CN104380403A - METHOD FOR PRODUCING Sr FERRITE SINTERED MAGNET - Google Patents

METHOD FOR PRODUCING Sr FERRITE SINTERED MAGNET Download PDF

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Publication number
CN104380403A
CN104380403A CN201380031855.4A CN201380031855A CN104380403A CN 104380403 A CN104380403 A CN 104380403A CN 201380031855 A CN201380031855 A CN 201380031855A CN 104380403 A CN104380403 A CN 104380403A
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sintered magnet
powder
ferrite sintered
ferrite
silicate glasses
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王子直人
和田洪德
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TDK Corp
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TDK Corp
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    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
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Abstract

The invention provides a method for producing an Sr ferrite sintered magnet which has both excellent Br characteristics and excellent HcJ characteristics, while achieving high reliability. The invention is a method for producing an Sr ferrite sintered magnet, which comprises: a calcination step wherein a calcine containing Sr ferrite is obtained by firing a mixed powder that contains at least a powder of an iron compound and a powder of a strontium compound at 850-1450 DEG C; a pulverization step wherein a calcine powder is obtained by pulverizing the calcine; a step wherein a silicate glass powder is added and mixed into the calcine powder; and a firing step wherein a sintered body containing the Sr ferrite is obtained by firing a molded body, which has been obtained by molding the mixed powder of the calcine powder and the silicate glass powder in a magnetic field, at 1,000-1,300 DEG C. In this method for producing an Sr ferrite sintered magnet, the silicate glass has a softening point of 450-800 DEG C.

Description

The manufacture method of Sr ferrite sintered magnet
Technical field
The present invention relates to a kind of manufacture method of Sr ferrite sintered magnet.
Background technology
As the magnetic material for ferrite sintered magnet, there will be a known the Ba ferrite of the crystalline texture with hexagonal crystal system, Sr ferrite and Ca ferrite.In recent years, among these, as the ferromagnetic material of engine use etc., mainly adopt the Sr ferrite of Magnetoplumbate-type (M type).M type ferrite is with such as AFe 12o 19general formula represent.Sr ferrite has Sr in the A site of crystalline texture.
In order to improve the magnetic characteristic of ferrite sintered magnet, attempt being replaced into the rare earth elements such as La respectively by a part for the element by the element in A site and B site and Co improves magnetic characteristic.Such as, the part disclosed in patent documentation 1 by replacing A site and B site with the rare earth element of specified quantitative and Co improves the technology of residual magnetic flux density (Br) and coercive force (HcJ).
As the representational purposes of ferrite sintered magnet, engine can be enumerated.Ferrite sintered magnet for engine seeks Br and HcJ two excellent, but known usual Br and HcJ is in balance (trade-off) relation.Therefore, seek to establish the technology that can improve Br and HcJ two characteristic further.
As representing the index considering the magnetic characteristic of Br and HcJ two characteristic, there will be a known the calculating formula (for example, referring to patent documentation 1) of Br (kG)+1/3HcJ (kOe).Can say that this value is higher, then be suitable for the ferrite sintered magnet that the purposes of high magnetic characteristic sought by engine etc.
Prior art document
Patent documentation
Patent documentation 1: Japanese Unexamined Patent Publication 11-154604 publication
Summary of the invention
Invent technical problem to be solved
As shown in above-mentioned patent documentation 1, it is effective that the main crystal grain composition of control formation ferrite sintered magnet improves magnetic characteristic.But, if only control the composition of crystal grain, be also difficult to the magnetic characteristic greatly improving existing ferrite sintered magnet.On the other hand, the accessory ingredient contained by ferrite sintered magnet has the effect improving magnetic characteristic or agglutinating property.But, there is the situation damaging the reliability of the intensity or outward appearance etc. of the excellence of ferrite sintered magnet due to the kind of accessory ingredient or amount.Such as, if the ferrite sintered magnet of ferrite sintered magnet low for intensity or surface easily being separated out foreign matter is used for engine, then to worry in the use of engine that ferrite sintered magnet is damaged or peel off.Therefore, the ferrite sintered magnet that not only there is magnetic characteristic but also there is high reliability is sought.
The present invention completes in view of the foregoing, its object is to the excellent providing a kind of residual magnetic flux density (Br) and coercive force (HcJ) two aspect, and has the Sr ferrite sintered magnet of high reliability.In addition, its object is also the engine that provides a kind of efficiency high and excellent in reliability.
The technological means of technical solution problem
The composition that the present inventors are not only conceived to crystal grain is also conceived to make glass ingredient be present in the crystal boundary of Sr ferrite sintered magnet, particularly inquires into raising magnetic characteristic with the coated crystal grain of glass-film.It found that, by forming glass-film on the surface of Sr ferrite sintered magnet, can improve magnetic characteristic and reliability, thus completing the present invention.
Namely, the present invention provides a kind of manufacture method of Sr ferrite sintered magnet in one aspect, it has: pre-burning operation, is burnt till by the mixed-powder at least containing the powder of iron compound and the powder of strontium compound, obtain containing the ferritic pre-burning body of Sr at 850 ~ 1450 DEG C; Pulverizing process, pulverizes described pre-burning body and obtains preburning powder; In described preburning powder, add silicate glasses powder, and carry out the operation that mixes; Firing process, by shaping in magnetic field for the mixed-powder of described preburning powder and described silicate glasses powder, burns till the formed body obtained, obtains containing the ferritic sintered body of Sr at 1000 ~ 1300 DEG C.The softening point of above-mentioned silicate glasses is 450 ~ 800 DEG C.
By above-mentioned manufacture method, the characteristic of residual magnetic flux density (Br) and coercive force (HcJ) two side can be maintained with easy operation manufacture higher, and there is the Sr ferrite sintered magnet of high reliability.
The reason obtaining such effect is also indefinite, but is presumed as follows.
That is, think that even if burn till at relatively low temperatures, silicate glasses contained in formed body also can flow, and above forms uniform glass-film on the surface (interface) of ferrite particle by the silicate glasses of use low softening point.
Further, become the glass-film on the surface of coated Sr ferrite sintered magnet from the Clearance Flow of ferrite particle, the silicate glasses of oozing out, thus can effectively prevent foreign matter from separating out on the surface of ferrite sintered magnet.Its result, thinks and can obtain the high ferrite sintered magnet of reliability.
In manufacture method of the present invention, the average grain diameter of above-mentioned silicate glasses powder is preferably 0.3 ~ 1.0 μm.Thus, the silicate glasses in formed body becomes easy flowing owing to burning till, and the Sr ferrite sintered magnet obtained easily becomes fine and close tissue.
In manufacture method of the present invention, above-mentioned silicate glasses preferably comprises more than any one in boron, alkali and alkaline earth metal ions.Thus, owing to not containing Pb etc. in fact, and the softening point of silicate glasses can be adjusted to the scope of 450 ~ 800 DEG C, therefore, not produce the problem of environment aspect.
In manufacture method of the present invention, preferably in the above-mentioned mixed-powder of pre-burning, comprise above-mentioned silicate glasses further.Thus, in pre-burning operation, glass ingredient contributes to the ferritic sintering of Sr, and can be formed evenly glass-film, thus can magnetic characteristic be improved.
The Sr ferrite sintered magnet obtained by manufacture method of the present invention maintains the characteristic of residual magnetic flux density (Br) and coercive force (HcJ) two aspect higher, and has high reliability.
The present invention is providing a kind of engine possessing above-mentioned Sr ferrite sintered magnet on the other hand.This Sr ferrite sintered magnet can be the magnet obtained by above-mentioned manufacture method.Engine of the present invention maintains the characteristic of residual magnetic flux density (Br) and coercive force (HcJ) two aspect higher owing to possessing, and has the ferrite sintered magnet of high reliability, therefore, has high efficiency and high reliability concurrently.
The present invention provides a kind of generator possessing above-mentioned Sr ferrite sintered magnet in other side in addition.This Sr ferrite sintered magnet can be the magnet obtained by above-mentioned manufacture method.Generating body of the present invention maintains the characteristic of residual magnetic flux density (Br) and coercive force (HcJ) two aspect higher owing to possessing, and has the ferrite sintered magnet of high reliability, therefore, has high efficiency and high reliability concurrently.
The effect of invention
According to the present invention, can provide and can have a manufacture method of the Sr ferrite sintered magnet of the Sr ferrite sintered magnet of excellent magnetic characteristic and high reliability with low manufacturing cost manufacture by easy operation.In addition, can provide there is excellent magnetic characteristic and the Sr ferrite sintered magnet of high reliability.Further, the engine with high efficiency and high reliability and generator can be provided.
Accompanying drawing explanation
Fig. 1 be pattern represent the stereogram of the preferred implementation of ferrite sintered magnet of the present invention.
The explanation of symbol:
10 ... ferrite sintered magnet
Embodiment
Below, as required with reference to accompanying drawing and being described in detail to the preferred embodiment of the present invention.
The manufacture method of the Sr ferrite sintered magnet of present embodiment is below described.The manufacture method of the Sr ferrite sintered magnet of present embodiment has molding procedure and firing process in mixed processes, pre-burning operation, pulverizing process, magnetic field.The details of each operation is below described.
Mixed processes is the operation of the mixed-powder of modulation pre-burning.In mixed processes, first, weigh initiation material and coordinate with the ratio of regulation, utilize wet grinding machine or ball mill etc. to mix 1 ~ 20 hours, and carry out pulverization process.As initiation material, prepare the powder with the compound of the ferritic constitution element of Sr as principal component.As such powder, the powder of iron compound and the powder of strontium compound can be enumerated.In addition, in mixed processes, also can add the SiO as accessory ingredient 2and CaCO 3in powder.
As the compound with the ferritic constitution element of Sr, oxide can be used or by burning till the compounds such as carbonate, hydroxide or the nitrate that can become oxide.As such compound, such as, SrCO can be enumerated 3, La (OH) 3, Fe 2o 3and Co 3o 4deng.The average grain diameter of initiation material does not limit especially, such as, be 0.1 ~ 2.0 μm.Do not need all to mix initiation material in the mixed processes before pre-burning, can add part or all of each compound yet after pre-burning operation.
Pre-burning operation is by the operation of the feedstock composition pre-burning obtained in mixed processes.Pre-burning can wait in oxidizing atmosphere in atmosphere to be carried out.Calcined temperature is 850 ~ 1450 DEG C, is preferably 900 ~ 1350 DEG C, more preferably 1000 ~ 1300 DEG C.Burn-in time under calcined temperature is preferably 1 second ~ 10 hours, more preferably 1 minute ~ 3 hours.The ferritic content of the Sr with structure of hexagonal crystal in the pre-burning body that pre-burning obtains is preferably more than 70 quality %, more preferably more than 90 quality %.The primary particle size of pre-burning body is preferably less than 10 μm, more preferably less than 2.0 μm.
Pulverizing process is that pre-burning body is pulverized the operation obtained containing the ferritic preburning powder of Sr.Pulverizing process can carry out with a step, and coarse crushing operation and Crushing of Ultrafine operation two steps also can be divided into carry out.Pre-burning body is generally graininess or bulk, therefore, preferably first carries out coarse crushing operation.In coarse crushing operation, use vibration rod mill etc. to pulverize with dry type, modulation average grain diameter is the comminuted powder of 0.5 ~ 5.0 μm.The comminuted powder using wet grinding machine, ball mill or airslide disintegrating mill etc. to modulate like this with case of wet attrition, obtains average grain diameter and is 0.08 ~ 2.0 μm, is preferably 0.1 ~ 1.0 μm, the more preferably preburning powder (micropowder) of 0.2 ~ 0.8 μm.
The specific area obtained by BET method of preburning powder is preferably 5 ~ 14m 2/ g, more preferably 7 ~ 12m 2/ g.For grinding time, such as, when using wet grinding machine, it is 30 minutes ~ 10 hours; When using ball mill, it is 5 ~ 50 hours.These times preferably suitably regulate according to breaking method.
In pulverizing process, in preburning powder, add silicate glasses.In the present invention, the softening point of silicate glasses is 450 ~ 800 DEG C, more preferably 500 ~ 700 DEG C.
As such silicate glasses, be not particularly limited, such as, can enumerate Si-B-Na-Ca-O system glass, Si-Na-Ca-O system glass, Si-B-Bi system glass etc.In addition, can preferably use to comprise and be selected from B 2o 3, SiO 2, Bi 2o 3, MgO, CaO, SrO, BaO, Li 2o, Na 2o, K 2o, TiO 2, ZrO 2, V 2o 5, CuO, Ag, GeO 2, Al 2o 3, P 2o 5in the silicate glasses of at least a kind.
Particularly, silicate glasses preferably comprises more than any one in boron, alkali and alkaline earth metal ions, particularly preferably comprises alkali metal.But, if consider environment aspect, preferably avoid using the lead system glass containing lead such as PbO.The average grain diameter of glass powder is 0.3 ~ 1.0 μm, especially, and the more preferably scope of 0.4 ~ 0.8 μm.In addition, the average grain diameter of glass powder is preferably less than the average grain diameter of preburning powder.
By adding such silicate glasses powder in preburning powder, even if thus under the firing temperature of relatively low temperature, also can guarantee the mobility of the glass ingredient in formed body, in firing process, uniform glass-film can be formed on the surface of ferrite particle.Think that such glass-film is by existing equably as glass ingredient at the interface of ferrite particle, thus have and make the ferrite of Sr ferrite sintered magnet form stable effect.In addition, because such glass-film is nonmagnetic material, therefore, by with its coated Sr ferrite sintered magnet, the screening effect of electromagnetism can be obtained, thus Sr ferrite sintered magnet can maintain excellent magnetic characteristic.
When the softening point of silicate glasses is too low, the glass ingredient of melting and ferrite particle react, and can have an impact, there is the situation of a part of crystallization of the glass ingredient reacted to ferrite composition.Its result, is difficult to the ferrite characteristic obtaining expecting, and easily separates out as foreign matter on the surface of ferrite sintered magnet, also tend to be difficult to obtain uniform glass-film.On the other hand, when the softening point of silicate glasses is too high, sufficient mobility can not be obtained under lower firing temperature, uniform glass-film can not be formed, thus tend to be difficult to obtain the action effect that magnetic characteristic improves.
Also SiO can be added together with silicate glasses powder in preburning powder 2, CaCO 3, SrCO 3, BaCO 3, Na 2cO 3and K 2cO 3in powder.As the alkali metal compound of constitution element with Na or K, except above-mentioned carbonate, silicate can be used or comprise the organic compound (dispersant) of Na or K.By adding such accessory ingredient, can agglutinating property be improved and improve magnetic characteristic.In addition, because these accessory ingredients can flow out when carrying out shaping with wet type together with the solvent of slurry, therefore, preferably coordinate manyly than the content of the target in Sr ferrite sintered magnet.
In order to improve the magnetic aligning degree of Sr ferrite sintered magnet, preferably in above-mentioned accessory ingredient is with external Crushing of Ultrafine operation, add polyalcohol.The addition of polyalcohol is 0.05 ~ 5.0 quality % relative to interpolation object, is preferably 0.1 ~ 3.0 quality %, more preferably 0.3 ~ 2.0 quality %.In addition, the polyalcohol of interpolation can be removed by thermal decomposition in the firing process in magnetic field after molding procedure.
In magnetic field, molding procedure is by the preburning powder obtained in pulverizing process shaping operation making formed body in magnetic field.In magnetic field, molding procedure can be carried out with any one method dry formed or that wet type is shaping.From the view point of raising magnetic aligning degree, be preferably wet type shaping.When carrying out wet type and being shaping, Crushing of Ultrafine operation can be carried out with wet type, the slurry obtained is adjusted to the concentration of regulation, as the shaping slurry of wet type.The concentrated of slurry can be undertaken by centrifugation or filter press etc.
The content of the preburning powder in the shaping slurry of wet type is preferably 30 ~ 85 quality %.Decentralized medium as slurry can use water or non-water kind solvent.In the shaping slurry of wet type, in addition to water, also the surfactants such as gluconic acid, gluconate or D-sorbite can be added.The shaping slurry of such wet type is used to carry out in magnetic field shaping.Briquetting pressure is such as 0.1 ~ 0.5 ton/cm 2, applying magnetic field is such as 5 ~ 15kOe.
Firing process is operation formed body being fired into sintered body.Firing process usually waits in oxidizing atmosphere in atmosphere and carries out.Firing temperature is 1000 ~ 1300 DEG C, more preferably 1100 ~ 1250 DEG C, is more preferably 1150 ~ 1250 DEG C.Firing time under firing temperature is preferably 0.5 ~ 3 hour.
When firing temperature is too low, silicate glasses contained in formed body does not flow fully, can not form uniform glass-film, tends to the action effect being difficult to obtain magnetic characteristic raising.In addition, when firing temperature is too high, the glass ingredient of melting and ferrite particle react, and can have an impact, there is the situation of a part of crystallization of the glass ingredient reacted to ferrite composition.Its result, is difficult to the ferrite characteristic obtaining expecting, and easily separates out as foreign matter on the surface of ferrite sintered magnet, tend in addition be difficult to obtain uniform glass-film.Firing temperature preferably suitably regulates with the relation of the softening point with silicate glasses
By above operation, sintered body can be obtained.As required the sintered body obtained like this is processed into the shape of regulation, the Sr ferrite sintered magnet be made up of sintered body can be obtained.
Fig. 1 is the stereogram of the example schematically representing the Sr ferrite sintered magnet obtained by the manufacture method of present embodiment.The mode that Sr ferrite sintered magnet 10 becomes arc-shaped with end face has bending shape, usually has the shape being called as arc section (arc-segment) shape, C shape shape, watt shape shape or bowed shape.Sr ferrite sintered magnet 10 is preferably used as the magnet of such as engine.
Contain the Sr ferrite of the M type with structure of hexagonal crystal as main component in Sr ferrite sintered magnet 10.Sr ferrite as main component represents with such as following formula (1).
SrFe 12O 19(1)
The Fe in Sr and the B site in the A site in the Sr ferrite of above formula (1) can usually replace its part by impurity or the unit of having a mind to add.In addition, the ratio in A site and B site can have and departs from a little.In this case, Sr ferrite can represent with such as following general formula (2).
R xSr 1-x(Fe 12-yM y)zO 19(2)
In above-mentioned formula (2), x and y is such as 0.1 ~ 0.5, z is 0.7 ~ 1.2.
M in general formula (2) is such as being selected from the element of more than a kind in Co (cobalt), Zn (zinc), Ni (nickel), Mn (manganese), Al (aluminium) and Cr (chromium).In addition, the R in general formula (2) is such as being selected from the element of more than a kind in La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium) and Sm (samarium).In addition, in this case, SrF described later can calculate as M and R formation Sr ferrite.
The ferritic quality ratio of Sr in Sr ferrite sintered magnet 10 is preferably more than 90 quality %, more preferably more than 95 quality %, is more preferably more than 97 quality %.Like this, by reducing the quality ratio of the crystalline phase different from Sr ferrite, magnetic characteristic can be improved further.
Sr ferrite sintered magnet 10 contains the composition different from Sr ferrite as accessory ingredient.As accessory ingredient, silicate glasses, oxide and composite oxides can be enumerated.As silicate glasses, oxide and composite oxides, can enumerate, as constitution element, there are the silicate glasses of at least one be selected from Si (silicon), K (potassium), Na (sodium), Ca (calcium), Sr (strontium) and Ba (barium), oxide and composite oxides.As silicate glasses, Si-B-Na-Ca-O system glass, Si-Na-Ca-O system glass, Si-B-Bi system glass can be enumerated.As oxide, such as, SiO can be enumerated 2, K 2o, Na 2o, CaO, SrO, BaO.
The content of the silicate glasses in Sr ferrite sintered magnet 10 is preferably below 10 quality %, more preferably 0.1 ~ 5 quality %, is more preferably 0.5 ~ 2.0 quality %.If the content of silicate glasses is too low, then silicate glasses can not coated crystal grain equably, and cannot realize the stabilisation of ferrite composition, in addition, glass does not ooze out on the surface of ferrite sintered magnet yet, tends to obtain magnetic characteristic and improves effect.On the other hand, if the too high levels of silicate glasses, then tend to damage fully excellent magnetic characteristic.
Each constitution element content separately contained in Sr ferrite sintered magnetic spy 10 is roughly as described below.
In Sr ferrite sintered magnet 10, the content of Si is preferably with SiO 2be scaled 0.3 ~ 0.94 quality %.The lower limit of the content of Si is preferred with SiO further 2be scaled 0.4 quality %, be more preferably 0.45 quality %.If the content of Si is too low, then tend to sintered body densification and damage excellent magnetic characteristic deficiently.The upper limit of the content of Si is preferred with SiO further 2be scaled 0.9 quality %, be more preferably 0.8 quality %.If the too high levels of Si, then tend to damage fully excellent magnetic characteristic.
The total content of Na and K in Sr ferrite sintered magnet 10 is preferably scaled Na respectively 2o and K 2o is 0.004 ~ 0.31 quality %.The lower limit of the total content of Na and K is scaled Na respectively 2o and K 2o is 0.01 quality % more preferably, is more preferably 0.02 quality %, is particularly preferably 0.03 quality %.If the total content of Na and K is too low, then can not reduce sintering temperature, crystal grain carries out grain growth, tends to be difficult to obtain fully high magnetic characteristic.
The upper limit of the total content of Na and K is scaled Na respectively 2o and K 2o is 0.2 quality % more preferably, is more preferably 0.15 quality %, is particularly preferably 0.1 quality %.If the total too high levels of Na and K, then tend to the powder easily producing white on the surface of Sr ferrite sintered magnet 10.If produce powder on the surface of Sr ferrite sintered magnet 10, then the cohesive force of such as engine components and Sr ferrite sintered magnet 10 reduces, thus likely Sr ferrite sintered magnet 10 is peeled off from engine components.That is, the reliability of Sr ferrite sintered magnet 10 is damaged.
From the view point of improving magnetic characteristic and reliability further, the content of the Sr in Sr ferrite sintered magnet 10 converts with SrO and is preferably 10 ~ 13 quality %, more preferably 10.3 ~ 11.9 quality %.In addition, from the same viewpoint, the content of Ba in Sr ferrite sintered magnet 10, converts with BaO and is preferably 0.01 ~ 2.0 quality %, more preferably 0.01 ~ 0.2 quality %.
From the view point of improving magnetic characteristic and reliability further, the content of the Ca in Sr ferrite sintered magnet 10 converts with CaO and is preferably 0.05 ~ 2 quality %, more preferably 0.1 ~ 1.5 quality %.
In addition, in Sr ferrite sintered magnet 10, except these compositions, also can containing the inevitable composition from the impurity contained by raw material or manufacturing equipment.As such composition, such as, can enumerate each oxide of Ti (titanium), Cr (chromium), Mn (manganese), Mo (molybdenum), V (vanadium) and Al (aluminium) etc.
Accessory ingredient is mainly contained in the crystal boundary of the ferritic crystal grain of Sr in Sr ferrite sintered magnet 10.If the ratio of each element contained in change accessory ingredient, then the composition of crystal boundary changes, and its possibility of result can have an impact to the magnetic characteristic of Sr ferrite sintered magnet 10 or reliability.The Sr ferrite sintered magnet 10 obtained by the manufacture method of present embodiment passes through by the rate regulation of specific element contained in accessory ingredient in the scope of regulation, thus has excellent magnetic characteristic and high reliability.In addition, the content of each composition of Sr ferrite sintered magnet 10 can be measured by x-ray fluorescence analysis and inductively coupled plasma emission spectroanalysis (icp analysis).
Sr ferrite sintered magnet 10 preferably meets following formula (3).
1.3≤(SrF+Ba+Ca+2Na+2K)/Si≤5.7 (3)
In above formula (3), SrF represents that removing forms the content of the molar basis of the Sr of the ferritic Sr of Sr in Sr ferrite sintered magnet 10, and Ba, Ca, Na and K represent the content of the molar basis of each element.In the manufacture process of Sr ferrite sintered magnet 10, be greater than the ferritic metering of Sr than (SrFe in the ratio making Sr source relative to Fe source 12o 19) when, produce SrF.The ferritic metering of Sr is less than than (SrFe at the content of Sr 12o 19) when, SrF be less than 0 numerical value, i.e. negative.In this case, if also meet above-mentioned formula (3), then magnetic characteristic and reliability can be improved.
Think that the crystal boundary being present in Sr ferrite sintered magnet 10 by silicate glasses, Sr ferrite sintered magnet 10 meet above-mentioned formula (3), the composition stabilisation of crystal boundary, it contributes to the raising of magnetic characteristic and reliability.
The average grain diameter of the ferritic crystal grain of the Sr in Sr ferrite sintered magnet 10 is preferably less than 2.0 μm, more preferably less than 1.0 μm, is more preferably 0.3 ~ 1.0 μm.If the average grain diameter of the ferritic crystal grain of Sr is more than 2.0 μm, then tend to be difficult to obtain fully excellent magnetic characteristic.On the other hand, the Sr ferrite sintered magnet 10 that the average grain diameter of the ferritic crystal grain of Sr is less than 0.3 μm tends to be difficult to manufacture.
The average grain diameter of the ferritic crystal grain of Sr of Sr ferrite sintered magnet 10 can be measured by following order.Mirror ultrafinish is carried out to the cross section of Sr ferrite sintered magnet 10, carries out etch processes with acid such as hydrofluoric acid.Then, etching face is observed with SEM etc.In the observation image comprising hundreds of crystal grain, after being made clear by the profile of crystal grain, carry out image procossing etc., measure the domain size distribution in c face." particle diameter " in this specification refers to the major diameter (the axial diameter of a) in a face.This major diameter is tried to achieve as the long limit of " rectangle that area is minimum " that be external in each crystal grain.In addition, the long limit of " rectangle that area is minimum " is " draw ratio " relative to the ratio of minor face.In addition, except by acid be etched with except, also can by sample heating etch, i.e. so-called thermal etching.
According to the domain size distribution of the number benchmark measured, calculate the mean value of the number benchmark of the particle diameter of crystal grain.In addition, standard deviation is calculated according to the domain size distribution measured and mean value.In this manual, using these average grain diameters as the ferritic crystal grain of Sr and standard deviation.In Sr ferrite sintered magnet 10, the particle diameter of Sr this crystal grain ferritic is that the crystal grain of more than 2.0 μm is preferably less than 1% relative to the ratio of the number benchmark of crystal grain entirety, more preferably less than 0.9%.Thus, the ferrite sintered magnet with fully high magnetic characteristic can be made.From the same viewpoint, the number mean value (average aspect ratio) of the draw ratio of each crystal grain is preferably about 1.0.
Sr ferrite sintered magnet 10 preferably meets following formula (4).Not only the ferritic crystal grain of Sr is fully trickle for Sr ferrite sintered magnet 10, and has specific composition, therefore, has the high magnetic characteristic as met formula (4).The Sr ferrite sintered magnet 10 meeting this formula (4) has fully excellent magnetic characteristic.By such Sr ferrite sintered magnet 10, can provide and there is more high efficiency engine.
Br+1/3HcJ≥5.3 (4)
In formula (4), Br and HcJ represents residual magnetic flux density (kG) and coercive force (kOe) respectively.
Sr ferrite sintered magnet 10 can use as the magnet of the such as engine for automobile such as fuel pump use, power windows use, ABS (anti-lock braking system) use, fan use, wiper use, electronic-controlled power steering use, active quidance suspension use, starter use, door lock use, electric reverse light microscopic use.In addition, the magnet use of the OA/AV machine engines such as the capstan winch such as use, VTR camera capstan winch use, VTR camera swivel head use, VTR video camera zoom use, VTR camera focus use, radio-cassette player is used, CD/DVD/MD axle is used, CD/DVD/MD loading use, CD/DVD optical pickup use can be loaded with, video tape recorder (VTR) capstan winch, VTR swivel head, VTR reel, VTR as floppy disk (FDD) axle.Further, also can as compressor of air conditioner with, freezer compressor, electric tool drive with, drying machine fan, shaver drive with, electric toothbrush with etc. the magnet of home appliance engine use.Further, can also as manipulator shaft, joint drive with, robot main drive with, machine operation platform drive with, machine operation belt-driven with etc. the magnet of FA machine engine use.
The parts that Sr ferrite sintered magnet 10 is bonded in above-mentioned engine are arranged in engine.The Sr ferrite sintered magnet 10 with excellent magnetic characteristic, due to the generation of the foreign matter (white powder) of the generation and surface that can suppress crack fully, therefore, can bond with engine components fully securely.Like this, Sr ferrite sintered magnet 10 can be suppressed fully to peel off from the parts of engine.Therefore, the various engines possessing Sr ferrite sintered magnet 10 have high efficiency and high reliability concurrently.
The purposes of Sr ferrite sintered magnet 10 is not limited to engine, such as, also can use as parts such as motorcycle electric organ, loudspeaker receiver magnet, magnetron, Magnetic resonance imaging (MRI) field generator for magnetic, CD-ROM clamper, distribution transducer, ABS transducer, the right oil liquid level transducer of fuel, magnetic latch (magnet latch) or isolators.In addition, also can use as the target (bead) when forming the magnetosphere of magnetic recording media with vapour deposition method or sputtering method etc.
Preferred embodiment be illustrated of the present invention above, but the manufacture method of Sr ferrite sintered magnet of the present invention and engine are not limited to above-mentioned situation.
Such as, silicate glasses powder is not limited to add in above-mentioned pulverizing process, also can add in the mixed processes before pre-burning, also can add before pre-burning He after pre-burning in batches.In addition, the shape of Sr ferrite sintered magnet is not limited to the shape of Fig. 1, can suitably change to the shape being suitable for above-mentioned each purposes.
Embodiment
With reference to embodiment and comparative example, content of the present invention is described in further detail, but the present invention is not limited to following embodiment.
(embodiment 1)
[making of Sr ferrite sintered magnet]
While use wet grinding machine by 1000gFe 2o 3powder (primary particle size: 0.3 μm), 161.2gSrCO 3powder (primary particle size: 2 μm) and 3.6gSiO 2powder (primary particle size: 2 μm) is pulverized and is mixed, and carries out drying and whole grain.The powder obtained like this is burnt till 3 hours in atmosphere at 1200 DEG C, obtains granular pre-burning body.Use dry type vibratory rod mill by this pre-burning body coarse crushing, modulating the specific area obtained by BET method is 1m 2the powder of/g.
Add D-sorbite in powder after 130g coarse crushing, use ball mill to carry out case of wet attrition 21 hours, obtain the slurry containing preburning powder.The addition of D-sorbite with the quality of preburning powder for benchmark is 1 quality %.The specific area of the preburning powder after case of wet attrition is 8.8m 2/ g.Slurry after terminating relative to case of wet attrition, adds 1.9g softening point and is the silicate glasses powder (Si-Na-Ca-O system glass, average grain diameter is 0.4 μm) of 550 DEG C and stirs.
Thereafter, regulate the solid component concentration of slurry, use wet type pressing under magnetic field machine to carry out shaping in the applying magnetic field of 12kOe, obtain formed body.This formed body is burnt till in atmosphere at 1150 DEG C, obtains the Sr ferrite sintered magnet of cylindrical shape.
Make the Sr ferrite sintered magnet of sample 1 thus.
The evaluation > of < magnetic characteristic
After being processed the top and bottom of the Sr ferrite sintered magnet made, the B-H plotter that maximum applying magnetic field is 25kOe is used to determine magnetic characteristic.In mensuration, try to achieve Br, HcJ, and calculate the value of Br+1/3HcJ.Show the result in table 1.
< ocular estimate >
After the Sr ferrite sintered magnet of making is placed 7 days in atmosphere, by its surface of visualization, evaluate according to following standard.Show the result in table 1.
A: do not produce crack and white powder on the surface of magnet.
B: create crack on the surface of magnet, but do not produce white powder.
C: create crack on the surface of magnet, and attached to white powder.
[table 1]
Then, the Sr ferrite sintered magnet of sample 2 ~ 11 is made.In sample 2, with except not using silicate glasses powder, other all same with sample 1 method makes sample, and has carried out same evaluation.In sample 3 ~ 11, with except the softening point of the silicate glasses powder made an addition in slurry and the firing temperature of formed body being changed to respectively except shown in table 1, other all same with sample 1 method makes sample, and has carried out same evaluation.Show the result in table 1.
In addition, as silicate glasses powder, in sample 3,4,8 and 9, use Si-B-Na-Ca-O system glass, in other sample, employ Si-Na-Ca-O system glass.
As shown in table 1, formed body Sr ferrite sintered magnet (sample 1,4 ~ 6,9 and 10) of being fired under the firing temperature of regulation of silicate glasses powder containing the softening point with regulation is not produced crack or white powder, and the value of having excellent magnetic properties, particularly Br+1/3HcJ is more than 5.3.
In contrast, not containing in the Sr ferrite sintered magnet (sample 2) of silicic acid glass powder, result is that the value of Br+1/3HcJ is lower than 5.3.In addition, sample (sample 3 and 7) within the scope of the invention and firing temperature be not in sample (sample 8 and 11) within the scope of the invention for the softening point of silicate glasses, and result is all that the value of Br+1/3HcJ is lower than 5.3.Wherein, when firing temperature is too high and when the softening point of silicate glasses is too low, the result of ocular estimate is all poor.
(embodiment 2)
Then, the Sr ferrite sintered magnet of sample 21 ~ 24 is made.In sample 21 ~ 24, with except being changed to respectively by the particle diameter of silicate glasses powder except shown in table 1, other method same with sample 1 makes sample, carries out same evaluation.Show the result in table 2.
[table 2]
As shown in table 2, even if confirm, when changing the average grain diameter of silicate glasses powder, also not produce crack or white powder, and the value of having excellent magnetic properties, particularly Br+1/3HcJ is more than 5.3.
(embodiment 3)
Then, the Sr ferrite sintered magnet of sample 31 ~ 34 is made.In sample 31 ~ 34, in the mode that the content of the silicate glasses in the Sr ferrite sintered magnet finally obtained is identical with sample 1, the interpolation opportunity of silicate glasses and its addition are changed to shown in table 1 respectively.
At this, the rear interpolation 100% in sample 1 refers to the silicate glasses powder 1.9g that the pre-burning body powder 130g after relative to coarse crushing adds.Therefore, such as, the front interpolation 25% in sample 31 refer to using in sample 1 add silicate glasses 1.9g as 100%, in advance in pre-burning body powder containing its 25%, be manufacture method as described below.
In sample 31, use wet grinding machine by 1000gFe 2o 3powder, 161.2gSrCO 3powder, 3.6gSiO 2powder and 4.2g softening point are that silicate glasses powder (Si-Na-Ca-O system glass, average grain diameter the is 0.3 μm) pulverizing of 550 DEG C mixes, and carry out drying and whole grain.The powder obtained like this is burnt till 1 hour in atmosphere at 1000 DEG C, obtains granular pre-burning body.Use dry type vibratory rod mill, modulating the specific area obtained by BET method is 1m 2the powder of/g.
Add D-sorbite in powder after 130g coarse crushing, use ball mill to carry out case of wet attrition 21 hours, obtain the slurry containing preburning powder.The addition of D-sorbite with the quality of preburning powder for benchmark is 1 quality %.The specific area of the preburning powder after case of wet attrition is 10.4m 2/ g.Slurry after terminating relative to case of wet attrition, adds 1.4g softening point and is the silicate glasses powder (Si-Na-Ca-O system glass, average grain diameter is 0.3 μm) of 550 DEG C and stirs.
Thereafter, regulate the solid component concentration of slurry, use wet type pressing under magnetic field machine to carry out shaping in the applying magnetic field of 12kOe, obtain formed body.This formed body is burnt till in atmosphere at 1150 DEG C, obtains the Sr ferrite sintered magnet of cylindrical shape.
Make the Sr ferrite sintered magnet of sample 31 thus.
Similarly by regulating the front addition of silicate glasses powder to manufacture Sr ferrite sintered magnet in sample 32 ~ 34.Then, for sample 31 ~ 34, carry out the evaluation same with sample 1.Show the result in table 3.
[table 3]
As shown in table 3, even if when confirming to add silicate glasses before pre-burning, also do not produce crack or white powder, and the value of having excellent magnetic properties, particularly Br+1/3HcJ is more than 5.3.
(embodiment 4)
Substitute the pre-burning body used in sample 1, change the pre-burning body of calcined temperature in the scope being used in 850 ~ 1450 DEG C, obtain Sr ferrite sintered magnet.These Sr ferrite sintered magnets also confirm there is excellent magnetic characteristic in the same manner as sample 1.In addition, the pre-burning body at 800 DEG C after pre-burning can not be shaping, thus can not obtain formed body and Sr ferrite sintered magnet.
(embodiment 5)
Substitute the silicate glasses used in sample 1, use softening point is Si-B-Na-Ca-O system glass, the Si-B-Bi-Na-O system glass of 550 DEG C, obtains Sr ferrite sintered magnet.These Sr ferrite sintered magnets confirm there is excellent magnetic characteristic in the same manner as sample 1.
Industry utilizes possibility
According to the present invention, the manufacture method can with the Sr ferrite sintered magnet of the Sr ferrite sintered magnet of high magnetic characteristic and high reliability can be provided.In addition, the Sr ferrite sintered magnet with high magnetic characteristic and high reliability can be provided.Further, the engine with high efficiency and high reliability and generator can be provided.

Claims (7)

1. a manufacture method for Sr ferrite sintered magnet, wherein,
Have:
Pre-burning operation, burns till the mixed-powder at least containing the powder of iron compound and the powder of strontium compound at 850 ~ 1450 DEG C, obtains containing the ferritic pre-burning body of Sr;
Pulverizing process, pulverizes described pre-burning body and obtains preburning powder;
In described preburning powder, add silicate glasses, carry out the operation mixed;
Firing process, by shaping in magnetic field for the mixed-powder of described preburning powder and described silicate glasses powder, burns till the formed body obtained at 1000 ~ 1300 DEG C, and obtains containing the ferritic sintered body of Sr,
Described silicate glasses softening point is 450 ~ 800 DEG C.
2. the manufacture method of Sr ferrite sintered magnet as claimed in claim 1, wherein,
The average grain diameter of described silicate glasses powder is 0.3 ~ 1.0 μm.
3. the manufacture method of Sr ferrite sintered magnet as claimed in claim 1 or 2, wherein,
Described silicate glasses comprise boron, alkali and alkaline earth metal ions any one more than.
4. the manufacture method of the Sr ferrite sintered magnet according to any one of claims 1 to 3, wherein,
Described silicate glasses is comprised further in the described mixed-powder of pre-burning.
5. a Sr ferrite sintered magnet, wherein,
Described Sr ferrite sintered magnet is obtained by the manufacture method according to any one of Claims 1 to 4.
6. an engine, wherein,
Possesses Sr ferrite sintered magnet according to claim 5.
7. a generator, wherein,
Possesses Sr ferrite sintered magnet according to claim 5.
CN201380031855.4A 2012-12-03 2013-11-29 METHOD FOR PRODUCING Sr FERRITE SINTERED MAGNET Pending CN104380403A (en)

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Application publication date: 20150225