JPS59229461A - Magnetic alloy powder for magnetic recording - Google Patents

Abstract

PURPOSE:To obtain easily and inexpensively titled powder having high coercive force and high satd. magnetization by forming a magnetic alloy consisting essentially of R (rare earth elements including Y), B and Fe into pulverous powder having a specific grain size. CONSTITUTION:Titled powder consists of an R-B-Fe magnetic alloy consisting essentially of 5-20atom% R (>=1 kind among rare earth elements including Y), 5-20atom% B and 60-90atom% Fe, consists of the compd. of tetragonal system contg. R, B and Fe as a main phase and has <=10mu grain size. Since such powder utilizes crystal magnetic anisotropy as a mechanism for developing coercive force, the powder is easily obtd. by grinding, etc. without the need for forming accular and ultrafine powder as in the prior art. The powder has excellent satd. magnetization and coercive force and the coercive force is adjustable freely within a certain range; moreover the powder has a high squareness ratio with the magnetization curve and is excellent for not only recording in a longitudinal direction but recording in a perpendicular direction as well.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording magnetic alloy powder having excellent magnetic properties, which mainly contains a rare earth metal (at least one rare earth element including Y), boron, and iron. The present invention relates to a magnetic alloy powder for magnetic recording.

As magnetic powder for magnetic recording, fine oxide powders such as acicular γ-Fe103, acicular Cr Op, and 6-coated acicular iron oxide are commonly used.

Furthermore, today, there is a strong demand for high output and high density in magnetic recording media, and magnetic powders having characteristics of high coercive force and high saturation magnetization have become necessary.

Examples of such magnetic powder include acicular iron fine particles obtained by reducing acicular iron oxide, and alloy fine powders mainly composed of Fe or Fe-G, which are made into ultrafine powder by evaporating metal into hundreds of particles. A proposal has been made and improvements and development are underway.

However, since the above-mentioned acicular iron fine particles utilize shape anisotropy as their coercive force generation mechanism, the acicular iron particle has an acicular ratio of 5.
Although the above-mentioned elongated fine particles are necessary, there is a problem that the acicularity is easily lost due to sintering in the reduction treatment process, etc.
In addition, reduction treatment, sintering, and oxidation prevention measures increase the cost, and there are various problems such as the coercive force being limited to about 15,000 e. Although it does not require a high degree of strength, it requires a large amount of cost in the evaporation process that involves hundreds of people to turn it into ultra-fine powder, so it is limited to special uses, and its coercive force is limited to about 25,000 e, which poses various problems.

Regarding saturation magnetization, Ba0 6Fe203 and 5rO-
Hard ferrite represented by 6Fe203 is known, but its saturation magnetization is low at 60 to 708 mu10.
RCo5 and R2O whose main components are rare earth metals and 6) +7
The intermetallic compound represented by is also known to have a high coercive force due to its high magnetocrystalline anisotropy, but since Sm and 6 are the main components, the raw material cost increases, and the saturation magnetization is also 80.
It was as low as ~958ml+/(].

The object of the present invention is to provide a novel magnetic recording magnetic powder that has high coercive force and high saturation magnetization, and which can provide such excellent magnetic properties easily and inexpensively.

That is, this invention provides R (R is at least one kind of rare earth elements including Y) 5 at.% to 20 at.%, B
Consisting of R-B-Fe-based magnetic alloy powder whose main components are 55 to 20 at% and Fe60 to 90 at%, R
, B, the main phase is a tetragonal compound containing Fe, and the particle size is 1
The present invention is a magnetic alloy powder for magnetic recording, characterized in that it is 0ρ or less.

Magnetic alloys containing R, B, and Fe as main components were developed by the present inventors (Japanese Patent Application No. 57-145072, Japanese Patent Application No. 57-i666).
No. 63, Japanese Patent Application No. 58-5813), it was discovered that it has excellent magnetic properties as a sintered permanent magnet.
As a result of various studies on the properties of such alloys as fine powder,
It was discovered that this material has excellent properties as a magnetic powder for magnetic recording.

The magnetic alloy powder for magnetic recording according to the present invention utilizes magnetocrystalline anisotropy as a mechanism for expressing coercive force, so it is easy to manufacture without the need for the conventional sword-like property or ultra-fine pulverization.
Excellent saturation magnetization (σS) and coercive force (+HC) can be obtained, and this coercive force also ranges from several thousand e to about 100,000 e.
It can be freely adjusted up to have characteristics.

Next, the reason for limiting the components and component composition will be explained.

The rare earth element R is a rare earth element that includes yttrium (Y), light rare earths, and heavy rare earths, and is mainly composed of at least one of these, preferably light rare earths such as Nd and pr, or Nd, Pr, etc. Use a mixture of

That is, as R, Neodymium (Nd>, Praseodymium (Pr).

Lanthanum (La), cerium (Ce).

Terbium (Tb), dysprosium (Dy).

Holmium (HO), erbium (Er).

europium (El), samarium (Sm).

Cadolinium (Gd), promethium (PI).

Thulium (Tllll), Ytterbium (Yb).

Included are lutetium (LIJ) and yttrium (Y).

As R, a light rare earth element is sufficient, especially Nd.

pr is preferred. Also, one type of R is usually sufficient, but in practice, a mixture of two or more types (Mitushmetal, dididim, etc.) can be used for reasons such as convenience of availability.
Sm, Y, La, Ce, Gd.

etc. can be used as a mixture with other R1, especially Nd, pr, etc. Note that this R does not have to be a pure rare earth element, and may contain impurities that are unavoidable in production within an industrially available range.

When R is less than 5 atomic %, a cubic crystal structure having the same structure as α iron exists, and a good coercive force is obtained.

Saturation magnetization cannot be obtained, and when R exceeds 20 at% and Fe becomes unvortexed at 60 at%, R-rich non-magnetic phase becomes too large, saturation magnetization decreases, and the magnetic powder for magnetic recording R is 5 atom% because it is not practical as
~20 atomic%.

When B becomes unvortexed by 5 at%, it becomes a rhombohedral structure, making it impossible to obtain good coercive force and saturation magnetization, and when it exceeds 20 at%, the saturation magnetization decreases.
Defined as atomic %.

When Fe is 60 atomic % ungrooved, the R-rich nonmagnetic phase becomes too large and the saturation magnetization becomes small, making it impractical as a magnetic recording magnetic powder. Since the magnetic force decreases and it is unsuitable as a magnetic material for magnetic recording, the content is set at 60 at % to 90 at %.

In order for the alloy powder 1 having the above composition to exhibit high magnetocrystalline anisotropy and high saturation magnetization, its structure must be as follows:
It is essential that the structure has a tetragonal compound containing R, [3, Fe as the main phase, and the remainder is a substantially R-rich nonmagnetic phase. Further, even if a small amount of oxide phase and B Lynch phase are present in this structure, good characteristics are exhibited.

In this invention, replacing a part of the main component Fa with 6 is effective in improving the temperature characteristics of the R-B-Fe alloy powder without impairing its magnetic properties.
If the amount of substitution exceeds 50% of Fe, the magnetic properties of the alloy powder will deteriorate, which is not preferable.

In addition, in the present invention, even if the alloy powder contains Co substitution, addition of the following elements, and impurity elements mixed in raw materials or manufacturing processes, it is a tetragonal compound containing R, B, and Fe, and is suitable for magnetic recording. Shows excellent properties as a magnetic powder.

TL 4.5% or less, NL 4.5% or less, BL
5% or less, ■ 9.5% or less, m 12.5%
Below, Ta 10.5% or less, Cr 8.5% or less, -9.5% or less, W 9.5% or less, 13.5% or less, M 9.5% or less, Sb 2.5% or less, Ce 7% Below, ST+ 3, 5% JJ lower, Zy 5,5
% or less, ■ 5.5% or less, Cu 3.5% or less, S
20. % or less, C4% or less, Ca 8% or less, -8% or less, SL 8% or less, P3.5% or less, and 1% or less, H, Li, Na, K, Be
, Sr.

Ba, AA, Zn, N, F, Se
, To , Pb.

The reason why the particle size of the alloy powder of this invention is limited to iolIm or less is that if the particle size exceeds 10 μm, it will cause damage to the magnetic head and noise when applied to a magnetic tape, etc., making it unsuitable as a magnetic powder for magnetic recording. This is because
The particle size is preferably 2 to 3 or less.

Further, although it is desirable that the oxygen content of the alloy powder is low, if it is 2% or less, the coercive force will not be significantly reduced.

Next, to explain the method for producing magnetic alloy powder for magnetic recording according to the present invention, generally, an ingot is produced by vacuum melting, and the ingot is mechanically crushed to obtain a fine powder of several ρ or less. However, if it is pulverized in the presence of hydrogen, it can be pulverized more easily. It is also possible to make powder by atomization method, which involves spraying molten metal, by reducing oxides, by evaporation by arc discharge or high-temperature heating, by scattering, and by chemical electrolysis. It may also be powdered by reduction.

Powders with various levels of properties can be obtained by adjusting the particle size of the powder or changing the hydrogen content using the various manufacturing methods described above.

Furthermore, when applying the alloy powder according to the present invention to a recording medium as a magnetic powder for magnetic recording, it is important to stabilize the surface of the alloy powder. For example, by depositing an oxide film on the surface of the powder particles, Covering the surface with inorganic or organic matter,
Alternatively, a method of creating a surface treatment layer can be applied, especially when pulverized with hydrogen at 200°C to 300°C.
It is effective to perform the above-mentioned surface treatment after heat treatment.

Examples according to the present invention will be shown below to clarify its effects.

Example 1 Using pure iron, metal 11&l, and Fe-B alloy (820%) as raw materials, 1Vk110 at%-813 at%-Fe77
The ingot is blended to have an atomic percent composition and cast in a vacuum and argon atmosphere using a show crusher.

Coarsely grind with a disc mill, and then grind with a ball mill to 5 to 20
Fine pulverization was carried out by varying the 0 hour and pulverization times.

The average particle size and magnetic properties of the obtained alloy powder were measured, and the results shown in Table 1 were obtained. Moreover, the hydrogen content of the powder with an average particle size of 3 was 3000 pm or less when the grinding time was 5 hours.

Example 2 Ingot made of pure iron, metal 11&l, and Fa-B alloy (820%) as raw materials, blended to have a composition of 1Vk113 at% - B8 at% - Fe79 at%, and cast in vacuum and argon atmosphere. was held in hydrogen at 15 atm for 5 hours, hydrogen was further removed in vacuum for 20 hours, and then coarsely pulverized using a show crusher and a disk mill, and further pulverized for various average particle sizes using a ball mill. It was finely ground. When the average particle size and magnetic properties of the obtained alloy powder were measured, the results shown in Table 2 were obtained. In addition, the hydrogen content of the powder with an average particle size of 3ρ was 1500 ppm or less when the grinding time was 5 hours.

Example 3 Using pure iron, metal oxide, and Fe-8 alloy (B20%) as raw materials, various additives were added, the compositions were blended to have the composition shown in Table 3, and cast in a vacuum and argon atmosphere. Show crusher for ingots.

The mixture was coarsely ground using a disk mill and further finely ground using a ball mill for 5 hours. When the average particle size and magnetic properties of the obtained alloy powder were measured, the results shown in Table 3 were obtained.

Example 4 Using pure iron, metal oxide, and Fe-8 alloy (820%) as raw materials
Then, Nd18 atomic%-B6 atomic%-Fθ76
The composition was blended to have a composition of atomic%, melted in vacuum and argon atmosphere, the molten metal was dropped from a 3 mm diameter nozzle, and atomized with argon gas at 100 atm. The obtained alloy powder was further micromilled in a ball mill for 150 hours. Shattered.

In addition, this fine powder was heat-treated in a vacuum at ix 10-3 mmH () for 30 minutes at 600°C, and at a dew point of 20°C.
A heat treatment was performed at 600° C. for 30 minutes in tN2 to obtain a surface-treated alloy powder. When the magnetic properties of the two types of powders obtained were measured, the results shown in Table 4 were obtained.

As is clear from the results, the alloy powder without surface treatment also showed a higher holding power than the conventional powder, and the surface-treated powder had a significantly improved holding power (if-1c) of 1iooo.

Margin below -13--274- -i’t--

Claims (1)

[Claims] IR (R is at least one rare earth element including Y
species) 5 atom% to 20 atom%, B5 atom% to 20 atom%,
R-B-F whose main component is Fe 60 atomic % to 90 atomic %
1. A magnetic alloy powder for magnetic recording, comprising an e-based magnetic alloy powder, having a main phase of a tetragonal compound containing R9B and Fe, and having a particle size of 10ρ or less.