JP2018198280A - Nitride-based bond magnet - Google Patents

Abstract

To provide a nitride-based bond magnet having high remanent magnetization, high coercive force, and high mechanical strength.SOLUTION: In a nitride-based bond magnet containing nitride-based magnetic powder and resin, the nitride-based magnetic powder is composed of particles containing an iron nitride phase, and the cross section structure of the nitride-based bond magnet is a structure in which a plurality of nitride-based magnetic powder layers including nitride-based magnetic powders and resin organic material layers made of resins are alternately laminated, and a ratio expressed by (cross-sectional area of the nitride-based magnetic powder layer/cross-sectional area of the resin organic material layer) is 3.0 or more and 10.0 or less, and the thickness per organic resin layer is 1.0 μm or more and 5.0 μm or less.SELECTED DRAWING: Figure 1

Description

   The present invention relates to an iron nitride based bonded magnet.

  In recent years, Nd-Fe-B magnets have been widely used as motor magnets for electric vehicles and hybrid vehicles. However, rare earths typified by Nd are raw materials for high-value-added members that support the industrial field, and since demand is increasing in recent years, there is a concern about depletion of resources and destabilization of raw material prices. Furthermore, there is a problem in securing a stable supply because the demand is growing significantly in developing countries and the dependence on specific producing countries is high due to its uneven distribution.

  In order to avoid the above problems, it is required to develop a high-performance magnet from elements (iron, nitrogen) that are inexhaustible in nature without using rare earth.

Fe-N-based compounds, particularly Fe ₁₆ N _2, are attracting attention as one of materials exhibiting a larger saturation magnetization than Fe.

However, Fe ₁₆ N ₂ decomposes when exposed to a temperature of 200 ° C. or higher for a certain period of time, and the huge saturation magnetization disappears. Therefore, it cannot pass through processes, such as normal sintering. Therefore, a sintered magnet using Fe ₁₆ N ₂ cannot be obtained. That is, a bulk magnet densified by sintering cannot be produced. Because of such problems, it has been studied to use Fe ₁₆ N ₂ for a magnet that can be produced without a process such as ordinary sintering. For example, Patent Document 1 describes a bonded magnet using Fe ₁₆ N ₂ . However, the bond magnet has a problem that it is impossible to achieve both magnetic properties and mechanical strength, and cannot be used for a high-performance motor.

JP 2009-84115 A

  The present invention has been made in view of the above, and an object of the present invention is to provide an iron nitride-based bonded magnet having high residual magnetization, high coercive force, and high mechanical strength.

The iron nitride bond magnet according to the present invention is
It is an iron nitride based bonded magnet composed of iron nitride based magnetic powder and resin,
The iron nitride magnetic powder is composed of particles containing an iron nitride phase,
The cross-sectional structure of the iron nitride-based bonded magnet is a structure in which a plurality of iron nitride-based magnetic powder layers including the iron nitride-based magnetic powder and a resin organic material layer made of the resin are alternately stacked,
The ratio represented by (the cross-sectional area of the iron nitride magnetic powder layer / the cross-sectional area of the resin organic material layer) is 3.0 or more and 10.0 or less,
The thickness per layer of the organic resin layer is 1.0 μm or more and 5.0 μm or less.

  The iron nitride-based bonded magnet according to the present invention has higher residual magnetization and higher mechanical strength than conventional iron nitride-based bonded magnets.

  In the iron nitride-based bonded magnet according to the present invention, the ratio represented by (the cross-sectional area of the iron nitride-based magnetic powder layer / the cross-sectional area of the resin organic material layer) may be 4.0 or more and 7.0 or less.

  In the iron nitride-based bonded magnet according to the present invention, the resin organic layer may have a thickness of 2.0 μm or more and 4.0 μm or less.

  In the iron nitride-based bonded magnet according to the present invention, the average equivalent circle diameter of the particles containing the iron nitride phase may be 30 nm or more and 150 nm or less.

FIG. 1 is a schematic cross-sectional view of an iron nitride-based bonded magnet according to an embodiment of the present invention cut into a plane perpendicular to the laminated surface.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described based on the embodiments shown in the drawings. The present invention is not limited to the embodiments described below. In addition, the constituent elements shown in the embodiments and examples described below may be appropriately combined or may be appropriately selected.

  As shown in FIG. 1, an iron nitride based bonded magnet 1 according to the present invention includes an iron nitride based magnetic powder composed of particles 2a containing an iron nitride phase, an iron nitride based magnetic powder layer 2 composed of a resin organic material 4a, and a resin organic material 4a. And a resin organic material layer 4 made of

The iron nitride phase is a ferromagnetic phase mainly composed of iron nitride. While _{content of the Fe} 16 _{N 2} compound was as iron nitride is _typically not limited to _{content of the Fe} 16 _{N 2} compound thereof, such as Fe ₄ N compound may be a compound consisting of Fe and N. The particles 2a containing an iron nitride phase may contain a nitride phase other than the iron nitride phase. The ratio of the iron nitride phase in the particles 2a containing the iron nitride phase is not particularly limited, but is preferably 95% by weight or more. Moreover, it can be confirmed using XRD that the particles contain an iron nitride phase.

Furthermore, the iron nitride phase in the particles 2a containing the iron nitride phase may contain a transition metal such as Mn, Ni, Co, Ti, Zn. Further, the particles 2a containing the iron nitride phase may contain oxides such as Fe ₂ O ₃ , Fe ₃ O ₄ and FeO, a trace amount of Si compounds, etc. Other components may be included. There is no restriction | limiting in particular in content of these components. For example, assuming that the entire particle 2a containing the iron nitride phase is 100% by weight, the transition metal such as Mn, Ni, Co, Ti and Zn is 1% by weight or less, the Si compound is 3% by weight or less, and the other components May be contained in an amount of 1% by weight or less.

  The particles 2a containing the iron nitride phase may have a nonmagnetic phase on the surface. There is no particular limitation on the type of nonmagnetic phase. For example, an oxide phase of iron nitride is exemplified. Moreover, in this embodiment, as shown in FIG. 1, although resin organic substance 4a is filled in parts other than the particle | grains 2a containing the said iron nitride phase in the iron nitride type magnetic powder layer 2, it contains an iron nitride phase. Portions other than the particles 2a may be voids.

  The resin organic material layer 4 is mainly composed of the resin organic material 4a having a molecular weight of 10,000 or more, but may contain an organic material having a small molecular weight. And the resin organic substance layer 4 does not contain the particle | grains 2a containing the said iron nitride phase substantially. The phrase “resin organic matter 4a as a main component” means that the proportion of the resin organic matter 4a having a molecular weight of 10,000 or more in the resin organic matter layer 4 is 99% by weight or more. Moreover, it can confirm that the particle | grains 2a containing the said iron nitride phase are not included substantially because the component derived from the particle | grains 2a containing the said iron nitride phase is not detected in the element mapping mentioned later.

  In the iron nitride-based bonded magnet according to the present embodiment, the adhesion between the iron nitride-based magnetic powder layers 2 is improved by the presence of the resin organic material layer 4 that does not substantially include the particles 2a including the iron nitride phase. In addition, mechanical strength (particularly bending strength) is improved.

  In the cross section of the iron nitride-based magnet 1, a ratio represented by (the cross-sectional area of the iron nitride-based magnetic powder layer / the cross-sectional area of the resin organic material layer) (hereinafter sometimes simply referred to as “cross-sectional area ratio”) is 3. 0.0 or more and 10.0 or less. When the cross-sectional area ratio is less than 3.0, the ratio of the resin organic material layer 4 in the iron nitride-based bond magnet 1 is reduced, so that sufficient mechanical strength (particularly bending strength) is not easily obtained. Further, when the cross-sectional area ratio is greater than 10.0, the ratio of the iron nitride magnetic powder layer 2 in the iron nitride bond magnet 1 is reduced, so that it is difficult to obtain sufficient residual magnetization. More preferably, the cross-sectional area ratio is 4.0 or more and 7.0 or less.

  The thickness per layer of the iron nitride magnetic powder layer 2 is not particularly limited. For example, it can be 3.0 μm or more and 50 μm or less. Moreover, it is good also as 4.0 micrometers or more and 35 micrometers or less, and good also as 8.0 micrometers or more and 24 micrometers or less.

  In the cross section of the iron nitride-based bonded magnet 1, the thickness of the resin organic material layer 4 per layer is 1.0 μm or more and 5.0 μm or less. When the thickness per layer of the resin organic material layer 4 is less than 1.0 μm, it becomes difficult to sufficiently bond the iron nitride magnetic powder layers 2 to each other with the resin organic material layer 4, and sufficient mechanical strength (especially bending) (Strength) is not easily obtained. Further, when the thickness per layer of the resin organic material layer 4 is larger than 5.0 μm, the thickness per layer of the iron nitride magnetic powder layer 2 becomes relatively thick, and the inside of the iron nitride magnetic powder layer 2 is relatively thick. Cracks are likely to occur, and sufficient mechanical strength (particularly bending strength) cannot be obtained. More preferably, the thickness per layer of the resin organic material layer is 2.0 μm or more and 4.0 μm or less.

  Here, a method for identifying the iron nitride magnetic powder layer and the resin organic material layer will be described, and a method for identifying the cross-sectional area ratio and a method for identifying the thickness of each layer will be described.

  The iron nitride magnetic powder layer and the resin organic material layer can be identified by observing the cross section of the iron nitride bond magnet 1. For example, a cross section of a 1.0 μm × 1.0 μm measurement area is observed with a transmission electron microscope at a magnification of 200,000 times, further element distribution mapping is performed by EDS, and the element mapping image is derived from particles 2a containing an iron nitride phase. The layer containing the element and the element derived from the resin organic substance 4a was used as the iron nitride magnetic powder layer 2. Specifically, the layer in which Fe, N and C were detected by element mapping was used as an iron nitride magnetic powder layer. On the other hand, the layer containing only the element derived from the resin organic material 4a and substantially not including the element derived from the particle 2a containing the iron nitride phase was defined as the resin organic material layer 4. Specifically, a layer in which Fe is not detected by element mapping and C is detected by element mapping is identified as a resin organic material layer. In addition, when using the compound which does not contain N as the resin organic substance 4a, N will not be detected by elemental mapping with Fe.

  Regarding the cross-sectional area ratio, first, cross-sectional observation is performed on 500 different measurement regions with respect to the cross-section of the iron nitride-based bonded magnet, and the cross-sectional area ratio in each measurement region is calculated. Then, by averaging the cross-sectional area ratios in 500 regions, the cross-sectional area ratio of the iron nitride-based bond magnet can be calculated.

  Moreover, the thickness per layer of the organic material layer can be calculated from the cross-sectional area ratio of each constituent layer, the length of the organic material resin layer, and the number of organic material resin layers.

  The average equivalent circle diameter of the particles 2a containing the iron nitride phase is preferably 30 nm or more and 150 nm or less. When the average equivalent circle diameter of the particles 2a containing the iron nitride phase is within the above range, the coercive force tends to increase particularly. The average equivalent circle diameter of the particles 2a containing the iron nitride phase can be calculated from the cross-sectional area ratio of each constituent layer, the total area of each measurement region, and the number of particles containing the iron nitride phase in each measurement region.

  Hereinafter, although the suitable manufacturing method of the iron nitride based bonded magnet 1 which concerns on this embodiment is described, the manufacturing method of the iron nitride based bonded magnet 1 which concerns on this embodiment is not limited to the following method.

  First, iron oxide particles serving as a raw material for the particles 2a containing an iron nitride phase are prepared. The iron oxide particles are mixed with an aqueous iron salt solution containing an iron (II) salt and / or an iron (III) salt (hereinafter sometimes simply referred to as “iron salt”) and an alkaline aqueous solution. It can be produced by advancing the aging reaction.

  There are no particular limitations on the type of the iron salt, and for example, sulfates, chlorides, nitrates, and the like can be used, and these may be used in appropriate combination. Moreover, those hydrates can be used.

  There is no particular limitation on the type of the aqueous alkali solution, and for example, one or more selected from the group consisting of an aqueous sodium hydroxide solution, aqueous ammonia, aqueous ammonia salt solution, and aqueous urea solution can be used. May be used.

  There is no restriction | limiting in particular in the conditions of the said ageing | curing | ripening reaction, It can select suitably by the kind of the said iron salt and the kind of said aqueous alkali solution.

  Further, from the viewpoint of improving the crystallinity of iron oxide obtained after the aging reaction, controlling the particle size, and controlling the particle shape, the aging reaction can be carried out by in-liquid aging reaction such as hydrothermal treatment with an autoclave. preferable.

  The iron oxide particles obtained by the aging reaction can be recovered by filtering the aqueous solution after the aging reaction. Moreover, you may obtain the iron oxide slurry containing an iron oxide particle by performing washing processes, such as water washing, using the centrifuge etc. with respect to the aqueous solution after aging reaction.

  In order to suppress the iron oxide particles from being sintered together by a reduction treatment described later, a part of the particle surface may be coated with a Si compound. As the Si compound, colloidal silica, a silane coupling agent, a silanol compound, and the like can be used, but are not limited thereto.

  When coating with a Si compound, the coating amount of the Si compound is preferably 0.1% by weight or more and 20% by weight or less in terms of Si with respect to the iron oxide particles. By making the content 0.1% by weight or more, the effect of suppressing the sintering between the iron oxide particles during the heat treatment can be sufficiently obtained, and the average equivalent circle diameter of the particles 2a containing the iron nitride phase finally obtained is Can be controlled to 150 nm or less. By making the content 20% by weight or less, it becomes easy to moderately suppress the sintering between the iron oxide particles during the heat treatment, and it is easy to control the average equivalent circle diameter of the particles 2a containing the iron nitride phase finally obtained to 30 nm or more. Become.

  Further, the step of coating with the Si compound may be performed on the iron oxide particles obtained by filtration, or may be performed on the iron oxide slurry described above. Moreover, after performing the process which coat | covers with an Si compound with respect to an iron oxide slurry, an iron oxide particle can be collect | recovered by filtering an iron oxide slurry.

  The average particle diameter of the iron oxide particles is not particularly limited, but is preferably 10 nm or more and 150 nm or less. By setting the average particle size to 10 nm or more and 150 nm or less, it becomes easy to control the average of the equivalent circle diameter of the finally obtained particles 2 a containing an iron nitride phase to 30 nm or more and 150 nm or less.

Examples of the iron oxide particles include magnetite, γ-Fe ₂ O ₃ , α-Fe ₂ O ₃ , α-FeOOH, β-FeOOH, γ-FeOOH, FeO and the like, but other types of oxidation Iron particles may be used.

  There is no restriction | limiting in particular in the particle shape of the said iron oxide particle, Any, such as spherical shape, needle shape, a granular form, a spindle shape, a rectangular parallelepiped shape, may be sufficient. Moreover, before performing the reduction process mentioned later with respect to the obtained iron oxide particle, you may dry an iron oxide particle as needed. There is no particular limitation on the drying conditions.

  The particles 2a containing an iron nitride phase according to the present embodiment can be obtained by subjecting the iron oxide particles to a reduction treatment and subjecting the obtained iron particles to a nitriding treatment. Furthermore, the obtained particles 2a containing the iron nitride phase may be subjected to a gradual oxidation treatment at a low temperature and under a low oxygen partial pressure to form an oxide phase on the surface of the particles 2a containing the iron nitride phase.

  Hereinafter, reduction treatment, nitriding treatment, and gradual oxidation treatment will be described.

  Although the temperature of a reduction process is not specifically limited, It is preferable to set it as 200 to 400 degreeC. By reducing the temperature of the reduction treatment to 200 ° C. or higher, the iron oxide particles can be sufficiently reduced. By reducing the temperature of the reduction treatment to 400 ° C. or less, the iron oxide particles are sufficiently reduced, and the sintering between the particles can be moderately suppressed. The temperature of the reduction treatment is more preferably 230 ° C. or higher and 350 ° C. or lower.

  The time for the reduction treatment is not particularly limited, but is preferably 1 hour or more and 96 hours or less. When the time for the reduction treatment is 96 hours or less, it becomes difficult to appropriately proceed the sintering between particles even if the temperature of the reduction treatment is increased. As a result, the nitridation process at the later stage is likely to proceed. If the reduction treatment time is 1 hour or longer, the reduction is sufficiently facilitated. The reduction treatment time is more preferably 2 hours or more and 72 hours or less.

The atmosphere of the reduction process is, for example, an H ₂ atmosphere.

Next, nitriding treatment of the iron particles obtained by the reduction treatment is performed to obtain particles 2a containing an iron nitride phase. Examples of the iron nitride phase include, but are not particularly limited to, an Fe ₁₆ N ₂ phase.

  The nitriding temperature is preferably 100 ° C. or higher and 200 ° C. or lower. When the nitriding temperature is 100 ° C. or higher, nitriding is likely to proceed sufficiently. When the temperature of the nitriding treatment is 200 ° C. or less, the nitriding does not easily proceed excessively, and the deterioration of the magnetic characteristics is easily suppressed. The temperature of the nitriding treatment is more preferably 120 ° C. or higher and 180 ° C. or lower.

  The nitriding time is not particularly limited, but is preferably 1 hour or more and 48 hours or less. When the nitriding time is 48 hours or less, the magnetic characteristics are hardly deteriorated even if the nitriding temperature is increased. If the nitriding time is 1 hour or longer, nitriding is likely to proceed sufficiently. The nitriding time is more preferably 3 hours or more and 24 hours or less.

The atmosphere of the nitriding treatment is preferably an NH ₃ atmosphere. Further, nitriding treatment may be performed in an atmosphere in which N ₂ and / or H ₂ or the like is mixed in addition to NH ₃ .

  Moreover, an oxide phase can be formed on the surface of the particle | grains containing an iron nitride phase by performing the slow oxidation process of the particle | grains 2a containing the obtained iron nitride phase. The temperature of the gradual oxidation treatment is preferably 40 ° C. or higher and 100 ° C. or lower. By setting the temperature of the gradual oxidation treatment to 40 ° C. or higher, an oxide phase is easily formed on the particle surface, and the magnetic properties are hardly deteriorated. Further, when the temperature of the gradual oxidation treatment is 100 ° C. or lower, it becomes easy to control so that the ratio of the oxide phase does not become excessive, and the magnetic characteristics are not easily lowered. The temperature of the gradual oxidation treatment is more preferably 50 ° C. or higher and 80 ° C. or lower.

  The time for the gradual oxidation treatment is not particularly limited, but is preferably 1 hour or more and 96 hours or less. When the gradual oxidation treatment time is 96 hours or less, even if the gradual oxidation temperature is high or the oxygen concentration in the gradual oxidation atmosphere is high, the ratio of the oxide phase is hardly excessive and the magnetic characteristics are not easily lowered. . If the time for the gradual oxidation treatment is less than 1 hour or more, the oxide phase is sufficiently formed and the magnetic properties are not easily lowered. The time for the gradual oxidation treatment is more preferably 2 hours or more and 72 hours or less.

Xu atmosphere oxidation treatment is preferably _{N 2} atmosphere containing 10ppm or 500ppm or less _{O 2,} may be in addition to mixed with an inert gas such as He or Ar in _{N 2.} When O ₂ is 10 ppm or more, it is easy to sufficiently form an oxide phase, and the magnetic properties are hardly deteriorated. In addition, when O ₂ is 500 ppm or less, even if the gradual oxidation temperature is high, the ratio of the oxide phase does not easily become excessive, and the magnetic characteristics are hardly lowered. The content of O ₂ is more preferably 30 ppm or more and 100 ppm or less.

  The obtained iron nitride magnetic powder comprising particles 2a containing an iron nitride phase, a resin, a solvent, and, if necessary, an additive selected from various dispersants, plasticizers, and the like are kneaded with a ball mill or the like. As a result, an iron nitride magnetic powder slurry is obtained.

  Further, a resin, a solvent, and, if necessary, an additive selected from various dispersants, plasticizers, and the like are kneaded with a ball mill or the like to obtain a resin organic substance slurry.

  The iron nitride magnetic powder slurry and the resin organic slurry obtained by the above-described steps are respectively applied and dried to obtain an iron nitride magnetic powder sheet and a resin organic sheet. When producing an iron nitride magnetic powder sheet, a magnetic orientation treatment may be performed using a magnet or the like after applying the iron nitride magnetic powder slurry and before drying. There is no particular limitation on the method of applying each slurry. A typical method is a doctor blade method.

  Next, the iron nitride magnetic powder sheet obtained by the above-described process and the resin organic material sheet are alternately laminated to obtain a laminate. Subsequently, the obtained laminated body is gently pressed from both sides in the laminating direction to obtain the iron nitride bond magnet 1. There is no restriction | limiting in particular in the pressure at the time of pressurization, What is necessary is just a moderate pressure so that the magnetic orientation in an iron nitride type magnetic powder sheet may not collapse. For example, it can be 1.0 MPa or more and 100 MPa or less.

  The magnetic characteristics of the iron nitride-based bonded magnet according to the present embodiment are remarkably improved because the iron nitride-based magnetic powder sheet is magnetically oriented and pressed so that the orientation does not collapse in subsequent steps. It is considered that the degree of orientation of the iron nitride-based bonded magnet 1 becomes very high.

  When the laminate is pressurized, it may be pressurized while applying a magnetic field. By applying pressure while applying a magnetic field, the iron nitride-based magnetic powder contained in the finally obtained iron nitride-based bonded magnet 1 is further oriented in a specific direction, so that the iron nitride-based bonded magnet has more excellent magnetic properties. 1 can be obtained.

  The obtained iron nitride-based bonded magnet 1 may be plated or painted on the surface in order to prevent deterioration of the oxide layer, resin, or the like.

  Next, the iron nitride-based bonded magnet of the present invention will be described in more detail using examples and comparative examples, but the present invention is not limited to the embodiments shown in the examples.

(Example 1) 167 g of iron sulfate heptahydrate (FeSO ₄ · 7H ₂ O) and 85 g of iron chloride hexahydrate (FeCl ₃ · 6H ₂ O) are dissolved in 248 mL of ion-exchanged water. Produced. Separately from the iron salt aqueous solution, 600 g of a 2.5 mol / L ammonia aqueous solution prepared was maintained at 30 ° C., and 500 g of the iron salt aqueous solution prepared previously was added to 600 g of the ammonia aqueous solution. Thereafter, the temperature of the aqueous ammonia solution was controlled so as to be constant at 70 ° C., and the mixture was stirred for 30 minutes to advance the aging reaction in the liquid, thereby generating iron oxide. Then, the iron oxide slurry was produced by performing washing | cleaning 3 times with 2L ion-exchange water using a centrifuge.

To 1000 g of the iron oxide slurry, 5.0 g of tetraethoxysilane, 21 g of ethanol, and 78 g of diethylene glycol monobutyl ether were added to perform Si deposition treatment. The iron oxide slurry subjected to the Si deposition treatment was filtered and then dried at 85 ° C. for 24 hours to produce iron oxide particles containing Fe ₂ O ₃ .

  2 g of the iron oxide particles were placed in a firing boat and left in a heat treatment furnace. After filling the furnace with nitrogen gas, increase the temperature to 250 ° C. at a rate of 5 ° C./min while flowing hydrogen gas at a flow rate of 1 L / min. It was. After maintaining at 250 ° C. for 48 hours, the supply of hydrogen gas was stopped and the temperature was lowered to 140 ° C. while flowing nitrogen gas at a flow rate of 2 L / min. Subsequently, nitriding treatment was performed by maintaining ammonia gas at a flow rate of 0.2 L / min and holding at 140 ° C. for 24 hours. After holding at 140 ° C. for 24 hours, the temperature was lowered to 50 ° C. while flowing nitrogen gas at a flow rate of 2 L / min.

  Next, a resin and a solvent to be kneaded with the obtained iron nitride magnetic powder were prepared. Urethane resin was prepared as a resin, and xylene, methyl ethyl ketone and cyclohexanone were prepared as solvents. A urethane resin having a molecular weight of 23,000 was used. The solvent used was a mixture of xylene, methyl ethyl ketone and cyclohexanone in a weight ratio of 4: 4: 2.

  10 g of the iron nitride magnetic powder, 4.7 g of the urethane resin, and 30 g of the solvent were weighed and kneaded with a zirconia ball having a diameter of 2 mm for 20 hours by a ball mill to obtain an iron nitride magnetic powder slurry.

  Further, 4.7 g of the urethane resin and 30 g of the solvent were weighed and kneaded with a zirconia ball having a diameter of 2 mm for 20 hours by a ball mill to obtain a resin organic slurry.

  The iron nitride magnetic powder slurry was applied onto a PET film by a doctor blade method to obtain an iron nitride magnetic powder sheet. Moreover, the resin organic substance slurry was apply | coated by the doctor blade method on PET film, and the resin organic substance sheet was obtained.

  The gap of the blade was adjusted so that the thickness of the iron nitride magnetic powder layer in the finally obtained iron nitride bond magnet was 15 μm. Further, the gap of the blade was adjusted so that the thickness of the resin organic material layer in the finally obtained iron nitride-based bonded magnet was 3 μm.

  The produced iron nitride-based magnetic powder sheet and the resin organic material sheet are peeled off from the PET film, alternately laminated, and molded by applying a pressure of 20 MPa from both sides in the lamination direction, thereby providing an iron nitride-based bond having a laminated structure. A magnet was obtained.

  (Example 2) An iron nitride-based bonded magnet was produced in the same manner as in Example 1 except that the amount of tetraethoxysilane added to the iron oxide slurry was 4.0 g.

  Example 3 An iron nitride-based bonded magnet was produced in the same manner as in Example 1 except that the amount of tetraethoxysilane added to the iron oxide slurry was 2.5 g.

  (Example 4) Except that the amount of tetraethoxysilane added to the iron oxide slurry was 2.5 g, and the blade gap was adjusted so that the thickness of the finally obtained iron nitride magnetic powder layer was 9 μm, In the same manner as in Example 1, an iron nitride based bonded magnet was produced.

  (Example 5) Except that the amount of tetraethoxysilane added to the iron oxide slurry was 2.5 g, and the blade gap was adjusted so that the thickness of the finally obtained iron nitride magnetic powder layer was 12 μm, In the same manner as in Example 1, an iron nitride based bonded magnet was produced.

  (Example 6) Except that the amount of tetraethoxysilane added to the iron oxide slurry was 2.5 g, and the blade gap was adjusted so that the thickness of the finally obtained iron nitride magnetic powder layer was 21 μm, In the same manner as in Example 1, an iron nitride based bonded magnet was produced.

  (Example 7) The amount of tetraethoxysilane added to the iron oxide slurry was 2.5 g, and the blade gap was adjusted so that the thickness of the finally obtained iron nitride-based magnetic powder layer was 30 μm, In the same manner as in Example 1, an iron nitride based bonded magnet was produced.

  (Example 8) The amount of tetraethoxysilane added to the iron oxide slurry was 2.5 g, and the blade gap was adjusted so that the thickness of the finally obtained iron nitride magnetic powder layer was 5 μm. An iron nitride-based bonded magnet was produced in the same manner as in Example 1 except that the blade gap was adjusted so that the thickness of the obtained resin organic layer was 1 μm.

  (Example 9) The amount of tetraethoxysilane added to the iron oxide slurry is 2.5 g, and the blade gap is adjusted so that the thickness of the finally obtained iron nitride magnetic powder layer is 10 μm. An iron nitride-based bonded magnet was produced in the same manner as in Example 1 except that the blade gap was adjusted so that the thickness of the resulting resin organic layer was 2 μm.

  (Example 10) The amount of tetraethoxysilane added to the iron oxide slurry is 2.5 g, and the blade gap is adjusted so that the thickness of the finally obtained iron nitride magnetic powder layer is 20 μm. An iron nitride-based bonded magnet was produced in the same manner as in Example 1 except that the blade gap was adjusted so that the thickness of the obtained resin organic layer was 4 μm.

  (Example 11) The amount of tetraethoxysilane added to the iron oxide slurry was 2.5 g, and the blade gap was adjusted so that the thickness of the finally obtained iron nitride magnetic powder layer was 25 μm, and finally An iron nitride-based bonded magnet was produced in the same manner as in Example 1 except that the blade gap was adjusted so that the thickness of the obtained resin organic layer was 5 μm.

  (Example 12) An iron nitride-based bonded magnet was produced in the same manner as in Example 1 except that the amount of tetraethoxysilane added to the iron oxide slurry was 1.8 g.

  (Example 13) An iron nitride-based bonded magnet was produced in the same manner as in Example 1 except that the amount of tetraethoxysilane added to the iron oxide slurry was 0.8 g.

  (Example 14) An iron nitride-based bonded magnet was produced in the same manner as in Example 1 except that the amount of tetraethoxysilane added to the iron oxide slurry was 0.6 g.

  (Comparative Example 1) Except that the amount of tetraethoxysilane added to the iron oxide slurry was 2.5 g and the blade gap was adjusted so that the finally obtained iron nitride magnetic powder layer had a thickness of 7.5 μm. Produced an iron nitride-based bonded magnet in the same manner as in Example 1.

  (Comparative example 2) Other than the point that the amount of tetraethoxysilane added to the iron oxide slurry was 2.5 g, and the blade gap was adjusted so that the finally obtained iron nitride magnetic powder layer had a thickness of 31.5 μm Produced an iron nitride-based bonded magnet in the same manner as in Example 1.

  (Comparative Example 3) The amount of tetraethoxysilane added to the iron oxide slurry was 2.5 g, and the blade gap was adjusted so that the thickness of the finally obtained iron nitride magnetic powder layer was 2.5 μm. An iron nitride-based bonded magnet was produced in the same manner as in Example 1 except that the blade gap was adjusted so that the thickness of the resin organic layer thus obtained was 0.5 μm.

  (Comparative Example 4) The amount of tetraethoxysilane added to the iron oxide slurry was 2.5 g, and the blade gap was adjusted so that the thickness of the finally obtained iron nitride magnetic powder layer was 27.5 μm. An iron nitride-based bonded magnet was produced in the same manner as in Example 1 except that the blade gap was adjusted so that the thickness of the resin organic layer thus obtained was 5.5 μm.

(Comparative Example 5) First, an iron nitride magnetic powder slurry and a resin organic matter slurry were obtained in the same manner as in Example 1 except that the amount of tetraethoxysilane added to the iron oxide slurry was 2.5 g. Next, the iron nitride magnetic powder slurry and the resin organic slurry were mixed at a weight ratio of 5: 1 to obtain a mixed slurry. Furthermore, the mixed slurry was dried in a hot air dryer for 24 hours to obtain a mixed powder of iron nitride magnetic powder and organic powder. Then, the mixed powder was filled in a mold and compression-molded by applying a load of 3 kgf / cm ² to produce an iron nitride-based bonded magnet having no laminated structure.

<Confirmation that iron nitride magnetic powder contains iron nitride phase>
About the produced iron nitride magnetic powder, an X-ray diffraction profile was obtained by powder XRD (Rigaku RINT-2500). From the X-ray diffraction profile, it was confirmed that the iron nitride magnetic powder was a particle containing an iron nitride phase. Examples of the iron nitride phase identified by the X-ray diffraction profile include an Fe ₁₆ N ₂ compound phase, but are not particularly limited.

<Identification of constituent layers in the cross section of iron nitride-based bonded magnet>
The obtained iron nitride-based bonded magnet was cut out so that a cross section appeared in a direction perpendicular to the stacking direction. A cross section of the 1.0 μm × 1.0 μm measurement region was observed at a magnification of 200,000 with a transmission electron microscope (TEM, JEM-2100FCS manufactured by JEOL), and element distribution mapping was performed with EDS. From the element mapping image, a layer containing Fe, N and C was identified as an iron nitride magnetic powder layer, and a layer containing only C (a layer in which Fe and N were not detected) was identified as a resin organic material layer.

<Identification of cross-sectional area ratio of each constituent layer>
The cross section of the iron nitride bond magnet is observed in 500 different 50 μm × 50 μm measurement areas, and the cross-sectional area ratio in each area is calculated and averaged. The cross-sectional area ratio was calculated.

<Thickness per layer of organic resin layer>
The thickness per layer of the organic resin layer was calculated from the cross-sectional area ratio of each constituent layer, the length of the organic resin layer, and the number of organic resin layers.

<Equivalent circle diameter of particles containing iron nitride phase>
From the cross-sectional area ratio of each constituent layer, the area of each measurement region, and the number of particles containing the iron nitride phase in each measurement region, the equivalent circle diameter of the particles containing the iron nitride phase was calculated.

<Measurement of residual magnetization Br and coercive force Hc>
A BH tracer (TRE-5BH manufactured by Toei Kogyo Co., Ltd.) was used to measure the residual magnetization Br and the coercive force Hc of the obtained iron nitride-based bonded magnet. The residual magnetization Br and the coercive force Hc were obtained from a demagnetization curve obtained by changing the externally applied magnetic field from 25 kOe to −25 kOe. In this example, an iron nitride based bond magnet having a residual magnetization Br of 3.0 kG or more and a coercive force Hc of 2.0 kOe or more was considered to have good magnetic properties. In addition, an iron nitride-based bonded magnet having a residual magnetization Br of 4.0 kG or more and a coercive force Hc of 2.5 kOe or more was further improved in magnetic characteristics.

<Measurement of bending strength>
The bending strength was measured by processing the obtained iron nitride-based bonded magnet into a size of 80 mm × 10 mm × 4 mm and using a bending strength tester (INSTRON 5543 manufactured by Instron Japan Company Limited) according to JIS K7171 standard. Five test samples were prepared for each level, the bending strength was measured, and the average value was taken as the bending strength for each level. The case where the bending strength was 25 MPa or more was considered good. Moreover, the case where bending strength was 35 Mpa or more was made further favorable.

In all Examples and Comparative Examples, it was confirmed that the iron nitride magnetic powder was composed of an Fe ₁₆ N ₂ compound phase.

  From Examples 1 to 14, when the cross-sectional area ratio and the thickness per layer of the resin organic material layer were within the predetermined ranges, Br, Hc and bending strength were all good.

  From Examples 1 to 3 and 12 to 14, when the equivalent circle diameter of the particles containing the iron nitride phase was 30 nm or more and 150 nm or less (Examples 2, 3, 12 and 13), Hc was even better. .

  From Examples 3 to 7, when the cross-sectional area ratio was 4.0 or more and 7.0 or less (Examples 4 to 6), the Br and bending strength were even better. On the other hand, in Comparative Example 1 in which the cross-sectional area ratio was 2.5, Br was significantly reduced. Further, in Comparative Example 2 in which the cross-sectional area ratio was 10.5, the bending strength was remarkably reduced.

  It can be considered that the reason why Br was significantly reduced in Comparative Example 1 was that the proportion of the ferromagnetic phase contained in the iron nitride-based bonded magnet was too small. Further, the reason why the bending strength is remarkably lowered in Comparative Example 2 is that the ratio of the resin contained in the iron nitride-based bonded magnet is reduced, and the iron nitride-based magnetic powder layers cannot be sufficiently bonded to each other by the resin organic material layer. It is thought that.

  From Examples 3 and 8 to 11, when the thickness per layer of the resin organic material layer was 2.0 μm or more and 4.0 μm or less (Examples 3, 9 and 10), the bending strength was even better. On the other hand, the comparative example 3 in which the thickness per layer of the resin organic material layer is 0.5 μm and the comparative example 4 in which the thickness is 5.5 μm are remarkably lowered in bending strength.

  The reason why the bending strength is remarkably reduced in Comparative Example 3 is considered to be because the thickness of the resin organic material layer is too thin and the iron nitride magnetic powder layers cannot be sufficiently bonded to each other by the resin organic material layer.

  The reason why the bending strength is remarkably lowered in Comparative Example 4 is considered to be that cracks are likely to occur inside the iron nitride magnetic powder layer because the iron nitride magnetic powder layer becomes too thick. .

  As shown in Comparative Example 5, even in the case of an iron nitride-based bonded magnet not having the laminated structure of the present invention, the bending strength was extremely low. This is considered to be because the bending strength resulting from the laminated structure of the present invention was not obtained because the particles containing the iron nitride phase and the resin were uniformly mixed.

  As described above, the iron nitride-based bonded magnet according to the present invention has high residual magnetization, high coercive force, and high mechanical strength (particularly bending strength), and thus is useful as a magnet that does not use rare earth.

DESCRIPTION OF SYMBOLS 1 Iron nitride type bonded magnet 2 Iron nitride type magnetic powder layer 2a Particles containing iron nitride phase 4 Resin organic material layer 4a Resin organic material

Claims (4)

An iron nitride-based bond magnet containing iron nitride-based magnetic powder and resin,
The iron nitride magnetic powder is composed of particles containing an iron nitride phase,
The cross-sectional structure of the iron nitride-based bonded magnet is a structure in which a plurality of iron nitride-based magnetic powder layers including the iron nitride-based magnetic powder and a resin organic material layer made of the resin are alternately stacked,
The ratio represented by (the cross-sectional area of the iron nitride magnetic powder layer / the cross-sectional area of the resin organic material layer) is 3.0 or more and 10.0 or less,
An iron nitride-based bonded magnet having a thickness per layer of the organic resin layer of 1.0 μm or more and 5.0 μm or less.   2. The iron nitride-based bonded magnet according to claim 1, wherein a ratio represented by (the cross-sectional area of the iron nitride-based magnetic powder layer / the cross-sectional area of the resin organic material layer) is 4.0 or more and 7.0 or less.   The iron nitride based bonded magnet according to claim 1 or 2, wherein the resin organic layer has a thickness of 2.0 µm or more and 4.0 µm or less. The iron nitride-based bond magnet according to any one of claims 1 to 3, wherein an average equivalent circle diameter of the particles containing the iron nitride phase is 30 nm or more and 150 nm or less.

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