CN100449658C - Magnetic field gel injection molding method for large scale rare-earth sintering magnet - Google Patents
Magnetic field gel injection molding method for large scale rare-earth sintering magnet Download PDFInfo
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- CN100449658C CN100449658C CNB2006101125404A CN200610112540A CN100449658C CN 100449658 C CN100449658 C CN 100449658C CN B2006101125404 A CNB2006101125404 A CN B2006101125404A CN 200610112540 A CN200610112540 A CN 200610112540A CN 100449658 C CN100449658 C CN 100449658C
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Abstract
The invention relates to a magnetic gel injection molding method of large-scale rare-earth sinter magnet, wherein it comprises: dissolving ethyl acrylate into toluene to be the pre-mixed solution at 5-50vol.%; adding disperse agent into the pre-mixed solution to be mixed with magnetic powder in Ar condition inside vacuum operation box; grinding the mixture material for 2-24hours; adding initiator, defoaming the slurry room for 5-30mins; pouring slurry into mould; heating mould to 40-80Deg. C; heeping the temperature of magnetic field for 30-150mins; demoulding; vacuum drying, to obtain the rare-earth magnetic blank; vacuum sintering the blank, thermally treating to obtain the rare-earth sintered magnet. The invention has the advantages that: it can improve the magnetic directed degree to obtain high magnetic property, with simple operation and lower cost.
Description
Technical field
The invention belongs to the powder metallurgy forming technical field, the magnetic field gel injection molding method of large scale rare-earth sintering magnet particularly is provided.
Background technology
At present, Nd-Fe-B system or Sm-Co are that the prior powder metallurgy pressing process is mainly adopted in rare-earth sintering magnet production.In magnetic field compression moulding process, magnetic improvement of the degree of orientation in magnetic field is the key factor that improves the permanent magnet magnetic performance.But magnetic will meet obstructions in the orientation rotation process.Irregular mechanical resistance that causes of frictional force, powder shape that resistance produced when mainly coming from powder particle and being in contact with one another and the frictional force between magnetic and the mould.And as a kind of micron dimension powder, magnetic is owing to the interaction of Van der Waals force, London power and magnetic force between the powder, and powder is agglomerated into the secondary powder particle, makes the powder flowbility variation, has increased difficulty for compression moulding powder particle magnetic field orientating.
In order to obtain the high-orientation rare-earth sintering magnet, the researcher invests wet therapy forming process to sight, wishes that good fluidity by liquid reduces to be suspended in the frictional force between wherein the powder, realizes the consistency that is orientated after the match in lower orientation.It is powder injection-molded that (Powder Injection Molding PIM) is the metallurgical near-net-shape technology of a more noticeable in the world in recent years novel powder.Lee S.H. is 5 μ m, Nd in irregular shape with particle diameter
14.7Fe
64.1Co
12.9A
10.8Zr
0.6B
6.9Magnetic and binding agent paraffin in inert atmosphere in 80 ℃ of mixing 10min, injection moulding under the effect of 85 ℃ of injection temperatures, injection pressure 19.4MPa and 8kOe externally-applied magnetic field then, 600～800 ℃ are carried out hot degreasing in hydrogen or argon gas atmosphere, 1100 ℃ of following sintering 1h in a vacuum, having obtained maximum magnetic energy product is 232kJ/m
3Magnet.Yamashita O. adopts methylated cellulose aqueous solution to do binding agent melting under 283K, and 20 ℃ injection temperature, 80 ℃ mold temperature is under the alignment magnetic field effect of 1.35MA/m, with the injection molding of 1.7MPa; Take off after binding agent, the dehydrogenation green compact in a vacuum 300 ℃ keep 0.5h down, at 1120 ℃ of vacuum-sintering 4h, subsequently at 500 ℃ of vacuum annealing 2h, the magnetic energy product of the magnet of acquisition is suitable substantially with traditional handicraft production.
But, generally speaking, the injection moulding sintered Nd-Fe-B need be added the thermoplastic polyester (as polyamide, polyolefin, polyvinyl chloride, polystyrene etc.) of 15%～50% percentage by volume as binding agent, high-temperature mixing process and organic pyrolysis subtractive process very easily make Nd-Fe-B oxidation, carburetting, and carbon residue in the alloy and oxygen content too Gao Junhui make the magnetic property of magnet impaired; And the very long subtractive process of a large amount of organic binder bonds is realized powder injection-molded being difficult to of large-scale part.On the other hand, injection molding feeding is dispersed in magnetic and obtains in the organic substance, and therefore in injection moulding and orientation process, the viscosity of feeding has intense influence to the orientation of magnetic.
Gel casting forming (gelcasting) is invented in early 1990s by people such as U.S. Oak Ridge National Laboratory professors M.A.Janney, is a kind of complicated shape pottery or the metal parts near-net-shape method that receives much attention in recent years.Its moulding mechanism is that organic monomer and solvent are mixed with certain density premixed liquid, metal or ceramic powder suspension are in the concentrate suspension of wherein making low viscosity, high solid loading, add after initator and the catalyst, this concentrate suspension (slurry) is injected non-porous mould, under certain temperature condition, organic polymer is monomer crosslinked to aggregate into three-dimensional network shaped polymer gel, and makes powder particle original position bonding and solidify to form base substrate.Base substrate drying, sintering obtain densification product.Its advantage is easy-formation large scale, complicated shape goods, and molding blank density is even, intensity is high, do not need special degreasing process.
Summary of the invention
The object of the present invention is to provide the magnetic field gel injection molding method of large scale rare-earth sintering magnet, adopt magnetic field gel injection molding technology to realize the production of big the rare-earth sintering magnet of complicated shape of large scale, high magnetic characteristics.
It is Sm-Co based sintered magnet and Nd-TM-B based sintered magnet that the present invention is suitable for rare-earth sintering magnet, and wherein TM represents Fe or Fe and Co.
The present invention dissolves in toluene with hydroxy-ethyl acrylate to be mixed with certain density premixed liquid, after premixed liquid adds dispersant, in the vacuumizing case, mixes with rare-earth magnetic under the Ar atmosphere and stir and the injection ball grinder, obtain suspended nitride through ball milling, add initator and catalyst after the froth in vacuum, afterwards this concentrate suspension slurry is injected non-porous mould, under certain temperature condition and magnetic field intensity, organic polymer is monomer crosslinked to aggregate into three-dimensional network shaped polymer gel, and makes powder particle original position bonding and solidify to form base substrate.Obtain rare-earth sintering magnet after base substrate drying, sintering, the heat treatment.Concrete technology is as follows:
A, hydroxy-ethyl acrylate is dissolved in toluene, makes the premixed liquid of 5～50vol.% (vol.% is a percent by volume) stable homogeneous;
B, in premixed liquid, add dispersant after, in the vacuumizing case, mix with magnetic under the Ar atmosphere; Wherein magnetic is 10～60vol.% of mixture; The dispersant that uses any as in polyacrylamide, polyacrylic acid, the polymethyl acid amide, dispersant dosage accounts for the 0.05～1.0wt% (wt% is a mass percent) of magnetic quality;
C, with b step gained compound ball milling 2～24 hours;
Behind d, adding initator benzoyl peroxide and the catalyst dimethylaniline, just c step gained slurry room temperature froth in vacuum is 5～30 minutes; Initiator amount accounts for 0.005～0.5wt% of magnetic quality; Catalyst amount accounts for 0.001～0.01wt% of magnetic quality;
E, slurry is injected mould, heating mould to 40～80 ℃ afterwards, insulation demoulding after about 30～150 minutes in magnetic field, room temperature vacuumize 12～72 hours obtains the rare earth magnet base substrate;
F, base substrate obtain rare-earth sintering magnet through 1000 ℃～1400 ℃ insulations of vacuum, 30～300min sintering, 300 ℃～900 ℃ insulation 30～120min heat treatment.
Described mold materials is glass or metal, rubber, plastics.
The present invention is applied to the main advantage of rare-earth sintering magnet moulding with the gel casting forming technology and is than other forming technique:
(1) compares with magnetic field compression moulding, gel casting forming is as a kind of wet method pressureless compacting technology, the frictional force that the suspended state of magnetic in liquid phase produced in the time of can reducing magnetic powder particle and be in contact with one another, because the frictional force between mechanical resistance, magnetic and the mould that out-of-shape causes, make magnetic outside identical, be arranged in outer magnetic field direction after the match to a greater extent, obtain high magnetic property thereby improve the magnetic aligning degree;
(2) body of powder when gel casting forming slurry and magnetic field compression moulding can be regarded the magnetic composite material of magnetic and non-magnetic liquid or gas composition as.Under low filling rate, the relative permeability μ of magnetic composite material
rBe directly proportional with the volume of filling magnetic, that is:
μ
r(V)＝1+AV
In the formula,
A-depends on the coefficient of magnetic material performance, shape and loading;
The volume fraction that the V-magnetic material is filled.
The slurry of gel casting forming can realize that the solid concentration high than magnetic field compression moulding is high particle content and can not damage orientation effect.Go up according to this formula, the magnetic composite material relative permeability μ that particle content is high during orientation
rHigher; And B=μ
rB
0, so the magnetic field in the higher gel casting forming slurry of particle content is higher relatively, helps obtaining than high-orientation;
(3) viscosity is lower than 0.01Pas under the gel casting forming solvent for use normal temperature; During magnetic field orientating, magnetic powder particle compares to process of injection molding, and littler, the action of resistance is more prone to when outer magnetic field direction rotates, therefore identical outside after the match, the gel casting forming rare-earth sintering magnet helps acquisition than high-orientation;
(4) to contain organic substance few for the gel casting forming base substrate, and 70%～90% for easy volatile solvent, can remove by dry run; After the solvent evaporates, the base substrate hole mostly is through hole, makes all the other organic substances be easy to remove, and does not therefore need special degreasing process, can prepare large-scale part and production efficiency height;
(5) the gel casting forming rare-earth sintering magnet need not high-temperature mixing and degreasing process, and magnetic is not contacted with oxygen in the air by the liquid encirclement in the forming process, and residual oxygen carbon residue is few, and magnetic property can be therefore not impaired;
(6) along with the continuous progress of science and technology, more and more higher and shape becomes increasingly complex to the precision requirement of magnet, and traditional manufacturing technology (as compression moulding) can't be economical satisfies above requirement.Mold materials such as the paraffin that the gel casting forming technology can be utilized is cheap, be convenient to obtain complicated shape, plastics clearly show minutia, and forming process does not need main equipment, easy and simple to handle, can under the prerequisite of lower cost, satisfy the requirement of large scale, complicated shape simultaneously, solve this difficult problem;
(7) gel casting forming technology mould therefor is simple in structure, is convenient to the setting of all directions externally-applied magnetic field, and equipment cost is reduced.
Description of drawings
Fig. 1 prepares the X-ray diffraction spectrum in Sintered NdFeB magnet (embodiment 1) vertical orientated direction cross section for the present invention.
Embodiment
Embodiment 1
The NdFeB powder is commercially available air-flow abrasive dust, and purity is 99.9%, particle mean size 3.7 μ m; The chemical composition of powder is Nd
2Fe
14B matrix phase constituent; It is pure that hydroxy-ethyl acrylate, solvent toluene, initator benzoyl peroxide, catalyst dimethylaniline, oleic acid are analysis.
The 30ml hydroxy-ethyl acrylate is dissolved in 70 milliliters of toluene, adds 760 gram NdFeB powder and 3 gram polyacrylic acid dispersant, ball milling adds initator and catalyst after 24 hours, froth in vacuum 30 minutes, the slurry of acquisition solid volume fraction 50%.With slurry injected plastic mould, in magnetic field, in 80 ℃ of following insulations 60 minutes, demoulding final vacuum can obtain magnetic field gel injection molding magnet base substrate in dry 12 hours with mould; Base substrate obtains the NdFeB sintered magnet after sintering, heat treatment.The X-ray diffraction spectrum in the vertical orientated direction of the Sintered NdFeB magnet cross section of this prepared is seen Fig. 1.
Embodiment 2
Sm-Co alloy powder composition is Sm (Co
0.72Fe
0.17Cu
0.08Zr
0.03)
7.5, particle mean size 4.1 μ m; It is pure that hydroxy-ethyl acrylate, solvent toluene, initator benzoyl peroxide, catalyst dimethylaniline, oleic acid are analysis.
10 gram hydroxy-ethyl acrylates are dissolved in 90 milliliters of toluene and make solution, add 840 gram titanium valves and 6 gram polyacrylamide dispersants, ball milling adds initator and catalyst after 24 hours, and froth in vacuum 20 minutes makes solid volume fraction and be 50% slurry.The gained slurry is injected glass mold, and in magnetic field, in 60 ℃ of insulations 120 minutes, slurry is cured as base substrate in the mould with mould, and demoulding final vacuum can obtain magnetic field gel injection molding magnet base substrate in dry 48 hours; Base substrate obtains the SmCo sintered magnet after sintering, heat treatment.
Claims (1)
1, a kind of magnetic field gel injection molding method of large scale rare-earth sintering magnet is characterized in that, technology is:
A, hydroxy-ethyl acrylate is dissolved in toluene, makes the premixed liquid of 5～50vol.% stable homogeneous;
B, in premixed liquid, add dispersant after, in the vacuumizing case, mix with magnetic under the Ar atmosphere; Wherein magnetic is 10～60vol.% of mixture; The dispersant that uses any as in polyacrylamide, polyacrylic acid, the polymethyl acid amide, dispersant dosage accounts for 0.05～1.0wt% of magnetic quality;
C, with b step gained compound ball milling 2～24 hours;
D, add initator benzoyl peroxide and catalyst dimethylaniline after, with gained slurry room temperature froth in vacuum 5～30 minutes; Initiator amount accounts for 0.005～0.5wt% of magnetic quality; Catalyst amount accounts for 0.001～0.01wt% of magnetic quality;
E, slurry is injected mould, heating mould to 40～80 ℃ afterwards, in magnetic field, be incubated 30～150 minutes after the demoulding, room temperature vacuumize 12～72 hours obtains the rare earth magnet base substrate;
F, base substrate obtain rare-earth sintering magnet through 1000 ℃～1400 ℃ insulations of vacuum, 30～300min sintering, 300 ℃～900 ℃ insulation 30～120min heat treatment;
Described rare-earth sintering magnet is Sm-Co based sintered magnet or Nd-TM-B based sintered magnet, and wherein TM represents Fe or Fe and Co.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101503299B (en) * | 2009-02-06 | 2012-12-26 | 中国计量学院 | Gel injection moulding preparation for gradient material in rotating magnetic field |
| CN103862052B (en) * | 2012-12-17 | 2017-10-31 | 北京中科三环高技术股份有限公司 | A kind of manufacturing process of isotropism neodymium iron boron magnetic body |
| CN103426621B (en) * | 2013-06-19 | 2015-12-23 | 浙江中元磁业股份有限公司 | A kind of method and size conditioning agent regulating neodymium iron boron magnetic body size |
| CN108231310B (en) * | 2016-12-15 | 2021-05-28 | 北京中科三环高技术股份有限公司 | Preparation method of modified neodymium iron boron magnetic powder, modified neodymium iron boron magnetic powder and neodymium iron boron sintered body |
| CN112185642A (en) * | 2020-09-23 | 2021-01-05 | 江西艾特磁材有限公司 | Method for coating magnetic powder core with ball milling modified sol-gel |
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|---|---|---|---|---|
| CN1445196A (en) * | 2003-04-14 | 2003-10-01 | 浙江大学 | Method for preparing gelatin mold made from functional gradient material in static magnetic field |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1445196A (en) * | 2003-04-14 | 2003-10-01 | 浙江大学 | Method for preparing gelatin mold made from functional gradient material in static magnetic field |
Non-Patent Citations (6)
| Title |
|---|
| 凝胶注模成型工艺研究. 晏伯武.中国陶瓷，第42卷第2期. 2006 |
| 凝胶注模成型工艺研究. 晏伯武.中国陶瓷，第42卷第2期. 2006 * |
| 凝胶注模成形技术的研究与发展. 杜景红等.陶瓷，第1期. 2006 |
| 凝胶注模成形技术的研究与发展. 杜景红等.陶瓷，第1期. 2006 * |
| 铁基粉末凝胶注模成形工艺研究. 刘卫华等.粉末冶金工业，第16卷第1期. 2006 |
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