JP2010013713A - Composite particle, and method for manufacturing composite particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite particle which can be simply manufactured, and to provide a method for manufacturing the composite particle. <P>SOLUTION: As for the composite particle, a part or the whole of the surface of a nucleus 6 composed of metal M (M is the one composed of Fe with inevitable impurities or the one comprising ≥80% Fe and at least one element selected from Co, Ni, B, Mn, Si, Al, Cu, Cr, Ti, V, Mo, Zr, Nb and Ga with inevitable impurities) is covered with the oxide 5 of rare earths R (R denotes at least one selected from Ce, La, Y, Nd, Pr, Dy, Tb, Sm, Gd and Yb). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a composite particle and a method for producing the composite particle, and in particular, a composite particle in which a part or all of the surface of a nucleus composed of a soft magnetic material represented by iron is coated with a rare earth oxide and The present invention relates to a method for producing composite particles.

  Composite particles with a soft magnetic metal core coated with an oxide, which is an insulator, have both high insulation properties and excellent magnetic properties. Applications in fields such as sensors and magnetoresistance are promising.

As a method for producing such composite particles, a solution containing a metal salt is sprayed into droplets, and the droplets are heated to a temperature higher than the decomposition temperature of the metal salt and higher than the decomposition temperature of the oxide. And the like (for example, see Patent Document 1).
However, in the method described in Patent Document 1, since the droplet containing the metal salt is set higher than the decomposition temperature of the metal salt, much energy is required for the decomposition of the metal salt. Further, in the method described in Patent Document 1, since a water vapor atmosphere is formed by evaporation of a solution containing a metal salt, a sufficient reduction reaction is performed when the metal is a metal that is easily oxidized, such as iron. Therefore, the production of the composite particles may be technically difficult.

  As a technique for solving such a problem, a method of obtaining composite particles by subjecting compound powder to thermal decomposition has been proposed (for example, see Patent Document 2). Patent Document 2 discloses a spherical body having an average particle diameter of 0.1 to 20 μm made of a single crystal mainly composed of Fe, and an oxide having an element having a stronger affinity for oxygen than Fe on its surface. A magnetic metal powder having a coating layer is described. Further, Patent Document 2 discloses that a magnetic metal powder is supplied by supplying a mixture of a raw material oxide powder and a powder made of an oxide constituting a coating layer to a heat treatment process supplied with a reducing gas and an inert gas. A method for producing a powder is described. Furthermore, Patent Document 2 discloses a technique for obtaining a spherical magnetic metal powder by forming a spherical product by surface tension as a product that has become droplets by melting.

  However, the method described in Patent Document 2 has a disadvantage that the dispersibility to a base material such as a resin is poor when the size of the powder is small, and the powder is dispersed in the base material. This is a problem when used as an electromagnetic wave absorbing material.

  As a method for obtaining large-sized particles, a method is proposed in which inorganic powder is granulated to a particle size of 1 μm or more and 500 μm or less, then dispersed in an oxygen-acetylene burner flame, and heated and melted to produce spherical inorganic particles. (For example, see Patent Document 3).

  In Patent Document 4, a plurality of powders having different melting points produced by using a spray dryer are supplied together with an oxidizing gas and / or an inert gas into a combustion flame, and the granular powder is melted in the combustion flame. Describes a method for producing composite particles in which a melt-processed product is obtained, and the melt-processed product is separated into a core body and a coating layer.

  Further, in Patent Document 5, a fine powder of ceramics and a scale-like metal powder are added to a metal powder having a particle size of 1 to 1000 μm, and the mixture is ground and mixed in a state where a strong compressive force is applied. A method for producing composite particles is described in which a metal powder particle is used as a core and a coating layer is formed on the surface by a mixture of metal fine powder and ceramic fine powder using mechanochemical action.

Conventionally, a combustion synthesis method has been used as a technique for synthesizing an intermetallic compound (see, for example, Patent Document 6). In Patent Document 6, as a raw material, a plurality of types of metal powders capable of forming an intermetallic compound by an exothermic reaction are used, and the step of mixing the plurality of types of metal powders and a mixture of the plurality of types of metal powders in a predetermined shape are used. Describes a method for producing an inorganic porous material, which includes a step of pressure molding and a step of igniting a part of the obtained molded body to cause a combustion synthesis reaction. In the combustion synthesis method, the compound synthesis and the sintering process can be simultaneously performed, and the intermetallic compound can be synthesized in a very short time in seconds.
JP-A-62-1807 JP 2004-91928 A Japanese Patent Laid-Open No. 10-137574 JP 2004-290730 A JP-A-5-317679 JP 2002-356706 A

However, the conventional technology has insufficient productivity, and there has been a demand for composite particles that can be easily manufactured without performing a process using a flame and a method for manufacturing the same.
This invention is made | formed in view of the said situation, Comprising: It aims at providing the composite particle which can be manufactured simply, and its manufacturing method.

  In order to obtain composite particles that can be easily produced, the present inventor has intensively studied focusing on rare earth metals, which are easily sparked, and produced an alloy composed of a metal and an oxide of a rare earth metal. The inventors have found that composite particles obtained by coating a metal with an oxide of a rare earth metal can be obtained by self-combustion (spontaneous ignition) of an alloy in an atmosphere having a concentration of 5 vol% or more. That is, the present invention relates to the following.

[1] Part or all of the surface of the nucleus composed of the metal M exhibiting ferromagnetism is at least one selected from the rare earth R (R is Ce, La, Y, Nd, Pr, Dy, Tb, Sm, Gd, Yb) A composite particle characterized by being coated with an oxide of
[2] The metal M is composed of Fe and inevitable impurities, or Fe of 80 wt% or more, Co, Ni, B, Mn, Si, Al, Cu, Cr, Ti, V, Mo, Zr, Nb The composite particle according to [1], comprising at least one element selected from Ga and inevitable impurities.
[3] The composite particle according to [1] or [2], wherein the core has a particle size of 1 μm to 500 μm.
[4] The composite particles according to any one of [1] to [3], wherein the composite particles have a particle size of 10 to 1000 μm.
[5] The composite particle according to any one of [1] to [4], wherein the metal M has an oxygen concentration of 300 to 15000 ppm and a carbon concentration of 100 to 400 ppm.
[6] The metal M is characterized by containing 200 to 1500 ppm of Mn, 250 to 800 ppm of Ni, 100 to 1400 ppm of Si, 3000 to 20000 ppm of Cu, 150 to 1500 ppm of Cr, and 300 to 1200 ppm of Co. The composite particle according to any one of [1] to [5].

[7] Part or all of the surface of the nucleus composed of metal M exhibiting ferromagnetism is at least one selected from rare earth R (R is Ce, La, Y, Nd, Pr, Dy, Tb, Sm, Gd, Yb) In the method for producing composite particles coated with oxides), an alloy MR comprising the metal M and the rare earth R is spontaneously ignited in an atmosphere having an oxygen concentration of 5 vol% or more, thereby partially Alternatively, a method for producing composite particles, wherein the whole is coated with the rare earth R oxide.
[8] The metal M is composed of Fe and inevitable impurities, or Fe of 80 wt% or more, Co, Ni, B, Mn, Si, Al, Cu, Cr, Ti, V, Mo, Zr, Nb The method for producing composite particles according to [7], which contains at least one element selected from Ga and inevitable impurities.

Furthermore, in order to solve the above-mentioned problems, the present inventor has conducted extensive research, and in order to efficiently self-combust the MR alloy (spontaneous ignition), the MR alloy is crushed so as to generate many sparks from the MR alloy. It was found that the MR alloy may be spontaneously ignited using the spark generated from the MR alloy as an ignition source.
[9] The method for producing composite particles according to [7] or [8], wherein the alloy MR is spontaneously ignited by crushing the alloy MR.
[10] The method for producing composite particles according to [9], wherein the alloy MR is crushed to a particle size of 10 to 1000 μm.
[11] The method for producing composite particles according to [9] or [10], wherein the alloy MR is crushed to generate fine powder having a particle size of 0.01 to 5 μm made of the alloy MR.
[12] The method for producing composite particles according to any one of [7] to [11], wherein the alloy MR is spontaneously ignited by crushing the alloy MR in the air.

In the composite particle of the present invention, a part or all of the surface of the nucleus composed of the metal M exhibiting ferromagnetism is selected from rare earth R (R is Ce, La, Y, Nd, Pr, Dy, Tb, Sm, Gd) Since it is coated with at least one kind of oxide, by spontaneously igniting the alloy MR composed of the metal M and the rare earth R, it is excellent in productivity that can be easily manufactured.
In the method for producing composite particles of the present invention, the alloy MR composed of the metal M exhibiting ferromagnetism and the rare earth R is spontaneously ignited in an atmosphere having an oxygen concentration of 5 vol. In this method, a part or all of the surface of the nucleus composed of is coated with the rare earth R oxide, so that at least a part of the periphery of the nucleus composed of the metal M exhibiting ferromagnetism is coated with the rare earth R oxide. The composite particles of the present invention can be easily produced.

Hereinafter, composite particles and a method for producing the same according to embodiments of the present invention will be described with reference to the drawings.
"Composite particles"
FIG. 1 is a schematic diagram for explaining an example of the composite particles of the present invention.
The composite particles shown in FIGS. 1A to 1C include a metal M (M is composed of Fe and inevitable impurities, or Fe of 80 wt% or more, Co, Ni, B, Mn, Si, A part or all of the surface of the core 6 made of Al, Cu, Cr, Ti, V, Mo, Zr, Nb, or Ga and containing at least one element and inevitable impurities) is a rare earth R (R is And at least one selected from Ce, La, Y, Nd, Pr, Dy, Tb, Sm, Gd, and Yb).

  As shown in FIG. 1A, the composite particle of the present invention may be one in which a plurality of nuclei 6 made of a metal M are integrated by an oxide 5 of rare earth R, or FIG. And as shown in FIG.1 (c), you may have one nucleus 6. FIG. In addition, the composite particles of the present invention, as shown in FIGS. 1 (a) and 1 (c), are those in which the entire surface of the core 6 made of the metal M is coated with the rare earth R oxide 5. Alternatively, as shown in FIG. 1B, only a part of the surface of the nucleus 6 may be covered with the rare earth R oxide 5.

  The particle diameter of the nucleus 6 made of the metal M (in this specification, “nucleus particle diameter” means an average value of the particle diameter of the nucleus) is preferably 1 μm to 500 μm. If the particle diameter of the nucleus 6 is less than the above range, the relative volume ratio of the rare earth R oxide 5 becomes too high, and predetermined magnetic characteristics may not be obtained. On the other hand, when the particle size of the core 6 exceeds the above range, the surface area of the soft magnetic material becomes small, and predetermined electromagnetic wave absorption characteristics may not be obtained.

The metal M is composed of Fe and inevitable impurities, or Fe of 80 wt% or more as a main component, and Co, Ni, B, Mn, Si, Al, Cu, Cr, Ti, V, Mo, Zr, Nb. And at least one element selected from Ga and inevitable impurities. As a raw material for the metal M, iron alloys such as Fe—B, Fe—V, Fe—Cr, Fe—Zr, Fe—Nb, and Fe—Mo can be used in addition to pure metals of the respective elements. These alloys are useful for preventing unmelted refractory metals.
In the present embodiment, the magnetic properties of the composite particles can be adjusted by changing the composition of the metal M.

  The metal M preferably contains 200 to 1500 ppm of Mn, 250 to 800 ppm of Ni, 100 to 1400 ppm of Si, 3000 to 20000 ppm of Cu, 150 to 1500 ppm of Cr, and 300 to 1200 ppm of Co. By setting it as such a metal M, it can be set as the composite particle which has the outstanding magnetic characteristic, without using an expensive material.

The metal M preferably has an oxygen concentration of 300 to 15000 ppm and a carbon concentration of 100 to 400 ppm. Regarding the oxygen concentration, a lower oxygen concentration is more preferable because magnetic characteristics are improved.
When the oxygen concentration and the carbon concentration are within the above ranges, composite particles having predetermined magnetic characteristics can be easily obtained.

  As the rare earth R, at least one selected from Ce, La, Y, Nd, Pr, Dy, Tb, Sm, Gd, and Yb can be used. As the raw material of the rare earth R, Ce-La misch metal, Nd-Pr didymium alloy, Dy-Fe alloy, etc. can be used in addition to pure metals of the respective elements. Since these alloys can be obtained at a lower cost than using pure metal, they are useful for reducing the manufacturing cost.

  Moreover, the ratio of the metal M and the rare earth R in the composite particle is not particularly limited, but it is preferable that the composite particle contains 10 to 80 wt% of the rare earth R. When the ratio of the rare earth R in the composite particles is less than the above range, the amount of the rare earth R oxide 5 covering the surface of the core 6 made of the metal M is reduced, and the metal M is replaced with the rare earth R oxide 5. In some cases, functions such as insulation obtained by coating cannot be sufficiently obtained. Moreover, when the ratio of the rare earth R in the composite particles exceeds the above range, composite particles having sufficient magnetic properties may not be obtained.

  The particle diameter of the composite particles (in this specification, “particle diameter of the composite particles” means an average value of the particle diameters of the composite particles) is preferably 10 to 1000 μm. When the particle size of the composite particles is smaller than the above range, it is not preferable because it tends to be non-uniform during kneading with the resin. If the particle size of the composite particles is larger than the above range, when the composite particles are dispersed in the resin and used as an electromagnetic wave absorbing material, the volume ratio of the composite particles in the resin becomes too small and the predetermined magnetic properties are obtained. There is a risk that it will not be obtained.

"Production method of composite particles"
Next, the manufacturing method of the composite particle of this invention is demonstrated.
In the method for producing composite particles of the present invention, the alloy MR composed of the metal M and the rare earth R is spontaneously ignited in an atmosphere having an oxygen concentration of 5 vol% or more, so that a part of the surface of the core 6 composed of the metal M or This is a manufacturing method including a step of covering the whole with a rare earth R oxide 5.
The alloy MR can be manufactured using, for example, the following method using a vacuum induction furnace. First, the vacuum induction furnace is evacuated, and the metal M and rare earth R are loaded into an alumina crucible. Thereafter, the inside of the vacuum induction furnace is set to an Ar atmosphere or an Ar reduced pressure atmosphere, and the metal M and the rare earth R are heated to 1200 to 1500 ° C. and melted by high frequency induction to form a molten metal. Thereafter, the alloy MR is obtained by pouring and solidifying the molten metal on a single copper roll or a mold.

  The melting temperature of the alloy MR is preferably set to a temperature higher by about 200 ° C. than the melting point of the alloy MR. By using such a temperature, when using a tundish during casting, solidification of the alloy MR in the tundish can be prevented, which is preferable. Moreover, by setting it as such temperature, it becomes possible to supply via a tundish to the copper single roll currently cooled with water from the crucible, and it becomes possible to produce alloy MR as a single roll quenching alloy.

When the alloy MR is manufactured as a single-roll quenching alloy, for example, it is substantially composed of 70 wt% or more of Al ₂ O ₃ and 30 wt% or less of SiO ₂ shown in WO99 / 67187 as the material of the tundish. Or consisting essentially of one or more of 70 wt% or more of ZrO ₂ and 30 wt% or less of Y ₂ O ₃ , Ce ₂ O ₃ , CaO, MgO, Al ₂ O ₃ , TiO ₂ or SiO ₂ , Bulk density is 1 g / cm ³ or less, thermal conductivity in the temperature range of 1200 to 1400 ° C. is 0.5 kcal / (mh ° C.) or less, 1400 ° C., and the ignition loss rate under heating conditions for 1 hour is 0.5 wt% or less. It is preferable to use a refractory material. By using a tundish made of such a material, it is possible to effectively prevent the molten metal being supplied from the crucible to the single roll from solidifying in the tundish, which is preferable.

  In addition, when using a copper single roll that is water-cooled, the peripheral speed of the single roll is set to 0.5 to 2.0 m / s, and the thickness of the alloy MR is set to 0.1 to 0.5 mm. It is preferable to pour into the roll. In this case, stable casting becomes possible, and an alloy MR having a uniform structure can be manufactured. On the other hand, when the thickness of the alloy MR is less than 0.1 mm, it is not preferable because it takes a lot of cost to transport the alloy MR and a large amount of fine powder composed of the alloy MR is generated. On the other hand, if the thickness of the alloy MR exceeds 0.5 mm, it may be excessively welded to a single roll, and the uniformity of the alloy structure may be lost.

Moreover, it is preferable that the alloy MR after being peeled off from the water-cooled copper single roll is cooled by dropping between metal cooling plates as disclosed in, for example, Japanese Patent No. 03561692. In this case, the alloy structure can be easily controlled and the productivity can be improved.
Further, as a cooling medium for the alloy MR after peeling from the single roll, it is preferable to use an inert gas such as Ar or He in order to prevent the alloy MR from being oxidized.

  Further, when the alloy MR is manufactured by pouring the molten metal into the mold, the productivity can be improved by setting the distance between the molds for determining the thickness of the alloy MR to 1 to 5 cm. If the distance between the molds exceeds the above range, the thickness of the obtained alloy MR becomes thick, and it is not preferable because much energy is required when the alloy MR is crushed. In addition, if the distance between the molds is less than the above range, the molten metal may solidify before the molten metal reaches the lower part of the mold. Deteriorate.

  Thereafter, the alloy MR thus obtained is spontaneously ignited in an atmosphere having an oxygen concentration of 5 vol% or more. The method of spontaneously igniting the alloy MR is not particularly limited, but it is preferable to use a method of spontaneously igniting the spark generated from the alloy MR by using the crushing device to crush the alloy MR. The atmosphere at which the alloy MR is crushed may be an atmosphere having an oxygen concentration of 5 vol% or more, and may be an air atmosphere or an atmosphere containing Ar or nitrogen as an inert gas in addition to oxygen. Good.

In this embodiment, as a crusher used for crushing alloy MR, a crusher generally used for roughly crushing metal, ore, or the like can be used. Specifically, examples of the crusher include a jaw crusher, a disk mill, a hammer mill, and a roll crusher.
In order to spontaneously ignite the alloy MR by crushing the alloy MR, it is preferable that the crushing conditions are such that a spark is easily generated from the alloy MR. Such crushing conditions are preferably crushing conditions that cause strong friction between the alloys MR or between the crushing teeth of the crushing device and the alloy MR.

  Further, in order to effectively use the spark generated from the alloy MR by crushing the alloy MR as an ignition source of the alloy MR, the alloy MR is crushed so that the alloy MR together with the crushed pieces made of the alloy MR. It is preferable to produce a fine powder. The size of the fine powder produced here (in this specification, “the size of the fine powder” means an average value of the particle size of the fine powder) is preferably a particle size of 0.01 to 5 μm. More preferably, the particle size is 0.01 to 3 μm. By setting the particle size of the fine powder within the above range, the probability that the fine powder made of the alloy MR is ignited by the spark generated from the alloy MR is increased, and the productivity of the composite particles can be further improved, which is preferable.

  Moreover, it is preferable that the production amount of the fine powder produced | generated by crushing alloy MR is the range of 0.001 wt%-0.1 wt% of alloy MR. If the amount of fine powder produced is less than the above range, even if a spark is generated by crushing the alloy MR, the alloy MR does not sufficiently burn and composite particles may not be obtained. On the other hand, if the amount of fine powder produced exceeds the above range, the fine powder composed of the alloy MR is fixed in the crushing apparatus, and the yield is unfavorable. In addition, the action of combustion by the fine powder works too much, so that an oxide of metal M is generated, and the target composite particles may not be manufactured.

  The alloy MR is crushed pieces having a particle size of 10 to 1000 μm by crushing (in this specification, “particle size of the crushed pieces” means the average value of the particle sizes of the crushed pieces). The particle size is preferably 10 to 200 μm. If the particle size of the crushed pieces is less than the above range, the action of combustion due to spontaneous ignition becomes too strong, and the metal M becomes an oxide, which may make it impossible to produce the desired composite particles. Further, if the particle size of the crushed pieces exceeds the above range, sufficient thermite reaction may not be performed, and the target composite particles may not be produced simply by enlargement of the structure of the alloy MR.

  Here, the process of producing composite particles by spontaneously igniting the alloy MR will be described with reference to the drawings. FIG. 2A to FIG. 2C are schematic views for explaining a process in which composite particles are manufactured by spontaneous ignition of the alloy MR. In FIG. 2, reference numeral 1 indicates an alloy MR before crushing, reference numeral 2 indicates a spark, reference numeral 3 indicates fine powder made of the alloy MR generated by crushing, and reference numeral 4 indicates a crushed piece made of the alloy MR generated by crushing. Is shown.

  As shown in FIG. 2 (a), the alloy MR1 is crushed in an atmosphere having an oxygen concentration of 5 vol% or more, thereby forming a crushed piece 4 containing fine powder 3 while generating a spark 2. As shown in FIG. 2B, the spark 2 generated here first ignites fine powder 3 that is easily ignited. As shown in FIG. 2C, the ignited fine powder 3 adheres to the crushed pieces 4 while being oxidized at high temperature by self-combustion, and ignites the alloy MR constituting the crushed pieces 4 by heating the crushed pieces 4.・ Burn. By such ignition and combustion of the crushed pieces 4, the alloy MR constituting the crushed pieces 4 undergoes a redox reaction, and the rare earth R contained in the alloy MR is heated by the combustion of the fine powder 3 and the crushed pieces 4 and in the atmosphere. Oxidized with oxygen to form an oxide, which is separated from the metal M. Further, the metal M contained in the alloy MR constituting the crushed pieces 4 is melted by heating due to the combustion of the fine powder 3 and ignition / combustion of the alloy MR constituting the crushed pieces 4 and aggregates in a spherical shape. As shown in FIGS. 1A to 1C, the metal MR and the rare earth R are separated by such a thermite reaction of the alloy MR, and the molten metal M becomes a spherical nucleus 6, and a nucleus made of the metal M. Thus, composite particles in which part or all of the surface of 6 is coated with the rare earth R oxide 5 are obtained.

  In addition, in such a manufacturing process, the particle | grains which consist only of the nucleus 6 comprised from the metal M shown by Fig.3 (a) with the composite particle shown to Fig.1 (a)-(c), or Fig.3 ( In some cases, particles comprising only the rare earth R oxide 5 shown in b) are also produced. 3A is separated from the rare earth R by the oxidation-reduction reaction of the alloy MR constituting the crushed piece 4, and the metal M is dissolved and aggregated by ignition and combustion of the alloy MR. Formed by. Further, the particles made of only the rare earth R oxide 5 shown in FIG. 3B are converted into oxides by the rare earth R contained in the alloy MR due to the oxidation-reduction reaction of the alloy MR constituting the crushed pieces 4. It is obtained by separating from the metal M. 3 (a) and FIG. 3 (b), the particles made of only the metal M or the rare earth R oxide 5 may be combined with the composite particles shown in FIGS. 1 (a) to 1 (c). Can be separated.

  In the manufacturing process shown in FIGS. 2A to 2C, when the metal M constituting the alloy MR1 contains oxygen, the oxygen contained in the metal M is around the metal M. It becomes a supply source of oxygen to the oxide 5 of the rare earth R generated so as to surround the metal. That is, oxygen contained in the metal M is taken away by the rare earth R which is easily oxidized and separated and removed from the metal M, and the oxide 5 of the rare earth R is generated on the surface of the metal M from which oxygen is removed. To do. Part or all of the metal M from which oxygen is removed is surrounded by the rare earth R oxide 5 as shown in FIGS. It is prevented that oxygen is newly supplied to the nucleus 6. Thus, even when oxygen is contained in the metal M constituting the alloy MR1, the metal M is reduced by crushing the alloy MR in an atmosphere having an oxygen concentration of 5 vol% or more. Without this, a nucleus 6 made of metal M is generated. Further, when the metal M constituting the alloy MR1 contains oxygen, the rare earth R oxide 5 is generated on the surface of the metal M from which oxygen has been removed, using the removed oxygen as a supply source. 3 (a) and FIG. 3 (b), the amount of particles made of only the metal M or only the rare earth R oxide 5 is reduced, and a part or all of the surface of the core 6 made of the metal M is rare earth. Composite particles coated with the oxide 5 of R can be produced more efficiently.

  The size of the composite particle and the size of the nucleus 6 shown in FIGS. 1A to 1C vary depending on the duration of oxidation-reduction reaction of the alloy MR, the maximum temperature, and the size of the crushed pieces 4. Therefore, by changing the composition of the rare earth R and metal M and the crushing conditions of the alloy MR, and controlling the duration and maximum temperature of the oxidation-reduction reaction of the alloy MR and the size of the crush pieces 4, the particle size of the composite particles Can be controlled in the range of 10 μm to 1000 μm, for example, and the particle size of the core 6 can be controlled in the range of 1 μm to 500 μm, for example. It is preferable that the size of the nucleus 6 is as small as 10 μm or less because it exhibits excellent electromagnetic wave absorption characteristics. Further, when the composite particles are made larger than 20 μm, when the composite particles are added to the resin and kneaded, they are less likely to agglomerate and easily disperse, and can be uniformly distributed in the resin. Therefore, it can be suitably used for an electromagnetic wave absorbing material in which composite particles are dispersed in a resin.

  For example, when Ce, La, Pr, or Nd having high activity with oxygen is used as the rare earth R, the temperature at which the alloy MR self-combusts becomes relatively high, and the nucleus 6 made of the metal M grows greatly. For this reason, large composite particles can be obtained. Further, when rare earth R uses Dy, Tb, and Gd, which are less active with oxygen than Ce, La, Pr, and Nd, the temperature at which the alloy MR self-combusts becomes relatively low, and the nucleus composed of metal M The size of 6 becomes smaller. For this reason, small composite particles are obtained.

  In addition, when the melting point of the alloy MR is increased by containing a high melting point metal in the metal M, the time for the metal M to melt and aggregate is shortened, and a sufficient time for the nucleus 6 made of the metal M to grow is obtained. Disappear. For this reason, the size of the nuclei 6 is reduced, resulting in small composite particles. On the other hand, when a low melting point metal is contained in the metal M to lower the melting point of the alloy MR, the time for the metal M to melt and aggregate becomes longer, and the time for the growth of the nucleus 6 made of the metal M becomes longer. For this reason, the size of the nucleus 6 is increased, resulting in a large composite particle.

  Further, the composite particles of the present embodiment can be used as an electromagnetic wave absorbing material by being dispersed in a resin and kneaded. Examples of the resin used here include an epoxy resin and an acrylic resin. The electromagnetic wave absorbing material obtained by dispersing the composite particles according to the present embodiment includes the composite particles according to the present embodiment containing iron as a main component as the metal M, and thus has excellent absorption characteristics in a high frequency band and protects electronic components. It will be useful for use.

In the composite particle of the present embodiment, a part or all of the surface of the nucleus made of the metal M is coated with the rare earth R oxide, so that the alloy MR composed of the metal M and the rare earth R is made of the alloy MR. By spontaneously igniting, it is excellent in productivity that can be easily manufactured.
Moreover, according to the composite particle of this embodiment, the electromagnetic wave absorption characteristics and the magnetic characteristics can be easily adjusted by changing the composition of the metal M constituting the core 6.

Further, in the method for producing composite particles of the present embodiment, the alloy MR composed of the metal M and the rare earth R is spontaneously ignited in an atmosphere having an oxygen concentration of 5 vol% or more, so that the surface of the core composed of the metal M is Since the method includes a step of covering part or all with a rare earth R oxide, at least a part of the periphery of the core made of the metal M is coated with the rare earth R oxide without performing a step of using a flame. The composite particles of this embodiment can be easily produced.
Further, when the alloy MR is spontaneously ignited by crushing the alloy MR, the alloy MR can be easily ignited easily by using a spark generated from the alloy MR by crushing the alloy MR as an ignition source. .
Further, when the alloy MR is spontaneously ignited by crushing the alloy MR in the air, it becomes easy to control the atmosphere in which the alloy MR is crushed, and the composite particles can be manufactured more easily.

  In addition, according to the method for producing composite particles of the present embodiment, the size of the composite particles can be easily controlled. For example, by making the size of the core 6 as small as 10 μm or less, it is excellent. Composite particles exhibiting electromagnetic wave absorption characteristics can be easily provided. In addition, for example, by making the size of the composite particles larger than 20 μm, when added to the resin and kneaded, it is difficult to agglomerate, easily disperse, and can be uniformly distributed in the resin. It becomes.

EXAMPLES Next, although an Example is shown and this invention is demonstrated further in detail, this invention is not limited only to these Examples.
"Experiment 1"
The metal M is composed of Fe (96.6 wt%), Co (1.5 wt%), B (1.5 wt%), Al (0.3 wt%), Cu (0.1 wt%), and the rare earth R is Nd. (78.1 wt%), Pr (18.8 wt%), Dy (2.8 wt%), Tb (0.3 wt%), and the composition of the alloy MR is Fe (65.7 wt%), Co (1 0.0 wt%), B (1.0 wt%), Al (0.20 wt%), Cu (0.1 wt%), Nd (25 wt%), Pr (6 wt%), Dy (0.9 wt%), Tb (0.1 wt%) iron, Fe-B alloy (B content 21 wt%), Al metal, Cu metal, Co metal, Nd metal, Pr metal, Dy metal, Tb metal and weighed alumina Place in crucible and heat to 1500 ° C in Ar atmosphere using high frequency vacuum induction furnace A molten metal was poured into a water-cooled copper roll having a roll peripheral speed of 1.0 m / s so that the average thickness was 0.3 mm, and an alloy MR made of a quenched alloy was produced.

  The alloy MR thus obtained is crushed using a roll crusher in an air atmosphere to generate a spark as an ignition source and have a particle size of 10 containing a fine powder having a particle size of 0.1 to 5 μm made of the alloy MR. Alloy MR was spontaneously ignited by generating crushed pieces of ˜800 μm. As a result, an experiment example in which a part or all of the surface of the spherical nucleus made of the metal M (Fe, B, Al, Cu, Co) was coated with an oxide of the rare earth R (Nd, Pr, Dy, Tb). 1 composite particles were obtained.

FIG. 4 is a reflected electron image of a cross section of the product obtained after spontaneous firing of the alloy MR in Experimental Example 1. In FIG. 4, the dark gray portion indicates the metal M, and the light gray portion indicates the rare earth R oxide 5.
As shown in FIG. 4, in Experimental Example 1, composite particles in which a part or all of the surface of the spherical nucleus 6 made of the metal M was coated with the rare earth R oxide 5 were obtained. As shown in FIG. 4, in Experimental Example 1, the obtained composite particles include those in which a plurality of nuclei 6 are integrated by a rare earth R oxide 5 and those having one nuclei 6. It was included. Further, as shown in FIG. 4, in Experimental Example 1, as the obtained composite particles, the entire surface of the nucleus 6 was covered with the rare earth R oxide 5 and only a part of the surface of the nucleus 6 was obtained. Are coated with the rare earth R oxide 5. Furthermore, in Experimental Example 1, not only composite particles but also particles composed only of nuclei 6 made of metal M and particles composed only of oxide 5 of rare earth R are mixed and formed as shown in FIG. It had been.

"Experimental example 2"
A molten metal similar to that of Experimental Example 1 was prepared, and poured into a copper mold having an interval for determining the thickness of the alloy MR being 2 cm, thereby preparing an alloy MR.
The alloy MR thus obtained was crushed in the same manner as in Experimental Example 1, and the alloy MR was spontaneously ignited. As a result, an experiment example in which a part or all of the surface of the spherical nucleus made of the metal M (Fe, B, Al, Cu, Co) was coated with an oxide of the rare earth R (Nd, Pr, Dy, Tb). 2 composite particles were obtained.

"Experiment 3"
The metal M is composed of Fe (87.5 wt%), Co (6.3 wt%), Ni (5.6 wt%), Si (0.6 wt%), and the rare earth R is Ce (60.0 wt%), La (25.0 wt%), Y (15.0 wt%), and the composition of the alloy MR is Fe (70 wt%), Co (5.0 wt%), Ni (4.5 wt%), Si (0.5 wt%) %), Ce (12 wt%), La (5 wt%), Y (3 wt%), and weigh iron, Co metal, Ni metal, Si metal, Ce metal, La metal, and Y metal to obtain an alumina crucible. Put it in and heat it to 1400 ° C in an Ar atmosphere using a high-frequency vacuum induction furnace to make a molten metal, then pour it into a water-cooled copper roll with a roll peripheral speed of 1.0 m / s so that the average thickness is 0.3 mm An alloy MR made of a quenched alloy was produced.

  The alloy MR thus obtained was crushed in the same manner as in Experimental Example 1, and the alloy MR was spontaneously ignited. As a result, the composite particle of Experimental Example 3 in which a part or all of the surface of the spherical nucleus made of the metal M (Fe, Co, Ni, Si) was coated with the rare earth R (Ce, La, Y) oxide. was gotten.

"Experimental example 4"
The metal M is composed of Fe (66.7 wt%), Co (26.7 wt%), Ni (2.7 wt%), Ti (2.7 wt%), Mo (1.3 wt%), and the rare earth R is Sm. (80.0 wt%), Gd (20.0 wt%), and the composition of the alloy MR is Fe (50 wt%), Co (20 wt%), Ni (2 wt%), Ti (2 wt%), Mo ( 1 wt%), Sm (20 wt%), Gd (5 wt%), iron, Co metal, Ni metal, Ti metal, Fe—Mo (Mo content 63 wt%), Sm metal, Gd metal are weighed. In an alumina crucible and heated to 1600 ° C. in an Ar atmosphere using a high-frequency vacuum induction furnace to form a molten metal so that the average thickness is 0.3 mm on a water-cooled copper roll with a roll peripheral speed of 1.0 m / s. Pouring and making an alloy MR made of a quenched alloy It was.

  The alloy MR thus obtained was crushed in the same manner as in Experimental Example 1, and the alloy MR was spontaneously ignited. As a result, the composite particle of Experimental Example 4 in which a part or all of the surface of the spherical nucleus made of the metal M (Fe, Co, Ni, Ti, Mo) was coated with the rare earth R (Sm, Gd) oxide. was gotten.

"Experimental Example 5-Experimental Example 8"
Example 1 is the same as Example 1 except that the alloys MR of Experiments 5 to 8 were prepared in the same manner as Experimental Examples 1 to 4, and the atmosphere when the alloy MR was crushed was changed to an atmosphere having an oxygen concentration of 2 vol%. In the same manner, the alloy MR of Experimental Examples 5 to 8 was crushed. As a result, although sparks were generated by crushing the alloy MR of Experimental Example 5 to Experimental Example 8, none of the Alloy MR of Experimental Example 5 to Experimental Example 8 resulted in combustion, Also remained in the alloy MR.

“Experimental Example 9 to Experimental Example 12”
In the same manner as Experimental Example 1 to Experimental Example 4, Alloys MR of Experimental Example 9 to Experimental Example 12 were prepared, and when the alloy MR was crushed, it was crushed while passing air at a wind speed of 16 m / s and removing fine powder. Except for this, the alloy MR of Experimental Examples 9 to 12 was crushed in the same manner as Experimental Example 1. As a result, sparks were generated by crushing the alloy MR of Experimental Examples 9 to 12, but none of the Alloy MR of Experimental Examples 9 to 12 resulted in combustion, and the obtained particles were alloyed. It remained MR.

“Experimental Example 13 to Experimental Example 16”
In the same manner as in Experimental Example 1, Alloys MR in Experimental Examples 13 to 16 were produced, respectively, and in the same manner as Experimental Example 1 except that the atmosphere when the alloy MR was crushed was an Ar atmosphere, Experimental Examples 13 through The alloy MR of Experimental Example 16 was crushed to obtain a crushed powder having a particle size of 200 μm or less. Thereafter, the obtained crushed powder was heated with a propane-oxygen burner. As a result, in any of Experimental Examples 13 to 16, the obtained particles were not composite particles in which a part or all of the surface of the spherical nucleus composed of the metal M was coated with the rare earth R oxide. .

  FIG. 5 is a reflected electron image of the cross section of the particle obtained in Experimental Example 13. In the particles of Experimental Example 13, as shown in FIG. 5, the nucleus composed of the metal M was not formed.

FIG. 1 is a schematic diagram for explaining an example of the composite particles of the present invention. FIG. 2A to FIG. 2C are schematic views for explaining a process in which composite particles are manufactured by spontaneous ignition of the alloy MR. FIG. 3 is a schematic diagram for explaining particles generated together with the composite particles. FIG. 4 is a reflected electron image of a cross section of the product obtained after spontaneous firing of the alloy MR in Experimental Example 1. FIG. 5 is a reflected electron image of the cross section of the particle obtained in Experimental Example 13.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Alloy MR, 2 ... Spark, 3 ... Fine powder, 4 ... Fragmented piece, 5 ... Rare earth R oxide, 6 ... Core.

Claims (12)

  Oxidation of rare earth R (R is at least one selected from Ce, La, Y, Nd, Pr, Dy, Tb, Sm, Gd, and Yb) on part or all of the surface of the nucleus composed of the metal M exhibiting ferromagnetism Composite particles characterized in that they are coated with an object.   The metal M is composed of Fe and inevitable impurities, or Fe of 80 wt% or more, and Co, Ni, B, Mn, Si, Al, Cu, Cr, Ti, V, Mo, Zr, Nb, and Ga. The composite particle according to claim 1, comprising at least one element selected and inevitable impurities.   3. The composite particle according to claim 1, wherein a particle diameter of the nucleus is 1 μm to 500 μm.   The composite particle according to any one of claims 1 to 3, wherein the composite particle has a particle size of 10 to 1000 µm.   5. The composite particle according to claim 1, wherein the metal M has an oxygen concentration of 300 to 15000 ppm and a carbon concentration of 100 to 400 ppm.   The metal M includes 200 to 1500 ppm of Mn, 250 to 800 ppm of Ni, 100 to 1400 ppm of Si, 3000 to 20000 ppm of Cu, 150 to 1500 ppm of Cr, and 300 to 1200 ppm of Co. The composite particles according to claim 5. Oxidation of rare earth R (R is at least one selected from Ce, La, Y, Nd, Pr, Dy, Tb, Sm, Gd, and Yb) on part or all of the surface of the nucleus composed of the metal M exhibiting ferromagnetism In the method for producing composite particles coated with an object,
The alloy MR comprising the metal M and the rare earth R is spontaneously ignited in an atmosphere having an oxygen concentration of 5 vol% or more, thereby covering a part or all of the surface of the nucleus with the rare earth R oxide. A method for producing composite particles.   The metal M is composed of Fe and inevitable impurities, or Fe of 80 wt% or more, and Co, Ni, B, Mn, Si, Al, Cu, Cr, Ti, V, Mo, Zr, Nb, and Ga. The method for producing composite particles according to claim 7, comprising at least one element selected and inevitable impurities.   The method for producing composite particles according to claim 7 or 8, wherein the alloy MR is spontaneously ignited by crushing the alloy MR.   The method for producing composite particles according to claim 9, wherein the alloy MR is crushed to a particle size of 10 to 1000 μm.   11. The method for producing composite particles according to claim 9, wherein fine particles having a particle diameter of 0.01 to 5 μm made of the alloy MR are generated by crushing the alloy MR.   The method for producing composite particles according to any one of claims 7 to 11, wherein the alloy MR is spontaneously ignited by crushing the alloy MR in the atmosphere.

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