CN114517125A - Isostatic pressing liquid medium and preparation method of neodymium iron boron magnet - Google Patents
Isostatic pressing liquid medium and preparation method of neodymium iron boron magnet Download PDFInfo
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- CN114517125A CN114517125A CN202011312274.6A CN202011312274A CN114517125A CN 114517125 A CN114517125 A CN 114517125A CN 202011312274 A CN202011312274 A CN 202011312274A CN 114517125 A CN114517125 A CN 114517125A
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- 238000000462 isostatic pressing Methods 0.000 title claims abstract description 95
- 229910001172 neodymium magnet Inorganic materials 0.000 title claims abstract description 64
- 239000007788 liquid Substances 0.000 title claims abstract description 34
- 238000002360 preparation method Methods 0.000 title claims abstract description 10
- 238000000034 method Methods 0.000 claims abstract description 42
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 39
- 239000000839 emulsion Substances 0.000 claims abstract description 29
- 238000005496 tempering Methods 0.000 claims description 28
- 238000005245 sintering Methods 0.000 claims description 22
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 14
- 239000001301 oxygen Substances 0.000 claims description 14
- 229910052760 oxygen Inorganic materials 0.000 claims description 14
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 11
- 239000002199 base oil Substances 0.000 claims description 11
- 239000003921 oil Substances 0.000 claims description 9
- 235000019198 oils Nutrition 0.000 claims description 9
- 229910052788 barium Inorganic materials 0.000 claims description 8
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 claims description 8
- QRUDEWIWKLJBPS-UHFFFAOYSA-N benzotriazole Chemical compound C1=CC=C2N[N][N]C2=C1 QRUDEWIWKLJBPS-UHFFFAOYSA-N 0.000 claims description 8
- 239000012964 benzotriazole Substances 0.000 claims description 8
- 238000011049 filling Methods 0.000 claims description 8
- 239000003208 petroleum Substances 0.000 claims description 8
- BDHFUVZGWQCTTF-UHFFFAOYSA-M sulfonate Chemical compound [O-]S(=O)=O BDHFUVZGWQCTTF-UHFFFAOYSA-M 0.000 claims description 8
- 239000004094 surface-active agent Substances 0.000 claims description 8
- 239000003112 inhibitor Substances 0.000 claims description 5
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 claims description 5
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 229910052757 nitrogen Inorganic materials 0.000 claims description 5
- WRIDQFICGBMAFQ-UHFFFAOYSA-N (E)-8-Octadecenoic acid Natural products CCCCCCCCCC=CCCCCCCC(O)=O WRIDQFICGBMAFQ-UHFFFAOYSA-N 0.000 claims description 3
- LQJBNNIYVWPHFW-UHFFFAOYSA-N 20:1omega9c fatty acid Natural products CCCCCCCCCCC=CCCCCCCCC(O)=O LQJBNNIYVWPHFW-UHFFFAOYSA-N 0.000 claims description 3
- QSBYPNXLFMSGKH-UHFFFAOYSA-N 9-Heptadecensaeure Natural products CCCCCCCC=CCCCCCCCC(O)=O QSBYPNXLFMSGKH-UHFFFAOYSA-N 0.000 claims description 3
- ZQPPMHVWECSIRJ-UHFFFAOYSA-N Oleic acid Natural products CCCCCCCCC=CCCCCCCCC(O)=O ZQPPMHVWECSIRJ-UHFFFAOYSA-N 0.000 claims description 3
- 239000005642 Oleic acid Substances 0.000 claims description 3
- CEGOLXSVJUTHNZ-UHFFFAOYSA-K aluminium tristearate Chemical compound [Al+3].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O CEGOLXSVJUTHNZ-UHFFFAOYSA-K 0.000 claims description 3
- QXJSBBXBKPUZAA-UHFFFAOYSA-N isooleic acid Natural products CCCCCCCC=CCCCCCCCCC(O)=O QXJSBBXBKPUZAA-UHFFFAOYSA-N 0.000 claims description 3
- 239000002480 mineral oil Substances 0.000 claims description 3
- 235000010446 mineral oil Nutrition 0.000 claims description 3
- ZQPPMHVWECSIRJ-KTKRTIGZSA-N oleic acid Chemical compound CCCCCCCC\C=C/CCCCCCCC(O)=O ZQPPMHVWECSIRJ-KTKRTIGZSA-N 0.000 claims description 3
- WSFQLUVWDKCYSW-UHFFFAOYSA-M sodium;2-hydroxy-3-morpholin-4-ylpropane-1-sulfonate Chemical compound [Na+].[O-]S(=O)(=O)CC(O)CN1CCOCC1 WSFQLUVWDKCYSW-UHFFFAOYSA-M 0.000 claims description 3
- 235000015112 vegetable and seed oil Nutrition 0.000 claims description 3
- 239000008158 vegetable oil Substances 0.000 claims description 3
- 238000004806 packaging method and process Methods 0.000 abstract description 11
- 230000009286 beneficial effect Effects 0.000 abstract description 10
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 8
- 239000011449 brick Substances 0.000 abstract description 8
- 238000007664 blowing Methods 0.000 abstract description 5
- 229910052799 carbon Inorganic materials 0.000 abstract description 5
- 239000013556 antirust agent Substances 0.000 abstract description 4
- 230000005540 biological transmission Effects 0.000 abstract description 4
- 230000000694 effects Effects 0.000 abstract description 4
- 230000003647 oxidation Effects 0.000 abstract 1
- 238000007254 oxidation reaction Methods 0.000 abstract 1
- QJVKUMXDEUEQLH-UHFFFAOYSA-N [B].[Fe].[Nd] Chemical compound [B].[Fe].[Nd] QJVKUMXDEUEQLH-UHFFFAOYSA-N 0.000 description 24
- VBICKXHEKHSIBG-UHFFFAOYSA-N 1-monostearoylglycerol Chemical compound CCCCCCCCCCCCCCCCCC(=O)OCC(O)CO VBICKXHEKHSIBG-UHFFFAOYSA-N 0.000 description 10
- 229940075507 glyceryl monostearate Drugs 0.000 description 5
- 239000001788 mono and diglycerides of fatty acids Substances 0.000 description 5
- 239000002985 plastic film Substances 0.000 description 5
- 238000003825 pressing Methods 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000012856 packing Methods 0.000 description 4
- 230000007547 defect Effects 0.000 description 3
- 239000010439 graphite Substances 0.000 description 3
- 229910002804 graphite Inorganic materials 0.000 description 3
- 229920006255 plastic film Polymers 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 238000010998 test method Methods 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 2
- 229940063655 aluminum stearate Drugs 0.000 description 2
- 238000003763 carbonization Methods 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 238000011068 loading method Methods 0.000 description 2
- 239000010721 machine oil Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 238000009461 vacuum packaging Methods 0.000 description 2
- 241000167854 Bourreria succulenta Species 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 235000019693 cherries Nutrition 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 230000003670 easy-to-clean Effects 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
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- 238000000465 moulding Methods 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000012797 qualification Methods 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 150000002910 rare earth metals Chemical class 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M173/00—Lubricating compositions containing more than 10% water
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
- C10M2207/28—Esters
- C10M2207/287—Partial esters
- C10M2207/289—Partial esters containing free hydroxy groups
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M2215/00—Organic non-macromolecular compounds containing nitrogen as ingredients in lubricant compositions
- C10M2215/22—Heterocyclic nitrogen compounds
- C10M2215/223—Five-membered rings containing nitrogen and carbon only
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M2219/00—Organic non-macromolecular compounds containing sulfur, selenium or tellurium as ingredients in lubricant compositions
- C10M2219/04—Organic non-macromolecular compounds containing sulfur, selenium or tellurium as ingredients in lubricant compositions containing sulfur-to-oxygen bonds, i.e. sulfones, sulfoxides
- C10M2219/044—Sulfonic acids, Derivatives thereof, e.g. neutral salts
Abstract
The invention provides a preparation method of an isostatic pressing liquid medium and a neodymium iron boron magnet. The isostatic pressing liquid medium is a mixed liquid of water-based emulsion and water, wherein the weight percentage of the water-based emulsion is 10-30%. Compared with an oily medium, the isostatic pressing hydraulic medium can greatly reduce the viscosity of the isostatic pressing hydraulic medium, after air blowing treatment, the packaging surface of a green body basically has no residual liquid, and the risk that the green body is polluted by oil stain to cause that the magnetic property and the mechanical strength of the green body are poor due to overhigh carbon content is greatly reduced. Compared with water, the isostatic pressing medium can also greatly improve the pressure transmission uniformity in the isostatic pressing process, which is beneficial to improving the density of green bodies obtained after isostatic pressing treatment, thereby being beneficial to improving the performances of magnetic density and the like of the magnet. In addition, contain waterborne antirust agent among the hydraulic medium that this application provided, can effectively avoid unburned bricks contact oxidation behind the air to play the effect that the protection unburned bricks were not oxidized.
Description
Technical Field
The invention relates to the field of preparation of neodymium iron boron magnets, in particular to an isostatic pressing liquid medium and a preparation method of a neodymium iron boron magnet.
Background
The traditional sintered Nd-Fe-B molding is completed in a non-magnetic steel mold in a short-time high magnetic field press, and the pressed initial blank has the problems of low density, large surface area and the like due to the structures of the non-magnetic steel mold and the press, the characteristics of Nd-Fe-B powder and the like, so that the blank needs to be further pressed by isostatic pressing after being packaged.
The isostatic pressure working principle is Pascal's law: the pressure of the medium (liquid or gas) in the closed container can be transmitted equally in all directions. After the product to be pressed is loaded into the equipment, the product is acted by the ultrahigh pressure medium with equal direction, so that the density of the product is increased, and the shrinkage of the pressing block depends on the compressibility of the material and the pressure during pressing. The prior art has the following problems: the isostatic pressing oil has high viscosity, is not easy to clean after isostatic pressing, and is easy to bring the oil into a sintered graphite box and be stained on the surface of a product when a packaging bag is subsequently removed, loaded into a furnace and sintered, so that the problems that the magnetic property of the sintered product is reduced, the mechanical strength of the product is poor and the like are caused by carbonization.
On the basis, the neodymium iron boron forming method capable of solving the problem of pollution to the neodymium iron boron magnet green bodies in the isostatic pressing process is needed.
Disclosure of Invention
The invention mainly aims to provide an isostatic pressing liquid medium and a preparation method of a neodymium iron boron magnet, so as to solve the problem that the prior neodymium iron boron magnet green body is polluted by the isostatic pressing step in the neodymium iron boron preparation process, and further the comprehensive performance of the neodymium iron boron magnet is influenced.
In order to achieve the above object, the present invention provides an isostatic pressing liquid medium, wherein the isostatic pressing liquid medium is a mixed liquid of a water-based emulsion and water, and the weight percentage of the water-based emulsion is 10-30%.
Further, the water-based emulsion comprises base oil, an aqueous rust inhibitor and a surfactant, wherein the base oil is selected from one or more of the group consisting of mineral oil, vegetable oil and synthetic oil, and the aqueous rust inhibitor is selected from one or more of the group consisting of benzotriazole, barium petroleum sulfonate, aluminum stearate, oleic acid and zinc naphthenate.
Further, the water-based emulsion comprises 5-20% of a water-based antirust agent, 1-10% of a surfactant and the balance of base oil in percentage by weight of the water-based emulsion.
Another aspect of the present application also provides a method for manufacturing a neodymium iron boron magnet, which includes: and placing the sealed packaged neodymium iron boron magnet green bodies in an isostatic pressing device for isostatic pressing treatment, wherein the isostatic pressing medium adopted in the isostatic pressing treatment process is the isostatic pressing liquid medium provided by the application.
Further, the isostatic pressing treatment process comprises three steps of pressure boosting, pressure maintaining and pressure releasing, wherein the pressure in the pressure maintaining step is 160-230 MPa, and the pressure maintaining time is 10-50 s.
Further, the preparation method of the neodymium iron boron magnet further comprises the following steps: placing the neodymium iron boron magnet green bodies subjected to isostatic pressing treatment in a glove box, and filling nitrogen into the glove box to discharge oxygen; and when the oxygen content in the glove box reaches a preset value, removing the sealed package, and then sequentially sintering and tempering to obtain the neodymium-iron-boron magnet.
Further, the predetermined value is an oxygen content of less than 1000 ppm.
Further, the temperature in the sintering process is 1050-1100 ℃, and the sintering time is 3-8 h.
Further, the tempering treatment comprises primary tempering treatment and secondary tempering treatment, wherein the temperature of the primary tempering treatment is 850-950 ℃, the primary tempering time is 1-4 h, the temperature of the secondary tempering treatment is 480-520 ℃, and the time of the secondary tempering treatment is 3-6 h.
By applying the technical scheme of the invention, compared with an oily medium, the isostatic pressing hydraulic medium provided by the invention can greatly reduce the viscosity of the isostatic pressing liquid medium, and after air blowing treatment, the surface of a green blank package basically has no residual liquid, so that oil stains can not be brought in the process of removing the package, and the risk of poor magnetic performance and mechanical strength of the blank due to overhigh carbon content caused by the fact that the green blank is stained with the oil stains is greatly reduced. Compared with the method that water is used as an isostatic pressing medium, the isostatic pressing medium can greatly improve the pressure transmission uniformity in the isostatic pressing process, so that the density of the green body obtained after the isostatic pressing treatment is favorably improved, and the performances of the magnetic density and the like of the magnet are favorably improved. In addition, in the actual operation process, the package of the green body inevitably has some gas leakage defects, and individual green body is caused to contact with air and hydraulic medium. In conclusion, the isostatic pressing treatment process by using the isostatic pressing medium is beneficial to greatly improving the magnet performance and mechanical strength of the neodymium-iron-boron magnet, and meanwhile, the neodymium-iron-boron magnet can have higher magnet density.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail with reference to examples.
As described in the background art, the prior art has the problem that the neodymium iron boron magnet green body is polluted by the isostatic pressing step in the neodymium iron boron preparation process, and the comprehensive performance of the neodymium iron boron magnet is affected. In order to solve the technical problem, the application provides an isostatic pressing liquid medium, wherein the isostatic pressing liquid medium is a mixed solution of water-based emulsion and water, and the weight percentage of the water-based emulsion is 10-30%.
Compare in oily medium, the isostatic pressing hydraulic medium that this application provided can greatly reduced isostatic pressing liquid medium's viscosity, through blowing the processing back, the packing surface of unburned bricks does not basically have residual liquid, therefore demolish the in-process of packing and can not bring the greasy dirt into yet, greatly reduced because of the unburned bricks be infected with the risk that the greasy dirt leads to the blank to lead to magnetic properties and mechanical strength variation because of the carbon content is too high. Compared with the method that water is used as an isostatic pressing medium, the isostatic pressing medium can greatly improve the pressure transmission uniformity in the isostatic pressing process, so that the density of the green body obtained after the isostatic pressing treatment is favorably improved, and the performances of the magnetic density and the like of the magnet are favorably improved. In addition, in the actual operation process, the package of the green body inevitably has some gas leakage defects, and individual green body is caused to contact with air and hydraulic medium. In conclusion, the isostatic pressing treatment process by using the isostatic pressing medium is beneficial to greatly improving the magnet performance and mechanical strength of the neodymium-iron-boron magnet, and meanwhile, the neodymium-iron-boron magnet can have higher magnet density.
In a preferred embodiment, the water-based emulsion comprises a base oil including, but not limited to, one or more of the group consisting of mineral oil, vegetable oil, and synthetic oil, an aqueous rust inhibitor including, but not limited to, one or more of the group consisting of benzotriazole, barium petroleum sulfonate, aluminum stearate, oleic acid, and zinc naphthenate, and a surfactant.
By adding the aqueous antirust agent into the hydraulic medium, the isostatic pressing equipment can be protected from being corroded, and the service life of the isostatic pressing treatment device is prolonged. The addition of the surfactant is beneficial to improving the phase solubility of each component in the isostatic pressing medium, thereby being beneficial to improving the isostatic pressing effect and the magnetic property of the subsequently prepared neodymium iron boron magnet.
The surfactant used in the present application may be selected from those commonly used in the art.
More preferably, the water-based emulsion comprises 5-20% of water-based antirust agent, 1-10% of surfactant and the balance of base oil in percentage by weight of the water-based emulsion.
In order to further optimize the viscosity of the isostatic pressing liquid medium and improve the isostatic pressing treatment effect, more preferably, the isostatic pressing liquid medium comprises 10-20 wt% of water-based emulsion and 80-90 wt% of water by percentage of the isostatic pressing liquid medium, wherein the water-based emulsion comprises 8-12 wt% of barium petroleum sulfonate, 2-5 wt% of benzotriazole and 2-5 wt% of glyceryl monostearate as base oil.
Another aspect of the present application further provides a method for preparing an ndfeb magnet, including: and placing the sealed and packaged neodymium iron boron magnet green body in an isostatic pressing device for isostatic pressing treatment, wherein the isostatic pressing medium adopted in the isostatic pressing treatment process is the isostatic pressing liquid medium provided by the application.
Compare in oily medium, the isostatic pressing hydraulic medium that this application provided can greatly reduced isostatic pressing liquid medium's viscosity, through blowing the processing back, the packing surface of unburned bricks does not basically have residual liquid, therefore demolish the in-process of packing and can not bring the greasy dirt into yet, greatly reduced because of the unburned bricks be infected with the risk that the greasy dirt leads to the blank to lead to magnetic properties and mechanical strength variation because of the carbon content is too high. Compared with the method that water is used as an isostatic pressing medium, the isostatic pressing medium can greatly improve the pressure transmission uniformity in the isostatic pressing process, so that the density of the green body obtained after the isostatic pressing treatment is favorably improved, and the performances of the magnetic density and the like of the magnet are favorably improved. In addition, in the actual operation process, the package of the green body inevitably has some gas leakage defects, and individual green body is caused to contact with air and hydraulic medium. In conclusion, the isostatic pressing treatment process by using the isostatic pressing medium is beneficial to greatly improving the magnet performance and mechanical strength of the neodymium-iron-boron magnet, and meanwhile, the neodymium-iron-boron magnet can have higher magnet density.
The above-mentioned isostatic pressing process may employ a process commonly used in the art. In a preferable embodiment, the isostatic pressing treatment process comprises three steps of pressure increasing, pressure maintaining and pressure releasing, wherein the pressure of the pressure maintaining step is 160-230 MPa, and the pressure maintaining time is 10-50 s. The special water-based emulsion is adopted as the isostatic pressing medium, so that the performance of the isostatic pressing medium is comprehensively considered, and the pressure maintaining time in the pressure maintaining step are limited in the range, so that the density of the magnet of the neodymium iron boron blank is further improved, and the magnetic performance of the neodymium iron boron blank is further improved.
In a preferred embodiment, the method for preparing the ndfeb magnet further comprises: placing the neodymium iron boron magnet green bodies subjected to isostatic pressing treatment in a glove box, and filling nitrogen into the glove box to discharge oxygen; and when the oxygen content in the glove box reaches a preset value, removing the sealed package of the neodymium iron boron magnet green body, and then sequentially sintering and tempering to obtain the neodymium iron boron magnet.
After carrying out the isostatic pressing processing step and before getting rid of the sealed package of neodymium iron boron magnetism body unburned bricks, fill nitrogen gas earlier to discharge oxygen, this is favorable to reducing the risk that the neodymium iron boron unburned bricks was oxidized. Preferably, the predetermined value is an oxygen content of less than 1000 ppm.
The sintering process can adopt the common technique in the field, and the suitable sintering temperature and sintering time can be selected according to the actual requirement. In a preferred embodiment, the temperature of the sintering process is 1050-1100 ℃, and the sintering time is 3-8 h. The sintering temperature and the sintering time include, but are not limited to, the above ranges, and the limitation of the sintering temperature and the sintering time within the above ranges is beneficial to further densifying the neodymium iron boron magnet blank, so as to further improve the magnetic properties such as the magnetic energy density and the coercive force of the subsequently prepared sintered neodymium iron boron blank.
In a preferred embodiment, the tempering treatment comprises primary tempering treatment and secondary tempering treatment, wherein the temperature of the primary tempering treatment is 850-950 ℃, the time of the primary tempering treatment is 1-4 h, the temperature of the secondary tempering treatment is 480-520 ℃, and the time of the secondary tempering treatment is 3-6 h. The neodymium iron boron green body is tempered twice within the temperature range, so that the reduction rate of the internal stress in the sintered neodymium iron boron green body can be reduced, the brittleness of the sintered neodymium iron boron green body is reduced, and the hardness is improved, thereby being beneficial to further improving the comprehensive performance of the sintered neodymium iron boron green body.
The present application is described in further detail below with reference to specific examples, which should not be construed as limiting the scope of the invention as claimed.
Example 1
A method for pressing and forming sintered neodymium iron boron comprises the following steps:
(1) removing surface powder residue from the press-molded neodymium iron boron green body with the size of 76 × 40 × 38mm in a press glove box, wrapping a layer of plastic film (with the thickness of 12 μm), packaging in a packaging bag, and sealing by a vacuum packaging machine.
(2) And (4) putting the packaged neodymium iron boron green bodies into an isostatic pressing machine for isostatic pressing, and filling the isostatic pressing machine with isostatic pressing liquid. The isostatic pressing liquid is prepared from 12 wt% of emulsion and 88 wt% of water, wherein the emulsion comprises, by weight percentage, 10 wt% of barium petroleum sulfonate (TST-701), 3 wt% of benzotriazole (Cherokee Rose Sagittata), 3 wt% of glyceryl monostearate (surfactant-Jialish), and the balance of industrial machine oil (No. 10 machine oil). And (3) keeping the pressure at 200MPa for 25 seconds in the isostatic pressing process, and putting the green body subjected to isostatic pressing into blowing equipment to blow off liquid on the surface of the package.
(3) Putting the neodymium iron boron green body into a glove box matched with a sintering furnace, filling nitrogen and discharging oxygen for 15 minutes until the oxygen content is less than 1000ppm, dismantling a packaging bag in the glove box, removing a plastic sheet film, putting the packaging bag into a graphite box, transferring the packaging bag into a VS-300RPA vacuum sintering furnace, and respectively carrying out sintering treatment at 1070 ℃ for 6h, primary tempering treatment at 900 ℃ for 3h and secondary tempering treatment at 510 ℃ for 5h under the environment of 5 multiplied by 10-2Pa to obtain a sintered neodymium iron boron blank.
Example 2
The differences from example 1 are:
the water-based emulsion comprises 15 wt% of barium petroleum sulfonate (TST-701), 5 wt% of benzotriazole (German cherry), 10 wt% of glyceryl monostearate (surfactant-Jialish) and the balance of the base oil.
Example 3
The differences from example 1 are:
the water-based emulsion comprises 4 wt% of barium petroleum sulfonate (TST-701), 1 wt% of benzotriazole (Cherokee Sakura Germany), 1 wt% of glyceryl monostearate (surfactant-Jialish) and the balance of the base oil.
Example 4
The differences from example 1 are: the organic components in the water-based emulsion comprise 20 wt% of barium petroleum sulfonate (TST-701), 10 wt% of benzotriazole (Cherokee Rose Sagittifolia Vahl), 15 wt% of glyceryl monostearate (surfactant-Jialish), and the balance of the base oil.
Example 5
The differences from example 1 are: the isostatic medium comprises 18 wt% of emulsion and 82 wt% of water.
Example 6
The differences from example 1 are: the isostatic medium comprises 30 wt% emulsion and 70 wt% water.
Comparative example 1
A method for pressing and forming sintered neodymium iron boron comprises the following steps:
(1) removing residual powder on the surface of the press-formed neodymium iron boron green body with the size of 76 multiplied by 40 multiplied by 38mm in a press glove box, wrapping a layer of plastic film, filling the plastic film into a packaging bag, and vacuumizing, packaging and sealing the packaging bag by using a vacuum packaging machine.
(2) And (4) putting the packaged neodymium iron boron green bodies into an isostatic pressing machine for isostatic pressing, and filling the isostatic pressing machine with No. 10 isostatic pressing oil. The pressure was maintained at 200MPa for 25 seconds, and the green body after isostatic pressing was wiped with a cloth to remove the remaining oil.
(3) Loading the neodymium iron boron green body into a glove box matched with a sintering furnace, filling nitrogen and discharging oxygen for 15 minutes until the oxygen content is less than 1000ppm, dismantling the packaging bag in the glove box, removing the plastic sheet film, loading into a graphite box, transferring into a VS-300RPA vacuum sintering furnace, and performing vacuum degree of 5 multiplied by 10-2Sintering treatment at 1070 ℃ for 6h, primary tempering treatment at 900 ℃ for 3h and secondary tempering treatment at 510 ℃ for 5h in a Pa environment to obtain the sintered neodymium iron boron blank.
Comparative example 2
The differences from example 1 are: the isostatic medium comprises 5 wt% of the emulsion and 95 wt% of water.
Comparative example 3
The differences from example 1 are: the isostatic medium comprises 45 wt% of the emulsion and 55 wt% of water.
Magnetic performance test and carbon content test were performed on the blanks prepared in examples 1 to 6 and comparative examples 1 to 3 using a permanent magnet material measurement B-H instrument, the test methods are described in GB/T3217 permanent magnet (hard magnet) material magnetic test method, GB/T31967.2 rare earth permanent magnet material physical property test method part 2: flexural strength and fracture toughness were measured and the results are shown in Table 1.
TABLE 1
As can be seen from table 1: the method for pressing and forming the sintered neodymium iron boron can reduce blank carbonization, improve blank performance, improve magnet bending strength, improve blank qualification rate and reduce production cost.
From the above description, it can be seen that the above-described embodiments of the present invention achieve the following technical effects: the isostatic pressing treatment process by adopting the isostatic pressing medium is not only beneficial to greatly improving the magnet performance and mechanical strength of the neodymium iron boron magnet, but also capable of enabling the neodymium iron boron magnet to have higher magnet density.
It should be noted that the terms "first," "second," and the like in the description and in the claims of the present application are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of operation in sequences other than those described or illustrated herein.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. The isostatic pressing liquid medium is characterized by being a mixed liquid of water-based emulsion and water, wherein the water-based emulsion accounts for 10-30% of the weight of the isostatic pressing liquid medium.
2. The isostatic press liquid medium according to claim 1, wherein said water based emulsion comprises a base oil selected from one or more of the group consisting of mineral oil, vegetable oil and synthetic oil, an aqueous rust inhibitor selected from one or more of the group consisting of benzotriazole, barium petroleum sulfonate, aluminium stearate, oleic acid and zinc naphthenate, and a surfactant.
3. The isostatic pressing liquid medium as claimed in claim 2, wherein said water-based emulsion comprises 5-20% of said aqueous rust inhibitor, 1-10% of said surfactant, and the balance of said base oil, in terms of weight percentage of said water-based emulsion.
4. The preparation method of the neodymium iron boron magnet is characterized by comprising the following steps: placing the sealed and packaged neodymium iron boron magnet green body in an isostatic pressing device for isostatic pressing treatment, wherein the isostatic pressing medium adopted in the isostatic pressing treatment process is the isostatic pressing liquid medium in any one of claims 1 to 3.
5. The method of manufacturing a neodymium-iron-boron magnet according to claim 4, wherein the isostatic pressing process comprises three steps of pressure increase, pressure maintaining and pressure relief, wherein the pressure of the pressure maintaining step is 160-230 MPa, and the pressure maintaining time is 10-50 s.
6. The method of manufacturing a neodymium iron boron magnet according to claim 4 or 5, characterized in that the method further comprises:
placing the neodymium iron boron magnet green bodies subjected to the isostatic pressing treatment in a glove box, and filling nitrogen into the glove box to discharge oxygen;
and when the oxygen content in the glove box reaches a preset value, removing the sealed package, and then sequentially performing sintering and tempering treatment to obtain the neodymium-iron-boron magnet.
7. The method of manufacturing a neodymium-iron-boron magnet according to claim 6, wherein the predetermined value is an oxygen content of less than 1000 ppm.
8. The method for preparing the neodymium-iron-boron magnet according to claim 6 or 7, wherein the temperature in the sintering process is 1050-1100 ℃, and the sintering time is 3-8 h.
9. The method for preparing a neodymium-iron-boron magnet according to claim 8, characterized in that the tempering treatment comprises primary tempering treatment and secondary tempering treatment, wherein the temperature of the primary tempering treatment is 850-950 ℃, the primary tempering time is 1-4 h, the temperature of the secondary tempering treatment is 480-520 ℃, and the time of the secondary tempering treatment is 3-6 h.
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