JPH01298101A - Method for annealing metal powder for magnetic shield - Google Patents

Abstract

PURPOSE:To manufacture metal powder having excellent magnetic shield characteristic without mutually sintering metal powders to each other by mixing the specific heat resistant oxide powder and annealing at the time of annealing flaky powder for magnetic shield of 'Permalloy(R)', etc. CONSTITUTION:In order to display the magnetic shield effect by mixing ink, paint, etc., a material, which is made flaky with a stirring mill to water- atomizing powder of Fe-Ni series alloy, such as 'Permalloy(R)', composing of 35-80wt.% Ni and further if necessary, <=5wt.% one or more kinds among W, Mo, Cu, Cr and Nb and the balance Fe, is used. As the magnetic shield effect is lowered by developing internal strain in the powder at the time of process of pulverizing and flaking, Al2O3, SiO2, ZrO2, TiO2 and MgO as the heat resistant oxide having fine powdery state at <=0.3mu particle size, are sufficiently mixed at 0.1-10wt.% to the metal powder and annealed at 450-850 deg.C. The flaky Fe-Ni series alloy powder is removed the internal strain with the annealing without any sintering and the flaky metal powder having excellent magnetic shield effect is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of annealing a scale-like metal powder for magnetic shielding that is mixed and applied to ink, paint, etc.

[Conventional technology]

In general, it is known to produce flaky metal powder for magnetic shielding by forming water atomized alloy powder into flakes using a stirring mill.

[Problem to be solved by the invention]

However, even if the scaly metal powder produced by the above production method has an appropriate particle size and shape, it has internal strain during crushing or flaking, and its magnetic shielding properties as a magnetic shielding metal powder are extremely low. .

This can be improved by annealing, but there is a problem in that annealing causes the metal powders to sinter with each other.

[Means to solve the problem]

Therefore, the present inventors conducted research to solve this problem, and as a result, wet-processed a small amount of extremely fine heat-resistant oxide powder into the pulverized scaly metal powder for magnetic shielding. They have found that when mixed, dried, and then annealed, the scaly powders do not sinter together during the annealing.

The invention was made based on this knowledge, and in weight% (hereinafter % indicates weight%) NI: 35 ~
Contains 80%17, and further contains W, Mo, Cu as necessary
An alloy containing one or more of the following: 5% or less of Nb, Cr, and Nb, with the remainder consisting of FC and unavoidable impurities (this alloy is generally known as permalloy, but In the method of annealing a magnetic shielding scale-like metal powder made of a Fe-Ni alloy (hereinafter referred to as Fe-Ni alloy), the magnetic shielding scale-like metal powder has an average particle size of 0.3-
This method is characterized by an annealing method for magnetic shielding metal powder, in which 0.1 to 10% of the following heat-resistant oxide powders are wet-mixed, dried, and then annealed at a temperature of 450 to 850°C.

Specifically, the heat-resistant oxide powders include clay powder, alumina powder, silica powder, and ZrO2 powder.

The above-mentioned Fe-
Any oxide powder that does not react with the Ni-based alloy may be used.

The blending amount of the heat-resistant oxide powder is preferably 0.1 to 10%; if it is less than 0.1%, there is no effect of preventing sintering between the flaky metal powders for magnetic shielding; on the other hand, if it is blended in excess of 10%, This is not preferable because it reduces the magnetic shielding effect.

Even if the above-mentioned magnetic shielding metal powder contains 0.1 to 10% of the above-mentioned heat-resistant oxide powder with an average particle size of 0.3 mm or less, the magnetic shielding metal used by mixing with ink 2 paint etc. There is no problem in using it as a powder.

The heat-resistant oxide powder with an average particle size of 0.3 urn or less can be uniformly dispersed on the surface of the metal powder by wet mixing with water or an organic solvent, and the heat-resistant oxide powder on the surface can be dispersed uniformly on the surface of the metal powder. The metal powder in which the material powder is dispersed is annealed a
Even at extremely high temperatures, sintering of the powders does not occur.

When the average particle size of the heat-resistant oxide exceeds O or Sm, it becomes difficult to uniformly disperse the heat-resistant oxide powder on the surface of the metal powder, and as a result, in order to prevent sintering,
This is not suitable because it requires adding a large amount of oxide exceeding 0%.

The heat-resistant oxide powder is suspended in water or an organic solvent, mixed with the flaky metal powder made of the Fc-Ni alloy, and dried to be uniformly dispersed on the surface of the flaky metal powder, and then annealed. However, the above Fe-N
The annealing temperature of the scaly metal powder made of i-based alloy is 450°C.
On the other hand, if the temperature exceeds 850°C, sintering of the powders will occur even if heat-resistant oxides are dispersed. :Need to be annealed at 450-850°C.

〔Example〕

Next, the present invention will be specifically explained based on examples.

Fe-Ni alloy flake powder was prepared by making water atomized powder with the composition shown in Table 1 into flakes using a stirring mill, and the coercive force of these flake powders was measured, and the coercive force before annealing was It is shown in Table 1.

On the other hand, heat-resistant oxide powder having the particle size shown in Table 1 is suspended in a wet mixed liquid in the amount shown in Table 1, wet mixed with the scale-like powder of the Fc-Ni alloy, and dried. The heat-resistant oxide powder is dispersed and adhered to the surface of the scale-like powder of the Fe-Ni alloy by
A scaly powder of an e-Ni alloy was held at the temperature shown in Table 1 for 1 hour to obtain a sintered ML. The presence or absence of sintering of the flaky powder after the annealing was examined, and the coercive force of the flaky powder after the annealing was measured and is shown in Table 1. The * mark in the comparative example in Table 1 above indicates a value outside the range of the present invention.

〔Effect of the invention〕

After water atomization, the powder is made into flakes using a stirring mill.
Although it is an excellent metal powder for magnetic shielding, by annealing the above-mentioned scaly metal powder, the internal strain is removed and the coercive force is reduced as shown in Table 1, resulting in an excellent magnetic shielding layer. A scaly metal powder having characteristics can be obtained.

Applicant: 2 Nippon Telegraph and Telephone Corporation (2 others)

Claims (5)

[Claims] (1) In the method of annealing the scaly metal powder for magnetic shielding, the average particle size of the scaly metal powder for magnetic shielding is 0.3.
A method for annealing scale-like metal powder for magnetic shielding, characterized by wet mixing heat-resistant oxide powder of μ or less and then annealing. (2) In the above annealing method, the magnetic shielding scaly metal powder contains 35 to 80% by weight of Ni, and if necessary, one or two of W, Mo, Cu, Cr, and Nb. The annealing method according to claim 1, wherein the magnetic shielding scale-like metal powder has a composition of: 5% by weight or less, and the remainder: Fc and unavoidable impurities. (3) In the above annealing method, the heat-resistant oxide powder is clay powder, alumina powder, silica powder, ZrO powder, TiO
Claim 1 characterized in that the powder is MgO powder.
Annealing method as described. (4) The annealing method according to claim 1, wherein in the annealing method, 0.1 to 10% by weight of heat-resistant metal oxide powder is used in the magnetic shielding scaly metal powder. (5) In the above annealing method, a mixture of magnetic shielding scale-like metal powder and heat-resistant metal oxide powder is heated at a temperature of 450 to 85.
The annealing method according to claim 1, characterized in that the annealing is performed at 0°C.