CN111243804B - Rare earth permanent magnet with hydrogen resistance and preparation method thereof - Google Patents
Rare earth permanent magnet with hydrogen resistance and preparation method thereof Download PDFInfo
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
- H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
- H01F1/047—Alloys characterised by their composition
- H01F1/053—Alloys characterised by their composition containing rare earth metals
- H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
- H01F1/0555—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 pressed, sintered or bonded together
- H01F1/0556—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 pressed, sintered or bonded together pressed
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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
- H01F1/0555—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 pressed, sintered or bonded together
- H01F1/0557—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 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
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Abstract
The application relates to a rare earth permanent magnet with hydrogen resistance and a preparation method thereof, belonging to the technical field of rare earth permanent magnet materials. The rare earth permanent magnet is Sm 2 (CoCuFeZr) 17 A magnet, wherein the mass percentage of Sm is m, and the sum of the mass percentages of Co and Fe is n, n>3m; the sealing layer outside the rare earth permanent magnet is formed by sealing a cerium-containing water-based silane solvent, and the hydrogen resistance of the rare earth permanent magnet is improved through heat treatment. The application ensures that the surface of the rare earth permanent magnet is more densified and stable by setting the sum of the mass percentages of Co and Fe to be larger than that of Sm and combining a heat treatment method so as to reduce the path of hydrogen atoms entering a grain boundary from the surface of the material and improve the hydrogen resistance of the rare earth permanent magnet, thereby achieving the aim of preventing hydrogen from entering the magnet.
Description
Technical Field
The application relates to the technical field of rare earth permanent magnet materials, in particular to a rare earth permanent magnet with hydrogen resistance.
Background
The rare earth permanent magnetic material is a permanent magnetic material with the highest comprehensive performance known at present, and has the magnetic performance which is more than 100 times higher than that of magnetic steel used in ninety century, is much superior to that of ferrite and alnico, and is one time higher than that of expensive platinum-cobalt alloy. The use of rare earth permanent magnetic material not only promotes the miniaturization development of permanent magnetic devices and improves the performance of products, but also promotes the production of certain special devices. The main types of magnetic permanent magnet materials currently include sintered and bonded rare earth permanent magnets. The rare earth permanent magnet material has high magnetic energy product and high coercivity, and becomes an indispensable material for manufacturing stators and rotors of modern motors and realizing miniaturization of high-performance motors.
Under the condition that the existing rare earth permanent magnet is contacted with hydrogen, hydrogen atoms can enter the rare earth permanent magnet material along a grain boundary, so that the rare earth permanent magnet material is pulverized, the magnetic performance is lost, and finally the motor is disabled. The application endows the motor with permanent magnetic material with the capability of stably operating in the environment contacting hydrogen by carrying out surface modification and sealing on the rare earth permanent magnetic material.
The prior art also has patent applications for improving the properties of rare earth permanent magnet materials, such as: the name of the application is: the high-performance high-resistivity sintered samarium cobalt permanent magnet material, a preparation method and application thereof (application number: 201810074109.8, application date: 2018.01.25) utilize the permanent magnetic property of the main phase of the samarium cobalt matrix to realize the high magnetic property of the magnet, and the resistivity of the magnet is improved through the wrapping of a grain boundary phase, and the precipitated grain boundary phase has the characteristics of small size, high resistivity and concentrated distribution range, so that the influence on the magnetic property of the magnet is small, the obtained magnet can expand the application field of the samarium cobalt permanent magnet material, and the obtained magnet can be widely applied to the fields of high-temperature, high-frequency or high-speed motors and the like; in addition, the samarium cobalt permanent magnet material does not need to compound a high-resistivity compound through a complex process, and the resistivity of the magnet is improved on the basis of not changing the process flow of sintering the samarium cobalt magnet. However, this technique does not improve the hydrogen resistance of rare earth permanent magnets.
In addition, the application also discloses the inventive name: a method for preparing high-performance SmCo permanent magnetic material (application number 201210272726.1, application date 2012.07.26) improves the permanent magnetic performance of a magnet by improving the aging process and adding a constant magnetic field when aging the permanent magnetic material. However, this method also does not improve the hydrogen resistance of rare earth permanent magnets.
Disclosure of Invention
1. Technical problem to be solved by the application
The application aims to solve the problem that the conventional permanent magnet material is easy to fail when being contacted with hydrogen in the prior art, and provides a rare earth permanent magnet with hydrogen resistanceMagnet and preparation method thereof, and rare earth permanent magnet is Sm 2 (CoCuFeZr) 17 The sum of the mass percentages of Co and Fe of the magnet is more than 3 times of that of Sm, so that the surface of the rare earth permanent magnet is more densified and stabilized, the path of hydrogen atoms entering a grain boundary from the surface of the material can be reduced, and the hydrogen resistance of the rare earth permanent magnet material is improved.
2. Technical proposal
In order to achieve the above purpose, the technical scheme provided by the application is as follows:
the application relates to a rare earth permanent magnet with hydrogen resistance, which is Sm 2 (CoCuFeZr) 17 A magnet, wherein the mass percentage of Sm is m, and the sum of the mass percentages of Co and Fe is n, n>3m。
Preferably, the mass percentage of Co is 45-55%, the mass percentage of Fe is 18-20%, and the mass percentage of Sm is 15-23%.
Preferably, the rare earth permanent magnet is provided with a sealing layer on the outside, and the sealing layer is formed by sealing with a cerium-containing water-based silane solvent.
Preferably, the Cu content is 2-6% by mass.
The application also provides a preparation method of the hydrogen-resistant rare earth permanent magnet, which comprises the following steps:
(1) Smelting: smelting in a smelting furnace to obtain Sm 2 (CoCuFeZr) 17 A magnet, wherein the mass percentage of Sm is m, and the sum of the mass percentages of Co and Fe is n, n>3m, and obtaining an ingot;
(2) Pulverizing: crushing the cast ingot and pulverizing to obtain permanent magnet powder;
(3) Compression molding: stamping and forming the permanent magnet powder to obtain a green permanent magnet body;
(4) Sintering: sintering the permanent magnet green body at 1150-1250 ℃ for 3-5 hours to obtain a permanent magnet blank;
(5) And (3) heat treatment: cooling to room temperature after sintering, and then carrying out heat treatment on the permanent magnet blank in nitrogen atmosphere, wherein the heat treatment temperature is 650-1050 ℃, and the heat treatment time is more than 12 hours.
Preferably, the process of heat treatment comprises three stages:
stage one: firstly, heating the rare earth permanent magnet to 650-750 ℃ under the vacuum condition, and carrying out heat preservation treatment for 2-3 h;
stage two: then heating to 750-850 ℃ at a heating rate of 1-5 ℃/min, charging nitrogen into the vacuum furnace, and carrying out heat preservation treatment for 2-3 h;
stage three: heating to 900-1050 ℃ at a heating rate of 1-5 ℃/min, and carrying out heat preservation treatment for 10-15 h.
Preferably, the rare earth permanent magnet is sealed after heat treatment, and the specific steps are as follows: cooling the rare earth permanent magnet to room temperature, immersing the rare earth permanent magnet into a sealing agent for dip-coating sealing treatment, wherein the sealing agent is a cerium-containing water-based silane solvent, and curing after sealing is finished, so as to obtain the rare earth permanent magnet.
Preferably, the blocking agent comprises a water-based silane solvent and cerium oxide, and the mass of cerium oxide is 0.5% -2.1% of the mass of the water-based silane solvent.
Preferably, the capping reagent further comprises nano SiO 2 。
Preferably, the baking temperature of the curing treatment is 150-180 ℃.
3. Advantageous effects
Compared with the prior art, the technical scheme provided by the application has the following remarkable effects:
(1) According to the rare earth permanent magnet with hydrogen resistance, the sum of the mass percentages of Co and Fe in the rare earth permanent magnet is more than 3 times of that of Sm, so that the surface of the rare earth permanent magnet is more densified and stable, the path of hydrogen atoms entering a grain boundary from the surface of the material is reduced, and the hydrogen resistance of the rare earth permanent magnet material is improved.
(2) According to the preparation method of the rare earth permanent magnet with the hydrogen resistance, the rare earth permanent magnet is subjected to heat treatment after being sintered, so that the rare earth phases enriched in the grain boundary are distributed more uniformly, densification of the grain boundary is promoted, the path of hydrogen atoms entering the grain boundary from the surface of the material is further reduced, and the hydrogen resistance of the rare earth permanent magnet material is improved.
(3) According to the preparation method of the rare earth permanent magnet with the hydrogen resistance, the rare earth permanent magnet after heat treatment is subjected to sealing treatment, so that a film sealing layer is formed on the surface of the rare earth permanent magnet, and the silanized sealing layer after film formation can fill microcracks and micropores on the surface of the rare earth permanent magnet by controlling the curing temperature to be 150-180 ℃, so that the long-term stable working capacity of the magnet in a hydrogen environment is further improved.
(4) According to the preparation method of the rare earth permanent magnet with hydrogen resistance, the rare earth permanent magnet is subjected to sealing treatment by adopting the water-based silane solvent containing cerium, a metal silane composite film is formed on the metal surface by a silane treatment agent through film forming reaction, and a large amount of oligosiloxane is formed on the water-based silane solvent containing cerium through condensation reaction, so that a sealing layer of a composite passivation film is formed on the surface of the rare earth permanent magnet, and the sealing layer has self-repairing capability and can prevent damage of the rare earth permanent magnet material due to scraping.
(5) The application relates to a preparation method of rare earth permanent magnet with hydrogen resistance, which adds nano SiO in the process of sealing treatment 2 Nano SiO during sealing treatment 2 Can gather at the micropore defect of the hydrogen-resistant layer, promote the formation of a complete silane film sealing layer while improving the strength of the sealing side, and prevent the migration of hydrogen atoms from the surface of the magnet to the interior of the magnet.
Drawings
FIG. 1 is a graph showing the time-dependent changes in the hydrogen absorption amount (100 ℃ C.) of example 1 and comparative example 1 according to the present application.
Detailed Description
The present application will be described in detail with reference to examples and drawings, and the detailed description is as follows.
Example 1
The rare earth permanent magnet with hydrogen resistance provided by the application is Sm 2 (CoCuFeZr) 17 The sum of the mass percentages of Co and Fe of the magnet is greater than that of Sm, further illustrating that the mass percentages of Sm includeThe sum of the mass percentages of Co and Fe is n, n>3m. The sum of the mass percentages of Co and Fe is set to be larger than the mass percentage of Sm, so that Sm is wrapped by Co and Fe, and the prepared rare earth permanent magnet Sm 2 (CoCuFeZr) 17 The magnet is more densified, so that the path of hydrogen atoms entering the grain boundary from the surface of the material is reduced, and the hydrogen resistance of the rare earth permanent magnet material is improved.
The preparation method of the hydrogen-resistant rare earth permanent magnet comprises the following steps:
(1) Smelting: proportioning according to the components, and smelting in a smelting furnace to obtain Sm 2 (CoCuFeZr) 17 The mass percentage of each element of the magnet is as follows: 45-55% of Co,15-23% of Sm, 2-6% of Cu, 18-20% of Fe, 1-4% of Zr and 0-2% of impurities; the rare earth permanent magnet in the embodiment comprises the following elements in percentage by mass: 47% Co,18% Sm,3% Cu,19% Fe,2% Zr,1% impurities; and an ingot is obtained.
(2) Pulverizing: crushing and pulverizing the cast ingot to obtain permanent magnet powder, wherein the permanent magnet powder is controlled to have a granularity of 1-10 mu m and a particle size distribution of 3-5 mu m, and the mass percent of the particles is more than 80%; the powder preparation method comprises air milling by adding 0.1-3.5mL of antioxidant per kilogram of permanent magnet powder during air milling, wherein the antioxidant is thymol (C) 10 H 14 O) and calcium stearate (C) 36 H 70 O 4 Ca), and thymol (C) 10 H 14 O) and calcium stearate (C) 36 H 70 O 4 Ca) is 1:2, and in the embodiment, the antioxidant in each kilogram of permanent magnet powder is 2mL, and Sm can be reduced 2 O 3 Impurity content;
(3) Compression molding: stamping and forming the permanent magnet powder to obtain a green permanent magnet body;
(4) Sintering: sintering the permanent magnet green body at 1150-1250 ℃ for 3-5 hours to obtain a permanent magnet blank;
in the embodiment, the sintering temperature is controlled to 1230 ℃ during the sintering treatment process, the sintering time is 4 hours, argon is adopted for protection during the sintering process, and the uniformity of the furnace temperature is +/-2 ℃ under the condition of full load control during the sintering process;
(5) And (3) heat treatment: cooling the permanent magnet blank to room temperature after sintering, and then carrying out heat treatment on the permanent magnet blank in nitrogen atmosphere, wherein the heat treatment temperature is 650-1050 ℃ and the heat treatment time is more than 12 hours;
in detail, the heat treatment process includes three steps:
stage one: firstly, under the condition of vacuum, heating rare earth permanent magnet to 650-750 deg.C, vacuum degree is 1.3X 10 -1 ～1.3×10 -3 Pa, and carrying out heat preservation treatment for 2-3 h; in this example, the rare earth permanent magnet is first heated to 750 deg.C and then heat-preserved for 2h, in this example 1.5X10 -2 Pa；
Stage two: heating to 750-850 ℃ at a heating rate of 1-5 ℃/min, charging nitrogen into the vacuum furnace, controlling nitrogen partial pressure protective atmosphere in the furnace to be 200-300 mbar after the temperature reaches the furnace, and then carrying out heat preservation treatment for 2-3 h; in the embodiment, the temperature is raised to 850 ℃ at the heating rate of 3 ℃/min, nitrogen is introduced into the heat treatment furnace, the nitrogen partial pressure protective atmosphere in the furnace is controlled to be 200mbar, and the heat preservation treatment is carried out for 2 hours;
stage three: heating to 900-1050 ℃ at a heating rate of 1-5 ℃/min, and carrying out heat preservation treatment for 8-15 h. In the embodiment, the temperature is raised to 1050 ℃ at a heating rate of 3 ℃/min, and the heat preservation treatment is carried out for 8 hours;
in the cooling process, the space-time cooling speed is controlled to be 100-175 ℃/h, so that the rare earth magnet grains are more uniform and finer, the distribution of the rare earth phases enriched in the grain boundary is more uniform, the grain boundary is purified to promote the densification of the material, the path of hydrogen atoms entering the grain boundary from the surface of the material is reduced, and the hydrogen resistance of the rare earth permanent magnet material is improved.
Because nitrogen has a gap atom effect, the concentration of nitrogen atoms in the metal layer surface of the rare earth permanent magnet is highest in the heat treatment process, and the permeation process of the nitrogen atoms in the metal has a permeation limit, so that the concentration of the nitrogen atoms in the permanent magnet is close to zero, and a nitrogen atom concentration gradient from outside to inside is formed; wherein the permeation limit of nitrogen atoms is related to the nitrogen atom concentration, reaction time and reaction temperature; during the heat treatment, nitrogen atoms continuously permeate into the low nitrogen content area under the drive of the concentration gradient, and nitrogen finally forms a nitrogen concentration which tends to be balanced in the metal layer of the samarium-iron-cobalt alloy surface layer. That is, in the heat treatment process, nitrogen permeated into the surface layer of samarium-iron-cobalt alloy reacts with the surface of the magnet, so that the nitrogen reacts with the samarium-iron-cobalt alloy on the surface of the rare earth permanent magnet in a gas-solid manner, and nitrogen atoms are introduced into interstitial crystal positions of the samarium-iron-cobalt alloy and stably exist, so that a stable complete nitriding phase is formed on the surface of the rare earth permanent magnet, and the rare earth permanent magnet has hydrogen resistance. It is worth noting that since nitrogen gradually reacts with samarium-iron-cobalt alloy during permeation, the process is not just a physical permeation process but a dynamic chemical permeation process.
In addition, the heat treatment of the application can ensure that the distribution of the rare earth phase enriched in the grain boundary is more uniform, and the impurities of the grain boundary on the surface of the rare earth permanent magnet are purified, so that the path of hydrogen atoms entering the grain boundary from the surface of the material is reduced, and the hydrogen resistance of the rare earth permanent magnet material is improved.
(6) And (3) sealing:
in order to improve the hydrogen resistance, the present embodiment performs a sealing treatment after the step of heat treatment; firstly cooling to room temperature, then carrying out deoiling and water washing treatment on the rare earth permanent magnet, adopting a sealing agent to carry out dip coating treatment on the rare earth permanent magnet, wherein the sealing agent is a cerium-containing water-based silane solvent, and after dip coating sealing, carrying out baking and solidifying treatment at 150-180 ℃ so as to form a sealing layer on the surface, wherein the baking and solidifying temperature in the embodiment is 180 ℃.
Illustratively, the blocking agent comprises a water-based silane solvent, cerium oxide and water, wherein the water-based silane solvent is a mixed silane system of bis (3-trimethoxysilylpropyl) amine (BAS) and vinyltriacetoxy silane (VTAS), and the blocking agent is prepared by the following specific steps:
firstly, mixing bis (3-trimethoxysilylpropyl) amine (BAS) and vinyl triacetoxy silane (VTAS) according to a volume ratio of 1:5, and stirring for 4 hours to obtain a mixed silane system, wherein the mixed silane system is a water-based silane solvent;
then adding cerium oxide into the water-based silane solvent, wherein the addition amount of the cerium oxide is 0.5-2.1% of the mass of the water-based silane solvent; adding water into the mixture after mixing and stirring, wherein the water can be deionized water, the adding amount of the deionized water is 35-55 times of the volume of the water-based silane solvent, and continuously stirring for 6-8 hours after adding the water to obtain a sealing agent; the deionized water of this example was added in an amount 35 times the volume of the water-based silane solvent and the stirring time was 6 hours.
The rare earth permanent magnet is soaked in a sealing agent, a sealing film layer is formed on the surface of the rare earth permanent magnet, and the silanized sealing layer after film formation can fill microcracks and micropores on the surface of the rare earth permanent magnet, so that the long-term stable working capacity of the magnet in a hydrogen environment can be ensured; the water-based silane solvent of cerium oxide forms a large amount of oligosiloxanes through condensation reaction, and a composite passivation film is formed on the surface of metal, and the composite passivation sealing film layer has higher hardness and self-repairing capability, namely, after the rare earth permanent magnet material is scratched, the composite passivation sealing film layer can react with oxygen and water in the air, and the scratch position of the sealing film layer is repaired, so that the aim of preventing hydrogen from entering a magnet is fulfilled.
The prepared rare earth permanent magnet is subjected to hydrogen resistance detection, namely the hydrogen absorption performance of the prepared rare earth permanent magnet at 100 ℃ and under the hydrogen pressure of 1MPa is detected, and the hydrogen content in the rare earth permanent magnet is detected in the hydrogen absorption process and is plotted in the graph in figure 1.
Comparative example 1
The rare earth permanent magnet material prepared in the comparative example comprises the following components: 48% of Co,27% of Sm,8% of Cu,15% of Fe,1% of Zr and 1% of impurities. The preparation method of the rare earth permanent magnet material of the comparative example comprises the following steps:
(1) Smelting: proportioning according to the components, and smelting in a smelting furnace to obtain Sm 2 (CoCuFeZr) 17 The mass percentage of each element of the magnet is as follows: 48% Co,27% Sm,8% Cu,15% Fe,1% Zr,1% impurities; and an ingot is obtained.
(2) Pulverizing: crushing the cast ingot and pulverizing to obtain permanent magnet powder, wherein the granularity of the permanent magnet powder is controlled to be 1-10 mu m; the method for pulverizing powder can select an air flow mill, and 2mL/kg of antioxidant is added in the air flow mill process;
(3) Compression molding: stamping and forming the permanent magnet powder to obtain a green permanent magnet body;
(4) Sintering: sintering the green permanent magnet at 1230 ℃ for 4 hours to obtain the finished rare earth permanent magnet in the prior art;
the comparative example does not undergo heat treatment or sealing treatment during the process of preparing the rare earth permanent magnet; and sintering to obtain the rare earth permanent magnet.
Then, the rare earth permanent magnet prepared in comparative example 1 was subjected to hydrogen resistance test, namely, the hydrogen absorption performance of the prepared rare earth permanent magnet at 100 ℃ and under a hydrogen pressure of 1MPa was tested, and the hydrogen content in the rare earth permanent magnet was tested during the hydrogen absorption process and plotted in fig. 1.
As can be seen by comparing example 1 and comparative example 1 in fig. 1, the rare earth permanent magnet in example 1 had a hydrogen absorption amount of 0 at 24 hours, i.e., did not react with hydrogen, and was maintained at a low level all the time. The hydrogen absorption amount of the rare earth permanent magnet in the prior art gradually increases along with the increase of time, and particularly after the hydrogen absorption is carried out for 5 hours, the hydrogen absorption amount of the rare earth permanent magnet is obviously increased. The reason is that the rare earth magnetic material makes the magnet not react with hydrogen through special components and a heat treatment process; the rare earth magnetic material improves the hydrogen resistance of the rare earth permanent magnet through heat treatment, a closed film layer is formed on the surface of the magnet, and the silanized closed layer after film formation can fill microcracks and micropores on the surface of the rare earth permanent magnet, so that the long-term stable working capacity of the magnet in a hydrogen environment can be ensured.
Example 2
The basic content of the present application is the same as that of example 1, except that: the preparation method of the hydrogen-resistant rare earth permanent magnet comprises the following steps:
(1) Smelting: proportioning according to the components, and smelting in a smelting furnace to obtain Sm 2 (CoCuFeZr) 17 The mass percentage of each element of the magnet is as follows: 50% Co,23% Sm,5% Cu,20% Fe,1% Zr,1% impurities; and obtain castingAn ingot.
(2) Pulverizing: crushing and pulverizing the cast ingot to obtain permanent magnet powder, wherein the permanent magnet powder is controlled to have a granularity of 1-10 mu m and a particle size distribution of 3-5 mu m, and the mass percent of the particles is more than 80%; the powder preparation method can select an air flow mill, and 0.1-3.5mL of antioxidant is added into each kilogram of permanent magnet powder in the air flow mill process;
(3) Compression molding: stamping and forming the permanent magnet powder to obtain a green permanent magnet body;
(4) Sintering: sintering the green permanent magnet at 1250 ℃ for 5 hours to obtain a blank of the permanent magnet; argon is adopted for protection in the sintering process;
(5) And (3) heat treatment: the heat treatment process comprises three steps:
stage one: heating rare-earth permanent magnet to 650 deg.C under vacuum condition, vacuum degree being 1.3×10 -3 Pa, and carrying out heat preservation treatment for 2.5h;
stage two: in the embodiment, the temperature is raised to 750 ℃ at the heating rate of 1 ℃/min, nitrogen is introduced into the heat treatment furnace, the nitrogen partial pressure protective atmosphere in the furnace is controlled to be 300mbar, and the heat preservation treatment is carried out for 2.5 hours;
stage three: in the embodiment, the temperature is raised to 900 ℃ at the heating rate of 1 ℃/min, and the heat preservation treatment is carried out for 10 hours;
in the cooling process, the space-time cooling speed is controlled to be 120 ℃/h, so that the rare earth magnet grains are more uniform and finer, the distribution of the rare earth phases enriched in the grain boundary is more uniform, the grain boundary is purified to promote the densification of the material, the path of hydrogen atoms entering the grain boundary from the surface of the material is reduced, and the hydrogen resistance of the rare earth permanent magnet material is improved.
(6) And (3) sealing: after cooling to room temperature, firstly carrying out deoiling and washing treatment on the rare earth permanent magnet, then carrying out dip coating treatment on the rare earth permanent magnet by adopting a sealing agent, wherein the sealing agent is a cerium-containing water-based silane solvent, and after dip coating sealing, carrying out baking and solidifying treatment at 150-180 ℃ so as to form a sealing layer on the surface, wherein the baking and solidifying temperature in the embodiment is 150 ℃.
Illustratively, the capping reagent comprises a water-based silane solvent, cerium oxide, nano SiO 2 And water, wherein the water-based silane solvent is a mixed silane system of bis (3-trimethoxysilylpropyl) amine (BAS) and vinyl triacetoxy silane (VTAS), and the preparation method of the blocking agent comprises the following specific steps:
firstly, mixing bis (3-trimethoxysilylpropyl) amine (BAS) and vinyl triacetoxy silane (VTAS) according to a volume ratio of 1:5, and stirring for 4 hours to obtain a mixed silane system, wherein the mixed silane system is a water-based silane solvent;
then adding cerium oxide into the water-based silane solvent, wherein the addition amount of the cerium oxide is 0.5% -2.1% of the mass of the water-based silane solvent, and the addition amount of the cerium oxide is 2% in the embodiment; adding water into the mixture after mixing and stirring, wherein the water can be deionized water, the adding amount of the deionized water is 40 times of the volume of the water-based silane solvent, and stirring is continued for 8 hours after adding the water; and then adding nano SiO into the mixture 2 Nano SiO 2 The addition amount of the catalyst is 0.5 to 5.0 percent of the total mass of the water-based silane solvent, cerium oxide and water, and the nano SiO of the embodiment 2 The addition amount is 2.5 percent, and the nano SiO is prepared 2 Is 10-30 nm in diameter.
The rare earth phases enriched in the surface grain boundary of the rare earth permanent magnet are distributed more uniformly, the densification of the grain boundary is promoted, the path of hydrogen atoms entering the grain boundary from the surface of the material is further reduced, and the hydrogen resistance of the rare earth permanent magnet material is improved; it is worth noting that due to the inclusion of nano SiO in the capping reagent 2 Nano SiO 2 The hydrogen atoms are accumulated at the micropore defects of the hydrogen-resistant layer so as to form a complete silane film, and meanwhile, the strength of the sealing layer is improved, and the migration process of the hydrogen atoms from the surface of the magnet to the interior of the magnet is prevented.
Example 3
The basic content of the present application is the same as that of example 1, except that: the preparation method of the hydrogen-resistant rare earth permanent magnet comprises the following steps:
(1) Smelting: proportioning according to the components, and smelting in a smelting furnace to obtain Sm 2 (CoCuFeZr) 17 The mass percentage of each element of the magnet is as follows: 55% Co,15% Sm,6% Cu,18% Fe,4% Zr,2% impurities; and an ingot is obtained.
(2) Pulverizing: crushing and pulverizing the cast ingot to obtain permanent magnet powder, wherein the permanent magnet powder is controlled to have a granularity of 1-10 mu m and a particle size distribution of 3-5 mu m, and the mass percent of the particles is more than 80%; the powder preparation method can select an air flow mill, and 3.5mL of antioxidant is added into each kilogram of permanent magnet powder in the air flow mill process;
(3) Compression molding: stamping and forming the permanent magnet powder to obtain a green permanent magnet body;
(4) Sintering: sintering the permanent magnet green body at 1150 ℃ for 3 hours to obtain a permanent magnet blank; argon is adopted for protection in the sintering process;
(5) And (3) heat treatment: the heat treatment process comprises three steps:
stage one: firstly, under the condition of vacuum, the rare earth permanent magnet is heated to 700 ℃, and the vacuum degree is 1.3 multiplied by 10 -1 Pa, and carrying out heat preservation treatment for 3h;
stage two: in the embodiment, the temperature is raised to 800 ℃ at the temperature rising speed of 5 ℃/min, nitrogen is introduced into the heat treatment furnace, the nitrogen partial pressure protective atmosphere in the furnace is controlled to be 250mbar, and the heat preservation treatment is carried out for 3 hours;
stage three: in the embodiment, the temperature is raised to 1000 ℃ at the temperature rising speed of 5 ℃/min, and the heat preservation treatment is carried out for 15 hours;
in the cooling process, the space-time cooling rate is controlled to 175 ℃/h, so that the rare earth magnet grains are more uniform and finer, the distribution of the rare earth phases enriched in the grain boundary is more uniform, the grain boundary is purified to promote the densification of the material, the path of hydrogen atoms entering the grain boundary from the surface of the material is reduced, and the hydrogen resistance of the rare earth permanent magnet material is improved.
(6) And (3) sealing: after cooling to room temperature, firstly carrying out oil removal and water washing treatment on the rare earth permanent magnet, and then pre-coating the rare earth permanent magnet in a pre-coating agent, wherein the pre-coating agent contains nano SiO 2 Baking and curing the water-based silane solvent at 180 ℃ to form a precoat on the surface layer of the rare earth permanent magnet; then dip-coating the rare earth permanent magnet surface with a sealing agent which is a cerium-containing water-based silane solvent, wherein the baking curing temperature in this example is 160 ℃, and the sealing agent in this example is the same as that in example 1The blocking agent is the same.
Illustratively, the precoating agent includes a water-based silane solvent, nano SiO 2 And water, wherein the water-based silane solvent is a mixed silane system of bis (3-trimethoxysilylpropyl) amine (BAS) and vinyl triacetoxy silane (VTAS), and the preparation method of the blocking agent comprises the following specific steps:
firstly, mixing bis (3-trimethoxysilylpropyl) amine (BAS) and vinyl triacetoxy silane (VTAS) according to a volume ratio of 1:5 to obtain a mixed silane system, wherein the mixed silane system is a water-based silane solvent;
then adding water into the water-based silane solvent, wherein the water can be deionized water, the adding amount of the deionized water is 40 times of the volume of the water-based silane solvent, and stirring is continued for 6 hours after the water is added; and then adding nano SiO into the mixture 2 Nano SiO 2 The addition amount of the nano SiO is 0.5 to 5.0 percent of the total mass of the water-based silane solvent and the water 2 The addition amount was 3%.
The rare earth permanent magnet has hydrogen resistance, the rare earth phases enriched in the grain boundary are distributed more uniformly, densification of the grain boundary is promoted, the path of hydrogen atoms entering the grain boundary from the surface of the material is further reduced, and the hydrogen resistance of the rare earth permanent magnet material is improved; it is worth to say that, the surface of the rare earth permanent magnet material is dip-coated with a precoat, and the precoat contains nano SiO 2 Nano SiO 2 Accumulating at the microporous defect of the hydrogen resistant layer to form a complete silane film; and then dip-coating the sealing layer, thereby forming a sealing layer on the outer surface of the precoat, forming a sealing film layer on the surface of the rare earth permanent magnet, and filling microcracks and micropores on the surface of the rare earth permanent magnet with the silanized sealing layer after film formation, so that the long-term stable working capacity of the magnet in a hydrogen environment can be ensured.
Example 4
The basic content of the present application is the same as that of example 1, except that: in the embodiment, after the heat treatment of the permanent magnet blank, the rare earth permanent magnet is prepared, i.e. no sealing treatment is performed. The rare earth permanent magnet prepared by the embodiment still has good hydrogen resistance, because the rare earth permanent magnet is subjected to heat treatment, the rare earth phases enriched in the grain boundary are distributed more uniformly, the densification of the grain boundary is promoted, and the hydrogen resistance of the rare earth permanent magnet material is improved; furthermore, it is worth noting that the hydrogen resistance of this example is slightly inferior to example 1.
The application has been described in detail hereinabove with reference to specific exemplary embodiments thereof. It will be understood that various modifications and changes may be made without departing from the scope of the application as defined by the appended claims. The detailed description and drawings are to be regarded in an illustrative rather than a restrictive sense, and if any such modifications and variations are desired to be included within the scope of the application described herein. Furthermore, the background art is intended to illustrate the state of the art and the meaning of the development and is not intended to limit the application or the field of application of the application.
Claims (5)
1. A preparation method of a hydrogen-resistant rare earth permanent magnet is characterized in that the hydrogen-resistant rare earth permanent magnet is Sm 2 (CoCuFeZr) 17 A magnet; the preparation method comprises the following steps:
(1) Smelting: smelting in a smelting furnace to obtain a magnet, wherein the mass percentage content of Sm is m, the sum of the mass percentage content of Co and Fe is n, and n is more than 3m, and obtaining an ingot;
(2) Pulverizing: crushing the cast ingot and pulverizing to obtain permanent magnet powder;
(3) Compression molding: stamping and forming the permanent magnet powder to obtain a green permanent magnet body;
(4) Sintering: sintering the permanent magnet green body at 1150-1250 ℃ for 3-5 hours to obtain a permanent magnet blank;
(5) And (3) heat treatment: cooling to room temperature after sintering, and then carrying out heat treatment on the permanent magnet blank in nitrogen atmosphere, wherein the heat treatment temperature is 650-1050 ℃ and the heat treatment time is more than 12 hours;
the heat treatment process comprises three steps:
stage one: firstly, heating the rare earth permanent magnet to 650-750 ℃, and carrying out heat preservation treatment for 2-3 h;
stage two: heating to 750-850 ℃ at a heating rate of 1-5 ℃/min, charging nitrogen into the vacuum furnace, controlling nitrogen partial pressure protective atmosphere in the furnace to be 200-300 mbar after the temperature reaches the furnace, and then carrying out heat preservation treatment for 2-3 h;
stage three: heating to 900-1050 ℃ at a heating rate of 1-5 ℃/min, and carrying out heat preservation treatment for 10-15 h;
(6) And (3) sealing: after heat treatment, the rare earth permanent magnet is sealed, and the specific steps are as follows: cooling the rare earth permanent magnet to room temperature, immersing the rare earth permanent magnet into a sealing agent for dip-coating sealing treatment, wherein the sealing agent is a cerium-containing water-based silane solvent, and curing after sealing is finished, so as to obtain the rare earth permanent magnet;
the sealing agent comprises a water-based silane solvent and cerium oxide, and the mass of the cerium oxide is 0.5-2.1% of that of the water-based silane solvent.
2. The method for preparing a hydrogen-resistant rare earth permanent magnet according to claim 1, wherein: the sealant also comprises nano SiO 2 。
3. The method for preparing a hydrogen-resistant rare earth permanent magnet according to claim 1, wherein: the baking temperature of the curing treatment is 150-180 ℃.
4. A rare earth permanent magnet having hydrogen resistance, characterized in that: the rare earth permanent magnet is prepared according to the preparation method of any one of claims 1 to 3;
the mass percentage content of Sm in the rare earth permanent magnet is m, and the sum of the mass percentage content of Co and Fe is n, wherein n is more than 3m;
the rare earth permanent magnet is Sm 2 (CoCuFeZr) 17 A magnet; and the mass percentage of Co of the rare earth permanent magnet is 45-55%; the mass percentage of Fe is 18-20%; 15-23% of Sm and 2-6% of Cu.
5. A rare earth permanent magnet having hydrogen resistance according to claim 4, characterized in that: the outside of the rare earth permanent magnet is provided with a sealing layer, and the sealing layer is formed by sealing a cerium-containing water-based silane solvent.
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