CN118116680A - High-magnetic energy product low-temperature coefficient sintered rare earth permanent magnet material and preparation method thereof - Google Patents

High-magnetic energy product low-temperature coefficient sintered rare earth permanent magnet material and preparation method thereof Download PDF

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CN118116680A
CN118116680A CN202311698177.9A CN202311698177A CN118116680A CN 118116680 A CN118116680 A CN 118116680A CN 202311698177 A CN202311698177 A CN 202311698177A CN 118116680 A CN118116680 A CN 118116680A
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rare earth
permanent magnet
magnet material
phase
earth permanent
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黄敏
丁勇
王春国
刘雷
周波
孙颖莉
闫阿儒
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Ningbo Institute of Material Technology and Engineering of CAS
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Ningbo Institute of Material Technology and Engineering of CAS
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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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    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/02—Making ferrous alloys by powder metallurgy
    • C22C33/0257—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements
    • C22C33/0278—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5%
    • C22C33/0285—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5% with Cr, Co, or Ni having a minimum content higher than 5%
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/10—Ferrous alloys, e.g. steel alloys containing cobalt
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
    • 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
    • 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

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Abstract

The invention relates to a high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material and a preparation method thereof, belonging to the technical field of rare earth permanent magnet materials. The invention discloses a high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material, which comprises the following components in percentage by weight: LRE: 20-32%, HRE:1 to 6 percent of Co: 19-25%, B:0.9 to 1.2 percent, cu: 0-1%, al: 0-1%, zr: 0-1%, and the balance being Fe; LRE is one or two of light rare earth Pr and Nd; HRE is one or more of heavy rare earth Gd, tb, dy, ho; the high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material comprises a main phase and a grain boundary phase, wherein the main phase has a core-shell structure, and the thickness of a shell layer of the main phase with the core-shell structure is reduced along with the increase of the surface distance from the sintered rare earth permanent magnet material in a region of 0-500 mu m of inward radiation of the surface layer of the sintered rare earth permanent magnet material; the cobalt-rich iron-rich rare earth-rich phase in the grain boundary phase accounts for more than 70% of the total mass of the components in the grain boundary phase.

Description

High-magnetic energy product low-temperature coefficient sintered rare earth permanent magnet material and preparation method thereof
Technical Field
The invention belongs to the technical field of rare earth permanent magnet materials, and relates to a high-magnetic energy product low-temperature coefficient sintered rare earth permanent magnet material and a preparation method thereof.
Background
Since the advent of Nd-Fe-B magnets in 1984, the use of sintered Nd-Fe-B magnets has rapidly expanded to various fields. The maximum magnetic energy product of the neodymium-iron-boron rare earth permanent magnet material can reach more than 54MGOe, which is the intactly-known magnetic king. However, the Curie temperature is relatively low (generally not more than 360 ℃), the temperature stability is relatively poor (the remanence temperature coefficient is between-0.09 and-0.12%/DEG C), and the requirements of many high-temperature fields are difficult to meet. In order to better meet the requirements of core control devices in the fields of electric automobiles, wind power generation, nuclear energy application, aerospace and the like on performance stability, reliability and high heat resistance indexes of rare earth permanent magnet materials, main factors and action rules affecting the thermal stability of magnets are researched, and the method has important academic significance and practical value.
In the current market, a typical method for improving the service temperature of the neodymium-iron-boron magnet is to add heavy rare earth dysprosium or terbium to greatly improve the coercive force of the magnet, so that the magnet can still keep strong demagnetizing resistance at a higher service temperature. Although the temperature stability of the high-coercivity magnet is improved to a certain extent, the Curie temperature is not improved obviously, the magnetic performance is reduced relatively quickly along with the temperature rise, and the temperature stability is poor.
Therefore, how to obtain a magnet with higher magnetic energy product and good temperature stability, and expand the application field of neodymium iron boron is a difficulty in current work.
Disclosure of Invention
Aiming at the problems existing in the prior art, the invention provides a high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material with a main phase and a grain boundary phase, wherein the cobalt-rich iron-rich rare earth-rich phase in the grain boundary phase occupies a larger proportion, so that a lower residual magnetic temperature coefficient is ensured; and the coercivity is optimized by grain boundary diffusion.
The aim of the invention can be achieved by the following technical scheme:
The sintered rare earth permanent magnet material with high magnetic energy product and low temperature coefficient comprises the following components in percentage by weight: LRE: 20-32%, HRE:1 to 6 percent of Co: 19-25%, B:0.9 to 1.2 percent, cu: 0-1%, al: 0-1%, zr: 0-1%, and the balance being Fe;
LRE is one or two of light rare earth Pr and Nd;
HRE is one or more of heavy rare earth Gd, tb, dy, ho;
the high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material comprises a main phase and a grain boundary phase, wherein the grain boundary phase isolates and/or coats the main phase;
The main phase is provided with a core-shell structure, the core-shell structure comprises an inner core and a shell layer, and the shell layer is positioned on the outer side of the main phase;
In the area of 0-500 mu m of inward radiation of the surface layer of the sintered rare earth permanent magnet material, the thickness of the shell layer of the main phase with the core-shell structure is reduced along with the increase of the distance between the surface layer of the sintered rare earth permanent magnet material and the surface layer of the sintered rare earth permanent magnet material;
the grain boundary phase includes a rare earth-rich phase and a very small amount of a boron-rich phase, the rare earth-rich phase including an iron-poor cobalt-poor rare earth-rich phase and a cobalt-rich iron-rich rare earth-rich phase, the cobalt-rich iron-rich rare earth-rich phase accounting for 70% or more of the total mass of the grain boundary phase components.
The cobalt-rich iron-rich rare earth-rich phase in the magnet has high proportion in the grain boundary phase, and the high cobalt content in the main phase can ensure a lower residual magnetism temperature coefficient.
The distribution depth of the main phase with the core-shell structure on the surface of the magnet is large, so that the coercivity of the magnet is improved; and the thickness of the shell layer is decreased along with the increase of the distribution depth, so that the magnet is beneficial to ensuring enough high remanence and high magnetic energy product.
The wettability of the grain boundary phase is related to the components of the grain boundary phase, and the higher wettability is beneficial to grain boundary diffusion.
Preferably, the Cu+Al is more than or equal to 0.2% and less than or equal to 0.4%; the content of Cu+Al+Zr is more than or equal to 0.3% and less than 0.6%.
Preferably, the main phase is RE (Fe, co): B=2:14:1 structure main phase crystal grain, RE includes light rare earth LRE and heavy rare earth HRE.
Preferably, the main phase accounts for 92-96% of the total mass of the sintered rare earth permanent magnet material.
Preferably, the mass of the heavy rare earth in the shell layer of the main phase accounts for 0.01-2% of the total mass of the sintered rare earth permanent magnet material.
Preferably, the cobalt content of the cobalt-rich iron-rich rare earth-rich phase in the grain boundary phase is higher than that of the high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material;
The cobalt content of the rare earth phase with poor iron and poor cobalt in the grain boundary phase is far lower than that of the sintered rare earth permanent magnet material with high magnetic energy product and low temperature coefficient;
The cobalt content of the core of the main phase is slightly higher than or close to that of the high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material;
the cobalt content of the shell layer of the main phase is slightly higher than or close to that of the high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material.
Preferably, the high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material comprises the following components in percentage by weight: LRE aHREbCocMdBeFe1-a-b-c-d-e;
LRE is one or two of light rare earth Pr and Nd;
HRE is one or more of heavy rare earth Gd, tb, dy, ho;
M is one or more of Cu, al and Zr;
20％≤a≤32％，1％≤b≤6％，19％≤c≤25％，0％≤d≤3％，0.9％≤e≤1.2％。
preferably, the shell layer of the main phase comprises the following components in percentage by weight: LRE fHREgCohBiFe1-f-g-h-i;
LRE is one or two of light rare earth Pr and Nd;
HRE is one or more of heavy rare earth Gd, tb, dy, ho;
15％≤f≤22％，6％≤g≤9％，19％≤h≤25％，0.9％≤i≤1.2％，50％≤1-f-g-h-i≤55％。
preferably, the core component of the main phase comprises the following components in percentage by weight: LRE kHREmConBpFe1-k-m-n-p;
LRE is one or two of light rare earth Pr and Nd;
HRE is one or more of heavy rare earth Gd, tb, dy, ho;
18％≤k≤28％，1％≤m≤5％，19％≤n≤25％，0.9％≤p≤1.2％，50％≤1-k-m-n-p≤55％。
Preferably, the components of the lean iron, lean cobalt and rich rare earth phase in the grain boundary phase are as follows in percentage by weight: LRE rHREsCotMuOvFe1-r-s-t-u-v;
LRE is one or two of light rare earth Pr and Nd;
HRE is one or more of heavy rare earth Gd, tb, dy, ho;
M is one or more of Cu, al and Zr;
60％≤r≤85％，0％≤s≤25％，0％≤t≤14％，0％≤u≤3％，0％≤v≤1.3％，2％≤1-r-s-t-u-v≤10％。
Preferably, the components of the cobalt-rich, iron-rich and rare earth-rich phase in the grain boundary phase are as follows in percentage by weight: LRE wHRExCoyMzFe1-w-x-y-z;
LRE is one or two of light rare earth Pr and Nd;
HRE is one or more of heavy rare earth Gd, tb, dy, ho;
M is one or more of Cu, al and Zr;
40％≤w≤60％，0％≤x≤8％，22％≤y≤30％，0％≤z≤3％，20％≤1-w-x-y-z≤30％。
preferably, the rare earth content in the shell layer of the main phase is 1.0 to 1.5 times of the rare earth content in the core of the main phase.
Preferably, the HRE content of the main phase shell layer is 2.2-2.9 times of that of the main phase core.
Preferably, the cobalt-rich iron-rich rare earth-rich phase (Fe, co) RE atomic ratio is (2-3.5): 1.
In one embodiment of the present invention, the shell component of the main phase is Nd 14.0Pr4.6Tb8.5Co20. 5Fe51.3B1.1 by weight; the core component of the main phase is Nd 17.5Pr5.8Tb3.0Co21.0Fe51.7B1.0 in percentage by weight.
In one embodiment of the invention, the composition of the lean iron, cobalt and rare earth-rich phase in the grain boundary phase is Nd 49.9Pr31.5Co13.9Fe3.2O0.9Cu0.6 in percentage by weight; the components of the cobalt-rich iron-rich rare earth-rich phase in the grain boundary phase are Nd 32.1Pr13.3Tb5.8Co25.5Fe21.9Zr1.4 in percentage by weight.
Preferably, the thickness of the sintered rare earth permanent magnet material is 1-10 mm; the average size of the main phase is 1-10 mu m, and the thickness of the shell layer of the main phase is less than or equal to 6 mu m.
Further preferably, the thickness of the sintered rare earth permanent magnetic material is 6-9 mm; the size of the main phase is 4-8 mu m, and the thickness of a shell layer of the main phase is less than or equal to 4 mu m;
still more preferably, the size of the main phase is 5 μm, and the shell thickness of the main phase is 4 μm or less;
the main phase with the core-shell structure is distributed in a region of 0-500 mu m of inward radiation on the surface layer of the sintered rare earth permanent magnet material;
the thickness of the shell layer is 3-4 mu m in the area of 0-100 mu m of inward radiation of the surface layer of the sintered rare earth permanent magnet material;
The thickness of the shell layer is 1-3 mu m in the area of the surface layer of the sintered rare earth permanent magnet material radiating inwards by 100-300 mu m;
The thickness of the shell layer is 0.01-1 mu m in the area of the surface layer of the sintered rare earth permanent magnet material radiating inwards by 300-500 mu m;
The thickness contrast of the shell layer is not obvious in the area of the surface layer of the sintered rare earth permanent magnet material which radiates inwards by more than 500 mu m.
A method for preparing a high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material, comprising the following steps: proportioning, smelting, coarse grinding, fine grinding, magnetic field forming, sintering and grain boundary diffusion; and (3) performing magnetic field molding to obtain a green body, and diffusing the grain boundary to obtain the high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material.
Preferably, the preparation method comprises the following steps:
(1) Proportioning, namely preparing raw materials according to the weight percentage of the components of the rare earth permanent magnet material, wherein LRE: 20-32%, HRE:1 to 6 percent of Co: 19-25%, B:0.9 to 1.2 percent, cu: 0-1%, al: 0-1%, zr: 0-1%, and the balance being Fe; LRE is one or more of light rare earth Pr and Nd; HRE is one or more of heavy rare earth Gd, tb, dy, ho;
(2) Smelting, namely putting raw materials into a vacuum smelting furnace, vacuumizing the smelting furnace to 10 -3～10- 1 Pa after multiple times of gas washing, then filling protective argon to maintain the pressure value to-0.06 to-0.04 MPa, and obtaining a quick-setting casting sheet after vacuum smelting and cooling water cooling;
(3) Coarse grinding, crushing the rapid hardening cast sheet into coarse powder with a hydrogen breaking furnace, wherein the particle size is 10-500 mu m;
(4) Finely grinding, namely grinding coarse powder into fine powder with the particle size of 3-5 mu m through air flow grinding equipment under the protection of nitrogen;
(5) Performing magnetic field forming, namely performing orientation forming on the fine powder under a magnetic field of 1.5-2T, and performing isostatic pressing to obtain a green body;
(6) Sintering, namely sintering the green body under the vacuum condition, wherein the sintering temperature is 1000-1100 ℃ and the sintering time is 2-5 hours, so as to obtain a sintered magnet;
(7) Grain boundary diffusion, namely heavy rare earth diffusion is carried out on the sintered magnet; the diffusion temperature is 850-960 ℃, the diffusion time is 6-15 h, and the sintered rare earth permanent magnet material with high magnetic energy product and low temperature coefficient is prepared.
The presence of the cobalt-rich phase in the magnet of the present invention is detrimental to the enhancement of coercivity, and thus the coercivity is optimized by grain boundary diffusion.
Preferably, the density of the green embryo is 7.6-7.8 g/cm 3.
Preferably, the heavy rare earth diffusion process in (7) includes: coating the heavy rare earth solution with the weight ratio of 0.1-5% on the surface of the magnet.
Further preferably, the coating amount of the heavy rare earth solution is 0.5 to 1%.
The shell thickness of the main phase is closely related to the high remanence and high magnetic energy product performance of the magnet, and the shell with decreasing thickness is beneficial to maintaining the overall remanence of the bulk magnet; the coating amount of the heavy rare earth diffusion source affects the thickness of the shell layer, so that the content of the heavy rare earth element in the heavy rare earth solution and the coating amount of the heavy rare earth solution need to be controlled.
Further preferably, the heavy rare earth comprises one or more of Gd, tb, dy, ho.
Further preferably, the heavy rare earth element in the heavy rare earth solution is the same as the heavy rare earth element in the magnet raw material.
Further preferably, the solvent in the heavy rare earth solution comprises one or more of ethanol and methanol.
Preferably, the density of the high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material is 7.7-8.0 g/cm 3, and the Curie temperature is 500-600 ℃.
Preferably, the residual magnetism temperature coefficient alpha of the high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material at 20-150 ℃ is minus 0.07-minus 0.01%/DEGC.
Compared with the prior art, the invention has the following beneficial effects:
1. The high magnetic energy product low temperature coefficient sintered rare earth permanent magnetic material comprises a main phase and a grain boundary phase, wherein the grain boundary phase is isolated and/or coated with the main phase, the grain boundary phase is mainly a rare earth-rich phase and comprises a cobalt-poor phase and a cobalt-rich phase, the cobalt-rich phase accounts for more than 70% of the total mass of components of the grain boundary phase, and the high cobalt content can ensure lower residual magnetic temperature coefficient;
2. The invention carries out heavy rare earth grain boundary diffusion on the magnet to optimize the coercive force; and the adoption of the heavy rare earth elements which are the same as the raw materials is beneficial to fully utilizing the residual heavy rare earth elements in the grain boundary phase;
3. The Zr element in the raw materials of the high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material is beneficial to grain refinement; the Al and Cu elements can improve the fluidity and wettability of the grain boundary phase.
Drawings
FIG. 1 is a microstructure of a sintered rare earth permanent magnet material with high magnetic energy product and low temperature coefficient according to example 1 of the present invention.
FIG. 2 is a microstructure of the sintered rare earth permanent magnet material of example 1 of the present invention with a high magnetic energy product and a low temperature coefficient at a distance of 280 μm from the surface.
FIG. 3 is a microstructure of the sintered rare earth permanent magnet material of example 1 of the present invention with a high magnetic energy product and a low temperature coefficient at a distance of 400 μm from the surface.
Detailed Description
The following are specific examples of the present invention, and the technical solutions of the present invention are further described, but the present invention is not limited to these examples.
The materials adopted by the invention are conventional commercial products, and the adopted method is conventional technical means unless specified.
Example 1
(1) Proportioning according to the components of the high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material designed in the table 1;
(2) Smelting, namely placing raw materials into a vacuum smelting furnace, vacuumizing the smelting furnace to 10 -1 Pa after multiple times of gas washing, then filling protective argon to maintain the pressure value to-0.06 MPa, and obtaining a rapid hardening casting sheet after vacuum smelting and cooling water cooling, wherein the average thickness dimension is 0.38mm;
(3) Coarse grinding, namely crushing the rapid hardening cast sheet into coarse powder with a hydrogen breaking furnace, wherein the particle size is 300 mu m;
(4) Finely grinding, namely grinding coarse powder into fine powder with the particle size of 4.43 mu m through air flow grinding equipment under the protection of nitrogen;
(5) Performing magnetic field forming, namely performing isostatic pressing on the fine powder at 2T, wherein the pressure is 180Mpa, the time is 40s, and a green body is obtained, and the density of the green body is 5.4g/cm 3;
(6) Sintering, namely sintering the green body under the vacuum condition, wherein the sintering temperature is 1060 ℃, and the sintering time is 2 hours, so as to obtain a sintered magnet, and the thickness of the magnet is 7mm;
(7) Grain boundary diffusion, namely heavy rare earth diffusion is carried out on the sintered magnet;
The heavy rare earth diffusion process comprises the following steps: acid washing the surface of a sintered magnet, coating a heavy rare earth Tb solution with the weight ratio of 1% on the upper surface and the lower surface of the magnet, and then carrying out heat treatment for 10 hours at 950 ℃ under vacuum condition, so that a heavy rare earth diffusion source enters a main phase along a grain boundary, and the density of the prepared magnet is 7.712g/cm 3;
(8) The magnet was machined into a column of Φ10×7 mm.
FIG. 1 is a surface microstructure of a sintered rare earth permanent magnet material with high magnetic energy product and low temperature coefficient in this embodiment; FIG. 2 is a microstructure of the sintered rare earth permanent magnet material with high magnetic energy product and low temperature coefficient of 280 μm from the surface in the present embodiment; FIG. 3 is a microstructure of the sintered rare earth permanent magnet material with high magnetic energy product and low temperature coefficient at 400 μm distance from the surface in the present embodiment; as can be seen from comparison, the thickness of the shell layer decreases with the increase of the distribution depth of the main phase.
Testing the magnet, wherein the components of the high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material are Nd 20.25Pr6.75Tb3.5Co20Cu0.2Al0.1Zr0.2Fe48.04B0.96 in percentage by weight;
The shell layer of the main phase comprises Nd 14.0Pr4.6Tb8.5Co20.5Fe51.3B1.1 in percentage by weight; the core component of the main phase comprises Nd 17.5Pr5.8Tb3.0Co21.0Fe51.7B1.0 in percentage by weight;
The components of the lean iron, cobalt and rare earth phases in the grain boundary phase are as follows in percentage by weight: nd 49.9Pr31.5Co13.9Fe3. 2O0.9Cu0.6; the cobalt-rich iron-rich phase and the rare earth-rich phase in the grain boundary phase comprise the following components in percentage by weight: nd 32.1Pr13.3Tb5.8Co25.5Fe21.9Zr1.4.
The magnetic properties of the magnet in (8) were measured using a NIM-2000 hysteresis loop tester, and the specific properties are shown in table 2.
Example 2
(1) Proportioning according to the components of the high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material designed in the table 1;
(2) Smelting, namely placing raw materials into a vacuum smelting furnace, vacuumizing the smelting furnace to 10 -1 Pa after multiple times of gas washing, then filling protective argon to maintain the pressure value to-0.06 MPa, and obtaining a rapid hardening casting sheet after vacuum smelting and cooling water cooling, wherein the average thickness dimension is 0.38mm;
(3) Coarse grinding, namely crushing the rapid hardening cast sheet into coarse powder with a hydrogen breaking furnace, wherein the particle size is 300 mu m;
(4) Finely grinding, namely grinding coarse powder into fine powder with the particle size of 4.43 mu m through air flow grinding equipment under the protection of nitrogen;
(5) Performing magnetic field forming, namely performing isostatic pressing on the fine powder at 2T, wherein the pressure is 180Mpa, the time is 40s, and a green body is obtained, and the density of the green body is 5.52g/cm 3;
(6) Sintering, namely sintering the green body under the vacuum condition, wherein the sintering temperature is 1060 ℃, and the sintering time is 2 hours, so as to obtain a sintered magnet;
(7) Grain boundary diffusion, namely heavy rare earth diffusion is carried out on the sintered magnet; the diffusion temperature is 950 ℃, and the diffusion time is 10 hours;
The heavy rare earth diffusion process comprises the following steps: coating a heavy rare earth Tb solution with the weight ratio of 1% on the upper surface and the lower surface of a magnet, and then carrying out heat treatment at 950 ℃ for 10 hours, so that a heavy rare earth diffusion source enters a main phase along a grain boundary, and the density of the prepared magnet is 7.768g/cm 3;
(8) The magnet was machined into a column shape of Φ10×7mm, and the magnetic properties of the magnet were measured using NIM-2000 hysteresis loop tester, the specific properties of which are shown in table 2.
Example 3
(1) Proportioning according to the components of the high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material designed in the table 1;
(2) Smelting, namely placing raw materials into a vacuum smelting furnace, vacuumizing the smelting furnace to 10 -1 Pa after multiple times of gas washing, then filling protective argon to maintain the pressure value to-0.06 MPa, and obtaining a rapid hardening casting sheet after vacuum smelting and cooling water cooling, wherein the average thickness dimension is 0.38mm;
(3) Coarse grinding, namely crushing the rapid hardening cast sheet into coarse powder with a hydrogen breaking furnace, wherein the particle size is 300 mu m;
(4) Finely grinding, namely grinding coarse powder into fine powder with the particle size of 4.43 mu m through air flow grinding equipment under the protection of nitrogen;
(5) Performing magnetic field forming, namely performing isostatic pressing on the fine powder at 2T, wherein the pressure is 180Mpa, the time is 40s, and a green body is obtained, and the density of the green body is 5.60g/cm 3;
(6) Sintering, namely sintering the green body under the vacuum condition, wherein the sintering temperature is 1060 ℃, and the sintering time is 2 hours, so as to obtain a sintered magnet;
(7) Grain boundary diffusion, namely heavy rare earth diffusion is carried out on the sintered magnet; the diffusion temperature is 950 ℃, and the diffusion time is 10 hours;
the heavy rare earth diffusion process comprises the following steps: coating a heavy rare earth Tb solution with the weight ratio of 1% on the upper surface and the lower surface of a magnet, and then carrying out heat treatment at 950 ℃ for 10 hours, so that a heavy rare earth diffusion source enters a main phase along a grain boundary, and the density of the prepared magnet is 7.812g/cm 3;
(8) The magnet was machined into a column shape of Φ10×7mm, and the magnetic properties of the magnet were measured using NIM-2000 hysteresis loop tester, the specific properties of which are shown in table 2.
Comparative example 1
The difference compared to example 1 is that no heavy rare earth grain boundary diffusion is performed.
The properties of the prepared sintered rare earth permanent magnet material are shown in Table 2.
Comparative examples 2 to 5
In comparison with example 1, the difference is that the ingredients of the sintered rare earth permanent magnet material designed in table 1 were dosed.
The properties of the prepared sintered rare earth permanent magnet material are shown in Table 2.
TABLE 1 high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material composition (%)
Pr Nd Tb Co Cu Al Zr B Fe
Example 1 6.75 20.25 3.5 20 0.2 0.1 0.2 0.96 Allowance of
Example 2 5.6 22.4 3 22 0.15 0.1 0.15 1.0 Allowance of
Example 3 6.5 19.5 4 25 0.1 0.1 0.15 0.98 Allowance of
Comparative example 1 6.75 20.25 3.4 20 0.2 0.1 0.2 0.96 Allowance of
Comparative example 2 6.75 20.25 3.5 15 0.2 0.1 0.2 0.96 Allowance of
Comparative example 3 6.75 20.25 3.5 20 0 0.1 0 0.96 Allowance of
Comparative example 4 6.75 20.25 3.5 20 0.2 0 0 0.96 Allowance of
Comparative example 5 6.75 20.25 3.5 20 0 0 0 0.96 Allowance of
TABLE 2 Performance of high magnetic energy product low temperature coefficient sintered rare earth permanent magnet materials
Br(kGs) Hcj(kOe) (BH)max α(RT～150℃)
Example 1 13.10 19.87 41.04 -0.0686
Example 2 12.47 20.09 36.77 -0.068
Example 3 12.10 18.49 34.08 -0.068
Comparative example 1 13.11 12.80 40.96 -0.069
Comparative example 2 13.08 16.92 39.87 -0.072
Comparative example 3 12.98 17.12 39.72 -0.069
Comparative example 4 12.94 17.56 39.88 -0.069
Comparative example 5 12.96 16.52 39.82 -0.069
As can be seen from tables 1 and 2, the sintered rare earth permanent magnet materials in examples 1 to 3 of the present invention have both high magnetic energy product and low temperature coefficient.
The coercivity is significantly reduced in comparative example 1 due to the lack of heavy rare earth grain boundary diffusion; the Co content in comparative example 2 was reduced to 15%, resulting in an increase in the absolute value of the residual magnetic temperature coefficient; comparative example 3, in which Cu and Zr were not added, resulted in an increase in the average grain size of the main phase and a slight decrease in coercive force; the absence of Al and Zr in comparative example 4 resulted in an increase in the average grain size of the main phase and a slight decrease in the coercivity; the absence of Cu, al and Zr added in comparative example 5 resulted in an increase in the average grain size of the main phase and a slight decrease in the coercive force.
In summary, the high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material provided by the invention comprises a main phase and a grain boundary phase, wherein the main phase is isolated and/or coated by the grain boundary phase, the grain boundary phase is mainly a rare earth-rich phase and comprises a cobalt-poor phase and a cobalt-rich phase, the cobalt-rich phase accounts for more than 70% of the total mass of components of the grain boundary phase, and the high cobalt content can ensure a lower residual magnetic temperature coefficient.
The specific embodiments described herein are offered by way of example only to illustrate the spirit of the invention. Those skilled in the art may make various modifications or additions to the described embodiments or substitutions thereof without departing from the spirit of the invention or exceeding the scope of the invention as defined in the accompanying claims.

Claims (10)

1. The high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material is characterized by comprising the following components in percentage by weight: LRE: 20-32%, HRE:1 to 6 percent of Co: 19-25%, B:0.9 to 1.2 percent, cu: 0-1%, al: 0-1%, zr: 0-1%, and the balance being Fe;
LRE is one or two of light rare earth Pr and Nd;
HRE is one or more of heavy rare earth Gd, tb, dy, ho;
the high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material comprises a main phase and a grain boundary phase, wherein the grain boundary phase isolates and/or coats the main phase;
The main phase is provided with a core-shell structure, the core-shell structure comprises an inner core and a shell layer, and the shell layer is positioned on the outer side of the main phase;
in the area of 0-500 mu m of inward radiation of the surface layer of the sintered rare earth permanent magnet material, the thickness of the shell layer of the main phase with the core-shell structure is reduced along with the increase of the distance between the surface layer of the sintered rare earth permanent magnet material and the surface layer of the sintered rare earth permanent magnet material; the grain boundary phase includes a rare earth-rich phase and a very small amount of a boron-rich phase, the rare earth-rich phase including an iron-poor cobalt-poor rare earth-rich phase and a cobalt-rich iron-rich rare earth-rich phase, the cobalt-rich iron-rich rare earth-rich phase accounting for 70% or more of the total mass of the grain boundary phase components.
2. The high magnetic energy product low temperature coefficient sintered rare earth permanent magnetic material according to claim 1, wherein the Cu+Al is more than or equal to 0.2% and less than or equal to 0.4%; the content of Cu+Al+Zr is more than or equal to 0.3% and less than 0.6%.
3. The high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material according to claim 1, wherein the main phase is RE (Fe, co): main phase grains of b=2:14:1 structure, RE including light rare earth LRE and heavy rare earth HRE;
The main phase accounts for 92-96% of the total mass of the sintered rare earth permanent magnet material;
The mass of heavy rare earth in the shell layer of the main phase accounts for 0.01-2% of the total mass of the sintered rare earth permanent magnet material.
4. The high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material according to claim 1, wherein the shell layer components of the main phase are as follows by weight percent: LRE fHREgCohBiFe1-f-g-h-i; LRE is one or two of light rare earth Pr and Nd;
HRE is one or more of heavy rare earth Gd, tb, dy, ho;
15％≤f≤22％，6％≤g≤9％，19％≤h≤25％，0.9％≤i≤1.2％，50％≤1-f-g-h-i≤55％。
5. the high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material according to claim 1, wherein the core component of the main phase comprises the following components in percentage by weight: LRE kHREmConBpFe1-k-m-n-p; LRE is one or two of light rare earth Pr and Nd;
HRE is one or more of heavy rare earth Gd, tb, dy, ho;
18％≤k≤28％，1％≤m≤5％，19％≤n≤25％，0.9％≤p≤1.2％，50％≤1-k-m-n-p≤55％。
6. the high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material according to claim 1, wherein the components of the lean iron, lean cobalt and rich rare earth phase in the grain boundary phase are as follows in percentage by weight: LRE rHREsCotMuOvFe1-r-s-t-u-v;
LRE is one or two of light rare earth Pr and Nd;
HRE is one or more of heavy rare earth Gd, tb, dy, ho;
M is one or more of Cu, al and Zr;
60％≤r≤85％，0％≤s≤25％，0％≤t≤14％，0％≤u≤3％，0％≤v≤1.3％，2％≤1-r-s-t-u-v≤10％。
7. The high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material according to claim 1, wherein the components of the cobalt-rich, iron-rich and rare earth-rich phases in the grain boundary phase are as follows in percentage by weight: LRE wHRExCoyMzFe1-w-x-y-z;
LRE is one or two of light rare earth Pr and Nd;
HRE is one or more of heavy rare earth Gd, tb, dy, ho;
M is one or more of Cu, al and Zr;
40％≤w≤60％，0％≤x≤8％，22％≤y≤30％，0％≤z≤3％，20％≤1-w-x-y-z≤30％。
8. the high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material according to claim 1, wherein the thickness of the sintered rare earth permanent magnet material is 1-10 mm; the average size of the main phase is 1-10 mu m, and the thickness of the shell layer of the main phase is less than or equal to 6 mu m.
9. The preparation method of the high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material is characterized by comprising the following steps: proportioning, smelting, coarse grinding, fine grinding, magnetic field forming, sintering and grain boundary diffusion; and (3) performing magnetic field molding to obtain a green body, and diffusing the grain boundary to obtain the high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material.
10. The method according to claim 9, wherein the green embryo has a density of 7.6 to 7.8g/cm 3; the density of the high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material is 7.7-8.0 g/cm 3, and the Curie temperature is 500-600 ℃; the residual magnetism temperature coefficient alpha of the high magnetic energy product low temperature coefficient sintered rare earth permanent magnet material is-0.07 to-0.01 percent/DEG C at 20-150 ℃.
CN202311698177.9A 2023-12-12 2023-12-12 High-magnetic energy product low-temperature coefficient sintered rare earth permanent magnet material and preparation method thereof Pending CN118116680A (en)

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