JP3108945B2 - Method for producing shape anisotropic alloy powder - Google Patents

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 a shape anisotropic alloy powder, and more particularly to an improvement in mechanical properties of a shape anisotropic alloy powder containing Fe and Si as main components. It is.

[0002]

2. Description of the Related Art Conventionally, Fe which is inexpensive and has high magnetizability is used.
Is regarded as the most important substance as a magnetic material. It is generally known that alloys containing Fe and Si as main components exhibit soft magnetism that is easy to magnetize, and these soft magnetic alloys containing Fe and Si as main components are usually used in blocks or plates. Is done.

However, in recent years, the use of these alloys in powder form has been utilized in fields such as molding and coating since their shapes can be freely selected. However, in the powder form, the proportion of the metal occupied by the powder is generally small, and the amount of magnetization per unit volume tends to be small. In addition, it is known that the influence of the demagnetizing field increases with the granulation, and the magnetization characteristics tend to decrease.

[0004] In order to alleviate the drawbacks caused by powdering, there has been proposed a method of imparting shape anisotropy to an alloy powder to facilitate magnetization only in a specific direction. These shape anisotropic soft magnetic alloy powders are generally manufactured by a mechanical pulverization method such as a ball mill or an attritor. It is said that the effect will be greater.

[0005]

Incidentally, such a shape-anisotropic soft magnetic alloy powder has a tendency that the strength decreases as the thickness of the powder particles decreases. When molding or coating is performed using such an alloy powder having reduced strength, fracture is often caused by an external force applied to the powder particles. Therefore, finer particles are promoted and Hc (coercive force) increases. And the effect of the demagnetizing field increases, and the magnetic properties of the obtained alloy powder are significantly impaired.

[0006] In view of such circumstances, an object of the present invention is to improve the mechanical strength of a shape anisotropic alloy powder containing Fe and Si as main components.

[0007]

Therefore, in the present invention, the particle surfaces of an alloy powder having a shape anisotropy imparted by a mechanical pulverization method and a shape anisotropic soft magnetic alloy powder containing Si as a main component are used. It is characterized by being coated with Si.

[0008]

The diffusion film of Si formed on the surface of the alloy powder particles exerts a large adhesive force and envelops the alloy powder.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the surface of the alloy powder particles is made of Si.
When coating with Si, a treatment solution adjusted to contain 0.5 to 5.0% by weight of Si is heated and melted within a temperature range of 800 to 1000 ° C., and is mechanically placed in this heat bath as described above. Fe and Si given shape anisotropy by the pulverization method
Is immersed. Then, thermal decomposition and substitution reaction occur, and a diffusion film of Si is formed on the surface of the alloy powder particles. This coating envelopes the alloy powder particles with a uniform and strong adhesive force, and greatly contributes to improving the mechanical strength of the alloy powder.

The basic bath of the above-mentioned processing solution is NaCl-
It is desirable to use KCl and NaCl-KCl-NaFe, but it is not limited to this, and any neutral salt that promotes coating with Si may be used.

In the treatment liquid of the present invention, the content of Si is preferably 0.5% by weight or more. Below these lower limits, the Si powder uniformly and closely adhered to the surface of the alloy powder particles
This is because no coating film is formed and no improvement in the strength of the alloy powder particles is observed.

Further, in the treatment liquid of the present invention, the content of Si is preferably set to 5.0% by weight or less. If the content is more than this, the Si coating film on the surface of the alloy powder particles is apt to peel off, the adhesion becomes weak, and the improvement of the strength of the alloy powder particles becomes insufficient.

Further, in the processing solution of the present invention, it is preferable to keep the temperature at 1000 ° C. or lower. In a temperature range exceeding this upper limit, the diffusion of Fe into Si tends to progress remarkably, resulting in a bad influence on the magnetic properties of the alloy powder.

Specific Example 1 Using Fe and Si having a purity of 99.8% or more, 10% by weight of Si was removed by high-frequency heating in an argon atmosphere.
An ingot having a thickness of about 20 mm was prepared with the composition of e. Next, the ingot was roughly crushed to 150 μm or less by a jaw crush lure and a roll crusher.
These coarsely crushed pieces were pulverized by a wet attritor using a stainless steel ball and ethanol, and the average diameter was about 40 μm.
An alloy powder composed of plate-like particles having a thickness of about 0.5 μm and a thickness of about 0.5 μm was obtained. Next, Si was converted to NaCl-KCl and NaCl-
It is mixed with a KCl-NaF solution, and the mixed amount of Si is 0.3, 0.5, 1.0, 3.0, 5.0 and 1 in terms of% by weight.
A processing solution was prepared so as to be 0.0. Each processing solution was put into a stainless steel crucible, and 200, 800, 900,
Melted at 1000 and 1100 ° C. Thereafter, the above-mentioned alloy powder was put into each heat bath and left for 3 hours. Then, the heat bath was cooled to room temperature, and the alloy powder was taken out. The extracted alloy powder was heated and dried at 100 ° C. for 30 minutes. Next, using these alloy powders, 1 kg of glass beads having a diameter of 1 mm, 1 liter of ethanol and 100 g of the alloy powder were put into a rotating ball mill pot having an inner diameter of 15 mm and a volume of 2.5 l, and subjected to 1 HR treatment at 1500 rpm. The shape of the powder particles in Japanese is measured by a scanning electron microscope (SE
M). Table 1 shows the results.

[0015]

[Table 1]

In Table 1, the symbol 示 し indicates that no breakage of the powder particles was confirmed, the mark Δ indicates the state where the breakage of the powder particles was slightly confirmed, and the cross mark indicates that the breakage of the powder particles was significantly confirmed. It shows a state in which A in the table indicates N as a processing solution.
aCl-KCl-Si solution is used, B is NaCl-
The case where a KCl-NaF-Si-based solution is used is shown.

From these results, it was found that 0.5 to 0.5% with respect to the basic bath.
Adjust to mix 5.0 wt% Si and 800
It can be seen that strong alloy powder particles can be produced by using a surface treatment liquid that has been melted at a temperature of at least ℃.

Concrete Example 2 NaCl-KCl and NaCl having a mixing amount of 0.5% and 5.0% by weight of Si obtained in Concrete Example 1
-KCl-NaF-Si solution 800, 900, 100
After mixing 2% by weight of epoxy resin for each of a total of 17 kinds of alloy powder treated and untreated alloy powder in a heat bath melted at 0 and 1100 ° C., a pressure of about 500 kg / cm 2 was measured using a mold. In one direction to obtain a cubic green compact of about 13 mm. In the powder particles of these compacts, the surfaces of the disk-shaped particles were oriented so as to be orthogonal to the compression direction. Next, the magnetic properties were measured such that the direction of the plate surface of each of the compact particles became the magnetization direction.

FIG. 1 shows the measurement results. 4πIs in the figure
Is a value obtained by converting the space factor of the powder to 100%. Also, the solid line (indicated by a circle) in FIG.
The alloy powder obtained by treating a Cl—KCl—Si solution at 800 to 1100 ° C. in a heat bath is shown.
NaCl-KCl-Si containing 5.0% by weight of Si
The alloy powder obtained by treating the solution in a heat bath melted at 800 to 1100 ° C. is indicated by a dashed line (▽) and a two-dot chain line (□)
Mark) is a mixture of 0.5 and 5.0% by weight of NaCl.
3 shows an alloy powder obtained by treating a KCl—Si solution at 800 to 1100 ° C. in a heat bath. In addition, the mark ● indicates an untreated alloy powder.

From this figure, it can be seen that the heating and melting temperature of the processing solution is 1
It can be seen that when the temperature exceeds 000 ° C., 4πIs starts to decrease sharply, and the magnetic characteristics tend to deteriorate rather. This is because the diffusion of Si into the alloy powder has progressed.

[0021]

According to the present invention, since the powder particles become strong without impairing the magnetic properties of the Fe-Si based shape anisotropic alloy powder, the mechanical strength of the alloy powder is improved.

[Brief description of the drawings]

FIG. 1 is a graph showing measurement results of a specific example 2.

Claims (4)

(57) [Claims] 1. The method of claim 1, wherein the surface of the alloy powder having shape anisotropy imparted by mechanical pulverization and the surface of the shape anisotropic soft magnetic alloy powder containing Si as a main component are coated with Si. Method for producing isotropic alloy powder. 2. The method according to claim 1, wherein the coating is performed with 0.5 to 0.5% Si.
The method according to claim 1, wherein the shape-anisotropic soft magnetic alloy powder is immersed in a treatment solution adjusted to contain 5.0% by weight. 3. The method according to claim 1, wherein the treatment liquid is 800 to 1000 during immersion.
3. The method according to claim 2, wherein the temperature is kept in a temperature range of ° C. 4. A process according to claim 1, wherein said treatment solution has a basic bath of NaCl-
3. The method according to claim 2, wherein KCl and NaCl-KCl-NaF are used.