EP3357074A1 - Verfahren zum herstellen eines permanentmagneten - Google Patents
Verfahren zum herstellen eines permanentmagnetenInfo
- Publication number
- EP3357074A1 EP3357074A1 EP16781067.0A EP16781067A EP3357074A1 EP 3357074 A1 EP3357074 A1 EP 3357074A1 EP 16781067 A EP16781067 A EP 16781067A EP 3357074 A1 EP3357074 A1 EP 3357074A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- minutes
- mbar
- bar
- rare earth
- earth element
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 17
- 239000011230 binding agent Substances 0.000 claims abstract description 77
- 229910052761 rare earth metal Inorganic materials 0.000 claims abstract description 56
- 150000001875 compounds Chemical class 0.000 claims abstract description 42
- 239000007858 starting material Substances 0.000 claims abstract description 42
- 238000001746 injection moulding Methods 0.000 claims abstract description 22
- 229910052751 metal Inorganic materials 0.000 claims abstract description 17
- 239000002184 metal Substances 0.000 claims abstract description 17
- 238000000034 method Methods 0.000 claims description 72
- 238000006243 chemical reaction Methods 0.000 claims description 57
- 239000000463 material Substances 0.000 claims description 37
- 239000001257 hydrogen Substances 0.000 claims description 34
- 229910052739 hydrogen Inorganic materials 0.000 claims description 34
- 238000005245 sintering Methods 0.000 claims description 31
- 239000000843 powder Substances 0.000 claims description 28
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 23
- 239000012298 atmosphere Substances 0.000 claims description 23
- 229910052799 carbon Inorganic materials 0.000 claims description 21
- 239000011261 inert gas Substances 0.000 claims description 17
- 238000010438 heat treatment Methods 0.000 claims description 16
- 229910001172 neodymium magnet Inorganic materials 0.000 claims description 16
- 239000007789 gas Substances 0.000 claims description 14
- 230000001681 protective effect Effects 0.000 claims description 10
- 150000002431 hydrogen Chemical class 0.000 claims description 9
- 238000001816 cooling Methods 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 7
- 150000002910 rare earth metals Chemical class 0.000 abstract description 2
- 230000008569 process Effects 0.000 description 31
- 229910052779 Neodymium Inorganic materials 0.000 description 25
- -1 hydrogen compound Chemical class 0.000 description 25
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 description 23
- 239000000126 substance Substances 0.000 description 19
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 18
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 17
- 230000015572 biosynthetic process Effects 0.000 description 17
- 229910052760 oxygen Inorganic materials 0.000 description 17
- 239000001301 oxygen Substances 0.000 description 17
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 8
- 150000001247 metal acetylides Chemical class 0.000 description 8
- 229910052692 Dysprosium Inorganic materials 0.000 description 7
- 229910052771 Terbium Inorganic materials 0.000 description 7
- 238000007872 degassing Methods 0.000 description 7
- KBQHZAAAGSGFKK-UHFFFAOYSA-N dysprosium atom Chemical compound [Dy] KBQHZAAAGSGFKK-UHFFFAOYSA-N 0.000 description 7
- GZCRRIHWUXGPOV-UHFFFAOYSA-N terbium atom Chemical compound [Tb] GZCRRIHWUXGPOV-UHFFFAOYSA-N 0.000 description 7
- 238000005984 hydrogenation reaction Methods 0.000 description 6
- 238000002360 preparation method Methods 0.000 description 6
- 229910045601 alloy Inorganic materials 0.000 description 5
- 239000000956 alloy Substances 0.000 description 5
- 238000006356 dehydrogenation reaction Methods 0.000 description 5
- 239000000696 magnetic material Substances 0.000 description 5
- 230000009257 reactivity Effects 0.000 description 5
- 239000002904 solvent Substances 0.000 description 5
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 4
- IMNFDUFMRHMDMM-UHFFFAOYSA-N N-Heptane Chemical compound CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 description 4
- 229910052786 argon Inorganic materials 0.000 description 4
- 229910052729 chemical element Inorganic materials 0.000 description 4
- 230000006866 deterioration Effects 0.000 description 4
- PLDDOISOJJCEMH-UHFFFAOYSA-N neodymium oxide Inorganic materials [O-2].[O-2].[O-2].[Nd+3].[Nd+3] PLDDOISOJJCEMH-UHFFFAOYSA-N 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 230000035484 reaction time Effects 0.000 description 4
- 238000005979 thermal decomposition reaction Methods 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 3
- 229910052772 Samarium Inorganic materials 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 230000003197 catalytic effect Effects 0.000 description 3
- 238000000354 decomposition reaction Methods 0.000 description 3
- 229910003460 diamond Inorganic materials 0.000 description 3
- 239000010432 diamond Substances 0.000 description 3
- 238000002347 injection Methods 0.000 description 3
- 239000007924 injection Substances 0.000 description 3
- 238000003754 machining Methods 0.000 description 3
- 230000005415 magnetization Effects 0.000 description 3
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 3
- 229910052756 noble gas Inorganic materials 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 238000004886 process control Methods 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- KZUNJOHGWZRPMI-UHFFFAOYSA-N samarium atom Chemical compound [Sm] KZUNJOHGWZRPMI-UHFFFAOYSA-N 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 229910052684 Cerium Inorganic materials 0.000 description 2
- 229910052691 Erbium Inorganic materials 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 229910052693 Europium Inorganic materials 0.000 description 2
- 229910052688 Gadolinium Inorganic materials 0.000 description 2
- 229910052689 Holmium Inorganic materials 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 229910052765 Lutetium Inorganic materials 0.000 description 2
- 229930040373 Paraformaldehyde Natural products 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 2
- 239000002202 Polyethylene glycol Substances 0.000 description 2
- 239000004743 Polypropylene Substances 0.000 description 2
- 239000004793 Polystyrene Substances 0.000 description 2
- 229910052777 Praseodymium Inorganic materials 0.000 description 2
- 229910052773 Promethium Inorganic materials 0.000 description 2
- 244000269722 Thea sinensis Species 0.000 description 2
- 229910052775 Thulium Inorganic materials 0.000 description 2
- 229910052769 Ytterbium Inorganic materials 0.000 description 2
- 238000005275 alloying Methods 0.000 description 2
- ZMIGMASIKSOYAM-UHFFFAOYSA-N cerium Chemical compound [Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce] ZMIGMASIKSOYAM-UHFFFAOYSA-N 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- UYAHIZSMUZPPFV-UHFFFAOYSA-N erbium Chemical compound [Er] UYAHIZSMUZPPFV-UHFFFAOYSA-N 0.000 description 2
- OGPBJKLSAFTDLK-UHFFFAOYSA-N europium atom Chemical compound [Eu] OGPBJKLSAFTDLK-UHFFFAOYSA-N 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- UIWYJDYFSGRHKR-UHFFFAOYSA-N gadolinium atom Chemical compound [Gd] UIWYJDYFSGRHKR-UHFFFAOYSA-N 0.000 description 2
- 238000005324 grain boundary diffusion Methods 0.000 description 2
- KJZYNXUDTRRSPN-UHFFFAOYSA-N holmium atom Chemical compound [Ho] KJZYNXUDTRRSPN-UHFFFAOYSA-N 0.000 description 2
- 150000004678 hydrides Chemical class 0.000 description 2
- 229910052746 lanthanum Inorganic materials 0.000 description 2
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 2
- OHSVLFRHMCKCQY-UHFFFAOYSA-N lutetium atom Chemical compound [Lu] OHSVLFRHMCKCQY-UHFFFAOYSA-N 0.000 description 2
- 239000006249 magnetic particle Substances 0.000 description 2
- 239000006247 magnetic powder Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 229920003023 plastic Polymers 0.000 description 2
- 239000004033 plastic Substances 0.000 description 2
- 229920003229 poly(methyl methacrylate) Polymers 0.000 description 2
- 229920000573 polyethylene Polymers 0.000 description 2
- 229920001223 polyethylene glycol Polymers 0.000 description 2
- 239000004926 polymethyl methacrylate Substances 0.000 description 2
- 229920006324 polyoxymethylene Polymers 0.000 description 2
- 229920001155 polypropylene Polymers 0.000 description 2
- 229920002223 polystyrene Polymers 0.000 description 2
- 238000012805 post-processing Methods 0.000 description 2
- PUDIUYLPXJFUGB-UHFFFAOYSA-N praseodymium atom Chemical compound [Pr] PUDIUYLPXJFUGB-UHFFFAOYSA-N 0.000 description 2
- VQMWBBYLQSCNPO-UHFFFAOYSA-N promethium atom Chemical compound [Pm] VQMWBBYLQSCNPO-UHFFFAOYSA-N 0.000 description 2
- 229910052706 scandium Inorganic materials 0.000 description 2
- SIXSYDAISGFNSX-UHFFFAOYSA-N scandium atom Chemical compound [Sc] SIXSYDAISGFNSX-UHFFFAOYSA-N 0.000 description 2
- 238000011282 treatment Methods 0.000 description 2
- NAWDYIZEMPQZHO-UHFFFAOYSA-N ytterbium Chemical compound [Yb] NAWDYIZEMPQZHO-UHFFFAOYSA-N 0.000 description 2
- 229910052727 yttrium Inorganic materials 0.000 description 2
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical group [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- 241001522319 Chloris chloris Species 0.000 description 1
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 description 1
- 239000004952 Polyamide Substances 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- QJVKUMXDEUEQLH-UHFFFAOYSA-N [B].[Fe].[Nd] Chemical compound [B].[Fe].[Nd] QJVKUMXDEUEQLH-UHFFFAOYSA-N 0.000 description 1
- 229910052767 actinium Inorganic materials 0.000 description 1
- QQINRWTZWGJFDB-UHFFFAOYSA-N actinium atom Chemical compound [Ac] QQINRWTZWGJFDB-UHFFFAOYSA-N 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 239000012300 argon atmosphere Substances 0.000 description 1
- 229910052788 barium Inorganic materials 0.000 description 1
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 1
- 238000009739 binding Methods 0.000 description 1
- DQXBYHZEEUGOBF-UHFFFAOYSA-N but-3-enoic acid;ethene Chemical compound C=C.OC(=O)CC=C DQXBYHZEEUGOBF-UHFFFAOYSA-N 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 239000004203 carnauba wax Substances 0.000 description 1
- 235000013869 carnauba wax Nutrition 0.000 description 1
- 238000006757 chemical reactions by type Methods 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000005038 ethylene vinyl acetate Substances 0.000 description 1
- 235000009569 green tea Nutrition 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910052747 lanthanoid Inorganic materials 0.000 description 1
- 150000002602 lanthanoids Chemical class 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910001092 metal group alloy Inorganic materials 0.000 description 1
- 239000013528 metallic particle Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000012778 molding material Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 150000002927 oxygen compounds Chemical class 0.000 description 1
- 239000012188 paraffin wax Substances 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 229920001200 poly(ethylene-vinyl acetate) Polymers 0.000 description 1
- 229920002037 poly(vinyl butyral) polymer Polymers 0.000 description 1
- 229920002647 polyamide Polymers 0.000 description 1
- 229920000098 polyolefin Polymers 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 235000013616 tea Nutrition 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
- 239000004416 thermosoftening plastic Substances 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 229920003169 water-soluble polymer Polymers 0.000 description 1
- 239000001993 wax Substances 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Classifications
-
- 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
- H01F1/0573—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 obtained by reduction or by hydrogen decrepitation or embrittlement
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/10—Sintering only
- B22F3/1017—Multiple heating or additional steps
- B22F3/1021—Removal of binder or filler
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/22—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces for producing castings from a slip
- B22F3/225—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces for producing castings from a slip by injection molding
-
- 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
- H01F41/0273—Imparting anisotropy
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
- B22F2998/10—Processes characterised by the sequence of their steps
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
- B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
- B22F9/20—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C2202/00—Physical properties
- C22C2202/02—Magnetic
Definitions
- the invention relates to a method for producing a permanent magnet.
- Permanent magnets which are also referred to as permanent magnets, which have at least one element from the group of rare earths, are characterized by a very high energy product, in particular neodymium-iron-boron magnets (NdFeB magnets) with their energy product of about 385 kJ / m J or 48 MGOe enable new technical solutions for a variety of applications.
- NdFeB magnets neodymium-iron-boron magnets
- elaborate processing steps are necessary for the production of such magnets, which also entail higher costs.
- One established way of making such magnets involves melting an alloy of the magnetic material.
- blocks of material cast from the melt are crushed and ground to a fine powder, pressed in a magnetic field, and then sintered.
- blocks of material cast from the melt are crushed and ground to a fine powder, pressed in a magnetic field, and then sintered.
- In this way only simple geometric shapes can be produced.
- For the production of complex geometries however, often isostatically pressed and then sintered ingots are used in large dimensions.
- For these rough blocks form magnets are cut, which must be done for example with a diamond saw under water because of the poor machinability of the magnetic material.
- Disk-shaped and / or annular magnets are also produced with diamond tools. Due to the machining process, considerable production waste is generated, which in turn has a negative effect on the costs. The same applies to the costly procurement and use of diamond tools.
- MIM Metal Injection Molding
- a metal powder with a typically organic binder material is processed into an injection-moldable mass, the so-called feedstock, and on injection molding machines in a corresponding mold by injection molding in the form.
- a sintering step in which finished-contour or at least near-net-shape prefabricated components can be produced.
- Characteristic of the MIM process is the efficient use of raw materials, since virtually no production waste can be used.
- Machining post-processing steps can namely be at least largely avoided.
- the high raw material costs because of the high raw material costs, the low availability of the starting materials and the very problematic machinability, even complex shaped permanent magnets based on elements from the group of rare earths are suitable candidates to be produced by means of an MIM process.
- the alloying element neodymium (Nd) which is very advantageous for high-performance permanent magnets, have a very high reactivity with regard to oxygen (0 2 ) and carbon (C).
- a binder material which in particular organic compounds, in particular plastic compounds, which release in a thermal debinding, ie in a burn-out to remove the binder material, carbon and oxygen.
- a binder material which in particular organic compounds, in particular plastic compounds, which release in a thermal debinding, ie in a burn-out to remove the binder material, carbon and oxygen.
- the invention has for its object to provide a method for producing a permanent magnet, wherein said disadvantages do not occur.
- the object is achieved by providing a method with the steps of claim 1.
- the object is achieved in particular by providing a method for producing a permanent magnet, wherein the permanent magnet comprises a rare earth element, in particular neodymium, wherein a starting material is processed in a metal powder injection molding (MIM) method, wherein the starting material is a rare earth Element, and wherein the rare earth element present in the starting material is converted into an inerted compound prior to a debinding step of the metal powder injection molding process.
- MIM metal powder injection molding
- the rare earth element Due to the fact that the rare earth element is converted into an inertized compound before the debinding step, it is in the Debinding step not in its highly reactive form to oxygen and carbon before, but rather in a reaction-carrier form, so that the risk of formation of oxides or carbides of the rare earth element during the binder removal step significantly reduced, preferably completely avoided. In this way, a strong deterioration of the hard magnetic properties of the permanent magnet can be prevented by the binder removal step. This in turn allows due to the appropriate process control a production of oxide and carbide poor or oxide and carbide-free permanent magnet with high energy product by means of metal powder injection molding, so that this for the first time in mass production suitable manner for producing such permanent magnets, the rare earth elements can be applied.
- complex geometries for such magnets can also be produced quickly, simply and cost-effectively, in particular with a low cost of materials and preferably while avoiding production waste by machining post-processing steps.
- the method enables an efficient use of raw materials without the problem of a deterioration of the hard magnetic properties of the permanent magnets produced by the method.
- a metal powder injection molding method which is also referred to as MIM method for short, is understood to mean a method in which a raw material is injection-molded, thereby obtaining a molded article which is subsequently sintered.
- the starting material may be a metal powder, in particular a powder of a metal alloy, which is then processed in a separate step of the MIM process into an injection-moldable material by mixing with a binder material, this injection-moldable material being referred to as a feedstock, and wherein the step of mixing the metal powder with the preferably thermoplastic binder material is referred to as a feedstock preparation.
- feedstock preparation itself is not part of the process.
- the feedstock is injection molded in an injection molding machine, resulting in the molded part, which is also referred to as green compact, and which still has the metal powder and the binder material, thus the feedstock.
- the green compact is then subjected to at least one debinding step, whereby the binder material is removed.
- a catalytic debinding under catalytic chemical reaction of the binder material to gaseous products that can be expelled a chemical debindering Dissolution of the binder material in a typically liquid solvent, and / or thermal debinding with thermal reaction, in particular burnout, the binder material possible.
- a combination of these steps is possible.
- the so-called browning product is produced from the green compact, which only has the metal powder or-after a first debindering step-the metal powder and the secondary binder component.
- the Braunling is then sintered, possibly still existing backbone binder is thermally removed. From the sintering step finally results in the finished, produced by the MIM process component.
- the terms “green body” and “brown body” or “green tea” and “brown tea” are sometimes used.
- the rare earth element is converted to its inertized compound prior to a thermal debinding step so that the formation of oxides and / or carbides during the thermal debindering step is avoided or at least reduced.
- a rare earth element in particular a chemical element, also in the form of a compound and in particular an alloy with at least one other chemical element, which belongs to the metals of the rare earths. These are in particular the chemical elements of the third subgroup of the periodic table with the exception of the actinium, as well as the lanthanides.
- the rare earth element is preferably selected from a group consisting of scandium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, yttrium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium.
- the rare earth element is selected from the so-called light rare earth elements, namely a group consisting of scandium, lanthanum, cerium, praseodymium, Neodymium, Promethium, Samarium and Europium.
- the rare earth element is preferably selected from the group of so-called heavy rare earth elements, namely a group consisting of yttrium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.
- the rare earth element is selected from a group consisting of neodymium, dysprosium, terbium and samarium.
- the rare earth element is selected from a group consisting of neodymium, dysprosium and terbium.
- a starting material is used which has neodymium as the rare earth element.
- the starting material has more than one rare earth element.
- the starting material contains, in addition to neodymium, dysprosium and / or terbium as another rare earth element (s).
- s another rare earth element
- more than one rare earth element comprised by the starting material it is additionally or alternatively possible for more than one rare earth element comprised by the starting material to be converted into an inerted compound. It is also possible that all of the rare earth elements included in the starting material are each converted into an inerted compound.
- a "conversion" into an inerted compound means in particular a chemical reaction of the rare earth element, in particular a chemical reaction of the rare earth element with at least one further element or at least one compound understand the formation of a covalent bond but may involve the formation of at least one covalent bond.
- conversion Other types of binding and / or chemical reaction types are also encompassed by the term "conversion.”
- the formation of an ionic bond, a complex bond, and a metallic bond is included, and the conversion can therefore include, in particular, the formation of a metallic phase
- the inertized compound when the rare earth element is converted to an inertized compound, it means that the compound of the rare earth element created by the transformation is less reactive than the rare earth element in its pre-conversion form, and the inertized compound is particularly reactive towards the elements carbon and oxygen as the rare earth element in the form before the conversion.
- An embodiment of the method is preferred, which is characterized in that the inertized compound is reconverted into the rare earth element after the debinding step.
- the inertized compound is preferably reconverted to the rare earth element after its debinding step in its present form prior to conversion to the inerted compound.
- the rare earth element has not been present in elemental form prior to conversion into the inerted compound, but in another form, in particular in the form of an alloy or metallic phase, and then back into the inertised compound previously converted alloy or metallic phase or other form is reconverted.
- the binder removal step ie when there is no longer any danger of formation of carbides or oxides which are detrimental to the hard magnetic properties of the permanent magnet
- the properties of the rare earth element which are favorable for the permanent magnet are recovered in its form present before conversion into the inerted compound.
- this back conversion takes place before sintering, in particular between the thermal debinding step and the sintering step of the MIM process.
- An embodiment of the process is preferred, which is characterized in that the conversion of the rare earth element into the inerted compound is carried out on a binder-free rare earth element powder as starting material.
- the conversion is carried out in particular before the feedstock preparation.
- the conversion is particularly preferably carried out simultaneously and / or jointly with a step of hydrogen decrepitation, which is in particular intended to obtain a fine-grained powder for the MIM process.
- the conversion before the feedstock preparation has the advantage that shorter reaction times are possible due to the higher reactivity of the starting material without the binder material.
- the conversion of the rare earth element into the inerted compound is carried out on a mixture of the powder comprising the rare earth element and the binder material, that is to say in particular on the feedstock, as starting material.
- a mixture of the powder comprising the rare earth element and the binder material that is to say in particular on the feedstock, as starting material.
- An embodiment of the method is also preferred, which is characterized in that at least one first conversion step is carried out in an atmosphere which comprises hydrogen or consists of hydrogen.
- a hydrogenation of the rare earth element can be carried out, wherein this in its hydrogenated form, thus as a compound with hydrogen, at least up to 500 ° C is chemically stable than in its dehydrogenated form, in particular more stable to carbon and oxygen.
- the rare earth element is converted into a hydrogenated form, thus into a hydrogen compound.
- the term hydrogen compound is not limited to a covalent compound. Rather, it may also be in particular a hydrogen-containing, metallic phase.
- Neodymium is particularly preferably converted into a neodymium hydride, in particular NdH 3 , in the context of the process.
- the previously formed hydride of the rare earth element is reconverted as an inerted compound after the debinding step by dehydrogenation.
- neodymium hydride in particular NdH or NdH 2 .7, is reconverted to neodymium (Nd).
- the first conversion step is preferably carried out at a pressure of at most 2.5 bar, preferably at a pressure of at least 1.5 bar to at most 3.5 bar, preferably at a pressure of at least 1.5 bar to at most 3 bar, preferably at a pressure of at least 1.5 bar to at most 2.5 bar, preferably at least 1.5 bar to at most 2 bar, preferably at least 2 bar to at most 3 bar, preferably at least 2 bar to at most 2.5 bar, preferably from 2, 5 bar.
- the first conversion step is carried out at a temperature of at least 15 ° C to at most 200 ° C, preferably at least 15 ° C to at most 150 ° C, preferably from at least 100 ° C to at most 150 ° C, preferably from 125 ° C , preferably from at least 15 ° C to at most 35 ° C, preferably at least 15 ° C to at most 30 ° C, preferably at least 20 ° C to at most 30 ° C, preferably from 25 ° C. It is thus possible, in particular, to carry out the first conversion step at room temperature or at elevated temperature, in particular up to 150 ° C.
- the first conversion step is preferably carried out for a period of at least 5 minutes to at most two hours, preferably from at least 30 minutes to at most 90 minutes, preferably for a period of one hour.
- the specifically selected reaction time depends in particular on the amount of the rare earth element to be converted and thus in particular on the amount of the starting material to be treated.
- the hydrogen-containing atmosphere preferably has from at least 200 mbar to at most 1 bar of pure hydrogen.
- the atmosphere consists of hydrogen in one of the aforementioned pressure ranges.
- high purity gases having a low oxygen content are used for the process, in particular hydrogen, which contains oxygen at a concentration - by volume - of at most 2 ppm (parts per million), ie 2 ppmv (parts per million based on the Volume), preferably at most 1 ppmv, more preferably at most 0.5 ppmv.
- hydrogen having a purity of at least 99.999% by volume (hydrogen 5.0), hydrogen with a purity of 99.9999% by volume (hydrogen 6.0) being very particularly preferred.
- an optionally used protective gas in particular argon.
- An embodiment of the method is preferred in which at least a second conversion step is performed.
- the conversion of the rare earth element into the inerted compound is thus carried out in two steps.
- hydrogenation is particularly preferably carried out in the first conversion step, partial dehydrogenation being carried out in the second conversion step in order, in particular, to achieve an even more stable compound.
- neodymium hydride having the molecular formula NdH 3 formed in the first conversion step is the partially dehydrated neodymium hydride having the approximate molecular formula NdH 2 . 7 produced by partial degassing, this partial dehydrogenated neodymium hydride is stable to carbon and oxygen to about 500 ° C.
- the at least one second conversion step is preferably carried out under vacuum, under a hydrogen-containing or hydrogen-containing atmosphere, and / or under an at least one inert gas or consisting of at least one inert gas atmosphere.
- a protective gas is understood in particular to mean a gas which is inert or at least inert to the substances or substance mixtures used to produce the permanent magnet.
- the shielding gas is preferably selected from a group consisting of a noble gas, nitrogen, and carbon dioxide.
- the protective gas is selected from a group consisting of a noble gas and nitrogen.
- the protective gas is a noble gas. Particular preference is given to using argon as protective gas.
- the at least one second conversion step is preferably carried out at a pressure of at least 100 mbar to at most 1 bar, preferably from at least 100 mbar to at most 700 mbar, preferably from at least 200 mbar to at most 600 mbar.
- the second conversion step is carried out either under atmospheric pressure (1 bar) or else in a pressure range of at least 200 mbar to at most 600 mbar.
- the at least one second conversion step is preferably carried out at an increasing temperature, in particular thus by heating the compound resulting from the first conversion step.
- the temperature preferably rises from a starting temperature of 100 ° C to a target temperature of 350 ° C, preferably from a starting temperature of 150 ° C to a target temperature of 300 ° C.
- the at least one second conversion step is preferably carried out for a period of at least 20 minutes to at most 120 minutes, preferably from at least 30 minutes to at most 90 minutes, preferably from at least 40 minutes to at most 80 minutes, preferably from at least 50 minutes to at most 70 minutes, preferably 60 minutes.
- a temperature ramp is preferably driven, starting from one of the aforementioned start temperatures up to one of the aforementioned target temperatures.
- the second conversion step in particular a partial degassing and especially a partial dehydrogenation of in The compound produced in the first conversion step, wherein an even more stable, compared to oxygen and carbon even more inert the intertflowere compound is formed.
- An embodiment of the method is preferred, which is characterized in that a binder material is used, which has at least one secondary binder component which is completely decomposable below a temperature of 500 ° C or at most at 600 ° C. This allows thermal removal of the binder material at a temperature at which the inertized compound is inert and, in particular, stable to carbon and oxygen.
- the debindering can be carried out without the risk of deterioration of the hard magnetic properties of the permanent magnet to be formed by formation of carbides or oxides, or of carbon and / or oxygen-rich phases.
- a binder material which has a primary binder component and a secondary binder component.
- a primary binder component is understood as meaning a component which may be a substance or a mixture of substances whose properties substantially contribute to the flow of the feedstock being processable by injection molding.
- This primary binder component is also referred to as a major binder.
- the secondary binder component is in particular a substance or a mixture of substances which is intended to impart mechanical stability to the green compact - and optionally also the brown compact before sintering - by bonding the metallic particles together.
- This secondary binder component is also referred to as a backbone binder.
- the primary binder component is preferably completely decomposable below a temperature of 500 ° C or at most at 600 ° C.
- an embodiment of the method is preferred in which the primary binder component is chemically removable by dissolution in a solvent, and preferably removed, whereby the secondary binder component is thermally debinded.
- a solvent for chemical debindering of the primary binder component it is preferable to use an organic solvent, especially heptane, cyclohexane, hexane, ethanol and / or acetone.
- no binder component is catalytically debindered, so that is dispensed with a catalytic debindering.
- a binder material is used in which the primary binder component is selected from a group consisting of a paraffin wax, a carnauba wax, a polyolefin wax, polypropylene, polyethylene, polyethylene glycol, a water-soluble polymer, polymethylmethacrylate, and polyoxymethylene.
- the primary binder component may also comprise a majority of these substances, in particular in any desired combination with one another, and / or comprise further additional substances. But it is also possible that the primary binder component consists of one of the aforementioned substances.
- a binder material having a secondary binder component selected from a group consisting of ethylene-vinyl acetate, polyethylene, polypropylene, polystyrene or polystyrene, polyethylene glycol, polymethyl methacrylate, polyamide, polyoxymethylene, and polyvinyl butyral is preferably used.
- the secondary binder component can also have a majority of the substances mentioned here, in particular in any desired combination with one another. In addition to the substances mentioned here, it may also have at least one further substance not mentioned here. But it is also possible that the secondary binder component consists of one of the substances mentioned here.
- An embodiment of the method is preferred, which is characterized in that the - preferably second, thermal debinding step under vacuum, under an atmosphere which comprises at least one inert gas or at least one inert gas, and / or under a hydrogen-containing or Hydrogen existing atmosphere is carried out.
- a debindering under hydrogen, especially under a hydrogen-containing or consisting of hydrogen atmosphere, is particularly advantageous because just in combination with the conversion of S eltener d-element in the inerted compound an extremely efficient protection against the formation of carbides, oxides and / or can be ensured by carbon- and / or hydrogen-containing phases of the s eltener d element.
- the debinding step is additionally or alternatively preferably carried out at a pressure of at least 100 mbar to at most 1 bar, preferably from at least 100 mbar to at most 700 mbar, preferably from at least 200 mbar to at most 600 mbar.
- the debinding step is preferably carried out at a temperature of at most 600 ° C, preferably less than or not more than 500 ° C, preferably at least 100 ° C to at most 500 ° C, preferably at least 200 ° C to at most 400 ° C, particularly preferably at 300 ° C performed.
- a sufficiently large process window for the complete and at the same time with respect to the hard magnetic properties of the resulting permanent magnet gentle decomposition of the binder material is ensured. In particular, in this way, a reaction with the carbon and oxygen stable rare earth hydride phase can be prevented.
- the debinding step is preferably carried out for a period of at least 80 minutes to at most 170 minutes, preferably from at least 100 minutes to at most 150 minutes, preferably for a period of 125 minutes.
- the times mentioned here preferably ensure complete decomposition of the binder material.
- the specifically selected process time for the binder removal step depends, in particular, on the amount of material to be decomposed, in particular, on the size of the part to be binder-removed.
- debindering step is understood here to mean, in particular, the thermal decomposition of binder material, which means in particular that the thermal removal or burnout of the secondary binder component is addressed, and it is therefore possible that in a first debindering step the primary binder component is chemically With the secondary binder component being thermally removed in a second debindering step, which is the debinding step relevant here, this second thermal debinding step is particularly relevant for the method proposed here as debindering step, since carbon and oxygen compounds are formed in this debindering step, which are critical for the hard magnetic properties of the permanent magnet to be formed.
- An embodiment of the method is preferred, which is characterized in that the reconversion of the inertized compound under vacuum and / or under an atmosphere which comprises at least one inert gas or consists of at least one inert gas, is carried out.
- the reconversion of the inertized compound under vacuum and / or under an atmosphere which comprises at least one inert gas or consists of at least one inert gas is carried out.
- the back conversion is preferably carried out at a pressure of at least 100 mbar to at most 1 bar, preferably from at least 100 mbar to at most 700 mbar, preferably from at least 200 mbar to at most 600 mbar.
- the re-conversion is preferably carried out at a temperature of at least 500 ° C, preferably at a temperature above 500 ° C, preferably at a temperature of at least 500 ° C to at most 900 ° C.
- the reconversion is preferably carried out for a period of at least 40 minutes to at most 100 minutes, preferably from at least 50 minutes to at most 90 minutes, preferably from at least 60 minutes to at most 80 minutes, preferably 70 minutes.
- the re-conversion of the inertized compound is preferably carried out in a sintering furnace.
- sintering furnace is understood to mean, in particular, a device which is designed to sinter the parts resulting from the preceding steps of the MIM process, in which case the thermal debinding step can also be carried out in the sintering furnace.
- a sintering step is carried out in vacuo, and / or under an atmosphere which comprises at least one inert gas or consists of at least one inert gas.
- the sintering step is preferably carried out at a pressure of at least 100 mbar to at most 1 bar, preferably from at least 100 mbar to at most 700 mbar, preferably from at least 200 mbar to at most 600 mbar.
- the sintering step is preferably carried out at a temperature of at least 900 ° C to at most 1200 ° C, preferably at a temperature of at least 980 ° C to at most 1100 ° C.
- the sintering step is preferably carried out for a period of at least 100 minutes to at most 160 minutes, preferably from at least 110 minutes to at most 150 minutes, preferably from at least 120 minutes to at most 140 minutes, preferably from 130 minutes.
- a sintered body is produced.
- the sintered body is produced by sintering from the brown or brown body.
- An embodiment of the method is preferred, which is characterized in that after the sintering step, a cooling, preferably under vacuum and / or under an atmosphere which has at least one inert gas or consists of at least one inert gas, takes place, wherein the cooling a heat treatment can connect.
- a cooling preferably under vacuum and / or under an atmosphere which has at least one inert gas or consists of at least one inert gas, takes place, wherein the cooling a heat treatment can connect.
- Such heat treatments are known in particular for conventionally sintered NdFeB magnets and serve to improve the hard magnetic properties of the permanent magnet.
- Such a heat treatment can also be advantageously carried out in a permanent magnet produced according to the method proposed here.
- At least one additional rare earth element or an additional amount of the at least one rare earth element is introduced into the sintered body, more preferably via grain boundary diffusion, preferably by an electrochemical process.
- the coercive force of the permanent magnet can be further increased.
- additional neodymium, dysprosium and / or terbium is introduced into the sintered body.
- An embodiment of the method is also preferred, which is characterized in that a magnetic field is applied to the starting material. Alternatively or additionally, a magnetic field is applied to the sintered body. Particularly preferably, the magnetic field is applied to the starting material during injection molding.
- the magnetic alignment is preferably carried out during the molding process, in particular when the starting material has been introduced into the injection mold or is about to be introduced, or alternatively only towards the end of the flow process during injection molding prior to curing of the binder material.
- a magnetic field in particular a magnetic pulse, is applied to the sintered body, whereby the permanent magnet receives its magnetization, or whereby the magnetization of the permanent magnet is amplified.
- a magnetic field is applied both to the starting material during injection molding and to the sintered body.
- the magnetic particles can first be aligned in the magnetic field during injection molding, wherein this alignment is maintained during sintering.
- the parallel alignment of electron spins of the magnetic material is lost during sintering, but preserving the geometric orientation of the material.
- the application of a magnetic pulse is preferably carried out by means of a pulse magnetometer.
- a starting material is used which comprises NdFeB or consists of NdFeB.
- NdFeB-based permanent magnets in particular NdFeB magnets with a very high energy product, can be produced in an advantageous manner.
- the starting material preferably comprises NdFeB in powdered or granulated form, or it consists of NdFeB in powdered or granulated form.
- a starting material which is in powder form or in granulated form, and which has a powder particle size of not more than 50 ⁇ m.
- the particle size is particularly preferably less than 10 ⁇ m, which makes anisotropic magnetic orientation of the particles during injection molding in the magnetic field particularly feasible.
- a starting material NdFeB powder used or included in the starting material has a grain size of not more than 50 ⁇ m and preferably less than 10 ⁇ m.
- Figure 1 is a schematic representation of an embodiment of the method in the form of a
- Figure 2 is a schematic representation of a temperature profile during a
- FIG. 1 shows a schematic representation of an embodiment of the method for producing a permanent magnet in the form of a flow chart. Two alternative approaches to the procedure are shown in an upper part of the diagram.
- a first alternative embodiment is shown in which in a first step Sl a starting material in the form of a NdFeB powder is provided.
- the neodymium encompassed by the starting material is converted into an inertized compound in a second step S2, which takes place in particular by hydrotreating at overpressure up to 2.5 bar, either at room temperature or at elevated temperature up to 150.degree.
- a hydrogenation reaction of the neodymium with hydrogen produces the neodymium hydride NdH 3 , which is much more stable than elementary neodymium.
- the hydrogenation to NdH is carried out in particular in a first conversion step, in particular for a period of at least 5 minutes to at most two hours, preferably from at least 30 minutes to at most 90 minutes, preferably for one hour.
- this first conversion step can be used in conjunction with a Hydrogen decrepitation treatment of a molten NdFeB alloy can be performed.
- a third step S3 the magnetic powder treated in the second step S2 is then mixed with a binder material, thus producing a feedstock for further processing in the MIM process.
- a first step Sl 'is provided in powder mixture, namely a so-called feedstock, as a starting material which comprises NdFeB powder and a binder material as a mixture.
- This feedstock is treated in a second step S2 'by hydrotreating at overpressure up to 2.5 bar, either at room temperature or elevated temperature, in particular up to 150 ° C, wherein neodymium is hydrogenated to the more stable neodymium hydride NdH 3 .
- This hydrogen treatment of a first conversion step is also preferably carried out for a period of at least 5 minutes to at most two hours, preferably from at least 30 minutes to at most 90 minutes, preferably for a period of one hour. It is to be noted that the time period selected for the alternative second step S2 'should typically be longer than the time period chosen for the second step S2 according to the first alternative, since the additionally present binder material reduces the reactivity of the plastic bound neodymium and thus longer Reaction times required. The feedstock thus treated in the alternative second step S2 'is then provided for the further MIM process.
- a green compact is produced by injection molding from the feedstock.
- a magnetic field is preferably applied to the feedstock so that the individual magnetic grains are aligned in the injection molding material.
- a fifth step S5 takes place by heating the green body under vacuum, under a protective gas atmosphere or under a hydrogen atmosphere, at atmospheric pressure or at reduced pressure of at least 200 mbar to at most 600 mbar, at a temperature of at least 150 ° C to at most 300 ° C a Partial degassing of NdH 3 , with the opposite Carbon and oxygen at least up to about 500 ° C stable compound forms with the approximate molecular formula NdH 2 .7.
- a temperature ramp can be run for this step, preferably from 150 ° C. to 300 ° C., preferably over a period of 60 minutes.
- This is followed, preferably, by a holding time for the temperature at 300 ° C. in order to achieve complete partial degassing of the neodymium hydride into its particularly stable form with the approximate molecular formula NdH 2 . 7 to ensure.
- This hold time is preferably 40 minutes.
- a sixth step S6 the green compact is debinded.
- the binder removal is preferably carried out in two steps, wherein a primary binder component is chemically dissolved by means of a solvent, in particular heptane and / or acetone, whereby a secondary binder component, the so-called backbone binder, is removed thermally.
- the first debinding step namely the chemical debindering of the primary binder component, is carried out before the fifth step S5, ie before the partial degassing of the neodymium hydride.
- the thermal debinding, and thus the second debinding step for removing the secondary binder component is preferably carried out after the fifth step S5, since this thermal debinding step is critical to the possible formation of carbides or oxides in the magnetic material. Therefore, this is preferably before this thermal debinding in its at least to 500 ° C stable form with the approximate molecular formula NdH. 2 7 converted. It is possible that both debindering steps, namely, the first chemical debinding step, and the second, thermal debinding step, are performed after the fifth step S5.
- the decomposition of all remaining organic binder components, in particular the secondary binder component is preferably below a limit temperature for the stability of NdH 2 .
- the binder removal is preferably carried out under a hydrogen atmosphere or under a protective gas atmosphere, in particular under argon atmosphere, in particular either at atmospheric pressure, at reduced pressure, or in vacuo.
- a protective gas atmosphere in particular under argon atmosphere, in particular either at atmospheric pressure, at reduced pressure, or in vacuo.
- the carbon and oxygen components which are formed during debindering can be reacted without reaction with the NdH 2 which is stable to them.
- 7 phase can be dissipated by process gas and / or vacuum.
- a seventh step S7 the temperature is further increased, preferably in the sintering furnace, to above 500 ° C., preferably to above 600 ° C., and a corresponding holding time a dehydration of the neodymium hydride NdH 2 .7 to elemental neodymium.
- This dehydrogenation can be carried out under reduced pressure or under protective gas, in particular under argon, at atmospheric pressure or at reduced pressure. Since neither carbon nor oxygen residues are left in the sintering atmosphere, no undesired formation of neodymium carbides or neodymium oxides can occur.
- step S8 then the sintering takes place, wherein initially a heating to a sintering temperature, which is preferably between 980 ° C and 1100 ° C is carried out.
- a heating to a sintering temperature which is preferably between 980 ° C and 1100 ° C is carried out.
- the elementary neodymium with the alloying elements iron and boron forms a structure consisting essentially of the conventional sintered magnet known phases Nd 2 Fei 4 , Ndi + E Fe 4 B 4 and an Nd-rich grain boundary phase.
- a cooling of the sintered body formed by sintering takes place.
- a customary heat treatment known from sintered NdFeB magnets there is optionally carried out a customary heat treatment known from sintered NdFeB magnets. It is possible that, in addition to the heat treatment, a further aftertreatment takes place, in which additional neodymium, additional dysprosium and / or terbium are introduced into the structure via grain boundary diffusion, for example via an electrochemical process, in particular by the coercive field strength of the permanent magnet to increase.
- an eleventh step Si l the application of a magnetic field, in particular a magnetic pulse, to the sintered body in order to magnetize it.
- the magnetic pulse is preferably applied by means of a pulse magnetometer.
- Fig. 2 shows a schematic representation of a temperature profile in one embodiment of the method.
- a temperature T in ° C is plotted against a process time t in minutes.
- the diagram starts within the method after the fourth step S4, thus after the injection molding and thus the production of the green compact.
- the temperature curve preferably starts at room temperature, in particular at 25 ° C. First, it is heated over a temperature ramp from room temperature to about 150 ° C, during a heating time of about 80 minutes, with the partial degassing of the neodymium hydride NdH 3 beginning at about 150 ° C. It joins a steeper temperature ramp over which a Heat up to about 300 ° C for about 60 minutes.
- the partial degassing and formation of the more stable neodymium hydride having the approximate molecular formula NdH 2 .7 is preferably completed during a hold time at about 300 ° C for about 40 minutes.
- a chemical debinding of the primary binder component has taken place, this is preferably now.
- the heating ramp takes about 170 minutes.
- the temperature is maintained at about 500 ° C for about 125 minutes.
- a thermal decomposition of the secondary binder component thus a thermal debinding.
- a temperature of 1100 ° C for example, is heated up here, namely during a ramp of 250 minutes, wherein for sintering, the temperature at 1100 ° C is held for 130 minutes. It is possible that the temperature is chosen slightly lower than 1100 ° C, in particular between 980 ° C and 1100 ° C, since this is favorable for the magnetic properties of the resulting permanent magnet.
- cooling takes place along a nonlinear cooling curve predetermined, in particular, by the properties of the sintering furnace, preferably cooling to room temperature.
- a heat treatment it may be followed by a heat treatment.
- a magnetic field in particular a magnetic pulse, preferably with a pulse magnetometer, preferably adjoins the sintered body formed during sintering.
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DE (1) | DE112016004392A5 (de) |
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DE102020214335A1 (de) | 2020-11-13 | 2022-05-19 | Mimplus Technologies Gmbh & Co. Kg | Verfahren zur Herstellung eines Permanentmagneten aus einem magnetischen Ausgangsmaterial |
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US6511552B1 (en) * | 1998-03-23 | 2003-01-28 | Sumitomo Special Metals Co., Ltd. | Permanent magnets and R-TM-B based permanent magnets |
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2016
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- 2016-09-22 DE DE112016004392.9T patent/DE112016004392A5/de not_active Withdrawn
- 2016-09-22 EP EP16781067.0A patent/EP3357074B1/de active Active
- 2016-09-22 SI SI201631790T patent/SI3357074T1/sl unknown
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Publication number | Publication date |
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SI3357074T1 (sl) | 2024-04-30 |
EP3357074B1 (de) | 2023-10-25 |
DE112016004392A5 (de) | 2018-06-21 |
WO2017055170A1 (de) | 2017-04-06 |
ES2968229T3 (es) | 2024-05-08 |
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