JP7044304B2 - Rare earth transition metal alloy powder manufacturing method - Google Patents

Description

The present invention relates to a method for producing a rare earth transition metal alloy powder, and more particularly to a method for producing a rare earth transition metal alloy powder capable of suppressing oxidative deterioration of the alloy surface during wet treatment.

The rare earth transition metal alloy powder is used as a raw material powder for rare earth magnets, hydrogen storage alloys, magnetic strain alloys, photomagnetic recording alloys, magnetic refrigeration materials, and the like.
The reduction diffusion method is known as a method for producing a rare earth transition metal alloy powder, and water washing or acid washing is used to disintegrate the massive reaction product obtained by reduction diffusion and remove excess reducing agent. It is done. In this method, a rare earth oxide powder and a transition metal powder are mixed with at least one reducing agent selected from alkali metals, alkaline earth metals and hydrides thereof, and the mixture is heated in an inert gas atmosphere. After reduction and diffusion, the obtained massive reaction product is put into water to disintegrate it, and the obtained slurry is wet-treated by washing with hydrochloric acid or acetic acid and washing with water to remove the by-produced reducing agent component. ..

For example, in the method of producing a rare earth-transition metal-nitrogen magnet coarse powder by the reduction diffusion method and then finely pulverizing it with phosphoric acid in a pulverizer, the reaction product after reduction diffusion occludes hydrogen and disintegrates the roasted product into pure water. It is poured into the water, stirring and decantation are repeated until the hydrogen ion concentration pH becomes 10 or less, acetic acid is added to water until the pH becomes 5, and stirring is performed in this state (see Patent Document 1). ).

In addition, water and acid are also used in the method for producing rare earth-iron-nitrogen magnet fine powder, in which a rare earth iron alloy by reduction diffusion is cooled and then subjected to nitriding heat treatment, and the obtained nitriding reaction product is put into water for wet treatment. By the wet treatment, impurities such as CaO are washed and removed from the nitriding reaction product (see Patent Document 2). In these methods, by performing a wet treatment, excess reducing agent is effectively removed from the reduction reaction product, and a powder having excellent magnetic properties is obtained.

However, in general, when a lumpy reaction product is put into water and disintegrated by wet treatment, oxides and hydroxides are generated on the surface of the alloy powder, and the oxygen concentration of the alloy powder is increased. Further, in pickling using hydrochloric acid or acetic acid together with water, if the stirring of the slurry is insufficient during washing, a high concentration of acid may locally corrode the surface of the alloy.

Japanese Unexamined Patent Publication No. 2017-011276 Japanese Unexamined Patent Publication No. 2017-147434

In view of the above-mentioned problems of the prior art, an object of the present invention is to suppress oxidative deterioration of the alloy surface during wet treatment in a rare earth transition metal alloy powder directly produced by a reduction diffusion method. The purpose is to provide a method for producing a powder.

As a result of diligent studies on the relationship between the oxygen content of the rare earth transition metal alloy powder and the treatment conditions in the wet treatment process, the present inventors have found that the phenomenon that the oxygen content of the alloy produced by the reduction diffusion method increases is We have investigated that it is induced by water washing, which has been generally performed conventionally, and found that the amount of oxygen in the alloy can be significantly reduced by using glycol as a cleaning agent in the wet treatment step, and completed the present invention. I let you.

That is, according to the first aspect of the present invention, an alkali metal, an alkaline earth metal, and at least one reducing agent selected from these hydrides are added to the raw material containing the rare earth oxide powder and the transition metal powder. A first step of mixing at a predetermined ratio, a second step of heating the mixture in an inert gas atmosphere to reduce and diffuse it, and a wet treatment of putting the obtained reaction product into a washing liquid to disintegrate it. After reducing the reducing agent from the reaction product, the rare earth transition metal comprises a third step of adding an acid and a cleaning liquid to the alloy slurry of the cleaning liquid for acid cleaning, and then adding the cleaning liquid to remove the acid. A method for producing an alloy powder, wherein the cleaning liquid is a glycol having a water content of 0 to 50% by mass defined by water / (glycol + water). Provided.

Further, according to the second aspect of the present invention, in the first aspect, the rare earth oxide powder is derived from Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, and Yb. Provided is a method for producing a rare earth transition metal alloy powder, which comprises one or more selected rare earth elements.

Further, according to the third aspect of the present invention, in the first or second aspect, the transition metal powder contains one or more transition elements selected from Fe, Co, Ni, Cu, Cr, and Mn. Provided is a method for producing a rare earth transition metal alloy powder, which is characterized by the above.

Further, according to the fourth aspect of the present invention, in any one of the first to third aspects, the cleaning liquid is selected from ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol. Provided is a method for producing a rare earth transition metal alloy powder, which is characterized by being one or more kinds of alkylene glycol.

Further, according to the fifth aspect of the present invention, in any one of the first to the fourth aspects, the acid is one or more selected from hydrochloric acid, acetic acid, nitric acid, and sulfuric acid. A method for producing a metal alloy powder is provided.

Further, according to the sixth aspect of the present invention, in any one of the first to fifth aspects, the rare earth transition metal alloy powder obtained in the third step is further heated in an atmosphere containing nitrogen and / or ammonia. A method for producing a rare earth transition metal alloy powder, which is characterized by being nitrided, is provided.

Further, according to the seventh aspect of the present invention, an alkali metal, an alkaline earth metal, and at least one reducing agent selected from these hydrides are added to the raw material containing the rare earth oxide powder and the transition metal powder. The first step of mixing at a predetermined ratio, the second step of heating the mixture in an inert gas atmosphere to reduce and diffuse it, and heating the obtained reaction product in a nitrogen and / or ammonia-containing atmosphere to nitrid. In the fourth step of After that, it is a method for producing a rare earth transition metal alloy powder, which comprises a fifth step of adding a cleaning liquid to remove acid, and the cleaning liquid has a water content of 0 to 50 defined by water / (glycol + water). Provided is a method for producing a rare earth transition metal alloy powder, which is characterized by being glycol by mass.

Further, according to the eighth aspect of the present invention, for the rare earth transition metal alloy powder containing Sm and Fe, the rare earth oxide powder containing Sm and the transition metal oxide powder containing Mn and / or Cr are provided. An alkali metal, an alkaline earth metal, and at least one reducing agent selected from these hydrides are mixed at a predetermined ratio, and this mixture is heated in an inert gas atmosphere to reduce and diffuse the mixture, and then the obtained reduction is performed. The diffusion reaction product is heated and nitrided in an atmosphere containing nitrogen and / or ammonia, and subsequently, the obtained nitride reaction product is put into a washing liquid to perform a wet treatment to disintegrate it, and a reducing agent is obtained from the nitride reaction product. A method for producing a rare earth transition metal alloy powder, which comprises a step of reducing the amount of water, wherein the cleaning liquid is glycol having a water content of 0 to 50% by mass defined by water / (glycol + water). A method for producing a rare earth transition metal alloy powder is provided.

According to the aspect of the present invention, in the production of the rare earth transition metal alloy powder, glycol is used as a cleaning agent when the reduction diffusion product or the nitriding reaction product thereof is wet-treated, so that the rare earth transition metal alloy powder after the treatment can be used. The amount of oxygen contained can be significantly reduced, the dissolution reaction to the alloy powder can be alleviated by acid washing, and the yield can be improved. Further, since the amount of oxygen contained in the obtained rare earth transition metal alloy powder is significantly reduced, the magnetic properties and the PCT (pressure one composition first temperature ray) property, which is the hydrogen storage performance, are improved.

Hereinafter, the method for producing the rare earth transition metal alloy powder of the present embodiment will be described in detail. The production of rare earth transition metal alloy powder has at least a raw material mixing step, a reduction diffusion step, and a wet treatment step, and in the case of Sm ₂ Fe ₁₇ alloy powder, it is manufactured by the method of the present invention further including a nitride heat treatment step. ..

≪Rare earth transition metal alloy powder≫
The rare earth transition metal alloy powder intended by the production method of the present invention is an alloy powder containing the rare earth element R and the transition metal TM as main constituents, and is CaCu ₅ type, Th ₂ Zn ₁₇ type, Th ₂ Ni ₁₇ type. , TbCu ₇ type, ThMn ₁₂ type, NaZn ₁₃ type, Nd ₂ Fe ₁₄ B type, MgCu ₂ type and other alloy powders containing intermetallic compounds having a crystalline structure. The rare earth transition metal alloy powder is not limited by the average particle size and the particle size distribution, but preferably has an average particle size of 1 to 100 μm.

Specifically, Sm ₂ Fe ₁₇ alloy powder, Nd ₂ Fe ₁₄ B alloy powder, Sm Co ₅ alloy powder, LaNi ₅ alloy powder, Sm ₂ Co ₁₇ alloy powder, Sm (Fe, Ti) ₁₂ alloy powder, La ( Fe, Si) ₁₃ alloy powder, TbFe ₂ alloy powder, DyFe ₂ alloy powder, Sm ₂ Fe ₁₇ N ₃ alloy powder, alloy powder in which these rare earth elements and transition metal elements are replaced with other elements, for example, Sm ₂ Fe ₁₇ Examples thereof include magnetic powder having an N ₃ alloy as a core and Sm ₂ (Fe, M) ₁₇ N _x (M = Cr, Mn) as a shell layer.

Of these, the Sm ₂ Fe ₁₇ alloy powder has Sm of 23 to 25% by mass, O of 0.1% by mass or less, Ca of 0.01% by mass or less, the balance of iron, and the main phase is Th ₂ Zn ₁₇ type. It is a Sm ₂ Fe ₁₇ alloy powder of rhombic crystal, and has an average particle size of 10 to 40 μm.

The Nd ₂ Fe ₁₄ B alloy powder is mainly composed of 32 to 35% by mass of Nd, 1 to 3% by mass of B, 0.1% by mass or less of O, 0.1% by mass or less of Ca, and the balance is iron. The crystal structure of the phase is Nd ₂ Fe ₁₄ B type square crystal, and the average particle size is 5 to 50 μm.

The SmCo ₅ alloy powder has Sm of 32 to 38% by mass, O of 0.1% by mass or less, Ca of 0.1% by mass or less, the balance of cobalt, and the crystal structure of the main phase is CaCu ₅ type hexagonal crystal. The average particle size is 5 to 50 μm. Although the Sm composition and crystal structure are different, the same applies to the Sm ₂ Co ₁₇ -based alloy powder.

The LaNi ₅ alloy powder has La of 31 to 37% by mass, O of 0.1% by mass or less, Ca of 0.1% by mass or less, the balance of nickel, and the crystal structure of the main phase is CaCu ₅ type hexagonal crystal. Things are illustrated. The average particle size is 10 to 50 μm.

In the Sm ₂ Fe ₁₇ N ₃ alloy powder, Sm is 23 to 24% by mass, N is 3 to 5% by mass, O is 0.8% by mass or less depending on the average particle size, Ca is 0.5% by mass or less, and the balance. Is iron, and the main phase is Th ₂ Zn ₁₇ type rhombic body crystal Sm ₂ Fe ₁₇ N ₃ alloy powder. It is preferable that the average particle size is 1 to 40 μm and the peak of the particle size distribution is 1 to 5 μm.

Further, the magnetic powder having Sm ₂ Fe ₁₇ N ₃ alloy as a core and Sm ₂ (Fe, M) ₁₇ N _x (M = Mn, Cr) as a shell layer has an overall average composition of 23 Sm. ~ 29% by mass, Mn or Cr is 1 to 3% by mass, N is 3 to 5% by mass, O is 0.8% by mass or less depending on the average particle size, Ca is 0.5% by mass or less, and the balance is iron. The average particle size is 1 to 20 μm. When N exceeds 4% by mass, the shell layer contains a metal structure composed of cellular fine crystal grains and an amorphous boundary layer, and the inside of the Sm ₂ (Fe, M) ₁₇ N _y compound crystal phase. A metal structure in which a wire-like amorphous phase having a high concentration of Mn or Cr and N and having a long and short shape is randomly or regularly present is observed.

The oxygen content of the rare earth transition metal alloy powder is 0.8% by mass or less, preferably 0.1% by mass or less, and more preferably 0.08% by mass or less. The amount of oxygen depends on the average particle size and particle size distribution of the alloy powder, but as a cleaning agent for wet treatment, it is compared with the conventional wet treatment in which the reduction diffusion reaction product and the nitrided reaction product are washed with water alone. , 30-70% by mass.

≪Manufacturing method of rare earth transition metal alloy powder≫
In the present embodiment, the raw material and the reducing agent are mixed, and the reduction diffusion product obtained by reduction diffusion is wet-treated with glycol having a water content of 0 to 50% by mass to produce a rare earth transition metal alloy powder. In order to convert the rare earth transition metal alloy powder into a magnet alloy powder, further nitriding heat treatment may be performed. Hereinafter, each step of the raw material mixing step, the reduction diffusion step, the wet treatment step, and the nitriding heat treatment step will be described. The nitriding heat treatment can also be performed before the wet treatment.

That is, in the method for producing a rare earth transition metal alloy powder of the present embodiment, at least one reduction selected from an alkali metal, an alkaline earth metal, and a hydride thereof is used as a raw material containing a rare earth oxide powder and a transition metal powder. A first step of mixing the agents at a predetermined ratio, a second step of heating the mixture in an inert gas atmosphere to reduce and diffuse it, and a wet method in which the obtained reaction product is put into a washing liquid to disintegrate it. Rare earths including a third step of performing a treatment to reduce the reducing agent from the reaction product, then performing acid cleaning by adding an acid and a cleaning liquid to the alloy slurry of the cleaning liquid, and then adding the cleaning liquid to remove the acid. It is a method for producing a transition metal alloy powder, and is characterized by using glycol having a water content of 0 to 50% by mass defined by water / (glycol + water) as a cleaning liquid.

(Raw material)
First, rare earth oxide powder and transition metal powder are prepared as raw material. The rare earth oxide powder is an oxide containing one or more rare earth elements selected from Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, and Yb. Among them, those containing Sm, Nd, or La are particularly preferable because they exert the effect of the present embodiment remarkably, and when applied to a bonded magnet, 50 atomic% or more thereof is Sm, and high frequency magnetism. When applied to materials, it is desirable that 50 atomic% or more of them is Nd.

The average particle size of the rare earth oxide powder is preferably 50 μm or less, preferably 20 μm or less, more preferably 10 μm or less, and the rare earth oxide particles are uniform in the vicinity of the transition metal particles depending on the final alloy composition. It is better to determine the average particle size so that it is present in. Further, the rare earth oxide powder contains water, organic substances and the like as impurities, and these impurities increase the amount of oxygen in the obtained rare earth transition metal alloy powder. The amount of this impurity can be evaluated by the mass loss before and after heating when heated to 1000 ° C. and then cooled. In the present embodiment, the mass loss is 2% or less, preferably 1% or less. Oxide powder is preferred.

On the other hand, the transition metal powder is a metal or a metal compound containing one or more transition elements selected from Fe, Co, Ni, Cu, Cr, and Mn. As the iron powder which is a typical transition metal, for example, reduced iron powder, gas atomizing powder, water atomizing powder, electrolytic iron powder and the like can be used, and the powder is classified so as to have an optimum particle size as needed.

The average particle size of the transition metal powder is 100 μm or less, preferably 80 μm or less, more preferably 60 μm or less, and particularly preferably 50 μm or less. When the average particle size exceeds 100 μm, the rare earth component reduced by the reducing agent does not diffuse to the inside of the transition metal particles, and the undiffused portion remains as a core. However, this does not apply if there is no problem in the residual undiffused portion due to the post-process of the obtained alloy powder. If there is a target average particle size of the alloy powder, it is advisable to use a transition metal powder that is 1/2 to 1 times the target average particle size. Since the reduction diffusion reaction is a thermite reaction, 20% by mass or less of the transition metal powder can be used in the form of an oxide powder for the purpose of utilizing the exothermic reaction for raising the temperature.

Further, instead of or as a part of the transition metal powder, an alloy powder of a rare earth and a transition metal or a composite oxide powder thereof can also be used. However, when using composite oxide powder, the amount of composite oxide powder should be suppressed to 20% by mass or less of the transition metal powder so that thermite heat generation does not become excessive, or it should be reduced once with hydrogen gas or the like and then used as a raw material. good. These average particle sizes are based on the average particle sizes of transition metal powders or rare earth oxide powders. Further, the additive element such as B constituting the NdFeB alloy powder can be used as a single powder, but may be used in the form of FeB alloy powder. In that case, the average particle size is selected in the same range as the particle size of the transition metal powder.

(1) Mixing of raw materials The rare earth oxide powder and transition metal powder of the raw materials are prepared in a predetermined amount in the container of the mixer so as to have the composition of the target alloy powder, and in an inert gas atmosphere so as not to be unevenly distributed. Stir and mix well with. Since the reduction diffusion method is reflected in the alloy composition in which the local mixed composition is obtained, it is necessary that rare earth oxide particles and other additive elements reflecting the alloy composition are present around each transition metal particle.

The mixer used in this process includes a dry type and a wet type. The dry type mixers include V blender, locking mixer, S blender, Henshell mixer, Compix, mechano hybrid, mechanofusion, nobilta, and high. A hybridization system, a mirroro, a tumbler mixer, a theta composer, a spartan mixer, etc. are used. The raw material should be mixed in an atmosphere of an inert gas such as nitrogen gas or argon gas to avoid oxidation. On the other hand, as the wet mixer, a bead mill, a ball mill, a nanomizer, a wet cyclone, a homogenizer, a dissolver, a fill mix and the like are used. In the case of a wet mixer, it is necessary to sufficiently dry an organic solvent such as water or alcohol, or a mixed solvent of both, in order to prevent an increase in the amount of oxygen in the finally obtained alloy powder. In this case as well, it is preferable to dry the mixture so that the mass loss is 2% or less, preferably 1% or less, and more preferably 0.5% or less, as in the case of the rare earth oxide powder.

(2) Reduction and Diffusion Treatment This step is a step of reducing the rare earth oxide to a rare earth element and synthesizing a rare earth transition metal alloy in which the rare earth element is diffused into a transition metal such as iron powder.

In the reduction diffusion treatment, at least one selected from alkali metals, alkaline earth metals and hydrides thereof is used as the reducing agent for the rare earth oxide powder. Specifically, Li, Na, K, Mg, Ca, Sr or Ba metal, or hydride is used. When the raw material contains an oxide powder of a transition metal, they also act as a reducing agent. The reducing agent is supplied in the form of granules or powder, and it is desirable to use a reducing agent having an average particle size of 10 mm or less, preferably 0.1 to 7 mm, and more preferably 0.2 to 5 mm. Of these, Ca is particularly useful, so Ca will be described below as an example.

When the amount of Ca as a reducing agent is contained in a rare earth oxide powder or a transition metal oxide powder, it is desirable that the amount of Ca be 1.1 to 5 times the amount required for reduction of the oxide powder. If Ca is less than 1.1 times, diffusion does not proceed easily after the oxide is reduced, and if it exceeds 5 times, the residue caused by Ca increases and it takes time to remove it, which is not preferable. Further, it is preferable to use Ca having a purity of 95% by mass or more. If it is less than 95% by mass, the diffusion reaction after reduction is difficult to proceed.

It is important that the raw material and Ca particles are placed in a mixer and mixed uniformly. As the mixer, a V blender, an S blender, a ribbon mixer, a ball mill, a Henschel mixer, a mechanofusion, a novirta, a hybridization system, a mirrorro and the like can be used.

The mixture is loaded into a crucible, placed in a reaction vessel and installed in an electric furnace. From mixing to installation in an electric furnace, it is preferable to avoid contact with air and water vapor as much as possible. Further, in order to remove the air and water remaining in the mixture, it is preferable to evacuate the inside of the reaction vessel and replace it with an inert gas such as He or Ar.

In the reduction diffusion treatment, the temperature of these inert gases is raised while flowing in the container, and the rare earth elements adjusted at a predetermined temperature are held for a sufficient time to diffuse into the transition metal particles. The holding temperature is equal to or lower than the melting point of the target rare earth transition metal alloy phase and is equal to or higher than the melting point of the reducing agent, alkali metal or alkaline earth metal. However, if the reducing agent has a high vapor pressure, the rare earth oxide powder can be reduced by the vapor of the reducing agent at the melting point or lower. For example, in the case of producing Sm ₂ Fe ₁₇ alloy powder from raw materials such as samarium oxide and iron powder, when the reducing agent is metallic Ca, it is usually from 800 ° C. near the melting point of metallic Ca to Sm ₂ Fe ₁₇ intermetallic compound. The holding temperature is set in the range of the peritectic temperature of 1280 ° C.
Here, if Ca steam is used, the holding temperature can be set lower than 600 ° C. The holding time is set to a sufficient time for the reduced rare earth element to diffuse into the inside of the particles at the holding temperature in consideration of the particle size of the transition metal powder which is the raw material. For the production of Sm ₂ Fe ₁₇ alloy powder, it is preferable to keep it in the above temperature range for 1 to 8 hours. When producing Nd ₂ Fe ₁₄ B alloy powder, Sm ₂ Co ₁₇ alloy powder, or LaNi ₅ alloy powder, the temperature may be maintained in the range of 900 to 1100 ° C. for 1 to 5 hours. After holding for a predetermined time, cool to room temperature while maintaining the inert gas atmosphere.

After cooling, the reaction products recovered from the pot are the target rare earth transition metal alloy powder, by-produced alkali metal or alkaline earth metal oxide particles, and the alkali metal or alkaline soil remaining after being excessively charged. It is a composite composed of similar metal components.

Before proceeding to the next step, hydrogen gas, a gas containing nitrogen such as nitrogen or ammonia, CO gas, a hydrocarbon gas, etc. are supplied to the obtained reaction product, and heat treatment is performed in this gas atmosphere. The rare earth transition metal alloy particles in the reaction product can also be hydrogenated, nitrided and carbonized. When the rare earth transition metal alloy particles are hydrogenated, the reaction product obtained in the form of agglomerates easily occludes hydrogen and disintegrates. Regarding nitriding using a gas containing nitrogen, the section will be described in detail again.

(3) Wet Treatment In the wet treatment, in the wet treatment, the reaction product obtained in the reduction / diffusion treatment step is glycol or a glycol solution having a water content of 50% by mass or less, that is, a water content of 0 to 50% by mass. This is an operation in which impurities are washed by adding to% glycol, stirring and forming an alloy slurry.

When the reducing agent is Ca, the reaction product obtained by the reduction diffusion treatment is a porous sintered body consisting of a rare earth transition metal alloy, CaO, and excess Ca, so CaO, Ca, and different phases must be removed. Must be. In this wet treatment step, the porous sintered body is put into the first cleaning agent to form a slurry, the cleaning is performed by removing the reducing agent with the first cleaning agent, and the acid is added to the second cleaning agent. This includes an acid cleaning that further reduces the residual reducing agent, and an operation of adding a third cleaning liquid to the alloy slurry in which the reducing agent is reduced to remove the acid. The first cleaning agent, the second cleaning agent, and the third cleaning agent may be the same or different.

As the glycol, one or more alkylene glycols selected from ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol and tripropylene glycol can be used. It is preferable to use these glycols and their mixtures as they are. However, since alkylene glycol has a high viscosity, it may be difficult to separate the rare earth transition metal powder and the reducing agent component after slurry formation to remove the reducing agent component.
Therefore, it can be diluted with water and used as a glycol solution. However, the water content of glycol should be 50% by mass or less. Here, the water content is a percentage of the mass ratio of water / (glycol + water). If the amount of water exceeds 50% by mass, the oxidation of rare earth transition metal particles becomes remarkable, which is not preferable. A glycol solution having a preferable water content of 30% by mass or less, more preferably 10% by mass or less, and particularly preferably 5% by mass or less is preferable.

In this step, first, the reaction product obtained in the reduction / diffusion treatment step is put into a glycol solution as a first detergent or a glycol solution having a water content of 50% by mass or less to form a slurry. At this time, the form of the reaction product is arbitrary, but in the case of a lump, the reaction proceeds rapidly if it is mechanically crushed in advance and then charged. If the reaction product exhibits hydrogen embrittlement, it may be crushed by creating a hydrogen atmosphere and heat-treating at a temperature suitable for absorbing hydrogen instead of mechanical crushing. Further, if the slurry is treated while stirring, the reaction tends to proceed, so that the treatment time can be shortened. The treatment time depends on the type of the rare earth transition metal alloy, but the initial treatment time is in the range of 2 to 15 hours, preferably 6 to 12 hours.

The amount of glycol to be added as the first cleaning agent is not particularly limited, but it is possible to use 2 to 10 times as much glycol as the equivalent amount of the reducing agent component in the reaction product reacting with glycol at one time. can. It is preferable to use 3 to 8 times as much glycol as the mass of the reaction product.

Here, the reaction mechanism will be described in the case where metallic calcium is used as a reducing agent and ethylene glycol (HOC ₂ H ₄ OH) is used as the glycol in the production of the Sm ₂ Fe ₁₇ alloy powder. The calcium oxide CaO remaining in the reaction product proceeds to form a slurry by the reaction of the formula (1) with ethylene glycol, and when metallic Ca remains in the reaction product, ethylene glycol is used. And the reaction of the formula (2) progresses, and the slurry formation proceeds.

CaO + HOC ₂ H ₄ OH → CaC ₂ H ₄ O ₂ + H ₂ O ... (1)
Ca + 4HOC ₂ H ₄ OH → Ca (OC ₂ H ₄ OH) 2.2 HOC ₂ H ₄ OH + H ₂ (gas) ... ( ₂ )

When the reaction product thus slurried is allowed to stand, the rare earth transition metal alloy powder having a large specific gravity is settled, so that the supernatant containing the reducing agent component is removed by decantation. Glycol, which is the first detergent, or a glycol solution having a water content of 50% by mass or less is added thereto again, and stirring-standing-decantation is repeated 2 to 8 times. The number of repetitions depends on the residual amount of the reducing agent, but is preferably 5 times or less. This operation removes the reducing agent component as much as possible. Further, the second and subsequent stirring-standing-decantation may be performed in a shorter time than the first time, preferably 3 to 15 minutes, and preferably 5 to 10 minutes.

Next, an acid is added to the alloy slurry after the cleaning, acid cleaning is performed to dissolve and remove the reducing agent component remaining in the cleaning, and then a cleaning liquid is added to the alloy having a reduced reducing agent to remove the acid from the alloy slurry. Perform the removal operation. When a rare earth-rich subphase is formed in the alloy powder from the target rare earth transition metal alloy phase, the rare earth-rich phase can also be dissolved and removed by this acid cleaning, if necessary.

As the acid, an inorganic acid such as hydrochloric acid, nitric acid or sulfuric acid or an organic acid such as acetic acid can be used, but hydrochloric acid or acetic acid is preferable from the viewpoint of cost and the like. Prior to use, it is preferably diluted with glycol containing a second cleaning agent or water. This is because when only water is used as a medium in pickling as in the conventional case, the added acid is rapidly ionized in water, and as a result, a strong dissolution reaction occurs in the powder. In the present embodiment, a glycol solution having a water content of 50% by mass or less, which is defined by the percentage of water / (glycol + water), is used for pickling. If the amount of water exceeds 50% by mass, the acid concentration of the rare earth transition metal particles decreases and the pickling effect decreases, which is not preferable. A glycol solution having a preferable water content of 30% by mass or less, more preferably 10% by mass or less, and particularly preferably 5% by mass or less is preferable.

The amount of acid used is determined by the amount of rare earth elements and the amount of reduction diffusion products. The acid diluted with the glycol solution is preferably added dropwise to the alloy powder little by little and maintained at pH 3 to 6 for 3 to 20 minutes. Even if a reducing agent that is difficult to remove remains in the alloy and a phase richer in rare earth than the target composition is contained in the alloy powder, if the reducing agent or rare earth is treated by adding hydrochloric acid or acetic acid while stirring the slurry. The rich phase can be dissolved and removed. The temperature of the second cleaning liquid is not particularly limited. However, since the solubility of the reducing agent component in the glycol decreases as the temperature of the cleaning solution rises, the temperature of the cleaning solution is set to 50 ° C. or lower, preferably 40 ° C. or lower, more preferably 30 ° C. or lower in the entire wet treatment step.

After acid cleaning, a glycol solution having a water content of 50% by mass or less is added again as a third cleaning solution so that the acid does not remain in the alloy slurry, and stirring, standing, and decantation are repeated to remove the acid. It is preferable to do so.
The rare earth transition metal alloy powder slurry that has been washed in this way can finally be filtered and dried to obtain the desired alloy powder. When the glycol is highly viscous and difficult to dry, alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol and ketones such as acetone can be used to easily replace the glycol and dry the glycol efficiently. Alcohols such as ethyl alcohol and isopropyl alcohol are preferred. The drying conditions may be in the range of 1 to 8 hours at 100 to 200 ° C. under reduced pressure, although it depends on the type of glycol, alcohol and diluent contained.

Through the series of steps described above, a rare earth transition metal alloy powder having a reduced oxygen content is produced. The amount of oxygen in the rare earth transition metal alloy powder depends on the average particle size and particle size distribution, but can be reduced to 30 to 70% by mass as compared with the case where the same reaction product is washed with water alone.

Among the rare earth transition metal alloy powders, the LaNi ₅ alloy powder can be used as a hydrogen storage alloy by forming it into a desired shape and then heating it to a high temperature for sintering. Since the amount of oxygen is reduced, the activity of the surface is not reduced, and the powder is used for hydrogen storage alloys in which adverse effects on PCT characteristics are avoided.

Further, the SmCo ₅ alloy powder, the Sm ₂ Co ₁₇ alloy powder, and the Nd ₂ Fe ₁₄ B alloy powder are formed into a desired shape, and then a rare earth-rich alloy powder or Co is added as a sintering aid to obtain a high temperature. It can be used as a sintered magnet by heating to and sintering. As the amount of oxygen is reduced, the sintering density is increased, and the powder for sintered magnets has improved magnetic properties. However, among the rare earth transition metal alloy powders, the Sm ₂ Fe ₁₇ alloy powder does not exhibit its function as it is, so it is heated in an atmosphere containing nitrogen and / or ammonia and nitrided to obtain the Sm ₂ Fe ₁₇ N ₃ alloy powder. The conditions for the nitriding heat treatment are as described in detail in the next section.
On the other hand, Ho ₂ Co ₁₇ alloy powder, Sm (Fe, Ti) ₁₂ alloy powder, La (Fe, Si) ₁₃ alloy powder, La (Fe, Si) 13H _X alloy powder, TbFe ₂ alloy powder, _{DyFe 2} alloy powder. Some of them are used for magnetic strain alloys, photomagnetic recording alloys, magnetic refrigeration materials, and the like.

(4) Nitriding heat treatment In the above method, it has been described that the reaction product subjected to the reduction / diffusion treatment is subjected to a wet treatment, but the reaction product can also be subjected to a nitriding heat treatment before the wet treatment.

That is, in this method for producing a rare earth transition metal alloy powder, an alkali metal, an alkaline earth metal, and at least one reducing agent selected from these hydrides are added to the raw material containing the rare earth oxide powder and the transition metal powder. The first step of mixing at a predetermined ratio, the second step of heating the mixture in an inert gas atmosphere to reduce and diffuse it, and heating the obtained reaction product in a nitrogen and / or ammonia-containing atmosphere for nitriding. The fourth step is to perform a wet treatment in which the obtained nitriding reaction product is put into a cleaning liquid to cause disintegration, the reducing agent is reduced from the nitriding reaction product, and then an acid is added to the nitriding alloy slurry. After that, it is a method for producing a rare earth transition metal alloy powder, which comprises a fifth step of adding a cleaning liquid to remove acid, and the cleaning liquid has a water content of 0 to 50 defined by water / (glycol + water). It is characterized by being a mass% glycol.

In this nitriding heat treatment, the obtained reaction product is heated in an atmosphere containing nitrogen and / or ammonia to obtain a nitriding reaction product. Examples of the nitrogen and / or ammonia-containing atmosphere include a nitrogen gas atmosphere, a mixed atmosphere of nitrogen gas and hydrogen gas, an ammonia gas atmosphere, a mixed atmosphere of ammonia gas and hydrogen gas, a mixed gas atmosphere of ammonia gas and nitrogen gas, and an ammonia gas. And the atmosphere of a mixed gas of nitrogen gas and hydrogen gas. When a mixed atmosphere of ammonia gas and hydrogen gas is used, the flow rate ratio is preferably 1: 1 to 3.
It is preferable to use an atmosphere containing nitrogen gas and / or a mixed atmosphere of ammonia gas and hydrogen gas, and a sufficient amount of argon gas is supplied even after nitriding to produce a reaction product in a temperature range of 300 to 500 ° C. Is to heat. If the heating temperature is less than 300 ° C, nitriding does not proceed, while if it exceeds 500 ° C, the alloy decomposes into the nitriding reaction product of the rare earth element and iron, which is not preferable. More preferably, it is 300 to 450 ° C.
The treatment time is related to the heating temperature, the flow rate of each gas, the size of the reaction product, etc., but in the case of a mixed atmosphere of ammonia gas and hydrogen gas, for example, 100 minutes to 10 hours is preferable, and 2 to 8 hours is preferable. More preferred.

In this way, the nitriding heat treatment is performed and then the wet treatment is performed. The wet treatment method and treatment conditions for the nitriding reaction product are the same as those for the wet treatment for the reduction diffusion product. That is, it is an operation of putting the nitriding reaction product obtained in the nitriding step into the first cleaning agent, stirring the mixture to form a slurry, and cleaning. Normally, a second cleaning agent and an acid are added to the alloy slurry after cleaning, the reducing agent is dissolved from the alloy, and then a third cleaning liquid is added to the alloy in which the reducing agent is reduced to remove the acid. .. The present embodiment is characterized in that glycol having a water content of 0 to 50% by mass is used as a cleaning agent. The first cleaning agent, the second cleaning agent, and the third cleaning agent may be the same or different.

As the glycol, one or more alkylene glycols selected from ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol and tripropylene glycol can be used. It is preferable to use these glycols and their mixtures as they are. However, if it is difficult to separate and remove the rare earth transition metal powder and the reducing agent component after slurrying due to its high viscosity, it can be diluted with water before use. When diluting glycol, the water content should be 50% by mass or less. If the amount of water exceeds 50% by mass, the oxidation of rare earth transition metal particles becomes remarkable, which is not preferable.

The amount of glycol used is not particularly limited, but 2 to 10 times as much glycol as the equivalent amount at which the reducing agent component in the nitriding reaction product reacts with glycol can be used. It is preferable to use 3 to 8 times as much glycol as the mass of the nitriding reaction product.

Thereby, Sm ₂ Fe ₁₇ N ₃ magnet alloy powder can be obtained. The physical characteristics of the magnet powder can be evaluated by using the resin composition as a binder and measuring the magnetic properties of the molded bonded magnet. It was confirmed that the Coercive force (MA / m) of the Sm ₂ Fe ₁₇ N ₃ alloy powder was improved by 5% or more and the squareness was improved by 10% or more as compared with the case of washing with water alone by the conventional method. There is.

The rare earth transition metal alloy powder can be further subjected to a wet surface treatment to form, for example, a phosphate-based compound film to enhance oxidation resistance and weather resistance. Further, in addition to Cr and Mn, a metal layer such as Zn, Cu and Ni can be formed on the powder surface by a plating treatment or the like.

(Formation of shell layer on Sm ₂ Fe ₁₇ N ₃ alloy)
Next, a method for producing an alloy powder having Sm ₂ Fe ₁₇ N ₃ alloy as a core and Sm ₂ (Fe, M) ₁₇ N _x (M = Cr, Mn) as a shell layer will be described according to the present embodiment.

In order to produce an alloy powder in which a shell layer is formed on a Sm ₂ Fe ₁₇ N ₃ alloy, a rare earth oxide powder containing Sm and Mn and / or Cr are used as opposed to a rare earth transition metal alloy powder containing Sm and Fe. The transition metal oxide powder containing the above is mixed with an alkali metal, an alkaline earth metal, and at least one reducing agent selected from these hydrides at a predetermined ratio, and the mixture is heated in an inert gas atmosphere. After reduction and diffusion, the obtained reduction and diffusion reaction product is heated in a nitrogen and / or ammonia-containing atmosphere to be nitrided, and then the obtained nitride reaction product is put into a washing liquid to cause disintegration. The step of reducing the reducing agent from the nitrided reaction product is included. Then, as the cleaning liquid, glycol having a water content of 0 to 50% by mass defined by water / (glycol + water) is used.

The Sm ₂ Fe ₁₇ alloy powder, which is a rare earth transition metal alloy powder, is not limited by the production method. For example, a reducing agent is mixed with Sm ₂ O3 powder _, which is a rare earth oxide powder, and iron powder, which is a transition metal oxide powder, and reduced and diffused in the same manner as in (1) to (3) above to generate a reduction and diffusion reaction. It can be obtained by putting a substance into glycol and performing a wet treatment to remove the reducing agent. This is a Mn oxide powder such as Sm ₂ O ₃ powder, which is a rare earth oxide powder having an average particle size of 5 μm or less, and Mn ₃ O ₄ , which is a transition metal oxide powder having an average particle size of 3 μm or less, or Cr ₂ O. It is preferable to mix with a Cr oxide powder such as ₃ and finely grind to make the average particle size of the mixture 5 μm or less, more preferably 3 μm or less.

The mixing ratio is preferably 5 to 20 parts by mass for the Sm ₂ O ₃ powder and 1 to 10 parts by mass for the Mn oxide powder or Cr oxide powder with respect to 100 parts by mass of the alloy powder. It is desirable that the amount of Ca as the reducing agent is 1.1 to 10 times the amount required for reduction of the Sm ₂ O ₃ powder and the Mn oxide powder or the Cr oxide powder. Further, it is desirable that the water content of the mixed powder of Sm ₂ Fe ₁₇ rare earth iron alloy powder, Sm ₂ O ₃ powder, Mn oxide powder or Cr oxide powder is less than 1% by mass.

Then, the inside of the reaction vessel is evacuated again, or the mixture is reduced and diffused by heat treatment while flowing an inert gas such as He or Ar into the vessel. This heat treatment is slightly different from the reduction / diffusion conditions in the second step, and is preferably 700 to 1000 ° C. in a temperature range of 650 to 1000 ° C., and Mn or Cr reduced by Ca is a Sm ₂ Fe ₁₇ alloy. The condition is that it does not diffuse into the powder. At temperatures lower than 650 ° C, even if the reduction of Sm ₂ O ₃ and Mn oxide and Cr oxide progresses with Ca, it is difficult to proceed with the formation of the shell layer by the diffusion reaction on the surface of the Sm ₂ Fe ₁₇ alloy powder, and the final result is obtained. The heat resistance of the magnetic powder is not improved. On the other hand, if the temperature exceeds 1000 ° C., the reduced Mn or Cr diffuses to the center of the Sm ₂ Fe ₁₇ alloy powder, and a shell layer having the desired thickness cannot be obtained, and improvement in heat resistance cannot be expected. ..

The heating retention time of the mixture is also set so as to adjust the thickness of the shell layer due to the diffusion of Mn or Cr. The mixture is kept at the set temperature for 8 hours or less. The holding time is preferably 5 hours or less, more preferably 1 hour or less. If it exceeds 8 hours, the thickness of the shell layer increases due to the diffusion of Mn or Cr, and it may be difficult to obtain the desired particle properties.

Next, the reaction product is subjected to a nitriding heat treatment at a temperature of 300 to 500 ° C. for 50 minutes to 24 hours in an air stream containing nitrogen gas, and if necessary, the atmosphere is switched to a mixed atmosphere of ammonia and hydrogen gas. It is preferable to carry out a nitriding heat treatment for 1 to 120 minutes.

In this way, the nitriding heat treatment is performed and then the wet treatment is performed. The wet treatment method and treatment conditions for the nitriding reaction product are the same as those for the wet treatment performed on the reduction diffusion product. That is, it is an operation in which the nitriding reaction product obtained in the nitriding heat treatment step is put into a glycol or a glycol liquid which is a first cleaning agent, and stirred to form a slurry for cleaning. The type and amount of glycol used are the same as above, and when a glycol solution is used, the water content specified by water / (glycol + water) is 50% by mass or less in order to suppress the oxidation of the nitride alloy powder. And. The water content is preferably 30% by mass or less, more preferably 10% by mass or less, still more preferably 5% by mass or less.

The powder in which the shell layer is formed on the obtained Sm ₂ Fe ₁₇ N ₃ alloy has a reduced amount of oxygen. The amount of oxygen depends on the average particle size and the particle size distribution, but is reduced to 30 to 70% by mass as compared with the case where the same reaction product is washed with water alone.

The physical characteristics of the magnet powder can be evaluated by using the resin composition as a binder and measuring the magnetic properties of the molded bonded magnet. The alloy powder with Sm ₂ Fe ₁₇ N ₃ alloy as the core and Sm ₂ (Fe, M) ₁₇ N _x (M = Cr, Mn) as the shell layer is more durable than the conventional method of washing with water alone. It has been confirmed that the magnetic force (MA / m) and squareness are nearly doubled, which is a remarkable effect.

Hereinafter, Examples will be described in more detail with reference to Comparative Examples, but the present invention is not limited to the following Examples.

[Example 1]
44 g of samarium oxide Sm ₂ O ₃ powder with an average particle size (D ₅₀ ) of 2.3 μm and a mass loss of 1% or less, 100 g of iron powder with an average particle size (D ₅₀ ) of 40 μm, and 23 g of granular metallic calcium with an average particle size (D 50) of 1 to 2 mm. Was mixed with a small mixer, placed in an iron pot, and heat-treated at 1100 ° C. for 7 hours under an atmosphere of argon gas.
100 g of the reaction product taken out after cooling was put into 550 g of ethylene glycol and left to stand for 12 hours with stirring to form a slurry. After stopping the stirring of this slurry and allowing it to stand for 2 minutes, the supernatant is discarded, 500 g of ethylene glycol is newly added, the mixture is stirred for 5 minutes, and the mixture is allowed to stand for 2 minutes, and the supernatant is discarded when the SmFe alloy powder has settled. This operation was repeated 5 times.
With 500 g of ethylene glycol added again and the alloy powder stirred, a solution prepared by diluting 15 g of acetic acid with 65 g of a mixture of ethylene glycol having a water content of 40% by mass and water was prepared, and a dropper was used for 40 minutes. Dropped. Then, the supernatant was discarded, 500 g of ethylene glycol was added again and the mixture was stirred, and the operation of removing the supernatant was performed three times. Finally, after replacing the ethylene glycol with 500 g of dehydrated ethyl alcohol, the alloy powder was recovered by filtration through a nutche. This was placed in a small mixer, stirred and dried at 150 ° C. for 6 hours while reducing the pressure to obtain 118 g of Sm ₂ Fe ₁₇ alloy powder having an average particle size of 28 μm.
In the cleaning liquid used in Example 1, the water content is highest after the entire amount of the mixed solution of acetic acid, ethylene glycol and water is added dropwise to ethylene glycol, and the water content of the cleaning liquid at this time is 4. It is 0.6% by mass.
The composition of this alloy powder is Sm of 24.5% by mass, O of 0.04% by mass, Ca of less than 0.01% by mass, the balance of iron, and the main phase is Th ₂ Zn ₁₇ type crystal structure Sm. It was ₂ Fe ₁₇ .
This alloy powder is placed in a tubular furnace and subjected to nitriding heat treatment at 450 ° C. for 8 hours while flowing at a flow rate ratio of ammonia gas: hydrogen gas = 1: 2, and then the atmosphere is switched to argon gas and heat treated for 1 hour to Sm. ₂ Fe ₁₇ N ₃ powder was prepared. When this powder was embedded in a resin, the cross section was polished, and the SEM reflected electron image was observed, it was confirmed that the inside of the particles was uniformly nitrided. The obtained powder was finely pulverized with an ethyl alcohol solvent in a medium stirring mill until _D50 became 2.2 μm, vacuum dried, and the magnetic characteristics were measured with a vibration sample magnetometer. As shown in Table 1. The coercive force HcJ was 0.89 MA / m, and the angular Hk was 0.48 MA / m, which were good.

[Comparative Example 1]
In the same manner as in Example 1, the raw material and the reducing agent were blended in the same amount and heat-treated under the same conditions to obtain a reduction-diffusion reaction product.
100 g of this reaction product was put into 1 L of water and stirred for 12 hours to form a slurry. After stopping the stirring of this slurry and allowing it to stand for 2 minutes, discard the supernatant, add 1 L of water, stir for 5 minutes, and let stand for 2 minutes to suspend calcium hydroxide when the SmFe alloy powder has settled. Discard the supernatant. This operation was repeated 5 times.
A solution prepared by diluting 15 g of acetic acid with 65 g of water was prepared by adding 1 L of water again and stirring the alloy powder, and the solution was added dropwise over 40 minutes with a dropper. Then, the supernatant was discarded, 1 L of water was added again, and the mixture was stirred to remove the supernatant three times. Finally, the water was replaced with 500 g of dehydrated ethyl alcohol, and then filtered through a nutche to recover the alloy powder. This was placed in a small mixer, stirred and dried at 150 ° C. for 6 hours while reducing the pressure to obtain 120 g of Sm ₂ Fe ₁₇ alloy powder having an average particle size of 26 μm.
The composition of this alloy powder is Sm of 24.3% by mass of Sm, 0.17% by mass of O, less than 0.01% by mass of Ca, the balance is iron, and the main phase is Th ₂ Zn ₁₇ type crystal structure Sm. It was ₂ Fe ₁₇ .
The obtained alloy powder was placed in a tube furnace in the same manner as in Example 1 to prepare a Sm ₂ Fe ₁₇ N ₃ powder. When this powder was embedded in a resin and the cross section was polished and the SEM reflected electron image was observed, about 10% of the particles had a bright contrast showing an unnitrided phase inside the particles. The magnetic properties of the fine powder after fine pulverization were measured. As shown in Table 1, the coercive force HcJ was 0.81 MA / m, and the angular Hk was 0.31 MA / m due to the unnitrided phase. showed that.

"evaluation"
Comparing Example 1 and Comparative Example 1, the magnetic property results of the alloy powder shown in Table 1 show that in Example 1, both the coercive force HcJ and the angular Hk are higher than those in Comparative Example 1. Since ethylene glycol was used in the wet treatment in Example 1, the amount of oxygen in the powder was reduced as compared with Comparative Example 1 which was washed with water. I understand.

[Example 2]
(1) First, the raw material and the reducing agent were mixed in the same amount in the same manner as in Example 1, and heat-treated under the same conditions to obtain a reduction-diffusion reaction product. Here, without wet treatment, this reaction product is placed in a tube furnace and subjected to nitriding heat treatment at 450 ° C. for 6 hours while flowing at a flow rate ratio of ammonia gas: hydrogen gas = 1: 2, and then the atmosphere is changed to argon. It was switched to gas and heat-treated for 1 hour.
100 g of the nitriding reaction product taken out after cooling was put into 550 g of propylene glycol and slurryed over 12 hours with stirring. After stopping the stirring of this slurry and allowing it to stand for 2 minutes, the supernatant is discarded, 500 g of propylene glycol is newly added, the mixture is stirred for 5 minutes, and the mixture is allowed to stand for 2 minutes, and the supernatant is discarded when the alloy powder has settled. This operation was repeated 5 times.
With 500 g of propylene glycol added again and the alloy powder stirred, a solution prepared by diluting 10 g of acetic acid with 100 g of a mixture of propylene glycol having a water content of 10% by mass and water was prepared, and a dropper was used for 40 minutes. Dropped. Then, the supernatant was discarded, 500 g of propylene glycol was added again, and the mixture was stirred to remove the supernatant three times. Finally, 500 g of dehydrated ethyl alcohol was used to replace the propylene glycol, and then the mixture was filtered through a nutche to recover the alloy powder. This was placed in a small mixer, stirred and dried at 180 ° C. for 2 hours while reducing the pressure to obtain 121 g of Sm ₂ Fe ₁₇ N ₃ alloy powder having an average particle size of 19 μm.
In the cleaning liquid used here, the water content is highest after dropping the entire mixed solution of acetic acid, ethylene glycol and water into ethylene glycol, and the water content of the cleaning liquid at this time is 1.7. It is mass%.
The composition of this alloy powder is 23.3% by mass for Sm, 3.5% by mass for N, 0.09% by mass for O, less than 0.01% by mass for Ca, the balance is iron, and the main phase is Th. It was Sm ₂ Fe ₁₇ N ₃ with a ₂ Zn ₁₇ type crystal structure.
When this powder was embedded in a resin, the cross section was polished, and the SEM reflected electron image was observed, it was confirmed that the inside of the particles was uniformly nitrided. The obtained powder was finely pulverized with an ethyl alcohol solvent in a medium stirring mill until _D50 became 2.3 μm, vacuum dried, and the magnetic characteristics were measured with a vibration sample magnetometer. As shown in Table 2. The coercive force HcJ was 0.94 MA / m, and the angular Hk was 0.57 MA / m, which were good.

(2) Next, in the same manner as in (1) above, all the cleaning liquids in the wet treatment were Sm ₂ Fe ₁₇ N ₃ having an average particle size of 18 μm, except that 500 g of propylene glycol containing 40% by mass of ion-exchanged water was used. 119 g of alloy powder was obtained.
In the cleaning liquid used here, the water content is highest after the total amount of a mixed solution of acetic acid, propylene glycol and water is added dropwise to propylene glycol, and the water content of the cleaning liquid at this time is 35% by mass. Is.
The composition of this alloy powder is 23.2% by mass for Sm, 3.5% by mass for N, 0.11% by mass for O, 0.01% by mass for Ca, the balance is iron, and the main phase is Th ₂ . It was Sm ₂ Fe ₁₇ N ₃ with a Zn ₁₇ type crystal structure.
When this powder was embedded in a resin, the cross section was polished, and the SEM reflected electron image was observed, it was confirmed that the inside of the particles was uniformly nitrided. The obtained powder was finely pulverized with an ethyl alcohol solvent in a medium stirring mill until _D50 became 2.3 μm, vacuum dried, and the magnetic characteristics were measured with a vibration sample magnetometer. As shown in Table 2. The coercive force HcJ was 0.90 MA / m, and the angular Hk was 0.55 MA / m, which were good.

[Comparative Example 2]
(1) First, the same amount of the raw material and the reducing agent are blended in the same manner as in Example 2, and heat-treated under the same conditions to obtain a reduction-diffusion reaction product. The product was obtained.
100 g of this nitriding reaction product was put into 1 L of water and stirred for 12 hours to form a slurry. After allowing this slurry to stand for 2 minutes, discard the supernatant, add 1 L of water, stir for 5 minutes, leave for 2 minutes, and discard the supernatant in which calcium hydroxide is suspended when the SmFeN alloy powder has settled. .. This operation was repeated 5 times. A solution prepared by diluting 10 g of acetic acid with 100 g of water was prepared by adding 1 L of water again and stirring the alloy powder, and the solution was added dropwise over 40 minutes with a dropper. Then, the supernatant was discarded, 1 L of water was added again, and the mixture was stirred to remove the supernatant three times. Finally, the water was replaced with 500 g of dehydrated ethyl alcohol, and then filtered through a nutche to recover the alloy powder. This was placed in a small mixer, stirred and dried at 180 ° C. for 2 hours while reducing the pressure to obtain 119 g of Sm ₂ Fe ₁₇ N ₃ alloy powder having an average particle size of 20 μm.
The composition of this alloy powder is 23.1% by mass for Sm, 3.5% by mass for N, 0.18% by mass for O, less than 0.01% by mass for Ca, the balance is iron, and the main phase is Th. It was Sm ₂ Fe ₁₇ N ₃ with a ₂ Zn ₁₇ type crystal structure.
When this powder was embedded in a resin and the cross section was polished and the SEM reflected electron image was observed, it was confirmed that the number of particles having an unnitrided phase was about 12%. The obtained powder was finely pulverized with an ethyl alcohol solvent in a medium stirring mill until _D50 became 2.3 μm, vacuum dried, and the magnetic characteristics were measured with a vibration sample magnetometer. As shown in Table 2. The coercive force HcJ was 0.78 MA / m, and the angular Hk was 0.40 MA / m.

(2) Next, in the same manner as in (1) above, all the cleaning liquids in the wet treatment were Sm ₂ Fe ₁₇ N ₃ having an average particle size of 21 μm, except that 500 g of propylene glycol containing 60% by mass of ion-exchanged water was used. 120 g of alloy powder was obtained.
The composition of this alloy powder is 23.2% by mass for Sm, 3.5% by mass for N, 0.15% by mass for O, less than 0.01% by mass for Ca, the balance is iron, and the main phase is Th. It was Sm ₂ Fe ₁₇ N ₃ with a ₂ Zn ₁₇ type crystal structure.
When this powder was embedded in a resin and the cross section was polished and the SEM reflected electron image was observed, it was confirmed that the number of particles having an unnitrided phase was about 4% based on the number of particles. The obtained powder was finely pulverized with an ethyl alcohol solvent in a medium stirring mill until _D50 became 2.3 μm, vacuum dried, and the magnetic characteristics were measured with a vibration sample magnetometer. As shown in Table 2. The coercive force HcJ was 0.83 MA / m, and the angular Hk was 0.44 MA / m.

"evaluation"
Comparing Example 2 (1) and Comparative Example 2 (1), from the magnetic property results of the alloy powder shown in Table 2, in Example 2 (1) using propylene glycol in the wet treatment, the coercive force HcJ, Both square Hk show higher values than Comparative Example 2 (1) using water. Further, in Example 2 (2), since the oxygen content of the powder is smaller than that of Comparative Example 2 (2) washed with a propylene glycol solution having a water content of 60% by mass or more, the wet treatment is performed. It can be seen that the use of propylene glycol having a water content of 40% by mass or less has a remarkable effect.

[Example 3]
The operation of Example 1 was repeated under the same conditions to obtain 600 g of Sm ₂ Fe ₁₇ alloy powder. This alloy powder has an average particle size (D ₅₀ ) of 29 μm, Sm of 24.5% by mass, O of 0.07% by mass, Ca of less than 0.01% by mass, and the balance of iron. The main phase is Sm ₂ Fe ₁₇ having a Th ₂ Zn ₁₇ type crystal structure.
Next, with respect to 500 g of this Sm ₂ Fe ₁₇ alloy powder, 33.0 g of samarium oxide Sm ₂ O ₃ powder having an average particle size (D ₅₀ ) of 1.5 μm and a mass loss of 1% or less, and an average particle size (D 50). 13.0 g of Mn ₃ O ₄ powder having a _D50 ) of 0.3 μm was added, and the mixture was finely ground while mixing with a medium stirring mill using n-heptane as a solvent, and then dried under reduced pressure. The average particle size (D ₅₀ ) of the obtained mixed powder was 2.1 μm.
To this mixed powder, 153 g of granular metallic calcium of 1 to 2 mm is added in an Ar gas atmosphere and mixed for 30 minutes with a locking mixer. As a reduction diffusion treatment, the mixture is placed in an iron crucible and heated in an Ar gas atmosphere at 860 ° C. It was held for 1.5 hours and cooled.
The recovered reaction product is crushed to a size of 10 mm or less, placed in a tubular furnace as a nitriding heat treatment, heated in a stream of N ₂ gas 3.6 L / min, maintained at 400 ° C. for 22 hours, and maintained at a temperature. While still, switch to a mixed gas of NH ₃ gas 1.5 L / min and H ₂ gas 2.1 L / min and hold for 60 min, and then switch to Ar gas 3.6 L / min and hold for 60 min at the same temperature to cool. did.
100 g of the nitriding reaction product taken out after cooling was put into 500 g of ethylene glycol and slurryed over 12 hours with stirring. After stopping the stirring of this slurry and allowing it to stand for 2 minutes, the supernatant is discarded, 500 g of ethylene glycol is newly added, the mixture is stirred for 5 minutes, and the mixture is allowed to stand for 2 minutes, and the supernatant is discarded when the alloy powder has settled. This operation was repeated 8 times. Subsequently, after replacing ethylene glycol with 500 g of dehydrated ethyl alcohol, the alloy powder was recovered by filtration through Nuche. This was placed in a small mixer, stirred and dried at 150 ° C. for 2 hours while reducing the pressure to obtain 71 g of a rare earth iron nitrogen-based magnetic powder having an average particle size (D ₅₀ ) of 3.2 μm.
In the operation of Example 1, the reduction / diffusion reaction product is pickled, but in Example 3, the nitriding reaction product is not pickled. Therefore, the cleaning liquid used in the wet treatment does not contain water (water content is 0% by mass).
This rare earth iron nitride-based magnetic powder has a crystal structure of Th ₂ Zn ₁₇ type as the main phase, and by TEM observation, Sm ₂ (Fe, Mn) _{17 Ny} shell layer on the particle surface, and Mn is almost diffused inside. It was confirmed that it had a core-shell structure having a non-Sm ₂ Fe ₁₇ N ₃ core. In this shell layer, a metal structure composed of cellular microcrystal grains and an amorphous boundary layer, and a wire having high and short concentrations of Mn and N inside the Sm ₂ (Fe, Mn) _{17 Ny} compound crystal phase. It was observed that the amorphous phase had a random or regular presence in the metal structure. Analyzing the whole of this magnetic powder, the average composition is 28.1% by mass for Sm, 1.7% by mass for Mn, 3.6% by mass for N, 0.38% by mass for O, and 0.17 for Ca. Mass%, the balance was iron. When the magnetic properties of the magnetic powder were measured with a vibration sample magnetometer, the coercive force HcJ was 1.18 MA / m and the square Hk was 0.27 MA / m as shown in Table 3.

[Comparative Example 3]
In the same manner as in Example 3, the raw material and the reducing agent were blended in the same amount, heat-treated under the same conditions to obtain a reduction diffusion reaction product, and further subjected to nitriding heat treatment to obtain a nitriding reaction product.
100 g of the nitriding reaction product taken out after cooling was put into 1 L of water and stirred for 12 hours to form a slurry. After stopping the stirring of this slurry and allowing it to stand for 2 minutes, discard the supernatant, add 1 L of water, stir for 5 minutes, and let stand for 2 minutes to suspend calcium hydroxide when the SmFe alloy powder has settled. Discard the supernatant. This operation was repeated 8 times. Subsequently, after replacing the water with 500 g of dehydrated ethyl alcohol, the alloy powder was recovered by filtration through Nutche. This was placed in a small mixer, stirred and dried at 150 ° C. for 2 hours while reducing the pressure to obtain 68 g of a rare earth iron nitrogen-based magnetic powder having an average particle size (D ₅₀ ) of 3.0 μm.
Even in this rare earth iron nitrogen-based magnetic powder, the main phase is a Th ₂ Zn ₁₇ -type crystal structure, and by TEM observation, the Sm ₂ (Fe, Mn) _{17 Ny} shell layer is almost diffused inside the particle surface. It was confirmed that the shell layer had a core-shell structure having a non-Sm ₂ Fe ₁₇ N ₃ core, and the shell layer had a metal structure composed of cellular fine crystal grains and an amorphous boundary layer, and Sm ₂ (Fe). , Mn) A metal structure was observed in which a wire-like amorphous phase having a high concentration of Mn and N and long and short was randomly or regularly present inside the _{17 Ny} compound crystal phase. Analyzing the whole of this magnetic powder, the average composition is 27.9% by mass for Sm, 1.7% by mass for Mn, 3.5% by mass for N, 1.5% by mass for O, and 0.36 for Ca. It is considered that the oxidation proceeded because the mass% was iron, the balance was iron, and O and Ca were higher than those in Example 3. When the magnetic properties of the magnetic powder were measured with a vibration sample magnetometer, the coercive force HcJ was 0.61 MA / m and the square Hk was 0.14 MA / m, which are quite low values, as shown in Table 3.

"evaluation"
Comparing Example 3 and Comparative Example 3, from the magnetic property results of the alloy powder shown in Table 3, in Example 3, both the coercive force HcJ and the angular Hk show higher values than in Comparative Example 3. Since ethylene glycol was used in the wet treatment in Example 3, the amount of oxygen and Ca in the powder was lower than that in Comparative Example 3 washed with water. Therefore, it is remarkable that ethylene glycol was used in the wet treatment. You can see the effects.

[Example 4]
405 g of neodymium oxide Nd ₂ O ₃ powder with an average particle size (D ₅₀ ) of 4.7 μm and a mass loss of 1% or less, 405 g of iron powder with an average particle size (D ₅₀ ) of 40 μm, and an average particle size (D ₅₀ ). 65 g of 63 μm ferroboron powder (B content 18.7% by mass), 217 g of granular metallic calcium of 1 to 2 mm, and 20 g of anhydrous calcium chloride are mixed with a small mixer, placed in an iron pot, and placed at 1000 ° C. under an argon gas atmosphere. It was heat-treated for 3 hours.
100 g of the reaction product taken out after cooling was put into 500 g of ethylene glycol and slurryed over 12 hours with stirring. After stopping the stirring of this slurry and allowing it to stand for 2 minutes, the supernatant is discarded, 500 g of ethylene glycol is newly added, the mixture is stirred for 5 minutes, and the mixture is allowed to stand for 2 minutes, and the supernatant is discarded when the NdFeB alloy powder has settled. This operation was repeated 5 times. With 500 g of ethylene glycol added again and the alloy powder stirred, a solution prepared by diluting 20 g of acetic acid with 20 g of a mixture of ethylene glycol having a water content of 50% by mass and water was prepared, and the pH was added dropwise with a dropper. = 6.0 was maintained for 5 minutes. Then, the supernatant was discarded, 500 g of ethylene glycol was added again, and the mixture was stirred to remove the supernatant three times. Finally, after replacing the ethylene glycol with 500 g of dehydrated ethyl alcohol, the alloy powder was collected by filtration through a nutche. This was placed in a small mixer, stirred and dried at 100 ° C. for 5 hours while reducing the pressure to obtain 58 g of NdFeB alloy powder having an average particle size of 20 μm.
In the cleaning liquid used in Example 4, the water content is highest after the entire amount of the mixed solution of acetic acid, ethylene glycol and water is added dropwise to ethylene glycol, and the water content of the cleaning liquid at this time is 1. It is 9.9% by mass.
The composition of this alloy powder is 33.5% by mass of Nd, 1.3% by mass of B, 0.07% by mass of O, 0.01% by mass of Ca, and the balance is iron, and the crystal structure of the main phase. Was an Nd ₂ Fe ₁₄ B-type tetragonal crystal.

[Comparative Example 4]
In the same manner as in Example 4, the raw material and the reducing agent were blended in the same amount and heat-treated under the same conditions to obtain a reduction-diffusion reaction product.
100 g of this reaction product was put into 1 L of water and stirred for 12 hours to form a slurry. After stopping the stirring of this slurry and allowing it to stand for 2 minutes, discard the supernatant, add 1 L of water, stir for 5 minutes, and let stand for 2 minutes to suspend calcium hydroxide when the SmFe alloy powder has settled. Discard the supernatant. This operation was repeated 5 times. With 1 L of water added again and the alloy powder stirred, a solution prepared by diluting 20 g of acetic acid with 20 g of water was prepared, and pH = 6.0 was maintained for 5 minutes while dropping with a dropper. Then, the supernatant was discarded, 1 L of water was added again, and the mixture was stirred to remove the supernatant three times. Finally, the water was replaced with 500 g of dehydrated ethyl alcohol, and then filtered through a nutche to recover the alloy powder. This was placed in a small mixer, stirred and dried at 100 ° C. for 5 hours while reducing the pressure to obtain 63 g of NdFeB alloy powder having an average particle size of 21 μm.
The composition of this alloy powder is 33.4% by mass of Nd, 1.3% by mass of B, 0.17% by mass of O, 0.02% by mass of Ca, and the balance is iron, and the crystal structure of the main phase. Was an Nd ₂ Fe ₁₄ B-type tetragonal crystal. It can be seen that the amount of O is higher than that of Example 4.

"evaluation"
Comparing Example 4 and Comparative Example 4, the oxygen content of the alloy powder shown in Table 4 shows that the oxygen content of the powder in Example 4 is smaller than that in Comparative Example 4. In Example 4, ethylene glycol is used in the wet treatment, and a remarkable effect on Comparative Example 4 washed with water is obtained.

[Example 5]
157 g of samarium oxide Sm ₂ O ₃ powder with an average particle size (D ₅₀ ) of 2.3 μm and a mass loss of 1% or less, 264 g of cobalt powder with an average particle size (D ₅₀ ) of 62 μm, and 76 g of granular metallic calcium with an average particle size (D 50) of 1 to 2 mm. Was mixed with a small mixer, placed in an iron crucible, and heat-treated at 950 ° C. for 2 hours under an atmosphere of argon gas.
100 g of the reaction product taken out after cooling was put into 500 g of ethylene glycol and slurryed over 6 hours with stirring. After stopping the stirring of this slurry and allowing it to stand for 2 minutes, the supernatant is discarded, 500 g of ethylene glycol is newly added, the mixture is stirred for 5 minutes, and the mixture is allowed to stand for 2 minutes, and the supernatant is discarded when the SmFe alloy powder has settled. This operation was repeated 5 times. With 500 g of ethylene glycol added again and the alloy powder stirred, a solution prepared by diluting 20 g of acetic acid with 20 g of a mixture of ethylene glycol having a water content of 50% by mass and water was prepared, and the pH was added dropwise with a dropper. = 4.0 was maintained for 5 minutes. Then, the supernatant was discarded, 500 g of ethylene glycol was added again, and the mixture was stirred to remove the supernatant three times. Finally, after replacing the ethylene glycol with 500 g of dehydrated ethyl alcohol, the alloy powder was collected by filtration through a nutche. This was placed in a small mixer, stirred and dried at 100 ° C. for 5 hours while reducing the pressure to obtain 58 g of SmCo ₅ alloy powder having an average particle size of 20 μm.
In the cleaning liquid used in Example 5, the water content is highest after the entire amount of the mixed solution of acetic acid, ethylene glycol and water is added dropwise to ethylene glycol, and the water content of the cleaning liquid at this time is 1. It is 9.9% by mass.
The composition of this alloy powder was 33.8% by mass of Sm, 0.06% by mass of O, 0.01% by mass of Ca, the balance was cobalt, and the crystal structure of the main phase was CaCu ₅ type hexagonal crystal. ..

[Comparative Example 5]
In the same manner as in Example 5, the raw material and the reducing agent were blended in the same amount and heat-treated under the same conditions to obtain a reduction-diffusion reaction product.
100 g of this reaction product was put into 1 L of water and left for 6 hours while stirring to form a slurry. After stopping stirring this slurry and letting it stand for 2 minutes, discard the supernatant, add 1 L of water, stir for 5 minutes, and let stand for 2 minutes to suspend calcium hydroxide when the SmFe alloy powder has settled. Discard the supernatant. This operation was repeated 5 times. With 1 L of water added again and the alloy powder stirred, a solution prepared by diluting 20 g of acetic acid with 20 g of water was prepared, and pH = 4.0 was maintained for 5 minutes while dropping with a dropper. Then, the supernatant was discarded, 1 L of water was added again, and the mixture was stirred to remove the supernatant three times. Finally, the water was replaced with 500 g of dehydrated ethyl alcohol, and then filtered through a nutche to recover the alloy powder. This was placed in a small mixer, stirred and dried at 100 ° C. for 5 hours while reducing the pressure to obtain 55 g of SmCo ₅ alloy powder having an average particle size of 19 μm.
The composition of this alloy powder was 33.6% by mass of Sm, 0.18% by mass of O, 0.04% by mass of Ca, the balance was cobalt, and the crystal structure of the main phase was CaCu ₅ type hexagonal crystal. ..

"evaluation"
Comparing Example 5 and Comparative Example 5, from the results of the oxygen content of the alloy powder shown in Table 4, the oxygen content and the Ca amount of the powder in Example 5 are smaller than those in Comparative Example 5. In Example 5, ethylene glycol is used in the wet treatment, and a remarkable effect on Comparative Example 5 washed with water is obtained.

[Example 6]
67 g of lanthanum oxide La ₂ O ₃ powder having an average particle size (D ₅₀ ) of 3.8 μm and a mass loss of 1% or less, 100 g of nickel powder having a particle size of 53 μm or less, and 30 g of granular metallic calcium having a particle size of 1 to 2 mm are mixed in a small mixer. It was placed in an iron crucible and heat-treated at 1000 ° C. for 4 hours under an atmosphere of argon gas.
100 g of the reaction product taken out after cooling was put into 500 g of ethylene glycol containing 50% by mass of ion-exchanged water and left to stand for 6 hours with stirring to form a slurry. After stopping the stirring of this slurry and letting it stand for 2 minutes, discard the supernatant, add 500 g of ethylene glycol containing 50% by mass of ion-exchanged water, stir for 5 minutes, and let stand for 2 minutes to settle the LaNi alloy powder. Discard the supernatant at that point. This operation was repeated 5 times. Prepare a solution obtained by diluting 8 g of acetic acid with 20 g of a mixture of ethylene glycol having a water content of 50% by mass and water in a state where 500 g of ethylene glycol containing 45% by mass of ion-exchanged water is added again and the alloy powder is stirred. Then, pH = 4.0 was maintained for 10 minutes while dropping with a dropper. After that, discard the supernatant, add 500 g of ethylene glycol containing 50% by mass of ion-exchanged water again, stir to remove the supernatant three times, and finally replace the ethylene glycol with 500 g of dehydrated ethyl alcohol, and then filter with Nuche. The alloy powder was recovered. This was placed in a small mixer, stirred and dried at 100 ° C. for 5 hours while reducing the pressure to obtain 73 g of LaNi alloy powder having an average particle size of 32 μm.
In the cleaning liquid used in Example 6, the water content is highest when decanting with ethylene glycol containing 50% by mass of ion-exchanged water, and the water content of the cleaning liquid at this time is 50% by mass. Is.
The composition of this alloy powder was 36.6% by mass of La, 0.05% by mass of O, 0.02% by mass of Ca, the balance was nickel, and the crystal structure of the main phase was CaCu ₅ type hexagonal crystal. ..

[Example 7]
74 g of LaNi alloy powder having an average particle size of 33 μm was obtained in the same manner as in Example 6 except that all the cleaning liquids in the wet treatment were ethylene glycol containing 25% by mass of ion-exchanged water. The water content of the cleaning liquid used here is 25% by mass.
The composition of this alloy powder was 36.8% by mass of La, 0.04% by mass of O, 0.06% by mass of Ca, the balance was nickel, and the crystal structure of the main phase was CaCu ₅ type hexagonal crystal. ..

[Example 8]
77 g of LaNi alloy powder having an average particle size of 35 μm was obtained in the same manner as in Example 6 except that all the cleaning liquids in the wet treatment were 500 g of ethylene glycol containing 5% by mass of ion-exchanged water. The water content of the cleaning liquid used here is 5% by mass.
The composition of this alloy powder was 37.0% by mass of La, 0.03% by mass of O, 0.07% by mass of Ca, the balance was nickel, and the crystal structure of the main phase was CaCu ₅ type hexagonal crystal. ..

[Example 9]
78 g of LaNi alloy powder having an average particle size of 37 μm was obtained in the same manner as in Example 6 except that all the cleaning liquids in the wet treatment were 500 g of ethylene glycol containing no water. The water content of the cleaning liquid used here is 0% by mass.
The composition of this alloy powder was 37.2% by mass of La, 0.02% by mass of O, 0.1% by mass of Ca, the balance was nickel, and the crystal structure of the main phase was CaCu ₅ type hexagonal crystal. ..

[Comparative Example 6]
In the same manner as in Example 6, the raw material and the reducing agent were blended in the same amount and heat-treated under the same conditions to obtain a reduction-diffusion reaction product.
100 g of this reaction product was put into 0.5 L of ion-exchanged water and slurryed over 6 hours with stirring. After stopping the stirring of this slurry and letting it stand for 2 minutes, discard the supernatant, add 0.5 L of ion-exchanged water, stir for 5 minutes, leave it for 2 minutes, and hydroxylate when the LaNi alloy powder has settled. Discard the supernatant on which calcium is suspended. This operation was repeated 5 times. With 0.5 L of water added again and the alloy powder stirred, a solution prepared by diluting 8 g of acetic acid with 20 g of ion-exchanged water was prepared, and pH = 4.0 was maintained for 10 minutes while dropping with a dropper. After that, the supernatant was discarded, 0.5 L of ion-exchanged water was added again, and the mixture was stirred to remove the supernatant three times. Finally, the water was replaced with 500 g of dehydrated ethyl alcohol, and then filtered through a nutche to recover the alloy powder. .. This was placed in a small mixer, stirred and dried at 100 ° C. for 5 hours while reducing the pressure to obtain 75 g of LaNi alloy powder having an average particle size of 34 μm.
The composition of this alloy powder was 36.9% by mass of La, 0.13% by mass of O, 0.02% by mass of Ca, the balance was nickel, and the crystal structure of the main phase was CaCu ₅ type hexagonal crystal. ..

[Comparative Example 7]
76 g of LaNi alloy powder having an average particle size of 31 μm was obtained in the same manner as in Comparative Example 6 except that 500 g of ethylene glycol containing 60% by mass of ion-exchanged water was used for all the cleaning liquids in the wet treatment. The water content of the cleaning liquid used here is 60% by mass.
The composition of this alloy powder was 36.5% by mass of La, 0.10% by mass of O, 0.03% by mass of Ca, the balance was nickel, and the crystal structure of the main phase was CaCu ₅ type hexagonal crystal. ..

"evaluation"
From the results of the oxygen content of the alloy powder shown in Table 5, the oxygen content of the powder in Examples 6 to 9 is lower than that in Comparative Examples 6 and 7. By comparing Examples 6 and 9 with Comparative Example 7, it can be seen that the use of ethylene glycol or an ethylene glycol solution having a water content of 50% by mass or less in the wet treatment has a remarkable effect.

Since the rare earth transition metal alloy powder of the present invention can contain less oxygen than before, it is a raw material alloy in a wide range of fields such as rare earth magnet alloys, hydrogen storage alloys, magnetic strain alloys, photomagnetic recording alloys, and magnetic refrigeration materials. Or as a rare earth sintered magnet or a bonded magnet.

Claims (8)

A first step of mixing a raw material containing a rare earth oxide powder and a transition metal powder with at least one reducing agent selected from an alkali metal, an alkaline earth metal and a hydride thereof at a predetermined ratio, and a mixture thereof. In the second step of heating and reducing and diffusing in an inert gas atmosphere, and a wet treatment in which the obtained reaction product is put into a washing liquid to disintegrate the reaction product, the reducing agent is reduced from the reaction product, and then the reaction product is subjected to a wet treatment. A method for producing a rare earth transition metal alloy powder, which comprises a third step of adding an acid and a cleaning liquid to an alloy slurry of a cleaning liquid to perform acid cleaning, and then adding a cleaning liquid to remove the acid.
A method for producing a rare earth transition metal alloy powder, wherein the cleaning liquid is a glycol having a water content of 0 to 50% by mass defined by water / (glycol + water). The rare earth oxide powder is characterized by containing one or more rare earth elements selected from Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, and Yb. The method for producing a rare earth transition metal alloy powder according to 1. The production of the rare earth transition metal alloy powder according to claim 1 or 2, wherein the transition metal powder contains one or more transition elements selected from Fe, Co, Ni, Cu, Cr, and Mn. Method. Claims 1 to 3 are characterized in that the cleaning liquid is a liquid containing one or more alkylene glycols selected from ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol and water. The method for producing a rare earth transition metal alloy powder according to any one of the above items. The method for producing a rare earth transition metal alloy powder according to any one of claims 1 to 4, wherein the acid is one or more selected from hydrochloric acid, acetic acid, nitric acid, and sulfuric acid. The rare earth transition according to any one of claims 1 to 5, wherein the rare earth transition metal alloy powder obtained in the third step is further heated and nitrided in an atmosphere containing nitrogen and / or ammonia. Method for manufacturing metal alloy powder. A first step of mixing a raw material containing a rare earth oxide powder and a transition metal powder with at least one reducing agent selected from an alkali metal, an alkaline earth metal and a hydride thereof at a predetermined ratio, and a mixture thereof. A second step of heating and reducing and diffusing in an inert gas atmosphere, a fourth step of heating and nitriding the obtained reaction product in a nitrogen and / or ammonia-containing atmosphere, and the obtained nitriding reaction product. A fifth step of adding an acid to the nitride alloy slurry after performing a wet treatment of adding the metal to the cleaning liquid to disintegrate it to reduce the reducing agent from the nitriding reaction product, and then adding the cleaning liquid to remove the acid. A method for producing a rare earth transition metal alloy powder, including
A method for producing a rare earth transition metal alloy powder, wherein the cleaning liquid is a glycol having a water content of 0 to 50% by mass defined by water / (glycol + water). Rare earth transition metal alloy powder containing Sm and Fe, rare earth oxide powder containing Sm, transition metal oxide powder containing Mn and / or Cr, alkali metal, alkaline earth metal, and hydrides thereof. After mixing at least one reducing agent selected from the above in a predetermined ratio, heating the mixture in an inert gas atmosphere for reduction and diffusion, the obtained reduction and diffusion reaction product contains nitrogen and / or ammonia. A rare earth transition metal alloy powder including a step of heating in an atmosphere to nitrid the metal, followed by a wet treatment in which the obtained nitriding reaction product is put into a cleaning liquid to cause disintegration, and the reducing agent is reduced from the nitriding reaction product. It ’s a manufacturing method,
A method for producing a rare earth transition metal alloy powder, wherein the cleaning liquid is a glycol having a water content of 0 to 50% by mass defined by water / (glycol + water).