JPH01301803A - Fine powder for soft magnetic materials - Google Patents

Abstract

PURPOSE:To produce the fine metal powder which yields soft magnetic products having good magnetic characteristics by mechanically pulverizing metal lumps to form fine powder having single crystal grains and specific average grain sizes. CONSTITUTION:The metal lumps of magnetic alloy systems (Fe-Si, Fe-Al, Fe-Ni, etc.) are pulverized by using a mechanical pulverization method to form the fine metal powder having the single crystal grains or the sizes approximate to the sizes thereof and <=3mu average grain size. The crystal grains of this soft magnetic product are easily coarsened if the powder is molded in a magnetic field and the molding is sintered at about 1,100 to 1,400 deg.C. The max. magnetic permeability and magnetic flux of the sintered body are thereby increased and the soft magnetic parts having magnetic anisotropy are obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a powder raw material for sintering for producing soft magnetic parts.

(Prior Art) Many magnetic components are fabricated using a sintering method. Among these, soft magnetic components are mainly used as magnetic cores for inductors and transformers.

Most of the soft magnetic parts made by the sintering method are polycrystalline, and depending on the size, shape, and distribution of the crystal grains, the size, distribution, and position of the pores, and the nature of the grain boundaries, Domain wall movement is easily affected. Therefore, the magnetic properties of a magnetic component change with respect to the microstructure, and the powder properties of the raw material and the sintering technique are important factors in controlling this microstructure arbitrarily.

(Problem to be Solved by the Invention) However, soft magnetic parts manufactured by a sintering method using conventional powder for soft magnetic materials have micropores (
A large number of vacancies (vacancies) are easily formed, and the density is low (85-90%).
Met. Therefore, there is a problem in that the magnetic properties, particularly the maximum magnetic permeability, magnetic flux density, coercive force, etc., are relatively inferior to soft magnetic parts made of molten material.

The present invention was made to solve these problems, and it provides a fine powder for soft magnetic materials for manufacturing soft magnetic parts having magnetic properties such as high maximum magnetic permeability, high magnetic flux density, and low coercive force. The purpose is to provide

(Means for Solving the Problems) For this purpose, the fine powder for soft magnetic materials of the present invention is a fine metal powder obtained by crushing a metal lump by a mechanical crushing method to an average particle size such that the magnetic anisotropy cannot be ignored. It is characterized by being a fine metal powder having a single crystal grain or a size close to this and an average grain size of 3 μm or less.

The metal lump was ground into fine powder with an average particle size of 3 μm or less using the pirated grinding method.The reason is that the powder that is ground into fine powder with a single crystal grain has strong magnetic anisotropy. ,
This is because if an external magnetic field is applied to such powder, a magnetic material with strong magnetic anisotropy can be easily obtained.

1) It is more desirable that the metal fine powder is pulverized to have an average particle size of 2 μm or less. This is because when the particle size is small, the resulting fine powder has a magnetic domain tf4 structure that is closer to a single crystal grain, so that the powder compact is easily aligned in the axis of easy magnetization in a magnetic field.

Therefore, by imparting magnetic anisotropy and coarsening the crystal grains during high-temperature sintering after forming in a magnetic field, the magnetic properties can be significantly improved.

The alloy system of the metal fine powder is Fe-3i, Fe-Al,
A magnetic alloy system such as Fe-Ni, Fe-Aj2-5i, Fe-Go, etc. can be used.

(Function) When the fine powder for soft magnetic materials according to the present invention is molded in a magnetic field and the molded body is sintered at a high temperature, for example, +100-1400°C, the crystal grains tend to become coarse and the sintered body has a high maximum temperature. Soft magnetic parts with high magnetic permeability and high magnetic flux density and magnetic anisotropy can be obtained.

(Example) Examples of the present invention will be described.

The raw material of Fe-3Si alloy is crushed with an average particle size of 3 μm.
Grind into a fine powder. This fine powder is estimated to have a single crystal grain or a structure close to this.

This fine powder was mixed with 40% by volume of an organic binder, and the mixed powder was thoroughly kneaded. The obtained kneaded product was molded using an injection molding machine at a pressure of 50 to 70 kg/cm" and a magnetic field strength of 5.
Injection molding was performed in a magnetic field of 000 (Oe) to obtain an injection molded article. The compacted powder density of this molded body was measured and found to be 85% by volume.

Next, this molded body was sintered in a sintering furnace at a temperature of 1250° C. to obtain a product as a sintered body. When the sintered density of the obtained product was measured, it was 92% by volume.

The obtained sintered product has fewer pores (micropores) as described above and has a high density, so it is presumed that its magnetic properties will be high maximum permeability, low coercive force, etc.

When the maximum magnetic permeability and low coercive force of the sintered product were measured, they were 45.000 (Oe) and 0.I (Oe), respectively.

In this example, Fe-3Si alloy was used as the raw material.
The type of metal to which the present invention is applied may be any soft magnetic material, such as Fe, Fe-1~16S i, F
e-36~78N i, Fe-6~16 eight floods, Fe-2
0~50Co, Fc-9゜5AA-5,5Si, Fe-
Metals or alloys such as 13-25Cr can be used.

(Effects of the Invention) As explained below, when the powder for soft magnetic materials of the present invention is used, since the raw material powder is a fine powder with a single crystal grain or a structure similar to this, it is difficult to sinter at high temperatures. By coarsening the crystal grains, soft magnetic parts with magnetic anisotropy and good magnetic properties, that is, high maximum permeability, high magnetic flux density, and low coercive force, can be produced at low cost. There is an effect.

In addition, if the present invention is applied, it is not necessary to 1) refine the powder to a level with 1-crystal grains (i.e., to convert the fine powder of the 1-chi uniform diameter level, which has a structure close to the lit magnetic domain structure, into raw material powder). Therefore, soft magnetic parts with high maximum magnetic permeability, high magnetic flux density, and low coercive force can be manufactured at low cost by molding and high-temperature sintering in a magnetic field6.

Claims (1)

[Claims] (1) Fine powder for soft magnetic materials, characterized in that it is a single crystal grain obtained by crushing a metal lump by a mechanical crushing method, or a fine metal powder having an average particle size of 3 μm or less and having a size close to this single crystal grain.