CN104876559A - Ferrite sintered compact and electronic component using the same, and power supply device - Google Patents
Ferrite sintered compact and electronic component using the same, and power supply device Download PDFInfo
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- CN104876559A CN104876559A CN201510089298.2A CN201510089298A CN104876559A CN 104876559 A CN104876559 A CN 104876559A CN 201510089298 A CN201510089298 A CN 201510089298A CN 104876559 A CN104876559 A CN 104876559A
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- sintered compact
- ferrite
- cemented body
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
- C04B35/26—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on ferrites
- C04B35/2658—Other ferrites containing manganese or zinc, e.g. Mn-Zn ferrites
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- 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
- H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
- H01F1/34—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials non-metallic substances, e.g. ferrites
- H01F1/342—Oxides
- H01F1/344—Ferrites, e.g. having a cubic spinel structure (X2+O)(Y23+O3), e.g. magnetite Fe3O4
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/30—Constituents and secondary phases not being of a fibrous nature
- C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
- C04B2235/327—Iron group oxides, their mixed metal oxides, or oxide-forming salts thereof
- C04B2235/3272—Iron oxides or oxide forming salts thereof, e.g. hematite, magnetite
- C04B2235/3274—Ferrites
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- Dispersion Chemistry (AREA)
- Power Engineering (AREA)
- Soft Magnetic Materials (AREA)
- Magnetic Ceramics (AREA)
Abstract
The invention discloses a ferrite sintered compact and an electronic component using the same, and a power supply device. The ferrite sintered compact herein is not provided with a special coating which causes a cost increase of the ferrite sintered compact, but has a high strength. The invention also provides an electronic component which utilizes the excellent strength of the ferrite sintered compact and also a highly reliable power supply device which uses the electronic component. The ferrite sintered compact herein refers to the Mn-Zn group ferrite sintered compact containing Co, being characterized in that: a compressive stress is attached to the range extending inwardly from the utmost surface of the Mn-Zn group ferrite sintered compact containing Co to a third of the thickness of the sintered compact including the utmost surface.
Description
Technical field
The present invention relates to and be suitable for the magnetic core of transformer or reactance coil etc. and the ferrite cemented body of high strength.In addition, the present invention relates to the electronic unit employing such ferrite cemented body.In addition, the present invention relates to the supply unit employing this electronic unit.
Background technology
In recent years, the miniaturization of electronics and high efficiency development, the electronic unit that supply unit etc. use also is strongly required miniaturization, high efficiency.In order to miniaturization, high efficiency, the ferrite cemented body used for the electronic unit such as coil or transformer requires low loss characteristic.
In the past, the low loss characteristic that ferrite cemented body becomes excellent to make its magnetic properties, and with after sintering not the mode of residual strain manufacture.Reason is, if strain is residual after sintering, then due to this residual strain, produces residual stress and cause the reduction of permeability or magnetic loss to increase the deterioration of such magnetic properties at ferrite cemented body.
Such as, in the low loss ferrite material described in patent documentation 1, reduce residual stress by the speed of cooling controlling firing process and reduce magnetic loss.In addition, such as, in the manufacture method of the soft ferrite described in patent documentation 2, when the burning till of ferrite formed body, make between deposited plate at formed body and pottery and be scattered with the powder such as zinc oxide.Stop thus and react from ferritic dezincify, improve the deterioration of the magnetic properties that the stretching residual stress that produces due to the contraction of the lattice parameter of Spinel causes.In addition, such as, in the ferrite core described in patent documentation 3, by being covered the surface of core with what be made up of glass composition by rete, thus the difference of the thermal expansivity of core and coating layer is utilized to reduce residual stress and improve initial magnetic permeability.In addition, describing can by being played the breakage etc. being used for effectively preventing core of expendable film by rete.
As shown in patent documentation 1,2,3, up to the present, in order to not make the magnetic properties of ferrite cemented body worsen, be strongly required to eliminate the residual stress produced due to residual strain.
Prior art document
Patent documentation
Patent documentation 1: Japanese Unexamined Patent Publication 2007-204349 publication
Patent documentation 2: Japanese Patent No. 2833722 publication
Patent documentation 3: Japanese Patent No. 5195669 publication
Summary of the invention
Invent technical problem to be solved
As shown in patent documentation 1,2,3, up to the present, think ferrite cemented body the residual stress that namely produces due to residual strain of the strain that remains be unwanted, thus use up effort and eliminate to greatest extent.
When the low-loss magneticsubstance described in patent documentation 1, define firing process in the mode not producing residual stress after sintering.In the manufacture method of the soft ferrite described in patent documentation 2, by stoping ferritic dezincify to be reacted, thus improve the deterioration of the magnetic properties caused by produced residual stress.But, in above-mentioned patent documentation 1,2, with the cognation of the strain residuing in ferrite cemented body, any consideration is not done to the intensity (resistance to stress) of ferrite cemented body.In the ferrite cemented body that the electronic unit such as coil or transformer uses, there are many resins etc. to cover overall sintered compact or the sintered compact of a bonding part, or accept the such sintered compact of external stress consistently with fixing sintered compacies etc. such as metal partss.For such background, require the ferrite cemented body of high strength.
In addition, in the ferrite core described in patent documentation 3, describe by relaxing the residual stress of core with coating layer and improve initial magnetic permeability, and effectively can prevent the breakage etc. of core by the effect being played expendable film by rete.About patent documentation 3, owing to being prevented breakage etc. by having by rete, therefore think that intensity improves.But even if such as improved intensity by having by rete, the intensity (resistance to stress) of sintered compact itself also can not improve, and there is the rough sledding being coated with the way such by rete that be made up of glass composition and bringing cost to increase.In addition, although the intensity of refer to, do not present any data about resistance to stress.
In addition, as shown in patent documentation 2,3, up to the present, make great efforts to eliminate the residual stress caused by strain remaining in hundreds of μm from the most surface of ferrite cemented body.
Such as, shown in patent documentation 2, describe and from the most surface of ferrite cemented body, cause dezincify reaction and magnetic properties is deteriorated, in contrast, by removing from the most surface of ferrite cemented body about 250 μm improve iron loss.At this, the layer involved by strain is read as 250 μm.
Describe too in patent documentation 3 think that the reason of residual stress is ferrite composition burn till, the stress caused by contraction when cooling or owing to burning till, cooling time ferrite composition in the stress etc. that produces of the evaporation etc. of composition particularly ZnO component.In patent documentation 3, do not mention the surface of ferrite cemented body, but it is as noted above, as being that the place being 0.2 ~ 0.3mm with the thickness of the flange part 5 of core 2 in the point (same with patent documentation 2) of reason or embodiment is also known from the evaporation particularly mentioning ZnO component, similarly, the layer involved by assumed strain field mostly is about hundreds of μm most to patent documentation 2.At this, the maximum ga(u)ge due to flange part is 0.3mm, and therefore supposition is 0.15mm (150 μm) to the maximum is clearly.
In patent documentation 1, do not control in suitable oxygen partial pressure, suitable speed of cooling if had in the process of cooling of sintering circuit yet, then sintered compact surface or peroxidation or cross reduction, or Grain-Boundary Phase is blocked up, or do not form Grain-Boundary Phase, but not hard to imaginely in the same manner as patent documentation 2,3 mention the stress remaining in hundreds of μm from the most surface of ferrite cemented body.
As noted above, up to the present, think that strain is the unnecessary strain that " layer that composition etc. uneven " of existence from the most surface of ferrite cemented body to hundreds of μm produces.But the present inventor etc. are conceived to strain the relation with the intensity of ferrite cemented body, after measuring the intensity of the ferrite cemented body after making strain variation, find that strain impacts the intensity of ferrite cemented body.In addition, the result made by existing method for making such shown in patent documentation 1,2,3 described above, finds that this strain is not the strain residuing in most surface, but residues in the strain of the inside of more than hundreds of μm from the most surface of ferrite cemented body.
The present invention, because the above-mentioned and invention made, its object is to the ferrite cemented body providing a kind of high strength.In addition, another object of the present invention is to provide a kind of electronic unit employing the excellent strength of such ferrite cemented body.In addition, another object of the present invention is to provide a kind of supply unit with high reliability employing this electronic unit.
The means of technical solution problem
The present inventor etc. have carried out studying with keen determination in order to achieve the above object.It found that, by thinking existing the scope that unwanted strain is attached to more than " form etc. uneven layer " (hundreds of μm: the words of such as dezincify layer are 250 μm) formed by existing method for making from the most surface of the Mn-Zn based ferrite sintered compact containing Co, the intensity of the Mn-Zn based ferrite sintered compact containing Co can be improved, thus complete the present invention.
At this, just " layer that composition etc. are uneven " is described.The uneven layers such as composition refer to, compared with the penetralia of ferrite cemented body and central part, " being present in the layer of hundreds of μm from the most surface of ferrite cemented body " of one of them change such as composition, valence mumber, Grain-Boundary Phase thickness or particle diameter, it is the layer making the reason of magnetic properties deterioration by producing residual stress.As everyone knows, this layer is removed by mechanical mill or chemical grinding thus recovers magnetic properties.After the present inventor etc. estimate the thickness of above-mentioned layer according to the recovery situation of icp analysis and magnetic properties, maximum less than 300 μm.That is, the layer less than 300 μm from the most surface of ferrite cemented body is referred to " form etc. uneven layer " formed by existing method for making mentioned here.
Achieve the goal to solve above-mentioned technology, ferrite cemented body involved in the present invention, it is characterized in that, it is the Mn-Zn based ferrite sintered compact containing Co, in the most surface from the described Mn-Zn based ferrite sintered compact containing Co internally, until the scope comprising 1/3rd of the sintered compact thickness of most surface is attached with compressive strain.According to this ferrite cemented body, to be additional to from the most surface of the described Mn-Zn based ferrite sintered compact containing Co internally until comprise the scope of 1/3rd of the sintered compact thickness of most surface by compressive strain, the fracture resistence force of the described Mn-Zn based ferrite sintered compact containing Co can be improved.Its result, can improve the intensity of ferrite cemented body.
In addition, in the evaluation of magnetic loss, do not consider excitation waveform in the past.Generally speaking, the evaluation of magnetic loss is undertaken by sinusoidal wave excitation, in above-mentioned patent documentation 1,2,3, to excitation waveform all without any consideration, record.That is, the characteristic that the magnetic properties of deterioration is such due to residual strain on the books in above-mentioned patent documentation 1,2,3 is the characteristic measured by sinusoidal wave excitation.But in the circuit of the product of reality, excitation waveform is not sine wave, be nearly all carry out action with square wave excitation.It is important for reproducing the actual state being equipped on physical device better that the present inventor etc. are conceived to the mensuration that square wave excitation carries out, except strain of the present invention adds except caused intensity increases, be also repeated with regard to the change of the magnetic loss caused by square wave excitation and study with keen determination.It found that, the composition of the Mn-Zn based ferrite sintered compact containing Co described in consisting of order is suitable scope or additional dependent variable is suitable scope, thus except first object of the present invention and intensity increase, the loss caused by square wave excitation can also be suppressed.
That is, in the present invention, preferably, the principal constituent of the described Mn-Zn based ferrite sintered compact containing Co when being converted into oxide compound respectively by the Fe of 51 ~ 54 % by mole
2o
3, the ZnO of 6 ~ 16 % by mole, the MnO of surplus form, relative to total quality 1 mass parts of the described oxide compound of described principal constituent, if be converted into CoO, then containing 100 × 10
-6~ 4000 × 10
-6the Co of mass parts is as minor component.According to this ferrite cemented body, the composition consisting of the described Mn-Zn based ferrite sintered compact containing Co order is suitable scope, thus can improve the intensity of sintered compact in the scope that can obtain low loss characteristic.Its result, can provide low-loss and the ferrite cemented body of the improved excellence of intensity.
In addition, in the present invention, additional compressive strain is preferably 3.5 ~ 102 μ ε.By making additional compressive strain be such scope, thus except effect of the present invention and intensity increase, the ferrite cemented body significantly increased of the magnetic loss under square wave excitation can also be suppressed.
The present invention is a kind of electronic unit, it is characterized in that, employs the described Mn-Zn based ferrite sintered compact containing Co.By using the described Mn-Zn based ferrite sintered compact containing Co, thus the electronic unit of excellent strength can be provided.
The present invention is a kind of supply unit, it is characterized in that, possesses described electronic unit.According to this supply unit, due to the electronic unit of working strength excellence, the supply unit with high reliability therefore can be provided.
Invention effect
As more than, according to the present invention, the ferrite cemented body of high strength, the electronic unit of excellent strength can be provided and there is the supply unit of high reliability.
Accompanying drawing explanation
Fig. 1 is the stereographic map of the embodiment representing ferrite cemented body involved in the present invention.
Fig. 2 is the graphic representation of an example of the temperature setting represented in existing firing process.
Fig. 3 is the graphic representation of an example of the temperature setting represented in firing process involved in the present invention.
Fig. 4 represents it is the ferrite cemented body of an embodiment of ferrite cemented body involved in the present invention and the stereographic map of the sticking position of strainometer and strainometer.
Fig. 5 is the stereographic map in the direction of the inboard portion represented by grinding the ferrite cemented body eliminating the embodiment being ferrite cemented body involved in the present invention.
The explanation of symbol:
1 ferrite cemented body 1
2 central part sides 2
3 strainometers 3
Embodiment
(embodiment)
ferrite cemented body
The shape of the ferrite cemented body of an embodiment involved in the present invention is not particularly limited, and except EE type, can also illustrate FT type, ET type, EI type, UU type, drum type, EER type, UI type, ring-like, crucible-type, cup type etc.In the present embodiment, as shown in Figure 1, ferrite cemented body 1 has I type shape.Ferrite cemented body is made up of ferrite composition, is preferably Mn-Zn based ferrite or Ni-Zn based ferrite, is more preferably Mn-Zn based ferrite.Reason is the having excellent magnetic properties of Mn-Zn based ferrite.
ferrite sintered manufacturing method
Ferrite cemented body is by using Fe
2o
3, the oxide raw material such as ZnO, MnO, NiO, and by pre-burning, pulverizing, shaping, burn till so existing powder metallurgic method and make.
Below, the ferrite composition just forming the Mn-Zn based ferrite sintered compact of an embodiment involved in the present invention is described.
In the ferrite composition forming Mn-Zn based ferrite sintered compact, principal constituent is by with Fe
2o
3the convert ferric oxide of 51 ~ 54mol%, to convert with the ZnO zinc oxide of 6 ~ 16mol%, the manganese oxide of surplus is formed.In addition, relative to total quality 1 mass parts of the oxide compound of above-mentioned principal constituent, convert containing 100 × 10 with CoO
-6~ 4000 × 10
-6the cobalt oxide of mass parts is as minor component.In the poor situation of ferric oxide, produce exaggerated grain growth during sintering and intensity reduces.In addition, reduce if cross density at most, thus intensity reduces significantly.In the poor situation of zinc oxide, the intensity losses caused by density reduces is remarkable.In addition, if too much, then due to exaggerated grain growth, intensity reduces.By the cobalt oxide containing appropriate minor component, the temperature variation of magnetic loss can be reduced.On the other hand, although the content of cobalt oxide is 4000 × 10
-6the temperature variation of the above magnetic loss of mass parts diminishes, but magnetic loss increases.
In the ferrite composition of present embodiment, except the principal constituent of above-mentioned compositing range, minor component, also containing silica and calcium oxide as minor component.By containing such minor component, the bonding force of crystal boundary increases, and can obtain high strength.The content of silicon oxide relative to principal constituent 100 % by weight with SiO
2be scaled 50 ~ 300ppm.Silicon oxide is too much or very few, all has and produces exaggerated grain growth and the tendency of intensity reduction.The content of calcium oxide is scaled 110 ~ 1120ppm relative to principal constituent 100 % by weight with CaO.The content of calcium oxide is too much or very few, all has and produces exaggerated grain growth and the tendency of intensity reduction.
Then, an example of the manufacture method of the ferrite cemented body involved by present embodiment is described.
First, in order to the raw material of the ferrite composition of composition of preparation ferrite cemented body 1, by initial feed (raw material of principal constituent and the raw material of minor component) to become the mode weighing of the ratio of components of regulation and to mix, obtain raw mixture.As the method for mixing, such as, can enumerate the wet mixing using ball mill to carry out or the dry type mixing using dry mix machine to carry out.In addition, preferably use median size is the initial feed of 0.1 ~ 3 μm.
As the raw material of principal constituent, ferric oxide (α-Fe can be used
2o
3), zinc oxide (ZnO), manganese oxide (Mn
3o
4) or composite oxides etc.In addition, can also use in addition by burning till the various compounds etc. becoming above-mentioned oxide compound or composite oxides.As by burning till the compound becoming above-mentioned oxide compound, such as, metal simple-substance can be enumerated, carbonate, oxalate, nitrate, oxyhydroxide, halogenide, organometallic compound etc.In addition, the content of the manganese oxide in principal constituent converts with MnO and calculates, but as the raw material of principal constituent, preferably uses Mn
3o
4.
As the raw material of minor component, not only can use oxide compound in the same manner as the situation of the raw material of principal constituent, but also composite oxides can be used or after burning till, become the compound of oxide compound.When cobalt oxide (CoO), preferably use Co
3o
4.In addition, at silicon oxide (SiO
2) when, preferably use SiO
2.In addition, when calcium oxide (CaO), calcium carbonate (CaCO is preferably used
3).
Then, carry out the pre-burning of raw mixture, obtain pre-burning material.Pre-burning in order to cause the disappearance of the super-fine powder caused by the thermolysis of raw material, the homogenizing of composition, ferritic generation, sintering and to the granular size of appropriateness grain growing and raw mixture is transformed into the form being suitable for rear operation and carries out.Such pre-burning, preferably at the temperature of 800 ~ 1100 DEG C, carries out 1 ~ 3 hours usually.Pre-burning can be carried out in air (air), also can carry out under atmosphere high in oxygen partial pressure is than air or pure oxygen atmosphere.In addition, the raw material of principal constituent can carry out with mixing of the raw material of minor component before pre-burning, also can carry out after pre-burning.
Then, carry out the pulverizing of pre-burning material, obtain pulverised material.The powder that pulverizing has the coking property of appropriateness in order to the cohesion and becoming disintegrating pre-burning material carries out.When pre-burning material forms large block, after carrying out coarse reduction, ball mill or masher etc. is used to carry out case of wet attrition.The median size that case of wet attrition proceeds to pre-burning material is preferably about 1 ~ 2 μm.
Then, carry out the granulation (particle) of pulverised material, obtain granules.Granulation becomes the flocculated particle of modest size to make pulverised material and is transformed into and is suitable for shaping form and carries out.As such comminution granulation, such as, can enumerate pressurization comminution granulation or spray-drying process etc.Spray-drying process be in pulverised material, add the normally used caking agents such as polyvinyl alcohol after, to be atomized in spray-drier, the method for cryodrying.
Then, granules is shaped to regulation shape, obtains formed body.Shaping as granules, such as can enumerate dry formed, wet type is shaping, extrusion moulding etc.Dry formed method carries out compressing pressurization (punching press) and the method for forming of carrying out by granules being filled in mould.The shape of formed body is not particularly limited, as long as be suitable for determining according to purposes, is I type shape in present embodiment.
Then, carry out burning till of formed body, obtain sintered compact (ferrite cemented body 1).Burning till is in order between the powder granule comprising lacunose formed body perhaps, and the sintering adhered under causing the temperature of powder below fusing point, obtains fine and close sintered compact and carry out.Burning till preferably at the temperature of 900 ~ 1300 DEG C like this, carries out 2 ~ 5 hours usually.Burn till and can carry out in air (air), also can carry out under atmosphere high in oxygen partial pressure is than air.
But, in the ferrite cemented body made by existing method, do not present effect of the present invention and high-strength characteristic.Therefore, below, the addition method of the compressive strain presented required for high-strength characteristic is described.
strain addition method
In present embodiment, in order to additional compression strain, study intensively firing process.First, carry out describing with regard to existing firing process.
Fig. 2 is the graphic representation of an example of the temperature setting represented in existing firing process.As shown in Figure 2, firing process at least have heat the formed body in process furnace gradually heating process S1, keep the temperature of temperature to keep operation S2, carry out the quenching process S4 of chilling after terminating from the gradually cooling working procedure S3 keeping temperature to lower the temperature gradually and at gradually cooling working procedure S3.
In heating process S1, heat-up rate is set to 10 ~ 300 DEG C/h.Keep, in operation S2, keeping temperature to be 1150 ~ 1350 DEG C in temperature.In gradually cooling working procedure S3, gradually speed of cooling is less than 150 DEG C/h.Terminate gradually cooling working procedure S3 and the temperature (gradually cold end temp) starting quenching process S4 is 950 ~ 1150 DEG C.It is more than the outline of existing firing process.
In the present embodiment, in order to additional compression strain, as shown in Figure 3, additional heating process S5 and additional cooling process S6 is set in the midway of gradually cooling working procedure S3.Increase and add operation and operation firing condition, make from the Outboard Sections of ferrite cemented body and most surface internally until the state comprising the layer of the scope of 1/3rd of the sintered compact thickness of most surface changes and controls dependent variable in desired value.In addition, as other strain addition methods, also can by through existing firing process, the ferrite cemented body being in normal temperature is put in process furnace again and is warmed up to any one temperature in 800 ~ 1300 DEG C and the annealing of cooling realizes.
dependent variable measuring method
In order to measure dependent variable, pre-set the reference figure of ferrite cemented body.The I type ferrite sintered compact 1 (Fig. 1) of reference figure to be size be length 70mm, width 8mm, thickness 8mm.In the mensuration of strain, strainometer 3 is attached at as shown in Figure 4 the central part side 2 of I type ferrite sintered compact 1, and as shown in Figure 5 the face plane grinding dish with the opposition side, face having attached strainometer is ground to till thickness is 2mm.By doing like this, the inboard portion of ferrite cemented body 1 can be removed, and mensuration is additional to from most surface internally until comprise the dependent variable of the layer of the scope of 1/3rd of the sintered compact thickness of most surface.In addition, this reference figure also uses as benchmark when measuring folding strength.
At this, just using be ground to dependent variable when thickness becomes 2mm as final dependent variable according to being described.As the preliminary experiment estimating dependent variable, the dependent variable using the ferrite cemented body of the square cubic shaped of 12mm to measure caused by amount of grinding changes.Its result, when the cubical grinding progress that 12mm is square, strains by discharging gradually that ferrite cemented body presents stretching, extension.When making grinding be in progress further, remaining from the place of 1/3rd, the stretching, extension of ferrite cemented body does not change.That is, from the thickness of ferrite cemented body is the place of 4mm, dependent variable does not change.Its result, thinks the scope of forcing additional strain to be additional to from the surface of ferrite cemented body 1/3rd.Actually being used in the square sample of 8mm that dependent variable measures, is also that the change of thickness below 1/3rd and 2mm or 1mm dependent variable restrains, thus with the dependent variable that 2mm is final.In addition, for this result, think that it is much the same for playing about 1/3rd as sintered compact from surface.At this, mention much the same be because, think ferrite cemented body extremely surface also there is the residual strain that can be formed by existing method for making.But even if think that the scope playing 300 μm from the surface of ferrite cemented body exists the residual strain caused by " composition etc. uneven layer ", residual strain is only for the small residual strain of most surface.Reason is, even if be ground to below it by remaining for ferrite cemented body from 1/3rd, dependent variable does not also change.If due to the residual strain caused by " layer that composition etc. are uneven ", ferrite cemented body presents stretching, extension, then the change strained would not converge to becomes thickness less than 300 μm.
As mentioned above, in the present invention, it is characterized in that, in the most surface from ferrite cemented body internally until comprise the scope additional compression strain of 1/3rd of the sintered compact thickness of most surface.
additional strain amount
Additional strain amount is preferably 3.5 more than μ ε.Reason is, compared with the ferrite cemented body not having at 3.5 more than μ ε to strain, estimates have the intensity of more than 10% to rise in folding strength.On the other hand, additional strain amount is at 102 more than μ ε, and intensity rises, but the magnetic loss caused by square wave excitation is increased to 600kW/m
3above.As the ferrite cemented body that electronic unit uses, magnetic loss is preferably 600kW/m
3below.Therefore, in the present invention, the additional preferred scope of dependent variable is set to 3.5 ~ 102 μ ε.The preferred dependent variable that can improve effect of the present invention is further the scope of 3.5 ~ 83 μ ε.Reason is, by making dependent variable be 3.5 ~ 83 μ ε, thus suppresses the magnetic loss measured by square wave excitation at 560kW/m as far as possible
3below, and folding strength can be obtained increase high effect.The preferred dependent variable that can improve effect of the present invention is further the scope of 3.5 ~ 64 μ ε.Reason is, by making dependent variable be 3.5 ~ 64 μ ε, thus suppresses the magnetic loss measured by square wave excitation at 540kW/m as far as possible
3below, and folding strength can be obtained increase high effect.
At this, although with values dictate additional strain amount, the relation of stress σ and strain stress represents by following formula 1.E represents coefficient of elasticity and different and different according to material.
< formula 1 >
σ＝Eε
Coefficient of elasticity due to ferrite cemented body is about 110 ~ 170GPa, therefore in scope 3.5 ~ 64 μ ε of most preferred dependent variable, minimumly becomes such calculating for σ=0.39MPa, the stress that is σ=10.88MPa to the maximum.The compressive strain additional by these and produce from most surface internally until the stress comprising the scope of 1/3rd of the sintered compact thickness of most surface contributes to ferrite cemented body, carry out high strength thus.
the reason of gaining in strength is strained by additional compression
In folding strength test, stress under compression is applied to pressure point, tensile stress is applied to the dorsal part of pressure point.If have fine crack or defect at the dorsal part of pressure point, then it becomes starting point, and sample is disrumpent feelings.In the ferrite cemented body with effect of the present invention, be all attached with stress under compression at the position becoming the disrumpent feelings starting point of sample, therefore, think that folding strength increases.
Generally speaking, represent the folding strength of the physical strength of material, its higher resistance to breakage is more excellent.That is, if improve folding strength, then the cracking of ferrite cemented body, defect reduce.
If the electronic unit such as transformer or choke coil carries ferrite cemented body during fabrication, or skeleton is installed on ferrite cemented body, or ferrite cemented body is fixed on fixing fixture, then ferrite cemented body is impinging one another or due to damaged by impact during holder sometimes in the fabrication process, but by using the ferrite cemented body with the high strength of effect of the present invention, such breakage can be reduced.
In addition, when the electronic unit such as transformer or choke coil is assembled in supply unit, if electronic unit is transferred or fix, then ferrite cemented body is again through there being the operation of damaged possibility, but by using the electronic unit with the excellent strength of the ferrite cemented body of the high strength of effect of the present invention, such breakage can be reduced.
Possess the ferrite cemented body employing the high strength that the present invention presents excellent strength electronic unit supply unit in, when power supply manufactures or when carrying, ferrite cemented body can not be damaged, therefore, the chip not having the ferrite cemented body of damaged electroconductibility is mixed into the circuit of supply unit inside and causes insulation breakdown, and the reliability of quality product is reduced.That is, the supply unit with high reliability can be provided.
even if the reason that the magnetic loss caused by additional compression strain rectangle excitation also increases not significantly
Although do not know clear and definite reason, when excitation waveform is square wave, different from sinusoidal wave situation, include higher harmonic component.Therefore, the several per-cents in total loss comprise the loss caused by various high frequency.In " addition of the ferrite cemented body of strain " in the present invention, the total loss of the loss that the loss under first-harmonic (1 time) adds caused by higher harmonic does not significantly increase, therefore, as a result, the reason that the magnetic loss caused by square wave excitation increases not significantly is thought to become.
[embodiment 1]
The oxide raw material forming ferrite cemented body is become Fe with final principal constituent
2o
3: 52.6mol%, ZnO:10.6mol%, surplus MnO, minor component becomes CoO:100 × 10
-6the mode weighing of mass parts, and use ball mill to carry out wet mixing.After making raw mixture drying, pre-burning at the temperature of about 900 DEG C in atmosphere.Obtained pre-burning powder is dropped into ball mill, carries out case of wet attrition until become desired particle diameter.The comminuted powder obtained like this is carried out drying, and the polyvinyl alcohol added as adhesive resin carries out granulation and makes particle.With the pressure of about 150MPa, extrusion forming is carried out to this particle, obtain annular formed body and I font formed body.In the nitrogen, air gas mixture of control oxygen partial pressure, the formed body obtained like this is burnt till, obtain being of a size of length 70mm, width 8mm, the I type ferrite sintered compact of thickness 8mm and the annular ferrite cemented body of external diameter 20mm, internal diameter 10mm, highly 5mm.The I type ferrite sintered compact of thickness 8mm is used for the mensuration of dependent variable and the mensuration of folding strength.Annular ferrite cemented body is used for the mensuration of magnetic properties.
In addition, due to the additional strain when burning till, therefore increase the additional heating process (300 DEG C/h) being warming up to from 1200 DEG C and arriving temperature A as shown in Figure 3 in gradually cooling working procedure midway and from the additional cooling process (300 DEG C/h) arriving temperature A and be cooled to 1200 DEG C.Arrival temperature A in additional operation is changed, as shown in table 1ly obtains the different ferrite cemented body of multiple dependent variable.
The mensuration of strain uses the strainometer (KFG: general foil strain gauge) of republicanism electric industry to carry out.As shown in Figure 4, strainometer 3 is attached at the central part side 2 of I type ferrite sintered compact, as shown in Figure 5, side plane grinding dish with the opposition side, face having attached strainometer 3 is ground to thickness be 1/3rd (2.67mm) below, remove the inboard portion of ferrite cemented body thus, and mensuration is additional to from most surface internally until comprise the dependent variable of the layer of the scope of 1/3rd of the sintered compact thickness of most surface.In addition, the mensuration of dependent variable measures periodically thinning for sintered compact thickness for 5mm, 2.67mm, 2mm, 1mm, the dependent variable of the 2mm of the dimensional change caused by strain is represented in Table 1.Change list about the mensuration dependent variable caused by sintered compact thickness is shown in table 1-2.The strain measured at this is compressive strain.If remove the inboard portion of ferrite cemented body, then the strainometer attached with remaining Outboard Sections shows and stretches.
The mensuration of folding strength and flexural strength is undertaken by using 3 pliability tests of I type ferrite sintered compact.Make distance between the fulcrum be 50mm, trial speed is 5mm/ minute.The mensuration of magnetic properties uses square wave, measures, and compare the magnetic loss at 100 DEG C under the condition of frequency 100kHz, magneticflux-density 250mT.
The measurement result of dependent variable and folding strength and magnetic loss is represented in table 1.As shown in table 1, by making the arrival temperature A in additional operation change when burning till, thus in the embodiment 1a ~ 6a of the surperficial additional strain of ferrite cemented body, increase relative to comparative example 1a folding strength.In addition, in the embodiment 2a ~ 6a of scope being in the preferred dependent variable of the present invention, suppress the significantly increase of magnetic loss as far as possible, and the higher effect of folding strength increase can be obtained.
[table 1]
※ comparative example 1a makes under the existing firing condition not adding operation.
The change of the mensuration dependent variable caused by sintered compact thickness is represented in table 1-2.As known in shown as shown in 1-2, if grinding progress and sintered compact thickness be 1/3rd (2.67mm) below, then dependent variable change convergence.
[table 1-2]
[embodiment 2]
The oxide raw material of the Mn-Zn based ferrite sintered compact formed containing Co is become Fe with final principal constituent
2o
3: 52.6mol%, ZnO:10.6mol%, surplus MnO, minor component becomes CoO:4000 × 10
-6the mode weighing of mass parts, and use ball mill to carry out wet mixing.Except the amount making the CoO added in embodiment 2 is 4000 × 10
-6beyond mass parts, material fabrication process and evaluation method same with the above embodiments 1.In addition, as previously discussed, the measured value of dependent variable converge on sintered compact thickness be 1/3rd (2.67mm) below and not change, therefore, be final dependent variable to change the strain measurement definite value that the sintered compact thickness of convergence is 2mm.
The measurement result of dependent variable and folding strength and magnetic loss is represented in table 2.As shown in table 2, increasing relative to comparative example 1b folding strength in the embodiment 1b ~ 6b of the surperficial additional strain of ferrite cemented body by making the arrival temperature A in additional operation change when burning till.In addition, in the embodiment 2b ~ 6b of scope being in the preferred dependent variable of the present invention, suppress magnetic loss significantly to increase as far as possible, and the higher effect of folding strength increase can be obtained.
[table 2]
※ comparative example 1b makes under the existing firing condition not adding operation.
[embodiment 3]
By each component materials finally to become the mode weighing of the composition shown in table 3, and ball mill is used to carry out wet mixing.In embodiment 3, each composition is as shown in table 3, and material fabrication process and evaluation method same with above-described embodiment 1.In addition, the arrival temperature A of the additional operation in burning till is 1260 DEG C.In addition, as previously discussed, the measured value of dependent variable converge on sintered compact thickness be 1/3rd (2.67mm) below and not change, therefore, be final dependent variable to change the strain measurement definite value that the sintered compact thickness of convergence is 2mm.
The measurement result of dependent variable and folding strength and magnetic loss is represented in table 3.As shown in table 3, by making the arrival temperature A in additional operation change when burning till in whole samples of the embodiment 1c ~ 6c of the surperficial additional strain of ferrite cemented body, the high breaking strength of performance more than 110MPa.Especially, in the embodiment 2c ~ 5c of scope being in the preferred dependent variable of the present invention, if magnetic loss is 540kW/m
3high breaking strength below, then suppresses the increase of magnetic loss as far as possible, while can be obtained.
[table 3]
[comparative example]
Then, in order to confirm the impact caused the folding strength of the extremely residual strain on surface formed by existing method for making, the sample that the oxygen concn in the gradually cooling working procedure S3 of the existing firing process shown in Fig. 2 is changed is made.By making the oxygen concn in gradually cooling working procedure S3 change, thus the change of the degree of oxidation on sintered compact surface, reducing degree, inside and outside sintered compact, produce stress and magnetic loss increases.
Material fabrication process beyond firing process is same with above-described embodiment 2.About evaluation method, the mensuration of folding strength and flexural strength is same with above-described embodiment 2.On the other hand, measure under the condition of the condition determination being determined at general supply transformer Ferrite Material of magnetic properties and frequency 100kHz, magneticflux-density 200mT, and compare the magnetic loss at 100 DEG C.
Maintenance temperature in the maintenance operation S2 of aforementioned firing process is 1300 DEG C, keeps oxygen concn to be 2.4%.Oxygen concn P (%) gradually in cooling working procedure S3 making that a is obliquity, T is absolute temperature (K), b be by the maintenance temperature in aforementioned maintenance operation and keep oxygen concn and upper aforementioned gradient a uniquely to determine constant time, specified by the formula of Log (P)=a/T+b (wherein, Log is denary logarithm).In this comparative experiments, make the sample producing residual strain by making the value of aforementioned obliquity a change in the most surface of ferrite cemented body.
The sample like this obtained carry out the mensuration of dependent variable, the mensuration of folding strength, the magnetic loss caused by original sine ripple excitation mensuration and produced residual stress by mechanical mill and chemical grinding removing " layer that composition etc. are uneven " after the mensuration of the magnetic loss caused by sinusoidal wave excitation, confirm the impact of the extremely residual strain on surface formed by existing method for making.In an experiment, the layer of about 300 μm from the most surface of ferrite cemented body is removed by mechanical mill and chemical grinding.
The measurement result of the magnetic loss caused by sinusoidal wave excitation after dependent variable and the removing of folding strength, the initial magnetic loss caused by sinusoidal wave excitation and most surface is represented in table 4.As shown in table 4, in existing method for making, until the non-additional strain in inside that layer from the most surface of ferrite cemented body to 2mm is such.Therefore, the dependent variable measured by strainometer does not change.In addition, due to the non-additional strain in inside that the layer from most surface to 2mm is such, therefore folding strength is not also significantly improved.On the other hand, initial magnetic loss is not controlling to increase in comparative example 1d, 3d, 4d at suitable oxygen concn.This is because in the most surface (less than 300 μm) of ferrite cemented body, due to peroxidation or cross reduction and produce residual strain, produce residual stress thus.But, even do not control the sample at suitable oxygen concn, after removing most surface, the recovery of magnetic properties also can be seen.
That is, in existing method for making, if do not control at suitable oxygen concn, then produce residual strain in the most surface of ferrite cemented body and make the magnetic loss deterioration caused by sinusoidal wave excitation.But, in the residual strain on the extremely surface of accidental like this generation, can not get the effect of effect of the present invention and folding strength increase.
[table 4]
Utilizability in industry
As previously discussed, ferrite cemented body involved in the present invention is useful for the ferrite cemented body that the electronic unit such as transformer or choke coil uses.
Claims (5)
1. a ferrite cemented body, is characterized in that,
The Mn-Zn based ferrite sintered compact containing Co, in the most surface from the described Mn-Zn based ferrite sintered compact containing Co internally, until the scope comprising 1/3rd of the sintered compact thickness of most surface is attached with compressive strain.
2. ferrite cemented body as claimed in claim 1, is characterized in that,
The principal constituent of the described Mn-Zn based ferrite sintered compact containing Co when being converted into oxide compound respectively by the Fe of 51 ~ 54 % by mole
2o
3, the ZnO of 6 ~ 16 % by mole, the MnO of surplus form, relative to total quality 1 mass parts of the described oxide compound of described principal constituent, if be converted into CoO, then containing 100 × 10
-6~ 4000 × 10
-6the Co of mass parts is as minor component.
3. ferrite cemented body as claimed in claim 1 or 2, is characterized in that,
The amount of described strain is 3.5 ~ 83 μ ε.
4. an electronic unit, is characterized in that,
The ferrite cemented body described in any one in claim 1 ~ 3 is used to form.
5. a supply unit, is characterized in that,
Possesses electronic unit according to claim 4.
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| CN108779035A (en) * | 2016-03-10 | 2018-11-09 | 松下知识产权经营株式会社 | Ferrite Material, composite magnetic body, coil component and supply unit |
| CN116813323A (en) * | 2023-07-07 | 2023-09-29 | 上海宝钢磁业有限公司 | Wide-temperature low-loss soft magnetic manganese zinc ferrite material suitable for 25-140 ℃ and preparation method and application thereof |
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| CN101061080A (en) * | 2004-11-19 | 2007-10-24 | 日立金属株式会社 | Low-loss Mn-Zn ferrite and, electronic part and switching power supply utilizing the same |
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| CN107403679A (en) * | 2017-07-31 | 2017-11-28 | 中国航天时代电子公司 | A kind of highly reliable Ethernet transformer of wide Wen Naigao direct currents |
| CN116813323A (en) * | 2023-07-07 | 2023-09-29 | 上海宝钢磁业有限公司 | Wide-temperature low-loss soft magnetic manganese zinc ferrite material suitable for 25-140 ℃ and preparation method and application thereof |
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