CN109585109B - Mixed rare earth permanent magnet and preparation method thereof - Google Patents
Mixed rare earth permanent magnet and preparation method thereof Download PDFInfo
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- CN109585109B CN109585109B CN201811234407.5A CN201811234407A CN109585109B CN 109585109 B CN109585109 B CN 109585109B CN 201811234407 A CN201811234407 A CN 201811234407A CN 109585109 B CN109585109 B CN 109585109B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
- H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
- H01F1/047—Alloys characterised by their composition
- H01F1/053—Alloys characterised by their composition containing rare earth metals
- H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
- H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
- H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
- H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
- H01F1/0577—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together sintered
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- 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
Abstract
The invention relates to a rare earth permanent magnet for improving mixing and a preparation method thereof, belonging to the field of rare earth permanent magnet material preparation. The mixed rare earth permanent magnet is prepared by crushing a praseodymium-neodymium-rich master alloy A and a lanthanum-cerium-rich master alloy B into a praseodymium-neodymium-rich magnetic powder A and a lanthanum-cerium-rich magnetic powder B and mixing, wherein the praseodymium-neodymium-rich magnetic powder A and the lanthanum-cerium-rich magnetic powder B respectively account for 30-70% and 30-70% of the total mass of the mixed rare earth permanent magnet. According to the invention, by combining the characteristics of liquid phase sintering of the neodymium-iron-boron magnet, the fine-particle-diameter praseodymium-neodymium-rich magnetic powder and the coarse-particle-diameter lanthanum-cerium-rich magnetic powder are selected, and the compaction of the press blank prepared by molding after uniform blending is realized in the sintering process, so that the regulation and control of rare earth elements on the surface layer of the crystal grains are realized, and the comprehensive magnetic performance of the mixed rare earth permanent magnet is further improved.
Description
Technical Field
The invention relates to a mixed rare earth permanent magnet and a preparation method thereof, in particular to a rare earth permanent magnet with excellent sintering comprehensive magnetic property prepared by using mixed rare earth, belonging to the field of rare earth permanent magnet material preparation.
Background
The neodymium iron boron magnet is named as 'magawa' because of the characteristics of high coercive force and high magnetic energy product, and is a commercial magnetic material with the highest cost performance so far. With the increase of the consumption of the neodymium iron boron magnet, the critical rare earth resources praseodymium and neodymium in the material are rapidly consumed, so that the improvement of the utilization of the abundant rare earth lanthanum and cerium in the rare earth permanent magnet is particularly important from the perspective of comprehensive utilization of the rare earth resources, and meanwhile, the lanthanum and cerium exist in a form of concomitance in the nature, so that the lanthanum and cerium are required to undergo the steps of separation, refining, purification and the like when being used independently, and the pollution to the environment cannot be avoided in the series of processes. Therefore, if the co-associated lanthanum-cerium mixed rare earth can be directly used as a raw material in the development of the magnet, the method has very important significance for reducing the cost of manufacturing enterprises and reducing the energy consumption pollution of the rare earth during separation and purification.
At present, research work on lanthanum-cerium misch metal in permanent magnets has been partially progressed, and in patent application document CN1035737A, researchers use a direct smelting mode to partially replace Pr and Nd with La and Ce, so as to obtain a cheap Nd- (La, Ce) -Fe-B magnet, but the magnet performance is obviously deteriorated; in patent application document CN103123838A, researchers perform grain boundary nano modification on a lanthanum-containing mischmetal magnet, which improves the magnetic properties of the magnet to a certain extent, and this method is widely used in sintered magnets at present. In a sintered magnet made by taking reverse domain nucleation as a coercive machine, a defect area on the surface layer of a crystal grain is generally considered as a weak magnetic area which is firstly nucleated, so that the coercive force of the magnet can be greatly improved by hard magnetization of the surface layer of the crystal grain, and the nucleation of a reverse magnetized domain is inhibited.
Disclosure of Invention
The invention aims to provide a rare earth permanent magnet with excellent comprehensive magnetic property and a preparation method for producing a high-performance sintered rare earth permanent magnet by using mixed rare earth aiming at the existing problems.
In order to achieve the purpose, the invention comprises the following technical scheme: the mixed rare earth permanent magnet is prepared by crushing a praseodymium-neodymium-rich master alloy A and a lanthanum-cerium-rich master alloy B into a praseodymium-neodymium-rich magnetic powder A and a lanthanum-cerium-rich magnetic powder B and mixing, wherein the praseodymium-neodymium-rich magnetic powder A and the lanthanum-cerium-rich magnetic powder B respectively account for 30-70% and 30-70% of the total mass of the mixed rare earth permanent magnet.
In the above-mentioned mixed rare earth permanent magnet, the chemical formula of praseodymium-neodymium-rich master alloy A [ (Pr)rNd1-r)]aTmbBcFe1-a-b-cWherein r is more than or equal to 0 and less than or equal to 1, a is more than or equal to 28 and less than or equal to 33, b is more than or equal to 0 and less than or equal to 5, and c is more than or equal to 0.85 and less than or equal to 1.5 in mass fraction; the chemical molecular formula of the mother alloy B rich in lanthanum and cerium is [ (Pr)rNd1-r)xMM1-x)]aTmbBcFe1-a-b-cIn terms of mass fraction, r is more than or equal to 0 and less than or equal to 1, x is more than or equal to 0 and less than or equal to 1, a is more than or equal to 28 and less than or equal to 33, b is more than or equal to 0 and less than or equal to 5, c is more than or equal to 0.85 and less than or equal to 1.5, MM is one of La, Ce and lanthanum-cerium mixed rare earth, and Tm is one or more of Ga, Co, Cu, Nb, Al and Zr; x represents the mass fraction of the high-abundance rare earth alloy replacing Pr and Nd rare earth alloys.
The invention also provides a method for preparing the mixed rare earth permanent magnet, which comprises the following steps:
1): chemical molecular formula of praseodymium-neodymium-rich master alloy A [ (Pr)rNd1-r)]aTmbBcFe1-a-b-cWherein r is more than or equal to 0 and less than or equal to 1, a is more than or equal to 28 and less than or equal to 33, B is more than or equal to 0 and less than or equal to 5, c is more than or equal to 0.85 and less than or equal to 1.5, and the chemical molecular formula of the mother alloy B rich in lanthanum and cerium is [ (Pr)rNd1-r)xMM1-x)]aTmbBcFe1-a-b-cIn terms of mass fraction, r is more than or equal to 0 and less than or equal to 1, x is more than or equal to 0 and less than or equal to 1, a is more than or equal to 28 and less than or equal to 33, b is more than or equal to 0 and less than or equal to 5, c is more than or equal to 0.85 and less than or equal to 1.5, MM is lanthanum-cerium mixed rare earth or one of La and Ce, and Tm is one or more of Ga, Co, Cu, Nb, Al and Zr; x represents the mass fraction of the high-abundance rare earth alloy replacing Pr and Nd rare earth alloys;
2): polishing the proportioned master alloy A rich in praseodymium and neodymium and the master alloy B rich in lanthanum and cerium, then putting the polished master alloy A and the master alloy B into a rapid hardening furnace for smelting, and respectively obtaining a rapid hardening sheet A and a rapid hardening sheet B through a rapid hardening process;
3): respectively placing the quick-setting sheet A and the quick-setting sheet B in a hydrogen breaking furnace, charging hydrogen for breaking to respectively obtain coarse broken powder, then continuously breaking the coarse broken powder in a nitrogen-protected airflow mill, and adjusting the rotating speed and the oxygen content of a sorting wheel to obtain magnetic powder A with the average particle size of 0.5-2.0 mu m and magnetic powder B with the average particle size of 2.5-3.2 mu m;
4): uniformly mixing the magnetic powder A and the magnetic powder B, then orienting and molding in a magnetic field to obtain a blank magnet, and carrying out isostatic pressing treatment in an oil press after vacuum packaging;
5): and sintering the blank magnet after isostatic pressing treatment in a vacuum sintering furnace, and then performing heat treatment to obtain the mixed rare earth permanent magnet.
The crystal grain A of the praseodymium-neodymium-rich crystal grain has high surface activity, so that the crystal grain A is dissolved in a liquid phase in the sintering process, element diffusion and material migration occur under the action of high temperature, and then when the solubility of the crystal grain in the liquid phase exceeds the saturation degree, the crystal grain A is separated out on the surface layer of the coarse crystal grain to form a praseodymium-neodymium-rich shell layer with high anisotropy field, so that the regulation and control of rare earth elements on the surface layer of the crystal grain are realized, and finally the improvement of the magnetic performance of the magnet is realized.
In the method for preparing the mixed rare earth permanent magnet, the smelting temperature in the step 2) is 1300-1450 ℃, and the rotating speed of a copper roller during smelting is 1.0-1.5 m/s.
In the method for preparing the mixed rare earth permanent magnet, the average thickness of the quick-setting sheet A and the average thickness of the quick-setting sheet B in the step 2) are both 0.2-0.4 mm.
In the method for preparing the mixed rare earth permanent magnet, the airflow milling process of the quick-setting sheet A in the step 3): the rotating speed of a sorting wheel is 4800-6000 rad/min, and the oxygen content is 30-40 ppm; and in the airflow milling process of the quick setting sheet B, the rotating speed of a sorting wheel is 2400-3600 rad/min, and the oxygen content is 20-30 ppm.
In the method for preparing the mixed rare earth permanent magnet, in the step 4), the magnetic powder A and the magnetic powder B respectively account for 30-70% and 30-70% of the total mass of the magnetic powder A and the magnetic powder B.
In the method for preparing the mixed rare earth permanent magnet, the sintering temperature in the step 5) is 950-1050 ℃, and the sintering time is 1-6 hours. If the proportion of the fine-particle-diameter magnetic powder A in the mixed magnetic powder is high, the sintering temperature of the magnet is low, and if the proportion of the coarse-particle-diameter magnetic powder B in the mixed magnetic powder is high, the sintering temperature of the magnet is high; and the sintering process is accompanied with element migration and substance diffusion, so the invention carries out sintering treatment at 950-1050 ℃.
In the method for preparing the mixed rare earth permanent magnet, the tempering temperature of the heat treatment in the step 5) is 400-800 ℃, and the tempering time is 1-6 hours.
The preparation process of the traditional sintered magnet generally comprises smelting, hydrogen breaking, airflow milling, orientation forming and sintering heat treatment. According to the invention, by combining the characteristic of liquid phase sintering of the neodymium-iron-boron magnet, the fine-grain-diameter praseodymium-neodymium-rich magnetic powder and the coarse-grain-diameter lanthanum-cerium-rich magnetic powder are selected, and the compaction is realized in the sintering process of the blank prepared by molding after uniform blending.
Drawings
Fig. 1 is a microscopic topography and line scanning elemental analysis spectrum (la-ce-rich in the center region of the grain, pr-nd-rich in the edge region of the grain) of the magnet of example 2 of the present invention.
Detailed Description
The following is a description of specific embodiments of the present invention with reference to the drawings, and the technical solutions of the present invention will be further described, but the present invention is not limited to these embodiments.
Example 1
1): chemical molecular formula of praseodymium-neodymium-rich master alloy A [ (Pr)0.2Nd0.8)]30.5Al0.2Cu0.2Ga0.2B1Fe67.9The chemical formula of the mother alloy B rich in lanthanum and cerium is [ (Pr)0.2Nd0.8)0.5Ce0.5)]30.5Al0.2Cu0.2Ga0.2B1Fe67.9In terms of mass fraction.
2): polishing the proportioned raw materials, putting the polished raw materials into a rapid hardening furnace, smelting praseodymium-neodymium-rich master alloy A at 1420 ℃, keeping the rotating speed of a copper roller at 1.2m/s during smelting, and obtaining the master alloy A rapid hardening sheet with the average thickness of 0.2-0.4 mm through a rapid hardening process; similarly, smelting the mother alloy B rich in lanthanum and cerium at 1350 ℃, wherein the rotating speed of a copper roller is kept at 1.2m/s during smelting, and the average thickness of the rapidly solidified sheet of the mother alloy B is finally within the range of 0.2-0.4 mm.
3): respectively placing the obtained quick-setting sheet A and the quick-setting sheet B in a hydrogen breaking furnace, charging hydrogen for crushing to obtain coarse crushed powder, then respectively continuously crushing the obtained coarse crushed powder in a jet mill protected by nitrogen, adjusting the rotating speed of a sorting wheel to 4800rad/min, and adjusting the oxygen content to 30ppm to obtain jet mill magnetic powder A with the average particle size of 2.0 mu m; the rotating speed of the sorting wheel is adjusted to 3600rad/min, the oxygen content is 20ppm, and the jet mill magnetic powder B with the average grain diameter of 3.2 mu m is obtained.
4): grinding with air flow to obtain magnetic powder A with fine particle diameter and magnetic powder B with coarse particle diameterA:mBUniformly mixing the components 6:4, then performing orientation forming in a magnetic field to obtain a blank magnet, performing vacuum packaging on the obtained blank magnet, and performing isostatic pressing treatment in an oil press.
5): sintering the blank magnet after isostatic pressing treatment in a vacuum sintering furnace to obtain a mixed rare earth permanent magnet; wherein the sintering process parameters are as follows: sintering at 1020 ℃ for 4 hours, and carrying out heat treatment on the obtained sintered magnet: the tempering temperature is 600 ℃, and the tempering time is 4 hours.
Comparative example 1
1): the specific components of example 1, mixed with mA, mB, 6:4, were weighed: [ (Pr)0.2Nd0.8)0.8Ce0.2]30.5Al0.2Cu0.2Ga0.2B1Fe67.9In terms of mass fraction.
2): and polishing the proportioned raw materials, putting the grinded raw materials into a rapid hardening furnace, smelting at 1400 ℃, keeping the rotating speed of a copper roller at 1.2m/s during smelting, and obtaining the alloy rapid hardening sheet with the average thickness of 0.2-0.4 mm through a rapid hardening process.
3): and placing the obtained quick-setting sheet in a hydrogen breaking furnace, filling hydrogen for breaking to obtain coarse broken powder, continuing breaking the obtained coarse broken powder in a jet mill protected by nitrogen, adjusting the rotating speed of a sorting wheel to 4000rad/min, and adjusting the oxygen content to 30ppm to obtain jet mill magnetic powder with the average particle size of 2.8 mu m.
4): the jet mill magnetic powder was made into a magnet according to steps 4) and 5) in the examples.
The magnets prepared in example 1 and comparative example 1 were compared in terms of performance, and the results are as follows:
| Br/kGs | Hcj/kOe | (BH)max/MGOe | |
| example 1 | 13.34 | 13.58 | 44.12 |
| Comparative example 1 | 13.33 | 12.16 | 43.21 |
Example 2
1): chemical molecular formula of praseodymium-neodymium-rich master alloy A [ (Pr)0.2Nd0.8)]30.5Al0.2Cu0.2Ga0.2B1Fe67.9The chemical formula of the mother alloy B rich in lanthanum and cerium is [ (Pr)0.2Nd0.8)0.5(La0.3Ce0.7)0.5]30.5Al0.2Cu0.2Ga0.2B1Fe67.9In terms of mass fraction.
2): polishing the proportioned raw materials, putting the polished raw materials into a rapid hardening furnace, smelting a master alloy A at 1420 ℃, keeping the rotating speed of a copper roller at 1.2m/s during smelting, and obtaining a master alloy A rapid hardening sheet with the average thickness of 0.2-0.4 mm through a rapid hardening process; similarly, the master alloy B is smelted at 1380 ℃, the rotation speed of a copper roller is kept at 1.2m/s during smelting, and the average thickness of the rapidly solidified sheet of the master alloy B finally obtained is in the range of 0.2-0.4 mm.
3): respectively placing the obtained quick-setting sheet A and the quick-setting sheet B in a hydrogen breaking furnace, filling hydrogen for crushing to obtain coarse crushed powder, then respectively continuously crushing the obtained coarse crushed powder in a nitrogen-protected airflow mill, and adjusting the rotating speed and the oxygen content of a sorting wheel to respectively obtain airflow mill magnetic powder A with the average particle size of 0.5-1.8 mu m and airflow mill magnetic powder B with the average particle size of 2.5-3.2 mu m; the airflow milling process of the quick setting sheet A comprises the following steps: the rotating speed of a sorting wheel is 5500rad/min, and the oxygen content is 38 ppm; and (3) an air flow milling process of the quick setting sheet B, wherein the rotating speed of a sorting wheel is 2800rad/min, and the oxygen content is 28 ppm.
4): grinding with air flow to obtain magnetic powder A with fine particle diameter and magnetic powder B with coarse particle diameterA:mBUniformly mixing the components 6:4, then performing orientation forming in a magnetic field to obtain a blank magnet, performing vacuum packaging on the obtained blank magnet, and performing isostatic pressing treatment in an oil press.
5): sintering the blank magnet after isostatic pressing treatment in a vacuum sintering furnace to obtain a mixed rare earth permanent magnet; wherein the sintering process parameters are as follows: the sintering temperature is 980 ℃, the sintering time is 5 hours, the obtained sintered magnet is subjected to heat treatment, and the technological parameters of the tempering heat treatment are as follows: the tempering temperature is 500 ℃, and the tempering time is 3 hours.
Fig. 1 shows a microscopic topography and a line scan elemental analysis spectrum (la-rich cerium in the center region of the grain, and pr-rich neodymium in the edge region of the grain) of the magnet prepared in example 2. The region from the dotted line of the outer circle to the dotted line of the inner circle in the figure represents the edge region of the crystal grain, and the right element energy spectrum analysis graph shows that the edge region is rich in praseodymium and neodymium, so that the surface layer has higher anisotropy field and saturation magnetization intensity locally, and the magnet has more excellent comprehensive magnetic performance.
Comparative example 2
The specific components of the mixture of mA, mB and 6:4 in example 2 are weighed: [ (Pr)0.2Nd0.8)0.5La0.06Ce0.14]30.5Al0.2Cu0.2Ga0.2B1Fe67.9In terms of mass fraction; and a magnet was produced in the same manner as in comparative example 1.
The prepared magnets of example 2 and comparative example 2 were placed in a closed-circuit type NIM-500C permanent magnet material measurement system for testing, and the following results of magnetic properties were obtained:
| Br/kGs | Hcj/kOe | (BH)max/MGOe | |
| example 2 | 13.26 | 12.66 | 43.54 |
| Comparative example 2 | 13.28 | 11.23 | 41.32 |
Example 3
1): chemical molecular formula of praseodymium-neodymium-rich master alloy A [ (Pr)0.5Nd0.5)]30.5Al0.2Cu0.2Ga0.2B1Fe67.9The chemical formula of the mother alloy B rich in lanthanum and cerium is [ (Pr)0.5Nd0.5)0.5Ce0.5]30.5Al0.2Cu0.2Ga0.2B1Fe67.9In terms of mass fraction.
2): polishing the proportioned raw materials, putting the polished raw materials into a rapid hardening furnace, smelting a master alloy A at 1450 ℃, keeping the rotating speed of a copper roller at 1.2m/s during smelting, and obtaining a master alloy A rapid hardening sheet with the average thickness of 0.2-0.4 mm through a rapid hardening process; similarly, smelting the master alloy B quick-setting sheet at 1350 ℃, and keeping the rotating speed of a copper roller at 1.2m/s during smelting to finally obtain the master alloy B quick-setting sheet with the average thickness within the range of 0.2-0.4 mm.
3): respectively placing the obtained quick-setting sheet A and the quick-setting sheet B in a hydrogen breaking furnace, charging hydrogen for crushing to obtain coarse crushed powder, then respectively continuously crushing the obtained coarse crushed powder in a jet mill protected by nitrogen, adjusting the rotating speed of a sorting wheel to 4800rad/min, and adjusting the oxygen content to 30ppm to obtain jet mill magnetic powder A with the average particle size of 2.0 mu m; the rotating speed of the sorting wheel is adjusted to 3600rad/min, the oxygen content is 20ppm, and the jet mill magnetic powder B with the average grain diameter of 3.2 mu m is obtained.
4): grinding with air flow to obtain magnetic powder A with fine particle diameter and magnetic powder B with coarse particle diameterA:mBUniformly mixing the components 6:4, then performing orientation forming in a magnetic field to obtain a blank magnet, performing vacuum packaging on the obtained blank magnet, and performing isostatic pressing treatment in an oil press.
5): sintering the blank magnet after isostatic pressing treatment in a vacuum sintering furnace to obtain a mixed rare earth permanent magnet; wherein the sintering process parameters are as follows: sintering at 1050 ℃ for 5 hours, and carrying out heat treatment on the obtained sintered magnet, wherein the technological parameters of the tempering heat treatment are as follows: the tempering temperature is 800 ℃, and the tempering time is 2 hours.
Comparative example 3
The specific components of the mixture of mA, mB and 6:4 in example 3 are weighed as follows: [ (Pr)0.2Nd0.8)0.8Ce0.2]30.5Al0.2Cu0.2Ga0.2B1Fe67.9In terms of mass fraction; and a magnet was produced in the same manner as in comparative example 1.
The magnets of example 3 and comparative example 3 were placed in a closed NIM-500C permanent magnet material measurement system for testing, and the following magnetic performance results were obtained:
| Br/kGs | Hcj/kOe | (BH)max/MGOe | |
| example 3 | 13.29 | 13.76 | 44.15 |
| Comparative example 3 | 13.33 | 12.16 | 43.21 |
Example 4
1): chemical molecular formula of praseodymium-neodymium-rich master alloy A [ (Pr)0.5Nd0.5)]30.5Al0.2Cu0.2Ga0.2B1Fe67.9The chemical formula of the mother alloy B rich in lanthanum and cerium is [ (Pr)0.5Nd0.5)0.5(La0.3Ce0.7)0.5]30.5Al0.2Cu0.2Ga0.2B1Fe67.9In terms of mass fraction.
2): polishing the proportioned raw materials, putting the polished raw materials into a rapid hardening furnace, smelting a master alloy A at 1420 ℃, keeping the rotating speed of a copper roller at 1.2m/s during smelting, and obtaining a master alloy A rapid hardening sheet with the average thickness of 0.2-0.4 mm through a rapid hardening process; similarly, the master alloy B quick-setting piece is smelted at 1380 ℃, the rotating speed of a copper roller is kept at 1.2m/s during smelting, and the average thickness of the finally obtained master alloy B quick-setting piece is within the range of 0.2-0.4 mm.
3): respectively placing the obtained quick-setting sheet A and the quick-setting sheet B in a hydrogen breaking furnace, charging hydrogen for crushing to obtain coarse crushed powder, then respectively continuously crushing the obtained coarse crushed powder in a jet mill protected by nitrogen, adjusting the rotating speed of a sorting wheel to 4800rad/min, and adjusting the oxygen content to 30ppm to obtain jet mill magnetic powder A with the average particle size of 2.0 mu m; the rotating speed of the sorting wheel is adjusted to 3600rad/min, the oxygen content is 20ppm, and the jet mill magnetic powder B with the average grain diameter of 3.2 mu m is obtained.
4): grinding with air flow to obtain magnetic powder A with fine particle diameter and magnetic powder B with coarse particle diameterA:mBUniformly mixing the components 6:4, then performing orientation forming in a magnetic field to obtain a blank magnet, performing vacuum packaging on the obtained blank magnet, and performing isostatic pressing treatment in an oil press.
5): sintering the blank magnet after isostatic pressing treatment in a vacuum sintering furnace to obtain a mixed rare earth permanent magnet; wherein the sintering process parameters are as follows: sintering at 950 ℃ for 5 hours, and carrying out heat treatment on the obtained sintered magnet, wherein the technological parameters of the tempering heat treatment are as follows: the tempering temperature is 400 ℃, and the tempering time is 6 hours.
Comparative example 4
The specific components of the mixture of mA, mB and 6:4 in example 4 are weighed as follows: [ (Pr)0.2Nd0.8)0.8(La0.3Ce0.7)0.2]30.5Al0.2Cu0.2Ga0.2B1Fe67.9In terms of mass fraction; and a magnet was produced in the same manner as in comparative example 1.
The magnets of example 3 and comparative example 3 were placed in a closed-circuit NIM-500C permanent magnet material measurement system and tested, and the magnetic performance results were as follows:
| Br/kGs | Hcj/kOe | (BH)max/MGOe | |
| example 4 | 13.26 | 12.04 | 42.17 |
| Comparative example 4 | 13.28 | 11.23 | 41.32 |
In conclusion, the invention combines the characteristics of liquid phase sintering of the neodymium-iron-boron magnet, selects the fine-particle-diameter neodymium-rich magnetic powder and the coarse-particle-diameter lanthanum-cerium-rich magnetic powder, and realizes densification of the pressed blank prepared by molding after uniform blending in the sintering process, thereby realizing the regulation and control of rare earth elements on the surface layer of crystal grains and further improving the comprehensive magnetic performance of the mixed rare earth permanent magnet.
In addition, the technical scope of the invention is not exhaustive, and new technical solutions formed by equivalent replacement of single or multiple technical features in the embodiment technical solutions are also within the scope of the invention; meanwhile, in all the embodiments of the invention, which are listed or not listed, each parameter in the same embodiment represents only one example (i.e., a feasible solution) of the technical scheme.
The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.
While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.
Claims (1)
1. A mixed rare earth permanent magnet is characterized in that the mixed rare earth permanent magnet is prepared by crushing a praseodymium-neodymium-rich master alloy A and a lanthanum-cerium-rich master alloy B into praseodymium-neodymium-rich magnetic powder A and lanthanum-cerium-rich magnetic powder B and mixing; the preparation method of the mixed rare earth permanent magnet comprises the following steps:
1): chemical molecular formula of praseodymium-neodymium-rich master alloy A [ (Pr)0.2Nd0.8)]30.5Al0.2Cu0.2Ga0.2B1Fe67.9The chemical formula of the mother alloy B rich in lanthanum and cerium is [ (Pr)0.2Nd0.8)0.5(La0.3Ce0.7)0.5]30.5Al0.2Cu0.2Ga0.2B1Fe67.9In terms of mass fraction;
2): polishing the proportioned raw materials, putting the polished raw materials into a rapid hardening furnace, smelting a master alloy A at 1420 ℃, keeping the rotating speed of a copper roller at 1.2m/s during smelting, and obtaining a master alloy A rapid hardening sheet with the average thickness of 0.2-0.4 mm through a rapid hardening process; similarly, smelting the master alloy B at 1380 ℃, wherein the rotating speed of a copper roller is kept at 1.2m/s during smelting, and the average thickness of the rapidly solidified sheet of the master alloy B is in the range of 0.2-0.4 mm;
3): respectively placing the obtained quick-setting sheet A and the quick-setting sheet B in a hydrogen breaking furnace, filling hydrogen for crushing to obtain coarse crushed powder, then respectively continuously crushing the obtained coarse crushed powder in a nitrogen-protected airflow mill, and adjusting the rotating speed and the oxygen content of a sorting wheel to respectively obtain airflow mill magnetic powder A with the average particle size of 0.5-1.8 mu m and airflow mill magnetic powder B with the average particle size of 2.5-3.2 mu m; the airflow milling process of the quick setting sheet A comprises the following steps: the rotating speed of a sorting wheel is 5500rad/min, and the oxygen content is 38 ppm; the air flow milling process of the quick setting sheet B is that the rotating speed of a sorting wheel is 2800rad/min, and the oxygen content is 28 ppm;
4): grinding with air flow to obtain magnetic powder A with fine particle diameter and magnetic powder B with coarse particle diameterA:mBUniformly mixing the components 6:4, then performing orientation forming in a magnetic field to obtain a blank magnet, performing vacuum packaging on the obtained blank magnet, and performing isostatic pressing treatment in an oil press;
5): sintering the blank magnet after isostatic pressing treatment in a vacuum sintering furnace to obtain a mixed rare earth permanent magnet; wherein the sintering process parameters are as follows: the sintering temperature is 980 ℃, the sintering time is 5 hours, the obtained sintered magnet is subjected to heat treatment, and the technological parameters of the tempering heat treatment are as follows: the tempering temperature is 500 ℃, the tempering time is 3 hours, and the mixed rare earth permanent magnet is obtained.
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| CN113035482A (en) * | 2021-04-23 | 2021-06-25 | 宁波佳丰磁材科技有限公司 | Double-alloy neodymium-iron-boron magnet and preparation method thereof |
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| JPH0945567A (en) * | 1995-07-27 | 1997-02-14 | Hitachi Metals Ltd | Rare earth-iron-boron permanent magnet manufacturing method |
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| CN104252937B (en) * | 2014-09-12 | 2016-10-05 | 沈阳中北通磁科技股份有限公司 | A kind of regulate and control the sintered NdFeB permanent magnet ferrum of particulate combinations and manufacture method |
| CN104700973B (en) * | 2015-03-05 | 2017-07-04 | 内蒙古科技大学 | A kind of rare-earth permanent magnet being made up of the common association raw ore mischmetal of Bayan Obo and preparation method thereof |
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| JP2023043831A (en) * | 2021-09-16 | 2023-03-29 | 煙台東星磁性材料株式有限公司 | METHOD OF MANUFACTURING LaCe-ADDED Pr Nd-Fe-B BASED SINTERED MAGNETIC MATERIAL |
| JP7414384B2 (en) | 2021-09-16 | 2024-01-16 | 煙台東星磁性材料株式有限公司 | Method for manufacturing LaCe-added Pr/Nd-Fe-B sintered magnetic material |
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