CN115410816A - Preparation method of modified neodymium iron boron magnetic powder - Google Patents
Preparation method of modified neodymium iron boron magnetic powder Download PDFInfo
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- CN115410816A CN115410816A CN202211235006.8A CN202211235006A CN115410816A CN 115410816 A CN115410816 A CN 115410816A CN 202211235006 A CN202211235006 A CN 202211235006A CN 115410816 A CN115410816 A CN 115410816A
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- QJVKUMXDEUEQLH-UHFFFAOYSA-N [B].[Fe].[Nd] Chemical class [B].[Fe].[Nd] QJVKUMXDEUEQLH-UHFFFAOYSA-N 0.000 title claims abstract description 174
- 239000006247 magnetic powder Substances 0.000 title claims abstract description 170
- 238000002360 preparation method Methods 0.000 title claims abstract description 13
- 239000002904 solvent Substances 0.000 claims abstract description 92
- 229910001172 neodymium magnet Inorganic materials 0.000 claims abstract description 81
- 238000006243 chemical reaction Methods 0.000 claims abstract description 47
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims abstract description 38
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 claims abstract description 38
- 235000011114 ammonium hydroxide Nutrition 0.000 claims abstract description 38
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 28
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims abstract description 28
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims abstract description 28
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 28
- 239000000178 monomer Substances 0.000 claims description 58
- 239000003607 modifier Substances 0.000 claims description 45
- 238000003756 stirring Methods 0.000 claims description 45
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical group CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 18
- 239000003960 organic solvent Substances 0.000 claims description 18
- 230000035484 reaction time Effects 0.000 claims description 18
- 239000007787 solid Substances 0.000 claims description 18
- 238000006116 polymerization reaction Methods 0.000 claims description 15
- 238000001132 ultrasonic dispersion Methods 0.000 claims description 12
- 239000006087 Silane Coupling Agent Substances 0.000 claims description 9
- 239000012298 atmosphere Substances 0.000 claims description 9
- 239000011203 carbon fibre reinforced carbon Substances 0.000 claims description 9
- 239000011247 coating layer Substances 0.000 claims description 9
- 239000003999 initiator Substances 0.000 claims description 9
- 230000001681 protective effect Effects 0.000 claims description 9
- 239000000126 substance Substances 0.000 claims description 9
- 238000000034 method Methods 0.000 claims description 8
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims description 7
- 125000003118 aryl group Chemical group 0.000 claims description 6
- 230000005347 demagnetization Effects 0.000 abstract description 12
- 238000012986 modification Methods 0.000 abstract description 6
- 230000004048 modification Effects 0.000 abstract description 6
- 230000005389 magnetism Effects 0.000 abstract description 3
- 238000007796 conventional method Methods 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 3
- 230000000379 polymerizing effect Effects 0.000 description 3
- 239000000696 magnetic material Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000005672 electromagnetic field Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 150000002910 rare earth metals Chemical class 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Classifications
-
- 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
-
- 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
- H01F1/0572—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 with a protective layer
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Hard Magnetic Materials (AREA)
Abstract
The invention discloses a preparation method of modified neodymium iron boron magnetic powder, which comprises the following steps: (1) Dispersing the first nanometer neodymium iron boron magnetic powder, the nanometer silver powder and the nanometer aluminum powder in a first solvent, adding first concentrated ammonia water and first tetraethyl orthosilicate for reaction to obtain first modified neodymium iron boron magnetic powder; (2) Dispersing the second nanometer neodymium-iron-boron magnetic powder, the nanometer zinc powder and the nanometer copper powder in a second solvent, adding second concentrated ammonia water and second tetraethyl orthosilicate for reaction to obtain second modified neodymium-iron-boron magnetic powder; the first modified neodymium iron boron magnetic powder and the second modified neodymium iron boron magnetic powder are prepared firstly, then the first modified neodymium iron boron magnetic powder and the second modified neodymium iron boron magnetic powder are mixed for secondary modification, and the two modifications are organically combined, so that the prepared permanent magnet has larger residual magnetism and magnetic energy product, the coercive force is effectively improved, the demagnetization rate is greatly reduced, and the use requirement is met.
Description
Technical Field
The invention relates to the technical field of neodymium iron boron magnetic powder, in particular to a preparation method of modified neodymium iron boron magnetic powder.
Background
The magnets for the motor directly affect the life, reliability and durability of the motor. The main raw material of the magnet for the motor is generally permanent magnetic ferrite, and rare earth permanent magnetic materials are also used. The basic performance of permanent magnets for automotive motors is mainly expressed in two indexes. One is the product of magnetic energy (BH) max And the other is the intrinsic coercivity (Hcj). With the development of science and technology in the field of magnetic material application, the performance requirements of high-performance industrial motors are further improved. Industrial motors not only require high magnetic energy products, but also have high intrinsic coercivity to suppress demagnetization from opposing electromagnetic fields due to temperature changes and large current surges. Therefore, it is an important problem to ensure the stability and reliability of the industrial motor during long-term use.
The permanent magnet for the current industrial motor is mainly made of neodymium iron boron magnetic powder which is not modified usually, so that the manufactured permanent magnet has small remanence and magnetic energy product, low coercive force and large demagnetization rate, and cannot meet the use requirement. Therefore, there is a need to develop a solution to the above problems.
Disclosure of Invention
In view of the above, the present invention is directed to a method for preparing a modified ndfeb magnetic powder, which can increase the remanence and magnetic energy product of a permanent magnet, increase the coercivity, and reduce the demagnetization rate.
In order to achieve the purpose, the invention adopts the following technical scheme:
a preparation method of modified neodymium iron boron magnetic powder comprises the following steps:
(1) Dispersing the first nanometer neodymium iron boron magnetic powder, the nanometer silver powder and the nanometer aluminum powder in a first solvent, and adding first concentrated ammonia water and first tetraethyl orthosilicate for reaction to obtain first modified neodymium iron boron magnetic powder;
(2) Dispersing the second nanometer neodymium-iron-boron magnetic powder, the nanometer zinc powder and the nanometer copper powder in a second solvent, adding second concentrated ammonia water and second tetraethyl orthosilicate for reaction to obtain second modified neodymium-iron-boron magnetic powder;
(3) Adding the first modified neodymium iron boron magnetic powder prepared in the step (1) and the second modified neodymium iron boron magnetic powder prepared in the step (2) into an organic solvent medium containing a modifier, and ultrasonically dispersing and stirring to connect the modifier with the first modified neodymium iron boron magnetic powder and the second modified neodymium iron boron magnetic powder through chemical bonds;
(4) And further adding an unsaturated monomer and an initiator, performing ultrasonic dispersion and stirring to enable the unsaturated monomer and the modifier to perform a grafting reaction, and enabling the unsaturated monomer to perform a polymerization reaction to form a coating layer, thereby obtaining a finished product.
Preferably, the first nano neodymium iron boron magnetic powder is 50 parts by weight, the nano silver powder is 1-2 parts by weight, the nano aluminum powder is 0.5-1 part by weight, the first solvent is absolute ethyl alcohol, and the solid content of the first nano neodymium iron boron magnetic powder, the nano silver powder and the nano aluminum powder in the first solvent is 0.8-1 g/ml; the adding amount of the first strong ammonia water is 8-10% of the volume of the first solvent; the adding amount of the first tetraethyl orthosilicate is 4-5% of the volume of the first solvent; the reaction temperature is 35-40 ℃, and the reaction time is 5-10 h.
Preferably, the second nano neodymium iron boron magnetic powder is 50 parts by weight, the nano zinc powder is 1-2 parts by weight, the nano copper powder is 0.5-1 part by weight, the second solvent is absolute ethyl alcohol, and the solid content of the second nano neodymium iron boron magnetic powder, the nano zinc powder and the nano copper powder in the second solvent is 0.8-1 g/ml; the adding amount of the second stronger ammonia water is 8-10% of the volume of the second solvent; the adding amount of the second tetraethyl orthosilicate is 4-5% of the volume of the second solvent; the reaction temperature is 35-40 ℃, and the reaction time is 5-10 h.
Preferably, the modifier is a silane coupling agent containing carbon-carbon double bonds, the volume ratio of the mass of the magnetic powder to the organic solvent is 50-55 g/100ml, and the concentration of the modifier is 4-5 wt%.
Preferably, the unsaturated monomer is at least one of an acrylic unsaturated monomer and an aromatic unsaturated monomer, and the mass ratio of the unsaturated monomer to the magnetic powder is 6-8.
Preferably, the stirring speed in the step (3) is 400-500 r/min, and the stirring time is 15-20min.
Preferably, in the step (4), the stirring speed is 80-90 r/min, the temperature is raised to 70-75 ℃, and the polymerization reaction is carried out for 4-5 h under the protective atmosphere.
Compared with the prior art, the invention has obvious advantages and beneficial effects, and specifically, the technical scheme includes that:
the first modified neodymium iron boron magnetic powder and the second modified neodymium iron boron magnetic powder are prepared firstly, then the first modified neodymium iron boron magnetic powder and the second modified neodymium iron boron magnetic powder are mixed for secondary modification, and the two modifications are organically combined, so that the prepared permanent magnet has larger residual magnetism and magnetic energy product, the coercive force is effectively improved, the demagnetization rate is greatly reduced, and the use requirement is met.
Detailed Description
The invention discloses a preparation method of modified neodymium iron boron magnetic powder, which comprises the following steps:
(1) Dispersing the first nanometer neodymium iron boron magnetic powder, the nanometer silver powder and the nanometer aluminum powder in a first solvent, adding first concentrated ammonia water and first tetraethyl orthosilicate for reaction to obtain first modified neodymium iron boron magnetic powder; the first nanometer neodymium iron boron magnetic powder is 50 parts by weight, the nanometer silver powder is 1-2 parts by weight, the nanometer aluminum powder is 0.5-1 part by weight, the first solvent is absolute ethyl alcohol, and the solid content of the first nanometer neodymium iron boron magnetic powder, the nanometer silver powder and the nanometer aluminum powder in the first solvent is 0.8-1 g/ml; the adding amount of the first strong ammonia water is 8-10% of the volume of the first solvent; the adding amount of the first tetraethyl orthosilicate is 4-5% of the volume of the first solvent; the reaction temperature is 35-40 ℃, and the reaction time is 5-10 h.
(2) Dispersing the second nanometer neodymium-iron-boron magnetic powder, the nanometer zinc powder and the nanometer copper powder in a second solvent, adding second concentrated ammonia water and second tetraethyl orthosilicate for reaction to obtain second modified neodymium-iron-boron magnetic powder; the second nanometer neodymium iron boron magnetic powder is 50 parts by weight, the nanometer zinc powder is 1-2 parts by weight, the nanometer copper powder is 0.5-1 part by weight, the second solvent is absolute ethyl alcohol, and the solid content of the second nanometer neodymium iron boron magnetic powder, the nanometer zinc powder and the nanometer copper powder in the second solvent is 0.8-1 g/ml; the adding amount of the second strong ammonia water is 8-10% of the volume of the second solvent; the adding amount of the second tetraethyl orthosilicate is 4-5% of the volume of the second solvent; the reaction temperature is 35-40 ℃, and the reaction time is 5-10 h.
(3) Adding the first modified neodymium iron boron magnetic powder prepared in the step (1) and the second modified neodymium iron boron magnetic powder prepared in the step (2) into an organic solvent medium containing a modifier, and ultrasonically dispersing and stirring to connect the modifier with the first modified neodymium iron boron magnetic powder and the second modified neodymium iron boron magnetic powder through chemical bonds; the modifier is a silane coupling agent containing carbon-carbon double bonds, the volume ratio of the mass of the magnetic powder to the organic solvent is 50-55 g/100ml, and the concentration of the modifier is 4-5 wt%. The stirring speed is 400-500 r/min, and the stirring time is 15-20min.
(4) And further adding an unsaturated monomer and an initiator, performing ultrasonic dispersion and stirring to enable the unsaturated monomer and the modifier to perform a grafting reaction, and enabling the unsaturated monomer to perform a polymerization reaction to form a coating layer, thereby obtaining a finished product. The unsaturated monomer is at least one of acrylic unsaturated monomer and aromatic unsaturated monomer, and the mass ratio of the unsaturated monomer to the magnetic powder is 6-8. The stirring speed is 80-90 r/min, the temperature is raised to 70-75 ℃, and the polymerization reaction is carried out for 4-5 h under the protective atmosphere.
The invention is illustrated in more detail below in the following examples:
example 1:
a preparation method of modified neodymium iron boron magnetic powder comprises the following steps:
(1) Dispersing the first nanometer neodymium iron boron magnetic powder, the nanometer silver powder and the nanometer aluminum powder in a first solvent, and adding first concentrated ammonia water and first tetraethyl orthosilicate for reaction to obtain first modified neodymium iron boron magnetic powder; the first nanometer neodymium iron boron magnetic powder is 50 parts by weight, the nanometer silver powder is 1 part by weight, the nanometer aluminum powder is 0.6 part by weight, the first solvent is absolute ethyl alcohol, and the solid content of the first nanometer neodymium iron boron magnetic powder, the nanometer silver powder and the nanometer aluminum powder in the first solvent is 0.88g/ml; the adding amount of the first strong ammonia water is 8.5 percent of the volume of the first solvent; the adding amount of the first tetraethyl orthosilicate is 4.2 percent of the volume of the first solvent; the reaction temperature is 36 ℃, and the reaction time is 6h.
(2) Dispersing the second nanometer neodymium-iron-boron magnetic powder, the nanometer zinc powder and the nanometer copper powder in a second solvent, adding second concentrated ammonia water and second tetraethyl orthosilicate for reaction to obtain second modified neodymium-iron-boron magnetic powder; the second nanometer neodymium iron boron magnetic powder is 50 parts by weight, the nanometer zinc powder is 1.5 parts by weight, the nanometer copper powder is 0.8 part by weight, the second solvent is absolute ethyl alcohol, and the solid content of the second nanometer neodymium iron boron magnetic powder, the nanometer zinc powder and the nanometer copper powder in the second solvent is 0.82g/ml; the adding amount of the second stronger ammonia water is 8.1 percent of the volume of the second solvent; the adding amount of the second tetraethyl orthosilicate is 4.5 percent of the volume of the second solvent; the reaction temperature is 35 ℃ and the reaction time is 7h.
(3) Adding the first modified neodymium iron boron magnetic powder prepared in the step (1) and the second modified neodymium iron boron magnetic powder prepared in the step (2) into an organic solvent medium containing a modifier, and ultrasonically dispersing and stirring to connect the modifier with the first modified neodymium iron boron magnetic powder and the second modified neodymium iron boron magnetic powder through chemical bonds; the modifier is a silane coupling agent containing carbon-carbon double bonds, the volume ratio of the mass of the magnetic powder to the organic solvent is 52g/100ml, and the concentration of the modifier is 4.5wt%. The stirring speed is 400r/min, and the stirring time is 17min.
(4) And further adding an unsaturated monomer and an initiator, performing ultrasonic dispersion and stirring to enable the unsaturated monomer and the modifier to perform a grafting reaction, and enabling the unsaturated monomer to perform a polymerization reaction to form a coating layer, thereby obtaining a finished product. The unsaturated monomer is an acrylic unsaturated monomer, and the mass ratio of the unsaturated monomer to the magnetic powder is 6. Stirring at 81r/min, heating to 75 deg.C, and polymerizing under protective atmosphere for 4h.
The neodymium iron boron permanent magnet is prepared from the modified neodymium iron boron magnetic powder prepared by the embodiment by adopting a conventional method, through tests, the remanence of the prepared neodymium iron boron permanent magnet is 20.4kGs, the magnetic energy product is 61MGOe, the coercive force is 51000Oe, and the high-temperature demagnetization rate of the neodymium iron boron permanent magnet is 0.03% after the neodymium iron boron permanent magnet is placed at 200 ℃ for 1 hour.
Example 2:
a preparation method of modified neodymium iron boron magnetic powder comprises the following steps:
(1) Dispersing the first nanometer neodymium iron boron magnetic powder, the nanometer silver powder and the nanometer aluminum powder in a first solvent, and adding first concentrated ammonia water and first tetraethyl orthosilicate for reaction to obtain first modified neodymium iron boron magnetic powder; the first nanometer neodymium iron boron magnetic powder is 50 parts by weight, the nanometer silver powder is 2 parts by weight, the nanometer aluminum powder is 0.8 part by weight, the first solvent is absolute ethyl alcohol, and the solid content of the first nanometer neodymium iron boron magnetic powder, the nanometer silver powder and the nanometer aluminum powder in the first solvent is 0.8g/ml; the adding amount of the first concentrated ammonia water is 9 percent of the volume of the first solvent; the adding amount of the first tetraethyl orthosilicate is 4.5 percent of the volume of the first solvent; the reaction temperature is 35 ℃ and the reaction time is 7h.
(2) Dispersing the second nanometer neodymium-iron-boron magnetic powder, the nanometer zinc powder and the nanometer copper powder in a second solvent, adding second concentrated ammonia water and second tetraethyl orthosilicate for reaction to obtain second modified neodymium-iron-boron magnetic powder; the second nanometer neodymium iron boron magnetic powder is 50 parts by weight, the nanometer zinc powder is 1 part by weight, the nanometer copper powder is 0.5 part by weight, the second solvent is absolute ethyl alcohol, and the solid content of the second nanometer neodymium iron boron magnetic powder, the nanometer zinc powder and the nanometer copper powder in the second solvent is 0.91g/ml; the adding amount of the second stronger ammonia water is 8 percent of the volume of the second solvent; the adding amount of the second tetraethyl orthosilicate is 4.8 percent of the volume of the second solvent; the reaction temperature is 37 ℃ and the reaction time is 8h.
(3) Adding the first modified neodymium iron boron magnetic powder prepared in the step (1) and the second modified neodymium iron boron magnetic powder prepared in the step (2) into an organic solvent medium containing a modifier, and ultrasonically dispersing and stirring to connect the modifier with the first modified neodymium iron boron magnetic powder and the second modified neodymium iron boron magnetic powder through chemical bonds; the modifier is a silane coupling agent containing carbon-carbon double bonds, the volume ratio of the mass of the magnetic powder to the organic solvent is 50g/100ml, and the concentration of the modifier is 4wt%. The stirring speed is 430r/min, and the stirring time is 15min.
(4) And further adding an unsaturated monomer and an initiator, performing ultrasonic dispersion and stirring to enable the unsaturated monomer and the modifier to perform a grafting reaction, and enabling the unsaturated monomer to perform a polymerization reaction to form a coating layer, thereby obtaining a finished product. The unsaturated monomer is an aromatic unsaturated monomer, and the mass ratio of the unsaturated monomer to the magnetic powder is 6.5. Stirring at 85r/min, heating to 70 deg.C, and polymerizing under protective atmosphere for 4.5h.
The neodymium iron boron permanent magnet is prepared from the modified neodymium iron boron magnetic powder prepared by the embodiment by adopting a conventional method, through tests, the remanence of the prepared neodymium iron boron permanent magnet is 19.4kGs, the magnetic energy product is 59MGOe, the coercive force is 49050Oe, and the high-temperature demagnetization rate of the neodymium iron boron permanent magnet is 0.04% after the neodymium iron boron permanent magnet is placed at 200 ℃ for 1 hour.
Example 3:
a preparation method of modified neodymium iron boron magnetic powder comprises the following steps:
(1) Dispersing the first nanometer neodymium iron boron magnetic powder, the nanometer silver powder and the nanometer aluminum powder in a first solvent, adding first concentrated ammonia water and first tetraethyl orthosilicate for reaction to obtain first modified neodymium iron boron magnetic powder; the first nanometer neodymium iron boron magnetic powder is 50 parts by weight, the nanometer silver powder is 1.5 parts by weight, the nanometer aluminum powder is 1 part by weight, the first solvent is absolute ethyl alcohol, and the solid content of the first nanometer neodymium iron boron magnetic powder, the nanometer silver powder and the nanometer aluminum powder in the first solvent is 0.85g/ml; the adding amount of the first strong ammonia water is 8 percent of the volume of the first solvent; the adding amount of the first tetraethyl orthosilicate is 4% of the volume of the first solvent; the reaction temperature is 37 ℃ and the reaction time is 5h.
(2) Dispersing the second nanometer neodymium-iron-boron magnetic powder, the nanometer zinc powder and the nanometer copper powder in a second solvent, adding second concentrated ammonia water and second tetraethyl orthosilicate for reaction to obtain second modified neodymium-iron-boron magnetic powder; the second nanometer neodymium iron boron magnetic powder is 50 parts by weight, the nanometer zinc powder is 2 parts by weight, the nanometer copper powder is 0.7 part by weight, the second solvent is absolute ethyl alcohol, and the solid content of the second nanometer neodymium iron boron magnetic powder, the nanometer zinc powder and the nanometer copper powder in the second solvent is 0.8g/ml; the adding amount of the second stronger ammonia water is 9 percent of the volume of the second solvent; the adding amount of the second tetraethyl orthosilicate is 4% of the volume of the second solvent; the reaction temperature was 39 ℃ and the reaction time was 10h.
(3) Adding the first modified neodymium iron boron magnetic powder prepared in the step (1) and the second modified neodymium iron boron magnetic powder prepared in the step (2) into an organic solvent medium containing a modifier, and ultrasonically dispersing and stirring to connect the modifier with the first modified neodymium iron boron magnetic powder and the second modified neodymium iron boron magnetic powder through chemical bonds; the modifier is a silane coupling agent containing carbon-carbon double bonds, the volume ratio of the mass of the magnetic powder to the organic solvent is 54g/100ml, and the concentration of the modifier is 5wt%. The stirring speed is 500r/min, and the stirring time is 18min.
(4) And further adding an unsaturated monomer and an initiator, performing ultrasonic dispersion and stirring to enable the unsaturated monomer and the modifier to perform a grafting reaction, and enabling the unsaturated monomer to perform a polymerization reaction to form a coating layer, thereby obtaining a finished product. The unsaturated monomer is a mixture of acrylic unsaturated monomer and aromatic unsaturated monomer, and the mass ratio of the unsaturated monomer to the magnetic powder is 7. The stirring speed is 90r/min, the temperature is raised to 71 ℃, and the polymerization reaction is carried out for 4.3h under the protective atmosphere.
The neodymium iron boron permanent magnet is prepared from the modified neodymium iron boron magnetic powder prepared by the embodiment by adopting a conventional method, through tests, the remanence of the prepared neodymium iron boron permanent magnet is 20.1kGs, the magnetic energy product is 58MGOe, the coercive force is 48500Oe, and the high-temperature demagnetization rate is 0.04% after the neodymium iron boron permanent magnet is placed at 200 ℃ for 1 hour.
Example 4:
a preparation method of modified neodymium iron boron magnetic powder comprises the following steps:
(1) Dispersing the first nanometer neodymium iron boron magnetic powder, the nanometer silver powder and the nanometer aluminum powder in a first solvent, adding first concentrated ammonia water and first tetraethyl orthosilicate for reaction to obtain first modified neodymium iron boron magnetic powder; the first nanometer neodymium iron boron magnetic powder is 50 parts by weight, the nanometer silver powder is 1.6 parts by weight, the nanometer aluminum powder is 0.7 part by weight, the first solvent is absolute ethyl alcohol, and the solid content of the first nanometer neodymium iron boron magnetic powder, the nanometer silver powder and the nanometer aluminum powder in the first solvent is 0.9g/ml; the adding amount of the first strong ammonia water is 10 percent of the volume of the first solvent; the adding amount of the first tetraethyl orthosilicate is 5% of the volume of the first solvent; the reaction temperature is 38 ℃, and the reaction time is 10h.
(2) Dispersing the second nanometer neodymium-iron-boron magnetic powder, the nanometer zinc powder and the nanometer copper powder in a second solvent, adding second concentrated ammonia water and second tetraethyl orthosilicate for reaction to obtain second modified neodymium-iron-boron magnetic powder; the second nanometer neodymium iron boron magnetic powder is 50 parts by weight, the nanometer zinc powder is 1.6 parts by weight, the nanometer copper powder is 0.9 part by weight, the second solvent is absolute ethyl alcohol, and the solid content of the second nanometer neodymium iron boron magnetic powder, the nanometer zinc powder and the nanometer copper powder in the second solvent is 1g/ml; the adding amount of the second stronger ammonia water is 10 percent of the volume of the second solvent; the adding amount of the second tetraethyl orthosilicate is 5% of the volume of the second solvent; the reaction temperature is 40 ℃, and the reaction time is 5h.
(3) Adding the first modified neodymium iron boron magnetic powder prepared in the step (1) and the second modified neodymium iron boron magnetic powder prepared in the step (2) into an organic solvent medium containing a modifier, and performing ultrasonic dispersion and stirring to connect the modifier with the first modified neodymium iron boron magnetic powder and the second modified neodymium iron boron magnetic powder through chemical bonds; the modifier is a silane coupling agent containing carbon-carbon double bonds, the volume ratio of the mass of the magnetic powder to the organic solvent is 55g/100ml, and the concentration of the modifier is 4.3wt%. The stirring speed is 480r/min, and the stirring time is 19min.
(4) And further adding an unsaturated monomer and an initiator, performing ultrasonic dispersion and stirring to enable the unsaturated monomer and the modifier to perform a grafting reaction, and enabling the unsaturated monomer to perform a polymerization reaction to form a coating layer, thereby obtaining a finished product. The unsaturated monomer is an acrylic unsaturated monomer, and the mass ratio of the unsaturated monomer to the magnetic powder is 7.8. Stirring at 80r/min, heating to 73 deg.C, and polymerizing under protective atmosphere for 5h.
The neodymium iron boron permanent magnet is prepared from the modified neodymium iron boron magnetic powder prepared by the embodiment by adopting a conventional method, through tests, the remanence of the prepared neodymium iron boron permanent magnet is 19.5kGs, the magnetic energy product is 60MGOe, the coercive force is 49000Oe, and the high-temperature demagnetization rate of the neodymium iron boron permanent magnet is 0.05% after the neodymium iron boron permanent magnet is placed at 200 ℃ for 1 hour.
Example 5:
a preparation method of modified neodymium iron boron magnetic powder comprises the following steps:
(1) Dispersing the first nanometer neodymium iron boron magnetic powder, the nanometer silver powder and the nanometer aluminum powder in a first solvent, adding first concentrated ammonia water and first tetraethyl orthosilicate for reaction to obtain first modified neodymium iron boron magnetic powder; the first nanometer neodymium iron boron magnetic powder is 50 parts by weight, the nanometer silver powder is 1.8 parts by weight, the nanometer aluminum powder is 0.9 part by weight, the first solvent is absolute ethyl alcohol, and the solid content of the first nanometer neodymium iron boron magnetic powder, the nanometer silver powder and the nanometer aluminum powder in the first solvent is 1g/ml; the adding amount of the first concentrated ammonia water is 9.5 percent of the volume of the first solvent; the adding amount of the first tetraethyl orthosilicate is 4.8 percent of the volume of the first solvent; the reaction temperature is 40 ℃, and the reaction time is 8h.
(2) Dispersing the second nanometer neodymium-iron-boron magnetic powder, the nanometer zinc powder and the nanometer copper powder in a second solvent, adding second concentrated ammonia water and second tetraethyl orthosilicate for reaction to obtain second modified neodymium-iron-boron magnetic powder; the second nanometer neodymium iron boron magnetic powder is 50 parts by weight, the nanometer zinc powder is 1.8 parts by weight, the nanometer copper powder is 1 part by weight, the second solvent is absolute ethyl alcohol, and the solid content of the second nanometer neodymium iron boron magnetic powder, the nanometer zinc powder and the nanometer copper powder in the second solvent is 0.85g/ml; the adding amount of the second stronger ammonia water is 8.8 percent of the volume of the second solvent; the adding amount of the second tetraethyl orthosilicate is 4.3 percent of the volume of the second solvent; the reaction temperature is 36 ℃, and the reaction time is 6h.
(3) Adding the first modified neodymium iron boron magnetic powder prepared in the step (1) and the second modified neodymium iron boron magnetic powder prepared in the step (2) into an organic solvent medium containing a modifier, and performing ultrasonic dispersion and stirring to connect the modifier with the first modified neodymium iron boron magnetic powder and the second modified neodymium iron boron magnetic powder through chemical bonds; the modifier is a silane coupling agent containing carbon-carbon double bonds, the volume ratio of the mass of the magnetic powder to the organic solvent is 53g/100ml, and the concentration of the modifier is 4.8wt%. The stirring speed is 460r/min, and the stirring time is 20min.
(4) And further adding an unsaturated monomer and an initiator, performing ultrasonic dispersion and stirring to enable the unsaturated monomer and the modifier to perform a grafting reaction, and enabling the unsaturated monomer to perform a polymerization reaction to form a coating layer, thereby obtaining a finished product. The unsaturated monomer is an aromatic unsaturated monomer, and the mass ratio of the unsaturated monomer to the magnetic powder is 8. The stirring speed is 86r/min, the temperature is raised to 72 ℃, and the polymerization reaction is carried out for 4.5h under the protective atmosphere.
The neodymium iron boron permanent magnet is prepared from the modified neodymium iron boron magnetic powder prepared by the embodiment by adopting a conventional method, through tests, the remanence of the prepared neodymium iron boron permanent magnet is 19.8kGs, the magnetic energy product is 58MGOe, the coercive force is 47800Oe, and the high-temperature demagnetization rate of the neodymium iron boron permanent magnet is 0.05% after the neodymium iron boron permanent magnet is placed at 200 ℃ for 1 hour.
Example 6:
a preparation method of modified neodymium iron boron magnetic powder comprises the following steps:
(1) Dispersing the first nanometer neodymium iron boron magnetic powder, the nanometer silver powder and the nanometer aluminum powder in a first solvent, and adding first concentrated ammonia water and first tetraethyl orthosilicate for reaction to obtain first modified neodymium iron boron magnetic powder; the first nanometer neodymium iron boron magnetic powder is 50 parts by weight, the nanometer silver powder is 1.3 parts by weight, the nanometer aluminum powder is 0.5 part by weight, the first solvent is absolute ethyl alcohol, and the solid content of the first nanometer neodymium iron boron magnetic powder, the nanometer silver powder and the nanometer aluminum powder in the first solvent is 0.95g/ml; the adding amount of the first concentrated ammonia water is 9.8 percent of the volume of the first solvent; the adding amount of the first tetraethyl orthosilicate is 4.4% of the volume of the first solvent; the reaction temperature was 39 ℃ and the reaction time was 9h.
(2) Dispersing the second nanometer neodymium-iron-boron magnetic powder, the nanometer zinc powder and the nanometer copper powder in a second solvent, adding second concentrated ammonia water and second tetraethyl orthosilicate for reaction to obtain second modified neodymium-iron-boron magnetic powder; the second nanometer neodymium iron boron magnetic powder is 50 parts by weight, the nanometer zinc powder is 1.7 parts by weight, the nanometer copper powder is 0.6 part by weight, the second solvent is absolute ethyl alcohol, and the solid content of the second nanometer neodymium iron boron magnetic powder, the nanometer zinc powder and the nanometer copper powder in the second solvent is 0.95g/ml; the adding amount of the second stronger ammonia water is 9.5 percent of the volume of the second solvent; the adding amount of the second tetraethyl orthosilicate is 4.1 percent of the volume of the second solvent; the reaction temperature is 38 ℃, and the reaction time is 9h.
(3) Adding the first modified neodymium iron boron magnetic powder prepared in the step (1) and the second modified neodymium iron boron magnetic powder prepared in the step (2) into an organic solvent medium containing a modifier, and performing ultrasonic dispersion and stirring to connect the modifier with the first modified neodymium iron boron magnetic powder and the second modified neodymium iron boron magnetic powder through chemical bonds; the modifier is a silane coupling agent containing carbon-carbon double bonds, the volume ratio of the mass of the magnetic powder to the organic solvent is 51g/100ml, and the concentration of the modifier is 4.9wt%. The stirring speed is 470r/min, and the stirring time is 16min.
(4) And further adding an unsaturated monomer and an initiator, performing ultrasonic dispersion and stirring to enable the unsaturated monomer and the modifier to perform a grafting reaction, and enabling the unsaturated monomer to perform a polymerization reaction to form a coating layer, thereby obtaining a finished product. The unsaturated monomer is an acrylic unsaturated monomer, and the mass ratio of the unsaturated monomer to the magnetic powder is 7.4. The stirring speed is 88r/min, the temperature is raised to 74 ℃, and the polymerization reaction is carried out for 4.8h under the protective atmosphere.
The neodymium iron boron permanent magnet is prepared from the modified neodymium iron boron magnetic powder prepared by the embodiment by adopting a conventional method, through tests, the remanence of the prepared neodymium iron boron permanent magnet is 18.8kGs, the magnetic energy product is 60MGOe, the coercive force is 49000Oe, and the high-temperature demagnetization rate of the neodymium iron boron permanent magnet is 0.04% after the neodymium iron boron permanent magnet is placed at 200 ℃ for 1 hour.
The design key points of the invention are as follows: the first modified neodymium iron boron magnetic powder and the second modified neodymium iron boron magnetic powder are prepared firstly, then the first modified neodymium iron boron magnetic powder and the second modified neodymium iron boron magnetic powder are mixed for secondary modification, and the two modifications are organically combined, so that the prepared permanent magnet has larger residual magnetism and magnetic energy product, the coercive force is effectively improved, the demagnetization rate is greatly reduced, and the use requirement is met.
The technical principle of the present invention is described above in connection with specific embodiments. The description is made for the purpose of illustrating the principles of the invention and should not be construed in any way as limiting the scope of the invention. Based on the explanations herein, those skilled in the art will be able to conceive of other embodiments of the present invention without inventive effort, which would fall within the scope of the present invention.
Claims (7)
1. A preparation method of modified neodymium iron boron magnetic powder is characterized by comprising the following steps: the method comprises the following steps:
(1) Dispersing the first nanometer neodymium iron boron magnetic powder, the nanometer silver powder and the nanometer aluminum powder in a first solvent, adding first concentrated ammonia water and first tetraethyl orthosilicate for reaction to obtain first modified neodymium iron boron magnetic powder;
(2) Dispersing the second nanometer neodymium iron boron magnetic powder, the nanometer zinc powder and the nanometer copper powder in a second solvent, and adding second concentrated ammonia water and second tetraethyl orthosilicate for reaction to obtain second modified neodymium iron boron magnetic powder;
(3) Adding the first modified neodymium iron boron magnetic powder prepared in the step (1) and the second modified neodymium iron boron magnetic powder prepared in the step (2) into an organic solvent medium containing a modifier, and ultrasonically dispersing and stirring to connect the modifier with the first modified neodymium iron boron magnetic powder and the second modified neodymium iron boron magnetic powder through chemical bonds;
(4) And further adding an unsaturated monomer and an initiator, performing ultrasonic dispersion and stirring to enable the unsaturated monomer and the modifier to perform a grafting reaction, and enabling the unsaturated monomer to perform a polymerization reaction to form a coating layer, thereby obtaining a finished product.
2. The method for preparing the modified neodymium-iron-boron magnetic powder according to claim 1, which is characterized in that: the first nanometer neodymium iron boron magnetic powder is 50 parts by weight, the nanometer silver powder is 1-2 parts by weight, the nanometer aluminum powder is 0.5-1 part by weight, the first solvent is absolute ethyl alcohol, and the solid content of the first nanometer neodymium iron boron magnetic powder, the nanometer silver powder and the nanometer aluminum powder in the first solvent is 0.8-1 g/ml; the adding amount of the first strong ammonia water is 8-10% of the volume of the first solvent; the adding amount of the first tetraethyl orthosilicate is 4-5% of the volume of the first solvent; the reaction temperature is 35-40 ℃, and the reaction time is 5-10 h.
3. The method for preparing the modified neodymium-iron-boron magnetic powder according to claim 1, which is characterized in that: the second nanometer neodymium iron boron magnetic powder is 50 parts by weight, the nanometer zinc powder is 1-2 parts by weight, the nanometer copper powder is 0.5-1 part by weight, the second solvent is absolute ethyl alcohol, and the solid content of the second nanometer neodymium iron boron magnetic powder, the nanometer zinc powder and the nanometer copper powder in the second solvent is 0.8-1 g/ml; the adding amount of the second strong ammonia water is 8-10% of the volume of the second solvent; the adding amount of the second tetraethyl orthosilicate is 4-5% of the volume of the second solvent; the reaction temperature is 35-40 ℃, and the reaction time is 5-10 h.
4. The method for preparing the modified neodymium-iron-boron magnetic powder according to claim 1, which is characterized in that: the modifier is a silane coupling agent containing carbon-carbon double bonds, the volume ratio of the mass of the magnetic powder to the volume of the organic solvent is 50-55 g/100ml, and the concentration of the modifier is 4-5 wt%.
5. The method for preparing the modified neodymium-iron-boron magnetic powder according to claim 1, which is characterized in that: the unsaturated monomer is at least one of acrylic unsaturated monomer and aromatic unsaturated monomer, and the mass ratio of the unsaturated monomer to the magnetic powder is 6-8.
6. The method for preparing the modified neodymium-iron-boron magnetic powder according to claim 1, which is characterized in that: in the step (3), the stirring speed is 400-500 r/min, and the stirring time is 15-20min.
7. The method for preparing the modified neodymium-iron-boron magnetic powder according to claim 1, characterized by comprising the following steps: in the step (4), the stirring speed is 80-90 r/min, the temperature is raised to 70-75 ℃, and the polymerization reaction is carried out for 4-5 h under the protective atmosphere.
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