CN104379537A - Manufacturing method for Sr ferrite particles for sintered magnet, and manufacturing method for Sr ferrite sintered magnet - Google Patents

Manufacturing method for Sr ferrite particles for sintered magnet, and manufacturing method for Sr ferrite sintered magnet Download PDF

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CN104379537A
CN104379537A CN201380029932.2A CN201380029932A CN104379537A CN 104379537 A CN104379537 A CN 104379537A CN 201380029932 A CN201380029932 A CN 201380029932A CN 104379537 A CN104379537 A CN 104379537A
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sintered magnet
ferrite
ferrite sintered
alkali metal
manufacture method
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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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Abstract

The present invention has: a mixing step in which a mixture is prepared by mixing an iron compound powder, a strontium compound powder, and, as a constituent element, an alkali metal salt compound powder of an alkali metal element; and a calcination step in which the mixture is fired at 850-1100 DEG C to obtain Sr ferrite particles of which the primary particles have a mean particle diameter of 0.1-1.0 [mu]m. In the mixing step, the alkali metal salt compound is mixed in so that, relative to the total of the iron compound powder and the strontium compound power, the total of the alkali metal is 0.03-1.05 mass% in terms of alkali metal oxide, and the alkali metal compound is at least one among an alkali chloride, an organic acid salt, a phosphate, a borate or a zeolite.

Description

The manufacture method of sintered magnet with Sr ferrite particle, the manufacture method of Sr ferrite sintered magnet
Technical field
The present invention relates to the manufacture method of the manufacture method of sintered magnet Sr ferrite particle, Sr ferrite sintered magnet.
Background technology
As the magneticsubstance being used to ferrite sintered magnet, as we all know there are Ba ferrite, Sr ferrite and the Ca ferrite with hexagonal crystal structure.In recent years, among those, as engine with etc. ferromagnetic material mainly have employed the Sr ferrite of Magnetoplumbate-type (M type).M type ferrite is by such as general formula AFe 12o 19represent.Sr ferrite has Sr in the A site of crystalline texture.
In order to improve the magnetic properties of Sr ferrite sintered magnet and the part that attempt by replacing the element in A site and the element in B site respectively with the rare earth elements such as La and Co, improve magnetic properties.Such as, in patent documentation 1, disclose the part by replacing A site and B site with the rare earth element of specified quantitative and Co thus improve the technology of residual flux density (Br) and coercive force (HcJ).
Representational purposes as Sr ferrite sintered magnet can enumerate engine and generator.Although the Sr ferrite sintered magnet being used to engine and generator is required high squareness ratio and excellent in Br and HcJ two characteristics, it is generally acknowledged that Br and HcJ is in the relation of balance (trade off).For this reason, require to establish the technology that can improve Br and HcJ two characteristic further.
As representing the index considering the magnetic properties of two characteristics of Br and HcJ, there will be a known the calculating formula (for example, referring to patent documentation 1) of Br (kG)+1/3HcJ (kOe).This value is got over Gao Zeyue and be can be described as and be suitable for the Sr ferrite sintered magnet that engine or generator etc. require the purposes of high magnetic properties.
As shown in above-mentioned patent documentation 1, it is effective that the composition of the main crystal grain of control formation Sr ferrite sintered magnet improves magnetic properties.But, even if the composition only controlling crystal grain is also difficult to the magnetic properties improving existing Sr ferrite sintered magnet significantly.As other means of the magnetic properties of raising Sr ferrite sintered magnet, consider to make to organize granular.As making the means organizing granular, consider the micronized means of pre-burning body making the raw material being used as Sr ferrite sintered magnet.Although as making the micronized method of pre-burning body can enumerate the method for mechanically fine pulverizing pre-burning body or extend the method for grinding time, if mechanically fine pulverizing like this, likely can occur that size-grade distribution becomes wide, causes manufacturing cost to increase and the problem such as yield rate reduction due to the loss etc. of power consumption increase or equipment.
For Sr ferrite sintered magnet, present majority is the anisotropic Sr ferrite sintered magnet making its crystalline orientation on c-axis direction.When manufacturing anisotropic Sr ferrite sintered magnet, be necessary fully to carry out Ferrite method reaction in pre-burning operation to improve the orientation that formed by the magnetic field of ferrite particle in the stage being made into body.Therefore, be carry out pre-burning under hot conditions more than 1250 DEG C in the past.The energy consumption cost of its result in pre-burning operation increase and ferrite particle also can grain growing to several μm ~ tens of μm.In order to improve Sr ferrite sintered magnet magnetic properties and will ferrite particle by such grain growing granular is very difficult to less than 1 μm equably.In addition, the cost that may be used for pulverizing pre-burning body also can increase.
There is coprecipitation method as the method obtaining trickle Sr ferrite powder and add the flux method etc. of fusing assistant, but need when manufacturing Sr ferrite powder in these processes to clean the loaded down with trivial details operation such as the operation of fusing assistant or the operation of modulation solution, operation becomes complicated and manufacturing cost increases.Under situation like this, require to establish and can manufacture with easy operation and with low the manufacture method that original making has the Sr ferrite sintered magnet of high magnetic properties.In addition, Sr ferrite sintered magnet majority is used to engine or generator.For this reason, in the use at engine or generator, Sr ferrite sintered magnet occurs damaged or peels off and damage engine or generator, thus also requires that Sr ferrite sintered magnet is excellent in reliability.
Prior art document
Patent documentation
Patent documentation 1: Japanese Unexamined Patent Publication 11-154604 publication
Summary of the invention
The technical problem solved is wanted in invention
The present invention is exactly the invention completed in view of the foregoing, and its object is to provides a kind of manufacture method of Sr ferrite sintered magnet and the manufacture method of sintered magnet Sr ferrite particle that can manufacture the Sr ferrite sintered magnet with excellent magnetic properties and high reliability with easy operation.
The means of technical solution problem
Inventors of the present invention are in order to carry out various discussion by the organizing granular of ferrite sintered magnet to the method manufactured containing the ferritic trickle comminuted powder of Sr.It found that by least one alkali metal compound in interpolation alkali metal chloride, organic acid salt, phosphoric acid salt, borate, zeolite thus can reduce significantly and generates the ferritic temperature of Sr.Like this, finding by using the Sr ferrite particle (pre-burning body) obtained with easy fired, magnetic properties and the reliability of Sr ferrite sintered magnet can be improved while reducing manufacturing cost, thus complete the present invention.
Namely, go up in one aspect, the invention provides a kind of manufacture method of sintered magnet Sr ferrite particle, it is characterized in that, possess: mixed processes, the mixing powder of iron cpd, the powder of strontium compound and the alkali metal compound containing alkali metal carry out modulating mixture; Pre-burning operation, described mixture is burnt till thus the median size obtaining primary particle is the Sr ferrite particle of 0.1 ~ 1.0 μm at 850 ~ 1100 DEG C, with the total relative to the powder of described iron cpd and the powder of described strontium compound in described mixed processes, the mode that alkali-metal total is scaled 0.03 ~ 1.05 quality % by alkalimetal oxide mixes described alkali metal compound, and described alkali metal compound is at least one in alkali metal chloride, organic acid salt, phosphoric acid salt, borate, zeolite.
By the manufacture method of the invention described above, can and Sr ferrite particle that magnetic properties high fully trickle with easy operation manufacture.It is high that such Sr ferrite particle can either maintain squareness ratio (Hk/HcJ), residual flux density (Br) and coercive force (HcJ) all characteristics, can also have the Sr ferrite sintered magnet of high reliability with easy operation manufacture.
The reason obtaining such effect is presumed to as described below.That is, in manufacture method of the present invention, the mixture containing specific alkali metal compound with specified amount is used as pre-burning body raw material.Thus, even if firing temperature during pre-burning is 850 ~ 1100 DEG C, also in pre-burning body, fully Sr ferrite can be generated.Like this because firing temperature during pre-burning is fully low, so the trickle and Sr ferrite particle that is excellence in coking property of appropriateness can be obtained.By using such Sr ferrite particle, crystal grain can be produced trickle and there is the Sr ferrite sintered magnet of excellent homogeneity.In addition, foreign matter (powder) fully can be suppressed to separate out on the surface of Sr ferrite sintered magnet, and Sr ferrite sintered magnet excellent in reliability can be produced.
As generating the ferritic reason of Sr with low firing temperature like this, think because the potassium be contained in mixture and/or sodium composition facilitate the ferritic generation of Sr.For this reason, the Sr ferrite particle obtained by manufacture method of the present invention has high magnetic properties.Further, the Sr ferrite particle obtained by manufacture method of the present invention because trickle and in shape and size, there is high uniformity, so excellent in coking property.Therefore, by the Sr obtained by manufacture method of the present invention ferrite particle is used in the manufacture of Sr ferrite sintered magnet, thus can be excellent and there is the Sr ferrite sintered magnet of high magnetic properties with easy operation fabrication reliability.
In addition, the specific alkali metal compound added in the mixed processes of manufacture method of the present invention is because generate liquid phase at low temperatures and promote reaction, so firing temperature when can reduce manufacture Sr ferrite particle (pre-burning body) further.Thus, the tissue of Sr ferrite sintered magnet by further granular, and can improve magnetic properties and reliability further.
Further, in existing flux method, also there is the situation using alkali metal chloride, but its manufacture method feature needs to use alkali metal chloride in a large number compared to method of the present invention, in addition, in subsequent handling, need matting.In the present invention, if being converted into alkalimetal oxide is 0.03 ~ 1.05 quality %, the addition of alkali metal chloride can be reduced significantly.In addition, due to by above-mentioned pre-burning operation, the alkali metal chloride volatilization added in above-mentioned mixed processes is made can to reduce the content of alkali metal chloride further, so can not undesirable condition be produced after sintering process afterwards.Therefore, matting required in existing flux method can not be needed.But for the purpose of prudent, also can add matting.
In manufacture method of the present invention, in above-mentioned pre-burning operation, preferably make the alkali metal chloride volatilization added in above-mentioned mixed processes, and the content preferably obtaining chlorine is the pre-burning body of below 1000ppm, more preferably the content of chlorine is below 500ppm, and the content being particularly preferably chlorine is below 200ppm.This is because the possibility of matting can not be needed like this in operation afterwards to improve.
In manufacture method of the present invention, the saturation magnetization of the Sr ferrite particle (pre-burning body) obtained in pre-burning operation is preferably more than 67emu/g.Such pre-burning body is because the ratio of Sr ferrite phase is fully high, so can produce the Sr ferrite sintered magnet with higher magnetic properties.
In manufacture method of the present invention, the specific surface area measured by BET method of the Sr ferrite particle (pre-burning body) obtained in pre-burning operation is such as 1.5 ~ 10m 2/ g, more preferably 2 ~ 10m 2/ g.Thus, plasticity improves and the homogeneity of the ferritic crystal grain of Sr in Sr ferrite sintered magnet improves further.Therefore, it is possible to improve magnetic properties and the reliability of Sr ferrite sintered magnet further.
Go up in yet another aspect, the invention provides Sr ferrite particle that a kind of use obtains by the manufacture method of above-mentioned Sr ferrite particle to manufacture the manufacture method of the Sr ferrite sintered magnet of Sr ferrite sintered magnet.
The manufacture method of Sr ferrite sintered magnet of the present invention can be the manufacture method possessing such as following operation: Crushing of Ultrafine operation, the Sr ferrite particle that case of wet attrition is obtained by above-mentioned manufacture method; Forming process, the Sr ferrite particle to case of wet attrition carries out wet forming and is made into body; Sintering circuit, burns till molding and obtains sintered magnet at 1000 ~ 1250 DEG C.
By the manufacture method of above-mentioned Sr ferrite sintered magnet, highly can maintain squareness ratio (Hk/HcJ), residual flux density (Br) and coercive force (HcJ) to generate heat all characteristics, the Sr ferrite sintered magnet of high reliability can be had again with easy operation manufacture.The reason obtaining such effect is speculated as follows.That is, in above-mentioned manufacture method, the Sr ferrite particle of the mixture manufacture with the K (potassium) containing specified amount and/or Na (sodium) is used as raw material.Thus, even if firing temperature is 850 ~ 1100 DEG C and also can generates Sr ferrite fully when pre-burning.Like this because pre-burning time firing temperature enough low, so can obtain trickle and there is the Sr ferrite particle of excellence in coking property of high uniformity in shape and size.By using such Sr ferrite particle, crystal grain can be produced trickle and there is the Sr ferrite sintered magnet of excellent homogeneity.In addition, at sintered magnet on the surface, the precipitation from the foreign matter of the alkali metal compound of surplus is adequately suppressed, and thus can be manufactured on the Sr ferrite sintered magnet of reliability aspect excellence.
The Sr ferrite sintered magnet manufactured by the present invention due to the ferritic crystal grain of Sr trickle and there is excellent homogeneity, so there is high magnetic properties and excellent in reliability.In the manufacture method of Sr ferrite sintered magnet of the present invention, different from coprecipitation method or flux method, need not numerous and diverse operation be carried out, Sr ferrite sintered magnet can be manufactured with easy operation.That is, the manufacture method of Sr ferrite sintered magnet of the present invention can be described as the manufacture method of the volume production being suitable for Sr ferrite sintered magnet.
In manufacture method of the present invention, in the above-mentioned crushed material that also can obtain pulverizing above-mentioned pre-burning body, again add specific alkalimetal oxide.In this case, also when the burning till of molding, the effect of the alkalimetal oxide when pre-burning can be expected.
In the Sr ferrite sintered magnet obtained by manufacture method of the present invention, the median size of Sr ferrite crystal grains is less than 0.6 μm, and particle diameter is that the ratio of the number benchmark of the crystal grain of more than 1.8 μm is preferably less than 1%.Like this, Sr ferrite sintered magnet that is trickle and that have a high uniformity is more excellent and can play consistently out high magnetic properties in reliability.
The Sr ferrite sintered magnet obtained by manufacture method of the present invention preferably meets following formula (1).Thereby, it is possible to make the Sr ferrite sintered magnet taking into account residual flux density (Br) and coercive force (HcJ) with higher level.In addition, the Sr ferrite sintered magnet obtained by manufacture method of the present invention preferably meets following formula (1) and squareness ratio is more than 80%.
Br+1/3HcJ≥5.5(1)
[in formula (1), Br and HcJ represents residual flux density (kG) and coercive force (kOe) respectively]
The Sr ferrite sintered magnet obtained by manufacture method of the present invention is preferably containing the alkali metal compound of at least one element with K and Na, and the total content of K and Na is converted into K respectively 2o and Na 2o is then the median size of the ferritic crystal grain of below 0.17 quality %, Sr is less than 0.6 μm, and particle diameter is the ratio of the number benchmark of the crystal grain of more than 1.8 μm is less than 1%.
The Sr ferrite sintered magnet obtained by manufacture method of the present invention because to contain the alkali metal compound of regulation with specified amount, so possess fully trickle and there is the tissue of high homogeneity.Such a Sr ferrite sintered magnet is excellent in all characteristics of squareness ratio (Hk/HcJ), residual flux density (Br) and coercive force (HcJ), and has high reliability.
The Sr ferrite sintered magnet obtained by manufacture method of the present invention is suitable as engine magnet or generator magnet uses, and has fully high efficiency.
Invention effect
A kind of manufacture method of Sr ferrite sintered magnet and the manufacture method of sintered magnet Sr ferrite particle can with low manufacturing cost manufacture by easy operation with the Sr ferrite sintered magnet of excellent magnetic properties and high reliability can be provided by the present invention.
Accompanying drawing explanation
Fig. 1 is the stereographic map of the preferred implementation schematically showing ferrite sintered magnet of the present invention.
Embodiment
Below as required with reference to accompanying drawing being preferred embodiment described in detail for of the present invention.
Fig. 1 is the stereographic map of the Sr ferrite sintered magnet schematically showing present embodiment.Anisotropic Sr ferrite sintered magnet 10 has becomes the bending shape of the mode of arc-shaped with end face, generally has the shape being called as arc section shape, C shape shape, watt shape shape or bowed shape.The magnet that Sr ferrite sintered magnet 10 is such as suitable as engine or generator uses.
In Sr ferrite sintered magnet 10, as main component, containing the ferritic crystal grain of Sr of M type with structure of hexagonal crystal.Sr ferrite is such as represented by following formula (2).
SrFe 12O 19(2)
In the Sr ferrite of above formula (2), its part of Fe in Sr and the B site in A site can by impurity or the element substitution added intentionally.In addition, the ratio in A site and B site can have some deviations.In this case, Sr ferrite such as can be represented by following general formula (3).
R xSr 1-x(Fe 12-yM y) zO 19(3)
In above formula (3), x and y is such as 0.1 ~ 0.5, z is 0.7 ~ 1.2.
M in general formula (3) is 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 (3) is selected from the element of more than a kind in La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium) and Sm (samarium).
The ratio of the Sr ferrite phase in Sr ferrite sintered magnet 10 is preferably more than 90%, and more preferably more than 95%, be more preferably more than 97%.Like this by reducing the ratio of the crystallization phases mutually different from Sr ferrite, magnetic properties can be improved further.Ferritic for Sr saturation magnetization theoretical value is being designated as σ by the ratio (%) of the Sr ferrite phase in Sr ferrite sintered magnet 10 t, and measured value is designated as σ stime, can with (σ s/ σ tthe calculating formula of) × 100 is tried to achieve.
In Sr ferrite sintered magnet 10, as minor component, containing the composition different from Sr ferrite.As minor component, the alkali metal compound of K (potassium) and/or the Na (sodium) had as constitution element can be enumerated.Such as Na can be enumerated as alkali metal compound 2o and K 2the oxide compound of O etc. or silicate glasses.K and Na is converted into K by the total content of the alkalimetal oxide in Sr ferrite sintered magnet 10 respectively 2o and Na 2o is below 0.17 quality %.
In addition, in the present embodiment, can also except K and/or Na or replace them and containing there is the alkali metal compound of Li and/or Rb as minor component in Sr ferrite sintered magnet 10.In Sr ferrite sintered magnet 10, the total content of alkalimetal oxide is converted into alkalimetal oxide and (is such as converted into Li when basic metal is Li and Ru 2o and Ru 2o) be then below 0.17 quality %.
If the alkali-metal total content such as Na and K is more than 0.17 quality %, have the tendency easily producing white powder on the surface of Sr ferrite sintered magnet 10.If produce powder on the surface of Sr ferrite sintered magnet 10, then the component of such as engine or generator and the cohesive force of Sr ferrite sintered magnet 10 reduce, thus have the possibility that Sr ferrite sintered magnet 10 peels off from the component of engine or generator.That is, the reliability of Sr ferrite sintered magnet 10 is damaged.
From the view point of the reliability improving Sr ferrite sintered magnet further, the upper limit of the alkali-metal total content such as Na and K in Sr ferrite sintered magnet 10 is converted into alkalimetal oxide respectively and is preferably 0.12 quality %, more preferably 0.1 quality %, is more preferably 0.08 quality %.From the view point of reducing manufacturing cost further, the lower limit of the alkali-metal total content such as Na and K is converted into Na respectively 2o and K 2the alkalimetal oxides such as O are preferably 0.01 quality %, more preferably 0.02 quality %, are more preferably 0.03 quality %.In order to reduce the operation that the alkali-metal total content such as Na and K need to carry out cleaning micro mist flour.Therefore, if make the total content of Na and K be less than above-mentioned lower value, then have the possibility that manufacturing cost rises.
In Sr ferrite sintered magnet 10, as minor component, arbitrary composition can also be contained except above-mentioned alkali metal compound.The oxide compound with at least one be selected from Si (silicon), Ca (calcium), Sr (strontium) and Ba (barium) and composite oxides can be enumerated as such composition.Such as SiO can be enumerated as oxide compound 2, CaO, SrO and BaO.
The content of the Si in Sr ferrite sintered magnet 10 is such as converted into SiO 2be 0.1 ~ 1.0 quality %.It is 10 ~ 13 quality % that the content of the Sr in Sr ferrite sintered magnet 10 is such as converted into SrO.Sr ferrite sintered magnet 10 also can contain Ba.It is 0.01 ~ 2.0 quality % that the content of the Ba in Sr ferrite sintered magnet 10 is such as converted into BaO.In Sr ferrite sintered magnet 10, the content of Ca is such as converted into CaO is 0.05 ~ 2 quality %.In ferrite sintered magnet 10, can also containing the impurity be contained in raw material or the inevitable composition coming from producing apparatus outside these compositions above-mentioned.Each oxide compound of Ti (titanium), Cr (chromium), Mn (manganese), Mo (molybdenum), V (vanadium) and Al (aluminium) etc. such as can be enumerated as such composition.
Minor component is mainly contained in the crystal boundary of the ferritic crystal grain of Sr in Sr ferrite sintered magnet 10.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)
The median size of the ferritic crystal grain of the Sr in Sr ferrite sintered magnet 10 is less than 0.6 μm, is preferably less than 0.59 μm.If the median size of Sr ferrite crystal grains is more than 0.6 μm, have the tendency being difficult to obtain fully excellent magnetic properties.On the other hand, the Sr ferrite sintered magnet that the median size of the ferritic crystal grain of Sr is less than 0.3 μm has the tendency being difficult to volume production.
The deviation being preferably contained in the particle diameter of the ferritic crystal grain of Sr in Sr ferrite sintered magnet 10 is little.Like this, if the homogeneity of the ferritic crystal grain of Sr improves, high magnetic properties can either be improved further and can improve reliability again.From such a viewpoint, less than 1% is preferably relative to the ratio of the number benchmark of the ferritic crystal grain of Sr that the particle diameter of the Sr ferrite crystal grains entirety in Sr ferrite sintered magnet 10 is more than 1.8 μm, more preferably less than 0.8%, be more preferably less than 0.66%.
The particle diameter of the Sr ferrite crystal grains of Sr ferrite sintered magnet 10 can measure according to following order.The sample sheet scaled off from Sr ferrite sintered magnet is observed with TEM.Or mirror ultrafinish carried out in the cross section of this sample and carries out corrosion treatment with acid such as fluoric acids, then observing with SEM etc.In the observation image of SEM or TEM comprising hundreds of crystal grain, after by the clear-cut of crystal grain, just carry out image procossing etc., measure the size distribution in c face." particle diameter " in this specification sheets refers to the major diameter (the axial diameter of a) on a face.This major diameter is tried to achieve as the long limit being external in each crystal grain " area becomes minimum rectangle ".In addition, the long limit of " area becomes minimum rectangle " is " aspect ratio " relative to the ratio of minor face.In addition, also can substitute the corrosion undertaken by acid and be corroded by heating sample, namely carry out so-called thermal etching.
The mean value of the number benchmark of the particle diameter of crystal grain is calculated from the size distribution of the number benchmark be measured to.In addition, standard deviation is calculated from the size distribution measured and mean value.In this manual using these median sizes as the ferritic crystal grain of Sr and standard deviation.From the view point of producing the Sr ferrite sintered magnet 10 with fully high magnetic properties, the number mean value (average aspect ratio) of the aspect ratio of each crystal grain is preferably about 1.7.
Sr ferrite sintered magnet 10 preferably meets following formula (1).The Sr ferrite sintered magnet of present embodiment, because Sr ferrite crystal grains is enough trickle, meets the such high magnetic properties of formula (1) so have.The Sr ferrite sintered magnet meeting this formula (1) has enough excellent magnetic properties.One just can be provided to have more high efficiency engine and generator by such Sr ferrite sintered magnet.In addition, preferably Sr ferrite sintered magnet 10 meets following formula (4) further.Like this, a kind of magnetic properties of Sr ferrite sintered magnet 10 can be provided to become higher and have more high efficiency engine and generator.
Br+1/3HcJ≥5.5 (1)
Br+1/3HcJ≥5.6 (4)
In above-mentioned formula (1) and (4), Br and HcJ represents residual flux density (kG) and coercive force (kOe) respectively.
The squareness ratio of Sr ferrite sintered magnet 10 is preferably more than 80%, and more preferably more than 90%.By having magnetic properties excellent like this, engine or generator can be used in more aptly.
Sr ferrite sintered magnet 10 such as can use as the magnet of the engine for automobile such as oil fuel pump use, power windows use, ABS (ABS (Anti-lock Braking System)) use, fan use, wiper use, power steering use, active quidance suspension use, starting engine use, door lock use, electric reverse light microscopic use.In addition, can use as floppy disk (FDD) the axle magnet that, video tape recorder (VTR) capstan winch, VTR rotating head, VTR reel, VTR loads the OA/AV machine engines such as the capstan winch such as use, VTR camera capstan winch use, VTR pick up camera rotating head use, VTR pick up 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.Further, can also to drive with, freezer compressor, power tool as compressor of air conditioner and drive the magnet of the home appliance engines such as use, electric toothbrush use to use with, drying machine fan, shaver.Further, the magnet of the FA machine engines such as use, machine operation belt-driven use can also be driven to use as manipulator shaft, joint drive use, main use, the machine operation platform of driving of robot.
Sr ferrite sintered magnet 10 is bonded in the component of above-mentioned engine and is arranged in engine.There is the Sr ferrite sintered magnet 10 of excellent magnetic property because the generation of crackle fully can be suppressed, so can be bonding with engine component fully securely.This makes it possible to fully suppress Sr ferrite sintered magnet 10 to be peeled off from the component of engine.Therefore, the various engines possessing Sr ferrite sintered magnet 10 have both efficient and high reliability.
The purposes of Sr ferrite sintered magnet 10 is not limited to engine, such as, can also use as the component of electric organ, speaker headset magnet, magnetron, Magnetic resonance imaging (MRI) field generator for magnetic, CD-ROM clamper, distribution transducer, ABS sensor, fuel fuel liquid level sensor, magnetic latch (magnet latch) or shield retaining etc.In addition, can also use as the target (bead) when forming magnetic recording media magnetospheric with vapour deposition method or sputtering method etc.Sr ferrite sintered magnet 10 can be manufactured by following illustrated manufacture method.
It is below the preferred implementation of the manufacture method that Sr ferrite sintered magnet of the present invention is described.The manufacture method of the Sr ferrite sintered magnet of present embodiment possesses: mixed processes, and the mixing powder of iron cpd, the powder of strontium compound and the alkali metal compound containing alkali metal carry out modulating mixture; Pre-burning operation, burns till this mixture thus obtains comprising the ferritic pre-burning body of the Sr with structure of hexagonal crystal at 850 ~ 1100 DEG C; Pulverizing process, pulverizes pre-burning body and obtains comminuted powder; Sintering circuit, burns till and in magnetic field, to make comminuted powder be shaped and the molding that obtains thus obtain Sr ferrite sintered magnet at 1000 ~ 1200 DEG C.
But the manufacture method of the Sr ferrite particle of present embodiment has above-mentioned mixed processes, above-mentioned pre-burning operation.In addition, according to circumstances also above-mentioned pulverizing process can be had.Like this due in the manufacture method of Sr ferrite sintered magnet and the manufacture method of Sr ferrite particle, mixed processes, pre-burning operation and pulverizing process can be common, concentrate explanation so following.
Mixed processes is the operation of the mixture of modulation pre-burning.In mixed processes, first weigh starting raw material and coordinate with regulation ratio, mix 1 ~ 20 hours with wet grinding machine or with ball mill etc. and carry out pulverization process.The powder of iron cpd, the powder of strontium compound and the alkali metal compound containing alkali metal can be enumerated as starting raw material.Alkali metal compound both can be Powdered also can be aqueous.
Oxide compound can be used or by burning till the compounds such as carbonate, oxyhydroxide or the nitrate that can become oxide compound as iron cpd and strontium compound.Such as SrCO can be enumerated as such compound 3and Fe 2o 3deng.In addition, La (OH) can also be added except these compositions 3and Co 3o 4deng.
Such as potassium, sodium, rubidium and lithium etc. can be enumerated as alkali metal.In addition, at least one in alkali metal chloride, organic acid salt, phosphoric acid salt, borate, zeolite such as can be enumerated as the alkali metal compound containing alkali metal.
Sodium-chlor, Repone K, lithium chloride, rubidium chloride etc. can be enumerated as alkali metal chloride.In addition, oxalate, acetate, soap etc. can be enumerated as organic acid salt.These organic acid salts also can expect the function as the tensio-active agent in shaping in magnetic field described later, and can expect the raising of characteristic.
In addition, sodium phosphate, potassiumphosphate etc. can be enumerated as phosphoric acid salt.Further, sodium metaborate, sodium tetraborate etc. can be enumerated as borate.
In mixed processes, the total of alkali metal compound be converted into alkalimetal oxide and become the amount mixed alkali metal compound of 0.03 ~ 1.05 quality % relative to the total of iron cpd powder and strontium compound powder.From the view point of the firing temperature be reduced in further when obtaining pre-burning body and Sr ferrite sintered magnet, the lower value of the numerical range of above-mentioned total is preferably 0.1 quality %.From the view point of the magnetic properties improving Sr ferrite sintered magnet further, the higher limit of the numerical range of above-mentioned total is preferably 0.8 quality %, is more preferably 0.6 quality %.
In mixed processes, except above-mentioned alkali metal compound, other minor components can also be added.SiO can be enumerated as minor component described above 2and CaCO 3deng.The median size of starting raw material without particular limitation of, can be such as 0.1 ~ 2.0 μm.The specific surface area measured by BET method of starting raw material is preferably 2m 2/ more than g.Thus, trickleer comminuted powder can be obtained.The mixture modulated in mixed processes both can be Powdered also can be the slurry that mixed powder is scattered in solvent.
Pre-burning operation is the operation of the mixture that pre-burning obtains in mixed processes.Pre-burning can be carried out in the oxidation atmosphere gases such as air.Firing temperature in pre-burning operation is 850 ~ 1100 DEG C, is preferably 900 ~ 1000 DEG C.Burn-in time under calcined temperature is preferably 0.5 ~ 5 hour, more preferably 1 ~ 3 hour.The ferritic content of Sr in the pre-burning body (Sr ferrite particle) obtained by pre-burning is preferably more than 70 quality %, is more preferably more than 90 quality %.In the manufacture method of present embodiment, because with the addition of alkali metal compound with specified amount before pre-burning operation, even so above-mentioned calcined temperature also fully can generate the Sr ferrite with structure of hexagonal crystal.
The saturation magnetization of pre-burning body and Sr ferrite particle is preferably more than 67emu/g, more preferably more than 70emu/g, is more preferably more than 70.5emu/g.Like this by generating the pre-burning body (Sr ferrite particle) with high saturation, the Sr ferrite sintered magnet with higher magnetic properties can be obtained.Saturation magnetization in this specification sheets can measure with commercially available vibrating example magnetometer (VSM).
From the view point of the abundant granular of tissue of the Sr ferrite sintered magnet making finally to obtain, the specific surface area measured by BET method of the pre-burning body obtained in pre-burning operation (Sr ferrite particle) is 2m 2/ more than g, more preferably 2.5m 2/ more than g, is more preferably 2.7m 2/ more than g.In addition, from the view point of plasticity when being made into body well, the specific surface area obtained by BET method of pre-burning body is preferably 15m 2/ below g, more preferably 10m 2/ below g, is more preferably 7m 2/ below g.In addition, the specific surface area in this specification sheets can measure with commercially available BET specific surface area determinator (Mountech Inc., trade(brand)name: HM Model-1210).
Well make again the tissue of the Sr ferrite sintered magnet finally obtained fully trickle from the view point of making coking property, the median size of the primary particle of the Sr ferrite particle obtained in pre-burning operation is less than 1.0 μm, be preferably less than 0.8 μm, more preferably less than 0.7 μm, be more preferably less than 0.6 μm.In addition, from the view point of making, molding when being made into body is good, and the median size of the primary particle of Sr ferrite particle is more than 0.1 μm, is preferably more than 0.2 μm, is more preferably more than 0.3 μm.In addition, the median size of the primary particle in this specification sheets can use the observation image obtained by TEM or SEM to try to achieve.Specifically, in the observation image of SEM or TEM comprising hundreds of primary particles, carry out image procossing and measure size distribution.The mean value of the number benchmark of the particle diameter of primary particle is calculated from the size distribution of the number benchmark be measured to.Using the mean value that is measured to the like this median size as the primary particle of Sr ferrite particle.
In addition, the alkali metal compound added in the mixed processes of present embodiment promotes reaction owing to generating liquid phase at low temperatures, so can be reduced in firing temperature when manufacturing pre-burning body further.Thus, the tissue of Sr ferrite sintered magnet by further granular, and can improve magnetic properties and reliability further.
In addition, in existing flux method, also there is the situation using alkali metal chloride, but its manufacture method feature needs to use alkali metal chloride in a large number compared to method of the present invention, in addition, in subsequent handling, need matting.In the present embodiment, if be when employing alkali metal chloride, if be converted into alkalimetal oxide and become 0.03 ~ 1.05 quality %, then can reduce the addition of alkali metal chloride significantly.
In addition, in pre-burning operation, due to the content of alkali metal chloride can be reduced further, so can not produce undesirable condition after sintering process afterwards by making the alkali metal chloride added in mixed processes volatilize.Therefore, matting required in existing flux method can not be needed.But for the purpose of prudent, also can add matting.
In the manufacture method of present embodiment, when employing alkali metal chloride, in pre-burning operation, preferably make the alkali metal chloride volatilization added in above-mentioned mixed processes, obtaining cl content is below 1000ppm, more preferably below 500ppm, is particularly preferably the pre-burning body (Sr ferrite particle) of below 200ppm.This is because the possibility of matting can not be needed like this in operation afterwards to uprise.
In addition, in the present embodiment, when employing the specific alkali metal compound beyond alkali metal chloride, the content easily obtaining chlorine is below 1000ppm, be more preferably below 500ppm, be particularly preferably the pre-burning body (Sr ferrite particle) of below 200ppm.
In pulverizing process, pulverize and the pre-burning body (Sr ferrite particle) that pre-burning obtains is carried out to the mixture obtained by mixed processes, and modulate comminuted powder.Pulverizing can be carried out with a stage, and two stages that also can be divided into coarse reduction operation and Crushing of Ultrafine operation carry out.First pre-burning body (Sr ferrite particle) normally particulate state or bulk, therefore preferably carry out coarse reduction operation.In coarse reduction operation, use vibration rod mill and pulverize with dry type, modulation meal flour.The meal flour wet grinding machine of such as above-mentioned modulation, ball mill or jet mill etc. are pulverized by wet type and obtains micro mist flour.Grinding time is such as 30 minutes ~ 10 hours when using wet grinding machine, is 5 ~ 50 hours when using ball mill.These times preferably appropriately adjust according to breaking method.In the manufacture method of present embodiment, owing to being carry out pre-burning in the temperature lower than prior art, so the ferritic primary particle of Sr in pre-burning body is trickleer than existing.Therefore, in pulverizing process (particularly Crushing of Ultrafine operation), mainly primary particle aggegation and the offspring formed is broken up into trickle primary particle.
Also the SiO as minor component can be added in pulverizing process (coarse reduction operation and/or Crushing of Ultrafine operation) 2, CaCO 3, SrCO 3and BaCO 3deng powder.Can coking property be improved by adding such a minor component and can magnetic properties be improved.In addition, these minor components because can flow out together with the solvent of slurry, coordinate more than the content of target so preferred when forming with wet type in ferrite sintered magnet.
In order to improve the magnetic aligning degree of ferrite sintered magnet, outside above-mentioned minor component, preferably in Crushing of Ultrafine operation, add polyvalent alcohol.The addition of polyvalent alcohol is 0.05 ~ 5.0 quality % relative to interpolation object, is preferably 0.1 ~ 3.0 quality %, is more preferably 0.3 ~ 2.0 quality %.In addition, the polyvalent alcohol added is thermal decomposited removing in sintering circuit.
Fully trickle from the view point of the tissue of the Sr ferrite sintered magnet making finally to obtain, the specific surface area obtained by BET method of the comminuted powder obtained in pulverizing process and be preferably 6m 2/ more than g, is more preferably 8m 2/ more than g.In addition, from the view point of making, plasticity when being made into body is good, and the specific surface area measured by BET method of comminuted powder is preferably 12m 2/ below g, is more preferably 10m 2/ below g.There is the comminuted powder of such specific surface area because fully trickle and excellent in treatability and plasticity, so not only maintain the simplicity of operation but also make the further granular of the tissue of Sr ferrite sintered magnet, and the magnetic properties of Sr ferrite sintered magnet can be improved further.
Forming process is that the comminuted powder that is shaped in magnetic field is made into the operation of body.In forming process, first carry out being formed in magnetic field the comminuted powder that obtains in pulverizing process and be made in the magnetic field of body and be shaped.Be shaped in magnetic field and can carry out with any one method of dry pressing or wet forming, from the view point of the orientation degree improving magnetic, be preferably wet forming.When carrying out wet forming, carry out coordinating comminuted powder and dispersion medium and the case of wet attrition of carrying out pulverizing to modulate slurry, use this slurry to be made into body.The concentrated of slurry can be undertaken by centrifugation or press filtration etc.
The content of the solids component in slurry is preferably 30 ~ 85 quality %.Dispersion medium as slurry can use water or non-aqueous solvent.The tensio-active agents such as gluconic acid, gluconate or Sorbitol Powder can also be added in addition to water in the slurry.Use such slurry to carry out being shaped in magnetic field, thus produce molding.Compacting pressure is such as 0.1 ~ 0.5 ton/cm 2, the magnetic field applied is such as 5 ~ 15kOe.
Then, burn till molding and make sintered compact.Sintering circuit is operation molding being fired at 1000 ~ 1250 DEG C Sr ferrite sintered magnet.Burn till normally to wait in oxidizing atmosphere in atmosphere and carry out.Firing temperature is 1000 ~ 1250 DEG C, is preferably 1100 ~ 1200 DEG C.Firing time under firing temperature is preferably 0.5 ~ 3 hour.Sintered compact and Sr ferrite sintered magnet 10 can be obtained by above operation.
In the manufacture method of the Sr ferrite sintered magnet of present embodiment, due to the trickle pre-burning body (Sr ferrite particle) that the median size employing primary particle is little, so can obtain organizing trickle and that homogeneity is high Sr ferrite sintered magnet.Such Sr ferrite sintered magnet is all excellent and have high reliability in all characteristics of squareness ratio (Hk/HcJ), residual flux density (Br) and coercive force (HcJ).The magnet that this Sr ferrite sintered magnet is suitable as engine use or generator uses.
Be explained above the preferred embodiment of the present invention, but the present invention is not limited to above-mentioned embodiment.Such as, the shape of Sr ferrite sintered magnet is not limited to the shape of Fig. 1, can be suitable for being altered to the shape being suitable for above-mentioned various uses.
In addition, in the above-described embodiment, the above-mentioned specific alkali metal compound being preferably about 0 ~ 0.15 quality % is again added in the crushed material lotion that can obtain to pulverizing pre-burning body.In this case, the effect of alkali metal compound during pre-burning also can be expected when the burning till of molding.
Embodiment
Further describe content of the present invention with reference to embodiment and comparative example, but the present invention is not limited to following embodiment.
[modulation of Sr ferrite particle and evaluation]
(embodiment 1, comparative example 1)
Prepare following starting raw material.In addition, specific surface area is the value measured by BET method.
Fe 2o 3powder (specific surface area: 4.4m 2/ g) 220g
SrCO 3powder (specific surface area: 5.0m 2/ g) 35.23g
Wet-type ball mill is used to pulverize above-mentioned Fe 2o 3powder and SrCO 3powder 16 hours is also mixed to get slurry.The powder of the alkali metal compound shown in table 1 is added in this slurry.Addition is now relative to Fe 2o 3powder and SrCO 3the total quality of powder is as shown in table 1, and (the Na addition in table is for being converted into Na 2the value of O).
Afterwards, carry out the spraying dry of slurry, obtain the granular mixture that particle diameter is about 10 μm, afterwards, burn till this mixture 1 hour with the firing temperature (T1) shown in table 1 in atmosphere, obtain granular Sr ferrite particle.Saturation magnetization (the σ of obtained Sr ferrite powder is measured with commercially available vibrating example magnetometer (VSM) s: emu/g).Measuring method as described below.The magnetization (σ) in magnetic field (Hex) from 16kOe to 19kOe is measured by VSM (Tohei Ind Co., Ltd.'s system, trade(brand)name: VSM-3 type).Then, by approach to saturation rule to calculate Hex infinitely great time the value (σ of σ s).That is, by σ to 1/Hex 2mapping is then similar to straight line, and tries to achieve and be extrapolated to 1/Hex 2value when → 0.Relation conefficient is now more than 99%.The result of carrying out like this measuring is shown in Table 1.
(comparative example)
Except not adding the powder of alkali metal compound, all the other are all to modulate Sr ferrite particle similarly to Example 1.Saturation magnetization (the σ of obtained Sr ferrite particle is tried to achieve with method similarly to Example 1 s).The results are shown in table 1.
[table 1]
Na addition is for being converted into Na 2quality ratio during O
Be determined at the median size of the primary particle of the Sr ferrite particle obtained in each embodiment shown in table 1 and comparative example.Its result is that median size is all 0.2 ~ 1 μm when firing temperature T1 is below 1100 DEG C.In contrast, median size has exceeded 1 μm when firing temperature T1 is 1200 DEG C.
In embodiment 1, the Sr ferrite particle with the high saturation of more than 67emu/g can obtain in large firing temperature (T1) scope.This is equivalent to more than 93% of the ferritic theoretical value 71.5emu/g of Sr, and represents that Ferrite method reaction is carried out quite a lot of.
Use the Sr ferrite particle of each embodiment and according to the sequentially built same with embodiment 2 described later Sr ferrite sintered magnet (firing temperature T2=1160 DEG C).Its result has good outward appearance in all embodiments, and can obtain the Sr ferrite sintered magnet that Br+1/3HcJ is more than 5.5.
[making of Sr ferrite sintered magnet]
(embodiment 2-3)
Prepare following starting raw material.In addition, specific surface area is the value measured by BET method.
Fe 2o 3powder (specific surface area: 4.4m 2/ g) 220g
SrCO 3powder (specific surface area: 5.0m 2/ g) 35.23g
Wet-type ball mill is used to pulverize above-mentioned Fe 2o 3powder and SrCO 3powder 16 hours while be mixed to get slurry.By sodium metaborate (NaBO 2) add in this slurry.Addition is now converted into Na 2o is relative to Fe 2o 3powder and SrCO 3the total quality of powder is 0.42 quality %.Afterwards, the spraying dry carrying out slurry obtains after particle diameter is about the granular mixture of 10 μm, burns till 1 hour at 950 DEG C in atmosphere, obtain granular pre-burning body (Sr ferrite particle) to by mixture.
The magnetic properties of the pre-burning body (Sr ferrite particle) using commercially available vibrating example magnetometer (VSM) to measure to obtain.Measuring method is as described below.By the magnetization (σ) in the magnetic field (Hex) of VSM (Tohei Ind Co., Ltd. manufactures, trade(brand)name: VSM-3 type) mensuration from 16kOe to 19kOe.Then, by the rule that approaches to saturation to calculate the value (σ of the infinitely-great σ of Hex s).That is, by σ relative to 1/Hex 2make straight line to be similar to, and try to achieve and be extrapolated to 1/Hex 2value when → 0.Relation conefficient is now more than 99%.The result measured is saturation magnetization (σ s) be 69.6emu/g, coercive force (HcJ) is 3.354kOe.In addition, the specific surface of pre-burning body (Sr ferrite particle) is 2.7m 2/ g, the median size of primary particle is 0.4 μm.Sorbitol Powder 1 quality %, SiO is added relative to this pre-burning body of 130g (Sr ferrite particle) 20.4 quality %, CaCO 3after 0.9 quality %, carry out case of wet attrition with ball mill and obtain slurry in 16 hours.This de-watering of slurries is obtained comminuted powder.The specific surface area measured by BET method of the comminuted powder obtained is 8.5m 2/ g.
Observe the comminuted powder with ball mill case of wet attrition pre-burning body (Sr ferrite particle) with electron micrograph, found that the comminuted powder of modulation in embodiment 1 ~ 2 does not comprise the coarse particle that particle diameter is more than 1 μm.In addition, particle diameter is that the ratio of the ultramicron of less than 0.1 μm also diminishes.In addition, measured the content of the chlorine in embodiment 1 ~ 2 in pre-burning body (Sr ferrite particle) by fluorescent X-ray semi-quantitative analysis method, result is all below 200ppm.
In addition, by except not adding sodium metaborate and controlled by the firing temperature when obtained pre-burning body at 1250 DEG C and will carry out case of wet attrition with ball mill and be set to except 23 hours before pre-burning, other comminuted powder modulated by existing manufacture method all modulated by the method identical with embodiment 2 ~ 3 is also observed with electron micrograph.In its results verification embodiment 1 ~ 2, the comminuted powder of modulation is trickleer than existing comminuted powder and size-grade distribution is also narrower, and excellent in homogeneity.
In embodiment 2 ~ 3, adjust the concentration of the slurry containing comminuted powder as solids component.The slurry that have adjusted solid component concentration is imported in wet type magnetic forming machine, form in the externally-applied magnetic field of 12kOe and obtain the molding of cylindrical shape.At 1160 ~ 1200 DEG C, 1 hour is burnt till to this molding in atmosphere, thus obtain the ferrite sintered magnet of embodiment 2 ~ 3.The firing temperature of each embodiment is as shown in table 1.
(comparative example 2 ~ 3)
Except not adding except sodium metaborate to slurry, all the other have all made the ferrite sintered magnet of comparative example 2 ~ 3 equally with embodiment 2 ~ 3.In addition, the saturation magnetization (σ of the pre-burning body modulated in comparative example 2 ~ 3 s) be 65.5emu/g, coercive force (HcJ) is 3.09kOe, and the specific surface area measured by BET method is 3.1m 2/ g.In addition, the specific surface area measured by BET method of the comminuted powder obtained by case of wet attrition is 10.2m 2/ g.
[evaluation of Sr ferrite sintered magnet]
The evaluation > of < magnetic properties
After the top and bottom of the Sr ferrite sintered magnet by each embodiment and each comparative example process, use the B-H tracer of maximum applying magnetic field 25kOe to measure magnetic properties.In mensuration, try to achieve Br, HcJ, bHc and (BH) max, and measure Br become 90% time external magnetic field strength (Hk), try to achieve squareness ratio [Hk/HcJ (%)] according to this measurement result.In addition, the value of Br+1/3HcJ is calculated.These results are shown in Table 1.Its squareness ratio of Sr ferrite sintered magnet of embodiment 2 ~ 3 and Br+1/3HcJ are both high numerical value.In contrast, its squareness ratio of Sr ferrite sintered magnet of comparative example 2 ~ 3 is low.This is considered to result from owing to fully not generating Sr ferrite in pre-burning body (Sr ferrite particle) in comparative example 2 ~ 3, so there is the growth of abnormal grain thus the tissue of sintered compact becomes uneven in sintering circuit.
[table 2]
< compositional analysis >
The composition of the ferrite sintered magnet of embodiment 3 is measured with fluorescent X-ray analysis instrument.During using ferrite sintered magnet entirety as benchmark, the content of Fe, Sr, Na, Si is being converted into Fe respectively 2o 3, SrO, Na 2o, SiO 2time be 88.5 quality %, 10.3 quality %, 0.044 quality % and 0.324 quality %.In addition, K is not detected.This ferrite sintered magnet, except Fe, Sr, Na, Si, contains the trace ingredients from raw material impurity.Even if the content of above-mentioned each oxide compound is also be converted into the value of trying to achieve after oxide compound calculates to these impurities.
The analysis > of < fine structure
Sheet is carried out in the cross section (a face) of the Sr ferrite sintered magnet of embodiment 3, and observes with TEM.In this observation image, after the clear-cut making Sr ferrite crystal grains, measured the size-grade distribution of the number benchmark of Sr ferrite crystal grains by image procossing.
Try to achieve the histogram of the size-grade distribution representing the Sr ferrite crystal grains be contained in the ferrite sintered magnet of embodiment 3, try to achieve median size and the standard deviation of the number benchmark of Sr ferrite crystal grains according to the data of this size-grade distribution.In addition, measure the aspect ratio of each crystal grain, and try to achieve mean value and the standard deviation of the aspect ratio of number benchmark.These results are shown in Table 3.
In embodiment 3, particle diameter is the crystal grain of more than 1.8 μm is less than 1% relative to the ratio of the number benchmark of Sr ferrite crystal grains entirety.That is, the homogeneity confirming the grain-size in Sr ferrite sintered magnet is fully high.Thus, confirm by use contain the alkali metal compounds such as sodium metaborate and the pre-burning body obtained with the easy fired of 950 DEG C with specified amount, thus just can obtain there is high squareness ratio and the value of Br+1/3HcJ be more than 5.60 Sr ferrite sintered magnet.
[table 3]
[making of Sr ferrite sintered magnet and evaluation]
(embodiment 11 ~ 14)
Use wet-type ball mill while by Fe used in example 2 2o 3powder and SrCO 3powder carries out the pulverizing of 18 hours while carry out mixing thus obtaining slurry.Sodium metaborate is added in this slurry.Relative to Fe 2o 3powder and SrCO 3the total quality of powder, addition is now converted into Na 2o is 0.38 quality %.Afterwards, the spraying dry carrying out slurry obtains after particle diameter is approximately the particle of 10 μm, carries out burning till for 1 hour in atmosphere, thus obtain granular pre-burning body (Sr ferrite particle) at 950 DEG C to this particle.
Saturation magnetization (the σ of the pre-burning body obtained s) be 70.3emu/g, coercive force (HcJ) is 3.79kOe.In addition, the specific surface area of this pre-burning body (Sr ferrite particle) is 2.7m 2/ g, the median size of primary particle is 0.5 μm.Sorbitol Powder 1 quality %, SiO is being added relative to this pre-burning body of 130g 20.4 quality % and CaCO 3after 0.9 quality %, carry out case of wet attrition with ball mill and modulate slurry.Now, the time of case of wet attrition is adjusted to 10 ~ 28 hours, and modulates the micro mist flour of the different embodiment of specific surface area 11 ~ 14.The specific surface area being undertaken measuring by BET method of each micro mist flour obtained is as shown in table 4.
The slurry that have adjusted solid component concentration is imported in wet type magnetic forming machine, in the externally-applied magnetic field of 12kOe, form the molding obtaining cylindrical shape.This molding is burnt till 1 hour in atmosphere at 1160 ~ 1180 DEG C, obtains the Sr ferrite sintered magnet of embodiment 11 ~ 14.The firing temperature of each embodiment is as shown in table 4.The magnetic properties of the Sr ferrite sintered magnet of embodiment 11 ~ 14 is measured equally with embodiment 1.Show the result in table 4.
(comparative example 11 ~ 13)
Except firing temperature when obtaining pre-burning body (Sr ferrite particle) is set to 1200 DEG C, all the other all modulate pre-burning body (Sr ferrite particle) equally with embodiment 11.Sorbitol Powder 1 quality %, SiO is being with the addition of relative to this pre-burning body of 130g (Sr ferrite particle) 20.3 quality % and CaCO 3after 0.6 quality %, carry out using the coarse reduction of dry type vibratory mill and modulating slurry by the case of wet attrition of ball mill.Between 17 ~ 35 hours, adjust the time of case of wet attrition, thus modulate the comminuted powder of the different comparative example of specific surface area 11 ~ 13.The specific surface area measured by BET method of each comminuted powder obtained is as shown in table 4.
The slurry having carried out solid component concentration adjustment is imported in wet type magnetic forming machine, is shaped in the applying magnetic field of 12kOe and obtains the molding of cylindrical shape.This molding is burnt till 1 hour in atmosphere at 1200 DEG C, obtains the Sr ferrite sintered magnet of comparative example 11 ~ 13.The firing temperature of the molding of each comparative example is as shown in table 4.The magnetic properties of the Sr ferrite sintered magnet of each comparative example is measured equally with embodiment 1.Show the result in table 4.The Sr ferrite sintered magnet of embodiment 11 ~ 14 had both maintained high squareness ratio [Hk/HcJ (%)], and the value of Br+1/3HcJ also becomes higher than comparative example.
[table 4]
In each Sr ferrite sintered magnet of embodiment 11 ~ 14, containing being converted into Na 2o is the Na of 0.04 quality %.In addition, the particle diameter of the ferritic crystal grain of Sr in each Sr ferrite sintered magnet is 0.3 ~ 1.9 μm.
[making of Sr ferrite sintered magnet and evaluation]
(embodiment 21 ~ 24)
Use wet-type ball mill while pulverize the Fe used in embodiment 1 2o 3powder and SrCO 3powder 16 hours, while mixed, obtains slurry.Sodium metaborate is added in this slurry.Relative to Fe 2o 3powder and SrCO 3the total quality of powder, addition is now converted into Na 2o is then 0.38 quality %.Afterwards, carry out the spraying dry of slurry and after obtaining powder, at 900 DEG C, this mixture burnt till 1 hour in atmosphere, obtain granular pre-burning body (Sr ferrite particle).
Saturation magnetization (the σ of the pre-burning body (Sr ferrite particle) obtained s) be 69.2emu/g, coercive force (HcJ) is 3.32kOe.In addition, the specific surface area measured by BET method of pre-burning body (Sr ferrite particle) is 2.7m 2/ g, the median size of primary particle is 0.4 μm.Sorbitol Powder 1 quality %, SiO is added relative to this pre-burning body 130g 20.4 quality %, CaCO 3after 0.9 quality %, the case of wet attrition of carrying out with ball mill 22 hours obtains slurry.The specific surface area measured by BET method of the comminuted powder obtained is 10.2m 2/ g.
Sodium metaborate is added in slurry and modulate 4 kinds of different slurries of Na content.The addition of sodium metaborate is now, the sodium metaborate content in molding is converted into Na 2o becomes the quality % shown in table 4.The slurry that the concentration of carrying out solids component adjusts is imported in wet type magnetic forming machine, in the externally-applied magnetic field of 12kOe, forms the molding obtaining cylindrical shape.At 1160 ~ 1170 DEG C, burn till this molding 1 hour in atmosphere, obtain the Sr ferrite sintered magnet of embodiment 21 ~ 24.The firing temperature of the molding in each embodiment 21 ~ 24 is as shown in table 5.Similarly to Example 1, the magnetic properties of the Sr ferrite sintered magnet of embodiment 21 ~ 24 is determined.Show the result in table 5.
The composition of the Sr ferrite sintered magnet of each embodiment is measured with x-ray fluorescence analysis.Overall for the Sr ferrite sintered magnet content as Na, Si, Ca, Fe, Sr of benchmark is converted into Na respectively 2o, SiO 2, CaO, Fe 2o 3, SrO being shown in Table 6 (unit is quality %).Further, K is not detected.This Sr ferrite sintered magnet except above-mentioned element, containing the trace ingredients coming from raw material impurity.Also the content of above-mentioned each oxide compound is calculated after oxide compound is converted into these impurities.
[table 5]
[table 6]
Na 2O SiO 2 CaO Fe 2O 3 SrO
Embodiment 21 0.042 0.481 0.520 88.1 10.3
Embodiment 22 0.055 0.476 0.522 88.1 10.4
Embodiment 23 0.102 0.475 0.531 88.0 10.3
Embodiment 24 0.158 0.466 0.533 88.0 10.3
[making of ferrite sintered magnet]
(embodiment 31 ~ 33)
Prepare following starting raw material.
Fe 2o 3powder (specific surface area: 4.4m 2/ g) 220g
SrCO 3powder (specific surface area: 5.0m 2/ g) 35.23g
Use wet-type ball mill while pulverize above-mentioned Fe 2o 3powder and SrCO 3powder 16 hours, while mixed, obtains slurry.Sodium metaborate (NaBO is with the addition of in this slurry 2).Relative to Fe 2o 3powder and SrCO 3the total quality of powder, the addition of sodium metaborate is now converted into Na 2o is then 0.38 quality %.Afterwards, the spraying dry carrying out slurry obtains after particle diameter is the particle of 10 μm, under the firing temperature (T1) in atmosphere shown in table 7, this powder burnt till 1 hour, thus obtaining granular pre-burning body.The specific surface area measured by BET method of firing temperature and pre-burning body is as shown in table 7.Vibrating example magnetometer is used to measure the magnetic properties of obtained pre-burning body.Measurement result is shown in table 7.
Sorbitol Powder 1 quality %, SiO is added relative to this pre-burning body 130g 2powder 0.6 quality %, CaCO 3after powder 0.9 quality %, carry out case of wet attrition with ball mill and modulate slurry in 22 hours.The slurry of the concentration that have adjusted solids component is imported in wet type magnetic forming machine, be shaped in the externally-applied magnetic field of 12kOe and obtain the molding of cylindrical shape.With the firing temperature (T2) shown in table 7,1 hour is burnt till to this molding in atmosphere, obtain the ferrite sintered magnet of embodiment 31 ~ 33.
(embodiment 31 ~ 36)
Except not adding in slurry except sodium metaborate, all the other all make the ferrite sintered magnet of each comparative example equally with embodiment 31.The specific surface area measured by BET method and the magnetic properties of pre-burning body obtained in each comparative example are shown in Table 7.In addition, the firing temperature (T1) during the pre-burning of each comparative example and firing temperature (T2) as shown in table 7.In addition, in comparative example 31 and comparative example 32 because can not body be made into, so can not manufacture Sr ferrite sintered magnet.
[table 7]
In table, * 1 represents because can not be shaped, so can not obtain molding and sintered magnet.
[evaluation of ferrite sintered magnet]
The magnetic properties of the ferrite sintered magnet of each embodiment and each comparative example is have rated equally with embodiment 2.These results are shown in Table 8.In addition, the surface of the ferrite sintered magnet of each embodiment of visual observation and each comparative example, and visual valuation has flawless.By not finding that the ferrite sintered magnet of crackle is judged to be " A ", the ferrite sintered magnet finding that there is crackle is judged to be " B ".Result of determination is shown in Table 8.
[table 8]
The Sr ferrite sintered magnet of each embodiment, because have high squareness ratio and the value of Br+1/3HcJ is more than 5.68, has both high Br and high HcJ so be confirmed to be.
By the embodiment 31 ~ 33 shown in comparison sheet 7 and table 8 and comparative example 31 ~ 36, the Sr ferrite sintered magnet (embodiment 31 ~ 33) confirming to obtain when manufacturing when adding the alkali metal compounds such as sodium metaborate before pre-burning, compared with the Sr ferrite sintered magnet (comparative example 31 ~ 36) when not adding alkali metal compound and manufacture, also has excellent magnetic properties even if the specific surface area of pre-burning body is same degree.As major cause, think can promote the ferritic generation of Sr in pre-burning body by adding the alkali metal compounds such as sodium metaborate before pre-burning.
Industry utilizes possibility
A kind of manufacture method that can produce the Sr ferrite sintered magnet of the Sr ferrite sintered magnet with high magnetic properties and high reliability with easy operation can be provided by the present invention.In addition, a kind of Sr ferrite sintered magnet with high magnetic properties and high reliability can be provided.Further, a kind of engine and the generator with high-level efficiency and high reliability can be provided.

Claims (9)

1. a sintered magnet manufacture method for Sr ferrite particle, is characterized in that:
Possess:
Mixed processes, the mixing powder of iron cpd, the powder of strontium compound and the alkali metal compound containing alkali metal carry out modulating mixture;
Pre-burning operation, burns till described mixture at 850 ~ 1100 DEG C, thus the median size obtaining primary particle is the Sr ferrite particle of 0.1 ~ 1.0 μm,
In described mixed processes, with the total relative to the powder of described iron cpd and the powder of described strontium compound, the mode that alkali-metal total is converted into alkalimetal oxide becomes 0.03 ~ 1.05 quality % mixes described alkali metal compound,
Described alkali metal compound is at least one in alkali metal chloride, organic acid salt, phosphoric acid salt, borate, zeolite.
2. the sintered magnet manufacture method of Sr ferrite particle as claimed in claim 1, is characterized in that:
In described pre-burning operation, make the volatilization at least partially of the alkali metal compound added in described mixed processes, and the content obtaining chlorine is the Sr ferrite particle of below 1000ppm.
3. the sintered magnet manufacture method of Sr ferrite particle as claimed in claim 1 or 2, is characterized in that:
The saturation magnetization of described Sr ferrite particle is more than 67emu/g.
4. the manufacture method of Sr ferrite particle of the sintered magnet according to any one of claims 1 to 3, is characterized in that:
The specific surface area of the Sr ferrite particle obtained in described pre-burning operation is 1.5 ~ 10m 2/ g.
5. a manufacture method for Sr ferrite sintered magnet, is characterized in that:
The Sr ferrite particle that the manufacture method of use according to any one of Claims 1 to 4 obtains is to manufacture Sr ferrite sintered magnet.
6. the manufacture method of Sr ferrite sintered magnet as claimed in claim 5, is characterized in that:
In described Sr ferrite sintered magnet,
The median size of Sr ferrite crystal grains is less than 0.6 μm,
Particle diameter is the ratio of the number benchmark of the described crystal grain of more than 1.8 μm is less than 1%.
7. the manufacture method of Sr ferrite sintered magnet as claimed in claim 6, is characterized in that:
Meet following formula (1),
Br+1/3HcJ≥5.5 (1)
In formula (1), Br and HcJ represents residual flux density and coercive force respectively, and wherein, residual flux density unit is kG, and coercitive unit is kOe.
8. the manufacture method of the Sr ferrite sintered magnet as described in claim 6 or 7, is characterized in that:
Squareness ratio is more than 80%.
9. the manufacture method of the Sr ferrite sintered magnet according to any one of claim 5 ~ 8, is characterized in that:
Described alkali metal compound is again added in the crushed material obtained being pulverized by pre-burning body.
CN201380029932.2A 2012-07-27 2013-07-26 Manufacturing method for Sr ferrite particles for sintered magnet, and manufacturing method for Sr ferrite sintered magnet Pending CN104379537A (en)

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JP6488675B2 (en) * 2013-12-06 2019-03-27 Tdk株式会社 Sr ferrite sintered magnet, motor and generator
CN114974875B (en) * 2022-06-30 2023-11-14 余子欣 Preparation method of environment-friendly high-performance bonded permanent magnetic ferrite magnetic powder

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CN106045494A (en) * 2016-05-31 2016-10-26 山东嘉诺电子有限公司 Manganese-zinc soft magnetic ferrite material and preparing method thereof
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