CN111430091B - High-coercivity sintered NdFeB magnet and preparation method thereof - Google Patents
High-coercivity sintered NdFeB magnet and preparation method thereof Download PDFInfo
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- 229910001172 neodymium magnet Inorganic materials 0.000 title claims abstract description 64
- 238000002360 preparation method Methods 0.000 title claims abstract description 21
- 229910052761 rare earth metal Inorganic materials 0.000 claims abstract description 24
- 229910052779 Neodymium Inorganic materials 0.000 claims abstract description 15
- 229910052796 boron Inorganic materials 0.000 claims abstract description 11
- 229910052777 Praseodymium Inorganic materials 0.000 claims abstract description 7
- 229910045601 alloy Inorganic materials 0.000 claims description 71
- 239000000956 alloy Substances 0.000 claims description 71
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 52
- 239000001257 hydrogen Substances 0.000 claims description 52
- 229910052739 hydrogen Inorganic materials 0.000 claims description 52
- 239000010949 copper Substances 0.000 claims description 28
- 238000005496 tempering Methods 0.000 claims description 24
- 239000007788 liquid Substances 0.000 claims description 22
- 239000000843 powder Substances 0.000 claims description 22
- 238000000227 grinding Methods 0.000 claims description 21
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 18
- 239000011362 coarse particle Substances 0.000 claims description 18
- 229910052802 copper Inorganic materials 0.000 claims description 14
- 238000010438 heat treatment Methods 0.000 claims description 14
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 12
- 238000005245 sintering Methods 0.000 claims description 12
- 239000002245 particle Substances 0.000 claims description 10
- 229910052757 nitrogen Inorganic materials 0.000 claims description 9
- 238000002844 melting Methods 0.000 claims description 8
- 230000008018 melting Effects 0.000 claims description 8
- 238000000034 method Methods 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 229910052733 gallium Inorganic materials 0.000 claims description 5
- 229910052742 iron Inorganic materials 0.000 claims description 5
- 229910052692 Dysprosium Inorganic materials 0.000 claims description 3
- 238000010902 jet-milling Methods 0.000 claims 1
- 150000002910 rare earth metals Chemical class 0.000 abstract description 15
- 239000000203 mixture Substances 0.000 abstract description 6
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 18
- 230000000052 comparative effect Effects 0.000 description 15
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 14
- 229910052786 argon Inorganic materials 0.000 description 7
- 239000007789 gas Substances 0.000 description 7
- 239000002994 raw material Substances 0.000 description 7
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 6
- 238000011049 filling Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 3
- QJVKUMXDEUEQLH-UHFFFAOYSA-N [B].[Fe].[Nd] Chemical compound [B].[Fe].[Nd] QJVKUMXDEUEQLH-UHFFFAOYSA-N 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 229910052771 Terbium Inorganic materials 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000314 lubricant Substances 0.000 description 2
- 239000000696 magnetic material Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002090 carbon oxide Inorganic materials 0.000 description 1
- 238000009694 cold isostatic pressing Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- KBQHZAAAGSGFKK-UHFFFAOYSA-N dysprosium atom Chemical compound [Dy] KBQHZAAAGSGFKK-UHFFFAOYSA-N 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 210000004754 hybrid cell Anatomy 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 description 1
- GZCRRIHWUXGPOV-UHFFFAOYSA-N terbium atom Chemical compound [Tb] GZCRRIHWUXGPOV-UHFFFAOYSA-N 0.000 description 1
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- 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
- H01F1/0576—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 pressed, e.g. hot working
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- 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 discloses a high-coercivity sintered NdFeB magnet and a preparation method thereof, belonging to the technical field of magnet preparation, wherein the high-coercivity sintered NdFeB magnet comprises, by weight, 30.10-32.45% of R, 0.84-0.91% of B, 0.08-0.22% of Si, 0.08-0.25% of Cu, 0.08-0.20% of Al, 0.45-0.88% of Ga, 0.87-3.00% of Co and the balance of Fe; r is at least 1 element of rare earth elements, and must contain Nd or Pr; the weight percentage of each component meets a certain proportion relation. The high-coercivity sintered NdFeB magnet can be prepared by adjusting the composition of Nd, pr, B, si, ga elements to meet a certain weight percentage relationship, so that the high-coercivity sintered NdFeB magnet can be obtained under the condition of reducing heavy rare earth or rare earth such as Dy.
Description
Technical Field
The invention belongs to the technical field of magnet preparation, and particularly relates to a high-coercivity sintered NdFeB magnet and a preparation method thereof.
Background
The permanent magnetic material is a material which can realize energy exchange between electric energy and mechanical energy through a magnetic field generated by the permanent magnetic material without an external electric field. The permanent magnet material is one of key materials for realizing high performance, miniaturization and high efficiency of household appliances such as air conditioners, refrigerators, traction motors, generators, fuel cells, hybrid electric vehicles, wind motors and other electrical equipment. The output of the permanent magnet motor is continuously increased, and the permanent magnet motor is influenced by environmental protection policies of reducing emission of greenhouse effect gases, such as carbon oxide and carbon dioxide, so that the demand of the permanent magnet material is continuously increased. Neodymium (Nd) is a main raw material for producing neodymium-iron-boron magnets, and due to the increase of the yield, the demand for Nd is also increasing, the content of Nd in minerals is limited, and the increasing demand increases the price of Nd. In order to reduce the usage amount of Nd, a method for preparing a sintered NdFeB magnet by compositely adding other rare earth elements to replace Nd is presented, such as Chinese patent application No. 200510049811.1, and the intrinsic coercivity of the magnet is improved by compositely adding heavy rare earth elements dysprosium (Dy) and terbium (Tb) to replace part of Nd. However, in 2011, the price of rare earth has been increased by 10 times, and many magnet manufacturers have suffered fatal attacks, forcing the price of rare earth permanent magnets to be increased. In addition to the pursuit of high performance, the price of Nd magnets has become a serious problem. For the third generation rare earth permanent magnet material, namely the sintered neodymium-iron-boron magnet, the market is in urgent need of the sintered neodymium-iron-boron magnet with low heavy rare earth or low rare earth and high performance and high coercivity.
Disclosure of Invention
In order to overcome the defects in the prior art, the technical problems to be solved by the invention are as follows: provides a high coercivity sintered NdFeB magnet with low heavy rare earth or little rare earth and a preparation method thereof.
In order to solve the technical problems, the invention adopts the following technical scheme: the high coercivity sintered NdFeB magnet comprises, by weight, 30.10-32.45% of R, 0.84-0.91% of B, 0.08-0.22% of Si, 0.08-0.25% of Cu, 0.08-0.20% of Al, 0.45-0.88% of Ga, 0.87-3.00% of Co and the balance of Fe; r is at least 1 element of rare earth elements and must contain Nd or Pr;
wherein, the weight percentages of the components are as follows:
0.050<((Nd+Pr)/143.61-2B/10.81)<0.062；
(Si/28.08)/(Ga/69.72)<0.65。
the invention adopts another technical scheme that: the preparation method of the high-coercivity sintered NdFeB magnet comprises the following steps of:
step 1, heating and melting 30.10-32.45% of R, 0.84-0.91% of B, 0.08-0.22% of Si, 0.08-0.25% of Cu, 0.08-0.20% of Al, 0.45-0.88% of Ga, 0.87-3.00% of Co and the balance of Fe into alloy liquid according to weight percentage, and pouring the alloy liquid onto a rotating copper roller to obtain a solidified alloy sheet;
step 2, performing hydrogen breaking treatment on the solidified alloy sheet to obtain coarse particles;
step 3, grinding the coarse particles into alloy powder with the particle size of 3-5 mu m through air flow;
step 4, forming alloy powder in a magnetic field of 1000-1600KA/m to obtain a green body;
step 5, sintering the green compact in a vacuum atmosphere to obtain a sintered magnet;
step 6, tempering the sintered magnet to obtain a high-coercivity sintered NdFeB magnet;
wherein, the weight percentages of the components are as follows:
0.050<((Nd+Pr)/143.61-2B/10.81)<0.062；
(Si/28.08)/(Ga/69.72)<0.65。
the invention has the beneficial effects that: the high-coercivity sintered NdFeB magnet provided by the invention has the advantages that the composition of Nd, pr, B, si, ga elements is adjusted to meet a certain weight percentage relationship, so that the high-coercivity sintered NdFeB magnet can be obtained under the condition of reducing rare earth elements (such as Dy), and the weight percentage of Si and Ga meets (Si/28.08)/(Ga/69.72)<When 0.65, fe and Nd, pr, si and Ga form a non-magnetic or low-magnetic 6:13:1 grain boundary phase, and when ((Nd+Pr)/143.61-2B/10.81) value is smaller than 0.050, the non-magnetic 6:13:1 grain boundary phase is too small, so that the intrinsic coercivity is limited; if the ratio is more than 0.062, the non-magnetic 6:13:1 type grain boundary phase is excessive, and a soft magnetic phase Nd is easy to form 2 Fe 17 Phase, the squareness of the magnet is reduced, and when Nd, pr and B satisfy 0.050<((Nd+Pr)/143.61-2B/10.81)<At 0.062, if (Si/28.08)/(Ga/69.72) is greater than 0.65, it is indicated that the Ga of the magnet is too small, so that the non-magnetic 6:13:1 type grain boundary phase is too small, and the improvement of the intrinsic coercivity is insufficient; when the rare earth, B, ga and Si are contained in any amount out of the above range, the magnet cannot form a nonmagnetic thin-walled grain boundary phase having a thickness of 5-15nm and an (R+Cu+Ga) of more than 75% and Fe element of less than 15%, so that a high intrinsic coercive force cannot be obtained. By means of the change of the components, the cost of raw materials in production can be greatly reduced, and dependence of high-quality neodymium-iron-boron magnets on a large amount of rare earth raw materials is eliminated. The preparation method of the high-coercivity sintered NdFeB magnet provided by the invention has the advantages of simple process, low equipment investment cost, no dependence on Dy addition and reduced production cost.
Drawings
FIG. 1 is a schematic diagram showing the results of the combined magnetic properties of sintered NdFeB magnets of examples 1-10 and comparative examples 1-5 according to embodiments of the present invention.
Detailed Description
In order to describe the technical contents, the achieved objects and effects of the present invention in detail, the following description will be made with reference to the embodiments in conjunction with the accompanying drawings.
The invention provides a high coercivity sintered NdFeB magnet, which comprises, by weight, 30.10-32.45% of R, 0.84-0.91% of B, 0.08-0.22% of Si, 0.08-1.2% of Cu, 0.08-0.20% of Al, 0.45-0.88% of Ga, 0.87-3.00% of Co and the balance of Fe; r is at least 1 element of rare earth elements and must contain Nd or Pr;
wherein, the weight percentages of the components are as follows:
0.050<((Nd+Pr)/143.61-2B/10.81)<0.062；
(Si/28.08)/(Ga/69.72)<0.65。
from the above description, the beneficial effects of the invention are as follows: the high coercivity sintered NdFeB magnet provided by the invention has the advantages that the composition of Nd, pr, B, si, ga element is adjusted to meet a certain weight percentage relation, and specifically, the weight percentage of Si and Ga meets (Si/28.08)/(Ga/69.72)<When 0.65, fe and Nd/Pr and Si, ga form a non-magnetic or low-magnetic 6:13:1 grain boundary phase, and if ((Nd+Pr)/143.61-2B/10.81) value is smaller than 0.050, the non-magnetic 6:13:1 grain boundary phase is too small, so that the intrinsic coercivity is limited; if the ratio is more than 0.062, the non-magnetic 6:13:1 type grain boundary phase is excessive, and a soft magnetic phase Nd is easy to form 2 Fe 17 Phase, the squareness of the magnet is reduced, and when Nd, pr and B satisfy 0.050<((Nd+Pr)/143.61-2B/10.81)<At 0.062, if (Si/28.08)/(Ga/69.72) is greater than 0.65, it is indicated that the Ga of the magnet is too small, so that the non-magnetic 6:13:1 type grain boundary phase is too small, and the improvement of the intrinsic coercivity is insufficient; when the rare earth, B, ga and Si are contained in any amount out of the above range, the magnet cannot form a nonmagnetic thin-walled grain boundary phase having a thickness of 5-15nm and an (R+Cu+Ga) of more than 75% and Fe element of less than 15%, so that a high intrinsic coercive force cannot be obtained. The high coercivity sintered NdFeB magnet can be obtained on the premise of not depending on the addition of a large amount of rare earth elements by precisely controlling the composition and the proportion of the element content.
The invention provides a preparation method of a high-coercivity sintered NdFeB magnet, which comprises the following steps:
step 1, heating and melting 30.10-32.45% of R, 0.84-0.91% of B, 0.08-0.22% of Si, 0.08-0.25% of Cu, 0.08-0.20% of Al, 0.45-0.88% of Ga, 0.87-3.00% of Co and the balance of Fe into alloy liquid according to weight percentage, and pouring the alloy liquid onto a rotating copper roller to obtain a solidified alloy sheet;
step 2, carrying out hydrogen breaking treatment on the solidified alloy sheet obtained in the step 1 to obtain coarse particles;
step 3, grinding the coarse particles obtained in the step 2 into alloy powder with the particle size of 3-5 mu m through air flow grinding;
step 4, forming the alloy powder obtained in the step 3 in a magnetic field of 1000-1600KA/m to obtain a green body;
step 5, sintering the green body obtained in the step 4 in a vacuum atmosphere to obtain a sintered magnet;
and 6, tempering the sintered magnet obtained in the step 5 to obtain the high-coercivity sintered NdFeB magnet.
From the above description, the beneficial effects of the invention are as follows: the preparation method of the high-coercivity sintered NdFeB magnet provided by the invention has the advantages of simple process and low equipment input cost, does not depend on addition of rare earth raw materials such as Dy and the like, and reduces the production cost.
Further, the high coercivity sintered NdFeB magnet is prepared from 22.16% of Nd, 7.26% of Pr, 2.67% of Dy, 0.87% of B, 0.08% of Si, 0.22% of Cu, 0.2% of Al, 0.5% of Ga, 1% of Co and the balance of Fe in percentage by weight.
Further, the high coercivity sintered NdFeB magnet is prepared from 25.14% of Nd, 7.20% of Pr, 0.86% of B, 0.1% of Si, 0.2% of Cu, 0.08% of Al, 0.82% of Ga, 1.22% of Co and the balance of Fe in percentage by weight.
From the above description, the sintered neodymium-iron-boron magnet made of the two components in percentage by weight is a high-coercivity sintered neodymium-iron-boron magnet with optimal magnetism when Dy is contained and Dy is not contained respectively.
Further, the temperature of the alloy liquid in the step 1 is 1300-1400 ℃, the rotating speed of the copper roller is 1.0-1.5m/s, and the thickness of the solidified alloy sheet is 0.15-5mm.
Further, the air flow grinding and crushing conditions in the step 3 are as follows: the nitrogen pressure is 0.5-0.65MPa, and the rotating speed is 3500-5000 rpm.
Further, the sintering temperature in the step 5 is 1000-1100 ℃.
Further, the tempering in the step 6 specifically includes: the primary tempering is carried out for 2-6h at 850-950 ℃, and the secondary tempering is carried out for 2-6h at 400-600 ℃.
Further, the tempering in the step 6 specifically includes: tempering at 400-600 deg.c for 2-6 hr.
The compositions (in weight percent) of the components of the high coercivity sintered NdFeB magnets of examples 1-10 and comparative examples 1-5 are shown in Table 1, with the sum of the weight percent of all components being 100%;
the value of (Nd+Pr)/143.61-2B/10.81 is represented by U;
the value of (Si/28.08)/(Ga/69.72) is represented by V.
TABLE 1
The preparation methods of the high coercivity sintered NdFeB magnets of examples 1-10 and the sintered NdFeB magnets of comparative examples 1-5 specifically comprise the following steps:
step 1, heating and melting all components in table 1 into alloy liquid at 1300 ℃ according to weight percentage, and pouring the alloy liquid onto a rotating copper roller with the rotating speed of 1.0m/s to obtain a solidified alloy sheet with the thickness of 0.5 mm;
wherein Nd is Nd with purity of more than 99.5%, B is from ferroboron, fe is from pure iron and ferroboron, co, al, cu, ga is electrolysis Co, al, cu, ga;
step 2, placing the solidified alloy sheet into a hydrogen breaking furnace for hydrogen breaking treatment, and vacuumizing the hydrogen breaking furnace to 1 multiplied by 10 after the solidified alloy sheet is placed into the hydrogen breaking furnace -2 Pa，Then argon is filled to 1.5kPa, the temperature is raised to 300 ℃ and the temperature is kept for 2 hours, and then the vacuum is pumped to 1X 10 - 2 Pa, recharging hydrogen to 0.25MPa, absorbing hydrogen under hydrogen pressure, and dehydrogenating at 570 ℃ to obtain coarse particles;
step 3, adding a lubricant into the coarse powder according to the proportion of 0.5ml/kg, mixing, and grinding into alloy powder with the particle size of 5 mu m through air flow grinding, wherein the conditions of the air flow grinding are as follows: nitrogen pressure 0.5MPa, rotational speed 3500 rpm;
step 4, forming alloy powder in a magnetic field of 1600KA/m, and preparing a green body by cold isostatic pressing of 17 MPa;
step 5, sintering the green compact in vacuum atmosphere at 1060 ℃ for 4 hours to obtain a sintered magnet;
and 6, performing primary tempering on the sintered magnet for 3 hours at 890 ℃, and performing secondary tempering on the sintered magnet for 3 hours at 490 ℃ to obtain the high-coercivity sintered NdFeB magnet.
Example 11:
the preparation method of the high-coercivity sintered NdFeB magnet specifically comprises the following steps:
step 1, heating and melting 22.7% of Nd, 7.4% of Pr, 0.84% of B, 0.16% of Si, 0.08% of Cu, 0.1% of Al, 0.7% of Ga, 3.0% of Co and the balance of Fe according to weight percentage to obtain alloy liquid at 1300 ℃, and pouring the alloy liquid onto a rotating copper roller with the rotating speed of 1.0m/s to obtain a solidified alloy sheet with the thickness of 0.5 mm;
step 2, placing the solidified alloy sheet into a hydrogen breaking furnace for hydrogen breaking treatment, and vacuumizing the hydrogen breaking furnace to 1 multiplied by 10 after the solidified alloy sheet is placed into the hydrogen breaking furnace -2 Pa, then filling argon gas to 1.5kPa, heating to 280 ℃ and preserving heat for 2 hours, then vacuumizing to 1X 10 - 2 Pa, recharging hydrogen to 0.25MPa, absorbing hydrogen under hydrogen pressure, and dehydrogenating at 570 ℃ to obtain coarse particles;
step 3, adding a lubricant into the coarse powder according to the proportion of 0.5ml/kg, mixing, and grinding into alloy powder with the particle size of 5 mu m through air flow grinding, wherein the conditions of the air flow grinding are as follows: nitrogen pressure 0.5MPa, rotational speed 3500 rpm;
step 4, forming alloy powder in a magnetic field of 1600KA/m to obtain a green body;
step 5, sintering the green compact in vacuum atmosphere at 1000 ℃ to obtain a sintered magnet;
and 6, carrying out primary tempering on the sintered magnet at 900 ℃ for 2 hours, and carrying out secondary tempering at 600 ℃ for 3 hours to obtain the high-coercivity sintered NdFeB magnet.
The obtained high-coercivity sintered NdFeB magnet: remanence Br (kG): 14.0; intrinsic coercivity Hcj (kOe): 18.70; comprehensive magnetic properties: 32.70.
example 12:
the preparation method of the high-coercivity sintered NdFeB magnet specifically comprises the following steps:
step 1, heating and melting 22.7% of Nd, 7.4% of Pr, 0.85% of B, 0.22% of Si, 0.08% of Cu, 0.1% of Al, 0.88% of Ga, 3.0% of Co and the balance of Fe according to weight percentage to obtain alloy liquid with the temperature of 1400 ℃, and pouring the alloy liquid onto a rotating copper roller with the rotating speed of 1.5m/s to obtain a solidified alloy sheet with the thickness of 0.15 mm;
step 2, placing the solidified alloy sheet into a hydrogen breaking furnace for hydrogen breaking treatment, and vacuumizing the hydrogen breaking furnace to 1 multiplied by 10 after the solidified alloy sheet is placed into the hydrogen breaking furnace -2 Pa, then filling argon gas to 1kPa, heating to 200 ℃ and preserving heat for 3 hours, then vacuumizing to 1X 10 - 2 Pa, recharging hydrogen to 0.2MPa, absorbing hydrogen under hydrogen pressure, and dehydrogenating at 570 ℃ to obtain coarse particles;
step 3, grinding coarse particles into alloy powder with the particle size of 3 mu m by using an air flow, wherein the conditions of the air flow grinding are as follows: nitrogen pressure is 0.65MPa, and rotation speed is 5000 rpm;
step 4, forming alloy powder in a magnetic field of 1000KA/m to obtain a green body;
step 5, sintering the green compact in a vacuum atmosphere at 1100 ℃ to obtain a sintered magnet;
and 6, tempering the sintered magnet at 600 ℃ for 6 hours to obtain the high-coercivity sintered NdFeB magnet.
The obtained high-coercivity sintered NdFeB magnet: br (kG): 13.8; hcj (kOe): 18.50; comprehensive magnetic properties: 32.30.
example 13:
the preparation method of the high-coercivity sintered NdFeB magnet specifically comprises the following steps:
step 1, according to weight percentage, 25.14% of Nd, 7.20% of Pr, 0.86% of B, 0.1% of Si, 0.2% of Cu, 0.08% of Al, 0.82% of Ga, 1.22% of Co and the balance of Fe are heated and melted into alloy liquid at 1350 ℃, and then the alloy liquid is poured onto a rotating copper roller with the rotating speed of 1.2m/s, so as to obtain a solidified alloy sheet with the thickness of 0.35 mm;
step 2, placing the solidified alloy sheet into a hydrogen breaking furnace for hydrogen breaking treatment, and vacuumizing the hydrogen breaking furnace to 1 multiplied by 10 after the solidified alloy sheet is placed into the hydrogen breaking furnace -2 Pa, then filling argon gas to 1.5kPa, heating to 300 ℃ and preserving heat for 1h, then vacuumizing to 1X 10 - 2 Pa, recharging hydrogen to 0.25MPa, absorbing hydrogen under hydrogen pressure, and dehydrogenating at 570 ℃ to obtain coarse particles;
step 3, crushing coarse particles into alloy powder with the particle size of 4 mu m through air flow grinding, wherein the conditions of the air flow grinding are as follows: nitrogen pressure is 0.6MPa, and rotating speed is 4500 rpm;
step 4, forming alloy powder in a magnetic field of 1500KA/m to obtain a green body;
step 5, sintering the green compact in a vacuum atmosphere at 1050 ℃ to obtain a sintered magnet;
and 6, tempering the sintered magnet at 400 ℃ for 2 hours to obtain the high-coercivity sintered NdFeB magnet.
Example 14:
the preparation method of the high-coercivity sintered NdFeB magnet specifically comprises the following steps:
step 1, heating and melting 25.14% of Nd, 7.20% of Pr, 0.86% of B, 0.1% of Si, 0.2% of Cu, 0.08% of Al, 0.82% of Ga, 1.22% of Co and the balance of Fe according to weight percentage to obtain alloy liquid at 1300 ℃, and pouring the alloy liquid onto a rotating copper roller with the rotating speed of 1.5m/s to obtain a solidified alloy sheet with the thickness of 0.4 mm;
step 2, placing the solidified alloy sheet in hydrogen breakPerforming hydrogen breaking treatment in the furnace, placing the solidified alloy sheet into the hydrogen breaking furnace, and vacuumizing the hydrogen breaking furnace to 1X 10 -2 Pa, then filling argon gas to 1.5kPa, heating to 250 ℃ and preserving heat for 2 hours, then vacuumizing to 1X 10 - 2 Pa, recharging hydrogen to 0.2MPa, absorbing hydrogen under hydrogen pressure, and dehydrogenating at 570 ℃ to obtain coarse particles;
step 3, crushing coarse particles into alloy powder with the particle size of 3.5 mu m through air flow grinding, wherein the conditions of the air flow grinding are as follows: nitrogen pressure is 0.55MPa, and rotating speed is 4000 rpm;
step 4, forming alloy powder in a magnetic field of 1300KA/m to obtain a green body;
step 5, sintering the green compact in vacuum atmosphere at 1080 ℃ to obtain a sintered magnet;
and 6, carrying out primary tempering on the sintered magnet at 850 ℃ for 6 hours, and carrying out secondary tempering at 400 ℃ for 2 hours to obtain the high-coercivity sintered NdFeB magnet.
Example 15:
the preparation method of the high-coercivity sintered NdFeB magnet specifically comprises the following steps:
step 1, according to weight percentage, 25.14% of Nd, 7.20% of Pr, 0.86% of B, 0.1% of Si, 0.2% of Cu, 0.08% of Al, 0.82% of Ga, 1.22% of Co and the balance of Fe are heated and melted into alloy liquid at 1400 ℃, and then the alloy liquid is poured onto a rotating copper roller with the rotating speed of 1.3m/s, so as to obtain a solidified alloy sheet with the thickness of 0.3 mm;
step 2, placing the solidified alloy sheet into a hydrogen breaking furnace for hydrogen breaking treatment, and vacuumizing the hydrogen breaking furnace to 1 multiplied by 10 after the solidified alloy sheet is placed into the hydrogen breaking furnace -2 Pa, charging argon gas to 1.3kPa, heating to 200-300 deg.C, maintaining for 3h, and vacuumizing to 1X 10 -2 Pa, recharging hydrogen to 0.25MPa, absorbing hydrogen under hydrogen pressure, and dehydrogenating at 570 ℃ to obtain coarse particles;
step 3, crushing coarse particles into alloy powder with the particle size of 4 mu m through air flow grinding, wherein the conditions of the air flow grinding are as follows: nitrogen pressure is 0.65MPa, and rotation speed is 5000 rpm;
step 4, forming alloy powder in a magnetic field of 1400KA/m to obtain a green body;
step 5, sintering the green compact in vacuum atmosphere at 1090 ℃ to obtain a sintered magnet;
and 6, performing primary tempering on the sintered magnet for 4 hours at 950 ℃ and performing secondary tempering on the sintered magnet for 6 hours at 500 ℃ to obtain the high-coercivity sintered neodymium-iron-boron magnet.
Comparative example 6:
the preparation method of the sintered NdFeB magnet specifically comprises the following steps:
step 1, heating and melting 28.4% of Nd, 7.20% of Pr, 1.05% of B, 0.12% of Si, 0.1% of Cu, 0.16% of Al, 0.85% of Ga, 0.87% of Co and the balance of Fe according to weight percentage to obtain alloy liquid with the temperature of 1400 ℃, and pouring the alloy liquid onto a rotating copper roller with the rotating speed of 1.5m/s to obtain a solidified alloy sheet with the thickness of 0.15 mm;
step 2, placing the solidified alloy sheet into a hydrogen breaking furnace for hydrogen breaking treatment, and vacuumizing the hydrogen breaking furnace to 1 multiplied by 10 after the solidified alloy sheet is placed into the hydrogen breaking furnace -2 Pa, then filling argon gas to 1kPa, heating to 200 ℃ and preserving heat for 3 hours, then vacuumizing to 1X 10 - 2 Pa, recharging hydrogen to 0.2MPa, absorbing hydrogen under hydrogen pressure, and dehydrogenating at 570 ℃ to obtain coarse particles;
step 3, grinding coarse particles into alloy powder with the particle size of 3 mu m by using an air flow, wherein the conditions of the air flow grinding are as follows: nitrogen pressure is 0.65MPa, and rotation speed is 5000 rpm;
step 4, forming alloy powder in a magnetic field of 1000KA/m to obtain a green body;
step 5, sintering the green compact in a vacuum atmosphere at 1100 ℃ to obtain a sintered magnet;
and 6, tempering the sintered magnet at 600 ℃ for 6 hours to obtain the sintered neodymium-iron-boron magnet.
The obtained sintered NdFeB magnet: br (kG): 13.25; hcj (kOe): 14.55; comprehensive magnetic properties: 27.80.
the preparation methods and specific parameter steps of comparative example 6 and example 12 are the same, and only the proportions of the raw materials are different, but the performance of the sintered neodymium-iron-boron magnet obtained in comparative example 6 is far inferior to that of the sintered neodymium-iron-boron magnet obtained in example 12.
The magnetic properties of the high coercivity sintered NdFeB magnets of examples 1-10 and comparative examples 1-5 are shown in Table 2, where 0.050< ((Nd+Pr)/143.61-2B/10.81) <0.062 (1);
(Si/28.08)/(Ga/69.72)<0.65 (2)。
TABLE 2
| Satisfying (1) | Satisfying type (2) | Br(kG) | Hcj(kOe) | Comprehensive magnetic performance | |
| Example 1 | √ | √ | 13.40 | 19.60 | 33.00 |
| Example 2 | √ | √ | 13.40 | 19.50 | 32.90 |
| Example 3 | √ | √ | 13.60 | 19.00 | 32.60 |
| Example 4 | √ | √ | 13.40 | 19.40 | 32.80 |
| Example 5 | √ | √ | 13.70 | 18.70 | 32.40 |
| Example 6 | √ | √ | 13.20 | 20.00 | 33.20 |
| Example 7 | √ | √ | 13.30 | 19.50 | 32.80 |
| Example 8 | √ | √ | 13.00 | 21.50 | 34.50 |
| Example 9 | √ | √ | 13.40 | 22.30 | 35.70 |
| Example 10 | √ | √ | 12.90 | 23.90 | 36.80 |
| Comparative example 1 | × | √ | 14.10 | 8.75 | 22.85 |
| Comparative example 2 | × | √ | 13.60 | 11.10 | 24.70 |
| Comparative example 3 | × | √ | 14.20 | 15.00 | 29.20 |
| Comparative example 4 | × | × | 13.80 | 14.70 | 28.50 |
| Comparative example 5 | × | √ | 13.40 | 16.50 | 29.90 |
It can be seen that the heavy rare earth Dy and Tb of examples 1-10 are used in small or no amount, but have a comprehensive magnetic property value of more than 32, i.e. show good remanence and intrinsic coercivity, and have good market competitiveness. Comparative examples 1 to 5 do not satisfy formula 1; comparative example 4 does not satisfy formulas 1 and 2, and the combined magnetic property value of the comparative example is less than 30.
In summary, the composition of Nd, pr, B, si, ga element is adjusted to satisfy a certain weight percentage relationship, so that the sintered neodymium-iron-boron magnet with high coercivity can be obtained under the condition of reducing rare earth elements (such as Dy). By means of the change of the components, the cost of raw materials in production can be greatly reduced, and dependence of high-quality neodymium-iron-boron magnets on a large amount of rare earth raw materials is eliminated. The preparation method of the high-coercivity sintered NdFeB magnet provided by the invention has the advantages of simple process, low equipment investment cost, no dependence on Dy addition and reduced production cost.
The foregoing description is only illustrative of the present invention and is not intended to limit the scope of the invention, and all equivalent changes made by the specification and drawings of the present invention, or direct or indirect application in the relevant art, are included in the scope of the present invention.
Claims (9)
1. The high coercivity sintered NdFeB magnet is characterized by comprising, by weight, 30.10-32.45% of R, 0.84-0.91% of B, 0.08-0.22% of Si, 0.08-0.25% of Cu, 0.08-0.20% of Al, 0.45-0.88% of Ga, 0.87-3.00% of Co and the balance of Fe; r is at least 1 element of rare earth elements and must contain Nd or Pr;
wherein, the weight percentages of the components are as follows:
0.050<((Nd+Pr)/143.61-2B/10.81)<0.062；
(Si/28.08)/(Ga/69.72) <0.65 to form a non-magnetic thin-walled grain boundary phase having a thickness of 5-15nm and (R+Cu+Ga) exceeding 75% and Fe element below 15%.
2. The high coercivity sintered neodymium-iron-boron magnet according to claim 1, characterized in that it is made of 22.16% Nd, 7.26% Pr, 2.67% Dy, 0.87% B, 0.08% Si, 0.22% Cu, 0.2% Al, 0.5% Ga, 1% Co and the balance Fe in weight percent.
3. The high coercivity sintered neodymium-iron-boron magnet according to claim 1, characterized in that it is made of 25.14% Nd, 7.20% Pr, 0.86% B, 0.1% Si, 0.2% Cu, 0.08% Al, 0.82% Ga, 1.22% Co and the balance Fe in weight percent.
4. The preparation method of the high-coercivity sintered NdFeB magnet is characterized by comprising the following steps of:
step 1, heating and melting 30.10-32.45% of R, 0.84-0.91% of B, 0.08-0.22% of Si, 0.08-0.25% of Cu, 0.08-0.20% of Al, 0.45-0.88% of Ga, 0.87-3.00% of Co and the balance of Fe into alloy liquid according to weight percentage, and pouring the alloy liquid onto a rotating copper roller to obtain a solidified alloy sheet;
step 2, performing hydrogen breaking treatment on the solidified alloy sheet to obtain coarse particles;
step 3, grinding the coarse particles into alloy powder with the particle size of 3-5 mu m through air flow;
step 4, forming alloy powder in a magnetic field of 1000-1600KA/m to obtain a green body;
step 5, sintering the green compact in a vacuum atmosphere to obtain a sintered magnet;
step 6, tempering the sintered magnet to obtain a high-coercivity sintered NdFeB magnet;
wherein, the weight percentages of the components are as follows:
0.050<((Nd+Pr)/143.61-2B/10.81)<0.062；
(Si/28.08)/(Ga/69.72) <0.65 to form a non-magnetic thin-walled grain boundary phase having a thickness of 5-15nm and (R+Cu+Ga) exceeding 75% and Fe element below 15%.
5. The method according to claim 4, wherein the temperature of the alloy liquid in the step 1 is 1300-1400 ℃, the rotational speed of the copper roller is 1.0-1.5m/s, and the thickness of the solidified alloy sheet is 0.15-5mm.
6. The method for preparing a high coercivity sintered neodymium-iron-boron magnet according to claim 4, wherein the conditions of the air-jet milling and crushing in step 3 are as follows: the nitrogen pressure is 0.5-0.65MPa, and the rotating speed is 3500-5000 rpm.
7. The method of manufacturing a high coercivity sintered neodymium-iron-boron magnet according to claim 4, where the sintering temperature in step 5 is 1000-1100 ℃.
8. The method for preparing a high coercivity sintered neodymium-iron-boron magnet according to claim 4, wherein the tempering in step 6 is specifically: the primary tempering is carried out for 2-6h at 850-950 ℃ and the secondary tempering is carried out for 2-6h at 400-600 ℃.
9. The method for preparing a high coercivity sintered neodymium-iron-boron magnet according to claim 4, wherein the tempering in step 6 is specifically: tempering is carried out at 400-600 ℃ for 2-6h.
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