JP2018198281A - Iron nitride magnet - Google Patents

Abstract

To provide an iron nitride magnet having high magnetic properties and high mechanical strength.SOLUTION: There is provided an iron nitride magnet composed of an iron nitride magnetic particle and low melting point glass. The low melting point glass contains at least one element contained in the iron nitride based magnetic particle.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an iron nitride-based 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 an invention of an iron nitride magnet including an Fe ₁₆ N ₂ phase. However, at present, there is a demand for a magnet having further improved magnetic properties and mechanical strength. Patent Document 2 describes that a low-melting glass is added to increase the mechanical strength. However, even in the magnet described in Patent Document 2, desired mechanical characteristics may not be obtained.

JP-A-2006-134583 JP, 2015-103770, A

  The present invention has been made in view of the above, and an object thereof is to provide an iron nitride-based magnet having high magnetic properties and high mechanical strength.

The iron nitride magnet according to the present invention is
An iron nitride magnet composed of iron nitride magnetic particles and low melting point glass,
The low melting glass contains at least one element contained in the iron nitride magnetic particles.

  The iron nitride magnet according to the present invention has higher magnetic properties and higher mechanical strength than conventional iron nitride magnets.

The iron nitride magnet according to the present invention is
The ratio represented by (the cross-sectional area of the low-melting glass / the cross-sectional area of the iron nitride magnetic particles) is 0.10 or more and 0.40 or less,
The iron nitride-based magnetic particles contain P at 1.0 at% to 4.0 at%,
The low melting point glass is made of phosphate glass,
Even if the phosphate glass is made of P ₂ O ₅ —Ag ₂ O glass, P ₂ O ₅ —V ₂ O ₅ glass, or P ₂ O ₅ —Ag ₂ O—V ₂ O ₅ glass. Good.

  The ratio represented by (the cross-sectional area of the low-melting glass / the cross-sectional area of the iron nitride magnetic particles) may be 0.20 or more and 0.30 or less.

  The iron nitride magnetic particles may contain P at 2.1 at% to 3.0 at%.

  The average equivalent circle diameter of the iron nitride magnetic particles may be 30 nm to 150 nm.

FIG. 1 is a schematic cross-sectional view of an iron nitride magnet according to an embodiment of the present invention.

  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, the cross section of the iron nitride-based magnet 1 according to the present invention includes iron nitride-based magnetic particles 2 and low-melting glass 3, and low-melting-point glass is interposed between the iron nitride-based magnetic particles 2. 3 is filled.

The iron nitride magnetic particles 2 contain iron nitride and are ferromagnetic. 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. Further, the iron nitride magnetic particles 2 may contain a transition metal such as Mn, Ni, Co, Ti, Zn. Moreover, the component contained in the said iron nitride type magnetic particle 2 is not limited to said component, As long as the effect of this invention is not disturbed, the other component may be included.

  The ratio of iron nitride in the iron nitride magnetic particles 2 is not particularly limited, but is preferably 95% by weight or more. Moreover, it can be confirmed using XRD that the iron nitride magnetic particles 2 contain iron nitride. Moreover, there is no restriction | limiting in particular in content of said component. For example, the total amount of the iron nitride magnetic particles 2 may be 100% by weight, the transition metal such as Mn, Ni, Co, Ti, and Zn may be 1% by weight or less, and the other components may be 1% by weight or less. Good.

Further, the surface of the iron nitride magnetic particles 2 may be covered with an oxide (not shown). There is no particular limitation on the oxide, for example, _{Fe 2 O 3, Fe 3 O} 4 or iron oxide such as FeO and the like. Further, the oxide may contain a small amount of Si compound or the like.

  In the cross section of the iron nitride-based magnet 1 according to the present embodiment, a ratio represented by (the cross-sectional area of the low melting point glass / the cross-sectional area of the iron nitride-based magnetic particles) (hereinafter, simply referred to as “cross-sectional area ratio”). ) Is preferably in the range of 0.10 to 0.40. When the cross-sectional area ratio is 0.10 or more, the amount of the low melting point glass 3 in the cross section of the iron nitride-based magnet 1 becomes a sufficient amount, and voids are generated between the plurality of iron nitride-based magnetic particles 2. It is easy to suppress, and it is easy to fully improve mechanical strength (especially bending strength). Further, when the cross-sectional area ratio is 0.40 or less, iron nitride having ferromagnetism tends to be sufficiently increased in the iron nitride magnet 1. That is, since the portion having ferromagnetism is sufficiently secured, the saturation magnetization is likely to be sufficiently improved. More preferably, the cross-sectional area ratio is in the range of 0.20 to 0.30.

  The low melting point glass 3 contains at least one element contained in the iron nitride magnetic particles 2. In other words, the iron nitride magnet 1 according to the present embodiment includes at least one element contained in both the low melting point glass 3 and the iron nitride magnetic particles 2.

  There are no particular restrictions on the types of elements contained in both the low-melting glass 3 and the iron nitride magnetic particles 2. For example, at least one selected from Fe, Mn, Ni, Co, Ti, Zn, Be, B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl, K, and Ca is there.

  The case of “included in both the low melting glass 3 and the iron nitride magnetic particles 2” means that “the content in the low melting glass 3 is 0.1 at% or more, and the iron nitride. The case where the content in the system magnetic particles 2 is 0.1 at% or more is indicated.

The element contained in both the low-melting glass 3 and the iron nitride magnetic particles 2 is preferably P. In this case, it is preferable that the amount of P contained in the iron nitride magnetic particles is 1.0 at% or more and 4.0 at% or less. By containing P in the iron nitride-based magnetic particles, P penetrates into the lattice of Fe ₁₆ N ₂ , or P substitutes a part of N constituting Fe ₁₆ N ₂ , whereby Fe ₁₆ N ₂ This is because the lattice of the above is distorted, the anisotropy of the iron nitride magnetic particles is increased, and a high coercive force can be obtained while maintaining a high saturation magnetization. The amount of P contained in the iron nitride magnetic particles is more preferably 2.1 at% or more and 3.0 at% or less. The low melting point glass 3 is preferably a phosphate glass. More preferably, the phosphate glass is made of P ₂ O ₅ —Ag ₂ O glass, P ₂ O ₅ —V ₂ O ₅ glass, or P ₂ O ₅ —Ag ₂ O—V ₂ O ₅ glass.

The kind of the low melting point glass 3 has an appropriate composition and particle size in consideration that the temperature at which the iron nitride magnet 1 can be sufficiently densified (densification temperature) becomes an appropriate temperature during the heat treatment described later. It is preferable to select a low melting glass. Moreover, you may add an additive suitably to the low melting glass 3 if it is a range which does not prevent the effect of this invention. Examples of the additive include B ₂ O ₃ and ZnO, but are not limited thereto.

  The reason why the iron nitride magnet 1 according to the present embodiment has a high coercive force is that the low melting glass 3 exists between the plurality of iron nitride magnetic particles 2 and the low melting glass 3 is nonmagnetic. This is probably because the iron nitride magnetic particles 2 are magnetically separated. Furthermore, the fact that the iron nitride magnetic particles 2 contain a predetermined amount of P changes the crystal magnetic anisotropy of the iron nitride magnetic particles 2, which is why the coercive force of the iron nitride magnet 1 is improved. it is conceivable that. Moreover, it is thought that coercive force and saturation magnetization can be made compatible by adjusting the cross-sectional area ratio.

  Furthermore, the reason why the iron nitride magnet 1 according to the present embodiment has high mechanical strength (particularly bending strength) is good because both the iron nitride magnetic particles 2 and the low melting point glass 3 contain a common element. This is considered to show wettability. Further, it is considered that the mechanical strength is improved by the low melting point glass 3 serving as a binder for the iron nitride magnetic particles 2.

  Here, a method for identifying the iron nitride magnetic particles 2 and the low-melting glass 3 will be described, and a method for identifying the cross-sectional area ratio will be described.

  The iron nitride magnetic particles 2 and the low melting point glass 3 can be identified by observing the cross section of the iron nitride magnet 1. For example, a cross section of a measurement region of 1.0 μm × 1.0 μm is observed with a transmission electron microscope at a magnification of 200,000, element distribution mapping is further performed with EDS, and an element derived from an element containing iron nitride is included in the element mapping image Is the iron nitride magnetic particles 2. Specifically, the portion where Fe and N are detected by element mapping is referred to as iron nitride magnetic particles 2. On the other hand, only the element derived from the low-melting glass and containing only the element derived from iron nitride is referred to as the low-melting glass 3. When the low-melting glass is the above-mentioned phosphate glass, specifically, Fe and N are not detected by element distribution mapping and are included in both the iron nitride magnetic particles 2 and the low-melting glass. A portion where the element is detected by element distribution mapping and Ag and / or V is detected by element distribution mapping is identified as the low melting glass 3. In the case of using a low melting point glass containing N, Fe is not detected by element distribution mapping, and elements contained in both the iron nitride magnetic particles 2 and the low melting point glass are detected by element distribution mapping. A portion where an element contained only in the low melting point glass containing N is detected by element distribution mapping is identified as the low melting point glass 3.

  Regarding the cross-sectional area ratio, first, cross-sectional observation is performed with respect to the cross section of the iron nitride-based magnet 1 in 500 different measurement areas, and the cross-sectional area ratio in each measurement area is calculated. Then, the cross-sectional area ratio of the iron nitride magnet can be calculated by averaging the cross-sectional area ratios in the 500 regions.

  The content of the common element contained in the iron nitride magnetic particles 2 can be identified by element mapping using EDS.

  The average equivalent circle diameter of the iron nitride magnetic particles 2 is preferably 30 nm or more and 150 nm or less. When the average equivalent circle diameter of the iron nitride magnetic particles 2 is within the above range, the coercive force tends to increase. The average equivalent circle diameter of the iron nitride magnetic particles 2 can be calculated from the total area of the iron nitride magnetic particles 2 in each measurement region and the total number of iron nitride magnetic particles in each measurement region.

  Hereinafter, a preferred method for manufacturing the iron nitride magnet 1 according to the present embodiment will be described. Hereinafter, although the suitable manufacturing method in case the iron nitride magnet 1 is an iron nitride bond magnet is described, the manufacturing method of the iron nitride magnet 1 according to the present embodiment is not limited to the following method.

  First, iron oxide particles to be a raw material for the iron nitride magnetic particles 2 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 is no restriction | limiting in particular in the kind of said iron salt, For example, a sulfate, a chloride, nitrate etc. can be used, You may use combining these suitably. Moreover, those hydrates can be used.

  The kind of the aqueous alkali solution is not particularly limited, 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, sodium silicate, 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 iron nitride-based magnetic particles 2 finally obtained can be obtained. It becomes easy to control to 150 nm or less. By making it 20% by weight or less, it becomes easy to moderately suppress sintering between iron oxide particles during heat treatment, and it becomes easy to control the average equivalent circle diameter of iron nitride-based magnetic particles 2 finally obtained to 30 nm or more. .

  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 diameter to 10 nm or more and 150 nn or less, it becomes easy to control the average of equivalent circle diameters of the finally obtained iron nitride magnetic particles 2 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 iron nitride magnetic powder according to this 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 iron nitride magnetic powder may be subjected to a slow oxidation treatment at a low temperature and a low oxygen partial pressure to form an oxide on the surface of the iron nitride magnetic powder.

  Hereinafter, the reduction process and the nitriding process 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 more, 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, the sintering between the particles does not easily proceed even if the temperature for 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 iron particles obtained by the reduction treatment is performed. When the common element is P, in this embodiment, a mixed gas of ammonia gas and phosphine gas is used in the nitriding treatment. By controlling the ratio of the phosphine gas in the mixed gas, the content of P in the iron nitride magnetic powder can be controlled.

The ratio of the phosphine gas in the mixed gas of ammonia gas and phosphine gas is preferably 0.8 mol% or more and 29 mol% or less. By making the ratio of the phosphine gas 0.8 mol% or more, the content of P in the iron nitride magnetic powder is easily made 0.1 at% or more, and the iron nitride contained in the iron nitride magnet 1 finally obtained The effect of penetration and substitution of P into the system magnetic particles 2 can be sufficiently obtained. And it becomes easy to make content of P in the iron nitride type magnetic particle 2 contained in the iron nitride type magnet 1 finally obtained into 1.0 at% or more. By making the ratio of the phosphine gas 29 mol% or less, the content of P in the iron nitride-based magnetic powder can be easily made 4.5 at% or less, and Fe ₃ P in which a part of iron nitride Fe ₁₆ N ₂ is an impurity. It becomes difficult to cause a reaction that changes to. And it becomes easy to make content of P in iron nitride system magnetic particles 2 contained in iron nitride system magnet 1 finally obtained into 4.0 at% or less.

  The temperature of the nitriding treatment is preferably 100 to 200 ° C. 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.

  At this time, iron oxide may exist on the surface of the iron nitride magnetic powder.

  The phosphate glass powder according to the present embodiment can be produced by a vapor deposition method, a sputtering method, a flame spray pyrolysis method, a high-frequency thermal plasma method, or the like, but may be produced by other methods. At this time, the average particle diameter of the phosphate glass powder is preferably 10 nm or more and 30 nm or less. By setting the average particle diameter of the phosphate glass powder within the above range, the phosphate glass can be uniformly filled between the particles of the iron nitride magnetic particles in the molded body described later.

Examples of the phosphate type _glass, may be used P ₂ O 5 -Ag ₂ O and _{P 2 O 5 -V 2 O 5} , P 2 O 5 -Ag 2 O-V 2 O 5. There is no restriction | limiting in particular in the ratio of each component in each phosphate glass. The softening point (melting point) of each phosphate glass can be controlled by changing the composition ratio and particle diameter of each component, and is 150 ° C. or less, which is the temperature when densifying the iron nitride magnet. Control to soften. Specifically, the softening point tends to increase by increasing the content ratio of P ₂ O ₅ contained in the phosphate glass. The softening point can also be controlled by changing the content ratio of Ag ₂ O and / or V ₂ O ₅ . Moreover, it exists in the tendency for a softening point to become low by making the particle diameter of the said phosphate glass small.

  When the common element is other than P, the common element is contained in the iron nitride magnetic powder and the glass powder by a known method.

Next, an iron nitride magnetic powder and a phosphate glass powder are mixed to obtain a mixed powder. The mixing method is not particularly limited, and may be wet mixing or dry mixing. The mixed powder is put into a mold having an arbitrary shape and size, and a load of 3 kgf / cm ² or more and 20 kgf / cm ² or less is applied to produce a molded body. By setting it as the load of this range, a molded object has sufficient shape retention property and the crack which generate | occur | produces in a molded object can be suppressed. More preferably, it is 10 kgf / cm ² or more and 20 kgf / cm ² or less.

  The molded body may be molded while applying a magnetic field when it is molded into a predetermined shape. By shaping while applying a magnetic field, the finally obtained iron nitride-based magnet 1 is oriented in a specific direction, so that the iron nitride-based magnet 1 with more excellent magnetic properties can be obtained.

The obtained compact is densified by heat treatment at a temperature of 150 ° C. or lower to obtain an iron nitride-based magnet 1. When heat treatment is performed at a temperature exceeding 150 ° C., the iron nitride (Fe ₁₆ N ₂ compound) contained in the iron nitride-based magnetic particles 2 may be decomposed, and the magnetic properties may be significantly deteriorated. The heat treatment temperature is more preferably 130 ° C. or lower. It is also possible to increase the density by applying an energization process using SPS.

The atmosphere for the heat treatment is not particularly limited, but is preferably an inert atmosphere such as N ₂ , He, Ar, or a vacuum.

  As the heat treatment, in addition to general atmospheric heat treatment, for example, pressure heat treatment such as hot pressing, HIP, SPS and the like can be selected. However, the present invention is not limited to these methods, and other methods are employed. You can also.

  The obtained iron nitride-based magnet 1 may be plated or painted in order to prevent surface deterioration.

  Next, the iron nitride-based magnet according to the present invention will be described in more detail using examples and comparative examples, but the present invention is not limited to the mode 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, the ammonia gas flow rate was set to 165 mL / min, the phosphine gas flow rate was set to 35 mL / min, and a mixed gas of ammonia gas and phosphine gas was allowed to flow and maintained at 140 ° C. for 24 hours for nitriding. 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. Finally, air substitution was carried out for 24 hours to produce an iron nitride magnetic powder.

Next, to obtain a _{40P 2 O} 5 -60Ag 2 _O glass powder having an average particle diameter of about 20nm by sputtering. Specifically, sputtering was applied to the target material of P ₂ O ₅ and Ag ₂ O to obtain 40P ₂ O ₅ -60Ag ₂ O glass powder. The sputtering conditions were atmospheric pressure, pressure of 20 Pa, vapor deposition current of about 10 mA, and reaction time of 15 min. Note that _{"40P 2 O} 5 -60Ag 2 _O", P ₂ O 5: refers to Ag ₂ O is 40:60 in molar ratio.

A slurry was prepared by mixing 59 g of the iron nitride magnetic powder and 4.8 g of the 40P ₂ O ₅ -60Ag ₂ O glass powder with 1000 g of sufficiently dehydrated toluene. The slurry was dispersed with a homomixer and then dried at 25 ° C. for 24 hours to obtain a mixed powder composed of iron nitride magnetic particles and 40P ₂ O ₅ -60Ag ₂ O glass particles.

The obtained mixed powder was filled in a 12 × 12 mm mold, and a pressure of 10 kgf / cm ² was applied at room temperature to obtain a molded body for magnetic property evaluation. Moreover, it filled with the 90x12 mm metal mold | die, and applied the pressure of 10 kgf / cm < ² > at room temperature, and obtained the molded object for bending strength measurement.

  Each obtained molded object was left still in the heat treatment furnace, and the inside of the furnace was filled with argon gas. Thereafter, the compact was densified by heat treatment at 130 ° C. for 2 hours while flowing argon gas at a flow rate of 2 L / min, and an iron nitride magnet was obtained.

(Example 2) The amount of tetraethoxysilane added to the iron oxide slurry is 4.0 g, the flow rate of ammonia gas during nitriding is 166 mL / min, the flow rate of phosphine gas is 34 mL / min, and the blending amount of the mixed powder Was made in the same manner as in Example 1 except that 63 g of iron nitride magnetic powder and 4.8 g of 40P ₂ O ₅ -60Ag ₂ O glass powder were used.

(Example 3) The amount of tetraethoxysilane added to the iron oxide slurry is 2.5 g, the flow rate of ammonia gas during nitriding is 185 mL / min, the flow rate of phosphine gas is 16 mL / min, and the blending amount of the mixed powder Was made in the same manner as in Example 1 except that 56 g of iron nitride magnetic powder and 4.8 g of 40P ₂ O ₅ -60Ag ₂ O glass powder were used.

  (Example 4) Except that the amount of tetraethoxysilane added to the iron oxide slurry was 2.5 g, the flow rate of ammonia gas during nitriding was 170 mL / min, and the flow rate of phosphine gas was 30 mL / min. An iron nitride magnet was produced in the same manner as in Example 1.

  (Example 5) Except that the amount of tetraethoxysilane added to the iron oxide slurry is 2.5 g, the flow rate of ammonia gas during nitriding is 164 mL / min, and the flow rate of phosphine gas is 36 mL / min. An iron nitride magnet was produced in the same manner as in Example 1.

(Example 6) The amount of tetraethoxysilane added to the iron oxide slurry is 2.5 g, the flow rate of ammonia gas during nitriding is 160 mL / min, the flow rate of phosphine gas is 40 mL / min, and the blending amount of the mixed powder Was made in the same manner as in Example 1 except that 59 g of iron nitride magnetic powder and 4.8 g of 40P ₂ O ₅ -60Ag ₂ O glass powder were used.

  (Example 7) Implementation was performed except that the amount of tetraethoxysilane added to the iron oxide slurry was 2.5 g, the flow rate of ammonia gas during nitriding was 150 mL / min, and the flow rate of phosphine gas was 50 mL / min. An iron nitride magnet was produced in the same manner as in Example 1.

(Example 8) the amount of tetraethoxysilane is added to the iron oxide slurry and 2.5g, the amount of iron nitride-based magnetic powder 234g of the mixed _powder, was 40P ₂ O 5 -60Ag ₂ O glass powder 4.8g Except for this point, an iron nitride magnet was produced in the same manner as in Example 1.

(Example 9) The amount of tetraethoxysilane added to the iron oxide slurry is 2.5 g, the flow rate of ammonia gas during nitriding is 164 mL / min, the flow rate of phosphine gas is 36 mL / min, and the blending amount of the mixed powder Was made in the same manner as in Example 1 except that 77 g of iron nitride magnetic powder and 4.8 g of 40P ₂ O ₅ -60Ag ₂ O glass powder were used.

(Example 10) The amount of tetraethoxysilane added to the iron oxide slurry is 2.5 g, the flow rate of ammonia gas during nitriding is 166 mL / min, the flow rate of phosphine gas is 34 mL / min, and the blending amount of the mixed powder Was made in the same manner as in Example 1, except that 47 g of iron nitride magnetic powder and 4.8 g of 40P ₂ O ₅ -60Ag ₂ O glass powder were used.

(Example 11) the amount of tetraethoxysilane is added to the iron oxide slurry and 2.5g, the amount of iron nitride-based magnetic powder _29g of the mixed powder, was _{40P 2} O 5 -60Ag 2 O glass powder 4.8g Except for this point, an iron nitride magnet was produced in the same manner as in Example 1.

(Example 12) The amount of tetraethoxysilane added to the iron oxide slurry is 2.5 g, 35P ₂ O ₅ -65V ₂ O ₅ glass powder is used as the glass powder, and the blending amount of the mixed powder is the iron nitride magnetic powder. An iron nitride magnet was prepared in the same manner as in Example 1 except that 59 g and 2.9 g of 35P ₂ O ₅ -65V ₂ O ₅ glass powder were used.

(Example 13) The amount of tetraethoxysilane added to the iron oxide slurry was 2.5 g, and 30P ₂ O ₅ -50Ag ₂ O-20V ₂ O ₅ glass powder was used as the glass powder. The flow rate was 166 mL / min, the flow rate of phosphine gas was 34 mL / min, and the blending amount of the mixed powder was 59 g of iron nitride magnetic powder and 4.1 g of 30P ₂ O ₅ -50Ag ₂ O-20V ₂ O ₅ glass powder. Except for the above, an iron nitride magnet was manufactured in the same manner as in Example 1.

(Example 14) the amount of tetraethoxysilane is added to the iron oxide slurry and 1.8g, the amount of iron nitride-based magnetic powder _63g of the mixed powder, was _{40P 2} O 5 -60Ag 2 O glass powder 4.8g Except for this point, an iron nitride magnet was produced in the same manner as in Example 1.

  (Example 15) Implementation was performed except that the amount of tetraethoxysilane added to the iron oxide slurry was 0.8 g, the flow rate of ammonia gas during nitriding was 166 mL / min, and the flow rate of phosphine gas was 34 mL / min. An iron nitride magnet was produced in the same manner as in Example 1.

(Example 16) the amount of tetraethoxysilane is added to the iron oxide slurry and 0.6 g, the amount of iron nitride-based magnetic powder _56g of the mixed powder, was _{40P 2} O 5 -60Ag 2 O glass powder 4.8g Except for this point, an iron nitride magnet was produced in the same manner as in Example 1.

  (Comparative Example 1) Iron nitride as in Example 1 except that the amount of tetraethoxysilane added to the iron oxide slurry was 2.5 g, and 60 g of iron nitride magnetic powder was used instead of the mixed powder. A system magnet was produced.

(Comparative Example 2) The amount of tetraethoxysilane added to the iron oxide slurry was 2.5 g, and the blended amount of the mixed powder was 59 g of iron nitride-based magnetic powder and 4.2 g of 90Te ₂ O-10V ₂ O ₅ glass powder. Except for the above, an iron nitride magnet was manufactured in the same manner as in Example 1.

<Measurement of amount of P contained in iron nitride powder>
0.05 g of the obtained iron nitride magnet was weighed in a Teflon (registered trademark) beaker and dissolved by heating at 120 ° C. or higher and 150 ° C. or lower. After cooling, 1 mL of hydrogen fluoride was added, the volume was adjusted to 50 mL, and measured and calculated using an inductively coupled plasma emission spectrometer (ICP).

<Identification of iron nitride magnetic particles and low melting point glass>
The obtained iron nitride-based magnet obtained an X-ray diffraction profile by powder XRD (Rigaku RINT-2500), and identified iron nitride-based magnetic particles and low-melting glass. The obtained iron nitride-based magnet was cut out so that the cross section appeared. Using a transmission electron microscope (TEM, JEOL JEM-2100FCS), a 1.0 μm × 1.0 μm measurement region was observed at a magnification of 200,000 times, and an electron diffraction image was observed. Furthermore, element distribution mapping was performed by EDS. From the element mapping image, the part containing Fe and N was identified as iron nitride magnetic particles, and the part containing no Fe and N, containing P, and containing Ag or V was identified as low melting glass.

<Identification of P content in iron nitride magnetic particles>
The content of P in the iron nitride magnetic particles was identified by elemental mapping by EDS.

<Identification of cross-sectional area ratio and calculation of equivalent circle diameter of iron nitride magnetic particles>
By image analysis of the obtained element mapping image, cross-section observation is performed with 500 different 50 μm × 50 μm measurement regions on the cross-section of the iron nitride magnet, and the cross-sectional area ratio in each region is calculated and averaged. As a result, the cross-sectional area ratio of the iron nitride magnet was calculated. The equivalent circle diameter was calculated from the cross-sectional area of the obtained iron nitride magnetic particles and the number of iron nitride magnetic particles.

<Measurement of saturation magnetization Ms and coercive force Hc>
A BH tracer (TRE-5BH manufactured by Toei Kogyo Co., Ltd.) was used to measure the saturation magnetization Ms and the coercive force Hc of the obtained iron nitride magnet for magnetic measurement evaluation. The externally applied magnetic field was changed from 25 kOe to −25 kOe, and the saturation magnetization Ms and the coercive force Hc were obtained from the obtained demagnetization curve. In this example, an iron nitride magnet having a saturation magnetization Ms of 6.0 kG or more and a coercive force Hc of 2.0 kOe or more was considered to have good magnetic properties. Further, an iron nitride magnet having a saturation magnetization Ms of 7.0 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 a sample for measuring the bending strength 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 30 MPa or more was considered good. Moreover, the case where bending strength was 45 Mpa or more was made more favorable.

  In all the examples, the iron nitride-based magnet is composed of iron nitride-based magnetic particles and phosphate-based glass that is a low-melting glass filled between the plurality of iron nitride-based magnetic particles. It was. All of the iron nitride magnetic particles contained P. In all the examples, the magnetic properties and bending strength were all good.

  As in Examples 4, 5, 6, 9, 10, 12, 13, and 14, the ratio represented by (the cross-sectional area of the low-melting glass / the cross-sectional area of the iron nitride magnetic particles) is 0.20 or more and 0.0. When the content of P in the iron nitride magnetic particle is 2.0 at% or more and 3.0 at% or less and the equivalent circle diameter of the iron nitride magnetic particle is 30 nm or more and 150 nm or less, the magnetic properties and bending The strength was even better.

  On the other hand, in Comparative Example 1 in which the ratio represented by (cross-sectional area of the low-melting glass / cross-sectional area of the iron nitride-based magnetic particles) is 0, the bending strength and the coercive force Hc are significantly reduced.

  The reason why the coercive force Hc is remarkably lowered in Comparative Example 1 is considered that the magnetic separation effect is not enhanced because the low melting point glass is not present between the iron nitride magnetic particles. The reason why the bending strength is remarkably lowered is that a large number of voids remain in the iron nitride magnet due to the low melting point glass not being sufficiently filled between the plurality of iron nitride magnetic particles. This is probably because the particles are not firmly connected to each other.

In Comparative Example 2 in which the low melting point glass was 90Te ₂ O-10V ₂ O ₅ , the coercive force Hc and the bending strength were significantly reduced.

  The reason why the bending strength is remarkably reduced in Comparative Example 2 is that the low melting point glass does not contain P, and the elements contained in the iron nitride magnetic particles and the low melting point glass are all different elements. This is probably because the wettability with glass deteriorated. The wettability between the iron nitride-based magnetic particles and the low melting point glass is deteriorated, so that it is considered that the plurality of iron nitride-based magnetic particles cannot be firmly connected to each other, and the bending strength is lowered.

  The reason why the coercive force Hc was remarkably lowered in Comparative Example 2 was that the low melting point glass did not contain P, and the elements contained in the iron nitride magnetic particles and the low melting point glass were all different elements. This is considered to be due to insufficient expression of. In addition, the absence of P in the low melting point glass deteriorates the wettability between the iron nitride magnetic particles and the low melting point glass, and the low melting point glass between the plurality of iron nitride magnetic particles as the wettability deteriorates. Is not sufficiently filled, the magnetic separation effect is not enhanced, and it is considered that Hc is lowered.

  As described above, the iron nitride-based magnet according to the present invention has high magnetic properties (particularly saturation magnetization and coercive force) and high mechanical strength (particularly bending strength). It is.

1 Iron nitride magnet 2 Iron nitride magnetic particles 3 Low melting point glass

Claims (5)

An iron nitride magnet composed of iron nitride magnetic particles and low melting point glass,
An iron nitride magnet in which the low melting glass contains at least one element contained in the iron nitride magnetic particles. The ratio represented by (the cross-sectional area of the low-melting glass / the cross-sectional area of the iron nitride magnetic particles) is 0.10 or more and 0.40 or less,
The iron nitride-based magnetic particles contain P at 1.0 at% to 4.0 at%,
The low melting point glass is made of phosphate glass,
The phosphate type _glass, P ₂ O 5 -Ag ₂ O _{glass, P 2 O 5 -V 2 O} 5 glass, or, according to claim _1, consisting of _{P 2 O 5 -Ag 2 O-} V 2 O 5 glass The iron nitride magnet described in 1.   The iron nitride-based magnet according to claim 2, wherein a ratio represented by (the cross-sectional area of the low-melting glass / the cross-sectional area of the iron nitride-based magnetic particles) is 0.20 or more and 0.30 or less.   The iron nitride-based magnet according to claim 2 or 3, wherein the iron nitride-based magnetic particles contain P at 2.1 at% or more and 3.0 at% or less.   The iron nitride magnet according to any one of claims 2 to 4, wherein an average equivalent circle diameter of the iron nitride magnetic particles is 30 nm to 150 nm.

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