CN113223799B - Neodymium-iron-boron strip and pulse magnetizing process thereof - Google Patents
Neodymium-iron-boron strip and pulse magnetizing process thereof Download PDFInfo
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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
- H01F1/0572—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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- 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
- H01F1/0578—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 bonded together
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- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F13/00—Apparatus or processes for magnetising or demagnetising
- H01F13/003—Methods and devices for magnetising permanent magnets
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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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Abstract
The application relates to the field of rare earth permanent magnets, and particularly discloses a neodymium iron boron strip, which comprises the following raw materials: modifying neodymium iron boron powder by a pyrophosphate titanate coupling agent; an epoxy resin binder; and (3) a thermal curing agent. A pulse magnetizing process for neodymium iron boron strips comprises the following steps: s1, weighing pyrophosphate titanate coupling agent modified neodymium iron boron powder, epoxy resin binder and thermal curing agent according to the required weight parts of the formula, and uniformly stirring and mixing to obtain a mixture; s2, pre-magnetizing the mixture obtained in the step S1 in a pulse magnetic field, then applying orientation pulse for magnetization, pressing at the temperature of 160-170 ℃, curing and forming to obtain a finished product. The neodymium-iron-boron powder is modified by adopting a pyrophosphate titanate coupling agent, so that the iron-boron strip has better mechanical strength and better coercive force and remanence. The epoxy resin adhesive with the epoxy equivalent of 500-850g/eq is selected to ensure the density and compressive strength of the neodymium iron boron strip.
Description
Technical Field
The application relates to the field of rare earth permanent magnets, in particular to a neodymium iron boron strip and a pulse magnetizing process thereof.
Background
The magnetic energy product of the neodymium iron boron permanent magnet is between 27 and 50MGOe, is called as 'permanent magnet king', and is the permanent magnet material with the highest magnetism at present.
With the continuous expansion of the application field of the neodymium iron boron magnet, higher requirements are provided for the magnetization of the high-end rare earth permanent magnet material neodymium iron boron, and the requirement that the magnetization field strength required by the saturation magnetization of the neodymium iron boron magnet is about 3-5 times of the intrinsic coercive force is met. Because the pulse magnetizing current intensity is large, the time is short, and the conversion of electromagnetic energy can saturate and magnetize the permanent magnet with ultrahigh intrinsic coercivity, the pulse magnetizing method replaces the constant and stable magnetic field magnetizing method of the traditional electromagnet and is valued.
The neodymium iron boron magnet has two types of sintering and bonding, when the neodymium iron boron magnet is prepared by adopting a bonding process, a bonding agent is added into neodymium iron boron magnetic powder, the mixture is mixed, solidified and molded into a solid, and a finished product neodymium iron boron magnet is prepared by a magnetizing process in the later stage.
However, due to the addition of the binder, the density of the ndfeb magnet is reduced, the intrinsic coercive force and the residual magnetic induction intensity are reduced, and the magnetism of the ndfeb magnet is affected, so that in the manufacturing process of the ndfeb magnet, the content of the binder in the magnet is reduced as much as possible on the premise that a complete magnet with certain mechanical properties is required to be obtained.
Therefore, it is a hot point of research to develop a neodymium iron boron magnet with better mechanical property and magnetism under the condition of low binder addition.
Disclosure of Invention
In order to develop a neodymium iron boron magnet with good mechanical property and magnetism under the condition of low addition of a bonding agent, the application provides a neodymium iron boron strip and a pulse magnetizing process thereof
In a first aspect, the present application provides a neodymium iron boron strip, which adopts the following technical scheme:
a neodymium iron boron strip comprises the following raw materials in parts by weight:
100 parts of modified neodymium iron boron powder of a pyrophosphate titanate coupling agent;
1.4-2 parts of epoxy resin binder;
0.6-1.1 parts of thermal curing agent.
Through adopting above-mentioned technical scheme, adopt pyrophosphate type titanate coupling agent to modify neodymium iron boron powder, make neodymium iron boron powder surface and pyrophosphate type titanate coupling agent graft and form the chemical bond, at the neodymium iron boron surface cladding one deck coupling agent.
The compatibility of the pyrophosphate titanate coupling agent modified neodymium iron boron powder and an epoxy resin binder is good, so that the neodymium iron boron powder is not easy to agglomerate.
According to the application, the epoxy resin binder accounting for 1.4-2% of the mass of the pyrophosphate titanate coupling agent modified neodymium iron boron powder is added, and a trace amount of the epoxy resin binder can fully infiltrate the surface of the pyrophosphate titanate coupling agent modified neodymium iron boron powder, so that the bonding area of adjacent neodymium iron boron powder particles is increased, and the bonding strength is improved. And a small amount of epoxy resin binder is added, so that the density of the neodymium iron boron magnet is guaranteed, and the neodymium iron boron strip has good intrinsic coercive force and residual magnetic induction strength.
And preferentially carrying out chemical reaction on the pyrophosphate titanate coupling agent and the epoxy resin binder to improve the number of active hydroxyl groups on the surface of the neodymium iron boron, and grafting the epoxy resin on the modified neodymium iron boron powder to ensure that the number of grafted epoxy resin molecules on the unit area of the neodymium iron boron powder is large, so that a stable chemical bond is formed, the bonding strength is improved, and the compressive strength of the neodymium iron boron magnetic stripe is improved.
Through adopting pyrophosphate titanate coupling agent and introducing flexible pyrophosphate group, when the neodymium iron boron strip is subjected to external acting force, stress is generated between powder particles inside the neodymium iron boron strip to resist the external force, so that the neodymium iron boron strip is not easy to crack, and the mechanical strength of the neodymium iron boron strip is improved.
The thermal curing agent is used for curing the epoxy resin binder under the heating condition to form a three-dimensional network structure.
Optionally, the epoxy equivalent of the epoxy resin adhesive is 500-850 g/eq.
Through adopting above-mentioned technical scheme, the epoxy binder of molecular weight in adopting makes epoxy's mobility moderate, conveniently closely wraps up pyrophosphate type titanate coupling agent modified neodymium iron boron powder, and in the production process of neodymium iron boron strip, in high temperature process, epoxy volatilizees lessly, makes neodymium iron boron strip inner structure compact, guarantees the density of neodymium iron boron strip, makes the neodymium iron boron strip have better intrinsic coercive force and surplus magnetic induction intensity.
Optionally, the pyrophosphate titanate coupling agent is bis (dioctyloxypyrophosphate) ethylene titanate.
Through the technical scheme, a large number of pyrophosphate-based flexible groups are contained in the bis (dioctyloxy pyrophosphate-based) ethylene titanate, a large number of flexible chains are introduced, and the internal stress generated by the neodymium iron boron strip when the neodymium iron boron strip is subjected to external force is remarkably improved, so that the neodymium iron boron strip has better mechanical strength.
Optionally, the thermal curing agent is methyl tetrahydrophthalic anhydride.
By the technical scheme, the methyl tetrahydrophthalic anhydride is a novel liquid organic anhydride epoxy resin curing agent with excellent performance. The heat curing agent has the advantages of light color, good stability, long working life, low toxicity, small heating loss and good solubility, and is suitable for heat curing agents required in schemes.
Optionally, the preparation method of the pyrophosphate titanate coupling agent modified neodymium iron boron powder comprises the following steps:
s1, weighing 8-12 parts of pyrophosphate titanate coupling agent, and dissolving in 5-10 parts of ethanol to obtain a mixed solution A;
s2, weighing 100 parts of neodymium-iron-boron powder and 30-50 parts of ethanol, uniformly stirring and mixing, heating to 60-70 ℃, adding the mixed solution A prepared in the step S1, stirring and reacting at constant temperature for 1-2 hours, stopping heating, standing for layering, and drying the lower-layer solid to obtain pyrophosphate type titanate coupling agent modified neodymium-iron-boron powder.
Through the technical scheme, the pyrophosphate titanate coupling agent modified neodymium iron boron powder is prepared.
Optionally, 0.5-1 part of lauric acid monoglyceride is added in the step of S1.
Through the technical scheme, the addition of the lauric acid monoglyceride improves the grafting amount of the neodymium iron boron powder and the pyrophosphate titanate coupling agent.
In a second aspect, the application provides a pulse magnetizing process for neodymium iron boron strips, which adopts the following technical scheme:
a pulse magnetizing process for neodymium iron boron strips comprises the following steps:
s1, weighing pyrophosphate titanate coupling agent modified neodymium iron boron powder, epoxy resin binder and thermal curing agent according to the required weight parts of the formula, and uniformly stirring and mixing to obtain a mixture;
s2, pre-magnetizing the mixture obtained in the step S1 in a pulse magnetic field, then applying orientation pulse for magnetization, pressing at the temperature of 160-170 ℃, curing and forming to obtain a finished product.
By adopting the technical scheme, the finished neodymium iron boron strip is directly obtained in one step by carrying out curing crosslinking in the oriented magnetic field and pressing and forming, so that the magnetizing process is simple, the time cost is low, and the production efficiency is high.
Optionally, nitrogen is used for protection when the pressing is carried out at the temperature of 160-170 ℃ in the step S2.
By adopting the technical scheme, the epoxy resin adhesive is easy to oxidize under the high-temperature condition, so that the heat loss of the epoxy resin adhesive is increased, the adhesive strength is influenced, the density of the neodymium iron boron strip is also influenced, and the residual magnetic induction intensity of the neodymium iron boron strip is reduced. Meanwhile, the neodymium iron boron is easy to self-ignite at high temperature, and is protected by nitrogen to prevent the neodymium iron boron from self-igniting, so that the safety of the production process is improved.
In summary, the present application has the following beneficial effects:
1. because the neodymium iron boron powder modified by the pyrophosphate titanate coupling agent is used as the raw material, the iron boron strip has better mechanical strength and better intrinsic coercive force and residual magnetic induction strength.
2. The density of the neodymium iron boron strip is ensured by selecting the epoxy resin adhesive with the epoxy equivalent of 500-850g/eq, so that the neodymium iron boron strip has better intrinsic coercive force and residual magnetic induction strength.
3. By adding lauric acid monoglyceride, the reaction of neodymium iron boron powder with ethanol is suppressed, and the grafting amount with the pyrophosphate-type titanate coupling agent is increased.
Detailed Description
The present application will be described in further detail with reference to examples.
| Name of raw materials | Species or origin |
| Neodymium iron boron powder | Particle D50 was 100 microns, sold by Nikegaku, Japan. |
| Epoxy resin binder | NPES-601 with an epoxy equivalent of 510-570 g/eq; NPES-602L, epoxy equivalent is 640-680 g/eq; NPES-604 with an epoxide equivalent of 800- |
| Pyrophosphate type titanate coupling agent | Bis (dioctyloxypyrophosphate) ethylene titanate coupling agent sold by Wuhan Huaxiangchu scientific biotechnology Limited |
| Thermal curing agent | Methyltetrahydrophthalic anhydride, Haoyao, HY7887755 |
| Lauric acid monoglyceride | All in China |
Preparation example
Preparation example 1
Preparation of pyrophosphate titanate coupling agent modified neodymium iron boron powder:
s1, weighing 10kg of bis (dioctyloxy pyrophosphate) ethylene titanate coupling agent, stirring and dissolving in 10kg of ethanol to obtain a mixed solution A;
s2, weighing 100kg of neodymium-iron-boron powder and 42kg of ethanol, uniformly stirring and mixing, heating to 70 ℃, adding the mixed solution A prepared in the step S1, stirring and reacting for 2 hours at constant temperature, stopping heating, standing for layering, taking a lower-layer solid, cleaning with acetone for three times, and drying in vacuum to obtain the pyrophosphate type titanate coupling agent modified neodymium-iron-boron powder.
Preparation example 2
Preparation of pyrophosphate titanate coupling agent modified neodymium iron boron powder:
the difference from preparation example 1 was that 0.8kg of monoglyceride laurate was added in the step of S1.
Preparation example 3
Preparation of comparative neodymium iron boron powder:
the difference from preparation example 1 is that the titanate coupling agent sold by Nanjing Feiteng chemical company Limited is substituted for bis (dioctyloxy pyrophosphate) ethylene titanate coupling agent in equal amount to obtain the neodymium iron boron powder.
Examples
Example 1
A neodymium iron boron strip comprises the following raw materials by weight:
100kg of pyrophosphate-type titanate coupling agent-modified neodymium iron boron powder obtained in preparation example 1;
NPES-601 1.4kg；
0.6kg of methyl tetrahydrophthalic anhydride.
A pulse magnetizing process for neodymium iron boron strips comprises the following steps:
s1, weighing pyrophosphate titanate coupling agent modified neodymium-iron-boron powder, NPES-601 and methyl tetrahydrophthalic anhydride according to the required weight of the formula, and uniformly stirring and mixing to obtain a mixture, wherein the stirring speed is 500 r/min;
and S2, pre-magnetizing the mixture obtained in the step S1 in a pulse magnetic field provided by a high-field pulse magnetizing machine, applying an orientation magnetic field to perform pulse magnetizing, stirring at 160 ℃ for 5min under the protection of nitrogen, pressing by using a microcomputer-controlled hydraulic pressure tester, curing and forming, wherein the pressure of the pressure tester is 700MPa, and obtaining a cylindrical finished product with the diameter of 10mm and the length of 80 mm.
Example 2
A neodymium iron boron strip comprises the following raw materials:
100kg of pyrophosphate-type titanate coupling agent-modified neodymium iron boron powder obtained in preparation example 1;
NPES-601 2kg；
1.1kg of methyl tetrahydrophthalic anhydride.
A pulse magnetizing process for neodymium iron boron strips comprises the following steps:
s1, weighing pyrophosphate titanate coupling agent modified neodymium-iron-boron powder, NPES-601 and methyl tetrahydrophthalic anhydride according to the required weight of the formula, and uniformly stirring and mixing to obtain a mixture, wherein the stirring speed is 500 r/min;
and S2, pre-magnetizing the mixture obtained in the step S1 in a pulse magnetic field provided by a high-field pulse magnetizing machine, applying an orientation magnetic field to perform pulse magnetizing, stirring at the temperature of 170 ℃ for 5min under the protection of nitrogen, pressing by using a microcomputer-controlled hydraulic pressure tester, curing and forming, wherein the pressure of the pressure tester is 700MPa, and thus obtaining a cylindrical finished product with the diameter of 10mm and the length of 80 mm.
Example 3
A neodymium iron boron strip comprises the following raw materials:
100kg of pyrophosphate-type titanate coupling agent-modified neodymium iron boron powder obtained in preparation example 1;
NPES-601 1.6kg；
0.8kg of methyl tetrahydrophthalic anhydride.
A pulse magnetizing process for neodymium iron boron strips comprises the following steps:
s1, weighing pyrophosphate titanate coupling agent modified neodymium-iron-boron powder, NPES-601 and methyl tetrahydrophthalic anhydride according to the required weight of the formula, and uniformly stirring and mixing to obtain a mixture, wherein the stirring speed is 500 r/min;
and S2, pre-magnetizing the mixture obtained in the step S1 in a pulse magnetic field provided by a high-field pulse magnetizing machine, applying an orientation magnetic field to perform pulse magnetizing, stirring at 165 ℃ for 5min under the protection of nitrogen, pressing by using a microcomputer-controlled hydraulic pressure tester, curing and forming, wherein the pressure of the pressure tester is 700MPa, and obtaining a cylindrical finished product with the diameter of 10mm and the length of 80 mm.
Example 4
The difference from example 3 is that NPES-602L replaces NPES-601 by the same amount.
Example 5
The difference from example 3 is that NPES-604 replaces NPES-601 by an equal amount.
Example 6
The difference from example 3 is that NPEL-127 is substituted for NPES-601 in equal amount, and the epoxy equivalent of NPEL-127 is 176-184 g/eq.
Example 7
The difference from example 3 is that NPES-627 is substituted for NPES-601 in equal amount, and NPEL-127 has an epoxy equivalent of 1650-1900 g/eq.
Example 8
The difference from example 3 is that the pyrophosphate type titanate coupling agent modified neodymium iron boron powder is obtained from preparation example 2.
Example 9
The difference from example 8 is that the pressure in the pressure tester is 600 MPa.
Example 10
The difference from example 8 is that the pressure in the pressure tester is 800 MPa.
Comparative example
Comparative example 1
The difference from example 3 is that the neodymium iron boron powder modified with a pyrophosphate-type titanate coupling agent was replaced by the comparative neodymium iron boron powder obtained in preparation example 3 in equal amounts.
Comparative example 2
The difference from comparative example 1 is that the pressure of the pressure tester is 600 MPa.
Comparative example 3
The difference from comparative example 3 is that the neodymium-iron-boron powder is not modified, 10kg of bis (dioctyloxy-pyrophosphate-based) ethylene titanate coupling agent, 100kg of neodymium-iron-boron powder, 1.6kg of NPES-601 and 0.8kg of methyl tetrahydrophthalic anhydride are stirred and mixed uniformly to obtain a mixture, and the stirring speed is 500 r/min; then the cylindrical product with the diameter of 10mm and the length of 80mm is prepared by the step of S2.
Comparative example 4
The difference from example 3 is that NPES-601 was added in an amount of 1 kg.
Comparative example 5
The difference from example 3 is that NPES-601 was added in an amount of 2.5 kg.
Performance test
The cylindrical products obtained in examples 1 to 11 and comparative examples 1 to 3 were observed for the presence of cracks and tested as follows, the results of which are detailed in Table 1.
And (3) testing the density: the mass of the product is weighed by an STC electronic balance, and the density is obtained by calculation.
Testing of magnetic properties: determination of intrinsic coercivity H of cylindrical finished product by DGN-3 multifunctional magnetic measuring instrumentcjAnd residual magnetic induction intensity Br。
And (3) testing the compressive strength: and detecting the compressive strength by a DW-5 electronic universal tester.
TABLE 1
| Br（T） | Hcj（kA*m-1） | ρ（g*cm-3） | Compressive strength (MPa) | Whether or not there is a crack | |
| Example 1 | 0.526 | 726 | 5.72 | 35 | Whether or not |
| Example 2 | 0.542 | 733 | 5.78 | 36 | Whether or not |
| Example 3 | 0.544 | 741 | 5.82 | 38 | Whether or not |
| Example 4 | 0.532 | 730 | 5.76 | 36 | Whether or not |
| Example 5 | 0.529 | 728 | 5.72 | 36 | Whether or not |
| Example 6 | 0.499 | 703 | 5.55 | 31 | Whether or not |
| Example 7 | 0.505 | 711 | 5.63 | 32 | Whether or not |
| Example 8 | 0.546 | 743 | 5.84 | 43 | Whether or not |
| Example 9 | 0.479 | 682 | 5.34 | 31 | Whether or not |
| Example 10 | 0.552 | 756 | 5.94 | 36 | Is that |
| Comparative example 1 | 0.526 | 724 | 5.73 | 25 | Is that |
| Comparative example 2 | 0.481 | 692 | 5.36 | 27 | Is that |
| Comparative example 3 | 0.507 | 706 | 5.80 | 29 | Whether or not |
| Comparative example 4 | 0.551 | 748 | 5.89 | 27 | Is that |
| Comparative example 5 | 0.487 | 665 | 7.54 | 39 | Whether or not |
It can be seen from the combination of examples 1-5 and comparative examples 1 and 2 and table 1 that the introduction of the flexible pyrophosphate-type titanate coupling agent modified neodymium iron boron powder can lead to the cylindrical product with better compressive strength, and the cylindrical product is not easy to crack under the same production pressure.
It can be seen by combining example 3 with comparative examples 1 and 2 and by combining table 1 that cracks appear in the cylindrical finished product even at a processing pressure of 600 MPa.
By combining example 3 and comparative example 3 and table 1, it can be seen that when a neodymium iron boron powder bis (dioctyloxypyrophosphate) ethylene titanate coupling agent and NPES-601 are directly coupled to prepare a cylindrical finished product, the coupling reaction effect is poor, and the compressive strength of the cylindrical finished product is obviously reduced under the condition of similar densities.
When example 3 and comparative examples 4 to 5 are combined and table 1 is combined, the compressive strength is obviously reduced when the addition amount of NPES-601 is reduced, but the intrinsic coercive force and the residual magnetic induction are only improved to a small extent; however, after the addition amount is increased, the compressive strength of the cylindrical finished product is not changed greatly, but the intrinsic coercive force and the residual magnetic induction intensity are both greatly reduced.
Combining the examples 3 and 4-7 and combining the table 1, it can be seen that when the epoxy equivalent of the epoxy resin binder is at 510-570g/eq, 640-680 g/eq and 800-850g/eq, the effect is better, and when the epoxy equivalent of the epoxy resin binder is at 176-184g/eq and 1650-1900g/eq, the density of the cylindrical product is reduced, because the epoxy resin binder with low epoxy equivalent has higher fluidity and larger heating loss; the epoxy resin binder with high epoxy equivalent has high consistency, so that the cladding performance of the neodymium iron boron powder is poor, the compression resistance and the density are reduced, and the intrinsic coercive force and the residual magnetic induction intensity of the cylindrical finished product are poor.
By combining example 3 and example 8 and table 1, it can be seen that the monolaurin increases the grafting amount of the coupling agent with pyrophosphate titanate, so that the grafting amount of the coupling agent with pyrophosphate titanate per unit area of the neodymium iron boron powder modified by the coupling agent with pyrophosphate titanate is opposite, and the chemical bonds generated after the late crosslinking with the epoxy resin binder are more, so that the compressive strength of the cylindrical finished product is remarkably improved.
Combining example 8 with examples 9 and 10 and combining table 1, it can be seen that the processing pressure is small, resulting in a decrease in the density of the finished cylindrical product, and thus the intrinsic coercivity and residual magnetic induction of the finished cylindrical product are poor. When the working pressure reaches 800MP, the result is that although the density of the cylindrical product increases, cracks appear.
The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.
Claims (3)
1. The neodymium iron boron strip is characterized by comprising the following raw materials in parts by weight:
100 parts of modified neodymium iron boron powder of a pyrophosphate titanate coupling agent;
1.4-2 parts of epoxy resin binder;
0.6-1.1 parts of a thermal curing agent;
the epoxy equivalent of the epoxy resin binder is 500-850 g/eq;
the pyrophosphate titanate coupling agent is bis (dioctyloxy pyrophosphate) ethylene titanate;
the preparation method of the pyrophosphate titanate coupling agent modified neodymium iron boron powder comprises the following steps:
s1, weighing 8-12 parts of pyrophosphate titanate coupling agent, and dissolving in 5-10 parts of ethanol to obtain a mixed solution A;
s2, weighing 100 parts of neodymium-iron-boron powder and 30-50 parts of ethanol, uniformly stirring and mixing, heating to 60-70 ℃, adding the mixed solution A prepared in the step S1, stirring and reacting at constant temperature for 1-2 hours, stopping heating, standing for layering, and drying the lower-layer solid to obtain pyrophosphate type titanate coupling agent modified neodymium-iron-boron powder;
0.5-1 part of lauric acid monoglyceride is added in the step S1;
the pulse magnetizing process of the neodymium iron boron strip comprises the following steps:
s1, weighing pyrophosphate titanate coupling agent modified neodymium iron boron powder, epoxy resin binder and thermal curing agent according to the required weight parts of the formula, and uniformly stirring and mixing to obtain a mixture;
s2, pre-magnetizing the mixture obtained in the step S1 in a pulse magnetic field, then applying orientation pulse for magnetization, pressing at the temperature of 160-170 ℃, curing and forming to obtain a finished product.
2. A neodymium iron boron strip according to claim 1, characterized in that: the thermal curing agent is methyl tetrahydrophthalic anhydride.
3. A neodymium iron boron strip according to claim 1, characterized in that: and in the step S2, nitrogen protection is adopted when the pressure is carried out at the temperature of 160-170 ℃.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN101000818A (en) * | 2006-01-13 | 2007-07-18 | 横店集团东磁有限公司 | Adhesive motor magnetic strip and preparation method thereof |
| CN101740193A (en) * | 2009-12-31 | 2010-06-16 | 中国船舶重工集团公司第七二五研究所 | Rare-earth permanent magnet with high magnetic performance and high electric resistance and preparation method thereof |
| CN108335815A (en) * | 2018-01-30 | 2018-07-27 | 苏州宝力塑胶材料有限公司 | Rare-earth magnetic composition for magnetic master batch or magnetic fibre and the method for preparing the rare-earth magnetic composition |
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| JP2861374B2 (en) * | 1990-11-19 | 1999-02-24 | 味の素株式会社 | toner |
| JP2002373805A (en) * | 2001-06-13 | 2002-12-26 | Daido Electronics Co Ltd | Neodymium-based bond magnet and forming method thereof |
| CN101656134A (en) * | 2008-08-18 | 2010-02-24 | 上海爱普生磁性器件有限公司 | High temperature resistant bonding rare earth magnet and preparation method thereof |
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| CN101000818A (en) * | 2006-01-13 | 2007-07-18 | 横店集团东磁有限公司 | Adhesive motor magnetic strip and preparation method thereof |
| CN101740193A (en) * | 2009-12-31 | 2010-06-16 | 中国船舶重工集团公司第七二五研究所 | Rare-earth permanent magnet with high magnetic performance and high electric resistance and preparation method thereof |
| CN108335815A (en) * | 2018-01-30 | 2018-07-27 | 苏州宝力塑胶材料有限公司 | Rare-earth magnetic composition for magnetic master batch or magnetic fibre and the method for preparing the rare-earth magnetic composition |
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