JPH0620814A - Manufacture of nitride magnetic powder - Google Patents

Abstract

PURPOSE:To manufacture a rare earth-iron nitride having less initial variation with time of coercive force, improved filling density and high saturated magnetization. CONSTITUTION:When the magnet material of rare earth-iron nitride is going to be pulverized using an organic solvent consisting at least of a coupling agent and/or a lubricant, alcohol of C2 or higher, ketone of C3 or higher, and hydrocarbon of C5 or higher, a nitride is pulverized by bringing the oxygen concentration in a pulverizer into 0<O2<=5vol.%. A rare earth-iron nitride is indicated as R-Fe-N-X-Z magnet compound. R indicates one or more kinds of elements selected from rare earth element(La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb) and Y. X indicates one or more kinds of elements selected from B, Ti, Mo, Cr and Co. Z indicates one or more kinds of elements selected from O, H and C. There is a case where X and Z are not contained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing magnetic powder of rare earth-iron based nitride having excellent magnetic properties. Since the nitride magnetic powder has excellent magnetic properties, it is used as a small motor, an actuator, etc. in home appliances, audio equipment, office equipment, automobile fields, etc., and at the same time used as a large magnet for medical equipment. It has a wide range of applications in various fields of electronics.

[0002]

2. Description of the Related Art As a method for producing fine powder of rare earth-iron-based nitride magnetic powder having excellent magnetic properties, various grinding methods have been proposed so far. For example, Japanese Patent Laid-Open No. 2-257603
In the examples described in the publication, crushing is performed by a planetary ball mill in addition to a vibrating ball mill, and it is described in the text that a cutter mill or a jet mill can also be used.

However, in the conventional methods, the coercive force can be improved by pulverizing the powder, but the saturation magnetization is greatly reduced, which is not sufficiently satisfactory. Further, the magnetic powder produced by the ball mill pulverization has a significant decrease in coercive force when left in the air, and it is difficult to obtain a compact with a high packing density when the magnetic powder is used as a bonded magnet, and a new pulverization method for fine powder is desired. ing.

[0004]

DISCLOSURE OF THE INVENTION According to the present invention, even if the coercive force is improved by pulverizing a rare earth-iron-based nitride, the saturation magnetization is less reduced and the coercive force is less likely to change with time in the initial stage. It is an object of the present invention to provide a pulverizing method and a pulverizing method of the above-mentioned nitride which can improve the packing density when the magnetic powder is made into a bonded magnet.

[0005]

[Means for Solving the Problems] The present inventors
As a result of extensive studies on a method for pulverizing iron-based nitrides, an effective solution to the above problems was found and the present invention was achieved. That is, the present invention is a method for producing a nitride magnetic powder in which a rare earth-iron-based nitride that is a magnet material is finely pulverized by using a wet pulverizer, and a coupling agent and / or a lubricant, C2 or more alcohols, C3 or more Is a ketone and an organic solvent containing at least one of C5 or higher hydrocarbons, and is pulverized in an atmosphere having an oxygen concentration of 0 <O ₂ ≤5 vol%. .

In the present invention, the rare earth-iron-based nitride is R
Represents a —Fe—N—X—Z based magnet compound. Here, R is a rare earth element (La, Ce, Pr, Nd, Sm, Eu, G
d, Tb, Dy, Ho, Er, Tm, Yb) and one or more elements selected from Y. X is B, Ti, M
It means one or more elements selected from o, Cr and Co, but it may not be contained. Z is one or more elements selected from O, H and C. Here, X and Z may not be contained in some cases.

R is a rare earth element (La, Ce, Pr, N
d, Sm, Eu, Gd, Tb, Dy, Ho, Er, T
m, Yb) and one or more elements selected from Y, preferably Sm, Nd, Pr, Ce, Dy, G
d and La, and more preferably Sm, Nd and Pr. X represents B, Ti, Mo, Cr, Co, preferably B, Cr, Co, and more preferably Co. As a preferable specific example, Sm-Fe-N system, S
m- (Nd, Pr) -Fe-N system, Sm-Fe-N-H
System, Sm- (Nd, Pr) -Fe-N-H system, Sm-F
e-N-O system, Sm- (Nd, Pr) -Fe-N-O
System, Sm-Fe-N-H-O system, Sm- (Nd, Pr)
-Fe-NH-O system, Sm-Fe-Co-N system, Sm
-(Nd, Pr) -Fe-Co-N system, Sm-Fe-C
o-N-H system, Sm- (Nd, Pr) -Fe-Co-N
-H system, Sm-Fe-Co-N-H-O system, Sm- (N
d, Pr) -Fe-Co-N-H-O system. The crystal structure of each of these is preferably hexagonal, rhombohedral or tetragonal.

Organic solvents include C2 or higher alcohols and C
Examples include ketones of 3 or more, hydrocarbons of C5 or more, and mixtures thereof. Examples include ethanol, n-propyl alcohol, i-propyl alcohol, and n-butanol.
Examples include alcohols such as alcohol, i-butanol and cellosolve, ketones such as acetone, methyl ethyl ketone and cyclohexanone, and hydrocarbon compounds such as cyclohexane, hexane, heptane, octane, mineral spirits, benzene, toluene and xylene. Preferred are i-propyl alcohol, acetone, methyl ethyl ketone and cyclohexane.

Specific examples of the coupling agent used in the present invention include isopropyl triisostearoyl titanate, isopropyl tri (N-aminoethyl-aminoethyl) titanate, isopropyl tris (dioctyl pyrophosphate) titanate, tetraisopropyl bis (dioctyl). Phosphite) titanate, tetraisopropyl titanate, tetrabutyl titanate, tetraoctyl bis (ditridecyl phosphite) titanate, isopropyl trioctanoyl titanate, isopropyl tridodecylbenzene sulfonyl titanate, isopropyl tri (dioctyl phosphate) titanate, bis (dioctyl) Pyrophosphate) ethylene titanate, isopropyl dimethacryl isostearoyl titanate, tetra ( , 2-diallyloxymethyl -
Titanium coupling agents such as 1-butyl) bis (ditridecyl phosphite) titanate, isopropyl tricumyl phenyl titanate, bis (dioctyl pyrophosphate) oxyacetate titanate, isopropyl isostearoyl diacrylic titanate, γ-aminopropyl triethoxysilane , N-β- (aminoethyl)
-Γ-aminopropyltrimethoxysilane, γ-glycidoxy-propyltrimethoxysilane, β- (3,4-
Epoxy-cycloxyl) ethyltrimethoxysilane,
Vinyltriethoxysilane, vinyl-tris (2-methoxyethoxy) silane, diphenyldimethoxysilane,
γ-mercaptopropyltrimethoxysilane, N-β-
(Aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N- (3-triethoxysilylpropyl) urea, methyltrimethoxysilane, octadecyltriethoxysilane, vinyltriacetoxysilane, γ -Chloropropyltrimethoxysilane, hexamethyldisilazane, γ-anilinopropyltrimethoxysilane, octadecyldimethyl [3- (trimethoxysilyl) propyl] ammonium chloride, γ-chloropropylmethyldimethoxysilane, methyltrichlorosilane, polyalkylene In addition to silicon-containing coupling agents such as oxide silanes and perfluoroalkyltrimethoxysilanes, aluminum compounds such as acetoalkoxy aluminum diisopropylate Examples include coupling agents such as aluminum, zirconium, chromium, iron and tin.

Preferably, titanates such as isopropyl triisostearoyl titanate, isopropyl tri (N-aminoethyl-aminoethyl) titanate, isopropyl tris (dioctyl pyrophosphate) titanate and isopropyl trioctanoyl titanate,
γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, γ-glycidoxy-propyltrimethoxysilane,
Silane-based cups such as β- (3,4-epoxy-cycloxyl) ethyltrimethoxysilane, vinyltriethoxysilane, vinyl-tris (2-methoxyethoxy) silane, diphenyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane Ring agents may be mentioned.
The addition amount is preferably 0.001 to 5 wt% with respect to the magnetic powder.

Specific examples of the lubricant include stearic acid, oleic acid, palmitic acid, linoleic acid, lauric acid,
Fatty acids such as 1,2-oxystearic acid and ricinoleic acid, amines such as oleylamine, stearylamine and laurylamine, amino acids such as glycine, alanine, aspartic acid, arginine and histidine, zinc stearate, calcium stearate, stearin Acid salts of barium acid, aluminum stearate, magnesium stearate, zinc laurate, calcium laurate, zinc ricinoleate, calcium ricinoleate, zinc 2-ethylhexoate, stearic acid amide,
Fatty acid amides such as hydroxystearic acid amide and palmitic acid amide, Si ₃ N ₄ , SiC, MgO, A
Inorganic compound powder such as l ₂ O ₃ , TiC, Sb ₂ O ₃ , silicone oil, silicone grease, silicone resin, polysiloxane such as polysilane coupling agent, fatty acid ester such as butyl stearate, ethylene glycol, stearyl Alcohols such as alcohol, paraffin wax, liquid paraffin, polyethylene wax,
Waxes such as polypropylene wax, ester wax, carnauba wax, and microwax can be used. Preferred are amines, fatty acid amides and waxes. Usually, one or more of these lubricants are used. The addition amount is preferably 0.001 to 5 wt% with respect to the magnetic powder.

A dispersant may be added simultaneously with the lubricant. As the dispersant, polycarboxylic acid sodium salt, polycarboxylic acid ammonium salt, condensed naphthalenesulfonic acid sodium salt, condensed naphthalenesulfonic acid ammonium salt, cationic surfactant, anionic surfactant, nonionic surfactant, diamine Examples thereof include system surfactants, polyvalent amine surfactants, amide surfactants, ester nonionic surfactants, and polyfunctional ester polymers.

In the wet pulverizer used in the present invention, a cylindrical pulverizing section is filled with spherical balls as a pulverizing medium, and a magnetic material such as nitride magnetic powder, a coupling agent and / or Alternatively, the lubricant and the organic solvent are added to form a crushing unit, and the crushing unit is rotated, or the ball is forcibly moved to perform crushing. The fine powder obtained by the present invention has an average particle size of 20 μm or less, preferably 10 μm.
m or less.

The type of wet crusher is not particularly limited,
Examples thereof include a conventional wet ball mill, a vertical wet mill such as an attritor, a horizontal wet mill such as a dyno mill, and a vibrating ball mill that vibrates a pot from the outside. There are no particular restrictions on the type of ball, but for example,
Ceramics include alumina, zirconia, glass and the like, and metals include stainless steel and the like.

When a coupling agent or a lubricant is present during pulverization, the surface of the pulverized magnetic powder is coated with the coupling agent or the lubricant to prevent particles from adhering to each other, thereby increasing the pulverization speed. Further, the coating of the coupling agent and the lubricant stabilizes the surface and prevents the reduction of the coercive force. In addition, since there is no newly formed interface, abrupt oxidation reaction is prevented even if it is exposed to oxygen during taking out, which is extremely effective for safety.

The oxygen concentration in the gas phase in the crusher during crushing is
The preferred range varies depending on the selection of the type of solvent and the type of nitride used, but it is necessary that 0 <O ₂ ≦ 5 vol%. It is preferably 0.001 <O ₂ ≦ 3 vol%. In this oxygen concentration range, the surface of the crushed nitride particles is covered with a stable thin oxide film, and thus fine particles having low cohesiveness can be obtained. Further, in the pulverization in an atmosphere not containing oxygen, the surface is pulverized and the surface becomes active, and the particles adhere to each other or to the wall surface, so that the pulverization progresses slowly. In addition, when taken out from the crusher, the surface is active, which causes rapid oxidation,
Not only the saturation magnetization and coercive force decrease, but it may also ignite. On the other hand, when the oxygen concentration is higher than 5 vol%, the active particle surface is likely to be rapidly oxidized and the magnetization is lowered. In addition, it may be in the explosive range of the organic solvent, which is difficult to implement for safety reasons.

The operating temperature range is not particularly limited, but it is generally performed at room temperature. In the present invention, the final fine pulverization is performed by the method of the present invention, and it is also possible to use other pulverization methods for practically obtaining a certain particle size. For example, since a jet mill has a very high pulverizing efficiency up to a particle size of about 5 μm, it is possible to pulverize with a jet mill to 5 to 10 μm first, and then wet pulverize with the method of the present invention.

[0018]

EXAMPLES Examples will be shown below, but the present invention is not limited thereto. For the measurement of magnetic properties, a vibrating sample magnetometer (VSM) [VSM-3 manufactured by Toei Industry Co., Ltd.] was used. The packing density of the molded body was determined by (molded body weight) / (volume of the rectangular parallelepiped measured by the length).

[0019]

Example 1 Sm _9.0 Fe _76.9 N having an average particle size of 45 μm
5 g of a raw material alloy of _13.6 H _0.1 O _0.4 was charged into a stainless steel ball mill having a diameter of 15 cm and 20% by volume of a stainless steel ball (3 mm diameter). Coupling agent (γ-aminopropyltriethoxysilane) into it 2
0 mg, 20 mg of a lubricant (oleylamine), and 150 ml of cyclohexane as an organic solvent were added to adjust the oxygen concentration in the gas phase portion of the system to 3 vol%, and the mixture was pulverized at 300 rpm for 6 hours. The average particle size of the obtained fine powder is 2.3 μm.
Met. This fine powder is applied to a magnetic field of 5 KOe by using a press at a pressure of 10 ton / cm ^{2 and} a pressure of 5 × 10 × 1 m.
When a sample of m was prepared and measured using a vibrating sample magnetometer (VSM), the coercive force was improved from 500 oe of the magnetic powder to 8500 oe, and the decrease of the saturation magnetization before and after pulverization was 4%. The packing density of the molded body at this time was 6.0 g / ml.

[0020]

Example 2 Sm _9.0 Fe _76.9 N having an average particle size of 45 μm
_13.6 H _0.1 O _0.4 raw material alloy 10 g was filled with 80% by volume of zircon beads, and a glass dyno mill (24
0 ml). Into it, the coupling agent (N-
β- (aminoethyl) -γ-aminopropyltrimethoxysilane) 35 mg, lubricant (ethylenebisstearic acid amide) 35 mg, isopropanol 1 as organic solvent
90 ml was added to adjust the oxygen concentration in the system to 0.05 vol%, and the mixture was pulverized at 2000 rpm for 15 minutes.

The average particle size of the resulting fine powder was 2.8 μm. This fine powder was molded in the same manner as in Example 1 and measured using a vibrating sample magnetometer (VSM).
It was improved from 500oe to 7000oe, and the decrease in saturation magnetization before and after pulverization was 3%. The packing density of the molded body at this time is 6.0.
It was g / ml.

[0022]

Example 3 Sm _9.0 Fe _76.9 N having an average particle size of 40 μm
5 g of a _13.6 H _0.1 O _0.4 raw material alloy was charged into a stainless steel ball mill having a diameter of 15 cm and 20% by volume of a stainless steel ball (3 mm diameter). Coupling agent (vinyltriethoxysilane) 20 mg, lubricant (paraffin wax) 20 mg, and cyclohexane 150 ml as an organic solvent were added therein to adjust the oxygen concentration in the gas phase portion of the system to 2 vol% and the rotation speed at 350 rpm for 8 hours. It was crushed. The average particle size of the obtained fine powder was 1.9 μm. When this fine powder was molded in the same manner as in Example 1 and measured using a vibrating sample magnetometer (VSM), the coercive force was 500o.
It increased from e to 10200oe and the decrease in saturation magnetization before and after pulverization was 4%. The packing density of the molded product at this time is 6.0 g.
/ Ml. When this molded body was left in an environment of 110 ° C., the coercive force decreased by about 3% after 2 hours.

[0023]

Example 4 Sm _9.0 Fe _73.1 Co having an average particle size of 45 μm
_3.8 N _13.6 H _0.1 O _0.4 raw material alloy 5g, diameter 15
It was filled in a stainless steel ball mill filled with 20 vol% of stainless steel ball (3 mm diameter) in cm. 20 mg of a coupling agent (isopropyltri (N-aminoethyl-aminoethyl) titanate), 20 mg of a lubricant (stearylamine), and 150 ml of cyclohexane as an organic solvent were added thereto, and the oxygen concentration in the gas phase part of the system was adjusted to 5 vol.
% And pulverized at a rotation speed of 300 rpm for 4 hours. The average particle size of the obtained fine powder was 2.5 μm. This fine powder was molded in the same manner as in Example 1, and a vibrating sample magnetometer (VS
M), the coercive force is from 500oe to 7500
oe was improved, and the decrease in saturation magnetization before and after pulverization was 4%. The packing density of the molded body at this time was 6.0 g / ml. When this molded body was left in an environment of 110 ° C., the coercive force decreased by about 3% after 2 hours.

[0024]

Example 5 Sm _9.0 Fe _69.2 Co having an average particle size of 50 μm
_7.7 kg of N _13.6 H _0.1 O _0.4 raw material alloy was filled in an attritor (Mitsui Miike: MAID type), and 10 g of a coupling agent (isopropyltriisostearoyl titanate) and a lubricant (oleylamine) 10 were charged therein.
g, and 1800 g of isopropanol as an organic solvent were added to adjust the oxygen concentration in the gas phase in the system to 0.5 vol%, and the mixture was pulverized at a rotation speed of 250 rpm for 8 hours. The average particle size of the obtained fine powder was 2.2 μm. When this fine powder was molded in the same manner as in Example 1 and measured using a vibrating sample magnetometer (VSM), the coercive force was improved from 500 oe to 9000 oe, and the decrease in saturation magnetization before and after pulverization was 4%. . The packing density of the molded body at this time was 6.0 g / ml.

[0025]

Example 6 The same raw material as in Example 1 was pulverized using a jet mill (Nippon Pneumatic, LJ type). The pressure of the supply gas was 8 kg / cm ² , the oxygen concentration was 0.1 vol%, and the supply amount of the magnetic powder was 500 g / H. The average particle size of the obtained fine powder was 7.0 μm. 2.8 kg of this magnetic powder is used as an attritor (Mitsui Miike: MAID type)
And 10 g of a coupling agent (γ-glycidpropyltrimethoxysilane), 10 g of a lubricant (ethylenebisstearic acid amide), and 1.8 liter of isopropanol as an organic solvent were added thereto, and the gas phase part in the system was filled. The oxygen concentration was adjusted to 0.1 vol% and pulverization was performed at a rotation speed of 200 rpm for 3 hours. The average particle size of the obtained fine powder was 2.4 μm. This fine powder was molded in the same manner as in Example 1 and measured using a vibrating sample magnetometer (VSM).
It increased from 500oe to 8000oe, and the decrease of the saturation magnetization before and after pulverization was 4%. The packing density of the molded body at this time is 6.0.
It was g / ml.

[0026]

[Example 7] 5 g of magnetic powder obtained by the jet mill of Example 6
A stainless steel ball with a diameter of 15 cm (3 mm diameter)
Was added to a stainless steel ball mill filled with 20 vol% of a coupling agent (β- (3,4-epoxy-cycloxyl) ethyltrimethoxysilane) 20 m therein.
g, 20 mg of a lubricant (oleylamine), and 150 ml of cyclohexane as an organic solvent were added to adjust the oxygen concentration in the gas phase part in the system to 3 vol%, and the mixture was pulverized at 250 rpm for 2 hours. The average particle size of the obtained fine powder was 2.8 μm. When this fine powder was molded in the same manner as in Example 1 and measured using a vibrating sample magnetometer (VSM), the coercive force was 50.
It increased from 0oe to 7200oe, and the decrease of the saturation magnetization before and after pulverization was 3%. The packing density of the molded product at this time is 6.0 g.
/ Ml.

[0027]

[Comparative Example 1] Sm _9.0 Fe _76.9 N having an average particle size of 40 μm
5 g of a _13.6 H _0.1 O _0.4 raw material alloy was charged into a stainless steel ball mill having a diameter of 15 cm and 20% by volume of a stainless steel ball (3 mm diameter). Cyclohexane (150 ml) was added as an organic solvent to adjust the oxygen concentration in the gas phase portion in the system to 2 vol%, and the mixture was pulverized at a rotation speed of 300 rpm for 4 hours. The average particle size of the obtained fine powder was 2.8 μm. When this fine powder was molded in the same manner as in Example 1 and measured using a vibrating sample magnetometer (VSM), the coercive force was 50.
Although it was improved from 0 oe to 6500 oe, the coercive force decreased by about 15% when the molded body was left in an environment of 110 ° C. for 2 hours.

[0028]

[Comparative Example 2] Sm _9.0 Fe _76.9 N having an average particle size of 40 μm
5 g of a _13.6 H _0.1 O _0.4 raw material alloy was charged into a stainless steel ball mill having a diameter of 15 cm and 20% by volume of a stainless steel ball (3 mm diameter). Cyclohexane (150 ml) was added as an organic solvent to adjust the oxygen concentration in the gas phase in the system to 0%, and the mixture was pulverized at a rotation speed of 300 rpm for 4 hours. The average particle size of the obtained fine powder was 3.6 μm. When this fine powder was molded in the same manner as in Example 1 and measured using a vibrating sample magnetometer (VSM), the coercive force was 500o.
Although it was improved from e to 5500oe, the coercive force decreased by about 20% when the molded body was left in an environment of 110 ° C for 2 hours.

[0029]

[Comparative Example 3] Sm _9.0 Fe _76.9 N having an average particle size of 40 μm
5 g of a _13.6 H _0.1 O _0.4 raw material alloy was charged into a stainless steel ball mill having a diameter of 15 cm and 20% by volume of a stainless steel ball (3 mm diameter). Coupling agent (γ-glycidpropyltrimethoxysilane) into it 2
0 mg, a lubricant (oleylamine) 20 mg, and cyclohexane 150 ml as an organic solvent were added to adjust the oxygen concentration in the gas phase portion of the system to 7.0 vol%, and the mixture was pulverized at 300 rpm for 4 hours. The average particle size of the obtained fine powder is 2.5.
was μm. When this fine powder was molded in the same manner as in Example 1 and measured using a vibrating sample magnetometer (VSM), the coercive force was improved from 500oe to 6000oe, but the decrease in saturation magnetization before and after grinding was 20%. It was

[0030]

EFFECTS OF THE INVENTION According to the manufacturing method of the present invention, a decrease in saturation magnetization can be reduced, a coercive force can be improved, a thermally stable magnetic powder can be supplied, and a packing density when the magnetic powder is formed into a bond magnet is improved. I can do things.

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Claims (1)

[Claims] 1. A method for producing a nitride magnetic powder in which a rare earth-iron-based nitride that is a magnet material is finely pulverized by using a wet pulverizer, and a coupling agent and / or a lubricant, C2 or more alcohols, C3 or more A process for producing a nitride magnetic powder, which comprises crushing in an atmosphere having an oxygen concentration of 0 <O ₂ ≤5 vol% using an organic solvent composed of at least one of ketones and C5 or higher hydrocarbons.