Powder mixture for powder magnetic core, and powder magnetic core

专利摘要:
Abstract The present invention pertains to: a powder mixture for powder magnetic coreobtained by mixing a lubricant, a solid lubricant, and a soft magnetic powder coatedwith an insulating coating, wherein a lubricant content is 0.1% by mass or more and08% by mass and a solid lubricant content is 0,01% by mass or more and 02% by mass or less; and a powder magnetic core in which the powder mixture is used. 16
公开号:SE1751500A1
申请号:SE1751500
申请日:2016-04-27
公开日:2017-12-06
发明作者:Hirofumi Hojo；Hiroyuki Mitani；Satomi Sato；Yuji Taniguchi
申请人:Kobe Steel Ltd；
IPC主号:

专利说明:

[2] [0002] Electromagnetic steel sheets, powder magnetic cores, soft ferrites, and the likeare used for iron cores of electromagnetic devices used in altemating current magneticfields such as noise filters and reactors. In all cases, it is necessary to suppress an eddycurrent generated in the iron core in an altemating current magnetic field. The eddycurrent is suppressed by forming an insulating coating on the plate surface of theelectromagnetic steel sheet and on the powder surface of the powder magnetic core,respectively. ln addition, since the soft ferrite is an oxide, the electric resistance of thematerial itself is high, and thus it is not necessary to form an insulating coating in thecase of the soft ferrite.
[3] [0003] Among them, the use of a powder magnetic core obtained by compressionmolding of a soft magnetic powder as an iron core of an electromagnetic device hasbeen increasing particularly in recent years. The powder magnetic core is formed bycompression molding of a soft magnetic powder having an insulating coating formed onits surface, but the magnetic characteristics thereof largely depend on the compactdensity, and it is necessary to form the powder magnetic core at a high density whilesecuring electrical insulation between particles to obtain high magnetic characteristics.[0004] Here, the magnetic characteristics refer to magnetic flux density, magneticperrneability, iron loss, etc. When electrical insulation between particles is secured, aninterparticle eddy current loss generated between particles is suppressed. As a result,an eddy current loss is only an intraparticle eddy current loss generated inside particles,and thus the eddy current loss is minimized. Therefore, for the characteristics of thepowder magnetic core obtained by compression molding of a soft magnetic powdercoated with an insulating coating, the direct current magnetic characteristics representedby magnetic flux density and magnetic perrneability are important characteristics.
[5] [0005] Since saturated magnetic flux density is proportional to the amount of iron, it depends on the compact density. In addition, since the magnetic perrneability is aninclination of an initial magnetization curve and is an index representing easiness ofpassing the magnetic flux, the magnetic perrneability becomes higher as the number ofthe gaps that become magnetoresistance is smaller, and similarly to the saturationmagnetic flux density, the magnetic perrneability becomes higher as the compact densitybecomes higher.
[6] [0006] Further, high magnetic perrneability means that the magnetic flux density at acertain excitation magnetic field is high, and not only the saturation magnetic fluxdensity but also the magnetic flux density can be improved by increasing the compactdensity. Therefore, for improving the direct current magnetic characteristics, it is mostimportant to increase the compact density.
[7] [0007] As described above, the powder magnetic core is obtained by compressionmolding of a soft magnetic powder having an insulating coating formed thereon, i.e., thepowder magnetic core is obtained by filling a soft magnetic powder in a mold, followedby compression molding. A lubricant is used to prevent seizure with the mold inmolding.
[8] [0008] There are roughly two ways to use a lubricant when preparing a powdermagnetic core. One way is an intemal lubrication molding (mixed lubricationmolding) in which a lubricant is directly mixed with a soft magnetic powder or a softmagnetic powder is coated with a lubricant, and the other is a mold lubrication moldingin which a lubricant is applied to the inner surface of a mold. In the mold lubricationmolding, there is a problem that it is difficult to form a complicated shape. Therefore,in the case of manufacturing a compact having a complicated shape, an intemallubrication molding, in which a lubricant is mixed with a soft magnetic powder, may beused in combination.
[9] [0009] The mold lubrication molding has an advantage that a high compact density canbe obtained since a lubricant is not contained inside the compact. However, since thelubricant is applied to the inner wall surface of the mold, the shape of the compact isrestricted, and thus the mold lubrication molding is not a suitable method for forrningcomplex shapes. On the other hand, there remains a problem that a high compactdensity cannot be obtained in the intemal lubrication molding. Under suchcircumstances, the development of a technique for increasing the compact density evenwhen adopting the intemal lubrication molding suited for forrning complex shapes hasbeen desired. [00l0] Techniques described in Patent Documents l and 2 are known as examples in which a lubricant is used in producing a green compact, but lubricants used in these techniques are only organic lubricants.[0011] On the other hand, examples in which an organic lubricant and a solid lubricantare used together in producing a sliding part such as a valve guide used at hightemperature are disclosed in Patent Documents 3 to 5. However, the key of thesetechniques is to leave the solid lubricant after sintering, and such techniques are notintended to improve the compact density by improving the compaction property.[0012] The present invention has been made to solve the above-mentioned conventionalproblems, and it is an object of the present invention to provide a powder mixture forpowder magnetic core capable of producing a powder magnetic core excellent inmagnetic properties while increasing the compact density even when adopting intemallubrication molding in the production of the powder magnetic core, and provide apowder magnetic core produced by using the powder mixture for powder magnetic core.Citation ListPatent Literatures[0013] Patent Literature 1: Japanese Patent Application Laid-Open No. 2012-111987Patent Literature 2: Japanese Patent Application Laid-Open No. 2012-67334Patent Literature 3: Japanese Patent Application Laid-Open No. 2003-183701Patent Literature 4: Japanese Patent Application Laid-Open No. 2008-202123Patent Literature 5: Japanese Patent Application Laid-Open No. 2010-216016Summary of the Invention[0014] A powder mixture for powder magnetic core according to an aspect of thepresent invention is a powder mixture for powder magnetic core obtained by mixing alubricant, a solid lubricant, and a soft magnetic powder coated with an insulatingcoating, wherein the lubricant content is 0.1% by mass or more and 08% by mass orless and the solid lubricant content is 0.01% by mass or more and 0.2% by mass or less.Brief Description of Drawings[0015] FIG. 1 is a graph illustrating the relationship between the compact density of apowder magnetic core and the compacting pressure at the time of compression mo lding.
[18] [0018] As described above, since the lubricant is a material necessary for preventingseizure with the mold at the time of molding, the amount that can be reduced is limited,and it is necessary to achieve both compactibility and reduction of the amount of thelubricant at the same time.
[19] [0019] In view of such circumstances, the present inventors have intensively studiedresearch, experiments and the like, and focused on the volume of the lubricant. Thepresent inventors have found that, in order to reduce the volume of the lubricant, it iseffective to use a lubricant of high density, and by replacing a part of the lubricant witha solid lubricant of high density, the compactibility and the reduction of the amount ofthe lubricant can be achieved at the same time, so that the present inventors havecompleted the present invention.
[20] [0020] In addition, as a result of studies on the insulating coating covering the surfaceof the soft magnetic powder, the present inventors have found that an inorganicinsulating coating, particularly a phosphoric acid-based coating, has lubricity. Thepresent inventors have also found that reduction of the amount of the lubricant can beachieved more effectively by adopting a soft magnetic powder coated with a phosphoricacid-based coating as the material for a powder magnetic core.
[21] [0021] The powder mixture for powder magnetic core of the present invention is formedby mixing a soft magnetic powder coated with an insulating coating, and a lubricant anda solid lubricant as a lubricant. Hereinafter, embodiments of the present invention willbe described in detail in the order of a soft magnetic powder, an insulating coating, alubricant, and a solid lubricant. However, the present invention is not limited to theseembodiments.
[22] [0022] (Soft Magnetic Powder) As the soft magnetic powder, an iron-based soft magnetic powder can be exemplified. The iron-based soft magnetic powder is a ferromagnetic metal powder,specifically, pure iron powder, iron-based alloy powder (Fe-Al alloy, Fe-Si alloy,sendust, perrnalloy, etc.), amorphous powder, or the like.
[23] [0023] Such a soft magnetic powder can be obtained by, for example, preparing fineparticles by an atomizing method, reducing the fine particles, and then pulverizing theparticles, or the like. In the present embodiment, it is possible to exert the effect of thesoft magnetic powder regardless of particle size distribution as long as the particle sizeis used in principle for ordinary powder metallurgy.
[24] [0024] However, the present embodiment is intended to simultaneously improve thecompressibility at the time of molding into a compact while suppressing apredeterrnined iron loss. Therefore, the iron-based soft magnetic powder to be used ispreferably an iron-based soft magnetic powder containing a component having a largeparticle size (for example, a particle size of 250 um or more and 600 um or less) in anamount somewhat more than usual. For example, an iron-based soft magnetic powderhaving a particle size distribution as shown in Table l can be exemplified.
[25] [0025] The particle size distribution of the iron-based soft magnetic powder shown inTable l can be obtained by sieving according to "Method for Deterrnination of SieveAnalysis of Metal Powders" stipulated by Japan Powder Metallurgy Association (J PMAPO2-l992)”. Specifically, the sieving is first performed using a sieve with an openingof 600 um. Then, the sieving is further performed by sequentially using sieves havingopenings of 250 um to 45 um corresponding to the particle sizes shown in Table 1,whereby a desired particle size distribution can be obtained.
[26] [0026] [Table 1] Particle size Degree (%)250 um or more 21.8180 - 250 um 19.7150 - 180 um 14.1106 -150 um 20.875 - 106 um 14.163 - 75 um 2.845 - 63 um 5.045 um or less 1.7
[27] [0027] (Insulating Coating)On the surface of the soft magnetic powder, an insulating coating is formed forsuppressing eddy current. This insulating coating is preferably an inorganic insulating coating. Typical examples of the inorganic insulating coating include a phosphoric 5 acid-based coating (phosphoric acid-based chemical coating), and a chromium-basedchemical coating. Particularly, the phosphoric acid-based coating has good WettabilityWith respect to the soft magnetic powder, can uniforrnly coat the surface of the softmagnetic powder, and has lubricating property. Therefore, the phosphoric acid-basedcoating is used more suitably as an insulating coating in this embodiment.
[28] [0028] The insulating coating may be an organic insulating coating made of an organicmaterial such as silicone, or may be a double coating of an organic insulating coatingmade of an organic material such as silicone and an inorganic insulating coating such asa phosphoric acid-based coating.
[29] [0029] The phosphoric acid-based coating can be formed on the surface of the softmagnetic poWder by, for example, mixing l000 parts by mass of Water, 193 parts bymass of H3PO4, 3l parts by mass of MgO, and 30 parts by mass of H3BO3; diluting themixture 20 times in Water to prepare a treatment solution for a phosphoric acid-basedcoating; mixing 5 parts by mass of this treatment solution With l00 parts by mass of thesoft magnetic poWder; and drying the mixture at 200°C in the atmosphere. Thethickness of the phosphoric acid-based coating is l0 to l00 nm.
[30] [0030] (Lubricant) A lubricant among the lubricants to be mixed at the time of compressionmolding may be, for example, an organic lubricant consisting of an organic compoundhaving a straight chain (-CH2-) structure With l2 or more carbon atoms. An organiclubricant such as a hydrocarbon type, a fatty acid type, a higher alcohol type, analiphatic amide type, a metal soap type, and an ester type, in addition to a metal stearatesuch as zinc stearate can be exemplif1ed, and specif1cally, the following organiclubricants can be included.
[31] [0031] Examples of the hydrocarbon-based lubricant include liquid paraffin, paraffinWax, and synthetic polyethylene Wax. Examples of the fatty acid-based and higheralcohol-based lubricants include stearic acid and stearyl alcohol, Which are relativelyinexpensive and have loW toxicity.
[32] [0032] Examples of the aliphatic amide-based lubricant include fatty acid amides suchas stearamide, oleamide, and erucamide, and alkylene fatty acid amides such asmethylene bisstearic acid amide and ethylene bisstearic acid amide.
[33] [0033] As the metallic soap-based lubricant, a metal stearate among metal soaps ismainly used, and zinc stearate, calcium stearate, lithium stearate or the like may beused.
[34] [0034] Examples of ester-based lubricants include stearic monoglyceride of fatty acid alcohol esters.
[35] [0035] In the present embodiment, as the lubricant, one or more of the above-mentionedorganic lubricants can be selected to be used.
[36] [0036] The content of these lubricants in the powder mixture for powder magnetic coreof the present embodiment is set to 01% by mass or more and 0.8% by mass or less.When the content is less than 0. l% by mass, seizing with a mold occurs during powdercompacting. On the other hand, when the content exceeds 0.8% by mass, the compactdensity decreases, resulting in failure to obtain a powder magnetic core excellent inmagnetic properties.
[37] [0037] (Solid Lubricant) A solid lubricant to be mixed together with the lubricant in powder compactingmay be for example, an inorganic lubricant consisting of an inorganic compound havinga density of 4.0 g/cm3 or more. Specific examples thereof include molybdenumdisulf1de (MoSg) and zinc oxide (ZnO). In the present embodiment, as the solidlubricant, one or more of the above-mentioned inorganic lubricants can be selected to beused.
[38] [0038] Among the lubricants, if the lubricant density is 2.0 g/cm3 or less but the solidlubricant density is not twice or more the lubricant density, the reduction of the amountof the lubricant cannot be achieved effectively. For this reason, the solid lubricantdensity is set to 4.0 g/cm3 or more.
[39] [0039] The particle size of the solid lubricant is preferably 20 nm or more but 20 um orless. If the particle size of the solid lubricant is less than 20 nm, the solid lubricantenters the unevenness of the surface of the soft magnetic powder or the gaps betweenthe soft magnetic powders, and thus the lubrication fi1nction cannot be exhibited. Onthe other hand, when the particle size of the solid lubricant exceeds 20 um, the numberof particles of the solid lubricant decreases, which makes it impossible to contribute tothe reduction of the friction between the soft magnetic powders, as well as to thereduction of the friction between the soft magnetic powder and the mo ld.
[40] [0040] The content of these solid lubricants in the powder mixture for powder magneticcore of the present embodiment is 0.0l% by mass or more and 0.2% by mass or less.When the content is less than 0.0l% by mass, the replacement of the lubricant with thesolid lubricant becomes insufficient, and the direct current magnetic property cannot beimproved. On the other hand, when the content exceeds 0.2% by mass, the totalamount of the lubricant to be added to maintain the extractability is increased, so thecompact density is reduced, resulting reduction of the saturation magnetic flux density.[004l] (Powder Magnetic Core) Further, the powder magnetic core of the present embodiment can be formed by compression molding in a mold using a powder mixture for powder magnetic core, which is obtained by mixing a lubricant, a solid lubricant, and a soft magnetic powdercoated with an insulating coating, and then by heat annealing.
[42] [0042] Although the present specification discloses techniques of various aspects asdescribed above, main techniques among them are summarized below.
[43] [0043] The powder mixture for powder magnetic core according to an aspect of thepresent invention is a powder mixture for powder magnetic core obtained by mixing alubricant, a solid lubricant, and a soft magnetic powder coated with an insulatingcoating, in which the lubricant content is 01% by mass or more and 0.8% by mass orless, and the solid lubricant content is 0.01% by mass or more and 0.2% by mass or less.
[44] [0044] With such a configuration, the compact density can be increased even when theintemal lubrication molding is adopted in the production of a powder magnetic core, sothat a powder magnetic core excellent in magnetic properties can be obtained.
[45] [0045] In addition, the insulating coating is preferably a phosphoric acid-based coating.
[46] [0046] The lubricant is preferably an organic lubricant consisting of an organiccompound having a straight chain structure with 12 or more carbon atoms, and the solidlubricant is preferably an inorganic lubricant consisting of an inorganic compoundhaving a density of 4.0 g/cm3 or more. As a result, it is considered that the amount oflubricant can be effectively reduced, and the above effects can be more reliablyobtained.
[47] [0047] The solid lubricant is preferably in the form of a powder having a particle size of20 nm or more and 20 um or less. Thereby, the lubrication fi.1nction can be effectivelyexhibited, and the friction between the soft magnetic powders and the friction of the softmagnetic powder against the mold can be effectively reduced.
[48] [0048] The powder magnetic core according to another aspect of the present inventionis a powder magnetic core obtained by compression molding of the powder mixture forpowder magnetic core, followed by heat annealing.
[49] [0049] Hereinafter, the present invention will be described in more detail with referenceto examples. The present invention is not limited to the following examples, and canbe implemented with appropriate modif1cations within the scope adaptable to the gist ofthe present invention, and all those modifications are included in the technical scope of the present invention.
[50] [0050] As a soft magnetic powder, pure iron powder (MAGMEL (registered trademark)ML35N, manufactured by Kobe Steel, Ltd.) was used to form a phosphoric acid-basedcoating which serves as an insulating coating on its surface. For forming thephosphoric acid-based coating, 1000 parts by mass of water, 193 parts by mass ofH3PO4, 31 parts by mass of MgO, and 30 parts by mass of H3BO3 were mixed as atreatment solution for the phosphoric acid-based coating to prepare a stock solution.The stock solution, whose concentration was suitably diluted up to 20 times with waterto change the electric resistance, was used as a treatment solution. Five parts by massof the treatment solution was mixed with 100 parts by mass of pure iron powder, anddried at 200°C in the atmosphere to form a phosphoric acid-based coating on the surfaceof the pure iron powder.
[51] [0051] Thereafter, the pure iron powder having the phosphoric acid-based coatingformed on the surface obtained above, a lubricant (stearamide (18 carbon atoms) orlauramide (12 carbon atoms)), and a solid lubricant (ZnO (density: 5.6 g/cm3) having aparticle size of 0.5 um or MoSg (density 5.06 g/cm3) having a particle size of 0.5 um)only in inventive examples were mixed while varying the contents as shown in Table 2,and then the mixture was subjected to powder compacting by intemal lubricationmolding to prepare a powder magnetic core.
[52] [0052] The compact density, extraction pressure, magnetic perrneability and magneticflux density of each of the prepared various powder magnetic cores were measured.[0053] The mass and size of a cuboid test piece as formed (before heat treatment) wasmeasured to calculate the compact density from the volume and the mass. The size ofthe cuboid test piece is 12.7 mm >< 31.75 mm >< approximately 5 mm thick, and thepowder mass (single weight) to be filled is 15 g.
[54] [0054] The thickness of the cuboid test piece was set to "approximately" because thethickness varies depending on the compacting pressure. The compact density shownin Table 2 is a compact density when the compacting pressure is 900 MPa. The heightof a columnar compact and the thickness of a ring-shaped test piece to be describedhereinafter are also set to "approximately" for the same reason.
[55] [0055] Three cylindrical compacts having a diameter of 25 mm >< a height ofapproximately 25 mm and having a single weight of 83 g were prepared at a compactingpressure of 588 MPa, and the pressure at the time of extraction was measured. Theextraction pressure is an average value of such pressure. This extraction pressureneeds to be 30 MPa or less.
[56] [0056] A ring-shaped test piece having an outer diameter of 45 mm >< an inner diameter of 33 mm >< a thickness of approximately 5 mm, and having a single weight of 31 g was prepared, he1d in air at 350°C for 20 minutes, and then air-coo1ed. The magneticperrneability and magnetic flux density of this ring-shaped test piece were measuredusing a magnetic measuring device manufactured by Metron, Inc. The magneticperrneabi1ity herein refers to a maximum magnetic perrneability, and was measured witha primary winding number 200, a secondary winding number 50, and a maximumexcitation magnetic field 10000 A/m. In addition, the magnetic flux density refers to amagnetic flux density at the excitation magnetic f1e1d of 10000 A/m.
[57] [0057] Table 2 and FIGS. 1 to 3 show the compact density, extraction pressure,magnetic perrneability and magnetic flux density obtained by these measurements.The compact density shown in Tab1e 2 is a compact density when the compactingpressure was 900 MPa. In addition, the test data shown in Tab1e 2 and the test datashown in FIGS. 1 to 3 differ slightly due to different batches of tests.
[58] [0058] 1161516 2] Lubricant Solid lubricant Üf Cdïïlåïßt Extraction pressure Magnetic Maâgílsíícl flux Spæific SpeøiesO/o by mESS % by mâSS % by mass g/Cmay MPa permöabflity T y Lubricant Solid lubflcant(kmparafive 0,24 _ 0.24 7.60 31 425 1.61 steafamiae _Example 1Cêfaïšïgše 0,26 _ 0.26 7.59 3 1 414 1 .60 steammide _Comparative .Exmple 3 0.28 _ 0.28 7.57 29 406 1.60 sfeafamme _Comparative ,Example 4 0.3 _ 0,3 7.54 26 351 1.52 sreammae _mvenfive 0.2 0.1 0,3 7.57 27 437 1.58 steafamiae znoExample 1hmmm 0.2 0.1 0.3 7.56 29 400 1.56 sfeafamiae MoszExample 2mvemwe 0.18 0.1 0.28 7.57 28 494 1.60 sfearamiae znoExample 3mmm 0,18 0.2 0.38 7.54 24 474 1.59 sreafamiae znoExample 4Cgfifïfšïšiše 0,28 _ 0.28 7.49 24 440 1.56 Laummiae _hmmm 0.27 0.01 0.28 7.50 24 449 1.57 Lamamifie znoExample 5mmm 0.255 0,025 0.28 7.51 24 445 1.56 Laummide znoExample 6mvermve 0,23 0.05 0.28 7.52 25 443 1.56 Laufamide znoExample 7”Vem” 0.205 0.075 0.28 7.54 26 445 1.57 Laufamide znoExample 8Invemwe 0.18 0.1 0.28 7.54 27 442 1.57 Lamamifie znoExample 9 11
[59] [0059] (Relationship Among Compact Density, Magnetic Perrneability and MagneticFlux Density) According to Table 2 and FIG. 1, when comparing Comparative Example 4with Inventive Example 1 in which the total mass of the lubricant is 0.3% by mass, thecompact density in Inventive Example 1 in which a part of the lubricant is replaced witha solid lubricant of high density from the lubricant is higher than that in ComparativeExample 4.
[60] [0060] Also, according to Table 2 and FIG. 2, when comparing Comparative Example 4with Inventive Example 1, the magnetic perrneability and the magnetic flux density inInventive Example 1 in which a part of the lubricant is replaced by a solid lubricant ofhigh density from the lubricant are higher than that in Comparative Example 4. Fromthe test results, it can be understood that the magnetic perrneability and the magneticflux density are improved when the compact density is increased.
[61] [0061] (Influence of Particle Size of Solid Lubricant) FIG. 3 shows an influence of the particle size of the solid lubricant (zinc oxide)in Inventive Example 1 on the compact density. From FIG. 3 , it can be seen that thecompact density in Inventive Example 1 was increased irrespective of the particle sizeof the zinc oxide, as compared with Comparative Example 4 in which all of thelubricant was used as a lubricant.
[62] [0062] Particularly, when the particle size of zinc oxide is 20 nm (0.02 um), 0.5 um,and 11 um, the compact density is higher than that of Comparative Example 4 at allcompacting pressures. Among them, it can be said that zinc oxide having a particlesize of approximately 0.5 um is most preferable.
[63] [0063] The particle size of zinc oxide can be measured with a measuring instrument (forexample, Microtrack) using laser diffraction. The above-mentioned particle sizeshows a particle size D50 of 50% in terms of production degree.
[64] [0064] (Reduction Effect of Extracting Pressure by Phosphoric Acid-Based Coating) A soft magnetic powder and 0.3% by mass of stearamide as a lubricant weremixed and compression-molded at a compacting pressure of 600 MPa to prepare acylindrical compact having a diameter of 25 mm >< a height of approximately 25 mm,and the pressure and the cornpanttt derisity' at the tirne Lif extracting the compëtct wererneasured. The soft magnetic powders used in the test were of three types including asample No. 1 in which no coating was formed on its surface, a sample No. 2 which wassubjected to water treatment to form an oxide coating on its surface, and a sample No. 3having a phosphoric acid-based coating formed on its surface. The test results areshown in Table 3. 12
[65] [0065] [Table 3] No. Coating Compact Clgensíty Extraction pressure MPag/ cm1 None 7.26 3 0. . 50 or more(Cancellation of measurement2 Oxlde coanng 720 because of unable extraction)3 Phosphoric acid-based 722 21coating
[66] [0066] According to Table 3, the extraction pressure of No. 1 having no coating on thesurface of the soft magnetic powder was 30 MPa, whereas No. 2 in which an oxidecoating was forrned on the surface of the soft magnetic powder by water treatment couldnot extract the compact even if the extraction pressure was 50 MPa. On the other hand,the extraction pressure of No. 3 in which a phosphoric acid-based coating was formedon the surface was 21 MPa, and thus it can be understood that such formation of thephosphoric acid-based coating on the surface of the soft magnetic powder is effective onthe reduction of the extraction pressure.
[67] [0067] Generally, when forming a sintered part or the like, a lubricant of 0.5% by massor more, preferably 0.75% by mass or more is usually mixed with the soft magneticpowder. However, since an inorganic insulating coating such as a phosphoricacid-based coating has lubricity, it was confirmed that even if the lubricant was reducedto 0.3% by mass or less, the extraction pressure was low and the compact density couldbe improved.
[68] [0068] It is considered that the solid lubricant is poor in lubricity because the solidlubricant has a higher melting point than the organic lubricant used as a lubricant anddoes not melt during compression molding. However, since the inorganic insulatingcoating such as the phosphoric acid-based coating has lubricity, as in Inventive Example4 of Table 2, addition of 0.2% by mass of a solid lubricant having poor lubricity doesnot lead to an increase in extraction pressure.
[69] [0069] (Effect of Solid Lubricant Content) From Table 2, when comparing Comparative Example 5 and InventiveExamples 5 to 9 in which the total mass of the lubricant was all 028% by mass, it canbe found that the compact density, magnetic perrneability, and magnetic flux densitywere improved even if the content of 0.0l% by mass is substituted with a solid lubricantfrom a lubricant. In addition, even when the content of 0.l% by mass is substitutedwith a solid lubricant, it can be found that the compact density, magnetic perrneability, and magnetic flux density were improved at the extraction pressure which is within an 13 allowable range of 30 MPa or less.
[70] [0070] Even if 02% by mass of a solid lubricant is added, such amount is effective for improving the compact density, magnetic perrneability, and magnetic flux density.
[71] [0071] The present application is based on Japanese Patent Application No. 2015-113915 filed on June 4, 2015, the contents of Which are included in the presentapplication.
[72] [0072] The present invention has been adequately and suff1ciently described through theembodiments in the foregoing With reference to the draWings and the like in order to express the present invention. HoWever, it should be recognized that a person skilledin the art can easily change and/or modify the embodiments described above.
[73] [0073] The present invention has a Wide range of industrial applicability in the technicalfield of a powder mixture for poWder magnetic core, as Well as in the technical field of a poWder magnetic core. 14

权利要求:
Claims (5)
[1] 1. l. A powder mixture for powder magnetic core, obtained by mixing a lubricant, asolid lubricant, and a soft magnetic powder coated with an insulating coating, wherein alubricant content is 0.l% by mass or more and 0.8% by mass or less and a solid lubricant content is 0.0l% by mass or more and 02% by mass or less.
[2] 2. The powder mixture for powder magnetic core according to claim l, wherein the insulating coating is a phosphoric acid-based coating.
[3] 3. The powder mixture for powder magnetic core according to claim l, whereinthe lubricant is an organic lubricant consisting of an organic compound having a straightchain structure with l2 or more carbon atoms, and the solid lubricant is an inorganic lubricant consisting of an inorganic compound having a density of 4.0 g/ cm3 or more.
[4] 4. The powder mixture for powder magnetic core according to claim l, whereinthe solid lubricant is in the forrn of a powder having a particle size of 20 nm or more and 20 um or less.
[5] 5. A powder magnetic core produced by compression mo lding of the powder mixture for powder magnetic core according to any one of claims l to 4, followed by heat annealing.

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CN111065474A|2020-04-24|Method for manufacturing dust core and raw material powder for dust core

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SE1551331A1|2015-10-15|Iron powder for dust core

同族专利:

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公开号 | 公开日

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CA2986885A1|2016-12-08|

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CA2986885C|2021-08-24|

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SE541728C2|2019-12-03|

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KR20180015712A|2018-02-13|

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JP2017004992A|2017-01-05|

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CN107615411A|2018-01-19|

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WO2016194525A1|2016-12-08|

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US10923257B2|2021-02-16|

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US20180182520A1|2018-06-28|

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CN107615411B|2021-04-02|

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法律状态:

优先权:

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申请号 | 申请日 | 专利标题

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JP2015113915A|JP2017004992A|2015-06-04|2015-06-04|Mixed powder for powder magnetic core and powder magnetic core|

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PCT/JP2016/063171|WO2016194525A1|2015-06-04|2016-04-27|Powder mixture for powder magnetic core, and powder magnetic core|

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