CN100481281C - Process for clinkering anisotropic permanent ferrite through polymer bonding and modeling - Google Patents
Process for clinkering anisotropic permanent ferrite through polymer bonding and modeling Download PDFInfo
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- CN100481281C CN100481281C CNB2005100335773A CN200510033577A CN100481281C CN 100481281 C CN100481281 C CN 100481281C CN B2005100335773 A CNB2005100335773 A CN B2005100335773A CN 200510033577 A CN200510033577 A CN 200510033577A CN 100481281 C CN100481281 C CN 100481281C
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Abstract
The invention discloses a method for sintering anisotropic permanent ferrite by binding molding of polymer, comprising the following preparing steps: fully mixing ferrite powder with polymer binder accounting for 0.1-3.0% of the total weight of raw materials to obtain molding powder; then heating the molding material and a mould to 60-150 deg.C, placing the molding powder in the mould and making pressure molding under external oriented magnetic field so as to obtain blanks; finally sintering the blanks at the stable temperature of 1200-1280 deg.C to make it. The invention is low-cost, and the obtained ferrite has high magnetic property and has no pollution to the environment and has no effect on the health of producing personnel.
Description
Technical field
The present invention relates to the manufacture method of permanent-magnet ferrite, particularly a kind of method of clinkering anisotropic permanent ferrite through polymer bonding and modeling.
Background technology
As traditional magnetic energy savings material, the main application fields of permanent-magnet ferrite is motor and loud speaker, and they are widely used in each electric appliances of automobile, motorcycle, all kinds of audio/video, computer peripheral equipment and OA equipment and daily life.
Permanent-magnet ferrite is by the different isotropism and the anisotropy permanent-magnet ferrites of being divided into of performance requirement and production method.Wherein, it is chaotic basically that the magnetic particle of isotropism permanent-magnet ferrite distributes, but its production process is simple and economical, is used for the less demanding occasion of magnetic property more; The anisotropy permanent-magnet ferrite is to add an alignment magnetic field magnetic particle is made along the easy magnetizing axis orientation in forming process, and its maximum magnetic energy product is higher 2.5～4 times than isotropism permanent-magnet ferrite.
In the production process of anisotropy permanent-magnet ferrite,, require the coefficient of friction between the magnetic particle that it can freely be rotated, promptly require magnetic particle to have certain dispersiveness and lubrification for making the magnetic particle favorable orientation.Cohesion between the mono domain magnetic particles is strong and dispersed and lubrification is relatively poor, causes its orientations difficulty in magnetic field; Simultaneously, for reaching the desired mechanical strength of green compact, require to have caking property between the magnetic particle again on the technology, promptly can be bonded to one under pressure to reach certain density and intensity.But simple ferrite powder is difficult to the requirement that reaches such, so need add additive in the production process of anisotropy permanent-magnet ferrite in ferrite powder.Selected additive need be to play lubricated and cementation a bit, and the back residue that can volatilize fully in lower temperature range and volatilize does not again influence the material of ferrite magnetic performance.According to the type and the characteristic of additive, the main forming method of anisotropy permanent-magnet ferrite has two kinds of wetpressing and dry pressings.
Wetpressing is to be lubricant with water, and materials are the ooze shape and include moisture between 30～40%.In the forming process, because the effect of externally-applied magnetic field, the easy magnetizing axis of single domain particle turns to outer magnetic field direction gradually; Compress blank then, particle can not rotate voluntarily and cause height-oriented arrangement.Though the properties of product of wetpressing preparation are high and stable, the blank after the moulding is low because of wayward its rate of finished products that makes of dewatering.For example, particularly the weather in spring of South China is moist relatively to be subject to such environmental effects, and airborne moisture makes blank be difficult for drying and dehydrating, causes rate of finished products to reduce when serious (have unexpectedly 50% cracking) significantly; In addition, the blank drying need take large-area place and dry naturally, causes production cost to improve; Also have,, exist therefore that molding time is long, production efficiency is low, the mould structure complexity of shaped device in pressure process, be difficult to the shortcoming that realizes that automation size is produced because wetpressing must get rid of most of moisture from mould.
Dry pressing is that the dry magnetic that is mixed with solid binder and lubricant is filled in the molding space, and moulding is carried out in pressurization in magnetic field.Conventional dry platen press product density height, shrinkage is little, rate of finished products is high, cost is low, realizes serialization production in enormous quantities easily, is particularly suitable for the product of moulding complicated shape such as small-sized magnetic shoe etc.But, conventional dry platen press product is because the orientation of particles degree is poor, and the magnetic property of product often has only 80～90% of magnetic wetpressing product at the same level, for reaching the equal magnetic property of wetpressing product, the dry pressing product need adopt the magnetic of high-grade, has significantly improved production cost; On the other hand, the employed binding agent of conventional dry platen press is generally camphor, and it is a kind of volatile and excitant extra-heavy, harmful material, and heavy dose of contact can cause the cardiomotility paralysis, cause serious spasm.Because the camphor smell is heavy, producers do not advance workshop as not being with breathing mask at all.
Therefore, the novel preparation technology of research and development low cost, environmental protection and high performance dry-pressing formed anisotropy permanent-magnet ferrite is very important, and this also is the problem that the permanent-magnet ferrite manufacturer of South China presses for solution.
Summary of the invention
The objective of the invention is to overcome the shortcoming that exists in the prior art, a kind of method of clinkering anisotropic permanent ferrite through polymer bonding and modeling is provided.
Purpose of the present invention is achieved through the following technical solutions: the method for this clinkering anisotropic permanent ferrite through polymer bonding and modeling comprises following preparation process----
(1) powder process: ferrite powder is fully mixed with the polymeric binder that accounts for raw material total weight 0.1～3.0%, obtain the moulding powder;
(2) moulding: described moulding powder and mould all are heated to 60～150 ℃, again the moulding powder are put into mould,, obtain green part adding compression moulding under the alignment magnetic field;
(3) sintering:, obtain the anisotropy permanent-magnet ferrite at last with described green part sintering under 1200～1280 ℃ stable temperature.
Described polymeric binder is polyamide, polyester, polyalcohols or synthetic wax; One or more mixtures in preferred polyamide, polycarbonate, novolac resin, glycerine, polyethylene glycol, polyvinyl alcohol, the Tissuemat E; More preferably polyethylene glycol.Preferred 0.5～1.5% (percentage by weight) of the consumption of described polymeric binder.The consumption of polymeric binder is very few, and the caking property and the lubrification that are played are relatively poor, makes blank not reach the density of requirement and intensity, also be unfavorable for the rotation of magnetic magnetocrystalline and particle; The consumption of polymeric binder is too much, and the product pore quantity behind the sintering is increased, and reduces product density and magnetic property.
Described ferrite powder is the brilliant magneto plumbite type ferrite powder of hexagonal MO. (Fe
2O
3)
6, wherein M is selected from a kind of element among Sr, Ba, the Pb; Preferred strontium ferrite powder SrO. (Fe
2O
3)
6Ferrite powder can adopt regrind, oven dry, fragmentation, and granularity is preferably 0.9～1.11 μ m.
Described pulverizing process can adopt dispersion powder process, and ferrite powder with after polymeric binder is fully mixed, is crossed mixture 120～200 order sub-sieves again and carried out dispersion treatment with mechanical device, obtains the moulding powder.Adopt and disperse powder process, can further improve the decentralization of ferrite powder, be beneficial to ferrite magnetocrystalline and the particle orientation under magnetic field and rotate arrangement.
In the described forming process, moulding powder and mould all are heated to 60～150 ℃, wherein the temperature of moulding powder is hanged down 10～20 ℃ than the temperature of mould; Preferably described moulding powder and mould all are heated to 100～130 ℃, wherein the temperature of moulding powder is hanged down 10～20 ℃ than the temperature of mould.Forming temperature should be controlled in certain scope, because the polymeric binder in the moulding powder just has best caking property and lubrification in a certain temperature range, after surpassing this temperature range, the coefficient of friction of this polymeric binder raises, lubrication weakens, and the amplitude of variation of green compact density reduces; On the other hand, the formed lubricating film of this polymeric binder is along with the undue rising of temperature is easier to be destroyed, and this is unfavorable for that polymeric binder brings into play its lubrification and caking property.According to the theory of molecular thermalmotion, after temperature raise, the molecular motion aggravation caused along the particle of magnetic field orientating and magnetocrystalline before green compact do not suppress fully, rotated again, caused the degree of orientation of magnet to descend; In addition, the rising of temperature will cause equipment burden, add the reduction of alignment magnetic field, this all is unfavorable for the raising of permanent-magnet ferrite performance and the reduction of production cost.The temperature of described moulding powder is lower than the temperature of described mould, to more help the moulding powder before being filled into the die cavity of mould, polymeric binder in the moulding powder is not in molten condition as yet, help the moulding powder evenly and loosely is filled in the die cavity, thereby help the rotation of magnetocrystalline and particle; Also help simultaneously and improve the even of blank density, further improve magnetic property.
In the described forming process, the intensity in magnetic field is relevant with magnetic particle capability, is generally 5～10kOe, preferred 6～8kOe.
Described sintering process can be carried out in air, also can carry out in the partial pressure of oxygen reducing atmosphere lower than air; Preferred 1240～1260 ℃ of the stable temperature of sintering; Sintering time can be 0.5～2 hour, preferred 1～1.5 hour.
Polymeric binder of the present invention has lower softening point, and the temperature that can reduce the ferrite moulding is to save energy consumption; It has suitable viscosity and flowability under viscous state, can give full play to its caking property and to the lubrication of ferrite magnetocrystalline and particle; It has good stable under normal temperature and ferrite forming temperature, and the gas that generates behind Pintsch process flavor is light, nontoxic, helps environmental protection; It can and volatilize totally gradually along with the temperature rising, and volatile quantity is not concentrated in a certain narrow temperature; Residue after its volatilization does not have influence or influences very little magnetic.The effect of this polymeric binder in the ferrite forming process is as follows: begin rising along with temperature from room temperature, this polymeric binder exists three kinds of states and two transformations, i.e. glassy state, elastomeric state and viscous state, and glass transition and flowing changes.When this polymeric binder is in viscous state and is molten condition: on the one hand, it produces adhewsive action and has flowability on the magnetic surface, can be transferred in the hole between the powder, improve the adhesion between polymer and the magnetic, help the moulding of magnet and the raising of density; On the other hand, it also has lubrification, can reduce the frictional force that ferrite particle rotates in the forming process, helps improving the orientation of particles degree, also can reduce ejection resistance simultaneously.Theory analysis shows, the magnetic property of anisotropy permanent-magnet ferrite depends on the degree of orientation of magnetic magnetocrystalline and particle in magnet density, magnetic powder particle degree and the forming process.In the ferrite forming process, the polymeric binder that is in molten condition has not only improved the density of green compact, and can reduce the frictional force that particle rotates in the forming process, help magnetic magnetocrystalline and the particle abundant orientations under the action of a magnetic field, thereby significantly improve the magnetic property of dry-pressing formed anisotropy permanent-magnet ferrite.
The present invention fully mixes ferrite powder with polymeric binder in pulverizing process, on the one hand, make polymeric binder under forming temperature, can spread over the surface of ferrite powder, change the surface state of powder, thereby improve in the pressing process between the powder and powder and the lubricant effect between powder and the mold wall, improve effective pressing pressure; On the other hand, polymeric binder can be volatilized in blank uniformly in the sintering process, helps improving the density of magnet.
The present invention compared with prior art has following advantage and effect:
(1) cost is low, can adopt other magnetic powders of inferior grade to obtain the anisotropy permanent-magnet ferrite of high magnetic characteristics after using polymeric binder instead;
(2) the magnetic property height of prepared anisotropy permanent-magnet ferrite can be apparently higher than the product of traditional dry-pressing (comprising the camphor binding agent) moulding;
(3) polymeric binder that is adopted is the environmental protection material, volatilization back environmentally safe, to producers' healthy nothing influence.
Embodiment
Below in conjunction with embodiment the present invention is done further detailed description, but embodiments of the present invention are not limited thereto.
Embodiment 1
Adopt the strontium ferrite powder SrO. (Fe of Y30BH grade
2O
3)
6, through regrind, oven dry, fragmentation, granularity is 1.06～1.11 μ m.With V-0.002 type high efficient mixed machine the 2g polyethylene glycol was fully mixed 1 hour with 198g strontium ferrite powder, again mixture is crossed 200 order sub-sieves, and carry out dispersion treatment, obtain the moulding powder with the miniature high-speed dispersion machine; Then moulding powder and mould are heated to 110 ℃ and 130 ℃ respectively, again the moulding powder are put into mold cavity, compression moulding under the alignment magnetic field of 8kOe obtains ferritic green part; Again ferritic green part is put into roller kilns in 1250 ℃ of sintering 1.5 hours, obtained the anisotropy permanent-magnet ferrite at last.
Embodiment 2
The 3g polyethylene glycol fully mixes with 197g strontium ferrite powder, and other is with embodiment 1.
Embodiment 3
Polymeric binder is selected Tissuemat E for use, and other is with embodiment 1.
Embodiment 4
Powder for molding and mould are heated to 130 ℃ and 150 ℃ respectively, and other is with embodiment 1.
Comparative example 1
Adopt the strontium ferrite powder SrO. (Fe of Y30BH grade
2O
3)
6, through regrind, oven dry, fragmentation, granularity is 1.06～1.11 μ m.With V-0.002 type high efficient mixed machine 4g camphor, 2g calcium stearate were fully mixed 1 hour with the 194g ferrite powder, again mixture is crossed 200 order sub-sieves, and carry out dispersion treatment, obtain the moulding powder with the miniature high-speed dispersion machine; Then the moulding powder is put into mold cavity, compression moulding under the alignment magnetic field of 8kOe obtains ferritic green part; Again ferritic green part is put into roller kilns in 1250 ℃ of sintering 1.5 hours.
Comparative example 2
Moulding powder and mould all do not heat, and other is with embodiment 1.
The magnetism testing of the foregoing description 1～4, comparative example 1～2 prepared anisotropy permanent-magnet ferrite the results are shown in Table 1.
The magnetic property comparable situation of table 1 embodiment and the obtained product of comparative example
The fundamental characteristics of permanent-magnet ferrite is used Br (remnant field), H always
Cb(magnetic strength coercive force), H
Cj(HCJ) and (BH)
Max(maximum magnetic energy product) four indexs are represented.From the result of table 1 as can be seen, the magnetic property height of the prepared anisotropy permanent-magnet ferrite of the present invention can be apparently higher than the product of traditional dry-pressing (as the camphor binding agent) moulding.
The density of the permanent-magnet ferrite that the present invention makes is generally at 4.8～4.9g/cm
3, (density is generally at 4.6～4.8g/cm apparently higher than the product of camphor binding agent dry-pressing permanent-magnet ferrite
3), its reason is the adding of polymer, has changed the surface state of powder, thereby has improved in pressing process between the powder and powder and the lubricant effect between powder and the mold wall, has improved effective pressing pressure; Simultaneously, the gap of green compact inside is occupied by the polymer of viscous state, and they play a part even transmitted load, have improved payload, thereby has improved the density and the uniformity of permanent-magnet ferrite.
Claims (10)
1, a kind of method of clinkering anisotropic permanent ferrite through polymer bonding and modeling is characterized in that comprising following preparation process:
(1) powder process: ferrite powder is fully mixed with the polymeric binder that accounts for raw material total weight 0.1～3.0%, obtain the moulding powder;
(2) moulding: described moulding powder and mould all are heated to 60～150 ℃, again the moulding powder are put into mould,, obtain green part adding compression moulding under the alignment magnetic field;
(3) sintering:, obtain the anisotropy permanent-magnet ferrite at last with described green part sintering under 1200～1280 ℃ stable temperature.
2, the method for clinkering anisotropic permanent ferrite through polymer bonding and modeling according to claim 1 is characterized in that: described polymeric binder is polyamide, polyester, polyalcohols or synthetic wax.
3, the method for clinkering anisotropic permanent ferrite through polymer bonding and modeling according to claim 2 is characterized in that: described polymeric binder is a kind of in polycarbonate, novolac resin, glycerine, polyethylene glycol, polyvinyl alcohol, the Tissuemat E.
4, the method for clinkering anisotropic permanent ferrite through polymer bonding and modeling according to claim 1 is characterized in that: described polymeric binder accounts for 0.5～1.5% of raw material total weight.
5, the method for clinkering anisotropic permanent ferrite through polymer bonding and modeling according to claim 1 is characterized in that: described ferrite powder is the brilliant magneto plumbite type ferrite powder of hexagonal MO. (Fe
2O
3)
6, wherein M is selected from a kind of element among Sr, Ba, the Pb.
6, the method for clinkering anisotropic permanent ferrite through polymer bonding and modeling according to claim 5 is characterized in that: described ferrite powder adopts regrind, oven dry, fragmentation, and granularity is 0.9～1.11 μ m.
7, the method for clinkering anisotropic permanent ferrite through polymer bonding and modeling according to claim 1, it is characterized in that: described pulverizing process adopts and disperses powder process, earlier ferrite powder is fully mixed with polymeric binder, then mixture is crossed 120～200 order sub-sieves and carried out dispersion treatment, obtain the moulding powder with mechanical device.
8, the method for clinkering anisotropic permanent ferrite through polymer bonding and modeling according to claim 1 is characterized in that: in the described forming process, moulding powder and mould all are heated to 100～130 ℃.
9, according to the method for claim 1 or 8 described clinkering anisotropic permanent ferrite through polymer bonding and modeling, it is characterized in that: the temperature of moulding powder is hanged down 10～20 ℃ than the temperature of mould.
10, the method for clinkering anisotropic permanent ferrite through polymer bonding and modeling according to claim 1 is characterized in that: in the described sintering process, the stable temperature of sintering is 1240～1260 ℃; The time of sintering is 0.5～2 hour.
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Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100368344C (en) * | 2006-05-30 | 2008-02-13 | 华南理工大学 | Preparation process of anisotropic permanent magnetic ferrite |
| CN103145409B (en) * | 2013-03-11 | 2015-06-03 | 广东江粉磁材股份有限公司 | Manufacturing method of dry-type anisotropic strontium ferrite |
| CN104034154B (en) * | 2014-06-09 | 2016-05-04 | 中钢集团安徽天源科技股份有限公司 | Segmented high-performance strontium ferrite preburning equipment and pre-firing method thereof |
| CN104609869A (en) * | 2015-01-23 | 2015-05-13 | 苏州天源磁业有限公司 | Preparation method of binder solution for molding soft magnetic ferrite |
| US9947988B2 (en) * | 2015-08-06 | 2018-04-17 | Thin Film Electronics Asa | Wireless communication device with integrated ferrite shield and antenna, and methods of manufacturing the same |
| CN107954707A (en) * | 2017-12-13 | 2018-04-24 | 江西伟普科技有限公司 | A kind of preparation method of the magnetic binding material with high heat conduction |
| CN110828091A (en) * | 2019-11-21 | 2020-02-21 | 广东华南半导体光电研究院有限公司 | Preparation method of environment-friendly magnet |
| CN114380588B (en) * | 2020-10-20 | 2023-03-24 | 海安南京大学高新技术研究院 | Preparation method of dry-pressed anisotropic permanent magnetic ferrite |
| CN112375513B (en) * | 2020-11-13 | 2022-06-17 | 横店集团东磁股份有限公司 | Preparation method of high-plasticity soft magnetic ferrite molding binder solution and granule |
| CN113327737B (en) * | 2021-05-25 | 2022-06-10 | 合泰盟方电子（深圳）股份有限公司 | Soft magnetic composite material for inductor and preparation method thereof |
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Non-Patent Citations (2)
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| 用温压法制备铁氧体. 罗青云等.粉末冶金技术，第22卷第6期. 2004 |
| 用温压法制备铁氧体. 罗青云等.粉末冶金技术，第22卷第6期. 2004 * |
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