, carrying out hot deformation cake treatment on the magnet under the temperature of 710 ℃ and 170MPa in the argon atmosphere at the setting speed of 0.15mm/s, wherein the temperature rise mode of densification treatment and hot deformation cake treatment is a discharge plasma sintering mode, and obtaining the anisotropic nanocrystalline rare earth permanent magnet material with the diamond addition of 0.1%.
And keeping other conditions unchanged, and setting the mass fraction of nano diamond powder in the uniformly mixed magnetic powder to be 0 to obtain the anisotropic nanocrystalline rare earth permanent magnet material with the diamond addition of 0.
The anisotropic nanocrystalline rare earth permanent magnet materials of the present example, in which the diamond addition amounts were 0 and 0.1%, were respectively tested for magnetic properties, and the obtained performance comparison results are shown in table 5.
TABLE 5 magnetic properties comparison results of permanent magnet materials with diamond additions of 0 and 0.1%
According to the embodiment, the anisotropic nanocrystalline rare earth permanent magnet material prepared by the method has the advantages that the magnetic property is improved to a certain extent relative to alloy powder, and the coercivity of a magnet can be greatly improved and the residual magnetism of the magnet can not be seriously damaged by adding the nano diamond powder with specific mass fraction.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.
Claims (8)
1. The anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity is characterized by being prepared from the following raw materials in percentage by mass:
98-99.99% of alloy powder and 0.01-2% of diamond powder;
The rare earth permanent magnet material consists of a main phase Re 2Fe14 B, a rare earth-rich phase and nano diamond, wherein the main phase is a flaky grain, and the diamond is uniformly distributed at the magnetic powder interface;
The preparation method of the anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity comprises the following steps:
(1) Mixing alloy powder and diamond powder, and then carrying out densification treatment to obtain an isotropic magnet;
(2) Carrying out thermal deformation orientation treatment on the isotropic magnet to obtain the anisotropic nanocrystalline rare earth permanent magnet material;
The thermal deformation orientation treatment mode in the step (2) is thermal deformation cake treatment or back extrusion ring treatment, wherein the pressure of the thermal deformation cake treatment is 100-150 MPa, the back extrusion ring treatment is to place an isotropic magnet in a die with a specific size, extrusion is carried out under dynamic pressure, and the end pressure of the back extrusion ring treatment is 100-200 MPa.
2. The anisotropic nanocrystalline rare earth permanent magnet material according to claim 1, wherein the alloy powder is Re xFe100-x-y-zTMyBz, re is one or more of La, ce, pr, nd, Y, dy and Tb, and TM is one or more of Co, zr, cr, V, nb, si, ti, mo, mn, W, ga, cu, al, zn;
wherein, the x is more than or equal to 26.0 and less than or equal to 36.0,0.14 and y is more than or equal to and z is more than or equal to 8.0,0.8 and less than or equal to 1.36.
3. The anisotropic nanocrystalline rare earth permanent magnet material according to claim 1, wherein the diamond powder has a particle size of 5 to 1000nm.
4. The method for preparing the anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity according to any one of claims 1-3, which is characterized by comprising the following steps:
(1) Mixing alloy powder and diamond powder, and then carrying out densification treatment to obtain an isotropic magnet;
(2) Carrying out thermal deformation orientation treatment on the isotropic magnet to obtain the anisotropic nanocrystalline rare earth permanent magnet material;
The thermal deformation orientation treatment mode in the step (2) is thermal deformation cake treatment or back extrusion ring treatment, wherein the pressure of the thermal deformation cake treatment is 100-150 MPa, the back extrusion ring treatment is to place an isotropic magnet in a die with a specific size, extrusion is carried out under dynamic pressure, and the end pressure of the back extrusion ring treatment is 100-200 MPa.
5. The method according to claim 4, wherein the densification environment in the step (1) is a vacuum environment or an argon atmosphere, the vacuum degree of the vacuum environment is 1 x 10 -2 Pa or more, the densification temperature is 400-750 ℃ or 20-30 ℃, the densification pressure is 100-700 mpa, and the densification time is 3-10 min.
6. The method according to claim 4 or 5, wherein the heat distortion orientation treatment in the step (2) is performed in a vacuum atmosphere or an argon atmosphere, the vacuum degree of the vacuum atmosphere is 10Pa or more, the temperature of the heat distortion orientation treatment is 650-850 ℃, and the rate of the heat distortion orientation treatment is 0.01-0.5 mm/s.
7. The method according to claim 6, wherein the deformation amount of the thermally deformed cake in the step (2) is 30 to 80%.
8. The use of the anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity according to any one of claims 1-3 in the field of permanent magnet motors.
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