CN112750611B - Method for improving sintered NdFeB (NdFeB) crystal boundary diffusion by loading nano film - Google Patents
Method for improving sintered NdFeB (NdFeB) crystal boundary diffusion by loading nano film Download PDFInfo
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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
- H01F41/0293—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 diffusion of rare earth elements, e.g. Tb, Dy or Ho, into permanent magnets
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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
Abstract
The invention discloses a method for improving sintered NdFeB grain boundary diffusion by loading a nano film, which comprises the following steps: 1) preparing black sheets of sintered neodymium iron boron; 2) TiO loading is carried out on sintered neodymium iron boron black sheets by adopting a magnetron sputtering method2Preparing a nanocrystal film: using ceramic TiO2Target with background vacuum degree lower than 3.5X 10‑4Starting sputtering when Pa, taking argon as sputtering gas, and cooling in the sputtering process; 3) will support TiO2Soaking the sintered Nd-Fe-B black sheet of the nano-crystal film into a suspension containing terbium and/or dysprosium to perform grain boundary diffusion by a coating method; 4) and after the completion of the grain boundary diffusion, carrying out heat treatment, and after the heat treatment is finished, cooling to room temperature to complete the infiltration process. The invention couples the nano material with the adsorption characteristic with the coating process, thereby enhancing the binding force of the coating and improving the defects of easy falling off, uneven coating and the like of the coating.
Description
Technical Field
The invention belongs to the technical field of rare earth magnetic materials, and relates to a method for improving sintered NdFeB (NdFeB) grain boundary diffusion by loading a nano film.
Background
The sintered Nd-Fe-B is Nd with the volume ratio of more than 95 percent2Fe14The permanent magnetic material based on the B tetragonal phase is known as "magical king" because of its characteristics of extremely high magnetic energy product, coercive force, energy density, low cost, light weight and the like, and is widely applied to the fields of industrial permanent magnetic motors, wind power generation, consumer electronics (such as mobile phones and audios), household appliances and the like.
With the development of economic society, the demand of people for high-performance neodymium-iron-boron magnets is rapidly increased, which causes a serious shortage of heavy rare earth resources, and the grain boundary diffusion treatment technology is concerned by related researchers. The grain boundary diffusion treatment technique is to adhere Dy or Tb to the sintered magnet surface and perform diffusion treatment at a high temperature above the melting point of the neodymium-rich phase to allow heavy rare earth such as Dy or Tb to penetrate into the magnet through the grain boundary of the magnet.
At present, the main grain boundary diffusion technology of sintered neodymium iron boron includes: surface coating, vapor deposition, direct landfill, sputtering of heavy rare earth metal simple substances on the surface of the magnet and the like. The coating method of coating by using a powder penetrating agent and an organic solvent has been widely used for penetrating sintered neodymium iron boron due to the advantages of low requirements on equipment, low cost and the like. However, the method has the disadvantages of large waste amount, uneven coating, poor bonding force between the coating and the aggregate, and easy falling heat of the coating, so that the limited diffusion distance of the heavy rare earth element in the magnet is caused, the thickness of a sample is limited, the application range and the practicability of a grain boundary infiltration technology are also limited, and the development of the grain boundary technology is restricted.
Disclosure of Invention
An object of the present invention is to solve at least the above problems and/or disadvantages and to provide at least the advantages described hereinafter.
It is still another object of the present invention to provide a method for improving grain boundary diffusion of sintered NdFeB by loading a nano-film. The invention aims to use TiO by changing the magnet itself2The nano film loads sintered neodymium iron boron, so that the magnet has adsorption performance, and the mass transfer process of grain boundary diffusion is strengthened.
Therefore, the technical scheme provided by the invention is as follows:
a method for improving sintered NdFeB grain boundary diffusion by supporting a nano film comprises the following steps:
1) preparing black sheets of sintered neodymium iron boron with the orientation direction being less than or equal to 5 mm;
2) carrying out TiO loading on the sintered neodymium iron boron black sheet by adopting a magnetron sputtering method2Preparing a nanocrystal film: using ceramic TiO2Target, vacuum degree below 3.5X 10 in background-4Beginning sputtering when Pa, taking argon as sputtering gas, cooling in the sputtering process, and obtaining the ceramic TiO2The sputtering power of the target is 35-55W, and the sputtering time is 150-;
3) will support TiO2Immersing the sintered Nd-Fe-B black sheet of the nanocrystal film into a suspension containing terbium and/or dysprosium to perform grain boundary diffusion by a coating method;
4) and after the completion of the grain boundary diffusion, carrying out heat treatment, and after the heat treatment is finished, cooling to room temperature to complete the infiltration process.
Preferably, in the method for improving grain boundary diffusion of sintered NdFeB by supporting a nano thin film, in the step 2), the flow rate of the sputtering gas is 20 to 30sccm, and the sputtering pressure is 0.2 to 0.4 Pa.
Preferably, in the method for improving grain boundary diffusion of sintered NdFeB by supporting a nano-film, the method for preparing a suspension containing terbium and/or dysprosium in step 3) includes the steps of: and (2) placing any one or more of terbium oxide, terbium fluoride, dysprosium oxide and dysprosium fluoride in ethanol, propanol, n-butanol, cyclohexanol or isopropanol, and uniformly dispersing to prepare the suspension with the solid-to-liquid ratio of 0.8-1.5.
Preferably, in the method for improving grain boundary diffusion of sintered NdFeB by loading the nano film, the suspension is placed in an oven and is kept at the temperature of 80-150 ℃ for 1-2 hours.
Preferably, in the method for improving grain boundary diffusion of sintered NdFeB by loading a nano thin film, in step 3), the specific step of performing grain boundary diffusion by using a coating method includes: immersing the sintered neodymium iron boron black sheet into the suspension for 1-8 minutes, taking out and drying; then taking out and drying the dried sintered neodymium iron boron black sheets again in the turbid liquid for 1-8 minutes; the above operation is repeated several times.
Preferably, in the method for improving grain boundary diffusion of sintered NdFeB by loading a nano-film, in step 4), the heat treatment includes two treatments, respectively: the primary tempering temperature is 800-900 ℃, the heat preservation time is 2-6 h, the secondary tempering temperature is 460-510 ℃, and the heat preservation time is 3-8 h.
Preferably, in the method for improving grain boundary diffusion of sintered NdFeB by loading the nano-film, in the step 1), the specific method for preparing the sintered nd-fe-b black sheet with the orientation direction less than or equal to 5mm comprises the following steps:
1.1) mixing praseodymium-neodymium, pure iron, ferroboron alloy, pure aluminum, pure copper, cobalt, gallium and ferrozirconium alloy together;
1.2) smelting the mixed materials by a vacuum smelting furnace to prepare an alloy rapid-hardening casting sheet with a certain thickness;
1.3) carrying out hydrogen crushing, coarse powder mixing, airflow milling and fine powder mixing on the alloy quick-setting casting sheet to prepare neodymium iron boron alloy powder with the average particle size of 2-4 mu m;
1.4) pressing and packaging the mixed fine powder of the neodymium iron boron alloy powder in an oriented magnetic field;
1.5) carrying out cold isostatic pressing on the pressed blank;
1.6) placing the formed blank after the cold isostatic pressing into a vacuum sintering furnace for sintering, pre-pumping for 1-1.5 h, wherein the sintering temperature is 1000-1080 ℃, the heat preservation time is 7-12 h, and the tempering treatment is not performed.
And 1.7) processing the sintered blank, slicing by using a slicing machine, and grinding by using a double-end-face grinding machine to obtain the black sheet.
Preferably, in the method for improving grain boundary diffusion of sintered NdFeB by loading a nano-film, in step 1.1), the composition of the components of the NdFeB alloy comprises the following components in parts by weight: 26-31 parts of PrNd, 64.8-70.4 parts of Fe, 0.8-1.5 parts of B, 1-2 parts of Co, 0.05-0.15% of Al, 0.1-0.2 part of Cu, 0.15-0.25 part of Zr and 0.1-7.1 parts of Ga.
Preferably, in step 1.2) of the method for improving grain boundary diffusion of sintered NdFeB by supporting a nano thin film, the average thickness of the alloy rapid-solidification casting sheet is 0.15mm-0.45 mm.
Preferably, in the method for improving grain boundary diffusion of sintered NdFeB by loading a nano film, in step 1.4), a vacuum packaging machine is used to package the pressed blank without cracks and broken edges under the protection of nitrogen; in the step 1.5), the pressure in the cold isostatic pressing is 200 +/-15 MPa.
The invention provides a novel method for strengthening grain boundary diffusion by improving sintered neodymium iron boron, which at least comprises the following beneficial effects:
1. surface coating is a technique of forming a film layer on the surface of a substrate to improve the surface properties. The coating layer has chemical composition and structure different from that of the matrix material, and has surface performance, high binding strength between the coating layer and the matrix material, high economical efficiency and environment friendship. The thickness of the coating layer can be several millimeters or several micrometers, and the invention utilizes TiO2The nano film overcomes the defect of poor binding force of a coating method.
2. Compounding the conventional process of strengthening grain boundary penetration only by changing external conditions, and utilizing TiO2Loading sintered Nd-Fe-B on nano film by using TiO2The adsorption capacity of the nano film ensures that the coated coating is not easy to fall off.
3. By using TiO2The adsorption capacity of the nano film ensures that the coated coating is uniformThe sexual performance and the stability are improved.
4. Adding TiO into the mixture2The nano film is applied to the brand new rare earth technical field.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.
Detailed Description
The present invention is described in further detail below to enable those skilled in the art to practice the invention with reference to the description.
It will be understood that terms such as "having," "including," and "comprising," as used herein, do not preclude the presence or addition of one or more other elements or groups thereof.
The invention provides a method for improving grain boundary diffusion of sintered NdFeB by loading a nano film, which comprises the following steps of:
1) preparing black sheets of sintered neodymium iron boron with the orientation direction being less than or equal to 5 mm; preferably, black pieces of 3-4mm can be made.
2) Carrying out TiO loading on the sintered neodymium iron boron black sheet by adopting a magnetron sputtering method2Preparing a nanocrystal film: using ceramic TiO2Target, vacuum degree below 3.5X 10 in background-4Beginning sputtering when Pa, taking argon as sputtering gas, controlling the flow of the sputtering gas to be 20-30sccm and the sputtering gas pressure to be 0.2-0.4Pa, cooling in the sputtering process, and obtaining the ceramic TiO2The sputtering power of the target is 35-55W, and the sputtering time is 150-;
3) will support TiO2Immersing the sintered Nd-Fe-B black sheet of the nanocrystal film into a suspension containing terbium and/or dysprosium to perform grain boundary diffusion by a coating method;
4) and after the completion of the grain boundary diffusion, carrying out heat treatment, and after the heat treatment is finished, cooling to room temperature to complete the infiltration process.
In the above aspect, preferably, in step 2), the flow rate of the sputtering gas is 20 to 30sccm, and the sputtering gas pressure is 0.2 to 0.4 Pa.
In one embodiment of the present invention, preferably, in step 3), the method for preparing the suspension containing terbium and/or dysprosium includes the steps of: and (2) placing any one or more of terbium oxide, terbium fluoride, dysprosium oxide and dysprosium fluoride in ethanol, propanol, n-butanol, cyclohexanol or isopropanol, uniformly dispersing to prepare a suspension with the solid-to-liquid ratio of 0.8-1.5, and placing the prepared slurry into an oven for heat preservation.
In the scheme, the suspension is preferably placed in an oven for heat preservation, wherein the temperature in the oven is 80-150 ℃, and the heat preservation time is 1-2 hours.
In one embodiment of the present invention, preferably, in step 3), the specific step of performing grain boundary diffusion by using a coating method includes: immersing the sintered neodymium iron boron black sheet into the suspension for 1-8 minutes, taking out and drying; then taking out and drying the dried sintered neodymium iron boron black sheets again in the turbid liquid for 1-8 minutes; the above operation is repeated several times.
In one embodiment of the present invention, preferably, in step 4), the heat treatment includes two treatments, which are respectively: the primary tempering temperature is 800-900 ℃, the heat preservation time is 2-6 h, the secondary tempering temperature is 460-510 ℃, and the heat preservation time is 3-8 h.
In the above scheme, preferably, in step 1), the specific method for preparing the sintered nd-fe-b black sheet with the orientation direction less than or equal to 5mm includes the following steps:
1.1) mixing praseodymium-neodymium, pure iron, ferroboron alloy, pure aluminum, pure copper, cobalt, gallium and ferrozirconium alloy together;
1.2) smelting the mixed materials by a vacuum smelting furnace to prepare an alloy rapid-hardening casting sheet with a certain thickness;
1.3) carrying out hydrogen crushing, coarse powder mixing, airflow milling and fine powder mixing on the alloy quick-setting casting sheet to prepare neodymium iron boron alloy powder with the average particle size of 2-4 mu m; the specific method comprises the following steps:
hydrotreating (HD): hydrogen absorption Nb2Fe14B + H2 → Nb2Fe14BHx dehydrogenation Nb2Fe14BHx → Nb2Fe14B + H2, hydrogen absorption process, hydrogen pressure + 0.066- +0.098MPa dehydrogenation process, heating 580 ℃.
The purpose of hydrogen explosion is as follows: the reaction causes the bulk neodymium iron boron alloy to expand in volume, internal stress is generated, and the neodymium iron boron alloy is broken along the grain boundary and transgranular, so that pulverization is realized, and the purpose of crushing is achieved.
Mixing coarse powder, air flow grinding and mixing fine powder: and crushing the crystals to reach the required granularity.
Coarse powder mixing: coarsely mixing the crushed material tank with two-dimensional mixed powder, adding additives (sodium stearate and antioxidant), and mixing for 1.5-2 h.
And (3) jet milling: the coarse powder after stirring is blown up by high-pressure air flow, and the force is reduced by mutual collision, so that the coarse powder is called fine powder.
Mixing fine powder: and (3) adding an additive for the second time, wherein the additive is liquid and has the following functions: the powder is moistened, so that the subsequent pressing forming is facilitated, and the powder adhesion is increased.
1.4) adding an additive (a mixed solution of methyl carbonate and alkane) into the neodymium iron boron alloy powder subjected to the jet milling within 24 hours, and mixing for 120 +/-10 min in a V-shaped powder mixer to obtain D50: neodymium iron boron alloy powder with 3.45-4.20 μm, carbon content of 600-900ppm and O content of 500-3000ppm, and then pressing and packaging in an orientation magnetic field;
1.5) carrying out cold isostatic pressing on the pressed blank;
1.6) placing the formed blank after the cold isostatic pressing into a vacuum sintering furnace for sintering, pre-pumping for 1-1.5 h, wherein the sintering temperature is 1000-1080 ℃, the heat preservation time is 7-12 h, and the tempering treatment is not performed.
And 1.7) processing the sintered blank, slicing by using a slicing machine, and grinding by using a double-end-face grinding machine to obtain the black sheet.
In the above scheme, preferably, the composition of the neodymium iron boron alloy composition components comprises, by weight: 26-31 parts of Pr and Nd, 64.8-70.4 parts of Fe, 0.8-1.5 parts of B, 1-2 parts of Co, 0.05-0.15% of Al, 0.1-0.2 part of Cu, 0.15-0.25 part of Zr and 0.1-7.1 parts of Ga.
In one embodiment of the present invention, preferably, in step 1.2), the average thickness of the alloy rapid-solidification cast piece is 0.15mm to 0.45 mm.
In one embodiment of the present invention, preferably, in step 1.4), the post-pressing blank without cracks and broken edges is subjected to the packaging by using a vacuum packaging machine under the protection of nitrogen; in the step 1.5), the pressure in the cold isostatic pressing is 200 +/-15 MPa.
In order to make the technical solution of the present invention better understood by those skilled in the art, the following examples are now provided for illustration:
example 1
A method for improving sintered NdFeB grain boundary diffusion by loading a nano film comprises the following steps:
(1) the method is characterized in that praseodymium-neodymium with the purity of 0.99, BFe alloy with the purity of 0.18, ferrozirconium alloy with the purity of 0.76 and aluminum with the purity of 1, copper, cobalt, iron and gallium are mixed, the alloy components comprise Pr 7.75%/ppm, Nd 23.25%/ppm, Fe 64.85%/ppm, B1.5%/ppm, Co 2%/ppm, Al 0.15%/ppm, Cu 0.15%/ppm, Zr 0.25%/ppm and Ga 0.1%/ppm, and the mixed materials are smelted by a vacuum smelting furnace to prepare the alloy rapid-casting sheet with the sheet thickness of 95% between 0.15mm and 0.45mm, more than 0.45mm and less than 2% and less than 0.15mm and less than 2%.
(2) And (3) subjecting the obtained throwing piece with the columnar crystal proportion of more than 90% to hydrogenation treatment (HD), coarse powder mixing, airflow milling and fine powder mixing to obtain D50: neodymium iron boron alloy powder with the diameter of 3.45-3.65 μm. The specific method comprises the following steps:
hydrotreating (HD): hydrogen-absorbing Nb2Fe14B+H2→Nb2Fe14BHxDehydrogenated Nb2Fe14BHx→Nb2Fe14B+H2Hydrogen absorbing process, hydrogen pressure + 0.066- +0.098MPa dehydrogenation process, heating 580 deg.C
The purpose of hydrogen explosion is as follows: the reaction causes the bulk neodymium iron boron alloy to expand in volume, internal stress is generated, and the neodymium iron boron alloy is broken along the grain boundary and transgranular, so that pulverization is realized, and the purpose of crushing is achieved.
Mixing coarse powder, air flow grinding and mixing fine powder: and crushing the crystals to reach the required granularity.
Coarse powder mixing: coarsely mixing the crushed material tank with two-dimensional mixed powder, adding additives (sodium stearate and antioxidant), and mixing for 1.5-2 h.
And (3) jet milling: the coarse powder after stirring is blown up by high-pressure air flow, and the force is reduced by mutual collision, so that the coarse powder is called fine powder.
Mixing fine powder: and (3) adding an additive for the second time, wherein the additive is liquid and has the following functions: the powder is moistened, so that the subsequent pressing forming is facilitated, and the powder adhesion is increased. This is also done in subsequent embodiments.
(3) Pressing the mixed fine powder in an oriented magnetic field with the magnetic field intensity of more than or equal to 11000Gs and the current of 700-1100A.
(4) And (3) carrying out cold isostatic pressing on the pressed blank under the pressure of 200 +/-15 MPa.
(5) And (3) cutting materials within 24 hours after cold isostatic pressing, sintering in a vacuum sintering furnace, pre-pumping for 1-1.5 hours, sintering at the temperature of 1000-1080 ℃, keeping the temperature for 7-12 hours, and not performing tempering treatment.
The sintered blank was passed through a dicing, lapping, slicing, lapping to produce 19+0.04/0 x 13+0.12/+0.05 x 4+0.08/+0.02mm black flakes (i.e., black flakes having a thickness of 4mm, written in the form of length x width x thickness, later +/-representing tolerances).
Loading Ti' O on the processed black sheet on the machine frame by adopting a magnetron sputtering method2And (4) preparing a nanocrystal film. At room temperature, TiO with a diameter of 50mm is used2Ceramic target (purity 99.99%), and sintered Nd-Fe-B black sheet on the frame by magnetron sputtering method to prepare TiO2A film. Background vacuum of less than 3.5X 10-4And starting sputtering when Pa, taking high-purity argon as a sputtering gas, wherein the flow rate of the sputtering gas is 25sccm, the sputtering gas pressure is 0.3Pa, and introducing cooling water for cooling in the sputtering process. TiO 22The sputtering power of the target was 45W, and the sputtering time was 200 min.
The method is characterized in that the heat is preserved for 1 hour in an oven at 100 ℃, the solid is terbium fluoride, the liquid is propanol, and the solid-liquid dosage ratio is 1: 1.2, uniformly stirring the mixed suspension of terbium fluoride and propanol, and adding Ti' O2The nanocrystal film was coated to form a coating with a thickness of 15 μm.
And (3) placing the sheet coated with the terbium fluoride mixed turbid liquid on the surface in a graphite box which is subjected to heat preservation at 100 ℃ in advance, and carrying out heat treatment twice in a tempering furnace, wherein the primary tempering temperature is 880 ℃, the heat preservation time is 3 hours, the secondary tempering temperature is 480 ℃, and the heat preservation time is 4 hours. And after the heat treatment is finished, cooling to room temperature to finish the infiltration process.
The penetrated sample is made into a sample with 7 x 4mm (M), and the magnetic property is tested by using a NIM-15000H bulk rare earth permanent magnet measuring instrument.
Example 2
(1) The method is characterized in that praseodymium-neodymium with the purity of 0.99, BFe alloy with the purity of 0.18, ferrozirconium alloy with the purity of 0.76 and aluminum with the purity of 1, copper, cobalt, iron and gallium are mixed, the alloy components comprise Pr 7.75%/ppm, Nd 23.25%/ppm, Fe 64.85%/ppm, B1.5%/ppm, Co 2%/ppm, Al 0.15%/ppm, Cu 0.15%/ppm, Zr0.25%/ppm and Ga 0.1%/ppm, and the mixed materials are smelted by a vacuum smelting furnace to prepare the alloy rapid-casting sheet with the sheet thickness of 95% between 0.15mm and 0.45mm, more than 0.45mm and less than 2% and less than 0.15mm and less than 2%.
(2) And (3) subjecting the obtained throwing piece with the columnar crystal proportion of more than 90% to hydrogenation treatment (HD), coarse powder mixing, airflow milling and fine powder mixing to obtain D50: neodymium iron boron alloy powder with the diameter of 3.45-3.65 μm.
(3) And pressing the alloy powder after the fine powder mixing in an oriented magnetic field with the magnetic field intensity of more than or equal to 11000Gs and the current of 700-1100A.
(4) And (3) carrying out cold isostatic pressing on the pressed blank under the pressure of 200 +/-15 MPa.
(5) And (3) cutting materials within 24 hours after cold isostatic pressing, sintering in a vacuum sintering furnace, pre-pumping for 1-1.5 hours, sintering at the temperature of 1000-1080 ℃, keeping the temperature for 7-12 hours, and not performing tempering treatment.
The sintered blank was sliced, lapped, sliced, and lapped to obtain a black piece 19+0.04/0 x 13+0.12/+0.05 x 3.5+0.08/+0.02mm (m) with an orientation of 3.5 mm.
Loading Ti' O on the processed black sheet on the machine frame by adopting a magnetron sputtering method2And (4) preparing a nanocrystal film. At room temperature, TiO with a diameter of 50mm is used2Ceramic target (purity 99.99%), on a frame by magnetron sputteringPreparing TiO on the sintered Nd-Fe-B black sheet2A film. Background vacuum of less than 3.5X 10-4And starting sputtering when Pa, taking high-purity argon as a sputtering gas, wherein the flow rate of the sputtering gas is 25sccm, the sputtering gas pressure is 0.3Pa, and introducing cooling water for cooling in the sputtering process. TiO 22The sputtering power of the target was 45W, and the sputtering time was 200 min.
The method is characterized in that the heat is preserved for 1 hour in an oven at 100 ℃, the solid is terbium fluoride, the liquid is propanol, and the solid-liquid dosage ratio is 1: 1.2, uniformly stirring the mixed suspension of terbium fluoride and propanol, and adding Ti' O2The nanocrystal film was coated to form a coating with a thickness of 15 μm.
And (3) placing the sheet coated with the terbium fluoride mixed turbid liquid on the surface in a graphite box which is subjected to heat preservation at 100 ℃ in advance, and carrying out heat treatment twice in a tempering furnace, wherein the primary tempering temperature is 880 ℃, the heat preservation time is 3 hours, the secondary tempering temperature is 480 ℃, and the heat preservation time is 4 hours. And after the heat treatment is finished, cooling to room temperature to finish the infiltration process.
The samples after permeation are made into 7 × 3.5mm (M) samples, and the magnetic performance is tested by using a NIM-15000H bulk rare earth permanent magnet measuring instrument.
Example 3
(1) The method is characterized in that praseodymium-neodymium with the purity of 0.99, BFe alloy with the purity of 0.18, ferrozirconium alloy with the purity of 0.76 and aluminum with the purity of 1, copper, cobalt, iron and gallium are mixed, the alloy components comprise Pr 7.75%/ppm, Nd 23.25%/ppm, Fe 64.85%/ppm, B1.5%/ppm, Co 2%/ppm, Al 0.15%/ppm, Cu 0.15%/ppm, Zr0.25%/ppm and Ga 0.1%/ppm, and the mixed materials are smelted by a vacuum smelting furnace to prepare the alloy rapid-casting sheet with the sheet thickness of 95% between 0.15mm and 0.45mm, more than 0.45mm and less than 2% and less than 0.15mm and less than 2%.
(2) And (3) subjecting the obtained throwing piece with the columnar crystal proportion of more than 90% to hydrogenation treatment (HD), coarse powder mixing, airflow milling and fine powder mixing to obtain D50: neodymium iron boron alloy powder with the diameter of 3.45-3.65 μm.
(3) And pressing the alloy powder after the fine powder mixing in an oriented magnetic field with the magnetic field intensity of more than or equal to 11000Gs and the current of 700-1100A.
(4) And (3) carrying out cold isostatic pressing on the pressed blank under the pressure of 200 +/-15 MPa.
(5) And (3) cutting materials within 24 hours after cold isostatic pressing, sintering in a vacuum sintering furnace, pre-pumping for 1-1.5 hours, sintering at the temperature of 1000-1080 ℃, keeping the temperature for 7-12 hours, and not performing tempering treatment.
And (3) slicing and lapping the sintered blank to obtain a black sheet with the orientation direction of 3mm, namely the orientation direction of 3mm, of 19+0.04/0 x 13+0.12/+0.05 x 3+0.08/+0.02mm (M).
Loading Ti' O on the processed black sheet on the machine frame by adopting a magnetron sputtering method2And (4) preparing a nanocrystal film. At room temperature, TiO with a diameter of 50mm is used2Ceramic target (purity 99.99%), and sintered Nd-Fe-B black sheet on the frame by magnetron sputtering method to prepare TiO2A film. Background vacuum of less than 3.5X 10-4And starting sputtering when Pa, taking high-purity argon as a sputtering gas, wherein the flow rate of the sputtering gas is 25sccm, the sputtering gas pressure is 0.3Pa, and introducing cooling water for cooling in the sputtering process. TiO 22The sputtering power of the target was 45W, and the sputtering time was 200 min.
The method is characterized in that the heat is preserved for 1 hour in an oven at 100 ℃, the solid is terbium fluoride, the liquid is propanol, and the solid-liquid dosage ratio is 1: 1.2, uniformly stirring the mixed suspension of terbium fluoride and propanol, and adding Ti' O2The nanocrystal film was coated to form a coating with a thickness of 15 μm.
And (3) placing the sheet coated with the terbium fluoride mixed turbid liquid on the surface in a graphite box which is subjected to heat preservation at 100 ℃ in advance, and carrying out heat treatment twice in a tempering furnace, wherein the primary tempering temperature is 880 ℃, the heat preservation time is 3 hours, the secondary tempering temperature is 480 ℃, and the heat preservation time is 4 hours. And after the heat treatment is finished, cooling to room temperature to finish the infiltration process.
The penetrated sample is made into a sample with 7 × 3mm (M) and is subjected to magnetic performance test by using a NIM-15000H bulk rare earth permanent magnet measuring instrument.
Example 4
(1) The method is characterized in that praseodymium-neodymium with the purity of 0.99, BFe alloy with the purity of 0.18, ferrozirconium alloy with the purity of 0.76 and aluminum with the purity of 1, copper, cobalt, iron and gallium are mixed, the alloy components comprise Pr 7.75%/ppm, Nd 23.25%/ppm, Fe 64.85%/ppm, B1.5%/ppm, Co 2%/ppm, Al 0.15%/ppm, Cu 0.15%/ppm, Zr 0.25%/ppm and Ga 0.1%/ppm, and the mixed materials are smelted by a vacuum smelting furnace to prepare the alloy rapid-casting sheet with the sheet thickness of 95% between 0.15mm and 0.45mm, more than 0.45mm and less than 2% and less than 0.15mm and less than 2%.
(2) And (3) subjecting the obtained throwing piece with the columnar crystal proportion of more than 90% to hydrogenation treatment (HD), coarse powder mixing, airflow milling and fine powder mixing to obtain D50: neodymium iron boron alloy powder with the diameter of 3.45-3.65 μm.
(3) Pressing the mixed fine powder in an oriented magnetic field with the magnetic field intensity of more than or equal to 11000Gs and the current of 700-1100A.
(4) And (3) carrying out cold isostatic pressing on the pressed blank under the pressure of 200 +/-15 MPa.
(5) And (3) cutting materials within 24 hours after cold isostatic pressing, sintering in a vacuum sintering furnace, pre-pumping for 1.25 hours, keeping the sintering temperature at 1040 ℃ for 9.5 hours, and not tempering.
The sintered blank was passed through a dicing, lapping, slicing, lapping to produce 19+0.04/0 x 13+0.12/+0.05 x 4+0.08/+0.02mm black flakes (i.e., black flakes having a thickness of 3mm, written in a format of length x width x thickness, later +/-representing tolerances).
Loading Ti' O on the processed black sheet on the machine frame by adopting a magnetron sputtering method2And (4) preparing a nanocrystal film. At room temperature, TiO with a diameter of 50mm is used2Ceramic target (purity 99.99%), and sintered Nd-Fe-B black sheet on the frame by magnetron sputtering method to prepare TiO2A film. Background vacuum of less than 3.5X 10-4And starting sputtering when Pa, taking high-purity argon as a sputtering gas, controlling the flow of the sputtering gas to be 20sccm and the sputtering pressure to be 0.4Pa, and introducing cooling water for cooling in the sputtering process. TiO 22The sputtering power of the target was 35W, and the sputtering time was 250 min.
The method is characterized in that the heat is preserved for 1 hour in an oven at 100 ℃, the solid is terbium fluoride, the liquid is propanol, and the solid-liquid dosage ratio is 1: 1.2, uniformly stirring mixed suspension of terbium fluoride and propanolFor good Ti' O loading2The nanocrystal film was coated to form a coating with a thickness of 15 μm.
And (3) placing the sheet coated with the terbium fluoride mixed turbid liquid on the surface in a graphite box which is subjected to heat preservation at 100 ℃ in advance, and carrying out heat treatment twice in a tempering furnace, wherein the primary tempering temperature is 800 ℃, the heat preservation time is 6 hours, the secondary tempering temperature is 460 ℃, and the heat preservation time is 8 hours. And after the heat treatment is finished, cooling to room temperature to finish the infiltration process.
The penetrated sample is made into a sample with 7 x 4mm (M), and the magnetic property is tested by using a NIM-15000H bulk rare earth permanent magnet measuring instrument.
Example 5
(1) The method is characterized in that praseodymium-neodymium with the purity of 0.99, BFe alloy with the purity of 0.18, ferrozirconium alloy with the purity of 0.76 and aluminum with the purity of 1, copper, cobalt, iron and gallium are mixed, the alloy components comprise Pr 7.75%/ppm, Nd 23.25%/ppm, Fe 64.85%/ppm, B1.5%/ppm, Co 2%/ppm, Al 0.15%/ppm, Cu 0.15%/ppm, Zr0.25%/ppm and Ga 0.1%/ppm, and the mixed materials are smelted by a vacuum smelting furnace to prepare the alloy rapid-casting sheet with the sheet thickness of 95% between 0.15mm and 0.45mm, more than 0.45mm and less than 2% and less than 0.15mm and less than 2%.
(2) And (3) subjecting the obtained throwing piece with the columnar crystal proportion of more than 90% to hydrogenation treatment (HD), coarse powder mixing, airflow milling and fine powder mixing to obtain D50: neodymium iron boron alloy powder with the diameter of 3.45-3.65 μm.
(3) And pressing the alloy powder after the fine powder mixing in an oriented magnetic field with the magnetic field intensity of more than or equal to 11000Gs and the current of 700-1100A.
(4) And (3) carrying out cold isostatic pressing on the pressed blank under the pressure of 215 Mpa.
(5) And (3) cutting materials within 24 hours after cold isostatic pressing, sintering in a vacuum sintering furnace, pre-pumping for 1.5 hours, keeping the sintering temperature at 1000 ℃ for 7 hours, and not performing tempering treatment.
The sintered blank was cut into pieces, and the pieces were cut into pieces, and milled into black pieces having an orientation of 3mm, and having a thickness of 19+0.04/0 x 13+0.12/+0.05 x 4+0.08/+0.02mm (M).
Loading Ti' O on the processed black sheet on the machine frame by adopting a magnetron sputtering method2And (4) preparing a nanocrystal film. At room temperature, TiO with a diameter of 50mm is used2Ceramic target (purity 99.99%), and sintered Nd-Fe-B black sheet on the frame by magnetron sputtering method to prepare TiO2A film. Background vacuum of less than 3.5X 10-4And starting sputtering when Pa, taking high-purity argon as sputtering gas, wherein the flow rate of the sputtering gas is 20sccm, the sputtering gas pressure is 0.3Pa, and introducing cooling water for cooling in the sputtering process. TiO 22The sputtering power of the target was 55W, and the sputtering time was 150 min.
The method is characterized in that the heat is preserved for 1 hour in an oven at 100 ℃, the solid is terbium fluoride, the liquid is propanol, and the solid-liquid dosage ratio is 1: 1.2, uniformly stirring the mixed suspension of terbium fluoride and propanol, and adding Ti' O2The nanocrystal film was coated to form a coating with a thickness of 15 μm.
And (3) placing the sheet coated with the terbium fluoride mixed turbid liquid on the surface in a graphite box which is subjected to heat preservation at 100 ℃ in advance, and carrying out heat treatment twice in a tempering furnace, wherein the primary tempering temperature is 850 ℃, the heat preservation time is 4 hours, the secondary tempering temperature is 485 ℃, and the heat preservation time is 5.5 hours. And after the heat treatment is finished, cooling to room temperature to finish the infiltration process.
The penetrated sample is made into a sample with 7 x 4mm (M), and the magnetic property is tested by using a NIM-15000H bulk rare earth permanent magnet measuring instrument.
Example 6
(1) The method is characterized in that praseodymium-neodymium with the purity of 0.99, BFe alloy with the purity of 0.18, ferrozirconium alloy with the purity of 0.76 and aluminum with the purity of 1, copper, cobalt, iron and gallium are mixed, the alloy components comprise Pr 7.75%/ppm, Nd 23.25%/ppm, Fe 64.85%/ppm, B1.5%/ppm, Co 2%/ppm, Al 0.15%/ppm, Cu 0.15%/ppm, Zr0.25%/ppm and Ga 0.1%/ppm, and the mixed materials are smelted by a vacuum smelting furnace to prepare the alloy rapid-casting sheet with the sheet thickness of 95% between 0.15mm and 0.45mm, more than 0.45mm and less than 2% and less than 0.15mm and less than 2%.
(2) And (3) subjecting the obtained throwing piece with the columnar crystal proportion of more than 90% to hydrogenation treatment (HD), coarse powder mixing, airflow milling and fine powder mixing to obtain D50: neodymium iron boron alloy powder with the diameter of 3.45-3.65 μm.
(3) And pressing the alloy powder after the fine powder mixing in an oriented magnetic field with the magnetic field intensity of more than or equal to 11000Gs and the current of 700-1100A.
(4) And carrying out cold isostatic pressing on the pressed blank under the pressure of 185 MPa.
(5) And (3) cutting materials within 24 hours after cold isostatic pressing, sintering in a vacuum sintering furnace, pre-pumping for 1 hour, keeping the sintering temperature at 1080 ℃, keeping the temperature for 12 hours, and not tempering.
And (3) slicing and lapping the sintered blank to obtain a black sheet with the orientation direction of 3mm, namely the orientation direction of 3mm, of 19+0.04/0 x 13+0.12/+0.05 x 4+0.08/+0.02mm (M).
Loading Ti' O on the processed black sheet on the machine frame by adopting a magnetron sputtering method2And (4) preparing a nanocrystal film. At room temperature, TiO with a diameter of 50mm is used2Ceramic target (purity 99.99%), and sintered Nd-Fe-B black sheet on the frame by magnetron sputtering method to prepare TiO2A film. Background vacuum of less than 3.5X 10-4And starting sputtering when Pa, taking high-purity argon as sputtering gas, wherein the flow rate of the sputtering gas is 30sccm, the sputtering gas pressure is 0.2Pa, and introducing cooling water for cooling in the sputtering process. TiO 22The sputtering power of the target was 40W, and the sputtering time was 220 min.
The method is characterized in that the heat is preserved for 1 hour in an oven at 100 ℃, the solid is terbium fluoride, the liquid is propanol, and the solid-liquid dosage ratio is 1: 1.2, uniformly stirring the mixed suspension of terbium fluoride and propanol, and adding Ti' O2The nanocrystal film was coated to form a coating with a thickness of 15 μm.
And (3) placing the sheet coated with the terbium fluoride mixed turbid liquid on the surface in a graphite box which is subjected to heat preservation at 100 ℃ in advance, and carrying out heat treatment twice in a tempering furnace, wherein the primary tempering temperature is 900 ℃, the heat preservation time is 2 hours, the secondary tempering temperature is 510 ℃, and the heat preservation time is 3 hours. And after the heat treatment is finished, cooling to room temperature to finish the infiltration process.
The penetrated sample is made into a sample with 7 x 4mm (M), and the magnetic property is tested by using a NIM-15000H bulk rare earth permanent magnet measuring instrument.
Comparative example 1
(1) The method is characterized in that praseodymium-neodymium with the purity of 0.99, BFe alloy with the purity of 0.18, ferrozirconium alloy with the purity of 0.76 and aluminum with the purity of 1, copper, cobalt, iron and gallium are mixed, the alloy components comprise Pr 7.75%/ppm, Nd 23.25%/ppm, Fe 64.85%/ppm, B1.5%/ppm, Co 2%/ppm, Al 0.15%/ppm, Cu 0.15%/ppm, Zr0.25%/ppm and Ga 0.1%/ppm, and the mixed materials are smelted by a vacuum smelting furnace to prepare the alloy rapid-casting sheet with the sheet thickness of 95% between 0.15mm and 0.45mm, more than 0.45mm and less than 2% and less than 0.15mm and less than 2%.
(2) And (3) subjecting the obtained throwing piece with the columnar crystal proportion of more than 90% to hydrogenation treatment (HD), coarse powder mixing, airflow milling and fine powder mixing to obtain D50: neodymium iron boron alloy powder with the diameter of 3.45-3.65 μm.
(3) And pressing the alloy powder after the fine powder mixing in an oriented magnetic field with the magnetic field intensity of more than or equal to 11000Gs and the current of 700-1100A.
(4) And (3) carrying out cold isostatic pressing on the pressed blank under the pressure of 200 +/-15 MPa.
(5) And (3) cutting materials within 24 hours after cold isostatic pressing, sintering in a vacuum sintering furnace, pre-pumping for 1-1.5 hours, sintering at the temperature of 1000-1080 ℃, keeping the temperature for 7-12 hours, and not performing tempering treatment.
And (3) slicing and lapping the sintered blank to obtain 19+0.04/0 x 13+0.12/+0.05 x 3+0.08/+0.02mm (M), namely a black chip with the orientation direction of 3 mm.
The method is characterized in that the heat is preserved for 1 hour in an oven at 100 ℃, the solid is terbium fluoride, the liquid is propanol, and the solid-liquid dosage ratio is 1: 1.2, uniformly stirring the mixed suspension of terbium fluoride and propanol, and adding Ti' O2The nanocrystal film was coated to form a coating with a thickness of 15 μm.
And (3) placing the sheet coated with the terbium fluoride mixed turbid liquid on the surface in a graphite box which is subjected to heat preservation at 100 ℃ in advance, and carrying out heat treatment twice in a tempering furnace, wherein the primary tempering temperature is 880 ℃, the heat preservation time is 3 hours, the secondary tempering temperature is 480 ℃, and the heat preservation time is 4 hours. And after the heat treatment is finished, cooling to room temperature to finish the infiltration process.
The penetrated sample is made into a sample with 7 × 3mm (M) and is subjected to magnetic performance test by using a NIM-15000H bulk rare earth permanent magnet measuring instrument.
Comparative example 2
(1) The method is characterized in that praseodymium-neodymium with the purity of 0.99, BFe alloy with the purity of 0.18, ferrozirconium alloy with the purity of 0.76 and aluminum with the purity of 1, copper, cobalt, iron and gallium are mixed, the alloy components comprise Pr 7.75%/ppm, Nd 23.25%/ppm, Fe 64.85%/ppm, B1.5%/ppm, Co 2%/ppm, Al 0.15%/ppm, Cu 0.15%/ppm, Zr0.25%/ppm and Ga 0.1%/ppm, and the mixed materials are smelted by a vacuum smelting furnace to prepare the alloy rapid-casting sheet with the sheet thickness of 95% between 0.15mm and 0.45mm, more than 0.45mm and less than 2% and less than 0.15mm and less than 2%.
(2) And (3) subjecting the obtained throwing piece with the columnar crystal proportion of more than 90% to hydrogenation treatment (HD), coarse powder mixing, airflow milling and fine powder mixing to obtain D50: neodymium iron boron alloy powder with the diameter of 3.45-3.65 μm.
(3) And pressing the alloy powder after the fine powder mixing in an oriented magnetic field with the magnetic field intensity of more than or equal to 11000Gs and the current of 700-1100A.
(4) And (3) carrying out cold isostatic pressing on the pressed blank under the pressure of 200 +/-15 MPa.
(5) And (3) cutting materials within 24 hours after cold isostatic pressing, sintering in a vacuum sintering furnace, pre-pumping for 1-1.5 hours, sintering at the temperature of 1000-1080 ℃, and keeping the temperature for 7-12 hours. And (3) carrying out two-stage tempering treatment after sintering, wherein the first-stage tempering temperature is 900 ℃, the heat preservation time is 4 hours, the second-stage tempering temperature is 505 ℃, and the heat preservation time is 4 hours.
And (3) slicing and lapping the tempered blank to obtain 19+0.04/0 x 13+0.12/+0.05 x 3+0.08/+0.02mm (M), namely black chips with the orientation direction of 3 mm.
The processed sample is made into a sample with 7 × 3mm (M), and a NIM-15000H bulk rare earth permanent magnet measuring instrument is used for magnetic property test.
Table 1 shows the magnetic property data of examples 1 to 6 and comparative examples 1 and 2
As can be seen from the magnetic property data of the embodiment 1, the embodiment 2, the embodiment 3, the embodiment 4, the embodiment 5 and the embodiment 6 and the comparative example 1 and the comparative example 2, the coercivity is obviously improved due to the traditional coating method due to the grain boundary diffusion effect of the method of the invention, and the thinner the sample thickness is, the higher the coercivity is.
The number of modules and the processing scale described herein are intended to simplify the description of the invention. Applications, modifications and variations of the method for improving grain boundary diffusion of sintered NdFeB for supported nano-thin films of the present invention will be apparent to those skilled in the art.
As described above, according to the invention, the traditional process of strengthening grain boundary permeation only by changing external conditions in the prior art is compounded, the nano material with adsorption property is coupled with the coating process, and the terbium and dysprosium capable of obviously improving the coercive force is easier to permeate through three stages of external diffusion, internal diffusion and surface adsorption by utilizing the complex internal pore channel structure of the adsorption material, so that the binding force of the coating is enhanced, and the defects of easy falling off, uneven coating and the like of the coating are improved.
While embodiments of the invention have been disclosed above, it is not limited to the applications listed in the description and the embodiments, which are fully applicable in all kinds of fields of application of the invention, and further modifications may readily be effected by those skilled in the art, so that the invention is not limited to the specific details without departing from the general concept defined by the claims and the scope of equivalents.
Claims (10)
1. A method for improving sintered NdFeB grain boundary diffusion by loading a nano film is characterized by comprising the following steps:
1) preparing black sheets of sintered neodymium iron boron with the orientation direction being less than or equal to 5 mm;
2) carrying out TiO loading on the sintered neodymium iron boron black sheet by adopting a magnetron sputtering method2Preparing a nanocrystal film: using ceramic TiO2Target, vacuum degree below 3.5X 10 in background-4Beginning sputtering when Pa, taking argon as sputtering gas, cooling in the sputtering process, and obtaining the ceramic TiO2The sputtering power of the target is 35-55W, and the sputtering time is 150-;
3) will be negativeTiO supported catalyst2Immersing the sintered Nd-Fe-B black sheet of the nanocrystal film into a suspension containing terbium and/or dysprosium to perform grain boundary diffusion by a coating method;
4) and after the completion of the grain boundary diffusion, carrying out heat treatment, and after the heat treatment is finished, cooling to room temperature to complete the infiltration process.
2. The method for improving grain boundary diffusion of sintered NdFeB with supported nano-thin film according to claim 1, wherein in the step 2), the flow rate of the sputtering gas is 20 to 30sccm, and the sputtering pressure is 0.2 to 0.4 Pa.
3. The method for improving grain boundary diffusion of sintered NdFeB with supported nano-films according to claim 1, wherein in the step 3), the method for preparing the suspension containing terbium and/or dysprosium comprises the following steps: and (2) placing any one or more of terbium oxide, terbium fluoride, dysprosium oxide and dysprosium fluoride in ethanol, propanol, n-butanol, cyclohexanol or isopropanol, and uniformly dispersing to prepare the suspension with the solid-to-liquid ratio of 0.8-1.5.
4. The method for improving grain boundary diffusion of sintered NdFeB as claimed in claim 3, wherein the suspension is placed in an oven and kept at the temperature of 80-150 ℃ for 1-2 hours.
5. The method for improving grain boundary diffusion of sintered NdFeB by supporting nano-films according to claim 1, wherein the step 3) of carrying out grain boundary diffusion by a coating method comprises the following specific steps: immersing the sintered neodymium iron boron black sheet into the suspension for 1-8 minutes, taking out and drying; then taking out and drying the dried sintered neodymium iron boron black sheets again in the turbid liquid for 1-8 minutes; the above operation is repeated several times.
6. The method for improving grain boundary diffusion of sintered NdFeB as claimed in claim 1, wherein in the step 4), the heat treatment comprises two treatments, which are respectively: the primary tempering temperature is 800-900 ℃, the heat preservation time is 2-6 h, the secondary tempering temperature is 460-510 ℃, and the heat preservation time is 3-8 h.
7. The method for improving grain boundary diffusion of sintered NdFeB by supporting nano-films as claimed in any one of claims 1 to 6, wherein in the step 1), the specific method for preparing the sintered NdFeB black sheet with the orientation direction being less than or equal to 5mm comprises the following steps:
1.1) mixing praseodymium-neodymium, pure iron, ferroboron alloy, pure aluminum, pure copper, cobalt, gallium and ferrozirconium alloy together;
1.2) smelting the mixed materials by a vacuum smelting furnace to prepare an alloy rapid-hardening casting sheet with a certain thickness;
1.3) carrying out hydrogen crushing, coarse powder mixing, airflow milling and fine powder mixing on the alloy quick-setting casting sheet to prepare neodymium iron boron alloy powder with the average particle size of 2-4 mu m;
1.4) pressing and packaging the mixed fine powder of the neodymium iron boron alloy powder in an oriented magnetic field;
1.5) carrying out cold isostatic pressing on the pressed blank;
1.6) placing the formed blank after cold isostatic pressing in a vacuum sintering furnace for sintering, pre-pumping for 1-1.5 h, wherein the sintering temperature is 1000-;
and 1.7) processing the sintered blank, slicing by using a slicing machine, and grinding by using a double-end-face grinding machine to obtain the black sheet.
8. The method for improving grain boundary diffusion of sintered NdFeB by supporting a nano-film as claimed in claim 7, wherein in the step 1.1), the composition of the components of the NdFeB alloy comprises the following components in parts by weight: 26-31 parts of PrNd, 64.8-70.4 parts of Fe, 0.8-1.5 parts of B, 1-2 parts of Co, 0.05-0.15% of Al, 0.1-0.2 part of Cu, 0.15-0.25 part of Zr and 0.1-7.1 parts of Ga.
9. The method for improving grain boundary diffusion of sintered NdFeB by supporting nano-thin films according to claim 7, wherein in the step 1.2), the average thickness of the alloy rapid-solidification casting sheet is 0.15mm-0.45 mm.
10. The method for improving grain boundary diffusion of sintered NdFeB with supported nano-films according to claim 7, wherein in the step 1.4), the pressed blank without cracks and broken edges is subjected to packaging by using a vacuum packaging machine under the protection of nitrogen; in the step 1.5), the pressure in the cold isostatic pressing is 200 +/-15 MPa.
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| CN108231392A (en) * | 2016-12-12 | 2018-06-29 | 现代自动车株式会社 | The method for preparing rare-earth permanent magnet |
| CN108962582A (en) * | 2018-07-20 | 2018-12-07 | 烟台首钢磁性材料股份有限公司 | A kind of neodymium iron boron magnetic body coercivity method for improving |
| BR102018013463A2 (en) * | 2017-06-30 | 2019-01-15 | Toyota Jidosha Kabushiki Kaisha | rare earth magnet and production method of it |
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| CN108231392A (en) * | 2016-12-12 | 2018-06-29 | 现代自动车株式会社 | The method for preparing rare-earth permanent magnet |
| BR102018013463A2 (en) * | 2017-06-30 | 2019-01-15 | Toyota Jidosha Kabushiki Kaisha | rare earth magnet and production method of it |
| CN108962582A (en) * | 2018-07-20 | 2018-12-07 | 烟台首钢磁性材料股份有限公司 | A kind of neodymium iron boron magnetic body coercivity method for improving |
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