JP2009228108A - Powder for metallurgy, and method for manufacturing powder for metallurgy - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide powder for metallurgy which has satisfactory flowability, can be filled up with high density, and can improve moldability, and a method for manufacturing the powder for metallurgy. <P>SOLUTION: The powder for metallurgy includes first powder 10 and second powder 20. and the mass ratio of the second powder 20 to the first powder 10 is 1 to ≤7/3. The first powder 10 includes a plurality of first particles and a lubricant 13 covering the surfaces of the plurality of the first particles. The second powder 20 includes a plurality of second particles not covered with the lubricant on the surfaces. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a metallurgical powder and a method for producing the metallurgical powder, and, for example, to a metallurgical powder used for a dust core and a method for producing the metallurgical powder.

  Conventionally, when a metallurgical powder is compacted in a mold to obtain a molded body having a predetermined shape, friction occurs between the interface between the mold wall surface and the metallurgical powder particles, or between the metallurgical powder particles. The lubricant is applied to the mold. However, when the mold has a complicated shape, there is a problem that a portion where the lubricant is not applied is generated on the mold wall surface, and seizure occurs between the mold wall surface and the molded body.

  Also, the metal powder can be mixed with the lubricant powder and filled in the mold. However, in this case, since the lubricant is not uniformly dispersed and easily aggregated, the metallurgical powder is trapped in the solidified lubricant, and the metallurgical powder flows when the metallurgical powder is filled in the mold. There is a problem of getting worse.

  In order to uniformly disperse the lubricant in the metallurgical powder, for example, the metallurgical powder and the lubricant are mixed at a temperature equal to or higher than the melting point of the lubricant, and the lubricant is adhered to the particles of the metallurgical powder. It can also be compressed in the inside. However, in this case, the metallurgical powder particles are easily bonded (aggregated) via a lubricant to form secondary particles, and the fluidity of the iron-based powder is improved, but the packing density is poor. is there.

Furthermore, Japanese Patent Laid-Open No. 2001-192706 (Patent Document 1) discloses a method for producing a fluidity improving powder for powder metallurgy. Patent Document 1 discloses a method using a powder in which metal powder and a lubricant are mixed at a temperature not lower than 50 ° C. and not higher than 5 ° C. below the melting point of the lubricant.
JP 2001-192706 A

  However, in Patent Document 1, the lubricant may be softened by heating and become sticky. In this case, as in the conventional method described above, the secondary particles of the fluidity improving powder particles for powder metallurgy are used. There is a problem of inviting particles. Moreover, if the adhesiveness does not appear, there is a problem that seizure occurs between the mold and the molded body as in the case of simple mixing without a lubricant.

  Accordingly, an object of the present invention is to provide a metallurgical powder and a method for producing a metallurgical powder that have good fluidity, can be filled at a high density, and can improve moldability.

  The metallurgical powder of the present invention includes a first powder and a second powder, and a mass ratio of the second powder to the first powder is 1 or more and 7/3 or less. The first powder includes a plurality of first particles and a lubricant that covers the surfaces of the plurality of first particles. The second powder includes a plurality of second particles whose surfaces are not coated with a lubricant.

  The method for producing metallurgical powder of the present invention includes the following steps. A first powder including a plurality of first particles and a lubricant that covers the surfaces of the plurality of first particles is prepared. A second powder including a plurality of second particles whose surfaces are not coated with a lubricant is prepared. The first powder and the second powder are mixed so that the mass ratio of the second powder to the first powder is 1 or more and 7/3 or less.

  According to the metallurgical powder and the metallurgical powder manufacturing method of the present invention, the first powder has a lubricating function regardless of the shape of the mold because the surface of the first particles is coated with the lubricant. It can be expressed. For this reason, the first powder improves moldability. The second powder has a lower friction between the powders than the first powder because the surface of the second particles is not coated with a lubricant. For this reason, the second powder improves fluidity.

  The inventor of the present invention has a good moldability of the first powder and a good flowability of the second powder by setting the mass ratio of the second powder to the first powder to 1 to 7/3. I found out that they can be compatible.

  That is, when the mass ratio of the second powder to the first powder is 1 or more, the contact of the first particles coated with the lubricant can be suppressed. For this reason, deterioration of fluidity due to the first powder can be suppressed. Moreover, since it can suppress that 1st powder contacts, it can suppress that 1st particle | grains aggregate through a lubricant | lubricant by couple | bonding the lubricant coat | covered with a 1st powder. For this reason, the density of the molded object obtained by press-molding this metallurgical powder can be improved. On the other hand, when the mass ratio of the second powder to the first powder is 7/3 or less, the lubricant covering the first particles can exhibit a lubricating function, and the first powder is dispersed in the metallurgical powder. By doing so, the lubricant can be uniformly dispersed, so that segregation of the lubricant can be prevented. For this reason, since lubricity can be ensured when pressure-molding this metallurgical powder, moldability can be improved.

  Preferably, in the metallurgical powder, the first particle has a first iron-based particle and a first insulating coating surrounding the surface of the first iron-based particle, and the second particle is a second particle. And a second insulating film surrounding the surface of the second iron-based particle.

  Thereby, between each particle | grain can be electrically insulated in 1st and 2nd powder. For this reason, when this metallurgical powder is pressure-molded, a compact having a large electric resistance can be realized.

  Preferably, in the metallurgical powder, the first insulating coating is at least selected from the group consisting of an amorphous phosphate compound, an amorphous borate compound, an amorphous silicate compound, and an amorphous oxide. It consists of a kind of substance.

  The lubricant is coated so as to fill the recesses on the surface of the first iron-based particles, but since these substances can be coated on the surface of the iron-based particles by reducing the thickness, It can suppress that the difference of the unevenness | corrugation of the surface is reduced. For this reason, it can suppress that the quantity of the lubricant which coat | covers the surface of a 1st iron group particle | grain is reduced. Therefore, since the fall of lubrication performance can be suppressed more, a moldability can be improved more.

  According to the metallurgical powder and the metallurgical powder manufacturing method of the present invention, it has good fluidity, can be filled with high density, and can improve moldability.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

(Embodiment 1)
FIG. 1 is a cross-sectional view schematically showing a metallurgical powder in the present embodiment. As shown in FIG. 1, the metallurgical powder in the present embodiment includes a first powder 10 and a second powder, and the mass ratio of the second powder to the first powder 10 is 1 to 7 / 3 or less. The first powder 10 includes a plurality of first iron-based particles 11 and a lubricant 12 that covers the surfaces of the plurality of first iron-based particles 11. The second powder includes a plurality of second iron-based particles 21 whose surface is not coated with a lubricant. The lubricant 12 covers the surface of the first iron-based particles 11 and hardly exists between the first powder 10 and the second powder.

  The first and second iron-based particles 11 and 21 are, for example, iron (Fe), iron (Fe) -silicon (Si) alloy, iron (Fe) -aluminum (Al) alloy, iron (Fe)- Nitrogen (N) alloy, iron (Fe) -nickel (Ni) alloy, iron (Fe) -carbon (C) alloy, iron (Fe) -boron (B) alloy, iron (Fe) -cobalt ( Co) alloys, iron (Fe) -phosphorus (P) alloys, iron (Fe) -nickel (Ni) -cobalt (Co) alloys and iron (Fe) -aluminum (Al) -silicon (Si) alloys It is formed from. The first and second iron-based particles 11 and 21 may be a single metal or an alloy. Further, the first and second iron-based particles 11 and 21 may be the same material or different materials.

  The average particle diameter of the first and second iron-based particles 11 and 21 is preferably 30 μm or more and 500 μm or less. By setting the average particle diameter of the first iron-based particles 11 to 30 μm or more, the surface area of the first iron-based particles 11 can be increased, so that the amount of the lubricant 12 covering one particle can be increased. Moreover, the average particle diameter of the 1st and 2nd iron base particles 11 and 21 shall be 30 micrometers or more, and conveyance of the metallurgical powder is easy. On the other hand, when the thickness is 500 μm or less, deterioration of moldability can be prevented.

  The average particle size of the first and second iron-based particles 11 and 21 is the particle size of particles in which the sum of masses from the smaller particle size reaches 50% of the total mass in the particle size histogram, That means 50% particle size.

  In addition, since the lubricant 12 easily adheres to the concave portions on the surface of the first iron-based particles 11, the first iron-based particles 11 preferably have a surface with large irregularities.

  FIG. 2 is a cross-sectional view schematically showing another first powder in the present embodiment. The lubricant 12 covers the surface of the first iron-based particles 11. That is, the lubricant 12 may be attached only to the recesses on the surface of the first iron-based particles 11 as shown in FIG. 1, and the surface of the first iron-based particles 11 as shown in FIG. It may be attached so as to surround the entire circumference including the recess.

  The lubricant 12 may be a liquid or a solid at room temperature, but is preferably a solid with little change with time. The lubricant 12 is preferably an organic compound, such as a hydrocarbon lubricant, a fatty acid lubricant, an amide lubricant, an ester lubricant, a higher alcohol lubricant, a metal soap, and a composite lubricant. Can be used. The lubricant 12 includes paraffin wax, microwax, polyethylene wax as the hydrocarbon lubricant, stearic acid, behenic acid, 1,2-hydroxystearic acid as the fatty acid lubricant, and stearamide as the amide lubricant. Oleic acid amide, erucic acid amide, methylene bis stearic acid amide, ethylene bis stearic acid amide, ethylene bisolefinic acid amide, stearic acid monoglyceride, pentaerythritol tetrastearate, hydrogenated castor oil, stearyl stearate, Stearyl alcohol is preferably used as the higher alcohol type, and calcium stearate, zinc stearate, magnesium stearate, lead stearate and the like can be preferably used as the metal soap.

  The melting point of the lubricant 12 is preferably 150 ° C. or less, and more preferably 80 ° C. or less. By making the metal mold powder warm molding below the melting point of the lubricant, that is, below 150 ° C., the lubricant 12 can be caused to act as a liquid lubricant by self-melting. . When acting as a liquid lubricant, the lubricant 12 can be pushed out of the mold during pressure molding, so that a sufficient amount of the lubricant 12 can be secured between the molded body and the mold. Since the amount of lubricant remaining in the molded body formed by pressure molding the metallurgical powder can be reduced, the density of the molded body can be further improved. By setting the temperature to 80 ° C. or lower, the density of a molded body obtained by pressure molding the metallurgical powder can be further improved.

  The lubricant 12 is preferably contained in an amount of 0.2% by mass or more and 0.4% by mass or less based on the total mass of the first iron-based particles 11 and the second iron-based particles 21. By setting it to 0.2% by mass or more, the lubricating effect of the lubricant 12 can be expressed more. By setting the content to 0.4% by mass or less, the amount of the lubricant 12 remaining after the metallurgical powder in the present embodiment is pressure-molded does not increase, and the densification of the molded body can be realized.

  The lubricant 12 preferably has at least one of an ester bond and an amide bond, an acid value of 1 mgKOH / g or less, and a sum of a hydroxyl value and an amine value of 4 mgKOH / g or less. When the melting temperature range of the lubricant 12 has a narrow melt property, the lubricant 12 is more adhered to the details of the recesses of the first iron-based particles 11.

  Since the first powder 10 is coated with the lubricant 12 on the surface of the first iron-based particles 11, the first powder 10 can exhibit a lubricating function regardless of the shape of the mold. To play a role in improving

  Since the second powder (second iron-based particles 21 in the present embodiment) is not coated with a lubricant on the surface of the second iron-based particles 21, the friction between the powders is higher than that of the first powder 10. Is low. For this reason, the second powder plays a role of improving fluidity.

  The mass ratio of the second powder (in the present embodiment, the plurality of second iron-based particles 21) to the first powder 10 is 1 or more and 7/3 or less, and 3/2 or more and 7/3 or less. More preferred. The inventor of the present invention can achieve both good moldability of the first powder 10 and good fluidity of the second powder by setting the mass ratio of the second powder to the first powder in the above range. I found it.

  That is, when the mass ratio of the second powder (second iron-based particles 21 in the present embodiment) to the first powder 10 is less than 1, the first iron-based particles 11 coated with the lubricant 12. Is larger than the second iron-based particles 21 that are not coated with the lubricant, so that the probability that the first iron-based particles 11 that are coated with the lubricant 12 come into contact with each other increases. For this reason, the fluidity of the metallurgical powder is deteriorated by the first powder 10. In addition, when the probability that the first powders 10 come into contact with each other increases, the first iron-based particles 11 aggregate through the lubricant 12 due to the bonding of the lubricant 12 attached to the first powder 10. End up. For this reason, the density of the molded object obtained by pressure-molding this metallurgical powder will fall. When the mass ratio of the second powder to the first powder 10 is 3/2 or more, the contact of the first iron-based particles 11 coated with the lubricant 12 can be further suppressed, so that the fluidity is deteriorated. Can be further suppressed, and the density of the molded body can be improved.

  On the other hand, when the mass ratio of the second powder with respect to the first powder 10 exceeds 7/3, the lubricant 12 covering the first iron-based particles 11 is insufficient, so that the lubricating function cannot be sufficiently exhibited. For this reason, when this metallurgical powder is pressure-molded, a portion where the lubricant is not applied is generated on the mold wall surface, and seizure occurs between the mold wall surface and the molded body, resulting in poor moldability. When the mass ratio of the second powder to the first powder 10 is 7/3 or less, the lubricating performance can be exhibited, and the lubricant 12 is uniformly dispersed by dispersing the first powder 10 in the metallurgical powder. Therefore, segregation of the lubricant 12 can be prevented. For this reason, since lubricity can be ensured when pressure-molding this metallurgical powder, moldability can be improved.

  The metallurgical powder in the present embodiment may consist of only the first powder 10 and the second powder, or may further include a powder such as copper powder. In addition, the metallurgical powder in the present embodiment includes the first and second iron-based particles 11 and 21, but may include particles other than the iron-based particles.

  Then, the manufacturing method of the metallurgical powder in this Embodiment is demonstrated. FIG. 3 is a flowchart showing a method for producing metallurgical powder in the present embodiment.

  As shown in FIGS. 1 to 3, first, a first powder 10 including a plurality of first iron-based particles 11 and a lubricant 12 covering the surfaces of the plurality of first iron-based particles 11 is prepared. (Step S10).

  Specifically, for example, first iron-based particles 11 made of the material described above are prepared (step S11). Although the manufacturing method of the 1st iron base particle 11 is not specifically limited, For example, the 1st iron base particle 11 is prepared by the gas atomizing method, the water atomizing method, etc. From the viewpoint of preparing the first iron-based particles 11 having a rough surface, it is preferable to manufacture the first iron-based particles 11 by, for example, a water atomization method.

  Thereafter, the first iron-based particles 11 are heat-treated. Inside the first iron-based particles 11 before the heat treatment, there are a large number of defects such as strains and crystal grain boundaries due to thermal stress during atomization. Therefore, these defects can be reduced by subjecting the first iron-based particles 11 to heat treatment. This heat treatment may be omitted.

  Thereafter, the surfaces of the plurality of first iron-based particles 11 are coated with the lubricant 12 (step S12). The lubricant 12 is formed on the surface of the plurality of first iron-based particles 11 by the following method, for example. The plurality of first iron-based particles 11 and the lubricant 12 are mixed using a stirring mixer that can heat the inside of the mixing container. Then, the temperature in the mixing container is raised while mixing, and the lubricant 12 is melted. Thereby, the melted lubricant 12 enters the recesses on the surface of the plurality of first iron-based particles 11, and the liquid lubricant 12 oozes out between the plurality of first iron-based particles 11. Then, after a certain period of time, the temperature in the mixing container is lowered, and the lubricant 12 and the plurality of first iron-based particles 11 are continuously mixed until the lubricant 12 is solidified. Thereby, the melted lubricant 12 does not flow out from the surfaces of the plurality of first iron-based particles 11, and the plurality of first iron-based particles 11 coated with the lubricant 12 do not adhere to each other, The lubricant 12 is solidified with the concave portions on the surface of the first iron-based particles 11 being filled. As a result, as shown in FIG. 1 or 2, the lubricant 12 can be coated on the surfaces of the plurality of first iron-based particles 11.

  In addition to the case where the temperature of the mixing container is increased after starting the mixing of the plurality of first iron-based particles 11 and the lubricant 12 as described above, the temperature in the mixing container is increased to the temperature at which the lubricant 12 melts. After the temperature is raised in advance, the plurality of first iron-based particles 11 and the lubricant 12 may be added to the mixing container to start mixing.

  Further, when the plurality of first iron-based particles 11 and the lubricant 12 are mixed, the ratio of the lubricant 12 in the metallurgical powder (first powder 10) is 0.2 mass% or more and 0.4. It is preferable to adjust the mixing ratio so as to be not more than mass%.

  Furthermore, the mixing method is not particularly limited, and any of a mixer such as a V-type mixer, a vertical rolling mixer, a vibrating ball mill, a planetary ball mill, and the like can be used. It may be simply mixed at room temperature, or may be coated with the lubricant in a liquefied state by increasing the temperature and stabilized by cooling.

  Through the above steps S11 and S12, the first powder 10 shown in FIG. 1 or 2 can be prepared.

  Next, as shown in FIGS. 1-3, the 2nd powder containing the several 2nd particle | grains by which the surface is not coat | covered with the lubricant is prepared (step S20). In the present embodiment, for example, the second iron-based particles 21 made of the material as described above are prepared as the second powder (step S21). Although the manufacturing method of the 2nd iron base particle 21 is not specifically limited, For example, the 2nd iron base particle 21 is prepared by the gas atomization method, the water atomization method, etc. Further, the second iron-based particles 21 may be subjected to heat treatment in the same manner as the first iron-based particles 11.

  Next, the first powder 10 and the second powder 20 are mixed so that the mass ratio of the second powder 20 to the first powder 10 is 1 or more and 7/3 or less (step S30). The mass ratio of the second powder 20 to the first powder 10 is 1 or more and 7/3 or less, and preferably 3/2 or more and 7/3 or less.

  The method of mixing is not particularly limited. For example, the ratio of the first powder 10 and the second powder (second iron-based particles 21 in the present embodiment) described above in a mixing container such as a V-type mixer is described above. Mix with.

  By performing the above steps S10 to S30, the metallurgical powder shown in FIG. 1 can be manufactured. In the case of producing a molded body using this metallurgical powder, the following steps are further performed.

  Next, a compact is obtained by pressure-molding the metallurgical powder (step S40). Specifically, the obtained metallurgical powder is put into a mold and, for example, press-molded at a pressure of 390 MPa to 1500 MPa. Note that the pressure forming atmosphere is preferably an inert gas atmosphere or a reduced pressure atmosphere. In this case, oxidation of the metallurgical powder by oxygen in the atmosphere can be suppressed. Further, it is preferable to heat the mold to a temperature equal to or higher than the melting point of the lubricant 12.

  Next, the molded body obtained by pressure molding is heat-treated (step S50). Specifically, for example, heat treatment is performed at 550 ° C. or higher. Since many defects are generated in the molded body that has been subjected to pressure molding, these defects can be removed by heat treatment. In addition, step S50 which performs this heat treatment may be omitted. A molded object can be manufactured by implementing the above steps S10 to S50.

  Then, the effect of this Embodiment is demonstrated, comparing the metallurgical powder in this Embodiment with the conventional metallurgical powder.

  FIG. 4 is a cross-sectional view schematically showing a conventional metallurgical powder. The conventional metallurgical powder shown in FIG. 4 includes a plurality of iron-based particles 111 and a lubricant 112 mixed with the plurality of iron-based particles 111. In this metallurgical powder, as shown in FIG. 4, the lubricant 112 exists between the plurality of iron base particles 111, and most of the lubricant 112 is not in contact with the iron base particles 111. Further, even when the lubricant 112 is in contact with the iron-based particles 111, the lubricant 112 attached to the recesses of the iron-based particles 111 is hardly present.

  Conventional metallurgical powder is produced by mixing iron-based particles 111 with a lubricant 112. However, with this method, it is difficult to uniformly disperse the lubricant 112 in the metallurgical powder. For this reason, the conventional metallurgical powder has a problem that the fluidity of the metallurgical powder deteriorates when the metal mold is filled. In addition, the lubricant may be softened by heating, resulting in stickiness, and there is a problem that the particles of the metallurgical powder are made secondary particles. Moreover, if the adhesiveness does not appear, there is a problem that seizure occurs between the mold and the molded body as in the case of simple mixing without a lubricant.

  On the other hand, in the metallurgical powder of the present embodiment, in the first powder 10, the lubricant 12 is in contact with most of the recesses of the first iron-based particles 11, and the first powder 10 and the second powder Almost no lubricant 12 exists between the powder (second iron-based particles 21 in the present embodiment).

  In the metallurgical powder in the present embodiment, the mass ratio of the second powder to the first powder 10 is 1 or more and 7/3 or less. Therefore, the good moldability of the first powder 10 and the second powder It is compatible with the good fluidity of the powder.

  Specifically, when the mass ratio of the second powder to the first powder is 1 or more, the contact of the first iron-based particles 11 covered with the lubricant 12 can be suppressed. For this reason, deterioration of fluidity due to the first powder can be suppressed. Moreover, since it can suppress that 1st powder contacts, the 1st iron base particle | grains 11 pass through a lubrication agent, when the lubrication agent which coat | covers the several 1st iron base particle | grains 11 couple | bonds. Aggregation can be suppressed. Moreover, since fluidity | liquidity can be improved, the filling property of the metallurgical powder can be improved. For this reason, the density of the molded object obtained by press-molding this metallurgical powder can be improved. As a result, it is possible to reduce the size of equipment for pressure forming such as a mold.

  On the other hand, when the mass ratio of the second powder to the first powder is 7/3 or less, the lubricant 12 covering the plurality of first iron-based particles 11 is included to such an extent that a lubricating function can be exhibited. Moreover, since the lubricant 12 can be uniformly dispersed by dispersing the first powder 10 in the metallurgical powder, segregation of the lubricant 12 can be prevented. For this reason, since lubricity can be ensured when this metallurgical powder is pressure-molded, seizure between the mold wall surface and the molded body can be prevented, and the moldability can be improved.

(Embodiment 2)
FIG. 5 is a cross-sectional view schematically showing the metallurgical powder in the present embodiment. The metallurgical powder in the present embodiment shown in FIG. 5 has basically the same configuration as the metallurgical powder in the first embodiment shown in FIG. 1, but the first and second iron-based particles 11. The first and second insulating coatings 13 and 23 are formed on the surfaces of the first insulating coating 13 and the lubricant 12 is formed so as to cover the surface of the first insulating coating 13.

  Specifically, as shown in FIG. 5, the metallurgical powder includes a first powder 10 and a second powder 20, and the mass ratio of the second powder 20 to the first powder 10 is 1 or more. 7/3 or less. The first powder 10 covers a plurality of first iron-based particles 11, a first insulating film 13 that covers the surfaces of the plurality of first iron-based particles 11, and a surface of the first insulating film. And a lubricant 12. The second powder 20 includes a plurality of second iron-based particles 21 and a second insulating film 23 that covers the surfaces of the plurality of second iron-based particles 21, and the plurality of second insulating films 23. The surface is not coated with a lubricant.

  Since first and second iron-based particles 11 and 21 are the same as in the first embodiment, description thereof will not be repeated. In the present embodiment, the coercive force when pressure molding can be reduced by setting the average particle size of the first and second iron-based particles 11 and 21 to 30 μm or more. By setting the average particle size to 500 μm or less, eddy current loss can be reduced.

  The first and second insulating coatings 13 and 23 function as an insulating layer between the first and second iron-based particles 11 and 21. By covering each of the first and second iron-based particles 11 and 21 with each of the insulating coatings 13 and 23, the electrical resistivity ρ of the dust core obtained by pressure-molding the metallurgical powder is increased. be able to. Thereby, it can suppress that an eddy current flows between the 1st and 2nd iron base particles 11 and 21, and can reduce the eddy current loss of a powder magnetic core.

  The average film thickness of the first insulating film 13 is preferably thinner than the thickness of the second insulating film 23, and is preferably 100 nm or less, for example. In the case of 100 nm or less, the affinity with the lubricant 12 is increased, and the lubricant 12 tends to adhere to the recesses of the first iron-based particles 11. The insulating coating 13 covers the surface of the first iron-based particles 11 and is preferably made to have a substantially uniform thickness in order to take advantage of the uneven shape of the first iron-based particles 11. The lower limit of the first insulating coating 13 is, for example, 10 nm or more from the viewpoint of effectively suppressing eddy current loss.

  The average film thickness of the second insulating film 23 is preferably larger than the thickness of the first insulating film 13, and is preferably more than 100 nm and 1000 nm or less, for example. When the thickness of the second insulating film 23 is thicker than that of the first insulating film 13, the second insulating film 23 can improve the heat resistance of the first insulating film 13. When the thickness exceeds 100 nm, the electric resistance can be maintained, the eddy current loss can be reduced, and the low eddy current loss can be maintained even if the heat treatment necessary for reducing the hysteresis loss is performed. That is, both sufficient heat resistance and insulation can be achieved. On the other hand, in the case of 1000 nm or less, a decrease in magnetic flux density can be suppressed.

  The average film thickness is determined by composition analysis (TEM-EDX: transmission electron microscope energy dispersive X-ray spectroscopy) and inductively coupled plasma-mass spectrometry (ICP-MS). Considering the amount of element to be obtained, the equivalent thickness is derived, and further, the film is directly observed by a TEM photograph, and it is determined by confirming that the order of the equivalent thickness derived earlier is an appropriate value. Means something. If the thickness of the coating cannot be specified, such as when the constituent elements of the main coating are alloyed into the iron-based particles or are the same as the constituent elements of another coating, 10 TEM photographs with a cross-sectional range of 500 nm or more are observed. The average film thickness may be determined by observing more than one part.

  The first insulating coating 13 is made of, for example, at least one substance selected from the group consisting of an amorphous phosphate compound, an amorphous borate compound, an amorphous silicate compound, and an amorphous oxide. It is preferable. Examples of the amorphous oxide include an oxide of at least one substance selected from the group consisting of Al, Si, Ti, Mg, Ca, and Fe. Examples of such materials include iron phosphate, manganese phosphate, zinc phosphate, calcium phosphate, silicon oxide, titanium oxide, aluminum oxide, and zirconium oxide. Since these materials are excellent in insulation, eddy currents flowing between the first and second iron-based particles 11 and 21 can be more effectively suppressed. The first insulating coating 13 is preferably a single layer.

  The second insulating coating 23 is preferably made of at least one of an inorganic compound and an organic resin, for example. Examples of the inorganic compound include the materials described above. Examples of the organic resin include a silicone resin and a polyimide resin.

  FIG. 6 is a cross-sectional view schematically showing another second powder in the present embodiment. As shown in FIG. 5, the second powder 20 may be composed of one layer of insulating coating 23, or may be composed of two layers of insulating coating as shown in FIG. 6.

  As shown in FIG. 6, when the second insulating film 23 includes two insulating films, the second insulating film 23 includes an amorphous phosphate compound, an amorphous borate compound, A first layer 23a made of at least one material selected from the group consisting of an amorphous silicate compound and an amorphous oxide, and a group formed on the first layer 23a and made of a silicone resin and a metal oxide It is preferable to have the second layer 23b made of at least one material selected from the above. Thereby, since the 2nd insulating film 23 contains the 1st layer 23a excellent in deformation | transformation followability, and the 2nd layer 23b excellent in heat resistance, the 2nd powder 20 has the outstanding characteristic. be able to.

  The second insulating film 23 may be composed of three or more insulating films. When the second insulating film 23 is composed of a plurality of layers of insulating films, the thickness of the second insulating film 23 is the total thickness of the respective layers.

  In the first powder 10, the lubricant 12 is formed so as to surround the surfaces of the plurality of first insulating coatings 13. FIG. 7 is a cross-sectional view schematically showing another first powder in the present embodiment. As shown in FIG. 6, the lubricant 12 may be attached only to the concave portion on the surface of the first insulating coating 13, and includes the concave portion on the surface of the first insulating coating 13 as shown in FIG. 7. You may adhere so that the perimeter may be surrounded.

  Then, the manufacturing method of the metallurgical powder in this Embodiment is demonstrated. FIG. 8 is a flowchart showing a method for producing metallurgical powder in the present embodiment.

  As shown in FIGS. 6 to 8, first, a plurality of first iron-based particles 11, a first insulating film 13 covering the surfaces of the plurality of first iron-based particles 11, and a first insulating film First powder 10 including lubricant 12 covering 13 is prepared (step S10).

  Specifically, as in Embodiment 1, first iron-based particles 11 are prepared (step S11). Note that the first iron-based particles 11 may be subjected to heat treatment. Then, the 1st insulating coating 13 is coat | covered on the surface of the 1st iron base particle 11 (step S13). The first insulating coating 13 can be formed, for example, by subjecting the first iron-based particles 11 to a phosphate chemical conversion treatment. Moreover, as a formation method of the 1st insulating film 13 which consists of phosphates, the sol-gel process using a solvent spraying or a precursor other than a phosphate chemical conversion process can also be utilized. Moreover, you may form the 1st insulating film 13 which consists of a silicon type organic compound. The first insulating coating 13 can be formed by wet coating using an organic solvent, direct coating using a mixer, or the like. Thereby, the some composite magnetic particle which formed the 1st insulating film 13 in each surface of the some 1st iron base particle 11 is obtained.

  Thereafter, the surfaces of the plurality of first insulating coatings 13 are coated with the lubricant 12 (step S12). In this step S12, a plurality of first insulating coatings are used in the same manner as in the first embodiment, using the first iron-based particles 11 on which the first insulating coatings 13 are formed instead of the first iron-based particles 11. 13 surfaces are coated with a lubricant 12. Thereby, the plurality of first iron-based particles 11 shown in FIG. 5 or 7, the first insulating coating 13 covering the surfaces of the plurality of first iron-based particles 11, and the first insulating coating 13 A first powder 10 containing a lubricant 12 covering the surface can be produced.

  Next, a plurality of second iron-based particles 21 and a second insulating coating 23 that covers the surfaces of the plurality of second iron-based particles 21, the surface of which is not coated with a lubricant, are second. Powder 20 is prepared (step S20).

  Specifically, as in the first embodiment, the second iron-based particles 21 are prepared (step S21). The second iron-based particles 21 may be heat treated. Thereafter, the second insulating coating 23 is coated on the surface of the second iron-based particles 21 (step S22). This step S22 is the same as step S13 for covering the first insulating coating 13 described above.

  As shown in FIG. 6, when two or more layers of the second insulating coating 23 are formed on the second iron-based particles 21, the first layer 23 a surrounding the surface of the second iron-based particles 21, And a second layer 23b surrounding the surface of the first layer 23a. In this case, the first layer 23a is made of at least one substance selected from the group consisting of an amorphous phosphate compound, an amorphous borate compound, an amorphous silicate compound, and an amorphous oxide. It is preferable that the second layer 23b is made of at least one substance selected from the group consisting of a silicone resin and a metal oxide.

  Thereby, the 2nd powder containing the some 2nd iron base particle 21 shown in FIG. 5 or FIG. 6 and the 2nd insulating coating 23 which coat | covers the surface of the 2nd iron base particle 21 can be manufactured.

  Next, as in the first embodiment, the first powder 10 and the second powder 20 are mixed so that the mass ratio of the second powder 20 to the first powder 10 is 1 or more and 7/3 or less. Mix (step S30).

  The metallurgical powder shown in FIG. 5 can be manufactured by performing the above steps S10 to S30. In the case of producing a molded body using this metallurgical powder, the following steps are further performed.

  Next, as in the first embodiment, the metallurgical powder is pressure-molded to obtain a compact (step S40).

  Next, the molded body obtained by pressure molding is heat-treated (step S50). Specifically, heat treatment is performed at a temperature of, for example, 550 ° C. or higher and a temperature equal to or lower than the thermal decomposition temperature of the first and second insulating coatings 13 and 23. Since many defects are generated in the molded body that has been subjected to pressure molding, these defects can be removed by heat treatment.

  By the above steps S10 to S50, the dust core as the molded body in the present embodiment can be manufactured.

  The metallurgical powder in the present embodiment covers the plurality of first iron-based particles 11, the first insulating coating 13 surrounding the surfaces of the plurality of first iron-based particles 11, and the first insulating coating 13. A second powder including a first powder 10 containing a lubricant 12, a plurality of second iron-based particles 21, and a second insulating coating 23 covering the surfaces of the plurality of second iron-based particles 21. The mass ratio of the second powder to the first powder 10 is 1 or more and 7/3 or less.

  Thereby, in the 1st and 2nd powders 10 and 20, between each iron base particle can be electrically insulated. For this reason, when this metallurgical powder is pressure-molded, a powder magnetic core having a large electric resistance can be realized. Such a dust core has good fluidity, can be filled at a high density, and can improve moldability. Therefore, it is preferably used for a motor core, a solenoid valve, a reactor or an electromagnetic component in general.

  In this example, the effect of the mixing ratio of the first powder and the second powder being 1 or more and 7/3 or less was examined. Specifically, the first powder and the second powder are prepared, the metallurgical powder mixed at various mass ratios is manufactured, and the molded body manufactured by pressure molding the metallurgical powder. The flow time (FR value), apparent density (AD value), and moldability were measured.

(Samples 1-10)
In Samples 1 to 10, metallurgical powders were manufactured using the manufacturing method of Embodiment 2 shown in FIG. Specifically, ABC100.30 powder made by Höganäs AB was prepared as the first iron-based particles 11 (step S11). The average particle diameter of the first iron-based particles 11 was 80 μm.

  Next, a first insulating coating 13 made of iron phosphate and having a thickness of 20 nm was formed on the surface of the first iron-based particles 11 by a bond method (step S13). In addition, the thickness of the 1st insulating film 13 was set to the average film thickness calculated | required from 30 nm converted from the quantity of the phosphorus in ICP, and the actual measurement in TEM being 10 nm-50 nm. Thereafter, WSA75 manufactured by Dainichi Chemical Co., Ltd. was prepared as the lubricant 12. The lubricant 12 is an amide wax having a melting point of 75 ° C., and the viscosity at the melting point is about 20 mPa · s. The powdery lubricant 12 and the plurality of first iron-based particles 11 on which the second insulating coating 13 was formed were put into a warm mixer and mixed. These powders were heated to 85 ° C. while mixing and kneaded while melting. Thereafter, the warm mixer was cooled to below the melting point of the lubricant 12 while kneading. Thereby, the lubricant 12 surrounding the surface of the first insulating coating 13 was formed (step S12). As a result, a first powder 10 was obtained (step S10).

  Next, as the second iron-based particles 21, ABC100.30 powder made by Höganäs AB, similar to the first iron-based particles 11, was prepared (step S21).

  Next, a first layer 23a made of aluminum phosphate and having a thickness of 150 nm was formed on the surface of the second iron-based particles 21 by a bond method. The thickness of the first layer was 100 nm in terms of the amount of phosphorus in ICP, and the average film thickness obtained from the actual measurement with TEM was 30 nm to 150 nm. Further, the second iron-based particles 21 coated with the first layer 23a and 0.3% by mass of a silicone resin (XC96-B0446 manufactured by Momentive Performance Materials) are mixed in an ethanol solvent. Then, after drying and volatilizing, the silicone resin was thermally cured by heat treatment at 150 ° C. for 1 hour in the air. Thus, the second layer 23b covering the first layer 23a is formed by a wet method, thereby including the first layer 23a having a thickness of 150 nm and the second layer 23b having a thickness of 200 nm. A second insulating film 23 was formed (step S22). This thickness was 260 nm in terms of the amount of Si in ICP, and the average film thickness obtained from the actual measurement with TEM was 120 nm to 350 nm. As a result, a second powder 20 was obtained (step S20).

  Next, for samples 2 to 10, the first powder 10 and the second powder 20 were mixed in a V-shape so that the mass ratio of the second powder 20 to the first powder 10 was as shown in Table 1 below. (Step S30). Sample 1 was only the first powder 10 without mixing the second powder 20. Thereafter, the coating amount of the lubricant 12 in the first powder 10 was adjusted to 0.3 mass%. Through the above steps S10 to S30, metallurgical powders of Samples 1 to 10 were manufactured.

(Evaluation methods)
About the obtained metallurgical powders of Samples 1 to 10, the flow time (FR value) and the apparent density (AD value) were measured. The flow time (FR value) was measured according to JIS Z 2502. The apparent density (AD value) was measured according to JIS Z 2504. These results are shown in Table 1 below. The smaller the value of the flow time (FR value), the better the fluidity, and the higher the apparent density (AD value), the higher the value.

  Moreover, about the obtained powder for compacting, the pressure of 980 Mpa was applied using the metal mold | die, and the ring-shaped molded object of outer diameter 10mm was produced with the metal mold | die heated at 80 degreeC, respectively. Then, the presence or absence of seizure between the mold wall surface and the molded body was observed. These results are shown in Table 1 below. In addition, what was not seized was judged that moldability was favorable, and what was seized was judged that shaping | molding was impossible.

（測定結果）
表１に示すように、第１の粉末に対する第２の粉末の質量比が１以上７／３以下になるように、第１の粉末と第２の粉末とを混合した試料６〜８は、金型と成形体との焼き付きがなく成形性が良好で、見かけ密度が３．１〜３．２ｇ／ｃｍ³と高く、流動性が８．２〜１１．８ｓｅｃと良好であった。

(Measurement result)
As shown in Table 1, samples 6 to 8 in which the first powder and the second powder are mixed so that the mass ratio of the second powder to the first powder is 1 or more and 7/3 or less are: There was no seizure between the mold and the molded body, the moldability was good, the apparent density was as high as 3.1 to 3.2 g / cm ³ , and the fluidity was as good as 8.2 to 11.8 sec.

In particular, Samples 7 and 8 in which the mixing ratio of the first powder and the second powder is 3/2 or more and 7/3 or less have good moldability and an apparent density of 3.1 to 3.2 g / It was as high as cm ³ and the fluidity was very good at 8.2 to 8.8 sec.

  On the other hand, Samples 1 to 3 in which the mass ratio of the first powder containing the lubricant 12 covering the first insulating coating 13 was high were good in moldability, but contained the lubricant contained therein. Since the amount was too large, the metallurgical powders of Samples 1 to 3 could not be filled in the measurement container, and the apparent density and fluidity of the powder could not be measured.

  Samples 4 and 5 having a high mass ratio of the first powder containing the lubricant 12 covering the first insulating coating 13 had good moldability and could be filled in the measurement container. Since the amount of the lubricant was too large, the apparent density was low compared to Samples 6-8, and the fluidity was very poor compared to Samples 6-8.

  Furthermore, in the samples 9 and 10 in which the mass ratio of the first powder containing the lubricant 12 covering the first insulating coating 13 was low, the contained lubricant was less than 1.2% by mass. Therefore, the lubricant was insufficient with respect to the amount of the target lubricant added, and the apparent density and fluidity were not measured.

  As described above, according to the present example, by using the metallurgical powder having a mixing ratio of the first powder and the second powder of 1 to 7/3, it has good fluidity and high density. It was confirmed that the moldability can be improved and the moldability can be improved.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is shown not by the above-described embodiment but by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

It is sectional drawing which shows typically the metallurgical powder in Embodiment 1 of this invention. It is sectional drawing which shows typically another 1st powder in Embodiment 1 of this invention. It is a flowchart which shows the manufacturing method of the powder for metallurgical in Embodiment 1 of this invention. It is sectional drawing which shows the conventional metallurgical powder typically. It is sectional drawing which shows typically the metallurgical powder in Embodiment 2 of this invention. It is sectional drawing which shows typically another 2nd powder in Embodiment 2 of this invention. It is sectional drawing which shows typically another 1st powder in Embodiment 2 of this invention. It is a flowchart which shows the manufacturing method of the metallurgical powder in Embodiment 2 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 1st powder, 11 Iron base particle, 12 Lubricant, 13 1st insulating film, 20 2nd powder, 21 2nd iron base particle, 23 2nd insulating film, 23a 1st layer, 23b Second layer.

Claims (4)

A first powder comprising a plurality of first particles and a lubricant covering the surfaces of the plurality of first particles;
A second powder comprising a plurality of second particles, the surface of which is not coated with a lubricant,
A metallurgical powder, wherein a mass ratio of the second powder to the first powder is 1 or more and 7/3 or less. The first particles include first iron-based particles and a first insulating coating that surrounds a surface of the first iron-based particles;
2. The powder for metallurgy according to claim 1, wherein the second particles include second iron-based particles and a second insulating film surrounding a surface of the second iron-based particles.   The first insulating coating is made of at least one substance selected from the group consisting of an amorphous phosphate compound, an amorphous borate compound, an amorphous silicate compound, and an amorphous oxide. Item 3. A metallurgical powder according to Item 2. Providing a first powder comprising a plurality of first particles and a lubricant covering the surfaces of the plurality of first particles;
Providing a second powder comprising a plurality of second particles whose surfaces are not coated with a lubricant;
A metallurgical powder comprising a step of mixing the first powder and the second powder so that a mass ratio of the second powder to the first powder is 1 or more and 7/3 or less. Manufacturing method.

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