CN1367509A - Method for manufacturing dry formed sitering magnet - Google Patents
Method for manufacturing dry formed sitering magnet Download PDFInfo
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- CN1367509A CN1367509A CN 02102765 CN02102765A CN1367509A CN 1367509 A CN1367509 A CN 1367509A CN 02102765 CN02102765 CN 02102765 CN 02102765 A CN02102765 A CN 02102765A CN 1367509 A CN1367509 A CN 1367509A
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Abstract
The invention provides a method for manufacturing dry formed sitering magnet. This method is provided with a mixing process where at least a part of starting material powder is mixed, and mixed powder is obtained; a calcinating process where the mixed powder is calcinated and a calcinated object is obtained; a granulating process where the calcinated object is granulated and calcinated object powder is obtained; a molding process where powder to be molded which contains the calcinated object powder is subjected to dry molding in a magnetic field, and a molded object is obtained; and a sintering process where the molded object is baked and a sintered object is obtained. In the calcinating process, a calcinated object whose mean primary grain diameter exceeds 1 &mu m is obtained. The method can improve residual magnetic flux density, while restraining deterioration of coercive force.
Description
Technical field
The present invention relates to method with dry formed manufactured ferrite sintered magnet.
Background technology
Magnetoplumbite type (M type) ferrimagnet of general Sr system because inexpensive and have high magnetic characteristic, is widely used in the electric equipment that is assemblied on tame electrical article and the automobile with motor etc.
Ferrimagnet, general by after mixing the initiation material powder, calcining, after the granularity that is ground into appropriateness then became the calcined body powder, moulding became needed shape and carries out sintering and make.In order to make the anisotropy sintered magnet, in magnetic field, carry out moulding.Forming method roughly is divided into damp process and dry process, is the magnet employing wet type method of forming of target with high magnetic characteristic.
The wet type method of forming at first makes the calcined body powder suspension prepare slurries in the decentralized medium of water etc., and this slurries force feed is filled in the molding space of shaped device, makes formed body outside the molding space by pressurizeing simultaneously decentralized medium to be discharged in magnetic field.The wet type method of forming is owing to adopt decentralized medium, and the particle that constitutes the calcined body powder rotates easily, and its result is orientated under the effect of externally-applied magnetic field easily, can obtain high magnetic characteristic, especially high residue magnetic flux density.Yet the wet type method of forming be owing to must remove decentralized medium, has also that molding time is long, productivity ratio is low, a mould structure complexity of shaped device, the sweeping shortcoming of shaped device.
And dry formed method is filled in dry calcined body powder in the molding space, and moulding is carried out in pressurization in magnetic field.Dry formed method has the low advantage of production cost owing to productivity ratio height, shaped device is simple in structure.Yet, compare with the wet type method of forming, be that existence can not obtain the shortcoming of high residue magnetic flux density in the result who adds the poor orientation under the action of a magnetic field.Moreover, the relict flux density Br of magnet by the density of magnet and the degree of orientation thereof and, decide by the saturation magnetization (4 π Is) that its crystal structure determined, represent with formula, promptly
Br=4 π Is * degree of orientation * density
The orientation of dry formed method is bad, is because there is not the cause of the decentralized medium of the cohesion that relaxes between the calcined body particle, friction.Generally, dry formed method is in order to reduce interparticle friction, adds the organic substance of surfactant etc., perhaps the benefit shape power when improving pressurization and add organic bond.For example, when the spy opens in the flat 7-99129 communique case of wet attrition that proposes after calcining,, improve the degree of orientation and obtain the high residue magnetic flux density by in slurries, adding surfactant.But organic interpolation reduces density, and its result improves the effect of the relict flux density raising that causes, the method that improves the degree of orientation so wish to suppress organic addition owing to offset the degree of orientation.
Therefore, when making ferrimagnet, generally the additive that plays sintering aid, the effect of crystallization particle diameter controlling agent is placed to make it liquid phaseization between the calcined body particle and improve sintered density and coercive force.For example, open shown in the flat 7-99129 communique as above-mentioned spy, the most general additive is SiO
2, CaO.
In addition, open in the flat 11-154604 communique the spy and to propose, have high saturation and high-coercive force concurrently by a part with the principal component of the Sr based ferrite of La and Co displacement M type.Yet, confirm that in this communique high saturation and high-coercive force are the situations with the wet type moulding.
As mentioned above, the past, for the high performance of Sr based ferrite magnet, at first consider with the wet type method of forming to be the 1st scheme, therefore, but the dry formed method of employing cost degradation and to seek the proposal of high performance of magnet few.
For the high-coercive forceization of ferrimagnet, must improve the ratio of the single magnetic field crystalline particle in the magnet.In addition, in order to obtain the high residue magnetic flux density, as previously mentioned, the density that improves magnet is effective.Ferrite sintered magnet, the method that crystal grain is grown up improves density, can realize densification.Therefore, as described above, add SiO
2, CaO etc. sintering aid.Because carry out densification with the crystal grain growth, relict flux density increases, and carries out many magnetic regionizations of crystal grain owing to growing up with crystal grain singlely, coercive force reduces singlely.
Therefore, in the wet type moulding ferrite sintered magnet in past in order to improve coercive force and relict flux density simultaneously, the size of crystal grain is dwindled in employing in calcination process, and in calcination process, by making crystal grain-growth become the crystallization particle diameter of appropriateness, and on the basis that suppresses the coercive force deterioration, improve the method for magnet density.
, in this way, as the sintering aid that is used to make crystal grain-growth, owing to adopt SiO
2, CaO etc. nonmagnetic substance, relict flux density does not improve with the raising of sintered density.But, in wet type moulding ferrite sintered magnet, compare with dry formed ferrite sintered magnet, owing to can improve sintered density, even also can obtain sufficiently high relict flux density in this way.
, in the low utterly dry formed ferrite sintered magnet of sintered density, wish that the method that improves than the more effective relict flux density of wet type moulding ferrite sintered magnet is arranged.
Summary of the invention
But the objective of the invention is to seek on the basis that suppresses coercitive reduction, to improve relict flux density in the ferrite sintered magnet of dry formed manufactured of high characteristic adopting cost degradation but be difficult to obtain.
Adopt the present invention of following (1)～(5) to reach such purpose.
(1) manufacture method of dry formed sitering magnet, wherein, making with hexagonal crystal magnetoplumbite type ferrite is principal phase, containing at least a kind of element that is selected from Sr, Ba and Pb and the component that must contain Sr as A, containing at least a kind of element that is selected from Y, rare earth element and Bi and the component that must contain La as R, Co or Co and Zn during as M, principal component is during with the represented sintered magnet of following formula
Formula A
1-xR
x(Fe
12-yM
y)
zO
19
(x, y, z represent the mol ratio
0.04≤x≤0.45、
0.04≤y≤0.3、
0.9≤x/y≤1.5、
0.95≤z≤1.05)
At least a portion that mixing initiation material powder is set gets the mixed processes of mixed-powder, calcines the calcination process that aforementioned mixed-powder gets calcined body, pulverize the pulverizing process that aforementioned calcined body gets the calcined body powder, the dry formed moulding object powder that contains aforementioned calcined body powder gets the molding procedure of formed body and the sintering circuit that the aforementioned formed body of sintering gets sintered body in magnetic field
In aforementioned calcination process, obtain the calcined body of average primary particle diameter greater than 1 μ m.
(2) manufacture method of the dry formed sitering magnet of above-mentioned (1), wherein, between aforementioned calcination process and aforementioned molding procedure, the part of nonmagnetic initiation material powder is added in the calcined body as the back additive, and back additive is 2～20 quality % with respect to the ratio of the total amount of back additive and calcined body.
(3) manufacture method of the dry formed sitering magnet of above-mentioned (1), wherein, between aforementioned calcination process and aforementioned molding procedure, the part of nonmagnetic initiation material powder is added in the calcined body as the back additive, and back additive is 6～12 quality % with respect to the ratio of the total amount of back additive and calcined body.
(4) manufacture method of the dry formed sitering magnet of above-mentioned (2) or (3), wherein, the initiation material powder that contains aforementioned R all adds as aforementioned back additive with the initiation material powder that contains aforementioned M.
(5) manufacture method of each dry formed sitering magnet in above-mentioned (1)～(4) wherein, in aforementioned calcine technology, obtains the following calcined body of average primary particle diameter 5 μ m.
The present invention is when making dry formed ferrite sintered magnet, and the average primary particle diameter of control calcined body is greater than 1 μ m.The calcining particle (primary particle) of calcined body is the state of secondaryization, supplies with molding procedure after it is crushed to the degree that becomes the single magnetic field particle, and aforementioned average primary particle diameter is in the average grain diameter of pulverizing the primary particle of measuring before the calcined body.
In sintering circuit, the method in past is by at single magnetic field, and with the little comminuted powder of particle diameter particle is grown up, and is suppressing to improve relict flux density on the basis that coercive force reduces, owing to pulverize easily, the primary particle diameter of general calcined body is also little.And the inventor promptly, by promoting particle to grow up at calcination process, compares with method in the past by with the bigger calcined body of average primary particle diameter, can further improve the density of sintered magnet, and it found that and can further improve relict flux density.
Among the present invention, pulverize the average grain diameter behind the calcined body, promptly the average grain diameter of comminuted powder is roughly identical with the method in past.Therefore, the present invention only increases the average primary particle diameter of calcined body, and relict flux density just improves.Though its reason is unclear, even estimate it is that average grain diameter after pulverizing is identical, the cause that the particle that particle diameter is bigger in the comminuted powder is many.
With dry formed method the time, by with the big calcined body of average primary particle diameter, relict flux density height, and can obtain the also very high sintered magnet of coercive force.The inventor studies show that, during with the wet type method of forming, even with the big calcined body of average primary particle diameter, relict flux density can not significantly improve yet, the effect of equal extent in the time of can only obtaining and control the sintering aid addition.Therefore, the average primary particle diameter by the control calcined body improves relict flux density, can only be in dry formed sitering magnet practicability.
Utilize the back additive process in the preferred plan of the present invention.When adopting common powder metallurgic method to make sintered magnet, the whole initiation material powder behind the sintering aid are removed in calcining, pulverize resulting calcined body and carry out moulding, sintering.On the other hand, in the additive process of back, reserve that a part of initiation material powder is not calcined and as the back additive, behind calcining initiation material in addition, with calcined body with aforementioned after additives mixed, carry out moulding and sintering then.When containing Co, if utilize this back additive process, squareness ratio Hk/HcJ improves significantly.In addition, even, therefore can reduce cost because the content of Co, the R of high price also can obtain equal magnet characteristic less.Moreover the Hk among the above-mentioned Hk/HcJ is in the 2nd quadrant of magnetic hysteresis loop, and magnetic flux density becomes 90% o'clock external magnetic field strength in relict flux density.When Hk hangs down, can not obtain high maximum energy product.
The present invention carries out dry formed in magnetic field.Adding under the magnetic field state mould this moment, and moulding object powder is filled in the molding space in the mould.Moulding object powder attracted in the molding space along magnetic field during filling.The inventor finds that when then being filled into moulding object powder in the mould, the fluctuation of packed density (fluctuation between material feeding) diminishes to criticality with the addition of above-mentioned back additive process and control back additive within the limits prescribed in magnetic field.If the fluctuation of packed density is little,, alleviating for the man-hour load of adding that makes sintered body become given size because the accuracy to size of sintered body improves.In addition, the addition of back additive can obtain sufficiently high packed density in setting range, also can obtain the effect that formed body is difficult to crack during the demoulding from mould.Such effect that combination produced by dry formed method in the magnetic field and back additive process is that the inventor finds the earliest.
Though the reason that the packed density fluctuation reduces is not clear, can do similar following supposition.Need not the back during additive process, the calcined body powder itself becomes moulding object powder.Because the calcined body powder is a Magnaglo, when in magnetic field, being filled in the mould, carry out the magnetic cohesion easily.Even the magnetic field intensity during filling is identical, because the generation of magnetic cohesion is always not identical, during additive process, the fluctuation of packed density increases after difference.On the other hand, in the back additive process by nonmagnetic back additive and calcined body powder are mixed with moulding object powder.Therefore, in the back additive process by after the powder of the non magnetic composition that adds, and become the M type ferrite and carry out weighing the samely and mix the calcined body powder of being calcined, in moulding object powder, become the state that separates fully each other.Therefore, estimate that the back additive works as the padded coaming that hinders the interparticle magnetic cohesion of calcined body.The addition of back additive is very little the time, and such effect is insufficient.When then the addition of additive was too many, back additive was difficult to disperse equably in the calcined body powder, the instability so the effect of magnetic agglomeration preventing becomes.Its fluctuation of packed density as a result increases.
It is the sintered magnet of principal phase that the present invention makes hexagonal crystal M type ferrite.
In sintered magnet made in accordance with the present invention, with contain at least a kind of element that is selected from Sr, Ba and Pb and must contain Sr as A, with contain at least a kind of element that is selected from Y, rare earth element and Bi and must contain La as R, during as M, principal component is used Co or Co and Zn
Formula A
1-xR
x(Fe
12-yM
y)
zO
19Expression,
X, y, z represent the mol ratio
0.04≤x≤0.45、
0.04≤y≤0.3、
0.9≤x/y≤1.5、
0.95≤z≤1.05
Preferably
0.12≤x≤0.33、
0.12≤y≤0.25、
1.0≤x/y≤1.3、
0.975≤z≤1.025
In above-mentioned formula, x too hour, promptly the amount of element R is very little the time, element M can not be too many to the ferritic solid solution capacity of hexagonal crystal, saturation magnetization improves effect and/or anisotropy field, and to improve effect insufficient.When x is too big in the hexagonal crystal ferrite element R can not replace solid solution, the orthoferrite that for example contains element R generates the back saturation magnetization to be reduced.Y too hour, saturation magnetization improves effect and/or anisotropy field, and to improve effect insufficient.When y was too big, element M can not be replaced solid solution in the hexagonal crystal ferrite.In addition, even the scope of the replaceable solid solution of element M, anisotropy constant (K
1) and anisotropy field (H
A) reduction also increase.Z too hour owing to contain Sr and the non magnetic of element R increased mutually, so the saturation magnetization reduction.When z is too big, because α-Fe
2O
3Mutually or the non magnetic spinel type ferrite that contains element M increase mutually, so the saturation magnetization reduction.
In above-mentioned formula, no matter x/y is too little, too big, the valence mumber of element R and element M all can not get balance, generates the out-phase of W type ferrite etc. easily.Because of element M is a divalent, when element R is 3 valency ions, be x/y=1 ideally.Moreover x/y is greater than the big reason of 1 field permissible range being, even y is little, because Fe
3+→ Fe
2+Reduction, valence mumber obtains the cause of balance.
The ratio of Sr in the elements A better is more than the 51mol%, is more preferably more than the 70mol%, and be 100mol% well again.When the ratio of the Sr in the elements A is too low, can not fully improve saturation magnetization and coercive force.
The ratio that La accounts in element R better is more than the 40mol%, is more preferably more than the 70mol%, and in order to improve saturation magnetization, preferably element R only uses La.This is because the maximum cause of La when the solid solubility limit amount of hexagonal crystal M type ferrite compared.Therefore, when the ratio of the La among the element R is too low, can not increase the solid solution capacity of element R, the solid solution capacity of its result element M can not increase.In addition, if also use Bi, owing to reduce calcining heat and sintering temperature, favourable on producing.
Element M is Co or Co and Zn.The ratio of Co in the element M better is more than the 50mol%, is more preferably more than the 80mol%, preferably 100mol%.When the ratio of Co was too low, the raising of coercive force and saturation magnetization was insufficient.
In the above-mentioned formula that expression is formed, the mol number of oxygen (O) is 19, and this is that expression element R is 3 valencys, and the situation of the stoichiometric composition ratio when x=y, z=1.The mol number of oxygen is according to the difference of the kind of element R and x, y, z value and different.In addition, when for example calcination atmosphere is reducing atmosphere, the possibility of the defective (room) that forms oxygen is arranged.Moreover Fe exists with 3 valencys in the M type ferrite usually, but also changes into the possibility of divalent etc.In addition, the possibility that the element M of Co etc. also has valence mumber to change, according to these, oxygen changes the ratio of metallic element.In this specification,, the mol numerical table of oxygen is shown 19, sees that by the stoichiometric composition ratio mol number of actual oxygen is deviation more or less though do not rely on the value of the kind of element R and x, y, z.
In sintered magnet, contain SiO
2And CaO, this is added in the above-mentioned principal component as accessory ingredient.SiO
2With the total amount of CaO be 0.77～1.61 quality % to the ratio of above-mentioned principal component, it is desirable to 0.98～1.36 quality %.Moreover the quality of principal component according to containing the metallic element amount in the magnet, utilizes above-mentioned composition formula to calculate.In addition, the mol in the accessory ingredient is 1.3～2.6 than Ca/Si, it is desirable to 1.6～2.4.
Ratio by making accessory ingredient and Ca/Si are in above-mentioned scope, and the unusual particle in the time of can suppressing sintering is grown up, and promotes tabularization of crystal grain simultaneously.Its result can obtain fine and close sintered body, so make the sintered magnet of relict flux very high density simultaneously because the crystallization during sintering is arranged again.When too low, because undue tabularization that promotes crystal grain, coercive force reduces accessory ingredient to the ratio of principal component.And accessory ingredient is to the ratio of principal component when too high, since non magnetic components in proportions height, the result that saturation magnetization reduces, and relict flux density reduces.Ca/Si mol is than too hour, and the raising of sintered density is insufficient.And Ca/Si mol is when too big, i.e. SiO
2In the time of very little, the control that particle is grown up is invalid, and coercive force reduces.
Also can contain Al in the sintered magnet
2O
3Al
2O
3Coercive force is improved but residual density is reduced.Al
2O
3Content it is desirable to below the 1.0 quality %.If adopt the present invention, even with Al
2O
3Content suppresses so far, owing to can obtain sufficiently high coercive force, so can suppress the reduction of relict flux density.Moreover, in order to give full play to Al
2O
3The effect of adding, Al
2O
3Content be preferably more than the 0.1 quality %.
Also can contain B in the sintered magnet
2O
3Because by containing B
2O
3Can reduce calcining heat and sintering temperature, favourable on producing.B
2O
3Content, it is desirable to below the 0.5 quality % with respect to principal component.B
2O
3When content was too many, saturation magnetization reduced.
Preferably do not contain the alkali metal of Na, K, Rb etc. in the sintered magnet, contain but can be used as impurity yet.These elements are converted into Na
2O, K
2O, Rb
2When the oxide of O etc. was asked content, the total of these content it is desirable to below the 3 quality % of whole sintered magnets.When these content were too many, saturation magnetization reduced.
In addition, the form that for example Ga, In, Li, Mg, Mn, Ni, Cr, Cu, Ti, Zr, Ge, Sn, V, Nb, Ta, Sb, W, Mo etc. also can oxides contains.Its content is respectively below the gallium oxide 5 quality %, below the indium oxide 3 quality %, below the lithia 1 quality %, below the magnesium oxide 3 quality %, below the manganese oxide 3 quality %, below the nickel oxide 3 quality %, below the chromium oxide 5 quality %, below the cupric oxide 3 quality %, below the titanium oxide 3 quality %, below the zirconia 3 quality %, below the germanium oxide 3 quality %, below the tin oxide 3 quality %, below the vanadium oxide 3 quality %, below the niobium oxide 3 quality %, below the tantalum oxide 3 quality %, below the antimony oxide 3 quality %, below the tungsten oxide 3 quality %, below the molybdenum oxide 3 quality %.
The available fluorescent X-ray quantitative analysis of the composition of sintered magnet etc. is measured.In addition, principal phase, promptly have the available X-ray diffraction of existing of the ferrite phase of structure of hexagonal crystal to confirm.
Below, manufacture method of the present invention is described.Manufacture method of the present invention with the same mixed processes that the mixture that obtains the initiation material powder arranged of the usual way of dry formed method, calcination process that the aforementioned mixture of calcining obtains calcined body, pulverize that aforementioned calcined body gets the pulverizing process of calcined body powder, the dry formed moulding object powder that contains aforementioned calcined body powder gets the molding procedure of formed body and the sintering circuit of the aforementioned formed body of sintering in magnetic field.
As initiation material, can become all cpds of oxide with oxide or by roasting, for example can use carbonate, oxalates etc.
Thereby the present invention sets calcination condition and obtains average primary particle diameter greater than 1 μ m in calcination process, better is more than the 1.2 μ m, is more preferably the above calcined body of 1.5 μ m.Average primary particle diameter too hour does not realize effect of the present invention.Among the present invention, if the composition of sintered magnet is identical, along with the average primary particle diameter increase of calcined body, the relict flux density of sintered magnet increases singlely, and coercive force reduces singlely.When above-mentioned average primary particle diameter is the 5 μ m left and right sides, be difficult to guarantee high-coercive force with control sintering such as sintering aids the time, the average primary particle diameter of calcined body can not obtain the coercive force of realistic scale during greater than 5 μ m.Therefore, the average primary particle diameter of calcined body it is desirable to below the 5 μ m among the present invention.Moreover the average primary particle diameter of calcined body is measured with sweep electron microscope.This mensuration is at more than 200, and preferred primary particle more than 500 carries out.
Mol ratio Ca/Si by in the control aforementioned auxiliary composition can control relict flux density and coercive force simultaneously, and at this moment, if improve relict flux density, then coercive force reduces.But,, under equal coercive force, obtain higher relict flux density if the average primary particle diameter of calcined body among control the present invention and is compared by the control of Ca/Si mol ratio.
The control of the average primary particle diameter of the calcined body among the present invention is effective when dry formed.Along with the increase of average primary particle diameter, also with dry formed the same, relict flux density increases singlely in the wet type moulding, and coercive force reduces singlely.But during with the wet type moulding, by the effect of control average primary particle diameter raising relict flux density, the effect that obtains with the aforementioned Ca/Si mol ratio of control is suitable.That is, when utilizing the wet type moulding, no matter be the average primary particle diameter of control calcined body, still control the Ca/Si mol ratio, if coercive force is identical, then can only obtain equal relict flux density.
Concrete calcination condition is also formed according to magnet and different, usually, in air or the partial pressure of oxygen reducing atmosphere lower than air, better is 1100～1400 ℃ of calcinings 1 second～10 hours, about preferably 1 second～3 hours.Calcined body has the ferrite structure of magnetoplumbite type in fact.Moreover general calcining heat is higher, or calcination time is longer, and then the average primary particle diameter of calcined body is bigger.
In order to pulverize and even the broken calcined body that generally obtains, pulverizing process is set as graininess.Pulverizing process preferably at first carries out the dry type coarse crushing.During the dry type coarse crushing, in ferrite particle, import the irregularity crystallization, the effect of single reduction coercivity H B is also arranged.Because coercitive reduction, the cohesion of particle is suppressed, the dispersed raising.In addition, by suppressing the cohesion of particle, the degree of orientation improves.The irregularity crystallization that is imported in particle is released in the sintering circuit of back, recovers can be made into permanent magnet by coercive force.
After the dry type coarse crushing, preferred for preparation contains the pulverizing slurries of comminuted powder and water, and it is broken to carry out the wet type fine powder with it.After the wet type fine powder is broken, obtain the calcined body powder by carrying out drying.
In the pulverizing process,, add SiO as the initiation material of above-mentioned accessory ingredient
2Reach the CaCO that becomes CaO by roasting
3The initiation material of accessory ingredient can be to add in the above-mentioned mixed processes before calcining with a part also.Yet the method that the initiation material of accessory ingredient adds after calcining more effectively plays an effect of boundary's composition, and the even particle when helping sintering is grown up.Therefore, addition in pulverizing process better is more than the 50 quality % of whole accessory ingredients, more preferably 80 quality %, segregation partly takes place with Si that is added and Ca on most of grain circle and triple point in impurity, but a part also enters the ferrite part (principal phase) of intragranular.Especially Ca enters the ferritic possibility height of Sr.
The initiation material of the accessory ingredient that adds in pulverizing process can add when the dry type coarse crushing, also can add when the wet type fine powder is broken.
Moreover, in pulverizing process, also can add surfactant and/or organic bond as required.
In the molding procedure, in magnetic field, carry out dry formed.Briquetting pressure is that externally-applied magnetic field can be about 0.5～1.0T about 29～49MPa.
In sintering circuit, usually, in air or the partial pressure of oxygen reducing atmosphere lower, better be at 1150～1270 ℃ than air, be more preferably under 1180～1240 ℃ the temperature (stable temperature) and fire.The time (stabilization time) that remains on stable temperature when firing it is desirable to about 0.5～3 hour.
Among the present invention, starting material compound need all not mix before calcining, can be with part or all formation of adding as the calcining back of each compound.As above-mentioned, Si compound and Ca compound as initiation material (sintering aid) usefulness of accessory ingredient it is desirable to a part is preferably all added after calcining.
In addition, the compound beyond the sintering aid promptly contains at least a portion of the compound of Fe, elements A, element R or element M, preferably also adds after calcining.In this specification, the method for adding sintering aid compound in addition after calcining is called the back additive process.In this back additive process, at first making the hexagonal crystal ferrite that contains aforementioned elements A at least is the calcined body of principal phase.Then, pulverize this calcined body after, or when pulverizing, in calcined body, add and carry out the compound that add the back, then, carry out moulding, sintering.Moreover, in this specification, the compound that carries out adding the back is called the back additive.This back additive also comprises the sintering aid of Si compound, Ca compound etc.
Can use the R oxide as the compound that contains element R, but, the problem of outflow etc. be arranged when the wet type fine powder is broken because the R oxide is bigger to the solubility of water.In addition, owing to also moisture absorption is arranged, become the reason of weighing error easily.Therefore, as the R compound, preferably carbonate or hydroxide.The compound that the back additive that contains other elements can be used as oxide or becomes oxide by roasting for example carbonate or hydroxide adds.Specifically, as back additive, for example the most handy Fe
2O
3, La (OH)
3, Co
3O
4Deng.
The compound of selecting the back to add when implementing the back additive process will make in the additive of back and contain the element of selecting more than a kind or 2 kinds from element R and element M, preferably contains element R and element M.At this moment, the initiation material powder that preferably contains element R all adds as the back additive with the initiation material powder that contains element M.When containing Co,, can improve the characteristic of magnet as described above and reduce cost if utilize this back additive process.
The amount of back additive is preferably 2～20 quality % of total moulding object powder with respect to the total amount of back additive and calcined body.The amount of back additive is very little the time, adopts the back additive process and to make dihedral raising effect and cost reduce effect insufficient.On the other hand, when the amount of back additive is too many, the frequent crackle that takes place on the formed body when leaving mould and carrying out the demoulding.In addition, if back additive is 6～12 quality % to the ratio of total moulding object powder, when then being filled in moulding object powder in the mould in magnetic field, but the fluctuation criticality of packed density ground reduces, and can obtain sufficiently high packed density, and can prevent formed body generation crackle.When back additive was lower than 6 quality %, the fluctuation of packed density increased.When then additive surpassed 12 quality %, except that the fluctuation increase of packed density, itself also reduced packed density, and, crackle takes place on the formed body easily.
Moreover, when the amount of back additive was too many, crackle took place easily on formed body, this be because the content of nonmagnetic powder (back additive) in moulding object powder for a long time, to the cause of the mobile variation in magnetic field.During to the mobile variation in magnetic field, fillibility variation when in magnetic field, being filled in the mould.Specifically, in order to fill the powder of necessary amount, the degree of depth of the molding space in the mould is more deepened.Its result, the displacement when extracting formed body out from mould is elongated, so owing to crackle takes place on formed body the friction with mould easily.
The interpolation time of back additive can be after calcining and before the sintering, but because the back additive must be pulverized more consumingly with calcined body mixes, so preferably in aforementioned pulverizing process, add.Interpolation can be carried out when the dry type coarse crushing, also can carry out when the wet type fine powder is broken.
Moreover, determine the Fe in the calcined body
2O
3The mol ratio of/SrO will become the mixed phase of the single phase of M type ferrite or it and α-Fe, is generally 6～8, is preferably 6～7.5.
The shape that adopts the sintered magnet of manufacturing of the present invention to be processed to stipulate for example, is being used in the purposes widely shown in following.
For example, be suitable for: the automobile motor that petrolift is used etc. with, electronic milling machine with, door lock with, starter with, travelling cradle with, power steering gear with, slide with, fan with, ABS with, automatic open-close type (car) window; The FDD main shaft is used, the VTR capstan is used, the VTR swivel head is used, the VTR spool is used, the VTR assembling is used, VTR video camera capstan is used, VTR video camera swivel head is used, VTR video camera varifocal is used, the VTR video camera focuses on capstans usefulness such as usefulness, radio cassette recorder, CD, LD, MD main shaft are used, CD, LD, MD assemble usefulness, OA, the AV equipment motor that CD, the pick-up of LD light are used etc.; Air compressor, refrigerator car compressor drive with, electric fan with, electric tool and with, make-up machine drive the home appliance motor with, electric toothbrush used etc. with, stirrer-driven with, drier fan with, tray of microwave oven rotation with, fan for microwave oven; Drive from moving axis, joint and to drive usefulness, lathe with, the master of robot and drive with, plant equipment band and drive the FA machinery motor of using etc.; In addition, also be suitable for motorcycle electric organ, loudspeaker and earphone magnet, magnetron, MRI field generator for magnetic, CD-ROM clamper, distribution transducer, ABS transducer, fuel, oily bell jar transducer, electromagnetic clutch etc.
The simple declaration of accompanying drawing
Fig. 1 curve chart that to be expression concern with the coercivity H J and the relict flux density Br of the ferrite sintered magnet of dry formed method.
Fig. 2 curve chart that to be expression concern with the coercivity H J of the ferrite sintered magnet of the wet type method of forming and relict flux density Br.
Embodiment
EXAMPLE l
As the initiation material powder, prepare Fe
2O
3And SrCO
3, these make weighing
N=Fe
2O
3/ SrCO
3In mol be 6.0 than n.Water carries out wet mixed as decentralized medium.
The mixture that calcining obtains, the calcined body that obtains having the average primary particle diameter shown in the table 1.Calcining is 2 hours in air.The relation of calcining heat and average primary particle diameter is 0.8 μ m in the time of 1200 ℃, be 1.2 μ m 1230 ℃ the time, be 1.5 μ m in the time of 1260 ℃, be 2.0 μ m in the time of 1290 ℃.Average primary particle diameter is measured at 500 primary particle.With these calcined bodies of vibrating mill dry type coarse crushing, get the meal flour of average grain diameter 3 μ m.Think the aggregate (secondary) that contains primary particle in this meal flour.The aforementioned average grain diameter of this meal flour is the laser diffraction formula particle size distribution device (HELOS that sells with (strain) NEC; RODOS) measured value is different with the measured value of utilizing the sweep type electromicroscopic photograph.
In this meal flour, add Fe as the back additive
2O
3, La (OH)
3And Co
3O
4Set the addition of back additive, make consisting of behind the sintering
Formula Sr
0.82La
0.18(Fe
11.83Co
0.17) O
19In addition, as the initiation material of accessory ingredient, add SiO simultaneously
2Powder and CaCO
3Powder.Set the addition of accessory ingredient, make SiO
2+ CaO is 1.12% to the mass ratio of principal component, and Ca/Si becomes the value shown in the table 1.Then, being broken into whole average grain diameters with pulverizing mill wet type fine powder is 1 μ m.Decentralized medium water during this is pulverized.
After the wet type fine powder is broken, slurries are dehydrated, add the sublimability adhesive of 1 quality % then after, with the hammer broken condensation product, obtain moulding object powder this.
Then, in the magnetic field of 0.7T, the filling of moulding object powder is in the molding space of formula shaped device, dry formed under the pressure of 39MPa, obtain columned formed body.
The formed body that obtains was fired under 1230 ℃ 1 hour in air, obtained sintered body.Then, sintered body is carried out surface grinding use sample, use the BH tracer to each sample determination magnetic characteristic, and measure density as estimating.Relict flux density Br, coercivity H J and the density d f of each sample are shown in table 1.And the result shown in the table 1 is expressed as HcJ-Br curve among Fig. 1.[table 1]
| Calcined body average primary particle diameter (μ m) | ???Ca/Si | ?????Br ????(mT) | ?????HcJ ???(kA/m) | ?????df ???(g/cm 3) |
| ??????????0.8 * | ????1.7 ????2.0 ????2.3 | ????393.5 ????402.4 ????407.3 | ????354.1 ????303.2 ????225.2 | ????4.921 ????4.956 ????4.983 |
| ??????????1.2 | ????1.7 ????2.0 ????2.3 | ????399.0 ????406.8 ????410.2 | ????345.6 ????292.2 ????224.2 | ????4.932 ????4.975 ????5.018 |
| ??????????1.5 | ????1.7 ????2.0 ????2.3 | ????407.4 ????411.0 ????418.1 | ????325.9 ????278.7 ????222.8 | ????4.982 ????5.013 ????5.045 |
| ??????????2.0 | ????1.7 ????2.0 ????2.3 | ????412.9 ????417.2 ????422.7 | ????315.6 ????267.8 ????211.6 | ????5.002 ????5.035 ????5.058 |
*: outside the limited range
By table 1 and Fig. 1 effect of the present invention as can be known.That is, use the calcined body manufactured samples of average primary particle diameter in prescribed limit according to the present invention, but can guarantee high-coercive force and densification, show the dry formed magnet that adopts the present invention can obtain having high-coercive force and high residue magnetic flux density.Comparative example
Utilize the wet type method of forming, prepare the sintered magnet sample according to the following steps.Until the wet type fine powder is broken, all carry out similarly to Example 1.After the wet type fine powder was broken, it was 73% that slurries are concentrated to solid concentration, preparation moulding slurries.With this moulding slurries moulding, obtain cylindric formed body.Magnetic field intensity during moulding is identical with embodiment 1.Then, the same with embodiment 1, sintered moulded body obtains the sintered magnet sample.
The relation of the coercivity H J of gained sample and relict flux density Br is shown in Fig. 2.The Ca/Si mol ratio of sample shown in Figure 2 is selected in 1.7～2.0 scope.
From Fig. 1 and Fig. 2 more as can be seen, utilize when dry formed, the average primary particle diameter of control calcined body is effective.That is to say, when utilizing the wet type moulding, even the average primary particle diameter difference of calcined body, as shown in Figure 2, the measured value shape that also roughly is in line.That is, when utilizing the wet type moulding, no matter be the average primary particle diameter of control calcined body, still control the Ca/Si mol ratio, if coercive force is identical, can only obtain equal relict flux density.In contrast, utilize when dry formed, recently prevent coercitive reduction if increase the average primary particle diameter and the control Ca/Si mole of calcined body, not only coercive force can not reduce, and can improve relict flux density.
Embodiment 2
Carry out weighing and mix, make n=Fe
2O
3/ SrCO
3In n become the value shown in the table 2, then, calcine and coarse crushing with embodiment 1 the samely.It is 1.5 μ m that the selection of calcination condition will make the average primary particle diameter of calcined body.Then, in the ratio shown in the table 2, add Fe as the back additive
2O
3, La (OH)
3, Co
3O
4, SiO
2And CaCO
3The addition of the back additive shown in the table 2 is the ratio with respect to whole moulding object powder.Moreover, SiO
2With CaCO
3The total addition be 1.7 quality %, Ca/Si is 2.0.After this operation makes the sintered magnet sample with embodiment 1 the samely.Among the composition of these each samples and the embodiment 1 in the manufactured samples Ca/Si be that 2.0 composition is identical.
Dry formed in the magnetic field when making these each samples measured the powder packed density that enters in the molding space.Each sample determination number is 50, asks its mean value and standard deviation.And the ratio (measuring each sample of number 30 times) of the formed body that cracks when from mould, extracting out of investigation.These samples are measured coercivity H J, relict flux density Br and density d f with embodiment 1 the samely, show the result in table 2.[table 2]
| ???n | Back additive: Fe 2O 3(quality %) | Back additive: other (quality %) | Packed density mean value (g/cm 3) | The packed density fluctuation | Cracking frequency | ????Br ???(mT) | ????HcJ ??(kA/m) | ?????df ???(g/cm 3) |
| ??6.00 | ??????14.5 | ?????6.0 | ????1.01 | ??0.3126 | ??8/30 | ???411.0 | ???278.7 | ????5.013 |
| ??6.25 | ??????11.5 | ?????6.0 | ????1.05 | ??0.1912 | ??3/30 | ???411.2 | ???277.3 | ????5.016 |
| ??6.50 | ???????8.5 | ?????6.0 | ????1.11 | ??0.1331 | ??0/30 | ???410.5 | ???278.5 | ????5.015 |
| ??6.75 | ???????5.5 | ?????6.0 | ????1.18 | ??0.0929 | ??0/30 | ???412.2 | ???277.1 | ????5.021 |
| ??7.00 | ???????2.6 | ?????6.0 | ????1.20 | ??0.0874 | ??0/30 | ???412.0 | ???276.5 | ????5.020 |
* other back additive: Co
3O
4, La (OH)
3, SiO
2, CaCO
3
Effect of the present invention as shown in Table 2.If promptly the addition of back additive is below the 20 quality %, then from mould, during the demoulding, be difficult on the formed body crack.In addition, find out that also the addition of back additive is below the 12 quality %, then the fluctuation of packed density is very low, and can obtain sufficiently high packed density, and formed body does not crack.
Embodiment 3
As the back additive, prepare Fe
2O
3, La (OH)
3, Co
3O
4, SiO
2And CaCO
3To the addition of whole moulding body image powder, SiO
2And CaCO
3Identical with embodiment 2, stuck-at-.7 quality %, and Ca/Si is also identical with embodiment 2.In addition, to La (OH)
3, Co
3O
4And Fe
2O
3Determine addition, make formula Sr
1-xLa
x(Fe
12-yCo
y)
zO
19In
x/y＝1.05
z＝1。Other conditions are made the sintered magnet sample with embodiment 2 the samely.
When making these each samples, carry out the mensuration of relevant packed density and crackle with embodiment 2 the samely.Show the result in table 3.Table 3
| Back additive (quality %) | Packed density mean value (g/cm 3) | The packed density fluctuation | Cracking frequency |
| ??????1.7 | ???????1.21 | ?????0.1623 | ?????0/30 |
| ????????4 | ???????1.19 | ?????0.1566 | ?????0/30 |
| ????????6 | ???????1.16 | ?????0.1038 | ?????0/30 |
| ????????9 | ???????1.14 | ?????0.0968 | ?????0/30 |
| ???????12 | ???????1.12 | ?????0.1143 | ?????0/30 |
| ???????15 | ???????1.05 | ?????0.1502 | ?????2/30 |
| ???????18 | ???????1.01 | ?????0.1629 | ?????8/30 |
| ???????21 | ???????0.96 | ?????0.2874 | ????13/30 |
Effect of the present invention as shown in Table 3.That is, by will carry out the addition of the non-magnetic compound that adds of back set in the present invention in the restricted portion, when dry formed, the packed density in mould improves in magnetic field, in addition, formed body is difficult to crack when carrying out the demoulding from mould.And the fluctuation of packed density reduces.
Claims (5)
1. the manufacture method of dry formed sitering magnet, wherein, making with hexagonal crystal magnetoplumbite type ferrite is principal phase, contain at least a kind of element that is selected from Sr, Ba and Pb and must contain Sr as A, contain at least a kind of element that is selected from Y, rare earth element and Bi and must contain La as R, Co or Co and Zn during as M, the principal component formula
A
1-xR
x(Fe
12-yM
y)
zO
19
(x, y, z represent the mol ratio
0.04≤x≤0.45、
0.04≤y≤0.3、
0.9≤x/y≤1.5、
0.95≤z≤1.05) during represented sintered magnet,
Mixed processes that at least a portion of mixing the initiation material powder obtains mixed-powder, calcination process that the aforementioned mixed-powder of calcining obtains calcined body are set, pulverize that aforementioned calcined body obtains the pulverizing process of calcined body powder, the dry formed moulding object powder that contains aforementioned calcined body powder obtains the molding procedure of formed body and fires the sintering circuit that aforementioned formed body obtains sintered body in magnetic field
In aforementioned calcination process, obtain the calcined body of average primary particle diameter greater than 1 μ m.
2. the manufacture method of the dry formed sitering magnet of claim 1, wherein, between aforementioned calcination process and aforementioned molding procedure, the part of nonmagnetic initiation material powder is added in the calcined body as the back additive, and back additive is 2～20 quality % with respect to the ratio of the total amount of back additive and calcined body.
3. the manufacture method of the dry formed sitering magnet of claim 1, wherein, between aforementioned calcination process and aforementioned molding procedure, the part of nonmagnetic initiation material powder is added in the calcined body as the back additive, and back additive is 6～12 quality % with respect to the ratio of the total amount of back additive and calcined body.
4. the manufacture method of claim 2 or 3 dry formed sitering magnet, wherein, the initiation material powder that contains aforementioned R all adds as aforementioned back additive with the initiation material powder that contains aforementioned M.
5. the manufacture method of the dry formed sitering magnet of each of claim 1-4 wherein, in aforementioned calcine technology, obtains the following calcined body of average primary particle diameter 5 μ m.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP019196/2001 | 2001-01-26 | ||
| JP2001019196 | 2001-01-26 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1367509A true CN1367509A (en) | 2002-09-04 |
| CN100472675C CN100472675C (en) | 2009-03-25 |
Family
ID=18885115
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB02102765XA Expired - Lifetime CN100472675C (en) | 2001-01-26 | 2002-01-25 | Method for manufacturing dry formed sitering magnet |
Country Status (2)
| Country | Link |
|---|---|
| CN (1) | CN100472675C (en) |
| HK (1) | HK1048887A1 (en) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100377266C (en) * | 2003-03-25 | 2008-03-26 | 美蓓亚株式会社 | Ferrite magnet and method for production thereof |
| CN101329936A (en) * | 2007-06-21 | 2008-12-24 | 潘树明 | High performance rare-earth composite ferrite with low temperature coefficient and manufacturing technology thereof |
| CN101693621B (en) * | 2004-10-29 | 2012-11-28 | Tdk株式会社 | Manufacture method of ferrite magnetic material |
| CN103413671A (en) * | 2013-08-27 | 2013-11-27 | 南通众兴磁业有限公司 | Method for manufacturing ferrite cores |
| CN104616882A (en) * | 2015-01-17 | 2015-05-13 | 浙江和也健康科技有限公司 | Anisotropic bonded magnet and production process thereof |
| CN108987021A (en) * | 2018-06-21 | 2018-12-11 | 浙江凯文磁钢有限公司 | A kind of permanent-magnet ferrite material and its manufacturing method containing Bi, Ni element |
| CN109155175A (en) * | 2016-05-20 | 2019-01-04 | Tdk株式会社 | Ferrite lattice |
| CN109336579A (en) * | 2018-11-14 | 2019-02-15 | 横店集团东磁股份有限公司 | A kind of motor Ferrite Material and preparation method thereof |
| CN111755192A (en) * | 2019-03-27 | 2020-10-09 | Tdk株式会社 | Ferrite sintered magnet, ferrite particles, bonded magnet, and rotating electrical machine |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1265402C (en) * | 1997-12-25 | 2006-07-19 | 日立金属株式会社 | Ferrimagnet producing method and motor |
| WO2000031756A1 (en) * | 1998-11-26 | 2000-06-02 | Sumitomo Special Metals Co., Ltd. | Ferrite magnet powder and magnet using said magnet powder, and method for preparing them |
-
2002
- 2002-01-25 CN CNB02102765XA patent/CN100472675C/en not_active Expired - Lifetime
-
2003
- 2003-02-11 HK HK03100976.5A patent/HK1048887A1/en not_active IP Right Cessation
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100377266C (en) * | 2003-03-25 | 2008-03-26 | 美蓓亚株式会社 | Ferrite magnet and method for production thereof |
| CN101693621B (en) * | 2004-10-29 | 2012-11-28 | Tdk株式会社 | Manufacture method of ferrite magnetic material |
| CN101329936A (en) * | 2007-06-21 | 2008-12-24 | 潘树明 | High performance rare-earth composite ferrite with low temperature coefficient and manufacturing technology thereof |
| CN103413671A (en) * | 2013-08-27 | 2013-11-27 | 南通众兴磁业有限公司 | Method for manufacturing ferrite cores |
| CN104616882A (en) * | 2015-01-17 | 2015-05-13 | 浙江和也健康科技有限公司 | Anisotropic bonded magnet and production process thereof |
| CN104616882B (en) * | 2015-01-17 | 2017-07-04 | 浙江和也健康科技有限公司 | A kind of anisotropic bonded magnet and its production technology |
| CN109155175A (en) * | 2016-05-20 | 2019-01-04 | Tdk株式会社 | Ferrite lattice |
| CN109155175B (en) * | 2016-05-20 | 2020-09-15 | Tdk株式会社 | Ferrite magnet |
| CN108987021A (en) * | 2018-06-21 | 2018-12-11 | 浙江凯文磁钢有限公司 | A kind of permanent-magnet ferrite material and its manufacturing method containing Bi, Ni element |
| CN109336579A (en) * | 2018-11-14 | 2019-02-15 | 横店集团东磁股份有限公司 | A kind of motor Ferrite Material and preparation method thereof |
| CN111755192A (en) * | 2019-03-27 | 2020-10-09 | Tdk株式会社 | Ferrite sintered magnet, ferrite particles, bonded magnet, and rotating electrical machine |
Also Published As
| Publication number | Publication date |
|---|---|
| HK1048887A1 (en) | 2003-04-17 |
| CN100472675C (en) | 2009-03-25 |
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